A novel class of Pseudoautosomal region 1 deletions downstream of SHOX is associated with Leri-Weill dyschondrosteosis.,0
"Leri-Weill dyschondrosteosis (LWD) is a pseudoautosomal dominant disorder characterized by disproportionate short stature and a characteristic curving of the radius, known as the ""Madelung deformity."" SHOX mutations resulting in SHOX haploinsufficiency have been found in LWD and in a variable proportion of patients with idiopathic short stature (ISS), whereas homozygous loss of SHOX results in the more severe Langer mesomelic dysplasia (LMD). Defects in SHOX have been identified in approximately 60% of LWD cases, whereas, in the remaining approximately 40%, the molecular basis is unknown. This suggests either genetic heterogeneity or the presence of mutations in unanalyzed regions of SHOX, such as the upstream, intragenic, or downstream regulatory sequences. Therefore, the pseudoautosomal region 1 (PAR1) of 80 patients with LWD, in whom SHOX deletions and mutations had been excluded, was screened for deletions by use of a new panel of microsatellite markers. We identified 12 patients with LWD who presented with a novel class of PAR1 deletions that did not include SHOX. The deletions were of variable size and mapped at least approximately 30-530 kb downstream of SHOX. In our cohort, this type of deletion accounted for 15% of cases. In all cases, the deletions cosegregated with the phenotype. No apparent phenotypic differences were observed between patients with SHOX deletions and those with this new class of PAR1 deletions. Thus, we present here the identification of a second PAR1 region implicated in the etiopathogenesis of LWD. Our findings suggest the presence of distal regulatory elements of SHOX transcription in PAR1 or, alternatively, the existence of an additional locus apparently involved in the control of skeletal development. Deletion analysis of this newly identified region should be included in the mutation screening of patients with LWD, LMD, and ISS.",1
"Benito-Sanz, Sara, Thomas, N Simon, Huber, Céline, Huber, Celine, Gorbenko del Blanco, Darya, Del Blanco, Darya Gorbenko, Aza-Carmona, Miriam, Crolla, John A, Maloney, Vivienne, Rappold, Gudrun, Argente, Jesús, Argente, Jesus, Campos-Barros, Angel, Cormier-Daire, Valérie, Cormier-Daire, Valerie, Heath, Karen E",2
Assessment of the effect of age at onset on linkage to bipolar disorder: evidence on chromosomes 18p and 21q.,0
"Previous evidence suggests that the inheritance of bipolar disorder (BP) may vary depending on the age at onset (AAO). Therefore, we sought to incorporate AAO as a covariate in linkage analyses of BP using two different methods, LODPAL and ordered-subset analysis (OSA), in genomewide scans of 150 multiplex pedigrees with 874 individuals. The LODPAL analysis identified two loci, on chromosomes 21q22.13 (LOD = 3.29; empirical chromosomewide P value = .009) and 18p11.2 (LOD = 2.83; empirical chromosomewide P = .05), with increased linkage among subjects who had early onset (AAO < or = 21 years) and later onset (AAO >21 years), respectively. The finding on 21q22.13 was significant at the chromosomewide level, even after correction for multiple testing. Moreover, a similar finding was observed in an independent sample of 65 pedigrees (LOD = 2.88; empirical chromosomewide P = .025). The finding on 18p11.2 was only nominally significant and was not observed in the independent sample. However, 18p11.2 emerged as one of the strongest regions in the OSA (LOD = 2.92; empirical P = .001), in which it was the only finding to meet chromosomewide levels of significance after correction for multiple testing. These results suggest that 21q22.13 and 18p11.2 may harbor genes that increase the risks for early-onset and later-onset forms of BP, respectively. There have been previous reports of linkage on 21q22.13 and 18p11.2, but the findings have not been consistent. This inconsistency may be due to differences in the AAO characteristics of the samples examined. Future studies to fine map susceptibility genes for BP on chromosomes 21q22.13 and 18p11.2 should take AAO into account.",1
"Lin, Ping-I, McInnis, Melvin G, Potash, James B, Willour, Virginia L, Mackinnon, Dean F, Miao, Kuangyi, Depaulo, J Raymond, Zandi, Peter P",2
Meiotic synapsis proceeds from a limited number of subtelomeric sites in the human male.,0
"The formation of the synaptonemal complex (SC) is a crucial early step in the meiotic process, but relatively little is known about the establishment of the human SC. Accordingly, we recently initiated a study of synapsis in the human male, combining immunofluorescence and fluorescence in situ hybridization methodologies to analyze prophase spermatocytes from a series of control individuals. Our results indicate that synapsis is a tightly regulated process, with relatively little variation among individuals. On nonacrocentric chromosomes, there are two synaptic initiation sites, one on the distal short arm and one on the distal long arm, whereas acrocentric chromosomes exhibit a single site on the distal long arm. For both types of chromosomes, synapsis then proceeds toward the centromere, with little evidence that specific p- or q-arm sequences affect the process. However, the centromere appears to have an inhibitory effect on synapsis--that is, when one arm of a nonacrocentric chromosome is ""zippered up"" before the other, the centromere acts as a barrier to further movement from that arm.",1
"Brown, Petrice W, Judis, Luann, Chan, E Ricky, Schwartz, Stuart, Seftel, Allen, Thomas, Anthony, Hassold, Terry J",2
PTPN22 genetic variation: evidence for multiple variants associated with rheumatoid arthritis.,0
"The minor allele of the R620W missense single-nucleotide polymorphism (SNP) (rs2476601) in the hematopoietic-specific protein tyrosine phosphatase gene, PTPN22, has been associated with multiple autoimmune diseases, including rheumatoid arthritis (RA). These genetic data, combined with biochemical evidence that this SNP affects PTPN22 function, suggest that this phosphatase is a key regulator of autoimmunity. To determine whether other genetic variants in PTPN22 contribute to the development of RA, we sequenced the coding regions of this gene in 48 white North American patients with RA and identified 15 previously unreported SNPs, including 2 coding SNPs in the catalytic domain. We then genotyped 37 SNPs in or near PTPN22 in 475 patients with RA and 475 individually matched controls (sample set 1) and selected a subset of markers for replication in an additional 661 patients with RA and 1,322 individually matched controls (sample set 2). Analyses of these results predict 10 common (frequency >1%) PTPN22 haplotypes in white North Americans. The sole haplotype found to carry the previously identified W620 risk allele was strongly associated with disease in both sample sets, whereas another haplotype, identical at all other SNPs but carrying the R620 allele, showed no association. R620W, however, does not fully explain the association between PTPN22 and RA, since significant differences between cases and controls persisted in both sample sets after the haplotype data were stratified by R620W. Additional analyses identified two SNPs on a single common haplotype that are associated with RA independent of R620W, suggesting that R620W and at least one additional variant in the PTPN22 gene region influence RA susceptibility.",1
"Carlton, Victoria E H, Hu, Xiaolan, Chokkalingam, Anand P, Schrodi, Steven J, Brandon, Rhonda, Alexander, Heather C, Chang, Monica, Catanese, Joseph J, Leong, Diane U, Ardlie, Kristin G, Kastner, Daniel L, Seldin, Michael F, Criswell, Lindsey A, Gregersen, Peter K, Beasley, Ellen, Thomson, Glenys, Amos, Christopher I, Begovich, Ann B",2
Diagnostic genome profiling in mental retardation.,0
"Mental retardation (MR) occurs in 2%-3% of the general population. Conventional karyotyping has a resolution of 5-10 million bases and detects chromosomal alterations in approximately 5% of individuals with unexplained MR. The frequency of smaller submicroscopic chromosomal alterations in these patients is unknown. Novel molecular karyotyping methods, such as array-based comparative genomic hybridization (array CGH), can detect submicroscopic chromosome alterations at a resolution of 100 kb. In this study, 100 patients with unexplained MR were analyzed using array CGH for DNA copy-number changes by use of a novel tiling-resolution genomewide microarray containing 32,447 bacterial artificial clones. Alterations were validated by fluorescence in situ hybridization and/or multiplex ligation-dependent probe amplification, and parents were tested to determine de novo occurrence. Reproducible DNA copy-number changes were present in 97% of patients. The majority of these alterations were inherited from phenotypically normal parents, which reflects normal large-scale copy-number variation. In 10% of the patients, de novo alterations considered to be clinically relevant were found: seven deletions and three duplications. These alterations varied in size from 540 kb to 12 Mb and were scattered throughout the genome. Our results indicate that the diagnostic yield of this approach in the general population of patients with MR is at least twice as high as that of standard GTG-banded karyotyping.",1
"de Vries, Bert B A, Pfundt, Rolph, Leisink, Martijn, Koolen, David A, Vissers, Lisenka E L M, Janssen, Irene M, Reijmersdal, Simon van, Nillesen, Willy M, Huys, Erik H L P G, Leeuw, Nicole de, Smeets, Dominique, Sistermans, Erik A, Feuth, Ton, van Ravenswaaij-Arts, Conny M A, van Kessel, Ad Geurts, Schoenmakers, Eric F P M, Brunner, Han G, Veltman, Joris A",2
A variant in XPNPEP2 is associated with angioedema induced by angiotensin I-converting enzyme inhibitors.,0
"Angiotensin I-converting enzyme inhibitors (ACEi), which are used to treat common cardiovascular diseases, are associated with a potentially life-threatening adverse reaction known as angioedema (AE-ACEi). We have previously documented a significant association between AE-ACEi and low plasma aminopeptidase P (APP) activity. With eight large pedigrees, we hereby demonstrate that this quantitative trait is partially regulated by genetic factors. We tested APP activity using a variance-component QTL analysis of a 10-cM genomewide microsatellite scan enriched with seven markers over two candidate regions. We found significant linkage (LOD = 3.75) to a locus that includes the XPNPEP2 candidate gene encoding membrane-bound APP. Mutation screening of this QTL identified a large coding deletion segregating in one pedigree and an upstream single-nucleotide polymorphism (C-2399A SNP), which segregates in the remaining seven pedigrees. Measured genotype analysis strongly suggests that the linkage signal for APP activity at this locus is accounted for predominantly by the SNP association. In a separate case-control study (20 cases and 60 controls), we found significant association of this SNP to ACEi-induced AE (P=.0364). In conclusion, our findings provide supporting evidence that the C-2399A variant in XPNPEP2 is associated with reduced APP activity and a higher incidence of AE-ACEi.",1
"Duan, Qing Ling, Nikpoor, Borzoo, Dube, Marie-Pierre, Molinaro, Giuseppe, Meijer, Inge A, Dion, Patrick, Rochefort, Daniel, Saint-Onge, Judith, Flury, Leah, Brown, Nancy J, Gainer, James V, Rouleau, Jean L, Agostoni, Angelo, Cugno, Massimo, Simon, Pierre, Clavel, Pierre, Potier, Jacky, Wehbe, Bassem, Benarbia, Seddik, Marc-Aurele, Julien, Chanard, Jacques, Foroud, Tatiana, Adam, Albert, Rouleau, Guy A",2
"The beta -globin recombinational hotspot reduces the effects of strong selection around HbC, a recently arisen mutation providing resistance to malaria.",0
"Recombination is expected to reduce the effect of selection on the extent of linkage disequilibrium (LD), but the impact that recombinational hotspots have on sites linked to selected mutations has not been investigated. We empirically determine chromosomal linkage phase for 5.2 kb spanning the beta -globin gene and hotspot. We estimate that the HbC mutation, which is positively selected because of malaria, originated <5,000 years ago and that selection coefficients are 0.04-0.09. Despite strong selection and the recent origin of the HbC allele, recombination (crossing-over or gene conversion) is observed within 1 kb 5' of the selected site on more than one-third of the HbC chromosomes sampled. The rapid decay in LD upstream of the HbC allele demonstrates the large effect the ss-globin hotspot has in mitigating the effects of positive selection on linked variation.",1
"Wood, Elizabeth T, Stover, Daryn A, Slatkin, Montgomery, Nachman, Michael W, Hammer, Michael F",2
Linkage and association studies identify a novel locus for Alzheimer disease at 7q36 in a Dutch population-based sample.,0
"We obtained conclusive linkage of Alzheimer disease (AD) with a candidate region of 19.7 cM at 7q36 in an extended multiplex family, family 1270, ascertained in a population-based study of early-onset AD in the northern Netherlands. Single-nucleotide polymorphism and haplotype association analyses of a Dutch patient-control sample further supported the linkage at 7q36. In addition, we identified a shared haplotype at 7q36 between family 1270 and three of six multiplex AD-affected families from the same geographical region, which is indicative of a founder effect and defines a priority region of 9.3 cM. Mutation analysis of coding exons of 29 candidate genes identified one linked synonymous mutation, g.38030G-->C in exon 10, that affected codon 626 of the PAX transactivation domain interacting protein gene (PAXIP1). It remains to be determined whether PAXIP1 has a functional role in the expression of AD in family 1270 or whether another mutation at this locus explains the observed linkage and sharing. Together, our linkage data from the informative family 1270 and the association data in the population-based early-onset AD patient-control sample strongly support the identification of a novel AD locus at 7q36 and re-emphasize the genetic heterogeneity of AD.",1
"Rademakers, Rosa, Cruts, Marc, Sleegers, Kristel, Dermaut, Bart, Theuns, Jessie, Aulchenko, Yurii, Weckx, Stefan, De Pooter, Tim, Van den Broeck, Marleen, Corsmit, Ellen, De Rijk, Peter, Del-Favero, Jurgen, van Swieten, John, van Duijn, Cornelia M, Van Broeckhoven, Christine",2
Loss of desmoplakin tail causes lethal acantholytic epidermolysis bullosa.,0
"The cytoplasmic plaque protein desmoplakin (DP), which is located in desmosomes, plays a major role in epithelial and muscle cell adhesion by linking the transmembrane cadherins to the cytoplasmic intermediate filament network. Mutations of DP may cause striate palmoplantar keratoderma, arrhythmogenic right ventricular dysplasia, skin fragility/woolly hair syndrome, Naxos-like disease, and Carvajal syndrome. DP must be indispensable, because DP-/- mice are early abortive. Here, we report a patient with severe fragility of skin and mucous membranes caused by genetic truncation of the DP tail. The new phenotype is lethal in the neonatal period because of immense transcutaneous fluid loss. The phenotype also comprised universal alopecia, neonatal teeth, and nail loss. Histology showed suprabasal clefting and acantholysis throughout the spinous layer, mimicking pemphigus. Electron microscopy revealed disconnection of keratin intermediate filaments from desmosomes. Immunofluorescence staining of DP showed a distinct punctate intercellular pattern in the patient's skin. Protein analysis revealed expression of truncated DP polypeptides. Mutational analysis of the patient demonstrated compound heterozygosity for two DP mutations, 6079C-->T (R1934X) and 6370delTT, respectively. Aberrant mRNA transcripts that predict premature termination of translation with loss of the three intermediate filament-binding subdomains in the DP tail were detected by RT-PCR. The new dramatic phenotype, which we named ""lethal acantholytic epidermolysis bullosa,"" underscores the paramount role of DP in epidermal integrity.",1
"Jonkman, Marcel F, Pasmooij, Anna M G, Pasmans, Suzanne G M A, van den Berg, Maarten P, Ter Horst, Henk J, Timmer, Albertus, Pas, Hendri H",2
Linkage disequilibrium mapping of quantitative-trait Loci by selective genotyping.,0
"The principles of linkage disequilibrium mapping of dichotomous diseases can be well applied to the mapping of quantitative-trait loci through the method of selective genotyping. In 1999, M. Slatkin considered a truncation selection (TS) approach. We propose in this report an extended TS approach and an extreme-rank-selection (ERS) approach. The properties of these selection approaches are studied analytically. By using a simulation study, we demonstrate that both the extended TS approach and the ERS approach provide remarkable improvements over Slatkin's original TS approach.",1
"Chen, Zehua, Zheng, Gang, Ghosh, Kaushik, Li, Zhaohai",2
"Sex, not genotype, determines recombination levels in mice.",0
"Recombination, the precise physical breakage and rejoining of DNA between homologous chromosomes, plays a central role in mediating the orderly segregation of meiotic chromosomes in most eukaryotes. Despite its importance, the factors that control the number and placement of recombination events within a cell remain poorly defined. The rate of recombination exhibits remarkable species specificity, and, within a species, recombination is affected by the physical size of the chromosome, chromosomal location, proximity to other recombination events (i.e., chiasma interference), and, intriguingly, the sex of the transmitting parent. To distinguish between simple genetic and nongenetic explanations of sex-specific recombination differences in mammals, we compared recombination in meiocytes from XY sex-reversed and XO females with that in meiocytes from XX female and XY male mice. The rate and pattern of recombination in XY and XO oocytes were virtually identical to those in normal XX females, indicating that sex, not genotype, is the primary determinant of meiotic recombination patterns in mammals.",1
"Lynn, Audrey, Schrump, Stefanie, Cherry, Jonathan, Hassold, Terry, Hunt, Patricia",2
Charting the ancestry of African Americans.,0
"The Atlantic slave trade promoted by West European empires (15th-19th centuries) forcibly moved at least 11 million people from Africa, including about one-third from west-central Africa, to European and American destinations. The mitochondrial DNA (mtDNA) genome has retained an imprint of this process, but previous analyses lacked west-central African data. Here, we make use of an African database of 4,860 mtDNAs, which include 948 mtDNA sequences from west-central Africa and a further 154 from the southwest, and compare these for the first time with a publicly available database of 1,148 African Americans from the United States that contains 1,053 mtDNAs of sub-Saharan ancestry. We show that >55% of the U.S. lineages have a West African ancestry, with <41% coming from west-central or southwestern Africa. These results are remarkably similar to the most up-to-date analyses of the historical record.",1
"Salas, Antonio, Carracedo, Angel, Richards, Martin, Macaulay, Vincent",2
"Cloning of dimethylglycine dehydrogenase and a new human inborn error of metabolism, dimethylglycine dehydrogenase deficiency.",0
"Dimethylglycine dehydrogenase (DMGDH) (E.C. number 1.5.99.2) is a mitochondrial matrix enzyme involved in the metabolism of choline, converting dimethylglycine to sarcosine. Sarcosine is then transformed to glycine by sarcosine dehydrogenase (E.C. number 1.5.99.1). Both enzymes use flavin adenine dinucleotide and folate in their reaction mechanisms. We have identified a 38-year-old man who has a lifelong condition of fishlike body odor and chronic muscle fatigue, accompanied by elevated levels of the muscle form of creatine kinase in serum. Biochemical analysis of the patient's serum and urine, using (1)H-nuclear magnetic resonance NMR spectroscopy, revealed that his levels of dimethylglycine were much higher than control values. The cDNA and the genomic DNA for human DMGDH (hDMGDH) were then cloned, and a homozygous A-->G substitution (326 A-->G) was identified in both the cDNA and genomic DNA of the patient. This mutation changes a His to an Arg (H109R). Expression analysis of the mutant cDNA indicates that this mutation inactivates the enzyme. We therefore confirm that the patient described here represents the first reported case of a new inborn error of metabolism, DMGDH deficiency.",1
"Binzak, B A, Wevers, R A, Moolenaar, S H, Lee, Y M, Hwu, W L, Poggi-Bach, J, Engelke, U F, Hoard, H M, Vockley, J G, Vockley, J",2
Orientations of the tryptophan 9 and 11 side chains of the gramicidin channel based on deuterium nuclear magnetic resonance spectroscopy.,0
"Deuterium nuclear magnetic resonance spectroscopy was used to investigate the orientations of the indole rings of Trp9 and Trp11 in specific indole-d5-labeled samples of gramicidin A incorporated into dimyristoyl phosphatidylcholine bilayers in the beta 6.3 channel conformation. The magnitudes and signs of the deuterium quadrupolar splittings were fit to the rings and assigned to specific ring bonds, using a full rotation search of the chi 1 and chi 2 angles of each Trp and a least-squares method. Unique assignments were obtained. The data and assignments are in close agreement with four sets of (chi 1, chi 2) angles for each Trp in which the indole N-H is oriented toward the membrane's exterior surface. (Four additional sets of (chi 1, chi 2) angles with the N-H's pointing toward the membrane interior are inconsistent with previous observations.) One of the sets of (chi 1, chi 2) angles for each Trp is consistent with the corresponding Trp orientation found by Arsen'ev et al. (1986. Biol. Membr. 3:1077-1104) for gramicidin in sodium dodecyl sulfate micelles. Together, the 1H and 2H nuclear magnetic resonance methods suggest that the Trp9 and Trp11 side chain orientations could be very similar in dimyristoyl phosphatidylcholine membranes and in sodium dodecyl sulfate micelles. The data for Trp11 could be fit using a static quadrupolar coupling constant of 180 kHz under the assumption that the ring is essentially immobile. By contrast, Trp9 could be fit only under the assumption that the quadrupolar splittings for ring 9 are reduced by approximately 14% due to motional averaging. Such a difference in motional averaging between rings 11 and 9 is also consistent with the 15N data of Hu et al. (1993. Biochemistry. 32:7035-7047).",1
"Koeppe, R E, Killian, J A, Greathouse, D V",2
Lipid-glass adhesion in giga-sealed patch-clamped membranes.,0
"Adhesion between patch-clamped lipid membranes and glass micropipettes is measured by high contrast video imaging of the mechanical response to the application of suction pressure across the patch. The free patch of membrane reversibly alters both its contact angle and radius of curvature on pressure changes. The assumption that an adhesive force between the membrane and the pipette can sustain normal tension up to a maximum Ta at the edge of the free patch accounts for the observed mechanical responses. When the normal component of the pressure-induced membrane tension exceeds Ta membrane at the contact point between the free patch and the lipid-glass interface is pulled away from the pipette wall, resulting in a decreased radius of curvature for the patch and an increased contact angle. Measurements of the membrane radius of curvature as a function of the suction pressure and pipette radius determine line adhesion tensions Ta which range from 0.5 to 4.0 dyn/cm. Similar behavior of patch-clamped cell membranes implies similar adhesion mechanics.",1
"Opsahl, L R, Webb, W W",2
The solution structure of the four-way DNA junction at low-salt conditions: a fluorescence resonance energy transfer analysis.,0
"The four-way DNA (Holliday) junction is an important postulated intermediate in the process of genetic recombination. Earlier studies have suggested that the junction exists in two alternative conformations, depending upon the salt concentration present. At high salt concentrations the junction folds into a stacked X structure, while at low salt concentrations the data indicate an extended unstacked conformation. The stereochemical conformation of the four-way DNA junction at low salt (low alkali ion concentration and no alkaline earth ions) was established by comparing the efficiency of fluorescence resonance energy transfer (FRET) between donor and acceptor molecules attached pairwise in three permutations to the 5' termini of the duplex arms. A new variation of FRET was implemented based upon a systematic variation of the fraction of donor labeled single strands. The FRET results indicate that the structure of the four-way DNA junction at low salt exists as an unstacked, extended, square arrangement of the four duplex arms. The donor titration measurements made in the presence of magnesium ions clearly show the folding of the junction into the X stacked structure. In addition, the FRET efficiency can be measured. The fluorescence anisotropy of the acceptor in the presence of Mg2+ during donor titrations was also measured; the FRET efficiency can be calculated from the anisotropy data and the results are consistent with the folded, stacked X structure.",1
"Clegg, R M, Murchie, A I, Lilley, D M",2
"Low single channel conductance of the major skeletal muscle chloride channel, ClC-1.",0
"We expressed the skeletal muscle chloride channel, ClC-1, in HEK293 cells and investigated it with the patch-clamp technique. Macroscopic properties are similar to those obtained after expression in Xenopus oocytes, except that faster gating kinetics are observed in mammalian cells. Nonstationary noise analysis revealed that both rat and human ClC-1 have a low single channel conductance of about 1 pS. This finding may explain the lack of single-channel data for chloride channels from skeletal muscle despite its high macroscopic chloride conductance.",1
"Pusch, M, Steinmeyer, K, Jentsch, T J",2
Correction for missed events based on a realistic model of a detector.,0
"Quantitative patch-clamp analysis based on dwell-time histograms has to deal with the problem of missed events. The correction of the evaluated time constants has to take into account the characteristics of the detector used for the reconstruction of the time series. In previous approaches a simple model of the detector has been used, which is based on the assumption that all events shorter than the temporal resolution tres were missed, irrespective of the preceding events. Rather than the standard assumption of a fixed dead time, we introduce a more realistic model of a detector by a continuous-time version of the Hinkley detector. The combined state of the channel and the detector obeys a Markov model, which is governed by a Fokker-Planck-Kolmogorov partial differential equation. The steady-state solution leads to the determination of the apparent time constants tau o and tau c depending on the true rate constants koc and kco and the temporal resolution tres of the detector. Simulations with different kinds of detectors, including the Bessel filter with half-amplitude threshold detection, are performed. They show that our new equation predicts the dependence of tau c and tau o on koc, kco, and tres better than the standard equation used until now.",1
"Draber, S, Schultze, R",2
"Long-range interactions, voltage sensitivity, and ion conduction in S4 segments of excitable channels.",0
"Forces acting on the S4 segments of the channel, the voltage-sensing structures, are analyzed. The conformational change in the Na channel is modeled as a helix-coil transition in the four S4 segments, coupled to the membrane voltage by electrical forces. In the model, repulsions between like charges make the S4 segment unstable, but field-dependent forces hold it in an alpha-helix configuration at resting potential. At threshold depolarization, the S4 helices cooperatively expand into random coils, breaking the hydrogen bonds connecting adjacent loops of the alpha helices. Exposed electron pairs left on the carbonyl oxygens constitute sites at which cations can bind selectively. The first hydrogen bond to break is at the channel exterior, then the second breaks, and so on in a zipper-like motion along the entire segment. The Na+ ions hop from one site to the next until all H bonds are broken and all sites are filled with ions. This completes the pathway over which the permeant ions move through the channel, driven by the electrochemical potential difference across the membrane. This microscopic mechanism is consistent with the thermodynamic explanation of ion-channel gating previously formulated as the ferroelectric-superionic transition hypothesis.",1
"Leuchtag, H R",2
"Calorimetric studies of the kinetic unfreezing of molecular motions in hydrated lysozyme, hemoglobin, and myoglobin.",0
"Differential scanning calorimetric (DSC) studies of the glassy states of as-received and hydrated lysozyme, hemoglobin, and myoglobin powders, with water contents of < or = 0.25, < or = 0.30, and < or = 0.29 g/g of protein, show that their heat capacity slowly increases with increasing temperature, without showing an abrupt increase characteristic of glass-->liquid transition. Annealing (also referred to as physical aging) of the hydrated proteins causes their DSC scans to show an endothermic region, similar to an overshoot, immediately above the annealing temperature. This annealing effect appears at all temperatures between approximately 150 and 300 K. The area under these peaks increases with increasing annealing time at a fixed temperature. The effects are attributed to the presence of a large number of local structures in which macromolecular segments diffuse at different time scales over a broad range. The lowest time scale corresponds to the > N-H and -O-H group motions which become kinetically unfrozen at approximately 150-170 K on heating at a rate of 30 K min-1 and which have a relaxation time of 5-10 s in this temperature range. The annealing effects confirm that the individual glass transition of the relaxing local regions is spread over a temperature range up to the denaturation temperature region of the proteins. The interpretation is supported by simulation of DSC scans in which the distribution of relaxation times is assumed to be exceptionally broad and in which annealing done at several temperatures over a wide range produces endothermic effects (or regions of DSC scans) qualitatively similar to those observed for the hydrated proteins.",1
"Sartor, G, Mayer, E, Johari, G P",2
Three-dimensional reconstruction of a co-complex of F-actin with antibody Fab fragments to actin's NH2 terminus.,0
"We have decorated F-actin with Fab fragments of antibodies to actin residues 1-7. These antibody fragments do not strongly affect the rigor binding of myosin S-1 to actin, but do affect the binding of S-1 to actin in the presence of nucleotide (DasGupta, G., and E. Reisler, 1989. J. Mol. Biol. 207:833-836; 1991. Biochemistry. 30:9961-9966; 1992. Biochemistry. 31:1836-1841). Although the binding constant is rather low, we estimate that we have achieved about 85% occupancy of the actin sites. Three-dimensional reconstructions from electron micrographs of both negatively stained and frozen-hydrated filaments show that the Fab fragment is bound at the location of the NH2 terminus in the model of Holmes et al. (Holmes, K.C., D. Popp, W. Gebhard, and W. Kabsch. 1990. Nature. 347:37-44) for F-actin, excluding very different orientations of the actin subunit in the filament. Most of the mass of the antibody is not visualized, which is due to the large mobility of the NH2 terminus in F-actin, differences in binding angle within the polyclonal antibody population, or a combination of both of these possibilities.",1
"Orlova, A, Yu, X, Egelman, E H",2
Structures of large T antigen at the origin of SV40 DNA replication by atomic force microscopy.,0
"For inorganic crystals such as calcite (CaCO3), Atomic Force Microscopy (AFM) has provided surface structure at atomic resolution (Ohnesorge and Binnig, 1993). As part of a broad effort to obtain high resolution for an individual protein or protein assembly (Binnig et al., 1986; Rugar and Hansma, 1990; Radmacher et al., 1992), we applied AFM to study the ATP-dependent double hexamer of SV40 large T antigen, which assembles around the viral origin of DNA replication. Multimeric mass has been determined in two-dimensional projected images by Scanning Transmission Electron Microscopy (STEM) (Mastrangelo et al., 1989). By AFM, if the DNA-protein preparation has been stained positively by uranyl acetate, the contour at the junction between hexamers is visible as a cleft, 2-4 nm deep. The cleft, whether determined as a fraction of height by AFM or as a fraction of mass thickness by STEM, is of comparable magnitude. On either side of the cleft, hexamers attain a maximum height of 13-16 nm. Monomers found in the absence of ATP show heights of 5-7 nm. Taken together, the z coordinates provide a surface profile of complete and partial replication assemblies consistent with the spatial distribution of recognition pentanucleotides on the DNA, and they contribute direct geometrical evidence for a ring-like hexamer structure.",1
"Mastrangelo, I A, Bezanilla, M, Hansma, P K, Hough, P V, Hansma, H G",2
Amiloride-insensitive cation conductance in Xenopus laevis olfactory neurons: a combined patch clamp and calcium imaging analysis.,0
"We used digital calcium imaging with Fura-2 in conjunction with the tight-seal whole-cell patch clamp technique to describe a novel cation conductance in olfactory neurons of the clawed toad Xenopus laevis. Substitution of extracellular Ca2+ and Na+ was used as a tool to change [Ca2+]i. When [Ca2+]i was increased to about 450 nM, a conductance gcat activated that was permeable for cations. Upon gcat activation, an increase in [Ca2+]i occurred in the dendritic knob. Once activated, gcat showed no further dependence upon [Ca2+]i. Icat is shown to be different from the current activated by a mixture of the odorants citralva and amyl acetate. We conclude that there are two different cation conductances in the peripheral compartments of olfactory neurons in X. laevis.",1
"Schild, D, Lischka, F W",2
Analysis of protein binding to receptor-doped lipid monolayers by Monte Carlo simulation.,0
This paper presents a Monte Carlo simulation (MCS) method for estimating the parameters that characterize ligand-receptor binding directly from experimentally derived binding isotherms. Binding parameters are estimated by incorporating an MCS algorithm for ligand binding to a two-dimensional receptor array into a nonlinear regression program. The MCS method was tested by analyzing experimental isotherms of avidin binding to biotinylated lipid in Langmuir-Blodgett (LB) monolayers. The MCS-derived cooperativity coefficients and intrinsic association constants for avidin-biotin binding to LB films are correlated strongly (R2 > 0.93) with the binding parameters determined from the same experimental data by a thermodynamic equilibrium binding model (Zhao et al. 1993. Langmuir. 9:3166-3173). This result shows MCS to be an accurate and potentially more versatile method for characterizing biomolecular interactions at surfaces.,1
"Zhao, S, Reichert, W M",2
Analysis of the crystallization kinetics of lysozyme using a model with polynuclear growth mechanism.,0
A differential equation model with a polynuclear growth mechanism was formulated for a theoretical understanding of protein crystallization. The model equation contains two parameters characterizing nucleation and growth: the number of protein molecules constituting a critical nucleus and the order of growth kinetics. This model was applied successfully to explain the experimental data on the protein concentration changes due to nucleation and crystal growth of tetragonal and orthorhombic hen egg-white lysozyme. It was shown that the critical nucleus most probably consists of three or four molecules. The range and extent of the validity of the present model and analysis are discussed.,1
"Bessho, Y, Ataka, M, Asai, M, Katsura, T",2
Conductance mutations of the nicotinic acetylcholine receptor do not act by a simple electrostatic mechanism.,0
"Fixed negative charges in many cation channels raise the single-channel conductance, apparently by an electrostatic mechanism: their effects are accentuated in solutions of low ionic strength and attenuated at high ionic strength. The charges of specific amino acids near the ends of the proposed pore-lining M2 segment of the nicotinic acetylcholine receptor, termed the extracellular and cytoplasmic rings, have recently been shown to influence the single-channel K+ conductance (Imoto, K., C. Busch, B. Sakmann, M. Mishina, T. Konno, J. Nakai, H. Bujo, Y. Mori, K. Fukuda and S. Numa. 1988. Nature 335:645-648). We examined whether these charges might act by a direct electrostatic effect on the energy of ions in the pore, rather than indirectly by inducing a structural change. To this end, we measured the conductances of charge mutants over a range of K+ concentrations (ionic strengths). As expected, we found that negative charge mutations raise the conductance, and positive charge mutations lower it. The effects of cytoplasmic-ring mutations are accentuated at low ionic strength, but they are not completely attenuated at high ionic strength. The effects of extracellular-ring mutations are independent of ionic strength. These results are inconsistent with the simplest electrostatic model. We suggest a modified model that qualitatively accounts for the data.",1
"Kienker, P, Tomaselli, G, Jurman, M, Yellen, G",2
The rational design of amino acid sequences by artificial neural networks and simulated molecular evolution: de novo design of an idealized leader peptidase cleavage site.,0
"A method for the rational design of locally encoded amino acid sequence features using artificial neural networks and a technique for simulating molecular evolution has been developed. De novo in machine design of Escherichia coli leader peptidase (SP1) cleavage sites serves as an example application. A modular neural network system that employs sequence descriptions in terms of physicochemical properties has been trained on the recognition of characteristic cleavage site features. It is used for sequence qualification in the design cycle, representing the sequence fitness function. Starting from a random sequence several cleavage site sequences were generated by a simulated molecular evolution technique. It is based on a simple genetic algorithm that takes the quality values calculated by the artificial neural network as a heuristic for inductive sequence optimization. Simulated in vivo mutation and selection allows the identification of predominant sequence positions in Escherichia coli signal peptide cleavage site regions (positions -2 and -6). Various amino acid distance maps are used to define metrics for the step size of mutations. Position-specific mutability values indicate sequence positions exposed to high or low selection pressure in the simulations. The use of several distance maps leads to different courses of optimization and to various idealized sequences. It is concluded that amino acid distances are context dependent. Furthermore, a method for identification of local optima during sequence optimization is presented.",1
"Schneider, G, Wrede, P",2
The barrel-stave model as applied to alamethicin and its analogs reevaluated.,0
"Alamethicin and its analogs from cation selective, multi-conductance channels in lipid bilayers. The conductance levels have been thought to be due to a barrel-stave structure where conducting pores (barrels) are formed by the self-assembly of a variable number of alpha-helical rods (staves). The conductance transitions were then interpreted as the addition or deletion of peptide monomers from the pore-forming complex (Sansom, M.S. 1991. Prog. Biophys. Mol. Biol. 55:139-235). Initially, pore conductances were calculated from that expected of right circular cylinders of ""bulk"" electrolyte. More recent theories also included the access resistance of the electrolyte outside the pore. However, they all consistently overestimated the observed conductances. The reason for the discrepancy is presented here. Previous theories ignored the effects of ion concentration gradients near the pore. Hence, they only held in the limit of small bilayer potentials (< 25 mV) and so would overestimate measurements that typically used much larger potentials (> 100 mV). This theoretical flaw is corrected by using Läuger's theory of diffusion-limited ion flow (Läuger, P. 1976. Biochim. Biophys. Acta. 455:493-509). Thus, including the effects of ion concentration gradients results in a considerable improvement in predicting pore conductances. It is found that: 1) the effects of ion concentration gradients must be included in the barrel-stave model for it to apply to the available data; 2) previously published explanations for the discrepancy between the model and the data, namely the ""distorted bundle"" and the ""head-to-tail aggregate"" hypotheses are not necessary (reviewed by Sansom, 1991).",1
"Laver, D R",2
Diacylglycerol and hexadecane increase divalent cation-induced lipid mixing rates between phosphatidylserine large unilamellar vesicles.,0
"Bovine brain phosphatidylserine (BBPS) vesicles were prepared with traces of dioleoylglycerol (18:1, 18:1 DAG) or hexadecane (HD) to determine the influence of changes in headgroup or acyl chain packing on divalent cation-induced lipid mixing rates. A stopped-flow apparatus was used to combine vesicles with 3 mM Ca2+ or Ba2+. Aggregation was monitored by light scattering and lipid mixing by lipid probe dilution. Neither 3-6 mol% 18:1, 18:1 DAG nor up to 10 mol % HD significantly altered the BBPS chain melting temperature, vesicle diameter, or vesicle aggregation rates. Lipid mixing rates doubled by adding either 3 mol % 18:1, 18:1 DAG or 6 mol % HD to BBPS with no change in the Ca2+ concentration threshold. The Arrhenius slopes of the lipid mixing rates for control, 3 mol % 18:1, 18:1 DAG, and 6 mol % HD vesicles were identical. 2H-nuclear magnetic resonance spectra of perdeuterated dipalmitoylglycerol and HD in BBPS in the absence and presence of Ca2+ and Ba2+ showed that the solutes occupied different time-averaged positions in the bilayer under each condition. These data suggest that: 1) the enhanced lipid mixing rate is related to the volume of the added alkyl chains; 2) 18:1, 18:1 DAG and HD may alter the activation entropy or the attempt frequency at one or more steps in the lipid mixing process; 3) 18:1, 18:1 DAG and HD are likely to act at a different spatial or temporal point than the divalent cation; and 4) it is unlikely that the effect of these solutes on lipid mixing is due to their equilibrium time-averaged positions in the bilayer. Others have shown that apolar lipids accelerate fusion in nonbilayer phase-forming systems, but BBPS does not form these phases under these conditions. Therefore, we propose that the effect of very small amounts of apolar substances may be very general, e.g., stabilizing the hydrophobic interstices associated with a variety of proposed intermediate structures.",1
"Walter, A, Yeagle, P L, Siegel, D P",2
The neutral area surface of the cubic mesophase: location and properties.,0
"A neutral area surface can be defined as one whose area remains fixed upon bending. It is assumed that such a surface exists within the amphiphilic monolayers that constitute the bicontinuous cubic mesophases and that it parallels approximately the highly convoluted polar/apolar interface in such systems. Here, we report on how the neutral area surface in the cubic phase (space group Ia3d) of the hydrated monoacylglycerol, monoolein, was determined. It is located at a distance of approximately 8.8 A from the methyl terminus of the acyl chain. At 25 degrees C, the surface area per lipid molecule at the neutral area surface is 35.1 +/- 0.2 A2, which is remarkably similar to the mean cross-sectional area of hydrated monoolein in the lamellar liquid crystalline phase at this same temperature.",1
"Chung, H, Caffrey, M",2
Effects of diacylglycerols and Ca2+ on structure of phosphatidylcholine/phosphatidylserine bilayers.,0
"The combined effects of the diacylglycerols (DAGs) with the various acyl chains and Ca2+ on the structure of phosphatidylcholine/phosphatidylserine (4:1 mole/mole) bilayers were studied using 2H- and 31P NMR. The following DAG- and Ca(2+)-induced bilayer perturbations were identified. 1) Increased tendency to form nonbilayer lipid phases was induced by diolein or stearoylarachidonoylglycerol, and was synergistically enhanced by the addition of Ca2+. 2) ""Transverse"" bilayer perturbation was induced by dioctanoylglycerol. The addition of this DAG caused increased ordering of the phospholipid acyl side chains in the region adjacent to the headgroup, with the concomitant decrease of the order toward the bilayer interior. 3) Separation of the phosphatidylcholine and phosphatidylserine bilayer components was induced by combinations of relatively high (1:5 mole/mole to phosphatidylserine) Ca2+ and 25 mol% (to the phospholipids) of diolein, stearoylarachidonoylglycerol, or oleoylacetylglycerol. 4) Lateral phase separation of the bilayers on the regions of different fluidities was induced by dipalmitin. These physicochemical effects were correlated with the effects of these DAGs and Ca2+ on the activity of protein kinase C. The increased tendency to form nonbilayer lipid phases and the transverse bilayer perturbations correlated with the increased protein kinase C activity, whereas the actual presence of the nonbilayer lipid phases, as well as the separation of the phosphatidylcholine and phosphatidylserine components, was associated with the decrease in the protein kinase C activity. The lateral phase separation of the bilayer on gel-like and liquid crystalline regions did not have an effect on the activity of the enzyme. These results demonstrate the importance of the physicochemical properties of the membranes in the process of activation of protein kinase C.",1
"Goldberg, E M, Lester, D S, Borchardt, D B, Zidovetzki, R",2
Anomalous diffusion due to obstacles: a Monte Carlo study.,0
"In normal lateral diffusion, the mean-square displacement of the diffusing species is proportional to time. But in disordered systems anomalous diffusion may occur, in which the mean-square displacement is proportional to some other power of time. In the presence of moderate concentrations of obstacles, diffusion is anomalous over short distances and normal over long distances. Monte Carlo calculations are used to characterize anomalous diffusion for obstacle concentrations between zero and the percolation threshold. As the obstacle concentration approaches the percolation threshold, diffusion becomes more anomalous over longer distances; the anomalous diffusion exponent and the crossover length both increase. The crossover length and time show whether anomalous diffusion can be observed in a given experiment.",1
"Saxton, M J",2
The mechanism of lamellar-to-inverted hexagonal phase transitions: a study using temperature-jump cryo-electron microscopy.,0
"The lamellar/inverted hexagonal (L alpha/HII) phase transition can be very fast, despite the drastic change in the topology of the lipid/water interfaces. The first structures to form in this transition may be similar to those that mediate membrane fusion in many lipid systems. To study the transition mechanism and other dynamic phenomena in membrane dispersions, we constructed an apparatus to rapidly trigger the transition and then vitrify the specimens to preserve the structure of transient intermediates. The apparatus applies millisecond-long temperature jumps of variable size to aqueous dispersions of lipids on electron microscope grids at times 9-16 ms before specimen vitrification. The vitrified specimens are then examined by cryo-transmission electron microscopy. Dispersions of egg phosphatidylethanolamine completed the transition within 9 ms when superheated by 20 K. Similar transition times have been observed in dioleoylphosphatidylethanolamine via time-resolved x-ray diffraction. N-monomethylated dioleoylphosphatidylethanolamine dispersions superheated to lesser extent exhibited slower transitions and more complex morphology. The structure of the first intermediates to form in the transition process could not be determined, probably because the intermediates are labile on the time scale of sample cooling and vitrification (< 1 ms) and because of the poor contrast developed by some of these small structures. However, the results are more compatible with a transition mechanism based on ""stalk"" intermediates than a mechanism involving inverted micellar intermediates. Temperature-jump cryo-transmission electron microscopy should be useful in studying dynamic phenomena in biomembranes, large protein complexes, and other colloidal dispersions. It should be especially helpful in studying the mechanism of protein-induced membrane fusion.",1
"Siegel, D P, Green, W J, Talmon, Y",2
Kinetic modeling of exciton migration in photosynthetic systems. 2. Simulations of excitation dynamics in two-dimensional photosystem I core antenna/reaction center complexes.,0
"Kinetic modeling of the exciton migration in the cyanobacterial photosystem I core complex from Synechococcus sp. was performed by an exact solution of the Pauli master equation for exciton motion. A square two-dimensional 10 x 10 pigment lattice and a Förster dipole-dipole coupling between chromophores was assumed. We calculated decay-associated spectra and lifetimes and compared them to the corresponding experimental data from picosecond fluorescence and transient absorption obtained by global analysis. Seven spectral chlorophyll(Chl) forms, identical in shape but shifted in their absorption maximums, were used to describe the non-homogeneous broadening of the PS I-100 particle absorption spectrum. The optimized Chl lattice arrangement best reproducing the experimental decay-associated spectra as well as the steady-state fluorescence spectrum indicated the long-wavelength-absorbing Chls forming a cluster in the corner of the lattice with the reaction center (RC) placed apart at a distance of two lattice constants. The variable parameters, i.e., the charge separation rate in the RC and the lattice constant a, were found to be optimal at kRC = 2.3 ps-1 and a = 1.14 nm, respectively. The surprising conclusions of the simulations is that Chls with absorption maxima as long a 724 nm have to be taken into account to describe the time-resolved spectra of this PS I particle properly. The dependencies of the exciton decay in the model PS I particle on the excitation wavelength and on the temperature are discussed. We also show that the excited state decay of similar PS I particles that lack the long-wavelength absorbing Chls is nearly mono-exponential. Various critical factors that limit the general reliability of the conclusions of such simulations are discussed in detail.",1
"Trinkunas, G, Holzwarth, A R",2
Investigations of the thermal response of laser-excited biomolecules.,0
"A model is presented that connects the underlying classical thermal transport coefficients to the experimentally determined vibrational temperature of a photoexcited chromophore embedded in a protein matrix that is surrounded by water. Both photo-stationary state heating (e.g., within a 10-ns laser pulse) and transient cooling (e.g., after termination of the laser pulse) are treated. Because only a few thermal transport parameters can be experimentally determined, this simple model provides a practical and efficient method for describing the temperatures of the chromophore, protein, and solvent as functions of time and position. We expect that such a model will be useful in interfacing experimental observations with more elaborate molecular dynamics calculations, which depend upon many variables. In the transient cooling process, which is relevant for ultrafast pulsed laser measurements, the temperature of the chromophore follows a double exponential decay at short times, whereas at longer times the thermal decay ""rolls over"" to a diffusion limit (t-3/2). For typical 10-ns laser pulses (approximately 0.5 GW/cm2) and chromophore absorption cross-sections (approximately 10(-16) cm2), we find that the biomolecule reaches thermal steady-state on a ps time scale. The role of the various thermal transport coefficients and their independent experimental determination is also discussed.",1
"Li, P, Champion, P M",2
Time-resolved spectroscopy of energy and electron transfer processes in the photosynthetic bacterium Heliobacillus mobilis.,0
"The kinetics of excitation energy transfer and electron transfer processes within the membrane of Heliobacillus mobilis were investigated using femtosecond transient absorption difference spectroscopy at room temperature. The kinetics in the 725- to 865-nm region, upon excitation at 590 and 670 nm, were fit using global analysis. The fits returned three kinetic components with lifetimes of 1-2 ps and 27-30 ps, and a component that does not decay within several nanoseconds. The 1- to 2-ps component is attributed to excitation equilibration to form a thermally relaxed excited state. The 27- to 30-ps phase corresponds to the decay of the relaxed excited state to form a charge-separated state. The intrinsic energy and electron transfer rates were estimated using the experimental results and theoretical models for excitation migration and trapping dynamics. Taking into account the number of antenna pigments and their spectral distribution, an upper limit of 1.2 ps for the intrinsic time constant for charge separation in the reaction center is calculated. This upper limit corresponds with the trapping-limited case for excitation migration and trapping. Reduction of the primary electron acceptor A0 was observed in the 640 to 700 nm region using excitation at 780 nm. An instantaneous absorbance increase followed by a decay of about 30 ps was observed over a broad wavelength region due to the excited state absorption and decay of BChl g molecules in the antenna. In addition, a narrow bleaching band centered at 670 nm grows in with an apparent time constant of about 1.0 ps, superimposed on the 30-ps absorbance increase due to excited state absorption. Measurements on a longer time scale showed that besides the 670 nm pigment a BChl g molecule absorbing near 785 nm may be involved in the primary charge separation, and that this pigment may be in equilibrium with the 670 nm pigment. The bleaching bands at 670 nm and 785nm recovered with a time constant of about 600 ps, due to forward electron transport to a secondary electron acceptor. Energy and electron transfer properties of H. mobilis membranes are compared with Photosystem 1, to which the heliobacteria bear an evolutionary relationship.",1
"Lin, S, Chiou, H C, Kleinherenbrink, F A, Blankenship, R E",2
Hydrodynamics of horseradish peroxidase revealed by global analysis of multiple fluorescence probes.,0
"Previous fluorescence studies of horseradish peroxidase conjugated with protoporphyrin IX suggested that the protein behaved hydrodynamically as a prolate ellipsoid of axial ratio 3 to 1. The present study, designed to further investigate the hydrodynamics of this protein, exploits a series of probes, noncovalently bound to the heme binding site of apo-horseradish peroxidase, having different orientations of the excitation and emission transition dipoles with respect to the protein's rotational axes. The probes utilized included protoporphyrin IX and the naphthalene probes 1-anilino-8-naphthalene sulfonate, 2-p-toluidinyl-6-naphthalene sulfonate, and 4,4'-bis(1-anilino-8-naphthalene sulfonate). Time-resolved data were obtained using multifrequency phase fluorometry. The global analysis approach to the determination of molecular shape using multiple probes was evaluated by utilizing all data sets while maintaining a constant molecular shape for the protein. The results indicated that, in such analyses, probes exhibiting a single exponential decay and limited local motion have the major weight in the evaluation of the axial ratio. Probes that show complex decay patterns and local motions, such as the naphthalene derivatives, give rise to significant uncertainties in such global treatments. By explicitly accounting for the effect of such local motion, however, the shape of the protein can be reliably recovered.",1
"Brunet, J E, Vargas, V, Gratton, E, Jameson, D M",2
Stabilization of intermediate density states in globular proteins by homogeneous intramolecular attractive interactions.,0
"On-lattice simulations of two-dimensional self-avoiding chains subject to homogeneous intramolecular attractive interactions were performed as a model for studying various density regimes in globular proteins. For short chains of less than 15 units, all conformations were generated and classified by density. The range of intramolecular interactions was found to increase uniformly with density, and the average number of topological contacts is directly proportional to density. The uniform interaction energy increases the probability of high density states but does not necessarily lead to dominance of the highest density state. Typically, several large peaks appear in the probability distribution of packing densities, their location and amplitude being determined by the balance between entropic effects enhancing more expanded conformations and attractive interactions favoring compact forms. Also, the homogeneous interaction energy affects the distribution of most probable interacting points in favor of the longer range interactions over the short range ones, but in addition it introduces some more detailed preferences even among short range interactions. There are some implications about the characteristics of the intermediate density states and also for the likelihood that the native state does not correspond completely to the lowest energy conformation.",1
"Bahar, I, Jernigan, R L",2
Cooperative structural transitions induced by non-homogeneous intramolecular interactions in compact globular proteins.,0
"The role played by non-homogeneous interactions in stabilizing cooperative structural changes in proteins was investigated by exhaustive simulations of all compact conformations compatible with several well-defined globule-like shapes in three dimensions. Conformational free energies corresponding to the association of residues i and j were computed both for the unperturbed system, all subject to identical intramolecular interactions, and for the perturbed system in which a single pair of residues is probed by changing its interactions with an attractive or repulsive interaction. The high packing density leads to strong coupling between residues so that specific interactions between a given pair of residues are accompanied by considerable enthalpy changes. Relatively weak, about 1-2 kcal/mol, attractive interactions can exert a dramatic effect on the free energy distribution. Usually, central positions in the sequence most affect the conformational characteristics. Some of these interaction pairs appear to be capable of effecting major conformation transitions because of the high level of cooperativity in the dense state. Effects of repulsive interactions, however, do not depend so strongly on residue pair and cause more localized structural changes. This approach can suggest more, or less, sensitive loci for amino acid substitution.",1
"Bahar, I, Jernigan, R L",2
The use of fluorescence methods to monitor unfolding transitions in proteins.,0
"This article discusses several strategies for the use steady-state and time-resolved fluorescence methods to monitor unfolding transitions in proteins. The assumptions and limitations of several methods are discussed. Simulations are presented to show that certain fluorescence observables directly track the population of states in an unfolding transition, whereas other observables skew the transition toward the dominant fluorescing species. Several examples are given, involving the unfolding of Staphylococcal aureus nuclease A, in which thermodynamic information is obtained for the temperature and denaturant induced transitions in this protein.",1
"Eftink, M R",2
Scanning concentration correlation spectroscopy using the confocal laser microscope.,0
"Concentration correlation spectroscopy allows the assessment of molecular motions in complex systems. The technique generally monitors concentration fluctuations by means of some method such as the intensity of fluorescent molecules (fluorescence correlation spectroscopy). We describe here the use of scanning confocal laser microscopy to measure correlation functions in both space and time. This methodology offers two major advantages over conventional methods. First, collecting data from different regions of the sample significantly increases the signal-to-noise ratio. Second, molecular motions of colloidal gold can be analyzed by correlation methods with high temporal and spatial resolution. Using a MRC 600 laser scanning system, we collect data from an ensemble of 768 independent subvolumes and determine the space-time correlation function. We demonstrate the technique using two different types of samples, fluorescently labeled DNA molecules in solution and colloidal gold-tagged lipids in a planar bilayer. This approach, which we term ""scanning concentration correlation spectroscopy,"" provides a straightforward means of performing high resolution correlation analysis of molecular motions with available instrumentation.",1
"Koppel, D E, Morgan, F, Cowan, A E, Carson, J H",2
Antibody diffusion in human cervical mucus.,0
"The mucosal immune system actively transports large quantities of antibodies into all mucus secretions, and these secreted antibodies help prevent infectious entry of many pathogens. Mucus is generally thought to protect epithelial cells by forming a diffusional barrier through which only small molecules can pass. However, electron microscopy indicates that the pore size in mucus is approximately 100 nm, which suggests that antibodies as well as other large molecules might also diffuse through mucus. We measured the diffusion coefficients for antibodies and other proteins within human midcycle cervical mucus using two techniques: fluorescence imaging of concentration profiles and fluorescence photobleaching recovery. The two techniques are complementary, since the rates of diffusion are observed over millimeter distances with fluorescence imaging of concentration profiles and micron distances with fluorescence photobleaching recovery. Both methods yielded essentially the same diffusion coefficients. In contrast to previous reports indicating mucus significantly impedes diffusion of small molecules, antibody diffusion in mucus was relatively unimpeded. In our observations IgG, IgG fragments, IgA, and IgM diffused almost as rapidly in cervical mucus as in water (1.0 > Dmucus/Dwater > 0.7). Simple models for diffusion through water-filled pores suggest that the hydrodynamic pore size for cervical mucus is approximately 100 nm, smaller than the approximately 1000 nm pore size of a collagen gel (at 1 mg/ml) and larger than the approximately 10 nm pore size of gelatin (at 100 mg/ml). This estimated pore size is consistent both with electron micrographs and geometric models of interfiber spacing. Based on these results, we predict that particles as large as viruses can diffuse rapidly through human midcycle cervical mucus, provided the particle forms no adhesive interactions with mucus glycoproteins.",1
"Saltzman, W M, Radomsky, M L, Whaley, K J, Cone, R A",2
A multidimensional spectrophotometer for monitoring thermal unfolding transitions of macromolecules.,0
"We describe a multidimensional spectrometer that is capable of (nearly) simultaneous measurement of circular dichroism, steady-state fluorescence, and absorbance values on the same sample in a standard 1 x 1 cm cuvette. With a computer controlled thermoelectric cell holder, this instrument is capable of measuring the above types of spectral data at various wavelengths as a function of temperature. We have developed software to control the various acquisition functions and to convert the data files to a format appropriate for use with the nonlinear least squares program, NONLIN (Johnson and Frasier, 1985). We have tested various features of this instrument and we have applied this instrument and data analysis procedure to study the thermal unfolding of ribonuclease A, under conditions were the unfolding of this protein involves an intermediate state.",1
"Ramsay, G, Eftink, M R",2
The osmotic rupture hypothesis of intracellular freezing injury.,0
"A hypothesis of the nature of intracellular ice formation is proposed in which the osmotically driven water efflux that occurs in cells during freezing (caused by the increased osmotic pressure of the extracellular solution in the presence of ice) is viewed as the agent responsible for producing a rupture of the plasma membrane, thus allowing extracellular ice to propagate into the cytoplasm. This hypothesis is developed into a mathematical framework and the forces that are present during freezing are compared to the forces which are required to rupture membranes in circumstances unrelated to low temperatures. The theory is then applied to systems which have been previously studied to test implications of the theory on the nature of intracellular ice formation. The pressure that develops during freezing due to water flux is found to be sufficient to cause a rupture of the plasma membrane and the theory gives an accurate description of the phenomenology of intracellular ice formation.",1
"Muldrew, K, McGann, L E",2
Teaching active transport at the turn of the twenty-first century: recent discoveries and conceptual changes.,0
"The conceptual advances introduced by recent discoveries in the field of active transport have triggered a transition from a ""black box"" approach to a ""mechanistic"" approach. At present, treating this subject in the graduate setting requires consideration of equilibrium and kinetic experimentation, protein chemistry, mutational analysis and molecular structure, with the aim of defining the ""transport machine.""",1
"Inesi, G",2
Molecular distributions in interphases: statistical mechanical theory combined with molecular dynamics simulation of a model lipid bilayer.,0
"A mean-field statistical mechanical theory has been developed to describe molecular distributions in interphases. The excluded volume interaction has been modeled in terms of a reversible work that is required to create a cavity of the solute size against a pressure tensor exerted by the surrounding interphase molecules. The free energy change associated with this compression process includes the configuration entropy as well as the change in conformational energy of the surrounding chain molecules. The lateral pressure profile in a model lipid bilayer (30.5 A2/chain molecule) has been calculated as a function of depth in the bilayer interior by molecular dynamics simulation. The lateral pressure has a plateau value of 309 +/- 48 bar in the highly ordered region and decreases abruptly in the center of the bilayer. Model calculations have shown that for solute molecules with ellipsoidal symmetry, the orientational order increases with the ratio of the long to short molecular axes at a given solute volume and increases with solute volume at a given axial ratio, in accordance with recent experimental data. Increased lateral pressure (p perpendicular) results in higher local order and exclusion of solute from the interphase, in parallel with the effect of surface density on the partitioning and local order. The logarithm of the interphase/water partition coefficient for spherical solutes decreases linearly with solute volume. This is also an excellent approximation for elongated solutes because of the relatively weak dependence of solute partitioning on molecular shape. The slope is equal to (2p perpendicular - p parallel)/3KBT, where p parallel is the normal pressure component, and different from that predicted by the mean-field lattice theory. Finally, the lattice theory has been extended herein to incorporate an additional constraint on chain packing in the interphase and to account for the effect of solute size on partitioning.",1
"Xiang, T X, Anderson, B D",2
The temperature-composition phase diagram of monomyristolein in water: equilibrium and metastability aspects.,0
"The temperature-composition phase diagram of monomyristolein in water was constructed using x-ray diffraction. Low- and wide-angle diffraction patterns were collected from samples of fixed hydration as a function of temperature in the heating direction on x-ray-sensitive film and/or image plates. The phases identified in the system include the lamellar crystalline phase, the lamellar liquid crystalline phase, the fluid isotropic phase, and two inverted cubic phases. Particular attention has been devoted to the issues of phase equilibrium and phase boundary verification. Cubic phase undercooling was examined by adjusting the temperature of several samples in the cubic phase to a value where the lamellar liquid crystalline phase represents equilibrium behavior. Cooling-induced structure and phase changes were monitored continuously over a 30-min period by recording low-angle diffraction patterns from the samples using a streak camera. The cubic-to-lamellar transition rate decreased with increasing sample hydration. Additionally, the transition proceeded more rapidly at an incubation temperature of 25 degrees C compared to that at 0 degrees C. A mechanism is proposed that accounts for the hydration and temperature sensitivity of the phase transition under nonequilibrium conditions.",1
"Briggs, J, Caffrey, M",2
Reduction-of-dimensionality kinetics at reaction-limited cell surface receptors.,0
"It has been suggested for several years that reactions between ligands and cell surface receptors can be speeded up by nonspecific adsorption of the ligand to the cell surface followed by two-dimensional surface diffusion to the receptor, a mechanism referred to as ""reduction-of-dimensionality"" (RD) rate enhancement. Most of the theoretical treatments of this and related problems have assumed that the receptor is an irreversibly absorbing perfect sink. Such receptors induce a depletion zone of ligand probability density around themselves. The reaction rate in this case (called ""diffusion-limited"") is limited only by the time required for ligands to diffuse through this depletion zone. In some cases, however, the receptor may be far from ""perfect"" such that a collision with a ligand only rarely leads to binding. Receptors then do not create significant local depletion zones of ligand probability density, and the reaction rate becomes strongly affected by the (small) probability of reaction success per diffusive encounter (the ""reaction-limited"" case). This article presents a simple theory of RD rate enhancement for reaction-limited receptors that are either reversible or irreversible binders. In contrast to the diffusion-limited theories, the reaction-limited theory presented here: (a) differs quantitatively from diffusion-limited models; (b) is simple and algebraic in closed form; (c) exhibits significant rate enhancement in some realistic cases; (d) depends strongly on the actual Brownian rather than pure diffusive nature of the ligand's motion; (e) depends (for irreversibly binding receptors only) on the kinetic rates (not just equilibria) of reversible adsorption to nontarget regions, in contrast to some previous approximate theories of reduction of dimensionality; and (f) is applicable to actual ligand/receptor systems with binding success probabilities at the opposite extreme from the perfect sink/diffusion-limited models.",1
"Axelrod, D, Wang, M D",2
Solutions for transients in arbitrarily branching cables: IV. Nonuniform electrical parameters.,0
"Solutions for transients in arbitrarily branching passive cable neurone models with a soma are extended to models with nonuniform electrical parameters and multiple dendritic shunts. The response to an injected current can again be represented as an infinite series of exponentially decaying components with system time constants obtained from the roots of a recursive transcendental equation. The reciprocity relations and global parameter dependencies are the same as for uniform models. Infinitely many ""raw"" electro-morphological models map onto a given ""core"" electrotonic model; local as well as global raw parameter trade-offs are now possible. The solutions are illustrated by means of biologically relevant examples: (i) the effects of nonuniform electrical parameters in a two-cylinder + soma cortical pyramidal cell model, (ii) the errors that can occur when uniformity is incorrectly assumed in a single cylinder model, (iii) nonsumming interactions between cells and electrodes that can dramatically increase the duration of the effective capacitative electrode artefact, and (iv) shunting inhibition and double impalements in a hippocampal CA1 pyramidal cell ""cartoon"" representation. These solutions should complement compartmental modelling techniques.",1
"Major, G, Evans, J D",2
Molecular dynamics simulations of oxidized and reduced Clostridium beijerinckii flavodoxin.,0
"Molecular dynamics simulations of oxidized and reduced Clostridium beijerinckii flavodoxin in water have been performed in a sphere of 1.4-nm radius surrounded by a restrained shell of 0.8 nm. The flavin binding site, comprising the active site of the flavodoxin, was in the center of the sphere. No explicit information about protein-bound water molecules was included. An analysis is made of the motional characteristics of residues located in the active site. Positional fluctuations, hydrogen bonding patterns, dihedral angle transitions, solvent behavior, and time-dependent correlations are examined. The 375-ps trajectories show that both oxidized and reduced protein-bound flavins are immobilized within the protein matrix, in agreement with earlier obtained time-resolved fluorescence anisotropy data. The calculated time-correlated behavior of the tryptophan residues reveals significant picosecond mobility of the tryptophan side chain located close to the reduced isoalloxazine part of the flavin.",1
"Leenders, R, van Gunsteren, W F, Berendsen, H J, Visser, A J",2
Mutations in the M4 domain of Torpedo californica acetylcholine receptor dramatically alter ion channel function.,0
"Site-directed mutagenesis was used to mutate alpha Cys418 and beta Cys447 in the M4 domain of Torpedo californica acetylcholine receptor expressed in Xenopus laevis oocytes. The M4 region is a transmembrane domain thought to be located at the lipid-protein interface. By whole-cell voltage clamp analysis, mutation of both alpha subunits to alpha Trp418 increased maximal channel activity approximately threefold, increased the desensitization rate compared with wild-type receptor, and shifted the EC50 for acetylcholine from 32 microM to 13 microM. Patch measurements of single-channel currents revealed that the alpha Trp418 increased channel open times approximately 28-fold at 13 degrees C with no effect on channel conductance. All of our measured functional changes in the alpha Trp418 mutant are consistent with a simple kinetic model of the acetylcholine receptor in which only the channel closing rate is altered by the mutation. Our results show that changes in protein structure at the putative lipid-protein interface can dramatically affect receptor function.",1
"Lee, Y H, Li, L, Lasalde, J, Rojas, L, McNamee, M, Ortiz-Miranda, S I, Pappone, P",2
Permeation of Na+ through open and Zn(2+)-occupied conductance states of cardiac sodium channels modified by batrachotoxin: exploring ion-ion interactions in a multi-ion channel.,0
"Mammalian heart sodium channels inserted into planar bilayers exhibit a distinctive subconductance state when single batrachotoxin-modified channels are exposed to external Zn2+. The current-voltage behavior of the open state and the Zn(2+)-induced substate was characterized in the presence of symmetrical Na+ ranging from 2 to 3000 mM. The unitary conductance of the open state follows a biphasic dependence on [Na+] that can be accounted for by a 3-barrier-2-site model of Na+ permeation that includes double occupancy and Na(+)-Na+ repulsion. The unitary conductance of the Zn2+ substate follows a monophasic dependence on [Na+] that can be explained by a similar 3-barrier-2-site model with low affinity for Na+ and single occupancy due to repulsive interaction with a Zn2+ ion bound near the external entrance to the pore. The apparent association rate of Zn2+ derived from dwell-time analysis of flickering events is strongly reduced as [Na+] is raised from 50 to 500 mM. The apparent dissociation rate of Zn2+ is also enhanced as [Na+] is increased. While not excluding surface charge effects, such behavior is consistent with two types of ion-ion interactions: 1) A competitive binding interaction between Zn2+ and Na+ due to mutual competition for high affinity sites in close proximity. 2) A noncompetitive, destabilizing interaction resulting from simultaneous occupancy by Zn2+ and Na+. The repulsive influence of Zn2+ on Na+ binding in the cardiac Na+ channel is similar to that which has been proposed to occur between Ca2+ and Na+ in structurally related calcium channels. Based on recent mutagenesis data, a schematic model of functionally important residues in the external cation binding sites of calcium channels and cardiac sodium channels is proposed. In this model, the Zn(2+)-induced subconductance state results from Zn2+ binding to a site in the external vestibule that is close to the entrance of the pore but does not occlude it.",1
"Schild, L, Moczydlowski, E",2
Transverse distance between the membrane and the agonist binding sites on the Torpedo acetylcholine receptor: a fluorescence study.,0
"Fluorescence dipolar resonance energy transfer between a receptor-bound fluorescent agonist, dansyl-C6-choline, and two membrane-partitioned fluorescent probes, C18-rhodamine and C12-eosin, was used to measure the transverse distance between the acetylcholine (ACh) binding sites on the intact Torpedo nicotinic acetylcholine receptor (nAChR) and the surface of the lipid membrane. Control experiments demonstrated that: (1) dansyl-C6-choline binds to cobra-alpha-toxin sensitive sites on the nAChR with a KD approximately 20 nM, (2) the quantum yield of dansyl-C6-choline increases 3.1-fold upon binding, and (3) the receptor-bound dansyl-C6-choline fluorescence is stable for at least 2 h. The calculated transverse distances between receptor-bound dansyl-C6-choline and the membrane-partitioned acceptors, C12-eosin and C18-rhodamine, were 31 and 39 A, respectively. Therefore, given the dimensions of the extracellular domain of the receptor, the ACh binding sites are located significantly below (approximately 25 A) the extracellular apex of the nAChR. These results are in agreement with the recent proposed location for the ACh binding sites in a pocket within each of the two alpha-subunits, approximately 30 A above the membrane surface (Unwin, N. (1993) J. Mol. Biol. 229: 1101-1124).",1
"Valenzuela, C F, Weign, P, Yguerabide, J, Johnson, D A",2
Theory for establishing proximity relations in biological membranes by excitation energy transfer measurements.,0
"In a previous publication (Shaklai et al., 1977a) the present author developed a theory for evaluating proximity relations and surface densities sigma in biological membranes by measurements of excitation energy transfer from a donor attached to a specific site of a membrane protein and an acceptor attached to a specific carbon on a membrane lipid. It was assumed that the protein and lipid are randomly distributed in the plane of the membrane and that the donor and acceptor groups are confined to different planes in the membrane separated by a distance Rp. In this article several aspects of the theory presented in the previous paper are clarified, especially noting that the previous theoretical expressions for the time-dependent and steady state fluorescence intensities assumed that the labeled protein molecule is cylindrically symmetric with the symmetry axis perpendicular to the plane of the membrane and that the donor is positioned on the symmetry axis of the protein. This assumption is also implicitly or explicitly made in subsequent formulations by other investigators. In this article we generalize the theory to include the case where the donor is not on the symmetry axis of the labeled protein. Equations for calculating the time-dependent and steady state fluorescence intensities for this more general case are presented, and methods for applying these theoretical expressions to the analysis of steady state fluorescence intensity data and evaluation of proximity parameters are discussed. It is also shown in this article that the linear relation l/lo = 1 + Kq sigma previously derived for simple analysis of excitation transfer data for the condition rc/Ro 1 can be modified to apply to almost all practical ranges of rc/Ro without much affecting its simplicity in the analysis of experimental data.",1
"Yguerabide, J",2
Cysteines in the Shaker K+ channel are not essential for channel activity or zinc modulation.,0
"We investigated whether the cysteine residues in Shaker potassium (K+) channels are essential for activation and inactivation gating or for modulation of activation gating by external zinc (Zn2+). Mutants of the Shaker K+ channel were prepared in which all seven cysteine residues were replaced (C-less). These changes were made in both wild-type Shaker H4 channels and in a deletion mutant (delta 6-46) lacking N-type (""fast"") inactivation. Replacement of all cysteines left most functional properties of the K+ currents unaltered. The most noticeable difference between the C-less and wild-type currents was the faster C-type inactivation of the C-less channel which could be attributed largely to the mutation of Cys462. This is consistent with the effects of previously reported mutations of nearby residues in the S6 region. There were also small changes in the activation gating of C-less currents. Modulation by external Zn2+ of the voltage dependence and rate of activation gating is preserved in the C-less channels, indicating that none of the cysteines in the Shaker K+ channel plays an important role in Zn2+ modulation.",1
"Boland, L M, Jurman, M E, Yellen, G",2
An improved double vaseline gap voltage clamp to study electroporated skeletal muscle fibers.,0
"An improved voltage clamp with a double vaseline gap chamber was designed to study electroporated skeletal muscle fibers. The new clamp eliminated spike overshock of membrane potential when applying step stimulation occurring in the traditional configuration. It allowed greater consistency in membrane potential distribution. After the intracellular resistances of the fiber segment at the vaseline gap area were compensated, it was possible to change membrane potential more quickly. Using this technique, strong electrical pulses used to mimic the situation of electrical shock can be delivered to the cell membrane by voltage clamp. Transmembrane currents of skeletal muscle cell were simultaneously measured during a high pulsed shock and resolved into different components. Distinct transient changes of the transmembrane current, involving the time courses of the formation of electroporation and their recovery time constants, can be recorded. Because of more even membrane potential distribution and faster response to pulsed membrane potential change, this technique is also suitable for membrane study under physiological conditions.",1
"Chen, W, Lee, R C",2
Virtual electrode effects in myocardial fibers.,0
"The changes in transmembrane potential during a stimulation pulse in the heart are not known. We have used transmembrane potential sensitive dye fluorescence to measure changes in transmembrane potential along fibers in an anisotropic arterially perfused rabbit epicardial layer. Cathodal or anodal extracellular point stimulation produced changes in transmembrane potential within 60 microns of the electrode that were positive or negative, respectively. The changes in transmembrane potential did not simply decrease to zero with increasing distance, as would occur with a theoretical fiber space constant, but instead became reversed beyond approximately 1 mm from the electrode consistent with a virtual electrode effect. Even stimulation from a line of terminals perpendicular to the fibers produced negative changes in transmembrane potential for cathodal stimulation with the largest negative changes during a 50-ms pulse at 3-4 mm from the electrode terminals. Negative changes as large as the amplitude of the action potential rising phase occurred during a 50-ms pulse for 20-volt cathodal stimulation. Switching to anodal stimulation reversed the directions of changes in transmembrane potential at most recording spots, however for stimulation during the refractory period negative changes in transmembrane potential were significantly larger than positive changes in transmembrane potential. Anodal stimulation during diastole with 3-ms pulses produced excitation in the region of depolarization that accelerated when the stimulation strength was increased to > 3 times the anodal threshold strength. Thus, virtual electrode effects of unipolar stimulation occur in myocardial fibers, and for sufficiently strong stimuli the virtual electrode effects may influence electrical behavior of the myocardium.",1
"Knisley, S B, Hill, B C, Ideker, R E",2
Direct evidence of induction of interdigitated gel structure in large unilamellar vesicles of dipalmitoylphosphatidylcholine by ethanol: studies by excimer method and high-resolution electron cryomicroscopy.,0
"Interaction of large unilamellar vesicle (LUV) of dipalmitoylphosphatidylcholine (DPPC) with ethanol was investigated by the excimer method developed by Yamazaki et al. (Yamazaki, M., M. Miyazu, and T. Asano. 1992. Biochim. Biophys. Acta. 1106:94-98) and the high-resolution electron cryomicroscope with a new cryostage (top-entry superfluid stage) (HiRECM) developed by Fujiyoshi, Y. et al. (Fujiyoshi, Y., T. Mizusaki, K. Morikawa, H. Aoki, H. Kihara, and Y. Harada. 1991. Ultramicroscopy. 38:241-251). The excimer method is based on the fact that the ratio of excimer to monomer fluorescence intensity (E/M) of pyrene PC is lowered in the membrane in the interdigitated gel structure (L beta I), because structural restriction of L beta I structure largely decreases collisions of pyrene rings of the pyrene PCs in the membrane. E/M of pyrene PC in DPPC LUV decreased largely at high concentrations of ethanol, which indicated the induction of L beta I structures in DPPC LUV. Frozen-hydrated DPPC LUVs in a vitreous ice were observed at 4K with HiRECM, and these images were characterized by a pair of concentric circles. The membrane thickness of DPPC LUV which was estimated from the distance between the two concentric lines decreased largely at high concentration of ethanol. The mean value of membrane thickness of the LUV in the absence of ethanol was 3.8 nm, while at 15% (w/v) ethanol was 3.0 nm. These values were almost same as those obtained from the electron density profile of DPPC MLV by the x-ray diffraction analysis in each structures, L beta' and L beta I structures, respectively. These results indicated directly the induction of L beta 1 structure in DPPC LUV at high concentration of ethanol.",1
"Yamazaki, M, Miyazu, M, Asano, T, Yuba, A, Kume, N",2
Differential scanning calorimetry and X-ray diffraction studies of the thermotropic phase behavior of the diastereomeric di-tetradecyl-beta-D-galactosyl glycerols and their mixture.,0
"We have investigated the thermotropic phase behavior of aqueous dispersions of the 1,2- and 2,3-di-O-tetradecyl-1(3)-O-(beta-D-galactopyranosyl)-sn- glycerols and their diastereomeric mixture using differential scanning calorimetry and low-angle and wide-angle x-ray diffraction. Upon heating, unannealed aqueous dispersions of these compounds all exhibit a lower temperature, moderately energetic phase transition at approximately 52 degrees C and a higher temperature, weakly energetic phase transition at approximately 63 degrees C, both of which are reversible on cooling. X-ray diffraction measurements identify these events as the L beta (or L' beta)/L alpha and L alpha/HII phase transitions, respectively. The structures of the L beta, L alpha, and HII phases of these lipids, as determined by x-ray diffraction measurements, are identical within the error bars for all of these lipids. On annealing below the L beta/L alpha phase transition temperature, the L beta phase converts to an Lc phase at a rate which is strongly dependent on the chirality of the glycerol backbone (1,2-sn > 1,2-rac > 2,3-sn). The temperature of the phase transition from the Lc phase seen on reheating is also dependent on the glycerol chirality. In addition, the nature of the Lc phase changes on subsequent heating in the 1,2-sn and 1,2-rac lipids, but we have not been able to detect this Lc1/Lc2 phase transition by calorimetry. However, wide-angle x-ray diffraction measurements indicate that these Lc phases differ mostly in their hydrocarbon chain packing modes. The Lc2 phase does not appear to be present in the 2,3-sn compound, suggesting that its formation is not favored in this diastereomeric isomer. These observations are discussed in relation to the effect of glycerol chirality on the molecular packing of these glycolipids, particularly on hydrogen bonding and hydration in the interfacial region of the bilayer.",1
"Mannock, D A, McElhaney, R N, Harper, P E, Gruner, S M",2
Comparative differential scanning calorimetric and FTIR and 31P-NMR spectroscopic studies of the effects of cholesterol and androstenol on the thermotropic phase behavior and organization of phosphatidylcholine bilayers.,0
"We have investigated the comparative effects of the incorporation of increasing quantities of androstenol and cholesterol on the thermotropic phase behavior of aqueous dispersions of members of a homologous series of linear saturated diacyl PCs1 using high sensitivity DSC. We have also employed FTIR and 31P-NMR spectroscopy to study the comparative effects of androstenol and cholesterol incorporation on the organization of the host PC bilayer in both the gel and liquid-crystalline states. The effects of androstenol and cholesterol incorporation on the thermotropic phase behavior of shorter chain PCs like 14:0 PC are generally similar but not identical. The incorporation of either sterol progressively decreases the temperature and enthalpy, but not the cooperativity, of the pretransition and completely abolishes it at sterol concentrations above 5 mol%. Moreover, at sterol concentrations of 1 to 20-25 mol%, both androstenol and cholesterol incorporation produce DSC endotherms consisting of superimposed sharp and broad components, the former due to the hydrocarbon chain melting of sterol-poor and the latter to the melting of sterol-rich 14:0 PC domains. The temperature and cooperativity of the sharp component are reduced slightly with increasing concentration of androstenol or cholesterol, and the enthalpy of the sharp component decreases progressively and becomes zero at 20-25 mol% sterol. As well, at cholesterol or androstenol concentrations above 20-25 mol%, the enthalpy of the broad component also decreases linearly with increasing sterol incorporation and becomes zero at sterol levels of about 50 mol%. However, whereas cholesterol incorporation progressively increases the temperature of the broad component of the DSC endotherm, androstenol incorporation decreases the temperature of this component. In contrast, the effects of androstenol and cholesterol incorporation on the thermotropic phase behavior of the intermediate and longer chain PCs studied here are considerably different. Although the incorporation of cholesterol increases the main phase transition temperature of 16:0 PC slightly and decreases the phase transition of 18:0 PC and 21:0 PC, androstenol incorporation decreases the main phase transition temperatures of all three PCs rather markedly. Moreover, androstenol is less effective in reducing the enthalpy and cooperativity of the broad component of the DSC endotherm of 16:0 PC and especially 18:0 PC bilayers in comparison to cholesterol. Androstenol incorporation (> 5 mol%) also results in the appearance of a second, low temperature endotherm in the DSC traces of the intermediate and longer chain PC dispersions that is not observed in similar cholesterol/PC dispersions. FTIR and 31P-NMR results suggest that this endotherm arises from a temperature-induced dissolution of androstenol in the gel phase PC bilayers. This second endotherm occurs at lower androstenol concentrations and increases in area at a given androstenol level as the chain length of the host PC bilayer increases. We ascribe the increasing immiscibility of androstenol in both the gel and liquid-crystalline states of PC bilayers of increasing thickness to an increasing degree of hydrophobic mismatch between the androstenol molecule and the host phospholipid bilayer.",1
"McMullen, T P, Lewis, R N, McElhaney, R N",2
Electrochemical measurements of the lateral diffusion of electroactive amphiphiles in supported phospholipid monolayers.,0
"Chronocoulometry was used to characterize the fluidity and lateral diffusion coefficient of supported phospholipid bilayer assemblies. The bilayers were formed on the inner surfaces of the microporous template films of aluminum oxide on gold electrodes. The lipid monolayers were formed by adsorption and fusion of phospholipid vesicles on alkylated oxide surfaces. Octadecyltrichlorosilane (OTS) was used in the initial alkylation step. The surface concentration of the lipids in monolayer assemblies was measured by a radioactive assay method. Surface densities corresponding to 48 +/- 10 A2/molecule (DPPC) and 56 +/- 11 A2/molecule (DMPC) were obtained (for exposure times > 120 min) independent of the temperature of the vesicle's fusion (below or above chain-melting transition). Octadecylviologen (C18MV2+) was used as an electroactive probe species. Its limiting lateral diffusion coefficient in DMPC monolayers was 5 x 10(-8) cm2/s, measured as C18MV2+ mole fraction extrapolated to 0 decreasing linearly from 20 to below 1 mol%. Linear Arrhenius plots for C18MV2+ diffusion in DMPC monolayers were obtained with slopes of approximately 40 kJ/mol between 18 and 45 degrees C, demonstrating homogeneity and fluidity of the lipid monolayers. Chronocoulometry was also used to obtain lateral diffusion coefficient of ubiquinone in DMPC/OTS bilayers. A value of 1.9 x 10(-8) cm2/s at 30 degrees C was obtained.",1
"Torchut, E, Laval, J M, Bourdillon, C, Majda, M",2
Cholesterol modifies water concentration and dynamics in phospholipid bilayers: a fluorescence study using Laurdan probe.,0
"The effect of cholesterol on the gel, the liquid-crystalline, and mixed phospholipid phases has been studied using the fluorescence properties of 2-dimethylamino-6-lauroylnaphthalene (Laurdan). Laurdan sensitivity to the polarity and to the dynamics of its environment reveals that cholesterol affects phospholipid bilayers in the gel phase by expelling water and by increasing the amount of dipolar relaxation. In the liquid-crystalline phase, the effect of cholesterol is a reduction of both water concentration and amount of dipolar relaxation. Detailed studies of Laurdan excitation and emission spectral contours as a function of cholesterol concentration show that there are some cholesterol concentrations at which Laurdan spectral properties changes discontinuously. These peculiar cholesterol concentrations are in agreement with recent observations of other workers showing the formation of local order in the liquid-crystalline phase of phospholipids upon addition of phospholipid derivatives of pyrene. A local organization of phospholipids around cholesterol molecule seems to be produced by the presence of peculiar concentrations of cholesterol itself. This local organization is stable enough to be observed during the excited state lifetime of Laurdan of approximately 5-6 ns.",1
"Parasassi, T, Di Stefano, M, Loiero, M, Ravagnan, G, Gratton, E",2
Movement of single myosin filaments and myosin step size on an actin filament suspended in solution by a laser trap.,0
"Movement of single myosin filaments, synthesized by copolymerization of intact myosin and fluorescently labeled light meromyosin, were observed along a single actin filament suspended in solution by a dual laser trap in a fluorescence microscope. The sliding velocity of the myosin filaments was 11.0 +/- 0.2 micron/s at 27 degrees C. This is similar to that of actin moving toward the center from the tip (the physiological direction) of myosin filaments bound to a glass surface but several times larger than that in the opposite direction (Ishijima and Yanagida, 1991; Yanagida, 1993). This indicates that the movement of myosin filaments is dominated by the myosin heads on one side of the myosin filament, which are correctly oriented relative to the actin filament. The incorrectly oriented myosin heads on the other side do not interfere with the fast movement. The step size (displacement produced during one ATPase cycle) of correctly oriented myosin was estimated from the minimum number of myosin heads necessary to produce the maximum velocity. This was determined by measuring the velocities of various lengths of myosin filaments. The minimum length of the myosin filaments moving near the maximum velocity was 0.30-0.40 microns, which contains 20 +/- 5 correctly oriented myosin heads. This number leads to a myosin step size of 71 +/- 22 nm. This value probably represents the lower limit, because all of the myosin heads on the filament would not always interact with the actin filament. Thus, the myosin step size is considerably larger than the length of a power stroke expected from the physical size of a myosin head, 10-20 nm (Huxley, 1957, 1969).",1
"Saito, K, Aoki, T, Aoki, T, Yanagida, T",2
A model of the release of myosin heads from actin in rapidly contracting muscle fibers.,0
"We describe a model that relates the maximum shortening velocity of a muscle fiber, Vm, to the kinetics of the dissociation of a myosin head from actin. At Vm, the positive work exerted by cross-bridges attached in the powerstroke must be balanced by cross-bridges that have been carried by movement of the filaments into a region where they exert a negative force. This balance allows one to relate Vm and the rate of cross-bridge detachment. Studies of actomyosin kinetics suggest that at high substrate, detachment should be limited by a slow protein isomerization (approximately 50 s-1) that precedes ADP release. This rate is too slow to be easily accommodated in existing models. However, a slow rate for cross-bridge dissociation, similar to that of the isomerization, is predicted if previous models are modified to include rapid detachment of cross-bridges that have been carried so far into the negative force region that their free energy exceeds that of the detached state. The model also explains another aspect of muscle contraction: at high shortening velocities, the observed rate of ATP hydrolysis is low, because a cross-bridge can interact with multiple actin binding sites before releasing the hydrolysis products and binding another ATP.",1
"Cooke, R, White, H, Pate, E",2
"Oxygen exchange in the isolated, arrested guinea pig heart: theoretical and experimental observations.",0
"A model of oxygen transport in perfused myocardial tissue is presented. Steady-state conditions are assumed in order to mimic the metabolic rate of the arrested heart. The model incorporates Michaelis-Menten dependence of mitochondrial oxygen consumption, oxymyoglobin saturation and oxyhemoglobin saturation on oxygen partial pressure (PO2). The transport equations model both the advective supply of oxygen via the coronary circulation and the diffusive exchange of oxygen between tissues and environment across the epicardial and endocardial surfaces. The left ventricle is approximated by an axisymmetric prolate spheroid and the transport equations solved numerically using finite element techniques. Solution yields the PO2 profile across the heart wall. Integration of this profile yields the simulated rate of metabolic oxygen uptake determined according to the Fick principle. Correction for the diffusive flux of oxygen across the surfaces yields the simulated true metabolic rate of oxygen consumption. Simulated values of oxygen uptake are compared with those measured experimentally according to the Fick principle, using saline-perfused, Langendorff-circulated, K(+)-arrested, guinea pig hearts. Four perfusion variables were manipulated: arterial PO2, environmental PO2, coronary flow and perfusion pressure. In each case agreement between simulated and experimentally determined rates of oxygen consumption gives confidence that the model adequately describes the advective and diffusive transport of oxygen in the isolated, arrested, saline-perfused heart.",1
"Mawson, D A, Hunter, P J, Kenwright, D N, Loiselle, D S",2
Cross-linker dynamics determine the mechanical properties of actin gels.,0
"To evaluate the contributions of cross-linker dynamics and polymer deformation to the frequency-dependent stiffness of actin filament gels, we compared the rheological properties of actin gels with three types of cross-linkers: a weak one, Acanthamoeba alpha-actinin (dissociation rate constant 5.2 s-1, association rate constant 1.1 x 10(6) M-1 s-1); a strong one, chicken smooth muscle alpha-actinin (dissociation rate constant 0.66 s-1, association rate constant 1.20 x 10(6) M-1 s-1); and an extremely strong one, biotin/avidin (dissociation rate constant approximately zero). The biotin/avidin cross-linked gel, whose behavior is determined by polymer bending alone, behaves like a solid and shows no frequency dependence. The amoeba alpha-actinin cross-linked gel behaves like a viscoelastic fluid, and the frequency dependence of the stiffness can be explained by a mathematical model for dynamically cross-linked gels. The stiffness of the chicken alpha-actinin cross-linked gel is independent of frequency, and has viscoelastic properties intermediate between the two. The two alpha-actinins have similar association rate constants for binding to actin filaments, consistent with a diffusion-limited reaction. Rigid cross-links make the gel stiff, but make it elastic without the ability to deform permanently. Dynamically cross-linked actin filaments should allow the cell to react passively to various outside forces without any sort of signaling. Slower, signal-mediated pathways, such as severing filaments or changing the affinity of cross-linkers, could alter the nature of these passive reactions.",1
"Wachsstock, D H, Schwarz, W H, Pollard, T D",2
A mechanochemical study of MgDNA fibers in ethanol-water solutions.,0
"Highly oriented calf-thymus MgDNA fibers, prepared by a wet spinning method, were studied with a simple mechanochemical set-up. The relative fiber length, L/Lo, was measured with the fibers submerged in ethanol-water solutions. In one type of experiment L/Lo was measured as a function of ethanol concentration at room temperature. No substantial decrease in L/Lo with increasing ethanol concentration was observed, indicating that MgDNA fibers stay in the B form even when the water activity is very low. For low ethanol concentrations the fiber structure is stable and does not dissolve even at very high water activities. In a second type of experiment, the heat-induced helix-coil transition was manifested by a marked contraction of the fibers. The transition temperature decreases linearly with increasing ethanol concentration between 52 and 68% ethanol. At higher ethanol concentrations the helix-coil transition temperature increases due to strong aggregation within the DNA fibers, and above 77% ethanol the fibers do not contract at all, not even at the upper temperature limit of the experiments, approximately 80 degrees C. This behavior is discussed with reference to dried DNA and the P form of DNA. The helix-coil transition temperature of the MgDNA fibers in 70% ethanol does not show any dependence on the MgCl2 concentration. It is shown that the Poisson-Boltzmann cylindrical cell model can account qualitatively for this lack of salt dependence.",1
"Schultz, J, Rupprecht, A, Song, Z, Piskur, J, Nordenskiöld, L, Lahajnar, G",2
Premelting base pair opening probability and drug binding constant of a daunomycin-poly d(GCAT).poly d(ATGC) complex.,0
We calculate room temperature thermal fluctuational base pair opening probability of a daunomycin-poly d(GCAT).poly d(ATGC) complex. This system is constructed at an atomic level of detail based on x-ray analysis of a crystal structure. The base pair opening probabilities are calculated from a modified self-consistent phonon approach of anharmonic lattice dynamics theory. We find that daunomycin binding substantially enhances the thermal stability of one of the base pairs adjacent the drug because of strong hydrogen bonding between the drug and the base. The possible effect of this enhanced stability on the drug inhibition of DNA transcription and replication is discussed. We also calculate the probability of drug dissociation from the helix based on the selfconsistent calculation of the probability of the disruption of drug-base H-bonds and the unstacking probability of the drug. The calculations can be used to determine the equilibrium drug binding constant which is found to be in good agreement with observations on similar daunomycin-DNA systems.,1
"Chen, Y Z, Prohofsky, E W",2
Kinetics of chromosome condensation in the presence of topoisomerases: a phantom chain model.,0
"We discuss the requirement of type II DNA topoisomerase in the process of mitotic chromosome condensation. Using a known model describing the collapse of homopolymers, we propose that the compaction process necessitates a change in the topological state (i.e., a self-knotting) of the chromosomal chain. We argue that the enzymes are necessary to reach the compact metaphase state in a time interval that is much smaller than the time expected in the uncatalyzed process. The folding process is such that the potential entanglement points are localized at particular regions of the chromosome known as the scaffold-associated regions. The concentration of entanglements in the metaphase chromosome is related to the average size of the radial loops. A phantom chain model for the condensation process, in which each potential entanglement point is dealt with by a topoisomerase II molecule, is proposed.",1
"Sikorav, J L, Jannink, G",2
Photoinduced volume changes associated with the early transformations of bacteriorhodopsin: a laser-induced optoacoustic spectroscopy study.,0
"Volume changes associated with the primary photochemistry of bacteriorhodopsin (BR) were measured by temperature-dependent laser-induced optoacoustic spectroscopy (LIOAS). Excitation was performed with 8-ns flashes establishing a photoequilibrium between the BR and the K states (BR<-->hvK). The concentration of K at the end of the laser pulse, which is an important parameter for the calculation of the volume change per molecule from the LIOAS data, was determined by flash photolysis with optical detection under the specific conditions (concentration, photon density) of the LIOAS experiment. Temperature-dependent measurements yielded a linear dependency of the ratio of the optoacoustic signals for BR and for a calorimetric reference (CoCl2) with the cubic thermal expansion coefficient beta of water. From the slope of this linear ratio a contraction of 11 cm3/mol was determined.",1
"Schulenberg, P J, Rohr, M, Gärtner, W, Braslavsky, S E",2
Excited state dynamics in chlorophyll-based antennae: the role of transfer equilibrium.,0
"We present computer simulations of excited state dynamics in models of PS I and PS II which are based upon known structural and spectral properties of the antennae. In particular, these models constrain the pigment binding sites to three-dimensional volumes determined from molecular properties of the antenna complexes. The simulations demonstrate that within a 10-30 ps after light absorption, rapid energy transfer among coupled antenna chlorophylls leads to a quasiequilibrium state in which the fraction of the excited state on any antenna chlorophyll, normalized to the total excited state remaining on the model, remains constant with time. We describe this quasiequilibrium state as a ""transfer equilibrium"" (TE) state because of its dependence on the rates of processes that couple excited state motion and quenching in the antenna as well as on the individual antenna site energies and temperature. The TE state is not a true equilibrium in that loss of the excited state primarily due to photochemistry (but also due to fluorescence, thermal emission, and intersystem crossing) continues once TE is established. Depending on the dynamics of the system, the normalized distribution of excited state at TE may differ substantially from the Boltzmann distribution (the state of the model at infinite time in the absence of any avenues for decay of excited state). The models predict lifetimes, equilibration times, and photochemical yields that are in agreement with experimental data and affirm trap-limited dynamics in both photosystems. The rapid occurrence of TE states implies that any excited state dynamics that depends on antenna structure and excitation wavelength must occur before the TE state is established. We demonstrate that the excited state distribution of the TE state is central to determining the excited state lifetime and quantum efficiency of photochemistry.",1
"Laible, P D, Zipfel, W, Owens, T G",2
Light scattering by bovine alpha-crystallin proteins in solution: hydrodynamic structure and interparticle interaction.,0
"We have studied diluted bovine eye lens alpha-crystallin solutions by using light scattering. The protein particles were modeled as hard spheres, showing electrostatic repulsion, due to surplus electric charges, and weak attractive interaction. The repulsive potential VR is defined by the radius of the particles, the Debye length kappa-1, and the number of charges at the Gouy layer; the attractive potential has been described by the London-van der Waals potential and is defined by the Hamaker constant A. We have used the diluted gas approximation and the one component macrofluid model to relate the experimental static factor Ki to the theoretical expression of the interaction potential V(x). This resulted in a Hamaker constant A of 0.06 +/- 0.01 KBT and an effective charge q ranging from 18 +/- 1 at low ionic strength (omega = 0.0022 M) to 50 +/- 5 at high ionic strength (omega = 0.1472 M).",1
"Xia, J Z, Aerts, T, Donceel, K, Clauwaert, J",2
"A novel method for rapid measurement of membrane resistance, capacitance, and access resistance.",0
"During patch clamp recordings, measurement of passive parameters such as access resistance (Ra), membrane resistance (Rm), and membrane capacitance (Cm) often provides useful information regarding physiological changes in the cell. In particular, an increase in capacitance may indicate vesicle fusion events as occurs during exocytosis. Rapid capacitance changes are usually measured with a phase-sensitive detector set to a phase angle that is independent of resistance changes. However, this angle changes over time and may be difficult to determine in cells with a low membrane resistance. The present paper describes a technique for rapidly measuring Ra, Rm, and Cm by simultaneously applying two harmonic frequencies and calculating the passive parameters from the resultant electrode current. Calibration and operation are independent of the compensation circuit settings that may be set to null most of the electrode current. The technique may be implemented on a standard patch clamp setup without other specialized equipment and should be particularly useful for the study of cells that have low Rm or undergo rapid changes in Ra or Rm.",1
"Donnelly, D F",2
Stationary and nonstationary correlation-frequency analysis of heterodyne mode laser light scattering: magnitude and periodicity of canine tracheal ciliary beat frequency in vivo.,0
"Stationary and nonstationary correlation-frequency analysis of heterodyne laser light scattering were utilized to make automated, on-line, objective measurements of tracheal ciliary beat frequency (CBF) in intact, anesthetized canines. The stationary correlation-frequency analysis laser light-scattering technique was used to assess the magnitude of the CBF stimulatory responses induced by aerosolized 10(-5) M fenoterol (sympathomimetic), and 10(-8) M and 10(-6) M methacholine (parasympathomimetic) delivered to the whole lungs of eight barbiturate-anesthetized beagles. The nonstationary correlation-frequency analysis laser light-scattering technique was used to measure the effect on tracheal CBF of increasing the cytosolic calcium ion concentration with a calcium ionophore, A23187. Aerosolized A23187 was delivered to the isolated tracheal lumens of eight beagle dogs in cumulative doses ranging from 10(-9)M to 10(-6) M. Administration of the ionophore synchronized the CBF with a period of 5.3 min. Dose dependencies were observed in both the time to the peak CBF stimulation and the magnitude of the stimulatory response. The magnitude of CBF stimulation was inhibited by prior administration of aerosolized nifedipine (2 mg/ml), a voltage-operated calcium channel blocker. The A23187-induced modulation period of tracheal CBF, was unchanged by nifedipine. These are the first data to demonstrate that the magnitude and periodicity of CBF are two independent coupled processes. The cooperativity of these two processes could be determined in the effectiveness of mucociliary transport.",1
"Chandra, T, Yeates, D B, Miller, I F, Wong, L B",2
Saturation effects in polarized fluorescence photobleaching recovery and steady state fluorescence polarization.,0
"The time-resolved anisotropy produced in polarized fluorescence photobleaching recovery experiments has been successfully used to measure rotational correlation times in a variety of biological systems, however the magnitudes of the reported initial anisotropies have been much lower than the theoretically predicted maximum values. This small time-zero anisotropy has been attributed to fluorophore motion, wobble and rotation, during the photobleaching pulse. We demonstrate that inclusion of the possibility of saturation of the fluorophore's transition from its ground state to its excited state during the photobleaching pulse leads to the prediction of reduced time-zero anisotropy. This eliminates the need to rely solely on the assumption of fluorophore motion during the photobleaching pulse as the cause of the reduced initial anisotropy. We present theoretical and experimental results which show that the initial anisotropy decreases as both the bleach pulse intensity is increased and bleach pulse duration is decreased so as to keep the total integrated bleach pulse constant. We also show theoretical and experimental results demonstrating that at high excitation intensity the effects of saturation cause the steady state fluorescence polarization to decrease. We estimate that saturation may occur using common photobleaching conditions.",1
"Hellen, E H, Burghardt, T P",2
Pre-steady-state transient currents mediated by the Na/K pump in internally perfused Xenopus oocytes.,0
"Pre-steady-state transient currents have been investigated in the vegetal pole of Xenopus oocytes using the open-oocyte vaseline-gap technique of Taglialatela, Toro, and Stefani (Biophysical Journal. 61:78-82, 1992). Voltage pulses 40 ms in duration were made from a holding potential of -40 mV to command potentials over the range -160 to +60 mV in increments of 20 mV. Current records (averaged 20X; sampled every 200 microseconds) in the presence of dihydroouabain (DHO) or absence of external Na+ (Nao) were subtracted from current records obtained under Na/Na exchange conditions, i.e. internally perfused with 50 mM Na+, 5 mM ATP, and 5 mM ADP (K(+)-free) and externally superfused with 100 mM Na+,K(+)-free solution. Transient currents were dependent on intracellular Na+ and nucleotides, and diminished by activation of forward pumping; they were also reduced by 10 micrograms ml-1 of oligomycin B applied to the external solution. These properties of the pre-steady state currents are consistent with the Na/K pump operating in its electroneutral Na/Na exchange mode. The voltage dependence of the DHO- and Nao-sensitive transient currents was analyzed using a pseudo two-state model in which only the rate coefficient for Nao-binding/reocclusion is voltage-dependent (Rakowski, R. F. 1993. J. Gen. Physiol. 101:117-144). The apparent valence of the charge moved during the on (zq-on) and off (zq-off) of the pulse were 0.96 +/- 0.05 and 0.95 +/- 0.05 for Nao-sensitive, and 1.10 +/- 0.07 and 0.85 +/- 0.06 for DHO-sensitive transient currents, respectively. The total amount of charge moved (Qtot) and the mid-point voltage of the charge distribution (Vq) were 230 +/- 15 pC and -56.2 +/- 5.1 mV, and 268 +/- 34 pC and -67.0 +/- 7.6 mV for Nao- and DHO-sensitive transient currents, respectively. The apparent valence (zk) and the voltage at which the forward and backward rates are equal (Vk) obtained from the relaxation rates were 0.80 +/- 0.05 and -129.3 +/- 10.0 mV, and 0.86 +/- 0.10 and -135.1 +/- 9.0 mV for the Nao- and DHO-sensitive pre-steady state currents, respectively. The values of the parameters were not statistically significantly different between the Nao- and DHO-sensitive transient currents. Excluding the first 600 microseconds after the onset of a voltage step which was not temporally resolved, transient currents showed no indication of a rising phase. These results support the idea that charge translocation occurs within an external access channel at a rate that is governed by a voltage-dependent binding/reocclusion process and a voltage-independent deocclusion/unbinding process.",1
"Holmgren, M, Rakowski, R F",2
Orientation of cholera toxin bound to model membranes.,0
"The orientation of cholera toxin bound to its cell-surface receptor, ganglioside GM1, in a supporting lipid membrane was determined by electron microscopy of negatively stained toxin-lipid samples. Image analysis of two dimensional crystalline arrays has shown previously that the B-subunits of cholera toxin orient at the membrane surface as a pentameric ring with a central channel (Reed, R. A., J. Mattai, and G.G. Shipley. 1987. Biochemistry. 26:824-832; Ribi, H. O., D. S. Ludwig, K. L. Mercer, G. K. Schoolnik, and R. D. Kornberg. 1988. Science (Wash, DC). 239:1272-1276). We recorded images of negatively stained cholera toxin and isolated B-pentamers oriented perpendicular to the lipid surface so that the pentamer ring is viewed from the side. The pentamer dimensions, estimated from the average of 100 molecules, are approximately 60 by 30 A. Images of side views of whole cholera toxin clearly show density above the pentamer ring away from the lipid layer. On the basis of difference maps between averages of side views of whole toxin and B-pentamers, this density above the pentamer has been identified as a portion of the A-subunit. The A-subunit may also extend into the pore of the pentamer. In addition, Fab fragments from a monoclonal antibody to the A-subunit were mixed with the toxin prior to binding to GM1. Density from the Fab was localized to the region of toxin above the pentamer ring confirming the location of the A-subunit. The structure determined for the homologous heat-labile enterotoxin from Escherichia coli shows that the A-subunit lies mostly on one face of this pentamer with a small region penetrating the pentamer pore (Sixma, T. K., S. E. Pronk, K. H. Kalk, E. S. Wartna, B. A. M. van Zanten, B. Witholt,and W. G. J. Hol. 1991. Nature (Lond.). 351:371-377). The putative GM1 binding sites are located on the opposite face of the B-pentamer. Cholera toxin, therefore appears to bind to a model membrane with its GM1 binding surface adjacent to the membrane. Low resolution density maps were constructed from the x-ray coordinates of the E. coli toxin and compared with the electron microscopy-derived maps.",1
"Cabral-Lilly, D, Sosinsky, G E, Reed, R A, McDermott, M R, Shipley, G G",2
"Distribution of electrical potential, pH, free Ca2+, and volume inside cultured adult rabbit cardiac myocytes during chemical hypoxia: a multiparameter digitized confocal microscopic study.",0
"Exploiting the optical sectioning capabilities of laser scanning confocal microscopy and using parameter-specific fluorescent probes, we determined the distribution of pH, free Ca2+, electrical potential, and volume inside cultured adult rabbit cardiac myocytes during ATP depletion and reductive stress with cyanide and 2-deoxyglucose (""chemical hypoxia""). During normoxic incubations, myocytes exhibited a cytosolic pH of 7.1 and a mitochondrial pH of 8.0 (delta pH = 0.9 units). Sarcolemmal membrane potential (delta psi) was -80 mV, and mitochondrial delta psi was as high as -100 mV, yielding a mitochondrial protonmotive force (delta p) of -155 mV (delta P = delta psi - 60 delta pH). After 30 min of chemical hypoxia, mitochondrial delta pH decreased to 0.5 pH units, but mitochondrial delta psi remained essentially unchanged. By 40 min, delta pH was collapsed, and mitochondrial and cytosolic free Ca2+ began to increase. Mitochondrial and sarcolemmal delta psi remained high. as Ca2+ rose, myocytes shortened, hypercontracted, and blebbed with a 30% decrease of cell volume. After hypercontraction, extensive mitochondrial Ca2+ loading occurred. After another few minutes, mitochondrial depolarized completely and released their load of Ca2+. After many more minutes, the sarcolemmal permeability barrier broke down, and viability was lost. These studies demonstrate a sequence of subcellular ionic and electrical changes that may underlie the progression to irreversible hypoxic injury.",1
"Chacon, E, Reece, J M, Nieminen, A L, Zahrebelski, G, Herman, B, Lemasters, J J",2
Parametrization of direct and soft steric-undulatory forces between DNA double helical polyelectrolytes in solutions of several different anions and cations.,0
"Directly measured forces between DNA helices in ordered arrays have been reduced to simple force coefficients and mathematical expressions for the interactions between pairs of molecules. The tabulated force parameters and mathematical expressions can be applied to parallel molecules or, by transformation, to skewed molecules of variable separation and mutual angle. This ""toolbox"" of intermolecular forces is intended for use in modelling molecular interactions, assembly, and conformation. The coefficients characterizing both the exponential hydration and the electrostatic interactions depend strongly on the univalent counterion species in solution, but are only weakly sensitive to anion type and temperature (from 5 to 50 degrees C). Interaction coefficients for the exponentially varying hydration force seen at spacings less than 10 to 15 A between surfaces are extracted directly from pressure versus interaxial distance curves. Electrostatic interactions are only observed at larger spacings and are always coupled with configurational fluctuation forces that result in observed exponential decay lengths that are twice the expected Debye-Huckel length. The extraction of electrostatic force parameters relies on a theoretical expression describing steric forces of molecules ""colliding"" through soft exponentially varying direct interactions.",1
"Podgornik, R, Rau, D C, Parsegian, V A",2
Multiphasic desensitization of the GABAA receptor in outside-out patches.,0
"GABAA receptor function was studied in outside-out patches from guinea pig hippocampal neurons using a drug application system with an exchange time of under 1.5 ms. Application of GABA to these patches induced a Cl- conductance that desensitized with prolonged exposure. Increasing GABA concentrations induced larger conductance increases that were associated with more complex patterns of desensitization. Smaller GABA responses desensitized with monophasic kinetics, whereas large responses displayed bi- and triphasic kinetics. Desensitization of the response to 1 mM GABA was triphasic in about 70% of the patches (tau = 15.4, 207, and 1370 ms) and biphasic in about 30% of the patches (tau = 44 and 725 ms). All phases of desensitization reversed at the Cl- equilibrium potential. Over the concentration range from 3 microM to 3 mM, both the rate and the extent of desensitization increased; however, complete desensitization was rarely observed. The increase in desensitization rate was due to an increase in the relative contribution of the faster phases with increasing GABA. The time constants of the three phases were independent of concentration. The different phases are not mediated by separate receptor populations, because double pulse experiments demonstrated interconversion among the fastest phase and the two slower phases. We demonstrate the plausibility of a model in which multiphasic desensitization is a consequence of the faster association rate at higher GABA concentrations.",1
"Celentano, J J, Wong, R K",2
Myelin basic protein interaction with zinc and phosphate: fluorescence studies on the water-soluble form of the protein.,0
"The interaction of myelin basic protein (MBP) with zinc and phosphate ions has been studied by using the emission properties of the single tryptophan residue of the protein (Trp-115). The studies have been carried out by means of both static and time-resolved fluorescence techniques. The addition of either zinc to MBP in the presence of phosphate or phosphate to MBP in the presence of zinc resulted in an increase of fluorescence intensity and a blue shift of the emission maximum wavelength. Furthermore, a concomitant increase in the scattering was also detected. Anisotropy decay experiments demonstrated that these effects are due to the formation of MBP molecules into large aggregates. A possible physiological role for such interaction is discussed.",1
"Cavatorta, P, Giovanelli, S, Bobba, A, Riccio, P, Szabo, A G, Quagliariello, E",2
Measurement of the individual pKa values of acidic residues of hen and turkey lysozymes by two-dimensional 1H NMR.,0
"The pH dependence of the two-dimensional 1H nuclear magnetic resonance spectra of hen and turkey egg-white lysozymes has been recorded over the pH range 1-7. By monitoring the chemical shifts of the resonances of the various protons of ionizable residues, individual pKa values for the acidic residues have been determined for both proteins. The pKa values are displaced, with the exception of those of the residues in the active site cleft, by an average of 1 unit to low pH compared to model compounds.",1
"Bartik, K, Redfield, C, Dobson, C M",2
"Conformational dynamics of bovine Cu, Zn superoxide dismutase revealed by time-resolved fluorescence spectroscopy of the single tyrosine residue.",0
"The structural dynamics of bovine erythrocyte Cu, Zn superoxide dismutase (BSOD) was studied by time-resolved fluorescence spectroscopy. BSOD is a homodimer containing a single tyrosine residue (and no tryptophan) per subunit. Frequency-domain fluorometry revealed a heterogeneous fluorescence decay that could be described with a Lorentzian distribution of lifetimes. The lifetime distribution parameters (center and width) were markedly dependent on temperature. The distribution center (average lifetime) displayed Arrhenius behavior with an Ea of 4.2 kcal/mol, in contrast with an Ea of 7.4 kcal/mol for the single-exponential decay of L-tyrosine. This indicated that thermal quenching of tyrosine emission was not solely responsible for the effect of temperature on the lifetimes of BSOD. The distribution width was broad (1 ns at 8 degrees C) and decreased significantly at higher temperatures. Furthermore, the width of the lifetime distribution increased in parallel to increasing viscosity of the medium. The combined effects of temperature and viscosity on the fluorescence decay suggest the existence of multiple conformational substrates in BSOD that interconvert during the excited-state lifetime. Denaturation of BSOD by guanidine hydrochloride produced an increase in the lifetime distribution width, indicating a larger number of conformations probed by the tyrosine residue in the denatured state. The rotational mobility of the tyrosine in BSOD was also investigated. Analysis of fluorescence anisotropy decay data enabled resolution of two rotational correlation times. One correlation time corresponded to a fast (picosecond) rotation that contributed 62% of the anisotropy decay and likely reported local mobility of the tyrosine ring. The longer correlation time was 50% of the expected value for rotation of the whole (dimeric) BSOD molecule and appeared to reflect segmental motions in the protein in addition to overall tumbling. Comparison between rotational correlation times and fluorescence lifetimes of BSOD indicates that the heterogeneity in lifetimes does not arise from mobility of the tyrosine per se, but rather from dynamics of the protein matrix surrounding this residue which affect its fluorescence decay.",1
"Ferreira, S T, Stella, L, Gratton, E",2
Effect of ATP concentration on CFTR Cl- channels: a kinetic analysis of channel regulation.,0
"Phosphorylated cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels require nucleoside triphosphates, such as ATP, to open. As the concentration of intracellular ATP increases, the probability of the channel being open (Po) increases. To better understand how ATP regulates the channel, we studied excised inside-out membrane patches that contained single, phosphorylated CFTR Cl- channels and examined the kinetics of gating at different concentrations of ATP. As the ATP concentration increased from 0.1 to 3 mM the mean closed time decreased, but mean open time did not change. Analysis of the data using histograms of open- and closed-state durations, the maximum likelihood method, and the log-likelihood ratio test suggested that channel behavior could be described by a model containing one open and two closed states (C1<==>C2<==>O). ATP regulated phosphorylated channels at the transition between the closed states C1 and C2: as the concentration of ATP increased, the rate of transition from C1 to C2 (C1-->C2) increased. In contrast, transitions from C2 to C1 and between C2 and the open state (O) were not significantly altered by ATP. Addition of ADP in the presence of ATP decreased the transition rate from C1 to C2 without affecting other transition rates. These data suggest that ATP regulates CFTR Cl- channels through an interaction that increases the rate of transition from the closed state to a bursting state in which the channel flickers back and forth between an open and a closed state (C2). This transition may reflect ATP binding or perhaps a step subsequent to binding.",1
"Winter, M C, Sheppard, D N, Carson, M R, Welsh, M J",2
Permeability and electrical properties of planar lipid membranes from thylakoid lipids.,0
"Electrical measurements were carried out on planar lipid membranes from thylakoid lipids. The specific capacitance of membranes formed from decane-containing monogalactosyldiacylglycerol (MGDG), which accounts for 57% of the total lipid content of thylakoids, showed that it adopted a bilayer structure. Solvent-free bilayers of MGDG were not formed, with very rare exceptions, indicating that decane is required to stabilize the planar conformation. However, this cone-shaped lipid produces bilayer structures in combination with other cylindrical thylakoid lipids even in the absence of organic solvent. We compared the properties of solvent-free and decane-containing bilayers from MGDG, soybean lecithin, and the quaternary mixture of lipids similar to that found in vivo. The conductance of decane-MGDG was 26 times higher than that of decane-lecithin. The flux through the decane-lecithin bilayer was found to be slightly dependent on pH, whereas the decane-MGDG membrane was not. The specific conductance of bilayers formed from the quaternary mixture of lipids was 5 to 10 times larger than lecithin (with alkane or not). Further experiments with bilayers made in the presence of a KCl gradient showed that decane-MGDG, decane-MGDG/DGDG/SQDG/PG, and solvent-free MGDG/DGDG/SQDG/PG were cation-selective. The permeability coefficient for potassium ranged from 4.9 to 8.3 x 10(-11) cm s-1. The permeability coefficient for protons in galactolipids, however, was determined to be about six orders of magnitude higher than the value for potassium ions. The HCl permeation mechanism through the lipid membranes was determined from diffusion potentials measured in HCl gradients. Our results suggest that HCl was not transported as neutral molecules. The data is discussed with regard to the function of galactolipids in the ion transport through thylakoid membranes.",1
"Fuks, B, Homblé, F",2
The structure of an integral membrane peptide: a deuterium NMR study of gramicidin.,0
"Solid state deuterium NMR was employed on oriented multilamellar dispersions consisting of 1,2-dilauryl-sn-glycero-3-phosphatidylcholine and deuterium (2H) exchange-labeled gramicidin D, at a lipid to protein molar ratio (L/P) of 15:1, in order to study the dynamic structure of the channel conformation of gramicidin in a liquid crystalline phase. The corresponding spectra were used to discriminate between several structural models for the channel structure of gramicidin (based on the left- and right-handed beta 6.3 LD helix) and other models based on a structure obtained from high resolution NMR. The oriented spectrum is complicated by the fact that many of the doublets, corresponding to the 20 exchangeable sites, partially overlap. Furthermore, the asymmetry parameter, eta, of the electric field gradient tensor of the amide deuterons is large (approximately 0.2) and many of the amide groups are involved in hydrogen bonding, which is known to affect the quadrupole coupling constant. In order to account for these complications in simulating the spectra in the fast motional regime, an ab initio program called Gaussian 90 was employed, which permitted us to calculate, by quantum mechanical means, the complete electric field gradient tensor for each residue in gramicidin (using two structural models). Our results indicated that the left-handed helical models were inconsistent with our observed spectra, whereas a model based on the high-resolution structure derived by Arseniev and coworkers, but relaxed by a simple energy minimization procedure, was consistent with our observed spectra. The molecular order parameter was then estimated from the motional narrowing assuming the relaxed (right-handed) Arseniev structure. Our resultant order parameter of SZZ = 0.91 translates into an rms angle of 14 degrees, formed by the helix axis and the local bilayer normal. The strong resemblance between our spectra (and also those reported for gramicidin in 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) multilayers) and the spectra of the same peptide incorporated in a lyotropic nematic phase, suggests that the lyotropic nematic phase simulates the local environment of the lipid bilayer.",1
"Prosser, R S, Daleman, S I, Davis, J H",2
Dynamics of an integral membrane peptide: a deuterium NMR relaxation study of gramicidin.,0
"Solid state deuterium (2H) NMR inversion-recovery and Jeener-Broekaert relaxation experiments were performed on oriented multilamellar dispersions consisting of 1,2-dilauroyl-sn-glycero-3-phosphatidylcholine and 2H exchange-labeled gramicidin D, at a lipid to protein molar ratio (L/P) of 15:1, in order to study the dynamics of the channel conformation of the peptide in a liquid crystalline phase. Our dynamic model for the whole body motions of the peptide includes diffusion of the peptide around its helix axis and a wobbling diffusion around a second axis perpendicular to the local bilayer normal in a simple Maier-Saupe mean field potential. This anisotropic diffusion is characterized by the correlation times, tau R parallel and tau R perpendicular. Aligning the bilayer normal perpendicular to the magnetic field and graphing the relaxation rate, 1/T1Z, as a function of (1-S2N-2H), where S2N-2H represents the orientational order parameter, wer were able to estimate the correlation time, tau R parallel, for rotational diffusion. Although in the quadrupolar splitting, which varies as (3 cos2 theta D-1), has in general two possible solutions to theta D in the range 0 < or = theta D < or = 90 degrees, the 1/T1Z vs. (1-S2N-2H) curve can be used to determine a single value of theta D in this range. Thus, the 1/T1Z vs. (1-S2N-2H) profile can be used both to define the axial diffusion rate and to remove potential structural ambiguities in the splittings. The T1Z anisotropy permits us to solve for the two correlation times (tau R parallel = 6.8 x 10(-9) s and tau R perpendicular = 6 x 10(-6) s). The simulated parameters were corroborated by a Jeener-Broekaert experiment where the bilayer normal was parallel to the principal magnetic field. At this orientation the ratio, J2(2 omega 0)/J1(omega 0) was obtained in order to estimate the strength of the restoring potential in a model-independent fashion. This measurement yields the rms angle, <theta 2>1/2 (= 16 +/- 2 degrees at 34 degrees C), formed by the peptide helix axis and the average bilayer normal.",1
"Prosser, R S, Davis, J H",2
Studies on lipid membranes by two-dimensional Fourier transform ESR: Enhancement of resolution to ordering and dynamics.,0
"The first two-dimensional Fourier-transform electron spin resonance (2D-FT-ESR) studies of nitroxide-labeled lipids in membrane vesicles are reported. The considerable enhancement this experiment provides for extracting rotational and translational diffusion rates, as well as orientational ordering parameters by means of ESR spectroscopy, is demonstrated. The 2D spectral analysis is achieved using theoretical simulations that are fit to experiments by an efficient and automated nonlinear least squares approach. These methods are applied to dispersions of 1-palmitoyl-2oleoyl-sn-glycerophosphatidylcholine (POPC) model membranes utilizing spin labels 1-palmitoyl-2-(16-doxyl stearoyl) phosphatidylcholine and the 3-doxyl derivative of cholestan-3-one (CSL). Generally favorable agreement is obtained between the results obtained by 2D-FT-ESR on vesicles with the previous results on similar systems studied by continuous wave (cw) ESR on aligned samples. The precision in determining the dynamic and ordering parameters is significantly better for 2D-FT-ESR, even though the cw ESR spectra from membrane vesicles are resolved more poorly than those from well aligned samples. Some small differences in results by the two methods are discussed in terms of limitations of the methods and/or theoretical models, as well as possible differences between dynamic molecular structure in vesicles versus aligned membranes. An interesting observation with CSL/POPC, that the apparent homogeneous linewidths seem to increase in ""real time,"" is tentatively attributed to the effects of slow director fluctuations in the membrane vesicles.",1
"Crepeau, R H, Saxena, S, Lee, S, Patyal, B, Freed, J H",2
Pressure-induced correlation field splitting of vibrational modes: structural and dynamic properties in lipid bilayers and biomembranes.,0
"Correlation field splittings of the vibrational modes of methylene chains in lipid bilayers, isolated lipid molecules in perdeuterated lipid bilayers, crystalline lipid, and interdigitated lipid bilayers have been investigated by pressure-tuning Fourier-transform infrared spectroscopy. The correlation field splittings of these modes are originating from the vibrational coupling interactions between the fully extended methylene chains with different site symmetry along each bilayer leaflet. The interchain-interactions of the methylene chains with the same site symmetry only contribute to frequency shift of the vibrational modes. The magnitude of the correlation field splitting is a measure of the strength of the interchain-interactions, and the relative intensities of the correlation field component bands provide information concerning the relative orientation of the zig-zag planes of the interacting methylene chains. It has been demonstrated in the present work that the correlation field splitting of the CH2 bending and rocking modes commonly observed in the vibrational spectra of lipid bilayers is the result of the intermolecular interchain-interactions among the methylene chains of the neighboring molecules. The intramolecular interchain-interactions between the sn-1 and sn-2 methylene chains within each molecule are weak. The correlation field splitting resulting from the intramolecular interchain-interactions exhibits a much smaller magnitude than that from the intermolecular interchain-interactions and is observed only at very high pressure. Interdigitation of the opposing bilayer leaflets disturbs significantly the intermolecular interchain-interactions and results in dramatic changes in the pressure profiles of the correlation field component bands of both the CH2 bending and rocking modes. The relative intensities of the correlation field component bands of these modes and the magnitude of the splitting are also altered significantly. These results provide further evidence that the correlation field splitting of the CH2 bending and rocking modes in the vibrational spectra of lipid bilayers is due to the intermolecular interchain-interactions. The present work has also demonstrated that the correlation field splitting of the vibrational modes in lipid bilayers is mainly contributed by the intermolecular interchain-interactions among the nearest neighboring molecules and that the long-range correlation interactions beyond the second neighboring molecules are insignificant.",1
"Wong, P T",2
An electron spin resonance study of interactions between phosphatidylcholine and phosphatidylserine in oriented membranes.,0
"A detailed electron spin resonance (ESR) study of mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and phosphatidylserine (POPS) in oriented multilayers in the liquid crystalline phase is reported with the purpose of characterizing the effects of headgroup mixing on the structural and dynamical properties of the acyl chains. These studies were performed over a range of blends of POPC and POPS and temperatures, utilizing the spin-labeled lipids 16-phosphatidylcholine and 5-phosphatidylcholine as well as cholestane (CSL). The ESR spectra were analyzed by nonlinear least-squares fitting using detailed spectral simulations. Whereas CSL shows almost no variation in ordering and rotational dynamics versus mole fraction POPS, (i.e. XPS), and 5-PC shows small effects, the weakly ordered end-chain labeled 16-PC shows large relative effects, such that the orientational order parameter, S is at a minimum for XPS = 0.5 where it is about one-third the value observed for XPS = 0 and 1. This is directly reflected in the ESR spectrum as a substantial variation in the hyperfine splitting with XPS. The least-squares analysis also shows a reduction in rotational diffusion coefficient, R perpendicular by a fractor of 2 for XPS = 0.5 and permits the estimation of S2, the ordering parameter representing deviations from cylindrically symmetric alignment. These results are contrasted with 2H NMR studies which were insensitive to effects of mixing headgroups on the acyl chains. The ESR results are consistent with a somewhat increased disorder in the end-chain region as well as a small amount of chain tilting upon mixing POPC and POPS. They demonstrate the high sensitivity of ESR to subtle effects in chain ordering and dynamics.",1
"Ge, M, Budil, D E, Freed, J H",2
Low-temperature energy transfer in LHC-II trimers from the Chl a/b light-harvesting antenna of photosystem II.,0
"Temperature dependence in electronic energy transfer steps within light-harvesting antenna trimers from photosystem II was investigated by studying Chl a pump-probe anisotropy decays at several wavelengths from 675 to 682 nm. The anisotropy lifetime is markedly sensitive to temperature at the longest wavelengths (680-682 nm), increasing by factors of 5 to 6 as the trimers are cooled from room temperature to 13 K. The temperature dependence is muted at 677 and 675 nm. This behavior is modeled using simulations of temperature-broadened Chl a absorption and fluorescence spectra in spectral overlap calculations of Förster energy transfer rates. In this model, the 680 nm anisotropy decays are dominated by uphill energy transfers from 680 nm Chl a pigments at the red edge of the LHC-II spectrum; the 675 nm anisotropy decays reflect a statistical average of uphill and downhill energy transfers from 676-nm pigments. The measured temperature dependence is consistent with essentially uncorrelated inhomogeneous broadening of donor and acceptor Chl a pigments.",1
"Savikhin, S, van Amerongen, H, Kwa, S L, van Grondelle, R, Struve, W S",2
Structures of wild-type and mutant signal sequences of Escherichia coli ribose binding protein.,0
"The structure of a chemically synthesized 25-residue-long functional signal peptide of Escherichia coli ribose binding protein was compared with that of a nonfunctional mutant-signal peptide using circular dichroism and two-dimensional 1H NMR in solvents mimicking the amphiphilic environments. The functional peptide forms an 18-residue-long alpha-helix starting from the NH2-terminal region and reaching to the hydrophobic stretch in a solvent consisting of 10% dimethylsulfoxide, 40% water, and 50% trifluoroethanol (v/v). The nonfunctional mutant peptide, which contains a Pro at position 9 instead of a Leu in the wild-type peptide, does not have any secondary structure in that solvent but forms a 12-residue-long alpha-helix within the hydrophobic stretch in water/trifluoroethanol (50:50, v/v) solvent. It seems that the Pro-9 residue in the nonfunctional peptide disturbs the helix propagation from the hydrophobic stretch to the NH2-terminal region. Because both of these peptides have stable helices within the hydrophobic stretch, it may be concluded that the additional 2 turns of the alpha-helix in the NH2-terminal region of the wild-type signal peptide is important for its function.",1
"Yi, G S, Choi, B S, Kim, H",2
Structure and activation dynamics of RBL-2H3 cells observed with scanning force microscopy.,0
"Surface and subsurface dynamics of Rat Basophilic Leukemia cells, a model system of stimulated secretion, were imaged using Scanning Force Microscopy (SFM) at a rate of 50-60 s/image. Cytoskeletal elements and organelles were tracked within quiescent cells and those activated after IgE receptor crosslinking. In addition, surface waves were observed moving within the plasma membrane. The structures seen in quiescent and activated cells can be correlated with those seen in electron micrographs and topographic SFM images of fixed detergent-extracted cells. Furthermore, images of the detergent-extracted nuclei reveal the presence of numerous nuclear pore complexes. High-magnification images of the nuclear pore complexes show evidence of subunit structure and exhibit dimensions consistent with those reported previously using electron microscopy. The behavior and overall change in morphology of cells observed during activation was consistent with that observed under similar conditions with Differential Interference Contrast microscopy. This study demonstrates that SFM, unlike other techniques, can be used to provide high-resolution information in both fixed and living cells.",1
"Braunstein, D, Spudich, A",2
Cooperative action between band 3 and glycophorin A in human erythrocytes: immobilization of band 3 induced by antibodies to glycophorin A.,0
"The ability of transmembrane receptor proteins to change their association with the cytoskeleton in response to ligand binding seems to be a key mechanism of signal transduction across membranes. To investigate the molecular features of this mechanism we have used the red cell membrane as a model system to study signal transduction through the integral protein, glycophorin A. In these studies the lateral mobility of integral proteins was measured in situ by fluorescence recovery after photobleaching, and membrane rigidity was characterized by micropipette aspiration technique. We found that binding either a monoclonal antibody or its monovalent Fab to the exoplasmic domain of glycophorin A in normal red cells immobilized the receptor and rigidified the membrane. Further, immobilization and rigidification did not occur when antibodies were bound to Miltenberger V cells containing a mutant form of glycophorin A lacking the cytoplasmic domain. These results imply that the site of the immobilization/rigidification lies within the membrane skeletal structure, not in exofacial receptor crosslinking, and requires the extended cytoplasmic domain of normal glycophorin A. In addition, we found that glycophorin A immobilization and membrane skeletal rigidification were accompanied by immobilization of band 3 receptors. This unexpected result indicates a cooperative coupling between liganded glycophorin A, band 3, and the membrane skeleton. We speculate that cooperation of this type may represent a general mechanism for cytoskeletal linkage and transformation initiated by receptors with short cytoplasmic sequences, such as integrins.",1
"Knowles, D W, Chasis, J A, Evans, E A, Mohandas, N",2
Anisotropic propagation of Ca2+ waves in isolated cardiomyocytes.,0
"Digital imaging microscopy of fluor-3 fluorescence was used to study the propagation of intracellular Ca2+ waves in isolated adult rat cardiomyocytes from 17 to 37 degrees C. Ca2+ waves spread in both transverse and longitudinal direction of a myocyte. Transverse propagation was pronounced in waves starting from a focus at the edge of a myocyte and in waves following an irregular, curved path (spiral waves). For the former type of waves, propagation velocities were determined. Both transverse and longitudinal wave components propagated at constant velocity ranging from 30 to 125 micron/s. Myocytes were anisotropic with respect to wave propagation: waves propagated faster in the longitudinal than in the transverse direction. The ratio between longitudinal and transverse velocity increased from 1.30 at 17 degrees C to 1.55 at 37 degrees C. Apparent activation energies for transverse and longitudinal wave propagation were estimated to be -20 kJ/mol, suggesting that these processes are limited by diffusion of Ca2+. Direction-dependent propagation velocities are interpreted to result from the highly ordered structure of the myocytes, especially from the anisotropic arrangement of diffusion obstacles such as myofilaments and mitochondria.",1
"Engel, J, Fechner, M, Sowerby, A J, Finch, S A, Stier, A",2
Pattern recognition and classification of images of biological macromolecules using artificial neural networks.,0
"The goal of this work was to analyze an image data set and to detect the structural variability within this set. Two algorithms for pattern recognition based on neural networks are presented, one that performs an unsupervised classification (the self-organizing map) and the other a supervised classification (the learning vector quantization). The approach has a direct impact in current strategies for structural determination from electron microscopic images of biological macromolecules. In this work we performed a classification of both aligned but heterogeneous image data sets as well as basically homogeneous but otherwise rotationally misaligned image populations, in the latter case completely avoiding the typical reference dependency of correlation-based alignment methods. A number of examples on chaperonins are presented. The approach is computationally fast and robust with respect to noise. Programs are available through ftp.",1
"Marabini, R, Carazo, J M",2
Gating of the squid sodium channel at positive potentials. I. Macroscopic ionic and gating currents.,0
"Macroscopic ionic sodium currents and gating currents were studied in voltage-clamped, dialyzed giant axons of the squid Loligo pealei under conditions of regular and inverse sodium gradients. Sodium currents showed regular kinetics but inactivation was incomplete, showing a maintained current for depolarizations lasting 18 ms. The ratio of the maintained current to the peak current increased with depolarization and it did not depend on the direction of the current flow or the sodium gradient. The time constant of inactivation was not affected by the sodium gradient. Double-pulse experiments allowed the separation of a normal inactivating component and a noninactivating component of the sodium currents. In gating current experiments, the results from double-pulse protocols showed that the charge was decreased by the prepulse and that the slow component of the 'on' gating current was preferentially depressed. As expected, charge immobilization was established faster at higher depolarizations than at low depolarizations, however, the amount of immobilized charge was unaffected by the pulse amplitude. This indicates that the incomplete sodium inactivation observed at high depolarizations is not the result of decreased charge immobilization; the maintained current must be due to a conductance that appears after normal charge immobilization and fast inactivation.",1
"Correa, A M, Bezanilla, F",2
Ca(2+)-dependent inactivation of a cloned cardiac Ca2+ channel alpha 1 subunit (alpha 1C) expressed in Xenopus oocytes.,0
"The alpha 1 subunit of cardiac Ca2+ channel, expressed alone or coexpressed with the corresponding beta subunit in Xenopus laevis oocytes, elicits rapidly inactivating Ca2+ currents. The inactivation has the following properties: 1) It is practically absent in external Ba2+; 2) it increases with Ca2+ current amplitudes; 3) it is faster at more negative potentials for comparable Ca2+ current amplitudes; 4) it is independent of channel density; and 5) it does not require the beta subunit. These findings indicate that the Ca2+ binding site responsible for inactivation is encoded in the alpha 1 subunit and suggest that it is located near the inner channel mouth but outside the membrane electric field.",1
"Neely, A, Olcese, R, Wei, X, Birnbaumer, L, Stefani, E",2
Potassium secretion by vestibular dark cell epithelium demonstrated by vibrating probe.,0
"Detection of motion and position by the vestibular labyrinth depends on the accumulation of potassium within a central compartment of the inner ear as a source of energy to drive the transduction process. Much circumstantial evidence points to the vestibular dark cell (VDC) epithelium as being responsible for concentrating K+ within the lumen. We have used the vibrating probe technique to directly observe voltage and ion gradients produced by this tissue to put this assumption on a solid experimental footing. Relative current density (Isc,probe) over the apical membrane of VDC epithelium was measured with the vibrating voltage-sensitive probe, and this technique was validated by performing maneuvers known to either stimulate or inhibit the transepithelial equivalent short circuit current. Basolateral bumetanide (5 x 10(-5) M) and ouabain (1 x 10(-3) M) caused a decrease in Isc,probe by 55 +/- 6% and 39 +/- 3%, respectively while raising the basolateral K+ concentration from 4 to 25 mM caused an increase by 35 +/- 8%. A K+ gradient directed toward the apical membrane was detected with the vibrating K(+)-selective electrode, demonstrating that, indeed, the VDC epithelium secretes K+ under control conditions. This secretion was inhibited by bumetanide (by 94 +/- 7%) and ouabain (by 52 +/- 8%). The results substantiate the supposition that dark cells produce a K+ flux and qualitatively support the correlation between this flux and the transepithelial current.",1
"Marcus, D C, Shipley, A M",2
Increased adhesion between neutral lipid bilayers: interbilayer bridges formed by tannic acid.,0
"Tannic acid (TA) is a naturally occurring polyphenolic compound that aggregates membranes and neutral phosolipid vesicles and precipitates many proteins. This study analyzes TA binding to lipid membranes and the ensuing aggregation. The optical density of dispersions of phosphatidylcholine (PC) vesicles increased upon the addition of TA and electron micrographs showed that TA caused the vesicles to aggregate and form stacks of tightly packed disks. Solution calorimetry showed that TA bound to PC bilayers with a molar binding enthalpy of -8.3 kcal/mol and zeta potential measurements revealed that TA imparted a small negative charge to PC vesicles. Monolayer studies showed that TA bound to PC with a dissociation constant of 1.5 microM and reduced the dipole potential by up to 250 mV. Both the increase in optical density and decrease in dipole potential produced by TA could be reversed by the addition of polyvinylpyrrolidone, a compound that chelates TA by providing H-bond acceptor groups. NMR, micropipette aspiration, and x-ray diffraction experiments showed that TA incorporated into liquid crystalline PC membranes, increasing the area per lipid molecule and decreasing the bilayer thickness by 2 to 4%. 2H-NMR quadrupole splitting measurements also showed that TA associated with a PC molecule for times much less than 10(-4) s. In gel phase bilayers, TA caused the hydrocarbon chains from apposing monolayers to fully interdigitate. X-ray diffraction measurements of both gel and liquid crystalline dispersions showed that TA, at a critical concentration of about 1 mM, reduced the fluid spacing between adjacent bilayers by 8-10 A. These data place severe constraints on how TA can pack between adjacent bilayers and cause vesicles to adhere. We conclude that TA promotes vesicle aggregation by reducing the fluid spacing between bilayers by the formation of transient interbilayer bridges by inserting its digallic acid residues into the interfacial regions of adjacent bilayers and spanning the interbilayer space.",1
"Simon, S A, Disalvo, E A, Gawrisch, K, Borovyagin, V, Toone, E, Schiffman, S S, Needham, D, McIntosh, T J",2
Changes in the lipid dynamics of liposomal membranes induced by poly(ethylene glycol): free volume alterations revealed by inter- and intramolecular excimer-forming phospholipid analogs.,0
"Influence of osmotic shrinkage, swelling, and dehydration on large unilamellar liposomes (LUVs) of 1,2-dioleoylsn-glycero-3-phosphocholine (DOPC) was investigated using the fluorescent lipid probes 1-palmitoyl-2-[10-(pyren-1-yl)]-decanoyl-sn-glycero-3-phosphocholi ne (PPDPC) and 1,2-bis[10-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine (bisPDPC). Increasing concentrations of poly(ethylene glycol) (PEG, average molecular weight of 6000) producing osmotic gradients delta omega up to 250 mOsm/kg were first added to the outside of LUV labeled with 0.1 mol% of either of the above fluorescent phospholipids. The resulting osmotic shrinkage was accompanied by a progressive reduction in the lateral diffusion of the membrane-incorporated PPDPC, evident as a decrease in the rate of its intermolecular excimer formation. In contrast, under the same conditions the rate of intramolecular excimer formation by bisPDPC increased. Notably, signals opposite to those described above were observed for both of the fluorescent probes upon osmotic swelling of DOPC liposomes with encapsulated PEG. The lateral diffusion of PPDPC became progressively reduced upon membrane dehydration due to increasing concentrations of symmetrically distributed PEG (with equal polymer concentrations inside and outside of the liposomes) when neither shrinkage nor swelling occurs while enhanced excimer formation by bisPDPC was evident. The later results were interpreted in terms of osmotically induced changes in the hydration of lipids. In brief, the removal of water from the phospholipid hydration shell diminishes the effective size of the polar headgroup, which subsequently allows for an enhanced lateral packing of the phospholipid acyl chains. Our findings are readily compatible with membrane free volume Vf changes due to osmotic forces under three different kinds of stress (shrinkage, swelling, and dehydration) applied on the lipid bilayers.",1
"Lehtonen, J Y, Kinnunen, P K",2
"Exploration of physical principles underlying lipid regular distribution: effects of pressure, temperature, and radius of curvature on E/M dips in pyrene-labeled PC/DMPC binary mixtures.",0
"In a previous study, we observed a series of dips in the plot of E/M (the ratio of excimer to monomer fluorescence intensity) versus the mole fraction of 1-palmitoyl-2-(10-pyrenyl)decanoyl-sn-glycerol-3-phosphatidylcholine (Pyr-PC) in Pyr-PC/DMPC binary mixtures at 30 degrees C. In the present study, we have characterized the physical nature of E/M dips in Pyr-PC/DMPC binary mixtures by varying pressure, temperature, and vesicle diameter. The E/M dips at 66.7 and at 71.4 mol% PyrPC in DMPC multilamellar vesicles remain discernible at 30-43 degrees C. At higher temperatures (e.g., 53 degrees C), the depth of the dip abruptly becomes smaller. This result agrees with the idea that E/M dips appear as a result of regular distribution of pyrene-labeled acyl chains into hexagonal super-lattices at critical mole fractions. Regular distribution is a self-ordering phenomenon. Usually, in self-ordered systems, the number of structural defects increases with increasing temperature, and thermal fluctuations eventually result in an order-to-disorder transition. The effect of vesicle diameter on the E/M dip at 66.7 mol% Pyr-PC in DMPC has been studied at 37.5 degrees C by using unilamellar vesicles of varying sizes. The E/M dip is observable in large unilamellar vesicles; however, the depth of the E/M dip decreases when the vesicle diameter is reduced. When the vesicle diameter is reduced to about 64 nm, the dip becomes shallow and split. This result suggests that the curvature-induced increase in the separation of lipids in the outer monolayer decreases the tendency of regular distribution for pyrene-labeled acyl chains. Regular distribution is believed to arise from the long-range repulsive interaction between Pyr-PC molecules due to the elastic deformation of the lipid matrix around the bulky pyrene moiety. When the radius of curvature becomes small, outer monolayer lipids are more separated. Therefore, pyrene-containing acyl chains fit better into the membrane matrix, which alleviates the deformation of the lattice and diminishes the long-range repulsive interactions between pyrene-containing acyl chains. Furthermore, we have shown a striking difference in the pressure dependence of E/M at critical Pyr-PC mole fractions and at noncritical mole fractions. In the pressure range between 0.001 and 0.7 kbar at 30 degrees C, E/M decreases steadily with increasing pressure at noncritical mole fractions; in contrast, E/M changes little with pressure at critical mole fractions (e.g., 33.3 and 50.0 mol% Pyr-PC). The pressure data suggest that membrane free volume in the liquid crystalline state of the bilayer is less abundant at critical Pyr-PC mole fractions than at noncritical mole fractions.",1
"Chong, P L, Tang, D, Sugar, I P",2
A disulfide crosslink between Cys98 of troponin-C and Cys133 of troponin-I abolishes the activity of rabbit skeletal troponin.,0
"Various thio-reactive bifunctional crosslinkers as well as 5,5'-dithiobis(2-nitrobenzoate)-mediated disulfide bond formation were used to crosslink troponin-C and troponin-I, the Ca(2+)-binding and inhibitory subunits of troponin, respectively. In all cases, substantial crosslinking was obtained when the reactions were carried out in the absence of Ca2+. No disulfide crosslinking occurred if either Cys98 of TnC, or Cys133 of TnI were blocked, indicating that these thiols are involved in the crosslinking. Troponin containing the disulfide crosslink is no longer capable of regulating actomyosin ATPase activity in a Ca(2+)-dependent manner. Our results suggest that the relative movement between the Cys98 region of TnC and the Cys133 region of TnI is required for the Ca(2+)-regulatory process in skeletal muscle.",1
"Park, H S, Gong, B J, Tao, T",2
Light-induced voltage changes associated with electron and proton transfer in photosystem II core complexes reconstituted in phospholipid monolayers.,0
"We have measured light-induced voltage changes (electrogenic events) in photosystem II (PSII) core complexes oriented in phospholipid monolayers. These events are compared to those measured in the functionally and structurally closely related reaction centers from the photosynthetic bacterium Rhodobacter sphaeroides. In both systems we observed a rapid (< 100 ns) light-induced increase in voltage associated with charge separation. In PSII reaction centers it was followed by a decrease (decay) of approximately 14% of the charge-separation voltage and a time constant of approximately 500 microseconds. In bacterial reaction centers this decay was approximately 9% of the charge-separation voltage, and the time constant was approximately 200 microseconds. The decay was presumably associated with a structural change. In bacterial reaction centers, in the presence of excess water-soluble cytochrome c2+, it was followed by a slower increase of approximately 30% of the charge-separation voltage, associated with electron transfer from the cytochrome to the oxidized donor, P+. In PSII reaction centers, after the decay the voltage remained on the same level for > or = 0.5 s. In PSII reaction centers the electron transfer Q-AQB-->QA Q-B contributed with an electrogenicity of < or = 5% of that of the charge separation. In bacterial reaction centers this electrogenicity was < or = 2% of the charge-separation electrogenicity. Proton transfer to Q2-B in PSII reaction centers contributed with approximately 5% of the charge-separation voltage, which is approximately a factor of three smaller than that observed in bacterial reaction centers.",1
"Höök, F, Brzezinski, P",2
Photoinduced electric currents in carotenoid-deficient Chlamydomonas mutants reconstituted with retinal and its analogs.,0
"Reconstitution of the photoelectric responses involved in photosensory transduction in ""blind"" cells of Chlamydomonas reinhardtii carotenoid-deficient mutants was studied by means of a recently developed population method. Both the photoreceptor current and the regenerative response can be restored by addition of all-trans-retinal, 9-demethyl-retinal, or dimethyl-octatrienal, while the retinal analogs prevented from 13-cis/trans isomerization, 13-demethyl-retinal and citral, are not effective. Fluence dependence, spectral sensitivity, and effect of hydroxylamine treatment on retinal-induced photoelectric responses are similar to those found earlier in green strains of Chlamydomonas, although an alternative mechanism of antenna directivity in white cells of reconstituted ""blind"" mutants (likely based on the focusing effect of the transparent cell bodies) leads to the reversed sign of phototaxis in mutant cells under the same conditions. The results obtained indicate that both photoreceptor current and regenerative response are initiated by the same or similar rhodopsins with arhaebacterial-like chromophore(s) and prove directly the earlier suggested identity of the photoreceptor pigment(s) involved in photomotile and photoelectric responses in flagellated algae.",1
"Sineshchekov, O A, Govorunova, E G, Dér, A, Keszthelyi, L, Nultsch, W",2
Photoactivation of rhodopsin involves alterations in cysteine side chains: detection of an S-H band in the Meta I-->Meta II FTIR difference spectrum.,0
"FTIR difference spectroscopy has been used to study the role of cysteine residues in the photoactivation of rhodopsin. A positive band near 2550 cm-1 with a low frequency shoulder is detected during rhodopsin photobleaching, which is assigned on the basis of its frequency and isotope shift to the S-H stretching mode of one or more cysteine residues. Time-resolved studies at low temperature show that the intensity of this band correlates with the formation and decay kinetics of the Meta II intermediate. Modification of rhodopsin with the reagent NEM, which selectively reacts with the SH groups of Cys-140 and Cys-316 on the cytoplasmic surface of rhodopsin, has no effect on the appearance of this band. Four other cysteine residues are also unlikely to contribute to this band because they are either thio-palmitylated (Cys-322 and Cys-323) or form a disulfide bond (Cys-110 and Cys-187). On this basis, it is likely that at least one of the four remaining cysteine residues in rhodopsin is structurally active during rhodopsin photoactivation. The possibility is also considered that this band arises from a transient cleavage of the disulfide bond between cysteine residues 110 and 187.",1
"Rath, P, Bovee-Geurts, P H, DeGrip, W J, Rothschild, K J",2
On the efficiency and reversibility of active ligand transport induced by alternating rectangular electric pulses.,0
"The stationary-state kinetic properties of a simplified two-state electro-conformational coupling model (ECC) in the presence of alternating rectangular electric potential pulses are derived analytically. Analytic expressions for the transport flux, the rate of electric energy dissipation, and the efficiency of the transducing system are obtained as a function of the amplitude and frequency of the oscillation. These formulas clarify some fundamental concept of the ECC model and are directly applicable to the interpretation and design of experiments. Based on these formulas, the reversibility and the degree of coupling of the system can be studied quantitatively. It is found that the oscillation-induced free energy transduction is reversible and tight-coupled only when the amplitude of the oscillating electric field is infinitely large. In general, the coupling is not tight when the amplitude of the electric field is finite. Furthermore, depending on the kinetic parameters of the model, there may exist a ""critical"" electric field amplitude, below which free energy transduction is not reversible. That is, energy may be transduced from the electric to the chemical, but not from the chemical to the electric.",1
"Chen, Y, Tsong, T Y",2
Mapping interaction forces with the atomic force microscope.,0
"Force curves were recorded as the sample was raster-scanned under the tip. This opens new opportunities for imaging with the atomic force microscope: several characteristics of the samples can be measured simultaneously, for example, topography, adhesion forces, elasticity, van der Waals, and electrostatic interactions. The new opportunities are illustrated by images of several characteristics of thin metal films, aggregates of lysozyme, and single molecules of DNA.",1
"Radmacher, M, Cleveland, J P, Fritz, M, Hansma, H G, Hansma, P K",2
Passive mechanical behavior of human neutrophils: effect of cytochalasin B.,0
"Actin is a ubiquitous protein in eukaryotic cells. It plays a major role in cell motility and in the maintenance and control of cell shape. In this article, we intend to address the contribution of actin to the passive mechanical properties of human neutrophils. As a framework for assessing this contribution, the neutrophil is modeled as a simple viscous fluid drop with a constant cortical (""surface"") tension. The reagent cytochalasin B (CTB) was used to disrupt the F-actin structure, and the neutrophil cortical tension and cytoplasmic viscosity were evaluated by single-cell micropipette aspiration. The cortical tension was calculated by simple force balance, and the viscosity was calculated according to a numerical analysis of the cell entry into the micropipette. CTB reduced the cell cortical tension in a dose-dependent fashion: by 19% at a concentration of 3 microM and by 49% at 30 microM. CTB also reduced the cytoplasmic viscosity by approximately -25% at a concentration of 3 microM and by approximately 65% at a concentration of 30 microM when compared at the same aspiration pressures. All three groups of neutrophils, normal cells, and cells treated with either 3 or 30 microM CTB, exhibited non-Newtonian behavior, in that the apparent viscosity decreased with increasing shear rate. The dependence of the cytoplasmic viscosity on deformation rate can be described empirically by mu = mu c(gamma m/gamma c)-b, where mu is cytoplasmic viscosity, gamma m is mean shear rate, mu c is the characteristic viscosity at the characteristic shear rate gamma c, and b is a material coefficient. The shear rate dependence of the cytoplasmic viscosity was reduced by CTB treatment. This is reflected by the changes in the material coefficients. When gamma c was set to 1 s-1, pc = 130 +/- 23 Pa.s and b = 0.52 +/- 0.09 for normal neutrophils and pc = 54 +/- 15 Pa.S and b = 0.26 +/- 0.05 for cells treated with 30 micro M CTB. These results provide the first quantitative assessment of the role that Pa-s-actin structure plays in the passive mechanical properties of human neutrophils.",1
"Tsai, M A, Frank, R S, Waugh, R E",2
Aggregation efficiency of activated normal or fixed platelets in a simple shear field: effect of shear and fibrinogen occupancy.,0
"Shear rate can affect protein adsorption and platelet aggregation by regulating both the collision frequency and the capture efficiency (alpha). These effects were evaluated in well defined shear field in a micro-couette for shear rate G = 10 - 1000 s-1. The rate of protein binding was independent of G, shown for adsorption of albumin to latex beads and PAC1 to activated platelets. The initial aggregation rate for ADP-activated platelets in citrated platelet-rich plasma followed second order kinetics at the initial platelet concentrations between 20,000 and 60,000/microliters. alpha values, which dropped nearly fivefold for a 10-fold increase in G, were approximately proportional to G-1, contrary to a minor drop predicted by the theory that includes protein cross-bridging. Varying ADP concentration did not change alpha of maximally activated platelet subpopulations, suggesting that aggregation between unactivated and activated platelets is negligible. Directly blocking the unoccupied but activated GPIIb-IIIa receptors without affecting pre-bound Fg on ""RGD""-activated, fixed platelets (AFP) by GRGDSP or Ro 43-5054 eliminated aggregation, suggesting that cross-bridging of GPIIb-IIIa on adjacent platelets by fibrinogen mediates aggregation. Alpha for AFP remained maximal (approximately 0.24) over 25-75% Fg occupancy, otherwise decreasing rapidly, with a half-maximum occurring at around 2% occupancy, suggesting that very few bound Fg were required to cause significant aggregation.",1
"Xia, Z, Frojmovic, M M",2
Local television news coverage of traumatic deaths and injuries.,0
To assess how local television news programs' reporting of injuries and deaths from traumatic causes compares with coroners' records of deaths and the estimated incidence of injuries in the same geographic area during the same time.,1
"McArthur, D L, Magaña, D, Peek-Asa, C, Kraus, J F",2
Information superhighway or billboards by the roadside? An analysis of hospital web sites.,0
"To determine the prevalence of hospital web sites, the types of information provided within these sites, and the relationship of information to institutional characteristics.",1
"Zingmond, D S, Lim, Y W, Ettner, S L, Carlisle, D M",2
Brain drain from developing countries: how can brain drain be converted into wisdom gain?,0
"Brain drain is defined as the migration of health personnel in search of the better standard of living and quality of life, higher salaries, access to advanced technology and more stable political conditions in different places worldwide. This migration of health professionals for better opportunities, both within countries and across international borders, is of growing concern worldwide because of its impact on health systems in developing countries. Why do talented people leave their countries and go abroad? What are the consequences of such migrations especially on the educational sector? What policies can be adopted to stem such movements from developing countries to developed countries? This article seeks to raise questions, identify key issues and provide solutions which would enable immigrant health professionals to share their knowledge, skills and innovative capacities and thereby enhancing the economic development of their countries.",1
"Dodani, Sunita, LaPorte, Ronald E",2
"Research governance: where did it come from, what does it mean?",0
"For a variety of historical and social reasons, research has become increasingly formalized and regulated. This change has potential benefits (reduction in fraud and misconduct, protection of vulnerable groups, financial probity) but also disadvantages (increased paperwork, time delays, constraints on research freedom). The terms 'research' and 'governance' mean different things in different contexts. Even with explicit guidance, ambiguities must be resolved by human judgement. Variation in the nature and outcome of approval decisions is therefore a fact of life. The type of approval needed for a research study depends on the official remit of the approval body, the question to be addressed; the methods to be used; the context in which the work will take place; the level of analysis and interpretation; and the plans for how the findings will be presented and used.",1
"Shaw, Sara, Boynton, Petra M, Greenhalgh, Trisha",2
Venous thromboprophylaxis in UK medical inpatients.,0
"We prospectively assessed the implementation of venous thromboembolism (VTE) prophylaxis guidelines and the impact of grand round presentation of the data in changing clinical practice. Two NHS teaching hospitals were studied for 24 months from January 2003. Patients were risk stratified according to the THRIFT (thromboembolic risk factor) consensus group guidelines and compared with the recommendations of the THRIFT and ACCP (American College of Chest Physicians) consensus groups. Six months following presentation of the initial results, a further analysis was made to assess changes in clinical practice. 1128 patients were assessed of whom 1062 satisfied the inclusion criteria for thromboprophylaxis. 89% of all patients were stratified as having high or moderate risk of developing VTE. Of these only 28% were prescribed some form of thromboprophylaxis-4% received the THRIFT-recommended and 22% received the ACCP-recommended thromboprophylaxis. The vast majority (72%) received no thromboprophylaxis at all. Reassessment, following data presentation at grand rounds, showed a significant increase to 31% inpatients receiving THRIFT (P<0.0001) and ACCP (P=0.002) recommended thromboprophylaxis. However,the proportion of patients receiving no form of prophylaxis barely changed (72% to 69%: P=0.59). We found a gross underutilization of thromboprophylaxis in hospitalized medical patients. A simple grand-round presentation of the data and recommended guidelines to clinicians significantly increased the proportion of patients receiving recommended thromboprophylaxis but did not increase the overall proportion of patients receiving it. We therefore conclude that a single presentation of guidelines is not enough to achieve the desired levels. Such presentations may only serve to make DVT (deep venous thromboembolism) aware clinicians prescribe prophylaxis more accurately.",1
"Rashid, S T, Thursz, M R, Razvi, N A, Voller, R, Orchard, T, Rashid, S T, Shlebak, A A",2
SPdb--a signal peptide database.,0
"The signal peptide plays an important role in protein targeting and protein translocation in both prokaryotic and eukaryotic cells. This transient, short peptide sequence functions like a postal address on an envelope by targeting proteins for secretion or for transfer to specific organelles for further processing. Understanding how signal peptides function is crucial in predicting where proteins are translocated. To support this understanding, we present SPdb signal peptide database http://proline.bic.nus.edu.sg/spdb, a repository of experimentally determined and computationally predicted signal peptides.",1
"Choo, Khar Heng, Tan, Tin Wee, Ranganathan, Shoba",2
Inhibition of colony-stimulating-factor-1 signaling in vivo with the orally bioavailable cFMS kinase inhibitor GW2580.,0
"Colony-stimulating-factor-1 (CSF-1) signaling through cFMS receptor kinase is increased in several diseases. To help investigate the role of cFMS kinase in disease, we identified GW2580, an orally bioavailable inhibitor of cFMS kinase. GW2580 completely inhibited human cFMS kinase in vitro at 0.06 microM and was inactive against 26 other kinases. GW2580 at 1 microM completely inhibited CSF-1-induced growth of mouse M-NFS-60 myeloid cells and human monocytes and completely inhibited bone degradation in cultures of human osteoclasts, rat calvaria, and rat fetal long bone. In contrast, GW2580 did not affect the growth of mouse NS0 lymphoblastoid cells, human endothelial cells, human fibroblasts, or five human tumor cell lines. GW2580 also did not affect lipopolysaccharide (LPS)-induced TNF, IL-6, and prostaglandin E2 production in freshly isolated human monocytes and mouse macrophages. After oral administration, GW2580 blocked the ability of exogenous CSF-1 to increase LPS-induced IL-6 production in mice, inhibited the growth of CSF-1-dependent M-NFS-60 tumor cells in the peritoneal cavity, and diminished the accumulation of macrophages in the peritoneal cavity after thioglycolate injection. Unexpectedly, GW2580 inhibited LPS-induced TNF production in mice, in contrast to effects on monocytes and macrophages in vitro. In conclusion, GW2580's selective inhibition of monocyte growth and bone degradation is consistent with cFMS kinase inhibition. The ability of GW2580 to chronically inhibit CSF-1 signaling through cFMS kinase in normal and tumor cells in vivo makes GW2580 a useful tool in assessing the role of cFMS kinase in normal and disease processes.",1
"Conway, James G, McDonald, Brad, Parham, Janet, Keith, Barry, Rusnak, David W, Shaw, Eva, Jansen, Marilyn, Lin, Peiyuan, Payne, Alan, Crosby, Renae M, Johnson, Jennifer H, Frick, Lloyd, Lin, Min-Hwa Jasmine, Depee, Scott, Tadepalli, Sarva, Votta, Bart, James, Ian, Fuller, Karen, Chambers, Timothy J, Kull, Frederick C, Chamberlain, Stanley D, Hutchins, Jeff T",2
Support from the relationship of genetic and geographic distance in human populations for a serial founder effect originating in Africa.,0
"Equilibrium models of isolation by distance predict an increase in genetic differentiation with geographic distance. Here we find a linear relationship between genetic and geographic distance in a worldwide sample of human populations, with major deviations from the fitted line explicable by admixture or extreme isolation. A close relationship is shown to exist between the correlation of geographic distance and genetic differentiation (as measured by F(ST)) and the geographic pattern of heterozygosity across populations. Considering a worldwide set of geographic locations as possible sources of the human expansion, we find that heterozygosities in the globally distributed populations of the data set are best explained by an expansion originating in Africa and that no geographic origin outside of Africa accounts as well for the observed patterns of genetic diversity. Although the relationship between F(ST) and geographic distance has been interpreted in the past as the result of an equilibrium model of drift and dispersal, simulation shows that the geographic pattern of heterozygosities in this data set is consistent with a model of a serial founder effect starting at a single origin. Given this serial-founder scenario, the relationship between genetic and geographic distance allows us to derive bounds for the effects of drift and natural selection on human genetic variation.",1
"Ramachandran, Sohini, Deshpande, Omkar, Roseman, Charles C, Rosenberg, Noah A, Feldman, Marcus W, Cavalli-Sforza, L Luca",2
Outcomes of a pain management educational initiative at Baylor University Medical Center.,0
"Baylor University Medical Center established a pain initiative group in 1996 to research the effectiveness of pain management throughout the hospital. After analyzing 300 patient surveys, the group undertook an intensive program to educate physicians, nurses, and patients regarding newer pain management techniques. The outcome of this educational initiative was reassessed in 2001 based on surveys completed by 100 patients after discharge. Results showed marked improvement in patient education regarding pain management. In 2001, 93% of patients were offered education and choices regarding pain management vs only 36% in 1996. Fewer patients were afraid to ""bother"" their nurses to ask for pain medication (3% in 2001 vs 14% in 1996). Waiting time for administration of analgesics decreased considerably. The number of patients reporting moderate to severe pain decreased significantly since 1996, yet the overall satisfaction with pain relief remained high and did not change significantly. The overall incidence of patients reporting moderate to severe pain was significantly less at Baylor than the national average. In conclusion, attitudes, misconceptions, and fears about pain management can be changed with intensive educational programs.",1
"Noe, Carl E, Haynsworth, Robert F, Ramsay, Michael A E, Vera, Richard L, Racz, Tibor A, Clark, Timothy, Aguanno, Jean, Steves, Janet, Ganter, Elaine",2
Can psychological distress be detected by response to a needle stick?,0
"The purpose of this study was to determine whether an exaggerated response to a mildly painful stimulus would reflect abnormal levels of psychological distress in patients and, conversely, whether patients who show abnormal levels of psychological distress would have a low tolerance for a mildly painful stimulus. A total of 101 patients were given a mildly painful stimulus (30-gauge needle stick) and asked to record the amount of pain they felt on a scale of 0 to 10 (0 = no pain, 10 = severe pain). The mean response to the needle stick was a 1.9 on this scale. There was no gender difference, and the average did not change with increasing age. Psychological testing showed that 18% of the 101 patients had psychological distress prior to the needle stick. The pain ratings to needle stick of these 18 patients were not significantly different than those of patients without psychological distress (2.3 vs 1.9 on the scale). Seven percent of patients had a very low tolerance for pain (pain score of > or = 7). Evaluation of the psychological testing results on these patients showed no significant difference compared with known normal psychological values. Therefore, the assumption that patients who over-respond to a mildly painful stimulus have psychological distress is not valid. The results of this study suggest only that patients who over-respond to a needle stick have a low tolerance for pain. Furthermore, it is not valid to assume that patients who have psychological distress, poor coping abilities, or marked stress will respond in an exaggerated fashion to a mildly painful stimulus.",1
"Haynsworth, Robert F, Clark, Timothy, Noe, Carl E, Holmes, Jennifer, Havemann, Eric",2
"The use of pejorative terms to describe patients: ""Dirtball"" revisited.",0
"The use of pejorative terms for patients is well documented. Reasons include frustration and anger in managing certain patients, fostering group solidarity among caregivers under stress, and the alleged ""dehumanization"" of medical training. Medical students were surveyed to document and understand the phenomenon.",1
"Dans, Peter E",2
Crossing the quality chasm: lessons from health care quality improvement efforts in England.,0
"The second report from the US Institute of Medicine Crossing the Quality Chasm, highlighted the deficiencies in health care quality in the USA, analyzed the contributory factors, and proposed 13 recommendations for improvements. Clearly, the challenges are enormous. Can anything be learned from the experiences of other countries? This article describes the author's experiences of health care quality improvement efforts in the National Health Service in England and their implications for the USA and for Baylor Health Care System.",1
"Madhok, Rajan",2
Cross-cultural conceptions of pain and pain control.,0
"Pain is a ubiquitous feature of the human experience. This paper presents an anthropology of pain. Anthropology is defined as the cross-cultural and comparative study of human behavior. Pain can be acute and episodic, and pain can be constant and uninterrupted. Acute pain, lasting for minutes or hours, is reported at some time by virtually all adults and by most juveniles and is indicated by the cries and facial expressions of toddlers and infants. This universality of pain as a part of the human condition has been established by the research of many biological, physical, and social scientists. Ethnographers, physicians, and public health experts describe pain complaints for a variety of modern, industrial societies and traditional, undeveloped societies. Pain is the most frequent complaint brought to the offices of physicians in North America, and it is a focus of attention in the literate medical traditions of China, India, and Islamic cultures. Hence, the study of pain and the cultural perceptions of pain are prominent foci of anthropologists. Given that the goal of medicine is to offer medical care to all people who seek it, the practice of modern medicine may be assisted by an exploration of the possibility of cultural differences in medical beliefs and practices in the multiethnic and racially diverse patient populations today.",1
"Free, Mary Moore",2
Description and outcomes of a custom Web-based patient occurrence reporting system developed for Baylor University Medical Center and other system entities.,0
"To improve the timeliness, efficiency, and effectiveness of occurrence reporting.",1
"Dixon, John F, Wielgosz, Christopher, Pires, Mechelle L",2
Description and outcomes of the DoctorQuality incident reporting system used at Baylor Medical Center at Grapevine.,0
To improve error reporting so as to increase patient safety in a health care environment in which many barriers to reporting exist.,1
"Atherton, Traci",2
Management of a single coronary artery aneurysm by use of a stent.,0
A 36-year-old man is described with aneurysmal coronary artery disease successfully treated with a Jomed covered stent. This technique obviates the need for surgical exclusion or ligation of the aneurysm.,1
"Schussler, Jeffrey M, Jones, William H, Vallabhan, Ravi C",2
Dynamic knee motion in anterior cruciate impairment: a report and case study.,0
"Knee motion has been routinely analyzed using radiographic techniques in a static setting. Over the past decade, techniques of in vivo dynamic knee motion analysis have emerged, which have shed light on normal and pathologic knee motion. Most of these methods are either invasive or restricted to small indoor laboratories. This paper describes a new device that records in vivo dynamic knee motion without the restrictions of current techniques and shows results when this device is used with a patient with an anterior cruciate impairment. We believe that dynamic knee motion studies are critical to a full assessment of the effect of an injury and to subsequent rehabilitation and recovery and that this new device can be a useful diagnostic tool.",1
"Komdeur, Prashant, Pollo, Fabian E, Jackson, Robert W",2
Intraperitoneal hyperthermic chemotherapy: experience at Baylor University Medical Center.,0
Patients with peritoneal carcinomatosis have a dismal prognosis despite systemic chemotherapy or palliative surgery. A novel strategy of complete tumor debulking with intraoperative hyperthermia with chemotherapy has been proposed to provide prolonged survival.,1
"Kuhn, Joseph A, McLoughlin, James M, Harris, Daniel C, Talaasen, Loraye J, Sutton, Steven W, McCarty, Todd M",2
Surgical treatment of hyperparathyroidism using the quick parathyroid assay.,0
"The quick intraoperative parathyroid assay (qPTH) has been proposed as an effective tool in the surgical management of hyperparathyroidism. By measuring intact parathyroid hormone intraoperatively, the qPTH assay may facilitate directed exploration for solitary adenomas and may help guide the extent of resection in hyperplasia. In this study, results of the qPTH assay were analyzed prospectively in 63 consecutive patients who underwent exploration for hyperparathyroidism. Blood samples were drawn prior to surgical incision, prior to gland excision, and 5 and 10 minutes after gland excision. A decline >/=50% of the highest preincision or preexcision level within 10 minutes of resection was considered successful. Forty-nine patients (78%) had a solitary parathyroid adenoma. The qPTH assay was successful in 48 (98%) of these patients. One patient showed a delayed decline at 20 minutes. Fourteen patients (22%) had multiglandular disease: 6 with primary hyperplasia, 4 with hyperplasia secondary to renal failure, and 4 with double adenomas. The assay was successful in all of these patients. It detected multiglandular disease in 8 of 14 patients thought preoperatively to have solitary adenoma. Overall, the qPTH assay was successful in 62 of 63 patients (98%). All patients were normocalcemic after a median follow-up interval of 8 months. These data suggest that the qPTH assay can accurately facilitate directed neck exploration for solitary adenomas, guide the extent of resection for hyperplasia, and identify unknown multiglandular disease. It appears to eliminate the most common cause of parathyroidectomy failure, thereby improving surgical success rates while potentially decreasing morbidity, cost, and operative time.",1
"Stratmann, Stacy L, Kuhn, Joseph A, Preskitt, John T, O'Brien, John C, Stephens, Jeffrey S, McCarty, Todd M",2
Comparison of intraparenchymal and intradermal injection for identification of the sentinel node in patients with breast cancer.,0
Sentinel lymph node (SLN) mapping with radioisotope and blue dye has been advocated for the staging of clinically negative axillae in patients with breast cancer. The optimal radiotracer injection technique is still being defined. This study compares the results of intraparenchymal and intradermal injection of technetium 99m (Tc 99m) sulfur colloid to establish an optimal method for SLN localization.,1
"Knox, Sally M, Ley, Carolyn A",2
Risks and complications of neuraxial anesthesia and the use of anticoagulation in the surgical patient.,0
"Recognition of the risk of thromboembolic phenomena to patients in the postsurgical period has resulted in the practice of administering prophylactic anticoagulant agents to those patients who are at high risk for this complication. Institution of a perioperative anticoagulant or antithrombotic protocol needs to be considered when a regional anesthetic is proposed as part of, or as the total, anesthetic management of the patient. This article reviews current data on the risks involved in the use of neuraxial regional anesthesia in the care of surgical patients in whom prophylactic thromboembolic anticoagulant therapy is planned. Guidelines are established to help the physician minimize the risks of a neuraxial hematoma forming, monitor the patient for this complication, and optimally treat him or her if a hematoma were to occur.",1
"Allen, Douglas J, Chae-Kim, Sang H, Trousdale, Devin M",2
Structural and functional analysis of 5S rRNA in Saccharomyces cerevisiae.,0
"5S rRNA extends from the central protuberance of the large ribosomal subunit, through the A-site finger, and down to the GTPase-associated center. Here, we present a structure-function analysis of seven 5S rRNA alleles which are sufficient for viability in the yeast Saccharomyces cerevisiae when expressed in the absence of wild-type 5S rRNAs, and extend this analysis using a large bank of mutant alleles that show semi-dominant phenotypes in the presence of wild-type 5S rRNA. This analysis supports the hypothesis that 5S rRNA serves to link together several different functional centers of the ribosome. Data are also presented which suggest that in eukaryotic genomes selection has favored the maintenance of multiple alleles of 5S rRNA, and that these may provide cells with a mechanism to post-transcriptionally regulate gene expression.",1
"Kiparisov, Sergey, Petrov, Alexey, Meskauskas, Arturas, Sergiev, Petr V, Dontsova, Olga A, Dinman, Jonathan D",2
The HIR corepressor complex binds to nucleosomes generating a distinct protein/DNA complex resistant to remodeling by SWI/SNF.,0
"The histone regulatory (HIR) and histone promoter control (HPC) repressor proteins regulate three of the four histone gene loci during the Saccharomyces cerevisiae cell cycle. Here, we demonstrate that Hir1, Hir2, Hir3, and Hpc2 proteins form a stable HIR repressor complex. The HIR complex promotes histone deposition onto DNA in vitro and constitutes a novel nucleosome assembly complex. The HIR complex stably binds to DNA and nucleosomes. Furthermore, HIR complex binding to nucleosomes forms a distinct protein/DNA complex resistant to remodeling by SWI/SNF. Thus, the HIR complex is a novel nucleosome assembly complex which functions with SWI/SNF to regulate transcription.",1
"Prochasson, Philippe, Florens, Laurence, Swanson, Selene K, Washburn, Michael P, Workman, Jerry L",2
Symplekin and multiple other polyadenylation factors participate in 3'-end maturation of histone mRNAs.,0
"Most metazoan messenger RNAs encoding histones are cleaved, but not polyadenylated at their 3' ends. Processing in mammalian cell extracts requires the U7 small nuclear ribonucleoprotein (U7 snRNP) and an unidentified heat-labile factor (HLF). We describe the identification of a heat-sensitive protein complex whose integrity is required for histone pre-mRNA cleavage. It includes all five subunits of the cleavage and polyadenylation specificity factor (CPSF), two subunits of the cleavage stimulation factor (CstF), and symplekin. Reconstitution experiments reveal that symplekin, previously shown to be necessary for cytoplasmic poly(A) tail elongation and translational activation of mRNAs during Xenopus oocyte maturation, is the essential heat-labile component. Thus, a common molecular machinery contributes to the nuclear maturation of mRNAs both lacking and possessing poly(A), as well as to cytoplasmic poly(A) tail elongation.",1
"Kolev, Nikolay G, Steitz, Joan A",2
The PAS/LOV protein VIVID supports a rapidly dampened daytime oscillator that facilitates entrainment of the Neurospora circadian clock.,0
"A light-entrainable circadian clock controls development and physiology in Neurospora crassa. Existing simple models for resetting based on light pulses (so-called nonparametric entrainment) predict that constant light should quickly send the clock to an arrhythmic state; however, such a clock would be of little use to an organism in changing photoperiods in the wild, and we confirm that true, albeit dampened, rhythmicity can be observed in extended light. This rhythmicity requires the PAS/LOV protein VIVID (VVD) that acts, in the light, to facilitate expression of an oscillator that is related to, but distinguishable from, the classic FREQUENCY/WHITE-COLLAR complex (FRQ/WCC)-based oscillator that runs in darkness. VVD prevents light resetting of the clock at dawn but, by influencing frq RNA turnover, promotes resetting at dusk, thereby allowing the clock to run through the dawn transition and take its phase cues from dusk. Consistent with this, loss of VVD yields a clock whose performance follows the simple predictions of earlier models, and overexpression of VVD restores rhythmicity in the light and sensitivity of phase to the duration of the photoperiod.",1
"Elvin, Mark, Loros, Jennifer J, Dunlap, Jay C, Heintzen, Christian",2
Massive lung collapse with partial resolution after several years: a case report.,0
Bronchitis obliterans is a severe and extremely rare complication of respiratory tract infections in children and is characterized by massive atelectasis and collapse of the affected lung. Of the rare cases reported in the literature all surviving children underwent surgical resection of the collapsed lung.,1
"Govaere, Elke, Van Raemdonck, Dirk, Devlieger, Hugo, Smet, Maria-Helena, Verbeken, Eric, Proesmans, Marijke, De Boeck, Kris",2
Effect of connective tissue growth factor (CCN2/CTGF) on proliferation and differentiation of mouse periodontal ligament-derived cells.,0
"CCN2/CTGF is known to be involved in tooth germ development and periodontal tissue remodeling, as well as in mesenchymal tissue development and regeneration. In this present study, we investigated the roles of CCN2/CTGF in the proliferation and differentiation of periodontal ligament cells (murine periodontal ligament-derived cell line: MPL) in vitro.",1
"Asano, Masahiro, Kubota, Satoshi, Nakanishi, Tohru, Nishida, Takashi, Yamaai, Tomoichiro, Yosimichi, Gen, Ohyama, Kazumi, Sugimoto, Tomosada, Murayama, Yoji, Takigawa, Masaharu",2
Validating a Work Group Climate Assessment Tool for improving the performance of public health organizations.,0
"This article describes the validation of an instrument to measure work group climate in public health organizations in developing countries. The instrument, the Work Group Climate Assessment Tool (WCA), was applied in Brazil, Mozambique, and Guinea to assess the intermediate outcomes of a program to develop leadership for performance improvement. Data were collected from 305 individuals in 42 work groups, who completed a self-administered questionnaire.",1
"Perry, Cary, LeMay, Nancy, Rodway, Greg, Tracy, Allison, Galer, Joan",2
Geographical variation of cerebrovascular disease in New York State: the correlation with income.,0
"Income is known to be associated with cerebrovascular disease; however, little is known about the more detailed relationship between cerebrovascular disease and income. We examined the hypothesis that the geographical distribution of cerebrovascular disease in New York State may be predicted by a nonlinear model using income as a surrogate socioeconomic risk factor.",1
"Han, Daikwon, Carrow, Shannon S, Rogerson, Peter A, Munschauer, Frederick E",2
Early relief of osteoarthritis symptoms with a natural mineral supplement and a herbomineral combination: a randomized controlled trial [ISRCTN38432711].,0
"This study was designed to determine if a natural mineral supplement, sierrasil, alone and in combination with a cat's claw extract (Uncaria guianensis), vincaria, has therapeutic potential in mild to moderate osteoarthritis of the knee.",1
"Miller, Mark J S, Mehta, Komal, Kunte, Sameer, Raut, Vidyanand, Gala, Jayesh, Dhumale, Ramesh, Shukla, Anil, Tupalli, Hemant, Parikh, Himanshu, Bobrowski, Paul, Chaudhary, Jayesh",2
"Ethnic variations in incidence of asthma episodes in England & Wales: national study of 502,482 patients in primary care.",0
"Recent studies have demonstrated marked international variations in the prevalence of asthma, but less is known about ethnic variations in asthma epidemiology within individual countries and in particular the impact of migration on risk of developing asthma. Recent within country comparisons have however revealed that despite originating from areas of the world with a low risk for developing asthma, South Asian and Afro-Caribbean people in the UK are significantly (3x and 2x respectively) more likely to be admitted to hospital for asthma related problems than Whites.",1
"Netuveli, Gopalakrishnan, Hurwitz, Brian, Sheikh, Aziz",2
Interleukin-1beta induced vascular permeability is dependent on induction of endothelial tissue factor (TF) activity.,0
"IL-1beta is a pleotropic cytokine that may mediate increased procoagulant activity and permeability in endothelial tissue during inflammatory conditions. The procoagulant effects of IL-1beta are mediated through induction of tissue factor (TF) but its alterations on vascular permeability are not well characterized. We found that IL-1beta induced a rapid and dose-dependent increase in TF activity in human umbilical vein endothelial cells (ECs) under routine culture conditions. However, IL-1beta caused a rapid and marked increase in permeability across confluent EC monolayers using a two-compartment in vitro model only in the presence of factor VIII-deficient plasma that was completely abrogated by neutralizing anti-TF antibody pre-treatment. In vitro permeability was associated with loss of EC surface expression of VE-cadherin and contraction of F-actin cytoskeletal elements that resulted in EC intercellular gap formation. These data demonstrate that IL-1beta induces marked changes in permeability across activated endothelium via a TF dependent mechanism and suggest that modulation of TF activity may represent a strategy to treat various acute and chronic inflammatory conditions mediated by this cytokine.",1
"Puhlmann, Markus, Weinreich, David M, Farma, Jeffrey M, Carroll, Nancy M, Turner, Ewa M, Alexander, H Richard",2
Expression of Placenta growth factor (PlGF) in non-small cell lung cancer (NSCLC) and the clinical and prognostic significance.,0
"Placenta growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family. Over-expression of PlGF is known to be associated with pathological angiogenesis. This study examined PlGF expression at protein and message levels in non-small cell lung cancer (NSCLC), in which no reports on the significance of PlGF expression is available to date.",1
"Zhang, Lijian, Chen, Jinfeng, Ke, Yang, Mansel, Robert E, Jiang, Wen G",2
Axial stent strut angle influences wall shear stress after stent implantation: analysis using 3D computational fluid dynamics models of stent foreshortening.,0
The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD) models suggest that the vascular geometry created by an implanted stent causes local alterations in wall shear stress (WSS) that are associated with neointimal hyperplasia (NH). Foreshortening is a potential limitation of stent design that may affect stent performance and the rate of restenosis. The angle created between axially aligned stent struts and the principal direction of blood flow varies with the degree to which the stent foreshortens after implantation.,1
"LaDisa, John F, Olson, Lars E, Hettrick, Douglas A, Warltier, David C, Kersten, Judy R, Pagel, Paul S",2
"High-affinity interaction of the N-terminal myristoylation motif of the neuronal calcium sensor protein hippocalcin with phosphatidylinositol 4,5-bisphosphate.",0
"Many proteins are associated with intracellular membranes due to their N-terminal myristoylation. Not all myristoylated proteins have the same localization within cells, indicating that other factors must determine their membrane targeting. The NCS (neuronal calcium sensor) proteins are a family of Ca2+-binding proteins with diverse functions. Most members of the family are N-terminally myristoylated and are either constitutively membrane-bound or have a Ca2+/myristoyl switch that allows their reversible membrane association in response to Ca2+ signals. In the case of hippocalcin and NCS-1, or alternatively KChIP1 (K+ channel-interacting protein 1), their N-terminal myristoylation motifs are sufficient for targeting to distinct organelles. We have shown that an N-terminal myristoylated hippocalcin peptide is able to specifically reproduce the membrane targeting of hippocalcin/NCS-1 when introduced into permeabilized cells. The peptide binds to liposomes containing phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] with high affinity (K(d) 50 nM). Full-length hippocalcin also bound preferentially to liposomes supplemented with PtdIns(4,5)P2. Co-expression of hippocalcin-(1-14)-ECFP (enhanced cyan fluorescent protein) or NCS-1-ECFP partially displaced the expressed PH (pleckstrin homology) domain of phospholipase delta1 from the plasma membrane in live cells, indicating that they have a higher affinity for PtdIns(4,5)P2 than does this PH domain. The Golgi localization of the PH domain of FAPP1 (four-phosphate-adaptor protein 1), which binds to phosphatidylinositol 4-phosphate, was unaffected. The localization of NCS-1 and hippocalcin is likely to be determined, therefore, by their interaction with PtdIns(4,5)P2.",1
"O'Callaghan, Dermott W, Haynes, Lee P, Burgoyne, Robert D",2
"The GTPase RhoA increases utrophin expression and stability, as well as its localization at the plasma membrane.",0
"The Rho family of small GTPases are signalling molecules involved in cytoskeleton remodelling and gene transcription. Their activities are important for many cellular processes, including myogenesis. In particular, RhoA positively regulates skeletal-muscle differentiation. We report in the present study that the active form of RhoA increases the expression of utrophin, the autosomal homologue of dystrophin in the mouse C2C12 and rat L8 myoblastic cell lines. Even though this RhoA-dependent utrophin increase is higher in proliferating myoblasts, it is maintained during myogenic differentiation. This occurs via two mechanisms: (i) transcriptional activation of the utrophin promoter A and (ii) post-translational stabilization of utrophin. In addition, RhoA increases plasma-membrane localization of utrophin. Thus RhoA activation up-regulates utrophin levels and enhances its localization at the plasma membrane.",1
"Bonet-Kerrache, Armelle, Fortier, Mathieu, Comunale, Franck, Gauthier-Rouvière, Cécile",2
Brown recluse spider (Loxosceles reclusa) venom phospholipase D (PLD) generates lysophosphatidic acid (LPA).,0
"Envenomation by the brown recluse spider (Loxosceles reclusa) may cause local dermonecrosis and, rarely, coagulopathies, kidney failure and death. A venom phospholipase, SMaseD (sphingomyelinase D), is responsible for the pathological manifestations of envenomation. Recently, the recombinant SMaseD from Loxosceles laeta was demonstrated to hydrolyse LPC (lysophosphatidylcholine) to produce LPA (lysophosphatidic acid) and choline. Therefore activation of LPA signalling pathways may be involved in some manifestations of Loxosceles envenomation. To begin investigating this idea, we cloned a full-length cDNA encoding L. reclusa SMaseD. The 305 amino acid sequence of the L. reclusa enzyme is 87, 85 and 60% identical with those of L. arizonica, L. intermedia and L. laeta respectively. The recombinant enzyme expressed in bacteria had broad substrate specificity. The lysophospholipids LPC, LPI (18:1-1-oleyol lysophosphatidylinositol), LPS, LPG (18:1-1-oleoyl-lysophosphatidylglycerol), LBPA (18:1-1-oleoyl-lysobisphosphatidic acid) (all with various acyl chains), lyso-platelet-activating factor (C16:0), cyclic phosphatidic acid and sphingomyelin were hydrolysed, whereas sphingosylphosphorylcholine, PC (phosphatidylcholine; C22:6, C20:4 and C6:0), oxidized PCs and PAF (platelet-activating factor; C16:0) were not hydrolysed. The PAF analogue, edelfosine, inhibited enzyme activity. Recombinant enzyme plus LPC (C18:1) induced the migration of A2058 melanoma cells, and this activity was blocked by the LPA receptor antagonist, VPC32183. The recombinant spider enzyme was haemolytic, but this activity was absent from catalytically inactive H37N (His37-->Asn) and H73N mutants. Our results demonstrate that Loxosceles phospholipase D hydrolyses a wider range of lysophospholipids than previously supposed, and thus the term 'SMaseD' is too limited in describing this enzyme.",1
"Lee, Sangderk, Lynch, Kevin R",2
Neutrophil gelatinase-associated lipocalin as a survival factor.,0
"NGAL (human neutrophil gelatinase-associated lipocalin) and its mouse analogue 24p3 are members of the lipocalin family of small secreted proteins. These proteins are up-regulated in a number of pathological conditions, including cancers, and may function as transporters of essential factors. Although previous publications have suggested that 24p3 has pro-apoptotic functions, other data are more suggestive of a survival function. The current study was designed to determine whether NGAL is pro- or anti-apoptotic. Apoptosis induced in human adenocarcinoma A549 cells by the 5-lipoxygenase-activating-protein inhibitor MK886, or several celecoxib-derived PDK1 (phosphoinositide-dependent kinase 1) inhibitors that are devoid of cyclo-oxygenase-2 inhibitory activity, was accompanied by a dose- and time-dependent increase of NGAL mRNA levels, as was reported previously with 24p3. A similar induction of NGAL mRNA was observed in human breast cancer MCF7 cells treated with MK886, indicating this was not a cell-specific effect. Treatment of A549 cells with up to 150 mug/10(6) cells of purified recombinant NGAL protein had no effect on viability, whereas antisera against the full-length NGAL protein induced apoptosis in these cells. The stable overexpression of NGAL in A549 cells had no effect on proliferation or viability. However, the cell death induced by a PDK1 inhibitor was reduced by 50% in NGAL-overexpressing cells. Decreasing NGAL mRNA and protein expression with siRNA (small interfering RNA) in A549 cells increased the toxicity of a PDK1 inhibitor by approx. 45%. These data indicate that, although the induction of NGAL correlates with apoptosis, this induction represents a survival response. Because NGAL is a secreted protein, it may play an extracellular role in cell defence against toxicants and/or facilitate the survival of the remaining cells.",1
"Tong, Zhimin, Wu, Xuli, Ovcharenko, Dmitriy, Zhu, Jiuxiang, Chen, Ching-Shih, Kehrer, James P",2
Lipopolysaccharide rapidly modifies adenosine receptor transcripts in murine and human macrophages: role of NF-kappaB in A(2A) adenosine receptor induction.,0
"The A(2A) adenosine receptor (A(2A)AR) mediates anti-inflammatory actions of adenosine in a variety of cell types. LPS (lipopolysaccharide) was reported to induce a small (<2-fold) increase in the expression of A(2A)AR mRNA in human monocytes and monocytic cell lines. We investigated the effects of LPS on the expression of adenosine receptor mRNAs in primary mouse IPMPhi (intraperitoneal macrophages), human macrophages and Wehi-3 cells. Treatment with 10 ng/ml LPS for 4 h produced a >100-fold increase in A(2A)AR mRNA. LPS-induced increases in mRNA for A(2A)AR and TNFalpha (tumour necrosis factor alpha) are reduced by 90% in IPMPhi pretreated with the NF-kappaB (nuclear factor kappaB) inhibitor, BAY 11-7082 {(E)3-[(4-methylphenyl)sulphonyl]-2-propenenitrile; 10 microM}. In Wehi-3 cells exposed to LPS, A(2A)AR and A(2B)AR transcripts are elevated by 290- and 10-fold respectively, the A(1)AR transcript is unchanged and the A(3)AR transcript is decreased by 67%. The induction of A(2A)AR mRNA by LPS is detectable after 1 h, reaches a peak at 6 h at 600 times control and remains elevated beyond 24 h. The ED50 (effective dose) of LPS is 2.3 ng/ml. A(2A)AR receptor number, measured by 125I-ZM241385 binding to whole cells, is undetectable in naïve cells and increases linearly at a rate of 23 receptors x cell(-1) x min(-1) to a B(max) of 348 fmol/mg (28000 receptors/cell) in 20 h. The increase in receptor number is correlated with an increase in the potency of an A(2A) agonist (4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester; referred to as ATL146e) to stimulate cAMP in these cells. After LPS pretreatment, the potency of the A(2A) agonist, ATL146e, to reduce TNFalpha release from IPMPhi was increased by 200-fold. The results support the hypothesis that regulation of adenosine receptor expression, especially up-regulation of the A(2A)AR, is part of a delayed feedback mechanism initiated through NF-kappaB to terminate the activation of human and mouse macrophages.",1
"Murphree, Lauren J, Sullivan, Gail W, Marshall, Melissa A, Linden, Joel",2
Characterization of a c-Jun-responsive module in the 5'-flank of the human CYP2J2 gene that regulates transactivation.,0
"The human cytochrome P450 2J2 (CYP2J2) generates cytoprotective epoxyeicosatrienoic acids from arachidonic acid. Expression of CYP2J2 is decreased in hypoxia, and the resultant decrease in CYP2J2-derived epoxyeicosanoids may contribute to the pathogenesis of cardiac ischaemia. Recent studies have indicated that AP-1 (activator protein-1) regulates CYP2J2 expression in normoxia and hypoxia. Down-regulation of CYP2J2 in hypoxic HepG2 cells was closely associated with the up-regulation of c-fos and transient transfection analysis demonstrated that c-Fos abolishes the activation of CYP2J2 by the AP-1 protein c-Jun. Deletion of the region between nt -122 and -50 upstream of the start codon in CYP2J2 prevented c-Jun transactivation. In this study we demonstrate that the sequence at -105/-95 is a major regulatory element that binds c-Jun and has a prominent role in CYP2J2 gene transactivation. Mutagenesis of both the -105/-95 region and the previously identified element at -56/-63 was required for complete loss of transactivation by c-Jun; separate mutagenesis of the -105/-95 element or, to a lesser extent, the -56/-63 element resulted in a partial loss of gene activation. In contrast to the behaviour of the -56/-63 element, c-Jun homodimers and c-Fos/c-Jun heterodimers bound to the -105/-95 element. These findings demonstrate that the c-Jun-responsive module between -122 and -50 in the CYP2J2 proximal promoter contains an atypical AP-1 element at -105/-95 that has a major role in c-Jun transactivation and acts in conjunction with the -56/-63 element to regulate expression.",1
"Marden, Nicole Y, Murray, Michael",2
"The penta-EF-hand protein ALG-2 interacts directly with the ESCRT-I component TSG101, and Ca2+-dependently co-localizes to aberrant endosomes with dominant-negative AAA ATPase SKD1/Vps4B.",0
"ALG-2 (apoptosis-linked gene 2) is a Ca2+-binding protein that belongs to the PEF (penta-EF-hand) protein family. Alix (ALG-2-interacting protein X)/AIP1 (ALG-2-interacting protein 1), one of its binding partners, interacts with TSG101 and CHMP4 (charged multivesicular body protein 4), which are components of ESCRT-I (endosomal sorting complex required for transport I) and ESCRT-III respectively. In the present study, we investigated the association between ALG-2 and ESCRT-I. By a GST (glutathione S-transferase) pull-down assay using HEK-293T (human embryonic kidney 293T) cell lysates, endogenous TSG101 and two other exogenously expressed ESCRT-I components [hVps28 (human vacuolar protein sorting 28) and hVps37A] were shown to associate with GST-ALG-2 in the presence of Ca2+. By the yeast two-hybrid assay, however, a positive interaction was observed with only TSG101 among the three ESCRT-I components, suggesting that ALG-2 associates with hVps28 and hVps37A indirectly through TSG101. Using various deletion mutants of TSG101, the central PRR (proline-rich region) was found to be sufficient for interaction with ALG-2 by the GST-pull-down assay. Direct binding of ALG-2 to the TSG101 PRR was demonstrated by an overlay assay using biotin-labelled ALG-2 as a probe. In immunofluorescence microscopic analysis of HeLa cells that overexpressed a GFP (green fluorescent protein)-fused ATPase-defective dominant-negative form of SKD1/Vps4B (GFP-SKD1(E235Q)), ALG-2 exhibited a punctate distribution at the perinuclear area and co-localized with GFP-SKD1(E235Q) to aberrant endosomes. This punctate distribution of ALG-2 was markedly diminished by treatment of HeLa cells with a membrane-permeant Ca2+ chelator. Moreover, a Ca2+-binding-defective mutant of ALG-2 did not co-localize with GFP-SKD1(E235Q). Our findings suggest that ALG-2 may function as a Ca2+-dependent accessory protein of the endosomal sorting machinery by interacting directly with TSG101 as well as with Alix.",1
"Katoh, Keiichi, Suzuki, Hidenori, Terasawa, Yoshinori, Mizuno, Takako, Yasuda, Jiro, Shibata, Hideki, Maki, Masatoshi",2
Idiopathic chronic cough: a real disease or a failure of diagnosis?,0
"Despite extensive diagnostic evaluation and numerous treatment trials, a number of patients remain troubled by a chronic and uncontrollable cough. Eosinophilic bronchitis, atopic cough and non-acid reflux have been recently added to the diagnostic spectrum for chronic cough. In some cases, failure to consider these conditions may explain treatment failure. However, a subset of patients with persisting symptoms may be regarded as having an idiopathic cough. These individuals are most commonly female, of postmenopausal age and frequently report viral upper respiratory tract infections as an initiating event. This paper seeks to explore the validity of idiopathic cough as a distinct clinical entity.",1
"McGarvey, L P A",2
Vascular basis of mucosal color.,0
"Besides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics.",1
"Kleinheinz, Johannes, Büchter, André, Fillies, Thomas, Joos, Ulrich",2
Cephalometric norms for the Saudi children living in the western region of Saudi Arabia: a research report.,0
"Previous studies have established specific cephalometric norms for children with different ethnic backgrounds, showing different facial features for each group. Up till now, there is a paucity of information about the cephalometric features of Saudi children living in the western region of Saudi Arabia, who have distinct social and climatic characteristics. The aim of the present study was to establish cephalometric norms for children living in the western region of Saudi Arabia.",1
"Hassan, Ali H",2
Strain driven fast osseointegration of implants.,0
"Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved.",1
"Joos, Ulrich, Büchter, Andre, Wiesmann, Hans-Peter, Meyer, Ulrich",2
Trends and characteristics of oral and maxillofacial injuries in Nigeria: a review of the literature.,0
"The etiology of maxillofacial injuries varies from one country to another and even within the same country depending on the prevailing socioeconomic, cultural and environmental factors. Periodic verification of the etiology of maxillofacial injuries helps to recommend ways in which maxillofacial injuries can be averted. The aim of the present study is therefore to analyse the characteristics and trends of maxillofacial injuries in Nigeria based on a systematic review of the literature.",1
"Adeyemo, Wasiu Lanre, Ladeinde, Akinola Ladipo, Ogunlewe, Mobolanle Olugbemiga, James, Olutayo",2
"High throughput, high resolution selection of polymorphic microsatellite loci for multiplex analysis.",0
"Large-scale genetic profiling, mapping and genetic association studies require access to a series of well-characterised and polymorphic microsatellite markers with distinct and broad allele ranges. Selection of complementary microsatellite markers with non-overlapping allele ranges has historically proved to be a bottleneck in the development of multiplex microsatellite assays. The characterisation process for each microsatellite locus can be laborious and costly given the need for numerous, locus-specific fluorescent primers.",1
"Cryer, Nicholas C, Butler, David R, Wilkinson, Mike J",2
A rapid and versatile combined DNA/RNA extraction protocol and its application to the analysis of a novel DNA marker set polymorphic between Arabidopsis thaliana ecotypes Col-0 and Landsberg erecta.,0
"Many established PCR-based approaches in plant molecular biology rely on lengthy and expensive methods for isolation of nucleic acids. Although several rapid DNA isolation protocols are available, they have not been tested for simultaneous RNA isolation for RT-PCR applications. In addition, traditional map-based cloning technologies often use ill-proportioned marker regions even when working with the model plant Arabidopsis thaliana, where the availability of the full genome sequence can now be exploited for the creation of a high-density marker systems.",1
"Berendzen, Kenneth, Searle, Iain, Ravenscroft, Dean, Koncz, Csaba, Batschauer, Alfred, Coupland, George, Somssich, Imre E, Ülker, Bekir",2
Serial changes in the T1 magnetic relaxation parameter after myocardial infarction in man.,0
"A low field resistive nuclear magnetic resonance imaging system (0.08 Tesla) was used to study the in vivo changes in the relaxation parameter T1 of the left ventricular myocardium from the first day to six months after acute myocardial infarction in 41 consecutive patients admitted to a coronary care unit. T1 maps were constructed from transverse and coronal images at various times after infarction. Thrombolytic treatment had been successful in 28 patients. Thirty three of the 34 patients studied within two weeks of infarction had a significantly increased T1 value but this developed only after the third day in four. At day 1-3 the mean (1 SD) maximum T1 was 413 (29) ms (n = 23) compared with 430 (41) ms (n = 22) at day 4-7, 433 (35) ms (n = 24) at day 8-14, 420 (34) at one month (n = 22), 388 (39) (n = 20) at three months, and 361 (24) (n = 14) at six months. The number of regions of interest with an increased T1 followed a similar time course. Although the increase in T1 measured at three months correlated with the initial maximum creatine kinase and with the left ventricular ejection fraction measured at one month, the number of regions with abnormal T1 from day 4 through to one month correlated best with left ventricular ejection fraction. There was no significant difference in T1 between patients with or without reperfusion. The rise in T1 over the first few days together with the prolonged time course of T1 increase suggests that the increase in T1 may reflect cellular infiltration as much or more than tissue oedema.",1
"Been, M, Smith, M A, Ridgway, J P, Douglas, R H, de Bono, D P, Best, J J, Muir, A L",2
Gene interaction network suggests dioxin induces a significant linkage between aryl hydrocarbon receptor and retinoic acid receptor beta.,0
"Gene expression arrays (gene chips) have enabled researchers to roughly quantify the level of mRNA expression for a large number of genes in a single sample. Several methods have been developed for the analysis of gene array data including clustering, outlier detection, and correlation studies. Most of these analyses are aimed at a qualitative identification of what is different between two samples and/or the relationship between two genes. We propose a quantitative, statistically sound methodology for the analysis of gene regulatory networks using gene expression data sets. The method is based on Bayesian networks for direct quantification of gene expression networks. Using the gene expression changes in HPL1A lung airway epithelial cells after exposure to 2,3,7,8-tetrachlorodibenzo-(Italic)p(/Italic)-dioxin at levels of 0.1, 1.0, and 10.0 nM for 24 hr, a gene expression network was hypothesized and analyzed. The method clearly demonstrates support for the assumed network and the hypothesis linking the usual dioxin expression changes to the retinoic acid receptor system. Simulation studies demonstrated the method works well, even for small samples.",1
"Toyoshiba, Hiroyoshi, Yamanaka, Takeharu, Sone, Hideko, Parham, Frederick M, Walker, Nigel J, Martinez, Jeanelle, Portier, Christopher J",2
"Dissociation of ribulose-1,5-bisphosphate bound to ribulose-1,5-bisphosphate carboxylase/oxygenase and its enhancement by ribulose-1,5-bisphosphate carboxylase/oxygenase activase-mediated hydrolysis of ATP.",0
"Ribulose bisphosphate (RuBP), a substrate of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is an inhibitor of Rubisco activation by carbamylation if bound to the inactive, noncarbamylated form of the enzyme. The effect of Rubisco activase on the dissociation kinetics of RuBP bound to this form of the enzyme was examined and characterized with the use of (3)H-labeled RuBP and proteins purified from spinach (Spinacia oleracea L.) In the absence of Rubisco activase and in the presence of a large excess of unlabeled RuBP, the dissociation rate of bound [1-(3)H]RuBP was much faster after a short (30 second) incubation than after an extended incubation (1 hour). After 1 hour of incubation, the dissociation rate constant (K(off)) of the bound RuBP was 4.8 x 10(-4) per second, equal to a half-time of about 35 minutes, whereas the rate after only 30 seconds was too fast to be accurately measured. This time-dependent change in the dissociation rate was reflected in the subsequent activation kinetics of Rubisco in the presence of RuBP, CO(2), and Mg(2+), and in both the absence or presence of Rubisco activase. However, the activation of Rubisco also proceeded relatively rapidly without Rubisco activase if the RuBP level decreased below the estimated catalytic site concentration. High pH (pH 8.5) and the presence of Mg(2+) in the medium also enhanced the dissociation of the bound RuBP from Rubisco in the presence of RuBP. In the presence of Rubisco activase, Mg(2+), ATP (but not the nonhydrolyzable analog, adenosine-5'-O-[3-thiotriphosphate]), excess RuBP, and an ATP-regenerating system, the dissociation of [1-(3)H]RuBP from Rubisco was increased in proportion to the amount of Rubisco activase added. This result indicates that Rubisco activase-mediated hydrolysis of ATP is required for promotion of the enhanced dissociation of the bound RuBP from Rubisco. Furthermore, product analysis by ion-exchange chromatography demonstrated that the release of the bound RuBP, in an unchanged form, was considerably faster than the observed increase in Rubisco activity. Thus, RuBP dissociation was experimentally separated from activation and precedes the subsequent formation of active, carbamylated Rubisco during activation of Rubisco by Rubisco activase.",1
"Wang, Z Y, Portis, A R",2
"Cloning, characterization, and expression of a cDNA encoding a 50-kilodalton protein specifically induced by cold acclimation in wheat.",0
"We have isolated, sequenced, and expressed a cold-specific cDNA clone, Wcs120, that specifically hybridizes to a major mRNA species of approximately 1650 nucleotides from cold-acclimated wheat (Triticum aestivum L.). The accumulation of this mRNA was induced in less than 24 hours of cold treatment, and remained at a high steady-state level during the entire period of cold acclimation in the two freezing-tolerant genotypes of wheat tested. The expression of Wcs120 was transient in a less-tolerant genotype even though the genomic organization of the Wcs120 and the relative copy number were the same in the three genotypes. The mRNA level decreased rapidly during deacclimation and was not induced by heat shock, drought, or abscisic acid. The Wcs120 cDNA contains a long open reading frame encoding a protein of 390 amino acids. The encoded protein is boiling stable, highly hydrophilic, and has a compositional bias for glycine (26.7%), threonine (16.7%), and histidine (10.8%), although cysteine, phenylalanine, and tryptophan were absent. The WCS120 protein contains two repeated domains. Domain A has the consensus amino acid sequence GEKKGVMENIKEKLPGGHGDHQQ, which is repeated 6 times, whereas domain B has the sequence TGGTYGQQGHTGTT, which is repeated 11 times. The two domains were also found in barley dehydrins and rice abscisic acid-induced protein families. The expression of this cDNA in Escherichia coli, using the T(7) RNA polymerase promoter, produced a protein of 50 kilodaltons with an isoelectric point of 7.3, and this product comigrated with a major protein synthesized in vivo and in vitro during cold acclimation.",1
"Houde, M, Danyluk, J, Laliberté, J F, Rassart, E, Dhindsa, R S, Sarhan, F",2
Evidence for circadian regulation of starch and sucrose synthesis in sugar beet leaves.,0
"Starch accumulation and sucrose synthesis and export were measured in leaves of sugar beet (Beta vulgaris L.) during a period of prolonged irradiance in which illumination was extended beyond the usual 14-hour day period. During much of the 14-hour day period, approximately 50% of the newly fixed carbon was distributed to sucrose, about 40% to starch, and less than 10% to hexose. Beginning about 2 hours before the end of the usual light period, the portion of newly fixed carbon allocated to sucrose gradually increased, and correspondingly less carbon went to starch. By the time the transition ended, about 4 hours into the extension of the light period, nearly 90% of newly fixed carbon was incorporated into sucrose and little or none into starch. Most of the additional sucrose was exported. Gradual cessation of starch accumulation was not the result of a futile cycle of simultaneous starch synthesis and degradation. Neither was it the result of a decrease in the extractable activity of adenosine diphosphoglucose pyrophosphorylase or phosphoglucose isomerase, enzymes important in starch synthesis. Nor was there a notable change in control metabolites considered to be important in regulating starch synthesis. Starch accumulation appeared to decrease markedly because of an endogenous circadian shift in carbon allocation, which occurred in preparation for the usual night period and which diverted carbon from the chloroplast to the cytosol and sucrose synthesis.",1
"Li, B, Geiger, D R, Shieh, W J",2
Transport Interactions between Paraquat and Polyamines in Roots of Intact Maize Seedlings.,0
"Interactions between absorption of paraquat and the polyamines putrescine, cadaverine, and spermine in roots of intact maize (Zea mays L. cv 3377 Pioneer) seedlings were examined. Concentration-dependent kinetics for paraquat and putrescine influx were similar and both kinetic curves could be resolved into a linear and a saturable component. The linear component was previously shown to represent cell wall/membrane binding. The saturable components for paraquat and putrescine uptake, which represent influx across the plasmalemma, had K(m) values of 98 and 120 micromolar, respectively, and V(max) values of 445 and 456 nanomoles per gram fresh weight per hour, respectively. Lineweaver-Burk transformation of the saturable component of paraquat influx in the presence of varying concentrations of putrescine indicated that the diamine competitively inhibited the saturable component of paraquat uptake. Reciprocal experiments similarly demonstrated that paraquat competitively inhibited the saturable component of putrescine uptake. Competitive inhibition of both paraquat and putrescine influx could also be demonstrated with the diamine cadaverine, which has a charge distribution similar to that of paraquat and putrescine. In contrast, the larger, tetravalent polyamine spermine appeared to noncompetitively inhibit the influx of paraquat and putrescine. These results strongly suggest that paraquat enters maize root cells via a carrier system that normally functions in the transport of diamines with a charge distribution similar to that of paraquat.",1
"Hart, J J, Ditomaso, J M, Linscott, D L, Kochian, L V",2
Regulation of Plastid Gene Expression during Photooxidative Stress.,0
"We have used the carotenoid biosynthesis inhibitor norflurazon to study the relationship between chloroplast and nuclear gene expression and the mechanisms by which plastid mRNA accumulation is regulated in response to photooxidative stress. By treating 4-week-old hydroponic spinach plants (Spinacea oleracea), we were able to determine the response at two distinct stages of chloroplast development. For all parameters studied, differences were found between the norflurazon-treated young and mature leaves. Young leaves lost essentially all pigment content in the presence of norflurazon, whereas mature leaves retained more than 60% of their chlorophyll and carotenoids. The accumulation of plastid mRNA was determined for several genes, and we found a decrease in mRNA levels for all genes except psbA in herbicide-treated young leaves. For genes such as atpB, psbB, and psaA, there was a corresponding change in the relative level of transcription, but for psbA and rbcL, transcription and mRNA accumulation were uncoupled. In norflurazon-treated mature leaves, all plastid mRNAs except psaA accumulated to normal levels, and transcription levels were either normal or higher than corresponding controls. This led to the conclusion that plastid mRNA accumulation is regulated both transcriptionally and posttranscriptionally in response to photooxidative stress. Although direct photooxidative damage is confined to the plastid and peroxisome, there is a feedback of information controlling the transcription of nuclear-encoded plastid proteins. Considerable evidence has accumulated implicating a ""plastid factor"" in this control. Therefore, the expression of several nuclear-encoded plastid proteins and the corresponding mRNAs were determined. Although the levels of both the small subunit of ribulose-1,5-bisphosphate carboxylase and the light harvesting chlorophyll a/b-binding protein and corresponding mRNAs were reduced, a 28-kilodalton chloroplast RNA-binding protein and corresponding mRNA were at normal levels in norflurazon-treated plants. Changes in mRNA and protein levels were not the result of a general loss due to photooxidation but rather the result of selective stabilization of certain components. The response of both genomes to photooxidative stress is discussed in terms of the postulated plastid factor.",1
"Tonkyn, J C, Deng, X W, Gruissem, W",2
Involvement of Calmodulin and Calmodulin-Dependent Myosin Light Chain Kinase in Blue Light-Dependent H Pumping by Guard Cell Protoplasts from Vicia faba L.,0
"Signal transduction processes involved in blue light-dependent proton pumping were investigated using guard cell protoplasts from Vicia faba.N-[2-(Methylamino)ethyl]-5-isoquinolinesulfonamide, an inhibitor of cyclic AMP- and cyclic GMP-dependent protein kinases, had no effect. 1-(5-Isoquinolinesulfonyl)-2-methylpiperazine (H-7) and calphostin C, inhibitors of protein kinase C, produced slight inhibition of the blue light-dependent proton pumping. 1-[N, O-Bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl] -4-phenylpiperazine, a specific inhibitor of Ca(2+)/calmodulin (CaM)-dependent protein kinase II, did not inhibit the proton pumping, but 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine and 1-(5-chloro-naphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), inhibitors of Ca(2+)/CaM-dependent myosin light chain kinase, strongly suppressed the proton pumping. A CaM antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), inhibited blue light-dependent proton pumping, whereas its less active structural analog, N-(6-aminohexyl)-1-naphthalenesulfonamide (W-5), had little effect on the response. Other CaM antagonists, trifluoperazine, compound 48/80, prenylamine, and 3-(2-benzothiazolyl)-4,5-dimethoxy-N-[3-(4-phenyl-piperidinyl)- propylbenzenesulfonamide inhibited the proton pumping. In accord with these results, light-induced stomatal opening in the epidermis of Commelina benghalensis ssp. was inhibited by ML-9 and W-7, but not by H-7 and W-5. Thus, it is concluded that CaM and Ca(2+)/CaM-dependent myosin light chain kinase are the components of the signal transduction process in blue light-dependent proton pumping in guard cells.",1
"Shimazaki, K, Kinoshita, T, Nishimura, M",2
Time threshold for second positive phototropism is decreased by a preirradiation with red light.,0
"A second positive phototropic response is exhibited by a plant after the time of irradiation has exceeded a time threshold.  The time threshold of dark-grown seedlings is about 15 minutes for Arabidopsis thaliana.  This threshold is decreased to about 4 minutes by a 669-nanometer preirradiation.  Tobacco (Nicotiana tabacum) seedlings show a similar response.  The time threshold of dark-grown seedlings is about 60 minutes for tobacco, and is decreased to about 15 minutes after a preirradiation with either 450- or 669- nanometer light.  The existence of a time threshold for second positive phototropism and the dependence of this threshold on the irradiation history of the seedling contribute to the complexity of the fluence response relationship for phototropism.",1
"Janoudi A-K, R, Konjevic, P, Apel, K L, Poff, K L",2
Control of Photosynthesis and Stomatal Conductance in Ricinus communis L. (Castor Bean) by Leaf to Air Vapor Pressure Deficit.,0
"Castor bean (Ricinus communis L.) has a high photosynthetic capacity under high humidity and a pronounced sensitivity of photosynthesis to high water vapor pressure deficit (VPD). The sensitivity of photosynthesis to varying VPD was analyzed by measuring CO(2) assimilation, stomatal conductance (g(s)), quantum yield of photosystem II (phi(II)), and nonphotochemical quenching of chlorophyll fluorescence (q(N)) under different VPD. Under both medium (1000) and high (1800 micromoles quanta per square meter per second) light intensities, CO(2) assimilation decreased as the VPD between the leaf and the air around the leaf increased. The g(s) initially dropped rapidly with increasing VPD and then showed a slower decrease above a VPD of 10 to 20 millibars. Over a temperature range from 20 to 40 degrees C, CO(2) assimilation and g(s) were inhibited by high VPD (20 millibars). However, the rate of transpiration increased with increasing temperature at either low or high VPD due to an increase in g(s). The relative inhibition of photosynthesis under photorespiring (atmospheric levels of CO(2) and O(2)) versus nonphotorespiring (700 microbars CO(2) and 2% O(2)) conditions was greater under high VPD (30 millibars) than under low VPD (3 millibars). Also, with increasing light intensity the relative inhibition of photosynthesis by O(2) increased under high VPD, but decreased under low VPD. The effect of high VPD on photosynthesis under various conditions could not be totally accounted for by the decrease in the intercellular CO(2) in the leaf (C(i)) where C(i) was estimated from gas exchange measurements. However, estimates of C(i) from measurements of phi(II) and q(N) suggest that the decrease in photosynthesis and increase in photorespiration under high VPD can be totally accounted for by stomatal closure and a decrease in C(i). The results also suggest that nonuniform closure of stomata may occur in well-watered plants under high VPD, causing overestimates in the calculation of C(i) from gas exchange measurements. Under low VPD, 30 degrees C, high light, and saturating CO(2), castor bean (C(3) tropical shrub) has a rate of photosynthesis (61 micromoles CO(2) per square meter per second) that is about 50% higher than that of tobacco (C(3)) or maize (C(4)) under the same conditions. The chlorophyll content, total soluble protein, and ribulose-1,5-bisphosphate carboxylase/oxygenase level on a leaf area basis were much higher in castor bean than in maize or tobacco, which accounts for its high rates of photosynthesis under low VPD.",1
"Dai, Z, Edwards, G E, Ku, M S",2
Identification of factors regulating the phosphorylation status of sucrose-phosphate synthase in vivo.,0
"The purpose of this study was to identify the factors that control sucrose-phosphate synthase (SPS)-kinase and SPS-protein phosphatase (SPS-PP) activity in situ, and thereby mediate the activation of SPS by light or mannose. Feeding mannose to excised spinach (Spinacia oleracea) leaves in darkness resulted in a general sequestration of cellular phosphate (as evidenced by accumulation of mannose-6-P and depletion of glucose-6-P [Glc-6-P] and fructose-6-P [Fru-6-P]) and a relatively slow activation of SPS (maximum activation achieved within 90 min). Supplying exogenous inorganic phosphate (Pi) with mannose reduced sequestration of cellular Pi (as evidenced by mannose-6-P accumulation without depletion of hexose-P) and substantially reduced mannose activation of SPS. Thus, depletion of cytoplasmic Pi may be required for SPS activation; accumulation of mannose-6-P alone is clearly not sufficient. It was verified that Glc-6-P, but not mannose-6-P, was an inhibitor of partially purified SPS-kinase, and that Pi was an inhibitor of partially purified SPS-PP. Total extractable activity of SPS-kinase did not vary diurnally, whereas a pronounced light activation of SPS-PP activity was observed. Pretreatment of leaves in the dark with cycloheximide blocked the light activation of SPS-PP (assayed in vitro) and dramatically reduced the rate of SPS activation in situ (in saturating light and carbon dioxide). We conclude that rapid activation of SPS by light involves reduction in cytosolic Pi, an inhibitor of SPS-PP, and light activation of SPS-PP, by a novel mechanism that may involve (directly or indirectly) a protein synthesis step. An increase in cytosolic Glc-6-P, an inhibitor of SPS-kinase, would also favor SPS activation. Thus, the signal transduction pathway mediating the light activation of SPS involves elements of ""fine"" and ""coarse"" control.",1
"Weiner, H, McMichael, R W, Huber, S C",2
"Regulation of photosynthesis by end-product accumulation in leaves of plants storing starch, sucrose, and hexose sugars.",0
"In the present study, leaves of different plant species were girdled by the hot wax collar method to prevent export of assimilates. Photosynthetic activity of girdled and control leaves was evaluated 3 to 7 days later by two methods: (a) carbon exchange rate (CER) of attached leaves was determined under ambient CO(2) concentrations using a closed gas system, and (b) maximum photosynthetic capacity (A(max)) was determined under 3% CO(2) with a leaf disc O(2) electrode. Starch, hexoses, and sucrose were determined enzymically. Typical starch storers like soybean (Glycine max L.) (up to 87.5 milligrams of starch per square decimeter in girdled leaves), cotton (Gossypium hirsutum L.), and cucumber (Cucumis sativus L.) responded to 7 days of girdling by increased (80-100%) stomatal resistance (r(s)) and decreased A(max) (>50%). On the other hand, spinach (Spinacia oleracea L.), a typical sucrose storer (up to 160 milligrams of sucrose per square decimeter in girdled leaves), showed only a slight reduction in CER and almost no change in A(max). Intermediate plants like tomato (Lycopersicon esculentum Mill.), sunflower (Helianthus annuus L.), broad bean (Vicia faba L.), bean (Phaseolus vulgaris L.), and pea (Pisum sativum L.), which upon girdling store both starch and sucrose, responded to the girdle by a considerable reduction in CER but only moderate inhibition of A(max), indicating that the observed reduction in CER was primarily a stomatal response. Both the wild-type tobacco (Nicotiana sylvestris) (which upon girdling stored starch and hexoses) and the starchless mutant (which stored only hexoses, up to 90 milligrams per square decimeter) showed 90 to 100% inhibition of CER and approximately 50% inhibition of A(max). In general, excised leaves (6 days) behaved like girdled leaves of the respective species, showing 50% reduction of A(max) in wild-type and starchless N. sylvestris but only slight decline of A(max) in spinach. The results of the present study demonstrate the possibility of the occurrence of end-product inhibition of photosynthesis in a large number of crop plants. The long-term inhibition of photosynthesis in girdled leaves is not confined to stomatal responses since the A(max) declined up to 50%. The inhibition of A(max) by girdling was strongest in starch storers, but starch itself cannot be directly responsible, because the starchless mutant of N. sylvestris was also strongly inhibited. Similarly, the inhibition cannot be attributed to hexose sugars either, because soybean, cotton, and cucumber are among the plants most strongly inhibited although they do not maintain a large hexose pool. Spinach, a sucrose storer, showed the least inhibition in both girdled and excised leaf systems, which indicates that sucrose is probably not directly responsible for the end-product inhibition of photosynthesis. The occurrence of strong end-product inhibition appears to be correlated with high acid-invertase activity in fully expanded leaves. The inhibition may be related to the nature of soluble sugar metabolism in the extrachloroplastic compartment and may be caused by a metabolite that has different rates of accumulation and turnover in sucrose storers and other plants.",1
"Goldschmidt, E E, Huber, S C",2
Carbon Partitioning and Growth of a Starchless Mutant of Nicotiana sylvestris.,0
"We have further characterized the photosynthetic carbohydrate metabolism and growth of a starchless mutant (NS 458) of Nicotiana sylvestris that is deficient in plastid phosphoglucomutase (Hanson KR, McHale NA [1988] Plant Physiol 88: 838-844). In general, the mutant had only slightly lower rates of photosynthesis under ambient conditions than the wild type. However, accumulation of soluble sugars (primarily hexose sugars) in source leaves of the mutant compensated for only about half of the carbon stored as starch in the wild type. Therefore, the export rate was slightly higher in the mutant relative to the wild type. Starch in the wild type and soluble sugars in the mutant were used to support plant growth at night. Growth of the mutant was progressively restricted, relative to wild type, when plants were grown under shortened photoperiods. When grown under short days, leaf expansion of the mutant was greater during the day, but was restricted at night relative to wild-type leaves, which expanded primarily at night. We postulate that restricted growth of the mutant on short days is the result of several factors, including slightly lower net photosynthesis and inability to synthesize starch in both source and sink tissues for use at night. In short-term experiments, increased ""sink demand"" on a source leaf (by shading all other source leaves) had no immediate effect on starch accumulation during the photoperiod in the wild type or on soluble sugar accumulation in the mutant. These results would be consistent with a transport limitation in N. sylvestris such that not all of the additional carbon flux into sucrose in the mutant can be exported from the leaf. Consequently, the mutant accumulates hexose sugars during the photoperiod, apparently as the result of sucrose hydrolysis within the vacuole by acid invertase.",1
"Huber, S C, Hanson, K R",2
Molecular and physiological analysis of a heat-shock response in wheat.,0
"We have isolated two cDNA clones from wheat (Triticum aestivum L. var Stephens), designated WHSP16.8 and WHSP16.9, that are highly similar in sequence to the low molecular weight heat-shock protein genes previously isolated from soybean. RNA blot analysis confirms that these sequences are present in heat-shocked wheat seedlings, but not in control tissues. The WHSP16.8 and WHSP16.9 cDNAs were isolated by screening a lambda gt11 expression library with antibodies to HMGc (a chromosomal protein of wheat). Immunoblot analysis has demonstrated that the antibodies raised against HMGc also recognize a group of proteins that are induced by heat shock and have molecular weights (estimated by sodium dodecyl sulfate electrophoresis) consistent with the molecular weights of the proteins deduced from the sequences of the cDNAs.",1
"McElwain, E F, Spiker, S",2
Wheat vegetative nitrogen compositional changes in response to reduced reproductive sink strength.,0
"N redistribution patterns and the N composition of vegetative tissues above the peduncle node of wheat (Triticum aestivum L.) plants with altered reproductive sink strength were evaluated to determine the role of vegetative storage proteins in the temporary storage of excess N destined for export. The degree of leaf senescence symptoms (loss of chlorophyll, total N, and ribulose-1,5-bisphosphate carboxylase/oxygenase) were initially reduced, but the complete senescence of vegetative tissues proceeded even for plants completely lacking reproductive sinks. Plants with 50% less sink strength than control plants with intact spikes redistributed vegetative N to the spike almost as effectively as the control plants. Plants without reproductive sinks exported less N from the flag leaf and had flag leaf blades and peduncle tissues with higher soluble protein and alpha-NH(2) amino acid levels than control plants. An abundant accumulation of polypeptides in the soluble protein profiles of vegetative tissues was not evident in plants with reduced sink strength. Storage of amino acids apparently accommodates any excess N accumulated by vegetative tissues during tissue reproductive growth. Any significant role of vegetative storage proteins in the N economy of wheat is unlikely.",1
"Mackown, C T, Van Sanford, D A, Zhang, N",2
Substrate specificity of pyrophosphate:fructose 6-phosphate 1-phosphotransferase from potato tuber.,0
"The aim of this work was to establish the precise ionic form of the reactants used by pyrophosphate:fructose-6-phosphate phosphotransferase. The enzyme was purified to near-homogeneity from potato (Solanum tuberosum L.) tubers. Changes in enzyme activity when the pH of the assay and the concentration of fructose 6-phosphate, pyrophosphate, and magnesium are varied independently indicate that fructose 6-phosphate(2-) and MgP(2)O(7) (2-) are the reacting species in the glycolytic direction. Analogous experiments with fructose 1,6-bisphosphate, inorganic phosphate, and magnesium demonstrate that the enzyme uses fructose 1,6-bisphosphate(4-), HPO(4) (2-), and Mg(2+) in the gluconeogenic direction. The ionic species used in the glycolytic direction are comparable with those required by bacterial ATP-dependent phosphofructokinase. This is consistent with the proposal that the active site of pyrophosphate:fructose-6-phosphate phosphotransferase in plants is equivalent to that of the bacterial phosphofructokinase (SM Carlisle et al. [1990] J Biol Chem 265: 18366-18371).",1
"Montavon, P, Kruger, N J",2
Cloning and Characterization of an Arabidopsis thaliana Topoisomerase I Gene.,0
"cDNA and genomic clones encoding DNA topoisomerase I were isolated from Arabidopsis thaliana lambdagt11 and lambdaFix libraries by low stringency hybridization with a Saccharomyces cerevisiae TOP1 probe. The cDNA clones include a 2748-base pair open reading frame predicting an amino acid sequence that is highly homologous to sequences encoded by TOP1 from yeast and human sources. The sequence of the upstream genomic region reveals two putative TATA-like elements and a purine-rich region, but no other obvious controlling elements. Southern blot analysis shows that the gene is present as a single copy in the Arabidopsis genome. When expressed in a S. cerevisiae top1 mutant under the control of the GAL1 promoter, the gene complements the phenotype caused by loss of topoisomerase activity and directs the expression of a protein that cross-reacts with a human anti-topoisomerase I antibody.",1
"Kieber, J J, Tissier, A F, Signer, E R",2
Stomatal and nonstomatal limitations to net photosynthesis in seedlings of woody angiosperms.,0
"Comparative responses of net photosynthesis (A) to water stress in woody species from a variety of habitats were studied to assess the relationship between photosynthetic attributes and drought tolerance. Stomatal and nonstomatal limitations to A were compared in three-month-old white oak (Quercus alba L.), post oak (Quercus stellata Wangenh.), sugar maple (Acer saccharum Marsh.), and black walnut (Juglans nigra L.) seedlings during a drying cycle. Relative stomatal limitation of photosynthesis (I) was less than 50% in all species except for Q. stellata seedlings subjected to severe water stress. No significant changes in I were observed in Q. alba and J. nigra before, during, and after drought. In A. saccharum, I was generally low and decreased significantly under water stress. Under well-watered conditions, A was highest in Q. stellata, intermediate in Q. alba, and lower in A. saccharum and J. nigra. High A in well-watered Q. stellata was associated with high stomatal conductance and carboxylation efficiency, whereas low A was associated with low stomatal conductance and carboxylation efficiency in A. saccharum and low stomatal conductance, low carboxylation efficiency, and high CO(2) compensation point in J. nigra. Under severe water stress, A, carboxylation efficiency, and stomatal conductance decreased substantially in all species; however, Q. stellata had the highest carboxylation efficiency and lowest CO(2) compensation point under these conditions. After 5 days at high soil moisture after drought, stomatal and mesophyll components of A in A. saccharum and J. nigra had not recovered to predrought levels, whereas they had completely recovered in Q. stellata and Q. alba. The photosynthetic apparatus, especially mesophyll components, of drought-tolerant Quercus species showed either less inhibition under water stress, superior recovery to predrought capacity, or both. Exposure of the leaves to (14)CO(2) indicated apparent asymmetric stomatal closure for mildly water-stressed seedlings, but not for leaves of well-watered, severely stressed, or rehydrated plants. These results suggest that patchy stomatal closure under mild water stress might be important for water stress-induced inhibition of photosynthesis, but not under the more severe water stress imposed in this study.",1
"Ni, B R, Pallardy, S G",2
Immunofluorescent Localization of Plasma Membrane H-ATPase in Barley Roots and Effects of K Nutrition.,0
"The plasma membrane H(+)-ATPase (PM-H(+)-ATPase) of barley (Hordeum vulgare L. cv Klondike) roots was assayed by cross-reaction on western blots and cryosections with an antibody against the PM-H(+)-ATPase from corn roots. Under conditions of reduced K availability, which have previously been shown to increase K influx by greater than 25-fold, there were only minor changes detected in PM-H(+)-ATPase levels. Antibody labeling of cryosections showed the relative distribution of PM-H(+)-ATPase among cell types in root tips and mature roots. Epidermal cells, both protoderm and mature root epidermis, including root hairs, had high levels of antibody binding. In mature roots, the stelar tissue showing the highest antibody binding was the companion cells of the phloem, followed by pericycle, xylem parenchyma, and endodermis.",1
"Samuels, A L, Fernando, M, Glass, A D",2
Dry pea seed proteasome : purification and enzymic activities.,0
"Proteasomes were isolated from mature, dry pea seeds (Pisum sativum L.). They appear to be similar to proteasomes from other sources in that they are cylindrical (shown by negative staining), have a molecular mass greater than 600 kilodaltons (by gel permeation chromatography), and consist of several subunits between 25 and 31 kilodaltons. The seed proteasomes possess three characteristic partial activities (trypsin-like, chymotrypsin-like, and peptidyl glutamyl peptidase) as determined with fluorogenic peptide substrates. Activation and inhibition by various effectors, and particularly sensitivity to porphyrins, also match characteristics of proteasomes described for other organisms. The potential role of the proteasome in seed biology is discussed.",1
"Skoda, B, Malek, L",2
Purification and characterization of an anaerobically induced alanine aminotransferase from barley roots.,0
"Alanine aminotransferase (AlaAT, EC 2.6.1.2) is an enzyme that is induced under anaerobic conditions in cereal roots. In barley (Hordeum vulgare L.) roots, there are a number of isoforms of AlaAT. We have identified the anaerobically induced isoform and have purified it to homogeneity. The isolation procedure involved a two-step ammonium sulfate precipitation, gel filtration, ion-exchange chromatography, and chromatofocusing. The enzyme was purified approximately 350-fold to a specific activity of 2231 units/milligram protein. The apparent molecular masses of the native and sodium dodecyl sulfate-denatured AlaAT proteins are 97 and 50 kilodaltons, respectively, indicating that the native enzyme is probably a homodimer. AlaAT has a number of interesting characteristics when compared with other plant aminotransferases. AlaAT does not require the presence of pyridoxyl-5-phosphate to retain its activity, and it appears to be very specific in the reactions that it will catalyze.",1
"Good, A G, Muench, D G",2
Trigonelline and Stachydrine Released from Alfalfa Seeds Activate NodD2 Protein in Rhizobium meliloti.,0
"Spectroscopic data (nuclear magnetic resonance, mass spectrometry, ultraviolet-visible) in this study identify trigonelline and stachydrine as major components of alfalfa (Medicago sativa L.) seed rinse. Moreover, biological assays show that these natural products induce nodulation (nod) gene transcription in Rhizobium meliloti by activating the regulatory protein NodD2, but not the homologous NodD1 protein. These findings contrast with the fact that the only previously identified NodD2 activator, 4,4' -dihydroxy-2' -methoxychalcone (MCh), also activates NodD1 protein. Trigonelline and stachydrine induce nod genes only at much higher concentrations than MCh, but they are released from seeds in correspondingly greater amounts. The existence of these amphoteric, nonflavonoid nod gene inducers broadens our understanding of the biochemical processes and ecological mechanisms that a legume host uses to regulate its microbial symbiont.",1
"Phillips, D A, Joseph, C M, Maxwell, C A",2
Effects of Light on the Membrane Potential of Protoplasts from Samanea saman Pulvini : Involvement of K Channels and the H -ATPase.,0
"Rhythmic light-sensitive movements of the leaflets of Samanea saman depend upon ion fluxes across the plasma membrane of extensor and flexor cells in opposing regions of the leaf-movement organ (pulvinus). We have isolated protoplasts from the extensor and flexor regions of S. saman pulvini and have examined the effects of brief 30-second exposures to white, blue, or red light on the relative membrane potential using the fluorescent dye, 3,3'-dipropylthiadicarbocyanine iodide. White and blue light induced transient membrane hyperpolarization of both extensor and flexor protoplasts; red light had no effect. Following white or blue light-induced hyperpolarization, the addition of 200 millimolar K(+) resulted in a rapid depolarization of extensor, but not of flexor protoplasts. In contrast, addition of K(+) following red light or in darkness resulted in a rapid depolarization of flexor, but not of extensor protoplasts. In both flexor and extensor protoplasts, depolarization was completely inhibited by tetraethylammonium, implicating channel-mediated movement of K(+) ions. These results suggest that K(+) channels are closed in extensor plasma membranes and open in flexor plasma membranes in darkness and that white and blue light, but not red light, close the channels in flexor plasma membranes and open them in extensor plasma membranes. Vanadate treatment inhibited hyperpolarization in response to blue or white light, but did not affect K(+) -induced depolarization. This suggests that white or blue light-induced hyperpolarization results from activation of the H(+) -ATPase, but this hyperpolarization is not the sole factor controlling the opening of K(+) channels.",1
"Kim, H Y, Coté, G G, Crain, R C",2
Sugar Uptake and Metabolism in the Developing Endosperm of Tassel-seed Tunicate (Ts-5 Tu) Maize.,0
"Factors regulating assimilate transport into developing maize (Zea mays L.) kernels have been difficult to determine because of the structural complexity of basal kernel tissues and the damage that results from tissue dissection. The sensitivity of maize kernels to experimental manipulation is such that substantial maternal tissue is required to support kernel growth in vitro. Consequently, sugar transport experiments with isolated seed tissues or detached kernels have not unequivocally demonstrated how sugar transport occurs. In the present study, Tassel-seed Tunicate (Ts-5 Tu) maize kernels were investigated as a model system for introducing test solutions into the pedicel apoplast with minimal wounding. Transpiration in leafy glumes drew (14)C-sugar solutions up the 8- to 10-millimeter-long pedicel stalks into the basal endosperm transfer cell region. (14)C from fructose was incorporated into starch for 8 days. Sugar uptake into endosperm and embryo tissue showed specificity and inhibitor sensitivity. In particular, p-chloromercuribenzene sulfonate partially inhibited fructose uptake into the endosperm but had no effect on the metabolic conversion of that fructose that entered the endosperm. These results are consistent with active, carrier-mediated sugar transport, but a definitive determination would require more detailed tissue analysis. We propose that further refinement of the incubation solution may allow long-term kernel growth without cob tissue and thus provide a more precise determination of which maternal factors influence seed development.",1
"Thomas, P A, Felker, F C, Crawford, C G",2
Metabolism of 2'-carboxyarabinitol in leaves.,0
"Results presented here indicate that 2'-carboxyarabinitol (CA) is the in vivo precursor and product of 2'-carboxyarabinitol 1-phosphate (CA1P) metabolism in leaves. When [2-(14)C]CA was fed in the light to leaves of five species known to be highly active in CA1P metabolism (Phaseolus vulgaris, Lycopersicon esculentum, Helianthus annuus, Petunia hybrida, and Beta vulgaris), [(14)C]CA1P was formed in the dark. Reillumination of a Phaseolus leaf caused this [(14)C]CA1P to be rapidly metabolized to [(14)C]CA (t((1/2)) = 1 min). The epimer 2'-carboxyribitol could not substitute for CA in the dark synthesis of CA1P, and CA in the anionic form was a better substrate than CA in the lactone form. In leaves of Phaseolus vulgaris, the active CA pool size used in the dark synthesis of CA1P is between about 70 and 110 nanomoles per milligram of chlorophyll. The photosynthetic electron transport inhibitor diuron did not affect the dark synthesis of [(14)C]CA1P, but did greatly reduce the rate of its subsequent light degradation (t((1/2)) = approximately 10 min). Dark synthesis of [(14)C]CA1P was inhibited by dithiothreitol and NaF. From the present data, we suggest that CA1P and CA participate in a metabolic substrate cycle in vivo.",1
"Moore, B D, Seemann, J R",2
Auxin-induced growth of Avena coleoptiles involves two mechanisms with different pH optima.,0
"Although rapid auxin-induced growth of coleoptile sections can persist for at least 18 hours, acid-induced growth lasts for a much shorter period of time.  Three theories have been proposed to explain this difference in persistence.  To distinguish between these theories, the pH dependence for auxin-induced growth of oat (Avena sativa L.) coleoptiles has been determined early and late in the elongation process.  Coleoptile sections from which the outer epidermis was removed to facilitate buffer entry were incubated, with or without 10 micromolar indoleacetic acid, in 20 millimolar buffers at pH 4.5 to 7.0 to maintain a fixed wall pH.  During the first 1 to 2 hours after addition of auxin, elongation occurs by acid-induced extension (i.e. the pH optimum is <5 and the elongation varies inversely with the solution pH).  Auxin causes no additional elongation because the buffers prevent further changes in wall pH.  After 60 to 90 minutes, a second mechanism of auxin-induced growth, whose pH optimum is 5.5 to 6.0, predominates.  It is proposed that rapid growth responses to changes in auxin concentration are mediated by auxin-induced changes in wall pH, whereas the prolonged, steady-state growth rate is controlled by a second, auxin-mediated process whose pH optimum is less acidic.",1
"Cleland, R E, Cleland, R E",2
Cold Acclimation in Genetically Related (Sibling) Deciduous and Evergreen Peach (Prunus persica [L.] Batsch): I. Seasonal Changes in Cold Hardiness and Polypeptides of Bark and Xylem Tissues.,0
"Seasonal patterns of proteins and of cold hardiness were characterized in bark and xylem tissues of genetically related (sibling) deciduous and evergreen peach (Prunus persica [L.] Batsch). In contrast with deciduous trees, which entered endodormancy and abscised leaves in the fall, evergreen trees retained their leaves and exhibited shoot elongation under favorable environmental conditions. A successive increase in the cold hardiness of bark and xylem was observed during the fall in both genotypes. This was followed by a subsequent decrease from midwinter to spring. Xylem tissue in both genotypes exhibited deep supercooling and a significant correlation (r = 0.99) between the midpoint of the low-temperature exotherm and the subzero temperature at which 50% injury occurred (assessed by electrolyte leakage) was noted. The maximum hardiness level attained in deciduous trees was more than twofold that of evergreens. Seasonal pattern of proteins from bark and xylem of the sibling genotypes was characterized by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Among other qualitative and quantitative changes, accumulation of a 19-kilodalton polypeptide in the bark of both genotypes was observed during fall followed by a decrease in spring. This polypeptide accumulated to higher levels in the deciduous peach compared with the evergreen. Additionally, a 16-kilodalton protein exhibited the same pattern in deciduous trees but not in the evergreen trees. Both the 19- and a 16-kilodalton bark proteins conform to the criteria of a bark storage protein. The relationship of seasonal changes in protein to cold hardiness and dormancy in these genetically related peach genotypes is discussed.",1
"Arora, R, Wisniewski, M E, Scorza, R",2
"A Single Genetic Locus, Ckr1, Defines Arabidopsis Mutants in which Root Growth Is Resistant to Low Concentrations of Cytokinin.",0
"Arabidopsis mutants resistant to cytokinin (benzyladenine [BA]) have been isolated with the intent to find plants defective in cytokinin perception or response. At low concentrations, BA produces a ""cytokinin root syndrome"" in which primary root elongation is inhibited, but root hair elongation is stimulated. Five independent mutants that did not express this syndrome in the presence of BA were selected. All five mutants were recessive, and crosses between them indicated that they were in the same complementation group. The genetic locus represented by these mutations has been designated ckr1 and mapped to chromosome 5.",1
"Su, W, Howell, S H",2
Gibberellins and parthenocarpic ability in developing ovaries of seedless mandarins.,0
"Satsuma (Citrus unshiu [Mak] Marc.) and Clementine (Citrus reticulata [Hort.] Ex. Tanaka, cv Oroval) are two species of seedless mandarins differing in their tendency to develop parthenocarpic fruits. Satsuma is a male-sterile cultivar that shows a high degree of natural parthenocarpy and a high fruit set. Seedless Clementine varieties are self-incompatible, and in the absence of cross-pollination show a very low ability to set fruit. The gibberellins (GAs) GA53, putative 17-OH-GA(53), GA(44), GA(17), GA(19), GA(20), GA(29), GA(1), 3-epi-GA(1), GA(8), GA(24), GA(9), and GA(4) have been identified from developing fruits of both species by full-scan combined gas chromatography-mass spectrometry. Using selected ion monitoring with [(2)H(2)]- and [(13)C]-labeled internal standards, the levels of GA(53), GA(44), GA(19), GA(20), GA(1), GA(8), GA(4), and GA(9) were determined in developing ovaries at anthesis and 7 days before and after anthesis, from both species. Except for GA8, levels of the 13-hydroxy-GAs were higher in Satsuma than in Clementine, and these differences were more prominent for developing young fruits. At petal fall, Satsuma had, on a nanograms per gram dry weight basis, higher levels of GA(53) (10.4x), GA(44) (13.9x), GA(19) (3.0x), GA(20) (11.2x), and GA(1) (2.0x). By contrast, levels of GA(8) were always higher in Clementine, whereas levels of GA(4) did not differ greatly. Levels of GA(9) were very low in both species. At petal fall, fruitlets of Satsuma and Clementine contained 65 and 13 picograms of GA(1), respectively. At this time, the application of 25 micrograms of paclobutrazol to fruits increased fruit abscission in both varieties. This effect was reversed by the simultaneous applications of 1 microgram of GA(3). GA(3) alone improved the set in Clementine (13x), but had little influence on Satsuma. Thus, seedless fruits of the self-incompatible Clementine mandarin may not have adequate GA levels for fruit set. Collectively, these results suggest that endogenous GA content in developing ovaries is the limiting factor controlling the parthenocarpic development of the fruits.",1
"Talon, M, Zacarias, L, Primo-Millo, E",2
Studies of the uptake of nitrate in barley : v. Estimation of root cytoplasmic nitrate concentration using nitrate reductase activity-implications for nitrate influx.,0
"The cytoplasmic NO(3) (-) concentration ([NO(3) (-)](c)) was estimated for roots of barley (Hordeum vulgare L. cv Klondike) using a technique based on measurement of in vivo nitrate reductase activity. At zero external NO(3) (-) concentration ([NO(3) (-)](o)), [NO(3) (-)](c) was estimated to be 0.66 mm for plants previously grown in 100 mum NO(3) (-). It increased linearly with [NO(3) (-)](o) between 2 and 20 mm, up to 3.9 mm at 20 mm [NO(3) (-)](o). The values obtained are much lower than previous estimates from compartmental analysis of barley roots. These observations support the suggestion (MY Siddiqi, ADM Glass, TJ Ruth [1991] J Exp Bot 42: 1455-1463) that the nitrate reductase-based technique and compartmental analysis determine [NO(3) (-)](c) for two separate pools; an active, nitrate reductase-containing pool (possibly located in the epidermal cells) and a larger, slowly metabolized storage pool (possibly in the cortical cells), respectively. Given the values obtained for [NO(3) (-)](c) and cell membrane potentials of -200 to -300 mV (ADM Glass, JE Schaff, LV Kochian [1992] Plant Physiol 99: 456-463), it is very unlikely that passive influx of NO(3) (-) is possible via the high-concentration, low-affinity transport system for NO(3) (-). This conclusion is consistent with the suggestion by Glass et al. that this system is thermodynamically active and capable of transporting NO(3) (-) against its electrochemical potential gradient.",1
"King, B J, Siddiqi, M Y, Glass, A D",2
Distribution of Cytosolic mRNAs Between Polysomal and Ribonucleoprotein Complex Fractions in Alfalfa Embryos : Stage-Specific Translational Repression of Storage Protein Synthesis during Early Somatic Embryo Development.,0
"Cell-free translational and northern blot analyses were used to examine the distribution of storage protein messages in the cytoplasmic polysomal and mRNA-protein complex (mRNP) fractions during development of somatic and zygotic embryos of alfalfa (Medicago sativa cv Rangelander RL-34). No special array of messages was identified in the mRNP fraction; however, some messages were selectively enriched in either the polysome or mRNP fractions, and their distribution pattern varied quantitatively during development of the embryos. During the earliest stages of somatic embryo development, storage protein messages already were present, but there was no detectable accumulation of the proteins. Selective enrichment of messages for the 11S, 7S, and 2S storage proteins occurred in the mRNP fraction during the globular, heart, and torpedo stages of somatic embryogenesis, but the distribution pattern was shifted toward the polysomal fraction at the beginning of cotyledon development. Thus, there was translational repression of storage protein synthesis at the early stage of somatic embryo development that was relieved later. During the cotyledonary development stages in the somatic and zygotic embryos, storage protein synthesis and distribution of the messages were similar in that these specific messages were predominantly in the polysomal fraction.",1
"Pramanik, S K, Krochko, J E, Bewley, J D",2
Purification and Characterization of Glutamate 1-Semialdehyde Aminotransferase from Barley Expressed in Escherichia coli.,0
"The immediate precursor in the synthesis of tetrapyrroles is Delta-aminolevulinate (ALA). ALA is synthesized from glutamate in higher plants, algae, and certain bacteria. Glutamate 1-semialdehyde aminotransferase (EC 5.4.3.8) (GSA-AT), the third enzyme involved in this metabolic pathway, catalyzes the transamination of GSA to form ALA. The gene encoding this aminotransferase has previously been isolated from barley (Hordeum vulgare) and inserted into an Escherichia coli expression vector. We describe herein the purification of this recombinant barley GSA-AT expressed in Escherichia coli. Coexpression of GroEL and GroES is required for isolation of active aminotransferase from the soluble protein fraction of Escherichia coli. Purified GSA-AT exhibits absorption maxima characteristic of vitamin B(6)-containing enzymes. GSA-AT is primarily in the pyridoxamine form when isolated and can be interconverted between this and the pyridoxal form by addition of 4,5-dioxovalerate and 4,5-diaminovalerate. The conversion of GSA to ALA under steady-state conditions exhibited typical Michaelis-Menten kinetics. Values for K(m) (d,l-GSA) and k(cat) were determined to be 25 micromolar and 0.11 per second, respectively, by nonlinear regression analysis. Stimulation of ALA synthesis by increasing concentrations of d,l-GSA at various fixed concentrations of 4,5-diaminovalerate supports the hypothesis that 4,5-diaminovalerate is the intermediate in the synthesis of ALA.",1
"Berry-Lowe, S L, Grimm, B, Smith, M A, Kannangara, C G",2
Identification and Characterization of the ictA/ndhL Gene Product Essential to Inorganic Carbon Transport of Synechocystis PCC6803.,0
"The ictA gene, renamed ndhL in this paper, essential to inorganic carbon transport of Synechocystis PCC6803, was expressed in Eschericia coli as a fusion protein with glutathione S-transferase. An antibody was raised against this fusion protein. Western analysis of the thylakoid membrane of wild-type (WT) Synechocystis revealed that a protein with an apparent molecular mass of 6.7 kilodaltons cross-reacted with this antibody. No immunoreactive protein was present in the thylakoid membranes of the Synechocystis mutants, RKb and M9, which have defects in the ictA/ndhL gene, or in the cytoplasmic membranes of the WT and mutant cells. Thus, the protein reacted with the antibody is the ictA gene product (IctA) and is localized in the thylakoid membrane of WT cells. IctA was absent in the thylakoid membranes of the M55 mutant, in which the ndhB gene is inactivated, and was poorly immunostained in the membranes of the mutants (M-ndhC and M-ndhK) constructed by inactivating the ndhC and ndhK genes of WT Synechocystis, respectively. The carbon dioxide uptake activity was nearly zero in M-ndhK and was about 40% of the activity of WT cells in M-ndhC. The RKb, M-ndhC, and M-ndhK mutants were unable to grow or grew very slowly under photoheterotrophic conditions. These results indicated that NADH dehydrogenase is essential to inorganic carbon transport and photoheterotrophic growth of Synechocystis and that IctA is one of the subunits of this enzyme.",1
"Ogawa, T",2
Biosynthesis of Acyl Lipids Containing Very-Long Chain Fatty Acids in Microspore-Derived and Zygotic Embryos of Brassica napus L. cv Reston.,0
"Biosynthesis of very long chain (>C(18)) fatty acids (VLCFAs) and the pathway for their incorporation into acyl lipids was studied in microspore-derived (MD) and zygotic embryos of Brassica napus L. cv Reston. In the presence of [1-(14)C]oleoyl-coenzyme A or [1-(14)C] eicosenoyl-coenzyme A, malonyl-coenzyme A, and reducing equivalents, maximal in vitro elongation activity was expressed in protein preparations from early-mid cotyledonary stage MD embryos (17-20 days in culture), when endogenous eicosenoic (20:1) and erucic (22:1) acids were just beginning to accumulate (approximately 1.5 milligrams per gram dry weight). The biosynthesis of VLCFAs and their incorporation into glycerolipids in vitro in the MD embryo system occurred at rates comparable to those measured in developing zygotic Reston embryos at about 20 days postanthesis. When glycerol-3-phosphate was supplied as acyl acceptor in time-course experiments using homogenates prepared from 18-day MD embryos, newly synthesized [(14)C]20:1 and [(14)C]22:1 were incorporated primarily into triacylglycerols (TAGs) and, to a lesser extent, into lyso-phosphatidic/phosphatidic acids, diacylglycerols, and phosphatidylcholines as well as the acyl-coenzyme A and free fatty acid pools. [(14)C]24:1 was not detected in any acyl lipid. Stereospecific analyses of the radiolabeled TAGs indicated that [(14)C]20:1 and [(14)C]22:1 moieties were esterified predominantly at the sn-3 position, but were also found at the sn-1 position. [(14)C]20:1, but not [(14)C]22:1, was detected at the sn-2 position. Similar patterns of (14)C-labeled VLCFA distribution were obtained in experiments conducted using a 15,000g pellet fraction from 18-day MD embryos. All trends observed in the formation of TAGs containing VLCFAs in the Reston MD embryo system were also confirmed in studies of zygotic embryos of the same cultivar. The data support the biosynthesis of 20:1 and then 22:1 via successive condensations of malonyl-coenzyme A with oleoyl-coenzyme A and, for the first time in B. napus, demonstrate the incorporation of newly synthesized VLCFAs into TAGs via the Kennedy pathway.",1
"Taylor, D C, Barton, D L, Rioux, K P, Mackenzie, S L, Reed, D W, Underhill, E W, Pomeroy, M K, Weber, N",2
Aberrant processing of polyphenol oxidase in a variegated grapevine mutant.,0
"Bruce's Sport is a mutant grapevine (Vitis vinifera L.) with green and white variegated fruit derived from the Sultana variety. The white regions of tissue have decreased polyphenol oxidase (PPO) activity resulting in a reduced capacity for browning. Active PPO from Sultana grapes was purified and had an apparent molecular weight of 40,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Western blots indicated that mature Sultana grapes contained a single 40-kilodalton PPO, and young Sultana berries also had small quantities of a 60-kilodalton protein. Bruce's Sport grapes had much less of the 40-kilodalton PPO and greater amounts of the 60-kilodalton band. Protease digestion of Bruce's Sport extracts decreased the proportion of the 60-kilodalton protein and increased the 40-kilodalton band. A cDNA clone of grape PPO was used to probe a northern blot of Sultana and Bruce's Sport RNA and hybridized to a 2.2-kilobase transcript in both grapevines. The level of PPO mRNA was high in the early stages of berry development but then declined. The results suggest that in grapevine the active 40-kilodalton form of PPO is synthesized as a precursor protein of at least 60 kilodaltons, and normal processing is interrupted in Bruce's Sport resulting in the accumulation of the 60-kilodalton inactive preform of PPO.",1
"Rathjen, A H, Robinson, S P",2
The rb Mutation of Peas Causes Structural and Regulatory Changes in ADP Glucose Pyrophosphorylase from Developing Embryos.,0
"A mutation at the rb locus of pea (Pisum sativum L.) alters the shape, reduces the starch content, and increases the lipid and sucrose contents of the seed. These effects are probably all consequences of a reduction of up to 40-fold in the maximum catalytic activity of ADP glucose pyrophosphorylase in the developing embryo of the mutant relative to the wild type. We have investigated how the mutation brings about this reduction in activity. The purified enzyme from mutant embryos has a specific activity about 10-fold lower than that from wild-type embryos, and it is much more sensitive to the effectors inorganic phosphate and 3-phosphoglycerate than the wild-type enzyme. Both wild-type and mutant enzymes consist of polypeptides of around 50 kilodaltons. One of the polypeptides of the purified wild-type enzyme is missing from the mutant enzyme. We deduce that in the wild-type embryo this protein may interact with other subunits to confer a high specific activity and a low susceptibility to effectors on the enzyme.",1
"Hylton, C, Smith, A M",2
Effects and Absorption of Sethoxydim in Cell Cycle Progression of Corn (Zea mays) and Pea (Pisum sativum).,0
"The mechanisms of selective herbicidal action of sethoxydim were investigated by using cultured root tips of corn (Zea mays L. cv Goldencrossbantam) and pea (Pisum sativum L. cv Alaska). Meristematic cells in the cultured roots were arrested in G(1) and G(2) of the cell division cycle by sucrose starvation and resumed growth and cell division (proliferation) when sucrose was provided. Corn root growth after sucrose addition was inhibited by sethoxydim at concentrations of 0.01 micromolar and greater when roots were treated in the presence of sucrose but was not inhibited at 10 micromolar sethoxydim when they were treated during sucrose starvation. Greater absorption of [(14)C]sethoxydim into the meristematic region of corn roots was observed when cells were in proliferative condition but not when they were arrested by sucrose starvation, whereas no greater absorption of the herbicide into pea meristems was observed in either growth condition. In the cell cycle study, greater absorption of [(14)C]sethoxydim into the corn root meristem was observed at a certain limited time before S (DNA synthesis) stage. The physiological effects and the greater absorption of sethoxydim clearly depended on cell cycle progression of corn root meristem, whereas fatty acid synthesis, as well as its inhibition by sethoxydim, was not associated with either cell cycle progression or greater absorption of the herbicide.",1
"Hosaka, H, Takagi, M K",2
"A cold environment is a prerequisite for formation of ""plastid initials"" in winter buds of poplar.",0
"The ""plastid initial,"" the presumed precursor of eoplasts and proplastids, is present in the cells of the apical meristem of winter buds of poplar (Populus euramericana). The formation of the plastid initial in the cells of winter buds is initiated soon after the breaking of the innate or resting stage of dormancy, even in winter under nongrowing conditions in mid-January or early February. From this stage to March, the conglomeration of the plastid initial and the formation of prolamellar bodies is evident. In contrast to the poplar samples kept outdoors, the cells of the apical meristem of the indoor winter buds did not show any indication of the formation of the plastid initial and the buds of the latter sample did not flush even at the end of May. These results suggest that the sequence of reactions involved in the onset of regrowth may be closely related to the formation of the plastid initial.",1
"Sagisaka, S",2
Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin : Modulation of Leaf Gene Expression by Roots?,0
"Phosphoenolpyruvate carboxylase (PEPCase), the key enzyme of Crassulacean acid metabolism, is induced by water stress in leaves of Mesembryanthemum crystallinum. In water-stressed plants or excised leaves, exogenous cytokinin suppresses PEPCase transcript accumulation in the leaves. Cytokinin (6-benzylaminopurine) used in concentrations from 5 to 500 micromolar (a) inhibits the upregulation of PEPCase transcripts, enzyme activity, and Crassulacean acid metabolism induction in salt-stressed intact plants when sprayed once daily during the stress period, (b) inhibits the accumulation of PEPCase mRNA in leaves from well-watered plants, (c) down-regulates PEPCase transcripts within 8 hours in prestressed, intact plants after a single spraying of an individual leaf, (d) inhibits accumulation of PEPCase transcripts in excised, wilting leaves, and (e) accelerates the net decrease of PEPCase transcripts in excised leaves from prestressed plants under rehydration conditions. When roots, the main site of cytokinin biosynthesis, are excised, PEPCase induction under drought stress is intensified. We propose that roots, acting as sensors of soil water status, may regulate PEPCase gene expression in the leaves with cytokinin as a signal transducer.",1
"Schmitt, J M, Piepenbrock, M",2
Asparagine and boric Acid cause allantoate accumulation in soybean leaves by inhibiting manganese-dependent allantoate amidohydrolase.,0
"Our previous work demonstrated substantial accumulation of allantoate in leaf tissue of nodulated soybeans (Glycine max L. Merr., cv Williams) in response to nitrogen fertilization. Research was continued to determine the effect of nitrate and asparagine on ureide assimilation in soybean leaves. Stem infusion of asparagine into ureide-transporting soybeans resulted in a significant increase in allantoate concentration in leaf tissue. Accumulation of allantoate was also observed when asparagine was supplied in the presence of allopurinol, an inhibitor of xanthine dehydrogenase in the pathway of ureide biosynthesis. In vitro, asparagine was found to have an inhibitory effect on the activity of allantoate amidohydrolase, a Mn(2+)-dependent enzyme catalyzing allantoate breakdown in soybean leaves. The inhibition was partially overcome by supplemental Mn(2+) in enzyme assays. Another inhibitor of allantoate amidohydrolase, boric acid, applied foliarly on field-grown nodulated soybeans, caused up to a 10-fold increase in allantoate content of leaf tissue. Accumulation of allantoate in response to boric acid was either eliminated or greatly reduced in plants presprayed with Mn(2+). We conclude that elevated levels of allantoate in leaves of ureide-transporting soybeans fertilized with ammonium nitrate result from inhibition of allantoate degradation by asparagine and that Mn(2+) is a critical factor in this inhibition. Furthermore, our studies with asparagine and boric acid indicate that availability of Mn(2+) has a direct effect on ureide catabolism in soybean.",1
"Lukaszewski, K M, Blevins, D G, Randall, D D",2
Photographic survey of the occurrence of bundle-sheath extensions in deciduous dicots.,0
"In a survey of over 300 nonevergreen dicots in 69 families, many species were found to have translucent patterns attributed to the presence of bundle-sheath extensions (BSE) on the small and ultimate veinlets. The BSE have been shown by others to inhibit transverse air movement within leaves, and it has been suggested that they are important passageways between vascular tissue and the palisade. The only characteristic found to be associated with prominent BSE is that more trees have such features than herbaceous plants. However, many important herbs have them also, including soybeans and sunflowers.",1
"McClendon, J H",2
Phosphate Deficiency in Maize : III. Changes in Enzyme Activities during the Course of Phosphate Deprivation.,0
"The effects of low concentrations of phosphate (low-P) on soluble protein content, the activities of 12 different enzymes, and the rates of photosynthesis and respiration on the basis of leaf area were investigated in maize (Zea mays L.) leaves 16 to 24 days after planting (DAP). With low-P treatment, a drastic decrease in the rate of photosynthesis to only 6% of the maximum rate in control plants was observed by 24 DAP. Low-P treatment had almost no effect on the rate of respiration until 21 DAP, but then the rate of respiration decreased progressively to about 55% of the maximum rate in control plants. The soluble protein content in low-P plants decreased to 56% of the maximum content in control plants. The changes in the activities of enzymes in low-P plants showed several different patterns. The activities of pyruvate, orthophosphate dikinase, 3-phosphoglycerate kinase, phosphoenolpyruvate carboxylase (PEPC), ribulose 1,5-bisphosphate carboxylase, fructose 1,6-bisphosphate aldolase, catalase, phosphohexose isomerase, chloroplastic fructose 1,6-bisphosphatase, and ADP-glucose-pyrophosphorylase decreased steadily from 85 to 100% of the maximum activity found in 18- to 21-day-old control plants (V(max)) to 30 to 70% of V(max). The activity of sucrose phosphate synthase remained virtually constant at approximately 85 to 100% of V(max). The activity of UDP-glucose-pyrophosphorylase remained almost constant up to 21 DAP and then decreased to 80% of V(max) by 24 DAP. The activity of cytochrome c oxidase increased slightly up to 21 DAP but then decreased to 50% of V(max) by 24 DAP. As indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of soluble proteins, the subunit of PEPC stained less intensely in 24-d-old low-P plants. The possibility is discussed that during low-P treatment there is selective degradation of PEPC without a concomitant degradation of sucrose phosphate synthase, both of which are known to be localized in the cytoplasmic compartment of mesophyll cells.",1
"Usuda, H, Shimogawara, K",2
Localized Patch Clamping of Plasma Membrane of a Polarized Plant Cell : Laser Microsurgery of the Fucus spiralis Rhizoid Cell Wall.,0
We used an ultraviolet laser to rupture a small region of cell wall of a polarized Fucus spiralis rhizoid cell and gained localized access to the plasma membrane at the growing apex. Careful control of cell turgor enabled a small portion of plasma membrane-bound cytoplasm to be exposed. Gigaohm seals allowing single-channel recordings were obtained with a high success rate using this method with conventional patch clamp techniques.,1
"Taylor, A R, Brownlee, C",2
A Wound-Inducible Glycine-Rich Protein from Daucus carota with Homology to Single-Stranded Nucleic Acid-Binding Proteins.,0
A cDNA clone was isolated that encodes a wound-inducible glycine-rich protein. The homology of the carrot (Daucus carota) protein with the A1 protein of the heterogeneous ribonucleoprotein complex suggests that the polypeptide plays a role in the biosynthesis and processing of heterogeneous nuclear RNA and in the maturation of specific mRNAs in response to wounding.,1
"Sturm, A",2
"Methyl jasmonate, calcium, and leaf senescence in rice.",0
The possible involvement of calcium in the regulation of methyl jasmonate-promoted senescence of detached rice (Oryza sativa) leaves was investigated. Calcium effectively reduced methyl jasmonate-promoted senescence of detached rice leaves. The effect of methyl jasmonate on the senescence was also significantly reduced by calcium ionophore A23187. Methyl jasmonate-promoted senescence of detached rice leaves may be mediated through blocking the entrance of calcium ions into the cytosol.,1
"Chou, C M, Kao, C H",2
Increased Expression of a myo-Inositol Methyl Transferase in Mesembryanthemum crystallinum Is Part of a Stress Response Distinct from Crassulacean Acid Metabolism Induction.,0
"The facultative halophyte Mesembryanthemum crystallinum responds to osmotic stress by switching from C(3) photosynthesis to Crassulacean acid metabolism (CAM). This shift to CAM involves the stress-initiated up-regulation of mRNAs encoding CAM enzymes. The capability of the plants to induce a key CAM enzyme, phosphoenolpyruvate carboxylase, is influenced by plant age, and it has been suggested that adaptation to salinity in M. crystallinum may be modulated by a developmental program that controls molecular responses to stress. We have compared the effects of plant age on the expression of two salinity-induced genes: Gpdl, which encodes the photosynthesis-related enzyme glyceraldehyde 3-phosphate dehydrogenase, and Imtl, which encodes a methyl transferase involved in the biosynthesis of a putative osmoprotectant, pinitol. Imtl mRNA accumulation and the accompanying increase in pinitol in stressed Mesembryanthemum exhibit a pattern of induction distinct from that observed for CAM-related genes. We conclude that the molecular mechanisms that trigger Imtl and pinitol accumulation in response to salt stress in M. crystallinum differ in some respects from those that lead to CAM induction. There may be multiple signals or pathways that regulate inducible components of salinity tolerance in this facultative halophyte.",1
"Vernon, D M, Bohnert, H J",2
Differential Accumulation of Biotin Enzymes during Carrot Somatic Embryogenesis.,0
"The activities of four biotin enzymes, acetyl-coenzyme A (CoA) carboxylase, 3-methylcrotonyl-CoA carboxylase, pyruvate carboxylase, and propionyl-CoA carboxylase, and the accumulation of six biotin-containing polypeptides were determined during development of somatic embryos of carrot (Daucus carota). Acetyl-CoA carboxylase activity increased more than sevenfold, whereas the activities of 3-methylcrotonyl-CoA carboxylase, pyruvate carboxylase, and propionyl-CoA carboxylase were relatively unaltered. An increase also occurred in the accumulation of three of the biotin-containing polypeptides (molecular masses of 220, 62, and 34 kilodaltons). Of these, the most dramatic change was in the accumulation of the 62-kilodalton biotin-containing polypeptide, which increased by at least 50-fold as embryogenic cell clusters developed into torpedo embryos.",1
"Wurtele, E S, Nikolau, B J",2
Morphoregulatory role of thidiazuron : substitution of auxin and cytokinin requirement for the induction of somatic embryogenesis in geranium hypocotyl cultures.,0
"Somatic embryogenesis was induced in hypocotyl explants of geranium (Pelargonium x hortorum) cultured on media supplemented with various concentrations of N-phenyl-N'-1,2,3-thiadiazol-5-ylurea (thidiazuron). In less than 2 weeks, somatic embryos were observed in treatments containing levels of thidiazuron (TDZ) ranging from 0.2 to 1.0 micromolar. The use of N(6)-benzylaminopurine in combination with indole-3-acetic acid also evoked embryogenesis, but the efficiency of somatic embryo production was significantly lower than that obtained with TDZ. Hypocotyl culture for only 2 days on TDZ-supplemented medium before transfer to a basal medium was sufficient for inducing somatic embryogenesis. This distinction between the induction and expression of embryogenesis may provide an experimental system for studying the developmental biology of somatic embryogenesis. Substitution of the auxin-cytokinin requirement for the induction of somatic embryogenesis by TDZ suggests the possibility of a novel mode of its action by modulation of endogenous growth regulators.",1
"Visser, C, Qureshi, J A, Gill, R, Saxena, P K",2
Phytochrome Levels in Light-Grown Avena Change in Response to End-of-Day Irradiations.,0
"The effect of 15-minute end-of-day irradiations on photoreversible phytochrome levels in light-grown oat (Avena sativa L., cv Garry) seedlings was investigated. Oat seedlings were grown in a cycle of 8 hours of natural daylight and 16 hours of complete darkness, from sowing until harvest at day 10. The level of extractable, photoreversible phytochrome per unit fresh weight was 60% higher after end-of-day far-red irradiation than after either end-of-day red irradiation or end-of-day far-red followed by end-of-day red. Seedlings irradiated with end-of-day far-red also exhibited a small but significant increase in shoot height and fresh weight per seedling. Extracts of seedlings given each of these end-of-day treatments were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotted, and immunostained with monoclonal antibodies specific to different phytochromes. Regardless of end-of-day light treatment, phytochrome that is abundant in etiolated tissue was below the limit of detection, indicating that one or more of the phytochromes predominating in green tissue changes in abundance.",1
"Stewart, S J, Pratt, L H, Cordonnier-Pratt, I M",2
Organ- and development-specific acyl coenzyme a lysophosphatidate acyltransferases in palm and meadowfoam.,0
"Of the three acyl coenzyme A acyltransferases (AT) directly involved in the assembly of fatty acids into triacylglycerols (TAG) in maturing seed, lysophosphatidate (LPA) AT has the highest substrate stringence and dictates which fatty acids can be used. We studied LPA-AT in the microsomes from various organs of palm (Syragrus cocoides) and found that only the microsomes from maturing seed could act on 1-lauroyl-LPA and lauroyl-coenzyme A to produce dilauroyl-phosphatidate. Similarly, of the microsomes from various organs of meadowfoam (Limnanthes alba), only those from maturing seed were active with 1-erucoyl-LPA and erucoyl-coenzyme A to generate dierucoyl-phosphatidate. During maturation of the seeds of both species, the pattern of appearance of LPA-AT that produced dioleoyl phosphatidate was different from that of LPA-AT that generated dilauroyl or dierucoyl phosphatidate. The results show that in seeds, at least those that contain unusual fatty acids in the storage TAG, LPA-AT for the synthesis of TAG is different from the enzyme(s) for the synthesis of membrane lipids. They also suggest that there may be distinct pathways and/or compartments for the synthesis of TAG and membrane phospholipids.",1
"Laurent, P, Huang, A H",2
Lithium decreases cold-induced microtubule depolymerization in mesophyll cells of spinach.,0
"Freezing, dehydration, and supercooling cause microtubules in mesophyll cells of spinach (Spinacia oleracea L. cv Bloomsdale) to depolymerize (ME Bartolo, JV Carter [1991] Plant Physiol 97: 175-181). The objective of this study was to gain insight into the question of whether microtubules depolymerize as a direct response to environmental stresses or as an indirect response to cellular changes that accompany the stresses. Leaf sections of spinach were treated with Li(+) before and during exposure to low temperature. Treatment with Li(+) decreased the amount of microtubule depolymerization in cells subjected to low temperature, relative to a nontreated control, raising the possibility that the microtubules in these cells may not be inherently cold labile. Rather, microtubule depolymerization may be in response to cold-induced changes in concentration of cytoplasmic components.",1
"Bartolo, M E, Carter, J V",2
Measurement of indolebutyric Acid in plant tissues by isotope dilution gas chromatography-mass spectrometry analysis.,0
"An internal standard, [(13)C][indole-2]-indole-3-butyric acid, was synthesized from indole-2[(13)C] and was shown to be effective for the quantitative determination of indole-3-butyric acid from plant tissue. When this standard was used along with [(13)C(6)]indole-3-acetic acid, both indolic auxins could be quantified from the same tobacco (Nicotiana tabacam) leaf sample by isotope dilution analysis using selected ion monitoring gas chromatography-mass spectrometry for detection.",1
"Sutter, E G, Cohen, J D",2
Redox-modulation of chloroplast enzymes : a common principle for individual control.,0
"Assimilation of C, N, and S into organic compounds requires effective and flexible cooperation among the energy-converting, tightly coupled, thylakoid-bound processes and stromal metabolism. Fluctuations of light, temperature, and changing concentrations of the various reducible substrates pose unique regulatory problems to photoautotrophic plant cells. Covalent redox modification of enzyme proteins as mediated by the ferredoxin/thiore-doxin-system is suited to provide short-term adaptation of various enzymatic activities in the chloroplast. This mode of regulation is based on the continuous turnover of interconvertible enzyme forms, as in the systems driven by protein phosphorylation/dephosphorylation, but is particularly adapted to the unique conditions of a compartment performing oxygenic photosynthesis by depending on the simultaneous presence of reducing power and of oxygen. Individual fine control of each of the enzymes subjected to redox modification is achieved by specific metabolites acting as additional positive or negative effectors of the reductive (and/or oxidative) modification reaction. The biochemical prerequisite for such a control is the presence of regulatory (extra) sequences carrying cysteine residues which are subjected to reversible redox changes. Although no common amino acid sequence has yet been identified among the known regulatory peptides, in all cases the evolution of autotrophy should be related to the presence of extrasequences in otherwise very conserved enzyme molecules.",1
"Scheibe, R",2
Conjugation of ubiquitin to proteins from green plant tissues.,0
"Conjugation of the polypeptide ubiquitin to endogenous proteins was studied in oat (Avena sativa L.) plants, and particularly in green tissues. Conjugating activity in leaf extracts was different from that in root extracts, and in both was less than in etiolated tissue. The conjugates were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and their formation was both time- and ATP-dependent and had a pH optimum of about 8.2. The assay had a high affinity for ATP with a probable K(m) of less than 50 micromolar. The ubiquitin conjugating system was also shown to be present in isolated chloroplasts, and ubiquitin could be conjugated to endogenous proteins of lyzed chloroplasts in which the ATP concentrations were reduced by preincubation or desalting. SDS-PAGE analysis led to the suggestion that the large and small subunits of ribulose-1,5-bisphosphate carboxylase (RuBPCase) may be able to be ubiquitinated, and we have shown that ubiquitin can stimulate the in vitro breakdown of (125)I-labeled RuBPCase. These results invite the speculation that ubiquitin may be involved in the regulation of protein turnover in green plants.",1
"Veierskov, B, Ferguson, I B",2
Involvement of Cytochrome P-450 in the Biosynthesis of Dhurrin in Sorghum bicolor (L.) Moench.,0
"The biosynthesis of the tyrosine-derived cyanogenic glucoside dhurrin involves N-hydroxytyrosine, (E)- and (Z)-p-hydroxyphenylacetaldehyde oxime, p-hydroxyphenylacetonitrile, and p-hydroxymandelonitrile as intermediates and has been studied in vitro using a microsomal enzyme system obtained from etiolated sorghum (Sorghum bicolor [L.] Moench) seedlings. The biosynthesis is inhibited by carbon monoxide and the inhibition is reversed by 450 nm light demonstrating the involvement of cytochrome P-450. The combined use of two differently prepared microsomal enzyme systems and of tyrosine, p-hydroxyphenylacetaldehyde oxime, and p-hydroxyphenylacetonitrile as substrates identify two cytochrome P-450-dependent monooxygenases: the N-hydroxylase which converts tyrosine into N-hydroxytyrosine and the C-hydroxylase converting p-hydroxyphenylacetonitrile into p-hydroxymandelonitrile. The inhibitory effect of a number of putative cytochrome P-450 inhibitors confirms the involvement of cytochrome P-450. Monospecific polyclonal antibodies raised toward NADPH-cytochrome P-450-reductase isolated from sorghum inhibits the same metabolic conversions as carbon monoxide. No cytochrome P-450-dependent monooxygenase catalyzing an N-hydroxylation reaction has previously been reported in plants. The metabolism of p-hydroxyphenylacetaldehyde oxime is completely dependent on the presence of NADPH and oxygen and results in the production of p-hydroxymandelonitrile with no accumulation of the intermediate p-hydroxyphenylacetonitrile in the reaction mixture. The apparent NADPH and oxygen requirements of the oxime-metabolizing enzyme are identical to those of the succeeding C-hydroxylase converting p-hydroxyphenylacetonitrile to p-hydroxymandelonitrile. Due to the complex kinetics of the microsomal enzyme system, these requirements may not appertain to the oxime-metabolizing enzyme, which may convert p-hydroxyphenylacetaldehyde oxime to p-hydroxyacetonitrile by a simple dehydration.",1
"Halkier, B A, Møller, B L",2
The signal Peptide of a vacuolar protein is necessary and sufficient for the efficient secretion of a cytosolic protein.,0
"A cytosolic pea (Pisum sativum) seed albumin (ALB) and a chimeric protein (PHALB) consisting of the signal peptide and first three amino acids of phytohemagglutinin (PHA) and the amino acid sequence of ALB were expressed in parallel suspension cultures of tobacco (Nicotiana tabacum) cells and their intracellular fates examined. PHALB was efficiently secreted by the cells whereas ALB remained intracellular. These experiments show that the information contained in the signal peptide of a vacuolar protein is both necessary and sufficient for efficient secretion, and define secretion as a default or bulk-flow pathway. Entry into the secretory pathway was accompanied by glycosylation and the efficient conversion of the high mannose glycans into complex glycans indicating that transported glycoproteins do not need specific recognition domains for the modifying enzymes in the Golgi. Tunicamycin depressed the accumulation of the unglycosylated polypeptide in the culture medium much less than the accumulation of other glycoproteins. We interpret this as evidence that glycans on proteins that are not normally glycosylated do not have the same function of stabilizing and protecting the polypeptide as on natural glycoproteins.",1
"Hunt, D C, Chrispeels, M J",2
Colocalization of Polyphenol Oxidase and Photosystem II Proteins.,0
"Polyphenol oxidase (PPO) appears to be ubiquitous in higher plants but, as yet, no function has been ascribed to it. Herein, we report on the localization of PPO based upon biochemical fractionation of chloroplast membranes in Vicia faba (broad bean) into various complexes and immunocytochemical electron microscopic investigations. Sucrose density gradient fractionations of thylakoid membranes after detergent solubilization reveals that PPO protein (by reactivity with anti-PPO antibody) and activity (based upon ability to oxidize di-dihydroxyphenylalanine) are found only in fractions enriched in photosystem II (PSII). Furthermore, of the PSII particles isolated using three different protocols utilizing several plant species, all had PPO. Immunogold localization of PPO on thin sections reveals exclusive thylakoid labeling with a distribution pattern consistent with other PSII proteins (80% grana, 20% stroma). These data strongly indicate that PPO is at least peripherally associated with the PSII complex.",1
"Lax, A R, Vaughn, K C",2
Defense mechanisms of conifers : relationship of monoterpene cyclase activity to anatomical specialization and oleoresin monoterpene content.,0
"Cell-free extracts from Pinus ponderosa Lawson (ponderosa pine) and Pinus sylvestris L. (Scotch pine) wood exhibited high levels of monoterpene synthase (cyclase) activity, whereas bark extracts of these species contained no detectable activity, and they inhibited cyclase activity when added to extracts from wood, unless polyvinylpyrrolidone was included in the preparation. The molecular mass of the polyvinylpyrrolidone added was of little consequence; however, polyvinylpolypyrrolidone (a cross-linked insoluble form of the polymer) was ineffective in protecting enzyme activity. Based on these observations, methods were developed for the efficient extraction and assay of monoterpene cyclase activity from conifer stem (wood and bark) tissue. The level of monoterpene cyclase activity for a given conifer species was shown to correlate closely with the monoterpene content of the oleoresin and with the degree of anatomical complexity of the specialized resin-secreting structures. Cyclase activity and monoterpene content were lowest in the stems of species containing only isolated resin cells, such as western red cedar (Thuja plicata D. Don). Increasing levels of cyclase activity and oleoresin monoterpenes were observed in advancing from species with multicellular resin blisters (true firs [Abies]) to those with organized resin passages, such as western larch (Larix occidentalis Nutt.), Colorado blue spruce (Picea pungens Engelm.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The highest levels of cyclase activity and oleoresin monoterpenes were noted in Pinus species that contain the most highly developed resin duct systems. The relationship between biosynthetic capacity, as measured by cyclase activity, monoterpene content, and the degree of organization of the secretory structures for a given species, may reflect the total number of specialized resin-producing cells per unit mass of stem tissue.",1
"Lewinsohn, E, Gijzen, M, Savage, T J, Croteau, R",2
Mitochondria Isolated from NaCl-Adapted Tobacco Cell Lines (Nicotiana tabacum/gossii) Maintain Their Phosphorylative Capacity in Highly Saline Media.,0
"The in vivo functioning of mitochondria isolated from two tobacco cell lines in suspension culture (Nicotiana tabacum/gossii), wild type, and NaCl-adapted (A190), has been compared in the face of rising external salinity. The O(2) uptake of both state 3 and state 4 mitochondria was progressively inhibited with increasing external NaCl concentration in the case of both lines. Phosphorylation, however, was maintained at a higher level in the case of A190 mitochondria, as indicated both by stability of ADP:O ratio and rate of incorporation of (32)Pi. The superior phosphorylation performance of A190 mitochondria also emerged when phosphorylation was calculated per reducing equivalent, but not per unit DeltamuH(+) (electrochemical potential gradient for protons). However, the overall DeltamuH(+) was maintained at a higher level in A190 mitochondria due to the fact that the depolarization accompanying increase in external NaCl concentration was compensated for in A190 mitochondria by an increase in the transmembrane pH gradient, but not in wild type mitochondria. Increased proton permeability of the inner membrane is among the probable causes suggested for the loss of phosphorylation ability in wild type mitochondria; in contrast, A190 mitochondria maintain better membrane integrity under saline stress.",1
"Schwarz, M, Lerner, H R, Reinhold, L",2
Molecular cloning and differential expression of the maize ferredoxin gene family.,0
"In maize (Zea mays L.), four ferredoxin (Fd) isoproteins, Fd I to Fd IV, are differentially distributed in photosynthetic and nonphotosynthetic organs of young seedlings (Y Kimata, T Hase [1989] Plant Physiol 89: 1193-1197). To understand structural characteristics of the Fd isoproteins and molecular mechanism of the differential expression of their genes, we have cloned and characterized three different maize Fd cDNAs. DNA sequence analyses showed that two of the cDNAs encoded the entire precursor polypeptides of Fd I and Fd III, which were composed of 150 and 152 amino acid residues, respectively, and the other encoded a 135 amino acid precursor polypeptide of Fd not yet identified. High degrees of homologies were found in the deduced amino acid sequences of mature regions of these Fd isoproteins, but the transit peptide of Fd III differed considerably from those of other Fd isoproteins. Fd I and the unidentified Fd were encoded mainly with codons ending in C or G, but such strong codon bias was not seen in Fd III. Gene specific probes for each cDNA were used to probe Northern blots of RNA isolated from leaves, mesocotyls, and roots of maize seedlings. The gene transcripts for Fd I and the unidentified Fd were restricted to leaves and their levels increased markedly upon illumination of etiolated seedlings, whereas that for Fd III was detected in all organs and its accumulation was not light dependent. This organ specific accumulation of Fd mRNAs corresponds exactly to the distribution pattern of Fd isoproteins.",1
"Hase, T, Kimata, Y, Yonekura, K, Matsumura, T, Sakakibara, H",2
Independent Regulatory Aspects and Posttranslational Modifications of Two beta-Amylases of Rye : Use of a Mutant Inbred Line.,0
"We have examined the occurrence/disappearance, tissue location, and posttranslational modification of beta-amylase proteins in rye (Secale cereale L.) kernels at three physiological stages (development, maturity, germination) with a normal inbred line and a mutant line exhibiting a high but incomplete beta-amylase deficiency. This deficiency corresponds to a lack of accumulation of beta-amylase activity in the endosperm and does not affect the level of activity in the outer pericarp and green tissues as compared to the normal line. Two antigenically related but distinct beta-amylases (I and II) were detected in the normal line (II being the major constituent) and only one (I) in the mutant line. I and II display very similar electrophoretic polymorphism. In both lines, I appears to be ubiquitous, although it disappears from the outer pericarp during ripening. Antigen II was present only in the normal line and appears to be specific for the endosperm and perhaps for the maternal green tissues of the seed. Posttranslational modifications occurring during germination, which are mimicked by the action of papain, affect II but not I. The two groups of beta-amylases are discussed in relation to recent reports indicating the presence of two types of beta-amylase with different functions and gene loci in barley and wheat.",1
"Daussant, J, Sadowski, J, Rorat, T, Mayer, C, Laurière, C",2
Effect of Na(3)VO(4) on the P State of Nitella translucens.,0
"The capacity of sodium orthovanadate to inhibit the plasmalemma H(+) ATPase of Nitella translucens internodal cells in vivo was tested. Here we show that 1 millimolar vanadate added externally depolarizes strongly and permanently the membrane potential, both in dark and light, to the Nernst potential for potassium consistent with pump inhibition by vanadate. From the results it is clear that the H(+) ATPase is always active, under light or dark conditions, in contradiction with the widespread idea of pump inactivation by darkness. The changes in conductance for light, dark, and vanadate-induced conditions are analyzed. The effect of dark on membrane passive permeabilities and on the possibility that some plasmalemma channels could be regulated by a phosphorylation-dephosphorylation process is discussed.",1
"Cruz-Mireles, R M, Ortega-Blake, I",2
"The Purification, Properties, and Localization of an Abundant Legume Seed Lectin Cross-Reactive Material from Spartium junceum.",0
"The seeds of Spartium junceum contained a large quantity of lectin-like protein that did not appear to be either a hemagglutinin or active lectin. The cross-reactive material (CRM), like most legume seed lectins, was a tetrameric glycoprotein of about 130,000 M(r). The singlesized subunits of about 33,000 M(r) were not covalently associated. The amino acid composition was typical of legume lectins and was rich in hydroxy-amino acids and poor in sulfur-containing amino acids. The Spartium CRM contained about 3.5% covalently associated carbohydrate, most likely of the high-mannose type, since the CRM was precipitated by concanavalin A. The CRM was localized by electron-microscopic immunocytochemistry and found to be exclusively in protein-filled vacuoles (protein bodies). Because this protein was so similar immunologically, structurally, and in its physiology, to classic legume seed lectins, it is most likely a lectin homolog. Similar seed lectin CRMs appear to be both common and widespread in the Leguminosae.",1
"Hankins, C N, Herman, E M, Kindinger, J, Shannon, L M",2
Atrazine Resistance in a Velvetleaf (Abutilon theophrasti) Biotype Due to Enhanced Glutathione S-Transferase Activity.,0
"We previously reported that a velvetleaf (Abutilon theophrasti Medic) biotype found in Maryland was resistant to atrazine because of an enhanced capacity to detoxify the herbicide via glutathione conjugation (JW Gronwald, Andersen RN, Yee C [1989] Pestic Biochem Physiol 34: 149-163). The biochemical basis for the enhanced atrazine conjugation capacity in this biotype was examined. Glutathione levels and glutathione S-transferase activity were determined in extracts from the atrazine-resistant biotype and an atrazine-susceptible or ""wild-type"" velvetleaf biotype. In both biotypes, the highest concentration of glutathione (approximately 500 nanomoles per gram fresh weight) was found in leaf tissue. However, no significant differences were found in glutathione levels in roots, stems, or leaves of either biotype. In both biotypes, the highest concentration of glutathione S-transferase activity measured with 1-chloro-2,4-dinitrobenzene or atrazine as substrate was in leaf tissue. Glutathione S-transferase measured with 1-chloro-2,4-dinitrobenzene as substrate was 40 and 25% greater in leaf and stem tissue, respectively, of the susceptible biotype compared to the resistant biotype. In contrast, glutathione S-transferase activity measured with atrazine as substrate was 4.4- and 3.6-fold greater in leaf and stem tissue, respectively, of the resistant biotype. Kinetic analyses of glutathione S-transferase activity in leaf extracts from the resistant and susceptible biotypes were performed with the substrates glutathione, 1-chloro-2,4-dinitrobenzene, and atrazine. There was little or no change in apparent K(m) values for glutathione, atrazine, or 1-chloro-2,4-dinitrobenzene. However, the V(max) for glutathione and atrazine were approximately 3-fold higher in the resistant biotype than in the susceptible biotype. In contrast, the V(max) for 1-chloro-2,4-dinitrobenzene was 30% lower in the resistant biotype. Leaf glutathione S-transferase isozymes that exhibit activity with atrazine and 1-chloro-2,4-dinitrobenzene were separated by fast protein liquid (anion-exchange) chromatography. The susceptible biotype had three peaks exhibiting activity with atrazine and the resistant biotype had two. The two peaks of glutathione S-transferase activity with atrazine from the resistant biotype coeluted with two of the peaks from the susceptible biotype, but peak height was three- to fourfold greater in the resistant biotype. In both biotypes, two of the peaks that exhibit glutathione S-transferase activity with atrazine also exhibited activity with 1-chloro-2,4-dinitrobenzene, with the peak height being greater in the susceptible biotype. The results indicate that atrazine resistance in the velvetleaf biotype from Maryland is due to enhanced glutathione S-transferase activity for atrazine in leaf and stem tissue which results in an enhanced capacity to detoxify the herbicide via glutathione conjugation.",1
"Anderson, M P, Gronwald, J W",2
In Vivo pH Regulation by a Na/H Antiporter in the Halotolerant Alga Dunaliella salina.,0
"Na(+)/H(+) exchange activity in whole cells of the halotolerant alga Dunaliella salina can be elicited by intracellular acidification due to addition of weak acids at appropriate external pH. The changes in both intracellular pH and Na(+) were followed. Following a mild intracellular acidification, intracellular Na(+) content increased dramatically and then decreased. We interpret the phase of Na(+) influx as due to the activation of the plasma membrane Na(+)/H(+) antiporter and the phase of Na(+) efflux as due to an active Na(+) extrusion process. The following observations are in agreement with this interpretation: (a) the Na(+) influx phase was sensitive to Li(+), which is an inhibitor of the Na(+)/H(+) antiporter, did not require energy, and was insensitive to vanadate; (b) the Na(+) efflux phase is energy-dependent and sensitive to the plasma membrane ATPase inhibitor, vanadate. Following intracellular acidification, a drastic decrease in the intracellular ATP content is observed that is reversed when the cells regain their neutral pH value. We suggest that the intracellular acidification-induced change in the internal Na(+) concentration is due to a combination of Na(+) uptake via the Na(+)/H(+) antiporter and an active, ATPase-dependent, Na(+) extrusion. The Na(+)/H(+) antiporter seems, therefore, to play a principal role in internal pH regulation in Dunaliella.",1
"Katz, A, Bental, M, Degani, H, Avron, M",2
Antitranspirant-induced increases in leaf water potential increase tuber calcium and decrease tuber necrosis in water-stressed potato plants.,0
"Experiments were undertaken with field-grown potato (Solanum tuberosum L.) plants to test the hypothesis that altering leaf:tuber water potential gradients within a plant subjected to low soil moisture will allow greater Ca accumulation in tubers and reverse Ca deficiency-related tuber necrosis. Antitranspirant formulations containing a wax emulsion and a spreader/sticker surfactant increased leaf water potential during a drought episode, significantly reducing the potential gradient that develops between leaf and tuber during a period of stress. Increased leaf water potential in treated plants was associated with decreased leaf Ca and increased tuber Ca. Tuber necrosis was found to be reduced in treated plants, thus increasing tuber quality.",1
"Win, K, Berkowitz, G A, Henninger, M",2
"Physical, Chemical, Developmental, and Genetic Factors that Modulate the Agrobacterium-Vitis Interaction.",0
"Tumor formation in Vitis species and hybrids, incited by Agrobacterium tumefaciens, was altered by chemical, physical, developmental, and genetic variables. Knowledge of the effect of these variables was used to develop a stringent in vitro assay system to select parents for a study of genetic factors that modulate tumor formation. Tumor formation was reduced by short day preconditioning of assay plants and by inoculation of the morphological apex of isolated stem segments. Pretreatment of plants with auxin or cytokinin altered specificity in various combinations of strains and host genotypes. All Vitis species and hybrids formed tumors in response to strains designated as limited host range, but some displayed a necrotic reaction (cell death at and below site of inoculation) or a null response (same as the response to inoculation with an avirulent strain) to strains designated as wide host range (VC Knauf, CG Panagopoulos, EW Nester [1982] Phytopathology 72: 1545-1549). Screens of F(1) progeny, derived from crosses of null, necrotic, and tumor-producing phenotypes, demonstrated that the null and the necrotic phenotypes were modulated by dominant and recessive host genes. The extent of cellular necrosis in the necrotic phenotype was modified by the morphological location of the inoculation site, by the presence of buds on the host stem, and by deletion of the tryptophane monooxygenase locus gene of the Ti-plasmid.",1
"Lowe, B A, Krul, W R",2
Nitrogen and methyl jasmonate induction of soybean vegetative storage protein genes.,0
"Vegetative storage protein (VSP) and VSP mRNA levels in soybean (Glycine max) leaves correlated with the amount of NH(4)NO(3) provided to nonnodulated plants. The mRNA level declined as leaves matured, but high levels of N delayed the decline. This is consistent with the proposed role for VSP in the temporary storage of N. Wounding, petiole girdling, and treatment with methyljasmonate (MeJA) increased VSP mRNA in leaves 24 hours after treatment. The magnitude of the response depended on leaf age and N availability. N deficiency essentially eliminated the response to wounding and petiole girdling. MeJA was almost as effective in N-deficient plants as in those receiving abundant N. Inhibitors of lipoxygenase, the first enzyme in the jasmonic acid biosynthetic pathway, blocked induction by wounding and petiole girdling but not by MeJA. This supports a role for endogenous leaf jasmonic acid (or MeJA) in the regulation of VSP gene expression.",1
"Staswick, P E, Huang, J F, Rhee, Y",2
Biosynthesis and desaturation of prokaryotic galactolipids in leaves and isolated chloroplasts from spinach.,0
"Mono- and digalactosyldiacylglycerol (MGDG and DGDG) were isolated from the leaves of sixteen 16:3 plants. In all of these plant species, the sn-2 position of MGDG was more enriched in C(16) fatty acids than sn-2 of DGDG. The molar ratios of prokaryotic MGDG to prokaryotic DGDG ranged from 4 to 10. This suggests that 16:3 plants synthesize more prokaryotic MGDG than prokaryotic DGDG. In the 16:3 plant Spinacia oleracea L. (spinach), the formation of prokaryotic galactolipids was studied both in vivo and in vitro. In intact spinach leaves as well as in chloroplasts isolated from these leaves, radioactivity from [1-(14)C]acetate accumulated 10 times faster in MGDG than in DGDG. After 2 hours of incorporation, most labeled galactolipids from leaves and all labeled galactolipids from isolated chloroplasts were in the prokaryotic configuration. Both in vivo and in vitro, the desaturation of labeled palmitate and oleate to trienoic fatty acids was higher in MGDG than in DGDG. In leaves, palmitate at the sn-2 position was desaturated in MGDG but not in DGDG. In isolated chloroplasts, palmitate at sn-2 similarly was desaturated only in MGDG, but palmitate and oleate at the sn-1 position were desaturated in MGDG as well as in DGDG. Apparently, palmitate desaturase reacts with sn-1 palmitate in either galactolipid, but does not react with the sn-2 fatty acid of DGDG. These results demonstrate that isolated spinach chloroplasts can synthesize and desaturate prokaryotic MGDG and DGDG. The finally accumulating molecular species, MGDG(18:3/16:3) and DGDG(18:3/16:0), are made by the chloroplasts in proportions similar to those found in leaves.",1
"Heemskerk, J W, Schmidt, H, Hammer, U, Heinz, E",2
Cytochemical Localization of ATPase Activity in Salt-Treated and Salt-Free Grown Lycopersicon esculentum Roots.,0
"Adenosine-triphosphatase activity was localized by cytochemical methods in Lycopersicon esculentum Mill seedling roots. The identity of the enzyme was confirmed by its sensitivity to specific inhibitors. A differential distribution of ATPase activity was found depending on the region of the root. Under saline conditions, an increase of the tonoplast ATPase activity is observed, while the plasma membrane bound-ATPase activity decreases in the medial and basal regions of the root.",1
"Sanchez-Aguayo, I, Gonzalez-Utor, A L, Medina, A",2
Role of Ethylene on de Novo Shoot Regeneration from Cotyledonary Explants of Brassica campestris ssp. pekinensis (Lour) Olsson in Vitro.,0
"The promotive effect of AgNO(3) and aminoethoxyvinylglycine (AVG) on in vitro shoot regeneration from cotyledons of Brassica campestris ssp. pekinensis in relation to endogenous 1-amino-cyclopropane-1-carboxylic acid (ACC) synthase, ACC, and ethylene production was investigated. AgNO(3) enhanced ACC synthase activity and ACC accumulation, which reached a maximum after 3 to 7 days of culture. ACC accumulation was concomitant with increased emanation of ethylene which peaked after 14 days. In contrast, AVG was inhibitory to endogenous ACC synthase activity and reduced ACC and ethylene production. The promotive effect of AVG on shoot regeneration was reversed by 2-chloroethylphosphonic acid at 50 micromolar or higher concentrations, whereas explants grown on AgNO(3) medium were less affected by 2-chloroethylphosphonic acid. The distinctive effect of AgNO(3) and AVG on endogenous ACC synthase, ACC, and ethylene production and its possible mechanisms are discussed.",1
"Chi, G L, Pua, E C, Goh, C J",2
Auxin Transport in Suspension-Cultured Soybean Root Cells : II. Anion Effects on Carrier-Mediated Uptake.,0
"To test the hypothesis that the carrier-mediated component of the indoleacetic acid (IAA) influx involves an electrogenic proton/IAA anion symport, the effects on the IAA influx of salts expected to depolarize the membrane potential were examined in suspension-cultured soybean (Glycine max [L.] Merr.) root cells. Although KCl does inhibit carrier-mediated uptake, the effect is specific to the anion at low concentrations and not due to more general processes such as changes in ionic or osmotic strength. Other anions such as bromide, iodide, and fluoride inhibit the carrier more strongly. Because potassium iminodiacetate, which is also expected to depolarize the membrane potential, has no inhibitory effect on the IAA influx, there is no evidence for the involvement of the membrane potential in carrier-mediated uptake. It is therefore most likely that in soybean cells, if carrier-mediated uptake occurs via a proton symport, the H(+):IAA- stoichiometry is 1:1. At concentrations greater than 70 millimolar, sorbitol, a nonionic osmoticum, inhibits carrier-mediated IAA uptake. The effects of specific anions and osmotic potential on the uptake carrier necessitates the reevaluation of other auxin transport studies in which KCl was routinely used as an agent with which to depolarize the membrane potential.",1
"Loper, M T, Spanswick, R M",2
The synergistic effect of drought and light stresses in sorghum and pearl millet.,0
"The effects of drought stress and high irradiance and their combination were studied under laboratory conditions using young plants of a very drought-resistant variety, ICMH 451, of pearl millet (Pennisetum glaucum) and three varieties of sorghum (Sorghum bicolor)-one drought-resistant from India, one drought-tolerant from Texas, and one drought-sensitive variety from France. CO(2) assimilation rates and photosystem II fluorescence in leaves were analyzed in parallel with photosynthetic electron transport, photosystem II fluorescence, and chlorophyll-protein composition in chloroplasts isolated from these leaves. High irradiance slightly increased CO(2) assimilation rates and electron transport activities of irrigated plants but not fluorescence. Drought stress (less than -1 megapascal) decreased CO(2) assimilation rates, fluorescence, and electron transport. Under the combined effects of drought stress and high irradiance, CO(2) assimilation rates and fluorescence were severely inhibited in leaves, as were the photosynthetic electron transport activities and fluorescence in chloroplasts (but not photosystem I activity). The synergistic or distinctive effect of drought and high irradiance is discussed. The experiments with pearl millet and three varieties of sorghum showed that different responses of plants to drought and light stresses can be monitored by plant physiological and biochemical techniques. Some of these techniques may have a potential for selection of stress-resistant varieties using seedlings.",1
"Masojídek, J, Trivedi, S, Halshaw, L, Alexiou, A, Hall, D O",2
Purification and Developmental Analysis of the Major Anionic Peroxidase from the Seed Coat of Glycine max.,0
"We show that the majority of peroxidase activity in soybean (Glycine max var Williams 82) seeds is localized to the seed coat. A single isozyme is responsible for this activity and has been purified to electrophoretic homogeneity by successive chromatography on DEAE Sepharose Fast Flow, concanavalin A-Sepharose, and Sephadex G-75. The peroxidase exhibits a pl of 4.1, an apparent molecular mass of 37 kilodaltons, and has properties characteristic of a glycoprotein. The enzyme begins to accumulate approximately 21 days after anthesis and continues to do so throughout the maturation of the seed coat where it can represent at least 5% of the soluble protein in dry seed coats. Due to its localization in the seed, we propose that this isozyme may play a role in the hardening of the seed coat.",1
"Gillikin, J W, Graham, J S",2
Characterization of Cytoplasmic and Nuclear Mutations Affecting Chlorophyll and Chlorophyll-Binding Proteins during Senescence in Soybean.,0
"Soybean plants (Glycine max [L.] Merr. cv Clark) carrying nuclear and cytoplasmic ""stay-green"" mutations, which affect senescence, were examined. Normally, the levels of chlorophyll (Chl) a and b decline during seedfill and the Chl a/b ratio decreases during late pod development in cv Clark. Plants homozygous for both the d(1) and d(2) recessive alleles, at two different nuclear loci, respectively, retained most (64%) of their Chl a and b and exhibited no change in their Chl a/b ratio. Combination of G (a dominant nuclear allele in a third locus causing only the seed coat to stay green during senescence) with d(1)d(2) further inhibited the loss of Chl in the leaf. Whereas the thylakoid proteins seem to be degraded in normal Clark leaves during late pod development, they were not substantially diminished in d(1)d(2) and Gd(1)d(2) leaves. In plants carrying a cytoplasmic mutation, cytG, Chl declined in parallel with normal cv Clark; however, the cytG leaves had a much higher level of Chl b, and somewhat more Chl a, remaining at abscission, enough to color the leaves green. In cytG, most thylakoid proteins were degraded, but the Chl a/b-binding polypeptides of the light-harvesting complex in photosystem II (LHCII), and their associated Chl a and b molecules, were not. Thus, the combination of d(1) and d(2) causes broad preservation of the thylakoid proteins, whereas cytG appears to selectively preserve LHCII. The cytG mutation may be useful in elucidating the sequence of events involved in the degradation of LHCII proteins and their associated pigments during senescence.",1
"Guiamét, J J, Schwartz, E, Pichersky, E, Noodén, L D",2
Chloroplast Structure and Function Is Altered in the NCS2 Maize Mitochondrial Mutant.,0
"The nonchromosomal stripe 2 (NCS2) mutant of maize (Zea mays L.) has a DNA rearrangement in the mitochondrial genome that segregates with the abnormal growth phenotype. Yet, the NCS2 characteristic phenotype includes striped sectors of pale-green tissue on the leaves. This suggests a chloroplast abnormality. To characterize the chloroplasts present in the mutant sectors, we examined the chloroplast structure by electron microscopy, chloroplast function by radiolabeled carbon dioxide fixation and fluorescence induction kinetics, and thylakoid protein composition by polyacrylamide gel electrophoresis. The data from these analyses suggest abnormal or prematurely arrested chloroplast development. Deleterious effects of the NCS2 mutant mitochondria upon the cells of the leaf include structural and functional alterations in the both the bundle sheath and mesophyll chloroplasts.",1
"Roussell, D L, Thompson, D L, Pallardy, S G, Miles, D, Newton, K J",2
Ethylene Inhibitors Restore Nodulation to sym 5 Mutants of Pisum sativum L. cv Sparkle.,0
"The sym 5 mutants of pea, Pisum sativum L. cv Sparkle, do not differ in growth habit from their normal parent and nodulate poorly at a root temperature of 20 degrees C. If inhibitors of ethylene formation or action (Co(2+), aminoethoxyvinylglycine, or Ag(+)) are added to the substrate, nodulation of the sym 5 mutants is increased. Similar treatments of four other mutant sym lines do not restore nodulation. When Ag(+) is added to the substrate from 4 days before to 4 days after inoculation with rhizobia, nodulation of sym 5 mutants is increased. The roots of the mutant need only be exposed to Ag(+) for 4 hours to significantly increase nodule numbers. The content of free 1-aminocyclopropane-1-carboxylic acid and the production of ethylene in the lateral roots of sym 5 mutants do not differ from Sparkle.",1
"Fearn, J C, Larue, T A",2
Fructosyl Transfer between 1-Kestose and Sucrose in Wheat Leaves.,0
"The labeling pattern of the sugar moieties of 1-kestose after in vivo pulse labeling with (14)CO(2) was not the same as that after in vitro labeling with (14)C-sucrose. The two fructosyl residues of 1-kestose had similar specific radioactivities after in vitro synthesis, but after in vivo radiolabeling the specific radioactivity of the terminal fructosyl moiety was significantly less than the internal fructosyl moiety. Evidence is presented that the uneven specific radioactivity of in vivo radiolabeling results from enzymatic transfer of terminal fructosyl residue from 1-kestose to sucrose.",1
"Kanabus, J, Gibeaut, D M, Carpita, N C, Housley, T L",2
Herbicide Resistance in Datura innoxia: Kinetic Characterization of Acetolactate Synthase from Wild-Type and Sulfonylurea-Resistant Cell Variants.,0
"Acetolactate synthase (ALS, EC 4. 1.3. 18), the first enzyme in the biosynthesis of branched-chain amino acids, was isolated from wild-type and sulfonylurea-resistant Datura innoxia cell variants and characterized. Apparent K(m) values of the ALS for pyruvate from three sulfonylurea-resistant variants (CSR2, CSR6, and CSR10) were manyfold greater than that of the wild type. The inhibition of wild-type and herbicide-resistant ALS activity by chlorsulfuron (CS), a sulfonylurea herbicide, and l-leucine (l-Leu), one of the feedback inhibitors of the enzyme, was examined. ALS from two CS-resistant variants exhibited severalfold greater resistance to CS than did the wild-type enzyme. Inhibition of ALS by l-Leu fitted a partially competitive pattern most closely. It is proposed that the herbicide resistance mutation accentuated the partial inhibition characteristics of ALS by l-Leu. ALS from one of the two CS-resistant variants (CSR6) had a K(i) for l-Leu an order of magnitude greater than that of the wild-type enzyme. The alterations in kinetic properties observed in the ALS from sulfonylurea-resistant variants are discussed in relation to the possible evolutionary significance of the herbicide binding site of this enzyme, the physiological effects of such biochemical alterations, and their practical utility in genetic studies.",1
"Rathinasabapathi, B, King, J",2
Suppression of cellulase and polygalacturonase and induction of alcohol dehydrogenase isoenzymes in avocado fruit mesocarp subjected to low oxygen stress.,0
"Expression of polygalacturonase and cellulase, two hydrolytic enzymes of avocado (Persea americana, cv Hass) fruit which are synthesized de novo during ripening, and alcohol dehydrogenase, a known anaerobic protein, were studied under different O(2) regimes. Low O(2) concentrations (2.5-5.5%) diminished the accumulation of polygalacturonase and cellulase proteins and the expression of their isoenzymes. This pattern of change in cellulase protein was also reflected in the steady-state amount of its mRNA. In contrast, 7.5 and 10% O(2) did not alter the changes observed in fruits ripened in air. On the other hand, alcohol dehydrogenase was induced in 2.5, 3.5, and 5.5% O(2) but not in 7.5 or 10% O(2). The recovery from the hypoxic stress upon returning the fruits back to air for 24 hours, was also a function of O(2) tensions under which the fruits were kept. Thus, the synthesis of polygalacturonase and cellulase was directly related to O(2) levels, while the activity of the isoenzymes of alcohol dehydrogenase was inversely related to O(2) levels. The results indicate that hypoxia exerts both negative and positive effects on the expression of certain genes and that these effects are initiated at the same levels of O(2).",1
"Kanellis, A K, Solomos, T, Roubelakis-Angelakis, K A",2
In vivo regulatory phosphorylation site in c(4)-leaf phosphoenolpyruvate carboxylase from maize and sorghum.,0
"Reversible seryl-phosphorylation contributes to the light/dark regulation of C(4)-leaf phosphoenolpyruvate carboxylase (PEPC) activity in vivo. The specific regulatory residue that, upon in vitro phosphorylation by a maize-leaf protein-serine kinase(s), leads to an increase in catalytic activity and a decrease in malate-sensitivity of the target enzyme has been recently identified as Ser-15 in (32)P-phosphorylated/activated dark-form maize PEPC (J-A Jiao, R Chollet [1990] Arch Biochem Biophys 283: 300-305). In order to ascertain whether this N-terminal seryl residue is, indeed, the in vivo regulatory phosphorylation site, [(32)P]phosphopeptides were isolated and purified from in vivo(32)P-labeled maize and sorghum leaf PEPC and subjected to automated Edman degradation analysis. The results show that purified light-form maize PEPC contains 14-fold more (32)P-radioactivity than the corresponding dark-form enzyme on an equal protein basis and, more notably, only a single N-terminal serine residue (Ser-15 in maize PEPC and its structural homolog, Ser-8, in the sorghum enzyme) was found to be (32)P-phosphorylated in the light or dark. These in vivo observations, combined with the results from our previous in vitro phosphorylation studies (J-A Jiao, R Chollet [1989] Arch Biochem Biophys 269: 526-535; [1990] Arch Biochem Biophys 283: 300-305), demonstrate that an N-terminal seryl residue in C(4) PEPC is, indeed, the regulatory site that undergoes light/dark changes in phosphorylation-status and, thus, plays a major, if not cardinal role in the light-induced changes in catalytic and regulatory properties of this cytoplasmic C(4)-photosynthesis enzyme in vivo.",1
"Jiao, J A, Vidal, J, Echevarría, C, Chollet, R",2
Physiological responses of soybean plants grown in a nitrogen-free or energy limited environment.,0
"Soybean (Glycine max [L.] Merr.) seedlings grown in the absence of combined N and in an Ar:O(2) (79:21, volume/volume) atmosphere had greater seedling and nodule mass, threefold higher acetylene reducing activity per gram fresh weight nodules, no observable increase in nitrogenase Fe-protein, and a higher energy charge than did control plants. A sharp fall in acetylene reducing activity and energy charge accompanying stem-girdling was prevented by exogenous succinate, a result consistent with a path from the roots to the nodule other than via the phloem.",1
"Zhu, Y X, Schubert, K R, Kohl, D H",2
Acetolactate synthase inhibiting herbicides bind to the regulatory site.,0
"Acetolactate synthase from spontaneous mutants of tobacco (Nicotiana tabacum; KS-43 and SK-53) and cotton (Gossypium hirsutum; PS-3, PSH-91, and DO-2) selected in tissue culture for resistance to a triazolopyrimidine sulfonanilide showed varying degrees of insensitivity to feedback inhibitor(s) valine and/or leucine. A similar feature was evident in the enzyme isolated from chlorsulfuron-resistant weed biotypes, Kochia scoparia and Stellaria media. Dual inhibition analyses of triazolopyrimidine sulfonanilide, thifensulfuron, and imazethapyr versus feedback inhibitor leucine revealed that the three herbicides were competitive with the amino acid for binding to acetolactate synthase from wild-type cotton cultures. Acetolactate synthase inhibiting herbicides may bind to the regulatory site on the enzyme.",1
"Subramanian, M V, Loney-Gallant, V, Dias, J M, Mireles, L C",2
Protein Synthesis in Isolated Mitochondria of Rice (Oryza sativa L.) Seedlings.,0
"For studies of in organello mitochondrial protein synthesis in rice, Oryza sativa L., conventional surface-sterilization procedures were demonstrated to be ineffective. Because of the over-whelmingly efficient [(35)S]methionine utilization by contaminating bacteria, even ""essentially bacteria-free"" rice mitochondria were shown to be unsuitable for the study of in organello protein synthesis. We developed a procedure to obtain a bacteria-free preparation of rice mitochondria. Such mitochondria favored a membrane-dependent ATP-generating system over an external ATP-generating system as the energy supplement for in organello protein synthesis. Two distinct classes of [(35)S]methionine-labeled, cycloheximide-insensitive products were detected: an electrophoretically unresolved population and a set of some 22 to 27 discrete polypeptide species, each with a characteristic electrophoretic mobility and relative abundance.",1
"Dai, H, Lo, Y S, Wu, C Y, Tsou, C L, Hsu, G S, Chern, C G, Ruddat, M, Chiang, K S",2
Kinetic characterization of caffeoyl-coenzyme a-specific 3-o-methyltransferase from elicited parsley cell suspensions.,0
"The activity of caffeoyl-coenzyme A (CoA) 3-O-methyltransferase, an enzyme widely distributed in plants and involved in cell wall reinforcement in a disease resistance response, appears to be subject to a complex type of regulation in vivo. In cultured parsley (Petroselinum crispum) cells treated with an elicitor from Phytophthora megasperma f.sp. glycinea, the enzyme activity is rapidly induced by a transient increase in the rate of de novo transcription. Parsley caffeoyl-CoA-specific methyltransferase differs in several aspects from other plant O-methyltransferases but shows limited homology to bacterial adenine-specific DNA methyltransferases. Kinetic analysis revealed an Ordered Bi Bi mechanism for catalysis, with caffeoyl-CoA bound prior to S-adenosyl-l-methionine and feruloyl-CoA released last from the enzyme. The small inhibitory constant determined in vitro for feruloyl-CoA suggests that, in vivo, the enzyme activity is also under tight control by the steady-state product concentration in addition to the rate of transcription that becomes affected upon elicitor challenge.",1
"Pakusch, A E, Matern, U",2
"Differential Regulation of beta-1,3-Glucanase Messenger RNAs in Response to Pathogen Infection.",0
"The acidic, extracellular, glucan endo-1,3-beta-glucosidases (EC 3.2.1.39; beta-1,3-glucanases), pathogenesis-related proteins-2, -N, and -O (i.e. PR-2, PR-N, and PR-O) were purified from Nicotiana tabacum (tobacco) and their partial amino acid sequences determined. Based on these data, complementary DNA (cDNA) clones encoding the proteins were isolated. Additional cDNAs were isolated that encoded proteins approximately 90% identical with PR-2, PR-N, and PR-O. Although the proteins encoded by these cDNAs have not been identified, their deduced amino acid sequences have slightly basic or neutral calculated isoelectric points, as well as carboxy-terminal extensions. These physical characteristics are shared by the vacuolar form of beta-1,3-glucanase and other vacuolar localized analogs of PR proteins, suggesting that the unidentified proteins may be similarly localized. A preliminary evolutionary model that separates the beta-1,3-glucanase gene family from tobacco into at least five distinct subfamilies is proposed. The expression of beta-1,3-glucanase messenger RNAs (mRNAs) in response to infection by tobacco mosaic virus was examined. Messages for the acidic glucanases were induced similarly to the mRNAs for other PR proteins. However, the basic glucanase showed a different response, suggesting that different isoforms are differentially regulated by tobacco mosaic virus infection at the mRNA level.",1
"Ward, E R, Payne, G B, Moyer, M B, Williams, S C, Dincher, S S, Sharkey, K C, Beck, J J, Taylor, H T, Ahl-Goy, P, Meins, F, Ryals, J A",2
A Role for Glutamine Synthetase in the Remobilization of Leaf Nitrogen during Natural Senescence in Rice Leaves.,0
"Changes in the levels of cytosolic glutamine synthetase (GS1) and chloroplastic glutamine synthetase (GS2) polypeptides and of corresponding mRNAs were determined in leaves of hydroponically grown rice (Oryza sativa) plants during natural senescence. The plants were grown in the greenhouse for 105 days at which time the thirteenth leaf was fully expanded. This was counted as zero time for senescence of the twelfth leaf. The twelfth leaf blade on the main stem was analyzed over a time period of -7 days (98 days after germination) to +42 days (147 days after germination). Total GS activity declined to less than a quarter of its initial level during the senescence for 35 days and this decline was mainly caused by a decrease in the amount of GS2 polypeptide. Immunoblotting analyses showed that contents of other chloroplastic enzymes, such as ribulose-1,5-bisphosphate carboxylase/oxygenase and Fd-glutamate synthase, declined in parallel with GS2. In contrast, the GS1 polypeptide remained constant throughout the senescence period. Translatable mRNA for GS1 increased about fourfold during the senescence for 35 days. During senescence, there was a marked decrease in content of glutamate (to about one-sixth of the zero time value); glutamate is the major form of free amino acid in rice leaves. Glutamine, the major transported amino acid, increased about threefold compared to the early phase of the harvest in the senescing rice leaf blades. These observations suggest that GS1 in senescing leaf blades is responsible for the synthesis of glutamine, which is then transferred to the growing tissues in rice plants.",1
"Kamachi, K, Yamaya, T, Mae, T, Ojima, K",2
Elongation and termination reactions of protein synthesis on maize root tip polyribosomes studied in a homologous cell-free system.,0
"We show that the control of gene expression at the level of elongation and termination of protein synthesis can be observed in vitro. Free cytoplasmic polyribosomes were isolated from maize (Zea mays) root tips, and translated in root tip extracts that had been fractionated with ammonium sulfate to contain elongation factors, and be depleted in initiation factors. The root tip extract performs elongation and termination reactions as efficiently as wheat germ extracts. The translation products of the maize system are the same as made in vivo. The dependence of these in vitro elongation and termination reactions on pH was determined. Total protein synthesis in this system exhibits an optimum at pH approximately 7.5. However, the pH dependence of rates of synthesis of individual proteins is not at all uniform; many polyribosomes become stalled when translated at low pH. These data were compared with the elongation and termination capacity of polyribosomes isolated from oxygenated and hypoxic root tips (tissue having, respectively, high and low cytoplasmic pH values). We observed an inverse relationship between the relative abundance of many specific translatable mRNAs in polyribosomes of hypoxic root tips, and the relative rates of elongation and termination reactions on the different mRNAs at low pH in vitro. These results suggest that changes in intracellular pH in hypoxic root tips can be sensed directly by the translational machinery and thereby selectively modulate gene expression.",1
"Webster, C, Kim, C Y, Roberts, J K",2
Spatial distribution of turgor and root growth at low water potentials.,0
"Spatial distributions of turgor and longitudinal growth were compared in primary roots of maize (Zea mays L. cv FR27 x FRMo 17) growing in vermiculite at high (-0.02 megapascals) or low (-1.6 megapascals) water potential. Turgor was measured directly using a pressure probe in cells of the cortex and stele. At low water potential, turgor was greatly decreased in both tissues throughout the elongation zone. Despite this, longitudinal growth in the apical 2 millimeters was the same in the two treatments, as reported previously. These results indicate that the low water potential treatment caused large changes in cell wall yielding properties that contributed to the maintenance of root elongation. Further from the apex, longitudinal growth was inhibited at low water potential despite only slightly lower turgor than in the apical region. Therefore, the ability to adjust cell wall properties in response to low water potential may decrease with cell development.",1
"Spollen, W G, Sharp, R E",2
"In Plant Protoplasts, the Spontaneous Expression of Defense Reactions and the Responsiveness to Exogenous Elicitors Are under Auxin Control.",0
"When auxin was omitted during either the preparation or the culture of tobacco mesophyll protoplasts, as well as during both periods, synthesis of beta-glucanase was spontaneously induced. In contrast, when protoplasts were prepared and cultured in the presence of 16 micromolar 1-naphthaleneacetic acid (optimal concentration for protoplast division), the expression of beta-glucanase was maintained close to the minimal level observed in tobacco leaves. This inhibitory effect was only promoted by active auxins (1-naphthaleneacetic acid, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, and 3-indoleacetic acid) but not by inactive auxin analogs. Tobacco protoplasts responded to exogenous elicitors from the cell wall of Phytophthora megasperma glycinea (Pmg) by accumulating beta-glucanase in the presence of 16 micromolar 1-naphthaleneacetic acid. At higher auxin concentrations, the elicitor-induced beta-glucanase synthesis was inhibited. Naphthaleneacetic acid concentration (3 x 10(-5) molar) required to inhibit by 50% the expression of this defense reaction triggered by a near-optimal elicitor concentration was about 100 times higher than that sufficient to inhibit by 50% the spontaneous expression in nonelicited protoplasts. This is the first demonstration of an auxin-fungal elicitor interaction in the control of a defined defense reaction. The above observations were extended to soybean cell protoplasts. The Pmg elicitor-induced stimulation of the synthesis of pathogenesis related P17 polypeptides and of a 39-kilodalton peptide immunologically related to tobacco beta-glucanase was only observed when the spontaneous accumulation of these proteins was inhibited in auxin-treated protoplasts.",1
"Jouanneau, J P, Lapous, D, Guern, J",2
Characterization of Two Gene Transcripts Modulated by Cytokinins in Micropropagated Apple (Malus domestica [L.] Borkh) Plantlets.,0
"The micropropagation of apple (Malus domestica [L.] Borkh) cultivars is usually achieved by axillary bud stimulation and requires an exogenous cytokinin supply. Two cDNA libraries were constructed from mRNA isolated from plantlets grown in vitro on medium with or without benzyladenine. One cDNA clone (pSD3), corresponding to transcripts more abundant in plantlets grown on medium containing cytokinin than on medium lacking the hormone, was isolated. It corresponds to a mRNA of about 1,800 nucleotides which codes for a proline-rich protein with a predicted mass of 31,000 daltons. Its accumulation is restricted to roots and stems of in vivo grown apple plantlets and to stems of microcuttings cultivated on medium without cytokinin. Furthermore, it accumulates to comparable levels in leaves and stems when plantlets are grown on medium containing benzyladenine. A second cDNA clone (pSD4), corresponding to transcripts down-regulated in the presence of cytokinin in the culture medium, was also characterized. Its corresponding mRNA is about 700 nucleotides in length and encodes a protein highly homologous to the precursor of the 10-kilodalton polypeptide of the photosystem II from spinach. This mRNA accumulates specifically in leaves of apple plantlets and is more abundant in leaves of plantlets grown in the absence of cytokinin compared with plantlets grown in the presence of benzyladenine.",1
"Watillon, B, Kettmann, R, Boxus, P, Burny, A",2
Transformation of Wall Deficient Cultured Tobacco Protoplasts by Agrobacterium tumefaciens.,0
"Attachment of virulent Agrobacterium tumefaciens to plant cells is required for transformation. To further study the components of the plant cell wall that may be involved in the attachment process, tobacco (Nicotiana tabacum L.) protoplasts were cultured in the presence of 2,6 dichlorobenzonitrile (DB), an inhibitor of cellulose biosynthesis, and then assayed for their ability to be transformed by Agrobacterium. The DB treated protoplasts were deficient in wall production. Nevertheless, they were transformable at high frequency by wild type Agrobacterium strains but not by mutant strains that lack the ability to bind to normal, walled cells. Small quantities of calcofluor white positive material present on DB treated cells were correlated with their competence to be transformed. Further, the plant:bacterial association that leads to transformation is shown to become stable within 5 hours after bacterial co-cultivation with either control or DB treated cells.",1
"Binns, A N",2
Photosynthetic and photorespiratory characteristics of flaveria species.,0
"The genus Flaveria shows evidence of evolution in the mechanism of photosynthesis as its 21 species include C(3), C(3)-C(4), C(4)-like, and C(4) plants. In this study, several physiological and biochemical parameters of photosynthesis and photorespiration were measured in 18 Flaveria species representing all the photosynthetic types. The 10 species classified as C(3)-C(4) intermediates showed an inverse continuum in level of photorespiration and development of the C(4) syndrome. This ranges from F. sonorensis with relatively high apparent photorespiration and lacking C(4) photosynthesis to F. Among the intermediates, the photosynthetic CO(2) compensation points at 30 degrees C and 1150 micromoles quanta per square meter per second varied from 9 to 29 microbars. The values for the three C(4)-like species varied from 3 to 6 microbars, similar to those measured for the C(4) species. The activities of the photorespiratory enzymes glycolate oxidase, hydroxypyruvate reductase, and serine hydroxymethyltransferase decreased progressively from C(3) to C(3)-C(4) to C(4)-like and C(4) species. On the other hand, most intermediates had higher levels of phosphenolpyruvate carboxylase and NADP-malic enzyme than C(3) species, but generally lower activities compared to C(4)-like and C(4) species. The levels of these C(4) enzymes are correlated with the degree of C(4) photosynthesis, based on the initial products of photosynthesis. Another indication of development of the C(4) syndrome in C(3)-C(4)Flaveria species was their intermediate chlorophyll a/b ratios. The chlorophyll a/b ratios of the various Flaveria species are highly correlated with the degree of C(4) photosynthesis suggesting that the photochemical machinery is progressively altered during evolution in order to meet the specific energy requirements for operating the C(4) pathway. In the progression from C(3) to C(4) species in Flaveria, the CO(2) compensation point decreased more rapidly than did the decrease in O(2) inhibition of photosynthesis or the increase in the degree of C(4) photosynthesis. These results suggest that the reduction in photorespiration during evolution occurred initially by refixation of photorespired CO(2) and prior to substantive reduction in O(2) inhibition and development of the C(4) syndrome. However, further reduction in O(2) inhibition in some intermediates and C(4)-like species is considered primarily due to the development of the C(4) syndrome. Thus, the evolution of C(3)-C(4) intermediate photosynthesis likely occurred in response to environmental conditions which limit the intercellular CO(2) concentration first via refixation of photorespired CO(2), followed by development of the C(4) syndrome.",1
"Ku, M S, Wu, J, Dai, Z, Scott, R A, Chu, C, Edwards, G E",2
Carbon gain and photosynthetic response of chrysanthemum to photosynthetic photon flux density cycles.,0
"Most models of carbon gain as a function of photosynthetic irradiance assume an instantaneous response to increases and decreases in irradiance. High- and low-light-grown plants differ, however, in the time required to adjust to increases and decreases in irradiance. In this study the response to a series of increases and decreases in irradiance was observed in Chrysanthemum x morifolium Ramat. ""Fiesta"" and compared with calculated values assuming an instantaneous response. There were significant differences between high- and low-light-grown plants in their photosynthetic response to four sequential photosynthetic photon flux density (PPFD) cycles consisting of 5-minute exposures to 200 and 400 micromoles per square meter per second (mumol m(-2)s(-1)). The CO(2) assimilation rate of high-light-grown plants at the cycle peak increased throughout the PPFD sequence, but the rate of increase was similar to the increase in CO(2) assimilation rate observed under continuous high-light conditions. Low-light leaves showed more variability in their response to light cycles with no significant increase in CO(2) assimilation rate at the cycle peak during sequential cycles. Carbon gain and deviations from actual values (percentage carbon gain over- or underestimation) based on assumptions of instantaneous response were compared under continuous and cyclic light conditions. The percentage carbon gain overestimation depended on the PPFD step size and growth light level of the leaf. When leaves were exposed to a large PPFD increase, the carbon gain was overestimated by 16 to 26%. The photosynthetic response to 100 mumol m(-2) s(-1) PPFD increases and decreases was rapid, and the small overestimation of the predicted carbon gain, observed during photosynthetic induction, was almost entirely negated by the carbon gain underestimation observed after a decrease. If the PPFD cycle was 200 or 400 mumol m(-2) s(-1), high- and low-light leaves showed a carbon gain overestimation of 25% that was not negated by the underestimation observed after a light decrease. When leaves were exposed to sequential PPFD cycles (200-400 mumol m(-2) s(-1)), carbon gain did not differ from leaves exposed to a single PPFD cycle of identical irradiance integral that had the same step size (200-400-200 mumol m(-2) s(-1)) or mean irradiance (200-300-200 mumol m(-2) s(-1)).",1
"Stoop, J M, Willits, D H, Peet, M M, Nelson, P V",2
Implication of Gibberellins in Head Smut (Sporisorium reilianum) of Sorghum bicolor.,0
"The head smut fungus, Sporisorium reilianum ([Kuhn] Landon and Fullerton), was shown to reduce plant height in infected Sorghum bicolor ([L.] Moench) plants. The major reductions occurred in the internodes nearest the panicle and were more severe in naturally infected than in inoculated plants. Less affected plants developed reproductively sterile panicles, and eventually smutted panicles developed phyllodied growths which progressed into leafy shoots. Extracts of smutted, sterile, and healthy (control) panicles of field-grown plants exhibited gibberellin (GA)-like activity in the dwarf rice bioassay. When extracts were purified and assayed with deuterium-labeled GA standards by gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM), GA(1), GA(3), GA(19), GA(20), and GA(53) were detected based on coelution with the standards, identical Kovats retention index values, and matching ion masses and relative abundances for three major ions. In addition, based on published Kovats retention index values, ion masses, and relative abundance values, GA(4), GA(7), GA(8), GA(14), GA(29), and GA(44) were tentatively identified. Quantitative analysis revealed that panicles of healthy control plants contained from 60 to 100% higher total concentrations of GAs than panicles of smutted plants. These comparisons were most striking for the early 13-hydroxylation pathway precursors GA(53), GA(44), and GA(19) but not for GA(20). Extracts of S. reilianum sporidia and culture medium exhibited GA-like bioactivity, and GA(1) and GA(3) were detected based on GC-MS-SIM assay with (2)H-labeled internal standards. Quantitative analysis of these GAs showed increasing concentrations from 4 to 7 to 10 days of culture and a decline at 20 days. This is the first GC-MS-SIM detection of GAs in a non-Ascomycete fungus, and the disease symptoms and quantitative data suggested that fungal infection may interfere with biosynthesis of GAs by the host plant.",1
"Matheussen, A M, Morgan, P W, Frederiksen, R A",2
Novel Technique for Measuring Tissue Firmness within Tomato (Lycopersicon esculentum Mill.) Fruit.,0
"Developmental changes of tomato (Lycopersicon esculentum) fruit tissues during maturation were analyzed by a physically defined method (stress-relaxation analysis). The tip of a conical probe connected to a load sensor was positioned on the cut surface of a sliced tomato fruit, and the decay of the imposed stress was monitored. Stress-relaxation data thus obtained were used for the calculation of three stress-relaxation parameters. Different zones within tomato fruit harvested at six different ripening stages were analyzed. One of the stress-relaxation parameters, minimum stress-relaxation time (T(0)), decreased as the fruits matured. The decrease in T(0) was first found in the core of the carpel junction within the endopericarp at the blossom end during the breaker stage. The decrease in T(0) progressed from the blossom end, through the equatorial region and finally throughout the shoulder, as the fruit matured. In mature green fruit, T(0) values within the placenta and the proximal carpel junction were lower than those by other parts of the fruit. For all measurements the maximum stress-relaxation time was not substantially changed during maturation, nor were their changes observed in different regions of the fruit. The observed relaxation rate was therefore correlated with softening. The results indicate that fruit softening may be physically associated with the stress-relaxation parameter, T(0), and the extent of softening is a function of position within the fruit. Decreases in T(0) value appear to be correlated with the reported regional variation in the appearance of polygalacturonase.",1
"Kojima, K, Sakurai, N, Kuraishi, S, Yamamoto, R, Nevins, D J",2
Solubilization and reconstitution of ca pump from corn leaf plasma membrane.,0
"The Ca(2+) transport system of corn (Zea mays) leaf plasma membrane is composed of Ca(2+) pump and Ca(2+)/H(+) antiporter driven by H(+) gradient imposed by a H(+) pump (M Kasai, S Muto [1990] J Membr Biol 114: 133-142). It is necessary for characterization of these Ca(2+) transporters to establish the procedure for their solubilization, isolation, and reconstitution into liposomes. We attempted to solubilize and reconstitute the Ca(2+) pump in the present study. A nonionic detergent octaethyleneglycol monododecyl ether (C(12)E(8)) was the most effective detergent for a series of extraction and functional reconstitution of the Ca(2+) pump among seven detergents examined. This was judged from activities of ATP-dependent (45)Ca(2+) uptake into liposomes reconstituted with the respective detergent-extract of the plasma membrane by the detergent dilution method. C(12)E(8)-extract of the plasma membrane was subjected to high performance liquid chromatography using a DEAE anion exchange column. Ca(2+)-ATPase was separated from VO(4) (3-)-sensitive Mg(2+)-ATPase. These ATPases were separately reconstituted into liposomes, and their ATP-dependent Ca(2+) uptake was measured. The liposomes reconstituted with the Ca(2+)-ATPase, but not with the VO(4) (3-)-sensitive Mg(2+)-ATPase, showed ATP-dependent Ca(2+) uptake. Nigericin-induced pH gradient (acid inside) caused only a little Ca(2+) uptake into liposomes reconstituted with the Ca(2+)-ATPase, suggesting that the Ca(2+)/H(+) antiporter was not present in the preparation. These results indicate that the Ca(2+)-ATPase actually functions as Ca(2+) pump in the corn leaf plasma membrane.",1
"Kasai, M, Muto, S",2
Wound-induced deposition of polyphenols in transgenic plants overexpressing peroxidase.,0
"Tobacco (Nicotiana tabacum) plants transformed with a chimeric tobacco anionic peroxidase gene have previously been shown to synthesize high levels of peroxidase in all tissues throughout the plant. One of several distinguishable phenotypes of transformed plants is the rapid browning of pith tissue upon wounding. Pith tissue from plants expressing high levels of peroxidase browned within 24 hours of wounding, while tissue from control plants did not brown as late as 7 days after wounding. A correlation between peroxidase activity and wound-induced browning was observed, whereas no relationship between polyphenol oxidase activity and browning was found. The purified tobacco anionic peroxidase was subjected to kinetic analysis with substrates which resemble the precursors of lignin or polyphenolic acid. The purified enzyme was found to readily polymerize phenolic acids in the presence of H(2)O(2) via a modified ping-pong mechanism. The percentage of lignin and lignin-related polymers in cell walls was nearly twofold greater in pith tissue isolated from peroxidase-overproducer plants compared to control plants. Lignin deposition in wounded pith tissue from control plants closely followed the induction of peroxidase activity. However, wound-induced lignification occurred 24 to 48 hours sooner in plants overexpressing the anionic peroxidase. This suggests that the availability of peroxidase rather than substrate may delay polyphenol deposition in wounded tissue.",1
"Lagrimini, L M",2
Effect of Gabaculine on the Synthesis of Heme and Cytochrome f in Etiolated Wheat Seedlings.,0
"The effect of gabaculine (3-amino 2,3-dihydrobenzoic acid), an inhibitor of tetrapyrrole synthesis, on the accumulation of heme and cytochrome f in etiolated wheat (Triticum aestivum var Mardler) seedlings has been examined. Gabaculine treatment resulted in decreased amounts of heme and of holocytochrome f detected spectroscopically and by peroxidase activity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amount of the cytochrome f polypeptide detected immunochemically on Western blots was much less affected by gabaculine treatment, indicating that apocytochrome f synthesis was not tightly coupled to heme availability. Gabaculine treatment did not affect the size of the cytochrome f polypeptide, indicating that heme addition is not required for proteolytic removal of the presequence.",1
"Anderson, C M, Gray, J C",2
Comparison of Modeled and Observed Environmental Influences on the Stable Oxygen and Hydrogen Isotope Composition of Leaf Water in Phaseolus vulgaris L.,0
"In this paper we describe how a model of stable isotope fractionation processes, originally developed by H. Craig and L. I. Gordon ([1965] in E Tongiorgi, ed, Proceedings of a Conference on Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, Italy, pp 9-130) for evaporation of water from the ocean, can be applied to leaf transpiration. The original model was modified to account for turbulent conditions in the leaf boundary layer. Experiments were conducted to test the factors influencing the stable isotopic composition of leaf water under controlled environment conditions. At steady state, the observed leaf water isotopic composition was enriched above that of stem water with the extent of the enrichment dependent on the leaf-air vapor pressure difference (VPD) and the isotopic composition of atmospheric water vapor (AWV). The higher the VPD, the larger was the observed heavy isotope content of leaf water. At a constant VPD, leaf water was relatively depleted in heavy isotopes when exposed to AWV with a low heavy isotope composition, and leaf water was relatively enriched in heavy isotopes when exposed to AWV with a large heavy isotope composition. However, the observed heavy isotope composition of leaf water was always less than that predicted by the model. The extent of the discrepancy between the modeled and observed leaf water isotopic composition was a strong linear function of the leaf transpiration rate.",1
"Flanagan, L B, Comstock, J P, Ehleringer, J R",2
Xylem sap proteins.,0
"Xylem sap from apple (Malus domestica Borkh), peach (Prunus persica Batsch), and pear (Pyrus communis L.) twigs was collected by means of pressure extrusion. This sap contained a number of acidic peroxidases and other proteins. Two other sources of xylem sap used in this study were stem exudates and guttation fluid. Similar peroxidases were also found in stem exudates and guttation fluids of strawberry (Fragaria x ananassa Duch.), tomato (Lycopersicum esculentum L.), and cucumber (Cucumis sativus L.). Isoelectric focusing activity gels showed that two peroxidases (isoelectric point [pl] 9 and pl 4.6) were present in initial stem exudates collected in the first 30 minutes after excision. Subsequent samples of stem exudate collected contained only the pl 4.6 isozyme. The pl 4.6 peroxidase isozyme was also found in root tissue and guttation fluid. These observations suggest that roots produce and secrete the pl 4.6 peroxidase into xylem sap. Cucumber seedlings were treated with 100 microliters per liter ethylene for 16 hours and the exudate from decapitated hypocotyl stumps was collected over a 3 hour period. Ethylene increased the peroxidase activity of stem exudates and inhibited the amount of exudate released. These observations suggest that xylem sap peroxidase may play a role in plugging damaged vascular tissue.",1
"Biles, C L, Abeles, F B",2
Evidence for a nonstatistical carbon isotope distribution in natural glucose.,0
"The relative carbon isotope content (delta(13)C value) in each position of glucose from a C(4) plant (maize starch) and a C(3) plant (sugar beet sucrose) has been determined by stepwise chemical and biochemical degradation of the molecule and stable isotope ratio measurement of the fragments. The suitability of the degradation methods has been tested through their chemical yield and isotope balance. The results from both methods agreed perfectly, revealing a defined and reproducible (13)C distribution in glucose from both origins. Most prominent was a relative (13)C enrichment by 5 to 6 delta-units in position 4 and a depletion by about 5 delta-units in carbon 6. As possible reasons for these nonstatistical isotope distributions, isotope effects of the aldolase, the triose phosphate isomerase, and the transketolase reactions during carbohydrate biosynthesis are discussed. The practical importance of the results in regard to isotope distributions in secondary plant products as a means for food authenticity control is outlined.",1
"Rossmann, A, Butzenlechner, M, Schmidt, H L",2
Study of glucose starvation in excised maize root tips.,0
"Excised maize (Zea mays) root tips were used to follow the effects of a prolonged glucose starvation. Respiration rate began to decrease immediately after excision, reaching 30 to 40% of its initial value after 20 hours, and then declined more slowly until death of the tissues, which occurred after 200 hours of starvation. During the whole process, respiration could be uncoupled by 2,4-dinitrophenol and the energy charge remained high. These results suggest that in excised maize root tips, respiration rate is essentially limited by the rate of biosyntheses (ATP-utilizing processes) rather than mitochondrial number. During starvation the sugar content sharply decreased for the first 20 hours and reached zero at 120 hours. Following root excision, proteins and lipids were continuously degraded and were virtually the only substrates for respiration and biosyntheses after 20 hours of starvation. Over the first 90 hours of starvation, enzymic activities related to sugar metabolic pathways and the Krebs cycle decreased to 20% or less of their initial activity. Starvation was reversible only for the first 80 to 90 hours. Between 80 and 100 hours, there was a sharp fall in intracellular osmolarity and a 25% loss in the dry weight. The irreversibility may be due, as in senescence, to a change in membrane selective permeability.",1
"Brouquisse, R, James, F, Raymond, P, Pradet, A",2
Zeaxanthin Formation and Energy-Dependent Fluorescence Quenching in Pea Chloroplasts under Artificially Mediated Linear and Cyclic Electron Transport.,0
"Artificially mediated linear (methylviologen) and cyclic (phenazine methosulfate) electron transport induced zeaxanthin-dependent and independent (constitutive) nonphotochemical quenching in osmotically shocked chloroplasts of pea (Pisum sativum L. cv Oregon). Nonphotochemical quenching was quantitated as Stern-Volmer quenching (SV(N)) calculated as (F(m)/F'(m))-1 where F(m) is the fluorescence intensity with all PSII reaction centers closed in a nonenergized, dark-adapted state and F'(m) is the fluorescence intensity with all PSII reaction centers closed in an energized state. Reversal of quenching by nigericin and electron-transport inhibitors showed that both quenching types were energy-dependent SV(N). Under light-induced saturating DeltapH, constitutive-SV(N) reached steady-state in about 1 minute whereas zeaxanthin-SV(N) continued to develop for several minutes in parallel with the slow kinetics of violaxanthin deepoxidation. SV(N) above the constitutive level and relative zeaxanthin concentration showed high linear correlations at steady-state and during induction. Furthermore, F(o) quenching, also treated as Stern-Volmer quenching (SV(O)) and calculated as (F(o)/F'(o))-1, showed high correlation with zeaxanthin and consequently with SV(N) (F(o) and F'(o) are fluorescence intensities with all PSII reaction centers in nonenergized and energized states, respectively). These results support the view that zeaxanthin increases SV(N) above the constitutive level in a concentration-dependent manner and that zeaxanthin-dependent SV(N) occurs in the pigment bed. Preforming zeaxanthin increased the rate and extent of SV(N), indicating that slow events other than the amount of zeaxanthin also affect final zeaxanthin-SV(N) expression. The redox state of the primary electron acceptor of photosystem II did not appear to determine SV(N). Antimycin, when added while chloroplasts were in a dark-adapted or nonenergized state, inhibited both zeaxanthin-SV(N) and constitutive-SV(N) induced by linear and cyclic electron transport. These similarities, including possible constitutive F(o) quenching, suggest that zeaxanthin-dependent and constitutive SV(N) are mechanistically related.",1
"Gilmore, A M, Yamamoto, H Y",2
Aluminum and Temperature Alteration of Cell Membrane Permeability of Quercus rubra.,0
"This report extends research on Al-induced changes in membrane behavior of intact root cortex cells of Northern red oak (Quercus rubra). Membrane permeability was determined by the plasmometric method for individual intact cells at temperatures from 2 or 4 to 35 degrees C. Al (0.37 millimolar) significantly increased membrane permeability to urea and monoethyl urea and decreased permeability to water. Al significantly altered the activation energy required to transport water (+32%), urea (+9%), and monoethyl urea (-7%) across cell membranes. Above 9 degrees C, Al increased the lipid partiality of the cell membranes; below 7 degrees C, Al decreased it. Al narrowed by 6 degrees C the temperature range over which plasmolysis occurred without membrane damage. These changes in membrane behavior are explainable if Al reduces membrane lipid fluidity and kink frequency and increases packing density and the occurrence of straight lipid chains.",1
"Chen, J, Sucoff, E I, Stadelmann, E J",2
Response of photosynthesis and cellular antioxidants to ozone in populus leaves.,0
"Atmospheric ozone causes formation of various highly reactive intermediates (e.g. peroxyl and superoxide radicals, H(2)O(2), etc.) in plant tissues. A plant's productivity in environments with ozone may be related to its ability to scavenge the free radicals formed. The effects of ozone on photosynthesis and some free radical scavengers were measured in the fifth emergent leaf of poplars. Clonal poplars (Populus deltoides x Populus cv caudina) were fumigated with 180 parts per billion ozone for 3 hours. Photosynthesis was measured before, during, and after fumigation. During the first 90 minutes of ozone exposure, photosynthetic rates were unaffected but glutathione levels and superoxide dismutase activity increased. After 90 minutes of ozone exposure, photosynthetic rates began to decline while glutathione and superoxide dismutase continued to increase. Total glutathione (reduced plus oxidized) increased in fumigated leaves throughout the exposure period. The ratio of GSH/GSSG also decreased from 12.8 to 1.2 in ozone exposed trees. Superoxide dismutase levels increased twofold in fumigated plants. After 4 hours of ozone exposure, the photosynthetic rate was approximately half that of controls while glutathione levels and superoxide dismutase activity remained above that of the controls. The elevated antioxidant levels were maintained 21 hours after ozone exposure while photosynthetic rates recovered to about 75% of that of controls. Electron transport and NADPH levels remained unaffected by the treatment. Hence, elevated antioxidant metabolism may protect the photosynthetic apparatus during exposure to ozone.",1
"Gupta, A S, Alscher, R G, McCune, D",2
Peptidyl proline hydroxylation and the growth of a soybean cell culture.,0
"Peptidyl proline hydroxylase inhibitors block the growth of cultured soybean (Glycine max) cells and bring about the disappearance of the major salt-extractable hydroxyproline-rich protein, the 33 kilodalton repetitive proline-rich protein (RPRP2). Three polypeptides of 28, 20, and 14 kilodalton that cross-react with an antibody to RPRP2 accumulate in the culture during steady-state growth. In the presence of the proline hydroxylase inhibitors, all of these repetitive proline-rich proteins disappear. These results indicate that the hydroxyproline-rich proteins play a role in cell growth, and that hydroxylation may regulate the steady-state level of at least one of these proteins by influencing its turnover.",1
"Schmidt, A, Datta, K, Marcus, A",2
Glass transitions in soybean seed : relevance to anhydrous biology.,0
"We have investigated the mechanism by which anhydrobiotic organisms can survive severe dehydration. The method used was measurement of the rotational diffusion coefficient of a hydrophilic spin probe, inserted in the cytoplasm of soybean (Glycine max L.) axes, as a function of temperature and sample water content. Results indicate the existence of a hydration-dependent glass-like transition at physiological temperatures. No glass transitions have been observed in desiccation-intolerant samples, suggesting that the ability to withstand dehydration is associated with glass formation.",1
"Bruni, F, Leopold, A C",2
Multiple forms of plant cytochromes p-450.,0
"Accumulating evidence indicates that there is a multiplicity of cytochrome P-450 enzymes in plants. These monooxygenases are implicated in the metabolism of sterols, terpenes, gibberellins, isoflavonoids, and xenobiotics. Evidence that cytochromes P-450 are involved in the detoxification of herbicides (chlorotoluron, primsulfuron, and diclofop) includes photoreversible CO inhibition of the reactions, and a requirement for O(2) and NADPH. Several cytochromes P-450, M(r) 45,000 to 65,000, have been isolated, including hydroxylases of cinnamic acid, 3,9-dihydroxypterocarpan, and digitoxin. In some cases the purified cytochrome P-450 has been successfully reconstituted with NADPH:cytochrome P-450 reductase (M(r) 72,000-84,000 protein). This reductase appears to be a nonspecific electron donor to different forms of cytochrome P-450. Immunological techniques and specific inhibitors (triazoles, imidazole derivatives) are being used to characterize plant cytochromes P-450 and the NADPH:cytochrome P-450 reductase. Specific cytochromes P-450 are induced by wounding or pathogens, others are expressed in specific cell types. Plant cytochromes P-450 are found in various subcellular locations, including endoplasmic reticulum, plasma membranes, glyoxysomes, and perhaps mitochondria. A cytochrome P-450 demethylase from avocado has recently been sequenced and found to have a hydrophobic N terminus similar to the membrane anchor of cytochromes P-450 from other organisms. The existence of cytochromes P-450 in different subcellular locations suggests that there are many genes for cytochromes P-450 in plants which have yet to be identified and classified.",1
"Donaldson, R P, Luster, D G",2
Purification and characterization of galactinol synthase from mature zucchini squash leaves.,0
"Galactinol synthase catalyzes the first committed step in the biosynthesis of raffinose sugars. Previous attempts to purify the enzyme have proven difficult and have resulted in low quantities of unpurified enzyme. Galactinol synthase was purified 752-fold from mature zucchini (Cucurbita pepo L. cv Burpee Hybrid) leaves using sequential liquid chromatography on DE 52, Octyl-Sepharose CL-4B, and Sephacryl S-200. This isolation scheme resulted in an 18.6% recovery of the initial activity. The purified enzyme had a specific activity of 23.3 micromoles per minute per milligram protein, a pH optimum of 7.5, and the activity was enhanced by dithiothreitol and MnCl(2). The enzyme was only half as active with MgCl(2) as with MnCl(2). Na(+), K(+), and Ca(2+) cations had little effect on the enzyme activity, while Co(2+), Zn(2+), Cu(2+), and Fe(3+) cations were strongly inhibitory at 10 millimolar concentrations. Purified galactinol synthase bound specifically to the substrates myo-inositol and UDP-galactose (K(m) = 6.5 and 1.8 millimolar, respectively), while exhibiting little affinity for an alternative glycosyl donor (UDP-glucose) or inositol epimers (epi- and scyllo-). Ten millimolar concentrations of UMP, UDP, UTP, AMP, ADP, ATP, NAD(+), NADH, NADP(+), UDP-xylose, and UDP-mannose, or 20 millimolar sucrose, talose, galactose, glucose, xylose, and melibiose exhibited various degrees of inhibitory effects. Twenty millimolar stachyose, raffinose, fructose, and mannose, and 10 millimolar UDP-glucuronic acid and UDP-galacturonic acid had little or no effect on the enzyme activity. The purified galactinal synthase is a monomer of M(r) 42,000 with an isoelectric point of 4.1.",1
"Smith, P T, Kuo, T M, Crawford, C G",2
Immunocytochemical localization of nitrite reductase in green algae.,0
"The distribution of nitrite reductase (EC 1.7.7.1) in the green algae Chlamydomonas reinhardtii, Monoraphidium braunii, Chlorella fusca, and Scenedesmus obliquus was studied by immunoelectron microscopy. The labeling of ultrathin cryosections was performed with anti-nitrite reductase antibodies followed by gold-labeled goat anti-rabbit antibodies. In C. reinhardtii sections, gold label was mainly associated with the pyrenoid, tonoplast, and plasmalemma. Significant labeling was also detected in the thylakoid region. In all other organisms, label density was lower but distributed in the same locations, except that the plasmalemma of S. obliquus was not significantly labeled. From estimates of the relative volume of different cell regions, we found that approximately 80% of the total enzyme is located in the chloroplastic region (thylakoids plus pyrenoid) of C. reinhardtii, M. braunii, and C. fusca, and 97% in the case of S. obliquus.",1
"López-Ruiz, A, Verbelen, J P, Bocanegra, J A, Diez, J",2
Partial purification and characterization of a Ca(2+)-dependent protein kinase from pea nuclei.,0
"Almost all the Ca(2+)-dependent protein kinase activity in nuclei purified from etiolated pea (Pisum sativum, L.) plumules is present in a single enzyme that can be extracted from chromatin by 0.3 molar NaCl.  This protein kinase can be further purified 80,000-fold by salt fractionation and high performance liquid chromatography, after which it has a high specific activity of about 100 picomoles per minute per microgram in the presence of Ca2+ and reaches half-maximal activation at about 3 x 10(-7) molar free Ca2+, without calmodulin.  It is a monomer with a molecular weight near 90,000.  It can efficiently use histone III-S, ribosomal S6 protein, and casein as artificial substrates, but it phosphorylates phosvitin only weakly.  Its Ca(2+)-dependent kinase activity is half-maximally inhibited by 0.1 millimolar chlorpromazine, by 35 nanomolar K-252a and by 7 nanomolar staurosporine.  It is insensitive to sphingosine, an inhibitor of protein kinase C, and to basic polypeptides that block other Ca(2+)-dependent protein kinases.  It is not stimulated by exogenous phospholipids or fatty acids.  In intact isolated pea nuclei it preferentially phosphorylates several chromatin-associated proteins, with the most phosphorylated protein band being near the same molecular weight (43,000) as a nuclear protein substrate whose phosphorylation has been reported to be stimulated by phytochrome in a calcium-dependent fashion.",1
"Li, H, Dauwalder, M, Roux, S J, Roux, S J",2
Adaptation of Nodulated Soybean (Glycine max L. Merr.) to Growth in Rhizospheres Containing Nonambient pO(2).,0
"Nodulated soybean (Glycine max L. Merr. cv White Eye inoculated with Bradyrhizobium japonicum strain CB 1809) plants were cultured in the absence of combined N from 8 to 28 days with their root systems maintained continuously in 1, 2.5, 5, 10, 20, 40, 60, or 80% O(2) (volume/volume) in N(2). Plant dry matter yield was unaffected by partial pressure of oxygen (pO(2)) and N(2) fixation showed a broad plateau of maximum activity from 2.5 to 40 or 60% O(2). Slight inhibition of nitrogenase activity occurred at 1% O(2) and as much as 50% inhibition occurred at 80% O(2). Low pO(2) (less than 10%) decreased nodule mass on plants, but this was compensated for by those nodules having higher specific nitrogenase activities. Synthesis and export of ureides in xylem was maintained at a high level (70-95% of total soluble N in exudate) over the range of pO(2) used. Measurements of nitrogenase (EC 1.7.99.2) activity by acetylene reduction indicated that adaptation of nodules to low pO(2) was largely due to changes in ventilation characteristics and involved increased permeability to gases in those grown in subambient pO(2) and decreased permeability in those from plants cultured with their roots in pO(2) greater than ambient. A range of structural alterations in nodules resulting from low pO(2) were identified. These included increased frequency of lenticels, decreased nodule size, increased volume of cortex relative to the infected central tissue of the nodule, as well as changes in the size and frequency of extracellular voids in all tissues. In nodules grown in air, the inner cortex differentiated a layer of four or five cells which formed a band, 40 to 50 micrometers thick, lacking extracellular voids. This was reduced in nodules grown in low pO(2) comprising one or two cell layers and being 10 to 20 micrometers thick in those from 1% O(2). Long-term adaptation to different external pO(2) involved changes which modify diffusive resistance and are additional to adjustments in the variable diffusion barrier.",1
"Dakora, F D, Atkins, C A",2
Biochemical characterization of a spearmint mutant that resembles peppermint in monoterpene content.,0
"A radiation-induced mutant of Scotch spearmint (Mentha x gracilis) was shown to produce an essential oil containing principally C3-oxygenated p-menthane monoterpenes that are typical of peppermint, instead of the C6-oxygenated monoterpene family characteristic of spearmint. In vitro measurement of all of the enzymes responsible for the production of both the C3-oxygenated and C6-oxygenated families of monoterpenes from the common precursor (-)-limonene indicated that a virtually identical complement of enzymes was present in wild type and mutant, with the exception of the microsomal, cytochrome P-450-dependent (-)-limonene hydroxylase; the C6-hydroxylase producing (-)-trans-carveol in the wild type had been replaced by a C3-hydroxylase producing (-)-trans-isopiperitenol in the mutant. Additionally, the mutant, but not the wild type, could carry out the cytochrome P-450-dependent epoxidation of the alpha,beta-unsaturated bond of the ketones formed via C3-hydroxylation. Although present in the wild type, the enzymes of the C3-pathway that convert trans-isopiperitenol to menthol isomers are synthetically inactive because of the absence of the key C3-oxygenated intermediate generated by hydroxylation of limonene. These results, which clarify the origins of the C3- and C6-oxygenation patterns, also allow correction of a number of earlier biogenetic proposals for the formation of monoterpenes in Mentha.",1
"Croteau, R, Karp, F, Wagschal, K C, Satterwhite, D M, Hyatt, D C, Skotland, C B",2
Carbohydrate Metabolism in Taproots of Medicago sativa L. during Winter Adaptation and Spring Regrowth.,0
"Our objective was to identify amylases that may participate in starch degradation in alfalfa (Medicago sativa L.) taproots during winter hardening and subsequent spring regrowth. Taproots from field-grown plants were sampled at intervals throughout fall, winter, and early spring. In experiment 1, taproots were separated into bark and wood tissues. Concentrations of soluble sugars, starch, and buffer-soluble proteins and activities of endo- and exoamylase were determined. Starch concentrations declined in late fall, whereas concentrations of sucrose increased. Total amylolytic activity (primarily exoamylase) was not consistently associated with starch degradation but followed trends in soluble protein concentration of taproots. This was especially evident in spring when both declined as starch degradation increased and shoot growth resumed. Activity of endoamylase increased during periods of starch degradation, especially in bark tissues. In experiment 2, a low starch line had higher specific activity of taproot amylases. This line depleted its taproot starch by late winter, after which taproot sugar concentrations declined. As in experiment 1, total amylolytic activity declined in spring in both lines, whereas that of endoamylase increased in both lines even though little starch remained in taproots of the low starch line. Several isoforms of both amylases were distinguished using native polyacrylamide electrophoresis, with isoforms being similar in bark and wood tissues. The slowest migrating isoform of endoamylase was most prominent at each sampling. Activity of all endoamylase isoforms increased during winter adaptation and in spring when shoot growth resumed. Endoamylase activity consistently increased at times of starch utilization in alfalfa taproots (hardening, spring regrowth, after defoliation), indicating that it may serve an important role in starch degradation.",1
"Volenec, J J, Boyce, P J, Hendershot, K L",2
Wounding Nicotiana tabacum Leaves Causes a Decline in Endogenous Indole-3-Acetic Acid.,0
"We have previously observed that auxin can act as a repressor of the wound-inducible activation of a chimeric potato proteinase inhibitor II-CAT chimeric gene (pin2-CAT) in transgenic tobacco (Nicotiana tobacum) callus and in whole plants. Therefore, this study was designed to examine endogenous levels of indole-3-acetic acid (IAA) in plant tissues both before and after wounding. Endogenous IAA was measured in whole plant tissues by gas chromatography-mass spectrometry using an isotope dilution technique. (13)C-Labeled IAA was used as an internal standard. The endogenous levels of IAA declined two- to threefold within 6 hours after a wound. The kinetics of auxin decline are consistent with the kinetics of activation of the pin2-CAT construction in the foliage of transgenic tobacco.",1
"Thornburg, R W, Li, X",2
Gum arabic glycoprotein is a twisted hairy rope : a new model based on o-galactosylhydroxyproline as the polysaccharide attachment site.,0
"Separation of the wound exudate from Acacia senegal (L.) Willd., ""gum arabic,"" on a preparative Superose-6 column gave two major fractions: a high molecular weight gum arabic glycoprotein (GAGP) containing about 90% carbohydrate and a lower molecular weight heterogenous gum arabic polysaccharide fraction. Hydrogen fluoride-deglycosylation of GAGP gave a large ( approximately 400 residue) hydroxyproline-rich polypeptide backbone (dGAGP). Alkaline hydrolysis of GAGP showed that most of the carbohydrate was attached to the polypeptide backbone as small ( approximately 30 residue) hydroxyproline (Hyp)-polysaccharide substituents. After partial acid hydrolysis of the Hyp-polysaccharide fraction we identified O-galactosylhydroxyproline as the glycopeptide linkage, identical with that of hydroxyproline-rich arabinogalactan-proteins (AGPs). However, unlike the acidic alanine-rich AGPs, GAGP is basic and notably deficient in alanine. Thus, while the GAGP polypeptide backbone more closely resembles that of the Hyp-rich cell wall protein extensin, the GAGP polysaccharide sidechains resemble AGPs. Possibly all three proteins comprise a phylogenetically related extensin superfamily of extended rod-like macromolecules. The ""wattle-blossom"" model for AGP and gum arabic predicts a few large polysaccharide substituents along the polypeptide backbone of a spheroidal macromolecule. On the contrary, our data imply a rodlike molecule with numerous small polysaccharide substituents (attached to 24% of the Hyp residues), regularly arranged along a highly periodic polypeptide backbone based, hypothetically, on a 10 to 12 residue repetitive peptide motif. Thus, a simple statistical model of the gum arabic glycoprotein predicts a repeating polysaccharide-peptide subunit of about 7 kilodaltons. The small polysaccharide substituents will maximize intramolecular hydrogen bonding if aligned along the long axis of the molecule, forming in effect a twisted hairy rope. Electron micrographs of rotary shadowed GAGP molecules support that prediction and may also explain how such apparently large molecules can exit the cell by endwise reptation through the small pores of the primary cell wall.",1
"Qi, W, Fong, C, Lamport, D T",2
Maturation proteins associated with desiccation tolerance in soybean.,0
"A set of proteins that accumulates late in embryogenesis (Lea proteins) has been hypothesized to have a role in protecting the mature seed against desiccation damage. A possible correlation between their presence and the desiccation tolerant state in soybean seeds (Glycine max L. Chippewa) was tested. Proteins that showed the same temporal pattern of expression as that reported for Lea proteins were identified in the axes of soybean. They were distinct from the known storage proteins and were resistant to heat coagulation. The level of these ""maturation"" proteins was closely correlated with desiccation tolerance both in the naturally developing and in the germinating seed: increasing at 44 days after flowering, when desiccation tolerance was achieved, and decreasing after 18 hours of imbibition, when desiccation tolerance was lost. During imbibition, 100 micromolar abscisic acid or Polyethylene glycol-6000 (-0.6 megapascals) delayed disappearance of the maturation proteins, loss of desiccation tolerance, and germination. During maturation, desiccation tolerance was prematurely induced when excised seeds were dried slowly but not when seeds were held for an equivalent time at high relative humidity. In contrast, maturation proteins were induced under both conditions. We conclude that maturation proteins may contribute to desiccation tolerance of soybean seeds, though they may not be sufficient to induce tolerance by themselves.",1
"Blackman, S A, Wettlaufer, S H, Obendorf, R L, Leopold, A C",2
"Biochemical Bases for the Loss of Basipetal IAA Transport with Advancing Physiological Age in Etiolated Helianthus Hypocotyls: Changes in IAA Movement, Net IAA Uptake, and Phytotropin Binding.",0
"Basipetal transport of [(14)C]IAA in hypocotyl segments isolated from various regions of etiolated Helianthus annuus L. cv NK 265 seedlings declines with increasing physiological age. This decline was the result of a reduction in both transport capacity and apparent velocity. Net IAA uptake was greater and the abilities of auxin transport inhibitors to stimulate net IAA uptake were reduced in older tissues. Net IAA accumulation by microsomal vesicles exhibited a similar behavior with respect to age. Specific binding of [(3)H]N-1-naphthylphthalamic acid (NPA) to microsomes prepared from young and older hypocotyl regions was saturable and consistent with a single class of binding sites. The apparent affinity constants for NPA binding in microsomes prepared from young versus older tissues were 6.4 and 10.8 nanomolar, respectively, and the binding site densities for young versus old tissues were 7.44 and 3.29 picomoles/milligram protein, respectively. Specific binding of [(3)H]NPA in microsomes prepared from both tissues displayed similar sensitivities toward unlabeled flurenol and exhibited only slight differences in sensitivity toward 2,3,5-triiodobenzoic acid. These results demonstrate that the progressive loss of basipetal IAA transport capacity in etiolated Helianthus hypocotyls with advancing age is associated with substantial alterations in the phytotropin-sensitive, IAA efflux system and they suggest that these changes are, at least partially, responsible for the observed reduction of polar IAA transport with advancing tissue age.",1
"Suttle, J C",2
Sucrose Synthase Expression during Cold Acclimation in Wheat.,0
"When wheat (Triticum aestivum) seedlings are exposed to a cold temperature (2-4 degrees C) above 0 degrees C, sucrose accumulates and sucrose synthase activity increases. The effect of a cold period on the level of sucrose synthase (SS) was investigated. Using antibodies against wheat germ SS, Western blots studies showed that the amount of the SS peptide increased during 14 days in the cold, when plants were moved from 23 degrees C to 4 degrees C. The level of SS diminished when plants were moved back to 23 degrees C. Northern blots of poly(A)(+) RNA, confirmed a five- to sixfold induction of SS in wheat leaves during cold acclimation. These results indicate that SS is involved in the plant response to a chilling stress.",1
"Crespi, M D, Zabaleta, E J, Pontis, H G, Salerno, G L",2
Nitrate-dependent o(2) evolution in intact leaves.,0
"Evolution of O(2) by illuminated intact detached leaves from barley (Hordeum vulgare L. cv Athos) and pea (Pisum sativum L. cv Lincoln) in a CO(2)-saturating atmosphere was enhanced when KNO(3) (1-2.5 millimolar) had been previously supplied through the transpiration stream. The extra O(2) evolution observed after feeding KNO(3) increased with the light intensity, being maximal at near saturating photon flux densities and resulting in no changes in the initial slope of the O(2)versus light-intensity curve. No stimulation of O(2) evolution was otherwise observed after feeding KCl or NH(4)Cl. The data indicate that nitrate assimilation uses photosynthetically generated reductant and stimulates the rate of non-cyclic electron flow by acting as a second electron-accepting assimilatory process in addition to CO(2) fixation.",1
"de la Torre, A, Delgado, B, Lara, C",2
Acyl carrier protein is conjugated to glutathione in spinach seed.,0
"Acyl carrier protein (ACP) contains an essential sulfhydryl group in its phosphopantetheine prosthetic group. We have investigated the state of this sulfhydryl in developing and mature spinach seed (Spinacia oleracea). Seed extracts were separated on sodium dodecyl sulfate or native polyacrylamide gels, blotted to nitrocellulose, and probed with antibodies raised against spinach ACP-I. In extracts of mature seeds prepared with reducing agents, ACP-II migrated as a single major band, whereas extracts prepared without reducing agents gave two major bands. The additional band was identified as a conjugate of ACP-II to glutathione (ACP-S-S-G) on the basis of its sensitivity to reducing agents and its comigration with standards in both native and sodium dodecyl sulfate gel electrophoresis. In developing spinach seeds ACP-II exists primarily in its free sulfhydryl form or as acyl derivatives, with essentially no ACP-S-S-G present. During later stages of seed development, as seed water content declines, ACP-S-S-G accumulates to approximately 50% of the total ACP. Seed imbibition results in a rapid decline in ACP-S-S-G levels. The ACP-S-S-G:ACP-SH ratio of seeds during storage was found to be a function of seed water content and this could be manipulated by controlling the relative humidity under which the seeds were stored. We speculate that conjugation of ACP to glutathione protects the ACP from sulfhydryl oxidative damage in dry seeds.",1
"Butt, A D, Ohlrogge, J B",2
Characterization of heat injury in grapes using h nuclear magnetic resonance methods : changes in transverse relaxation times.,0
"Transverse relaxation times (T(2)) of tissue water ((1)H) in leaves and suspension cultured cells of grape hybrids (Vitis spp. cv ;Venus' and ;Veeblanc') were measured by nuclear magnetic resonance at various temperatures. The tissue water was characterized by two T(2) time constants. A sharp decrease in T(2) for the major fraction of tissue water was observed in association with heat injury, as measured by electrolyte leakage and triphenyltetrazolium chloride reduction in both leaves and suspension cultured cells. The changes in T(2) as a result of heat injury were irreversible, as indicated by a temperature dependent hysteresis of T(2). Studies using a paramagnetic probe (Mn(+2)) indicated that the plasma membrane was irreversibly damaged at the killing temperature, resulting in a loss of cell compartmentalization. Tissue water in heat-killed samples was characterized by only a single T(2).",1
"Abass, M, Rajashekar, C B",2
Compartmentation studies on spinach leaf peroxisomes : evidence for channeling of photorespiratory metabolites in peroxisomes devoid of intact boundary membrane.,0
"In concurrence with earlier results, the following enzymes showed latency in intact spinach (Spinacia oleracea L.) leaf peroxisomes: malate dehydrogenase (89%), hydroxypyruvate reductase (85%), serine glyoxylate aminotransferase (75%), glutamate glyoxylate aminotransferase (41%), and catalase (70%). In contrast, glycolate oxidase was not latent. Aging of peroxisomes for several hours resulted in a reduction in latency accompanied by a partial solubilization of the above mentioned enzymes. The extent of enzyme solubilization was different, being highest with glutamate glyoxylate aminotransferase and lowest with malate dehydrogenase. Osmotic shock resulted in only a partial reduction of enzyme latency. Electron microscopy revealed that the osmotically shocked peroxisomes remained compact, with smaller particle size and pleomorphic morphology but without a continuous boundary membrane. Neither in intact nor in osmotically shocked peroxisomes was a lag phase observed in the formation of glycerate upon the addition of glycolate, serine, malate, and NAD. Apparently, the intermediates, glyoxylate, hydroxypyruvate, and NADH, were confined within the peroxisomal matrix in such a way that they did not readily leak out into the surrounding medium. We conclude that the observed compartmentation of peroxisomal metabolism is not due to the peroxisomal boundary membrane as a permeability barrier, but is a function of the structural arrangement of enzymes in the peroxisomal matrix allowing metabolite channeling.",1
"Heupel, R, Markgraf, T, Robinson, D G, Heldt, H W",2
Genes with Homology to Fungal and S-Gene RNases Are Expressed in Arabidopsis thaliana.,0
"The only RNase genes that have been cloned from higher plants are those expressed in species that are known to exhibit self-incompatibility, such as the S genes of Nicotiana alata. In this report, we investigated whether the expression of this particular type of RNase gene is restricted to self-incompatible species, or if similar genes are expressed in other plants. Using a polymerase chain reaction approach we have identified a set of three putative RNase genes in the self-compatible plant Arabidopsis thaliana (L.) Heynh. ecotype Columbia. These A. thaliana genes, designated RNS1, RNS2, and RNS3, do not cross-hybridize to each other, and their products are homologous to both the S-gene RNases of N. alata and a set of related fungal enzymes. The A. thaliana RNS1, RNS2, and RNS3 genes encode transcripts of 1.1, 1.3, and 1.1 kilobases, respectively, and of the three genes, RNS2 is the most highly expressed in whole plants. The identification of the RNS genes in a self-compatible species suggests that this class of RNases is of general significance in RNA catabolism in higher plants.",1
"Taylor, C B, Green, P J",2
Systemic Endopolyploidy in Arabidopsis thaliana.,0
"Microfluorometric analysis of the nuclear DNA contents of the somatic tissues of Arabidopsis thaliana has revealed extensive endoreduplication, resulting in tissues that comprise mixtures of polyploid cells. Endoreduplication was found in all tissues except those of the inflorescences and was developmentally regulated according to the age of the tissues and their position within the plant.",1
"Galbraith, D W, Harkins, K R, Knapp, S",2
Downward Regulation of Photosynthesis and Growth at High CO(2) Levels : No Evidence for Either Phenomenon in Three-Year Study of Sour Orange Trees.,0
"Numerous photosynthesis and growth measurements of sour orange (Citrus aurantium L.) trees maintained in ambient air and air enriched with an extra 300 microliters per liter of CO(2) have revealed the CO(2)-enriched trees to have consistently sequestered approximately 2.8 times more carbon than the control trees over a period of three full years. Under field conditions in the natural environment, plants may not experience the downward regulation of photosynthetic capacity typically observed in long-term CO(2) enrichment experiments with plants growing in pots.",1
"Idso, S B, Kimball, B A",2
"Alpha-amylase inhibitor, not phytohemagglutinin, explains resistance of common bean seeds to cowpea weevil.",0
"There are claims that phytohemagglutinin (PHA), the lectin of common bean, Phaseolus vulgaris, is toxic when fed to the cowpea weevil, Callosobruchus maculatus, and that PHA serves as the chemical defense against this seed-feeding bruchid beetle (DH Janzen, HB Juster, IE Liener [1976] Science 192: 795-796; AMR Gatehouse, FM Dewey, J Dove, KA Fenton, A Pusztai [1984] J Sci Food Agric 35: 373-380). However, our studies indicate that neither PHA nor its isolectins have detrimental effects when fed to the cowpea weevil. To explain these contradictory results we characterized the commercial lectin source used by A. M. R. Gatehouse, F. M. Dewey, J. Dove, K. A. Fenton, A. Pusztai (1984, J Sci Food Agric 35: 373-380). We demonstrate here that the toxic effects of PHA to cowpea weevil are due to an alpha-amylase inhibitor contaminant in the commercial preparation.",1
"Huesing, J E, Shade, R E, Chrispeels, M J, Murdock, L L",2
Partial Purification and Reconstitution of the alpha-Ketoglutarate Carrier from Corn (Zea mays L.) Mitochondria.,0
"The alpha-ketoglutarate carrier from corn shoot mitochondria (Zea mays L., B 73) was solubilized in Triton X-114 and partially purified by chromatography on hydroxyapatite and celite in the presence of cardiolipin. On SDS-gel electrophoresis, the hydroxyapatite/celite eluate showed various protein bands between 12 and 70 kilodaltons. When reconstituted into liposomes, the alpha-ketoglutarate transport protein catalyzed a phthalonate-sensitive alpha-ketoglutarate/alpha-ketoglutarate exchange. The protein was purified 60-fold with a recovery of 88% with respect to the mitochondrial extract. The protein yield was 0.6%. The properties of the reconstituted carrier, i.e. requirement for a counter-anion, substrate specificity, and inhibitor sensitivity, were similar to those of the alpha-ketoglutarate transport system as characterized in plant and animal mitochondria.",1
"Genchi, G, De Santis, A, Ponzone, C, Palmieri, F",2
Polyamines and the Cell Cycle of Catharanthus roseus Cells in Culture.,0
"Investigation was made on the effect of partial depletion of polyamines (PAs), induced by treatment with inhibitors of the biosynthesis of PAs, on the distribution of cells at each phase of the cell cycle in Catharanthus roseus (L.) G. Don. cells in suspension cultures, using flow cytometry. More cells treated with inhibitors of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) were accumulated in the G(1) phase than those in the control, while the treatment with an inhibitor of spermidine (SPD) synthase showed no effect on the distribution of cells. The endogenous levels of the PAs, putrescine (PUT), SPD, and spermine (SPM), were determined during the cell cycle in synchronous cultures of C. roseus. Two peaks of endogenous level of PAs, in particular, of PUT and SPD, were observed during the cell cycle. Levels of PAs increased markedly prior to synthesis of DNA in the S phase and prior to cytokinesis. Activities of ADC and ODC were also assayed during the cell cycle. Activities of ADC was much higher than that of ODC throughout the cell cycle, but both activities of ODC and ADC changed in concert with changes in levels of PAs. Therefore, it is suggested that these enzymes may regulate PA levels during the cell cycle. These results indicate that inhibitors of PUT biosynthesis caused the suppression of cell proliferation by prevention of the progression of the cell cycle, probably from the G(1) to the S phase, and PUT may play more important roles in the progression of the cell cycle than other PAs.",1
"Maki, H, Ando, S, Kodama, H, Komamine, A",2
Sucrose Phosphate Is Not Transported into Vacuoles or Tonoplast Vesicles from Red Beet (Beta vulgaris) Hypocotyl.,0
"Tonoplast vesicles and vacuoles isolated from red beet (Beta vulgaris L.) hypocotyl accumulated externally supplied [(14)C]sucrose but not [(14)C]sucrose phosphate despite the occurrence of sucrose phosphate phosphohydrolytic activity in the vacuole. The activities of sucrose synthase and sucrose phosphate synthase in whole cell extracts were 960 and 30 nanomoles per milligram protein per minute, respectively; whereas, no sucrose synthesizing activity was measured in tonoplast preparations. The results obtained in this investigation are incompatible with the involvement of sucrose phosphate synthase in the process of sucrose synthesis and accumulation in the storage cells of red beet.",1
"Echeverria, E, Salvucci, M E",2
Photophosphorylation in Attached Leaves of Helianthus annuus at Low Water Potentials.,0
"The in situ response of photophosphorylation and coupling factor activity to low leaf water potential (psi(L)) was investigated using kinetic spectroscopy to measure the flash-induced electrochromic absorption change in attached sunflower (Helianthus annuus L. cv IS894) leaves. The electrochromic change is caused by the formation of an electric potential across the thylakoid membrane associated with proton uptake. Since depolarization of the thylakoid membrane following flash excitation is normally dominated by proton efflux through the coupling factor during ATP formation, this measurement can provide direct information about the catalytic activity of the coupling factor. Under low psi(L) conditions in which a clear nonstomatal limitation of net photosynthesis could be demonstrated, we found a strong inhibition of coupling factor activity in dark-adapted leaves which was probably caused by an increase in the energetic threshold for the activation of the enzyme at low psi(L). While this result supported earlier in vitro findings, we further discovered that the light-dependent reduction of coupling factor reversed any observable effect of low psi(L) on the energetics of activation or on photophosphorylation competence. Furthermore, coupling factor was reduced, even in severely droughted sunflower, almost immediately upon illumination. Based on these measurements, we conclude that the nonstomatal limitation of photosynthesis observed by us and others in droughted plants cannot be explained by impaired coupling factor activity.",1
"Ortiz-Lopez, A, Ort, D R, Boyer, J S",2
"Regulation by ca of a cytosolic fructose-1,6-bisphosphatase from spinach leaves.",0
"Cytosolic fructose-1,6-bisphosphatase from spinach (Spinacia oleracea L.) leaves was purified over 1700-fold. The final preparation was specific for fructose-1,6-bisphosphate in the presence of either Mg(2+) or Mn(2+), and was free of interfering enzyme activities. Ca(2+) was an effector of fructose-1,6-bisphosphatase activity, and showed different kinetics, depending on whether Mg(2+) or Mn(2+) was used as cofactor. In the presence of 5 millimolar Mg(2+), Ca(2+) appeared as activator or as inhibitor of the enzyme at low or high levels of substrate, respectively. In both cases, a rise in affinity for fructose-1,6-bisphosphate was observed. A model is proposed to describe the complex interaction of fructose-1,6-bisphosphatase with its substrate and Ca(2+). However, with Mn(2+) (60 micromolar) as cofactor, Ca(2+) exhibited the Michaelis-Menten kinetics of a noncompetitive inhibitor. When assayed at constant substrate concentration, Ca(2+) behaves as a competitive or noncompetitive inhibitor, depending on the use of Mg(2+) or Mn(2+) as cofactor, respectively, with a positive cooperativity in both cases. Fructose-2,6-bisphosphate showed a classic competitive allosteric inhibition in the presence of Mg(2+) as cofactor, but this effect was low with Mn(2+). From these results we suggest that Ca(2+) plays a role in the in vivo regulation of cytosolic fructose-1,6-bisphosphatase.",1
"Prado, F E, Lázaro, J J, Gorgé, J L",2
Plasmalemma redox activity and h extrusion in roots of fe-deficient cucumber plants.,0
"Cucumber plants (Cucumis sativus L.) with incipient Fe deficiency showed increased root capacity to reduce chelated Fe(3+) compared to Fe-sufficient plants. When Fe-ethylenediaminete-traacetate was added to the root medium of the Fe-deficient plants, the reductase activity was associated with acidification of the medium and an increase in the net apparent K(+) efflux. In the presence of the H(+)-ATPase inhibitor N,N'-dicyclohexylcarbodiimide the net apparent H(+) efflux was completely suppressed, though some reductase activity was preserved, and the net apparent K(+) efflux was significantly increased. The inhibition of the reductase activity by N,N'-dicyclohexylcarbodiimide was similar whether the pH of the medium was buffered or not. Anoxia and the protonophore carbonyl cyanide m-chlorophenyl hydrazone also caused a similar inhibition of the reductase activity. It is proposed that this redox system transports electrons only and that its activity is inhibited by plasmamembrane depolarization and anoxia. The H(+) and K(+) efflux associated with the reductase activity may be a result of the plasmamembrane depolarization it causes.",1
"Alcántara, E, de la Guardia, M D, Romera, F J",2
Expression of a Conserved Family of Cytoplasmic Low Molecular Weight Heat Shock Proteins during Heat Stress and Recovery.,0
"Plants synthesize several families of low molecular weight (LMW) heat shock proteins (HSPs) in response to elevated temperatures. We have characterized two cDNAs, HSP18.1 and HSP17.9, that encode members of the class I family of LMW HSPs from pea (Pisum sativum). In addition, we investigated the expression of these HSPs at the mRNA and protein levels during heat stress and recovery. HSP18.1 and HSP17.9 are 82.1% identical at the amino acid level and are 80.8 to 92.9% identical to class I LMW HSPs of other angiosperms. Heat stress experiments were performed using intact seedlings subjected to a gradual temperature increase and held at a maximum temperature of 30 to 42 degrees Celsius for 4 hours. HSP18.1 and HSP17.9 mRNA levels peaked at the beginning of the maximum temperature period and declined rapidly after the stress period. Antiserum against a HSP18.1 fusion protein recognized both HSP18.1 and HSP17.9 but not members of other families of LMW HSPs. The accumulation of HSP18.1-immunodetected protein was proportional to the severity of the heat stress, and the protein had a half-life of 37.7 +/- 8 hours. The long half-life of these proteins supports the hypothesis that they are involved in establishing thermotolerance.",1
"Derocher, A E, Helm, K W, Lauzon, L M, Vierling, E",2
Heat Shock Causes Selective Destabilization of Secretory Protein mRNAs in Barley Aleurone Cells.,0
"The aleurone layer of GA(3)-stimulated barley (Hordeum vulgare L., cv Himalaya) grains is normally devoted to the synthesis and secretion of hydrolytic enzymes. Heat shock, however, suppresses the synthesis of the main hydrolytic enzyme, alpha-amylase, by destabilizing its otherwise highly stable mRNA (FC Belanger, MR Brodl, T-hD Ho [1986] Proc Natl Acad Sci USA 83: 1354-1358). In this paper we document that heat shock causes the suppression of the synthesis of some normal cellular proteins, while the synthesis of other normal cellular proteins is unaffected by heat shock. There are two major isozymic forms of alpha-amylase encoded by distinct mRNAs. The mRNA levels for both isozymic forms and the mRNA levels of two other secretory proteins, a protease and an endochitinase, were markedly reduced during heat shock. However, the levels of actin and beta-tubulin mRNAs, both nonsecretory proteins, were not diminished during heat shock. In addition, the levels of three other mRNA species detected by a set of unidentified cDNA clones (the sequence of one shows that it lacks a signal sequence) remained unchanged during heat shock. These data indicate that there are two classes of normal cellular protein mRNAs with regard to the effect of heat shock upon their persistence in the cell, and suggest that the distinction between them is whether or not they encode secretory proteins.",1
"Brodl, M R, Ho, T H",2
"Solubilization, partial purification, and reconstitution of the glycolate/glycerate transporter from chloroplast inner envelope membranes.",0
"The glycolate/glycerate transporter of spinach (Spinacia oleracea L.) chloroplast inner envelope membranes was solubilized by treatment of the membranes with sodium cholate. Mixtures of the cholate extracts and soy asolectin were subjected to gel filtration to remove the detergent. The reconstituted vesicles were frozen, thawed, and sonicated in a buffer that contained 10 millimolar d-glycerate and, usually, [(3)H]sucrose as an internal space indicator. The dilution of the vesicles into a medium that contained 0.4 millimolar [(14)C]d-glycerate resulted in a rapid accumulation of labeled glycerate, followed by a much slower loss of [(14)C]d-glycerate from the vesicles. This behavior is characteristic of counterflow. The accumulation of [(14)C]d-glycerate was strongly inhibited by HgCl(2), which blocks glycolate/glycerate transport in intact chloroplasts. In the absence of proton ionophores, the extent of [(14)C]glycolate accumulation under similar conditions was much greater than that of [(14)C]d-glycerate. External glycolate inhibited d-glycerate counterflow and external d-glycerate inhibited glycolate counterflow. The external pH dependence of the efflux of [(14)C]d-glycerate accumulated in vesicles by counterflow and its inhibition by external l-mandelate are characteristics displayed by glycolate transport in intact chloroplasts. Partial purification of the transporter was achieved by glycerol gradient centrifugation. The solubilized glycolate and glycerate counterflow activities, assayed by reconstitution into vesicles, were found to sediment similarly.",1
"Howitz, K T, McCarty, R E",2
Evidence of zein-bound indoleacetic Acid using gas chromatography-selected ion monitoring-mass spectrometry analysis and immunogold labeling.,0
Commercial zein was base-hydrolyzed and purified extracts were subjected to gas chromatography-selected ion monitoring-mass spectrometry analysis. Indoleacetic acid (IAA) was shown to be released from this storage protein of corn (Zea mays). Isotope dilution using [(13)C(6)]IAA as an internal standard revealed a conservative ratio of 1 mole IAA to 175 moles zein. Immunoelectron micrographs of isolated protein bodies also showed IAA or an IAA-like molecule associated with zein and deposited within these organelles.,1
"Leverone, L A, Kossenjans, W, Jayasimihulu, K, Caruso, J L",2
"Cryptochrome, phytochrome, and anthocyanin production.",0
"Anthocyanin production in cabbage (Brassica oleracea L.) and tomato (Lycopersicon esculentum Mill.) seedlings exposed to prolonged irradiations was studied under conditions that allowed discrimination, within certain limits, between the contribution of cryptochrome and phytochrome in the photoregulation of the response. The results of the study provide confirming evidence for the involvement of cryptochrome and direct evidence for a significant contribution of cryptochrome to the fluence rate dependence of the response to blue. The results provide some preliminary, direct indication for an interaction between cryptochrome and phytochrome in the photoregulation of anthocyanin production in seedlings exposed to the prolonged irradiations required for a high level of expression of the response. The type and degree of interaction between the two photoreceptors vary significantly, depending on the species and experimental conditions.",1
"Mancinelli, A L, Rossi, F, Moroni, A",2
"Water Relations and Hydraulic Architecture of a Tropical Tree (Schefflera morototoni) : Data, Models, and a Comparison with Two Temperate Species (Acer saccharum and Thuja occidentalis).",0
"The water relations and hydraulic architecture of a tropical tree (Schefflera morototoni) and of two temperate species (Acer saccharum and Thuja occidentalis) are reported. Among the water relations parameters measured were leaf and stem water storage capacity, leaf water potential, transpiration, and vulnerability of stems to cavitation and loss of hydraulic conductivity by embolisms. Among the hydraulic architecture parameters measured were hydraulic conductivity per unit pressure gradient, specific conductivity, leaf-specific conductivity, and Huber value. In terms of vulnerability of stems to cavitation, stem and leaf capacitances, and leaf-specific conductivity, all three species followed the same sequence: Schefflera > Acer > Thuja. It is argued here that the high stem capacitance and high leaf-specific conductivity of Schefflera are necessary to compensate for its high vulnerability to cavitation. Extractable water storage per unit leaf area in Schefflera stems is >100 times that of Acer and may permit the species to survive unusually long, dry seasons in Panama. Although Schefflera frequently grows >20 meters, the biggest resistance to water flow in the shoots resides in the leaves.",1
"Tyree, M T, Snyderman, D A, Wilmot, T R, Machado, J L",2
Effects of temperature on the coupled activities of the vanadate-sensitive proton pump from maize root microsomes.,0
"The mechanism by which proton transport is coupled to ATP hydrolysis by vanadate-sensitive pumps is poorly understood. The effects of temperature on the activities of the vanadate-sensitive ATPase from maize (Zea mays) roots were assessed to provide insight into the coupling mechanism. The initial rate of proton transport had a bell-shaped dependence on temperature with an optimal range between 20 and 30 degrees C. However, the rate of vanadate-sensitive ATP hydrolysis increased as the temperature was raised from 4 to 43 degrees C. The differential sensitivity of proton transport to temperatures above 30 degrees C was also observed when the ATPase was reconstituted into dioleoylphosphatidylcholine vesicles. Inhibition of proton transport with temperatures above 30 degrees C was associated with higher rates of proton leakage from the membranes. In addition, proton transport was more inhibited than ATP hydrolysis at temperatures below 10 degrees C. Reduced rates of proton transport at lower temperatures were not associated with higher rate of proton conductivity across the membranes. Therefore, the preferential inhibition of proton transport at temperatures below 10 degrees C may reflect an effect of temperature on the coupling between proton transport and ATP hydrolysis within the vanadate-sensitive ATPase.",1
"Brauer, D, Loper, M, Schubert, C, Tu, S I",2
Correlation between CAM-Cycling and Photosynthetic Gas Exchange in Five Species of Talinum (Portulacaceae).,0
"Photosynthetic gas exchange and malic acid fluctuations were monitored in 69 well-watered plants from five morphologically similar species of Talinum in an investigation of the ecophysiological significance of the Crassulacean acid metabolism (CAM)-cycling mode of photosynthesis. Unlike CAM, atmospheric CO(2) uptake in CAM-cycling occurs exclusively during the day; at night, the stomata are closed and respiratory CO(2) is recaptured to form malic acid. All species showed similar patterns of day-night gas exchange and overnight malic acid accumulation, confirming the presence of CAM-cycling. Species averages for gas exchange parameters and malic acid fluctuation were significantly different such that the species with the highest daytime gas exchange had the lowest malic acid accumulation and vice versa. Also, daytime CO(2) exchange and transpiration were negatively correlated with overnight malic acid fluctuation for all individuals examined together, as well as within one species. This suggests that malic acid may effect reductions in both atmospheric CO(2) uptake and transpiration during the day. No significant correlation between malic acid fluctuation and water-use efficiency was found, although a nonsignificant trend of increasing water-use efficiency with increasing malic acid fluctuation was observed among species averages. This study provides evidence that CO(2) recycling via malic acid is negatively correlated with daytime transpirational water losses in well-watered plants. Thus, CAM-cycling could be important for survival in the thin, frequently desiccated soils of rock outcrops on which these plants occur.",1
"Harris, F S, Martin, C E",2
Inhibition by Ethylene of Auxin-Promotion of Flower Bud Formation in Tobacco Explants Is Absent in Plants Transformed by Agrobacterium rhizogenes.,0
"The in vitro regeneration of flower buds was studied in pedicel explants from tobacco (Nicotiana tabacum L., cv Petit Havana) transformed with Agrobacterium rhizogenes, pRi 1855 (agropine type). At a low concentration (0.1 micromolar) of 1-naphthalene-acetic acid, pedicel strips from phenotypically aberrant plants regenerated two to three times more flower buds than explants from untransformed tobacco. Intermediate bud numbers were observed in transformants with a less extreme phenotype. The results can be explained by an increased sensitivity of the transformed explants to auxin with respect to flower bud regeneration. The effect of transformation on the auxin response is fully accounted for by the absence of a negative interaction of endogenous ethylene with 1-naphthaleneacetic acid, a phenomenon normally encountered in untransformed tissues. Three observations led to this conclusion. Application of 1 micromolar AgNO(3) to untransformed explants increased the number of flower buds to the level observed in transformed tissues but had no effect on transformed pedicel strips; exposure to 10 microliters per liter ethylene strongly reduced the response to auxin at all concentrations in untransformed explants but was almost ineffective in the transformed tissues; and endogenous ethylene synthesis occurred at the same rate in both types of explants.",1
"Smulders, M J, Croes, A F, Kemp, A, Hese, K M, Harren, F, Wullems, G J",2
Lipids of plasma membranes prepared from oat root cells : effects of induced water-deficit tolerance.,0
"Plasma membranes were isolated from oat (Avena sativa) roots by the phase-partitioning method. The membranes were exposed to repeated periods of moderate water-deficit stress, and a water-deficit tolerance was induced (acclimated plants). The plasma membranes of the controls (nonacclimated plants) were characterized by a high phospholipid content, 79% of total lipids, cerebrosides (9%) containing hydroxy fatty acids (>90% 24:1-OH) and free sterols, acylated sterylglucosides, sterylglucosides, and steryl esters, together amounting to 12%. Major phospholipids were phosphatidylcholine and phosphatidylethanolamine with lesser amounts of phosphatidylglycerol, phosphatidylinositol, and phosphatidic acid. After the membranes were acclimated to dehydration, the lipid to protein ratio decreased from 1.3 to 0.7 micromoles per milligram. Furthermore, the cerebrosides decreased to 5% and free sterols increased from 9% (nonacclimated plants) to 14%. Because the total phospholipids did not change significantly, the free sterol to phospholipid ratio increased from 0.12 to 0.19. There was no change in the relative distribution of sterols after acclimation. The ratio of phosphatidylcholine to phosphatidylethanolamine changed from 1.1 in the nonacclimated plants to 0.69 in the acclimated plants. The results show that acclimation to dehydration implies substantial alterations in the lipid composition of the plasma membrane.",1
"Norberg, P, Liljenberg, C",2
Characterization and Intraorganellar Distribution of Protein Kinases in Amyloplasts Isolated from Cultured Cells of Sycamore (Acer pseudoplatanus L.).,0
"Incubation of amyloplasts isolated from cultured cells of sycamore (Acer pseudoplatanus L.) with [gamma-(32)P]ATP resulted in the rapid phosphorylation (half-time of 40 seconds at 25 degrees Celcius) of organellar polypeptides. The preferred substrate for amyloplast protein kinases was Mg(2+). ATP, and recovery of only [(32)P]serine after partial acid hydrolysis indicated the predominance of protein serine kinases in the organelle. These activities were located in the envelope and stromal fractions of the plastid, which showed different specificities toward exogenous protein substrates and distinct patterns of phosphorylation of endogenous polypeptides. A 66-kilodalton polypeptide, inaccessible to an exogenously added protease, was one of the major phosphorylated products found in intact amyloplasts at low [gamma-(32)P] adenosine triphosphate concentrations. This polypeptide represented the major phosphoprotein observed with the isolated envelope fraction. The patterns of polypeptide phosphorylation found in intact amyloplasts and chloroplasts from cultured cell lines of sycamore were clearly distinguishable. The overall results indicate the presence of protein phosphorylation systems unique to this reserve plastid present in nonphotosynthetic tissues.",1
"Viale, A M, Ngernprasirtsiri, J, Akazawa, T",2
Use of Dimethyl Sulfoxide to Detect Hydroxyl Radical during Bacteria-Induced Hypersensitive Reaction.,0
"Excess active oxygen is generated during the hypersensitive reaction (HR), an incompatible reaction of plants to bacterial pathogens. During HR, lipid peroxidation correlates chronologically with production of the oxygen species, superoxide (O(2) (.-)). However, O(2) (.-) may not be the active oxygen species that initiates lipid peroxidation. Evidence from other systems suggest that O(2) (.-) is converted to the hydroxyl radical (HO(.)) before lipid peroxidation is initiated. Until recently, HO(.) could not be detected directly in vivo. This study utilizes a newly reported method to directly detect and quantify the formation of HO(.)in vivo. Dimethyl sulfoxide (DMSO), used as a molecular probe, is oxidized by HO(.), forming the stable compound methanesulfinic acid. The methanesulfinic acid can be easily extracted from plant tissues and measured with a colorimetric assay. This study demonstrates significant increases in HO(.) concentration after simultaneous infiltration of cucumber (Cucumis sativa L.) plants with paraquat and DMSO. The concentration of HO(.) did not increase significantly when cucumber plants were infiltrated simultaneously with the HR-inducing bacteria, Pseudomonas syringae pv. pisi, and with DMSO. Lipid peroxidation, however, could be measured at times when HO(.) was not detectable. It appears that HO(.) is not generated during bacteria-induced HR; therefore, HO(.) is not responsible for the initiation of lipid peroxidation.",1
"Popham, P L, Novacky, A",2
Binding form of pollen mother cell protein in the nucleosomes of lily.,0
"We have previously reported the existence of pollen mother cell nuclear protein (PMCP) which appears during microsporogenesis in lily (Lilium spesiosum). It is very similar to mammalian testis specific H1 histone, H1t. In this paper, we describe the PMCP distribution in lily nucleosomes. Isolated nuclei were treated with micrococcal nuclease, and template active and inactive chromatin fractions were prepared. The nucleosome repeat length of pollen mother cells was determined to be 210 base pairs. The majority of the PMCP was found in the template inactive chromatin fraction, similar to other histones. PMCP was contained in the nucleosome monomer, but not in the core particle. However, PMCP was mainly found in the nucleosome dimer when slightly digested. Salt extraction from isolated nuclei indicated that PMCP and H1 histone share similar binding affinities to DNA. Judging from our results, it seems probable that PMCP links two core particles more strongly than H1 histone does. Since it is known that meiotic chromatin includes nick transferase and nuclease activity, one possible role of PMCP is the protection of its own chromatin. Other possible functions of PMCP are also discussed.",1
"Sasaki, Y, Harada, H",2
Transmembrane Electron Transport in Plasma Membrane Vesicles Loaded with an NADH-Generating System or Ascorbate.,0
"Sugar beet (Beta vulgaris L.) leaf plasma membrane vesicles were loaded with an NADH-generating system (or with ascorbate) and were tested spectrophotometrically for their ability to reduce external, membrane-impermeable electron acceptors. Either alcohol dehydrogenase plus NAD(+) or 100 millimolar ascorbate was included in the homogenization medium, and right-side-out (apoplastic side-out) plasma membrane vesicles were subsequently prepared using two-phase partitioning. Addition of ethanol to plasma membrane vesicles loaded with the NADH-generating system led to a production of NADH inside the vesicles which could be recorded at 340 nanometers. This system was able to reduce 2,6-dichlorophenolindophenol-3'-sulfonate (DCIP-sulfonate), a strongly hydrophilic electron acceptor. The reduction of DCIP-sulfonate was stimulated severalfold by the K(+) ionophore valinomycin, included to abolish membrane potential (outside negative) generated by electrogenic transmembrane electron flow. Fe(3+)-chelates, such as ferricyanide and ferric citrate, as well as cytochrome c, were not reduced by vesicles loaded with the NADH-generating system. In contrast, right-side-out plasma membrane vesicles loaded with ascorbate supported the reduction of both ferric citrate and DCIP-sulfonate, suggesting that ascorbate also may serve as electron donor for transplasma membrane electron transport. Differences in substrate specificity and inhibitor sensitivity indicate that the electrons from ascorbate and NADH were channelled to external acceptors via different electron transport chains. Transplasma membrane electron transport constituted only about 10% of total plasma membrane electron transport activity, but should still be sufficient to be of physiological significance in, e.g. reduction of Fe(3+) to Fe(2+) for uptake.",1
"Askerlund, P, Larsson, C",2
Pyrophosphate Dependent Phosphofructokinase of Citrullus lanatus: Molecular Forms and Expression of Subunits.,0
"During germination and seedling establishment, the total pyrophosphate-dependent phosphofructokinase (PFP) activity in the cotyledons increases. Two types of subunits with molecular weights of 68 (alpha-subunit) and 65 (beta-subunit) kilodaltons are present. The increase in activity coincides with an approximately 10-fold increase in beta-subunit and twofold increase in alpha-subunit content. Different isoforms of PFP are present at all stages of incubation, but the ratio between the isoforms significantly changes. A linear relationship exists between the ratio of the two PFP subunits and the ratio of the two isoforms of the enzyme. The more anionic (peak 2) isoform of the enzyme apparently is favored by a high ratio of total beta-subunit to alpha-subunit content. The beta- to alpha-subunit ratio of the peak 2 isoform is also approximately fivefold higher than that of the peak 1 (less anionic) isoform. It is evident that the two subunits are not coordinately expressed and the level of expression of each subunit appears to be the primary factor determining the molecular form in which the enzyme is present. In some tissues, only the 65 kilodalton polypeptide is expressed in large amounts. The peak 1 isoform has a higher affinity for pyrophosphate than the peak 2 isoform, while the affinity for fructose-6-phosphate is similar. Both molecular forms are activated by fructose-2,6-bisphosphate.",1
"Botha, A M, Botha, F C",2
Changes in Cytokinins before and during Early Flower Bud Differentiation in Lychee (Litchi chinensis Sonn.).,0
"Lychee (Litchi chinensis) has been analyzed for cytokinins in buds before and after flower bud differentiation, using reversephase high performance liquid chromatography in combination with Amaranthus bioassay and gas chromatography-mass spectrometry-selected ion monitoring. Four cytokinins, zeatin, zeatin riboside, N(6)-(delta(2)-isopentenyl)adenine, and N(6)-(delta(6)-isopentenyl) adenine riboside, were detected in buds. There was an increase of cytokinin activity in the buds during flower bud differentiation. In dormant buds, the endogenous cytokinin content was low, and the buds did not respond to exogenous cytokinin application. Application of kinetin promotes flower bud differentiation significantly after bud dormancy. These results are interpreted as an indication that the increase in endogenous cytokinin levels during flower bud differentiation may be correlative rather than the cause of flower bud initiation.",1
"Chen, W S",2
Ferredoxin and ferredoxin-NADP reductase from photosynthetic and nonphotosynthetic tissues of tomato.,0
"Ferredoxin and ferredoxin-NADP+ oxidoreductase (FNR) were purified from leaves, roots, and red and green pericarp of tomato (Lycopersicon esculentum, cv VFNT and cv Momotaro).  Four different ferredoxins were identified on the basis of N-terminal amino acid sequence and charge.  Ferredoxins I and II were the most prevalent forms in leaves and green pericarp, and ferredoxin III was the most prevalent in roots.  Red pericarp of the VFNT cv yielded variable amounts of ferredoxins II and III plus a unique form, ferredoxin IV.  Red pericarp of the Momotaro cv contained ferredoxins I, II, and IV.  This represents the first demonstration of ferredoxin in a chromoplast-containing tissue.  There were no major differences among the tomato ferredoxins in absorption spectrum or cytochrome c reduction activity.  Two forms of FNR were present in tomato as judged by anion exchange chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.  FNR II had a lower apparent relative molecular weight, a slightly altered absorption spectrum, and a lower specific activity for cytochrome c reduction than FNR I.  FNR II could be a partially degraded form of FNR I.  The FNRs from the different tissues of tomato plants all showed diaphorase activity, with FNR II being more active than FNR I.  The presence of ferredoxin and FNR in heterotrophic tissues of tomato is consistent with the existence of a nonphotosynthetic ferredoxin/FNR redox pathway to support the function of ferredoxin-dependent enzymes.",1
"Green, L S, Yee, B C, Buchanan, B B, Kamide, K, Sanada, Y, Wada, K, Buchanan, B B",2
Soluble Chloroplast Enzyme Cleaves preLHCP Made in Escherichia coli to a Mature Form Lacking a Basic N-Terminal Domain.,0
"We have investigated the specificity of a chloroplast soluble processing enzyme that cleaves the precursor of the major light-harvesting chlorophyll a/b binding protein (LHCP). The precursor of LHCP (preLHCP) was synthesized in Escherichia coli and recovered from inclusion-like bodies. It was found to be a substrate for proteolytic cleavage by the soluble enzyme in an organelle-free reaction, yielding a 25 kilodalton peptide. This peptide co-migrated during sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the smaller of the forms (25 and 26 kilodalton) produced when either the E. coli-synthesized precursor, or preLHCP made in a reticulocyte lysate, was imported into chloroplasts. N-Terminal sequence analysis of the E. coli-generated precursor showed that it lacked an N-terminal methionine. N-Terminal sequencing of the 25 kilodalton peptide produced in the organelle-free reaction indicated that processing occurred between residues 40 and 41, removing a basic domain (RKTAAK) thought to be at the N-terminus of all LHCP molecules of type I associated with photosystem II. To determine if the soluble enzyme involved also cleaves other precursor polypeptides, or is specific to preLHCP, it was partially purified, and the precursors for Rubisco small subunit, plastocyanin, Rubisco activase, heat shock protein 21, and acyl carrier protein were tested as substrates. All of these precursors were cleaved by the same chromatographic peak of activity that processes preLHCP in the organelle-free reaction.",1
"Abad, M S, Oblong, J E, Lamppa, G K",2
"Effects of Salt Stress on Amino Acid, Organic Acid, and Carbohydrate Composition of Roots, Bacteroids, and Cytosol of Alfalfa (Medicago sativa L.).",0
"Ethanol-soluble organic acid, carbohydrate, and amino acid constituents of alfalfa (Medicago sativa) roots and nodules (cytosol and bacteroids) have been identified by gas-liquid chromatography and high performance liquid chromatography. Among organic acids, citrate was the predominant compound in roots and cytosol, with malonate present in the highest concentration in bacteroids. These two organic acids together with malate and succinate accounted for more than 85% of the organic acid pool in nodules and for 97% in roots. The major carbohydrates in roots, nodule cytosol, and bacteroids were (descending order of concentration): sucrose, pinitol, glucose, and ononitol. Maltose and trehalose appeared to be present in very low concentrations. Asparagine, glutamate, alanine, gamma-aminobutyrate, and proline were the major amino acids in cytosol and bacteroids. In addition to these solutes, serine and glutamine were well represented in roots. When alfalfa plants were subjected to 0.15 m sodium chloride stress for 2 weeks, total organic acid concentration in nodules and roots were depressed by more than 40%, whereas lactate concentration increased by 11, 27, and 94% in cytosol, roots, and bacteroids, respectively. In bacteroids, lactate became the most abundant organic acid and might contribute partly to the osmotic adjustment. On the other hand, salt stress induced a large increase in the amino acid and carbohydrate pools. Within the amino acids, proline showed the largest increase, 11.3-, 12.8-, and 8.0-fold in roots, cytosol, and bacteroids, respectively. Its accumulation reflected an osmoregulatory mechanism not only in roots but also in nodule tissue. In parallel, asparagine concentration was greatly enhanced; this amide remained the major nitrogen solute and, in bacteroids, played a significant role in osmoregulation. On the contrary, the salt treatment had a very limited effect on the concentration of other amino acids. Among carbohydrates, pinitol concentration was increased significantly, especially in cytosol and bacteroids (5.4- and 3.4-fold, respectively), in which this cyclitol accounted for more than 35% of the total carbohydrate pool; pinitol might contribute to the tolerance to salt stress. However, trehalose concentration remained low in both nodules and roots; its role in osmoregulation appeared unlikely in alfalfa.",1
"Fougère, F, Le Rudulier, D, Streeter, J G",2
Isolation and Characterization of Three Genes Negatively Regulated by Phytochrome Action in Lemna gibba.,0
"We have isolated three distinct cDNA clones from Lemna gibba representing mRNAs that increase in abundance during dark treatment. All three mRNAs showed reduced expression in response to red or white light. These mRNAs range from approximately 680 to 800 nucleotides in length and thus encode relatively small proteins (maximum relative molecular weight 17,000 to 19,000). The genes corresponding to these dark-abundant mRNAs are designated NPR (negatively phytochrome regulated) 1, 2, and 3. Differences in the rapidity of mRNA accumulation during dark treatment were observed for each of the genes in both mature green plants and in etiolated plants. Differences in accumulation pattern were also observed in etiolated plants, depending on whether the plants received a far-red light treatment prior to darkness. Transcription of all three genes, assayed in nuclei isolated from either green or etiolated plants, increased during dark treatment. In etiolated plants, a single 2 minute red light treatment caused a detectable decrease in the transcription of the genes after the dark treatment, and 10 minutes of far-red light given immediately after the red light resulted in a reversal of the effect of red light. Additionally, treatment of the plants with far-red light prior to darkness resulted in greater rates of transcription of the NPR genes. Therefore, we conclude that phytochrome action results in decreased transcription of these NPR genes. Each of the NPR mRNAs are encoded by one to two genes.",1
"Okubara, P A, Tobin, E M",2
Limitations of Photosynthesis in Pinus taeda L. (Loblolly Pine) at Low Soil Temperatures.,0
"The relative importance of stomatal and nonstomatal limitations to net photosynthesis (A) and possible signals responsible for stomatal limitations were investigated in unhardened Pinus taeda seedlings at low soil temperatures. After 2 days at soil temperatures between 13 and 7 degrees C, A was reduced by 20 to 50%, respectively. The reduction in A at these moderate root-chilling conditions appeared to be the result of stomatal limitations, based on the decrease in intercellular CO(2) concentrations (c(i)). This conclusion was supported by A versus c(i) analysis and measurements of O(2) evolution at saturating CO(2), which suggested increases in stomatal but not biochemical limitations at these soil temperatures. Nonuniform stomatal apertures, which were demonstrated with abscisic acid, were not apparent 2 days after root chilling, and results of our A versus c(i) analysis appear valid. Bulk shoot water potential (psi) declined as soil temperature dropped below 16 degrees C. When half the root system of seedlings was chilled, shoot psi and gas-exchange rates did not decline. Thus, nonhydraulic root-shoot signals were not implicated in stomatal limitations. The initial decrease in leaf conductance to water vapor after root chilling appeared to precede any detectable decrease in bulk fascicle psi, but may be in response to a decrease in turgor of epidermal cells. These reductions in leaf conductance to water vapor, which occurred within 30 minutes of root chilling, could be delayed and temporarily reversed by reducing the leaf-to-air vapor-pressure deficit, suggesting that hydraulic signals may be involved in initiating stomatal closure. By independently manipulating the leaf-to-air vapor-pressure deficit of individual fascicles, we could induce uptake of water vapor through stomata, suggesting that nonsaturated conditions occur in the intercellular airspaces. There was an anomaly in our results on seedlings maintained for 2 days at soil temperatures below 7 degrees C. Lower A appeared primarily the result of nonstomatal limitations, based on large increases in calculated c(i) and A versus c(i) analysis. In contrast, measurements of O(2) evolution at saturating CO(2) concentrations implied nonstomatal limitations per se did not increase at these temperatures. One explanation for this paradox is that calculations of c(i) are unreliable at very low gas-exchange rates because of inadequate measurement resolution, and limitations of A are predominantly stomatal. An alternative interpretation is that increases in c(i) are real and the results from O(2)-evolution measurements are in error. The high CO(2) concentration used in O(2)-evolution measurements (15%) may have overcome nonstomatal limitations by enzymes that were down-regulated by a feedback mechanism. In this scenario, carbohydrate feedback limitations may be responsible for nonstomatal reductions in A after 2 days at soil temperatures below 7 degrees C.",1
"Day, T A, Heckathorn, S A, Delucia, E H",2
Arabinose Kinase-Deficient Mutant of Arabidopsis thaliana.,0
"A mutant of Arabidopsis thaliana that is sensitive to exogenous l-arabinose has been isolated. Comparisons of growth of the wild type, mutant, and F1 and F2 progeny of crosses showed the arabinose-sensitive phenotype is semidominant and segregates as a single Mendelian locus. Crosses of the mutant to marker strains showed the mutation is linked to the eceriferum-2 locus on chromosome 4. In vivo incorporation of exogenous labeled l-arabinose into ethanol-insoluble polysaccharides was greatly reduced in the mutant with a concomitant accumulation of free labeled arabinose. Enzyme assays of crude plant extracts demonstrated a defect in arabinose kinase activity in the mutant.",1
"Dolezal, O, Cobbett, C S",2
Effect of Elicitors on the Plasmamembrane of Petunia hybrida Cell Suspensions : Role of DeltapH in Signal Transduction.,0
"Primary processes during elicitation of the phenylpropanoid pathway (PPP) were studied in Petunia hybrida cell suspensions. We tested the hypothesis that decrease of the proton gradient across the plasma membrane activates the PPP. Induction of the PPP was determined by measuring phenylalanine ammonia lyase activity. A variety of ATPase inhibitors and ionophores were tested for the ability to elicit the PPP. The ATPase inhibitors orthovanadate and N,N'-dicyclohexylcarbodiimide and the ionophores carbonyl cyanide-4-trifluoromethoxyphenylhydrazone and nigericin were all effective elicitors. Carbonyl cyanide-4-trifluoromethoxyphenylhydrazone and nigericin elicit also when used in combination with N,N'-dicyclohexylcarbodiimide. Valinomycin had little effect on phenylalanine ammonia lyase activity. Treatment with orthovanadate or nigericin led to the formation of lignin. Alkalinization of the external medium by N,N'-dicyclohexylcarbodiimide, carbonyl cyanide-4-trifluoromethoxyphenylhydrazone, and nigericin was observed directly with the use of a sensitive pH electrode and internal acidification was deduced from the changes in emission intensity of the fluorescent probe bis[3-propyl-5-oxoisoxazol-4-yl] pentamethineoxonol. These data indicate that changes in the activity of the plasmamembrane H(+)-ATPase, and subsequent decrease of the proton gradient (particularly of the pH gradient) by itself are sufficient to influence phenylalanine ammonia lyase activity of P. hybrida cells and are therefore important intermediates in signal transduction.",1
"Hagendoorn, M J, Poortinga, A M, Sang, H W, van der Plas, L H, van Walraven, H S",2
Isolation and characterization of a small heat shock protein gene from maize.,0
"A maize (Zea mays L.) genomic clone (Zmempr 9') was isolated on the basis of its homology to a meiotically expressed Lilium sequence. Radiolabeled probe made from the maize genomic clone detected complementary RNA at high fidelity. Furthermore, it hybridized to RNA isolated from staged (an interval that is coincident with meiotic prophase) maize tassel spikelets. Complimentary RNA was strongly (at least 50-fold) induced during heat shock of maize somatic tissue and appeared as a single size class in Northern blot hybridizations. Sequencing of the complete coding region of Zmempr 9' confirmed the homology of the inferred amino acid sequence to other small heat shock proteins. Consensus sequences found in the flanking regions corresponded to the usual signals for initiation of RNA transcription, polyadenylate addition, and the induction of heat shock genes. The latter sequences conferred heat shock-specific transient expression in electroporated protoplasts when cloned into promoterless reporter gene plasmid constructs. Hybrid-selected translations revealed specific translation products ranging from 15 to 18 kilodaltons, providing evidence that this gene is a member of a related multigene family. We therefore conclude that this maize genomic DNA clone, recovered through its homology to clones for meiotic transcripts in lily, represents a genuine maize small heat shock protein gene.",1
"Dietrich, P S, Bouchard, R A, Casey, E S, Sinibaldi, R M",2
Root Isoflavonoid Response to Grafting between Wild-Type and Nodulation-Mutant Soybean Plants.,0
"It was previously reported that the hypernodulating soybean (Glycine max [L.] Merr.) mutants, derived from the cultivar Williams, had higher root concentration of isoflavonoid compounds (daidzein, genistein, and coumestrol) than did Williams at 9 to 12 days after inoculation with Bradyrhizobium japonicum. These compounds are known inducers of nod genes in B. japonicum and may be involved in subsequent nodule development. The current study involving reciprocal grafts between NOD1-3 (hypernodulating mutant) and Williams showed that root isoflavonoid concentration and content was more than twofold greater when the shoot genotype was NOD1-3. When grafted, NOD1-3 shoots also induced hypernodulation on roots of both Williams and NOD1-3, while Williams shoots induced normal nodulation on both root genotypes. This shoot control of hypernodulation may be causally related to differential root isoflavonoid levels, which are also controlled by the shoot. In contrast, the nonnodulating characteristic of the NN5 mutant was strictly root controlled, based on reciprocal grafts. Delayed inoculation (7 days after planting) resulted in greater nodule numbers on both NOD1-3 and Williams, compared with a seed inoculation treatment. The nodulation pattern of grafted plants was independent of whether the shoot portion was derived from inoculated seed or uninoculated seed, when grafted at day 7 onto seedling roots derived from inoculated seed. This observation, coupled with the fact that no difference existed in nodule number of NOD1-3 and Williams until after 9 days from seed inoculation, indicated that if isoflavonoids play a role in differential nodulation of the hypernodulating mutant and the wild type, the effect is on advanced stages of nodule ontogeny, possibly related to autoregulation, rather than on initial infection stages.",1
"Cho, M J, Harper, J E",2
Metabolic evidence for stelar anoxia in maize roots exposed to low o(2) concentrations.,0
"This investigation presents metabolic evidence to show that in 4- to 5-day-old roots of maize (Zea mays hybrid GH 5010) exposed to low external O(2) concentrations, the stele receives inadequate O(2) for oxidative phosphorylation, while the cortex continues to respire even when the external solution is at zero O(2) and the roots rely solely on aerenchyma for O(2) transport. Oxygen uptake rates (micromoles per cubic centimeter per hour) declined at higher external O(2) concentrations in excised segments from whole roots than from the isolated cortex; critical O(2) pressures for respiration were greater than 0.26 moles per cubic meter O(2) (aerated solution) for the whole root and only 0.075 moles per cubic meter O(2) for the cortex. For plants with their shoots excised and the cut stem in air, ethanol concentrations (moles per cubic meter) in roots exposed to 0.06 moles per cubic meter O(2) were 3.3 times higher in the stele than in the cortex, whereas this ethanol gradient across the root was not evident in roots exposed to 0 moles per cubic meter O(2). Alanine concentrations (moles per cubic meter) in the stele of roots exposed to 0.13 and 0.09 moles per cubic meter O(2) increased by 26 and 44%, respectively, above the levels found for aerated roots, whereas alanine in the cortex was unchanged; the increase in stelar alanine concentration was not accompanied by changes in the concentration of free amino acids other than alanine. For plants with their shoots intact, alcohol dehydrogenase and pyruvate decarboxylase activities (micromoles per gram protein per minute) in roots exposed to 0.13 moles per cubic meter O(2) increased in the stele by 40 to 50% over the activity in aerated roots, whereas there was no appreciable increase in alcohol dehydrogenase and pyruvate decarboxylase activity in the cortex of these roots. More convincingly, for roots receiving O(2) solely from the shoots via the aerenchyma, pyruvate decarboxylase in the cortex was in an ""inactive"" state, whereas pyruvate decarboxylase in the stele was in an ""active"" state. These results suggest that for roots in O(2)-free solutions, the aerenchyma provides adequate O(2) for respiration in the cortex but not in the stele, and this was supported by a change in pyruvate decarboxylase in the cortex to an active state when the O(2) supply to the roots via the aerenchyma was blocked.",1
"Thomson, C J, Greenway, H",2
Relationship of endogenous abscisic Acid to sucrose level and seed growth rate of soybeans.,0
"It has been proposed that abscisic acid (ABA) may stimulate sucrose transport into filling seeds of legumes, potentially regulating seed growth rate. The objective of this study was to determine whether the rate of dry matter accumulation in seeds of soybeans (Glycine max L.) is correlated with the endogenous levels of ABA and sucrose in those sinks. The levels of ABA and sucrose in seed tissues were compared in nine diverse Plant Introduction lines having seed growth rates ranging from 2.5 to 10.0 milligrams dry weight per seed per day. At 14 days after anthesis (DAA), seeds of all genotypes contained less than 2 micrograms of ABA per gram fresh weight. Levels of ABA increased rapidly, however, reaching maxima at 20 to 30 DAA, depending upon tissue type and genotype. ABA accumulated first in seed coats and then in embryos, and ABA maxima were higher in seed coats (8 to 20 micrograms per gram fresh weight) than in embryos (4 to 9 micrograms per gram fresh weight. From 30 to 50 DAA, ABA levels in both tissues decreased to less than 2 micrograms per gram fresh weight. Levels of sucrose were also low early in development, less than 10 milligrams per gram fresh weight at 14 DAA. However, by 30 DAA, sucrose levels in seed coats had increased to 20 milligrams per gram fresh weight and remained fairly constant for the remainder of the filling period. In contrast, sucrose accumulated in embryos throughout the filling period, reaching levels greater than 40 milligrams per gram fresh weight by 50 DAA. Correlation analyses indicated that the level of ABA in seed coats and embryos was not directly correlated to the level of sucrose measured in those tissues or to the rate of seed dry matter accumulation during the linear filling period. Rather, the ubiquitous pattern of ABA accumulation early in development appeared to coincide with water uptake and the rapid expansion of cotyledons occurring at that time. Whole tissue sucrose levels in embryos and seed coats, as well as sucrose levels in the embryo apoplast, were generally not correlated with the rate of dry matter accumulation. Thus, it appears that, in this set of diverse soybean genotypes, seed growth rate was not limited by endogenous concentrations of ABA or sucrose in reproductive tissues.",1
"Schussler, J R, Brenner, M L, Brun, W A",2
Activation of Plasma Membrane NADH Oxidase Activity by Products of Phospholipase A.,0
"An auxin-stimulated NADH oxidase activity (NADH oxidase I) of plasma membrane vesicles, highly purified by aqueous two-phase partition from soybean (Glycine max Merr.) hypocotyls was activated by lysophospholipids and fatty acids, both products of phospholipase A action. The activation of NADH oxidase activity occurred slowly, suggesting a mechanism whereby the lipids acted to stabilize the enzyme in a more active configuration. In contrast to activation by lipids, the activation by auxin was rapid. The average K(m) of the NADH oxidase after activation by lipids was four- to fivefold less than the K(m) before activation. The V(max) was unchanged by activation. The increases occurred in the presence of detergent and thus were not a result of exposure of latent active sites. Also, the activation did not result from activation of a peroxidase or lipoxygenase. Fatty acid esters, where growth promoting effects have been reported, also activated the auxin-stimulated oxidase. However, the auxin stimulation of NADH oxidase I did not appear to be obligatorily mediated by phospholipase A, nor did inhibitors of phospholipase A(2) block the stimulation of the oxidase by auxins.",1
"Brightman, A O, Zhu, X Z, Morré, D J",2
Origin of Thylakoid Membranes in Chlamydomonas reinhardtii y-1 at 38 degrees C.,0
"The origin of thylakoid membranes was studied in Chlamydomonas reinhardtii y-1 cells during greening at 38 degrees C. Previous studies showed that, when dark-grown cells are exposed to light under these conditions, the initial rates of accumulation of chlorophyll and the chlorophyll a/b-binding proteins in membranes are maximal (MA Maloney JK Hoober, DB Marks [1989] Plant Physiol 91: 1100-1106; JK Hoober MA Maloney, LR Asbury, DB Marks [1990] Plant Physiol 92: 419-426). As shown in this paper, photosystem II activity, which was nearly absent in dark-grown cells, also increased at a linear rate in parallel with chlorophyll. As compared with those made at 25 degrees C, photosystem II units assembled during greening at 38 degrees C were photochemically more efficient, as judged by saturation at a lower fluence of light and a negligible loss of excitation energy as fluorescence. Electron microscopy of cells in light for 5 or 15 minutes at 38 degrees C showed that these initial, functional thylakoid membranes developed in association with the chloroplast envelope.",1
"Hoober, J K, Boyd, C O, Paavola, L G",2
Immunocytochemical Localization of Mandelonitrile Lyase in Mature Black Cherry (Prunus serotina Ehrh.) Seeds.,0
"Mandelonitrile lyase (MDL, EC 4.1.2.10), which catalyzes the reversible dissociation of (R)-(+)-mandelonitrile to benzaldehyde and hydrogen cyanide, was purified to apparent homogeneity from mature black cherry (Prunus serotina Ehrh.) seeds by conventional protein purification techniques. This flavoprotein is monomeric with a subunit molecular mass of 57 kilodaltons. Glycoprotein character was shown by its binding to the affinity matrix concanavalin A-Sepharose 4B with subsequent elution by alpha-methyl-d-glucoside. Upon chemical deglycosylation by trifluoromethanesulfonic acid, the molecular mass was reduced to 50.9 kilodaltons. Two-dimensional gel analysis of deglycosylated MDL revealed the presence of several subunit isoforms of similar molecular mass but differing slightly in isoelectric point. Polyclonal antibodies were raised in New Zealand white rabbits against deglycosylated and untreated MDL. Antibody titers were determined by enzyme linked immunosorbent and dot immunobinding assays, while their specificities were assessed by Western immunoblot analysis. Antibodies raised against untreated lyase recognized several proteins in addition to MDL. In contrast, antisera raised against deglycosylated MDL were monospecific and were utilized for developmental and immunocytochemical localization studies. SDS-PAGE and immunoblotting analysis of seed proteins during fruit maturation showed that MDL first appeared in seeds shortly after cotyledons began development. In cotyledon cells of mature seeds, MDL was localized primarily in the cell wall with lesser amounts in the protein bodies, whereas in endosperm cells, this labeling pattern was reversed. N-terminal sequence data was gathered for future molecular approaches to the question of MDL microheterogeneity.",1
"Wu, H C, Poulton, J E",2
"DeltapH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet (Beta vulgaris L.) Leaves: II. Evidence for Multiple Aliphatic, Neutral Amino Acid Symports.",0
"Proton-coupled aliphatic, neutral amino acid transport was investigated in plasma membrane vesicles isolated from sugar beet (Beta vulgaris L., cv Great Western) leaves. Two neutral amino acid symport systems were resolved based on inter-amino acid transport competition and on large variations in the specific activity of each porter in different species. Competitive inhibition was observed for transport competition between alanine, methionine, glutamine, and leucine (the alanine group) and between isoleucine, valine, and threonine (the isoleucine group). The apparent K(m) and K(i) values were similar for transport competition among amino acids within the alanine group. In contrast, the kinetics of transport competition between these two groups of amino acids did not fit a simple competitive model. Furthermore, members of the isoleucine group were weak transport antagonists of the alanine group. These results are consistent with two independent neutral amino acid porters. In support of that conclusion, the ratio of the specific activity of alanine transport versus isoleucine transport varied from two- to 13-fold in plasma membrane vesicles isolated from different plant species. This ratio would be expected to remain relatively stable if these amino acids were moving through a single transport system and, indeed, the ratio of alanine to glutamine transport varied less than twofold. Analysis of the predicted structure of the aliphatic, neutral amino acids in solution shows that isoleucine, valine, and threonine contain a branched methyl or hydroxyl group at the beta-carbon position that places a dense electron cloud close to the alpha-amino group. This does not occur for the unbranched amino acids or those that branch further away, e.g. leucine. We hypothesize that this structural feature of isoleucine, valine, and threonine results in unfavorable steric interactions with the alanine transport system that limits their flux through this porter. Hydrophobicity and hydrated volumes did not account for the observed differences in transport specificity.",1
"Li, Z C, Bush, D R",2
Differentiation between Several Types of Phosphohydrolases in Light Microsomes of Corn Roots.,0
"The phosphohydrolase activity of a light microsomal fraction isolated from corn roots (Zea mays L. cv LG 55) was investigated. The fraction, which appears to be enriched in endoplasmic reticulum and Golgi membranes, has ATPase and pyrophosphatase activities that hydrolyze ATP and pyrophosphate at an optimum pH of 7.0, with K(m) values of about 160 and 240 micromolar and with V(max) values of about 200 and 50 nanomoles substrate hydrolyzed per milligram protein per minute, respectively. These enzymes differ in their sensitivity to anions and inhibitors. The ATPase is stimulated by sulfate anions, whereas pyrophosphatase is inhibited by molybdate. Furthermore, the simultaneous addition of ATP and pyrophosphate to the reaction medium increases phosphohydrolysis, suggesting that separate enzymes are operating in the membranes. We also observed that pyrophosphate competitively inhibits the ATPase, whereas ATP has no significant effect on the pyrophosphatase. On the other hand, we observed a detergent-stimulated, molybdate-insensitive inosine diphosphatase activity which, in the native state, hydrolyzes inosine diphosphate with a K(m) of about 700 micromolar and a V(max) of about 450 nanomoles inosine diphosphate hydrolyzed per milligram protein per minute. In the solubilized form, the enzyme appears to be fully active, exhibiting lower K(m) values to hydrolyze inosine diphosphate. Furthermore, we found that native inosine diphosphatase is inhibited either by ATP or pyrophosphate, whereas inosine diphosphate inhibits the ATPase, but has no significant effect on the pyrophosphatase. It appears that inosine diphosphate is a positive modulator of the inosine diphosphatase, whereas ATP and pyrophosphate act as negative modulators of this enzyme.",1
"Vicente, J A, Vale, M G",2
Transport and Metabolism of 1-Aminocyclopropane-1-carboxylic Acid in Sunflower (Helianthus annuus L.) Seedlings.,0
"Transport and metabolism of [2,3-(14)C] 1-aminocyclopropane-1-carboxylic acid (ACC) from roots to shoots in 4-day-old sunflower (Helianthus annuus L.) seedlings were studied. [(14)C]ACC was detected in, and (14)C(2)H(4) was evolved from, shoots 0.5 hours after [(14)C]ACC was supplied to roots. Ethylene emanation from the shoots returned to normal levels after 6 hours. The roots showed a similar pattern, although at 24 hours ethylene emanation was still slightly higher than in those plants that did not receive ACC. [(14)C]N-malonyl-ACC (MACC) was detected in both tissues at all times sampled. [(14)C]MACC levels surpassed [(14)C]ACC levels in the shoot at 2 hours, whereas [(14)C]MACC levels in the root remained below [(14)C]ACC levels until 6 hours, after which they were higher. Thin-layer chromatography analysis identified [(14)C] ACC in 1-hour shoot extracts, and [(14)C]MACC was identified in root tissues at 1 and 12 hours after treatment. [(14)C]ACC and [(14)C] MACC in the xylem sap of treated seedlings were identified by thin-layer chromatography. Xylem transport of [(14)C]ACC in treated seedlings, and transport of ACC in untreated seedlings, was confirmed by gas chromatography-mass spectrometry. Some evidence for the presence of [(14)C]MACC in xylem sap in [(14)C]ACC-treated seedlings is presented. A substantial amount of radioactivity in both ACC and MACC fractions was detected leaking from the roots over 24 hours. A second radiolabeled volatile compound was trapped in a CO(2)-trapping solution but not in mercuric perchlorate. Levels of this compound were highest after the peak of ACC levels and before peak MACC levels in both tissues, suggesting that an alternate pathway of ACC metabolism was operating in this system.",1
"Finlayson, S A, Foster, K R, Reid, D M",2
Light-enhanced dark respiration in mesophyll protoplasts from leaves of pea.,0
"The respiratory oxygen uptake by mesophyll protoplasts of pea (Pisum sativum cv Arkel) was stimulated up to threefold after 15 minutes of illumination at an intensity of 1250 microeinsteins per square meter per second in the presence of 5 millimolar bicarbonate at 30 degrees C. The extent of light-enhanced dark respiration (LEDR) increased progressively with duration of preillumination. The LEDR exhibited two phases. The initial high rate of respiration decreased in about 10 minutes to a lower steady value similar to that before illumination. The promotion of LEDR by the presence of bicarbonate and inhibition by glyceraldehyde or 3-(3,4-dichlorophenyl)-1,1-dimethylurea suggested that LEDR was dependent on products of photosynthetic carbon assimilation/electron transport. Thus, the photosynthetic products exert a markedly quick influence on dark respiration in mesophyll protoplasts.",1
"Reddy, M M, Vani, T, Raghavendra, A S",2
Complete Amino Acid Sequence of a Polypeptide from Zea mays Similar to the Pathogenesis-Related-1 Family.,0
"A polypeptide serologically related to the tobacco pathogenesis-related-1 family of proteins has been purified from the root tissue of maize (Zea mays L.), and the complete amino acid sequence has been determined. The mature protein has a calculated molecular weight of 14,970 and isoelectric point of 4.2. The maize protein shows 66 to 68% amino acid identity with the tobacco pathogenesis-related-1 family and 55% identity with the tomato p14 protein.",1
"Gillikin, J W, Burkhart, W, Graham, J S",2
Regulation of 5-Aminolevulinic Acid Synthesis in Developing Chloroplasts : IV. An Endogenous Inhibitor from the Thylakoid Membranes.,0
"5-Aminolevulinic acid synthesis in isolated, intact, developing chloroplasts from greening cucumber (Cucumis sativus) cotyledons was inhibited by broken chloroplast fragments. It was shown that the inhibitory constituent was associated with the thylakoid membrane system. The inhibitor was resistant to boiling, was not a form of ribonuclease, and did not inhibit Mg-chelatase, indicating that massive organelle destruction was not involved. The inhibitor was also found in etioplast and mature chloroplasts; and it was found in barley as well as cucumber. 5-Aminolevulinate synthesis in the dark with exogenous ATP and NADPH, or in the light without added cofactors, were inhibited approximately equally. In the dark, 5-aminolevulinate synthesis and protochlorophyllide synthesis from glutamate were inhibited to about equal extent. The inhibition was decreased when the membranes were washed with aqueous acetone prior to incubation. The inhibition by the unknown factor was compared to the inhibition by gabaculine, 4-amino-5-hexynoic acid, protoheme, and glutathione. The unknown inhibitor appeared to have a number of similarities with protoheme.",1
"Castelfranco, P A, Zeng, X",2
"Stress Responses in Alfalfa (Medicago sativa L.): X. Molecular Cloning and Expression of S-Adenosyl-l-Methionine:Caffeic Acid 3-O-Methyltransferase, a Key Enzyme of Lignin Biosynthesis.",0
"S-Adenosyl-l-methionine:caffeic acid 3-O-methyltransferase (COMT, EC 2.1.1.6) catalyzes the conversion of caffeic acid to ferulic acid, a key step in the biosynthesis of lignin monomers. We have isolated a functionally active cDNA clone (pCOMT1) encoding alfalfa (Medicago sativa L.) COMT by immunoscreening a lambdaZAPII cDNA expression library with anti-(aspen COMT) antibodies. The derived amino acid sequence of pCOMT1 is 86% identical to that of COMT from aspen. Southern blot analysis indicates that COMT in alfalfa is encoded by at least two genes. Addition of an elicitor preparation from bakers' yeast to alfalfa cell suspension cultures resulted in a rapid accumulation of COMT transcripts, which reached a maximum level around 19 hours postelicitation. Northern blot analysis of total RNA from different organs of alfalfa plants at various developmental stages showed that COMT transcripts are most abundant in roots and stems. Transcripts encoding ATP: i-methionine-S-adenosyl transferase (AdoMet synthetase, EC 2.5.1.6), the enzyme responsible for the synthesis of the methyl donor for the COMT reaction, were coinduced with COMT transcripts in elicitor-treated cells and exhibited a similar pattern of expression to that of COMT in different organs of alfalfa plants at various stages of development.",1
"Gowri, G, Bugos, R C, Campbell, W H, Maxwell, C A, Dixon, R A",2
Elicitor-induced ethylene biosynthesis in tomato cells: characterization and use as a bioassay for elicitor action.,0
"The induction of ethylene biosynthesis by an elicitor partially purified from yeast extract was studied in suspension-cultured tomato (Lycopersicon esculentum Mill.) cells. Unstimulated cells produced little ethylene during exponential growth and even less in stationary phase. Treatment with elicitor stimulated ethylene biosynthesis 10-fold to 20-fold in the exponentially growing cells and more than 100-fold in stationary cells. Activities of both 1-aminocyclopropane-1-carboxylate (ACC) synthase, measured in vitro, and ethylene-forming enzyme (EFE), measured in vivo, increased strongly in response to elicitor treatments. During exponential growth, cells contained large pools of ACC, and the elicitor stimulated ethylene biosynthesis primarily through induction of EFE. In the stationary phase, cells contained almost no ACC, and the elicitor stimulated ethylene biosynthesis primarily through its effect on ACC synthase activity. Cordycepin did not affect the increase in activity of ACC synthase but blocked that of EFE, indicating that the former was posttranscriptionally regulated, the latter transcriptionally regulated. Removal of elicitor by washing or inactivation of a biotinylated derivative of the elicitor by complexation with avidin caused a rapid cessation of the increase in ACC synthase activity, suggesting that continuous presence of stimulus is necessary for the response. Using induction of ethylene production to measure amounts of elicitor, it was found that the elicitor disappeared from the incubation medium during the course of the treatment.",1
"Felix, G, Grosskopf, D G, Regenass, M, Basse, C W, Boller, T",2
Relationships between the Efficiencies of Photosystems I and II and Stromal Redox State in CO(2)-Free Air : Evidence for Cyclic Electron Flow in Vivo.,0
"The responses of the efficiencies of photosystems I and II, stromal redox state (as indicated by NADP-malate dehydrogenase activation state), and activation of the Benson-Calvin cycle enzymes ribulose 1,5-bisphosphate carboxylase and fructose 1,6-bisphosphatase to varying irradiance were measured in pea (Pisum sativum L.) leaves operating close to the CO(2) compensation point. A comparison of the relationships among these parameters obtained from leaves in air was made with those obtained when the leaves were maintained in air from which the CO(2) had been removed. P700 was more oxidized at any measured irradiance in CO(2)-free air than in air. The relationship between the quantum efficiencies of the photosystems in CO(2)-free air was distinctly curvilinear in contrast to the predominantly linear relationship obtained with leaves in air. This nonlinearity may be consistent with the operation of cyclic electron flow around photosystem I because the quantum efficiency of photosystem II was much more restricted than the quantum efficiency of photosystem I. In CO(2)-free air, measured NADP-malate dehydrogenase activities varied considerably at low irradiances. However, at high irradiance the activity of the enzyme was low, implying that the stroma was oxidized. In contrast, fructose-1,6-bisphosphatase activities tended to increase with increasing electron flux through the photosystems. Ribulose-1,5-bisphosphate carboxylase activity remained relatively constant with respect to irradiance in CO(2)-free air, with an activation state 50% of maximum. We conclude that, at the CO(2) compensation point and high irradiance, low redox states are favored and that cyclic electron flow may be substantial. These two features may be the requirements necessary to trigger and maintain the dissipative processes in the thylakoid membrane.",1
"Harbinson, J, Foyer, C H",2
SO(2) Effect on Photosynthetic Activities of Intact Sugar Maple Leaves as Detected by Photoacoustic Spectroscopy.,0
"Short-term (4 hours) effect of different concentrations of SO(2) fumigation on in vivo photochemical activities of sugar maple (Acer saccharum Marsh.) leaves was investigated using photoacoustic spectroscopy. The relative quantum yield of O(2) evolution (ratio of O(2) signal to the photothermal signal) and photochemical energy storage are increased by 0.05 microliter per liter of SO(2). This increase is more pronounced in 5 to 7 year old saplings than in 3 month old seedlings. Both oxygen-relative quantum yield and energy storage of seedlings are inhibited by increased concentrations of SO(2) and the inhibition is concentration dependent. The inhibition is greater in seedlings than in saplings at 2 microliters per liter of SO(2), indicating the more susceptible nature of seedlings. The present study indicates a concentration dependent differential effect of SO(2) on photochemical activities of sugar maple leaves.",1
"Veeranjaneyulu, K, N'soukpoé-Kossi, C N, Leblanc, R M",2
Triacylglycerol Bioassembly in Microspore-Derived Embryos of Brassica napus L. cv Reston.,0
"Erucic acid (22:1) was chosen as a marker to study triacylglycerol (TAG) biosynthesis in a Brassica napus L. cv Reston microspore-derived (MD) embryo culture system. TAGs accumulating during embryo development exhibited changes in acyl composition similar to those observed in developing zygotic embryos of the same cv, particularly with respect to erucic and eicosenoic acids. However, MD embryos showed a much higher rate of incorporation of (14)C-erucoyl moieties into TAGs in vitro than zygotic embryos. Homogenates of early-late cotyledonary stage MD embryos (14-29 days in culture) were assessed for the ability to incorporate 22:1 and 18:1 (oleoyl) moieties into glycerolipids. In the presence of [1-(14)C]22:1-coenzyme A (CoA) and various acyl acceptors, including glycerol-3-phosphate (G-3-P), radiolabeled erucoyl moieties were rapidly incorporated into the TAG fraction, but virtually excluded from other Kennedy Pathway intermediates as well as complex polar lipids. This pattern of erucoyl incorporation was unchanged during time course experiments or upon incubation of homogenates with chemicals known to inhibit Kennedy Pathway enzymes. In marked contrast, parallel experiments conducted using [1-(14)C]18:1-CoA and G-3-P indicated that (14)C oleoyl moieties were incorporated into lyso-phosphatidic acids, phosphatidic acids, diacylglycerols, and TAGs of the Kennedy Pathway, as well as other complex polar lipids, such as phosphatidylcholines and phosphatidylethanolamines. When supplied with l-[2-(3)H(N)]G-3-P and [1-(14)C]22:1-CoA, the radiolabeled TAG pool contained both isotopes, indicating G-3-P to be a true acceptor of erucoyl moieties. Radio-high-performance liquid chromatography, argentation thin-layer chromatography/gas chromatography-mass spectrometry, and stereospecific analyses of radiolabeled TAGs indicated that 22:1 was selectively incorporated into the sn-3 position by a highly active diacylglycerol acyltransferase (DGAT; EC 2.3.1.20), while oleoyl moieties were inserted into the sn-1 and sn-2 positions. In the presence of sn-1,2-dierucin and [1-(14)C]22:1-CoA, homogenates and microsomal preparations were able to produce radiolabeled trierucin, a TAG not found endogenously in this species. A 105,000g pellet fraction contained 22:1-CoA:DGAT exhibiting the highest specific activity. The rate of 22:1-CoA:DGAT activity in vitro could more than account for the maximal rate of TAG biosynthesis observed in vivo during embryo development. In double label experiments, G-3-P was shown to stimulate the conversion of [(3)H]phosphatidylcholines to [(3)H]diacylglycerols, which subsequently acted as acceptors for (14)C erucoyl moieties. In vitro, 22:1 moieties did not enter the sn-1 position of TAGs by a postsynthetic modification or transacylation of preformed TAGs.",1
"Taylor, D C, Weber, N, Barton, D L, Underhill, E W, Hogge, L R, Weselake, R J, Pomeroy, M K",2
Metabolic bases for differences in sensitivity of two pea cultivars to sulfur dioxide.,0
"An oxidative chain reaction of sulfite initiated by the superoxide ion produced in the Mehler reaction has been implicated in the damage of plants exposed to sulfur dioxide. The toxicity of SO(2) may be alleviated by free radical scavenging systems acting to terminate this chain reaction. Hence, the relative sensitivity of plants to SO(2) toxicity could depend on differences in the responses of the levels of antioxidant metabolites and enzymes. The effect of SO(2) exposure on glutathione and ascorbic acid contents, glutathione reductase, and superoxide dismutase activities was assayed in two cultivars (Progress, Nugget) of pea (Pisum sativum L.) in which apparent photosynthesis showed a differential sensitivity to 0.8 microliter per liter SO(2) (R. Alscher, J. L. Bower, W. Zipfel [1987] J Exp Bot 38:99-108). Total and reduced glutathione increased more rapidly and to a greater extent in the insensitive Progress than in the sensitive Nugget, as did glutathione reductase activities. Superoxide dismutase activities increased significantly in Progress, whereas no such change was observed in Nugget as a result of SO(2) exposure. This increase in superoxide dismutase activity was observed at 210 minutes after 0.8 microliter per liter SO(2) concentration had been reached, in marked contrast to the increases in reduced glutathione content and glutathione reductase activity, which were apparent at the 90 minute time point. These data suggest that one basis for the relative insensitivity of the apparent photosynthesis of the pea cultivar Progress to SO(2) is the enhanced response of glutathione reductase, superoxide dismutase activities, and glutathione content.",1
"Madamanchi, N R, Alscher, R G",2
A Lipoxygenase Pathway Is Activated in Rice after Infection with the Rice Blast Fungus Magnaporthe grisea.,0
"Lipoxygenase (LOX) and lipid hydroperoxide-decomposing activity (LHDA) markedly increased in the fifth leaves of rice (Oryza sativa cv Aichiasahi) after infection with the rice blast fungus, Magnaporthe grisea. The increases in the enzyme activities were significantly higher in response to infection with an incompatible strain (race 131) compared with infection with a compatible strain (race 007) of the fungus. Using ion-exchange chromatography, we isolated three LOX activities (leaf LOX-1, -2, -3) from both uninoculated and infected leaves. The activity of leaf LOX-3, in particular, increased in the incompatible race-infected leaves. The leaf LOX-3 had a pH optimum of 5.0 and produced preferentially 13-l-hydroperoxy-9,11 (Z,E)-octadecadienoic acid (13-HPODD) from linoleic acid. 13-HPODD and 13-l-hydroxy-9,11 (Z,E)-octadecadienoic acid, one of the reaction products from 13-HPODD by LHDA, were highly inhibitory to the germination of conidia of the fungus. The present study provides correlative evidence for important roles of LOX and LHDA in the resistance response of rice against the blast fungus.",1
"Ohta, H, Shida, K, Peng, Y L, Furusawa, I, Shishiyama, J, Aibara, S, Morita, Y",2
Oxidation of External NAD(P)H by Purified Mitochondria from Fresh and Aged Red Beetroots (Beta vulgaris L.).,0
"Mitochondria were isolated from fresh beetroots (Beta vulgaris L. cvs Rubria and Nina) by differential centrifugation followed by Percoll gradient centrifugation. These purified mitochondria oxidized external NADH, although relatively slowly (20-40 versus 100-120 nanomoles oxygen per minute times milligram protein for NADH and succinate oxidation, respectively), with respiratory control ratios of two to three and ADP/O ratios of 1.2 to 1.6. NADPH was also oxidized, but even more slowly and with little or no coupling. The optimum for both NADH and NADPH oxidation by fresh beetroot mitochondria was pH 6. The rate of external NADH oxidation by isolated mitochondria was enhanced threefold during storage of the intact tubers at 10 degrees C for 12 weeks. The optimum of the induced NADH oxidation was approximately pH 6.8. Succinate and malate oxidation only increased by 30% during the same period and NADPH oxidation was constant. This is strong evidence that NADH and NADPH oxidation are catalyzed by different enzymes at least in beetroots. Activity staining of nondenaturing polyacrylamide gels with NADH and Nitro Blue Tetrazolium did not show differences in banding pattern between mitochondria isolated from fresh and stored beetroots. The induction is discussed in relation to physiological aging processes.",1
"Fredlund, K M, Rasmusson, A G, Møller, I M",2
Plant NAD(H)-Glutamate Dehydrogenase Consists of Two Subunit Polypeptides and Their Participation in the Seven Isoenzymes Occurs in an Ordered Ratio.,0
"The structure and function of NAD(H)-glutamate dehydrogenase in plants was studied by using grapevine (Vitis vinifera L. cv Sultanina) callus grown under different nitrogen sources. The enzyme consists of two subunit-polypeptides, alpha and beta, with similar antigenic properties but with different molecular mass and charge. The two polypeptides have molecular masses of 43.0 and 42.5 kilodaltons, respectively. The holoenzyme is hexameric and is resolved into seven isoenzymes by native gel electrophoresis. Two-dimensional native/SDS-PAGE revealed that the 1 and 7 isoenzymes are homohexamers and the isoenzymes 2 through 6 are hybrids of the two polypeptides following an ordered ratio. The total quantity of alpha- and beta-polypeptides and the isoenzymic pattern was altered by the exogenous nitrogen source. The sample derived from callus grown on nitrate or glutamic acid contained a slightly greater amount of beta-polypeptide and of the more cathodal isoenzymes, whereas alpha-polypeptide and the more anodal isoenzymes predominated in callus grown in the presence of either ammonium or glutamine. The anabolic reaction was correlated with the alpha- and the catabolic reaction with the beta-polypeptide; this could suggest that each isoenzyme exhibits anabolic and catabolic function of different magnitude. The isoenzymic patterns did not obey the expected binomial distribution proportions.",1
"Loulakakis, K A, Roubelakis-Angelakis, K A",2
Acid phosphatase-1 from nematode resistant tomato : isolation and characterization of its gene.,0
"Aps-1 encodes acid phosphatase-1, one of the many acid phosphatases present in tomato (Lycopersicon esculentum Mill.). Aps-1 is closely linked to Mi, a gene conferring resistance against nematodes. Thus, a clone of Aps-1 would provide access to the region of the genome containing Mi. Acid phosphatase-1 was purified from tomato suspension culture cells. Fragmentary amino acid sequences were derived from the purified protein and from its proteolytic and chemical digestion products. One of these amino acid sequences was used to design an oligodeoxyribonucleotide probe expected to hybridize to acid phosphatase-1 cDNA. This probe identified, in a cDNA library, a clone encoding the carboxyl-terminal sequence of a protein that is very similar, but not identical, to acid phosphatase-1. Using this clone, we discovered a second cDNA clone that corresponds in its carboxyl terminal sequence to acid phosphatase-1 but, surprisingly, retains sequences of an Aps-1 intron. The second cDNA clone was used to detect both a cDNA clone and a genomic clone corresponding to Aps-1. The identity of these clones was confirmed by sequence analysis and by the correlation of a restriction fragment length polymorphism with two Aps-1 alleles in a segregating tomato population. The deduced amino acid sequence of the Aps-1 open reading frame predicts a hydrophobic animoterminal signal sequence and a mature protein with a molecular weight of 25,000. The amino acid sequence of this protein has a strong similarity in size and sequence to a vegetative storage protein of soybean.",1
"Williamson, V M, Colwell, G",2
Light Intensity-Induced Changes in cab mRNA and Light Harvesting Complex II Apoprotein Levels in the Unicellular Chlorophyte Dunaliella tertiolecta.,0
"During a transition from high growth irradiance (700 micromoles quanta per square meter per second) to low growth irradiance (70 micromoles quanta per square meter per second), the unicellular marine chlorophyte Dunaliella tertiolecta Butcher increases the cellular pool size of the light-harvesting complex of photosystem II (LHC II). We showed that the increase in LHC II apoproteins and in chlorophyll content per cell is preceded by an approximately fourfold increase in cab mRNA. The increase in cab mRNA is detectable within 1.5 hours following a shift from high to low light intensity. An increase in the relative abundance of cab mRNA was also found following a shift from high light to darkness and from high light to low light in the presence of gabaculine, a chlorophyll synthesis inhibitor. However, the LHC II apoproteins did not accumulate in the latter experiments, suggesting that LHC II apoprotein synthesis is coupled to chlorophyll synthesis at or beyond translation. We propose that changes in energy balance brought about by a change in light intensity may control a regulatory factor acting to repress cab mRNA expression in high light.",1
"Laroche, J, Mortain-Bertrand, A, Falkowski, P G",2
"Influence of water deficit on maize endosperm development : enzyme activities and RNA transcripts of starch and zein synthesis, abscisic Acid, and cell division.",0
"In maize (Zea mays L.), drought during the post-pollination stage decreases kernel growth and often leads to grain yield losses. Kernels in the apical region of the ear are more severely affected than basally positioned kernels. We hypothesized that water deficit during early endosperm development might inhibit kernel growth by decreasing endosperm cell division, and that this response might be mediated by changes in endosperm abscisic acid (ABA) levels. Greenhouse-grown maize, cultivar Pioneer 3925, was subjected to water limitation from 1 to 15 days after pollination (DAP), spanning the period of endosperm cell division and induction of storage product accumulation. Water deficit decreased the number of endosperm nuclei during the treatment period; the most substantial effect was in the apical region of ears. Correspondingly, endosperm fresh weight, starch accumulation and dry mass at maturity were decreased by water limitation. Abscisic acid concentrations in endosperm were quantified by enzyme-linked immunosorbent assay. Water deficit increased ABA concentration in apical-region endosperm by four-fold compared to controls. ABA concentrations were also increased in middle and basal regions of the ear, but to a lesser extent. Two key enzymes in the starch synthesis pathway, sucrose synthase and granule-bound ADP-glucose starch synthase, and zein, the major storage protein in maize endosperm, were studied as markers of storage product synthesis. Water deficit did not affect sucrose synthase enzyme activity or RNA transcript abundance relative to total RNA. However, ADP-glucose starch synthase activity and RNA transcript abundance decreased slightly in apical-region endosperm of water-limited plants by 15 DAP, compared with well-watered controls. In contrast to starch, there was no treatment effect on the accumulation of zein, evaluated at either the polypeptide or RNA level. We conclude that under the conditions tested, the establishment of starch and zein synthetic potential in endosperm was only slightly affected by plant water deficit during the early phase of kernel growth, and that capacity for growth and starch accumulation was affected by the extent to which cell division was inhibited. Based on correlative changes in ABA concentration and cell division we suggest that ABA may play a role in inhibiting endosperm cell division during water limitation.",1
"Ober, E S, Setter, T L, Madison, J T, Thompson, J F, Shapiro, P S",2
Relevance of amadori and maillard products to seed deterioration.,0
"The possible role of Amadori and Maillard reactions in the deterioration of dry seeds was investigated using model systems and whole soybean seeds, Glycine max cv Hodgson. In model systems of glucose plus an enzyme (lysozyme), the production of Amadori products was accelerated by higher temperature and relative humidity. The reaction between glucose and lysozyme at 50 degrees C, 75% relative humidity, leads to a progressive decline in enzymatic activity. During accelerated aging of soybean seeds (40 degrees C, 100% relative humidity), a sequence is observed in which the Amadori products increase with time and then decline under conditions in which the Maillard products increase in the axes. Loss of germinability occurs at the time when the Maillard products increase in the soybean axes. These results are suggestive of a role for nonenzymic glycation in soybean seed deterioration during accelerated aging.",1
"Wettlaufer, S H, Leopold, A C",2
"Microtubules in mesophyll cells of nonacclimated and cold-acclimated spinach : visualization and responses to freezing, low temperature, and dehydration.",0
"Responses of cortical microtubules in spinach (Spinacia oleracea L. cv Bloomsdale) mesophyll cells to freezing, thawing, supercooling, and dehydration were assessed. Microtubules were visualized using a modified procedure for indirect immunofluorescence microscopy. Leaf sections of nonacclimated and cold-acclimated spinach were slowly frozen to various temperatures, fixed while frozen, and microtubules immunolabelled. Both nonacclimated and cold-acclimated cells exhibited nearly complete microtubule depolymerization after ice formation. After 1 hour thawing at 23 degrees C, microtubules in both nonacclimated and cold-acclimated cells repolymerized. With time, however, microtubules in nonacclimated cells again depolymerized. Since microtubules in cells of leaf tissue frozen slowly are subjected to dehydration as well as subzero temperatures, these stresses were applied separately and their effects on microtubules noted. Supercooling induced microtubule depolymerization in both nonacclimated and cold-acclimated cells, but to a smaller extent than did freezing. Exposing leaf sections to solutions of sorbitol (a cell wall-penetrating osmoticum) or polyethylene glycol 10,000 (a nonpenetrating osmoticum) at room temperature caused microtubule depolymerization. The effects of low temperature and dehydration are roughly additive in producing the observed microtubule responses during freezing. Only small differences in microtubule stability were resolved between nonacclimated and cold-acclimated cells.",1
"Bartolo, M E, Carter, J V",2
Influence of Water and Temperature Stress on the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination.,0
"The temperature dependence of the rate and magnitude of the reappearance of photosystem II (PSII) variable fluorescence following illumination has been used to determine plant temperature optima. The present study was designed to determine the effect of a plant's environmental history on the thermal dependency of the reappearance of PSII variable fluorescence. In addition, this study further evaluated the usefulness of this fluorescence technique in identifying plant temperature optima. Laboratory and greenhouse grown potato (Solanum tuberosum L. cv ""Norgold M"") plants had a thermal kinetic window between 15 and 25 degrees C. The minimum apparent K(m) of NADH hydroxypyruvate reductase for NADH occurred at 20 degrees C. This temperature was also the temperature providing maximal reappearance of variable fluorescence. Soybean (Glycine max [L.] Merrill cv ""Wayne"") plants had a thermal kinetic window between 15 and 30 degrees C with a minimum apparent K(m) at 25 degrees C. Maximal reappearance of variable fluorescence was seen between 20 and 30 degrees C. To determine if increasing environmental temperatures increased the temperature optimum provided from the fluorescence response curves, potato and soybean leaves from irrigated and dryland field grown plants were evaluated. Although the absolute levels of PSII variable fluorescence declined with increasing thermal stress, the temperature optimum of the dryland plants did not increase with increased exposure to elevated temperatures. Because of variability in the daily period of high temperature stress in the field, studies were initiated with tobacco plants grown in controlled environment chambers. The reappearance of PSII variable fluorescence in tobacco (Nicotiana tabacum L. cv ""Wisconsin 38"") leaves that had experienced continuous leaf temperatures of 35 degrees C for 8 days had the same 20 degrees C optima as leaves from plants grown at room temperature. The results of this study suggest that the temperature optimum for the reappearance of variable fluorescence following illumination is not altered by the plant's previous exposure to variable environmental temperatures. These findings support the usefulness of this procedure for the rapid identification of a plant's temperature optimum.",1
"Ferguson, D L, Burke, J J",2
Single rol Genes from the Agrobacterium rhizogenes T(L)-DNA Alter Some of the Cellular Responses to Auxin in Nicotiana tabacum.,0
"Two kinds of cellular responses to auxin, the hyperpolarization of protoplasts and the division of protoplast-derived cells, were compared in Nicotiana tabacum plants transformed by different T-DNA fragments of Agrobacterium rhizogenes strain A4. Using transmembrane potential difference measurements to characterize hormonal sensitivity of mesophyll protoplasts, we found a 30-fold increase in sensitivity to auxin in protoplasts transformed by the whole Ri A4 T-DNA. Furthermore, the rol genes of the Ri A4 T(L)-DNA, together or as single genes, were able to increase the sensitivity to auxin by factors up to 10(4). The different effects of the single rol genes on the sensitivity of mesophyll protoplasts to auxin, rolB being the most powerful, were consistent with their respective rhizogenic effects on leaf fragments (A Spena, T Schmülling, C Koncz, J Schell [1987] EMBO J 6: 3891-3899). No difference was seen concerning the effects of auxin on division of cells derived from normal or transformed protoplasts. These results suggest that only some cellular responses to auxin could be selectively altered by rol genes. They also show that rol-transformed tobaccos can be a model system to study auxin action in plants.",1
"Maurel, C, Barbier-Brygoo, H, Spena, A, Tempé, J, Guern, J",2
Response of soybean photosynthesis and chloroplast membrane function to canopy development and mutual shading.,0
"The effect of natural shading on photosynthetic capacity and chloroplast thylakoid membrane function was examined in soybean (Glycine max. cv Young) under field conditions using a randomized complete block design. Seedlings were thinned to 15 plants per square meter at 20 days after planting. Leaves destined to function in the shaded regions of the canopy were tagged during early expansion at 40 days after planting. To investigate the response of shaded leaves to an increase in available light, plants were removed from certain plots at 29 or 37 days after tagging to reduce the population from 15 to three plants per square meter and alter the irradiance and spectral quality of light. During the transition from a sun to a shade environment, maximum photosynthesis and chloroplast electron transport of control leaves decreased by two- to threefold over a period of 40 days followed by rapid senescence and abscission. Senescence and abscission of tagged leaves were delayed by more than 4 weeks in plots where plant populations were reduced to three plants per square meter. Maximum photosynthesis and chloroplast electron transport activity were stabilized or elevated in response to increased light when plant populations were reduced from 15 to three plants per square meter. Several chloroplast thylakoid membrane components were affected by light environment. Cytochrome f and coupling factor protein decreased by 40% and 80%, respectively, as control leaves became shaded and then increased when shaded leaves acclimated to high light. The concentrations of photosystem I (PSI) and photosystem II (PSII) reaction centers were not affected by light environment or leaf age in field grown plants, resulting in a constant PSII/PSI ratio of 1.6 +/- 0.3. Analysis of the chlorophyll-protein composition revealed a shift in chlorophyll from PSI to PSII as leaves became shaded and a reversal of this process when shaded leaves were provided with increased light. These results were in contrast to those of soybeans grown in a growth chamber where the PSII/PSI ratio as well as cytochrome f and coupling factor protein levels were dependent on growth irradiance. To summarize, light environment regulated both the photosynthetic characteristics and the timing of senescence in soybean leaves grown under field conditions.",1
"Burkey, K O, Wells, R",2
Spatial Distribution of Flavonoid Conjugates in Relation to Glucosyltransferase and Sulfotransferase Activities in Flaveria bidentis.,0
"The spatial distribution of sulfated and glucosylated flavonols as well as of the enzymes involved in the later steps of their biosynthesis, sulfotransferase and glucosyltransferase, were investigated in the shoots of Flaveria bidentis. The highest amounts of both types of flavonoid conjugates (as micromole per gram fresh weight) and the highest activities of their enzymes (as picokat per milligram) were detected in the terminal bud and the first pair of leaves. Sulfotransferase activity was also highest in the upper stem segments and in the basal section of the leaves. Western blot analysis of protein extracts showed that variations in sulfotransferase activity in different tissues correlate well with the amounts of immunodetected enzyme protein. These results were discussed in relation to the possible role of conjugated flavonoids in plant growth.",1
"Hannoufa, A, Varin, L, Ibrahim, R K",2
Diffusion and Electric Mobility of Ions within Isolated Cuticles of Citrus aurantium: Steady-State and Equilibrium Values.,0
"We report a new method for measuring cation and anion permeability across cuticles of sour orange, Citrus aurantium, leaves. The method requires the measurement of two electrical parameters: the diffusion potential arising when the two sides of the cuticle are bathed in unequal concentrations of a Cl(-) salt; and the electrical conductance of the cuticle measured at a salt concentration equal to the average of that used in the diffusion-potential measurement. The permeabilities of H(+), Li(+), Na(+), K(+), and Cs(+) ranged from 2 x 10(-8) to 0.6 x 10(-8) meters per second when cuticles were bathed in 2 moles per cubic meter Cl(-) salts. The permeability of Cl(-) was 3 x 10(-9) meters per second. The permeability of Li(+), Na(+), and K(+) was about five times less when measured in 500 moles per cubic meter Cl(-) salts. We also report an asymmetry in cuticle-conductance values depending on the magnitude and the direction of current flow. The asymmetry disappears at low current-pulse magnitude and increases linearly with the magnitude of the current pulse. This phenomenon is explained in terms of transport-number effects in a bilayer model of the cuticle. Conductance is not augmented by current carried by exchangeable cations in cuticles; conductance is rate limited by the outer waxy layer of the cuticle.",1
"Tyree, M T, Wescott, C R, Tabor, C A",2
Activity and accumulation of cell division-promoting phenolics in tobacco tissue cultures.,0
"Dehydrodiconiferyl alcohol glucosides (DCGs) are derivatives of the phenylpropanoid pathway that have been isolated from Catharansus roseus L. (Vinca rosea) crown gall tumors. Fractions containing purified DCGs have been shown previously to promote the growth of cytokinin-requiring tissues of tobacco in the absence of exogenous cytokinins. In this study, we utilized synthetic DCG isomers to confirm the cell division-promoting activity of DCG isomers A and B and show that they neither promote shoot meristem initiation on Nicotiana tabacum L., cv Havana 425, leaf explants nor induce betacyanin synthesis in amaranth seedlings. Analysis of cultured tobacco pith tissue demonstrated that DCG accumulation was stimulated by cytokinin treatment and correlated with cytokinin-induced cell division. Thus, the accumulation of metabolites that could replace cytokinin in cell division bioassays is stimulated by cytokinins. These data support the model that DCGs are a component of a cytokinin-mediated regulatory circuit controlling cell division.",1
"Teutonico, R A, Dudley, M W, Orr, J D, Lynn, D G, Binns, A N",2
Effects of Mild Water Stress and Diurnal Changes in Temperature and Humidity on the Stable Oxygen and Hydrogen Isotopic Composition of Leaf Water in Cornus stolonifera L.,0
"In this paper we make comparisons between the observed stable isotopic composition of leaf water and the predictions of the Craig-Gordon model of isotopic enrichment when plants (Cornus stolonifera L.) were exposed to natural, diurnal changes in temperature and humidity in a glasshouse. In addition, we determined the effects of mild water stress on the isotopic composition of leaf water. The model predicted different patterns of diurnal change for the oxygen and hydrogen isotopic composition of leaf water. The observed leaf water isotopic composition followed qualitatively similar patterns of diurnal change to those predicted by the model. At midday, however, the model always predicted a higher degree of heavy isotope enrichment than was actually observed in leaves. There was no effect of mild water stress on the hydrogen isotopic composition of leaf water. For the oxygen isotopic composition of leaf water, there was either no significant difference between control and water-stressed plants or the stressed plants had lower delta(18)O values, despite the enriched stem water isotopic composition observed for the stressed plants.",1
"Flanagan, L B, Ehleringer, J R",2
"Influence of Ozone on the Stable Carbon Isotope Composition, deltaC, of Leaves and Grain of Spring Wheat (Triticum aestivum L.).",0
"The relative composition of stable carbon isotopes, delta(13)C, was determined in flag leaves and grain of spring wheat (Triticum aestivum L. cv Albis) grown in open-top field fumigation chambers and exposed to different O(3) levels during the growing season. The aim of the study was to establish exposure-response relationships for the radiation-weighted seasonal mean O(3) concentration and delta(13)C (relative deviation of the (13)C/(12)C ratio) values of the two plant parts. Samples were collected at harvest in 1986, 1987, and 1988. With increasing O(3) concentration, delta(13)C values increased (became less negative) proportionally. Year to year delta(13)C differences at equivalent O(3) concentrations were small. The shift in delta(13)C caused by O(3) was more pronounced in grain than in leaves. According to models of (13)C discrimination in C(3) plants, these results indicate increasing limitation of photosynthesis by CO(2) diffusion relative to limitation by carboxylation with increasing O(3) exposure. This conclusion is not in agreement with results from gas exchange analysis. Water use efficiency in green flag leaves tended to decrease with increasing O(3), indicating a dominating effect of O(3) on CO(2) carboxylation.",1
"Saurer, M, Fuhrer, J, Siegenthaler, U",2
Regulation of light-induced chloroplast transcription and translation in eight-day-old dark-grown barley seedlings.,0
"Plastid transcription and translation are light-activated in 8-day-old dark-grown barley (Hordeum vulgare L.) seedlings. Pretreatment of dark-grown seedlings with cycloheximide (inhibitor of cytoplasmic protein synthesis) abolished the activation of rbcL, psbA, and psaA-B transcription by light. In contrast, inhibition of plastid protein synthesis by chloramphenicol stimulated light-activated transcription of rbcL, psbA, and psaA-B. Light-induced transcription of the plastid genome occurred normally in the chlorophyll-deficient mutant xan-J(64). These results suggest that although the light-induced activation of plastid transcription is modulated by cytoplasmic and organellar protein synthesis, transcriptional activation is not dependent on the absorption of light by protochlorophyllide or the attainment of photosynthetic competence. In addition, plastid translation increased dramatically when 8-day-old dark-grown seedlings were illuminated and activation was dependent on cytoplasmic protein synthesis. Blockage of light-activated plastid transcription by Tagetin treatment (inhibitor of plastid RNA polymerase) did not attenuate the activation of plastid translation by light. These results suggest that while light simultaneously activates plastid transcription and translation, the rapid burst in plastid protein synthesis is due mainly to cytoplasmic-derived changes that regulate the rate of translation of pre-existing mRNAs.",1
"Klein, R R",2
Germin-Like Polypeptides Increase in Barley Roots during Salt Stress.,0
"The 26 kilodalton, isoelectric point 6.3 and 6.5 (Gs1 and Gs2) polypeptides that increase in barley (Hordeum vulgare L.) roots during salt stress were isolated and identified. Both Gs1 and Gs2 had high sequence similarity to germin, a protein that increases significantly in germinating wheat seeds. Like germin, Gs1 and Gs2 were resistant to proteases and were glycosylated. Immunoblots were probed with antibodies to Gs1 and Gs2 to determine the distribution of these polypeptides among organs and cell-free fractions. Gs1 and Gs2 were present in roots and coleoptiles, but absent from leaves. In roots, Gs1 and Gs2 were present in the mature region, but not the tip. Gs1 and Gs2 increased in roots, but decreased in coleoptiles in response to salt stress. Gs1 and Gs2 were distributed among the soluble, microsomal, and cell wall fractions of roots, but the majority of Gs1 and Gs2 was present in the soluble fraction. Although Gs1 and Gs2 were heat stable, their synthesis was not affected by abscisic acid treatment. Gs2 accumulated during abscisic acid treatment, whereas Gs1 did not. However, a 25.5 kilodalton, isoelectric point 6.1 polypeptide that was immunologically related to Gs1 did accumulate with abscisic acid treatment.",1
"Hurkman, W J, Tao, H P, Tanaka, C K",2
Thylakoid Organization in the Chromophyte Alga Ochromonas danica: Isolation and Characterization of a New Pigment-Protein Complex.,0
"This report describes the isolation and preliminary characterization of a new pigment-protein complex from the chromophyte alga, Ochromonas danica. The pigment-protein complex was obtained by extracting a thylakoid membrane preparation with the zwitterionic detergent lauryldimethylamine oxide followed by ultracentrifugation on sucrose gradients. The pigment-protein complex has been characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, and low temperature (77 Kelvin) chlorophyll fluorescence spectroscopy. A polypeptide with a monomeric molecular weight of 31,000 as determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis was the major constituent of this pigment-protein complex. The major pigment in this complex was chlorophyll a, although an as yet unidentified carotenoid was also present. There was no evidence for the presence of chlorophyll c.",1
"Gibbs, P B, Biggins, J",2
Characterization of the Arrest in Anther Development Associated with Gibberellin Deficiency of the gib-1 Mutant of Tomato.,0
"The role of gibberellins in flower bud development was investigated by studying the gib-1 mutant of tomato, Lycopersicon esculentum. This gibberellin-deficient mutant initiates flower buds, but floral development is not completed unless the mutant is treated with gibberellin. Treatment with other plant growth regulators does not induce normal flower development. Development of gib-1 flower buds, as measured by progress toward anthesis, ceases at a bud length of 2.5 millimeters; however, increase in size of the bud continues. Buds between 2.5 and 3.7 millimeters are developmentally arrested but still are capable of developing normally after treatment with gibberellic acid. Anthers of these developmentally arrested buds contain pollen mother cells that are in the G1 phase of premeiotic interphase. Following treatment of developmentally arrested buds with gibberellic acid, premeiotic DNA synthesis and callose accumulation in pollen mother cells are evident by 48 hours posttreatment, and within 66 hours, prophase I of meiosis- and meiosis-related changes in tapetum development are observable.",1
"Jacobsen, S E, Olszewski, N E",2
The epidermis of the pea epicotyl is not a unique target tissue for auxin-induced growth.,0
"Previous research has suggested that the epidermis of dicotyledonous stems is the primary site of auxin action in elongation growth.  We show for pea (Pisum sativum L.) epicotyl sections that this hypothesis is incorrect.  In buffer (pH 6.5), sections from which the outer cell layers were removed (peeled) elongated slowly and to the same extent as intact sections.  Addition of 10 micromolar indoleacetic acid to this incubation medium caused peeled sections to grow to the same extent and with the same kinetics as auxin-treated nonpeeled sections.  This indicates that both epidermis and cortical tissues have the ability to respond rapidly to auxin and that the epidermis is not the sole site of auxin action in dicotyledonous stems.  Previous reports that peeled pea sections respond poorly to auxin may have resulted from an acid extension of these sections due to the use of distilled water as the incubation medium.",1
"Rayle, D L, Nowbar, S, Cleland, R E, Rayle, D L, Cleland, R E",2
Overproduction of petunia chloroplastic copper/zinc superoxide dismutase does not confer ozone tolerance in transgenic tobacco.,0
"Transgenic tobacco (Nicotiana tabacum cultivar W38) plants that overproduce petunia chloroplastic Cu/Zn superoxide dismutase were exposed to ozone dosages that injure control tobacco plants. Based on foliar injury ratings, there was no consistent protection provided to the transgenic plants. These data indicate that an increase in the chloroplastic Cu/Zn superoxide dismutase alone is not sufficient to reduce ozone toxicity.",1
"Pitcher, L H, Brennan, E, Hurley, A, Dunsmuir, P, Tepperman, J M, Zilinskas, B A",2
Gibberellic Acid Regulates the Level of a BiP Cognate in the Endoplasmic Reticulum of Barley Aleurone Cells.,0
The isolation of a 70-kilodalton protein from barley (Hordeum vulgare L.) aleurone layers that cross-reacts with an antibody against yeast binding protein (BiP) is reported. Endoplasmic reticulum isolated from aleurone layers treated with gibberellic acid contain much higher levels of the BiP cognate than do membranes isolated from layers treated with abscisic acid.,1
"Jones, R L, Bush, D S",2
Expression of a fungal sesquiterpene cyclase gene in transgenic tobacco.,0
The complete coding sequence for the trichodiene synthase gene from Fusarium sporotrichioides was introduced into tobacco (Nicotiana tabacum) under the regulation of the cauliflower mosiac virus 35S promoter. Expression of trichodiene synthase was demonstrated in the leaves of transformed plants. Leaf homogenates incubated with [(3)H]farnesyl pyrophosphate produced trichodiene as a major product. Trichodiene was detected in the leaves of a transformed plant at a level of 5 to 10 nanograms per gram fresh weight. The introduction of a fungal sesquiterpene cyclase gene into tobacco has resulted in the expression of an active enzyme and the accumulation of low levels of its sesquiterpenoid product.,1
"Hohn, T M, Ohlrogge, J B",2
Fractionation of Carbon Isotopes during Biogenesis of Atmospheric Isoprene.,0
"The stable carbon isotope composition of isoprene emitted from leaves of red oak (Quercus rubra L.) was measured. Isoprene was depleted in (13)C relative to carbon recently fixed by photosynthesis. The difference in isotope composition between recently fixed carbon and emitted isoprene was independent of the isotopic composition of the source CO(2). beta-Carotene, an isoprenoid plant constituent, was depleted in (13)C relative to whole leaf carbon to the same degree as isoprene, but fatty acids were more depleted. Isoprene emitted from leaves fed abscisic acid was much less depleted in (13)C than was isoprene emitted from unstressed leaves. We conclude that isoprene is made from an isoprenoid precursor that is derived from acetyl-CoA made from recent photosynthate. The carbon isotope composition of isoprene in the atmosphere is likely to be slightly more negative (less (13)C) than C(3) plant material but when plants are stressed the isotopic composition could vary.",1
"Sharkey, T D, Loreto, F, Delwiche, C F, Treichel, I W",2
Small light-harvesting antenna does not protect from photoinhibition.,0
"High-light-induced decrease in photosystem II (PSII) electron transfer activity was studied in high- and low-light-grown pumpkin (Cucurbita pepo L.) plants in vivo and in vitro. The PSII light-harvesting antenna of the low-light leaves was estimated to be twice as big as that of the high-light leaves. The low-light leaves were more susceptible to photoinhibition in vivo. However, thylakoids isolated from these two plant materials were equally sensitive to photoinhibition when illuminated in the absence of external electron acceptors. Only the intensity of the photoinhibitory light and the chlorophyll concentration of the sample, not the size of the light-harvesting antenna, determined the rate of PSII photoinhibition in vitro. Because excitation of the reaction center and not only the antenna chlorophylls is a prerequisite for photoinhibition of PSII activity, independence of photoinhibition on antenna size provides support for the hypothesis (Schatz EH, Brock H, Holzwarth AR [1988] Biophys J 54: 397-405) that the excitations of the antenna chlorophylls are in equilibrium with the excitations of the reaction centers. Better tolerance of the high-light leaves in vivo was due to a more active repair process and more powerful protective mechanisms, including photosynthesis. Apparently, some protective mechanism of the high-light-grown plants is at least partially active at low temperature. The protective mechanisms do not appear to function in vitro.",1
"Tyystjärvi, E, Koivuniemi, A, Kettunen, R, Aro, E M",2
Enhanced Photosynthesis and Stomatal Conductance of Pima Cotton (Gossypium barbadense L.) Bred for Increased Yield.,0
"Yield of Pima cotton (Gossypium barbadense L.) has tripled over the last 40 years with the development of new cultivars. Six genetic lines representing successive stages in the breeding process (one primitive noncultivated accession, four cultivars with release dates from 1949 to 1983, and one unreleased breeding line) were grown in a greenhouse, and their gas exchange properties were compared. Among the cultivated types, genetic advances were closely associated with increasing single-leaf photosynthetic rate (A) and stomatal conductance (g(s)), especially in the morning. The A and g(s) of the primitive line approached those of the cultivated types early in the morning, but were much lower for the rest of the day. In both morning and afternoon, A was correlated with g(s) across genotypes but was not correlated with leaf thickness, concentrations of chlorophyll or starch, or intercellular CO(2) concentration (c(i)). In the oldest cultivar, the relationship of A to c(i) did not change between morning and afternoon. In the two most recent lines, the slopes of the A:c(i) curves at limiting c(i) exceeded that of the oldest cultivar by 25 to 50% in the morning, but the differences were much smaller in the afternoon. The maximum A of the newer lines at high c(i) exceeded that of the oldest cultivar only in the morning. Breeding for increasing yield has enhanced the photosynthetic capacity and stomatal conductance of Pima cotton and altered the diurnal regulation of photosynthesis.",1
"Cornish, K, Radin, J W, Turcotte, E L, Lu, Z, Zeiger, E",2
Acclimation of CO(2) Assimilation in Cotton Leaves to Water Stress and Salinity.,0
"Cotton (Gossypium hirsutum L. cv Acala SJ2) plants were exposed to three levels of osmotic or matric potentials. The first was obtained by salt and the latter by withholding irrigation water. Plants were acclimated to the two stress types by reducing the rate of stress development by a factor of 4 to 7. CO(2) assimilation was then determined on acclimated and nonacclimated plants. The decrease of CO(2) assimilation in salinity-exposed plants was significantly less in acclimated as compared with nonacclimated plants. Such a difference was not found under water stress at ambient CO(2) partial pressure. The slopes of net CO(2) assimilation versus intercellular CO(2) partial pressure, for the initial linear portion of this relationship, were increased in plants acclimated to salinity of -0.3 and -0.6 megapascal but not in nonacclimated plants. In plants acclimated to water stress, this change in slopes was not significant. Leaf osmotic potential was reduced much more in acclimated than in nonacclimated plants, resulting in turgor maintenance even at -0.9 megapascal. In nonacclimated plants, turgor pressure reached zero at approximately -0.5 megapascal. The accumulation of Cl(-) and Na(+) in the salinity-acclimated plants fully accounted for the decrease in leaf osmotic potential. The rise in concentration of organic solutes comprised only 5% of the total increase in solutes in salinity-acclimated and 10 to 20% in water-stress-acclimated plants. This acclimation was interpreted in light of the higher protein content per unit leaf area and the enhanced ribulose bisphosphate carboxylase activity. At saturating CO(2) partial pressure, the declined inhibition in CO(2) assimilation of stress-acclimated plants was found for both salinity and water stress.",1
"Plaut, Z, Federman, E",2
Chemical characterization of stress-induced vascular coating in tomato.,0
"Indirect evidence suggests that vascular coatings formed by plants in response to stress consist of suberin-like substances containing lipid and phenolic compounds. To provide more direct chemical evidence that coatings are suberin, we used a natural pathogen, Verticillium albo-atrum, or a stress-responsive hormone, abscisic acid, to induce coating in two isolines of tomato (Lycopersicon esculentum L. cultivar Craigella) that are resistant or susceptible to the pathogen. Using treated petioles that had been monitored cytologically, chemical depolymerization followed by combined gas-liquid chromatography-mass spectrometry analysis of alkane-alpha,omega-diol levels confirmed the presence of suberin after induction of coating and showed quantitative differences between the isolines that correlated with cytological measurements of the coating response. Northern analysis of suberization-associated anionic peroxidase mRNA showed corresponding increases, and tissue blot analysis further indicated that induction of the mRNA was localized in the responding vascular bundles, as determined by suberin histochemistry. Taken together, these results provide chemical evidence that the coatings are mainly suberin.",1
"Robb, J, Lee, S W, Mohan, R, Kolattukudy, P E",2
Fe-Chelate Reductase Activity of Plasma Membranes Isolated from Tomato (Lycopersicon esculentum Mill.) Roots : Comparison of Enzymes from Fe-Deficient and Fe-Sufficient Roots.,0
"Reduction of Fe(3+) to Fe(2+) is a prerequisite for Fe uptake by tomato roots. Ferric chelate reductase activity in plasma membranes (PM) isolated from roots of both iron-sufficient (+Fe) and iron-deficient (-Fe) tomatoes (Lycopersicon esculentum Mill.) was measured as NADH-dependent ferric citrate reductase and exhibited simple Michaelis-Menten kinetics for the substrates, NADH and Fe(3+)(citrate(3-))(2). NADH and Fe(3+)(citrate(3-))(2)K(m) values for reductase in PM from +Fe and -Fe tomato roots were similar, whereas V(max) values were two- to threefold higher for reductase from -Fe tomatoes. The pH optimum for Fe-chelate reductase was 6.5. Fe-chelate reductases from -Fe and +Fe tomato roots were equally sensitive to several triazine dyes. Reductase was solubilized with n-octyl beta-d-glucopyranoside and electrophoresed in nondenaturing isoelectric focusing gels. Three bands, with isoelectric points of 5.5 to 6.2, were resolved by enzyme activity staining of electrofocused PM proteins isolated from +Fe and -Fe tomato roots. Activity staining was particularly enhanced in the isoelectric point 5.5 and 6.2 bands solubilized from -Fe PM. We conclude that PM from roots of +Fe and -Fe plants contain Fe-chelate reductases with similar characteristics. The response to iron deficiency stress likely involves increased expression of constitutive Fe-chelate reductase isoforms in expanding epidermal root PM.",1
"Holden, M J, Luster, D G, Chaney, R L, Buckhout, T J, Robinson, C",2
Induction of Senescence-Like Deterioration of Microsomal Membranes from Cauliflower by Free Radicals Generated during Gamma Irradiation.,0
"Membrane deterioration differs in aging and senescent tissues. Involvement of free radicals in the process is generally recognized. Little is known about the physiological effects of gamma irradiation on plant tissues. Degradation of microsomal membranes by the action of free radicals, generated in vivo by gamma rays, was investigated. Cauliflower florets (Brassica oleracea L., Botrytis group) were exposed to 2 or 4 kiloGray of gamma radiation. Membrane deterioration was assessed during 8-day storage at 13 degrees C. Some senescence was indicated in nonirradiated controls by a parallel depletion of lipid phosphate and protein. Irradiation caused an immediate increase in tissue electrolyte leakage and a small increase in the free fatty acid content of membranes. In irradiated samples, leakage of electrolytes and the ratios of sterol to phospholipid and of free fatty acid to phospholipid increased with storage. During this period, membrane protein was progressively lost and the lipid phosphate-to-protein ratio increased markedly. Polyunsaturated fatty acids were selectively depleted from the free fatty acid fraction for all treatments, suggesting lipoxygenase activity. No change in lipid saturation was observed in the polar lipid fraction. The results suggest an enzyme-catalyzed senescence-like membrane deterioration, probably induced by chemical deesterification of phospholipids by free radicals generated during irradiation.",1
"Voisine, R, Vézina, L P, Willemot, C",2
Tracing cell wall biogenesis in intact cells and plants : selective turnover and alteration of soluble and cell wall polysaccharides in grasses.,0
"Cells of proso millet (Panicum miliaceum L. cv Abarr) in liquid culture and leaves of maize seedlings (Zea mays L. cv LH51 x LH1131) readily incorporated d-[U-(14)C]glucose and l-[U-(14)C]arabinose into soluble and cell wall polymers. Radioactivity from arabinose accumulated selectively in polymers containing arabinose or xylose because a salvage pathway and C-4 epimerase yield both nucleotide-pentoses. On the other hand, radioactivity from glucose was found in all sugars and polymers. Pulse-chase experiments with proso millet cells in liquid culture demonstrated turnover of buffer soluble polymers within minutes and accumulation of radioactive polymers in the cell wall. In leaves of maize seedlings, radioactive polymers accumulated quickly and peaked 30 hours after the pulse then decreased slowly for the remaining time course. During further growth of the seedlings, radioactive polymers became more tenaciously bound in the cell wall. Sugars were constantly recycled from turnover of polysaccharides of the cell wall. Arabinose, hydrolyzed from glucuronoarabinoxylans, and glucose, hydrolyzed from mixed-linkage (1-->3, 1-->4)beta-d-glucans, constituted most of the sugar participating in turnover. Arabinogalactans were a large portion of the buffer soluble (cytoplasmic) polymers of both proso millet cells and maize seedlings, and these polymers also exhibited turnover. Our results indicate that the primary cell wall is not simply a sink for various polysaccharide components, but rather a dynamic compartment exhibiting long-term reorganization by turnover and alteration of specific polymers during development.",1
"Gibeaut, D M, Carpita, N C",2
NaCl Regulation of Tonoplast ATPase 70-Kilodalton Subunit mRNA in Tobacco Cells.,0
A cDNA clone encoding the 70-kilodalton subunit of the tobacco (Nicotiana tabacum var Wisconsin 38) tonoplast ATPase has been isolated. The 1.656 kilobase insert contains only open reading frame that represents more than 80% of the carrot cDNA coding region. The deduced amino acid sequence has greater than 95% sequence identity with the homologous carrot sequence. A transcript of approximately 2.7 kilobase was detected on Northern blots of tobacco poly(A)(+) selected or total RNA using labeled probe produced from this clone. The gene was expressed throughout the growth cycle in unadapted and 428 millimolar NaCl adapted cells. Transcription of the 70-kilodalton subunit gene or mRNA stability was induced by short-term NaCl treatment in NaCl adapted cells or by abscisic acid treatment in both adapted and unadapted cells. Southern analysis indicated the presence of up to four genes encoding the 70-kilodalton subunit.,1
"Narasimhan, M L, Binzel, M L, Perez-Prat, E, Chen, Z, Nelson, D E, Singh, N K, Bressan, R A, Hasegawa, P M",2
"Changes in beta-1,3-Glucan Synthase Activity in Developing Lima Bean Plants.",0
"A plasma membrane-enriched fraction was isolated from various tissues of developing lima bean seedlings, Phaseolus lunatus var Cangreen, to study beta-1,3-glucan synthase activity changes. All tissues contained an active beta-glucan synthase, including the cotyledons that will be senescent in mature lima bean plants. Young primary leaves exhibited a very active beta-glucan synthase; but this activity dropped markedly, about fivefold, as the leaves gained weight and became photosynthetic. Some tissues, such as the hypocotyl and young stem, exhibited an increase in beta-glucan synthase activity as the tissues were growing and a decrease as the growth rate slowed. Roots exhibited a high activity early in development that only decreased slightly, about 30%, as root growth increased. Surprisingly the senescent cotyledons contained an activity equivalent to some other tissues that was maintained over our measurement time of 21 days. Perhaps this callose synthesis activity is related to translocation processes as the cotyledons transfer their reserves to the growing seedling. We concluded that beta-glucan synthase was not a good indicator of sink strength in these lima bean tissues. The plasma membrane fractions also were tested for other enzymes that might be present because an electron microscope study revealed a low contamination by other types of membranes. The membrane fractions had low but detectable activities of sucrose synthase, UDPglucose pyrophosphorylase, UDPase, alkaline invertase, and a general phosphatase; but these enzymes exhibited no consistent pattern(s) of activity change with plant development.",1
"Dugger, W M, Palmer, R L, Black, C C",2
Postanoxic Injury in Soybean (Glycine max) Seedlings.,0
"The postanoxic injury, also known as reperfusion injury, is associated with the returning of anoxic tissues to normal atmosphere. Using tetrazolium chloride staining, ATP content, and seedling growth rate as indicators, we found that postanoxic injuries in soybean (Glycine max) seedlings were more severe after 1 and 2 hours of anoxia than after longer anoxic durations (3 to 5 hours). Anaerobic incubation of root tips in the presence of 100 mm ascorbate, an antioxidant and free radical-scavenging compound, alleviated the postanoxic injury associated with the short durations of anoxia. Extracts from soybean seedling roots returned to air from 1 hour of anoxia had an elevated capacity to produce superoxide radicals over extracts from postanoxic roots stressed for 3 or 5 hours. Activity of superoxide dismutase in soybean roots returned to air from 1 and 2 hours of anoxia was 30 to 50% lower than activities in roots returned to air from 5 hours of anoxia. Superoxide dismutase-specific transcripts were also lower in postanoxic roots stressed for 1 hour than in roots stressed for longer anoxic durations. The evidence suggested that the postanoxic injury of soybean roots after a short anoxic stress was associated with an increased superoxide radicals production capacity coupled with a reduced superoxide dismutase activity. Periods of anoxia of at least 3 hours were necessary for soybean seedlings to develop the ability to cope with postanoxic stress.",1
"Vantoai, T T, Bolles, C S",2
The k/na selectivity of a cation channel in the plasma membrane of root cells does not differ in salt-tolerant and salt-sensitive wheat species.,0
"The characteristics of cation outward rectifier channels were studied in protoplasts from wheat root (Triticum aestivum L. and Triticum turgidum L.) cells using the patch clamp technique. The cation outward rectifier channels were voltage-dependent with a single channel conductance of 32 +/- 1 picosiemens in 100 millimolar KCl. Whole-cell currents were dominated by the activity of the cation outward rectifiers. The time- and voltage-dependence of these currents was accounted for by the summed behavior of individual channels recorded from outside-out detached patches. The K(+)/Na(+) permeability ratio of these channels was measured in a salt-sensitive and salt-tolerant genotype of wheat that differ in rates of Na(+) accumulation, using a voltage ramp protocol on protoplasts in the whole-cell configuration. Permeability ratios were calculated from shifts in reversal potentials following ion substitutions. There were no significant differences in the K(+)/Na(+) permeability ratios of these channels in root cells from either of the two genotypes tested. The permeability ratio for K(+)/Cl(-) was greater than 50:1. The K(+)/Na(+) permeability ratio averaged 30:1, which is two to four times more selective than the same type of channel in guard cells and suspension culture cells. Lowering the Ca(2+) concentration in the bath solution to 0.1 millimolar in the presence of 100 millimolar Na(+) had no significant effect on the K(+)/Na(+) permeability ratios of the channel. It seems unlikely that the mechanism of salt tolerance in wheat is based on differences in the K(+)/Na(+) selectivity of these channels.",1
"Schachtman, D P, Tyerman, S D, Terry, B R",2
"Characterization of Satellite DNA from Three Marine Dinoflagellates (Dinophyceae): Glenodinium sp. and Two Members of the Toxic Genus, Protogonyaulax.",0
"Using CsCl-Hoechst dye or CsCl-ethidium bromide gradients, satellite and nuclear DNAs were separated and characterized in three marine dinoflagellates: Glenodinium sp., and two toxic dinoflagellates, Protogonyaulax tamarensis and Protogonyaulax catenella. In all three dinoflagellates, the lowest density fraction, satellite DNA(1), hybridized to chloroplast genes derived from terrestrial plants and/or other algae. Dinoflagellate chloroplast DNAs exhibited molecular sizes of 114 to 125 kilobase pairs, which is consistent with plastid sizes determined for other chromophytic algae (120-150 kilobase pairs). Mitochondrial DNA was not resolved from nuclear DNA in this system. Two additional satellite DNAs, satellite DNA(2) and satellite DNA(3), recovered from P. tamarensis and P. catenella were similar to one another, both within and between species, when characterized by restriction enzyme analysis. These satellites were 85 to 95 kilobase pairs in size, and exhibited restriction fragments that hybridized to yeast nuclear ribosomal RNA genes. Restriction enzyme analyses and DNA hybridization studies of cpDNA document that the two Protogonyaulax isolates are not evolutionarily identical.",1
"Boczar, B A, Liston, J, Cattolico, R A",2
Differential effects of elicitors on the viability of rice suspension cells.,0
"We have compared the effects of two elicitors of defense-related processes on rice (Oryza sativa L.) suspension cells. Both chitosan and salicylic acid induced the accumulation of extracellular chitinase, thickening of the cell wall, and a variety of cytological changes in treated cells. Chitosan also induced the production of a brown pigment and cell death. Both of these effects depended on the availability of reactive oxygen species, because the damage was greatly reduced by either catalase or free-radical scavengers. Pretreating cells with salicylic acid also protected them from the cytotoxic effects of chitosan. This type of induced tolerance persisted when salicylic acid was removed and was not simply due to the release of extracellular substances, because salicylic acid-treated cells did not protect untreated cells from chitosan-induced death. Salicylic acid also stimulated the production of a 10-kilodalton subtilisin inhibitor that was not produced by chitosan-treated cells. Most of these changes are associated with the hypersensitive response of many plant species, including monocotyledons, and may serve as an in vitro model for investigating the biochemistry of some diseases.",1
"Masuta, C, Van den Bulcke, M, Bauw, G, Van Montagu, M, Caplan, A B",2
"Fluoride-Induced Inhibition of Starch Biosynthesis in Developing Potato, Solanum tuberosum L., Tubers Is Associated with Pyrophosphate Accumulation.",0
"Pretreatment of discs excised from developing tubers of potato (Solanum tuberosum L.) with 10 millimolar sodium fluoride induced a transient increase in 3-phosphoglycerate content. This was followed by increases in triose-phosphate, fructose 1,6-bisphosphate and hexose-phosphate (glucose 6-phosphate + fructose 6-phosphate + glucose 1-phosphate). The effect of fluoride is attributed to an inhibition of glycolysis and a stimulation of triose-phosphate recycling (the latter confirmed by the pattern of (13)C-labeling [NMR] in sucrose when tissue was supplied with [2-(13)C]glucose). Fluoride inhibited the incorporation of [U-(14)C] glucose, [U-(14)C]sucrose, [U-(14)C]glucose 1-phosphate, and [U-(14)C] glycerol into starch. The incorporation of [U-(14)C]ADPglucose was unaffected. Inhibition of starch biosynthesis was accompanied by an almost proportional increase in the incorporation of (14)C into sucrose. The inhibition of starch synthesis was accompanied by a 10-fold increase in tissue pyrophosphate (PPi) content. Although the subcellular localization of PPi was not determined, a hypothesis is presented that argues that the PPi accumulates in the amyloplast due to inhibition of alkaline inorganic pyrophosphatase by fluoride ions.",1
"Viola, R, Davies, H V",2
Transport of arginine and aspartic Acid into isolated barley mesophyll vacuoles.,0
"The transport of arginine into isolated barley (Hordeum vulgare L.) mesophyll vacuoles was investigated. In the absence of ATP, arginine uptake was saturable with a K(m) of 0.3 to 0.4 millimolar. Positively charged amino acids inhibited arginine uptake, lysine being most potent with a K(i) of 1.2 millimolar. In the presence of free ATP, but not of its Mg-complex, uptake of arginine was drastically enhanced and a linear function of its concentration up to 16 millimolar. The nonhydrolyzable adenylyl imidodiphosphate, but no other nucleotide tested, could substitute for ATP. Therefore, it is suggested that this process does not require energy and does not involve the tonoplast ATPase. The ATP-dependent arginine uptake was strongly inhibited by p-chloromercuriphenylsulfonic acid. Furthermore, hydrophobic amino acids were inhibitory (I(50) phenylalanine 1 millimolar). Similar characteristics were observed for the uptake of aspartic acid. However, rates of ATP-stimulated aspartic acid transport were 10-fold lower as compared to arginine transport. Uptake of aspartate in the absence of ATP was negligible.",1
"Martinoia, E, Thume, M, Vogt, E, Rentsch, D, Dietz, K J",2
Two Apoplastic alpha-Amylases Are Induced in Tobacco by Virus Infection.,0
"alpha-Amylase activity (EC 3.2. 1.1) is greatly increased in leaves of tobacco (Nicotiana tabacum L. cv Samsun NN) infected with tobacco mosaic virus (TMV). The kinetics of enzyme induction during the hypersensitive reaction resemble those of other hydrolases known to be pathogenesis-related proteins of tobacco. Two alpha-amylases were purified from TMV-infected leaves and shown to have features in common with well-characterized pathogenesis-related proteins: they are acidic monomers that can be separated upon electrophoresis on basic native gels, and they are found in the apoplastic compartment of the cell. This extra-cellular localization was demonstrated by comparing the alpha-amylase partition between the intercellular wash fluid and the cell extract with that of proteins of known cellular compartmentalization. These data indicate an active secretion of both alpha-amylases produced in tobacco upon TMV infection.",1
"Heitz, T, Geoffroy, P, Fritig, B, Legrand, M",2
"Overexpression of Acetohydroxyacid Synthase from Arabidopsis as an Inducible Fusion Protein in Escherichia coli: Production of Polyclonal Antibodies, and Immunological Characterization of the Enzyme.",0
"Acetohydroxyacid synthase (AHAS, EC 4.1.3.18) is the first enzyme unique to the biosynthesis of valine, leucine, and isoleucine. This enzyme is the target site of several classes of structurally unrelated herbicides. The conventional method of antibody production using purified protein has not been successful with this enzyme. Two separate fragments of a gene encoding a portion of the mature region of AHAS from Arabidopsis were fused with the trpE gene from Escherichia coli using the pATH1 vector. E. coli cells transformed with each respective plasmid expressed a fusion protein at levels greater than 10% of the total cell protein. The fusion protein was purified and used to immunize rabbits. Antisera obtained from the immunized rabbits immunoprecipitated AHAS activity from Arabidopsis cell free extracts. The anti-AHAS antisera reacted with a 65 kilodalton protein band in electrophoretically resolved extracts of Arabidopsis. In cross-reactivity tests, this antibody was able to immunoprecipitate AHAS activity from various plant species. Furthermore, a protein band with a molecular mass of 65 kilodaltons was detected in the crude extracts of all plant species tested on a Western blot. These results indicate that the 65 kilodalton protein represents AHAS in various plant species. The wide spectrum of cross-reactivity for the antisera supports the view that the AHAS enzyme is highly conserved across all plant species.",1
"Singh, B, Schmitt, G, Lillis, M, Hand, J M, Misra, R",2
Elicitor-inducible 3-hydroxy-3-methylglutaryl coenzyme a reductase activity is required for sesquiterpene accumulation in tobacco cell suspension cultures.,0
"Addition of cell wall fragments from Phytophthora species or cellulase from Trichoderma viride, but not pectolyase from Aspergillus japonicus, to tobacco (Nicotiana tabacum) cell suspension cultures induced the accumulation of the extracellular sesquiterpenoid capsidiol. Pulse-labeling experiments with [(14)C]acetate and [(3)H]mevalonate suggested that enzymatic steps preceding mevalonate were limiting capsidiol biosynthesis in the pectolyase-treated cell cultures. Treatment of the cell cultures with either Phytophthora cell wall fragments or cellulase induced 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and sesquiterpene cyclase activities, enzymes of the sesquiterpene biosynthetic pathway, and phenylalanine ammonia lyase activity, an enzyme of the general phenylpropanoid pathway. Pectolyase treatment induced sesquiterpene cyclase and phenylalanine ammonia lyase activities, but not HMGR activity. These results corroborate the importance of inducible HMGR enzyme activity for sesquiterpene accumulation.",1
"Chappell, J, Vonlanken, C, Vögeli, U",2
Induction and regulation of ethylene biosynthesis by pectic oligomers in cultured pear cells.,0
"Pectic oligomers induced a rapid, transient increase in ethylene biosynthesis when added to pear cells in suspension culture. The rate of ethylene biosynthesis increased within 30 to 40 minutes after oligomer addition, reached a maximum between 90 and 120 minutes after addition, and then decreased to basal rates of synthesis. Both the rapid increase and decrease in biosynthesis appear to be precisely regulated components of the ethylene response to oligomers. Induction of ethylene biosynthesis by pectic oligomers resulted in a reduced sensitivity of cells to further ethylene induction. This reduction in sensitivity occurred within 90 minutes after an oligomer treatment, slightly preceding the decline in ethylene synthesis. The degree of insensitivity induced was proportional to the concentration of oligomer in the first treatment. Induced insensitivity to elicitors appears to represent a novel mechanism which may limit continued ethylene biosynthesis after ethylene induction. Ethylene was produced by pear cells throughout the cell growth cycle, as cells increased in density over a 6 day period. Endogenous ethylene biosynthesis was at a maximum during the first 4 days of rapid cell growth, then declined to half the peak rate through day 10. Pectic oligomers could induce an increase in ethylene biosynthesis above this background rate only after day 5, as endogenous biosynthesis declined. Changes in sensitivity to added oligomer during the growth cycle may result from insensitivity to elicitors induced by growth processes.",1
"Campbell, A D, Labavitch, J M",2
Induction and regulation of ethylene biosynthesis and ripening by pectic oligomers in tomato pericarp discs.,0
"The effect of pectic oligomers and 1-aminocyclopropane carboxylic acid on ethylene biosynthesis and color change was studied in ripening tomato pericarp discs excised from mature-green tomato fruit (Lycopersicon esculentum Mill.). Pectic oligomers induced at least four distinct responses when added to pericarp discs: (a) a short-term, transient increase in ethylene biosynthesis; (b) a long-term, persistent increase in climacteric ethylene in discs excised from mature-green fruit; (c) an advance in ripening processes, as indicated by increased reddening of the disc surfaces; and (d) a darkening of the treated endocarp surface. Pectic oligomers appear to affect the ripening of exocarp and endocarp tissues by different mechanisms. In exocarp tissues, the acceleration of reddening by pectic oligomers might simply be a consequence of induced ethylene biosynthesis. In endocarp tissues, the acceleration of reddening appears to be a direct effect of oligomers on ripening processes. We suggest that the rate of ripening of endocarp tissues may be regulated, in part, by the release of pectic oligomers from the cell walls of adjacent exocarp tissues. Exocarp and endocarp tissues of pericarp discs appear to differ in their sensitivity to ethylene at each maturity stage, and to exhibit independent changes in sensitivity to ethylene as ripening progresses. The tissue-specific pattern of reddening in tomato pericarp may result from this differential sensitivity to endogenous ethylene concentrations.",1
"Campbell, A D, Labavitch, J M",2
Genetic Regulation of Development in Sorghum bicolor: VI. The ma(3) Allele Results in Abnormal Phytochrome Physiology.,0
"Physiological processes controlled by phytochrome were examined in three near-isogenic genotypes of Sorghum bicolor, differing at the allele of the third maturity gene locus. Seedlings of 58M (ma(3) (R)ma(3) (R)) did not show phytochrome control of anthocyanin synthesis. In contrast, seedlings of 90M (ma(3)ma(3)) and 100M (Ma(3)Ma(3)) demonstrated reduced anthocyanin synthesis after treatment with far red and reversal of the far red effect by red. De-etiolation of 48-hour-old 90M and 100M dark-grown seedlings occurred with 48 hours of continuous red. Dark-grown 58M seedlings did not de-etiolate with continuous red treatment. Treatment of seedlings with gibberellic acid or tetcyclacis, a gibberellin synthesis inhibitor, did not alter anthocyanin synthesis. Levels of chlorophyll and anthocyanin were lower in light-grown 58M seedlings than in 90M and 100M. Etiolated seedlings of all three genotypes have similar amounts of photoreversible phytochrome. Crude protein extracts from etiolated seedlings were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose. Phytochrome was visualized with Pea-25, a monoclonal antibody directed to phytochrome from etiolated peas. The samples from all three genotypes contained approximately equivalent amounts of a prominent, immunostaining band at 126 kD. However, the sample from 58M did not show a fainter, secondary band at 123 kD that was present in 90M and 100M. The identity and importance of this secondary band at 123 kD is unknown. We propose that 58M is a phytochrome-related mutant that contains normal amounts of photoreversible phytochrome and normal phytochrome protein when grown in the dark.",1
"Childs, K L, Pratt, L H, Morgan, P W",2
Involvement of wound and climacteric ethylene in ripening avocado discs.,0
"Avocado (Persea americana Mill. cv Hass) discs (3 mm thick) ripened in approximately 72 hours when maintained in a flow of moist air and resembled ripe fruit in texture and taste. Ethylene evolution by discs of early and midseason fruit was characterized by two distinct components, viz. wound ethylene, peaking at approximately 18 hours, and climacteric ethylene, rising to a peak at approximately 72 hours. A commensurate respiratory stimulation accompanied each ethylene peak. Aminoethoxyvinyl glycine (AVG) given consecutively, at once and at 24 hours following disc preparation, prevented wound and climacteric respiration peaks, virtually all ethylene production, and ripening. When AVG was administered for the first 24 hours only, respiratory stimulation and softening (ripening) were retarded by at least a day. When AVG was added solely after the first 24 hours, ripening proceeded as in untreated discs, although climacteric ethylene and respiration were diminished. Propylene given together with AVG led to ripening under all circumstances. 2,5-Norbornadiene given continuously stimulated wound ethylene production, and it inhibited climacteric ethylene evolution, the augmentation of ethylene-forming enzyme activity normally associated with climacteric ethylene, and ripening. 2,5-Norbornadiene given at 24 hours fully inhibited ripening. When intact fruit were pulsed with ethylene for 24 hours before discs were prepared therefrom, the respiration rate, ethylene-forming enzyme activity buildup, and rate of ethylene production were all subsequently enhanced. The evidence suggests that ethylene is involved in all phases of disc ripening. In this view, wound ethylene in discs accelerates events that normally take place over an extended period throughout the lag phase in intact fruit, and climacteric ethylene serves the same ripening function in discs and intact fruit alike.",1
"Starrett, D A, Laties, G G",2
Accumulation of beta-Fructosidase in the Cell Walls of Tomato Roots following Infection by a Fungal Wilt Pathogen.,0
"Active defense in plants is associated with marked metabolic alterations, but little is known about the exact role of the reported changes in specific activity of several enzymes in infected plant tissues. beta-Fructosidase (invertase), the enzyme that converts sucrose into glucose and fructose, increases upon infection by fungi and bacteria. To understand the relationship between fungal growth and beta-fructosidase accumulation, we used an antiserum raised against a purified deglycosylated carrot cell wall beta-fructosidase to study by immunogold labeling the spatial and temporal distribution of the enzyme in susceptible and resistant tomato (Lycopersicon esculentum) root tissues infected with the necrotrophic fungus, Fusarium oxysporum f. sp. racidis-lycopersici. In susceptible plants, the enzyme started to accumulate in host cell walls about 72 hours after inoculation. Accumulation occurred only in colonized cells and was mainly restricted to areas where the walls of both partners contacted each other. In resistant plants, accumulation of beta-fructosidase was noticeable as soon as 48 hours after inoculation and appeared to reach an optimum by 72 hours after inoculation. Increase in wall-bound beta-fructosidase was not restricted to infected cells but occurred also, to a large extent, in tissues that remained uncolonized during the infection process. The enzyme also accumulated in wall appositions (papillae) and intercellular spaces. This pattern of enzyme distribution suggests that induction of beta-fructosidase upon fungal infection is part of the plant's defense response. The possible physiological role(s) of this enzyme in infected tomato plants is discussed in relation to the high demand in energy and carbon sources during pathogenesis.",1
"Benhamou, N, Grenier, J, Chrispeels, M J",2
Rhizobium nod Gene Inducers Exuded Naturally from Roots of Common Bean (Phaseolus vulgaris L.).,0
"Four compounds exuded from young roots of a black-seeded bean (Phaseolus vulgaris L., cv PI165426CS) induce transcription of nod genes in Rhizobium leguminosarum biovar phaseoli. The three most active nod gene inducers were identified by spectroscopic methods (ultraviolet/visible absorbance, proton nuclear magnetic resonance, and mass spectrometry) as being eriodictyol (5,7,3',4' -tetrahydroxyflavanone), naringenin (5,7,4' -trihydroxyflavanone), and a 7-O-glycoside of genistein (5,7,4' -trihydroxyisoflavone). Comparisons with authentic standards verified the chemical structures of the aglycones and their capacity to induce beta-galactosidase activity in R. leguminosarum strains containing nodA-lacZ or nodC-lacZ fusions controlled by R. leguminosarum biovar phaseoli nodD genes. Roots of 9-day-old seedlings released 42, 281, and 337 nanomoles per plant per day of genistein, eriodictyol, and naringenin, respectively. Genistein and naringenin induced higher maximum beta-galactosidase activities and required lower concentrations for half-maximum induction than eriodictyol. Comparing the nod gene-inducing activity of seed rinses with root exudate from PI165426CS bean showed that root flavonoids were released at about 6% the rate of those from seeds on a molar basis, but on average the individual compounds from roots were approximately three times more active than nod gene inducers from seeds.",1
"Hungria, M, Joseph, C M, Phillips, D A",2
Occurrence and in Vivo Biosynthesis of Indole-3-Butyric Acid in Corn (Zea mays L.).,0
"Indole-3-butyric acid (IBA) was identified as an endogenous compound in leaves and roots of maize (Zea mays L.) var Inrakorn by thin layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. Its presence was also confirmed in the variety Hazera 224. Indole-3-acetic acid (IAA) was metabolized to IBA in vivo by seedlings of the two maize varieties. The reaction product was identified by thin layer chromatography, high performance liquid chromatography, and gas chromatography-mass spectrometry after incubating the corn seedlings with [(14)C]IAA and [(13)C(6)]IAA. The in vivo conversion of IAA to IBA and the characteristics of IBA formation in two different maize varieties of Zea mays L. (Hazera 224 and Inrakorn) were investigated. IBA-forming activity was examined in the roots, leaves, and coleoptiles of both maize varieties. Whereas in the variety Hazera 224, IBA was formed mostly in the leaves, in the variety Inrakorn, IBA synthesis was detected in the roots as well as in the leaves. A time course study of IBA formation showed that maximum activity was reached in Inrakorn after 1 hour and in Hazera after 2 hours. The pH optimum for the uptake of IAA was 6.0, and that for IBA formation was 7.0. The K(m) value for IBA formation was 17 micromolar for Inrakorn and 25 micromolar for Hazera 224. The results are discussed with respect to the possible functions of IBA in the plant.",1
"Ludwig-Müller, J, Epstein, E",2
The 32-Kilodalton Vegetative Storage Protein of Salix microstachya Turz : Characterization and Immunolocalization.,0
"A 32-kilodalton vegetative storage protein, found in Salix microstachya Turz. bark during the overwintering period, was purified and characterized using several polyacrylamide gel electrophoretic procedures. Solubility characteristics and amino acid analyses were also performed. The protein is water soluble, is glycosylated, has no disulfide-bonded subunits, but is composed of a family of isoelectric isomers. The majority of these isomers are basic. Characteristic of storage proteins, the protein is rich in glutamine/glutamate and asparagine/aspartate (28%), the basic nature of the isomers indicating that most of these amino acid residues are in the amide form. The protein was purified using preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and antibodies raised in chickens. Immunoblot analysis suggested an annual cyclic nature of the accumulation and mobilization of this vegetative storage protein. Immunologically, it is related to a similar molecular weight protein found in the bark of Populus deltoides Marsh. but not to any overwintering storage proteins of the other hardwoods tested. Indirect immunolocalization revealed that the protein was sequestered in protein-storage vacuoles in parenchymatous cells of the inner bark tissues of Salix during the winter months.",1
"Wetzel, S, Greenwood, J S",2
"Cadaverine, an Essential Diamine for the Normal Root Development of Germinating Soybean (Glycine max) Seeds.",0
"When the polyamine content of soybean (Glycine max) seeds was examined during the early stages of germination, the major polyamine in the cotyledons was found to be spermidine, followed by spermine; while very low concentrations of cadaverine were found. In the embryonic axes, however, cadaverine was the main polyamine and its content markedly increased 24 hours after the start of germination. When the germination of the seeds was performed in the presence of 1 millimolar alpha-difluoromethylornithine (DFMO), a marked decrease in the cadaverine content was found, while the other polyamines were not affected. This decrease of the cadaverine content was already noticeable after the first hours of germination. In the presence of DFMO, a pronounced elongation in the roots of the seedlings and a marked decrease in the appearance of secondary roots as compared with controls, was observed. This abnormal rooting of the seedlings caused by DFMO was almost completely reverted by the addition of 1 millimolar cadaverine. The latter also increased the appearance of secondary roots in the seedlings. The decrease in the cadaverine content produced by DFMO could be traced to a strong inhibition of lysine decarboxylase. A temporal correlation between the increase in cadaverine content and the increase in lysine decarboxylase activity was found. Both reached a maximum at the second day of germination. The activity of diamine oxidase, the cadaverine degrading enzyme, started to increase at the third day and reached a maximum between the fourth and fifth day of germination. DFMO increased the activity of diamine oxidase by about 25%. Hence, the large decrease in cadaverine content produced by DFMO has to be attributed to the in vivo suppression of lysine decarboxylase activity. Ornithine decarboxylase activity was also suppressed by DFMO, but putrescine and spermidine contents were not affected, except in the meristematic tissues. The obtained results suggest an important role for cadaverine in the normal rooting process of soybean seedlings.",1
"Gamarnik, A, Frydman, R B",2
Purification and Developmental Analysis of a Metalloendoproteinase from the Leaves of Glycine max.,0
A metalloendoproteinase from leaves of soybean (Glycine max) has been purified 1160-fold to electrophoretic homogeneity. The native protein is monomeric with a molecular mass of 15 kilodaltons as estimated by gel filtration and 19 kilodaltons as estimated by denaturing gel electrophoresis. The enzyme has a pH optima of 8.0 to 9.0 using Azocoll as substrate. The proteolytic activity is susceptible to metal chelating agents and the inactivated enzyme can be restored to 69% of original activity by the addition of ZnCl(2). Western analysis shows that a fraction of the soybean metalloendoproteinase is present within the extracellular space of older leaves. Soybean metalloendoproteinase 1 is the Azocollase A activity first described by Ragster and Chrispeels (Plant Physiol 64: 857-862; 1979).,1
"Graham, J S, Xiong, J, Gillikin, J W",2
"Level of Abscisic Acid in Integuments, Nucellus, Endosperm, and Embryo of Peach Seeds (Prunus persica L. cv Springcrest) during Development.",0
"Free abscisic acid (ABA) in integuments, nucellus, endosperm, and embryo was determined throughout seed development of peach (Prunus persica L. cv Springcrest). Quantification of ABA was performed using combined high performance liquid chromatography-radioimmunoassay based on a monoclonal antibody raised against free (S)-ABA. In the integuments and endosperm, ABA concentration remained constant during the first 100 days after anthesis and rose in the following days when fresh weight was rapidly decreasing. In the nucellus, the ABA concentration variation pattern paralleled that of tissue growth. ABA concentration in the embryo increased constantly with the growth of the tissues to reach a maximum at the last growth stage. The role of ABA in peach seeds is discussed in relation to the development of the different seed tissues.",1
"Piaggesi, A, Perata, P, Vitagliano, C, Alpi, A",2
Abscisic Acid Metabolism in Salt-Stressed Cells of Dunaliella salina: Possible Interrelationship with beta-Carotene Accumulation.,0
"The interrelationship between abscisic acid (ABA) production and beta-carotene accumulation was investigated in salt-stressed cells of the halotolerant green alga Dunaliella salina var bardawil. Cells were supplied with either R-[2-(14)C]mevalonolactone or [(14)C] sodium bicarbonate for 20 hours and then exposed to increased salinity (1.5 to 3.0 molar NaCl) for various lengths of time. Incorporation of label into abscisic acid and phaseic acid and the distribution of [(14)C]ABA between the cells and incubation media were monitored. [(14)C]ABA and [(14)C]phaseic acid were identified as products of both R-[2-(14)C]mevalonolactone and [(14)C]sodium bicarbonate metabolism. ABA metabolism was enhanced by hypersalinity stress. Actinomycin D, chloramphenicol, and cycloheximide abolished the stress-induced production of ABA, suggesting a role for gene activation in the process. Kinetic analysis of both ABA and beta-carotene production demonstrated two stages of accelerated beta-carotene production. In addition, ABA levels increased rapidly, and this increase occurred coincident with the early period of accelerated beta-carotene production. A possible role for ABA as a regulator of carotenogenesis in cells of D. salina is therefore discussed.",1
"Cowan, A K, Rose, P D",2
Resistance to low temperature photoinhibition is not associated with isolated thylakoid membranes of winter rye.,0
"In vivo measurements of chlorophyll a fluorescence indicate that cold-hardened winter rye (Secale cereale L. cv Musketeer) develops a resistance to low temperature-induced photoinhibition compared with nonhardened rye. After 7.2 hours at 5 degrees C and 1550 micromoles per square meter per second, the ratio of variable fluorescence/maximum fluorescence was depressed by only 23% in cold-hardened rye compared with 46% in nonhardened rye. We have tested the hypothesis that the principal site of this resistance to photoinhibition resides at the level of rye thylakoid membranes. Thylakoids were isolated from cold-hardened and nonhardened rye and exposed to high irradiance (1000-2600 micromoles per square meter per second) at either 5 or 20 degrees C. The photoinhibitory response measured by room temperature fluorescence induction, photosystem II electron transport, photoacoustic spectroscopy, or [(14)C]atrazine binding indicates that the differential resistance to low temperature-induced photoinhibition in vivo is not observed in isolated thylakoids. Similar results were obtained whether isolated rye thylakoids were photoinhibited or thylakoids were isolated from rye leaves preexposed to a photoinhibitory treatment. Thus, we conclude that increased resistance to low temperature-induced photoinhibition is not a property of thylakoid membranes but is associated with a higher level of cellular organization.",1
"Lapointe, L, Huner, N P, Carpentier, R, Ottander, C",2
Regulation of sucrose-sucrose-fructosyltransferase in barley leaves.,0
"The activity of sucrose-sucrose-fructosyltransferase (SST), a vacuolar enzyme strongly induced by light in excised leaves of barley (Hordeum vulgare L.), rapidly declined even in continuous light upon feeding of cycloheximide (CHI). The rate of decline was similar to that observed in light-treated leaves that were placed into darkness, in the presence or absence of CHI. The protease inhibitor leupeptin totally stopped the decline in SST activity in the dark and caused a substantial increase in the rate of induction of SST activity by light. Feeding of sucrose prevented or even reversed the SST activity decay induced by darkness in the absence of CHI but did not stabilize SST activity in the presence of CHI. The results suggest that SST is continuously subjected to rapid, constant proteolytic degradation in the vacuole, and that the enhancement of SST activity in the light or upon feeding sucrose in the dark is due exclusively to de novo protein synthesis.",1
"Obenland, D M, Simmen, U, Boller, T, Wiemken, A",2
Wild-type levels of abscisic Acid are not required for heat shock protein accumulation in tomato.,0
"Levels of endogenous abscisic acid (ABA) in wild type were not required for the synthesis of heat shock proteins in detached leaves of tomato (Lycopersicon esculentum Mill., cv Ailsa Craig). Heat-induced alterations in gene expression were the same in the ABA-deficient mutant of tomato, flacca, and the wild type. Heat tolerance of the mutant was marginally less that the wild type, and in contrast, ABA applications significantly reduced the heat tolerance of wild-type leaves. It was concluded that elevated levels of endogenous ABA are not involved in the tomato heat shock response.",1
"Bray, E A",2
Mycorrhizal fungi and nonhydraulic root signals of soil drying.,0
"We propose that mycorrhizal colonization of roots alters nonhydraulic root to shoot communication of soil drying. Split-root rose (Rosa hybrida L. cv Samantha) plants-one side of the root system colonized by Glomus intraradices Schenck & Smith, the other side nonmycorrhizal-displayed different stomatal conductances upon partial drying, depending upon whether mycorrhizal or nonmycorrhizal roots were dried. No differences in leaf water status were observed among control plants and those whose mycorrhizal or nonmycorrhizal roots were dried.",1
"Augé, R M, Duan, X",2
Control of Nitrogenase mRNA Levels by Products of Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120.,0
"Nitrate inhibited nitrogenase synthesis and heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Inhibition of dinitrogen fixation by nitrate did not take place, however, in nitrate reductase-deficient derivatives of this strain. Hybridization of total RNA isolated from cells grown on different nitrogen sources with an internal fragment of the nifD gene showed that regulation of nitrogenase activity by nitrate is exerted through a negative control of the nitrogenase mRNA levels.",1
"Martín-Nieto, J, Herrero, A, Flores, E",2
Evidence That More than 90% of beta-Glucuronidase-Expressing Cells after Particle Bombardment Directly Receive the Foreign Gene in their Nucleus.,0
"Plasmid DNA harboring the beta-glucuronidase (GUS) gene, coated on gold particles, was delivered into cultured tobacco (Nicotiana tabacum L. cv Bright Yellow-2) cells using a pneumatic particle gun. Cytological analyses of intracellular location of the introduced gold particles before and after GUS expression assay indicated that more than 90% of GUS-expressing cells after bombardment received a DNA-coated particle in their nucleus.",1
"Yamashita, T, Iida, A, Morikawa, H",2
Hygromycin resistance gene cassettes for vector construction and selection of transformed rice protoplasts.,0
"Hygromycin resistance gene cassettes were designed to facilitate vector construction for plant transformation. Unique EcoRI, Pstl, and Sacll sites in the coding sequence of a hygromycin B phosphotransferase gene (hph) from Escherichia coli were eliminated. The mutated hph genes were used to form gene cassettes flanked by EcoRI-Sacll-Kpnl-Hindlll sites. Hygromycin resistance of wild-type and mutated hph genes was indistinguishable in E. coli and rice protoplast growth assay.",1
"Zheng, Z, Hayashimoto, A, Li, Z, Murai, N",2
Inhibition of lettuce seed germination by cycloheximide and chloramphenicol is alleviated by kinetin and oxygen.,0
Kinetin alleviates cycloheximide inhibition and oxygen alleviates chloramphenicol inibition of germination of lettuce seeds (Lactuca sativa L. cv Grand Rapids). The effect is not due to increased but rather a substitution for protein synthesis. A cytokinin and energy supply appear prime requirements for germination.,1
"Schultz, C, Small, J G",2
Purification and Characterization of Two Major Lectins from Araucaria brasiliensis syn. Araucaria angustifolia Seeds (Pinhão).,0
"Two major lectins (lectin I and lectin II) were purified to homogeneity from the seeds of Araucaria brasiliensis (Gymnospermae). The purity of the lectins was confirmed by polyacrylamide gel electrophoresis, isoelectric focusing, and high performance liquid chromatography. They are glycoproteins in nature containing 6.3 and 2.9%, respectively, of neutral sugar and have absorption coefficients of 3.8 and 4.7, respectively, at 280 nanometers. The molecular weights of both lectins obtained by gel filtration on Sephacryl S-400 were equal: 200,000. After dissociation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, molecular weights were 20,000 and 34,000, respectively, for lectin I and lectin II, suggesting they are decameric and hexameric in nature. The amino acid composition of both lectins showed little difference, but both had high amounts of acidic amino acids and lacked methionine in their molecule. The carbohydrate binding specificity of lectins was directed towards mannose, glucose, and their oligomers. High inhibitory activity was also found with thyroglobulin. The erythroagglutinating activity of the lectins was enhanced in the presence of high-molecular-weight substances both at 37 and 4 degrees C. Divalent cations do not appear to be essential for activity. They maintained their agglutinating activity over a broad but different range of pH: 5.5 to 7.5 and 6.5 to 7.5, respectively. Both lectins agglutinated erythrocytes of human ABO blood types equally well.",1
"Datta, P K, Figueroa, M O, Lajolo, F M",2
Effects of Elevated Cytosolic Glutathione Reductase Activity on the Cellular Glutathione Pool and Photosynthesis in Leaves under Normal and Stress Conditions.,0
"Tobacco (Nicotiana tabacum var Samsun) was transformed using the bacterial gor gene coding for the enzyme glutathione reductase. Transgenic plants were selected by their kanamycin resistence and expression of the bacterial gor gene. After separation by isoelectric focusing techniques, leaf extracts from transgenic plants having both native and bacterial glutathione reductase activity gave, in addition to the six bands of the native enzyme, two further closely running isoenzymes. These additional bands originating from the expression of the bacterial gor gene were nonchloroplastic. Leaves from transgenic plants had two- to 10-fold higher glutathione reductase activity than non-transgenic controls. The amount of extractable glutathione reductase activity obtained in transgenic plants was dependent on leaf age and the conditions to which leaves were exposed. Both light and exposure to methylviologen increased leaf glutathione reductase activity. Elevated levels of cytosolic glutathione reductase activity in transgenic plants had no effect on the amount or reduction state of the reduced glutathione/oxidized glutathione pool under optimal conditions or oxidative conditions induced by methylviologen. The glutathione pool was unaltered despite the oxidation-dependent loss of CO(2) assimilation and oxidation of enzymes involved in photosynthesis. However, the reduction state of the ascorbate pool was greater in transgenic plants relative to nontransgenic controls following illumination of methylviologen-treated leaf discs. Therefore, we conclude that in the natural state glutathione reductase is present in tobacco at levels above those required for maximal operation of the ascorbate-glutathione pathway.",1
"Foyer, C, Lelandais, M, Galap, C, Kunert, K J",2
Accumulation of Scoparone in Heat-Treated Lemon Fruit Inoculated with Penicillium digitatum Sacc.,0
"Phytoalexin scoparone (6,7-dimethoxycoumarin) generally was not detected in noninoculated lemon fruit (Citrus limon [L.] Burm., cv Eureka) but accumulated in fruit after inoculation with Penicillium digitatum Sacc. A much greater increase in the amount of scoparone was found in fruit exhibiting an incompatible response to Penicillium after heat treatment at 36 degrees C for 3 days. Heat treatment prevented development of decay in the inoculated fruit. The concentration of the compound after inoculation continued to increase during and after the heat treatment period, reaching 178 micrograms per gram fresh weight of the flavedo 6 days after the heat treatment. Changes in scoparone concentration in fruit were closely correlated with the changes in the antifungal activity of the fruit extract. A low concentration of the phytoalexin was detected in fruit injured mechanically. Scoparone also accumulated in the fruit following ultraviolet illumination; the concentration of the compound was dose-dependent. Median effective dose values of the inhibition of germ tube elongation and spore germination of P. digitatum were 29 and 46 micrograms per milliliter, respectively. Our findings suggest that the rapid increase in scoparone concentration plays an important role in the increased resistance of heat-treated lemon fruit to infection by P. digitatum.",1
"Kim, J J, Ben-Yehoshua, S, Shapiro, B, Henis, Y, Carmeli, S",2
Chlorophyll Fluorescence and Photon Yield of Oxygen Evolution in Iron-Deficient Sugar Beet (Beta vulgaris L.) Leaves.,0
"The response of sugar beet (Beta vulgaris L.) leaves to iron deficiency can be described as consisting of two phases. In the first phase, leaves may lose a large part of their chlorophyll while maintaining a roughly constant efficiency of photosystem II photochemistry; ratios of variable to maximum fluorescence decreased by only 6%, and photon yields of oxygen evolution decreased by 30% when chlorophyll decreased by 70%. In the second phase, when chlorophyll decreased below a threshold level, iron deficiency caused major decreases in the efficiency of photosystem II photochemistry and in the photon yield of oxygen evolution. These decreases in photosystem II photochemical efficiency were found both in plants dark-adapted for 30 minutes and in plants dark-adapted overnight, indicating that photochemical efficiency cannot be repaired in that time scale. Decreases in photosystem II photochemical efficiency and in the photon yield of oxygen evolution were similar when measurements were made (a) with light absorbed by carotenoids and chlorophylls and (b) with light absorbed only by chlorophylls. Leaves of iron-deficient plants exhibited a room temperature fluorescence induction curve with a characteristic intermediate peak I that increases with deficiency symptoms.",1
"Morales, F, Abadía, A, Abadía, J",2
Regulation of 2-carboxyarabinitol 1-phosphatase.,0
"The regulation of 2-carboxyarabinitol 1-phosphatase (CA 1-Pase) by phosphorylated effectors was studied with enzyme purified from tobacco (Nicotiana tabacum) leaves. CA 1-Pase activity was most stimulated by fructose 1,6-bisphosphate, exhibiting an A(0.5) value of 1.9 millimolar and a 10-fold enhancement of catalysis. With ribulose-1,5-bisphosphate, the A(0.5) was 0.6 millimolar, and maximal stimulation of activity was 5.3-fold. Among the monophosphates, 3-phosphoglycerate and phosphoglycolate were more potent positive effectors than glyceraldehyde 3-phosphate, glucose 1-phosphate, glucose 6-phosphate, and dihydroxyacetone phosphate. Stimulation of CA 1-Pase by ribulose-1,5-bisphosphate and fructose 1,6-bisphosphate increased V(max) but did not appreciably alter K(m) (2-carboxyarabinitol 1-phosphate) values. Inorganic phosphate appeared to inhibit CA 1-Pase noncompetitively with respect to 2-carboxyarabinitol 1-phosphate, exhibiting a K(i) of 0.3 millimolar. The results suggest that these positive and negative effectors bind to a regulatory site on CA 1-Pase and may have a physiologial role in the light regulation of this enzyme. Related experiments with CA 1-Pase inactivated by dialysis in the absence of dithiothreitol show that partial reactivation can be achieved in the presence of a range of reducing reagents, including dithiothreitol, cysteine, and reduced glutathione. This could imply an ancillary involvement of sulfhydryl reduction during light activation of CA 1-Pase in vivo. The enzyme was thermally stable up to 35 degrees C, in contrast to ribulose-1,5-bisphosphate carboxylase/oxygenase activase which lost activity above 30 degrees C. The activation energy for CA 1-Pase was calculated to be 56.14 kilojoules per mole.",1
"Holbrook, G P, Galasinski, S C, Salvucci, M E",2
Nucleotide sequence and spatial expression pattern of a drought- and abscisic Acid-induced gene of tomato.,0
"The nucleotide sequence of le16, a tomato (Lycopersicon esculentum Mill.) gene induced by drought stress and regulated by abscisic acid specifically in aerial vegetative tissue, is presented. The single open reading frame contained within the gene has the capacity to encode a polypeptide of 12.7 kilodaltons and is interrupted by a small intron. The predicted polypeptide is rich in leucine, glycine, and alanine and has an isoelectric point of 8.7. The amino terminus is hydrophobic and characteristic of signal sequences that target polypeptides for export from the cytoplasm. There is homology (47.2% identity) between the amino terminus of the LE 16 polypeptide and the corresponding amino terminal domain of the maize phospholipid transfer protein. le16 was expressed in drought-stressed leaf, petiole, and stem tissue and to a much lower extent in the pericarp of mature green tomato fruit and developing seeds. No expression was detected in the pericarp of red fruit or in drought-stressed roots. Expression of le16 was also induced in leaf tissue by a variety of other abiotic stresses including polyethylene glycol-mediated water deficit, salinity, cold stress, and heat stress. None of these stresses or direct applications of abscisic acid induced the expression of le16 in the roots of the same plants. The unique expression characteristics of this gene indicates that novel regulatory mechanisms, in addition to endogenous abscisic acid, are involved in controlling gene expression.",1
"Plant, A L, Cohen, A, Moses, M S, Bray, E A",2
Maintenance of turgor by rapid sealing of puncture wounds in leaf epidermal cells.,0
"When leaf epidermal cells are puncture wounded with a glass microcapillary tip, a small droplet of fluid is discharged and then evaporates, leaving a solid residue on the cell surface. For puncture wounds of about 3.5 micrometers in diameter, this process is complete within 2 to 3 seconds. A second puncture wound also exhibits a similar discharge, indicating the persistence of some turgor pressure within the cell, despite damage to the cell wall. Direct measurement of turgor on the large epidermal cells of Tradescantia virginiana L. demonstrated that turgor was substantially maintained (91-96%) after puncture wounding. Anatomical and histochemical evidence suggests that the damaged portion of the cell wall was sealed with an amorphous plug of material comprised of pectinaceous polysaccharides. Rapid sealing of puncture wounds and the maintenance of turgor in epidermal cells may be an important functional component of plant adaptation to physical damage such as that caused by insect feeding.",1
"Shackel, K A, Polito, V S, Ahmadi, H",2
Isolation and Partial Characterization of a Factor from Barley Aleurone that Modifies alpha-Amylase in Vitro.,0
"Posttranslational modifications that give rise to multiple forms of alpha-amylase (EC 3.2.1.1) in barley (Hordeum vulgare L. cv Himalaya) were studied. When analyzed by denaturing polyacrylamide gel electrophoresis, barley alpha-amylase has a molecular mass of 43 to 44 kilodaltons, but isoelectric focusing resolves the enzyme into a large number of isoforms. To precisely identify these isoforms, we propose a system of classification based on their isoelectric points (pl). alpha-Amylases with pls of approximately 5, previously referred to as low pl or Amy1 isoforms, have been designated HAMY1, and alpha-amylases with pls of approximately 6, referred to as high pl or Amy2, are designated HAMY2. Individual isoforms of HAMY1 and HAMY2 are identified by their pls. For example, the most acidic alpha-amylase synthesized and secreted by barley aleurone layers is designated HAMY1(4.56). Some of the diversity in the pls of barley alpha-amylases arises from posttranslational modifications of the enzyme. We report the isolation of a factor from barley aleurone layers and incubation media that can modify HAMY1 isoforms in vitro. This factor has a molecular mass between 30 and 50 kilodaltons, and it can catalyze the conversion of HAMY1(4.90) and HAMY1(4.64) to isoforms 4.72 and 4.56, respectively. The in vitro conversion of HAMY1 isoforms by the factor is favored by pH values of approximately 5 and is inhibited at approximately pH 7. The level of this factor in aleurone layers and incubation media is not affected by treatment of the tissue with gibberellic acid. The amylase-modifying activity from barley will also modify alpha-amylases isolated from human saliva and porcine pancreas. An activity that can modify HAMY1 isoforms in vitro has also been isolated from Onozuka R10 cellulase. Because the activity isolated from barley lowers the pl of alpha-amylase from barley, human saliva, and porcine pancreas, we speculate that it is a deamidase.",1
"Sticher, L, Jones, R L",2
High Affinity Transport of CO(2) in the Cyanobacterium Synechococcus UTEX 625.,0
"The active transport of CO(2) in Synechococcus UTEX 625 was measured by mass spectrometry under conditions that preclude HCO(3) (-) transport. The substrate concentration required to give one half the maximum rate for whole cell CO(2) transport was determined to be 0.4 +/- 0.2 micromolar (mean +/- standard deviation; n = 7) with a range between 0.2 and 0.66 micromolar. The maximum rates of CO(2) transport ranged between 400 and 735 micromoles per milligram of chlorophyll per hour with an average rate of 522 for seven experiments. This rate of transport was about three times greater than the dissolved inorganic carbon saturated rate of photosynthetic O(2) evolution observed under these conditions. The initial rate of chlorophyll a fluorescence quenching was highly correlated with the initial rate of CO(2) transport (correlation coefficient = 0.98) and could be used as an indirect method to detect CO(2) transport and calculate the substrate concentration required to give one half the maximum rate of transport. Little, if any, inhibition of CO(2) transport was caused by HCO(3) (-) or by Na(+)-dependent HCO(3) (-) transport. However, (12)CO(2) readily interfered with (13)CO(2) transport. CO(2) transport and Na(+)-dependent HCO(3) (-) transport are separate, independent processes and the high affinity CO(2) transporter is not only responsible for the initial transport of CO(2) into the cell but also for scavenging any CO(2) that may leak from the cell during ongoing photosynthesis.",1
"Espie, G S, Miller, A G, Canvin, D T",2
Changes in Osmotic Pressure and Mucilage during Low-Temperature Acclimation of Opuntia ficus-indica.,0
"Opuntia ficus-indica, a Crassulacean acid metabolism plant cultivated for its fruits and cladodes, was used to examine chemical and physiological events accompanying low-temperature acclimation. Changes in osmotic pressure, water content, low molecular weight solutes, and extracellular mucilage were monitored in the photosynthetic chlorenchyma and the water-storage parenchyma when plants maintained at day/night air temperatures of 30/20 degrees C were shifted to 10/0 degrees C. An increase in osmotic pressure of 0.13 megapascal occurred after 13 days at 10/0 degrees C. Synthesis of glucose, fructose, and glycerol accounted for most of the observed increase in osmotic pressure during the low-temperature acclimation. Extracellular mucilage and the relative apoplastic water content increased by 24 and 10%, respectively, during exposure to low temperatures. These increases apparently favor the extracellular nucleation of ice closer to the equilibrium freezing temperature for plants at 10/0 degrees C, which could make the cellular dehydration more gradual and less damaging. Nuclear magnetic resonance studies helped elucidate the cellular processes during ice formation, such as those revealed by changes in the relaxation times of two water fractions in the chlorenchyma. The latter results suggested a restricted mobility of intracellular water and an increased mobility of extracellular water for plants at 10/0 degrees C compared with those at 30/20 degrees C. Increased mobility of extracellular water could facilitate extracellular ice growth and thus delay the potentially lethal intracellular freezing during low-temperature acclimation.",1
"Goldstein, G, Nobel, P S",2
Purification and characterization of pea cytosolic ascorbate peroxidase.,0
"The cytosolic isoform of ascorbate peroxidase was purified to homogeneity from 14-day-old pea (Pisum sativum L.) shoots. The enzyme is a homodimer with molecular weight of 57,500, composed of two subunits with molecular weight of 29,500. Spectral analysis and inhibitor studies were consistent with the presence of a heme moiety. When compared with ascorbate peroxidase activity derived from ruptured intact chloroplasts, the purified enzyme was found to have a higher stability, a broader pH optimum for activity, and the capacity to utilize alternate electron donors. Unlike classical plant peroxidases, the cytosolic ascorbate peroxidase had a very high preference for ascorbate as an electron donor and was specifically inhibited by p-chloromercurisulfonic acid and hydroxyurea. Antibodies raised against the cytosolic ascorbate peroxidase from pea did not cross-react with either protein extracts obtained from intact pea chloroplasts or horseradish peroxidase. The amino acid sequence of the N-terminal region of the purified enzyme was determined. Little homology was observed among pea cytosolic ascorbate peroxidase, the tea chloroplastic ascorbate peroxidase, and horseradish peroxidase; homology was, however, found with chloroplastic ascorbate peroxidase isolated from spinach leaves.",1
"Mittler, R, Zilinskas, B A",2
Effects of exogenous auxins on expression of lipoxygenases in cultured soybean embryos.,0
"The expression of lipoxygenases (LOXs) is known to be developmentally regulated in soybeans (Glycine max. [L.] Merr.). Hormones have been firmly established as being involved in the growth and developmental processes of a number of plant species. Correlation between the expression of LOXs and the development and germination of soybean embryos suggests that plant hormones may affect the expression of LOXs. The present studies were conducted to investigate the effects of exogenous auxins on the expression of LOX isozymes and LOX activities in cultured cotyledon tissues of immature soybean seeds. The results revealed that at least one of the more acidic nonembryo LOX isozymes was induced by either alpha-naphthaleneacetic acid or indoleacetic acid but not by 2,4-dichlorophenoxyacetic acid after 4 days' exposure. Levels of LOX-1, -2, and -3 proteins and activities were significantly decreased by 2,4-dichlorophenoxyacetic acid 10 days after explanting. S1 analysis showed that embryo LOX messenger RNAs were detectable in the tissues treated with each of the auxins. The reduced levels of the embryo LOX proteins may, therefore, be regulated at the levels of translation, posttranslational modification, or degradation. The more acidic isozymes induced by alpha-naphthaleneacetic acid showed enzymatic activity and shared the same molecular mass and isoelectric point values as the germination-associated LOX isozymes found in hypocotyls and radicles, suggesting that those LOXs are involved in germination competency of soybean embryos.",1
"Liu, W, Hildebrand, D F, Grayburn, W S, Phillips, G C, Collins, G B",2
Ectomycorrhizin Synthesis and Polypeptide Changes during the Early Stage of Eucalypt Mycorrhiza Development.,0
"In functioning eucalypt ectomycorrhizas, biochemical alterations are accompanied by a differential accumulation of polypeptides including the synthesis of symbiosis-related proteins (JL Hilbert, Martin FM [1988] New Phytol 110: 339-346). In the present study, protein biosynthesis in the early stages of ectomycorrhiza formation on Eucalyptus globulus subsp. bicostata Kirkp. was examined using compatible and incompatible isolates of the basidiomycete Pisolithus tinctorius (Coker & Couch). Changes in polypeptide composition were observed within hours following contact of the compatible mycelium with the roots, well before the differentiation of typical symbiotic tissues. At this stage, at least seven symbiosis-related proteins (ectomycorrhizins) accumulated in root tissues. In vivo incorporation of [(35)S]methionine by ectomycorrhizas followed by electrophoresis of the labeled proteins revealed that most of these differences in polypeptide concentrations, including the ectomycorrhizin accumulation, are the result of differential protein biosynthesis rather than posttranslational modifications of the polypeptides. The initial development of eucalypt ectomycorrhizas, therefore, coincides with the synthesis of symbiosis-related proteins and the data presented here provide essential evidence to ascribe a functional developmental role to these proteins.",1
"Hilbert, J L, Costa, G, Martin, F",2
Assessing the degree of c(4) photosynthesis in c(3)-c(4) species using an inhibitor of phosphoenolpyruvate carboxylase.,0
"An analog of phosphoenolpyruvate, 3,3-dichloro-2-dihydroxyphosphinoylmethyl-2-propenoate (DCDP), was used to inhibit phosphoenolpyruvate carboxylase and, therefore, assess the contribution of the C(4) pathway to photosynthesis in detached leaves of several C(3)-C(4) intermediate species. There was no effect of 4 millimolar DCDP on apparent photosynthesis or on inhibition of apparent photosynthesis by 210 milliliters per liter of O(2) for the C(3)-C(4) species Panicum milioides, Moricandia arvensis, and Neurachne minor or the C(3) species Flaveria pringlei. However, when leaves of Flaveria linearis (C(3)-C(4)), Flaveria brownii (C(4)-like), and Flaveria trinervia (C(4)) were fed 4 millimolar DCDP, photosynthesis was reduced 32, 60, and 90%, respectively. Photosynthetic inhibition by 210 milliliter per liter of O(2) was also significantly increased in 4 millimolar DCDP-fed leaves of F. linearis and F. brownii but not in F. trinervia when compared with control values. These results with DCDP clearly demarcate C(3)-C(4) species into species including Panicum, Moricandia, and Neurachne whose reduced photorespiration occurs without any C(4) photosynthetic involvement and species of Flaveria in which C(4) photosynthesis contributes to CO(2) assimilation.",1
"Brown, R H, Byrd, G T, Black, C C",2
Ion Relations of Symplastic and Apoplastic Space in Leaves from Spinacia oleracea L. and Pisum sativum L. under Salinity.,0
"Salt tolerant spinach (Spinacia oleracea) and salt sensitive pea (Pisum sativum) plants were exposed to mild salinity under identical growth conditions. In order to compare the ability of the two species for extra- and intracellular solute compartmentation in leaves, various solutes were determined in intercellular washing fluids and in aqueously isolated intact chloroplasts. In pea plants exposed to 100 millimolar NaCl for 14 days, apoplastic salt concentrations in leaflets increased continuously with time up to 204 (Cl(-)) and 87 millimolar (Na(+)), whereas the two ions reached a steady concentration of only 13 and 7 millimolar, respectively, in spinach leaves. In isolated intact chloroplasts from both species, sodium concentrations were not much different, but chloride concentrations were significantly higher in pea than in spinach. Together with data from whole leaf extracts, these measurements permitted an estimation of apoplastic, cytoplasmic, and vacuolar solute concentrations. Sodium and chloride concentration gradients across the tonoplast were rather similar in both species, but spinach was able to maintain much steeper sodium gradients across the plasmamembrane compared with peas. Between day 12 and day 17, concentrations of other inorganic ions in the pea leaf apoplast increased abruptly, indicating the onset of cell disintegration. It is concluded that the differential salt sensitivity of pea and spinach cannot be traced back to a single plant performance. Major differences appear to be the inability of pea to control salt accumulation in the shoot, to maintain steep ion gradients across the leaf cell plasmalemma, and to synthesize compatible solutes. Perhaps less important is a lower selectivity of pea for K(+)/Na(+) and NO(3) (-)/Cl(-) uptake by roots.",1
"Speer, M, Kaiser, W M",2
Environmental Control of Phosphoenolpyruvate Carboxylase Induction in Mature Mesembryanthemum crystallinum L.,0
"Mesembryanthemum crystallinum L. plants shift the mode of carbon assimilation from C(3) to Crassulacean acid metabolism when stressed by high salinity. A prerequisite for Crassulacean acid metabolism induction is the synthesis of phosphoenolpyruvate carboxylase (PEPCase). A moderate increase in the abundance of PEPCase transcripts and activity is observed in 7-week-old, well-watered plants. This increase in PEPCase coincides in time with a decrease in the growth rate of the shoots. The steady-state level of PEPCase activity is uniform along the leaves of well-watered plants, as can be shown by comparing leaves of different age from individual 7-week-old plants. In contrast, the rate of induction in response to salt stress varies with the age of plants and to a lesser extent with the age of the leaves. Two-week-old seedlings induce PEPCase slowly under a moderate salt stress regimen, whereas older plants induce faster. When individual leaves from a seven-week-old plant are compared with respect to induction velocity, no clear-cut correlation with leaf age is apparent. The highest induction rate is observed in leaves from node five that are about 2 weeks old at the beginning of the experiment. PEPCase transcripts are readily down-regulated to minute levels when detached leaves are hydrated. The levels reached after 8 hours of rehydration are very similar, regardless of whether the leaves were cut from young or old plants or whether the plants were previously salt-stressed or well-watered. It is concluded that environmental rather than developmental factors are predominant in determining abundance of PEPCase activity and transcripts in leaves of mature M. crystallinum plants.",1
"Piepenbrock, M, Schmitt, J M",2
Genetic tests of the roles of the embryonic ureases of soybean.,0
"We assayed the in vivo activity of the ureases of soybean (Glycine max) embryos by genetically eliminating the abundant embryo-specific urease, the ubiquitous urease, or a background urease. Mutant embryos accumulated urea (250-fold over progenitor) only when lacking all three ureases and only when developed on plants lacking the ubiquitous urease. Thus, embryo urea is generated in maternal tissue where its accumulation is not mitigated by the background urease. However, the background urease can hydrolyze virtually all urea delivered to the developing embryo. Radicles of 2-day-old germinants accumulated urea in the presence or absence of the embryo-specific urease (2 micromoles per gram dry weight radicle). However, mutants lacking the ubiquitous urease exhibited increased accumulation of urea (to 4-5 micromoles urea per gram dry weight radicle). Thus, the ubiquitous and not the embryo-specific urease hydrolyzes urea generated during germination. In the absence of both of these ureases, the background urease activity (4% of ubiquitous urease) may hydrolyze most of the urea generated. A pleiotropic mutant lacking all urease accumulated 34 micromoles urea per gram dry weight radicle (increasing 2.5-fold at 3 days after germination). Urea (20 millimolar) was toxic to in vitro-cultured cotyledons which contained active embryo-specific urease. Cotyledons lacking the embryo-specific urease accumulated more protein when grown with urea than with no nitrogen source. Among cotyledons lacking the embryo-specific urease, fresh weight increases were virtually unchanged whether grown on urea or on no nitrogen and whether in the presence or absence of the ubiquitous urease. However, elimination of the ubiquitous urease reduced protein deposition on urea-N, and elimination of both the ubiquitous and background ureases further reduced urea-derived protein. The evidence is consistent with the lack of a role in urea hydrolysis for the embryo-specific urease in developing embryos or germinating seeds. Because the embryo-specific urease is deleterious to cotyledons cultured in vitro on urea-N, its role may be to hydrolyze urea in wounded or infected embryos, creating a hostile environment for pest or pathogen. While the ubiquitous urease is operative in leaves and in seedlings, all or most of its function can be assumed by the background urease in embryos and in seedlings.",1
"Stebbins, N, Holland, M A, Cianzio, S R, Polacco, J C",2
Fluorescence Study of Chemical Modification of Phosphoenolpyruvate Carboxylase from Crassula argentea.,0
"The chemical modification of phosphoenolpyruvate carboxylase purified from Crassula argentea leaves was studied using the fluorescence of the extrinsic probe 8-anilino-1-naphalenesulfonate. The effects of ligands on kinetic parameters of phosphoenolpyruvate carboxylase activity, and its response to pH and metal cations, were associated with the binding of the ligands to the enzyme as measured by fluorescence. Binding of the ligands phosphoenolpyruvate, malate, and glucose-6-phosphate revealed by fluorescence measurements corresponds to competitive phenomena observed in kinetic studies. The fluorescence measurements also suggest the involvement of specific amino acids in the binding of a given ligand. Arginyl residues modified by 2,3-butanedione appear to be directly involved in the binding of phosphoenolpyruvate and malate to the active and the inhibition sites, respectively. A histidyl residue was involved in the binding of malate, accounting for the lack of inhibition by malate in kinetic studies of the enzyme treated with diethylpyrocarbonate. Although activity was lost, there was no decrease in the ability of the treated enzyme to bind phosphoenolpyruvate, suggesting that additional histidyl residues are essential for activity although not directly involved in the binding of phosphoenolpyruvate. The lysine reagent trinitrobenzenesulfonate caused a loss of activity and a reduction in malate inhibition and glucose-6-phosphate activation, but these modifications were not related to changes in the ability of the enzyme to bind any of the three ligands. This suggests that lysine residues were not directly involved in the binding of these ligands.",1
"Rustin, P, Meyer, C R, Wedding, R T",2
Vegetative storage proteins in poplar : induction and characterization of a 32- and a 36-kilodalton polypeptide.,0
"Bark, wood, and root tissues of several Populus species contain a 32- and a 36-kilodalton polypeptide which undergo seasonal fluctuations and are considered to be storage proteins. These two proteins are abundant in winter and not detectable in summer as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection. An antibody raised against the 32-kilodalton storage protein of Populus trichocarpa (T. & G.) cross-reacts with the 36-kilodalton protein of this species. The synthesis of the 32- and 36-kilodalton proteins can be induced in micropropagated plants by short-day conditions in the growth chamber. These proteins are highly abundant in structural roots, bark, and wood and combined represent >25% of the total soluble proteins in these tissues. Nitrate concentration in the leaves and nitrate uptake rate decreased dramatically when LD plants were transferred to short-day conditions; the protein content in leaves was unaffected. A decrease of the 32- and 36-kilodalton polypeptides occurs after transferring induced plants back to LD conditions. Both polypeptides are glycosylated and can be efficiently purified by affinity chromatography using concanavalin A-Sepharose 4B. The 32- and the 36-kilodalton polypeptides have identical basic isoelectric points and both consist of at least three isoforms. The storage proteins show a loss in apparent molecular mass after deglycosylation with trifluoromethanesulfonic acid. It is concluded that the 32- and 36-kilodalton polypeptides are glycoforms differing only in the extent of glycosylation. The relative molecular mass of the native storage protein was estimated to be 58 kilodalton, using gel filtration. From the molecular mass and the elution pattern it is supposed that the storage protein occurs as a heterodimer composed of one 32- and one 36-kilodalton subunit. Preliminary data suggest the involvement of the phytochrome system in the induction process of the 32- and 36-kilodalton polypeptides.",1
"Langheinrich, U, Tischner, R",2
Cross-Resistance to Herbicides in Annual Ryegrass (Lolium rigidum) : III. On the Mechanism of Resistance to Diclofop-Methyl.,0
"Annual ryegrass (Lolium rigidum) biotype SLR 31 is resistant to the postemergent graminicide methyl-2-[4-(2,4-dichlorophenoxy)phenoxy]-propanoate (diclofop-methyl). Uptake of [(14)C](U-phenyl)diclofop-methyl and root/shoot distribution of radioactivity in susceptible and resistant plants were similar. In both biotypes, diclofop-methyl was rapidly demethylated to the biocidal metabolite diclofop acid which, in turn, was metabolized to ester and aryl-O-sugar conjugates. Susceptible plants accumulated 5 to 15% more radioactivity in dicloflop acid than did resistant plants. Resistant plants had a slightly greater capacity to form nonbiocidal sugar conjugates. Despite these differences, resistant plants retained 20% of (14)C in the biocidal metabolite diclofop acid 192 hours after treatment, whereas susceptible plants, which were close to death, retained 30% in diclofop acid. The small differences in the pool sizes of the active and inactive metabolites are by themselves unlikely to account for a 30-fold difference in sensitivity to the herbicide at the whole plant level. Similar high-pressure liquid chromatography elution patterns of conjugates from both susceptible and resistant biotypes indicated that the mechanisms and the products of catabolism in the biotypes are similar. It is suggested that metabolism of diclofop-methyl by the resistant biotype does not alone explain resistance observed at the whole-plant level. Diclofop acid reduced the electrochemical potential of membranes in etiolated coleoptiles of both biotypes; 50% depolarization required 1 to 4 mum diclofop acid. After removal of diclofop acid, membranes from the resistant biotype recovered polarity, whereas membranes from the susceptible biotype did not. Internal concentrations of diclofop acid 4 h after exposing plants to herbicide were estimated to be 36 to 39 micromolar in a membrane fraction and 16 to 17 micromolar in a soluble fraction. Such concentrations should be sufficient to fully depolarize membranes. It is postulated that differences in the ability of membranes to recover from depolarization are correlated with the resistance response of biotype SLR 31.",1
"Holtum, J A, Matthews, J M, Häusler, R E, Liljegren, D R, Powles, S B",2
Cross-Resistance to Herbicides in Annual Ryegrass (Lolium rigidum): IV. Correlation between Membrane Effects and Resistance to Graminicides.,0
"The herbicidally active aryloxyphenoxypropionates diclofop acid, haloxyfop acid, and fluazifop acid and the cyclohexanedione sethoxydim depolarized membranes in coleoptiles of eight biotypes of herbicide-susceptible and herbicide-resistant annual ryegrass (Lolium rigidum). Membrane polarity was reduced from -100 millivolts to -30 to -50 millivolts. Membranes repolarized after removal of the compounds only in biotypes with resistance to the compound added. Repolarization was not observed in herbicide-susceptible L. rigidum, nor was it observed in biotypes resistant to triazine, triazole, triazinone, phenylurea, or sulfonylurea herbicides but not resistant to aryloxyphenoxypropionates and cyclohexanediones. Chlorsulfuron, a sulfonylurea herbicide, at a saturating concentration of 1 micromolar, reduced membrane polarity in all biotypes studied by only 15 millivolts. The recovery of membrane potential following the removal of chlorsulfuron was restricted to chlorsulfuron-susceptible and -resistant biotypes that did not exhibit diclofop resistance. These differences in membrane responses are correlated with resistance to dicloflop rather than with resistance to chlorsulfuron. It is suggested that the differences may reflect altered membrane properties of diclofop-resistant biotypes. Further circumstantial evidence for dissimilarity of properties of membranes from diclofop-resistant and diclofop-susceptible ryegrass is provided by observations that K(+)/Na(+) ratios were significantly higher in coleoptiles from diclofop-resistant biotypes than in coleoptiles from susceptible plants. Intact and excised roots from susceptible biotypes were capable of acidifying the external medium, whereas roots from resistant biotypes were unable to do so. The ineluctable conclusion is that in L. rigidum the phenomena of membrane repolarization and resistance to aryloxyphenoxypropionate and cyclohexanedione herbicides are correlated.",1
"Häusler, R E, Holtum, J A, Powles, S B",2
"Oilbody Proteins in Microspore-Derived Embryos of Brassica napus: Hormonal, Osmotic, and Developmental Regulation of Synthesis.",0
"A number of treatments were tested for their ability to affect the synthesis of oilbody proteins in microspore-derived embryos of rapeseed (Brassica napus). Synthesis of the oilbody proteins was determined by [(35)S]methionine incorporation in vivo and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of washed oilbody fractions. Oilbody proteins of approximately 19, 23, and 32 kilodaltons were found to be prominent. These proteins showed differential patterns of regulation. The 19 and 23 kilodalton proteins (oleosins) were greatly enhanced by treatments with abscisic acid, jasmonic acid, and osmotic stress imposed using sorbitol (12.5%). Synthesis of the 32 kilodalton protein was inhibited by abscisic acid and by sorbitol (12.5%), but unaffected by jasmonates. The strong promotion of synthesis of the 19 and 23 kilodalton oilbody proteins appeared to be specific as they are not seen with gibberellic acid treatment or with a stress such as heat shock. Time course experiments revealed that the abscisic acid stimulation of oleosin synthesis is quite rapid (less than 2 hours), reaching a maximum at 6 to 8 hours. The response of the oleosins to abscisic acid is found in all stages of embryogenesis, with a major increase in synthetic rates even in globular embryos on abscisic acid treatment. This suggests that these proteins may accumulate much earlier in embryogenesis than has previously been believed. The 32 kilodalton oilbody-associated protein appears different from the oleosins in several ways, including its distinct pattern of regulation and its unique property, among the oilbody proteins, of undergoing phosphorylation.",1
"Holbrook, L A, van Rooijen, G J, Wilen, R W, Moloney, M M",2
"Hydroperoxide Lyase and Other Hydroperoxide-Metabolizing Activity in Tissues of Soybean, Glycine max.",0
"Hydroperoxide lyase (HPLS) activity in soybean (Glycine max) seed/seedlings, leaves, and chloroplasts of leaves required detergent solubilization for maximum in vitro activity. On a per milligram of protein basis, more HPLS activity was found in leaves, especially chloroplasts, than in seeds or seedlings. The total yield of hexanal from 13(S)-hydroperoxy-cis-9,trans-11-octadecadienoic acid (13S-HPOD) from leaf or chloroplast preparations was 58 and 66 to 85%, respectively. Because of significant competing hydroperoxide-metabolizing activities from other enzymes in seed/seedling preparations, the hexanal yields from this source were lower (36-56%). Some of the products identified from the seed or seedling preparations indicated that the competing activity was mainly due to both a hydroperoxide peroxygenase and reactions catalyzed by lipoxygenase. Different HPLS isozyme compositions in the seed/seedling versus the leaf/chloroplast preparations were indicated by differences in the activity as a function of pH, the K(m) values, relative V(max) with 13S-HPOD and 13(S)-hydroperoxy-cis-9,trans-11,cis-15-octadecatrienoic acid (13S-HPOT), and the specificity with different substrates. With regard to the latter, both seed/seedling and chloroplast HPLS utilized the 13S-HPOD and 13S-HPOT substrates, but only seeds/seedlings were capable of metabolizing 9(S)-hydroperoxy-trans-10,cis-12-octadecadienoic acid into 9-oxononanoic acid, isomeric nonenals, and 4-hydroxynonenal. From 13S-HPOD and 13S-HPOT, the products were identified as 12-oxo-cis-9-dodecenoic acid, as well as hexanal from 13S-HPOD and cis-3-hexenal from 13S-HPOT. In seed preparations, there was partial isomerization of the cis-3 or cis-9 into trans-2 or trans-10 double bonds, respectively.",1
"Gardner, H W, Weisleder, D, Plattner, R D",2
Carbon Assimilation and Leaf Water Status in Sugar Beet Leaves during a Simulated Natural Light Regimen.,0
"Carbon assimilation and leaf water status were studied in sugar beet (Beta vulgaris L., Klein E-type multigerm) leaves during a light period in which illumination either increased rapidly to full irradiance or changed gradually in a sinusoidal manner as generally occurs during a natural day. A light regimen that simulated the light of a natural day was produced by adjusting irradiance with a neutral-density filter under the control of a computer. Under this light regimen, photosynthesis, transpiration, and stomatal conductance followed the irradiance pattern very closely and ribulose bisphosphate carboxylase was nearly fully activated. When illumination was increased rapidly at the beginning of a light period, transpiration also increased quickly, causing leaves to wilt to some extent. The activation state of ribulose bisphosphate carboxylase increased to only 52%, but ribulose bisphosphate level was nearly twice as high as during the simulated natural day. In spite of the differences in activation state and ribulose bisphosphate levels, photosynthesis rates were very similar under both regimens. Nevertheless, differences in parameters between leaves under the two irradiance regimens can affect how a plant responds to internal or external factors, and therefore, the rate at which irradiance increases at the beginning of a light period is an important consideration when interpreting data.",1
"Geiger, D R, Shieh, W J, Lu, L S, Servaites, J C",2
Effect of N-(Phosphonomethyl)glycine on Carbon Assimilation and Metabolism during a Simulated Natural Day.,0
"The effects of N-(phosphonomethyl)glycine (glyphosate) on the regulation of carbon assimilation, metabolism, and translocation were studied in leaves of sugar beet (Beta vulgaris L., Klein E-type multigerm) under a light regimen that began with gradually increasing irradiance as generally occurs on a natural day. Soon after application, glyphosate caused a marked increase in ribulose bisphosphate and a decrease in phosphoglyceric acid. The response is most simply explained by direct inhibition of ribulose bisphosphate carboxylase activity. The extent of inhibition was small, and the carbon assimilation rate did not decrease. As predicted, photosynthesis declined within an hour after glyphosate was applied to leaves under gradually increasing light. Inhibition resulted from a decrease in ribulose bisphosphate due to depletion of carbon from the photosynthetic carbon reduction cycle. Photoinhibition, a light-dependent limitation of photosynthetic capacity, appeared to be necessary for marked glyphosate-induced inhibition of photosynthesis. As a result, photosynthesis rate increased with irradiance until it exceeded 400 micromoles per square meter per second but then declined as the light level increased beyond 500 micromoles per square meter per second. Glyphosate changed the allocation of newly fixed carbon between starch and sucrose for export. Changes in the levels of ribulose bisphosphate and phosphoglyceric acid produced important effects on the regulation of carbon assimilation and metabolism.",1
"Shieh, W J, Geiger, D R, Servaites, J C",2
Regulation of photosynthetic carbon reduction cycle by ribulose bisphosphate and phosphoglyceric Acid.,0
"The activation states of a number of chloroplastic enzymes of the photosynthetic carbon reduction cycle and levels of related metabolites were measured in leaves of sugar beet (Beta vulgaris L., Klein E-type multigerm) under slowly changing irradiance during a day. The activation states of both phosphoribulokinase and NADP(+)-glyceraldehyde-3-phosphate dehydrogenase increased early in the light period and remained constant during the middle of the day. Initial ribulose 1,5-bisphosphate carboxylase activity was already about one third of the midday level, did not change for the first 2 hours, but then increased in parallel with the rate of carbon fixation. Because the activation states increased by turns, first phosphoribulokinase and NADP(+)-glyceraldehyde-3-phosphate dehydrogenase and later ribulose 1,5-bisphosphate carboxylase, the ratios of the activation states changed remarkably. Levels of ribulose bisphosphate and phosphoglycerate, which were high enough to affect enzyme reaction rates and changed in concert with activation state, indicate that these metabolites are involved in feedback/feedforward regulation of enzymes of carbon assimilation. This regulatory sequence is able to explain how the reaction rates for the enzymes of carbon assimilation are adjusted to maintain their activities in balance with each other and with the flux of carbon fixation.",1
"Servaites, J C, Shieh, W J, Geiger, D R",2
Action Spectrum for Resetting the Circadian Phototaxis Rhythm in the CW15 Strain of Chlamydomonas: II. Illuminated Cells.,0
"The action spectrum for resetting the phase of the circadian clock in Chlamydomonas reinhardtii is different depending upon whether the light stimuli are presented to cells that were in darkness versus dim illumination before stimulation. In this report, we show that phase resetting of illuminated cells appears to be mediated by components of the photosynthetic apparatus. This conclusion is based upon the action spectrum for phase-shifting illuminated cells (which looks like that for photosynthesis) and upon the fact that inhibitors of photosynthetic electron transport also inhibit the light-induced phase shift of illuminated cells. Both of these characteristics differ from that of cells taken from darkness. We, therefore, believe that at least two resetting pathways for this circadian clock exist and that both of these pathways are ecologically significant.",1
"Johnson, C H, Kondo, T, Hastings, J W",2
Inward Rectifying K Channels in the Plasma Membrane of Arabidopsis thaliana.,0
"Ion channels in the plasma membrane of protoplasts isolated from cultured cells of Arabidopsis thaliana were studied by means of the patch-clamp technique applied in the whole-cell configuration. In some protoplasts, depolarizing pulses and, in other protoplasts, hyperpolarizing pulses elicited time-dependent currents; both kinds of current were only rarely observed in the same protoplast. The hyperpolarization-activated inward rectifying currents, the focus of this paper, appeared to be due to the relatively slow opening of channels (activation time constant = 150 to 300 milliseconds), which closed at positive potentials. The reversal potential of this current, measured in the presence of different ion concentrations (symmetrical or asymmetrical K(+) and Cl(-) or gluconate), was always close to the electrochemical equilibrium potential of K(+). The currents were inhibited by 10 millimolar tetraethylammonium, a K(+) channel blocker. These data show that the hyperpolarization-activated currents flow through K(+) channels, which can provide a pathway for the passive diffusion of K(+) down its electrochemical gradient.",1
"Colombo, R, Cerana, R",2
Effects of Salinity on Water Transport of Excised Maize (Zea mays L.) Roots.,0
"The root pressure probe was used to determine the effects of salinity on the hydraulic properties of primary roots of maize (Zea mays L. cv Halamish). Maize seedlings were grown in nutrient solutions modified by additions of NaCl and/or extra CaCl(2) so that the seedlings received one of four treatments: Control, plus 100 millimolar NaCl, plus 10 millimolar CaCl(2), plus 100 millimolar NaCl plus 10 millimolar CaCl(2). The hydraulic conductivities (Lp(r)) of primary root segments were determined by applying gradients of hydrostatic and osmotic pressure across the root cylinder. Exosmotic hydrostatic Lp(r) for the different treatments were 2.8, 1.7, 2.8, and 3.4.10(-7) meters per second per megapascals and the endosmotic hydrostatic Lp(r) were 2.4, 1.5, 2.7, and 2.3.10(-7) meters per second per megapascals, respectively. Exosmotic Lp(r) of the osmotic experiments were 0.55, 0.38, 0.68, and 0.60.10(-7) meters per second per megapascals and the endosmotic Lp(r) were 0.53, 0.21, 0.56, and 0.54.10(-7) meters per second per megapascals, respectively. The osmotic Lp(r) was significantly smaller (4-5 times) than hydrostatic Lp(r). However, both hydrostatic and osmotic Lp(r) experiments showed that salinization of the growth media at regular (0.5 millimolar) calcium levels decreased the Lp(r) significantly (30-60%). Addition of extra calcium (10 millimolar) to the salinized media caused ameliorative effects on Lp(r). The low Lp(r) values may partially explain the reduction in root growth rates caused by salinity. High calcium levels in the salinized media increased the relative availability of water needed for growth. The mean reflection coefficients of the roots using NaCl were between 0.64 and 0.73 and were not significantly different for the different treatments. The mean values of the root permeability coefficients to NaCl of the different treatments were between 2.2 and 3.5.10(-9) meters per second and were significantly different only in one of four treatments. Cutting the roots successively from the tip and measuring the changes in the hydraulic resistance of the root as well as staining of root cross-sections obtained at various distances from the root tip revealed that salinized roots had mature xylem elements closer to the tip (5-10 millimeters) compared with the controls (30 millimeters). Our results demonstrate that salinity has adverse effects on water transport and that extra calcium can, in part, compensate for these effects.",1
"Azaizeh, H, Steudle, E",2
Water Relations of Pachysandra Leaves during Freezing and Thawing : Evidence for a Negative Pressure Potential Alleviating Freeze-Dehydration Stress.,0
"The evergreen herb Pachysandra terminalis becomes moderately frost-hardy in winter. The water relations of its frost-hardy leaves were studied during a freeze-thaw cycle. Leaf water potentials, measured by psychrometry at subfreezing temperatures, were identical with those of ice, indicating equilibrium freezing. Microscopic observations showed extracellular freezing of tissue water. As evidenced by thermal analysis, the freezing process starts with the crystallization of a minor volume which was identified as apoplasmic water. The following long-lasting exotherm indicated slow export of water from the protoplasts driven by extracellular crystallization. In partially frozen leaves, the fractions of liquid water were measured at several subfreezing temperatures by nuclear magnetic resonance spectroscopy. They were consistently greater than those calculated from the osmotic potentials of cellular fluid, and the differences increased with decreasing temperature. About 50% of the differences could be abolished by freeze-killing of the leaf and was thus ascribed to the effect of a (negative) pressure reinforcing the osmotic potential. The persistent part of the differences may have reflected a matric component. At -7 degrees C, the absolute values of both potentials were -1.7 megapascals each. The water relations of Pachysandra leaves clearly indicate nonideal equilibrium freezing where negative pressures and matric potentials contribute to the leaf water potential and thus alleviate freeze-dehydration of the tissue.",1
"Zhu, J J, Beck, E",2
Computer-simulated evaluation of possible mechanisms for quenching heavy metal ion activity in plant vacuoles: I. Cadmium.,0
"Various mechanisms have been suggested for the quenching of Cd ion activity in plant vacuoles. These include solution complexation with organic acids and sulfhydryl-containing peptides and precipitation as sulfides. Because direct experimental support for these mechanisms is lacking and difficult to obtain, we have used a computer model to evaluate the quenching role of possible organic and inorganic ligands of tobacco cultured cells exposed to Cd. Results of this thermodynamic evaluation, which assumes that a chemical equilibrium state is met in the vacuole, support the conclusion that sulfhydryl-containing peptides and certain organic acids may form soluble Cd complexes. Although complexation of malate and oxalate with Cd is predicted to be less significant, citrate in the concentration range encountered in the tobacco cultured cell vacuoles has high potential for forming soluble complexes with Cd over the entire possible vacuolar pH range, especially 4.3 to 7.0, even in the presence of low levels of Cd-binding peptides. In addition, results show that inorganic chloride, sulfide (if present), and phosphate may also act to sequester Cd ion activity in the vacuole by forming soluble Cd-Cl and insoluble CdS and Cd-phosphate.",1
"Wang, J, Evangelou, B P, Nielsen, M T, Wagner, G J",2
Induction by Electric Currents of Ethylene Biosynthesis in Cucumber (Cucumis sativus L.) Fruit.,0
"The effects of an electric current on ethylene biosynthesis were investigated in cucumber (Cucumis sativus L.) fruit that were producing almost no ethylene. Direct currents at 0.5 to 3.0 milliamperes induced much ethylene synthesis, with a rapid continuous increase in the rate, which reached a peak within 5 to 6 hours and then decreased. The rate of production was greater with a stronger current. Ethylene production was not observed after the use of a sine-wave alternating current (60 hertz) at 3 milliamperes, the magnitude at which a direct current had the greatest effect. The activity of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ethylene forming enzyme (EFE) increased before the rise in ethylene production. ACC synthase and EFE were activated sixfold and fourfold, respectively, by 2 hours. The concentration of ACC increased linearly up to 6 hours and then decreased. Ethylene induction by an electric current was suppressed almost completely by the infiltration of the cucumbers with 5 millimolar aminooxyacetic acid, an inhibitor of ACC synthase, and was also suppressed 70% by 5 millimolar salicylic acid, an inhibitor of EFE. The results indicate that the ethylene induced by the direct current was synthesized via the ACC-ethylene pathway as a result of electrical stress, a new kind of stress to be identified.",1
"Inaba, A, Gao, J P, Nakamura, R",2
Physiology of Hormone Autonomous Tissue Lines Derived From Radiation-Induced Tumors of Arabidopsis thaliana.,0
"gamma-Radiation-induced tumors of Arabidopsis thaliana L. have been produced as a novel approach to isolation of genes that regulate plant development. Tumors excised from irradiated plants are hormone autonomous in culture and have been maintained on hormone-free medium for up to 4 years. Five tumor tissue lines having different morphologies and growth rates were analyzed for auxin, cytokinin, and 1-aminocyclopropane-1-carboxylic acid (ACC) content, ethylene production, and response to exogenous growth regulators. Normal tissues and two crown gall tissue lines were analyzed for comparison. Rosettes and whole seedlings each contained approximately 30 nanograms. (gram fresh weight)(-1) free indoleacetic acid (IAA), 150 nanograms. (gram fresh weight)(-1) ester-conjugated IAA, and 10 to 20 micrograms. (gram fresh weight)(-1) amide-conjugated IAA. The crown gall lines contained similar amounts of free and ester-conjugated IAA but less amide conjugates. Whereas three of the radiation-induced tumor lines had IAA profiles similar to normal tissues, one line had 10- to 100-fold more free IAA and three- to 10-fold less amide-conjugated IAA. The fifth line had normal free IAA levels but more conjugated IAA than control tissues. Whole seedlings contained approximately 2 nanograms. (gram fresh weight)(-1) of both zeatin riboside and isopentenyladenosine. The crown gall lines had 100- to 1000-fold higher levels of each cytokinin. In contrast, the three radiation-induced tumor lines analyzed contained cytokinin levels similar to the control tissue. The radiation-induced tumor tissues produced very little ethylene, although each contained relatively high levels of ACC. Normal callus contained similar amounts of ACC but produced several times more ethylene than the radiation-induced tumor lines. Each of the radiation-induced tumor tissues displayed a unique set of responses to exogenously supplied growth regulators. Only one tumor line showed the same response as normal callus to both auxin and cytokinin feeding. In some cases, one or more tumor lines showed increased sensitivity to certain growth substances. In other cases, growth regulator feeding had no significant effect on tumor tissue growth. Morphology of the radiation-induced tumor tissues generally did not correlate with auxin to cytokinin ratio in the expected manner. The results suggest that a different primary genetic event led to the formation of each tumor and that growth and differentiation in the tumor tissue lines are uncoupled from the normal hormonal controls.",1
"Campell, B R, Town, C D",2
Localization of a protease in protoplast preparations in infected cells of French bean nodules.,0
"Protoplasts from infected and uninfected cells were isolated from the central nitrogen fixing tissue of French bean (Phaseolus vulgaris L. cv Contender) root nodules. Successive filtrations allowed the separation of the infected cells, whereas the small uninfected cells were isolated on a discontinuous Percoll gradient. Higher yields of intact protoplasts were obtained from young (4-week-old) nodules whereas no protoplasts could be isolated from the oldest nodules. When proteolysis was determined in the cytosolic fraction of both infected and uninfected cells, at pH 5.0 and 8.0, with leghemoglobin or azocasein as substrate, activity was present only in infected cell protoplasts and increased with nodule age. A protease with an acidic pH optimum, mainly responsible for this increasing activity, was highly purified from senescing nodules by electro-elution after nondenaturing polyacrylamide gel electrophoresis and used to produce polyclonal antibodies. Western blots of nodule protein separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and probed with purified anti-protease immunoglobulin G showed the molecular mass of the protease to be 58 kilodaltons. Blots also confirmed that protease protein was located in infected cell protoplasts only, regardless of nodule age.",1
"Pladys, D, Dimitrijevic, L, Rigaud, J",2
Ethylene Biosynthesis-Inducing Endoxylanase Is Translocated through the Xylem of Nicotiana tabacum cv Xanthi Plants.,0
"Ethylene biosynthesis-inducing xylanase (EIX) from the fungus Trichoderma viride elicits enhanced ethylene production and tissue necrosis in whole tobacco (Nicotiana tabacum cv Xanthi) plants at sites far removed from the point of EIX application when applied through a cut petiole. Symptoms develop in a specific pattern, which appears to be determined by the interconnections of the tobacco xylem. Based on results of tissue printing experiments, EIX enters the xylem of the stem from the point of application and rapidly moves up and down the stem, resulting in localized foliar symptoms on the treated side of the plant above and below the point of EIX application. The observation that a fungal protein that elicits plant defense responses can be translocated through the xylem suggests that plants respond to pathogen-derived extracellular proteins in tissues distant from the invading pathogen.",1
"Bailey, B A, Taylor, R, Dean, J F, Anderson, J D",2
Autotrophy in maize husk leaves : evaluation using natural abundance of stable isotopes.,0
"The natural abundance of carbon and hydrogen isotopic composition, expressed as a delta(13)C value of plant dry matter and cellulose in the hypsophylls (husk leaves) of maize (Zea mays L.) was measured and compared with that of leaves and cobs. The delta(13)C values of outer hypsophylls were usually 2 to 3% per thousand more negative than leaves or other tissues, and became more negative with increasing chlorophyll content, indicating significant local C(3) pathway fixation of CO(2) in the outer hypsophylls. The deltaD values indicated a significant part of hypsophyll cellulose was derived from heterotrophic sources (sucrose from C(4) photosynthesis in other tissues). Isotopic mass balance calculations allowed quantitative estimation of these carbon sources and, in the samples examined, about 16% of hypsophyll cellulose was derived from local C(3) photosynthesis, about 62% from local C(4) photosynthesis, and about 22% from sucrose imported from other leaves.",1
"Yakir, D, Osmond, B, Giles, L",2
Light Microscopy Study of Nodule Initiation in Pisum sativum L. cv Sparkle and in Its Low-Nodulating Mutant E2 (sym 5).,0
"We compared nodule initiation in lateral roots of Pisum sativum (L.) cv Sparkle and in a low-nodulating mutant E2 (sym 5). In Sparkle, about 25% of the infections terminated in the epidermis, a similar number stopped in the cortex, and 50% resulted in the formation of a nodule meristem or an emerged nodule. The mutant E2 (sym 5) was infected as often as was the parent, and it formed a normal infection thread. In the mutant, cell divisions rarely occurred in advance of the infection thread, and few nodule primordia were produced. Growing the mutant at a low root temperature or adding Ag(+) to the substrate increased the number of cell divisions and nodule primordia. We conclude that, in the E2 line, the infection process is arrested in the cortex, at the stage of initial cell divisions before the establishment of a nodule primordium.",1
"Guinel, F C, Larue, T A",2
Evidence for a highly specific k/h antiporter in membrane vesicles from oil-seed rape hypocotyls.,0
"We present evidence strongly suggesting that a proton gradient (acid inside) is used to drive an electroneutral, substrate-specific, K(+)/H(+) antiport in both tonoplast and plasma membrane-enriched vesicles obtained from oilseed rape (Brassica napus) hypocotyls. Proton fluxes into and out of the vesicles were monitored both by following the quenching and restoration of quinacrine fluorescence (indicating a transmembrane pH gradient) and of oxonol V fluorescence (indicating membrane potential.) Supply of K(+) (with Cl(-) or SCN(-)) after a pH gradient had been established across the vesicle membrane by provision of ATP to the H(+)-ATPase dissipated the transmembrane pH gradient but did not depolarize the positive membrane potential. Evidence that the K(+)/H(+) exchange thus indicated could not be accounted for by mere electric coupling included the findings that, first, no positive potential was generated when KSCN or KCl was supplied, even in the absence of 100 millimolar Cl(-) and, second, efflux of K(+) from K(+)-loaded vesicles drives intravesicular accumulation of H(+) against the electrochemical potential gradient. Neither was the exchange due to competition between K(+) and quinacrine for membrane sites, nor to inhibition of the H(+)-ATPase. Thus, it is likely that it was effected by a membrane component. The exchanger utilized primarily K(+) (at micromolar concentrations); Na(+)/H(+) antiport was detected only at concentrations two orders of magnitude higher. Rb(+), Li(+), or Cs(+) were ineffective. Dependence of tonoplast K(+)/H(+) antiport on K(+) concentration was complex, showing saturation at 10 millimolar K(+) and inhibition by concentrations higher than 25 millimolar. Antiport activity was associated both with tonoplast-enriched membrane vesicles (where the proton pump was inhibited by more than 80% by 50 millimolar NO(3) (-) and showed no sensitivity to vanadate or oligomycin) and with plasma membrane-enriched fractions prepared by phase separation followed by separation on a sucrose gradient (where the proton pump was vanadate and diethylstilbestrol-sensitive but showed no sensitivity to NO(3) (-) or oligomycin). The possible physiological role of such a K(+)/H(+) exchange mechanism is discussed.",1
"Cooper, S, Lerner, H R, Reinhold, L",2
Nitrate inhibition of nodulation can be overcome by the ethylene inhibitor aminoethoxyvinylglycine.,0
"Previously, we reported (a) a positive correlation between the nitrate concentrations in growth medium and ethylene evolved from uninoculated and inoculated alfalfa (Medicago sativa) roots and (b) a negative correlation between ethylene evolution and nodulation. Here, we report that the inhibitory effect of NO(3) (-) on nodulation of alfalfa can be eliminated by the ethylene inhibitor aminoethoxyvinylglycine (AVG). This effect was probably related to the strong inhibition (90%) of ethylene biosynthesis caused by AVG in these inoculated and NO(3) (-)-treated roots. These results support our hypothesis that the inhibitory effect of NO(3) (-) is mediated through the phytohormone ethylene. A possible role of endogenous ethylene in the autoregulation of nodulation also is discussed. AVG at 10 micromolar significantly (P < 0.05) increased total nitrogenase activity (acetylene reduction) in 2.5 and 5 millimolar NO(3) (-)-fed plants probably as a result of the very high stimulation of nodulation.",1
"Ligero, F, Caba, J M, Lluch, C, Olivares, J",2
Amine Accumulation in Acidic Vacuoles Protects the Halotolerant Alga Dunaliella salina Against Alkaline Stress.,0
"Amines at alkaline pH induce in cells of the halotolerant alga Dunaliella a transient stress that is manifested by a drop in ATP and an increase of cytoplasmic pH. As much as 300 millimolar NH(4) (+) are taken up by the cells at pH 9. The uptake is not associated with gross changes in volume and is accompanied by K(+) efflux. Most of the amine is not metabolized, and can be released by external acidification. Recovery of the cells from the amine-induced stress occurs within 30 to 60 minutes and is accompanied by massive swelling of vacuoles and by release of the fluorescent dye atebrin from these vacuoles, suggesting that amines are compartmentalized into acidic vacuoles. The time course of ammonia uptake into Dunaliella cells is biphasic-a rapid influx, associated with cytoplasmic alkalinization, followed by a temperature-dependent slow uptake phase, which is correlated with recovery of cellular ATP and cytoplasmic pH. The dependence of amine uptake on external pH indicates that it diffuses into the cells in the free amine form. Studies with lysed cell preparations, in which vacuoles become exposed but retain their capacity to accumulate amines, indicate that the permeability of the vacuolar membrane to amines is much higher than that of the plasma membrane. The results can be retionalized by assuming that the initial amine accumulation, which leads to rapid vacuolar alkalinization, activates metabolic reactions that further increase the capacity of the vacuoles to sequester most of the amine from the cytoplasm. The results indicate that acidic vacuoles in Dunaliella serve as a high-capacity buffering system for amines, and as a safeguard against cytoplasmic alkalinization and uncoupling of photosynthesis.",1
"Pick, U, Zeelon, O, Weiss, M",2
Polyphosphate Hydrolysis within Acidic Vacuoles in Response to Amine-Induced Alkaline Stress in the Halotolerant Alga Dunaliella salina.,0
"The location and mobilization of polyphosphates in response to an amine-induced alkaline stress were studied in the halotolerant alga Dunaliella salina. The following observations suggest that polyphosphates accumulate in acidic vacuoles: (a) Accumulation of large amounts of polyphosphates is manifested as intravacuolar dense osmiophilic bodies in electron micrographs. (b) Uptake of amines into the vacuoles induces massive hydrolysis of polyphosphates, demonstrated by in vivo(31)P-nuclear magnetic resonance, and by analysis of hydrolytic products on thin layer chromatograms. The analysis indicates that: (a) Polyphosphate hydrolysis is kinetically correlated with amine accumulation and with the recovery of cytoplasmic pH. (b) The major hydrolytic product is tripolyphosphate. (c) The peak position of the tripolyphosphate terminal phosphate in nuclear magnetic resonance spectra is progressively shifted as the cells recover, indicating that the pH inside the vacuoles increases while the pH in the cytoplasm decreases. (d) In lysed cell preparations, in which vacuoles become exposed to the external pH, mild alkalinization in the absence of amines induces polyphosphate hydrolysis to tripolyphosphates. It is suggested that amine accumulation within vacuoles activates a specific phosphatase, which hydrolyzes long-chain polyphosphates to tripolyphosphates. The hydrolysis increases the capacity of the vacuoles to sequester amines from the cytoplasm probably by releasing protons required to buffer the amine, and leads to recovery of cytoplasmic pH. Thus, polyphosphate hydrolysis provides a high-capacity buffering system that sustains amine compartmentation into vacuoles and protects cytoplasmic pH.",1
"Pick, U, Weiss, M",2
Hydrolysis of polyphosphates and permeability changes in response to osmotic shocks in cells of the halotolerant alga dunaliella.,0
"The effects of osmotic shocks on polyphosphates and on the vacuolar fluorescent indicator atebrin have been investigated to test whether acidic vacuoles in the halotolerant alga Dunaliella salina have a role in osmoregulation. Upshocks and downshocks induce different patterns of polyphosphate hydrolysis. Upshocks induce rapid formation of new components, tentatively identified as 5 or 6 linear polyphosphates, formed only after upshocks with NaCl and not with glycerol, indicative of compartmentation of Na(+) into the vacuoles. Conversely, downshocks induce a slower transient accumulation of tripolyphosphates, indicating activation of a different hydrolytic process within the vacuoles. Osmotic shocks do not lead to release of atebrin from acidic vacuoles, indicating that they do not induce a major intravacuolar alkalinization. However, osmotic shocks induce transient permeability changes measured by amine-induced atebrin release from vacuoles. Hypoosmotic shocks transiently increase the permeability (up to 20-fold), whereas hyperosmotic shocks induce a rapid drop in permeability. Electron micrographs of osmotically shocked cells also reveal transient changes in the surface and internal organelles of D. salina cells. It is suggested that hyperosmotic and hypoosmotic shocks induce different changes within acidic vacuoles and in the organization and/or composition of the plasma membrane in Dunaliella.",1
"Weiss, M, Bental, M, Pick, U",2
Sucrose synthase and invertase in isolated vascular bundles.,0
"Vascular bundles were isolated from grapefruit (Citrus paradisi Macf.) during periods of rapid sucrose translocation into fruit. Invertase and sucrose synthase activities were assayed in these strands and compared with immediately adjacent tissues (inner most peel and segment epidermis) and phloem-free juice sacs during four growing seasons. Although sucrose synthase was present in sink cells, the significantly greater activity in vascular strands (per unit fresh weight and protein) indicated that the role of this enzyme in translocation may include a vascular function in addition to its proposed involvement in metabolism of importing cells.",1
"Tomlinson, P T, Duke, E R, Nolte, K D, Koch, K E",2
Jasmonic Acid induces tuberization of potato stolons cultured in vitro.,0
"The aim of the study was to assess the potential in vitro effects of jasmonic acid and kinetin on tuberization of potato (Solanum tuberosum). Of the two, the former was by far the stronger in vitro promoter of stolon tuberization. Number of tubers induced per stolon, tuberization rate, and final tuber weight were higher by factors of 2.8, 2.3, and 6.4, respectively. Bioassay sensitivity of jasmonic acid, measured in terms of the point at which the concentration for inducing tuberization was saturating, was more than 20 times greater than that of kinetin. Tuberization in both cases was associated with a decrease in rooting ability. Jasmonic acid also triggered a general state of induction throughout the stolon.",1
"Pelacho, A M, Mingo-Castel, A M",2
Effect of Hydrogen Cyanamide on Amino Acid Profiles in Kiwifruit Buds during Budbreak.,0
"Buds, and resultant shoots, were collected from kiwifruit (Actinidia deliciosa [A. Chev.] CF Liang et AR Ferguson var deliciosa cv Hayward) vines from late autumn until late spring with and without hydrogen cyanamide treatment. Those samples were weighed and analyzed for total nitrogen and free amino acids. By 7 days after hydrogen cyanamide treatment, the amount of proline had risen to nearly one-quarter of the total amino acid pool in the treated buds and that proportion was maintained for at least 14 days before it declined. The maximum concentration detected in treated buds was 25.8 micromoles per gram dry weight, 6.6 times that detected in untreated buds. By 95 days after treatment, the relative amounts of proline were not significantly different.",1
"Walton, E F, Clark, C J, Boldingh, H L",2
Abscisic Acid Negatively Regulates Expression of Chlorophyll a/b Binding Protein Genes during Soybean Embryogeny.,0
"The levels of abscisic acid (ABA) during embryogenesis in the soybean (Glycine max) cultivar Dare were quantitated. An increase in the quantity of ABA per cotyledon was correlated with a decrease in the chlorophyll a/b binding (Cab) protein gene mRNA population. Soybean cotyledons were cultured in vitro in the presence or absence of ABA. Quantitation of cotyledonary ABA levels and Cab mRNA levels indicated that the application of 5 x 10(-5) molar and 5 x 10(-6) molar exogenous ABA decreased Cab mRNA prevalences. S1 nuclease protection experiments demonstrated that exogenous ABA modulated the level of Cab3 mRNA. These data strongly suggest that one of the developmental regulators of Cab gene expression during soybean embryogeny is the plant hormone, ABA; ABA negatively regulates Cab mRNA accumulation.",1
"Chang, Y C, Walling, L L",2
Abrupt increase in the level of hydrogen peroxide in leaves of winter wheat is caused by cold treatment.,0
"After cold treatment of seedlings of winter wheat (Triticum aestivum L.), levels of hydrogen peroxide in the leaves were measured. The concentration of hydrogen peroxide increased to about three times the control level within a few minutes, and returned to the normal level in 15 to 20 minutes. The elevated level of hydrogen peroxide was found to be equivalent to 1.5 micromoles per gram fresh weight tissues of leaves.",1
"Okuda, T, Matsuda, Y, Yamanaka, A, Sagisaka, S",2
Purification and Characterization of Chorismate Synthase from Euglena gracilis: Comparison with Chorismate Synthases of Plant and Microbial Origin.,0
"Chorismate synthase was purified 1200-fold from Euglena gracilis. The molecular mass of the native enzyme is in the range of 110 to 138 kilodaltons as judged by gel filtration. The molecular mass of the subunit was determined to be 41.7 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified chorismate synthase is associated with an NADPH-dependent flavin mononucleotide reductase that provides in vivo the reduced flavin necessary for catalytic activity. In vitro, flavin reduction can be mediated by either dithionite or light. The enzyme obtained from E. gracilis was compared with chorismate synthases purified from a higher plant (Corydalis sempervirens), a bacterium (Escherichia coli), and a fungus (Neurospora crassa). These four chorismate synthases were found to be very similar in terms of cofactor specificity, kinetic properties, isoelectric points, and pH optima. All four enzymes react with polyclonal antisera directed against chorismate synthases from C. sempervirens and E. coli. The closely associated flavin mononucleotide reductase that is present in chorismate synthase preparations from E. gracilis and N. crassa is the main difference between those synthases and the monofunctional enzymes from C. sempervirens and E. coli.",1
"Schaller, A, van Afferden, M, Windhofer, V, Bülow, S, Abel, G, Schmid, J, Amrhein, N",2
Photosynthetic Characteristics of Rice Leaves Aged under Different Irradiances from Full Expansion through Senescence.,0
"Effects of irradiance on photosynthetic characteristics were examined in senescent leaves of rice (Oryza sativa L.). Two irradiance treatments (100 and 20% natural sunlight) were imposed after the full expansion of the 13th leaf through senescence. The photosynthetic rate was measured as a function of intercellular CO(2) pressure with a gas-exchange system. The amounts of cytochrome f, coupling factor 1, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), and chlorophyll were determined. The coupling factor 1 and cytochrome f contents decreased rapidly during senescence, and their rates of decrease were much faster from the 20% sunlight treatment than from the full sunlight treatment. These changes were well correlated with those in the photosynthetic rate at CO(2) pressure = 600 microbars, but not with those under the ambient air condition (350 microbars CO(2)) and 200 microbars CO(2). This suggested that the amounts of coupling factor 1 and cytochrome f from the full sunlight treatment cannot be limiting factors for the photosynthetic rate at ambient air conditions. The Rubisco content also decreased during senescence, but its decrease from the 20% sunlight treatment was appreciably retarded. However, this difference was not reflected in the photosynthetic rates at the ambient and 200 microbars CO(2). This implied that in vivo Rubisco activity may be regulated in the senescent leaves from the 20% sunlight treatment. The chlorophyll content decreased most slowly. In the 20% sunlight treatment, it remained apparently constant with a decline in chlorophyll a/b ratio. These photosynthetic characteristics of the senescent rice leaves under low irradiance were discussed in relation to acclimation of shade plants.",1
"Hidema, J, Makino, A, Mae, T, Ojima, K",2
Role of the root apoplasm for iron acquisition by wheat plants.,0
"The role of the root apoplasm for iron acquisition was studied in wheat (Triticum aestivum L. cv Ares) grown in nutrient solution under controlled environmental conditions. To obtain different levels of Fe in the root apoplasm, plants were supplied in the dark for 5 hours (preloading period) with various (59)Fe-labeled Fe compounds [Fe(III) hydroxide; microbial siderophores: Fe rhodotorulic acid (FeRDA) and ferrioxamin (FeDesferal(3)), and synthetic Fe chelate (FeEDDHA)], each at a concentration of 5 micromolar. Large pools of apoplasmic Fe were formed after supplying Fe(III) hydroxide or FeRDA, but no such pools were observed after supplying FeDesferal or FeEDDHA. Depending on plant Fe nutritional status (preculture +/- 0.1 millimolar FeEDTA), apoplasmic Fe was used to different extent for translocation to the shoot. Under Fe deficiency, a much greater fraction of the apoplasmic Fe was utilized than in Fe-sufficient plants, as a result of the different rates of phytosiderophore release. Because of the diurnal rhythm in release of phytosiderophores in Fe-deficient plants, the utilization of the apoplasmic Fe for translocation into the shoot started 2 hours after onset of the light period and was dependent on the concentration of Fe in the apoplasm, which followed the order: Fe(III) hydroxide > FeRDA > FeDesferal = FeEDDHA. From these results, it can be concluded that in soil-grown plants the apoplasmic Fe pool loaded by various indigenous Fe compounds such as siderophores in the soil solution can be an important Fe source in graminaceous species, particularly during periods of limited Fe supply from the soil.",1
"Zhang, F S, Römheld, V, Marschner, H",2
Protein compositions of mesophyll and paraveinal mesophyll of soybean leaves at various developmental stages.,0
"Mesophyll and paraveinal mesophyll protoplasts (PVMP) were isolated from leaves of soybean (Glycine max) at various stages of physiological development, and protein compositions of the two protoplast types were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. Polypeptides of 27, 29 (previously shown to be storage proteins), and 94 kilodaltons were found to be PVMP-specific proteins and were present in both nodulated and nonnodulated plants. The 27 and 94 kilodalton polypeptides were major PVMP constituents. All three polypeptides accumulate as early as one-quarter leaf expansion. Immunoblotting and immunocytochemical studies using antibodies against the 27/29 kilodalton proteins confirmed that they are specific to the paraveinal mesophyll (PVM) and that they are localized in the PVM vacuole. The 27 kilodalton polypeptide increased significantly by two weeks depodding, and this accumulation was restricted to the PVM vacuole. Radiolabeling experiments showed that the difference in relative amounts of the 27 and 29 kilodalton polypeptides was due to a greater rate of synthesis of the 27 kilodalton polypeptide. The 94 kilodalton polypeptide accumulated to a maximum at anthesis, but was absent at 2 weeks postanthesis in both depodded and podded nodulated plants, probably because they were nitrogen limited. In nonnodulated plants, it was present through 2 weeks postanthesis. The results confirm that the 27 and 29 kilodalton proteins of soybean leaf are stored in the PVM vacuole and show that they are accumulated early during leaf development while they are still strong sinks for nitrogen. The 94 kilodalton protein, previously found to accumulate in leaves after depodding, is also a PVM protein and is likely a third vegetative storage protein, although its accumulation appears to be more dependent on excess nitrogen availability. The results further support the hypothesis that the PVM is a specialized leaf tissue that functions in synthesis and compartmentation of storage proteins.",1
"Klauer, S F, Franceschi, V R, Ku, M S",2
Partial Purification and Characterization of Three NAD(P)H Dehydrogenases from Beta vulgaris Mitochondria.,0
"Mitochondria isolated from the taproot of beet (Beta vulgaris) were used in an effort to identify and partially purify the proteins constituting the exogenous NADH dehydrogenase. Three NAD(P)H dehydrogenases are released from these mitochondria by sonication, and these enzymes were partially purified using fast protein liquid chromatography. One of the enzymes, designated peak I, is capable of oxidizing NADPH and the beta form of NADH. The other two activities, peaks II and III, oxidize only beta-NADH. All three peaks are insensitive to divalent cation chelators and a complex I inhibitor, rotenone. The major component to peak I is a polypeptide with an apparent molecular mass of approximately 42 kilodaltons. Peak I activity was insensitive to platanetin, a specific inhibitor of the exogenous dehydrogenase, and insensitive to added Ca(2+) or Mg(2+). Peak I displayed a broad pH activity profile with an optimum between 7.5 and 8.0 for both NADPH and NADH. Purified peak II gave a single polypeptide of about 32 kilodaltons, had a pH optimum between 7.0 and 7.5, and was slightly stimulated by Ca(2+) and Mg(2+). As with peak I, platanetin had no effect on peak II activity. Peak III was not purified completely, but contained two major polypeptides with apparent molecular masses of 55 and 40 kilodaltons. This enzyme was not affected by Ca(2+) and Mg(2+), but was inhibited by platanetin. The peak III enzyme had a rather sharp pH optimum of approximately 6.5 to 6.6. The above data indicate that peak III activity is likely the exogenous NADH dehydrogenase.",1
"Luethy, M H, Hayes, M K, Elthon, T E",2
Bifunctional protein in carrot contains both aspartokinase and homoserine dehydrogenase activities.,0
"We have purified homoserine dehydrogenase to homogeneity and subjected polypeptide fragments derived from digests of the protein to amino acid sequencing. The amino acid sequence of homoserine dehydrogenase from carrot (Daucus carota) indicates that in carrot both aspartokinase and homoserine dehydrogenase activities reside on the same protein. Additional evidence that aspartokinase and homoserine dehydrogenase reside on a bifunctional protein is provided by coelution of activities during purification steps and by enzyme-specific gel staining techniques. Highly purified fractions containing aspartokinase activity were stained for aspartokinase activity, homoserine dehydrogenase activity, and protein. These gels confirmed that aspartokinase activity and homoserine dehydrogenase activity were present on the same protein. This arrangement of aspartokinase and homoserine dehydrogenase activities residing on the same protein is also found in Escherichia coli, which has two bifunctional enzymes, aspartokinase I-homoserine dehydrogenase I and aspartokinase II-homoserine dehydrogenase II. The amino acid sequence of the major form of homoserine dehydrogenase from carrot cell suspension cultures most closely resembles that of the E. coli ThrA gene product aspartokinase I-homoserine dehydrogenase I.",1
"Wilson, B J, Gray, A C, Matthews, B F",2
Association of phosphoenolpyruvate phosphatase activity with the cytosolic pyruvate kinase of germinating mung beans.,0
"The procedure of Malhotra and Kayastha ([1990] Plant Physiology 93: 194-200) for the purification to homogeneity of a phosphoenolpyruvate-specific alkaline phosphatase (PEP phosphatase) from germinating mung beans (Vigna radiata) was followed. Although a higher specific activity of 1.4 micromoles pyruvate produced per minute per milligram protein was obtained, the final preparation was less than 10% pure as judged by polyacrylamide gel electrophoresis. Attempts to further purify the enzyme resulted in loss of activity. The partially purified enzyme contained significant pyruvate kinase activity (0.13 micromole pyruvate produced per minute per milligram protein) when assayed at pH 7.2, but not at pH 8.5. The PEP phosphatase activity of the final preparation exhibited hysteresis; a lag time of 5 to 6 minutes was required before a steady-state reaction rate was attained. A western blot of the final preparation revealed an immunoreactive 57 kilodalton polypeptide when probed with monospecific rabbit polyclonal antibodies prepared against germinating castor bean cytosolic pyruvate kinase. No antigenic cross-reaction of the final preparation was observed with antibodies against castor bean leucoplast pyruvate kinase, or black mustard PEP-specific acid phosphatase. Nondenaturing polyacrylamide gel electrophoresis of the final preparation resulted in a single PEP phosphatase activity band; when this band was excised and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting, a 57 kilodalton silver-staining polypeptide was obtained that strongly cross-reacted with the anti-(cytosolic pyruvate kinase) immunoglobulin G. It is suggested that mung bean PEP-specific alkaline phosphatase activity is due to cytosolic pyruvate kinase, in which pyruvate and ortho-phosphate are formed in the absence of ADP.",1
"Podestá, F E, Plaxton, W C",2
Leucoplast Pyruvate Kinase from Developing Castor Oil Seeds : Characterization of the Enzyme's Degradation by a Cysteine Endopeptidase.,0
"Leucoplast pyruvate kinase (PK(p); EC 2.7.1.40) from endosperm of developing castor oil seeds (Ricinus communis L. cv Baker 296) appears to be highly susceptible to limited degradation by a cysteine endopeptidase during the purification of the enzyme or incubation of clarified homogenates at 4 degrees C. Purified castor seed PK(p) was previously reported to consist of immunologically related 57.5 and 44 kilodalton subunits (Plaxton WC, Dennis DT, Knowles VL [1990] Plant Physiol 94: 1528-1534). By contrast, immunoreactive polypeptides of about 63.5 and 54 kilodaltons were observed when a western blot of an extract prepared under denaturing conditions was probed with affinity purified rabbit anti-(castor seed PK(p)) immunoglobulin G. Proteolytic activity against PK(p) was estimated by the disappearance of the 63.5 and 54 kilodalton subunits and the concomitant appearance of lower molecular mass immunoreactive degradation products during the incubation of clarified homogenates at 4 degrees C. The presence of 2 millimolar dithiothreitol accelerated the degradation of PK(p). The conservation of the 63.5 and 54 kilodalton subunits was observed after extraction of the enzyme in the presence of 1 millimolar p-hydroxymecuribenzoate, or 1 millimolar Nalpha-p-tosyl-l-lysine chloromethyl ketone, or 10 millimolar iodoacetate. These results reveal that a cysteine endopeptidase was responsible for the in vitro proteolysis of PK(p). This endopeptidase is present throughout all stages of endosperm development. Its PK(p)-degrading activity, however, appears to be most pronounced in preparations from older endosperm. When lysates of purified leucoplasts were incubated at 4 degrees C for up to 21 hours, no degradation of PK(p) was observed; this indicated an extra-leucoplastic localization for the cysteine endopeptidase. Although the in vivo subunit structure of PK(p) remains uniform throughout all stages of endosperm development, the large decrease in PK activity that accompanies castor seed maturation coincides with a marked reduction in the concentration of PK(p).",1
"Plaxton, W C",2
Imidazolinone-induced loss of acetohydroxyacid synthase activity in maize is not due to the enzyme degradation.,0
"Acetohydroxyacid synthase (AHAS), the first enzyme leading to the biosynthesis of valine, leucine, and isoleucine, is inhibited by different chemical classes of herbicides. There is a loss in the extractable AHAS activity in imidazolinone-treated plants. Immunological studies using a monoclonal antibody against AHAS revealed no degradation of AHAS protein in imidazolinone-treated maize (Zea mays) plants. Therefore, the loss in AHAS activity is not due to the loss of AHAS protein.",1
"Shaner, D L, Singh, B K",2
Systemic Induction of Salicylic Acid Accumulation in Cucumber after Inoculation with Pseudomonas syringae pv syringae.,0
"Inoculation of one true leaf of cucumber (Cucumis sativus L.) plants with Pseudomonas syringae pathovar syringae results in the systemic appearance of salicylic acid in the phloem exudates from petioles above, below, and at the site of inoculation. Analysis of phloem exudates from the petioles of leaves 1 and 2 demonstrated that the earliest increases in salicylic acid occurred 8 hours after inoculation of leaf 1 in leaf 1 and 12 hours after inoculation of leaf 1 in leaf 2. Detaching leaf 1 at intervals after inoculation demonstrated that leaf 1 must remain attached for only 4 hours after inoculation to result in the systemic accumulation of salicylic acid. Because the levels of salicylic acid in phloem exudates from leaf 1 did not increase to detectable levels until at least 8 hours after inoculation with P. s. pathovar syringae, the induction of increased levels of salicylic acid throughout the plant are presumably the result of another chemical signal generated from leaf 1 within 4 hours after inoculation. Injection of salicylic acid into tissues at concentrations found in the exudates induced resistance to disease and increased peroxidase activity. Our results support a role for salicylic acid as an endogenous inducer of resistance, but our data also suggest that salicylic acid is not the primary systemic signal of induced resistance in cucumber.",1
"Rasmussen, J B, Hammerschmidt, R, Zook, M N",2
"Xylulose 1,5-Bisphosphate Synthesized by Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase during Catalysis Binds to Decarbamylated Enzyme.",0
"Xylulose 1,5-bisphosphate (XuBP) is synthesized from ribulose 1,5-bisphosphate (RuBP) at carbamylated catalytic sites on ribulose 1,5-bisphosphate carboxylase (Rubisco) with significant amounts of XuBP being formed at pH less than 8.0. XuBP has been separated by high performance liquid chromatography and identified by pulsed amperometry from compounds bound to Rubisco during catalysis with the purified enzyme and from celery (Apium graveolens var Utah) leaf extracts. XuBP does not bind tightly to carbamylated sites, but does bind tightly to decarbamylated sites. Upon incubation of fully activated Rubisco with 5 micromolar XuBP, loss of activator CO(2) occurred before XuBP bound to the enzyme catalytic sites, even in the presence of excess CO(2) and Mg(2+). Binding of XuBP to decarbamylated Rubisco sites was highly pH dependent. At pH 7.0 and 7.5 with 10 millimolar MgCl(2) and 10 millimolar KHCO(3), the apparent dissociation constant for XuBP, K(d), was 0.03 micromolar, whereas at pH 8.0 and 8.5, the apparent K(d) was 0.35 and 2.0 micromolar, respectively. This increase in K(d) with pH was a result of a decrease in the association rate constant and an increase in the dissociation rate constant of XuBP bound to decarbamylated sites on Rubisco. The K(d) of 2-carboxyarabinitol 1-phosphate binding to carbamylated sites was only slightly pH dependent.",1
"Zhu, G, Jensen, R G",2
"[C]GA(12)-Aldehyde, [C]GA(12), and [H]- and [C]GA(53) Metabolism by Elongating Pea Pericarp.",0
"Gibberellins (GAs) are either required for, or at least promote, the growth of the pea (Pisum sativum L.) fruit. Whether the pericarp of the pea fruit produces GAs in situ and/or whether GAs are transported into the pericarp from the developing seeds or maternal plant is currently unknown. The objective of this research was to investigate whether the pericarp tissue contains enzymes capable of metabolizing GAs from [(14)C]GA(12)-7-aldehyde ([(14)C]GA(12)ald) to biologically active GAs. The metabolism of GAs early in the biosynthetic pathway, [(14)C]GA(12) and [(14)C]GA(12)ald, was investigated in pericarp tissue isolated from 4-day-old pea fruits. [(14)C]GA(12)ald was metabolized primarily to [(14)C]GA(12)ald-conjugate, [(14)C]GA(12), [(14)C]GA(53), and polar conjugate-like products by isolated pericarp. In contrast, [(14)C]GA(12) was converted primarily to [(14)C]GA(53) and polar conjugate-like products. Upon further investigations with intact 4-day-old fruits on the plant, [(14)C]GA(12) was found to be converted to a product which copurified with endogenous GA(20). Lastly, [(2)H]GA(20) and [(2)H]GA(1) were recovered 48 hours after application of [(2)H]- and [(14)C]GA(53) to pericarp tissue of intact 3-day-old pea fruits. These results demonstrate that pericarp tissue metabolizes GAs and suggests a function for pericarp GA metabolism during fruit growth.",1
"Maki, S L, Brenner, M L",2
Organ-Specific and Environmentally Regulated Expression of Two Abscisic Acid-Induced Genes of Tomato : Nucleotide Sequence and Analysis of the Corresponding cDNAs.,0
"The cDNAs, pLE4 and pLE25, represent mRNAs that accumulate in response to water deficit and elevated levels of endogenous abscisic acid in detached leaves of drought-stressed tomato (Lycopersicon esculentum Mill., cv Ailsa Craig) (A Cohen, EA Bray [1990] Planta 182: 27-33). DNA sequence analysis of pLE4 and pLE25 showed that the deduced polypeptides were 13.9 and 9.3 kilodaltons, respectively. Each polypeptide was hydrophilic, cysteine- and tryptophan-free, and found to be similar to previously identified proteins that accumulate during the late stages of embryogenesis. pLE4 and pLE25 mRNA accumulated in a similar organ-specific pattern in response to specific abiotic stresses. Yet, expression patterns of the corresponding genes in response to developmental cues were not similar. pLE25 mRNA accumulated to much higher levels in developing seeds than in drought-stressed vegetative organs. pLE4 mRNA accumulated predominantly in drought-stressed leaves. The similarities and differences in the accumulation characteristics of these two mRNAs indicates that more than one mechanism exists for the regulation of their corresponding genes.",1
"Cohen, A, Plant, A L, Moses, M S, Bray, E A",2
Effects of O(2) and CO(2) Concentrations on Quantum Yields of Photosystems I and II in Tobacco Leaf Tissue.,0
"The interactive effects of irradiance and O(2) and CO(2) levels on the quantum yields of photosystems I and II have been studied under steady-state conditions at 25 degrees C in leaf tissue of tobacco (Nicotiana tabacum). Assessment of radiant energy utilization in photosystem II was based on changes in chlorophyll fluorescence yield excited by a weak measuring beam of modulated red light. Independent estimates of photosystem I quantum yield were based on the light-dark in vivo absorbance change at 830 nanometers, the absorption band of P700(+). Normal (i.e. 20.5%, v/v) levels of O(2) generally enhanced photosystem II quantum yield relative to that measured under 1.6% O(2) as the irradiance approached saturation. Photorespiration is suspected to mediate such positive effects of O(2) through increases in the availability of CO(2) and recycling of orthophosphate. Conversely, at low intercellular CO(2) concentrations, 41.2% O(2) was associated with lower photosystem II quantum yield compared with that observed at 20.5% O(2). Inhibitory effects of 41.2% O(2) may occur in response to negative feedback on photosystem II arising from a build-up in the thylakoid proton gradient during electron transport to O(2). Covariation between quantum yields of photosystems I and II was not affected by concentrations of either O(2) or CO(2). The dependence of quantum yield of electron transport to CO(2) measured by gas exchange upon photosystem II quantum yield as determined by fluorescence was unaffected by CO(2) concentration.",1
"Peterson, R B",2
Three RNases in Senescent and Nonsenescent Wheat Leaves : Characterization by Activity Staining in Sodium Dodecyl Sulfate-Polyacrylamide Gels.,0
"We have described three RNases in wheat leaves (Triticum aestivum L. cv Chinese Spring) and developed assays for measuring each RNase individually in crude leaf extracts. We initially used activity staining in sodium dodecyl sulfate-polyacrylamide gels to characterize RNases in extracts of primary and flag leaves. We thus identified acid RNase (EC 3.1.27.1, here designated RNase WL(A)), and two apparently novel enzymes, designated RNases WL(B) and WL(C). RNase WL(B) activity displays a distinctive isozyme pattern, a molecular mass of 26 kilodaltons (major species), a broad pH range with an optimum near neutrality, insensitivity to EDTA, and stimulation by moderate concentrations of KCl and by MgCl(2). RNase WL(C) activity exhibits a molecular mass of 27 kilodaltons, a neutral pH optimum, insensitivity to EDTA, and inhibition by KCl, MgCl(2), and tri-(hydroxymethyl)aminomethane. Based on distinctive catalytic properties established in gels, we designed conventional solution assays for selective quantitation of each RNase activity. We used the assays to monitor the individual RNases after gel filtration chromatography and native gel electrophoresis of extracts. In accompanying work, we used the assays to monitor RNases WL(A), WL(B), and WL(C), which are present in senescent and nonsenescent leaves, during the course of leaf senescence.",1
"Blank, A, McKeon, T A",2
Expression of Three RNase Activities during Natural and Dark-Induced Senescence of Wheat Leaves.,0
"We have monitored the activities of RNases WL(A), WL(B), and WL(C) (A Blank, TA McKeon [1991] Plant Physiol 97: 1402-1408) during leaf senescence in wheat (Triticum aestivum L. cv Chinese Spring). When seedlings were induced to senesce in darkness, protein loss from primary leaves began immediately. RNase WL(B) activity was unchanged for 2 days and then rose linearly, reaching a sixfold elevation in 7 days. RNase WL(C) activity declined for 2 days and then rose linearly, reaching a twofold elevation in 7 days. RNase WL(A) activity declined in the first 2 days and was unchanged thereafter. Although differentially expressed, these RNase activities may respond to a common regulatory mechanism(s) which, at 2 days of darkness, signals progression into a more advanced stage of senescence. The RNase activities were also differentially expressed during light-induced recovery, returning to normal levels in dissimilar patterns. In flag leaves of greenhouse-grown wheat, the three RNase activities increased during the early postanthesis period when protein content was stable and underwent further, accelerated accumulation during senescence. RNase WL(B) activity showed the largest overall senescence-associated elevation (sixfold), followed by RNase WL(C) (fourfold) and RNase WL(A) (threefold).",1
"Blank, A, McKeon, T A",2
Sugar-Dependent Expression of the CHS-A Gene for Chalcone Synthase from Petunia in Transgenic Arabidopsis.,0
"Transgenic Arabidopsis thaliana plants were constructed by introduction of a fusion of the gene for beta-glucuronidase (GUS) to the CHS-A gene, which is one of the two genes for chalcone synthase that are actively expressed in the floral organs of petunia. The expression of the fusion gene CHS-A::GUS was low in transgenic Arabidopsis plantlets, but it was enhanced when plantlets or detached leaves were transferred to a medium that contained 0.3 molar sucrose, glucose, or fructose. No enhancement was observed when plantlets were transferred to a medium that contained 0.3 molar mannitol. Measurements of cellular levels of sugars revealed a tight linkage between the level of expression of the CHS-A::GUS gene and the level of accumulation of exogenously supplied sugars, in particular sucrose. The parallelism between the organ-specific accumulation of sugar and the organ-specific expression of the CHS-A::GUS gene was also observed in petunia and A. thaliana plants grown under normal conditions in soil. The consensus sequences for sugar responses, such as boxes II and III in members of the family of sporamin genes from the sweet potato, were found in the promoter region of the CHS-A gene that was used for fusion to the GUS gene. It is suggested that the expression of the CHS-A gene is regulated by sugars, as is the expression of other sugar-responsive genes, such as the genes for sporamin. A putative common mechanism for the control of expression of ""sugar-related"" genes, including the CHS-A gene, is discussed.",1
"Tsukaya, H, Ohshima, T, Naito, S, Chino, M, Komeda, Y",2
Turnover of catalase heme and apoprotein moieties in cotyledons of sunflower seedlings.,0
"The turnover of catalase apoprotein and catalase heme was studied in cotyledons of sunflower (Helianthus annuus L.) seedlings by density labeling of apoprotein and radioactive labeling of heme moieties. The heavy isotope (50% (2)H(2)O) and the radioactive isotope ([(14)C]5-aminolevulinic acid) were applied either during growth in the dark (day 0-2.5) or in the light (day 2.5 and 5). Following isopycnic centrifugation of catalase purified from cotyledons of 5-day-old seedlings, superimposition curve fitting was used to determine the amounts of radioactive heme moieties in native and density-labeled catalase. Data from these determinations indicated that turnover of catalase heme and apoprotein essentially was coordinate. Only small amounts of heme groups were recycled into newly synthesized apoprotein during growth in the light, and no evidence was found for an exchange of heme groups in apoprotein moieties. It followed from these observations that degradation of catalase apoprotein was slightly faster than that of catalase heme. A degradation constant for catalase apoprotein of 0.263 per day was determined from the data on heme recycling and the degradation constant of catalase heme determined previously to be 0.205 per day (R Eising, B Gerhardt [1987] Plant Physiol 84: 225-232).",1
"Eising, R, Süselbeck, B",2
Heat Shock Proteins in Two Lines of Zea mays L. That Differ in Drought and Heat Resistance.,0
"Synthesis of heat shock proteins (HSPs) in the leaves of a drought- and heat-resistant (line ZPBL 1304), and a drought- and heat-sensitive (line ZPL 389) line of maize (Zea mays L.) was studied under two environmental stress treatments: (a) soil drying and high temperature and (b) high temperature. In the first treatment 13-day-old plants were exposed to 7-day soil drying followed by high temperature stress (45 degrees C), and in the second treatment 20-day-old plants were exposed to high temperature stress (45 degrees C). Second leaves were labeled with [(35)S]methionine. During the labeling period line ZPBL 1304 showed no signs of leaf dehydration under soil drying and high temperature stress conditions. In contrast, line ZPL 389 was dehydrated 23%, as determined by relative water content. Incorporation of [(35)S]methionine into protein was greater in the resistant than in the sensitive line in both treatments. The pattern of synthesis of HSPs in the two lines was similar in treatments 1 and 2. Both lines synthesized a high molecular mass set and a low molecular mass set of HSPs. Proteins from both sets from both lines of maize appeared similar to each other, with respect to the molecular mass. Heated plants of the drought- and heat-resistant line ZPBL 1304 synthesized a band of HSP(s) of approximately 45 kilodaltons which was not found in heated plants of the drought and heat sensitive line ZPL 389. This is the first report on qualitative intraspecific difference in the synthesis of HSPs in maize.",1
"Ristic, Z, Gifford, D J, Cass, D D",2
Role of Ethylene in the Germination of the Hemiparasite Striga hermonthica.,0
"Seed germination of the hemiparasitic angiosperm Striga hermonthica (Del.) Benth is elicited by compounds present in the root exudates of the host plant. Although a variety of compounds can substitute for the host-derived signal, the mechanism through which these act is unknown. In the present study, an inhibitor of ethylene biosynthesis, aminoethoxyvinyl glycine, was found to inhibit germination. Addition of an intermediate in ethylene biosynthesis, 1-aminocyclopropane-1-carboxylic acid, was found to override this inhibition and to act as a substitute for the host-derived signal. 2,5-Norbornadiene, an inhibitor of ethylene action, was also found to inhibit germination. Ethylene is rapidly produced by Striga seeds after treatment with host root exudates. These results are consistent with a model for Striga seed germination in which host-derived signals and other compounds act by eliciting the synthesis of ethylene and in which ethylene itself initiates the biochemical changes leading to germination.",1
"Logan, D C, Stewart, G R",2
Utilization of Inorganic Carbon by Ulva lactuca.,0
"Thalli discs of the marine macroalga Ulva lactuca were given inorganic carbon in the form of HCO(3) (-), and the progression of photosynthetic O(2) evolution was followed and compared with predicted O(2) evolution as based on calculated external formation of CO(2) (extracellular carbonic anhydrase was not present in this species) and its carboxylation (according to the K(m)(CO(2)) of ribulose-1,5-bisphosphate carboxylase/oxygenase), at two different pHs, assuming a photosynthetic quotient of 1. The K(m)(inorganic carbon) was some 2.5 times lower at pH 5.6 than at the natural seawater pH of 8.2, whereas V(max) was similar under the two conditions, indicating that the unnaturally low pH per se had no adverse effect on U. lactuca's photosynthetic performance. These results, therefore, could be evaluated with regard to differential CO(2) and HCO(3) (-) utilization. The photosynthetic performance observed at the lower pH largely followed that predicted, with a slight discrepancy probably reflecting a minor diffusion barrier to CO(2) uptake. At pH 8.2, however, dehydration rates were too slow to supply CO(2) for the measured photosynthetic response. Given the absence of external carbonic anhydrase activity, this finding supports the view that HCO(3) (-) transport provides higher than external concentrations of CO(2) at the ribulose-1,5-bisphosphate carboxylase/oxygenase site. Uptake of HCO(3) (-) by U. lactuca was further indicated by the effects of potential inhibitors at pH 8.2. The alleged band 3 membrane anion exchange protein inhibitor 4,4'-diisothiocyanostilbene-2,2'disulphonate reduced photosynthetic rates only when HCO(3) (-) (but not CO(2)) could be the extracellular inorganic carbon form taken up. A similar, but less drastic, HCO(3) (-)-competitive inhibition of photosynthesis was obtained with Kl and KNO(3). It is suggested that, under ambient conditions, HCO(3) (-) is transported into cells at defined sites either via facilitated diffusion or active uptake, and that such transport is the basis for elevated internal [CO(2)] at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase carboxylation.",1
"Drechsler, Z, Beer, S",2
Rapid Accumulation of Anionic Peroxidases and Phenolic Polymers in Soybean Cotyledon Tissues following Treatment with Phytophthora megasperma f. sp. Glycinea Wall Glucan.,0
"Phytophthora megasperma Drechs. f. sp. glycinea Kuan & Erwin (PMG) cell wall glucan has been extensively characterized as an elicitor of the pterocarpan phytoalexins, the glyceollins in soybean (Glycine max L.). Just recently, this glucan was shown to be a potent elicitor of conjugates of the isoflavones, daidzein and genistein as well. Here we report that PMG wall glucan also induces a rapid and massive accumulation of phenolic polymers in soybean cotyledon cells proximal to the point of elicitor application. Deposition of phenolic polymers is over then times that in wounded controls within just 4 hours of elicitor treatment and reaches a maximum by 24 hours. In the same tissues, isoflavone conjugates begin to accumulate at 8 hours and glyceollin at 12 hours. By 24 hours, the total deposition of wall bound phenolics in elicitor-treated tissues is several times greater than the peak glyceollin and isoflavone responses combined. Histochemical stains and quantitation of phenolic residues released after saponification and nitrobenzene or copper oxide oxidation suggest that the covalently linked phenolics include both lignin- and suberin-like polymers as well as simple esterified coumaric and ferulic acid monomers. Accumulations of phenolic polymers are accompanied by equally rapid and massive increases in activity of a specific group of anionic peroxidases. Although increases in peroxidase activity are not strictly limited to cells immediately adjacent to the area of elicitor treatment, the deposition of phenolic polymers is significantly less extensive in distal cells.",1
"Graham, M Y, Graham, T L",2
Cell Wall Metabolism in Ripening Fruit : V. Analysis of Cell Wall Synthesis in Ripening Tomato Pericarp Tissue Using a d-[U-C]Glucose Tracer and Gas Chromatography-Mass Spectrometry.,0
"A gas chromatographic-mass spectrometric technique utilizing d-[U-(13)C]glucose as a density label tracer was used to follow the synthesis of cell wall polysaccharides in pericarp discs that were excised from mature green tomato fruit (Lycopersicon esculentum) and allowed to ripen in culture. The biosynthetic capacity of discs from four different maturity stages was examined. Label was differentially incorporated into wall polysaccharides as the discs matured, indicating a change in the nature of wall polymers being synthesized. These differential rates of incorporation are consistent with descriptions of ripening-related cell wall compositional changes previously reported by other authors. Specific changes in wall biosynthesis noted include increased incorporation of xylosyl and mannosyl residues into hemicellulosic cell wall fractions as the discs mature and decreased incorporation of galactosyl residues into chelator-soluble pectins.",1
"Greve, L C, Labavitch, J M",2
Isolation and characterization of a tomato Acid phosphatase complementary DNA associated with nematode resistance.,0
"The tomato (Lycopersicon esculentum) acid phosphatase-1 (Apase-1(1), EC 3.1.3.2) isozyme variant, genetically linked to the root-knot nematode resistance locus (Mi) on chromosome 6, has been purified by a rapid procedure from tomato cell suspension cultures. Peptide fragments of the purified enzyme were generated from trypsin and Lys-C endoprotease digests and separated by reverse-phase high-performance liquid chromatography. Amino acid sequences derived from the purified peptide fragments represented >50% of the total amino acid content of the protein and enabled the construction of degenerate oligonucleotide probes that were used to screen a tomato cell culture complementary DNA library. Clones corresponding to full-length coding sequences for Apase-1 have been isolated and sequenced. Southern blot analysis of DNA isolated from a number of tomato cultivars shows that the Apase-1(1) gene (aps1) is present at one copy per genome and that genotypes containing the aps1(1) allele have restriction fragment length polymorphisms that distinguish them from cultivars having the aps1(+) allele. Segregation analysis demonstrates that the restriction fragment length polymorphisms are associated with the aps1 locus. Tomato Apase-1(1) is also found to have significant homology at the amino acid sequence level to a class of vegetative storage proteins characterized in soybean.",1
"Erion, J L, Ballo, B, May, L, Bussell, J, Fox, T, Thomas, S R",2
Effect of Light and NO(3) on Wheat Leaf Phosphoenolpyruvate Carboxylase Activity: Evidence for Covalent Modulation of the C(3) Enzyme.,0
"Phosphoenolpyruvate carboxylase (PEPcase) activity was studied in excised leaves of wheat (Triticum aestivum L.) in the dark and in the light, in presence of either N-free (low-NO(3) (-) leaves) or 40 millimolar KNO(3) (high-NO(3) (-) leaves) nutrient solutions. PEPcase activity increased to 2.7-fold higher than that measured in dark-adapted tissue (control) during the first 60 minutes and continued to increase more slowly to 3.8-fold that of the control. This level was reached after 200 minutes exposure of the leaves to light and high NO(3) (-). In contrast, the lower rate of increase recorded for low-NO(3) (-) leaves ceased after 60 minutes of exposure to light at 2.3-fold the control level. The short-term NO(3) (-) effect increased linearly with the level of NO(3) (-) uptake. In immunoprecipitation experiments, the antibody concentration for PEPcase precipitation increased with the protein extracts from the different treatments in the order: control, illuminated low-NO(3) (-) leaves, illuminated high-NO(3) (-) leaves. This order also applied with regard to a decreasing sensitivity to malate and an increasing stimulation by okadaic acid (an inhibitor of P-protein phosphatases). Following these studies, (32)P labeling experiments were carried out in vivo. These showed that the light-induced change in the properties of the PEPcase was due to an alteration in the phosphorylation state of the protein and that this effect was enhanced in high-NO(3) (-) conditions. Based on the responses of PEPcase and sucrose phosphate synthase in wheat leaves to light and NO(3) (-), an interpretation of the role of NO(3) (-) as either an inhibitor of P-protein phosphatase(s) or activator of protein kinase(s) is inferred. In the presence of NO(3) (-), the phosphorylation state of both PEPcase and sucrose phosphate synthase is increased. This causes activation of the former enzyme and inhibition of the latter. We suggest that NO(3) (-) modulates the relative protein kinase/protein phosphatase ratio to favor increased phosphorylation of both enzymes in order to redirect carbon flow away from sucrose synthesis and toward amino acid synthesis.",1
"Le Van Quy, C, Foyer, M L",2
"Vacuolar Release of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid, the Conjugated Form of the Ethylene Precursor.",0
"The mechanisms underlying the vacuolar retention or release of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the conjugated form of the ethylene precursor, has been studied in grape (Vitis vinifera) cells grown in vitro using the technique of compartmental analysis of radioisotope elution. Following its accumulation in the vacuole, M[2,3-(14)C]ACC could be released from cells when the vacuolar pH was artificially lowered by external buffers from its initial value of 6.2 to below the critical pH of 5.5. Successive release and retention of vacuolar MACC could be achieved by switching the vacuolar pH from values lower and higher than 5.5. The rate constant of efflux was highly correlated with the vacuolar pH. In plant tissues having low vacuolar pH under natural conditions, e.g. apple fruits (pH 4.2) and mung bean hypocotyls (pH 5.3), an efflux of M[2,3-(14)C]ACC also occurred. Its rate constant closely corresponded to the theorical values derived from the correlation established for grape cells. Evidence is presented that the efflux proceeded by passive lipophilic membrane diffusion only when MACC was in the protonated form. In contrast to other organic anions like malic acid, the mono and diionic species could not permeate the tonoplast, thus indicating the strict dependence of MACC retention upon the ionic status of the molecule and the absence of carrier-mediated efflux.",1
"Pedreño, M A, Bouzayen, M, Pech, J C, Marigo, G, Latché, A",2
Identification and Properties of the Major Ribonucleases of Arabidopsis thaliana.,0
"The profile of major ribonuclease (RNase) activities of Arabidopsis thaliana has been identified and characterized using a substrate-based gel assay. Following sodium dodecyl sulfatepolyacrylamide gel electrophoresis, as many as 16 RNases, varying in size from 9 to 41 kilodaltons can be detected. Most of the RNase activities exhibit a pH optimum of about 6.5; however, the activity of a 22.6-kilodalton RNase is greatly enhanced at low pH. A number of the RNases in the 30- to 41-kilodalton range are sensitive to ethylenediaminetetraacetic acid, and their activities are enhanced by the presence of a low concentration of zinc during renaturation. At least one RNase appears to comigrate with a major DNase activity. The differential accumulation of several RNases in stems versus leaves indicates that some RNases are controlled in an organ-specific manner in A. thaliana.",1
"Yen, Y, Green, P J",2
Phenylalanine Ammonia-Lyase from Tomato Cell Cultures Inoculated with Verticillium albo-atrum.,0
"Tomato (Lycopersicon esculentum Mill.) cell suspension cultures accumulated wall-bound phenolic materials in response to inoculation with Verticillium albo-atrum Reinke et Berth. in a fashion analogous to that observed in whole plants. Both monomeric and polymeric materials were recovered. Deposition of phenolics into the cell walls of inoculated tomato cell cultures was inhibited by the phenylalanine ammonia-lyase (PAL) inhibitor, 2-amino-2-indanephosphate. Tomato PAL activity was induced over 12-fold by fungal inoculation, with a concomitant increase in the corresponding mRNA. The enzyme was purified >3400-fold, to apparent homogeneity, by anion-exchange chromatography, chromatofocusing, and gel filtration. The holoenzyme had a molecular mass of 280 to 320 kilodaltons, comprising 74-kilodalton subunits, and displayed an isoelectric point of 5.6 to 5.7. Induced PAL displayed apparent Michaelis-Menten kinetics (K(m) = 116 micromolar) and was not appreciably inhibited by its product cinnamic acid. Chromatographic analysis did not reveal multiple forms of the enzyme in either inoculated or uninoculated cultures.",1
"Bernards, M A, Ellis, B E",2
Influence of Protoplasmic Water Loss on the Control of Protein Synthesis in the Desiccation-Tolerant Moss Tortula ruralis: Ramifications for a Repair-Based Mechanism of Desiccation Tolerance.,0
"Desiccation tolerance of the moss Tortula ruralis is characterized by a desiccation-induced change in gene expression that becomes evident upon rehydration. As reported earlier, this change in gene expression is apparently brought about by a change in the control of translation and does not include a major shift in mRNA abundance. A full qualitative and quantitative analysis of the alteration in gene expression, which is characterized by the loss of (or greater than fivefold decrease in) the synthesis of 25 hydration (h) proteins and initiation (or greater than fivefold increase) of the synthesis of 74 rehydration (r) proteins, is given in this report. Exposure to a desiccating atmosphere, for times that result in varying levels of water loss, enabled the determination that the control of synthesis of r proteins is different from the control of synthesis of h proteins. The r and h protein synthesis responses are internally coordinate, however. Similarly, the return to normal levels of h protein synthesis differs from that of the r proteins. The return to normal synthetic levels for all h proteins is synchronous, but the rate of loss of r protein synthesis varies with each individual r protein. Run-off translation of polysomes isolated from gametophytes during the drying phase demonstrates that there are no novel mRNAs recruited and no particular mRNA is favored for translation during desiccation. These findings add credence to the argument that translational control is the major component of the desiccation-induced alteration in gene expression in this plant, as discussed. Aspects of the response of protein synthesis to desiccation are consistent with the hypothesis that T. ruralis exhibits a repair-based mechanism of desiccation tolerance.",1
"Oliver, M J",2
Methyl jasmonate treatment eliminates cell-specific expression of vegetative storage protein genes in soybean leaves.,0
"Soybean (Glycine max) plants accumulate a vacuolar glycoprotein in the parenchymal cells of leaves, petioles, stems, seed pods, and germinating cotyledons that acts in temporary nitrogen storage during vegetative growth. In situ immunolocalization of this vegetative storage protein (VSP) revealed that it accumulates in those parenchymal cells in close proximity to existing and developing vasculature, as well as in epidermal and cortical cells. The protein was more prevalent in younger, nitrogen-importing tissues before pod and seed development. Removal of actively growing seed pods greatly enhanced VSP accumulation, primarily in bundle sheath and paraveinal mesophyll cells. In situ hybridization of a VSP RNA probe to mRNA in leaf sections demonstrated that cell-specific mRNA accumulation corresponded with the pattern of protein localization. Treatment of leaf explants with 50 micromolar methyl jasmonate resulted in accumulation of VSP mRNA and protein in all cell types.",1
"Huang, J F, Bantroch, D J, Greenwood, J S, Staswick, P E",2
Electrogenic transport properties of growing Arabidopsis root hairs : the plasma membrane proton pump and potassium channels.,0
"Ion transport, measured using double-barreled micropipettes to obtain current-voltage relations, was examined in Arabidopsis thaliana root hairs that continued tip growth and cytoplasmic streaming after impalement with the micropipette. To do this required in situ measurements with no handling of the seedlings to avoid wounding responses, and conditions allowing good resolution microscopy in tandem with the electrophysiological measurements. Two ion transport processes were demonstrated. One was a tetraethylammonium-sensitive potassium ion current, inward at hyperpolarized potentials and outward at depolarized potentials. The addition of tetraethylammonium (a potassium channel blocker) caused the potential to hyperpolarize, indicating the presence of a net inward potassium current through the ion channels at the resting potential. The potassium influx was sufficient to ""drive"" cellular expansion based upon growth rates. Indeed, tetraethylammonium caused transient inhibition of tip growth. The other electrogenic process was the plasma membrane proton pump, measured by indirect inhibition with cyanide or direct inhibition by vanadate. The proton pump was the dominant contribution to the resting potential, with a very high current density of about 250 microamperes per square centimeter (seen only in young growing root hairs). The membrane potential generated by the proton pump presumably drives the potassium influx required for cellular expansion. The pump appears to be a constant current source over the voltage range -200 to 0 millivolts. With this system, it is now possible to study the physiology of a higher plant cell in dynamic living state using a broad range of cell biological and electrophysiological techniques.",1
"Lew, R R",2
"Calcium-pumping ATPases in vesicles from carrot cells : stimulation by calmodulin or phosphatidylserine, and formation of a 120 kilodalton phosphoenzyme.",0
"Ca(2+)-ATPases keep cytoplasmic [Ca(2+)] low by pumping Ca(2+) into intracellular compartments or out of the cell. The transport properties of Ca(2+)-pumping ATPases from carrot (Daucus carota cv Danvers) tissue culture cells were studied. ATP-dependent Ca(2+) transport in vesicles that comigrated with an endoplasmic reticulum marker, was stimulated three- to fourfold by calmodulin. Cyclopiazonic acid (a specific inhibitor of the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase) partially inhibited oxalate-stimulated Ca(2+) transport activity; however, it had no effect on calmodulin-stimulated Ca(2+) uptake driven by ATP or GTP. The results would suggest the presence of two types of Ca(2+)-ATPases, an endoplasmic reticulum- and a plasma membrane-type. Interestingly, incubation of membranes with [gamma(32)P]ATP resulted in the formation of a single acyl [(32)P]phosphoprotein of 120 kilodaltons. Formation of this phosphoprotein was dependent on Ca(2+), but independent of Mg(2+). Its enhancement by La(3+) is characteristic of a phosphorylated enzyme intermediate of a plasma membrane-type Ca-ATPase. Calmodulin stimulated Ca(2+) transport was decreased by W-7 (a calmodulin antagonist), ML-7 (myosin light chain kinase inhibitor) or thyroxine. Acidic phospholipids, like phosphatidylserine, stimulated Ca(2+) transport, similar to their effect on the erythrocyte plasma membrane Ca(2+)-ATPase. These results would indicate that the calmodulin-stimulated Ca(2+) transport originated in large part from a plasma membrane-type Ca(2+) pump of 120 kilodaltons. The possibility of calmodulin-stimulated Ca(2+)-ATPases on endomembranes, such as the endoplasmic reticulum and secretory vesicles, as well as the plasma membrane is suggested.",1
"Hsieh, W L, Pierce, W S, Sze, H",2
Alternative respiration and heat evolution in plants.,0
"The alternative respiratory pathway dissipates most of the chemical energy of respiratory substrates as heat. We have shown that this heat can be quantified by microcalorimetry and is a measure of alternative pathway activity in vivo. The alternative pathway is known to increase in aged potato (Solanum tuberosum) slices and in chill-stressed leaves. Aging of potato slices for 24 hours was accompanied by an almost fourfold increase in the rate of heat evolution. This heat increase was resistant to KCN but could be blocked by an alternative pathway inhibitor, salicylhydroxamic acid (SHAM). In cucumber (Cucumis sativus) leaves subjected to chilling stress (between 4 and 16 degrees C), the rate of heat evolution was inversely related to temperature. As in aged potato slices, the increased rate of heat evolution in cucumber leaves was blocked by SHAM, but not by KCN. Nitrogen or the combination of SHAM and KCN blocked most of the heat evolution in both aged potato slices and chill-stressed cucumber leaves. Calorimetric measurements of the alternative pathway corresponded to respiration measurements performed using an oxygen electrode.",1
"Ordentlich, A, Linzer, R A, Raskin, I",2
Lidocaine and ATPase inhibitor interaction with the chloroplast envelope.,0
"Photosynthetic capacity of isolated intact chloroplasts is known to be sensitive to K(+) fluxes across the chloroplast envelope. However, little is known about the system of chloroplast envelope proteins that regulate this K(+) movement. The research described in this report focused on characterizing some of the components of this transport system by examining inhibitor effects on chloroplast metabolism. Digitoxin, an inhibitor of membrane-bound Na(+)/K(+) ATPases, was found to reduce stromal K(+) at a range of external K(+) and inhibit photosynthesis. Scatchard plot analysis revealed a specific protein receptor site with a K(m) for digitoxin binding of 13 nanomolar. Studies suggested that the receptor site was on the interior of the envelope. The effect of a class of amine anesthetics that are known to be K(+) channel blockers on chloroplast metabolism was also studied. Under conditions that facilitate low stromal pH and concomitant photosynthetic inhibition, the anesthetic, lidocaine, was found to stimulate photosynthesis. This stimulation was associated with the maintenance of higher stromal K(+). Comparison of the effects on photosynthesis of lidocaine analogs which varied in lipophilicity suggested a lipophilic pathway for anesthetic action. The results of experiments with lidocaine and digitoxin were consistent with the hypothesis that a K(+) channel and a K(+)-pumping envelope ATPase contribute to overall K(+) flux across the chloroplast envelope. Under appropriate assay conditions, photosynthetic capacity of isolated chloroplasts was shown to be much affected by the activity of these putative envelope proteins.",1
"Wu, W, Berkowitz, G A",2
Stromal low temperature compartment derived from the inner membrane of the chloroplast envelope.,0
"Leaf discs of four dicotyledonous species, when incubated at temperatures of 4 to 18 degrees C (optimum at 12 degrees C) for 30 or 60 minutes, responded by accumulations of membranes in the chloroplast stroma in the space between the inner membrane of the envelope and the thylakoids. The accumulated membranes, here referred to as the low temperature compartment, were frequently continuous with the envelope membrane and exhibited kinetics of formation consistent with a derivation from the envelope. Results were similar for expanding leaves of garden pea (Pisum sativum), soybean (Glycine max), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum). We suggest that the stromal low temperature compartment may be analogous to the compartment induced to form between the transitional endoplasmic reticulum and the Golgi apparatus at low temperatures. The findings provide evidence for the possibility of a vesicular transfer of membrane constituents between the inner membrane of the chloroplast envelope and the thylakoids of mature chloroplasts in expanding leaves.",1
"Morré, D J, Selldén, G, Sundqvist, C, Sandelius, A S",2
ADP-Glucose Transport by the Chloroplast Adenylate Translocator Is Linked to Starch Biosynthesis.,0
"In organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (Spinacia oleracea). Immunoblot analysis using a specific antiserum against the mitochondrial adenylate (ADP/ATP) translocator of Neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (Acer pseudoplatanus). The double silicone oil layer-filtering centrifugation technique was employed to study the kinetic properties of adenylate transport in the purified chloroplasts; ATP, ADP, AMP, and most importantly ADP-Glc were shown to be recognized by the adenylate translocator. Similar to the situation with sycamore amyloplasts, only ATP and ADP-Glc uptake was inhibited by carboxyatractyloside, an inhibitor of the mitochondrial adenylate translocator. Evidence is presented to show that the ADP-Glc transported into the chloroplast stroma is utilized for starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-d-glucan 4-alpha-d-glucosyltransferase). The high activity of sucrose synthase producing ADP-Glc observed in the extrachloroplastic fractions suggests that starch biosynthesis in chloroplasts may be coupled with the direct import of ADP-Glc from the cytosol.",1
"Pozueta-Romero, J, Ardila, F, Akazawa, T",2
Patch clamping protoplasts from vascular plants : method for the quick isolation of protoplasts having a high success rate of gigaseal formation.,0
"A method is described for the isolation of protoplasts (Pisum sativum, Phaseolus vulgaris, Avena sativa, Arabidopsis thaliana) in preparation for ion flux studies using patch clamp electrophysiology. Protoplasts that have been exposed to hydrolytic, cell wall degrading, enzymes for as little as 5 minutes form gigaseals (seal resistance higher than 10 giga Ohm) with the patch pipette with success rates greater than 40%. Sealing of these protoplasts is fast, averaging less than 2 minutes. This method yields high rates of gigaseal formation in a variety of tissues from both monocots and dicots and will enhance data collection in ion flux studies of plasma membranes of vascular plants.",1
"Elzenga, J T, Keller, C P, Van Volkenburgh, E",2
Simplified Procedure for the Isolation of Intact Chloroplasts from Chlamydomonas reinhardtii.,0
"A simple procedure that yields highly purified intact chloroplasts from Chlamydomonas reinhardtii is described. This procedure involves breakage of cell wall-deficient cells by passing them through a narrow bore syringe needle. The intact chloroplasts are then purified from the crude homogenate by differential centrifugation and Percoll gradient centrifugation. This procedure generates relatively high yields of chloroplasts capable of CO(2) fixation. These chloroplasts were characterized by electron microscopy, marker enzyme analysis, and ferricyanide exclusion. Transmission electron microscopy indicates that these chloroplasts retain their pyrenoids and eyespots. Scanning electron microscopy confirms that the characteristic cup shape of C. reinhardtii chloroplasts persists in vitro. This rapid, inexpensive procedure produces chloroplasts that should be useful for researchers studying the biochemistry and cell biology of C. reinhardtii chloroplasts.",1
"Mason, C B, Matthews, S, Bricker, T M, Moroney, J V",2
Transient down-regulation of phytochrome mRNA abundance in etiolated cucumber cotyledons in response to continuous white light.,0
"Phytochrome mRNA abundance decreased to 20% of the initial level in etiolated cucumber (Cucumis sativus L.) cotyledons exposed to continuous white light. Unexpectedly, by 12 hours of continuous white light, phytochrome mRNA had reaccumulated to 60% of the control level. High stringency RNA blot analyses suggest that it is the mRNA encoding type I phytochrome that reaccumulates.",1
"Tirimanne, T S, Colbert, J T",2
Efficiency of particle-bombardment-mediated transformation is influenced by cell cycle stage in synchronized cultured cells of tobacco.,0
Plasmid DNA pB1221 harboring beta-glucuronidase gene was delivered to synchronized cultured tobacco (Nicotiana tabacum L. cv Bright Yellow-2) cells of different cell cycle stages by a pneumatic particle gun. The cells bombarded at M and G(2) phases gave 4 to 6 times higher transformation efficiency than those bombarded at the S and G(1) phases.,1
"Iida, A, Yamashita, T, Yamada, Y, Morikawa, H",2
Enzymatic synthesis of isoprene from dimethylallyl diphosphate in aspen leaf extracts.,0
"Aspen (Populus tremuloides Michx.) leaf extracts contain a newly discovered enzyme activity that catalyzes the magnesium ion-dependent elimination of diphosphate from dimethylallyl diphosphate with rearrangement to form isoprene (2-methyl, 1-3-butadiene). This isoprene synthase activity has been partially purified. The nonenzymatic reaction of dimethylallyl diphosphate to isoprene, known to be acid catalyzed, may be insignificant at physiological pH. In contrast, the enzymatic reaction may be responsible for the majority of light-dependent isoprene production by isoprene-emitting plants.",1
"Silver, G M, Fall, R",2
Leaf catalase mRNA and catalase-protein levels in a high-catalase tobacco mutant with o(2)-resistant photosynthesis.,0
"Experiments were conducted with a tobacco (Nicotiana tabacum) mutant with 40 to 50% greater catalase activity than wild type that is associated with a novel form of O(2)-resistant photosynthesis. The apparent K(m) for H(2)O(2) was the same in mutant and wild-type leaf extracts. Tobacco RNAs were hybridized with Nicotiana sylvestris catalase cDNA, and a threefold greater steady-state level of catalase mRNA was found in mutant leaves. Steady-state levels of ribulose-1,5-bisphosphate carboxylase small subunit mRNA were similar in mutant and wild type. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of partially purified catalase showed that the protein concentration in the band corresponding to catalase was higher in the mutant than in the wild type. Separation of leaf catalase proteins by isoelectric focusing revealed the presence of five major bands and one minor band of activity. The distribution of the catalase activity among these forms was similar in mutant and wild type, although the total activity was higher in the mutant in all five major bands. The results indicate that the enhanced catalase activity in mutant leaves is caused by an increase in synthesis of catalase protein and that this trait is mediated at the nucleic acid level.",1
"Zelitch, I, Havir, E A, McGonigle, B, McHale, N A, Nelson, T",2
Sequence analysis of the msp4 gene of Anaplasma phagocytophilum strains.,0
"The causative agent of human granulocytic ehrlichiosis was recently reclassified as Anaplasma phagocytophilum, unifying previously described bacteria that cause disease in humans, horses, dogs, and ruminants. For the characterization of genetic heterogeneity in this species, the homologue of Anaplasma marginale major surface protein 4 gene (msp4) was identified, and the coding region was PCR amplified and sequenced from a variety of sources, including 50 samples from the United States, Germany, Poland, Norway, Italy, and Switzerland and 4 samples of A. phagocytophilum-like organisms obtained from white-tailed deer in the United States. Sequence variation between strains of A. phagocytophilum (90 to 100% identity at the nucleotide level and 92 to 100% similarity at the protein level) was higher than in A. marginale. Phylogenetic analyses of msp4 sequences did not provide phylogeographic information but did differentiate strains of A. phagocytophilum obtained from ruminants from those obtained from humans, dogs, and horses. The sequence analysis of the recently discovered A. phagocytophilum msp2 gene corroborated these results. The results reported here suggest that although A. phagocytophilum-like organisms from white-tailed deer may be closely related to A. phagocytophilum, they could be more diverse. These results suggest that A. phagocytophilum strains from ruminants could share some common characteristics, including reservoirs and pathogenicity, which may be different from strains that infect humans.",1
"de la Fuente, José, Massung, Robert F, Wong, Susan J, Chu, Frederick K, Lutz, Hans, Meli, Marina, von Loewenich, Friederike D, Grzeszczuk, Anna, Torina, Alessandra, Caracappa, Santo, Mangold, Atilio J, Naranjo, Victoria, Stuen, Snorre, Kocan, Katherine M",2
Erroneous reporting of coagulase-negative Staphylococci as Kocuria spp. by the Vitek 2 system.,0
"Misidentification of coagulase-negative staphylococci (CoNS) may delay appropriate treatment. We investigated 20 clinical isolates identified as Kocuria spp. by the Vitek 2 system. All were identified as CoNS by 16S rRNA gene sequencing (18 Staphylococcus epidermidis, 1 Staphylococcus haemolyticus). Four Kocuria isolates were shown to be identical to CoNS from the same patient by pulsed-field gel electrophoresis. Isolates identified by Vitek 2 as Kocuria most likely represent misidentified CoNS, and if clinically indicated, should be investigated further by genomic methods.",1
"Ben-Ami, R, Navon-Venezia, S, Schwartz, D, Schlezinger, Y, Mekuzas, Y, Carmeli, Y",2
"Rate and incidence estimates of recent human immunodeficiency virus type 1 infections among pregnant women in Sao Paulo, Brazil, from 1991 to 2002.",0
"The serological testing algorithm for recent human immunodeficiency virus (HIV) seroconversion (STARHS) was employed to estimate HIV incidence among pregnant women from Sao Paulo, Brazil. A cross-sectional study (1999 to 2002) showed an incidence of infection of 0.2 per 100 pregnant women per year (95% confidence interval, 0.041 to 0.608). Western blot profiles suggested an association between results of the STARHS analysis and gp41/gp31 bands.",1
"de Freitas Oliveira, Carmem A, Ueda, Mirthes, Yamashiro, Rosemeire, Rodrigues, Rosângela, Sheppard, Haynes W, de Macedo Brígido, Luís Fernando",2
Comparison of Easy-Flow Copan Liquid Stuart's and Starplex Swab transport systems for recovery of fastidious aerobic bacteria.,0
"Because samples are frequently submitted on swabs from distant sites, viability of the organism must be maintained. We compared two transport systems, a new Copan Liquid Stuart's swab with an Easy-Flow swab applicator and the Starplex Liquid Stuart's swab. The purpose of the study was to assess the release and/or recovery of organisms from the Copan system compared to that from Starplex. Triplicate swabs were seeded with 3 dilutions of Neisseria gonorrhoeae, Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae. Although the amount of the initial inoculum was the same for both transport systems, recovery by the roll-plate method at time zero was consistently increased with the Copan system (31 to 87% higher). This is the most important finding in this study. With N. gonorrhoeae, subsequent recoveries were similar for Copan and Starplex but poor for both systems. With N. meningitidis and Haemophilus, higher levels of recovery were clearly obtained with Copan (P < 0.05 to P < 0.001). With Streptococcus, subsequent recoveries for Copan and Starplex were mixed. In conclusion, Copan generally demonstrated better recovery of organisms compared to Starplex even (and especially) at time zero.",1
"Drake, Cheryl, Barenfanger, Joan, Lawhorn, Jerry, Verhulst, Steven",2
Novel antibody-lectin enzyme-linked immunosorbent assay that distinguishes prion proteins in sporadic and variant cases of Creutzfeldt-Jakob disease.,0
"We used different anti-prion protein (anti-PrP) monoclonal antibodies to capture either full-length or truncated PrP species and then used biotinylated lectin to compare the nature of the glycans on bound PrP species present in control, sporadic Creutzfeldt-Jakob disease (sCJD), or variant CJD (vCJD) brains. When full-length PrP species in these three groups were compared, no significant difference in the binding of concanavalin A or Aleuria aurantia lectin was detected. However, the binding of Ricinus communis agglutinin I (RCA) to sCJD and vCJD samples was significantly increased. In contrast, when only truncated PrP species were compared, only vCJD samples had more RCA binding activity. Therefore, while most of the RCA binding activity in sCJD is restricted to the full-length PrP species, the RCA binding activity in vCJD is associated with truncated and full-length PrP species. Furthermore, the RCA binding activity in sCJD and vCJD samples is mostly associated with proteinase K-resistant PrP species, a known signature of infectious prion. Therefore, PrP species in sCJD and vCJD have dissimilar lectin immunoreactivity, which reflects differences in their N-linked glycans. These differences may account for the distinct phenotypes of sCJD and vCJD.",1
"Pan, Tao, Li, Ruliang, Wong, Boon-Seng, Kang, Shin-Chung, Ironside, James, Sy, Man-Sun",2
Rapid identification of the coxsackievirus A24 variant by molecular serotyping in an outbreak of acute hemorrhagic conjunctivitis.,0
"We evaluated the clinical applicability of a molecular serotyping method for determination of the cause of epidemic acute hemorrhagic conjunctivitis. Seventy conjunctival swab specimens from individuals involved in a nationwide acute hemorrhagic conjunctivitis outbreak were tested. Viral culture and a molecular biology-based assay were compared by directly using clinical specimens. On the one hand, virus culture was done to isolate the enteroviruses, and serotyping was done by a coxsackievirus A24 variant-specific PCR. On the other hand, the original clinical specimens were directly screened for enterovirus by reverse transcription (RT)-PCR with panenterovirus-specific primers. Enterovirus screening-positive specimens were subjected to RT-PCR for detection of the VP1 region of enterovirus, and the amplicons were sequenced. Molecular serotyping was done by calculating the pairwise identity scores for the sequences with the maximum identities to the sequences of known prototype enteroviruses. Thirty-two specimens (45.7%) were culture positive, whereas 37 specimens (52.8%) were screening PCR positive (P < 0.001). The VP1 regions were amplified from 21 of the 37 specimens (56.8%), and the products amplified from 9 specimens were appropriately sequenced. These nine sequences were homologous with the sequence of the coxsackievirus A24 variant. Molecular serotyping by direct use of clinical specimens without cell culture could be applied for the rapid identification of the causative agent of epidemic acute hemorrhagic conjunctivitis.",1
"Park, Sang-Won, Lee, Chang-Seop, Jang, Hee-Chang, Kim, Eui-Chong, Oh, Myoung-don, Choe, Kang-Won",2
Use of microsatellite markers and gene dosage to quantify gene copy numbers in Candida albicans.,0
"With microsatellite marker typing, the number of alleles must be known for calculation of allelic frequencies in the diploid Candida albicans for a given locus. We describe a gene dosage with a double real-time PCR. Such a dosage should also be useful in exploring the loss of heterozygosity in C. albicans.",1
"Costa, J-M, Eloy, O, Botterel, F, Janbon, G, Bretagne, S",2
Loss of the mecA gene during storage of methicillin-resistant Staphylococcus aureus strains.,0
"The mecA gene was lost in 36 (14.4%) of 250 methicillin-resistant Staphylococcus aureus isolates after 2 years of storage at -80 degrees C with the Microbank system (Pro-lab Diagnostics, Austin, Tex.). Further analysis of 35 of these isolates confirmed loss of the mecA gene in 32 isolates. This finding has important implications for the management of strain collections.",1
"van Griethuysen, Arjanne, van Loo, Inge, van Belkum, Alex, Vandenbroucke-Grauls, Christina, Wannet, Wim, van Keulen, Peter, Kluytmans, Jan",2
Presence of DNA of human papillomavirus 16 but no other types in tumor-free tonsillar tissue.,0
"According to PCR, the prevalences of human papillomavirus (HPV) DNA were 6.3% (13 of 206) in tonsillitis or hypertrophic tonsillar tissues and 0.6% (1 of 174) in exfoliated cells from normal tonsils. HPV-16 was the only type detected in tonsillar tissues, but it did not appear to lead to L1 antibody production.",1
"Chen, Renwei, Sehr, Peter, Waterboer, Tim, Leivo, Ilmo, Pawlita, Michael, Vaheri, Antti, Aaltonen, Leena-Maija",2
Prevalence of norovirus among visitors from the United States to Mexico and Guatemala who experience traveler's diarrhea.,0
"Traveler's diarrhea (TD) is the most common infectious illness acquired by visitors to developing nations. The purpose of this study was to utilize molecular diagnostic techniques to determine the prevalence of norovirus (NoV) in TD occurring among visitors from the United States to Guatemala and Mexico. Stool samples (n = 54) were collected from 34 TD cases and analyzed for NoV by reverse transcription-PCR and oligoprobe confirmation. The overall prevalence of NoV was 65%. Interestingly, all NoV-positive stool samples were identified as genogroup I NoVs, and time spent at travel destinations was found to be an important factor in determining the frequency of infection (P = 0.003). Eleven NoV-positive stool samples also tested positive for enterotoxigenic Escherichia coli, indicating that dual infections with this leading bacterial cause of TD were very common. Results of this study suggest that NoV infection is a frequent occurrence among travelers to Mexico and Guatemala who experience episodes of TD. In addition, the simple molecular detection method utilized here will serve to facilitate more in-depth epidemiological studies of this emergent viral pathogen in travelers and other at-risk populations.",1
"Chapin, Amy R, Carpenter, Colleen M, Dudley, William C, Gibson, Lucy C, Pratdesaba, Rafael, Torres, Olga, Sanchez, Domingo, Belkind-Gerson, Jaime, Nyquist, Irene, Kärnell, Anders, Gustafsson, Bjorn, Halpern, Jane L, Bourgeois, A Louis, Schwab, Kellogg J",2
Distribution of Mycobacterium avium complex isolates in tissue samples of pigs fed peat naturally contaminated with mycobacteria as a supplement.,0
"In early 1999, there was an increased incidence of tuberculous lesions in the lymph nodes of slaughtered pigs in the Czech Republic. In part 1 of this study, tuberculous lesions were detected in 140 (62%) tissue samples collected from pigs coming from 15 farms in 15 districts at routine veterinary meat inspections in abattoirs. Mycobacteria were isolated from 37 (16%) tissue samples: 34 Mycobacterium avium subsp. hominissuis isolates and three environmentally derived mycobacteria. In search of infection sources, M. avium subsp. hominissuis was isolated from 38 (79%) samples of peat used as a feed supplement. In part 2 of our study, the head, mesenteric, and inguinal lymph nodes of 117 randomly selected slaughtered pigs from one farm with young piglets fed peat as a supplement were investigated for mycobacterial infection. From 65 (56%) pigs, a total of 76 mycobacterial isolates were identified (56 M. avium subsp. hominissuis isolates, 5 M. avium subsp. avium isolates, 3 M. intracellulare isolates, and 12 environmentally derived mycobacterial isolates). IS1245 restriction fragment length polymorphism (RFLP) types with >20 bands of 45 distinct RFLP types were found in 49 M. avium subsp. hominissuis isolates from pigs (n = 31) and peat (n = 18). Identical RFLP types were found in only four pig isolates. Five randomly selected isolates from pigs and peat were subcultured to six independent clones or colonies. Among the IS1245 RFLP types of 30 clones, identical RFLP types obtained from pigs and peat were identified, which confirmed the hypothesis that peat contaminated with mycobacteria represents a significant source of mycobacterial infection for pigs.",1
"Matlova, Ludmila, Dvorska, Lenka, Ayele, Wuhib Yayo, Bartos, Milan, Amemori, Takashi, Pavlik, Ivo",2
Predominance of porcine rotavirus G9 in Japanese piglets with diarrhea: close relationship of their VP7 genes with those of recent human G9 strains.,0
"Type G9 of group A rotavirus (GAR) was shown to be predominant in a survey of VP7 (G) and VP4 (P) genotypes among porcine GARs associated with outbreaks of diarrhea in young pigs in Japan between 2000 and 2002. Comparison of the G9 VP7 gene sequences showed that the porcine G9 strains were more closely related to human G9 strains reemerging globally since the mid-1990s than to those from the mid-1980s. The VP7 gene sequences of porcine G9 strains from different farms were divergent (6.1 to 7.2% difference in nucleotides), suggesting that these G9 VP7 genes were not the result of recent introduction into the porcine population. Regarding the P genotype specificities of porcine G9 strains, while the majority of strains were close to unusual porcine P types (P[13] and P[23]), two strains were of the P[6] type, which has closer sequence identity with the human AU19 strain than with the porcine Gottfried strain. These unexpected results suggest that G9 GARs in the porcine population have spread more widely than previously thought and that the VP7 genes of porcine G9 strains and those of some human G9 strains detected recently may have a common progenitor.",1
"Teodoroff, Tamara A, Tsunemitsu, Hiroshi, Okamoto, Kiyotora, Katsuda, Ken, Kohmoto, Mariko, Kawashima, Kenji, Nakagomi, Toyoko, Nakagomi, Osamu",2
Serotype G9 rotavirus infections in adults in Sweden.,0
"Rotavirus is a major cause of acute gastroenteritis. By examining 1,517 stool samples collected in 2001 and 2002 from Swedish adults with acute diarrhea, rotavirus was found in 3.2%, with the emerging G9P[8] serotype being the one most commonly identified (42.9%). This is the first documentation of G9 infections in adults in Europe.",1
"Rubilar-Abreu, Elba, Hedlund, Kjell-Olof, Svensson, Lennart, Mittelholzer, Christian",2
"Use of diagnostic microarrays for determination of virulence gene patterns of Escherichia coli K1, a major cause of neonatal meningitis.",0
"Forty Escherichia coli strains isolated primarily from neonatal meningitis, urinary tract infections and feces were screened for the presence of virulence genes with a newly developed microarray on the array tube format. A total of 32 gene probes specific for extraintestinal as well as intestinal E. coli pathotypes were included. Eighty-eight percent of the analyzed strains were positive for the K1-specific probe on the microarray and could be confirmed with a specific antiserum against the K1 capsular polysaccharide. The gene for the hemin receptor ChuA was predominantly found in 95% of strains. Other virulence genes associated with K1 and related strains were P, S, and F1C fimbriae specific for extraintestinal E. coli, the genes for aerobactin, the alpha-hemolysin and the cytotoxic necrotizing factor. In two strains, the O157-specific catalase gene and the gene for the low-molecular-weight heat-stable toxin AstA were detected, respectively. A total of 19 different virulence gene patterns were observed. No correlation was observed between specific virulence gene patterns and a clinical outcome. The data indicate that virulence genes typical of extraintestinal E. coli are predominantly present in K1 strains. Nevertheless, some of them can carry virulence genes known to be characteristic of intestinal E. coli. The distribution and combination of virulence genes show that K1 isolates constitute a heterogeneous group of E. coli.",1
"Korczak, Bozena, Frey, Joachim, Schrenzel, Jacques, Pluschke, Gerd, Pfister, Riccardo, Ehricht, Ralf, Kuhnert, Peter",2
Seroepidemiology of human metapneumovirus (hMPV) on the basis of a novel enzyme-linked immunosorbent assay utilizing hMPV fusion protein expressed in recombinant vesicular stomatitis virus.,0
"Human metapneumovirus (hMPV) is a newly identified human respiratory virus now recognized as a major respiratory pathogen of infants and children. To define the seroepidemiology of hMPV, we developed a novel enzyme-linked immunosorbent assay (ELISA) based on expression of the fusion protein of hMPV (hMPV F) in recombinant vesicular stomatitis virus (VSV). Western blot analysis using an hMPV F-specific antiserum confirmed the expression of hMPV in recombinant VSV. The ELISA is specific for hMPV F; antibody specific for the most closely related human paramyxovirus, respiratory syncytial virus, does not bind to hMPV F. Overall, 216 serum specimens were tested. The percentages of seropositive individuals were 89.1% in children < or =5 months old, 55.0% in children 6 to 11 months old, 36.0% in children 12 to 23 months old, 45.0% in children 24 to 47 months old, 77.3% in children 48 to 59 months old, 91.3% in children 5 to 10 years old, and 95.5% for individuals 11 to 20 years old. This is the first seroepidemiological survey of hMPV in the United States and the first analysis to determine the prevalence of antibody to a specific hMPV protein. The data suggest that exposure to hMPV is common in childhood and that hMPV F is an antigenic determinant of hMPV.",1
"Leung, Jessica, Esper, Frank, Weibel, Carla, Kahn, Jeffrey S",2
Rapid identification of staphylococcal strains from positive-testing blood culture bottles by internal transcribed spacer PCR followed by microchip gel electrophoresis.,0
"PCR analysis of the 16S-23S rRNA gene internal transcribed spacer (ITS) followed by microchip gel electrophoresis (MGE) was evaluated for its usefulness in identification of staphylococci. Forty ITS PCR patterns were demonstrated among 228 isolated colonies of Staphylococcus aureus: 26 patterns for methicillin-susceptible S. aureus (MSSA; 91 strains), 11 patterns for methicillin-resistant S. aureus (MRSA; 99 strains), and 3 patterns for both MSSA and MRSA (38 strains). Thirty-seven control strains of coagulase-negative staphylococci (CNS) representing 16 species showed unique ITS PCR patterns (24 patterns) at the species and subspecies levels: two patterns for S. caprae, S. cohnii, S. haemolyticus, and S. saprophyticus; three patterns for S. lugdunensis; four patterns for S. capitis; and one pattern for each of the other CNS species. The combined PCR-MGE method was prospectively adapted to the positive blood culture bottles, and this method correctly identified MSSA and MRSA in 102 (89%) of 114 blood cultures positive for S. aureus on the basis of the ITS PCR patterns. Eight ITS PCR patterns were demonstrated from 166 blood culture bottles positive for CNS. The most frequent CNS species isolated from blood cultures were S. epidermidis (76%), S. capitis (11%), and S. hominis (8%). Overall, all 280 blood culture bottles shown to contain a single Staphylococcus species by routine phenotypic methods were correctly identified by the PCR-MGE method at the species level, whereas the organism failed to be identified in 8 culture bottles (3%) with mixed flora. The PCR-MGE method is useful not only for rapid identification ( approximately 1.5 h) of staphylococci in positive blood culture bottles, but also for strain delineation of S. aureus.",1
"Fujita, Shin-Ichi, Senda, Yasuko, Iwagami, Thikako, Hashimoto, Takuma",2
Establishment of a universal size standard strain for use with the PulseNet standardized pulsed-field gel electrophoresis protocols: converting the national databases to the new size standard.,0
"The PulseNet National Database, established by the Centers for Disease Control and Prevention in 1996, consists of pulsed-field gel electrophoresis (PFGE) patterns obtained from isolates of food-borne pathogens (currently Escherichia coli O157:H7, Salmonella, Shigella, and Listeria) and textual information about the isolates. Electronic images and accompanying text are submitted from over 60 U.S. public health and food regulatory agency laboratories. The PFGE patterns are generated according to highly standardized PFGE protocols. Normalization and accurate comparison of gel images require the use of a well-characterized size standard in at least three lanes of each gel. Originally, a well-characterized strain of each organism was chosen as the reference standard for that particular database. The increasing number of databases, difficulty in identifying an organism-specific standard for each database, the increased range of band sizes generated by the use of additional restriction endonucleases, and the maintenance of many different organism-specific strains encouraged us to search for a more versatile and universal DNA size marker. A Salmonella serotype Braenderup strain (H9812) was chosen as the universal size standard. This strain was subjected to rigorous testing in our laboratories to ensure that it met the desired criteria, including coverage of a wide range of DNA fragment sizes, even distribution of bands, and stability of the PFGE pattern. The strategy used to convert and compare data generated by the new and old reference standards is described.",1
"Hunter, Susan B, Vauterin, Paul, Lambert-Fair, Mary Ann, Van Duyne, M Susan, Kubota, Kristy, Graves, Lewis, Wrigley, Donna, Barrett, Timothy, Ribot, Efrain",2
"Effect of clarithromycin treatment on Chlamydia pneumoniae in vascular tissue of patients with coronary artery disease: a randomized, double-blind, placebo-controlled trial.",0
"Several small clinical trials have indicated that antibiotic treatment of Chlamydia pneumoniae infection is associated with a better outcome in patients with coronary artery disease (CAD). It has not been demonstrated whether antibiotic treatment eradicates C. pneumoniae from vascular tissue. The aim of the present study was to assess the effect of clarithromycin on the presence of C. pneumoniae in the vascular tissue of patients with CAD. Patients who had CAD and who were waiting for coronary artery bypass graft surgery were enrolled in a randomized, double-blind, placebo-controlled trial. Patients were treated with clarithromycin at 500 mg or placebo once daily from the day of inclusion in the study until surgery. Several vascular tissue specimens were obtained during surgery. The presence of C. pneumoniae in vascular tissue specimens was examined by immunohistochemical staining (IHC) and two PCR assays. Chlamydia immunoglobulin G (IgG) titers were determined by an enzyme-linked immunosorbent assay at the time of inclusion in the study and 8 weeks after surgery. A total of 76 patients were included, and 180 vascular tissue specimens were obtained (80 specimens from the group treated with clarithromycin and 100 specimens from the group treated with placebo). Thirty-five patients received clarithromycin (mean duration, 27 days; standard deviation [SD], 12.2 days), and 41 patients received placebo (mean duration, 27 days; SD, 13.9 days). IHC detected the C. pneumoniae major outer membrane protein antigen in 73.8% of the specimens from the group treated with clarithromycin and 77.0% of the specimens from the group treated with placebo (P was not significant). Chlamydia lipopolysaccharide antigen was found in only one specimen from the group that received placebo. C. pneumoniae DNA was not detected in any specimen. Baseline Chlamydia-specific IgG titers were equally distributed in both groups and were not significantly different after treatment. There was no indication of an active C. pneumoniae infection in vascular tissue. Chlamydia-specific IgG titers remained unchanged throughout the study in both the antibiotic- and the placebo-treated patients.",1
"Berg, Hans F, Maraha, Boulos, van der Zee, Anneke, Gielis, Siska K, Roholl, Paul J M, Scheffer, Gert-Jan, Peeters, Marcel F, Kluytmans, Jan A J W",2
"Comparison of COBAS AMPLICOR Neisseria gonorrhoeae PCR, including confirmation with N. gonorrhoeae-specific 16S rRNA PCR, with traditional culture.",0
"A total of 3,023 clinical specimens were tested for Neisseria gonorrhoeae by using COBAS AMPLICOR (CA) PCR and confirmation of positives by N. gonorrhoeae-specific 16S rRNA PCR. The sensitivity of CA plus 16S rRNA PCR was 98.8%, compared to 68.2% for culture. Confirmation of CA positives increased the positive predictive value from 54.8 to 96.6%.",1
"Luijt, Dirk S, Bos, Petra A J, van Zwet, Anton A, van Voorst Vader, Pieter C, Schirm, Jurjen",2
Molecular subtyping and characterization of bovine and human Streptococcus agalactiae isolates.,0
"Streptococcus agalactiae causes severe invasive disease in humans and mastitis in cattle. Temporally matched bovine milk isolates and clinical human invasive isolates (52 each) collected in New York State over 18 months were characterized by molecular subtyping and phenotypic methods to probe the interspecies transmission potential of this species. EcoRI ribotyping differentiated 17 ribotypes, and DNA sequencing of the housekeeping gene sodA and the putative virulence gene hylB differentiated 7 and 17 allelic types, respectively. Human and bovine isolates were not randomly distributed between ribotypes or hylB and sodA clusters. The combined analysis of all subtyping data allowed the differentiation of 39 clonal groups; 26 groups contained only bovine isolates, and 2 groups contained both human and bovine isolates. The EcoRI ribotype diversity among bovine isolates (Simpson's numerical index of discrimination [mean +/- standard deviation], 0.90 +/- 0.05) being significantly higher than that among human isolates (0.42 +/- 0.15) further supports that these isolates represent distinct populations. Eight human isolates, but no bovine isolates, showed an IS1548 transposon insertion in hylB, which encodes a hyaluronidase. Based on data for 43 representative isolates, human isolates, on average, showed lower hyaluronidase activities than bovine isolates. Isolates with the IS1548 insertion in hylB showed no hyaluronidase activity. Human and bovine isolates did not differ in their abilities to invade HeLa human epithelial cells. Our data show that (i) EcoRI ribotyping, combined with hylB and sodA sequencing, provides a discriminatory subtype analysis of S. agalactiae; (ii) most human invasive and bovine S. agalactiae isolates represent distinct subtypes, suggesting limited interspecies transmission; and (iii) hyaluronidase activity is not required for all human infections.",1
"Sukhnanand, Sharinne, Dogan, Belgin, Ayodele, Maranatha O, Zadoks, Ruth N, Craver, Mary Patricia J, Dumas, Nellie B, Schukken, Ynte H, Boor, Kathryn J, Wiedmann, Martin",2
Human cytomegalovirus reactivation during lactation and mother-to-child transmission in preterm infants.,0
"In a clinical trial, the incidence of cytomegalovirus reactivation in breastfeeding mothers and transmission to their preterm infants were studied. Breast milk from 73 mothers as well as urine and tracheal and pharyngeal aspirates from their 89 infants were screened weekly for human cytomegalovirus (HCMV) DNA during the first 2 months after delivery. Of the 73 mothers, 48 (66%) were positive for HCMV DNA in the lactating breast. HCMV reactivation could be confirmed for 19 of 20 (95%) immunoglobulin G-positive mothers. Of the eight immunoglobulin G-negative mothers one was positive for HCMV DNA in breast milk. In only 2 out of 13 seropositive mothers with HCMV DNA in breast milk could viral DNA be detected in the peripheral blood. HCMV mother-to-child transmission was concluded for 20 of the 48 (42%) mothers positive for DNA or 7 of 19 (37%) seropositive for HCMV and positive for HCMV DNA in breast milk and one of one mother seronegative for HCMV but positive for HCMV DNA in breast milk. One mother transmitted the virus to her twins. In addition, one infant acquired postnatal HCMV infection despite the mother's being negative for HCMV DNA in breast milk; altogether, we found 22 infants with HCMV infection. In 13 of these 22 infants, virus infection occurred definitively postnatally; two of them developed severe symptomatic HCMV infection. HCMV-infected infants demonstrated higher incidences of amniotic infection, respiratory distress syndrome, bronchopulmonary dysplasia, and retinopathia praenatalis than noninfected infants, however, the differences were not statistically significant. In summary, our study confirmed a very high incidence of HCMV reactivation in mothers during lactation and a significant risk of transmission to preterm infants with the possibility of severe disease in these babies.",1
"Meier, Johannes, Lienicke, Uta, Tschirch, Edda, Krüger, Detlev H, Wauer, Roland R, Prösch, Susanna",2
Potential limitations of the 16S-23S rRNA intergenic region for molecular detection of Bartonella species.,0
"PCR targeting the 16S-23S rRNA gene intergenic transcribed spacer (ITS) region has been proposed as a rapid and reliable method for the detection of Bartonella species DNA in clinical samples. Because of variation in ITS sequences among Bartonella species, a single PCR amplification can be used to detect different species within this genus. Therefore, by targeting the ITS region, multiple PCRs or additional sample-processing steps beyond the primary amplification can be avoided when attempting to achieve molecular diagnostic detection of Bartonella species. Although PCR amplification targeting this region is considered highly sensitive, amplification specificity obviously depends on primer design. We report evidence of nonspecific PCR amplification of Mesorhizobium species with previously published primers that were designed to amplify the Bartonella consensus ITS region. Use of these or other, less species-specific, primers could lead to a false-positive diagnostic test result when evaluating clinical samples. We also report the presence of Mesorhizobium species DNA as a contaminant in molecular-grade water, a series of homologous sequences in the ITS region that are common to Bartonella and Mesorhizobium species, the amplification of Mesorhizobium DNA with unpublished primers designed in our laboratory targeting the ITS region, and the subsequent design of unambiguous ITS primers that avoid nonspecific amplification of Mesorhizobium species. Our results define some potential limitations associated with the molecular detection of Bartonella species in patient samples and indicate that primer specificity is of critical importance if the ITS region is used as a diagnostic target for detection of Bartonella species.",1
"Maggi, Ricardo G, Breitschwerdt, Edward B",2
Molecular epidemiology of meningococci isolated in Niger in 2003 shows serogroup A sequence type (ST)-7 and serogroup W135 ST-11 or ST-2881 strains.,0
"In 2003, in the Zinder and Maradi regions (Niger), epidemics were due to serogroup A:4:P1.9 meningococci belonging to sequence type 7 (ST-7). In Niamey, only sporadic cases were reported: 55% of the meningococcus strains were in serogroup A, and 38% were in serogroup W135 and could be placed in ST-11, identical to the 2002 Burkina Faso epidemic clone, and in ST-2881, a new ST.",1
"Nicolas, P, Djibo, S, Moussa, A, Tenebray, B, Boisier, P, Chanteau, S",2
Comparative typing of Campylobacter jejuni by heat-stable serotyping and PCR-based restriction fragment length polymorphism analysis.,0
"Campylobacter jejuni has become the most common bacterial cause of human gastroenteritis worldwide. Rapid, discriminatory typing methods are required to identify potential clusters of infections. The major disadvantage of the well-evaluated and widely used Penner heat-stable serotyping method is the high level of nontypeability. The correlation of the types determined by the Penner heat-stable serotyping method and PCR-based restriction fragment length polymorphism (RFLP) analysis of the lipooligosaccharide (LOS) biosynthesis genes of C. jejuni was studied with 149 C. jejuni strains. Of these strains, 79 were patient strains belonging to 25 Penner serotypes, 60 were nontypeable patient strains, and 10 were reference strains. A 9.6-kb DNA fragment of the LOS gene cluster was amplified and digested with the restriction enzymes HhaI and DdeI. Altogether, 39 different RFLP types (including 30 HhaI profiles and 32 DdeI profiles) were identified. Type Hh1Dd1 was the most common type, with 36% of the strains and strains of 12 serotypes being of this type. A high level of discrimination was obtained, and a correlation between the Penner serotypes and the PCR-RFLP types could be seen. Also, variation in the LOS biosynthesis genes within a single Penner serotype was found. Although the PCR-RFLP method may not be sufficient to compensate for Penner serotyping, it can give valuable information about nontypeable strains and further characterize strains of common serotypes.",1
"Nakari, Ulla-Maija, Laaksonen, Katja, Korkeila, Maija, Siitonen, Anja",2
Fatal peritonitis caused by Pasteurella multocida capsular type F in calves.,0
"A fatal case of atypical septicemia of pasteurellosis in veal calves is described. The causative organism was identified as a multiresistant Pasteurella multocida capsular type F isolate. The outbreak was characterized by fibrinous peritonitis and mortality, which are hitherto unreported features of P. multocida capsular type F infections.",1
"Catry, Boudewijn, Chiers, Koen, Schwarz, Stefan, Kehrenberg, Corinna, Decostere, Annemie, de Kruif, Aart",2
Molecular epidemiology of Shigella flexneri in a long-stay psychiatric nursing center during 2001 to 2003.,0
"With six separate wards accommodating more than 1,600 patients, V Nursing Center (VNC) is a long-stay psychiatric nursing center in eastern Taiwan. During 2001 to 2003, 39 shigellosis cases occurred in VNC. Different from the notion that most cases of shigellosis are caused by Shigella sonnei, all except one of these cases were caused by S. flexneri, with the remaining one caused by an S. sonnei isolate. O-antigen serotyping showed that the 38 S. flexneri strains were of either type 1a (n = 20) or 4a (n = 18), two less prevalent serotypes in Taiwan. NotI-based pulsed-field gel electrophoresis analyses performed with 8 type 1a non-VNC strains and 9 type 4a non-VNC strains isolated from 1996 to 2003 for comparison divided the 28 type 1a strains and the 27 type 4a strains into 7 and 10 subtypes, designated subtypes P1A to P1G and subtypes P4A to P4J, respectively. Subtypes P1A and P4A, which appeared in three consecutive years in VNC as well as outside of VNC, are the most prevalent subtypes. Analyses of the relatedness of the VNC strains on the basis of the banding patterns grouped the type 1a and 4a strains into four and five clusters, respectively. All except one of the type 1a strains had 95% similarity, indicating that they had a common parent, whereas the type 4a strains had similarities that ranged from 77 to 93%, suggesting that they were of diverse origins. In two of the outbreaks, less related subtypes of the type 4a strains were found in the same VNC wards in consecutive years, suggesting the possible existence of different subtypes in VNC all the time. Antibiotic susceptibility testing showed that all except one of the S. flexneri strains were sensitive to at least seven antibiotics; the remaining isolate was sensitive to three antibiotics. The data from the latter tests should be helpful for selection of proper treatments for S. flexneri infections in Taiwan.",1
"Lee, Yeong-Sheng, Liu, Ming-Ching, Ko, Ching-Fen, Lu, Cheng-Hsiung, Tseng, Yi-Hsiung",2
Detection and identification of Ehrlichia spp. in ticks collected in Tunisia and Morocco.,0
"A broad-range 16S rRNA gene PCR assay followed by partial sequencing of the 16S rRNA gene was used for the detection of members of the family Anaplasmataceae in ticks in North Africa. A total of 418 questing Ixodes ricinus ticks collected in Tunisia and Morocco, as well as 188 Rhipicephalus ticks from dogs and 52 Hyalomma ticks from bovines in Tunisia, were included in this study. Of 324 adult I. ricinus ticks, 16.3% were positive for Ehrlichia spp., whereas only 3.4 and 2.8% of nymphs and larvae, respectively, were positive. A large heterogeneity was observed in the nucleotide sequences. Partial sequences identical to that of the agent of human granulocytic ehrlichiosis (HGE) were detected in I. ricinus and Hyalomma detritum, whereas partial sequences identical to that of Anaplasma platys were detected in Rhipicephalus sanguineus. However, variants of Anaplasma, provisionally designated Anaplasma-like, were predominant in the I. ricinus tick population in Maghreb. Otherwise, two variants of the genus Ehrlichia were detected in I. ricinus and H. detritum. Surprisingly, a variant of Wolbachia pipientis was evidenced from I. ricinus in Morocco. These results emphasized the potential risk of tick bites for human and animal populations in North Africa.",1
"Sarih, M'Hammed, M'Ghirbi, Youmna, Bouattour, Ali, Gern, Lise, Baranton, Guy, Postic, Danièle",2
Evaluation of four commercially available extended-spectrum beta-lactamase phenotypic confirmation tests.,0
"Extended-spectrum beta-lactamase (ESBL) production in members of the Enterobacteriaceae can confer resistance to extended-spectrum cephalosporins, aztreonam, and penicillin. As such, the accurate detection of ESBL producers is essential for the appropriate selection of antibiotic therapy. Twenty previously characterized isolates and 49 clinical isolates suspected of ESBL production were tested by four ESBL phenotypic confirmatory methods for accuracy and ease of use. The four ESBL phenotypic confirmation tests included Dried MicroScan ESBL plus ESBL Confirmation panels (Dade Behring, Inc., West Sacramento, Calif.), Etest ESBL (AB BIODISK, Piscataway, N.J.), Vitek GNS-120 (bioMerieux, Inc., Hazelwood, Mo.), and BD BBL Sensi-Disk ESBL Confirmatory Test disks (BD Biosciences, Sparks, Md.). Results were compared to frozen microdilution panels prepared according to NCCLS specifications, and discrepant isolates were sent for molecular testing. The test sensitivities for the ESBL phenotypic confirmatory test methods used in this study were as follows: MicroScan ESBL plus ESBL confirmation panel, 100%; VITEK 1 GNS-120, 99%; Etest ESBL, 97%; and BD BBL Sensi-Disk ESBL Confirmatory Test disks, 96%. The test specificities were as follows: BD BBL Sensi-Disk ESBL Confirmatory Test disks, 100%; MicroScan ESBL plus ESBL confirmation panel and VITEK 1 GNS-120, 98%; and Etest ESBL, 94%. All methods were easy to perform; however, the Etest method required more expertise to interpret the results. All tests offer a feasible solution for confirming ESBL production in the clinical laboratory.",1
"Linscott, Andrea J, Brown, William J",2
Differentiation between atypical isolates of Candida lusitaniae and Candida pulcherrima by determination of mating type.,0
"We report on five clinical isolates routinely identified as Candida lusitaniae that the ID 32C system was unable to discriminate from the closely related species Candida pulcherrima. When additional tests did not allow accurate identification, the less usual mating type test identified all of them as Clavispora lusitaniae. Mating type testing appears to be a valuable tool for assessing the true incidence of this emerging non-albicans Candida species.",1
"Noël, Thierry, Favel, Anne, Michel-Nguyen, Annie, Goumar, Abdelhak, Fallague, Karim, Chastin, Christiane, Leclerc, Florence, Villard, Jean",2
Role of real-time molecular typing in the surveillance of Campylobacter enteritis and comparison of pulsed-field gel electrophoresis profiles from chicken and human isolates.,0
"The goal of the present study was to assess the contribution of real-time molecular typing, used alone or with clinical surveillance, to the prompt identification of clusters of Campylobacter enteritis. Potential poultry sources were sought by comparing the pulsed-field gel electrophoresis genotypes of human and fresh whole retail chicken isolates collected during the same study period. Among 183 human isolates, 82 (45%) had unique genotypes, 72 (39%) represented 26 clusters of 2 to 7 isolates each, and 29 (16%) represented three clusters of 8 to 11 isolates each. Molecular typing was useful for the confirmation of outbreaks suspected on the basis of epidemiological surveillance, but for most small clusters, no epidemiological link could be established. Thus, the added value of real-time molecular typing is questionable, since the numerous small clusters identified were of unclear public health significance. Among 177 chickens, 41 (23%) yielded campylobacter isolates; of these, 19 (46%) had genotypes similar to those of 41 (22%) human isolates. However, a temporal association was demonstrated in only a minority of cases, and most genotypes were present only in a single species, suggesting that sources other than chickens are important in human campylobacteriosis. Further investigation with samples from water and other possible environmental sources is needed to define the most efficient strategy for the application of molecular typing and identification of the source(s) of sporadic cases of campylobacteriosis.",1
"Michaud, Sophie, Ménard, Suzanne, Arbeit, Robert D",2
Systematic molecular characterization of multidrug-resistant Mycobacterium tuberculosis complex isolates from Spain.,0
"We used spoligotyping and restriction fragment length polymorphism (RFLP) of the IS6110-insertion sequence to study the molecular epidemiology of multidrug-resistant (MDR) tuberculosis in Spain. We analyzed 180 Mycobacterium tuberculosis complex isolates collected between January 1998 and December 2000. Consecutive isolates from the same patients (n = 23) always had identical genotypes, meaning that no cases of reinfection occurred. A total of 105 isolates (58.3%) had unique RFLP patterns, whereas 75 isolates (41.7%) were in 20 different RFLP clusters. Characterization of the katG and rpoB genes showed that 14 strains included in the RFLP clusters did not actually cluster. Only 33.8% of the strains isolated were suggestive of MDR transmission, a frequency lower than that for susceptible strains in Spain (46.6%). We found that the Beijing/W genotype, which is prevalent worldwide, was significantly associated with immigrants. The 22 isolates in the largest cluster corresponded to the Mycobacterium bovis strain responsible for two nosocomial MDR outbreaks in Spain.",1
"Samper, S, Iglesias, M J, Rabanaque, M J, Gómez, L I, Lafoz, M C, Jiménez, M S, Ortega, A, Lezcano, M A, Van Soolingen, D, Martín, C",2
Molecular epidemiology of macrolide-resistant Streptococcus pneumoniae isolates in Europe.,0
"In many European countries, the level of pneumococcal resistance to macrolides has now passed the level of resistance to penicillin G. A total of 82 erythromycin A-resistant isolates of Streptococcus pneumoniae were collected by 11 laboratories in seven European countries. All of the isolates were tested for antimicrobial susceptibility, analyzed for clonal relatedness by multilocus sequence typing, and characterized for macrolide resistance genotypes. The prevalence of the macrolide resistance genotypes varied substantially between countries. In France (87.5% of all strains), Spain (77.3%), Switzerland (80%), and Poland (100%), strains were predominantly erm(B) positive, whereas higher levels of mef(A)-positive strains were reported from Greece (100%) and Germany (33.3%). Macrolide resistance was caused by the oligoclonal spread of some multilocus sequence types, but significant differences in clonal distribution were noted between France and Spain, countries from which high levels of macrolide resistance have been reported. Overall, sequence type 81 (Spain23F-1 clone) was by far the most widespread. The mainly erm(B)-positive serotype 14 clone (sequence type 143), first reported in Poland in the mid-1990s, is now widespread in France.",1
"Reinert, Ralf René, Ringelstein, Adrian, van der Linden, Mark, Cil, Murat Yücel, Al-Lahham, Adnan, Schmitz, Franz-Josef",2
Detection of human metapneumovirus RNA sequences in nasopharyngeal aspirates of young French children with acute bronchiolitis by real-time reverse transcriptase PCR and phylogenetic analysis.,0
"Human metapneumovirus (HMPV) was the unique viral pathogen detected by a real-time reverse transcriptase PCR (RT-PCR) assay in 6 (6.4%) of 94 consecutive French children hospitalized for acute bronchiolitis from September 2001 to June 2002. This virus was identified as the third etiological cause of bronchiolitis, after respiratory syncytial virus and rhinovirus (35 [37%] and 21 [22%] of 94 cases, respectively). Phylogenetic analysis of F-gene sequences demonstrated the cocirculation of distinct HMPV genotypes during this study. These findings highlight the need to implement a rapid HMPV RT-PCR detection assay for the clinical diagnosis of respiratory infections in pediatric patients with bronchiolitis.",1
"Bouscambert-Duchamp, Maude, Lina, Bruno, Trompette, Aurélien, Moret, Hélène, Motte, Jacques, Andréoletti, Laurent",2
Characterization of virulence plasmids and serotyping of rhodococcus equi isolates from submaxillary lymph nodes of pigs in Hungary.,0
"The plasmid types and serotypes of 164 Rhodococcus equi strains obtained from submaxillary lymph nodes of swine from different piggeries in 28 villages and towns located throughout the country were examined. The strains were tested by PCR for the presence of 15- to 17-kDa virulence-associated protein antigen (VapA) and 20-kDa virulence-associated protein antigen (VapB) genes. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphism characteristics. None of the 164 isolates contained the vapA gene, and 44 (26.8%) isolates were positive for the vapB gene, showing a product of the expected 827-bp size in the PCR amplification. The 44 isolates of intermediate virulence contained virulence plasmids that were identified as types 1 (3 isolates), 4 (1 isolate), 5 (36 isolates), 6 (1 isolate), and 7 (2 isolates) and as a new variant (1 isolate). On the basis of restriction digestion patterns of plasmid DNAs, we tentatively designated the variant as type 17. Use of the serotyping method of Prescott showed that 110 (67.1%) out of the 164 isolates were typeable and that serotype 2 predominated (83 isolates [50.6%]), followed by serotype 1 (26 strains [15.9%]). Only one isolate belonged to serotype 3. A total of 54 (32.9%) isolates were untypeable in Prescott's system. The prevalence of R. equi strains of intermediate virulence among the isolates that came from the submaxillary lymph nodes of swine in Hungary was lower than that seen with isolates obtained elsewhere.",1
"Makrai, László, Takayama, Saki, Dénes, Béla, Hajtós, István, Sasaki, Yukako, Kakuda, Tsutomu, Tsubaki, Shiro, Major, Andrea, Fodor, László, Varga, János, Takai, Shinji",2
Multiplex real-time PCR assay using Scorpion probes and DNA capture for genotype-specific detection of Giardia lamblia on fecal samples.,0
"Two major genotypic assemblages of Giardia lamblia infect humans; the epidemiologic significance of this phenomenon is poorly understood. We developed a single-vessel multiplex real-time PCR (qPCR) assay that genotypes Giardia infections into assemblages A and/or B directly from fecal samples. The assay utilized Scorpion probes that combined genotype-specific primers and probes for the 18S rRNA gene into the same molecule. The protocol was capable of detecting as few as 20 trophozoites per PCR on fecal DNA isolated using a commercial method or 1.25 trophozoites per PCR on fecal DNA isolated using a G. lamblia-specific oligonucleotide capture technique. The assay was specific for fecal specimens, with no amplification of the discordant genotype with the opposite Scorpion probe. When 97 clinical specimens from Bangladesh were used, the multiplex PCR assay detected 95% (21 of 22) of Giardia microscopy-positive specimens and 18% (13 of 74) of microscopy-negative specimens. Microscopy-negative and qPCR-positive specimens had higher average cycle threshold values than microscopy-positive and qPCR-positive specimens, suggesting that they represented true low-burden infections. Most (32 of 35) infections were assemblage B infections. This single-reaction multiplex qPCR assay distinguishes assemblage A Giardia infections from assemblage B infections directly on fecal samples and may aid epidemiologic investigation.",1
"Ng, Cherie T, Gilchrist, Carol A, Lane, Ariel, Roy, Shantanu, Haque, Rashidul, Houpt, Eric R",2
Arthrobacter scleromae sp. nov. isolated from human clinical specimens.,0
"A gram-positive, coryneform bacterium was isolated from swollen scleromata of a dermatosis patient. An analysis of its phenotypic, chemotaxonomic, and genotypic characteristics showed that this bacterium is closely associated with Arthrobacter oxydans and Arthrobacter polychromogenes but that it belongs to a distinct species, for which the name Arthrobacter scleromae sp. nov. is proposed.",1
"Huang, Ying, Zhao, Naixin, He, Liang, Wang, Liming, Liu, Zhiheng, You, Min, Guan, Fulai",2
Epidemiologic import of tuberculosis cases whose isolates have similar but not identical IS6110 restriction fragment length polymorphism patterns.,0
"Isolates of Mycobacterium tuberculosis from patients with epidemiologic links frequently demonstrate identical IS6110 restriction fragment length polymorphism (RFLP) patterns (i.e., RFLP clustering) because they are infected with the same strain. Uncertainty arises with isolates that differ from one another by a few IS6110 hybridizing bands. During the period from 1 January 1996 to 31 December 1999, isolates from 585 tuberculosis (TB) cases were analyzed by RFLP, representing 98.2% of the 596 culture-positive TB cases reported in Arkansas during the study period. Of the 585 cases for which RFLP was available, 419 (71.6%) had an RFLP pattern with more than five copies of IS6110. Of the total 74 clusters, 48 comprised isolates with more than five copies of IS6110 and included 164 cases. Sixty-nine isolates with more than five copies of IS6110 comprising 16 clusters and 60 unique isolates were found to be similar to at least 1 other isolate (differing from it by one or two hybridizing bands). Among the 129 cases whose isolates were similar to other clustered or unique isolates, 16 cases were discovered with epidemiologic links: 14 (15.2%) were among the 92 cases with IS6110 RFLP patterns similar to those in clusters, and 2 (5.2%) were among the 37 unique cases that were similar to another unique case. The isolates from the epidemiologically linked patients shared common spoligotypes; all except one case shared common polymorphic GC-rich sequence (PGRS) patterns. Of the 129 patients whose isolates differed from another by one or two hybridizing IS6110 bands, 101 (78.3%) shared common spoligotypes and 87 (67.4%) shared common PGRS RFLP patterns.",1
"Cave, M D, Yang, Z H, Stefanova, R, Fomukong, N, Ijaz, K, Bates, J, Eisenach, K D",2
Systemic disease in Vaal rhebok (Pelea capreolus) caused by mycoplasmas in the mycoides cluster.,0
"In the winter of 2002, an outbreak of mycoplasma infection in Vaal rhebok (Pelea capreolus) originating from South Africa occurred 15 weeks after their arrival in San Diego, Calif. Three rhebok developed inappetence, weight loss, lethargy, signs related to pulmonary or arthral dysfunction, and sepsis. All three rhebok died or were euthanized. Primary postmortem findings were erosive tracheitis, pleuropneumonia, regional cellulitis, and necrotizing lymphadenitis. Mycoplasmas were detected in numerous tissues by electron microscopy, immunohistochemistry, and PCR. The three deceased rhebok were coinfected with ovine herpesvirus-2, and two animals additionally had a novel gammaherpesvirus. However, no lesions indicative of herpesvirus were seen microscopically in any animal. The rheboks' mycoplasmas were characterized at the level of the 16S rRNA gene, the 16S-23S intergenic spacer region, and the fructose biphosphate aldolase gene. Denaturing gradient gel electrophoresis was carried out to address the possibility of infection with multiple strains. Two of the deceased rhebok were infected with a single strain of Mycoplasma capricolum subsp. capricolum, and the third animal had a single, unique strain most closely related to Mycoplasma mycoides subsp. mycoides large-colony. A PCR survey of DNA samples from 46 other ruminant species demonstrated the presence of several species of mycoplasmas in the mycoides cluster, including a strain of M. capricolum subsp. capricolum identical to that found in two of the rhebok. These findings demonstrate the pervasiveness of mycoplasmas in the mycoides cluster in small ruminants and the potential for interspecies transmission and disease when different animal taxa come in contact.",1
"Nicolas, Melissa M, Stalis, Ilse H, Clippinger, Tracy L, Busch, Martin, Nordhausen, Robert, Maalouf, Gabriel, Schrenzel, Mark D",2
Detection of cryptosporidium and identification to the species level by nested PCR and restriction fragment length polymorphism.,0
"Cryptosporidiosis is an emerging protozoan disease associated with large waterborne outbreaks. Diagnosis relies on microscopic examination of stools, but this method cannot identify the infecting species of Cryptosporidium. We have developed a test based on nested PCR and restriction fragment length polymorphism (RFLP) that offers simple identification of Cryptosporidium hominis, Cryptosporidium parvum, and most other human infective species in stool samples. Purified C. parvum oocysts were used for PCR development. Extracted DNA was amplified by nested PCR targeting a 214-bp fragment of the 18S RNA gene. Enzymatic restriction sites were identified by bioinformatic analysis of all published Cryptosporidium 18S rRNA sequences. Experiments with spiked stool samples gave an estimated PCR detection limit of one oocyst. Specificity was assessed by testing 68 stool samples from patients with microscopically proven cryptosporidiosis and 31 Cryptosporidium-negative stools. Sixty-seven (98.5%) of the 68 stool samples from patients with microscopically proven cryptosporidiosis and 2 of the other stool samples were positive by PCR and could be genotyped. RFLP analysis identified 36 C. hominis, 19 C. parvum, 8 Cryptosporidium meleagridis, and 6 Cryptosporidium felis or Cryptosporidium canis samples. Species determination in 26 PCR-positive cases was in full agreement with DNA sequencing of the 18S rRNA hypervariable region. The excellent sensitivity of PCR, coupled with the accuracy of RFLP for species identification, make this method a suitable tool for routine diagnosis and genotyping of Cryptosporidium in stools.",1
"Coupe, Stephane, Sarfati, Claudine, Hamane, Samia, Derouin, Francis",2
Confirming positive results of nucleic acid amplification tests (NAATs) for Chlamydia trachomatis: all NAATs are not created equal.,0
"The Centers for Disease Control and Prevention recommended confirming positive screening tests for Chlamydia trachomatis when positive predictive values are <90%. It is accepted that less sensitive tests (i.e., culture and immunoassays) should not be used to confirm the results of more sensitive nucleic acid amplification tests (NAATs). We show that the same principle applies when NAATs are used for confirmation.",1
"Schachter, J, Hook, E W, Martin, D H, Willis, D, Fine, P, Fuller, D, Jordan, J, Janda, W M, Chernesky, M",2
Extended-spectrum beta-lactamase-producing Shiga toxin gene (Stx1)-positive Escherichia coli O26:H11: a new concern.,0
"Escherichia coli strain TUM2139 was isolated from a stool sample from a 9-year-old girl on 16 June 2004. This strain was categorized as Shiga toxin-producing Escherichia coli (STEC) because the Shiga-like toxin gene stx(1) was detected by immunochromatography and PCR assay. The strain was highly resistant to cefotaxime (256 microg/ml) and was also resistant to cefepime, cefpodoxime, ceftriaxone, and aztreonam. In the presence of 4 microg of clavulanic acid per ml, the MIC of cefotaxime decreased to < or =0.12 microg/ml, indicating that this strain was an extended-spectrum beta-lactamase (ESBL) producer. Cefotaxime resistance was transferred to E. coli C600 by conjugation at a frequency of 3.0 x 10(-6). A PCR assay was performed with primer sets specific for TEM-type and SHV-type ESBLs and for the CTX-M-2 (Toho-1), CTX-M-3, and CTX-M-9 groups of ESBLs. A specific signal was observed with the primer set specific for the CTX-M-9 group of beta-lactamases. This beta-lactamase was confirmed to be the ESBL CTX-M-18 by DNA sequencing. This is the first report of an ESBL-producing STEC isolate.",1
"Ishii, Yoshikazu, Kimura, Soichiro, Alba, Jimena, Shiroto, Katsuaki, Otsuka, Masanobu, Hashizume, Naotaka, Tamura, Kazumichi, Yamaguchi, Keizo",2
Genomic relatedness of the new Matlab variants of Vibrio cholerae O1 to the classical and El Tor biotypes as determined by pulsed-field gel electrophoresis.,0
"The genomes of the recently described Matlab variants of Vibrio cholerae O1 that are hybrids between classical and El Tor biotypes were compared with those of El Tor and classical biotypes by the use of pulsed-field gel electrophoresis. Dendrograms constructed using the unweighted-pair group method using average linkages generated from NotI restriction patterns of whole-chromosomal DNA grouped these strains into two major clusters that were found to be similar but not identical to those of either of the biotypes. Strains that clustered with the classical biotype appear to have been derived from the classical strains, which are thought to be extinct.",1
"Safa, Ashrafus, Bhuiyan, Nurul Amin, Alam, Munirul, Sack, David A, Nair, G Balakrish",2
CHROMagar Candida as the sole primary medium for isolation of yeasts and as a source medium for the rapid-assimilation-of-trehalose test.,0
"The chromogenic medium BBL CHROMagar Candida (CAC) was evaluated as a sole primary medium for the isolation of yeasts from clinical specimens in which yeasts are the primary concern. Additionally, the reliability of the rapid-assimilation-of-trehalose (RAT) test in yielding correct results with isolates taken from CAC was assessed. A total of 270 throat, urine, and genital (TUG) specimens were streaked onto CAC, Sabouraud dextrose agar (SDA), inhibitory mold agar (IMA), and Mycosel (MYC). A total of 69 blood culture broths that were smear positive for yeast were streaked onto CAC and SDA. A 1-h RAT test (NCCLS M35-A) was performed simultaneously on isolates from CAC and SDA. A total of 112 TUG specimens yielded yeast colonies (CAC, 111 colonies; IMA, 105; SDA, 103; MYC, 91). The 69 blood culture yeasts grew on both CAC and SDA. Mixed cultures of yeasts were detected on 11 CAC plates but were unrecognized on other media. Colonies suspected of being C. glabrata on 32 CAC plates were all RAT test positive and confirmed to be C. glabrata; of 59 colonies with various characteristics of color and morphology on CAC, none were RAT positive, and all were conventionally identified as yeasts other than C. glabrata (sensitivity and specificity, 100%). The same isolates from SDA tested for RAT produced six false negatives and no false positives (sensitivity, 81%; specificity, 100%). The results show that CAC can be used as the sole primary medium for recovery of yeasts from clinical specimens. Additionally, isolates grown on CAC yield excellent results with the RAT test utilized in this study.",1
"Murray, Melissa P, Zinchuk, Riva, Larone, Davise H",2
"Analysis of the influence of Tween concentration, inoculum size, assay medium, and reading time on susceptibility testing of Aspergillus spp.",0
"The influence of several test variables on susceptibility testing of Aspergillus spp. was assessed. A collection of 28 clinical isolates was tested against amphotericin B, itraconazole, voriconazole, and terbinafine. Inoculum size (10(4) CFU/ml versus 10(5) CFU/ml) and glucose supplementation (0.2% versus 2%) did not have significant effects on antifungal susceptibility testing results and higher inoculum size and glucose concentration did not falsely elevate MICs. In addition, antifungal susceptibility testing procedure with an inoculum size of 10(5) CFU/ml distinctly differentiated amphotericin B or itraconazole-resistant Aspergillus strains in vivo from the susceptible ones. Time of incubation significantly affected the final values of MICs, showing major increases (two to six twofold dilutions, P < 0.01 by analysis of variance) between MIC readings at 24 and 48 h, but no differences were observed between antifungal susceptibility testing results obtained at 48 h and at 72 h. Significantly higher MICs were uniformly associated with higher concentrations of Tween (P < 0.01), used as a dispersing agent in the preparation of inoculum suspensions. The geometric mean MICs showed increases of between 1.5- and 10-fold when the Tween concentration varied from 0.1% (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.29, 0.69, 1.06, and 0.64 mug/ml, respectively) to 5% (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.97, 5.79, 1.60, and 4.66 mug/ml, respectively). The inhibitory effect of Tween was clearly increased with inoculum sizes of 10(5) CFU/ml and was particularly dramatic for itraconazole, terbinafine, and Aspergillus terreus. The inoculum effect was not observed when the Tween concentration was below 0.5% (P > 0.01).",1
"Gomez-Lopez, Alicia, Aberkane, Amel, Petrikkou, Eva, Mellado, Emilia, Rodriguez-Tudela, Juan Luis, Cuenca-Estrella, Manuel",2
Epidemiology of human sporotrichosis investigated by amplified fragment length polymorphism.,0
"Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of Peruvian strains of Sporothrix schenckii and to compare them to a panel of non-Peruvian strains. AFLP analysis suggests that the Peruvian strains can be divided into two homogeneous clusters with no reference to geographical origin or the clinical form of sporotrichosis. The strains from abroad present heterogeneous profiles, with the Bolivian strain and the Colombian strains related to one of the Peruvian population. Sequencing of internal transcribed spacer 2, used to examine the relationships over a longer distance, confirmed the division of Peruvian strains into two populations that can be identified on the basis of a single but specific sequence divergence. This paper introduces automated AFLP analysis as a valuable tool for further investigation of the epidemiology and ecology of S. schenckii.",1
"Neyra, Edgar, Fonteyne, Pierre-Alain, Swinne, Danielle, Fauche, Frederic, Bustamante, Beatriz, Nolard, Nicole",2
Characterization of rotavirus strains in a Danish population: high frequency of mixed infections and diversity within the VP4 gene of P[8] strains.,0
"We characterized the G and P types from 162 rotavirus-positive stool specimens collected from 162 persons in Denmark (134 children and 28 adults) with acute diarrhea in 1998, 2000, and 2002. Samples were obtained during outpatient consultations (73%) and from hospitalized patients (27%). Although more than 20 different G-P combinations were identified, only 52% represented the globally most common types G1P[8], G2P[4], and G4P[8]. The G9 genotype, which is emerging worldwide, was identified in 12% of all samples. Twenty-one percent of the samples were of mixed genotypic origin, which is the highest frequency reported in any European population. The standard reverse transcription-PCR methods initially failed to identify a considerable fraction of the rotavirus P strains due to mutations at the VP4 primer-binding sites of P[8] strains. The application of a degenerate P[8] primer resulted in typing of most VP4 strains. There was considerable year-to-year variation among the circulating G-P types, and whereas G1P[8] was predominant in 1998 (42% of samples) and 2002 (26%), G2P[4] was the strain that was most frequently detected in 2000 (26% of samples). Our findings might implicate challenges for rotavirus vaccine implementation in a European population and underscore the importance of extensive strain surveillance prior to, during, and after introduction of any vaccine candidate.",1
"Fischer, T K, Eugen-Olsen, J, Pedersen, A G, Mølbak, K, Böttiger, B, Rostgaard, K, Nielsen, N M",2
"Molecular epidemiology of norovirus infections in Stockholm, Sweden, during the years 2000 to 2003: association of the GGIIb genetic cluster with infection in children.",0
"The incidence of norovirus-associated gastroenteritis and the molecular epidemiology of norovirus strains were studied during three seasons (2000-2001, 2001-2002, and 2002-2003) among patients of all ages, mainly from the Stockholm region in Sweden. A total of 3,252 fecal samples were analyzed by reverse transcription-PCR. The incidences of norovirus infection among adults were 23, 26, and 30% during the three seasons studied and 18, 11, and 15% among children 0 to 15 years of age. During the first season, all norovirus strains detected by PCR were typed either by reverse line blot hybridization or nucleotide sequence analysis. During the two successive seasons, a total of 60 norovirus-positive strains from the beginning, peak, and end of the seasons were selected for nucleotide sequence analysis. We identified two dominant norovirus variants over the seasons: a new norovirus variant, recently described as the GGIIb genetic cluster, dominated among children during the first season, and during the following two seasons, a GGII-4 variant dominated. Our data suggest that norovirus infections are common, not only among adults, but also among children, and that some strains may predominantly affect children.",1
"Lindell, Annika Tiveljung, Grillner, Lena, Svensson, Lennart, Wirgart, Benita Zweygberg",2
Vi antigen expression in Salmonella enterica serovar Typhi clinical isolates from Pakistan.,0
"The accurate identification of Salmonella enterica subsp. enterica serovar Typhi variants that fail to express the capsular polysaccharide, Vi, is an important and much discussed issue for medical microbiology. We have tested a multiplex PCR method which shows the presence or absence of the genetic locus required for Vi expression. Of 2,222 Salmonella serovar Typhi clinical isolates collected from patients' blood over a 4-year period in a region of Pakistan where typhoid is endemic, 12 tested negative for Vi expression by serological agglutination. However, only 1 of these 12 was Vi negative by the multiplex PCR method. This result was confirmed by immunofluorescence, the most sensitive method for Vi characterization in Salmonella serovar Typhi. The multiplex PCR described therefore represents a simple and accurate method for surveillance for Vi-negative variants of Salmonella serovar Typhi in Pakistan. Testing of clinical isolates of Salmonella serovar Typhi, before subculture, from other regions where Vi-negative Salmonella serovar Typhi has been described should be carried out so that the impact of vaccination with purified Vi antigen on the levels of Vi-negative Salmonella serovar Typhi in bacterial populations can be assessed.",1
"Wain, John, House, Deborah, Zafar, Afia, Baker, Stephen, Nair, Satheesh, Kidgell, Claire, Bhutta, Zulfiqar, Dougan, Gordon, Hasan, Rumina",2
Ascariasis is a zoonosis in denmark.,0
"A preliminary epidemiological survey indicated an association between Ascaris infections in Danish patients and contact with pigs or pig manure. In the present study, we compared Ascaris worms collected from humans and Ascaris worms collected from pigs by amplified fragment length polymorphism (AFLP) analysis, a technique for whole-genome fingerprinting, and by PCR-linked restricted fragment length polymorphism (PCR-RFLP) analysis of the internal transcribed spacer region of nuclear rDNA. The AFLP data were analyzed by distance- and model-based clustering methods. These results assigned Ascaris worms from Danish patients to a cluster different from that for worms from humans in other geographic areas. In contrast, worms from humans and pigs in Denmark were assigned to the same cluster. These results were supported by the PCR-RFLP results. Thus, all of the examined Danish patients had acquired Ascaris infections from domestic pigs; ascariasis may therefore be considered a zoonotic disease in Denmark.",1
"Nejsum, Peter, Parker, E Davis, Frydenberg, Jane, Roepstorff, Allan, Boes, Jaap, Haque, Rashidul, Astrup, Ingrid, Prag, Jørgen, Skov Sørensen, Uffe B",2
Genetic variability among serotype G4 Italian human rotaviruses.,0
"A total of 254 serotype GH rotavirus strains were detected in Palermo, Italy, from 1985 to 2003. Out of 38 serotype G4 strains selected for genetic analysis, 14 were recognized by genotyping as type G9. Strains confirmed to belong to the G4 type showed temporal patterns of genetic evolution in their VP7 and VP4 gene sequences, and the latest Italian G4 strains were distantly related to the reference vaccinal ST3 strain.",1
"Arista, S, Giammanco, G M, De Grazia, S, Colomba, C, Martella, V",2
Sensitive and specific detection of staphylococcal epidermolysins A and B in broth cultures by flow cytometry-assisted multiplex immunoassay.,0
"Two of the most common bacterial skin infections of young infants and children are bullous impetigo due to Staphylococcus aureus and its more acute form, staphylococcal scalded skin syndrome. Epidermolysin A (ETA), ETB and, possibly, ETD are responsible for these diseases, which may appear as epidemics in pediatric patients. We tested the reliability of a flow cytometry-assisted multiplex immunoassay (Bio-Plex system) for the detection of ETA and ETB. The Bio-Plex system was found to be highly specific and highly sensitive for toxin concentrations of between 2 and 80,000 pg/ml. The results of this assay were 100% identical to the results of a PCR-based method. We demonstrated that this test did not generate any cross-reactions with ETD-producing isolates. The level of detection of ETB by this test differed according to culture conditions and from isolate to isolate; these results must be taken into account for diagnostic purposes.",1
"Joubert, Olivier, Keller, Daniel, Pinck, Anne, Monteil, Henri, Prévost, Gilles",2
Detection of human metapneumovirus antigens in nasopharyngeal secretions by an immunofluorescent-antibody test.,0
"Human metapneumovirus (hMPV) is a recently discovered pathogen associated with respiratory tract infections, primarily in young children, immunocompromised individuals, and elderly individuals. Reverse transcription-PCR (RT-PCR) has been reported to be a more sensitive method for the diagnosis of hMPV infections than virus isolation by culture and serological study. However, there has been no report on rapid methods, such as an immunofluorescent-antibody test or an enzyme-linked immunosorbent assay, for the detection of hMPV antigens in nasopharyngeal secretions. In this study, we compared an indirect immunofluorescent-antibody test (IFA) with a monoclonal antibody with RT-PCR for detection of hMPV in nasal secretions from 48 hospitalized children with respiratory tract infections. Fifteen of the 48 children were positive for hMPV by RT-PCR. IFA results were positive for 11 of the 15 RT-PCR-positive children (sensitivity, 73.3%) and 1 of the 33 RT-PCR-negative children (specificity, 97.0%). Although the sensitivity of IFA is lower than that of RT-PCR, IFA is a rapid and useful test for the diagnosis of hMPV infections in children.",1
"Ebihara, Takashi, Endo, Rika, Ma, Xiaoming, Ishiguro, Nobuhisa, Kikuta, Hideaki",2
False-positive Histoplasma capsulatum Gen-Probe chemiluminescent test result caused by a Chrysosporium species.,0
We describe a case in which the Histoplasma capsulatum AccuProbe test displayed cross-reactivity with a respiratory isolate thought to be Histoplasma but not morphologically consistent with H. capsulatum. The isolate was later identified as the Chrysosporium anamorph of Nannizziopsis vriesii by sequence analysis and phenotypic data.,1
"Brandt, Mary E, Gaunt, Dennis, Iqbal, Naureen, McClinton, Shirley, Hambleton, Sarah, Sigler, Lynne",2
Identification of Mycobacterium species by secA1 sequences.,0
"We describe a novel molecular method for the differentiation and identification of 29 mycobacterial species. The target is the secA1 gene that codes for the essential protein SecA1, a key component of the major pathway of protein secretion across the cytoplasmic membrane. A 700-bp region of the secA1 gene was amplified and sequenced from 47 American Type Culture Collection strains of 29 Mycobacterium species as well as from 59 clinical isolates. Sequence variability in the amplified segment of the secA1 gene allowed the differentiation of all species except for the members of the Mycobacterium tuberculosis (MTB) complex, which had identical sequences. A range of 83.3 to 100% interspecies similarity was observed. All species could also be differentiated by their amino acid sequences as deduced from the sequenced region of the secA1 gene, with the exception of the MTB complex. Partial sequences of secA1 from clinical isolates belonging to nine frequently isolated species of mycobacteria revealed a very high intraspecies similarity at the DNA level (typically >99%; range, 96.0 to 100%); all clinical isolates were correctly identified. Comparison of the deduced 233-amino-acid sequences among clinical isolates of the same species showed between 99.6 and 100% similarity. To our knowledge, this is the first time a secretion-related gene has been used for the identification of the species within a bacterial genus.",1
"Zelazny, Adrian M, Calhoun, Leslie B, Li, Li, Shea, Yvonne R, Fischer, Steven H",2
"Trends in drug resistance, serotypes, and molecular types of Streptococcus pneumoniae colonizing preschool-age children attending day care centers in Lisbon, Portugal: a summary of 4 years of annual surveillance.",0
"Of the nasopharyngeal cultures recovered from 942 day care center (DCC) attendees in Lisbon, Portugal, 591 (62%) yielded Streptococcus pneumoniae during a surveillance performed in February and March of 1999. Forty percent of the isolates were resistant to one or more antimicrobial agents. In particular, 2% were penicillin resistant and 20% had intermediate penicillin resistance. Multidrug resistance to macrolides, lincosamides, and tetracycline was the most frequent antibiotype (17% of all isolates). Serotyping and molecular typing by pulsed-field gel electrophoresis were performed for 202 out of 237 drug-resistant pneumococci (DRPn). The most frequent serotypes were 6B (26%), 14 (22%), 19F (16%), 23F (10%), and nontypeable (12%). The majority (67%) of the DRPn strains were representatives of nine international clones included in the Pneumococcal Molecular Epidemiology Network; eight of them had been detected in previous studies. Fourteen novel clones were identified, corresponding to 26% of the DRPn strains. The remaining 7% of the strains were local clones detected in our previous studies. Comparison with studies conducted since 1996 in Portuguese DCCs identified several trends: (i) the rate of DRPn frequency has fluctuated between 40 and 50%; (ii) the serotypes most frequently recovered have remained the same; (iii) nontypeable strains appear to be increasing in frequency; and (iv) a clone of serotype 33F emerged in 1999. Together, our observations highlight that the nasopharynxes of children in DCCs are a melting pot of successful DRPn clones that are important to study and monitor if we aim to gain a better understanding on the epidemiology of this pathogen.",1
"Nunes, S, Sá-Leão, R, Carriço, J, Alves, C R, Mato, R, Avô, A Brito, Saldanha, J, Almeida, J S, Sanches, I Santos, de Lencastre, H",2
Diminished replicative fitness of primary human immunodeficiency virus type 1 isolates harboring the K65R mutation.,0
"The human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) resistance mutation K65R confers intermediate levels of resistance to several RT inhibitors, including a three- to fourfold reduction of tenofovir susceptibility. Here, we have used for the first time primary HIV-1 isolates from individuals who developed the K65R mutation while enrolled in a clinical trial of tenofovir to analyze the impact of this mutation on HIV-1 replicative fitness. A marked impairment in replicative fitness was observed in association with the selection of viruses carrying the K65R mutation in all patients. The mean replicative fitness among these viruses was 20% relative to the corresponding baseline wild-type virus, ranging from 10 to 32% depending on the accompanying RT mutations. These results support a reduction in in vivo replication for K65R mutant viruses.",1
"Weber, Jan, Chakraborty, Bikram, Weberova, Jitka, Miller, Michael D, Quiñones-Mateu, Miguel E",2
Infective endocarditis caused by Granulicatella elegans originating in the oral cavity.,0
"We studied the pheno- and genotypes of an oral Granulicatella elegans strain in comparison with those of a blood-derived isolate which caused infective endocarditis. The two isolates exhibited identical biochemical characteristics and had the same drug MICs. Their genotypes were indistinguishable, indicating that these were from the same clone. The transmission of G. elegans from the oral cavity thus should be noted as a possible cause of infective endocarditis.",1
"Ohara-Nemoto, Yuko, Kishi, Kayo, Satho, Mamoru, Tajika, Shihoko, Sasaki, Minoru, Namioka, Akiko, Kimura, Shigenobu",2
Dihydropteroate synthase and novel dihydrofolate reductase gene mutations in strains of Pneumocystis jirovecii from South Africa.,0
Dihydropteroate synthase (DHPS) gene mutations have raised concerns about emerging sulfonamide resistance in Pneumocystis jirovecii. DHPS and dihydrofolate reductase (DHFR) gene products were amplified in clinical specimens from South African patients. One of 53 DHPS genes sequenced contained the double mutation Thr55Ala Pro57Ser. DHFR gene mutations detected were Ala67Val and the new mutations Arg59Gly and C278T.,1
"Robberts, F J L, Chalkley, L J, Weyer, K, Goussard, P, Liebowitz, L D",2
Endophthalmitis caused by Enterococcus mundtii.,0
Enterococcus mundtii has rarely been isolated from environmental or human sources. We report the identification of E. mundtii as a pathogen of human infectious disease by DNA sequencing of 16S rRNA and sodA genes in a case of endophthalmitis developed in a 66-year-old immunocompetent gardener.,1
"Higashide, Tomomi, Takahashi, Mami, Kobayashi, Akira, Ohkubo, Shinji, Sakurai, Mayumi, Shirao, Yutaka, Tamura, Toshihiro, Sugiyama, Kazuhisa",2
"Evaluation of a point-of-care test, BVBlue, and clinical and laboratory criteria for diagnosis of bacterial vaginosis.",0
"Bacterial vaginosis (BV) remains the most common cause of abnormal vaginal discharge in women of reproductive age and is associated with increased susceptibility to human immunodeficiency virus and sexually transmitted infections and preterm delivery. Present diagnostic methods require access to microscopy and laboratory expertise; however, the majority of women, particularly those in populations with a high prevalence of BV, do not have access to clinical services with on-site microscopy capabilities. We evaluated a point-of-care test for the diagnosis of BV, the BVBlue test, with 288 women attending a sexual health service with symptoms of abnormal vaginal discharge and/or odor. The BVBlue test performed well compared with conventional diagnostic methods for the assessment of women with symptoms suggestive of BV at the bedside and significantly better than other simple tests, such as vaginal pH determination and the amine test, that do not require microscopy. The BVBlue test was sensitive (88%; 95% confidence interval [CI], 81 to 93%) and specific (95%; 95% CI, 91 to 98%) compared to the method of Nugent et al. (R. P. Nugent, M. A. Krohn, and S. L. Hillier, J. Clin. Microbiol. 29:297-301, 1991) and performed well compared with the method of Amsel et al. (R. Amsel, P. A. Totten, C. A. Spiegel, K. C. Chen, D. Eschenbach, and K. K. Holmes, Am. J. Med. 74:14-22, 1983), with a sensitivity of 88% (95% CI, 81 to 93%) and a specificity of 91% (95% CI, 85 to 94%). The BVBlue test is a simple, rapid, and objective test for the diagnosis of BV and has the potential to facilitate prompt diagnosis and appropriate treatment of BV in the absence of microscopy. The majority of women at the greatest risk for the sequelae of BV are not in settings where the conventional diagnostic methods are either practical or possible, and they would greatly benefit from access to rapid and reliable point-of-care tests to improve the diagnosis and management of BV.",1
"Bradshaw, C S, Morton, A N, Garland, S M, Horvath, L B, Kuzevska, I, Fairley, C K",2
First description of Curtobacterium spp. isolated from human clinical specimens.,0
"During a 4-year period, five strains (three of which were doubtless clinically significant) of yellow- or orange-pigmented, oxidative, slowly acid-producing coryneform bacteria were recovered from human clinical specimens in two reference laboratories or referred to them. The strains were motile, catalase positive, nitrate reductase negative, and urease negative, but strongly hydrolyzed esculin. In all reference and clinical strains described in the present study, anteisopentadecanoic (C(15:0ai)) and anteisoheptadecanoic (C(17:0ai)) acids represented more than 75% of all cellular fatty acids except in one clinical strain and in Curtobacterium pusillum, in which both the unusual omega-cyclohexyl fatty acid (identified as C(18:1omega7cis/omega9cis/omega12trans) by the Sherlock system) represented more than 50% of all cellular fatty acids. In all clinical strains, ornithine was the diamino acid of the cell wall, the interpeptide bridge consisted of ornithine, and acetyl was the acyl type of the peptidoglycan. Therefore, the five clinical strains were unambiguously identified as Curtobacterium spp. Analyses of the complete 16S rRNA genes of the five clinical strains with homologies to the established Curtobacterium species ranging from 99.2 to 100% confirmed the identifications as Curtobacterium spp. Data on the antimicrobial susceptibility pattern of curtobacteria are reported, with macrolides and rifampin showing very low MICs for all strains tested. This report is the first on the isolation of Curtobacterium strains from human clinical specimens.",1
"Funke, Guido, Aravena-Roman, Max, Frodl, Reinhard",2
The pls gene found in methicillin-resistant Staphylococcus aureus strains is common in clinical isolates of Staphylococcus sciuri.,0
"pls, a gene found in type I staphylococcal cassette chromosome mec (SCCmec) regions of methicillin-resistant Staphylococcus aureus strains, was present in 12 of the 15 human clinical Staphylococcus sciuri isolates studied. Pls was expressed in the S. sciuri isolates, although at a lower level than in S. aureus. Other parts of SCCmec could also be found in the S. sciuri genome.",1
"Juuti, Katri, Ibrahem, Salha, Virolainen-Julkunen, Anni, Vuopio-Varkila, Jaana, Kuusela, Pentti",2
Detection and genotyping of Mycobacterium species from clinical isolates and specimens by oligonucleotide array.,0
"Identification of pathogenic Mycobacterium species is important for a successful diagnosis of mycobacteriosis. The purpose of this study was to develop an oligonucleotide array which could detect and differentiate mycobacteria to the species level by using the internal transcribed spacer (ITS) sequence. Using a genus-specific probe and 20 species-specific probes including two M. avium-intracellulare complex (MAC)-specific probes, we have developed an ITS-based oligonucleotide array for the rapid and reliable detection and discrimination of M. tuberculosis, MAC, M. fortuitum, M. chelonae, M. abscessus, M. kansasii, M. gordonae, M. scrofulaceum, M. szulgai, M. vaccae, M. xenopi, M. terrae, M. flavescens, M. smegmatis, M. malmoense, M. simiae, M. marinum, M. ulcerans, M. gastri, and M. leprae. All mycobacteria were hybridized with a genus-specific probe (PAN-03) for detection of the genus Mycobacterium. Mycobacterial species were expected to show a unique hybridization pattern with species-specific probes, except for M. marinum and M. ulcerans, which were not differentiated by ITS-based probe. Among the species-specific probes, two kinds of species-specific probes were designed for MAC in which there were many subspecies. The performance of the oligonucleotide array assay was demonstrated by using 46 reference strains, 149 clinical isolates, and 155 clinical specimens. The complete procedure (DNA extraction, PCR, DNA hybridization, and scanning) was carried out in 4.5 h. Our results indicated that the oligonucleotide array is useful for the identification and discrimination of mycobacteria from clinical isolates and specimens in an ordinary clinical laboratory.",1
"Park, Heekyung, Jang, Hyunjung, Song, Eunsil, Chang, Chulhun L, Lee, Minki, Jeong, Seokhoon, Park, Junhyung, Kang, Byeongchul, Kim, Cheolmin",2
Clonal dissemination of macrolide-resistant and penicillin-susceptible serotype 3 and penicillin-resistant Taiwan 19F-14 and 23F-15 Streptococcus pneumoniae isolates in Japan: a pilot surveillance study.,0
"Large-scale surveillance studies using molecular techniques such as pulsed-field gel electrophoresis (PFGE) have revealed that the spread of antibiotic-resistant pneumococci is due to clonal spread. However, in Japan, surveillance studies using such molecular techniques have never been done. Therefore, we conducted a pilot surveillance study to elucidate the present situation in Japan. Among the 145 isolates examined, the most prevalent serotype was type 19F (20%), for which most isolates were not susceptible to penicillin (86.2%) but were positive for the mef(A)/mef(E) gene (89.7%). The secondmost prevalent was serotype 3 (16.6%), for which most isolates were susceptible to penicillin (87.5%) and positive for the erm(B) gene (91.7%). PFGE analysis showed that both serotypes consisted mainly of clonally identical or related isolates and, in particular, 38% of the type 19F isolates were indistinguishable from or closely related to the Taiwan 19F-14 clone. In addition, some of the Japanese type 23F isolates with the erm(B) gene were indistinguishable from or related to the Taiwan 23F-15 clone as analyzed by PFGE. Based on the results of our pilot study performed in a single institution, it is likely that international antibiotic-resistant clones have already spread in Japan; therefore, a nationwide surveillance study should be urgently conducted.",1
"Kasahara, Kei, Maeda, Koichi, Mikasa, Keiichi, Uno, Kenji, Takahashi, Ken, Konishi, Mitsuru, Yoshimoto, Eiichiro, Murakawa, Koichi, Kita, Eiji, Kimura, Hiroshi",2
Use of an electronic nose to diagnose Mycobacterium bovis infection in badgers and cattle.,0
"It is estimated that more than 50 million cattle are infected with Mycobacterium bovis worldwide, resulting in severe economic losses. Current diagnosis of tuberculosis (TB) in cattle relies on tuberculin skin testing, and when combined with the slaughter of test-positive animals, it has significantly reduced the incidence of bovine TB. The failure to eradicate bovine TB in Great Britain has been attributed in part to a reservoir of the infection in badgers (Meles meles). Accurate and reliable diagnosis of infection is the cornerstone of TB control. Bacteriological diagnosis has these characteristics, but only with samples collected postmortem. Unlike significant wild animal reservoirs of M. bovis that are considered pests in other countries, such as the brushtail possum (Trichosurus vulpecula) in New Zealand, the badger and its sett are protected under United Kingdom legislation (The Protection of Badgers Act 1992). Therefore, an accurate in vitro test for badgers is needed urgently to determine the extent of the reservoir of infection cheaply and without destroying badgers. For cattle, a rapid on-farm test to complement the existing tests (the skin test and gamma interferon assay) would be highly desirable. To this end, we have investigated the potential of an electronic nose (EN) to diagnose infection of cattle or badgers with M. bovis, using a serum sample. Samples were obtained from both experimentally infected badgers and cattle, as well as naturally infected badgers. Without exception, the EN was able to discriminate infected animals from controls as early as 3 weeks after infection with M. bovis, the earliest time point examined postchallenge. The EN approach described here is a straightforward alternative to conventional methods of TB diagnosis, and it offers considerable potential as a sensitive, rapid, and cost-effective means of diagnosing M. bovis infection in cattle and badgers.",1
"Fend, R, Geddes, R, Lesellier, S, Vordermeier, H-M, Corner, L A L, Gormley, E, Costello, E, Hewinson, R G, Marlin, D J, Woodman, A C, Chambers, M A",2
"The polypore mushroom Irpex lacteus, a new causative agent of fungal infections.",0
"Irpex lacteus, a wood-decaying basidiomycete, was isolated from a pulmonary abscess of an immunosuppressed child. This medical strain was compared morphologically and by sequencing of the ribosomal intergenic spacers with specimens from both culture collections and herbarium desiccated material. The patient was treated successfully with amphotericin B.",1
"Buzina, Walter, Lass-Flörl, Cornelia, Kropshofer, Gabriele, Freund, Martin C, Marth, Egon",2
European multicenter study of the LIAISON automated diagnostic system for determination of Toxoplasma gondii-specific immunoglobulin G (IgG) and IgM and the IgG avidity index.,0
"The LIAISON system is a fully automated system based on chemiluminescence and antigen bound to magnetic microparticles. The system allows fast and precise measurement of Toxoplasma-specific immunoglobulin G (IgG) and IgM antibody levels and measurement of the IgG avidity index even at low levels of Toxoplasma-specific IgG antibodies in a single step without manual interference. Seven European centers participated in a multicenter evaluation of the LIAISON system. The sensitivity and specificity of the LIAISON system compared to the Sabin-Feldman dye test were 99.3 and 96.8%, respectively. In a comparison of the LIAISON Toxoplasma-specific IgM assay with an immunosorbent agglutination assay, the LIAISON assay had a sensitivity of 96.7% and a specificity of 95.4%. The LIAISON IgG assay showed agreements of 91, 100, and 100% with the AXSYM IgG (Abbott), VIDAS IgG (bioMerieux), and Platelia IgG (Bio-Rad) assays, respectively. The LIAISON IgM assay showed agreements of 95% with the AXSYM IgM and Platelia IgM assays, 96% with the ISAGA IgM assay (bioMerieux), and 97% with the VIDAS IgM assay. The coefficient of correlation between the LIAISON system and the VIDAS Toxoplasma-specific IgG avidity index was 0.81. By use of the Toxoplasma-specific IgG avidity index assay with specific IgM-positive samples, the diagnosis of infection with Toxoplasma gondii in early pregnancy has been improved significantly. The LIAISON avidity assay is a valuable assay for the exclusion of recently acquired infection with T. gondii (less than 4 months) in pregnant women, and it decreases significantly the necessity for follow-up testing.",1
"Petersen, Eskild, Borobio, Maria Victoria, Guy, Edward, Liesenfeld, Oliver, Meroni, Valeria, Naessens, Anne, Spranzi, Emma, Thulliez, Philippe",2
Use of variable-number tandem repeats to examine genetic diversity of Neisseria meningitidis.,0
"Repetitive DNA motifs with potential variable-number tandem repeats (VNTR) were identified in the genome of Neisseria meningitidis and used to develop a typing method. A total of 146 meningococcal isolates recovered from carriers and patients were studied. These included 82 of the 107 N. meningitidis isolates previously used in the development of multilocus sequence typing (MLST), 45 isolates recovered from different counties in Norway in connection with local outbreaks, and 19 serogroup W135 isolates of sequence type 11 (ST-11), which were recovered in several parts of the world. The latter group comprised isolates related to the Hajj outbreak of 2000 and isolates recovered from outbreaks in Burkina Faso in 2001 and 2002. All isolates had been characterized previously by MLST or multilocus enzyme electrophoresis (MLEE). VNTR analysis showed that meningococcal isolates with similar MLST or MLEE types recovered from epidemiologically linked cases in a defined geographical area often presented similar VNTR patterns while isolates of the same MLST or MLEE types without an obvious epidemiological link showed variable VNTR patterns. Thus, VNTR analysis may be used for fine typing of meningococcal isolates after MLST or MLEE typing. The method might be especially valuable for differentiating among ST-11 strains, as shown by the VNTR analyses of serogroup W135 ST-11 meningococcal isolates recovered since the mid-1990s.",1
"Yazdankhah, Siamak P, Lindstedt, Bjørn-Arne, Caugant, Dominique A",2
Detection of human metapneumovirus in clinical samples by immunofluorescence staining of shell vial centrifugation cultures prepared from three different cell lines.,0
"Monoclonal antibody MAb-8 was evaluated for detection of human metapneumovirus (HMPV) in shell vial centrifugation cultures (SVCC). Detection of HMPV was similar in A549, HEp-2, and LLC-MK2 SVCC, and MAb-8 staining was optimal on day 2 postinoculation. Availability of SVCC for HMPV will be of significant benefit to clinical laboratories.",1
"Landry, Marie L, Ferguson, David, Cohen, Sandra, Peret, Teresa C T, Erdman, Dean D",2
Clinical manifestations of staphylococcal scalded-skin syndrome depend on serotypes of exfoliative toxins.,0
"We sought a possible correlation between the clinical manifestations of staphylococcal scalded-skin syndrome (SSSS) and the serotype of exfoliative toxins (ET) by PCR screening of the eta and etb genes in Staphylococcus aureus strains isolated from 103 patients with generalized SSSS and 95 patients with bullous impetigo. The eta gene and the etb gene were detected in, respectively, 31 (30%) and 20 (19%) episodes of generalized SSSS and 57 (60%) and 5 (5%) episodes of bullous impetigo. Both genes were detected in 52 (50%) episodes of generalized SSS and 33 (35%) episodes of bullous impetigo. To explain this link between etb and generalized SSSS, we examined the distribution of ETA- and ETB-specific antibodies in the healthy population (n = 175) and found that the anti-ETB antibody titer was lower than the anti-ETA titer. Thus, ETA is associated with bullous impetigo and ETB is associated with generalized SSSS, possibly owing to a lower titer of anti-ETB neutralizing antibodies in the general population.",1
"Yamasaki, Osamu, Yamaguchi, Takayuki, Sugai, Motoyuki, Chapuis-Cellier, Colette, Arnaud, François, Vandenesch, François, Etienne, Jerome, Lina, Gerard",2
CHROMagar Candida medium for direct susceptibility testing of yeast from blood cultures.,0
"An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-microg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 microg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more susceptible than the reference MIC interpretation. In summary, subculturing yeast directly from blood cultures onto CHROMagar to which a fluconazole disk has been added may provide a presumptive identification at 24 h and, with the exception of C. glabrata, was able to predict the susceptibility to fluconazole with the majority of Candida isolates examined in this evaluation.",1
"Tan, Grace L, Peterson, Ellena M",2
Rapid diagnostic method for detection of mumps virus genome by loop-mediated isothermal amplification.,0
"Most mumps patients are clinically diagnosed without any virological examinations, but some diagnosed cases of mumps may be caused by other pathogens or secondary vaccine failure (SVF). To clarify these issues, a sensitive, specific, and rapid diagnostic method is required. We obtained 60 salivary swabs from 34 patients with natural infection during the course of the illness, 10 samples from patients with vaccine-associated parotitis, and 5 samples from patients with SVF. Total RNA was extracted and subjected to reverse transcription-PCR (RT-PCR) and loop-mediated isothermal amplification (LAMP) for genome amplification. We detected mumps virus RNA corresponding to 0.1 PFU by LAMP within 60 min after RNA extraction, with the same sensitivity as RT-nested PCR. Mumps virus was isolated in 30 of 33 samples within day 2, and mumps virus genome was amplified by LAMP in 32 of them. The quantity of virus titer was calculated by monitoring the time to reach the threshold of turbidity. The viral load decreased after day 3 and was lower in patients serologically diagnosed as having SVF with milder illness. Accuracy of LAMP for the detection of mumps virus genome was confirmed; furthermore, it is of benefit for calculating the viral load, which reflects disease pathogenesis.",1
"Okafuji, Takao, Yoshida, Naoko, Fujino, Motoko, Motegi, Yoshie, Ihara, Toshiaki, Ota, Yoshinori, Notomi, Tsugunori, Nakayama, Tetsuo",2
Molecular identification of Capnocytophaga spp. via 16S rRNA PCR-restriction fragment length polymorphism analysis.,0
"Capnocytophaga spp. have been implicated as putative periodontal pathogens associated with various periodontal diseases. Although the genus is known to contain five human oral isolates, accurate identification to species level of these organisms recovered from subgingival plaque has been hampered by the lack of a reliable method. Hence, most studies to date have reported these isolates as Capnocytophaga spp. Previous attempts at identification were based on biochemical tests; however, the results were inconclusive. Considering the differing virulence features of the respective isolates, it is crucial to identify these isolates to species level. The universal and conservative nature of the 16S rRNA gene has provided an accurate method for bacterial identification. The aim of this study was to identify Capnocytophaga spp. via restriction enzyme analysis of this gene (16S rRNA PCR-restriction fragment length polymorphism). The results (backed up by 16S rRNA gene sequencing) showed that this method reliably identifies all named Capnocytophaga spp. to species level.",1
"Ciantar, Marilou, Newman, Hubert N, Wilson, Michael, Spratt, David A",2
Development and application of a Saccharomyces cerevisiae-expressed nucleocapsid protein-based enzyme-linked immunosorbent assay for detection of antibodies against infectious bronchitis virus.,0
"A Saccharomyces cerevisiae-expressed nucleocapsid (N) polypeptide of the M41 strain of infectious bronchitis virus (IBV) was used as antigen in a recombinant yeast-expressed N protein-based enzyme-linked immunosorbent assay (Y-N-ELISA). The Y-N-ELISA was rapid, sensitive, and specific for detecting chicken serum antibodies to IBV, and it compared favorably with a commercial ELISA.",1
"Gibertoni, Aliandra M, Montassier, Maria de Fátima S, Sena, Janete A D, Givisiez, Patrícia E N, Furuyama, Cibele R A G, Montassier, Hélio J",2
Fusarium verticillioides abscess of the nasal septum in an immunosuppressed child: case report and identification of the morphologically atypical fungal strain.,0
"Morphologically atypical Fusarium verticillioides causing a nasal abscess in a severely immunosuppressed child was successfully treated with repeated surgical intervention and liposomal amphotericin B, despite amphotericin B resistance in vitro. Definitive identification was achieved by sequencing the translation elongation factor alpha gene after ribosomal sequencing proved inadequate.",1
"Dornbusch, Hans Jürgen, Buzina, Walter, Summerbell, Richard C, Lass-Flörl, Cornelia, Lackner, Herwig, Schwinger, Wolfgang, Sovinz, Petra, Urban, Christian",2
Reemergence of emm1 and a changed superantigen profile for group A streptococci causing invasive infections: results from a nationwide study.,0
"Between 1999 and 2002, 496 invasive group A streptococcal (GAS) isolates from clinical microbiological departments in Denmark and subsequently 487 (98%) questionnaires from the clinicians treating the patients were received as part of a national surveillance. emm types and streptococcal superantigen (SAg) genes were determined. The incidence of invasive GAS infections was on average 2.3 per 100,000 per year. Bacteremia with no focal symptoms (27%) was together with erysipelas (20%) the most prevalent clinical diagnoses. Streptococcal toxic shock syndrome occurred in 10% of patients, of which 56% died. The overall case fatality rate within 30 days was 23%. In total, 47 different emm types were identified, of which emm1, emm3, emm4, emm12, emm28, and emm89 were identified in 72% of the 493 available isolates. During the 4-year period the presence of emm1 increased from 16% in 1999 to 40% in 2002. Concurrently, the presence of emm3 decreased from 23% in 1999 to 2% in 2002. The emm1 isolates predominantly carried speA, although the frequency decreased from 94% in 1999 to 71% in 2002, whereas the emm1-specific prevalence of speC increased from 25 to 53%. In a historical perspective, this could be interpreted as a reemergence of emm1 and could indicate a possible introduction of a new emm1 subclone. However, this reemergence did not result in any significant changes in the clinical manifestations during the study period. Our results show the complexity of invasive GAS infections, with time-dependent variations in the incidence and distribution of emm and SAg genes, which emphasizes the need for continuous epidemiological and molecular investigations.",1
"Ekelund, Kim, Skinhøj, Peter, Madsen, Jesper, Konradsen, Helle Bossen",2
Internally controlled real-time PCR monitoring of adenovirus DNA load in serum or plasma of transplant recipients.,0
"Adenoviruses have been recognized as important pathogens in immunocompromised hosts. Particularly in pediatric allogeneic stem cell transplant recipients, the morbidity of the patients and mortality in those patients with disseminated infections have been found to increase over the last few years. Severe infections are predominantly but not exclusively caused by subgroup C adenoviruses. A multiplex real-time PCR assay using molecular beacons as probes was developed to enable monitoring of adenovirus DNA in those patients with simultaneous identification of subgroups. An internal control was coamplified in the multiplex PCR to check for the DNA isolation procedure as well as the presence of inhibitors in the clinical samples. The assay has been applied retrospectively in patient groups with different clinical outcomes of infection. In fatal cases, significantly higher adenovirus loads developed, exceeding even 10(11) copies/ml of serum or plasma. Patients with viral loads over 10(6) copies/ml appear to have an increased risk for fatal complications. This quantitative real-time PCR assay has been prospectively used clinically since 2002 to study the course of adenovirus infection. In addition, the assay provides objective start and end points of therapeutic interventions, including the clinically important evaluation of antiviral drugs.",1
"Claas, Eric C J, Schilham, Marco W, de Brouwer, Caroline S, Hubacek, Petr, Echavarria, Marcela, Lankester, Arjan C, van Tol, Maarten J D, Kroes, Aloys C M",2
First report of infection with community-acquired methicillin-resistant Staphylococcus aureus in South America.,0
"Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has recently emerged in the southwestern Pacific, North America, and Europe. These S. aureus isolates frequently shared some genetic characteristics, including the SCCmec type IV and lukS-lukF genes. In this paper we show that typical CA-MRSA isolates have spread to South America (Brazil).",1
"Ribeiro, Apoena, Dias, Cícero, Silva-Carvalho, Maria Cícera, Berquó, Laura, Ferreira, Fabienne Antunes, Santos, Raquel Neves Soares, Ferreira-Carvalho, Bernadete Teixeira, Figueiredo, Agnes Marie",2
Dynamic range of hepatitis C virus RNA quantification with the Cobas Ampliprep-Cobas Amplicor HCV Monitor v2.0 assay.,0
"Accurate quantification of hepatitis C virus (HCV) RNA is needed in clinical practice to decide whether to continue or stop pegylated interferon-alpha-ribavirin combination therapy at week 12 of treatment for patients with chronic hepatitis C. Currently the HCV RNA quantification assay most widely used worldwide is the Amplicor HCV Monitor v2.0 assay (Roche Molecular Systems, Pleasanton, Calif.). The HCV RNA extraction step can be automated in the Cobas Ampliprep device. In this work, we show that the dynamic range of HCV RNA quantification of the Cobas Ampliprep/Cobas Amplicor HCV Monitor v2.0 procedure is 600 to 200,000 HCV RNA IU/ml (2.8 to 5.3 log IU/ml), which does not cover the full range of HCV RNA levels in infected patients. Any sample containing more than 200,000 IU/ml (5.3 log IU/ml) must thus be retested after dilution for accurate quantification. These results emphasize the need for commercial HCV RNA quantification assays with a broader range of linear quantification, such as real-time PCR-based assays.",1
"Gourlain, Karine, Soulier, Alexandre, Pellegrin, Bertrand, Bouvier-Alias, Magali, Hézode, Christophe, Darthuy, Françoise, Rémiré, Jocelyne, Pawlotsky, Jean-Michel",2
Susceptibilities of Mycobacterium tuberculosis to isoniazid and rifampin on blood agar.,0
"In this study, blood agar was used instead of 7H10 agar for the susceptibility testing of 34 clinical isolates of Mycobacterium tuberculosis to isoniazid (INH) and rifampin (RIF) in accordance with the NCCLS. The BACTEC 460 TB system (Becton Dickinson, Sparks, Md.) was used as a ""gold standard."" Results for both media were in agreement for RIF and INH at 100 and 94.1%, respectively. For INH, the specificity, sensitivity, positive predictive value, and negative predictive value were found to be 71.4, 100, 93.1, and 100%, respectively, while these values were 100% for RIF. In addition, the results of the susceptibility test performed with blood agar were obtained on day 14 of incubation. In conclusion, results were obtained much earlier with blood agar (2 weeks) than with 7H10 agar (3 weeks), and the results of this study suggest that blood agar may be used as an alternative medium for the susceptibility testing of M. tuberculosis to INH and RIF.",1
"Coban, Ahmet Yilmaz, Bilgin, Kemal, Uzun, Meltem, Tasdelen Fisgin, Nuriye, Akgunes, Alper, Cihan, Cigdem Cekic, Birinci, Asuman, Durupinar, Belma",2
Invasive infections caused by Trichosporon species and Geotrichum capitatum in patients with hematological malignancies: a retrospective multicenter study from Italy and review of the literature.,0
"Trichosporonosis is an uncommon but frequently fatal mycosis in immunocompromised patients. A multicenter retrospective study was conducted to characterize cases of proven or probable invasive trichosporonosis diagnosed over the past 20 years in Italian patients with hematological diseases. Of the 52 cases identified, 17 were classified as Trichosporon sp. infections and 35 were attributed to Geotrichum capitatum. Acute myeloid leukemia accounted for 65.4% of the cases. The incidence rates of Trichosporon sp. and G. capitatum infections in acute leukemia patients were 0.4 and 0.5%, respectively. Overall, 76.9% of cases had positive blood cultures. Pulmonary involvement was documented in 26.9% of cases. Death was reported for 57.1% of G. capitatum infections and for 64.7% of Trichosporon sp. infections. A literature review on trichosporonosis in patients with any underlying disease or condition reveals G. capitatum as a predominantly European pathogen, particularly in certain Mediterranean areas, while Trichosporon sp. infections are seen with similar frequencies on all continents. The majority of published Trichosporon sp. and G. capitatum infections occurred in patients with hematological diseases (62.8 and 91.7%, respectively). Well over half of these were suffering from acute leukemia (68 and 84% of patients with Trichosporon sp. and G. capitatum infections, respectively). Crude mortality rates were 77% for Trichosporon spp. and 55.7% for G. capitatum. The optimal therapy for trichosporonosis has yet to be identified; however, in vitro experiences are providing encouraging evidence of the potential role of the new triazoles, in particular, voriconazole.",1
"Girmenia, Corrado, Pagano, Livio, Martino, Bruno, D'Antonio, Domenico, Fanci, Rosa, Specchia, Giorgina, Melillo, Lorella, Buelli, Massimo, Pizzarelli, Giampaolo, Venditti, Mario, Martino, Pietro",2
env Gene typing of human immunodeficiency virus type 1 strains on electronic microarrays.,0
"The NanoChip system was used for subtyping human immunodeficiency virus type 1 (HIV-1) strains using probes complementary to the V1 region of the env gene. Probes for six subtypes (A to D, F, and G) and two circulating recombinant forms (AG and AE) of HIV-1 group M were included. The specificity of these oligonucleotides had been evaluated previously in a DNA enzyme immunoassay. Samples from 112 patient sera were used as templates in a nested reverse transcription-PCR to produce amplicons that were applied to the array. The array was then hybridized successively to pairs of oligonucleotide probes. The strains were assigned a subtype on the basis of their probe hybridization patterns. One strain gave a contradictory pattern and was designated as untypeable by the NanoChip assay. Eighty-eight strains gave hybridization patterns that allowed a correct subtype designation to be made by the NanoChip assay compared to either the sequence or the heteroduplex mobility assay (HMA)-determined subtypes. Thirteen strains that reacted with the subtype A probe (SA2) were incorrectly assigned to subtype A, or to one of the related circulating recombinant types (AE or AG), on the basis of reactions with probe SAE1 or SAG1. The results indicate that these oligonucleotides have relatively low specificities. The probe subtypes of three strains matched the subtypes determined for the gag and pol genes but not the env gene, suggesting that a recombination event may have occurred within the env gene. Overall, the NanoChip assay gave results comparable to those for HMA and sequencing and provides a convenient and cost-effective means by which to subtype HIV-1.",1
"Saunders, N A, Alexander, S, Tatt, I",2
Comparison between rpoB and 16S rRNA gene sequencing for molecular identification of 168 clinical isolates of Corynebacterium.,0
"Higher proportions (91%) of 168 corynebacterial isolates were positively identified by partial rpoB gene determination than by that based on 16S rRNA gene sequences. This method is thus a simple, molecular-analysis-based method for identification of corynebacteria, but it should be used in conjunction with other tests for definitive identification.",1
"Khamis, Atieh, Raoult, Didier, La Scola, Bernard",2
Latex agglutination test for monitoring antibodies to avian influenza virus subtype H5N1.,0
"A latex agglutination test (LAT) based on polystyrene beads sensitized with inactivated avian influenza virus H5N1 particles was developed. Compared with the hemagglutination inhibition test, the sensitivity and specificity of the LAT were 88.8 and 97.6%, respectively, in detecting 830 serum samples from vaccinated chickens. The test has application potential in field practice.",1
"Xu, Xiaojuan, Jin, Meilin, Yu, Zhengjun, Li, Hongchao, Qiu, Dexin, Tan, Yadi, Chen, Huanchun",2
Species-level identification of isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex by sequence analysis of the 16S-23S rRNA gene spacer region.,0
"The species Acinetobacter calcoaceticus, A. baumannii, genomic species 3, and genomic species 13TU included in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex are genetically highly related and difficult to distinguish phenotypically. Except for A. calcoaceticus, they are all important nosocomial species. In the present study, the usefulness of the 16S-23S rRNA gene intergenic spacer (ITS) sequence for the differentiation of (genomic) species in the A. calcoaceticus-A. baumannii complex was evaluated. The ITSs of 11 reference strains of the complex and 17 strains of other (genomic) species of Acinetobacter were sequenced. The ITS lengths (607 to 638 bp) and sequences were highly conserved for strains within the A. calcoaceticus-A. baumannii complex. Intraspecies ITS sequence similarities ranged from 0.99 to 1.0, whereas interspecies similarities varied from 0.86 to 0.92. By using these criteria, 79 clinical isolates identified as A. calcoaceticus (18 isolates) or A. baumannii (61 isolates) with the API 20 NE system (bioMerieux Vitek, Marcy l'Etoile, France) were identified as A. baumannii (46 isolates), genomic species 3 (19 isolates), and genomic species 13TU (11 isolates) by ITS sequencing. An identification rate of 96.2% (76 of 79 isolates) was obtained by using ITS sequence analysis for identification of isolates in the A. calcoaceticus-A. baumannii complex, and the accuracy of the method was confirmed for a subset of strains by amplified rRNA gene restriction analysis and genomic DNA analysis by AFLP analysis by using libraries of profiles of reference strains. In conclusion, ITS sequence-based identification is reliable and provides a promising tool for elucidation of the clinical significance of the different species of the A. calcoaceticus-A. baumannii complex.",1
"Chang, Hsien Chang, Wei, Yu Fang, Dijkshoorn, Lenie, Vaneechoutte, Mario, Tang, Chung Tao, Chang, Tsung Chain",2
Improvement of the specificity of an enzyme-linked immunosorbent assay for diagnosis of paracoccidioidomycosis.,0
"In an attempt to improve the specificity of an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of paracoccidioidomycosis (PCM), sera from patients with PCM were tested using various approaches, such as sodium metaperiodate antigen (gp43) treatment, a serum absorption process with Candida albicans or Histoplasma capsulatum antigens, and dilution of serum in galactose, the main common epitope among pathogenic fungi. The maximum specificity found in this ELISA was 84%. All of these procedures proved inefficient for eliminating all cross-reacting antibodies and obtaining an ELISA specific for PCM diagnosis.",1
"Albuquerque, C F, da Silva, S H Marques, Camargo, Z P",2
Clonal spread of a vancomycin-resistant Enterococcus faecium strain among bloodstream-infecting isolates in Italy.,0
"Recent data indicated that the rate of vancomycin resistance in bloodstream-infecting enterococcal isolates in Italy is one of the highest in Europe. The aims of this study were to characterize bloodstream-infecting vancomycin-resistant enterococci (VRE) obtained from various Italian hospitals and to establish whether the isolates were clonally related. During the years 2001 to 2003, a total of 39 VRE isolates were obtained from 19 hospital laboratories in various areas of Italy. Species identification and resistance genotypes of the isolates were obtained by multiplex PCR. Further characterization included antibiotic susceptibility testing, pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, detection of virulence genes (esp and hyl), and multilocus sequence typing (MLST) of selected isolates. VRE were identified as 31 Enterococcus faecium (VREfm) isolates and 8 E. faecalis isolates. All but one isolate carried the vanA gene; one VREfm isolate carried the vanB gene. Analysis of the PFGE profiles showed that 28 VREfm isolates shared a similar electrophoretic profile, designed type 1, and were clonally related. All type 1 isolates were resistant to ampicillin, streptomycin, gentamicin, and rifampin and were positive for the esp gene. MLST identified an allelic profile (ST78) comprising purK allele 1, belonging to the C1 clonal lineage, characteristic of human infection and hospital outbreak isolates. The vanB-carrying VREfm isolate, of PFGE type 2, was shown to be a single-locus variant of ST78. Our data indicate that the recent increase in the number of bloodstream infections caused by VRE in Italy is due to the spread of a hospital-adapted, multidrug-resistant VREfm clone belonging to an internationally disseminated lineage.",1
"Stampone, Lucia, Del Grosso, Maria, Boccia, Delia, Pantosti, Annalisa",2
Efficient discrimination within a Corynebacterium diphtheriae epidemic clonal group by a novel macroarray-based method.,0
"A large diphtheria epidemic in the 1990s in Russia and neighboring countries was caused by a clonal group of closely related Corynebacterium diphtheriae strains (ribotypes Sankt-Peterburg and Rossija). In the recently published complete genome sequence of C. diphtheriae strain NCTC13129, representative of the epidemic clone (A. M. Cerdeno-Tarraga et al., Nucleic Acids Res. 31:6516-6523, 2003), we identified in silico two direct repeat (DR) loci 39 kb downstream and 180 kb upstream of the oriC region, consisting of minisatellite (27- to 36-bp) alternating DRs and variable spacers. We designated these loci DRA and DRB, respectively. A reverse-hybridization macroarray-based method has been developed to study polymorphism (the presence or absence of 21 different spacers) in the larger DRB locus. We name it spoligotyping (spacer oligonucleotide typing), analogously to a similar method of Mycobacterium tuberculosis genotyping. The method was evaluated with 154 clinical strains of the C. diphtheriae epidemic clone from the St. Petersburg area in Russia from 1997 to 2002. By comparison with the international ribotype database (Institut Pasteur, Paris, France), these strains were previously identified as belonging to ribotypes Sankt-Peterburg (n = 79) and Rossija (n = 75). The 154 strains were subdivided into 34 spoligotypes: 14 unique strains and 20 types shared by 2 to 46 strains; the Hunter Gaston discriminatory index (HGDI) was 0.85. DRB locus-based spoligotyping allows fast and efficient discrimination within the C. diphtheriae epidemic clonal group and is applicable to both epidemiological investigations and phylogenetic reconstruction. The results are easy to interpret and can be presented and stored in a user-friendly digital database (Excel file), allowing rapid type determination of new strains.",1
"Mokrousov, Igor, Narvskaya, Olga, Limeschenko, Elena, Vyazovaya, Anna",2
Rapid detection of ofloxacin resistance in Mycobacterium tuberculosis by two low-cost colorimetric methods: resazurin and nitrate reductase assays.,0
"We have evaluated the performance of two rapid, low-cost methods for the detection of ofloxacin (OFX) resistance with 95 Mycobacterium tuberculosis isolates from countries with high multidrug-resistant tuberculosis endemicity. Results obtained by nitrate reductase and resazurin assays showed 100% agreement with those of the proportion method on 7H11 agar using 2 mug of OFX/ml. We confirmed the resistance of all isolates found to be resistant to OFX by the Mycobacterium Growth Indicator Tube system, and complete agreement among all methods was observed. Nitrate reductase and resazurin assays are rapid, simple, low-cost methods and might become inexpensive alternative procedures for rapid detection of OFX resistance in low-resource countries.",1
"Martin, Anandi, Palomino, Juan Carlos, Portaels, Françoise",2
Chryseobacterium indologenes non-catheter-related bacteremia in a patient with a solid tumor.,0
A case of non-catheter-related bacteremia caused by Chryseobacterium indologenes in a nonneutropenic man with a solid tumor is described. The patient was successfully treated with piperacillin-tazobactam.,1
"Christakis, George B, Perlorentzou, Stavroula P, Chalkiopoulou, Irene, Athanasiou, Athanasios, Legakis, Nikolas J",2
Evaluation and updating of the Osiris expert system for identification of Escherichia coli beta-lactam resistance phenotypes.,0
"Osiris is a video zone size reader for disk diffusion tests that includes a built-in extended expert system (EES). We evaluated the efficacy of the Osiris EES for the identification of beta-lactam susceptibility phenotypes of Escherichia coli isolates. Fifteen beta-lactam agents and three beta-lactam-beta-lactamase inhibitor combinations were tested by the disk diffusion method against 50 E. coli strains with well-characterized resistance mechanisms. The strains were screened for the production of extended-spectrum beta-lactamase (ESBL) by the double-disk synergy test using a disk of amoxicillin-clavulanic acid with disks of the extended-spectrum cephalosporins and aztreonam. Overall, the EES accurately identified the phenotype for 78% of the strains, indicated an inexact phenotype for 17% of the strains, and could not find a matching phenotype for the remaining 5% of the strains. The percentage of correct identification for each resistance mechanism was 100% for inhibitor-resistant TEM and for TEM plus cephalosporinase, 88.9% for TEM and for ESBL, 70.8% for cephalosporinase overproduction, and 25% for oxacillinase. The main cause of discrepancy was the misidentification of oxacillinase as inhibitor-resistant TEM. The conventional double-disk synergy test failed to detect ESBL production in two strains (one producing VEB-1 and one producing CTX-M-14), but synergy between cefepime and amoxicillin-clavulanic acid was visible after the distance between the disks was reduced to 20 mm. After the interpretative guidelines of the EES were updated according to our results, the percentage of correct phenotype identification increased from 78 to 96%.",1
"Bert, Frédéric, Juvin, Manette, Ould-Hocine, Zahia, Clarebout, Gervais, Keller, Emmanuelle, Lambert, Nicole, Arlet, Guillaume",2
Evaluation of two chromogenic agar media for recovery and identification of Staphylococcus aureus small-colony variants.,0
"To identify the most rapid and reliable technique for recovery and identification of Staphylococcus aureus small-colony variants (SCVs), the colonial appearance of 106 isolates representing SCVs and the normal phenotype were evaluated on two newly described chromogenic agar media. Although almost all of the SCVs grew on the chromogenic agar media, they did not exhibit a change of color. In comparison with conventional media, S. aureus ID agar (SAID; bioMerieux, La Balme Les Grottes, France) showed the most reliable results, with 49 of 53 SCVs tested growing either as an SCV colony or with a normal phenotype after only 24 h of incubation. Growth of SCVs was often not detected before 72 h of incubation on some of the media tested. In conclusion, the most accurate and rapid method to detect both the species S. aureus and the SCV phenotype is to inoculate specimens onto both Columbia blood agar and SAID.",1
"Kipp, Frank, Kahl, Barbara C, Becker, Karsten, Baron, Ellen J, Proctor, Richard A, Peters, Georg, von Eiff, Christof",2
Use of specific rRNA oligonucleotide probes for microscopic detection of Mycobacterium avium complex organisms in tissue.,0
"Members of the Mycobacterium avium complex (MAC) are important environmental pathogens that are implicated in several chronic, idiopathic diseases. Diagnosis of MAC-based diseases is compromised by the need to cultivate these fastidious and slowly growing organisms in order to identify which mycobacterial species are present. Detection is particularly difficult when MAC is intracellular or embedded within mammalian tissues. We report on the development of culture-independent, in situ hybridization (ISH) assays for the detection of MAC in culture, sputum, and tissue. This assay includes a highly reliable technique for the permeabilization of mycobacterial cells within culture and tissues. We describe a set of rRNA-based oligonucleotide probes that specifically detect either M. intracellulare, the two M. avium subspecies associated with human disease, or all members of MAC. The results call into question the validity of ISH results derived by the use of other gene loci, such as IS900.",1
"St Amand, Allison L, Frank, Daniel N, De Groote, Mary Ann, Pace, Norman R",2
Use of single nucleotide polymorphisms in the plcR gene for specific identification of Bacillus anthracis.,0
"A TaqMan-minor groove binding assay designed around a nonsense mutation in the plcR gene was used to genotype Bacillus anthracis, B. cereus, and B. thuringiensis isolates. The assay differentiated B. anthracis from these genetic near-neighbors and determined that the nonsense mutation is ubiquitous across 89 globally and genetically diverse B. anthracis strains.",1
"Easterday, W Ryan, Van Ert, Matthew N, Simonson, Tatum S, Wagner, David M, Kenefic, Leo J, Allender, Christopher J, Keim, Paul",2
Testing for induction of clindamycin resistance in erythromycin-resistant isolates of Staphylococcus aureus.,0
"Disk diffusion and broth microdilution (BMD) were used to perform clindamycin (CLI) induction testing on 128 selected nonduplicate isolates of Staphylococcus aureus. Disk diffusion testing involved placing CLI and erythromycin (ERY) disks approximately 12 mm apart (measured edge to edge) on a Mueller-Hinton agar plate that had been inoculated with an S. aureus isolate; the plate was then incubated for 16 to 18 h. Two distinct induction phenotypes (labeled D and D(+)) and four noninduction phenotypes (designated as negative [Neg], hazy D zone [HD], resistant [R], and susceptible [S]) were observed in disk diffusion results. A clear, D-shaped zone of inhibition around the CLI disk was designated as the D phenotype and was observed for 21 isolates while a D-shaped zone containing inner colonies growing up to the CLI disk was designated as D(+) (17 isolates). In addition, 10 isolates were CLI susceptible and ERY resistant but were not inducible and showed no blunting of the CLI zone (Neg phenotype). Isolates that were CLI and ERY resistant (constitutive macrolide-lincosamide-streptogramin B resistance) demonstrated either a double zone of inhibition with an inner ring of reduced growth up to the edge of the disks (HD phenotype; 33 isolates) or solid growth around the CLI and ERY disks (R phenotype; 16 isolates). Finally, 31 isolates were susceptible by disk testing to both CLI and ERY (S phenotype). PCR results showed that isolates with a D phenotype harbored ermA, isolates with a D(+) phenotype contained either ermC (16 isolates) or ermA and ermC (one isolate), and all 10 isolates with a Neg phenotype contained msrA. All isolates with an HD or R phenotype harbored at least one erm gene. Isolates showing the D(+) phenotype by disk diffusion were also detected by BMD using a variety of CLI and ERY concentrations; however, isolates with the D phenotype were more difficult to detect by BMD and will likely require optimization of ERY and CLI concentrations in multilaboratory studies to ensure adequate sensitivity. Thus, at present, disk diffusion is the preferred method for testing S. aureus isolates for inducible CLI resistance.",1
"Steward, Christine D, Raney, Patti M, Morrell, Allison K, Williams, Portia P, McDougal, Linda K, Jevitt, Laura, McGowan, John E, Tenover, Fred C",2
Use of quantitative real-time PCR to monitor the response of Chlamydophila felis infection to doxycycline treatment.,0
"Fifteen cats infected with Chlamydophila felis were monitored for the presence of C. felis DNA on ocular swabs by using real-time PCR and for clinical signs of disease. The cats were assigned to three groups: oral doxycycline at 10 mg/kg of body weight/day for 7 days (six cats), oral doxycycline at 10 mg/kg/day for 14 days (five cats), and an untreated control group (four cats). The untreated cats remained positive for C. felis throughout the trial; clinical signs were most severe on days 14 to 21 postinfection, and then they declined. Treatment with 7 and 14 days of doxycycline decreased C. felis relative copy numbers and clinical signs rapidly. C. felis became undetectable in some of the cats during or after treatment. However, after the cessation of treatment, a recurrence of high relative copy numbers of C. felis and severe clinical signs in all cats was seen. Rescue treatment with 21 days of doxycycline was successful at eliminating infection in eight of the cats; a further 28 days of doxycycline was required to eliminate infection in the remaining three cats. It was concluded that 7, 14, and, in some cases, 21 days of treatment with oral doxycycline will not eliminate C. felis infection. At least 28 days of treatment with doxycycline is required to ensure elimination of the organism. Real-time PCR is a sensitive technique for monitoring C. felis infection and the response to antibiotic treatment.",1
"Dean, Rachel, Harley, Ross, Helps, Chris, Caney, Sarah, Gruffydd-Jones, Tim",2
Molecular identification of mumps virus genotypes from clinical samples: standardized method of analysis.,0
"A sensitive nested reverse transcription-PCR assay, targeting a short fragment of the gene encoding the small hydrophobic protein (SH gene), was developed to allow rapid characterization of mumps virus in clinical samples. The sensitivity and specificity of the assay were established using representative genotypes A, B, C, D, E, and F. Mumps virus RNA was characterized directly from cerebrospinal fluid (CSF) samples and in extracts of mumps virus isolates from patients with various clinical syndromes. Direct sequencing of products and subsequent phylogenetic analysis enabled genetic classification. A simple web-based system of sequence analysis was established. The study also allowed characterization of mumps virus strains from Argentina as part of a new subgenotype. This PCR assay for characterization of mumps infections coupled to a web-based analytical program provides a rapid method for identification of known and novel strains.",1
"Palacios, G, Jabado, O, Cisterna, D, de Ory, F, Renwick, N, Echevarria, J E, Castellanos, A, Mosquera, M, Freire, M C, Campos, R H, Lipkin, W I",2
Determinants for the occurrence of acute exacerbation of hepatitis B virus infection in Chinese patients after HBeAg seroclearance.,0
"This study was performed to determine the factors for predicting the occurrence of acute exacerbation of hepatitis B virus infection in HBeAg-negative patients. Two hundred and sixteen patients with known times of HBeAg seroclearance were recruited. Liver biochemistry and virologic markers were monitored. Precore and core promoter mutations were determined by a line probe assay. The median age at HBeAg seroclearance was 34.5 years. The median follow-up duration was 26.4 months. Fifty-six (27.9%) patients had acute exacerbations. By Cox regression analysis, male gender, older age, and core promoter mutations at the time of HBeAg seroclearance were independently associated with the occurrence of acute exacerbation after HBeAg seroclearance (P = 0.025, 0.018, and 0.001, respectively). Fourteen (7.0%) patients had HBeAg seroreversion within a median follow-up period of 11.6 months after HBeAg seroclearance. By Cox regression analysis, older age at HBeAg seroclearance was independently associated with the chance of HBeAg seroreversion (P = 0.01). We concluded that male patients with core promoter mutations and delayed HBeAg seroclearance had a higher cumulative chance of acute exacerbation in the HBeAg-negative phase. Patients with delayed HBeAg seroclearance had a higher frequency of HBeAg seroreversion.",1
"Yuan, He-Jun, Yuen, Man-Fung, Wong, Danny Ka-Ho, Sum, Siu-Man, Doutreloigne, Joke, Sablon, Erwin, Lai, Ching-Lung",2
"Misidentification of Mycobacterium peregrinum, the causal organism of a case of bacteremia and automatic implantable cardioverter defibrillator-associated infection, due to its unusual acid-fast staining characteristics.",0
"We report an unusual case of Mycobacterium peregrinum bacteremia and infection of an automatic implantable cardioverter defibrillator that was originally misidentified as a Nocardia sp. due, in part, to its partially acid-fast staining characteristic, morphology, and odor. The misdiagnosis had a direct effect on patient care, though the patient was subsequently successfully treated.",1
"Short, William R, Emery, Christopher, Bhandary, Mallika, O'Donnell, Judith A",2
Discrimination within phenotypically closely related definitive types of Salmonella enterica serovar typhimurium by the multiple amplification of phage locus typing technique.,0
"Multilocus sequence typing (MLST) is a relatively new high-resolution typing system employed for epidemiological studies of bacteria, including Salmonella. Discrimination based on MLST of housekeeping genes may be problematical, due to the high identity of gene sequences of closely related Salmonella species. The presence of genomic sequences derived from stable temperate phages in Salmonella offers an alternative for MLST of Salmonella. We have used MLST of prophage loci in Salmonella enterica serovar Typhimurium to discriminate closely related isolates of serovar Typhimurium. We have compared these results to MLST of five housekeeping genes, as well as pulsed-field gel electrophoresis (PFGE). The presence or absence of prophage loci in the 73 serovar Typhimurium isolates tested, as well as allelic variation as detected by sequencing, provided greater discrimination between isolates than either MLST of housekeeping genes or PFGE. Amplification of prophage loci alone separated serovar Typhimurium isolates into 27 groups comprising multiple isolates or individual strains. Sequencing of isolates found within the clusters separated isolates even further. By contrast, PFGE could only divide the 73 isolates into five distinct groups. MLST using housekeeping genes did not provide any significant separation of isolates in comparison to amplification or MLST of prophage loci. The results demonstrate that the amplification and sequencing of prophage loci provides a high-resolution, objective method for the discrimination of closely related isolates of serovar Typhimurium. It is proposed that multiple amplification of phage locus typing may provide sufficient discrimination for epidemiological purposes without recourse to MLST.",1
"Ross, Ian L, Heuzenroeder, Michael W",2
Nucleic acid amplification assays for detection of La Crosse virus RNA.,0
"We report the development of nucleic acid sequence-based amplification (NASBA) and quantitative real-time reverse transcription (RT)-PCR assays for the detection of La Crosse (LAC) virus in field-collected vector mosquito samples and human clinical samples. The sensitivities of these assays were compared to that of a standard plaque assay in Vero cells. The NASBA and quantitative real-time RT-PCR assays demonstrated sensitivities greater than that of the standard plaque assay. The specificities of these assays were determined by testing a battery of reference strain viruses, including representative strains of LAC virus and other arthropod-borne viruses. Additionally, these assays were used to detect LAC viral RNA in mosquito pool samples and human brain tissue samples and yielded results within less than 4 h. The NASBA and quantitative real-time RT-PCR assays detect LAC viral RNA in a sensitive, specific, and rapid manner; these findings support the use of these assays in surveillance and diagnostic laboratory systems.",1
"Lambert, Amy J, Nasci, Roger S, Cropp, Bruce C, Martin, Denise A, Rose, Becky C, Russell, Brandy J, Lanciotti, Robert S",2
Evaluation of broth microdilution antifungal susceptibility testing conditions for Trichophyton rubrum.,0
"Fifty clinical isolates of Trichophyton rubrum were selected to test with ketoconazole, fluconazole, itraconazole, griseofulvin, and terbinafine by following the National Committee for Clinical Laboratory Standards susceptibility testing guidelines for filamentous fungi (M38-A). In addition, other susceptibility testing conditions were evaluated: (i) three medium formulations including RPMI 1640 (standard medium), McVeigh & Morton (MVM), and Sabouraud dextrose broth (SDB); (ii) two incubation temperatures (28 and 35 degrees C); and (iii) three incubation periods (4, 7, and 10 days). The strains Candida parapsilosis (ATCC 22019), Candida krusei (ATCC 6258), T. rubrum (ATCC 40051), and Trichophyton mentagrophytes (ATCC 40004) were included as quality controls. All isolates produced clearly detectable growth only after 7 days of incubation. MICs were significantly independent of the incubation temperature (28 or 35 degrees C) (P < 0.05). Different incubation periods resulted in MICs which were consistently different for each medium when azoles and griseofulvin were tested (P < 0.05). MICs obtained from different media at the same incubation time for the same isolate were significantly different when azoles and griseofulvin were tested (P < 0.05). MICs were consistently higher (usually 1 to 2 dilutions) with RPMI than with MVM or SDB (P < 0.05). When terbinafine was tested, no parameter had any influence on MICs (P < 0.05). RPMI standard medium appears to be a suitable testing medium for determining the MICs for T. rubrum. MICs obtained at different incubation times need to be correlated with clinical outcome to demonstrate which time has better reliability.",1
"Santos, D A, Hamdan, J S",2
Colonization of human immunodeficiency virus-infected outpatients in Taiwan with Candida species.,0
"To understand the Candida colonization of human immunodeficiency virus (HIV)-infected outpatients in Taiwan, we have conducted a prospective cohort study of Candida colonization and its risk factors at the National Taiwan University Hospital from 1999 to 2002. More than 50% of the patients were colonized with Candida species, and 12% developed symptomatic candidiasis. Patients colonized with fluconazole-resistant strains of Candida species had a higher prevalence of candidiasis than those colonized with susceptible strains. Our analysis found that antibiotic treatment and lower CD4(+) counts (<200 cells/mm(3)) increased the rate of oropharyngeal candidiasis in HIV-infected patients, while antiretroviral therapy protected patients from the development of candidiasis.",1
"Hung, Chien-Ching, Yang, Yun-Liang, Lauderdale, Tsai-Ling, McDonald, L Clifford, Hsiao, Chin-Fu, Cheng, Hsiao-Hsu, Ho, Yong An, Lo, Hsiu-Jung",2
Characterization of a Bacillus anthracis isolate causing a rare case of fatal anthrax in a 2-year-old boy from Hong Kong.,0
"We used multiple-locus variable-number tandem repeat analysis (MLVA) and pagA sequencing to genotype a Bacillus anthracis isolate from a fatal case of human anthrax in Hong Kong. The isolate has a unique MLVA genotype, is related to the Sterne and Ames strains, and is consistent with genotypes identified in China.",1
"Cheung, Danny T L, Kam, Kai Man, Hau, Kong Lung, Au, Tak Kong, Marston, Chung K, Gee, Jay E, Popovic, Tanja, Van Ert, Matthew N, Kenefic, Leo, Keim, Paul, Hoffmaster, Alex R",2
Multilocus sequence typing versus pulsed-field gel electrophoresis for characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolates.,0
"Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains are emerging pathogens. Molecular typing of ESBL-producing E. coli is useful for surveillance purposes, to monitor outbreaks and track nosocomial spread. Although pulsed-field gel electrophoresis (PFGE) is the current ""gold standard"" for bacterial molecular typing, multilocus sequence typing (MLST) may offer advantages. Forty ESBL-producing E. coli isolates were selected at random from a cohort of intensive care unit patients who had active surveillance perirectal cultures done. PFGE identified 19 unique PFGE types (PT) among the 40 isolates; MLST identified 22 unique sequence types. MLST had greater discriminatory ability than PFGE for ESBL-producing E. coli. Simpson's indices of diversity for PFGE and MLST were 0.895 and 0.956, respectively. There were five clonal complexes (CCs) (isolates with differences of no more than two loci) that each contained multiple PT, but each PT was found in only one CC, indicating genetic consistency within a CC. MLST has clear utility in studies of ESBL-producing E. coli, based on a greater discriminatory ability and reproducibility than PFGE and the ability to a priori define genetically related bacterial strains.",1
"Nemoy, Lucia L, Kotetishvili, Mamuka, Tigno, Justine, Keefer-Norris, Ananda, Harris, Anthony D, Perencevich, Eli N, Johnson, Judith A, Torpey, Dave, Sulakvelidze, Alexander, Morris, J Glenn, Stine, O Colin",2
Long-lasting CD3+ T-cell deficiency after cord blood stem cell transplantation in a human herpesvirus 6-infected child.,0
"We report a long-lasting (8-month) reactivation of human herpesvirus 6 (HHV-6) infection in child who had undergone cord blood stem cell transplantation. The reactivation was characterized by high viral loads and by immediate-early mRNA positivity. HHV-6 infection was associated with a deep depletion of CD3, while the CD4/CD8 ratio remained substantially unchanged.",1
"Comar, Manola, D'Agaro, Pierlanfranco, Horejsh, Douglas, Galvan, Monica, Fiorentini, Simona, Andolina, Marino, Caruso, Arnaldo, Di Luca, Dario, Campello, Cesare",2
Performance of CHROMagar MRSA medium for detection of methicillin-resistant Staphylococcus aureus.,0
"CHROMagar MRSA was evaluated for its ability to identify methicillin-resistant Staphylococcus aureus (MRSA). A well-defined collection consisting of 216 MRSA strains and 241 methicillin-susceptible Staphylococcus aureus isolates was used. The sensitivity of CHROMagar MRSA after 24 h of incubation was 95.4%, increasing to 100% after 48 h. The specificity was already 100% after 24 h.",1
"Diederen, Bram, van Duijn, Inge, van Belkum, Alex, Willemse, Piet, van Keulen, Peter, Kluytmans, Jan",2
"Invasive group A streptococcal disease in Alberta, Canada (2000 to 2002).",0
"Invasive group A streptococcal (iGAS) disease was placed under surveillance in Alberta in August 1999. The purpose of this study was to determine the incidence rates of iGAS infections throughout Alberta over a 3-year period (2000 to 2002) and to better understand the epidemiology of iGAS in this province. There were a total of 441 cases of invasive GAS disease over the 3 years examined (average population over 3 years, 3,055,765) and 47 deaths. The incidence in Alberta was 5.0 (2000), 5.7 (2001), and 3.8 (2002) per 100,000. The two main metropolitan regions (Edmonton and Calgary) had the majority of iGAS disease cases (305 cases), producing incidence rates of 4.8 (Edmonton) and 6.9 (Calgary) in 2000, 6.9 (Edmonton) and 6.6 (Calgary) in 2001, and 4.1 (Edmonton) and 3.9 (Calgary) in 2002, as well as deaths attributable to GAS (31 deaths). The three most prevalent M types were M1 (71 cases), M3 (52 cases), and MPT2967 (44 cases). With respect to age, the highest incidence rates occurred in those less than 1 year old (11.7 per 100,000) and those 65 years or older (11.5 per 100,000). Varicella virus infection preceded iGAS disease in 25% of children 8 years of age and under. A seasonal association was observed during the 3 years studied, with the highest number of cases occurring in the winter months and the lowest occurring during the summer months. The data for years 2000 and 2001 show that the metropolitan regions of Alberta experienced some of the highest incidence rates reported in North America in the past decade.",1
"Tyrrell, Gregory J, Lovgren, Marguerite, Kress, Bertha, Grimsrud, Karen",2
Multilocus variable-number tandem repeat typing of Mycobacterium ulcerans.,0
"The apparent genetic homogeneity of Mycobacterium ulcerans contributes to the poorly understood epidemiology of M. ulcerans infection. Here, we report the identification of variable number tandem repeat (VNTR) sequences as novel polymorphic elements in the genome of this species. A total of 19 potential VNTR loci identified in the closely related M. marinum genome sequence were screened in a collection of 23 M. ulcerans isolates, one Mycobacterium species referred to here as an intermediate species, and five M. marinum strains. Nine of the 19 loci were polymorphic in the three species (including the intermediate species) and revealed eight M. ulcerans and five M. marinum genotypes. The results from the VNTR analysis corroborated the genetic relationships of M. ulcerans isolates from various geographical origins, as defined by independent molecular markers. Although these results further highlight the extremely high clonal homogeneity within certain geographic regions, we report for the first time the discrimination of the two South American strains from Surinam and French Guyana. These findings support the potential of a VNTR-based genotyping method for strain discrimination within M. ulcerans and M. marinum.",1
"Ablordey, Anthony, Swings, Jean, Hubans, Christine, Chemlal, Karim, Locht, Camille, Portaels, Françoise, Supply, Philip",2
"Utility of pooled urine specimens for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in men attending public sexually transmitted infection clinics in Mumbai, India, by PCR.",0
"Pooling urogenital specimens for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by nucleic acid amplification tests is an attractive alternative to individual testing. As pooling can reduce the costs of testing as well as labor, it has been advocated for use in resource-poor settings. However, it has neither been widely adopted nor evaluated for use in developing countries. We evaluated the practical use of pooling first-catch urine (FCU) specimens for the detection of C. trachomatis and N. gonorrhoeae from 690 men in Mumbai, India, by PCR. FCU, urethral smears, and swabs were collected from men seen at two sexually transmitted infection (STI) clinics. All laboratory testing was done at the Lokmanya Tilak General Hospital. Gram stain smears and culture isolation for N. gonorrhoeae were performed. Each FCU was tested individually and in pools using the Roche Amplicor PCR for C. trachomatis and N. gonorrhoeae with an internal control for inhibition. Specimen pools consisted of aliquots from five consecutively processed FCUs combined into an amplification tube. An optical density reading of > or =0.20 indicated a pool for which subsequent testing of individual samples was required. Prevalence by PCR on single specimens was 2.2% (15/690) for C. trachomatis and 5.4% (37/690) for N. gonorrhoeae. Compared to individual FCU results, pooling for C. trachomatis and N. gonorrhoeae had an overall sensitivity of 96.1% (50/52). Specificity was 96.5% (83/86) in that three pools required single testing that failed to identify a positive specimen. Pooling missed two positive specimens, decreased the inhibition rate, and saved 50.3% of reagent costs. In this resource-limited setting, the use of pooling to detect C. trachomatis and N. gonorrhoeae by PCR proved to be a simple, accurate, and cost-effective procedure compared to individual testing.",1
"Lindan, Christina, Mathur, Meenakshi, Kumta, Sameer, Jerajani, Hermangi, Gogate, Alka, Schachter, Julius, Moncada, Jeanne",2
Identification of clinically relevant viridans streptococci by an oligonucleotide array.,0
"Viridans streptococci (VS) are common etiologic agents of subacute infective endocarditis and are capable of causing a variety of pyogenic infections. Many species of VS are difficult to differentiate by phenotypic traits. An oligonucleotide array based on 16S-23S rRNA gene intergenic spacer (ITS) sequences was developed to identify 11 clinically relevant VS. These 11 species were Streptococcus anginosus, S. constellatus, S. gordonii, S. intermedius, S. mitis, S. mutans, S. oralis, S. parasanguinis, S. salivarius, S. sanguinis, and S. uberis. The method consisted of PCR amplification of the ITS regions by using a pair of universal primers, followed by hybridization of the digoxigenin-labeled PCR products to a panel of species-specific oligonucleotides immobilized on a nylon membrane. After 120 strains of the 11 species of VG and 91 strains of other bacteria were tested, the sensitivity and specificity of the oligonucleotide array were found to be 100% (120 of 120 strains) and 95.6% (87 of 91 strains), respectively. S. pneumoniae cross-hybridized to the probes used for the identification of S. mitis, and simple biochemical tests such as optochin susceptibility or bile solubility should be used to differentiate S. pneumoniae from S. mitis. In conclusion, identification of species of VS by use of the present oligonucleotide array is accurate and could be used as an alternative reliable method for species identification of strains of VS.",1
"Chen, Chao Chien, Teng, Lee Jene, Kaiung, Seng, Chang, Tsung Chain",2
Direct detection of Nocardia spp. in clinical samples by a rapid molecular method.,0
We developed a 16S PCR-based assay for the rapid detection of Nocardia spp. directly from human clinical samples. The applicability of the assay was confirmed by using 18 samples from patients with nocardiosis as diagnosed by conventional cultures and 20 clinical samples from patients with confirmed tuberculosis used as negative controls.,1
"Couble, Andrée, Rodríguez-Nava, Verónica, de Montclos, Michèle Pérouse, Boiron, Patrick, Laurent, Frédéric",2
"Identification of genotype 3 hepatitis E virus (HEV) in serum and fecal samples from pigs in Thailand and Mexico, where genotype 1 and 2 HEV strains are prevalent in the respective human populations.",0
"Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important public health concern in many developing countries. Increasing evidence indicates that hepatitis E is a zoonotic disease. There exist four major genotypes of HEV, and HEV isolates identified in samples from pigs belong to either genotype 3 or 4. Genotype 1 and 2 HEVs are found exclusively in humans. To determine whether genotype 1 and 2 HEVs also exist in pigs, a universal reverse transcription-PCR assay that is capable of detecting all four HEV genotypes was used to test for the presence of HEV RNA in serum and/or fecal samples from pigs in Thailand, where genotype 1 human HEV is prevalent, and from pigs in Mexico, where genotype 2 human HEV was epidemic. In Thailand, swine HEV RNA was detected in sera from 10/26 pigs of 2 to 4 months of age but not in sera from 50 pigs of other ages. In Mexico, swine HEV RNA was detected in 8/125 sera and 28/92 fecal samples from 2- to 4-month-old pigs. Antibodies to swine HEV were also detected in about 81% of the Mexican pigs. A total of 44 swine HEV isolates were sequenced for the open reading frame 2 gene region. Sequence analyses revealed that all swine HEV isolates identified in samples from pigs in Thailand and Mexico belong to genotype 3. Phylogenetic analyses revealed that minor branches associated with geographic origin exist among the swine HEV isolates. The results indicated that genotype 1 or 2 swine HEV does not exist in pigs from countries where the respective human HEV genotype 1 or 2 is prevalent. It is likely that only genotype 3 and 4 HEV strains have zoonotic potential.",1
"Cooper, K, Huang, F F, Batista, L, Rayo, C D, Bezanilla, J C, Toth, T E, Meng, X J",2
Surgery and treatment with high-dose liposomal amphotericin B for eradication of craniofacial zygomycosis in a patient with Hodgkin's disease who had undergone allogeneic hematopoietic stem cell transplantation.,0
"This case report describes craniofacial zygomycosis in a 24-year-old male with Hodgkin's disease who underwent chemotherapy and autologous hematopoietic stem cell transplantation, followed by a nonmyeloablative allogeneic transplant. Empirical therapy with itraconazole and amoxicillin-clavulanate failed to resolve the infection. Postdiagnosis, surgery and treatment with high-dose liposomal amphotericin B eradicated the disease.",1
"Barron, Michelle A, Lay, Margaret, Madinger, Nancy E",2
Bacteremia caused by Clostridium intestinale.,0
"We describe a case of Clostridium intestinale bacteremia in a previously healthy adolescent female presenting with fever and abdominal pain. The bacterium was definitively identified via 16S rRNA gene sequencing. This is the first report, in the world literature, of human infection caused by this microorganism.",1
"Elsayed, Sameer, Zhang, Kunyan",2
"Comparing genomes of Helicobacter pylori strains from the high-altitude desert of Ladakh, India.",0
"The genomic diversity of Helicobacter pylori from the vast Indian subcontinent is largely unknown. We compared the genomes of 10 H. pylori strains from Ladakh, North India. Molecular analysis was carried out to identify rearrangements within and outside the cag pathogenicity island (cag PAI) and DNA sequence divergence in candidate genes. Analyses of virulence genes (such as the cag PAI as a whole, cagA, vacA, iceA, oipA, babB, and the plasticity cluster) revealed that H. pylori strains from Ladakh are genetically distinct and possibly less virulent than the isolates from East Asian countries, such as China and Japan. Phylogenetic analyses based on the cagA-glr motifs, enterobacterial repetitive intergenic consensus patterns, repetitive extragenic palindromic signatures, the glmM gene mutations, and several genomic markers representing fluorescent amplified fragment length polymorphisms revealed that Ladakhi strains share features of the Indo-European, as well as the East Asian, gene pools. However, the contribution of genetic features from the Indo-European gene pool was more prominent.",1
"Kauser, Farhana, Hussain, M Abid, Ahmed, Irshad, Ahmad, Naheed, Habeeb, Aejaz, Khan, Aleem A, Ahmed, Niyaz",2
"Epidemiology and predictors of mortality in cases of Candida bloodstream infection: results from population-based surveillance, barcelona, Spain, from 2002 to 2003.",0
"We conducted population-based surveillance for Candida bloodstream infections in Spain to determine its incidence, the extent of antifungal resistance, and risk factors for mortality. A case was defined as the first positive blood culture for any Candida spp. in a resident of Barcelona, from 1 January 2002 to 31 December 2003. We defined early mortality as occurring between days 3 to 7 after candidemia and late mortality as occurring between days 8 to 30. We detected 345 cases of candidemia, for an average annual incidence of 4.3 cases/100,000 population, 0.53 cases/1,000 hospital discharges, and 0.73 cases/10,000 patient-days. Outpatients comprised 11% of the cases, and 89% had a central venous catheter (CVC) at diagnosis. Overall mortality was 44%. Candida albicans was the most frequent species (51% of cases), followed by Candida parapsilosis (23%), Candida tropicalis (10%), Candida glabrata (8%), Candida krusei (4%), and other species (3%). Twenty-four isolates (7%) had decreased susceptibility to fluconazole (MIC > or = 16 microg/ml). On multivariable analysis, early death was independently associated with hematological malignancy (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.1 to 10.4). Treatment with antifungals (OR, 0.05; 95% CI, 0.01 to 0.2) and removal of CVCs (OR, 0.3; 95% CI, 0.1 to 0.9) were protective factors for early death. Receiving adequate treatment, defined as having CVCs removed and administration of an antifungal medication (OR, 0.2; 95% CI, 0.08 to 0.8), was associated with lower odds of late mortality; intubation (OR, 7.5; 95% CI, 2.6 to 21.1) was associated with higher odds. The incidence of candidemia and prevalence of fluconazole resistance are similar to other European countries, indicating that routine antifungal susceptibility testing is not warranted. Antifungal medication and catheter removal are critical in preventing mortality.",1
"Almirante, Benito, Rodríguez, Dolors, Park, Benjamin J, Cuenca-Estrella, Manuel, Planes, Ana M, Almela, Manuel, Mensa, Jose, Sanchez, Ferran, Ayats, Josefina, Gimenez, Montserrat, Saballs, Pere, Fridkin, Scott K, Morgan, Juliette, Rodriguez-Tudela, Juan L, Warnock, David W, Pahissa, Albert",2
Application of a molecular panel to demonstrate enterotropic virus shedding by healthy and human immunodeficiency virus-infected patients.,0
"We used a molecular panel, targeting seven enteric viruses, to explore the advantage of using molecular methods to establish the etiology of enteric diseases and to evaluate the prevalence of enteric viruses in asymptomatic human immunodeficiency virus-infected patients. This approach favors rapidity and sensitivity of laboratory diagnosis of viral enteric syndromes.",1
"Minosse, Claudia, Zaniratti, Maria S, Calcaterra, Silvia, Carletti, Fabrizio, Muscillo, Michele, Pisciotta, Marina, Pillitteri, Letizia, Corpolongo, Angela, Lauria, Francesco Nicola, Narciso, Pasquale, Anzidei, Gianfranco, Capobianchi, Maria R",2
Controlled clinical comparison of plastic and glass bottles of BacT/ALERT FA medium for culturing organisms from blood of adult patients.,0
"A new, clear-plastic nonvented aerobic FA bottle, designed to prevent breakage, has been developed for the BacT/ALERT blood culture system. We assessed the new plastic FA bottle by comparing its performance with that of the current glass FA bottle for recovery of microorganisms and time to detection of growth in blood samples obtained for culture from adult patients with suspected bloodstream infections. We conclude that the BacT/ALERT plastic and glass FA bottles are comparable for recovery of microorganisms and that the safety advantage of plastic bottles can be achieved without compromising performance.",1
"Petti, Cathy A, Mirrett, Stanley, Woods, Christopher W, Reller, L Barth",2
Influence of age and previous diet of Anopheles gambiae on the infectivity of natural Plasmodium falciparum gametocytes from human volunteers.,0
"The effect of age and dietary factors of Anopheles gambiae (Diptera: Culicidae) on the infectivity of natural Plasmodium falciparum parasites was studied. Mosquitoes of various ages (1-3, 4-7 and 8-11 day old) and those fed blood (either single or double meals) and sugar meals were experimentally co-infected with P. falciparum gametocytes obtained from different naturally infected human volunteers. On day 7, midguts were examined for oocyst infection to determine whether mosquito age or diets have significant effects on parasite infectivity. The age of the mosquitoes did not significantly influence the oocyst infection rates (chi2 = 48.32, df = 40, P = 0.172) or oocyst load (# of oocysts/midgut) (P = 0.14) observed. Oocyst load between groups was not significantly different. Similarly, the type of diet (either blood or sugar) did not influence oocyst infection rates (chi2 = 16.52, df = 19, P = 0.622). However, an increase in oocyst infection rates resulted after previous feeding on double blood meals (35%) compared to single blood meals (25%), with comparable oocyst load. These observations are in agreement with those reported in previous studies suggesting that increased mosquito nutritional reserves resulting from increased dietary resources is favorable for malaria infectivity. This field-based study indicates that vector competence of An. gambiae to natural P. falciparum parasites does not vary with age and that nutritional resources acquired prior to an infectious blood meal plays a crucial role in mosquito-parasite relationships.",1
"Okech, Bernard A, Gouagna, Louis C, Kabiru, Ephantus W, Beier, John C, Yan, Guiyun, Githure, John I",2
"Development of bollworms, Helicoverpa zea, on two commercial Bollgard cultivars that differ in overall Cry1Ac levels.",0
"Research was conducted to quantify the development of the corn earworm (= bollworm), Helicoverpa zea (Boddie), on two different transgenic cotton cultivars (DP 50B and NuCOTN 33B) that contained different levels of the Cry1Ac endotoxin from the soil bacterium, Bacillus thuringiensis Berliner. Using a field cage, an inverse relationship between the amount of Cry1Ac among cultivars versus the weight of bollworm larvae was observed. Larvae that were recovered from the DP 50B cultivar expressing lower Cry1Ac weighed significantly more than larvae collected from the higher expressing NuCOTN 33B cultivar. Cotton plants from NuCOTN 33B were measured as expressing 300% more Cry1Ac than DP 50B plants. The distribution of larval weights indicates that more late-instars (> 200 mg) were collected from the lower expressing DP50B cultivar than the higher expressing NuCOTN 33B cultivar. Within a single population, bollworm larvae were highly variable in their development when feeding on Bollgard cotton. Possible reasons and consequences for this variation are discussed.",1
"Adamczyk, John J, Gore, Jeffrey",2
Biotinylation facilitates the uptake of large peptides by Escherichia coli and other gram-negative bacteria.,0
"Gram-negative bacteria such as Escherichia coli can normally only take up small peptides less than 650 Da, or five to six amino acids, in size. We have found that biotinylated peptides up to 31 amino acids in length can be taken up by E. coli and that uptake is dependent on the biotin transporter. Uptake could be competitively inhibited by free biotin or avidin and blocked by the protonophore carbonyl m-chlorophenylhydrazone and was abolished in E. coli mutants that lacked the biotin transporter. Biotinylated peptides could be used to supplement the growth of a biotin auxotroph, and the transported peptides were shown to be localized to the cytoplasm in cell fractionation experiments. The uptake of biotinylated peptides was also demonstrated for two other gram-negative bacteria, Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa. This finding may make it possible to create new peptide antibiotics that can be used against gram-negative pathogens. Researchers have used various moieties to cause the illicit transport of compounds in bacteria, and this study demonstrates the illicit transport of the largest known compound to date.",1
"Walker, Jennifer R, Altman, Elliot",2
"Vertical distribution of the free-living amoeba population in soil under desert shrubs in the Negev desert, Israel.",0
"A field study was designed to examine the effect of desert shrubs on the dynamics of free-living amoebae in arid soil. Soil samples from 0- to 50-cm depths were collected at 10-cm intervals in each of the four seasons. The vertical distributions of the four main morphological types of amoebae, grouped according to their mobility, and of small flagellate populations were measured under the canopies of Hammada scoparia and Atriplex halimus, shrubs belonging to the chloride-absorbing xerohalophytes. The result obtained from the field study demonstrated that the total number of protozoa was significantly higher during the wet seasons (winter and spring) than during the dry seasons. The protozoan population was more diverse under the canopy of H. scoparia during the wet seasons, reaching 8,000 individuals per 1 g of dry soil, whereas during the dry seasons, the populations were higher under the canopy of A. halimus, with a mean of 250 individuals. The protozoan population in the deeper layers (40 to 50 cm) was found to be as active as that in the upper layers, demonstrating that, in the desert, soil columns below 20 cm are fertile and worth studying. The type 1 amoebae (e.g., Acanthamoeba and Filamoeba spp.) were the most abundant throughout the study period, and their numbers were significantly higher than those of the other amoeba types.",1
"Rodriguez-Zaragoza, Salvador, Mayzlish, Einav, Steinberger, Yosef",2
Effects of artificial defoliation of pines on the structure and physiology of the soil fungal community of a mixed pine-spruce forest.,0
"Loss of photosynthetic area can affect soil microbial communities by altering the availability of fixed carbon. We used denaturing gradient gel electrophoresis (DGGE) and Biolog filamentous-fungus plates to determine the effects of artificial defoliation of pines in a mixed pine-spruce forest on the composition of the fungal community in a forest soil. As measured by DGGE, two fungal species were affected significantly by the defoliation of pines (P < 0.001); the frequency of members of the ectomycorrhizal fungus genus Cenococcum decreased significantly, while the frequency of organisms of an unidentified soil fungus increased. The decrease in the amount of Cenococcum organisms may have occurred because of the formation of extensive hyphal networks by species of this genus, which require more of the carbon fixed by their host, or because this fungus is dependent upon quantitative differences in spruce root exudates. The defoliation of pines did not affect the overall composition of the soil fungal community or fungal-species richness (number of species per core). Biolog filamentous-fungus plate assays indicated a significant increase (P < 0.001) in the number of carbon substrates utilized by the soil fungi and the rate at which these substrates were used, which could indicate an increase in fungal-species richness. Thus, either small changes in the soil fungal community give rise to significant increases in physiological capabilities or PCR bias limits the reliability of the DGGE results. These data indicate that combined genetic and physiological assessments of the soil fungal community are needed to accurately assess the effect of disturbance on indigenous microbial systems.",1
"Cullings, Ken, Raleigh, Christopher, New, Michael H, Henson, Joan",2
Optimization of cholesterol removal by probiotics in the presence of prebiotics by using a response surface method.,0
"Lactobacillus casei ASCC 292 was grown in the presence of six prebiotics, namely, sorbitol, mannitol, maltodextrin, high-amylose maize, fructooligosaccharide (FOS), and inulin, in order to determine the combination of probiotic and prebiotics that would remove the highest level of cholesterol. A first-order model showed that the combination of L. casei ASCC 292, FOS, and maltodextrin was the most efficient for the removal of cholesterol, and the optimum experimental region was developed by using the steepest ascent. This led to the middle points of probiotic (1.70% [wt/vol]), FOS (4.80% [wt/vol]), and maltodextrin (6.80% [wt/vol]) for the development of a central composite design for optimization. Perturbation plot, response surface, and coefficient estimates showed that all three factors had significant quadratic effects on cholesterol removal, with FOS showing the most conspicuous quadratic change. A second-order polynomial regression model estimated that the optimum condition of the factors for cholesterol removal by L. casei ASCC 292 is 1.71% (wt/vol) probiotic, 4.95% (wt/vol) FOS, and 6.62% (wt/vol) maltodextrin. Validation experiments showed that the predicted optimum conditions were more efficient than the high and low levels of the factors and the center points. A response surface method proved reliable for developing the model, optimizing factors, and analyzing interaction effects. Analyses of growth, substrate utilization, growth yield, mean doubling time, and short-chain fatty acid (SCFA) production by the use of quadratic models indicated that cholesterol removal was growth associated. The concentration of L. casei ASCC 292 had the most significant quadratic effect on all responses studied, except for substrate utilization and SCFA production, which were significantly (P < 0.05) influenced by the interactions between the probiotic and both prebiotics, indicating that they were closely associated with the uptake of prebiotics.",1
"Liong, M T, Shah, N P",2
Potential of the polyvalent anti-Staphylococcus bacteriophage K for control of antibiotic-resistant staphylococci from hospitals.,0
"The increasing prevalence of antibiotic-resistant staphylococci has prompted the need for antibacterial controls other than antibiotics. In this study, a lytic bacteriophage (phage K) was assessed in vitro for its ability to inhibit emerging drug-resistant Staphylococcus aureus strains from hospitals and other species of Staphylococcus isolated from bovine infections. In in vitro inhibitory assays, phage K lysed a range of clinically isolated methicillin-resistant S. aureus (MRSA) strains, S. aureus with heterogeneous vancomycin resistance and vancomycin resistance, and teicoplanin-resistant strains. In these assays, 14 of the MRSA strains were initially only weakly sensitive to this phage. However, propagation of phage K on these less-sensitive strains resulted in all 14 being sensitive to the modified phages. The results enforce the principle that, while certain target bacteria may be relatively insensitive to lytic phage, this can be overcome by obtaining modified phage variants from passage of the phage through the insensitive strains. Model in situ hand wash studies using a phage-enriched wash solution resulted in a 100-fold reduction in staphylococcal numbers on human skin by comparison with numbers remaining after washing in phage-free solution. Infusion of the phage into a nonimmunogenic bismuth-based cream resulted in strong anti-Staphylococcus activity from the cream on plates and in broth.",1
"O'Flaherty, S, Ross, R P, Meaney, W, Fitzgerald, G F, Elbreki, M F, Coffey, A",2
"Identification and molecular epidemiology of Campylobacter coli isolates from human gastroenteritis, food, and animal sources by amplified fragment length polymorphism analysis and Penner serotyping.",0
"Campylobacter coli is an infrequently studied but important food-borne pathogen with a wide natural distribution. We investigated its molecular epidemiology by use of amplified fragment length polymorphism (AFLP)-based genotyping and Penner serotyping. Serotype reference strains and 177 Danish isolates of diverse origin identified by routine phenotyping as C. coli were examined. Molecular tools identified some 12% of field isolates as Campylobacter jejuni, emphasizing the need for improved identification methods in routine laboratories. Cluster analysis of AFLP profiles of 174 confirmed C. coli isolates revealed a difference in the distribution of isolates from pig and poultry (chicken, duck, turkey, and ostrich) species and indicated the various poultry species, but not pigs, to be likely sources of human C. coli infection. A poor correlation was observed between serotyping and AFLP profiling, suggesting that the former method has limited value in epidemiological studies of this species.",1
"Siemer, B L, Nielsen, E M, On, S L W",2
Genetic diversity of benzoyl coenzyme A reductase genes detected in denitrifying isolates and estuarine sediment communities.,0
"Benzoyl coenzyme A (benzoyl-CoA) reductase is a central enzyme in the anaerobic degradation of organic carbon, which utilizes a common intermediate (benzoyl-CoA) in the metabolism of many aromatic compounds. The diversity of benzoyl-CoA reductase genes in denitrifying bacterial isolates capable of degrading aromatic compounds and in river and estuarine sediment samples from the Arthur Kill in New Jersey and the Chesapeake Bay in Maryland was investigated. Degenerate primers were developed from the known benzoyl-CoA reductase genes from Thauera aromatica, Rhodopseudomonas palustris, and Azoarcus evansii. PCR amplification detected benzoyl-CoA reductase genes in the denitrifying isolates belonging to alpha-, beta-, or gamma-Proteobacteria as well as in the sediment samples. Phylogenetic analysis, sequence similarity comparison, and conserved indel determination grouped the new sequences into either the bcr type (found in T. aromatica and R. palustris) or the bzd type (found in A. evansii). All the Thauera strains and the isolates from the genera Acidovorax, Bradyrhizobium, Paracoccus, Ensifer, and Pseudomonas had bcr-type benzoyl-CoA reductases with amino acid sequence similarities of more than 97%. The genes detected from Azarocus strains were assigned to the bzd type. A total of 50 environmental clones were detected from denitrifying consortium and sediment samples, and 28 clones were assigned to either the bcr or the bzd type of benzoyl-CoA reductase genes. Thus, we could determine the genetic capabilities for anaerobic degradation of aromatic compounds in sediment communities of the Chesapeake Bay and the Arthur Kill on the basis of the detection of two types of benzoyl-CoA reductase genes. The detected genes have future applications as genetic markers to monitor aromatic compound degradation in natural and engineered ecosystems.",1
"Song, Bongkeun, Ward, Bess B",2
Endophytic colonization of Vitis vinifera L. by plant growth-promoting bacterium Burkholderia sp. strain PsJN.,0
"Patterns of colonization of Vitis vinifera L. cv. Chardonnay plantlets by a plant growth-promoting bacterium, Burkholderia sp. strain PsJN, were studied under gnotobiotic conditions. Wild-type strain PsJN and genetically engineered derivatives of this strain tagged with gfp (PsJN::gfp2x) or gusA (PsJN::gusA11) genes were used to enumerate and visualize tissue colonization. The rhizospheres of 4- to 5-week-old plantlets with five developed leaves were inoculated with bacterial suspensions. Epiphytic and endophytic colonization patterns were then monitored by dilution plating assays and microscopic observation of organ sections. Bacteria were chronologically detected first on root surfaces, then in root internal tissues, and finally in the fifth internode and the tissues of the fifth leaf. Analysis of the PsJN colonization patterns showed that this strain colonizes grapevine root surfaces, as well as cell walls and the whole surface of some rhizodermal cells. Cells were also abundant at lateral root emergence sites and root tips. Furthermore, cell wall-degrading endoglucanase and endopolygalacturonase secreted by PsJN explained how the bacterium gains entry into root internal tissues. Host defense reactions were observed in the exodermis and in several cortical cell layers. Bacteria were not observed on stem and leaf surfaces but were found in xylem vessels of the fifth internode and the fifth leaf of plantlets. Moreover, bacteria were more abundant in the fifth leaf than in the fifth internode and were found in substomatal chambers. Thus, it seems that Burkholderia sp. strain PsJN induces a local host defense reaction and systemically spreads to aerial parts through the transpiration stream.",1
"Compant, Stéphane, Reiter, Birgit, Sessitsch, Angela, Nowak, Jerzy, Clément, Christophe, Ait Barka, Essaïd",2
"Anaerobic, nitrate-dependent oxidation of U(IV) oxide minerals by the chemolithoautotrophic bacterium Thiobacillus denitrificans.",0
"Under anaerobic conditions and at circumneutral pH, cells of the widely distributed, obligate chemolithoautotrophic bacterium Thiobacillus denitrificans oxidatively dissolved synthetic and biogenic U(IV) oxides (uraninite) in nitrate-dependent fashion: U(IV) oxidation required the presence of nitrate and was strongly correlated with nitrate consumption. This is the first report of anaerobic U(IV) oxidation by an autotrophic bacterium.",1
"Beller, Harry R",2
Nonbioluminescent strains of Photobacterium phosphoreum produce the cell-to-cell communication signal N-(3-Hydroxyoctanoyl)homoserine lactone.,0
"Bioluminescence is a common phenotype in marine bacteria, such as Vibrio and Photobacterium species, and can be quorum regulated by N-acylated homoserine lactones (AHLs). We extracted a molecule that induced a bacterial AHL monitor (Agrobacterium tumefaciens NT1 [pZLR4]) from packed cod fillets, which spoil due to growth of Photobacterium phosphoreum. Interestingly, AHLs were produced by 13 nonbioluminescent strains of P. phosphoreum isolated from the product. Of 177 strains of P. phosphoreum (including 18 isolates from this study), none of 74 bioluminescent strains elicited a reaction in the AHL monitor, whereas 48 of 103 nonbioluminescent strains did produce AHLs. AHLs were also detected in Aeromonas spp., but not in Shewanella strains. Thin-layer chromatographic profiles of cod extracts and P. phosphoreum culture supernatants identified a molecule similar in relative mobility (Rf value) and shape to N-(3-hydroxyoctanoyl)homoserine lactone, and the presence of this molecule in culture supernatants from a nonbioluminescent strain of P. phosphoreum was confirmed by high-performance liquid chromatography-positive electrospray high-resolution mass spectrometry. Bioluminescence (in a non-AHL-producing strain of P. phosphoreum) was strongly up-regulated during growth, whereas AHL production in a nonbioluminescent strain of P. phosphoreum appeared constitutive. AHLs apparently did not influence bioluminescence, as the addition of neither synthetic AHLs nor supernatants delayed or reduced this phenotype in luminescent strains of P. phosphoreum. The phenotypes of nonbioluminescent P. phosphoreum strains regulated by AHLs remains to be elucidated.",1
"Flodgaard, L R, Dalgaard, P, Andersen, J B, Nielsen, K F, Givskov, M, Gram, L",2
Prevalence and genetic diversity of Campylobacter spp. in environmental water samples from a 100-square-kilometer predominantly dairy farming area.,0
"Water samples were taken systematically from a 100-km2 area of mainly dairy farmland in northwestern England and examined for Campylobacter spp. Pulsed-field gel electrophoresis-restriction fragment length polymorphism (PFGE-RFLP) and flaA strain typing of Campylobacter jejuni and Campylobacter coli isolates were done. Data on the water source and the adjacent environment were recorded and examined as explanatory variables. Campylobacter spp. were isolated from 40.5% (n = 119) of the water samples tested. C. jejuni was isolated from 14.3%, C. coli was isolated from 18.5%, and Campylobacter lari was isolated from 4.2% of the samples. Campylobacter hyointestinalis was not isolated from any water source. The difference in prevalence between water types (trough, running, and standing) was significant (P = 0.001). C. jejuni was the species most commonly isolated from trough-water and running-water sources, while C. coli was the most frequently isolated from standing water (P < 0.001). No association was found between the presence of Escherichia coli and that of Campylobacter spp. The final multivariable logistic regression model for Campylobacter spp. included the following variables: water source, soil type, aspect, and amount of cattle fecal material in the environment (fecal pat count). Strain typing demonstrated a diverse population of C. jejuni and the presence of a common C. coli flaA type that was widely distributed throughout the area. Most of the isolates within the common flaA type were discriminated by PFGE-RFLP. These findings suggest a possible role for environmental water in the epidemiology of Campylobacter spp. in a farming environment.",1
"Kemp, R, Leatherbarrow, A J H, Williams, N J, Hart, C A, Clough, H E, Turner, J, Wright, E J, French, N P",2
Novel major bacterial candidate division within a municipal anaerobic sludge digester.,0
"In a previous study, we analyzed the molecular diversity of Planctomycetales by PCR amplification and sequencing of 16S rRNA clone libraries generated from a municipal wastewater plant, using planctomycete-specific and universal primer sets (R. Chouari, D. Le Paslier, P. Daegelen, P. Ginestet, J. Weissenbach, and A. Sghir, Appl. Environ. Microbiol. 69:7354-7363, 2003). Only a small fraction (4%) of the 16S rRNA gene sequences of the digester clone library corresponded to the Planctomycetales division. Importantly, 85.9% of the digester clone sequences are grouped into two different clusters named WWE1 (81.4% of the sequences) and WWE2 (4.5%) and are distantly affiliated with unidentified bacterial sequences retrieved from a methanogenic reactor community and from a termite gut, respectively. In phylogenetic analysis using 16S rRNA gene sequence representatives of the main phylogenetic bacterial divisions, the two clusters are monophyletic, branch apart from each other, and are distantly related to Planctomycetales and other bacterial divisions. A novel candidate division is proposed for WWE1, while the WWE2 cluster strongly affiliates with the recently proposed Lentisphearae phylum. We designed and validated a 16S rRNA probe targeting WWE1 16S rRNA sequences by both fluorescent in situ hybridization (FISH) and dot blot hybridization (DBH). Results of FISH analysis show that WWE1 representative microorganisms are rods or filamentous shaped, while DBH shows that WWE1 accounts for 12% of the total bacterial rRNA within the anaerobic digester. The remaining 16S rRNA gene sequences are affiliated with Verrucomicrobia or recently described candidate divisions with no known pure culture representatives, such as OD1, BRC1, or NBL-UPA2, making up less than 3.5% of the clone library, respectively. This inventory expands the known diversity of the latter bacterial division-level lineages.",1
"Chouari, Rakia, Le Paslier, Denis, Dauga, Catherine, Daegelen, Patrick, Weissenbach, Jean, Sghir, Abdelghani",2
Pathways for methanogenesis and diversity of methanogenic archaea in three boreal peatland ecosystems.,0
"The main objectives of this study were to uncover the pathways used for methanogenesis in three different boreal peatland ecosystems and to describe the methanogenic populations involved. The mesotrophic fen had the lowest proportion of CH4 produced from H2-CO2. The oligotrophic fen was the most hydrogenotrophic, followed by the ombrotrophic bog. Each site was characterized by a specific group of methanogenic sequences belonging to Methanosaeta spp. (mesotrophic fen), rice cluster-I (oligotrophic fen), and fen cluster (ombrotrophic bog).",1
"Galand, P E, Fritze, H, Conrad, R, Yrjälä, K",2
Biocatalytic production of perillyl alcohol from limonene by using a novel Mycobacterium sp. cytochrome P450 alkane hydroxylase expressed in Pseudomonas putida.,0
"A number of oxygenated monoterpenes present at low concentrations in plant oils have anticarcinogenic properties. One of the most promising compounds in this respect is (-)-perillyl alcohol. Since this natural product is present only at low levels in a few plant oils, an alternative, synthetic source is desirable. Screening of 1,800 bacterial strains showed that many alkane degraders were able to specifically hydroxylate l-limonene in the 7 position to produce enantiopure (-)-perillyl alcohol. The oxygenase responsible for this was purified from the best-performing wild-type strain, Mycobacterium sp. strain HXN-1500. By using N-terminal sequence information, a 6.2-kb ApaI fragment was cloned, which encoded a cytochrome P450, a ferredoxin, and a ferredoxin reductase. The three genes were successfully coexpressed in Pseudomonas putida by using the broad-host-range vector pCom8, and the recombinant converted limonene to perillyl alcohol with a specific activity of 3 U/g (dry weight) of cells. The construct was subsequently used in a 2-liter bioreactor to produce perillyl alcohol on a scale of several grams.",1
"van Beilen, Jan B, Holtackers, René, Lüscher, Daniel, Bauer, Ulrich, Witholt, Bernard, Duetz, Wouter A",2
Proteomic profiling of recombinant Escherichia coli in high-cell-density fermentations for improved production of an antibody fragment biopharmaceutical.,0
"By using two-dimensional polyacrylamide gel electrophoresis, a proteomic analysis over time was conducted with high-cell-density, industrial, phosphate-limited Escherichia coli fermentations at the 10-liter scale. During production, a recombinant, humanized antibody fragment was secreted and assembled in a soluble form in the periplasm. E. coli protein changes associated with culture conditions were distinguished from protein changes associated with heterologous protein expression. Protein spots were monitored quantitatively and qualitatively. Differentially expressed proteins were quantitatively assessed by using a t-test method with a 1% false discovery rate as a significance criterion. As determined by this criterion, 81 protein spots changed significantly between 14 and 72 h (final time) of the control fermentations (vector only). Qualitative (on-off) comparisons indicated that 20 more protein spots were present only at 14 or 72 h in the control fermentations. These changes reflected physiological responses to the culture conditions. In control and production fermentations at 72 h, 25 protein spots were significantly differentially expressed. In addition, 19 protein spots were present only in control or production fermentations at this time. The quantitative and qualitative changes were attributable to overexpression of recombinant protein. The physiological changes observed during the fermentations included the up-regulation of phosphate starvation proteins and the down-regulation of ribosomal proteins and nucleotide biosynthesis proteins. Synthesis of the stress protein phage shock protein A (PspA) was strongly correlated with synthesis of a recombinant product. This suggested that manipulation of PspA levels might improve the soluble recombinant protein yield in the periplasm for this bioprocess. Indeed, controlled coexpression of PspA during production led to a moderate, but statistically significant, improvement in the yield.",1
"Aldor, Ilana S, Krawitz, Denise C, Forrest, William, Chen, Christina, Nishihara, Julie C, Joly, John C, Champion, Kathleen M",2
Explorative multifactor approach for investigating global survival mechanisms of Campylobacter jejuni under environmental conditions.,0
"Explorative approaches such as DNA microarray experiments are becoming increasingly important in microbial research. Despite these major technical advancements, approaches to study multifactor experiments are still lacking. We have addressed this problem by using rotation testing and a novel multivariate analysis of variance (MANOVA) approach (50-50 MANOVA) to investigate interacting experimental factors in a complex experimental design. Furthermore, a new rotation testing based method was introduced to calculate false-discovery rates for each response. This novel analytical concept was used to investigate global survival mechanisms in the environment of the major food-borne pathogen C. jejuni. We simulated nongrowth environmental conditions by investigating combinations of the factors temperature (5 and 25 degrees C) and oxygen tension (anaerobic, microaerobic, and aerobic). Data were generated with DNA microarrays for information about gene expression patterns and Fourier transform infrared (FT-IR) spectroscopy to study global macromolecular changes in the cell. Microarray analyses showed that most genes were either unchanged or down regulated compared to the reference (day 0) for the conditions tested and that the 25 degrees C anaerobic condition gave the most distinct expression pattern with the fewest genes expressed. The few up-regulated genes were generally stress related and/or related to the cell envelope. We found, using FT-IR spectroscopy, that the amount of polysaccharides and oligosaccharides increased under the nongrowth survival conditions. Potential mechanisms for survival could be to down regulate most functions to save energy and to produce polysaccharides and oligosaccharides for protection against harsh environments. Basic knowledge about the survival mechanisms is of fundamental importance in preventing transmission of this bacterium through the food chain.",1
"Moen, Birgitte, Oust, Astrid, Langsrud, Øyvind, Dorrell, Nick, Marsden, Gemma L, Hinds, Jason, Kohler, Achim, Wren, Brendan W, Rudi, Knut",2
Accumulation of polyhydroxyalkanoate from styrene and phenylacetic acid by Pseudomonas putida CA-3.,0
"Pseudomonas putida CA-3 is capable of converting the aromatic hydrocarbon styrene, its metabolite phenylacetic acid, and glucose into polyhydroxyalkanoate (PHA) when a limiting concentration of nitrogen (as sodium ammonium phosphate) is supplied to the growth medium. PHA accumulation occurs to a low level when the nitrogen concentration drops below 26.8 mg/liter and increases rapidly once the nitrogen is no longer detectable in the growth medium. The depletion of nitrogen and the onset of PHA accumulation coincided with a decrease in the rate of substrate utilization and biochemical activity of whole cells grown on styrene, phenylacetic acid, and glucose. However, the efficiency of carbon conversion to PHA dramatically increased once the nitrogen concentration dropped below 26.8 mg/liter in the growth medium. When supplied with 67 mg of nitrogen/liter, the carbon-to-nitrogen (C:N) ratios that result in a maximum yield of PHA (grams of PHA per gram of carbon) for styrene, phenylacetic acid, and glucose are 28:1, 21:1, and 18:1, respectively. In cells grown on styrene and phenylacetic acid, decreasing the carbon-to-nitrogen ratio below 28:1 and 21:1, respectively, by increasing the nitrogen concentration and using a fixed carbon concentration leads to lower levels of PHA per cell and lower levels of PHA per batch of cells. Increasing the carbon-to-nitrogen ratio above 28:1 and 21:1 for cells grown on styrene and phenylacetic acid, respectively, by decreasing the nitrogen concentration and using a fixed carbon concentration increases the level of PHA per cell but results in a lower level of PHA per batch of cells. Increasing the carbon and nitrogen concentrations but maintaining the carbon-to-nitrogen ratio of 28:1 and 21:1 for cells grown on styrene and phenylacetic acid, respectively, results in an increase in the total PHA per batch of cells. The maximum yields for PHA from styrene, phenylacetic acid, and glucose are 0.11, 0.17, and 0.22 g of PHA per g of carbon, respectively.",1
"Ward, Patrick G, de Roo, Guy, O'Connor, Kevin E",2
Molecular assays for targeting human and bovine enteric viruses in coastal waters and their application for library-independent source tracking.,0
"Rapid population growth and urban development along waterways and coastal areas have led to decreasing water quality. To examine the effects of upstream anthropogenic activities on microbiological water quality, methods for source-specific testing are required. In this study, molecular assays targeting human enteroviruses (HEV), bovine enteroviruses (BEV), and human adenoviruses (HAdV) were developed and used to identify major sources of fecal contamination in the lower Altamaha River, Georgia. Two-liter grab samples were collected monthly from five tidally influenced stations between July and December 2002. Samples were analyzed by reverse transcription- and nested-PCR. PCR results were confirmed by dot blot hybridization. Eleven and 17 of the 30 surface water samples tested positive for HAdV and HEV, respectively. Two-thirds of the samples tested positive for either HEV or HAdV, and the viruses occurred simultaneously in 26% of samples. BEV were detected in 11 of 30 surface water samples. Binary logistic regression analysis showed that the presence of both human and bovine enteric viruses was not significantly related to either fecal coliform or total coliform levels. The presence of these viruses was directly related to dissolved oxygen and streamflow but inversely related to water temperature, rainfall in the 30 days preceding sampling, and chlorophyll-a concentrations. The stringent host specificity of enteric viruses makes them good library-independent indicators for identification of water pollution sources. Viral pathogen detection by PCR is a highly sensitive and easy-to-use tool for rapid assessment of water quality and fecal contamination when public health risk characterization is not necessary.",1
"Fong, Theng-Theng, Griffin, Dale W, Lipp, Erin K",2
Spatial distribution and transcriptional activity of an uncultured clade of planktonic diazotrophic gamma-proteobacteria in the Arabian sea.,0
"The spatial distribution of an uncultured clade of marine diazotrophic gamma-proteobacteria in the Arabian Sea was investigated by the development of a specific primer pair to amplify an internal fragment of nifH by PCR. These organisms were most readily detected in highly oligotrophic surface waters but could also be found in deeper waters below the nutricline. nifH transcripts originating from this clade were detected in oligotrophic surface waters and, in addition, in the deeper and the more productive near-coastal waters. The nifH sequences most closely related to the unidentified marine bacterial group are from environmental clones amplified from the Atlantic and Pacific Oceans. These findings suggest that these gamma-proteobacteria are widespread and likely to be an important component of the heterotrophic diazotrophic microbial community of the tropical and subtropical oceans.",1
"Bird, Clare, Martinez Martinez, Joaquín, O'Donnell, Anthony G, Wyman, Michael",2
Exposure to cadmium elevates expression of genes in the OxyR and OhrR regulons and induces cross-resistance to peroxide killing treatment in Xanthomonas campestris.,0
"Cadmium is an important heavy metal pollutant. For this study, we investigated the effects of cadmium exposure on the oxidative stress responses of Xanthomonas campestris, a soil and plant pathogenic bacterium. The exposure of X. campestris to low concentrations of cadmium induces cross-protection against subsequent killing treatments with either H2O2 or the organic hydroperoxide tert-butyl hydroperoxide (tBOOH), but not against the superoxide generator menadione. The cadmium-induced resistance to peroxides is due to the metal's ability to induce increased levels of peroxide stress protective enzymes such as alkyl hydroperoxide reductase (AhpC), monofunctional catalase (KatA), and organic hydroperoxide resistance protein (Ohr). Cadmium-induced resistance to H2O2 is dependent on functional OxyR, a peroxide-sensing transcription regulator. Cadmium-induced resistance to tBOOH shows a more complex regulatory pattern. The inactivation of the two major sensor-regulators of organic hydroperoxide, OxyR and OhrR, only partially inhibited cadmium-induced protection against tBOOH, suggesting that these genes do have some role in the process. However, other, as yet unknown mechanisms are involved in inducible organic hydroperoxide protection. Furthermore, we show that the cadmium-induced peroxide stress response is mediated by the metal's ability to predominately cause an increase in intracellular concentrations of organic hydroperoxide and, in part, H2O2. Analyses of various mutants of peroxide-metabolizing enzymes suggested that this increase in organic hydroperoxide levels is, at least in part, responsible for cadmium toxicity in Xanthomonas.",1
"Banjerdkij, Peerakan, Vattanaviboon, Paiboon, Mongkolsuk, Skorn",2
Diversity of oxygenase genes from methane- and ammonia-oxidizing bacteria in the Eastern Snake River Plain aquifer.,0
"PCR amplification, restriction fragment length polymorphism, and phylogenetic analysis of oxygenase genes were used for the characterization of in situ methane- and ammonia-oxidizing bacteria from free-living and attached communities in the Eastern Snake River Plain aquifer. The following three methane monooxygenase (MMO) PCR primer sets were used: A189-A682, which amplifies an internal region of both the pmoA gene of the MMO particulate form and the amoA gene of ammonia monooxygenase; A189-mb661, which specifically targets the pmoA gene; and mmoXA-mmoXB, which amplifies the mmoX gene of the MMO soluble form (sMMO). Whole-genome amplification (WGA) was used to amplify metagenomic DNA from each community to assess its applicability for generating unbiased metagenomic template DNA. The majority of sequences in each archive were related to oxygenases of type II-like methanotrophs of the genus Methylocystis. A small subset of type I sequences found only in free-living communities possessed oxygenase genes that grouped nearest to Methylobacter and Methylomonas spp. Sequences similar to that of the amoA gene associated with ammonia-oxidizing bacteria (AOB) most closely matched a sequence from the uncultured bacterium BS870 but showed no substantial alignment to known cultured AOB. Based on these functional gene analyses, bacteria related to the type II methanotroph Methylocystis sp. were found to dominate both free-living and attached communities. Metagenomic DNA amplified by WGA showed characteristics similar to those of unamplified samples. Overall, numerous sMMO-like gene sequences that have been previously associated with high rates of trichloroethylene cometabolism were observed in both free-living and attached communities in this basaltic aquifer.",1
"Erwin, Daniel P, Erickson, Issac K, Delwiche, Mark E, Colwell, Frederick S, Strap, Janice L, Crawford, Ronald L",2
Characterization of a mobile clpL gene from Lactobacillus rhamnosus.,0
"Two genes encoding ClpL ATPase proteins were identified in a probiotic Lactobacillus rhamnosus strain, E-97800. Sequence analyses revealed that the genes, designated clpL1 and clpL2, share 80% identity. The clpL2 gene showed the highest degree of identity (98.5%) to a clpL gene from Lactobacillus plantarum WCFSI, while it was not detected in three other L. rhamnosus strains studied. According to Northern analyses, the expression of clpL1 and the clpL2 were induced during heat shock by > 20- and 3-fold, respectively. The functional promoter regions were determined by primer extension analyses, and the clpL1 promoter was found to be overlapped by an inverted repeat structure identical to the conserved CIRCE element, indicating that clpL1 belongs to the HrcA regulon in L. rhamnosus. No consensus binding sites for HrcA or CtsR could be identified in the clpL2 promoter region. Interestingly, the clpL2 gene was found to be surrounded by truncated transposase genes and flanked by inverted repeat structures nearly identical to the terminal repeats of the ISLpl1 from L. plantarum HN38. Furthermore, clpL2 was shown to be mobilized during prolonged cultivation at elevated temperature. The presence of a gene almost identical to clpL2 in L. plantarum and its absence in other L. rhamnosus strains suggest that the L. rhamnosus E-97800 has acquired the clpL2 gene via horizontal transfer. No change in the stress tolerance of the ClpL2-deficient derivative of E-97800 compared to the parental strain was observed.",1
"Suokko, Aki, Savijoki, Kirsi, Malinen, Erja, Palva, Airi, Varmanen, Pekka",2
Anaerobic ammonia-oxidizing bacteria and related activity in Baltimore inner harbor sediment.,0
"The discovery of bacteria capable of anaerobic ammonia oxidation (anammox) has generated interest in understanding the activity, diversity, and distribution of these bacteria in the environment. In this study anammox activity in sediment samples obtained from the Inner Harbor of Baltimore, Md., was detected by (15)N tracer assays. Anammox-specific oligonucleotide primer sets were used to screen a Planctomycetales-specific 16S rRNA gene library generated from sediment DNA preparations, and four new anammox bacterial sequences were identified. Three of these sequences form a cohesive new branch of the anammox group, and the fourth sequence branches separately from this group. Denaturing gradient gel electrophoresis analysis of sediment incubated with anammox-specific media confirmed the presence of the four anammox-related 16S rRNA gene sequences. Evidence for the presence of anammox bacteria in Inner Harbor sediment was also obtained by using an anammox-specific probe in fluorescence in situ hybridization studies. To our knowledge, this is the first report of anammox activity and related bacterial 16S rRNA gene sequences from the Chesapeake Bay basin area, and the results suggest that this pathway plays an important role in the nitrogen cycle of this estuarine environment. Furthermore, the presence of these bacteria and their activity in sediment strengthen the contention that anammox-related Plactomycetales are globally distributed.",1
"Tal, Yossi, Watts, Joy E M, Schreier, Harold J",2
Evidence for involvement of an electron shuttle in electricity generation by Geothrix fermentans.,0
"In experiments performed using graphite electrodes poised by a potentiostat (+200 mV versus Ag/AgCl) or in a microbial fuel cell (with oxygen as the electron acceptor), the Fe(III)-reducing organism Geothrix fermentans conserved energy to support growth by coupling the complete oxidation of acetate to reduction of a graphite electrode. Other organic compounds, such as lactate, malate, propionate, and succinate as well as components of peptone and yeast extract, were utilized for electricity production. However, electrical characteristics and the results of shuttling assays indicated that unlike previously described electrode-reducing microorganisms, G. fermentans produced a compound that promoted electrode reduction. This is the first report of complete oxidation of organic compounds linked to electrode reduction by an isolate outside of the Proteobacteria.",1
"Bond, Daniel R, Lovley, Derek R",2
Elimination of botulinum neurotoxin (BoNT) type B from drinking water by small-scale (personal-use) water purification devices and detection of BoNT in water samples.,0
"Seven small-scale drinking water purification devices were evaluated for their capacity to eliminate botulinum neurotoxin (BoNT) type B from drinking water. Influent water inoculated with toxic Clostridium botulinum cultures and effluent purified water samples were tested for the presence of BoNT by using a standard mouse bioassay and two commercial rapid enzyme immunoassays (EIAs). The water purification devices based on filtration through ceramic or membrane filters with a pore size of 0.2 to 0.4 microm or irradiation from a low-pressure UV-lamp (254 nm) failed to remove BoNT from raw water (reduction of < 0.1 log10 units). A single device based on reverse osmosis was capable of removing the BoNT to a level below the detection limit of the mouse bioassay (reduction of > 2.3 log10 units). The rapid EIAs intended for the detection of BoNT from various types of samples failed to detect BoNT from aqueous samples containing an estimated concentration of BoNT of 396,000 ng/liter.",1
"Hörman, Ari, Nevas, Mari, Lindström, Miia, Hänninen, Marja-Liisa, Korkeala, Hannu",2
Cytotoxicity potential and genotypic characterization of Escherichia coli isolates from environmental and food sources.,0
"The presence of Escherichia coli isolates in the environment is a potential source of contamination of food and water supplies. Moreover, these isolates may harbor virulence genes that can be a source of new forms of pathogenic strains. Here, using multiplex PCR, we examined the presence of virulence gene markers (stx1, stx2, eaeA, hlyA) in 1,698 environmental isolates of E. coli and 81 isolates from food and clinical sources. The PCR analysis showed that approximately 5% (79 of 1,698) of the total environmental isolates and 96% (79 of 81) of the food and clinical isolates were positive for at least one of the genes. Of the food and clinical isolates, 84% (68 of 81 isolates) were positive for all four genes. Of the subset of environmental isolates chosen for further analysis, 16% (13 of 79 isolates) were positive for stx2 and 84% (66 of 79 isolates) were positive for eaeA; 16 of the latter strains were also positive for hlyA. The pathogenic potentials of 174 isolates (81 isolates from food and clinical sources and 93 isolates from environmental sources) were tested by using a cytotoxicity assay based on lactate dehydrogenase release from Vero cells. In general, 97% (79 of 81) of the food and clinical isolates and 41% (39 of 93) of the environmental isolates exhibited positive cytotoxicity. High cytotoxicity values correlated to the presence of stx genes. The majority of hly-positive but stx-negative environmental isolates also exhibited a certain degree of cytotoxicity. Isolates were also tested for sorbitol utilization and were genotyped by ribotyping and by repetitive extragenic palindromic PCR (REP-PCR) as potential means of quickly identifying virulent strains from the environment, but none of these methods could be used to distinguish cytotoxic environmental isolates. Only 31% of the isolates were negative for sorbitol fermentation, and none of the isolates had common ribotypes or REP-PCR fingerprints. This study suggests that overall higher cytotoxicity values correlated with the production of stx genes, and the majority of hly-positive but stx-negative environmental isolates also exhibited a certain degree of cytotoxicity. This study demonstrated that there is widespread distribution of potentially virulent E. coli strains in the environment that may be a cause of concern for human health.",1
"Maldonado, Yadilka, Fiser, Jennifer C, Nakatsu, Cindy H, Bhunia, Arun K",2
Opposite enantioselectivities of two phenotypically and genotypically similar strains of Pseudomonas frederiksbergensis in bacterial whole-cell sulfoxidation.,0
"Soil samples were screened to select microorganisms with the capability to oxidize organic sulfides into the corresponding sulfoxides with differential enantioselectivities. Several bacterial strains that preferentially produced the S-configured sulfoxide enantiomer were isolated. Surprisingly, one bacterial strain, genotypically and phenotypically characterized as Pseudomonas frederiksbergensis, selectively gave the R enantiomer. The finding that two apparently identical organisms displayed opposite enantioselectivities is novel for non-genetically modified organisms.",1
"Adam, Waldemar, Heckel, Frank, Saha-Möller, Chantu R, Taupp, Marcus, Meyer, Jean-Marie, Schreier, Peter",2
"Improved assessment of denitrifying, N2-fixing, and total-community bacteria by terminal restriction fragment length polymorphism analysis using multiple restriction enzymes.",0
"A database of terminal restriction fragments (tRFs) of the 16S rRNA gene was set up utilizing 13 restriction enzymes and 17,327 GenBank sequences. A computer program, termed TReFID, was developed to allow identification of any of these 17,327 sequences by means of polygons generated from the specific tRFs of each bacterium. The TReFID program complements and exceeds in its data content the Web-based phylogenetic assignment tool recently described by A. D. Kent, D. J. Smith, B. J. Benson, and E. W. Triplett (Appl. Environ. Microb. 69:6768-6766, 2003). The method to identify bacteria is different, as is the region of the 16S rRNA gene employed in the present program. For the present communication the software of the tRF profiles has also been extended to allow screening for genes coding for N2 fixation (nifH) and denitrification (nosZ) in any bacterium or environmental sample. A number of controls were performed to test the reliability of the TReFID program. Furthermore, the TReFID program has been shown to permit the analysis of the bacterial population structure of bacteria by means of their 16S rRNA, nifH, and nosZ gene content in an environmental habitat, as exemplified for a sample from a forest soil. The use of the TReFID program reveals that noncultured denitrifying and dinitrogen-fixing bacteria might play a more dominant role in soils than believed hitherto.",1
"Rösch, Christopher, Bothe, Hermann",2
Heat inactivation of Mycobacterium avium subsp. paratuberculosis in milk.,0
"The effectiveness of pasteurization and the concentration of Mycobacterium avium subsp. paratuberculosis in raw milk have been identified in quantitative risk analysis as the most critical factors influencing the potential presence of viable Mycobacterium paratuberculosis in dairy products. A quantitative assessment of the lethality of pasteurization was undertaken using an industrial pasteurizer designed for research purposes with a validated Reynolds number of 62,112 and flow rates of 3,000 liters/h. M. paratuberculosis was artificially added to raw whole milk, which was then homogenized, pasteurized, and cultured, using a sensitive technique capable of detecting one organism per 10 ml of milk. Twenty batches of milk containing 10(3) to 10(4) organisms/ml were processed with combinations of three temperatures of 72, 75, and 78 degrees C and three time intervals of 15, 20, and 25 s. Thirty 50-ml milk samples from each processed batch were cultured, and the logarithmic reduction in M. paratuberculosis organisms was determined. In 17 of the 20 runs, no viable M. paratuberculosis organisms were detected, which represented > 6-log10 reductions during pasteurization. These experiments were conducted with very heavily artificially contaminated milk to facilitate the measurement of the logarithmic reduction. In three of the 20 runs of milk, pasteurized at 72 degrees C for 15 s, 75 degrees C for 25 s, and 78 degrees C for 15 s, a few viable organisms (0.002 to 0.004 CFU/ml) were detected. Pasteurization at all temperatures and holding times was found to be very effective in killing M. paratuberculosis, resulting in a reduction of > 6 log10 in 85% of runs and > 4 log10 in 14% of runs.",1
"McDonald, Wendy L, O'Riley, Kimberly J, Schroen, Christopher J, Condron, Robin J",2
Diversity of transcripts of nitrite reductase genes (nirK and nirS) in rhizospheres of grain legumes.,0
"Transcription of the nirK and nirS genes coding for dissimilatory bacterial nitrite reductases was analyzed by reverse transcription PCR (RT-PCR) of mRNA isolated from rhizosphere samples of three economically important grain legumes at maturity: Vicia faba, Lupinus albus, and Pisum sativum. The nirK gene and transcripts could be detected in all the rhizosphere samples. In contrast, nirS could not be detected. Sampling variations were analyzed by comparing denaturing gradient gel electrophoresis profiles derived from nirK RT-PCR products. High similarity was observed between the replicates, and so one representative product per legume was cloned. Clones with the correct insert size were screened by restriction fragment length polymorphism by using the restriction enzyme MspI. The clones could be distributed into 12 different patterns. Patterns 1, 3, 4, 5, and 7 were common in clone libraries of the three rhizosphere types under study. Patterns 2, 9, 10, and 11 were absent from Pisum rhizospheres, while patterns 6, 8, and 12 were absent from the Vicia library. Pattern 1, which was the most dominant in the Vicia and Lupinus libraries, constituted about 25% of all clones. The Lupinus library had clones representing all 12 patterns, indicating it to be the most diverse among the three. Clones representative of each pattern were sequenced. All patterns grouped together forming a distinct cluster, which was divergent from previously described nirK sequences in the database. The study revealed a hitherto unknown diversity of denitrifiers in legume rhizospheres. A plant-dependent rhizosphere effect on the transcripts of a gene was evident.",1
"Sharma, Shilpi, Aneja, Manish Kumar, Mayer, Jochen, Munch, Jean Charles, Schloter, Michael",2
Culture-dependent and -independent methods to investigate the microbial ecology of Italian fermented sausages.,0
"In this study, the microbial ecology of three naturally fermented sausages produced in northeast Italy was studied by culture-dependent and -independent methods. By plating analysis, the predominance of lactic acid bacteria populations was pointed out, as well as the importance of coagulase-negative cocci. Also in the case of one fermentation, the fecal enterocci reached significant counts, highlighting their contribution to the particular transformation process. Yeast counts were higher than the detection limit (> 100 CFU/g) in only one fermented sausage. Analysis of the denaturing gradient gel electrophoresis (DGGE) patterns and sequencing of the bands allowed profiling of the microbial populations present in the sausages during fermentation. The bacterial ecology was mainly characterized by the stable presence of Lactobacillus curvatus and Lactobacillus sakei, but Lactobacillus paracasei was also repeatedly detected. An important piece of evidence was the presence of Lactococcus garvieae, which clearly contributed in two fermentations. Several species of Staphylococcus were also detected. Regarding other bacterial groups, Bacillus sp., Ruminococcus sp., and Macrococcus caseolyticus were also identified at the beginning of the transformations. In addition, yeast species belonging to Debaryomyces hansenii, several Candida species, and Willopsis saturnus were observed in the DGGE gels. Finally, cluster analysis of the bacterial and yeast DGGE profiles highlighted the uniqueness of the fermentation processes studied.",1
"Rantsiou, Kalliopi, Urso, Rosalinda, Iacumin, Lucilla, Cantoni, Carlo, Cattaneo, Patrizia, Comi, Giuseppe, Cocolin, Luca",2
Agrobacterium tumefaciens-mediated transformation of Aspergillus fumigatus: an efficient tool for insertional mutagenesis and targeted gene disruption.,0
"Agrobacterium tumefaciens was used to transform Aspergillus fumigatus by either random or site-directed integration of transforming DNA (T-DNA). Random mutagenesis via Agrobacterium tumefaciens-mediated transformation (ATMT) was accomplished with T-DNA containing a hygromycin resistance cassette. Cocultivation of A. fumigatus conidia and Agrobacterium (1:10 ratio) for 48 h at 24 degrees C resulted in high frequencies of transformation (> 100 transformants/10(7) conidia). The majority of transformants harbored a randomly integrated single copy of T-DNA and were mitotically stable. We chose alb1, a polyketide synthase gene, as the target gene for homologous integration because of the clear phenotype difference between the white colonies of Deltaalb1 mutant strains and the bluish-green colonies of wild-type strains. ATMT with a T-DNA-containing alb1 disruption construct resulted in 66% albino transformants. Southern analysis revealed that 19 of the 20 randomly chosen albino transformants (95%) were disrupted by homologous recombination. These results suggest that ATMT is an efficient tool for transformation, random insertional mutagenesis, and gene disruption in A. fumigatus.",1
"Sugui, Janyce A, Chang, Yun C, Kwon-Chung, K J",2
Folate cross-feeding supports symbiotic homoacetogenic spirochetes.,0
"Treponema primitia, an H2-consuming CO2-reducing homoacetogenic spirochete in termite hindguts, requires an exogenous source of folate for growth. Tetrahydrofolate (THF) acts as a C1 carrier in CO2-reductive acetogenesis, a microbially mediated process important to the carbon and energy requirements of termites. To examine the hypothesis that other termite gut microbes probably supply some form of folate to T. primitia in situ, we used a bioassay to screen for and isolate folate-secreting bacteria from hindguts of Zootermopsis angusticollis, which is the host of T. primitia. Based on morphology, physiology, and 16S rRNA gene sequences, the major folate secretors were identified as strains of Lactococcus lactis and Serratia grimesii. During growth, these isolates secreted 5-formyl-THF at levels up to 146 ng/ml, and their cell-free culture fluids satisfied the folate requirement of T. primitia strains in vitro. Analysis of Z. angusticollis hindgut fluid revealed that 5-formyl-THF was the only detectable folate compound and occurred at an in situ concentration (1.3 mug/ml) which was more than sufficient to support the growth of T. primitia. These results imply that cross-feeding of 5-formyl-THF by other community members is important for growth of symbiotic hindgut spirochetes and thus termite nutrition and survival.",1
"Graber, Joseph R, Breznak, John A",2
Production of novel rapamycin analogs by precursor-directed biosynthesis.,0
"The natural product rapamycin, produced during fermentation by Streptomyces hygroscopicus, is known for its potent antifungal, immunosuppressive, and anticancer activities. During rapamycin biosynthesis, the amino acid l-pipecolate is incorporated into the rapamycin molecule. We investigated the use of precursor-directed biosynthesis to create new rapamycin analogs by substitution of unusual l-pipecolate analogs in place of the normal amino acid. Our results suggest that the l-pipecolate analog (+/-)-nipecotic acid inhibits the biosynthesis of l-pipecolate, thereby limiting the availability of this molecule for rapamycin biosynthesis. We used (+/-)-nipecotic acid in our precursor-directed biosynthesis studies to reduce l-pipecolate availability and thereby enhance the incorporation of other pipecolate analogs into the rapamycin molecule. We describe here the use of this method for production of two new sulfur-containing rapamycin analogs, 20-thiarapamycin and 15-deoxo-19-sulfoxylrapamycin, and report measurement of their binding to FKBP12.",1
"Ritacco, Frank V, Graziani, Edmund I, Summers, Mia Y, Zabriskie, T Mark, Yu, Ker, Bernan, Valerie S, Carter, Guy T, Greenstein, Michael",2
"Expression of abrB310 and SinR, and effects of decreased abrB310 expression on the transition from acidogenesis to solventogenesis, in Clostridium acetobutylicum ATCC 824.",0
"The transcription factors sinR and abrB are involved in the control of sporulation initiation in Bacillus subtilis. We identified a single homologue to sinR and three highly similar homologues to abrB, designated abrB310, abrB1941, and abrB3647, in Clostridium acetobutylicum ATCC 824. Using reporter vectors, we showed that the promoters of abrB1941 and abrB3647 were not active under the growth conditions tested. The abrB310 promoter was strongly active throughout growth and exhibited a transient elevation of expression at the onset of solventogenesis. Primer extension assays showed that two transcripts of abrB310 and a single, extremely weak transcript for sinR are expressed. Potential -35 and -10 consensus motifs are readily identifiable surrounding the transcription start sites of abrB310 and sinR, with a single putative 0A box present within the promoter of abrB310. In strains of C. acetobutylicum transformed with plasmids to elevate sinR expression or decrease sinR expression, no significant differences in growth or in acid or solvent production were observed compared to the control strains. In C. acetobutylicum strain 824(pAS310), which expressed an antisense RNA construct targeted against abrB310, the acids acetate and butyrate accumulated to approximately twice the normal concentration. This accumulation corresponded to a delay and decrease in acetone and butanol production. It was also found that sporulation in strain 824(pAS310) was delayed but that the morphology of sporulating cells and spores was normal. Based upon these observations, we propose that abrB310 may act as a regulator at the transition between acidogenic and solventogenic growth.",1
"Scotcher, Miles C, Rudolph, Frederick B, Bennett, George N",2
Rapid and sensitive detection of noroviruses by using TaqMan-based one-step reverse transcription-PCR assays and application to naturally contaminated shellfish samples.,0
"Noroviruses (NoV), which are members of the family Caliciviridae, are the most important cause of outbreaks of acute gastroenteritis worldwide and are commonly found in shellfish grown in polluted waters. In the present study, we developed broadly reactive one-step TaqMan reverse transcription (RT)-PCR assays for the detection of genogroup I (GI) and GII NoV in fecal samples, as well as shellfish samples. The specificity and sensitivity of all steps of the assays were systematically evaluated, and in the final format, the monoplex assays were validated by using RNA extracted from a panel of 84 stool specimens, which included NoV strains representing 19 different genotypes (7 GI, 11 GII, and 1 GIV strains). The assays were further validated with 38 shellfish cDNA extracts previously tested by nested PCR. Comparison with a recently described real-time assay showed that our assay had significantly higher sensitivity and was at least as sensitive as the nested PCR. For stool specimens, a one-step duplex TaqMan RT-PCR assay performed as well as individual genogroup-specific monoplex assays. All other enteric viruses examined were negative, and no cross-reaction between genogroups was observed. These TaqMan RT-PCR assays provide rapid (less than 90 min), sensitive, and reliable detection of NoV and should prove to be useful for routine monitoring of both clinical and shellfish samples.",1
"Jothikumar, Narayanan, Lowther, James A, Henshilwood, Kathleen, Lees, David N, Hill, Vincent R, Vinjé, Jan",2
Rehydration of the lichen Ramalina lacera results in production of reactive oxygen species and nitric oxide and a decrease in antioxidants.,0
"Lichens are slow-growing associations of fungi and unicellular green algae or cyanobacteria. They are poikilohydric organisms whose lifestyle in many cases consists of alternating periods of desiccation, with low metabolic activity, and hydration, which induces increase in their metabolism. Lichens have apparently adapted to such extreme transitions between desiccation and rehydration, but the mechanisms that govern these adaptations are still poorly understood. In this study, the effect of rehydration on the production of reactive oxygen species and nitric oxide as well as low-molecular-weight antioxidants was investigated with the lichen Ramalina lacera. Rehydration of R. lacera resulted in the initiation of and a rapid increase in photosynthetic activity. Recovery of photosynthesis was accompanied by bursts of intracellular production of reactive oxygen species and nitric oxide. Laser-scanning confocal microscopy using dichlorofluorescein fluorescence revealed that formation of reactive oxygen species following rehydration was associated with both symbiotic partners of the lichen. The rate and extent of reactive oxygen species production were similar in the light and in the dark, suggesting a minor contribution of photosynthesis. Diaminofluorescein fluorescence, indicating nitric oxide formation, was detected only in fungal hyphae. Activities associated with rehydration did not have a deleterious effect on membrane integrity as assessed by measurement of electrolyte leakage, but water-soluble low-molecular-weight antioxidants decreased significantly.",1
"Weissman, Lior, Garty, Jacob, Hochman, Ayala",2
Illness and amputation in the eighteenth century: the case of Sir James Lowther (1673-1755).,0
"Sir james Lowther of Whitehaven (1673-1755) suffered from gout, and eventually had his right leg amputated in 1750. He also experienced other serious illnesses. Surviving correspondence between Lowther, in London, and his Whitehaven steward, contain graphic accounts of his health, particularly the serious illness and amputation of 1750. From these letters, and a document surviving in the British Museum describing an attack of erysipelis in 1742, a short, documentary account of Lowther's medical history has been compiled. If for no other reason, he deserves to be remembered for surviving an amputation without anaesthetic, at the age of seventy-seven.",1
"Beckett, J V, Lowther, J",2
Further information on the prehistoric representations of human hands in the cave of Gargas.,0
"This paper amends and adds recent information to Paul A. Janssens' earlier article on the prehistoric paintings of human hands in the cave of Gargas, France.1 Possible diagnoses for the deficiencies found in many of the hand pictures, and some non-medical theories of explanation, are reviewed. It is concluded that the hands used as stencils were mutilated and that the images were deliberately placed within the cave and were not the by-products of some other activity.",1
"Hooper, A",2
Modulation of the cell growth regulator mTOR by Epstein-Barr virus-encoded LMP2A.,0
"Control of translation initiation is one means by which cells regulate growth and proliferation, with components of the protein-synthesizing machinery having oncogenic potential. Expression of latency protein LMP2A by the human tumor virus Epstein-Barr virus (EBV) activates phosphatidylinositol 3-kinase/Akt located upstream of an essential mediator of growth signals, mTOR (mammalian target of rapamycin). We show that mTOR is activated by expression of LMP2A in carcinoma cells, leading to wortmannin- and rapamycin-sensitive inhibition of the negative regulator of translation, eukaryotic initiation factor 4E-binding protein 1, and increased c-Myc protein translation. Intervention by this DNA tumor virus in cellular translational controls is likely to be an integral component of EBV tumorigenesis.",1
"Moody, Cary A, Scott, Rona S, Amirghahari, Nazanin, Nathan, Cherie-Ann, Young, Lawrence S, Dawson, Chris W, Sixbey, John W",2
RhoA signaling is required for respiratory syncytial virus-induced syncytium formation and filamentous virion morphology.,0
"Respiratory syncytial virus (RSV) is an important human pathogen that can cause severe and life-threatening respiratory infections in infants, the elderly, and immunocompromised adults. RSV infection of HEp-2 cells induces the activation of RhoA, a small GTPase. We therefore asked whether RhoA signaling is important for RSV replication or syncytium formation. The treatment of HEp-2 cells with Clostridium botulinum C3, an enzyme that ADP-ribosylates and specifically inactivates RhoA, inhibited RSV-induced syncytium formation and cell-to-cell fusion, although similar levels of PFU were released into the medium and viral protein expression levels were equivalent. Treatment with another inhibitor of RhoA signaling, the Rho kinase inhibitor Y-27632, yielded similar results. Scanning electron microscopy of C3-treated infected cells showed reduced numbers of single blunted filaments, in contrast to the large clumps of long filaments in untreated infected cells. These data suggest that RhoA signaling is associated with filamentous virus morphology, cell-to-cell fusion, and syncytium formation but is dispensable for the efficient infection and production of infectious virus in vitro. Next, we developed a semiquantitative method to measure spherical and filamentous virus particles by using sucrose gradient velocity sedimentation. Fluorescence and transmission electron microscopy confirmed the separation of spherical and filamentous forms of infectious virus into two identifiable peaks. The C3 treatment of RSV-infected cells resulted in a shift to relatively more spherical virions than those from untreated cells. These data suggest that viral filamentous protuberances characteristic of RSV infection are associated with RhoA signaling, are important for filamentous virion morphology, and may play a role in initiating cell-to-cell fusion.",1
"Gower, Tara L, Pastey, Manoj K, Peeples, Mark E, Collins, Peter L, McCurdy, Lewis H, Hart, Timothy K, Guth, Alex, Johnson, Teresa R, Graham, Barney S",2
"Transmission barriers for bovine, ovine, and human prions in transgenic mice.",0
"Transgenic (Tg) mice expressing full-length bovine prion protein (BoPrP) serially propagate bovine spongiform encephalopathy (BSE) prions without posing a transmission barrier. These mice also posed no transmission barrier for Suffolk sheep scrapie prions, suggesting that cattle may be highly susceptible to some sheep scrapie strains. Tg(BoPrP) mice were also found to be susceptible to prions from humans with variant Creutzfeldt-Jakob disease (CJD); on second passage in Tg(BoPrP) mice, the incubation times shortened by 30 to 40 days. In contrast, Tg(BoPrP) mice were not susceptible to sporadic, familial, or iatrogenic CJD prions. While the conformational stabilities of bovine-derived and Tg(BoPrP)-passaged BSE prions were similar, the stability of sheep scrapie prions was higher than that found for the BSE prions but lower if the scrapie prions were passaged in Tg(BoPrP) mice. Our findings suggest that BSE prions did not arise from a sheep scrapie strain like the one described here; rather, BSE prions may have arisen spontaneously in a cow or by passage of a scrapie strain that maintains its stability upon passage in cattle. It may be possible to distinguish BSE prions from scrapie strains in sheep by combining conformational stability studies with studies using novel Tg mice expressing a chimeric mouse-BoPrP gene. Single-amino-acid substitutions in chimeric PrP transgenes produced profound changes in incubation times that allowed us to distinguish prions causing BSE from those causing scrapie.",1
"Scott, Michael R, Peretz, David, Nguyen, Hoang-Oanh B, Dearmond, Stephen J, Prusiner, Stanley B",2
Binding and transfer of human immunodeficiency virus by DC-SIGN+ cells in human rectal mucosa.,0
"The role of DC-SIGN on human rectal mucosal dendritic cells is unknown. Using highly purified human rectal mucosal DC-SIGN+ cells and an ultrasensitive real-time reverse transcription-PCR assay to quantify virus binding, we found that HLA-DR+/DC-SIGN+ cells can bind and transfer more virus than the HLA-DR+/DC-SIGN- cells. Greater than 90% of the virus bound to total mucosal mononuclear cells (MMCs) was accounted for by the DC-SIGN+ cells, which comprise only 1 to 5% of total MMCs. Significantly, anti-DC-SIGN antibodies blocked 90% of the virus binding when more-physiologic amounts of virus inoculum were used. DC-SIGN expression in the rectal mucosa was significantly correlated with the interleukin-10 (IL-10)/IL-12 ratio (r = 0.58, P < 0.002; n = 26) among human immunodeficiency virus (HIV)-positive patients. Ex vivo and in vitro data implicate the role of IL-10 in upregulating DC-SIGN expression and downregulating expression of the costimulatory molecules CD80/CD86. Dendritic cells derived from monocytes (MDDCs) in the presence of IL-10 render the MDDCs less responsive to maturation stimuli, such as lipopolysaccharide and tumor necrosis factor alpha, and migration to the CCR7 ligand macrophage inflammatory protein 3beta. Thus, an increased IL-10 environment could render DC-SIGN(+) cells less immunostimulatory and migratory, thereby dampening an effective immune response. DC-SIGN and the IL-10/IL-12 axis may play significant roles in the mucosal transmission and pathogenesis of HIV type 1.",1
"Gurney, Kevin B, Elliott, Julie, Nassanian, Hoorig, Song, Carol, Soilleux, Elizabeth, McGowan, Ian, Anton, Peter A, Lee, Benhur",2
"Synthesis, assembly, and processing of the Env ERVWE1/syncytin human endogenous retroviral envelope.",0
"Syncytin is a fusogenic protein involved in the formation of the placental syncytiotrophoblast layer. This protein is encoded by the envelope gene of the ERVWE1 proviral locus belonging to the human endogenous retrovirus W (HERV-W) family. The HERV-W infectious ancestor entered the primate lineage 25 to 40 million years ago. Although the syncytin fusion property has been clearly demonstrated, little is known about this cellular protein maturation process with respect to classical infectious retrovirus envelope proteins. Here we show that the cellular syncytin protein is synthesized as a glycosylated gPr73 precursor cleaved into two mature proteins, a gp50 surface subunit (SU) and a gp24 transmembrane subunit (TM). These SU and TM subunits are found associated as homotrimers. The intracytoplasmic tail is critical to the fusogenic phenotype, although its cleavage requirements seem to have diverged from those of classical retroviral maturation.",1
"Cheynet, V, Ruggieri, A, Oriol, G, Blond, J-L, Boson, B, Vachot, L, Verrier, B, Cosset, F-L, Mallet, F",2
Scavenger receptor class B type I and hepatitis C virus infection of primary tupaia hepatocytes.,0
"Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide. The study of early steps during HCV infection has been hampered by the lack of suitable in vitro or in vivo models. Primary Tupaia hepatocytes (PTH) have been shown to be susceptible to HCV infection in vitro and in vivo. Human scavenger receptor class B type I (SR-BI) represents an HCV receptor candidate mediating the cellular binding of E2 glycoprotein to HepG2 hepatoma cells. However, the function of SR-BI for viral infection of hepatocytes is unknown. In this study, we used PTH to assess the functional role of SR-BI as a putative HCV receptor. Sequence analysis of cloned tupaia SR-BI revealed a high homology between tupaia and human SR-BI. Transfection of CHO cells with human or tupaia SR-BI but not mouse SR-BI cDNA resulted in cellular E2 binding, suggesting that E2-binding domains between human and tupaia SR-BI are highly conserved. Preincubation of PTH with anti-SR-BI antibodies resulted in marked inhibition of E2 or HCV-like particle binding. However, anti-SR-BI antibodies were not able to block HCV infection of PTH. In conclusion, our results demonstrate that SR-BI represents an important cell surface molecule for the binding of the HCV envelope to hepatocytes and suggest that other or additional cell surface molecules are required for the initiation of HCV infection. Furthermore, the structural and functional similarities between human and tupaia SR-BI indicate that PTH represent a useful model system to characterize the molecular interaction of the HCV envelope and SR-BI on primary hepatocytes.",1
"Barth, Heidi, Cerino, Raffaele, Arcuri, Mirko, Hoffmann, Marco, Schürmann, Peter, Adah, Mohammed I, Gissler, Bettina, Zhao, Xiping, Ghisetti, Valeria, Lavezzo, Bruna, Blum, Hubert E, von Weizsäcker, Fritz, Vitelli, Alessandra, Scarselli, Elisa, Baumert, Thomas F",2
Pathological prion protein in the tongues of sheep infected with naturally occurring scrapie.,0
"Tongue involvement by prion spreading was shown to be a common outcome after oral or intracranial experimental challenge with scrapie and transmissible mink encephalopathy sources in rodent models. It is also known that bovine spongiform encephalopathy, which is pathogenic for humans, is experimentally transmissible to sheep and can lead to a disease indistinguishable from scrapie. A recent European Food Safety Authority opinion recommended research into PrPsc accumulation in the tongues of ruminants. We report on the detection of PrPsc in the tongues of seven scrapie-infected sheep by immunohistochemistry and Western blotting.",1
"Casalone, Cristina, Corona, Cristiano, Crescio, Maria Ines, Martucci, Francesca, Mazza, Maria, Ru, Giuseppe, Bozzetta, Elena, Acutis, Pier Luigi, Caramelli, Maria",2
"The common viral insertion site Evi12 is located in the 5'-noncoding region of Gnn, a novel gene with enhanced expression in two subclasses of human acute myeloid leukemia.",0
"The leukemia and lymphoma disease locus Evi12 was mapped to the noncoding region of a novel gene, Gnn (named for Grp94 neighboring nucleotidase), that is located immediately upstream of the Grp94/Tra1 gene on mouse chromosome 10. The Gnn gene is conserved in mice and humans. Expression of fusion constructs between GFP and Gnn cDNA isoforms in HEK-293 cells showed that Gnn proteins are located mainly in the cytoplasm. Immunoblotting experiments demonstrated the presence of multiple Gnn protein isoforms in most organs, with the lowest levels of expression of the protein detected in bone marrow and spleen. The Evi12-containing leukemia cell line NFS107 showed high levels of expression of a approximately 150-kDa Gnn isoform (Gnn107) that was not observed in control cell lines. Overexpression may be due to the viral insertion in Evi12. The Gnn107 protein is probably encoded by a Gnn cDNA isoform that is expressed exclusively in NFS107 cells and that includes sequences of TU12B1-TY, a putative protein with homology to 5'-nucleotidase enzymes. Interestingly, using Affymetrix gene expression data of a cohort of 285 patients with acute myeloid leukemia (AML), we found that GNN/TU12B1-TY expression was specifically increased in two AML clusters. One cluster consisted of all AML patients with a t(8;21) translocation, and the second cluster consisted of AML patients with a normal karyotype carrying a FLT3 internal tandem duplication. These findings suggest that we identified a novel proto-oncogene that may be causally linked to certain types of human leukemia.",1
"van den Akker, Eric, Vankan-Berkhoudt, Yolanda, Valk, Peter J M, Löwenberg, Bob, Delwel, Ruud",2
Memory T-cell response to rotavirus detected with a gamma interferon enzyme-linked immunospot assay.,0
"Measurements of serum-neutralizing antibody and anti-rotavirus immunoglobulin A (IgA) are the current standard for assessing immune responses following rotavirus vaccination. However, there is ongoing debate as to whether antibody titers correlate with protection against rotavirus gastroenteritis. Children recovering from rotavirus gastroenteritis have increased gamma interferon release from cultured peripheral blood mononuclear cells (PBMCs), suggesting that cell-mediated immunity (CMI) may play a role in viral clearance and protection from subsequent gastroenteritis. We have developed a gamma interferon enzyme-linked immunospot (ELISPOT) assay for evaluation of CMI responses to rotavirus using frozen PBMCs obtained from healthy adults. Responses to three different rotavirus antigen types were analyzed-a peptide pool based on the human VP6 sequence; reassortant human:bovine vaccine strains; and cell culture-adapted (CCA) human G1, G2, G3, G4, and bovine (WC3) G6 strains. The reassortant strains consist of a bovine WC3 genome background expressing the human rotavirus surface proteins VP7 (G1, G2, G3, or G4) or VP4 (P1). Responses to titrations of the peptide pool as well as CCA and reassortant strains were assessed. Gamma interferon ELISPOT responses were similar for CCA and reassortant strains, whether live or UV inactivated, and when tested either individually or pooled. For most subjects, responses to the VP6 peptide pool positively correlated with responses to CCA and reassortant strains. Cell depletion studies indicate the memory responses detected with these frozen adult PBMCs were primarily due to the CD4+ T-cell population. This gamma interferon ELISPOT assay provides a new tool to apply in clinical studies for the characterization of natural or vaccine-induced CMI to rotavirus.",1
"Kaufhold, Robin M, Field, Jodie A, Caulfield, Michael J, Wang, Su, Joseph, Heather, Wooters, Melissa A, Green, Tina, Clark, H Fred, Krah, David, Smith, Jeffrey G",2
"Gamma interferon-dependent, noncytolytic clearance of sindbis virus infection from neurons in vitro.",0
"Due to the nonrenewable nature of neurons, recovery from viral infection of the central nervous system requires noncytopathic mechanisms for control of virus replication. Recovery from alphavirus encephalitis can occur without apparent neurological damage through the effects of antibody and gamma interferon (IFN-gamma). To establish an in vitro cell culture system that will allow the study of mechanisms of IFN-gamma-mediated control of Sindbis virus (SINV) replication in neurons, we have characterized the susceptibility to SINV infection and IFN-gamma responsiveness of two neuronal cell lines that can be differentiated in vitro: CSM14.1, a rat nigral cell line, and NSC34, a mouse motor neuron cell line. Undifferentiated CSM14.1 and NSC34 cells were permissive for SINV and susceptible to virus-induced cell death. With differentiation, CSM14.1 cells reduced virus replication and became progressively resistant to virus-induced cell death, resulting in prolonged virus replication. NSC34 cells did not differentiate completely and became only partially resistant to SINV infection. Both CSM14.1 and NSC34 cells responded to pretreatment with IFN-gamma by decreasing SINV replication. Differentiated CSM14.1 cells treated 24 h after infection with IFN-gamma responded with increased cell viability and clearance of infectious virus. IFN-gamma treatment sequentially altered the ratio of genomic to subgenomic viral RNA synthesis, promoted recovery of cellular protein synthesis, reduced viral protein synthesis, and inhibited viral RNA transcription within 24 h after treatment. We conclude that CSM14.1 cells provide an excellent model for the study of IFN-gamma-mediated noncytolytic clearance of SINV from mature neurons.",1
"Burdeinick-Kerr, Rebeca, Griffin, Diane E",2
Structure and assembly of a T=1 virus-like particle in BK polyomavirus.,0
"In polyomaviruses the pentameric capsomers are interlinked by the long C-terminal arm of the structural protein VP1. The T=7 icosahedral structure of these viruses is possible due to an intriguing adaptability of this linker arm to the different local environments in the capsid. To explore the assembly process, we have compared the structure of two virus-like particles (VLPs) formed, as we found, in a calcium-dependent manner by the VP1 protein of human polyomavirus BK. The structures were determined using electron cryomicroscopy (cryo-EM), and the three-dimensional reconstructions were interpreted by atomic modeling. In the small VP1 particle, 26.4 nm in diameter, the pentameric capsomers form an icosahedral T=1 surface lattice with meeting densities at the threefold axes that interlinked three capsomers. In the larger particle, 50.6 nm in diameter, the capsomers form a T=7 icosahedral shell with three unique contacts. A folding model of the BKV VP1 protein was obtained by alignment with the VP1 protein of simian virus 40 (SV40). The model fitted well into the cryo-EM density of the T=7 particle. However, residues 297 to 362 of the C-terminal arm had to be remodeled to accommodate the higher curvature of the T=1 particle. The loops, before and after the C-terminal short helix, were shown to provide the hinges that allowed curvature variation in the particle shell. The meeting densities seen at the threefold axes in the T=1 particle were consistent with the triple-helix interlinking contact at the local threefold axes in the T=7 structure.",1
"Nilsson, Josefina, Miyazaki, Naoyuki, Xing, Li, Wu, Bomu, Hammar, Lena, Li, Tian Cheng, Takeda, Naokazu, Miyamura, Tatsuo, Cheng, R Holland",2
Cell cycle arrest in G2/M promotes early steps of infection by human immunodeficiency virus.,0
"We have identified four small molecules that boost transduction of cells by human immunodeficiency virus (HIV) and investigated their mechanism of action. These molecules include etoposide and camptothecin, which induce DNA damage by inhibiting religation of cleaved topoisomerase-DNA complexes, taxol, which interferes with the function of microtubules, and aphidicolin, which inhibits DNA polymerases. All four compounds arrest the cell cycle at G2/M, though in addition high concentrations of aphidicolin arrest in G1. We find that early events of HIV replication, including synthesis of late reverse transcription products, two-long terminal repeat circles, and integrated proviruses, were increased after treatment of cells with concentrations of each compound that arrested in G2/M. Stimulation was seen for both transformed cell lines (293T and HeLa cells) and primary cells (IMR90 lung fibroblasts). Arrest in G1 with high concentrations of aphidicolin boosted transduction, though not much as with lower concentrations that arrested in G2/M. Arrest of IMR90 cells in G1 by serum starvation and contact inhibition reduced transduction. Previously, the proteasome inhibitor MG132 was reported to increase HIV infection-here we investigated the effects of combinations of the cell cycle inhibitors with MG132 and obtained data suggesting that MG132 may also boost transduction by causing G2/M cell cycle arrest. These data document that cell cycle arrest in G2/M boosts the early steps of HIV infection and suggests methods for increasing transduction with HIV-based vectors.",1
"Groschel, Bettina, Bushman, Frederic",2
"Identification of functional domains in kaposica, the complement control protein homolog of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8).",0
"Recently it has been shown that kaposica, an immune evasion protein of Kaposi's sarcoma-associated herpesvirus, inactivates complement by acting on C3-convertases by accelerating their decay as well as by acting as a cofactor in factor I-mediated inactivation of their subunits C3b and C4b. Here, we have mapped the functional domains of kaposica. We show that SCRs 1 and 2 (SCRs 1-2) and 1-4 are essential for the classical and alternative pathway C3-convertase decay-accelerating activity (DAA), respectively, while the SCRs 2-3 are required for factor I cofactor activity (CFA) for C3b and C4b. SCR 3 and SCRs 1 and 4, however, contribute to optimal classical pathway DAA and C3b CFA, respectively. Binding data show that SCRs 1-4 and SCRs 1-2 are the smallest structural units required for measuring detectable binding to C3b and C4b, respectively. The heparin-binding site maps to SCR 1.",1
"Mullick, Jayati, Singh, Akhilesh K, Panse, Yogesh, Yadav, Vivekanand, Bernet, John, Sahu, Arvind",2
Rapid viral escape at an immunodominant simian-human immunodeficiency virus cytotoxic T-lymphocyte epitope exacts a dramatic fitness cost.,0
"Escape from specific T-cell responses contributes to the progression of human immunodeficiency virus type 1 (HIV-1) infection. T-cell escape viral variants are retained following HIV-1 transmission between major histocompatibility complex (MHC)-matched individuals. However, reversion to wild type can occur following transmission to MHC-mismatched hosts in the absence of cytotoxic T-lymphocyte (CTL) pressure, due to the reduced fitness of the escape mutant virus. We estimated both the strength of immune selection and the fitness cost of escape variants by studying the rates of T-cell escape and reversion in pigtail macaques. Near-complete replacement of wild-type with T-cell escape viral variants at an immunodominant simian immunodeficiency virus Gag epitope KP9 occurred rapidly (over 7 days) following infection of pigtail macaques with SHIVSF162P3. Another challenge virus, SHIVmn229, previously serially passaged through pigtail macaques, contained a KP9 escape mutation in 40/44 clones sequenced from the challenge stock. When six KP9-responding animals were infected with this virus, the escape mutation was maintained. By contrast, in animals not responding to KP9, rapid reversion of the K165R mutation occurred over 2 weeks after infection. The rapidity of reversion to the wild-type sequence suggests a significant fitness cost of the T-cell escape mutant. Quantifying both the selection pressure exerted by CTL and the fitness costs of escape mutation has important implications for the development of CTL-based vaccine strategies.",1
"Fernandez, Caroline S, Stratov, Ivan, De Rose, Robert, Walsh, Katrina, Dale, C Jane, Smith, Miranda Z, Agy, Michael B, Hu, Shiu-Lok, Krebs, Kendall, Watkins, David I, O'connor, David H, Davenport, Miles P, Kent, Stephen J",2
The transcriptional transactivation function of HBx protein is important for its augmentation role in hepatitis B virus replication.,0
"The role and functional domain of hepatitis B virus (HBV) X protein (HBx) in regulating HBV transcription and replication were investigated with a transient transfection system in the human hepatoma cell line HepG2 using wild-type or HBx-minus HBV genome constructs and a series of deletion or mutation HBx expression plasmids. We show here that HBx has augmentation effects on HBV transcription and replication as a HBV mutant genome with defective X gene led to decreased levels of 3.5-kb HBV RNA and HBV replication intermediates and that these decreases can be restored by either transient ectopic expression of HBx or a stable HBx expression cell line. The C-terminal two-thirds (amino acids [aa] 51 to 154), which contain the transactivation domain, is required for this function of HBx; the N-terminal one-third (aa 1 to 50) is not required. Using the alanine scanning mutagenesis strategy, we demonstrated that the regions between aa 52 to 65 and 88 to 154 are important for the augmentation function of HBx in HBV replication. By the luciferase reporter gene analysis, we found that the transactivation and coactivation activities of HBx coincide well with its augmentation function in HBV transcription and replication. These results suggest that HBx has an important role in stimulating HBV transcription and replication and that the transcriptional transactivation function of HBx may be critical for its augmentation effect on HBV replication.",1
"Tang, Hong, Delgermaa, Luvsanjav, Huang, Feijun, Oishi, Naoki, Liu, Li, He, Fang, Zhao, Liansan, Murakami, Seishi",2
H-2 Kd-restricted hepatitis B virus-derived epitope whose specific CD8+ T lymphocytes can produce gamma interferon without cytotoxicity.,0
"It is necessary to evaluate the cytokine secretion status of CD8+ T lymphocytes and elucidate the factors influencing cytokine secretion, because the secretion of cytokines is also an important feature of CD8+ T lymphocytes, and the cytokines usually play critical roles in the outcome of diseases. We showed here that peptide AYRPPNAPI, derived from the core antigen of hepatitis B virus (HBV), could bind to H-2 Kd and induce primed splenocytes from HBcAg expression plasmid-immunized mice to produce gamma interferon (IFN-gamma) in H-2 Kd- and CD8-dependent manners instead of in a CD4-dependent manner. The induced cells were mainly CD3 and CD8 positive but had no cytotoxic effect on the corresponding target cells. When administered into HBV transgenic mice, these cells can decrease the serum HBV load without causing liver damage. These results suggest that this peptide is a special kind of CD8+ T-cell epitope, for which specific CD8+ T cells can produce IFN-gamma when antigenic stimulation is encountered but which have no cytotoxic effect on the corresponding target cells both in vitro and in HBV transgenic mice. This phenomenon indicates initially that the functional mechanisms of CD8+ T cells can be determined by their epitope specificity, which may be associated with the development of epitope-based immunotherapeutic approaches for infectious diseases and tumors.",1
"Chen, An, Wang, Li, Zhang, Jingbo, Zou, Liyun, Jia, Zhengcai, Zhou, Wei, Wan, Ying, Wu, Yuzhang",2
Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 replication and transcription activator regulates viral and cellular genes via interferon-stimulated response elements.,0
"Kaposi's sarcoma-associated herpesvirus (also called human herpesvirus 8 [HHV-8]) replication and transcription activator (RTA) is apparently necessary and sufficient for the switch from viral latency to lytic replication. RTA may regulate open reading frame (ORF) K14 (viral OX-2 homologue) and ORF74 (viral G-protein-coupled receptor homologue) genes through an interferon-stimulated response element (ISRE)-like sequence (K14 ISRE) in the promoter region. RTA strongly activated a K14 ISRE-containing K14-ORF74 promoter reporter construct and a heterologous promoter reporter construct containing K14 ISRE. RTA could bind to K14 ISRE and other ISREs, activate promoter reporter constructs from interferon-simulated genes (ISGs), and selectively induce three endogenous ISGs in primary endothelial cells: ISG-54, myxovirus resistance protein 1 (MxA), and stimulated trans-acting factor of 50 kDa. In addition, a region in the RTA DNA-binding domain has been identified with certain sequence similarity to the DNA-binding domains of the interferon regulatory factor (IRF) family. Mutation in one conserved amino acid within this region reduced the ability of RTA to bind to ISRE as well as other RTA response elements. Furthermore, the mutant failed to activate RTA-responsive promoters and to induce viral lytic gene expression. The mutation at the same conserved amino acid residue in IRF-7 drastically reduced its ability to bind to DNA and to activate the beta interferon promoter. The sequence and functional similarities between RTA and IRFs suggest that the HHV-8 RTA may usurp the cellular IRF pathway.",1
"Zhang, Jun, Wang, Jinzhong, Wood, Charles, Xu, Dongsheng, Zhang, Luwen",2
Inhibition of lysosome and proteasome function enhances human immunodeficiency virus type 1 infection.,0
"We previously reported that inhibition of endosomal/lysosomal function can dramatically enhance human immunodeficiency virus type 1 (HIV-1) infectivity, suggesting that under these conditions productive HIV-1 infection can occur via the endocytic pathway. Here we further examined this effect with bafilomycin A1 (BFLA-1) and show that this enhancement of infectivity extends to all HIV-1 isolates tested regardless of coreceptor usage. However, isolate-specific differences were observed in the magnitude of the effect. This was particularly evident in the case of the weakly infectious HIV-1(SF2), for which we observed the greatest enhancement. Using reciprocal chimeric viruses, we were able to determine that both the disproportionate increase in the infectivity of HIV-1(SF2) in response to BFLA-1 and its weak infectivity in the absence of BFLA-1 mapped to its envelope gene. Further, we found HIV-1(SF2) to have lower fusion activity and to be 12-fold more sensitive to the fusion inhibitor T-20 than HIV-1(NL4-3). Proteasomal inhibitors also enhance HIV-1 infectivity, and we report that the combination of a lysosomal and a proteasomal inhibitor greatly enhanced infectivity of all isolates tested. Again, HIV-1(SF2) was unique in exhibiting a synergistic 400-fold increase in infectivity. We also determined that inhibition of proteasomal function increased the infectivity of HIV-1 pseudotyped with vesicular stomatitis virus G protein. The evidence presented here highlights the important role of the lysosomes/proteasomes in the destruction of infectious HIV-1(SF2) and could have implications for the development of novel antiviral agents that might take advantage of these innate defenses.",1
"Wei, Bangdong L, Denton, Paul W, O'Neill, Eduardo, Luo, Tianci, Foster, John L, Garcia, J Victor",2
Dengue virus inhibits alpha interferon signaling by reducing STAT2 expression.,0
"Alpha/beta interferon (IFN-alpha/beta) is a key mediator of innate antiviral responses but has little effect on the established replication of dengue viruses, which are mosquito-borne flaviviruses of immense global health importance. Understanding how the IFN system is inhibited in dengue virus-infected cells would provide critical insights into disease pathogenesis. In a recent study analyzing the ability of individual dengue virus-encoded proteins to antagonize the IFN response, nonstructural (NS) protein 4B and possibly NS2A and NS4A were identified as candidate IFN antagonists. In monkey cells, NS4B appeared to inhibit both the IFN-alpha/beta and IFN-gamma signal transduction pathways, which are distinct but overlapping (J. L. Munoz-Jordan, G. G. Sanchez-Burgos, M. Laurent-Rolle, and A. Garcia-Sastre, Proc. Natl. Acad. Sci. USA 100:14333-14338, 2003). For this study, we examined the effects of dengue virus on the human IFN system, using cell lines that were stably transfected with self-replicating subgenomic dengue virus RNA (replicons) and that expressed all of the dengue virus nonstructural proteins together. We show here that in replicon-containing cells dengue virus RNA replication and the replication of encephalomyocarditis virus, an IFN-sensitive virus, are resistant to the antiviral effects of IFN-alpha. The presence of dengue virus replicons reduces global IFN-alpha-stimulated gene expression and specifically inhibits IFN-alpha but not IFN-gamma signal transduction. In cells containing replicons or infected with dengue virus, we found reduced levels of signal transducer and activator of transcription 2 (STAT2), which is a key component of IFN-alpha but not IFN-gamma signaling. Collectively, these data show that dengue virus is capable of subverting the human IFN response by down-regulating STAT2 expression.",1
"Jones, Meleri, Davidson, Andrew, Hibbert, Linda, Gruenwald, Petra, Schlaak, Joerg, Ball, Simon, Foster, Graham R, Jacobs, Michael",2
Regression of Epstein-Barr virus-induced B-cell transformation in vitro involves virus-specific CD8+ T cells as the principal effectors and a novel CD4+ T-cell reactivity.,0
"T-cell memory to Epstein-Barr virus (EBV) was first demonstrated through regression of EBV-induced B-cell transformation to lymphoblastoid cell lines (LCLs) in virus-infected peripheral blood mononuclear cell (PBMC) cultures. Here, using donors with virus-specific T-cell memory to well-defined CD4 and CD8 epitopes, we reexamine recent reports that the effector cells mediating regression are EBV latent antigen-specific CD4+ and not, as previously assumed, CD8+ T cells. In regressing cultures, we find that the reversal of CD23+ B-cell proliferation was always coincident with an expansion of latent epitope-specific CD8+, but not CD4+, T cells; furthermore CD8+ T-cell clones derived from regressing cultures were epitope specific and reproduced regression when cocultivated with EBV-infected autologous B cells. In cultures of CD4-depleted PBMCs, there was less efficient expansion of these epitope-specific CD8+ T cells and correspondingly weaker regression. The data are consistent with an effector role for epitope-specific CD8+ T cells in regression and an auxiliary role for CD4+ T cells in expanding the CD8 response. However, we also occasionally observed late regression in CD8-depleted PBMC cultures, though again without any detectable expansion of preexisting epitope-specific CD4+ T-cell memory. CD4+ T-cell clones derived from such cultures were LCL specific in gamma interferon release assays but did not recognize any known EBV latent cycle protein or derived peptide. A subset of these clones was also cytolytic and could block LCL outgrowth. These novel effectors, whose antigen specificity remains to be determined, may also play a role in limiting virus-induced B-cell proliferation in vitro and in vivo.",1
"Gudgeon, Nancy H, Taylor, Graham S, Long, Heather M, Haigh, Tracey A, Rickinson, Alan B",2
Homologous crossovers among molecules of brome mosaic bromovirus RNA1 or RNA2 segments in vivo.,0
"Previously we demonstrated frequent homologous crossovers among molecules of the RNA3 segment in the tripartite brome mosaic bromovirus (BMV) RNA genome (A. Bruyere, M. Wantroba, S. Flasinski, A. Dzianott, and J. J. Bujarski, J. Virol. 74:4214-4219, 2000). To further our knowledge about mechanisms of viral RNA genome variability, in this paper we have studied homologous recombination in BMV RNA1 and RNA2 components during infection. We have found that basal RNA-RNA crossovers could occur within coding regions of both RNAs, although recombination frequencies slightly varied at different RNA sections. In all cases, the frequencies were much lower than the rate observed for the intercistronic recombination hot spot in BMV RNA3. Probability calculations accounted for at least one homologous crossover per RNA molecule per replication cycle. In addition, we have demonstrated an efficient repair of mutations within the conserved 3' and 5' noncoding regions, most likely due to error-prone BMV RNA replication. Overall, our data verify that homologous crossovers are common events a during virus life cycle, and we discuss their importance for viral RNA genetics.",1
"Urbanowicz, Anna, Alejska, Magdalena, Formanowicz, Piotr, Blazewicz, Jacek, Figlerowicz, Marek, Bujarski, Jozef J",2
Macrophage inflammatory protein 1alpha inhibits postentry steps of human immunodeficiency virus type 1 infection via suppression of intracellular cyclic AMP.,0
"Primary isolates of human immunodeficiency virus type 1 (HIV-1) predominantly use chemokine receptor CCR5 to enter target cells. The natural ligands of CCR5, the beta-chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES, interfere with HIV-1 binding to CCR5 receptors and decrease the amount of virions entering cells. Although the inhibition of HIV-1 entry by beta-chemokines is well documented, their effects on postentry steps of the viral life cycle and on host cell components that control the outcome of infection after viral entry are not well defined. Here, we show that all three beta-chemokines, and MIP-1alpha in particular, inhibit postentry steps of the HIV-1 life cycle in primary lymphocytes, presumably via suppression of intracellular levels of cyclic AMP (cAMP). Productive HIV-1 infection of primary lymphocytes requires cellular activation. Cell activation increases intracellular cAMP, which is required for efficient synthesis of proviral DNA during early steps of viral infection. Binding of MIP-1alpha to cognate receptors decreases activation-induced intracellular cAMP levels through the activation of inhibitory G proteins. Furthermore, inhibition of one of the downstream targets of cAMP, cAMP-dependent PKA, significantly inhibits synthesis of HIV-1-specific DNA without affecting virus entry. These data reveal that beta-chemokine-mediated inhibition of virus replication in primary lymphocytes combines inhibitory effects at the entry and postentry levels and imply the involvement of beta-chemokine-induced signaling in postentry inhibition of HIV-1 infection.",1
"Amella, Carol-Ann, Sherry, Barbara, Shepp, David H, Schmidtmayerova, Helena",2
"St, a truncated envelope protein derived from the S protein of duck hepatitis B virus, acts as a chaperone for the folding of the large envelope protein.",0
"Envelope proteins of hepadnaviruses undergo a unique folding mechanism which results in the posttranslational translocation of 50% of the large envelope protein (L) chains across the endoplasmic reticulum. This mechanism is essential for the eventual positioning of the receptor-binding domain on the surface of the virus particle and in duck hepatitis B virus (DHBV) is dependent on the small (S) envelope protein as part of the assembly process. In this study, we report the identification of a third envelope protein, St, derived from the S protein and carrying functions previously attributed to S. Antibody mapping and mutagenesis studies indicated St to be C terminally truncated, spanning the N-terminal transmembrane domain (TM1) plus the adjacent cysteine loop. We have previously shown that the mutation of two conserved polar residues in TM1 of S (SAA) eliminates L translocation and assembly. A plasmid expressing a functional equivalent of St was able to rescue assembly, demonstrating that this assembly defect is due to mutations of the corresponding residues in St and not in S per se. Immunofluorescence analysis showed that St directly affects L protein cellular localization. These results indicate that St acts as a viral chaperone for L folding, remaining associated with the DHBV envelope upon secretion. The presence of St at a molar ratio of half that of L suggests that it is St which regulates L translocation to 50%.",1
"Grgacic, Elizabeth V L, Anderson, David A",2
Linked tumor-selective virus replication and transgene expression from E3-containing oncolytic adenoviruses.,0
"Historically, the adenoviral E3 region was found to be nonessential for viral replication in vitro. In addition, adenoviruses whose genome was more than approximately 105% the size of the native genome were inefficiently packaged. These profound observations were used experimentally to insert transgenes into the adenoviral backbone. More recently, however, the reintroduction of the E3 region into oncolytic adenoviruses has been found to positively influence antitumor efficacy in preclinical models and clinical trials. In the studies reported here, the granulocyte-macrophage colony-stimulating factor (GM-CSF) cDNA sequence has been substituted for the E3-gp19 gene in oncolytic adenoviruses that otherwise retained the E3 region. Five viruses that differed slightly in the method of transgene insertion were generated and compared to Ar6pAE2fGmF (E2F/GM/DeltaE3), a previously described E3-deleted oncolytic adenovirus encoding GM-CSF. In all of the viruses, the human E2F-1 promoter regulated E1A expression and GM-CSF expression was under the control of the adenoviral E3 promoter and the packaging signal was relocated immediately upstream from the right terminal repeat. The E3-gp19-deleted viruses had similar cytolytic properties, as measured in vitro by cytotoxicity assays, but differed markedly in their capacity to express and secrete GM-CSF. Ar15pAE2fGmF (E2F/GM/E3b), the virus that produced the highest levels of GM-CSF and retained the native GM-CSF leader sequence, was selected for further analysis. The E2F/GM/E3b and E2F/GM/DeltaE3 viruses exhibited similar cytotoxic activity and GM-CSF production in several tumor cell lines in vitro. However, when compared in vivo in nude mouse xenograft tumor models, E2F/GM/E3b spread through tumors to a greater extent, resulted in higher peak GM-CSF and total exposure levels in both tumor and serum, and was more efficacious than the E3-deleted virus. Using the matched WI-38 (parental) and WI-38-VA13 (simian virus 40 large T antigen transformed) cell pair, GM-CSF was shown to be selectively produced in cells expressing high levels of E2F, indicating that the tumor-selective E2F promoter controlled E1A and GM-CSF expression.",1
"Zhu, Mingzhu, Bristol, J Andrew, Xie, Yuefeng, Mina, Mervat, Ji, Hong, Forry-Schaudies, Suzanne, Ennist, David L",2
"Effects of nonstructural proteins NS1 and NS2 of human respiratory syncytial virus on interferon regulatory factor 3, NF-kappaB, and proinflammatory cytokines.",0
"Human respiratory syncytial virus (HRSV) is the leading cause of serious pediatric acute respiratory tract infections, and a better understanding is needed of the host response to HRSV and its attenuated vaccine derivatives. It has been shown previously that HRSV nonstructural proteins 1 and 2 (NS1 and NS2) inhibit the induction of alpha/beta interferon (IFN-alpha/beta) in A549 cells and human macrophages. Two principal transcription factors for the early IFN-beta and -alpha1 response are interferon regulatory factor 3 (IRF-3) and nuclear factor kappaB (NF-kappaB). At early times postinfection, wild-type HRSV and the NS1/NS2 deletion mutants were very similar in the ability to activate IRF-3. However, once NS1 and NS2 were expressed significantly, they acted cooperatively to suppress activation and nuclear translocation of IRF-3. Since these viruses differed greatly in the induction of IFN-alpha/beta, NF-kappaB activation was evaluated in Vero cells, which lack the structural genes for IFN-alpha/beta and would preclude confounding effects of IFN-alpha/beta. This showed that deletion of the NS2 gene sharply reduced the ability of HRSV to induce activation of NF-kappaB. Since recombinant HRSVs from which the NS1 or NS2 genes have been deleted are being developed as vaccine candidates, we investigated whether the changes in activation of host transcription factors and increased IFN-alpha/beta production had an effect on the epithelial production of proinflammatory factors. Viruses lacking NS1 and/or NS2 stimulated modestly lower production of RANTES (Regulated on Activation Normal T-cell Expressed and Secreted), interleukin 8, and tumor necrosis factor alpha compared to wild-type recombinant RSV, supporting their use as attenuated vaccine candidates.",1
"Spann, Kirsten M, Tran, Kim C, Collins, Peter L",2
An unrelated monoclonal antibody neutralizes human immunodeficiency virus type 1 by binding to an artificial epitope engineered in a functionally neutral region of the viral envelope glycoproteins.,0
"Neutralizing antibodies often recognize regions of viral envelope glycoproteins that play a role in receptor binding or other aspects of virus entry. To address whether this is a necessary feature of a neutralizing antibody, we identified the V4 region of the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) as a sequence that is tolerant of drastic change and thus appears to play a negligible role in envelope glycoprotein function. An artificial epitope tag was inserted into the V4 region without a significant effect on virus entry or neutralization by antibodies that recognize HIV-1 envelope glycoprotein sequences. An antibody directed against the artificial epitope tag was able to neutralize the modified, but not the wild-type, HIV-1. Thus, the specific target of a neutralizing antibody need not contribute functionally to the process of virus entry.",1
"Ren, Xinping, Sodroski, Joseph, Yang, Xinzhen",2
Novel macula-like virus identified in Bombyx mori cultured cells.,0
"We identified a novel, 6,513-bp-long RNA, termed Bombyx mori macula-like latent virus (BmMLV) RNA, which abundantly expressed in B. mori cultured BmN cells. BmMLV RNA potentially encodes two proteins, putative RNA replicase and coat protein, which share structural features and sequence similarities with those of a plant RNA virus, the genus Maculavirus. Northern blot analysis showed that two transcripts were expressed in BmN cells: a 6.5-kb-long RNA, which contains both putative RNA replicase and coat protein genes, and a 1.2-kb-long RNA, which contains only a coat protein gene. Southern blot analysis showed that BmMLV RNA is not carried by the B. mori genome. RT-PCR analysis also revealed the presence of BmMLV RNA in several B. mori cell lines other than BmN cells, suggesting that BmMLV RNA latently exists in B. mori cultured cells. Infection studies showed that BmMLV virions were able to infect BmMLV-negative Spodoptera frugiperda Sf-9 cells and B. mori larvae. Electron microscopy and Northern blot analysis of a purified BmMLV revealed that isometric virions appear to be 28 to 30 nm in diameter and contain a 6.5-kb genomic RNA. These results showed that BmMLV is a novel macula-like virus infectious to and replicable in B. mori-derived cells.",1
"Katsuma, Susumu, Tanaka, Shinichiro, Omuro, Naoko, Takabuchi, Lisa, Daimon, Takaaki, Imanishi, Shigeo, Yamashita, Shuichi, Iwanaga, Masashi, Mita, Kazuei, Maeda, Susumu, Kobayashi, Masahiko, Shimada, Toru",2
Rift valley fever virus nonstructural protein NSs promotes viral RNA replication and transcription in a minigenome system.,0
"Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, has a tripartite negative-strand genome (S, M, and L segments) and is an important mosquito-borne pathogen for domestic animals and humans. We established an RVFV T7 RNA polymerase-driven minigenome system in which T7 RNA polymerase from an expression plasmid drove expression of RNA transcripts for viral proteins and minigenome RNA transcripts carrying a reporter gene between both termini of the M RNA segment in 293T cells. Like other viruses of the Bunyaviridae family, replication and transcription of the RVFV minigenome required expression of viral N and L proteins. Unexpectedly, the coexpression of an RVFV nonstructural protein, NSs, with N and L proteins resulted in a significant enhancement of minigenome RNA replication. Coexpression of NSs protein with N and L proteins also enhanced minigenome mRNA transcription in the cells expressing viral-sense minigenome RNA transcripts. NSs protein expression increased the RNA replication of minigenomes that originated from S and L RNA segments. Enhancement of minigenome RNA synthesis by NSs protein occurred in cells lacking alpha/beta interferon (IFN-alpha/beta) genes, indicating that the effect of NSs protein on minigenome RNA replication was unrelated to a putative NSs protein-induced inhibition of IFN-alpha/beta production. Our finding that RVFV NSs protein augmented minigenome RNA synthesis was in sharp contrast to reports that Bunyamwera virus (genus Bunyavirus) NSs protein inhibits viral minigenome RNA synthesis, suggesting that RVFV NSs protein and Bunyamwera virus NSs protein have distinctly different biological roles in viral RNA synthesis.",1
"Ikegami, Tetsuro, Peters, C J, Makino, Shinji",2
Highly protective in vivo function of cytomegalovirus IE1 epitope-specific memory CD8 T cells purified by T-cell receptor-based cell sorting.,0
"Reconstitution of antiviral CD8 T cells is essential for controlling cytomegalovirus (CMV) infection after bone marrow transplantation. Accordingly, polyclonal CD8 T cells derived from BALB/c mice infected with murine CMV protect immunocompromised adoptive transfer recipients against CMV disease. The protective population comprises CD8 T cells with T-cell receptors (TCRs) specific for defined and for as-yet-unknown viral epitopes, as well as a majority of nonprotective cells with unrelated specificities. Defined epitopes include IE1/m123 and m164, which are immunodominant in terms of the magnitude of the CD8 T-cell response, and a panel of subordinate epitopes (m04, m18, M45, M83, and M84). While cytolytic T-lymphocyte lines (CTLLs) were shown to be protective regardless of the immunodominance of the respective epitope, the individual contributions of in vivo resident epitope-specific CD8 T cells to the antiviral control awaited investigation. The IE1 peptide 168-YPHFMPTNL-176 is generated from the immediate-early protein 1 (IE1) (pp89/76) of murine CMV and is presented by the major histocompatibility complex class I (MHC-I) molecule Ld. To quantitate its contribution to the protective potential of a CD8-T memory (CD8-TM) cell population, IE1-TCR+ and IE1-TCR- CD8-TM cells were purified by epitope-specific cell sorting with IE1 peptide-loaded MHC-immunoglobulin G1 dimers as ligands of cognate TCRs. Of relevance for clinical approaches to an adoptive cellular immunotherapy, sorted IE1 epitope-specific CD8-TM cells were found to be exceedingly protective upon adoptive transfer. Compared with CTLLs specific for the same epitope and of comparable avidity and TCR beta-chain variable region (Vbeta)-defined polyclonality, sorted CD8-TM cells proved to be superior by more than 2 orders of magnitude.",1
"Pahl-Seibert, Marcus-Folker, Juelch, Markus, Podlech, Jürgen, Thomas, Doris, Deegen, Petra, Reddehase, Matthias J, Holtappels, Rafaela",2
Complete genome sequence and in planta subcellular localization of maize fine streak virus proteins.,0
"The genome of the nucleorhabdovirus maize fine streak virus (MFSV) consists of 13,782 nucleotides of nonsegmented, negative-sense, single-stranded RNA. The antigenomic strand consisted of seven open reading frames (ORFs), and transcripts of all ORFs were detected in infected plants. ORF1, ORF6, and ORF7 had significant similarities to the nucleocapsid protein (N), glycoprotein (G), and polymerase (L) genes of other rhabdoviruses, respectively, whereas the ORF2, ORF3, ORF4, and ORF5 proteins had no significant similarities. The N (ORF1), ORF4, and ORF5 proteins localized to nuclei, consistent with the presence of nuclear localization signals (NLSs) in these proteins. ORF5 likely encodes the matrix protein (M), based on its size, the position of its NLS, and the localization of fluorescent protein fusions to the nucleus. ORF2 probably encodes the phosphoprotein (P) because, like the P protein of Sonchus yellow net virus (SYNV), it was spread throughout the cell when expressed alone but was relocalized to a subnuclear locus when coexpressed with the MFSV N protein. Unexpectedly, coexpression of the MFSV N and P proteins, but not the orthologous proteins of SYNV, resulted in accumulations of both proteins in the nucleolus. The N and P protein relocalization was specific to cognate proteins of each virus. The subcellular localizations of the MFSV ORF3 and ORF4 proteins were distinct from that of the SYNV sc4 protein, suggesting different functions. To our knowledge, this is the first comparative study of the cellular localizations of plant rhabdoviral proteins. This study indicated that plant rhabdoviruses are diverse in genome sequence and viral protein interactions.",1
"Tsai, Chi-Wei, Redinbaugh, Margaret G, Willie, Kristen J, Reed, Sharon, Goodin, Michael, Hogenhout, Saskia A",2
Pseudovirion particle production by live poxvirus human immunodeficiency virus vaccine vector enhances humoral and cellular immune responses.,0
"Live-vector-based human immunodeficiency virus (HIV) vaccines are an integral part of a number of HIV vaccine regimens currently under evaluation. Live vectors that carry an intact gag gene are capable of eliciting HIV pseudovirion particle formation from infected host cells. The impact of pseudovirion particle formation on the immune response generated by live HIV vaccine vectors has not been established. In this study, a canarypox HIV vaccine candidate vector expressing HIV gag and env genes, vCP205, was modified by the introduction of a glycine-to-alanine coding change in the N-terminal myristylation site of gag to create Myr- vCP205. This substitution effectively eliminated particle formation without altering the level of protein production. vCP205 and Myr- vCP205 were then directly compared for the ability to induce HIV-specific immune responses in mice. The particle-competent vector vCP205 elicited higher levels of CD8+ T-cell responses, as indicated by gamma interferon enzyme-linked immunospot (ELISPOT) assay and intracellular cytokine staining. Humoral responses to Gag and Env were also markedly higher from animals immunized with the particle-competent vector. Furthermore, HIV-specific CD4+ T-cell responses were greater among animals immunized with the particle-competent vector. Using a human dendritic cell model of antigen presentation in vitro, vCP205 generated greater ELISPOT responses than Myr- vCP205. These results demonstrate that pseudovirion particle production by live-vector HIV vaccines enhances HIV-specific cellular and humoral immune responses.",1
"Chen, Xuemin, Rock, Michael T, Hammonds, Jason, Tartaglia, James, Shintani, Ayumi, Currier, Jeff, Slike, Bonnie, Crowe, James E, Marovich, Mary, Spearman, Paul",2
Cross-reactive cytotoxic T lymphocytes against human immunodeficiency virus type 1 protease and gamma interferon-inducible protein 30.,0
"The gamma interferon (IFN-gamma)-inducible protein 30 (IP-30) signal peptide -11 to -3 (LLDVPTAAV) is a prominent self peptide expressed with the class I human histocompatibility leukocyte antigen A2 (HLA-A2). Stimulation of peripheral blood mononuclear cells (PBMC) from HLA-A2 human immunodeficiency virus type 1 (HIV-1)-infected individuals with an HLA-A2-restricted HIV protease (PR) peptide 76-84 (LVGPTPVNI) activated cytotoxic T lymphocytes (CTL) against the IP-30 signal peptide. Since HIV-1 PR 76-84 stimulated CD8+ T cells from these individuals to secrete IFN-gamma, we tested whether the activation of IP-30-specific CTL in vitro resulted from T-cell cross-reactivity or from up-regulation of IP-30 by IFN-gamma. Neither high levels of exogenous IFN-gamma nor incubation of PBMC with other HIV peptides triggering substantial IFN-gamma release activated IP-30-specific CTL. Although the IP-30 signal peptide did not stimulate IFN-gamma release from freshly isolated PBMC, it activated CTL in vitro against itself and HIV PR 76-84. Peptide-stimulated IFN-gamma release, cold target inhibition, and HLA-A2/immunoglobulin dimer-mediated binding and depletion of effector cells all indicated that in vitro stimulation with HIV PR 76-84 or the IP-30 signal peptide activated a comparable population of cross-reactive effector cells. Neither IP-30 nor HIV PR 76-84 activated CTL against themselves following in vitro stimulation of PBMC from non-HIV-infected HLA-A2 individuals. Peptide titrations indicated higher-avidity T-cell interactions with HIV PR 76-84 than with the IP-30 signal peptide. These data indicate that HIV PR 76-84 is a heteroclitic variant of the IP-30 signal peptide -11 to -3, which has implications for immune memory and autoimmunity.",1
"Mason, R D, Bowmer, M I, Howley, C M, Grant, M D",2
"Rhesus cytomegalovirus contains functional homologues of US2, US3, US6, and US11.",0
"Human cytomegalovirus (HCMV) is a paradigm for mechanisms subverting antigen presentation by major histocompatibility complex (MHC) molecules. Due to its limited host range, HCMV cannot be studied in animals. Thus, the in vivo importance of inhibiting antigen presentation for the establishment and maintenance of infection with HCMV is unknown. Rhesus cytomegalovirus (RhCMV) is an emerging animal model that shares many of the features of HCMV infection. The recent completion of the genomic sequence of RhCMV revealed a significant degree of homology to HCMV. Strikingly, RhCMV contains several genes with low homology to the HCMV US6 gene family of inhibitors of the MHC I antigen presentation pathway. Here, we examine whether the RhCMV US6 homologues (open reading frames Rh182, -184, -185, -186, -187, and -189) interfere with the MHC I antigen-processing pathway. We demonstrate that Rh182 and Rh189 function similarly to HCMV US2 and US11, respectively, mediating the proteasomal degradation of newly synthesized MHC I. The US3 homologue, Rh184, delayed MHC I maturation. Unlike US3, MHC I molecules eventually escaped retention by Rh184, so that steady-state surface levels of MHC I remained unchanged. Rh185 acted similarly to US6 and inhibited peptide transport by TAP and, consequently, peptide loading of MHC I molecules. Thus, despite relatively low sequence conservation, US6 family-related genes in RhCMV are functionally closely related to the conserved structural features of HCMV immunomodulators. The conservation of these mechanisms implies their importance for immune evasion in vivo, a question that can now be addressed experimentally.",1
"Pande, Nupur T, Powers, Colin, Ahn, Kwangseog, Früh, Klaus",2
Human immunodeficiency virus type 1 inhibits DNA damage-triggered apoptosis by a Nef-independent mechanism.,0
"It is controversial whether the accessory human immunodeficiency virus type 1 (HIV-1) Nef protein inhibits or enhances apoptosis. To address this issue, we investigated the effect of Nef on programmed cell death with vectors or proviral HIV-1 constructs coexpressing Nef and green fluorescent protein from single bicistronic RNAs. This approach allows us to readily identify transfected or infected cells and to correlate cell death directly with Nef expression levels. We demonstrate that Nef does not significantly affect apoptosis in transfected or HIV-1-infected Jurkat T cells or primary human peripheral blood mononuclear cells. Unexpectedly, however, both nef+ and nef-defective HIV-1 infection blocked apoptosis in cells treated with UV light or etoposide but not cell death induced by CD95 antibody, TRAIL, Ly294002, or serum starvation. Our results show that HIV-1 infection inhibits DNA damage-induced but not death receptor-dependent cell death by a Nef-independent mechanism.",1
"Schindler, Michael, Münch, Jan, Kirchhoff, Frank",2
Effect of antiviral treatment with entecavir on age- and dose-related outcomes of duck hepatitis B virus infection.,0
"Entecavir (ETV), a potent inhibitor of the hepadnaviral polymerases, prevented the development of persistent infection when administered in the early stages of duck hepatitis B virus (DHBV) infection. In a preliminary experiment, ETV treatment commenced 24 h before infection showed no significant advantage over simultaneous ETV treatment and infection. In two further experiments 14-day-old ducks were inoculated with DHBV-positive serum containing 10(4), 10(6), 10(8), or 5 x 10(8) viral genomes (vge) and were treated orally with 1.0 mg/kg of body weight/day of ETV for 14 or 49 days. A relationship between virus dose and infection outcome was seen: non-ETV-treated ducks inoculated with 10(4) vge had transient infection, while ducks inoculated with higher doses developed persistent infection. ETV treatment for 49 days did not prevent initial infection of the liver but restricted the spread of infection more than approximately 1,000-fold, a difference which persisted throughout treatment and for up to 49 days after withdrawal. Ultimately, three of seven ETV-treated ducks resolved their DHBV infection, while the remaining ducks developed viremia and persistent infection after a lag period of at least 63 days. ETV treatment for 14 days also restricted the spread of infection, leading to marked and sustained reductions in the number of DHBV-positive hepatocytes in 7 out of 10 ducks. In conclusion, short-term suppression with ETV provides opportunity for the immune response to successfully control DHBV infection. Since DHBV infection of ducks provides a good model system for HBV infection in humans, it seems likely that ETV may be useful in postexposure therapy for HBV infection aimed at preventing the development of persistent infection.",1
"Foster, Wendy K, Miller, Darren S, Scougall, Catherine A, Kotlarski, Ieva, Colonno, Richard J, Jilbert, Allison R",2
Evaluation of the conformational switch model for alfalfa mosaic virus RNA replication.,0
"Key elements of the conformational switch model describing regulation of alfalfa mosaic virus (AMV) replication (R. C. Olsthoorn, S. Mertens, F. T. Brederode, and J. F. Bol, EMBO J. 18:4856-4864, 1999) have been tested using biochemical assays and functional studies in nontransgenic protoplasts. Although comparative sequence analysis suggests that the 3' untranslated regions of AMV and ilarvirus RNAs have the potential to fold into pseudoknots, we were unable to confirm that a proposed pseudoknot forms or has a functional role in regulating coat protein-RNA binding or viral RNA replication. Published work has suggested that the pseudoknot is part of a tRNA-like structure (TLS); however, we argue that the canonical sequence and functional features that define the TLS are absent. We suggest here that the absence of the TLS correlates directly with the distinctive requirement for coat protein to activate replication in these viruses. Experimental data are evidence that elevated magnesium concentrations proposed to stabilize the pseudoknot structure do not block coat protein binding. Additionally, covarying nucleotide changes proposed to reestablish pseudoknot pairings do not rescue replication. Furthermore, as described in the accompanying paper (L. M. Guogas, S. M. Laforest, and L. Gehrke, J. Virol. 79:5752-5761, 2005), coat protein is not, by definition, inhibitory to minus-strand RNA synthesis. Rather, the activation of viral RNA replication by coat protein is shown to be concentration dependent. We describe the 3' organization model as an alternate model of AMV replication that offers an improved fit to the available data.",1
"Petrillo, Jessica E, Rocheleau, Gail, Kelley-Clarke, Brenna, Gehrke, Lee",2
Coat protein activation of alfalfa mosaic virus replication is concentration dependent.,0
"Alfalfa mosaic virus (AMV) and ilarvirus RNAs are infectious only in the presence of the viral coat protein; therefore, an understanding of coat protein's function is important for defining viral replication mechanisms. Based on in vitro replication experiments, the conformational switch model states that AMV coat protein blocks minus-strand RNA synthesis (R. C. Olsthoorn, S. Mertens, F. T. Brederode, and J. F. Bol, EMBO J. 18:4856-4864, 1999), while another report states that coat protein present in an inoculum is required to permit minus-strand synthesis (L. Neeleman and J. F. Bol, Virology 254:324-333, 1999). Here, we report on experiments that address these contrasting results with a goal of defining coat protein's function in the earliest stages of AMV replication. To detect coat-protein-activated AMV RNA replication, we designed and characterized a subgenomic luciferase reporter construct. We demonstrate that activation of viral RNA replication by coat protein is concentration dependent; that is, replication was strongly stimulated at low coat protein concentrations but decreased progressively at higher concentrations. Genomic RNA3 mutations preventing coat protein mRNA translation or disrupting coat protein's RNA binding domain diminished replication. The data indicate that RNA binding and an ongoing supply of coat protein are required to initiate replication on progeny genomic RNA transcripts. The data do not support the conformational switch model's claim that coat protein inhibits the initial stages of viral RNA replication. Replication activation may correlate with low local coat protein concentrations and low coat protein occupancy on the multiple binding sites present in the 3' untranslated regions of the viral RNAs.",1
"Guogas, Laura M, Laforest, Siana M, Gehrke, Lee",2
A conformational change in the adeno-associated virus type 2 capsid leads to the exposure of hidden VP1 N termini.,0
"The complex infection process of parvoviruses is not well understood so far. An important role has been attributed to a phospholipase A2 domain which is located within the unique N terminus of the capsid protein VP1. Based on the structural difference between adeno-associated virus type 2 wild-type capsids and capsids lacking VP1 or VP2, we show via electron cryomicroscopy that the N termini of VP1 and VP2 are involved in forming globules inside the capsids of empty and full particles. Upon limited heat shock, VP1 and possibly VP2 become exposed on the outsides of full but not empty capsids, which is correlated with the disappearance of the globules in the inner surfaces of the capsids. Using molecular modeling, we discuss the constraints on the release of the globularly organized VP1-unique N termini through the channels at the fivefold symmetry axes outside of the capsid.",1
"Kronenberg, Stephanie, Böttcher, Bettina, von der Lieth, Claus W, Bleker, Svenja, Kleinschmidt, Jürgen A",2
Characterization of prototype foamy virus gag late assembly domain motifs and their role in particle egress and infectivity.,0
"Foamy viruses (FV) are unusual among retroviruses since they require both Gag and Env structural proteins for particle egress. Recently significant progress has been made towards the mechanistic understanding of the viral release process, in particular that of retroviruses, and the viral domains and cellular pathways involved. However little is currently known about domains of FV structural proteins and cellular proteins engaged in this process. By mutational analysis of sequence motifs in prototype FV (PFV) Gag, bearing homology to known late assembly (L) domains, a PSAP motif with L domain function that was functionally interchangeable by heterologous L domains was identified. In contrast the inactivation of a PPPI motif had no significant influence on PFV particle release, although mutant viral particles displayed reduced infectivity. Similarly mutation of an evolutionary conserved YXXL motif revealed no classical L-domain function but resulted in release of noninfectious viruslike particles. Biochemical and electron microscopy analysis demonstrated that these mutant particles incorporated all viral structural proteins but contained aberrantly capsid structures, suggesting a role in capsid assembly for this PFV Gag sequence motif. In line with the mutational analysis, overexpression of dominant negative (DN) mutants and wild-type TSG101 but not the DN mutant of AIP-1/ALIX reduced PFV particle release and infectivity. Furthermore, DN mutants of Vps4A, Vps4B, and CHMP3 inhibited PFV egress and infectivity. Taken together these results demonstrate that PFV, like other viruses, requires components of the vacuolar protein sorting (VPS) machinery for egress and enters the VPS pathway through interaction with TSG101.",1
"Stange, Annett, Mannigel, Ingrid, Peters, Katrin, Heinkelein, Martin, Stanke, Nicole, Cartellieri, Marc, Göttlinger, Heinrich, Rethwilm, Axel, Zentgraf, Hanswalter, Lindemann, Dirk",2
"Replication-competent adenovirus formation in 293 cells: the recombination-based rate is influenced by structure and location of the transgene cassette and not increased by overproduction of HsRad51, Rad51-interacting, or E2F family proteins.",0
"Propagation of E1 region replacement adenovirus vectors in 293 cells results in the rare appearance of replication-competent adenovirus (RCA). The RCA genome contains E1 DNA acquired from the 293 cellular genome. The Luria-Delbruck fluctuation test was adapted to measure RCA formation rates. To test if structure affected rate, we measured rates during the production of adenovirus vectors with genomes containing three different expression cassette arrangements. The vectors had different extents of sequence identity with integrated Ad5 DNA of 293 cells and had different distributions of identity flanking the expression cassettes. Empty cassette vector RCA rates ranged from 2.5 x 10(-8) to 5.6 x 10(-10). The extent of sequence identity was not an accurate RCA rate predictor. The vector with the highest RCA rate also had the least overall sequence identity. To define factors controlling RCA generation, adenovirus vectors expressing E2F family proteins, known to modulate recombination gene expression, and overexpressing the human Rad51 recombination protein were analyzed. Compared to their corresponding empty vectors, RCA rates were not increased but were slightly decreased. Initial results suggested expression cassette orientation and/or transcription direction as potential RCA rate modifiers. Testing adenovirus vectors with identical transgene cassettes oriented in opposite directions suggested that transcription direction was not the basis of these rate differences. Thus, the overall structure and location of the transgene cassette had the largest effect on RCA rate. The RCA fluctuation test should be useful for investigators who require accurate measurements of targeted recombination and the probability of RCA formation during stock production.",1
"Duigou, Gregory J, Young, C S H",2
Endoplasmic reticulum-localized human papillomavirus type 16 E5 protein alters endosomal pH but not trans-Golgi pH.,0
"The human papillomavirus type 16 (HPV-16) E5 protein is a small, hydrophobic polypeptide that is expressed in virus-infected keratinocytes and alters receptor signaling pathways, apoptotic responses, and endosomal pH. Despite its ability to inhibit endosomal acidification, the HPV-16 E5 protein is found predominantly in the endoplasmic reticulum (ER), suggesting that its effect may be indirect and perhaps global. To determine whether E5 alters the pHs of additional intracellular compartments, we transduced human keratinocytes with a codon-optimized E5 vector and then quantified endosomal and trans-Golgi pHs using sensitive, compartment-specific, ratiometric pHluorin constructs. E5 protein increased endosomal pH from 5.9 to 6.9 but did not affect the normal trans-Golgi pH of 6.3. Confirming the lack of alteration in trans-Golgi pH, we observed no alterations in the acidification-dependent processing of the proH3 protein. C-terminal deletions of E5, which retained normal expression and localization in the ER, were defective for endosomal alkalization. Thus, E5 does not uniformly alkalinize intracellular compartments, and its C-terminal 10 amino acids appear to mediate interactions with critical ER targets that modulate proton pump function and/or localization.",1
"Disbrow, Gary L, Hanover, John A, Schlegel, Richard",2
Nearby clusters of hemagglutinin residues sustain SLAM-dependent canine distemper virus entry in peripheral blood mononuclear cells.,0
"Signaling lymphocytic activation molecule (SLAM, CD150) is the universal morbillivirus receptor. Based on the identification of measles virus (MV) hemagglutinin (H) amino acids supporting human SLAM-dependent cell entry, we mutated canine distemper virus (CDV) H and identified residues necessary for efficient canine SLAM-dependent membrane fusion. These residues are located in two nearby clusters in a new CDV H structural model. To completely abolish SLAM-dependent fusion, combinations of mutations were necessary. We rescued a SLAM-blind recombinant CDV with six mutations that did not infect ferret peripheral blood mononuclear cells while retaining full infectivity in epithelial cells.",1
"von Messling, Veronika, Oezguen, Numan, Zheng, Qi, Vongpunsawad, Sompong, Braun, Werner, Cattaneo, Roberto",2
Unique long terminal repeat and surface glycoprotein gene sequences of feline leukemia virus as determinants of disease outcome.,0
"The outcome of feline leukemia virus (FeLV) infection in nature is variable, including malignant, proliferative, and degenerative disorders. The determinants of disease outcome are not well understood but are thought to include viral, host, and environmental factors. In particular, genetic variations in the FeLV long terminal repeat (LTR) and SU gene have been linked to disease outcome. FeLV-945 was previously identified as a natural isolate predominant in non-T-cell neoplastic and nonneoplastic diseases in a geographic cohort. The FeLV-945 LTR was shown to contain unique repeat elements, including a 21-bp triplication downstream of the enhancer. The FeLV-945 SU gene was shown to encode mutational changes in functional domains of the protein. The present study details the outcomes of infection with recombinant FeLVs in which the LTR and envelope (env) gene of FeLV-945, or the LTR only, was substituted for homologous sequences in a horizontally transmissible prototype isolate, FeLV-A/61E. The results showed that the FeLV-945 LTR determined the kinetics of disease. Substitution of the FeLV-945 LTR into FeLV-A/61E resulted in a significantly more rapid disease onset but did not alter the tumorigenic spectrum. In contrast, substitution of both the FeLV-945 LTR and env gene changed the disease outcome entirely. Further, the impact of FeLV-945 env on the disease outcome was dependent on the route of inoculation. Since the TM genes of FeLV-945 and FeLV-A/61E are nearly identical but the SU genes differ significantly, FeLV-945 SU is implicated in the outcome. These findings identify the FeLV-945 LTR and SU gene as determinants of disease.",1
"Chandhasin, Chandtip, Coan, Patricia N, Pandrea, Ivona, Grant, Chris K, Lobelle-Rich, Patricia A, Puetter, Adriane, Levy, Laura S",2
Covert human immunodeficiency virus replication in dendritic cells and in DC-SIGN-expressing cells promotes long-term transmission to lymphocytes.,0
"HIV-1 virions are efficiently captured by monocyte-derived immature dendritic cells (iDCs), as well as by cell lines expressing the lectin DC-SIGN. Viral infectivity can be retained for several days, and even enhanced, before transmission to CD4+ lymphocytes. The role of DC-SIGN in viral retention and enhancement of infection is not fully understood and varies according to the cell line expressing the lectin. We studied here the mechanisms underlying this process. We focused our study on X4-tropic human immunodeficiency virus (HIV) strains, since they were widely believed not to replicate in iDCs. However, we first show that X4 HIV replicates covertly and slowly in iDCs. This is also the case in Raji-DC-SIGN cells, which are classically used to study HIV transmission. We used either single-cycle or replicative HIV and measured viral RT and replication to further demonstrate that transfer of incoming virions from iDCs or DC-SIGN+ cells occurs only on the short-term (i.e., a few hours after viral exposure). There is no long-term storage of original HIV particles in these cells. A few days after viral exposure, replicative viruses, and not single-cycle virions, are transmitted to CD4+ cells. The cell-type-dependent activity of DC-SIGN reflects the ability of HIV to replicate covertly in some cells, and not in others.",1
"Nobile, Cinzia, Petit, Caroline, Moris, Arnaud, Skrabal, Katharina, Abastado, Jean-Pierre, Mammano, Fabrizio, Schwartz, Olivier",2
Aged BALB/c mice as a model for increased severity of severe acute respiratory syndrome in elderly humans.,0
"Advanced age has repeatedly been identified as an independent correlate of adverse outcome and a predictor of mortality in cases of severe acute respiratory syndrome (SARS). SARS-associated mortality may exceed 50% for persons aged 60 years or older. Heightened susceptibility of the elderly to severe SARS and the ability of SARS coronavirus to replicate in mice led us to examine whether aged mice might be susceptible to disease. We report here that viral replication in aged mice was associated with clinical illness and pneumonia, demonstrating an age-related susceptibility to SARS disease in animals that parallels the human experience.",1
"Roberts, Anjeanette, Paddock, Christopher, Vogel, Leatrice, Butler, Emily, Zaki, Sherif, Subbarao, Kanta",2
Viremia and nasal and rectal shedding of rotavirus in gnotobiotic pigs inoculated with Wa human rotavirus.,0
"Respiratory symptoms with rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (Zheng et al., 1991, J. Med. Virol. 34:29-37). To investigate if attenuated and virulent human rotavirus (HRV) strains cause upper respiratory tract infections or viremia in gnotobiotic pigs, we inoculated them with attenuated or virulent HRV intranasally, intravenously, or orally or via feeding tube (gavage) and assayed virus shedding. After oral or intranasal inoculation with attenuated HRV, the pigs remained asymptomatic, but 79 to 95% shed virus nasally and 5 to 17% shed virus rectally. After inoculation by gavage, no pigs shed virus nasally or rectally, but all pigs seroconverted with antibodies to HRV. No viremia was detected through postinoculation day 10. Controls inoculated intranasally with nonreplicating rotavirus-like particles or mock inoculated did not shed virus. In contrast, 100% of pigs inoculated with virulent HRV (oral, intranasal, or gavage) developed diarrhea, shed virus nasally and rectally, and had viremia. The infectivity of sera from the viremic virulent HRV-inoculated pigs was confirmed by inoculating gnotobiotic pigs orally with pooled HRV-positive serum. Serum-inoculated pigs developed diarrhea and fecal and nasal virus shedding and seroconverted with serum and intestinal HRV antibodies. Pigs inoculated intravenously with serum or intestinal contents from the viremic virulent HRV-inoculated pigs developed diarrhea, virus shedding, and viremia, similar to the orally inoculated pigs. This study provides new evidence that virulent HRV causes transient viremia and upper respiratory tract infection in addition to gastrointestinal infection in gnotobiotic pigs, confirming previous reports of rotavirus antigenemia (Blutt et al., Lancet 362:1445-1449, 2003). Our data also suggest that intestinal infection might be initiated from the basolateral side of the epithelial cells via viremia. Additionally, virus shedding patterns indicate a different pathogenesis for attenuated versus virulent HRV.",1
"Azevedo, M S, Yuan, L, Jeong, K-I, Gonzalez, A, Nguyen, T V, Pouly, S, Gochnauer, M, Zhang, W, Azevedo, A, Saif, L J",2
ATPgammaS disrupts human immunodeficiency virus type 1 virion core integrity.,0
"Heat shock protein 70 (Hsp70) is incorporated within the membrane of primate lentiviral virions. Here we demonstrate that Hsp70 is also incorporated into oncoretroviral virions and that it remains associated with membrane-stripped human immunodeficiency virus type 1 (HIV-1) virion cores. To determine if Hsp70 promotes virion infectivity, we attempted to generate Hsp70-deficient virions with gag deletion mutations, Hsp70 transdominant mutants, or RNA interference, but these efforts were confounded, largely because they disrupt virion assembly. Given that polypeptide substrates are bound and released by Hsp70 in an ATP-hydrolytic reaction cycle, we supposed that incubation of HIV-1 virions with ATP would perturb Hsp70 interaction with substrates in the virion and thereby decrease infectivity. Treatment with ATP or ADP had no observable effect, but ATPgammaS and GTPgammaS, nucleotide triphosphate analogues resistant to Hsp70 hydrolysis, dramatically reduced the infectivity of HIV-1 and murine leukemia virus virions. ATPgammaS-treated virions were competent for fusion with susceptible target cells, but viral cDNA synthesis was inhibited to an extent that correlated with the magnitude of decrease in infectivity. Intravirion reverse transcription by HIV-1, simian immunodeficiency virus, or murine leukemia virus was also inhibited by ATPgammaS. The effects of ATPgammaS on HIV-1 reverse transcription appeared to be indirect, resulting from disruption of virion core morphology that was evident by transmission electron microscopy. Consistent with effects on capsid conformation, ATPgammaS-treated viruslike particles failed to saturate host antiviral restriction activity. Our observations support a model in which the catalytic activity of virion-associated Hsp70 is required to maintain structural integrity of the virion core.",1
"Gurer, Cagan, Höglund, Anders, Höglund, Stefan, Luban, Jeremy",2
Association of the influenza A virus RNA-dependent RNA polymerase with cellular RNA polymerase II.,0
"Transcription by the influenza virus RNA-dependent RNA polymerase is dependent on cellular RNA processing activities that are known to be associated with cellular RNA polymerase II (Pol II) transcription, namely, capping and splicing. Therefore, it had been hypothesized that transcription by the viral RNA polymerase and Pol II might be functionally linked. Here, we demonstrate for the first time that the influenza virus RNA polymerase complex interacts with the large subunit of Pol II via its C-terminal domain. The viral polymerase binds hyperphosphorylated forms of Pol II, indicating that it targets actively transcribing Pol II. In addition, immunofluorescence analysis is consistent with a new model showing that influenza virus polymerase accumulates at Pol II transcription sites. The present findings provide a framework for further studies to elucidate the mechanistic principles of transcription by a viral RNA polymerase and have implications for the regulation of Pol II activities in infected cells.",1
"Engelhardt, Othmar G, Smith, Matt, Fodor, Ervin",2
Amino acid changes in proteins 2B and 3A mediate rhinovirus type 39 growth in mouse cells.,0
"Many steps of viral replication are dependent on the interaction of viral proteins with host cell components. To identify rhinovirus proteins involved in such interactions, human rhinovirus 39 (HRV39), a virus unable to replicate in mouse cells, was adapted to efficient growth in mouse cells producing the viral receptor ICAM-1 (ICAM-L cells). Amino acid changes were identified in the 2B and 3A proteins of the adapted virus, RV39/L. Changes in 2B were sufficient to permit viral growth in mouse cells; however, changes in both 2B and 3A were required for maximal viral RNA synthesis in mouse cells. Examination of infected HeLa cells by electron microscopy demonstrated that human rhinoviruses induced the formation of cytoplasmic membranous vesicles, similar to those observed in cells infected with other picornaviruses. Vesicles were also observed in the cytoplasm of HRV39-infected mouse cells despite the absence of viral RNA replication. Synthesis of picornaviral nonstructural proteins 2C, 2BC, and 3A is known to be required for formation of membranous vesicles. We suggest that productive HRV39 infection is blocked in ICAM-L cells at a step posttranslation and prior to the formation of a functional replication complex. The observation that changes in HRV39 2B and 3A proteins lead to viral growth in mouse cells suggests that one or both of these proteins interact with host cell proteins to promote viral replication.",1
"Harris, Julie R, Racaniello, Vincent R",2
Few mutations in the 5' leader region mediate fitness recovery of debilitated human immunodeficiency type 1 viruses.,0
"Repeated bottleneck passages of RNA viruses result in fitness losses due to the accumulation of deleterious mutations. In contrast, repeated transfers of large virus populations result in exponential fitness increases. Human immunodeficiency virus type 1 (HIV-1) manifested a drastic fitness loss after a limited number of plaque-to-plaque transfers in MT-4 cells. An analysis of the mutations associated with fitness loss in four debilitated clones revealed mutation frequencies in gag that were threefold higher than those in env. We now show an increase in the fitness of the debilitated HIV-1 clones by repeated passages of large populations. An analysis of the entire genomic nucleotide sequences of these populations showed that few mutations, from two to seven per clone, mediated fitness recovery. Eight of the 20 mutations affected coding regions, mainly by the introduction of nonsynonymous mutations (75%). However, most of the mutations accumulated during fitness recovery (12 of 20) were located in the 5' untranslated leader region of the genome, and more specifically, in the primer binding site (PBS) loop. Two of the viruses incorporated the same mutation in the primer activation signal in the PBS loop, which is critical for the tRNA3Lys-mediated initiation of reverse transcription. Moreover, 25% of the mutations observed were reversions. This fact, together with the presence of a large proportion of nonsynonymous replacements, may disclose the operation, during large population passages, of strong positive selection for optimal HIV-1 replication, which seems to be primarily affected by binding of the tRNA to the PBS and the initiation of reverse transcription.",1
"Yuste, Eloísa, Bordería, Antonio V, Domingo, Esteban, López-Galíndez, Cecilio",2
T-cell growth transformation by herpesvirus saimiri is independent of STAT3 activation.,0
"Herpesvirus saimiri (saimirine herpesvirus 2) (HVS), a T-lymphotropic tumor virus, induces lymphoproliferative disease in several species of New World primates. In addition, strains of HVS subgroup C are able to transform T cells of Old World primates, including humans, to permanently growing T-cell lines. In concert with the Stp oncoprotein, the tyrosine kinase-interacting protein (Tip) of HVS C488 is required for T-cell transformation in vitro and lymphoma induction in vivo. Tip was previously shown to interact with the protein tyrosine kinase Lck. Constitutive activation of signal transducers and activators of transcription (STATs) has been associated with oncogenesis and has also been detected in HVS-transformed T-cell lines. Furthermore, Tip contains a putative consensus YXPQ binding motif for the SH2 (src homology 2) domains of STAT1 and STAT3. Tip tyrosine phosphorylation at this site was required for binding of STATs and induction of STAT-dependent transcription. Here we sought to address the relevance of STAT activation for transformation of human T cells by introducing a tyrosine-to-phenylalanine mutation in the YXPQ motif of Tip of HVS C488. Unexpectedly, the recombinant virus was still able to transform human T lymphocytes, but it had lost its capability to activate STAT3 as well as STAT1. This demonstrates that growth transformation by HVS is independent of STAT3 activation.",1
"Heck, Elke, Lengenfelder, Doris, Schmidt, Monika, Müller-Fleckenstein, Ingrid, Fleckenstein, Bernhard, Biesinger, Brigitte, Ensser, Armin",2
Regulation of translation by ribosome shunting through phosphotyrosine-dependent coupling of adenovirus protein 100k to viral mRNAs.,0
"Adenovirus simultaneously inhibits cap-dependent host cell mRNA translation while promoting the translation of its late viral mRNAs during infection. Studies previously demonstrated that tyrosine kinase activity plays a central role in the control of late adenovirus protein synthesis. The tyrosine kinase inhibitor genistein decreases late viral mRNA translation and prevents viral inhibition of cellular protein synthesis. Adenovirus protein 100k blocks cellular mRNA translation by disrupting the cap-initiation complex and promotes viral mRNA translation through an alternate mechanism known as ribosome shunting. 100k protein interaction with initiation factor eIF4G and the viral 5' noncoding region on viral late mRNAs, known as the tripartite leader, are both essential for ribosome shunting. We show that adenovirus protein 100k promotes ribosome shunting in a tyrosine phosphorylation-dependent manner. The primary sites of phosphorylated tyrosine on protein 100k were mapped and mutated, and two key sites are shown to be essential for protein 100k to promote ribosome shunting. Mutation of the two tyrosine phosphorylation sites in 100k protein does not impair interaction with initiation factor 4G, but it severely reduces association of 100k with tripartite leader mRNAs. 100k protein therefore promotes ribosome shunting and selective translation of viral mRNAs by binding specifically to the adenovirus tripartite leader in a phosphotyrosine-dependent manner.",1
"Xi, Qiaoran, Cuesta, Rafael, Schneider, Robert J",2
"Recruitment of CBP/p300, TATA-binding protein, and S8 to distinct regions at the N terminus of adenovirus E1A.",0
"The N-terminal region of the adenovirus (Ad) 12S E1A gene product targets several cellular proteins that are essential for the induction of S phase, cellular immortalization, cellular transformation, transcriptional repression, and transcriptional activation. The precise binding sites for these proteins, however, remain to be resolved. We therefore undertook an extensive site-directed mutagenesis approach to generate specific point mutants and to precisely map the binding sites for CBP, p300, TATA-binding protein (TBP), S4, S8, hGcn5, P/CAF, and Ran within the first 30 amino acids of the Ad5 12S E1A protein. We determined that although common residues within the N-terminal region can form partial binding sites for these proteins, point mutants were also generated that could discriminate between binding sites. These data indicate that AdE1A can target each of these proteins individually through distinct binding sites. It was evident, however, that the mutation of specific hydrophobic residues typically had the greatest effect upon AdE1A's ability to bind individual partners. Indeed, the mutation of L at positions 19 and 20 eliminated the ability of AdE1A to interact with any of the N-terminal binding proteins studied here. Interestingly, although TBP and S8 or CBP/p300 can exist as functional complexes, RNA interference revealed that the recruitment of either TBP, S8, or CBP/p300 to AdE1A was not dependent upon the expression of the other proteins. These data further indicate that AdE1A can target individual partner proteins in vivo and that it does not necessarily recruit these proteins indirectly as components of larger macromolecular complexes. Finally, we took advantage of the fine-mapping data to ascertain which proteins were targeted during the transformation process. Consistent with previous studies, CBP/p300 was found to be targeted by AdE1A during this process, although our data suggest that binding to other N-terminal proteins is also important for transformation.",1
"Rasti, Mozhgan, Grand, Roger J A, Mymryk, Joe S, Gallimore, Phillip H, Turnell, Andrew S",2
Identification of novel subgenomic RNAs and noncanonical transcription initiation signals of severe acute respiratory syndrome coronavirus.,0
"The expression of the genomic information of severe acute respiratory syndrome coronavirus (SARS CoV) involves synthesis of a nested set of subgenomic RNAs (sgRNAs) by discontinuous transcription. In SARS CoV-infected cells, 10 sgRNAs, including 2 novel ones, were identified, which were predicted to be functional in the expression of 12 open reading frames located in the 3' one-third of the genome. Surprisingly, one new sgRNA could lead to production of a truncated spike protein. Sequence analysis of the leader-body fusion sites of each sgRNA showed that the junction sequences and the corresponding transcription-regulatory sequence (TRS) are unique for each species of sgRNA and are consistent after virus passages. For the two novel sgRNAs, each used a variant of the TRS that has one nucleotide mismatch in the conserved hexanucleotide core (ACGAAC) in the TRS. Coexistence of both plus and minus strands of SARS CoV sgRNAs and evidence for derivation of the sgRNA core sequence from the body core sequence favor the model of discontinuous transcription during minus-strand synthesis. Moreover, one rare species of sgRNA has the junction sequence AAA, indicating that its transcription could result from a noncanonical transcription signal. Taken together, these results provide more insight into the molecular mechanisms of genome expression and subgenomic transcription of SARS CoV.",1
"Hussain, Snawar, Pan, Ji'an, Chen, Yu, Yang, Yalin, Xu, Jing, Peng, Yu, Wu, Ying, Li, Zhaoyang, Zhu, Ying, Tien, Po, Guo, Deyin",2
"Recombinant, live-attenuated tetravalent dengue virus vaccine formulations induce a balanced, broad, and protective neutralizing antibody response against each of the four serotypes in rhesus monkeys.",0
"Three tetravalent vaccine (TV) formulations of previously described monovalent dengue (DEN) virus vaccine candidates were compared to a tetravalent formulation of wild-type DEN viruses (T-wt) for replication in SCID mice transplanted with human liver cells (SCID-HuH-7) or for replication and immunogenicity in rhesus monkeys. TV-1 consists of recombinant DEN1, -2, -3, and -4, each with a 30-nucleotide deletion in the 3' untranslated region (Delta30). TV-2 consists of rDEN1Delta30, rDEN4Delta30, and two antigenic chimeric viruses, rDEN2/4Delta30 and rDEN3/4Delta30, both also bearing the Delta30 mutation. TV-3 consists of rDEN1Delta30, rDEN2Delta30, rDEN4Delta30, and a 10-fold higher dose of rDEN3/4Delta30. TV-1 and TV-2 were attenuated in SCID-HuH-7 mice with minimal interference in replication among the virus components. TV-1, -2, and -3 were attenuated in rhesus monkeys as measured by duration and peak of viremia. Each monkey immunized with TV-1 and TV-3 seroconverted to the four DEN components by day 28 with neutralization titers ranging from 1:52 to 1:273 and 1:59 to 1:144 for TV-1 and TV-3, respectively. TV-2 induced low antibody titers to DEN2 and DEN3, but a booster immunization after 4 months increased the neutralizing antibody titers to greater than 1:100 against each serotype and elicited broad neutralizing activity against 19 of 20 DEN subtypes. A single dose of TV-2 induced protection against wild-type DEN1, DEN3, and DEN4 challenge, but not DEN2. However, two doses of TV-2 or TV-3 induced protection against DEN2 challenge. Two tetravalent formulations, TV-2 and TV-3, possess properties of a successful DEN vaccine and can be considered for evaluation in clinical trials.",1
"Blaney, Joseph E, Matro, Jennifer M, Murphy, Brian R, Whitehead, Stephen S",2
Characterization of herpes simplex virus type 1 thymidine kinase mutants selected under a single round of high-dose brivudin.,0
"A broad variety of herpes simplex virus type 1 clones was selected under a single round of high-dose selection with brivudin. Mutations in the thymidine kinase (TK) genes consisted of 42% frameshift mutations within homopolymer repeats of G's and C's and single nucleotide substitutions (58%) that produced stop codons (Q261 and R281) or a new codon at the site of the substitution (A168T, R51W, G59W, G206R, R220H, Y239S, and T287 M). The A168T change, associated with an altered TK phenotype, proved to be the most commonly selected substitution. For the different mutants, a correlation between phenotype, genotype, and in vivo neurovirulence was observed.",1
"Andrei, Graciela, Balzarini, Jan, Fiten, Pierre, De Clercq, Erik, Opdenakker, Ghislain, Snoeck, Robert",2
Peptide mimetics of gamma interferon possess antiviral properties against vaccinia virus and other viruses in the presence of poxvirus B8R protein.,0
"We have developed peptide mimetics of gamma interferon (IFN-gamma) that play a direct role in the activation and nuclear translocation of STAT1alpha transcription factor. These mimetics do not act through recognition by the extracellular domain of IFN-gamma receptor but rather bind to the cytoplasmic domain of the receptor chain 1, IFNGR-1, and thereby initiate the cellular signaling. Thus, we hypothesized that these mimetics would bypass the poxvirus virulence factor B8R protein that binds to intact IFN-gamma and prevents its interaction with the receptor. Human and murine IFN-gamma mimetic peptides were introduced into an adenoviral vector for intracellular expression. Murine IFN-gamma mimetic peptide was also expressed via chemical synthesis with an attached lipophilic group for penetration of cell plasma membrane. In contrast to intact human IFN-gamma, the mimetics did not bind poxvirus B8R protein, a homolog of the IFN-gamma receptor extracellular domain. Expression of B8R protein in WISH cells did not block the antiviral effect of the mimetics against encephalomyocarditis or vesicular stomatitis virus, while the antiviral activity of human IFN-gamma was neutralized. Consistent with the antiviral activity, the upregulation of MHC class I molecules on WISH cells by the IFN-gamma mimetics was not affected by B8R protein, while IFN-gamma-induced upregulation was blocked. Finally, the mimetics, but not IFN-gamma, inhibited vaccinia virus replication in African green monkey kidney BSC-40 cells. The data presented demonstrate that small peptide mimetics of IFN-gamma can avoid the B8R virulence factor for poxviruses and, thus, are potential candidates for antivirals against smallpox virus.",1
"Ahmed, Chulbul M I, Burkhart, Marjorie A, Subramaniam, Prem S, Mujtaba, Mustafa G, Johnson, Howard M",2
Early T-cell responses to dengue virus epitopes in Vietnamese adults with secondary dengue virus infections.,0
"T-cell responses to dengue viruses may be important in both protective immunity and pathogenesis. This study of 48 Vietnamese adults with secondary dengue virus infections defined the breadth and magnitude of peripheral T-cell responses to 260 overlapping peptide antigens derived from a dengue virus serotype 2 (DV2) isolate. Forty-seven different peptides evoked significant gamma interferon enzyme-linked immunospot (ELISPOT) assay responses in 39 patients; of these, 34 peptides contained potentially novel T-cell epitopes. NS3 and particularly NS3200-324 were important T-cell targets. The breadth and magnitude of ELISPOT responses to DV2 peptides were independent of the infecting dengue virus serotype, suggesting that cross-reactive T cells dominate the acute response during secondary infection. Acute ELISPOT responses were weakly correlated with the extent of hemoconcentration in individual patients but not with the nadir of thrombocytopenia or overall clinical disease grade. NS3556-564 and Env414-422 were identified as novel HLA-A*24 and B*07-restricted CD8+ T-cell epitopes, respectively. Acute T-cell responses to natural variants of Env414-422 and NS3556-564 were largely cross-reactive and peaked during disease convalescence. The results highlight the importance of NS3 and cross-reactive T cells during acute secondary infection but suggest that the overall breadth and magnitude of the T-cell response is not significantly related to clinical disease grade.",1
"Simmons, Cameron P, Dong, Tao, Chau, Nguyen Vinh, Dung, Nguyen Thi Phuong, Chau, Tran Nguyen Bich, Thao, Le Thi Thu, Dung, Nguyen Thi, Hien, Tran Tinh, Rowland-Jones, Sarah, Farrar, Jeremy",2
Tumorigenic poxviruses up-regulate intracellular superoxide to inhibit apoptosis and promote cell proliferation.,0
"Tumorigenic leporipoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD1). The function of the orthologous myxoma virus M131R and Shope fibroma virus S131R gene products is uncertain, but they inhibit SOD1 activity by a process linked to binding its copper chaperone. Using a superoxide-sensitive dye (hydroethidine), we observed that virus infection increased intracellular superoxide levels in an M/S131R-dependent manner. To see whether this effect promotes infection, we deleted the Shope fibroma virus S131R gene and compared the clinical manifestations of wild-type and mutant virus infections in rabbits. S131RDelta virus produced significantly smaller fibroxanthosarcoma-like growths in vivo and, at a point where these growths were already receding, wild-type infections still showed extensive leukocyte infiltration, necrosis, and fibromatous cell proliferation. Coincidentally, whereas Jurkat cells are protected from mitochondria- and Fas-mediated apoptosis by wild-type myxoma virus in vitro, M131RDelta virus could not block Fas-initiated apoptosis as judged by DNA laddering, terminal deoxynucleotidyltransferase-mediated dUTP-fluorescein nick end labeling, and caspase 3 cleavage assays. These data suggest that tumorigenic poxviruses can modulate intracellular redox status to their advantage to stimulate infected cell growth and inhibit programmed cell death.",1
"Teoh, Melissa L T, Turner, Patricia V, Evans, David H",2
Characterization of a recombinant herpes simplex virus 1 designed to enter cells via the IL13Ralpha2 receptor of malignant glioma cells.,0
"Malignant glioma tumor cells in situ exhibit on their surfaces the interleukin 13 (IL-13) receptor designated IL13Ralpha2. To target herpes simplex virus 1 to this receptor, we constructed a recombinant virus (R5111) in which the known heparan sulfate binding sites in glycoproteins B and C were deleted and IL-13 was inserted into both glycoproteins C and D. We also transduced a baby hamster kidney cell line lacking the known viral receptors (J1-1) and Vero cells with a plasmid encoding IL13Ralpha2. The J1-1 derivative (J-13R) cell line is susceptible to and replicates the R5111 recombinant virus but not the wild-type parent virus. We report the following. (i) Expression of IL13Ralpha2 was rapidly lost from the surface of transduced cells grown in culture. The loss appeared to be related to ligands present in fetal bovine serum in the medium. None of the malignant glioma cell lines cultivated in vitro and tested to date exhibited the IL13Ralpha2 receptor. (ii) Soluble IL-13 but not IL-4 or IL-2 blocked the replication of R5111 recombinant virus in J-13R cells. (iii) The endocytosis inhibitor PD98059 blocked the replication in J1-1 cells of a mutant lacking glycoprotein D (gD-/-) but not the replication of R5111 in the J-13R cells. We conclude that R5111 enters cells via its interaction with the IL13Ralpha2 receptor in a manner that cannot be differentiated from the interaction of wild-type virus with its receptors.",1
"Zhou, Guoying, Roizman, Bernard",2
Inhibition of toll-like receptor 7- and 9-mediated alpha/beta interferon production in human plasmacytoid dendritic cells by respiratory syncytial virus and measles virus.,0
"Human plasmacytoid dendritic cells (PDC) are key sentinels alerting both innate and adaptive immune responses through production of huge amounts of alpha/beta interferon (IFN). IFN induction in PDC is triggered by outside-in signal transduction pathways through Toll-like receptor 7 (TLR7) and TLR9 as well as by recognition of cytosolic virus-specific patterns. TLR7 and TLR9 ligands include single-stranded RNA and CpG-rich DNA, respectively, as well as synthetic derivatives thereof which are being evaluated as therapeutic immune modulators promoting Th1 immune responses. Here, we identify the first viruses able to block IFN production by PDC. Both TLR-dependent and -independent IFN responses are abolished in human PDC infected with clinical isolates of respiratory syncytial virus (RSV), RSV strain A2, and measles virus Schwarz, in contrast to RSV strain Long, which we previously identified as a potent IFN inducer in human PDC (Hornung et al., J. Immunol. 173:5935-5943, 2004). Notably, IFN synthesis of PDC activated by the TLR7 and TLR9 agonists resiquimod (R848) and CpG oligodeoxynucleotide 2216 is switched off by subsequent infection by RSV A2 and measles virus. The capacity of RSV and measles virus of human PDC to shut down IFN production should contribute to the characteristic features of these viruses, such as Th2-biased immune pathology, immune suppression, and superinfection.",1
"Schlender, Jörg, Hornung, Veit, Finke, Stefan, Günthner-Biller, Margit, Marozin, Sabrina, Brzózka, Krzysztof, Moghim, Sharareh, Endres, Stefan, Hartmann, Gunther, Conzelmann, Karl-Klaus",2
Induction of lytic Epstein-Barr virus (EBV) infection by synergistic action of rituximab and dexamethasone renders EBV-positive lymphoma cells more susceptible to ganciclovir cytotoxicity in vitro and in vivo.,0
The purposeful induction of the lytic form of Epstein-Barr virus (EBV) infection combined with ganciclovir (GCV) treatment has been advocated as a novel strategy for EBV-positive B-cell lymphoma. We demonstrated that rituximab had a synergistic effect with dexamethasone on induction of the lytic EBV infection in CD20-positive lymphoma cells. Addition of GCV to the dexamethasone/rituximab-treated cells was more effective than dexamethasone/rituximab alone in killing EBV-positive lymphoma cells in vitro and in lymphoma-bearing nude mice but not in EBV-negative cells. These data suggest that induction of the lytic EBV infection with dexamethasone/rituximab in combination with GCV could be a potential virally targeted therapy for EBV-associated B-cell lymphoma.,1
"Daibata, Masanori, Bandobashi, Kentaro, Kuroda, Masayuki, Imai, Shosuke, Miyoshi, Isao, Taguchi, Hirokuni",2
Array analysis of simian varicella virus gene transcription in productively infected cells in tissue culture.,0
"Simian varicella virus (SVV) is a neurotropic alphaherpesvirus of monkeys that is a model for varicella pathogenesis and latency. Like human varicella-zoster virus (VZV), SVV causes chicken pox (varicella), becomes latent in ganglia along the entire neuraxis, and reactivates to produce shingles (zoster). We developed macroarrays to determine the extent of viral transcription from all 70 predicted SVV open reading frames (ORFs) in infected cells in tissue culture. Cloned fragments (200 to 400 bp) from the 5' and 3' ends of each ORF were PCR amplified, quantitated, spotted onto nylon membranes, and fixed by UV cross-linking. Using a cDNA probe prepared from poly(A)+ RNA extracted from SVV-infected Vero cells at the height of the cytopathic effect (3 days after infection) and chemiluminescence for detection, transcripts corresponding to all SVV ORFs were identified. The abundance of each SVV transcript was compared with that previously demonstrated for VZV in infected tissue culture cells.",1
"Deitch, Steven B, Gilden, Donald H, Wellish, Mary, Smith, John, Cohrs, Randall J, Mahalingam, Ravi",2
Potential of equine herpesvirus 1 as a vector for immunization.,0
"Key problems using viral vectors for vaccination and gene therapy are antivector immunity, low transduction efficiencies, acute toxicity, and limited capacity to package foreign genetic information. It could be demonstrated that animal and human cells were efficiently transduced with equine herpesvirus 1 (EHV-1) reconstituted from viral DNA maintained and manipulated in Escherichia coli. Between 13 and 23% of primary human CD3+, CD4+, CD8+, CD11b+, and CD19+ cells and more than 70% of CD4+ MT4 cells or various human tumor cell lines (MeWo, Huh7, HeLa, 293T, or H1299) could be transduced with one infectious unit of EHV-1 per cell. After intranasal instillation of EHV-1 into mice, efficient transgene expression in lungs was detectable. Successful immunization using EHV-1 was shown after delivery of the human immunodeficiency virus type 1 Pr55gag precursor by the induction of a Gag-specific CD8+ immune response in mice. Because EHV-1 was not neutralized by human sera containing high titers of antibodies directed against human herpesviruses 1 to 5, it is concluded that this animal herpesvirus has enormous potential as a vaccine vector, because it is able to efficiently transduce a variety of animal and human cells, has high DNA packaging capacity, and can conveniently be maintained and manipulated in prokaryotic cells.",1
"Trapp, Sascha, von Einem, Jens, Hofmann, Helga, Köstler, Josef, Wild, Jens, Wagner, Ralf, Beer, Martin, Osterrieder, Nikolaus",2
Viral RNA is required for the association of APOBEC3G with human immunodeficiency virus type 1 nucleoprotein complexes.,0
APOBEC3G (APO3G) is a host cytidine deaminase that is incorporated into human immunodeficiency virus type 1 (HIV-1) particles. We report here that viral RNA promotes stable association of APO3G with HIV-1 nucleoprotein complexes (NPC). A target sequence located within the 5'-untranslated region of the HIV-1 RNA was identified to be necessary and sufficient for efficient APO3G packaging. Fine mapping revealed a sequence normally involved in viral genomic RNA dimerization and Gag binding to be important for APO3G packaging and association with viral NPC. Our data suggest that packaging of APO3G into HIV-1 NPC is enhanced by viral RNA.,1
"Khan, Mohammad A, Kao, Sandra, Miyagi, Eri, Takeuchi, Hiroaki, Goila-Gaur, Ritu, Opi, Sandrine, Gipson, Clay L, Parslow, Tristram G, Ly, Hinh, Strebel, Klaus",2
Initiation of protein synthesis in bacteria.,0
"Valuable information on translation initiation is available from biochemical data and recently solved structures. We present a detailed description of current knowledge about the structure, function, and interactions of the individual components involved in bacterial translation initiation. The first section describes the ribosomal features relevant to the initiation process. Subsequent sections describe the structure, function, and interactions of the mRNA, the initiator tRNA, and the initiation factors IF1, IF2, and IF3. Finally, we provide an overview of mechanisms of regulation of the translation initiation event. Translation occurs on ribonucleoprotein complexes called ribosomes. The ribosome is composed of a large subunit and a small subunit that hold the activities of peptidyltransfer and decode the triplet code of the mRNA, respectively. Translation initiation is promoted by IF1, IF2, and IF3, which mediate base pairing of the initiator tRNA anticodon to the mRNA initiation codon located in the ribosomal P-site. The mechanism of translation initiation differs for canonical and leaderless mRNAs, since the latter is dependent on the relative level of the initiation factors. Regulation of translation occurs primarily in the initiation phase. Secondary structures at the mRNA ribosomal binding site (RBS) inhibit translation initiation. The accessibility of the RBS is regulated by temperature and binding of small metabolites, proteins, or antisense RNAs. The future challenge is to obtain atomic-resolution structures of complete initiation complexes in order to understand the mechanism of translation initiation in molecular detail.",1
"Laursen, Brian Søgaard, Sørensen, Hans Peter, Mortensen, Kim Kusk, Sperling-Petersen, Hans Uffe",2
Signaling by target of rapamycin proteins in cell growth control.,0
"Target of rapamycin (TOR) proteins are members of the phosphatidylinositol kinase-related kinase (PIKK) family and are highly conserved from yeast to mammals. TOR proteins integrate signals from growth factors, nutrients, stress, and cellular energy levels to control cell growth. The ribosomal S6 kinase 1 (S6K) and eukaryotic initiation factor 4E binding protein 1(4EBP1) are two cellular targets of TOR kinase activity and are known to mediate TOR function in translational control in mammalian cells. However, the precise molecular mechanism of TOR regulation is not completely understood. One of the recent breakthrough studies in TOR signaling resulted in the identification of the tuberous sclerosis complex gene products, TSC1 and TSC2, as negative regulators for TOR signaling. Furthermore, the discovery that the small GTPase Rheb is a direct downstream target of TSC1-TSC2 and a positive regulator of the TOR function has significantly advanced our understanding of the molecular mechanism of TOR activation. Here we review the current understanding of the regulation of TOR signaling and discuss its function as a signaling nexus to control cell growth during normal development and tumorigenesis.",1
"Inoki, Ken, Ouyang, Hongjiao, Li, Yong, Guan, Kun-Liang",2
"Cellulase, clostridia, and ethanol.",0
"Biomass conversion to ethanol as a liquid fuel by the thermophilic and anaerobic clostridia offers a potential partial solution to the problem of the world's dependence on petroleum for energy. Coculture of a cellulolytic strain and a saccharolytic strain of Clostridium on agricultural resources, as well as on urban and industrial cellulosic wastes, is a promising approach to an alternate energy source from an economic viewpoint. This review discusses the need for such a process, the cellulases of clostridia, their presence in extracellular complexes or organelles (the cellulosomes), the binding of the cellulosomes to cellulose and to the cell surface, cellulase genetics, regulation of their synthesis, cocultures, ethanol tolerance, and metabolic pathway engineering for maximizing ethanol yield.",1
"Demain, Arnold L, Newcomb, Michael, Wu, J H David",2
Detection of and response to signals involved in host-microbe interactions by plant-associated bacteria.,0
"Diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. Detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. This concept was first demonstrated for the members of the family Rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and animal hosts. The family Rhizobiaceae includes various genera of rhizobia as well as species of Agrobacterium. Rhizobia are symbionts of legumes, which fix nitrogen within root nodules, while Agrobacterium tumefaciens is a pathogen that causes crown gall tumors on a wide variety of plants. The plant-released signals that are recognized by these bacteria are low-molecular-weight, diffusible molecules and are detected by the bacteria through specific receptor proteins. Similar phenomena are observed with other plant pathogens, including Pseudomonas syringae, Ralstonia solanacearum, and Erwinia spp., although here the signals and signal receptors are not as well defined. In some cases, nutritional conditions such as iron limitation or the lack of nitrogen sources seem to provide a significant cue. While much has been learned about the process of host detection over the past 20 years, our knowledge is far from being complete. The complex nature of the plant-microbe interactions makes it extremely challenging to gain a comprehensive picture of host detection in natural environments, and thus many signals and signal recognition systems remain to be described.",1
"Brencic, Anja, Winans, Stephen C",2
Diversifying carotenoid biosynthetic pathways by directed evolution.,0
"Microorganisms and plants synthesize a diverse array of natural products, many of which have proven indispensable to human health and well-being. Although many thousands of these have been characterized, the space of possible natural products--those that could be made biosynthetically--remains largely unexplored. For decades, this space has largely been the domain of chemists, who have synthesized scores of natural product analogs and have found many with improved or novel functions. New natural products have also been made in recombinant organisms, via engineered biosynthetic pathways. Recently, methods inspired by natural evolution have begun to be applied to the search for new natural products. These methods force pathways to evolve in convenient laboratory organisms, where the products of new pathways can be identified and characterized in high-throughput screening programs. Carotenoid biosynthetic pathways have served as a convenient experimental system with which to demonstrate these ideas. Researchers have mixed, matched, and mutated carotenoid biosynthetic enzymes and screened libraries of these ""evolved"" pathways for the emergence of new carotenoid products. This has led to dozens of new pathway products not previously known to be made by the assembled enzymes. These new products include whole families of carotenoids built from backbones not found in nature. This review details the strategies and specific methods that have been employed to generate new carotenoid biosynthetic pathways in the laboratory. The potential application of laboratory evolution to other biosynthetic pathways is also discussed.",1
"Umeno, Daisuke, Tobias, Alexander V, Arnold, Frances H",2
Pathogenesis of Afa/Dr diffusely adhering Escherichia coli.,0
"Over the last few years, dramatic increases in our knowledge about diffusely adhering Escherichia coli (DAEC) pathogenesis have taken place. The typical class of DAEC includes E. coli strains harboring AfaE-I, AfaE-II, AfaE-III, AfaE-V, Dr, Dr-II, F1845, and NFA-I adhesins (Afa/Dr DAEC); these strains (i) have an identical genetic organization and (ii) allow binding to human decay-accelerating factor (DAF) (Afa/Dr(DAF) subclass) or carcinoembryonic antigen (CEA) (Afa/Dr(CEA) subclass). The atypical class of DAEC includes two subclasses of strains; the atypical subclass 1 includes E. coli strains that express AfaE-VII, AfaE-VIII, AAF-I, AAF-II, and AAF-III adhesins, which (i) have an identical genetic organization and (ii) do not bind to human DAF, and the atypical subclass 2 includes E. coli strains that harbor Afa/Dr adhesins or others adhesins promoting diffuse adhesion, together with pathogenicity islands such as the LEE pathogenicity island (DA-EPEC). In this review, the focus is on Afa/Dr DAEC strains that have been found to be associated with urinary tract infections and with enteric infection. The review aims to provide a broad overview and update of the virulence aspects of these intriguing pathogens. Epidemiological studies, diagnostic techniques, characteristic molecular features of Afa/Dr operons, and the respective role of Afa/Dr adhesins and invasins in pathogenesis are described. Following the recognition of membrane-bound receptors, including type IV collagen, DAF, CEACAM1, CEA, and CEACAM6, by Afa/Dr adhesins, activation of signal transduction pathways leads to structural and functional injuries at brush border and junctional domains and to proinflammatory responses in polarized intestinal cells. In addition, uropathogenic Afa/Dr DAEC strains, following recognition of beta(1) integrin as a receptor, enter epithelial cells by a zipper-like, raft- and microtubule-dependent mechanism. Finally, the presence of other, unknown virulence factors and the way that an Afa/Dr DAEC strain emerges from the human intestinal microbiota as a ""silent pathogen"" are discussed.",1
"Servin, Alain L",2
Subversion mechanisms by which Leishmania parasites can escape the host immune response: a signaling point of view.,0
"The obligate intracellular parasite Leishmania must survive the antimicrobial activities of its host cell, the macrophage, and prevent activation of an effective immune response. In order to do this, it has developed numerous highly successful strategies for manipulating activities, including antigen presentation, nitric oxide and oxygen radical generation, and cytokine production. This is generally the result of interactions between Leishmania cell surface molecules, particularly gp63 and LPG, and less well identified macrophage surface receptors, causing the distortion of specific intracellular signaling cascades. We describe some of the signaling pathways and intermediates that are repressed in infected cells, including JAK/STAT, Ca(2+)-dependent protein kinase C (PKC) isoforms, and mitogen-activated protein kinases (especially ERK1/2), and proteasome-mediated transcription factor degradation. We also discuss protein tyrosine phosphatases (particularly SHP-1), intracellular Ca2+, Ca(2+)-independent PKC, ceramide, and the suppressors of cytokine signaling family of repressors, which are all reported to be activated following infection, and the role of parasite-secreted cysteine proteases.",1
"Olivier, Martin, Gregory, David J, Forget, Geneviève",2
Metallo-beta-lactamases: the quiet before the storm?,0
"The ascendancy of metallo-beta-lactamases within the clinical sector, while not ubiquitous, has nonetheless been dramatic; some reports indicate that nearly 30% of imipenem-resistant Pseudomonas aeruginosa strains possess a metallo-beta-lactamase. Acquisition of a metallo-beta-lactamase gene will invariably mediate broad-spectrum beta-lactam resistance in P. aeruginosa, but the level of in vitro resistance in Acinetobacter spp. and Enterobacteriaceae is less dependable. Their clinical significance is further embellished by their ability to hydrolyze all beta-lactams and by the fact that there is currently no clinical inhibitor, nor is there likely to be for the foreseeable future. The genes encoding metallo-beta-lactamases are often procured by class 1 (sometimes class 3) integrons, which, in turn, are embedded in transposons, resulting in a highly transmissible genetic apparatus. Moreover, other gene cassettes within the integrons often confer resistance to aminoglycosides, precluding their use as an alternative treatment. Thus far, the metallo-beta-lactamases encoded on transferable genes include IMP, VIM, SPM, and GIM and have been reported from 28 countries. Their rapid dissemination is worrisome and necessitates the implementation of not just surveillance studies but also metallo-beta-lactamase inhibitor studies securing the longevity of important anti-infectives.",1
"Walsh, Timothy R, Toleman, Mark A, Poirel, Laurent, Nordmann, Patrice",2
Clostridium difficile toxins: mechanism of action and role in disease.,0
"As the leading cause of hospital-acquired diarrhea, Clostridium difficile colonizes the large bowel of patients undergoing antibiotic therapy and produces two toxins, which cause notable disease pathologies. These two toxins, TcdA and TcdB, are encoded on a pathogenicity locus along with negative and positive regulators of their expression. Following expression and release from the bacterium, TcdA and TcdB translocate to the cytosol of target cells and inactivate small GTP-binding proteins, which include Rho, Rac, and Cdc42. Inactivation of these substrates occurs through monoglucosylation of a single reactive threonine, which lies within the effector-binding loop and coordinates a divalent cation critical to binding GTP. By glucosylating small GTPases, TcdA and TcdB cause actin condensation and cell rounding, which is followed by death of the cell. TcdA elicits effects primarily within the intestinal epithelium, while TcdB has a broader cell tropism. Important advances in the study of these toxins have been made in the past 15 years, and these are detailed in this review. The domains, subdomains, and residues of these toxins important for receptor binding and enzymatic activity have been elegantly studied and are highlighted herein. Furthermore, there have been major advances in defining the role of these toxins in modulating the inflammatory events involving the disruption of cell junctions, neuronal activation, cytokine production, and infiltration by polymorphonuclear cells. Collectively, the present review provides a comprehensive update on TcdA and TcdB's mechanism of action as well as the role of these toxins in disease.",1
"Voth, Daniel E, Ballard, Jimmy D",2
"Molecular pathogenesis, epidemiology, and clinical manifestations of respiratory infections due to Bordetella pertussis and other Bordetella subspecies.",0
"Bordetella respiratory infections are common in people (B. pertussis) and in animals (B. bronchiseptica). During the last two decades, much has been learned about the virulence determinants, pathogenesis, and immunity of Bordetella. Clinically, the full spectrum of disease due to B. pertussis infection is now understood, and infections in adolescents and adults are recognized as the reservoir for cyclic outbreaks of disease. DTaP vaccines, which are less reactogenic than DTP vaccines, are now in general use in many developed countries, and it is expected that the expansion of their use to adolescents and adults will have a significant impact on reducing pertussis and perhaps decrease the circulation of B. pertussis. Future studies should seek to determine the cause of the unique cough which is associated with Bordetella respiratory infections. It is also hoped that data gathered from molecular Bordetella research will lead to a new generation of DTaP vaccines which provide greater efficacy than is provided by today's vaccines.",1
"Mattoo, Seema, Cherry, James D",2
Diagnosis and management of pediatric urinary tract infections.,0
"Urinary tract infection (UTI) is among the most commonly diagnosed bacterial infections of childhood. Although frequently encountered and well researched, diagnosis and management of UTI continue to be a controversial issue with many challenges for the clinician. Prevalence studies have shown that UTI may often be missed on history and physical examination, and the decision to screen for UTI must balance the risk for missed infections with the cost and inconvenience of testing. Interpretation of rapid diagnostic tests and culture is complicated by issues of contamination, false test results, and asymptomatic colonization of the urinary tract with nonpathogenic bacteria. The appropriate treatment of UTI has been controversial and has become more complex with the emergence of resistance to commonly used antibiotics. Finally, the anatomic evaluation and long-term management of a child after a UTI have been based on limited evidence, and newer studies question some of the tenets of prior recommendations. The goal of this review is to provide an up-to-date summary of the literature with particular attention to practical questions about diagnosis and management for the clinician.",1
"Zorc, Joseph J, Kiddoo, Darcie A, Shaw, Kathy N",2
"Melioidosis: epidemiology, pathophysiology, and management.",0
"Melioidosis, caused by the gram-negative saprophyte Burkholderia pseudomallei, is a disease of public health importance in southeast Asia and northern Australia that is associated with high case-fatality rates in animals and humans. It has the potential for epidemic spread to areas where it is not endemic, and sporadic case reports elsewhere in the world suggest that as-yet-unrecognized foci of infection may exist. Environmental determinants of this infection, apart from a close association with rainfall, are yet to be elucidated. The sequencing of the genome of a strain of B. pseudomallei has recently been completed and will help in the further identification of virulence factors. The presence of specific risk factors for infection, such as diabetes, suggests that functional neutrophil defects are important in the pathogenesis of melioidosis; other studies have defined virulence factors (including a type III secretion system) that allow evasion of killing mechanisms by phagocytes. There is a possible role for cell-mediated immunity, but repeated environmental exposure does not elicit protective humoral or cellular immunity. A vaccine is under development, but economic constraints may make vaccination an unrealistic option for many regions of endemicity. Disease manifestations are protean, and no inexpensive, practical, and accurate rapid diagnostic tests are commercially available; diagnosis relies on culture of the organism. Despite the introduction of ceftazidime- and carbapenem-based intravenous treatments, melioidosis is still associated with a significant mortality attributable to severe sepsis and its complications. A long course of oral eradication therapy is required to prevent relapse. Studies exploring the role of preventative measures, earlier clinical identification, and better management of severe sepsis are required to reduce the burden of this disease.",1
"Cheng, Allen C, Currie, Bart J",2
Isolation of lactococcal prolate phage-phage recombinants by an enrichment strategy reveals two novel host range determinants.,0
"Virulent lactococcal prolate (or c2-like) phages are the second most common phage group that causes fermentation failure in the dairy industry. We have mapped two host range determinants in two lactococcal prolate phages, c2 and 923, for the host strains MG1363 and 112. Each phage replicates on only one of the two host strains: c2 on MG1363 and 923 on 112. Phage-phage recombinants that replicated on both strains were isolated by a new method that does not require direct selection but rather employs an enrichment protocol. After initial mixed infection of strain 112, two rotations, the first of which was carried out on strain MG1363 and the second on 112, permitted continuous amplification of double-plating recombinants while rendering one of the parent phages unamplified in each of the two rotations. Mapping of the recombination endpoints showed that the presence of the N-terminal two-thirds of the tail protein L10 of phage c2 and a 1,562-bp cosR-terminal fragment of phage 923 genome overcame blocks of infection in strains MG1363 and 112, respectively. Both infection inhibition mechanisms act at the stage of DNA entry; in strain MG1363, the infection block acts early, before phage DNA enters the cytoplasm, and in strain 112, it acts late, after most of the DNA has entered the cell but before it undergoes cos-end ligation. These are the first reported host range determinants in bacteriophage of lactic acid bacteria required for overcoming inhibition of infection at the stage of DNA entry and cos-end ligation.",1
"Rakonjac, Jasna, O'Toole, Paul W, Lubbers, Mark",2
Plasmid-encoded regulator of extracellular proteases in Bacillus anthracis.,0
"Bacillus anthracis Sterne cured of the pXO1 plasmid had enhanced secreted protease activity during the postexponential phase but no change in hemolytic or lecithinase activities. A zymogen profile revealed at least six proteases, including serine, metal, and perhaps cysteine types. There were similar amounts of protease secreted by the closely related species Bacillus cereus and Bacillus thuringiensis, but the patterns differed. Among the pXO1 plasmid-encoded proteins, there is a tetratricopeptide protein designated Cot43 that is related to the Rap proteins of Bacillus subtilis and the PlcR pleiotropic regulator of secreted enzymes and toxins in B. thuringiensis. A disruption of the cot43 gene resulted in overproduction of several proteases to a somewhat greater extent than in the plasmid-cured strain. Transformation of either of these strains with a clone of the cot43 gene resulted in the inhibition of accumulation of some of the proteases and induction of at least one. On the basis of lacZ fusions, transcription of the cot43 gene increased in late exponential cells at the time of protease accumulation. The expression of lacZ fusions to the upstream regions of two B. anthracis extracellular protease genes was greater in the strain with the disruption of cot43 than in the Sterne strain, indicating regulation at the level of transcription. In B. anthracis, a pXO1 plasmid-encoded protein directly modulates or indirectly regulates the transcription of genes for several chromosomally encoded extracellular proteases.",1
"Aronson, Arthur I, Bell, Chris, Fulroth, Ben",2
Staphylococcus intermedius produces a functional agr autoinducing peptide containing a cyclic lactone.,0
"The agr system is a global regulator of accessory functions in staphylococci, including genes encoding exoproteins involved in virulence. The agr locus contains a two-component signal transduction module that is activated by an autoinducing peptide (AIP) encoded within the agr locus and is conserved throughout the genus. The AIP has an unusual partially cyclic structure that is essential for function and that, in all but one case, involves an internal thiolactone bond between a conserved cysteine and the C-terminal carboxyl group. The exceptional case is a strain of Staphylococcus intermedius that has a serine in place of the conserved cysteine. We demonstrate here that the S. intermedius AIP is processed by the S. intermedius AgrB protein to generate a cyclic lactone, that it is an autoinducer as well as a cross-inhibitor, and that all of five other S. intermedius strains examined also produce serine-containing AIPs.",1
"Ji, Guangyong, Pei, Wuhong, Zhang, Linsheng, Qiu, Rongde, Lin, Jianqun, Benito, Yvonne, Lina, Gerard, Novick, Richard P",2
Alternative splicing produces two endoglucanases with one or two carbohydrate-binding modules in Mucor circinelloides.,0
"We previously cloned three endoglucanase genes, rce1, rce2, and rce3, that were isolated from Rhizopus oryzae as the first cellulase genes from a member of the subdivision Zygomycota. In this study, two cDNAs homologous to the rce1 gene, designated the mce1 and mce2 cDNAs, were cloned from Mucor circinelloides, a member of the subdivision Zygomycota. The mce1 cDNA encoded an endoglucanase (family 45 glycoside hydrolase) having one carbohydrate-binding module (CBM), designated MCE1, and the mce2 cDNA encoded the same endoglucanase having two tandem repeated CBMs, designated MCE2. The two cDNAs contained the same sequences but with a 147-bp insertion. The corresponding genomic mce gene consisted of four exons. The mce1 cDNA was created from exons 1, 3, and 4, and the mce2 cDNA was created from exons 1, 2, 3, and 4. These results indicate that the mce1 and mce2 cDNAs were created from one genomic mce gene by alternative splicing. MCE1 and MCE2, purified to apparent homogeneity from the culture supernatant of M. circinelloides, had molecular masses of 43 and 47 kDa, respectively. The carboxymethyl cellulase specific activity of MCE2 was almost the same as that of MCE1, whereas the Avicelase specific activity of MCE2 was two times higher than that of MCE1. Furthermore, MCE2, whose two tandem CBMs might be more effective for degradation of crystalline cellulose than one CBM, was secreted only at an early culture stage when crystalline cellulose was abundant.",1
"Baba, Yuko, Shimonaka, Atsushi, Koga, Jinichiro, Kubota, Hidetoshi, Kono, Toshiaki",2
A glimpse into the expanded genome content of Vibrio cholerae through identification of genes present in environmental strains.,0
"Vibrio cholerae has multiple survival strategies which are reflected both in its broad distribution in many aquatic environments and its high genotypic diversity. To obtain additional information regarding the content of the V. cholerae genome, suppression subtractive hybridization (SSH) was used to prepare libraries of DNA sequences from two southern California coastal isolates which are divergent or absent in the clinical strain V. cholerae O1 El Tor N16961. More than 1,400 subtracted clones were sequenced. This revealed the presence of novel sequences encoding functions related to cell surface structures, transport, metabolism, signal transduction, luminescence, mobile elements, stress resistance, and virulence. Flanking sequence information was determined for loci of interest, and the distribution of these sequences was assessed for a collection of V. cholerae strains obtained from southern California and Mexican environments. This led to the surprising observation that sequences related to the toxin genes toxA, cnf1, and exoY are widespread and more common in these strains than those of the cholera toxin genes which are a hallmark of the pandemic strains of V. cholerae. Gene transfer among these strains could be facilitated by a 4.9-kbp plasmid discovered in one isolate, which possesses similarity to plasmids from other environmental vibrios. By investigating some of the nucleotide sequence basis for V. cholerae genotypic diversity, DNA fragments have been uncovered which could promote survival in coastal environments. Furthermore, a set of genes has been described which could be involved in as yet undiscovered interactions between V. cholerae and eukaryotic organisms.",1
"Purdy, Alexandra, Rohwer, Forest, Edwards, Rob, Azam, Farooq, Bartlett, Douglas H",2
The soluble NAD+-Reducing [NiFe]-hydrogenase from Ralstonia eutropha H16 consists of six subunits and can be specifically activated by NADPH.,0
"The soluble [NiFe]-hydrogenase (SH) of the facultative lithoautotrophic proteobacterium Ralstonia eutropha H16 has up to now been described as a heterotetrameric enzyme. The purified protein consists of two functionally distinct heterodimeric moieties. The HoxHY dimer represents the hydrogenase module, and the HoxFU dimer constitutes an NADH-dehydrogenase. In the bimodular form, the SH mediates reduction of NAD(+) at the expense of H(2). We have purified a new high-molecular-weight form of the SH which contains an additional subunit. This extra subunit was identified as the product of hoxI, a member of the SH gene cluster (hoxFUYHWI). Edman degradation, in combination with protein sequencing of the SH high-molecular-weight complex, established a subunit stoichiometry of HoxFUYHI(2). Cross-linking experiments indicated that the two HoxI subunits are the closest neighbors. The stability of the hexameric SH depended on the pH and the ionic strength of the buffer. The tetrameric form of the SH can be instantaneously activated with small amounts of NADH but not with NADPH. The hexameric form, however, was also activated by adding small amounts of NADPH. This suggests that HoxI provides a binding domain for NADPH. A specific reaction site for NADPH adds to the list of similarities between the SH and mitochondrial NADH:ubiquinone oxidoreductase (Complex I).",1
"Burgdorf, Tanja, van der Linden, Eddy, Bernhard, Michael, Yin, Qing Yuan, Back, Jaap W, Hartog, Aloysius F, Muijsers, Anton O, de Koster, Chris G, Albracht, Simon P J, Friedrich, Bärbel",2
Evidence for autotrophic CO2 fixation via the reductive tricarboxylic acid cycle by members of the epsilon subdivision of proteobacteria.,0
"Based on 16S rRNA gene surveys, bacteria of the epsilon subdivision of proteobacteria have been identified to be important members of microbial communities in a variety of environments, and quite a few have been demonstrated to grow autotrophically. However, no information exists on what pathway of autotrophic carbon fixation these bacteria might use. In this study, Thiomicrospira denitrificans and Candidatus Arcobacter sulfidicus, two chemolithoautotrophic sulfur oxidizers of the epsilon subdivision of proteobacteria, were examined for activities of the key enzymes of the known autotrophic CO(2) fixation pathways. Both organisms contained activities of the key enzymes of the reductive tricarboxylic acid cycle, ATP citrate lyase, 2-oxoglutarate:ferredoxin oxidoreductase, and pyruvate:ferredoxin oxidoreductase. Furthermore, no activities of key enzymes of other CO(2) fixation pathways, such as the Calvin cycle, the reductive acetyl coenzyme A pathway, and the 3-hydroxypropionate cycle, could be detected. In addition to the key enzymes, the activities of the other enzymes involved in the reductive tricarboxylic acid cycle could be measured. Sections of the genes encoding the alpha- and beta-subunits of ATP citrate lyase could be amplified from both organisms. These findings represent the first direct evidence for the operation of the reductive tricarboxylic acid cycle for autotrophic CO(2) fixation in epsilon-proteobacteria. Since epsilon-proteobacteria closely related to these two organisms are important in many habitats, such as hydrothermal vents, oxic-sulfidic interfaces, or oilfields, these results suggest that autotrophic CO(2) fixation via the reductive tricarboxylic acid cycle might be more important than previously considered.",1
"Hügler, Michael, Wirsen, Carl O, Fuchs, Georg, Taylor, Craig D, Sievert, Stefan M",2
"Novel roles of ohrR-ohr in Xanthomonas sensing, metabolism, and physiological adaptive response to lipid hydroperoxide.",0
"Lipid hydroperoxides are highly toxic to biological systems. Here, the Xanthomonas campestris pv. phaseoli sensing and protective systems against linoleic hydroperoxide (LOOH) were investigated by examining the phenotypes, biochemical and regulatory characteristics of various Xanthomonas mutants in known peroxide resistance pathways. Analysis of LOOH resistance levels indicates that both alkyl hydroperoxide reductase (AhpC) and organic hydroperoxide resistance enzyme (Ohr) have important and nonredundant roles in the process. Nonetheless, inactivation of ohr leads to a marked reduction in LOOH resistance levels. The regulatory characteristics of an ohr mutant add further support to its primary role in LOOH protection. Northern analysis shows that LOOH had differential effects on induction of ahpC and ohr expression with the latter being more sensitive to the inducer. Analysis of the ahpC and ohr promoters confirmed that the LOOH-dependent induction of these promoters is mediated by the transcription regulators OxyR and OhrR, respectively. Using the in vivo promoter assays and the in vitro gel mobility shift assay, we show that LOOH directly oxidized OhrR at the sensing residue Cys-22 leading to its inactivation. In addition, physiological analysis shows that pretreatment of X. campestris pv. phaseoli with a sublethal dose of LOOH induced high levels of resistance to subsequent exposure to lethal concentrations of LOOH. This novel LOOH-induced adaptive response requires a functional ohrR-ohr operon. These data illustrate an important novel physiological role for the ohrR-ohr system in sensing and inactivating lipid hydroperoxides.",1
"Klomsiri, Chananat, Panmanee, Warunya, Dharmsthiti, Saovanee, Vattanaviboon, Paiboon, Mongkolsuk, Skorn",2
Isolation and characterization of FecA- and FeoB-mediated iron acquisition systems of the spirochete Leptospira biflexa by random insertional mutagenesis.,0
"The specific mechanisms by which Leptospira spp. acquire iron from their ecological niches are unknown. A major factor contributing to our ignorance of spirochetal biology is the lack of methods for genetic analysis of these organisms. In this study, we have developed a system for random transposon mutagenesis of Leptospira biflexa using a mariner transposon, Himar1. To demonstrate the validity of Himar1 in vivo transposon mutagenesis in L. biflexa, a screen of mutants for clones impaired in amino acid biosynthesis was first performed, enabling the identification of tryptophan and glutamate auxotrophs. To investigate iron transporters, 2,000 L. biflexa transposon mutants were screened onto media with and without hemin, thus allowing the identification of five hemin-requiring mutants, and the putative genes responsible for this phenotype were identified. Three mutants had distinct insertions in a gene encoding a protein which shares homology with the TonB-dependent receptor FecA, involved in ferric citrate transport. We also identified two mutants with a Himar1 insertion into a feoB-like gene, the product of which is required for ferrous iron uptake in many bacterial organisms. Interestingly, the growth inhibition exhibited by the fecA and feoB mutants was relieved by deferoxamine, suggesting the presence of a ferric hydroxamate transporter. These results confirm the importance of iron for the growth of Leptospira and its ability to use multiple iron sources.",1
"Louvel, Hélène, Saint Girons, Isabelle, Picardeau, Mathieu",2
"Random insertional mutagenesis of Leptospira interrogans, the agent of leptospirosis, using a mariner transposon.",0
"The recent availability of the complete genome sequences of Leptospira interrogans, the agent of leptospirosis, has allowed the identification of several putative virulence factors. However, to our knowledge, attempts to carry out gene transfer in pathogenic Leptospira spp. have failed so far. In this study, we show that the Himar1 mariner transposon permits random mutagenesis in the pathogen L. interrogans. We have identified genes that have been interrupted by Himar1 insertion in 35 L. interrogans mutants. This approach of transposon mutagenesis will be useful for understanding the spirochetal physiology and the pathogenic mechanisms of Leptospira, which remain largely unknown.",1
"Bourhy, Pascale, Louvel, Hélène, Saint Girons, Isabelle, Picardeau, Mathieu",2
Inactivation of a predicted leader peptidase prevents photoautotrophic growth of Synechocystis sp. strain PCC 6803.,0
"To establish the role of the two putative type I leader peptidases (LepB1 and LepB2) encoded in the genome of the cyanobacterium Synechocystis sp. strain PCC 6803, we generated independent knockout mutants for both genes by introducing kanamycin resistance cassettes into the two open reading frames (sll0716 [lepB1] and slr1377 [lepB2], respectively). Although the insertion was successful in both instances, it was not possible to select homozygous mutant cells for lepB2, suggesting that the function of this gene is essential for cell viability. In contrast, LepB1 is apparently essential only for photoautotrophic growth, because homozygous lepB1::Km(r) cells could be propagated under heterotrophic conditions. They were even capable to some extent of photosynthetic oxygen evolution. However, the photosynthetic activity decreased gradually with extended incubation in the light and was particularly affected by high light intensities. Both features were indicative of photooxidative damage, which was probably caused by inefficient replacement of damaged components of the photosynthetic machinery due to the lack of a leader peptidase removing the signal peptides from photosynthetic precursor proteins. Indeed, processing of the PsbO precursor polypeptide to the corresponding mature protein was significantly affected in the mutant, and reduced amounts of other proteins that are synthesized as precursors with signal peptides accumulated in the cells. These results strongly suggest that LepB1 is important for removal of the signal peptides after membrane transport of the components of the photosynthetic machinery, which in turn is a prerequisite for the biogenesis of a functional photosynthetic electron transport chain.",1
"Zhbanko, Maria, Zinchenko, Vladislav, Gutensohn, Michael, Schierhorn, Angelika, Klösgen, Ralf Bernd",2
Polyphosphate kinase protects Salmonella enterica from weak organic acid stress.,0
"Mutants of Salmonella enterica lacking polyphosphate kinase (ppk) grow poorly in the presence of the weak organic acids acetate, propionate, and benzoate. This sensitivity is corrected by methionine and seems to result from destabilization of MetA (homoserine transsuccinylase), the first enzyme in methionine biosynthesis. The MetA protein is known to be sensitive to thermal inactivation, and ppk mutants are more sensitive to heat-induced methionine auxotrophy. Peroxide increases the sensitivity of ppk mutants to both heat and acid and may oxidatively damage (carbonylate) destabilized MetA. While acid appears to impair methionine biosynthesis, it leads to derepression of MetA and may inhibit growth by causing toxic accumulation of denatured protein. This is supported by the observation that the overexpression of MetA in ppk mutants causes acid sensitivity that is not corrected by methionine. We propose that polyphosphate acts as a chemical chaperone that helps refold MetA and/or may stimulate proteolysis of toxic denatured protein. The instability of MetA protein may provide a metabolic fuse that blocks growth under conditions that denature proteins; the sensitivity of this fuse is modulated by polyphosphate.",1
"Price-Carter, Marian, Fazzio, Thomas G, Vallbona, Ester Ibañez, Roth, John R",2
Global gene expression responses to cadmium toxicity in Escherichia coli.,0
Genome-wide analysis of temporal gene expression profiles in Escherichia coli following exposure to cadmium revealed a shift to anaerobic metabolism and induction of several stress response systems. Disruption in the transcription of genes encoding ribosomal proteins and zinc-binding proteins may partially explain the molecular mechanisms of cadmium toxicity.,1
"Wang, Anyou, Crowley, David E",2
Why does Escherichia coli grow more slowly on glucosamine than on N-acetylglucosamine? Effects of enzyme levels and allosteric activation of GlcN6P deaminase (NagB) on growth rates.,0
"Wild-type Escherichia coli grows more slowly on glucosamine (GlcN) than on N-acetylglucosamine (GlcNAc) as a sole source of carbon. Both sugars are transported by the phosphotransferase system, and their 6-phospho derivatives are produced. The subsequent catabolism of the sugars requires the allosteric enzyme glucosamine-6-phosphate (GlcN6P) deaminase, which is encoded by nagB, and degradation of GlcNAc also requires the nagA-encoded enzyme, N-acetylglucosamine-6-phosphate (GlcNAc6P) deacetylase. We investigated various factors which could affect growth on GlcN and GlcNAc, including the rate of GlcN uptake, the level of induction of the nag operon, and differential allosteric activation of GlcN6P deaminase. We found that for strains carrying a wild-type deaminase (nagB) gene, increasing the level of the NagB protein or the rate of GlcN uptake increased the growth rate, which showed that both enzyme induction and sugar transport were limiting. A set of point mutations in nagB that are known to affect the allosteric behavior of GlcN6P deaminase in vitro were transferred to the nagB gene on the Escherichia coli chromosome, and their effects on the growth rates were measured. Mutants in which the substrate-induced positive cooperativity of NagB was reduced or abolished grew even more slowly on GlcN than on GlcNAc or did not grow at all on GlcN. Increasing the amount of the deaminase by using a nagC or nagA mutation to derepress the nag operon improved growth. For some mutants, a nagA mutation, which caused the accumulation of the allosteric activator GlcNAc6P and permitted allosteric activation, had a stronger effect than nagC. The effects of the mutations on growth in vivo are discussed in light of their in vitro kinetics.",1
"Alvarez-Añorve, Laura I, Calcagno, Mario L, Plumbridge, Jacqueline",2
Molecular determinants for PspA-mediated repression of the AAA transcriptional activator PspF.,0
"The Escherichia coli phage shock protein system (pspABCDE operon and pspG gene) is induced by numerous stresses related to the membrane integrity state. Transcription of the psp genes requires the RNA polymerase containing the sigma(54) subunit and the AAA transcriptional activator PspF. PspF belongs to an atypical class of sigma(54) AAA activators in that it lacks an N-terminal regulatory domain and is instead negatively regulated by another regulatory protein, PspA. PspA therefore represses its own expression. The PspA protein is distributed between the cytoplasm and the inner membrane fraction. In addition to its transcriptional inhibitory role, PspA assists maintenance of the proton motive force and protein export. Several lines of in vitro evidence indicate that PspA-PspF interactions inhibit the ATPase activity of PspF, resulting in the inhibition of PspF-dependent gene expression. In this study, we characterize sequences within PspA and PspF crucial for the negative effect of PspA upon PspF. Using a protein fragmentation approach, we show that the integrity of the three putative N-terminal alpha-helical domains of PspA is crucial for the role of PspA as a negative regulator of PspF. A bacterial two-hybrid system allowed us to provide clear evidence for an interaction in E. coli between PspA and PspF in vivo, which strongly suggests that PspA-directed inhibition of PspF occurs via an inhibitory complex. Finally, we identify a single PspF residue that is a binding determinant for PspA.",1
"Elderkin, Sarah, Bordes, Patricia, Jones, Susan, Rappas, Mathieu, Buck, Martin",2
Two distinct functions of ComW in stabilization and activation of the alternative sigma factor ComX in Streptococcus pneumoniae.,0
"Natural genetic transformation in Streptococcus pneumoniae is controlled by a quorum-sensing system, which acts through the competence-stimulating peptide (CSP) for transient activation of genes required for competence. More than 100 genes have been identified as CSP regulated by use of DNA microarray analysis. One of the CSP-induced genes required for genetic competence is comW. As the expression of this gene depended on the regulator ComE, but not on the competence sigma factor ComX (sigma(X)), and as expression of several genes required for DNA processing was affected in a comW mutant, comW appears to be a new regulatory gene. Immunoblotting analysis showed that the amount of the sigma(X) protein is dependent on ComW, suggesting that ComW may be directly or indirectly involved in the accumulation of sigma(X). As sigma(X) is stabilized in clpP mutants, a comW mutation was introduced into the clpP background to ask whether the synthesis of sigma(X) depends on ComW. The clpP comW double mutant accumulated an amount of sigma(X) higher (threefold) than that seen in the wild type but was not transformable, suggesting that while comW is not needed for sigma(X) synthesis, it acts both in stabilization of sigma(X) and in its activation. Modification of ComW with a histidine tag at its C or N terminus revealed that both amino and carboxyl termini are important for increasing the stability of sigma(X), but only the N terminus is important for stimulating its activity.",1
"Sung, Chang Kyoo, Morrison, Donald A",2
Characterization of a cluster of three glycosyltransferase enzymes essential for Moraxella catarrhalis lipooligosaccharide assembly.,0
"Moraxella catarrhalis isolates express lipooligosaccharide (LOS) molecules on their surface, which share epitopes similar to that of the Neisseria and Haemophilus species. These common LOS epitopes have been implicated in various steps of pathogenesis for the different organisms. In this study, a cluster of three LOS glycosyltransferase genes (lgt) were identified in M. catarrhalis 7169, a strain that produces a serotype B LOS. Mutants in these glycosyltransferase genes were constructed, and the resulting LOS phenotypes were consistent with varying degrees of truncation compared to wild-type LOS. The LOS structures of each lgt mutant were no longer detected by a monoclonal antibody (MAb 4G5) specific to a highly conserved terminal epitope nor by a monoclonal antibody (MAb 3F7) specific to the serotype B LOS side chain. Mass spectrometry of the LOS glycoforms assembled by two of these lgt mutants indicated that lgt1 encodes an alpha(1-2) glucosyltransferase and the lgt2 encodes a beta(1-4) galactosyltransferase. However, these structural studies could not delineate the function for lgt3. Therefore, M. catarrhalis lgt3 was introduced into a defined beta(1-4) glucosyltransferase Haemophilus ducreyi 35000glu- mutant in trans, and monoclonal antibody analysis confirmed that Lgt3 complemented the LOS defect. These data suggest that lgt3 encodes a glucosyltransferase involved in the addition of a beta(1-4)-linked glucose to the inner core. Furthermore, we conclude that this enzymatic step is essential for the assembly of the complete LOS glycoform expressed by M. catarrhalis 7169.",1
"Edwards, Katie J, Allen, Simon, Gibson, Bradford W, Campagnari, Anthony A",2
Requirement of the receiver and phosphotransfer domains of ArcB for efficient dephosphorylation of phosphorylated ArcA in vivo.,0
"The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory conditions of growth. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. Under aerobic growth conditions, phosphorylated ArcA (ArcA-P) dephosphorylates and its transcriptional regulation is released. The dephosphorylation of ArcA-P has been shown to occur, at least in vitro, via an ArcA(Asp54)-P --> ArcB(His717)-P --> ArcB(Asp576)-P --> P(i) reverse phosphorelay. In this study, the physiological significance of this pathway was assessed. The results demonstrate that the receiver and phosphotransfer domains of the tripartite sensor kinase ArcB are necessary and sufficient for efficient ArcA-P dephosphorylation in vivo.",1
"Peña-Sandoval, Gabriela R, Kwon, Ohsuk, Georgellis, Dimitris",2
"Functional characterization of WaaL, a ligase associated with linking O-antigen polysaccharide to the core of Pseudomonas aeruginosa lipopolysaccharide.",0
"The O antigen of Pseudomonas aeruginosa B-band lipopolysaccharide is synthesized by assembling O-antigen-repeat units at the cytoplasmic face of the inner membrane by nonprocessive glycosyltransferases, followed by polymerization on the periplasmic face. The completed chains are covalently attached to lipid A core by the O-antigen ligase, WaaL. In P. aeruginosa the process of ligating these O-antigen molecules to lipid A core is not clearly defined, and an O-antigen ligase has not been identified until this study. Using the sequence of waaL from Salmonella enterica as a template in a BLAST search, a putative waaL gene was identified in the P. aeruginosa genome. The candidate gene was amplified and cloned, and a chromosomal knockout of PAO1 waaL was generated. Lipopolysaccharide (LPS) from this mutant is devoid of B-band O-polysaccharides and semirough (SR-LPS, or core-plus-one O-antigen). The mutant PAO1waaL is also deficient in the production of A-band polysaccharide, a homopolymer of D-rhamnose. Complementation of the mutant with pPAJL4 containing waaL restored the production of both A-band and B-band O antigens as well as SR-LPS, indicating that the knockout was nonpolar and waaL is required for the attachment of O-antigen repeat units to the core. Mutation of waaL in PAO1 and PA14, respectively, could be complemented with waaL from either strain to restore wild-type LPS production. The waaL mutation also drastically affected the swimming and twitching motilities of the bacteria. These results demonstrate that waaL in P. aeruginosa encodes a functional O-antigen ligase that is important for cell wall integrity and motility of the bacteria.",1
"Abeyrathne, Priyanka D, Daniels, Craig, Poon, Karen K H, Matewish, Mauricia J, Lam, Joseph S",2
Use of thioredoxin as a reporter to identify a subset of Escherichia coli signal sequences that promote signal recognition particle-dependent translocation.,0
"We have previously reported that the DsbA signal sequence promotes efficient, cotranslational translocation of the cytoplasmic protein thioredoxin-1 via the bacterial signal recognition particle (SRP) pathway. However, two commonly used signal sequences, those of PhoA and MalE, which promote export by a posttranslational mechanism, do not export thioredoxin. We proposed that this difference in efficiency of export was due to the rapid folding of thioredoxin in the cytoplasm; cotranslational export by the DsbA signal sequence avoids the problem of cytoplasmic folding (C. F. Schierle, M. Berkmen, D. Huber, C. Kumamoto, D. Boyd, and J. Beckwith, J. Bacteriol. 185:5706-5713, 2003). Here, we use thioredoxin as a reporter to distinguish SRP-dependent from non-SRP-dependent cleavable signal sequences. We screened signal sequences exhibiting a range of hydrophobicity values based on a method that estimates hydrophobicity. Successive iterations of screening and refining the method defined a threshold hydrophobicity required for SRP recognition. While all of the SRP-dependent signal sequences identified were above this threshold, there were also a few signal sequences above the threshold that did not utilize the SRP pathway. These results suggest that a simple measure of the hydrophobicity of a signal sequence is an important but not a sufficient indicator for SRP recognition. In addition, by fusing a number of both classes of signal sequences to DsbA, we found that DsbA utilizes an SRP-dependent signal sequence to achieve efficient export to the periplasm. Our results suggest that those proteins found to be exported by SRP-dependent signal sequences may require this mode of export because of their tendency to fold rapidly in the cytoplasm.",1
"Huber, Damon, Boyd, Dana, Xia, Yu, Olma, Michael H, Gerstein, Mark, Beckwith, Jon",2
Phosphorylation-independent activity of atypical response regulators of Helicobacter pylori.,0
"The genome of the gastric pathogen Helicobacter pylori harbors a remarkably low number of regulatory genes, including three and five open reading frames encoding two-component histidine kinases and response regulators, respectively, which are putatively involved in transcriptional regulation. Two of the response regulator genes, hp1043 and hp166, proved to be essential for cell growth, and inactivation of the response regulator gene hp1021 resulted in a severe growth defect, as indicated by a small-colony phenotype. The sequences of the receiver domains of response regulators HP1043 and HP1021 differ from the consensus sequence of the acidic pocket of the receiver domain which is involved in the phosphotransfer reaction from the histidine kinase to the response regulator. Using a genetic complementation system, we demonstrated that the function of response regulator HP166, which is essential for cell growth, can be provided by a mutated derivative carrying a D52N substitution at the site of phosphorylation. We found that the atypical receiver sequences of HP1043 and HP1021 are not crucial for the function of these response regulators. Phosphorylation of the receiver domains of HP1043 and HP1021 is not needed for response regulator function and may not occur at all. Thus, the phosphorylation-independent action of these regulators differs from the well-established two-component paradigm.",1
"Schär, Jennifer, Sickmann, Albert, Beier, Dagmar",2
Identification and characterization of genes required for competence in Neisseria meningitidis.,0
"We have identified genes required for competence of Neisseria meningitidis, a naturally transformable human pathogen. Although not comprehensive, our analysis identified competence-defective mutants with transposon insertions in genes not previously implicated in this process in Neisseria.",1
"Sun, Yao-Hui, Exley, Rachel, Li, Yanwen, Goulding, David, Tang, Christoph",2
"Synthesis of autoinducer 2 by the lyme disease spirochete, Borrelia burgdorferi.",0
"Defining the metabolic capabilities and regulatory mechanisms controlling gene expression is a valuable step in understanding the pathogenic properties of infectious agents such as Borrelia burgdorferi. The present studies demonstrated that B. burgdorferi encodes functional Pfs and LuxS enzymes for the breakdown of toxic products of methylation reactions. Consistent with those observations, B. burgdorferi was shown to synthesize the end product 4,5-dihydroxy-2,3-pentanedione (DPD) during laboratory cultivation. DPD undergoes spontaneous rearrangements to produce a class of pheromones collectively named autoinducer 2 (AI-2). Addition of in vitro-synthesized DPD to cultured B. burgdorferi resulted in differential expression of a distinct subset of proteins, including the outer surface lipoprotein VlsE. Although many bacteria can utilize the other LuxS product, homocysteine, for regeneration of methionine, B. burgdorferi was found to lack such ability. It is hypothesized that B. burgdorferi produces LuxS for the express purpose of synthesizing DPD and utilizes a form of that molecule as an AI-2 pheromone to control gene expression.",1
"Babb, Kelly, von Lackum, Kate, Wattier, Rachel L, Riley, Sean P, Stevenson, Brian",2
Functional characterization of a novel ArgA from Mycobacterium tuberculosis.,0
"The Mycobacterium tuberculosis gene Rv2747 encodes a novel 19-kDa ArgA that catalyzes the initial step in L-arginine biosynthesis, namely the conversion of L-glutamate to alpha-N-acetyl-L-glutamate. Initial velocity studies reveal that Rv2747 proceeds through a sequential kinetic mechanism, with K(m) values of 280 mM for L-glutamine and 150 microM for acetyl-coenzyme A and with a k(cat) value of 200 min(-1). Initial velocity studies with L-glutamate showed that even at concentrations of 600 mM, saturation was not observed. Therefore, only a k(cat)/K(m) value of 125 M(-1) min(-1) can be calculated. Inhibition studies reveal that the enzyme is strongly regulated by L-arginine, the end product of the pathway (50% inhibitory concentration, 26 microM). The enzyme was completely inhibited by 500 microM arginine, with a Hill coefficient of 0.60, indicating negatively cooperative binding of L-arginine.",1
"Errey, James C, Blanchard, John S",2
Requirements for Vibrio cholerae HapR binding and transcriptional repression at the hapR promoter are distinct from those at the aphA promoter.,0
"Virulence gene expression in certain strains of Vibrio cholerae is regulated in response to cell density by a quorum-sensing cascade that influences the levels of the LuxR homolog HapR through small regulatory RNAs that control the stability of its message. At high cell density, HapR represses the expression of the gene encoding the virulence gene activator AphA by binding to a site between -85 and -58 in the aphA promoter. We show here that a second binding site for HapR lies within the hapR promoter from which it functions to repress its own transcription. This site, as determined by gel mobility shift assay and DNaseI footprinting, is located between +8 and +36 from the transcriptional start and is not strongly conserved with the site at the aphA promoter. At low cell density, when the expression of a transcriptional hapR-lacZ fusion was low, no autorepression was observed. However, at high cell density, when the expression of the hapR-lacZ fusion was approximately 15-fold higher, the presence of HapR reduced its expression. Introduction of a single base pair change within the binding site at +18 prevented HapR binding in gel mobility shift assays. In the absence of HapR, this mutation did not significantly influence the expression of the hapR promoter, but in its presence, the expression of the promoter was increased at high cell density. These results indicate that HapR autorepresses from a single binding site in the hapR promoter and suggest a model for the temporal regulation of its expression as its intracellular levels increase.",1
"Lin, Wei, Kovacikova, Gabriela, Skorupski, Karen",2
Characterization of enhancer binding by the Vibrio cholerae flagellar regulatory protein FlrC.,0
"The human pathogen Vibrio cholerae is a highly motile organism by virtue of a polar flagellum, and motility has been inferred to be an important aspect of virulence. It has previously been demonstrated that the sigma(54)-dependent activator FlrC is necessary for both flagellar synthesis and for enhanced intestinal colonization. In order to characterize FlrC binding, we analyzed two FlrC-dependent promoters, the highly transcribed flaA promoter and the weakly transcribed flgK promoter, utilizing transcriptional lacZ fusions, mobility shift assays, and DNase I footprinting. Promoter fusion studies showed that the smallest fragment with wild-type transcriptional activity for flaAp was from positions -54 to +137 with respect to the start site, and from -63 to +144 for flgKp. Gel mobility shift assays indicated that FlrC binds to a fragment containing the region from positions +24 to +95 in the flaAp, and DNase I footprinting identified a protected region between positions +24 and +85. Mobility shift and DNase I footprinting indicated weak binding of FlrC to a region downstream of the flgKp transcription start site. These results demonstrate a relatively novel sigma(54)-dependent promoter architecture, with the activator FlrC binding downstream of the sigma(54)-dependent transcription start sites. When the FlrC binding site(s) in the flaA promoter was moved a large distance (285 bp) upstream of the transcription start site of either flaAp or flgKp, high levels of FlrC-dependent transcription resulted, indicating that this binding region functions as an enhancer element. In contrast, the relatively weak FlrC binding site(s) in the flgK promoter failed to function as an enhancer element at either promoter, suggesting that FlrC binding strength contributes to enhancer activity. Our results suggest that the differences in FlrC binding to various flagellar promoters results in the differences in transcription levels that mirror the relative requirement for the flagellar components within the flagellum.",1
"Correa, Nidia E, Klose, Karl E",2
Autoinduction in Erwinia amylovora: evidence of an acyl-homoserine lactone signal in the fire blight pathogen.,0
"Erwinia amylovora causes fire blight disease of apple, pear, and other members of the Rosaceae. Here we present the first evidence for autoinduction in E. amylovora and a role for an N-acyl-homoserine lactone (AHL)-type signal. Two major plant virulence traits, production of extracellular polysaccharides (amylovoran and levan) and tolerance to free oxygen radicals, were controlled in a bacterial-cell-density-dependent manner. Two standard autoinducer biosensors, Agrobacterium tumefaciens NTL4 and Vibrio harveyi BB886, detected AHL in stationary-phase cultures of E. amylovora. A putative AHL synthase gene, eamI, was partially sequenced, which revealed homology with autoinducer genes from other bacterial pathogens (e.g., carI, esaI, expI, hsII, yenI, and luxI). E. amylovora was also found to carry eamR, a convergently transcribed gene with homology to luxR AHL activator genes in pathogens such as Erwinia carotovora. Heterologous expression of the Bacillus sp. strain A24 acyl-homoserine lactonase gene aiiA in E. amylovora abolished induction of AHL biosensors, impaired extracellular polysaccharide production and tolerance to hydrogen peroxide, and reduced virulence on apple leaves.",1
"Molina, Lázaro, Rezzonico, Fabio, Défago, Geneviève, Duffy, Brion",2
The active site of O-acetylserine sulfhydrylase is the anchor point for bienzyme complex formation with serine acetyltransferase.,0
"The biosynthesis of cysteine in bacteria and plants is carried out by a two-step pathway, catalyzed by serine acetyltransferase (SAT) and O-acetylserine sulfhydrylase (OASS; O-acetylserine [thiol] lyase). The aerobic form of OASS forms a tight bienzyme complex with SAT in vivo, termed cysteine synthase. We have determined the crystal structure of OASS in complex with a C-terminal peptide of SAT required for bienzyme complex formation. The binding site of the peptide is at the active site of OASS, and its C-terminal carboxyl group occupies the same anion binding pocket as the alpha-carboxylate of the O-acetylserine substrate of OASS. These results explain the partial inhibition of OASS by SAT on complex formation as well as the competitive dissociation of the complex by O-acetylserine.",1
"Huang, Bin, Vetting, Matthew W, Roderick, Steven L",2
"Characterization of PmfR, the transcriptional activator of the pAO1-borne purU-mabO-folD operon of Arthrobacter nicotinovorans.",0
"Nicotine catabolism by Arthrobacter nicotinovorans is linked to the presence of the megaplasmid pAO1. Genes involved in this catabolic pathway are arranged on the plasmid into gene modules according to function. During nicotine degradation gamma-N-methylaminobutyrate is formed from the pyrrolidine ring of nicotine. Analysis of the pAO1 open reading frames (ORF) resulted in identification of the gene encoding a demethylating gamma-N-methylaminobutyrate oxidase (mabO). This gene was shown to form an operon with purU- and folD-like genes. Only in bacteria grown in the presence of nicotine could transcripts of the purU-mabO-folD operon be detected, demonstrating that this operon constitutes part of the pAO1 nicotine regulon. Its transcriptional start site was determined by primer extension analysis. Transcription of the operon was shown to be controlled by a new transcriptional regulator, PmfR, the product of a gene that is transcribed divergently from the purU, mabO, and folD genes. PmfR was purified, and electromobility shift assays and DNase I-nuclease digestion experiments were used to determine that its DNA binding site is located between -48 and -88 nucleotides upstream of the transcriptional start site of the operon. Disruption of pmfR by homologous recombination with a chloramphenicol resistance cassette demonstrated that PmfR acts in vivo as a transcriptional activator. Mutagenesis of the PmfR target DNA suggested that the sequence GTTT-14 bp-AAAC is the core binding site of the regulator upstream of the -35 promoter region of the purU-mabO-folD operon.",1
"Chiribau, Calin B, Sandu, Cristinel, Igloi, Gabor L, Brandsch, Roderich",2
"Impact of global transcriptional regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc on glucose catabolism in Escherichia coli.",0
"Even though transcriptional regulation plays a key role in establishing the metabolic network, the extent to which it actually controls the in vivo distribution of metabolic fluxes through different pathways is essentially unknown. Based on metabolism-wide quantification of intracellular fluxes, we systematically elucidated the relevance of global transcriptional regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc for aerobic glucose catabolism in batch cultures of Escherichia coli. Knockouts of ArcB, Cra, Fnr, and Mlc were phenotypically silent, while deletion of the catabolite repression regulators Crp and Cya resulted in a pronounced slow-growth phenotype but had only a nonspecific effect on the actual flux distribution. Knockout of ArcA-dependent redox regulation, however, increased the aerobic tricarboxylic acid (TCA) cycle activity by over 60%. Like aerobic conditions, anaerobic derepression of TCA cycle enzymes in an ArcA mutant significantly increased the in vivo TCA flux when nitrate was present as an electron acceptor. The in vivo and in vitro data demonstrate that ArcA-dependent transcriptional regulation directly or indirectly controls TCA cycle flux in both aerobic and anaerobic glucose batch cultures of E. coli. This control goes well beyond the previously known ArcA-dependent regulation of the TCA cycle during microaerobiosis.",1
"Perrenoud, Annik, Sauer, Uwe",2
"Changes in the extracellular proteome caused by the absence of the bldA gene product, a developmentally significant tRNA, reveal a new target for the pleiotropic regulator AdpA in Streptomyces coelicolor.",0
"The extracellular proteome of Streptomyces coelicolor grown in a liquid medium was analyzed by using two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time of flight peptide mass fingerprint analysis. Culture supernatants became protein rich only after rapid growth had been completed, supporting the idea that protein secretion is largely a stationary phase phenomenon. Out of about 600 protein spots observed, 72 were characterized. The products of 47 genes were identified, with only 11 examples predicted to be secreted proteins. Mutation in bldA, previously known to impair the stationary phase processes of antibiotic production and morphological differentiation, also induced changes in the extracellular proteome, revealing even greater pleiotropy in the bldA phenotype than previously known. Four proteins increased in abundance in the bldA mutant, while the products of 11 genes, including four secreted proteins, were severely down-regulated. Although bldA encodes the only tRNA capable of efficiently translating the rare UUA (leucine) codon, none of the latter group of genes contains an in-frame TTA. SCO0762, a serine-protease inhibitor belonging to the Streptomyces subtilisin inhibitor family implicated in differentiation in other streptomycetes, was completely absent from the bldA mutant. This dependence was shown to be mediated via the TTA-containing regulatory gene adpA, also known as bldH, a developmental gene that is responsible for the effects of bldA on differentiation. Mutation of the SCO0762 gene abolished detectable trypsin-protease inhibitory activity but did not result in any obvious morphological defects.",1
"Kim, Dae-Wi, Chater, Keith, Lee, Kye-Joon, Hesketh, Andy",2
RNase/anti-RNase activities of the bacterial parD toxin-antitoxin system.,0
"The bacterial parD toxin-antitoxin system of plasmid R1 encodes two proteins, the Kid toxin and its cognate antitoxin, Kis. Kid cleaves RNA and inhibits protein synthesis and cell growth in Escherichia coli. Here, we show that Kid promotes RNA degradation and inhibition of protein synthesis in rabbit reticulocyte lysates. These new activities of the Kid toxin were counteracted by the Kis antitoxin and were not displayed by the KidR85W variant, which is nontoxic in E. coli. Moreover, while Kid cleaved single- and double-stranded RNA with a preference for UAA or UAC triplets, KidR85W maintained this sequence preference but hardly cleaved double-stranded RNA. Kid was formerly shown to inhibit DNA replication of the ColE1 plasmid. Here we provide in vitro evidence that Kid cleaves the ColE1 RNA II primer, which is required for the initiation of ColE1 replication. In contrast, KidR85W did not affect the stability of RNA II, nor did it inhibit the in vitro replication of ColE1. Thus, the endoribonuclease and the cytotoxic and DNA replication-inhibitory activities of Kid seem tightly correlated. We propose that the spectrum of action of this toxin extends beyond the sole inhibition of protein synthesis to control a broad range of RNA-regulated cellular processes.",1
"Muñoz-Gómez, Ana J, Lemonnier, Marc, Santos-Sierra, Sandra, Berzal-Herranz, Alfredo, Díaz-Orejas, Ramón",2
Prevalence of Giardia and Cryptosporidium in beef cows in southern Ontario and in beef calves in southern British Columbia.,0
"In 1998 and 1999, fecal samples were collected from 669 beef cows on 39 farms located within 10 counties of Ontario. Overall prevalences of Giardia, Cryptosporidium muris, and Cryptosporidium parvum in cows were 8.7%, 10.6%, and 18.4%, respectively. Of the 39 farms sampled, Giardia was detected on 64%, Cr. muris on 72%, and Cr. parvum on 90%. Cryptosporidium parvum was detected in 28% of the cows in 1998 and in 5.2% in 1999. Differences between the 2 y were attributed to sampling during calving in 1998 and during gestation in 1999. In 1998, Giardia, Cr. muris, and Cr. parvum were detected in herds provided with municipal water. In 1998, 193 calves were sampled from 10 farms, representing 4 watersheds, in British Columbia. Thirty-six percent of the calves exhibited signs of diarrhea. Overall prevalences of Giardia and Cryptosporidium spp. in calves were 36% and 13%, respectively. There was evidence that calves with Giardia were more likely to develop scours. Restricting cattle from surface water during periods of high shedding may reduce watershed contamination.",1
"McAllister, Tim A, Olson, Merle E, Fletch, Andy, Wetzstein, Merv, Entz, Toby",2
Vertical distribution of zooplankton: density dependence and evidence for an ideal free distribution with costs.,0
"In lakes with a deep-water algal maximum, herbivorous zooplankton are faced with a trade-off between high temperature but low food availability in the surface layers and low temperature but sufficient food in deep layers. It has been suggested that zooplankton (Daphnia) faced with this trade-off distribute vertically according to an ""Ideal Free Distribution (IFD) with Costs"". An experiment has been designed to test the density (competition) dependence of the vertical distribution as this is a basic assumption of IFD theory.",1
"Lampert, Winfried",2
"Effect of Light on Anthocyanin Levels in Submerged, Harvested Cranberry Fruit.",0
"Anthocyanins are a group of plant antioxidants known for their therapeutic use. The effects of natural light, red light, and far-red light on individual as well as total anthocyanin content in cranberry fruit (Vaccinium macrocarpon Ait) were examined in an experimental setting designed to mimic water-harvesting conditions. The reversed-phase high performance liquid chromatography (HPLC) method was used to separate and analyze the anthocyanins. In contrast to the case of the control sample that was kept in the dark, natural light increased the total anthocyanin level by $75.3$ % and $87.2$ % after 24 and 48 hours water immersion, respectively. Red light and far-red light increased the total anthocyanin level by $41.5$ % and $34.7$ %, respectively. The amount of each individual anthocyanin increased differently under natural light, red light, and far-red light, suggesting that expressions of enzymes that catalyze the anthocyanin biosynthesis are regulated differently by environments.",1
"Zhou, Yu, Singh, Bal Ram",2
Molecular Mechanisms Behind the Chemopreventive Effects of Anthocyanidins.,0
"Anthocyanins are polyphenolic ring-based flavonoids, and are widespread in fruits and vegetables of red-blue color. Epidemiological investigations and animal experiments have indicated that anthocyanins may contribute to cancer chemoprevention. The studies on the mechanism have been done recently at molecular level. This review summarizes current molecular bases for anthocyanidins on several key steps involved in cancer chemoprevention: (i) inhibition of anthocyanidins in cell transformation through targeting mitogen-activated protein kinase (MAPK) pathway and activator protein 1 (AP-1) factor; (ii) suppression of anthocyanidins in inflammation and carcinogenesis through targeting nuclear factor kappa B (NF- $\kappa$ B) pathway and cyclooxygenase 2 (COX-2) gene; (iii) apoptotic induction of cancer cells by anthocyanidins through reactive oxygen species (ROS) / c-Jun NH(2)-terminal kinase (JNK)-mediated caspase activation. These data provide a first molecular view of anthocyanidins contributing to cancer chemoprevention.",1
"Hou, De-Xing, Fujii, Makoto, Terahara, Norihiko, Yoshimoto, Makoto",2
The Effect of Two Methods of Pomegranate (Punica granatum L) Juice Extraction on Quality During Storage at $4^\circ$ C.,0
"The effect of two extraction methods of pomegranate juice on its quality and stability was evaluated. The first method consisted of separation of the seeds from fruits and centrifugation. The second method consisted of squeezing fruit halves with an electric lemon squeezer. During a period of 72 hours of cold storage at $4^\circ$ C, the juices were evaluated for the presence of sugars, organic acids, and anthocyanins. Delphinidin 3-glucoside was identified to be the major anthocyanin present at the level of 45-69 mg/L. Among the organic acids, oxalic and tartaric acids dominated. The major sugars detected in pomegranate juice were glucose and sucrose. No significant differences in the content of sugars, organic acids, or anthocyanins in juices obtained through application of the two different extraction methods were detected, with the exception of the drastic decrease of cyanidin $3,5$ -diglucoside level in juice obtained by seed centrifugation. The pH did not show differences between treatments. Titrable acidity and the level of sugars expressed as ${}^{\circ}$ Brix decreased after 32 and 15 hours after extraction, respectively, when juice was obtained by centrifuging the seeds.",1
"Miguel, Graça, Dandlen, Susana, Antunes, Dulce, Neves, Alcinda, Martins, Denise",2
"Anthocyanin Concentration of ""Assaria"" Pomegranate Fruits During Different Cold Storage Conditions.",0
"The concentration of anthocyanins in fruits of ""Assaria"" pomegranate, a sweet Portuguese cultivar typically grown in Algarve (south Portugal), was monitored during storage under different conditions. The fruits were exposed to cold storage ( $5^{\circ}$ C) after the following treatments: spraying with wax; spraying with $1.5$ % CaCl(2); spraying with wax and $1.5$ % CaCl(2); covering boxes with 25 $\mu$ c thickness low-density polyethylene film. Untreated fruits were used as a control. The anthocyanin levels were quantified by either comparison with an external standard of cyanidin 3-rutinoside (based on the peak area) or individual calculation from the peak areas based on standard curves of each anthocyanin type. The storage time as well as the fruit treatment prior to storage influenced total anthocyanin content. The highest levels were observed at the end of the first month of storage, except for the fruits treated with CaCl(2), where the maximal values were achieved at the end of the second month. The anthocyanin quantification method influenced the final result. When total anthocyanin was calculated as a sum of individual pigments quantified based on standard curves of each anthocyanin type, lower values were obtained.",1
"Miguel, Graça, Fontes, Catarina, Antunes, Dulce, Neves, Alcinda, Martins, Denise",2
Effect of Grape Seed Extract and Quercetin on Cardiovascular and Endothelial Parameters in High-Risk Subjects.,0
"Grape seed extract (GSE) has in vitro antioxidant activity but whether or not it works in vivo is not clear. In a fully randomised, crossover trial with 4-week treatment periods on 36 men and women with above-average vascular risk, we aimed to demonstrate that 2 g/day of GSE (1 g of polyphenols) alone, or with 1 g/day of added quercetin in yoghurt, favourably alters vascular function, endothelial function, and degree of oxidative damage in comparison to a control yoghurt. GSE alone improved flow-mediated dilatation determined ultrasonically by an absolute $1.1$ % compared with control. There was no effect of the combination of GSE with quercetin. No other blood or urine measure was altered. Thus sufficient polyphenols from GSE appear to be absorbed to influence endothelial nitric oxide production, and GSE has the potential to favourably influence vascular function.",1
"Clifton, Peter M",2
Urinary Excretion of Cyanidin Glucosides and Glucuronides in Healthy Humans After Elderberry Juice Ingestion.,0
"In a pilot study with 6 females and 1 male, the metabolism of various cyanidin glucosides after oral administration of elderberry juice was investigated. The anthocyanin metabolites were detected in urinary excretion. After ingestion of a bolus quantity of $3.57$ g total anthocyanins in a $150$ mL elderberry juice concentrate, $0.053$ % of the administered dose was excreted in urine as glucosidically bound cyanidins within the first 5 hours. Only $0.003$ % of the ingested anthocyanin glucosides was excreted as cyanidin glucuronide, suggesting that this conversion step might be of minor importance in urinary excretion.",1
"Bitsch, Roland, Netzel, Michael, Sonntag, Susanne, Strass, Gabriele, Frank, Thomas, Bitsch, Irmgard",2
Bioavailability and Biokinetics of Anthocyanins From Red Grape Juice and Red Wine.,0
"In a comparative study, 9 healthy volunteers ingested a single oral dose of 400 mL red grape juice or red wine with dose-adjusted anthocyanin content ( $283.5$ mg or $279.6$ mg, resp.) in crossover. The content of anthocyanin glucosides was detected in plasma and urinary excretion. Additionally, the plasmatic antioxidant activity was assessed after intake. Based on the plasma content, biokinetic criteria of the single anthocyanins were calculated, such as AUC, $\mathrm{c}_{\mathrm{max}}$ , $\mathrm{t}_{\mathrm{max}}$ , and the elimination rate $\mathrm{t}_{1/2}$ . The urinary excretion of total anthocyanins differed significantly and amounted to $0.18$ % (red wine) and $0.23$ % (red grape juice) of the administered dose. Additionally, the plasmatic antioxidant activity increased to higher levels after juice ingestion compared to wine. The intestinal absorption of the anthocyanins of red grape juice seemed to be improved compared to red wine, suggesting a possible synergistic effect of the glucose content of the juice. The improved absorption resulted in an enhanced plasmatic bioactivity.",1
"Bitsch, Roland, Netzel, Michael, Frank, Thomas, Strass, Gabriele, Bitsch, Irmgard",2
Anthocyanins and Human Health: An In Vitro Investigative Approach.,0
"Anthocyanin pigments and associated flavonoids have demonstrated ability to protect against a myriad of human diseases, yet they have been notoriously difficult to study with regard to human health. Anthocyanins frequently interact with other phytochemicals to potentiate biological effects, thus contributions from individual components are difficult to decipher. The complex, multicomponent structure of compounds in a bioactive mixture and the degradation of flavonoids during harsh extraction procedures obscure the precise assignment of bioactivity to individual pigments. Extensive metabolic breakdown after ingestion complicates tracking of anthocyanins to assess absorption, bioavailability, and accumulation in various organs. Anthocyanin pigments and other flavonoids that are uniformly, predictably produced in rigorously controlled plant cell culture systems can be a great advantage for health and nutrition research because they are quickly, easily isolated, lack interferences found in whole fruits, can be elicited to provoke rapid and prolific accumulation, and are amenable to biolabeling so that metabolic fate can be investigated after ingestion.",1
"Lila, Mary Ann",2
New Family of Bluish Pyranoanthocyanins.,0
"The use of anthocyanins has been investigated for the preparation of food and beverage natural colorants as they seem to have nontoxic effects. In this context, vinylpyranoanthocyanins were recently found to naturally occur in ageing red wine. This new family of anthocyanin-derived pigments may be obtained directly through the reaction between anthocyanin derivatives and other compounds. Some of these newly formed pigments have been found to exhibit a bluish color at acidic pH. The formation of bluish pigment was obtained through reaction between anthocyanin-pyruvic-acid adducts and flavanols in the presence of acetaldehyde. The formation of similar bluish pigments was attempted using other different precursors. The chromatic features of this kind of pigments bring promising expectations concerning the use of these naturally occurring blue pigments in the food industry.",1
"Mateus, Nuno, Oliveira, Joana, Haettich-Motta, Mafalda, de Freitas, Victor",2
LC/PDA/ESI-MS Profiling and Radical Scavenging Activity of Anthocyanins in Various Berries.,0
"Anthocyanin extracts of two blueberries, Vaccinium myrtillus (bilberry) and Vaccinium ashei (rabbiteye blueberry), and of three other berries, Ribes nigrum (black currant), Aronia melanocarpa (chokeberry), and Sambucus nigra (elderberry), were analyzed by high-performance liquid chromatography coupled with photodiode array detection and electrospray ionization - mass spectrometry (LC/PDA/ESI-MS). Both bilberry and rabbiteye blueberry contained 15 identical anthocyanins with different distribution patterns. Black currant, chokeberry, and elderberry contained 6, 4, and 4 kinds of anthocyanins, respectively. The radical scavenging activities of these berry extracts were analyzed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH). All these extracts showed potent antiradical activities.",1
"Nakajima, Jun-Ichiro, Tanaka, Ippei, Seo, Shujiro, Yamazaki, Mami, Saito, Kazuki",2
Caffeoylquinic Acids Generated In Vitro in a High-Anthocyanin-Accumulating Sweet potato Cell Line.,0
"Accumulation of phenolic compounds has been monitored in a suspension culture of anthocyanin-accumulating sweet potato cell line grown under the conditions of modified Murashige and Skoog high-anthocyanin production medium (APM) over a period of 24 days. Tissue samples extracted with 15% acetic acid were analysed using HPLC at a detection wavelength of 326 nm. Among others, the following derivatives of caffeoylquinic acids were detected: 4,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid, and 3,4,5-tricaffeoylquinic acid. Their total amount reached a maximum of 110 mg/gFW between the 4th and the 15th day of culture growth on APM. The major compound of the phenolic mixture was 3,5-dicaffeoylquinic acid with maximum accumulation level of 80 mg/100 gFW. The potential effects of targeted phenolic compounds on the nutraceutical qualities of in vitro produced anthocyanin-rich extracts are discussed.",1
"Konczak, Izabela, Okuno, Shigenori, Yoshimoto, Makoto, Yamakawa, Osamu",2
Sour Cherry (Prunus cerasus L) Anthocyanins as Ingredients for Functional Foods.,0
"In the recent years many studies on anthocyanins have revealed their strong antioxidant activity and their possible use as chemotherapeutics. The finding that sour cherries (Prunus cerasus L) (also called tart cherries) contain high levels of anthocyanins that possess strong antioxidant and anti-inflammatory properties has attracted much attention to this species. Here we report the preliminary results of the induction of anthocyanin biosynthesis in sour cherry callus cell cultures. The evaluation and characterization of the in vitro produced pigments are compared to those of the anthocyanins found in vivo in fruits of several sour cherry cultivars. Interestingly, the anthocyanin profiles found in whole fruit extracts were similar in all tested genotypes but were different with respect to the callus extract. The evaluation of antioxidant activity, performed by ORAC and TEAC assays, revealed a relatively high antioxidant capacity for the fruit extracts (from 1145 to 2592 $\mu $ mol TE/100 g FW) and a lower one for the callus extract (688 $\mu $ mol TE/100 g FW).",1
"Blando, Federica, Gerardi, Carmela, Nicoletti, Isabella",2
To Stretch the Boundary of Secondary Metabolite Production in Plant Cell-Based Bioprocessing: Anthocyanin as a Case Study.,0
"Plant cells and tissue cultures hold great promise for controlled production of a myriad of useful secondary metabolites on demand. The current yield and productivity cannot fulfill the commercial goal of a plant cell-based bioprocess for the production of most secondary metabolites. In order to stretch the boundary, recent advances, new directions and opportunities in plant cell-based bioprocessing, have been critically examined for the 10 years from 1992 to 2002. A review of the literature indicated that most of the R&D work was devoted predominantly to studies at an empirical level. A rational approach to molecular plant cell bioprocessing based on the fundamental understanding of metabolic pathways and their regulations is urgently required to stimulate further advances; however, the strategies and technical framework are still being developed. It is the aim of this review to take a step forward in framing workable strategies and technologies for molecular plant cell-based bioprocessing. Using anthocyanin biosynthesis as a case study, an integrated postgenomic approach has been proposed. This combines the functional analysis of metabolic pathways for biosynthesis of a particular metabolite from profiling of gene expression and protein expression to metabolic profiling. A global correlation not only can thus be established at the three molecular levels, but also places emphasis on the interactions between primary metabolism and secondary metabolism; between competing and/or complimentary pathways; and between biosynthetic and post-biosynthetic events.",1
"Zhang, Wei, Franco, Chris, Curtin, Chris, Conn, Simon",2
"Characterization of Acylated Anthocyanins in Callus Induced From Storage Root of Purple-Fleshed Sweet Potato, Ipomoea batatas L.",0
"Four anthocyanins were isolated from a highly pigmented callus induced from the storage root of purple-fleshed sweet potato (Ipomoea batatas L) cultivar Ayamurasaki. The anthocyanins were respectively identified as cyanidin 3- $O$ -(2- $O$ -(6- $O$ -( $E$ )-caffeoyl- $\beta$ -D-glucopyranosyl)- $\beta$ -D-glucopyranoside)-5- $O$ - $\beta$ -D-glucopyranoside, cyanidin 3- $O$ -(2- $O$ -(6- $O$ -( $E$ )- $p$ -coumaroyl- $\beta$ -D-glucopyranosyl)-6- $O$ -( $E$ )-caffeoyl- $\beta$ -D-glucopyranoside)-5- $O$ - $\beta$ -D-glucopyranoside, cyanidin 3- $O$ -(2- $O$ -(6- $O$ -( $E$ )- $p$ -coumaroyl- $\beta$ -D-glucopyranosyl)-6- $O$ -( $E$ )- $p$ -coumaroyl- $\beta$ -D-glucopyranoside)-5- $O$ - $\beta$ -D-glucopyranoside, and peonidin 3- $O$ -(2- $O$ -(6- $O$ -( $E$ )- $p$ -coumaroyl- $\beta$ -D-glucopyranosyl)-6- $O$ -( $E$ )- $p$ -coumaroyl- $\beta$ -D-glucopyranoside)-5- $O$ - $\beta$ -D-glucopyranoside by chemical and spectroscopic analyses. These anthocyanins were examined with respect to the stability in neutral aqueous solution as well as the radical scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. These acylated anthocyanins exhibited both higher stability and higher DPPH radical scavenging activity than corresponding nonacylated cyanidin and peonidin 3- $O$ -sophoroside-5- $O$ -glucosides.",1
"Terahara, N, Konczak, I, Ono, H, Yoshimoto, M, Yamakawa, O",2
The Change of Total Anthocyanins in Blueberries and Their Antioxidant Effect After Drying and Freezing.,0
"This study examined the effects of freezing, storage, and cabinet drying on the anthocyanin content and antioxidant activity of blueberries (Vaccinium corymbosum L). Fresh samples were stored for two weeks at $\5^\circ$ C while frozen samples were kept for up to three months at $-20^\circ$ C. There were two drying treatments, one including osmotic pretreatment followed by cabinet drying and the other involving only cabinet drying. Total anthocyanins found in fresh blueberries were $7.2 \pm 0.5$ mg/g dry matter, expressed as cyanidin 3-rutinoside equivalents. In comparison with fresh samples, total anthocyanins in untreated and pretreated dried blueberries were significantly reduced to $4.3 \pm 0.1$ mg/g solid content, 41% loss, and $3.7 \pm 0.2$ mg/g solid content, 49% loss, respectively. Osmotic treatment followed by a thermal treatment had a greater effect on anthocyanin loss than the thermal treatment alone. In contrast, the frozen samples did not show any significant decrease in anthocyanin level during three months of storage. Measurement of the antioxidant activity of anthocyanin extracts from blueberries showed there was no significant difference between fresh, dried, and frozen blueberries.",1
"Lohachoompol, Virachnee, Srzednicki, George, Craske, John",2
Nature's Swiss Army Knife: The Diverse Protective Roles of Anthocyanins in Leaves.,0
"Anthocyanins, the pigments responsible for spectacular displays of vermilion in the leaves of deciduous trees, have long been considered an extravagant waste of a plant's resources. Contemporary research, in contrast, has begun to show that the pigments can significantly influence the way a leaf responds to environmental stress. Anthocyanins have been implicated in tolerance to stressors as diverse as drought, UV-B, and heavy metals, as well as resistance to herbivores and pathogens. By absorbing high-energy quanta, anthocyanic cell vacuoles both protect chloroplasts from the photoinhibitory and photooxidative effects of strong light, and prevent the catabolism of photolabile defence compounds. Anthocyanins also mitigate photooxidative injury in leaves by efficiently scavenging free radicals and reactive oxygen species. Far from being a useless by-product of the flavonoid pathway, these red pigments may in some instances be critical for plant survival.",1
"Gould, Kevin S",2
Localization and gene expression of steroid sulfatase by RT-PCR in cumulus cells and relationship to serum FSH levels observed during in vitro fertilization.,0
"BACKGROUND: The purpose of this study was to localize the expression of steroid sulfatase (STS) in cumulus cells and to determine the relationship between STS mRNA expression and the serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol and progesterone. METHODS: The subject group included 49 women (29 to 44 years old) for whom in vitro fertilization treatment was indicated. All subjects gave informed consent. One hundred fourteen samples of cumulus-oocyte complex (COC) were obtained under microscopic observation. Part of the COC was stained by STS antibody. RNA was extracted by phenol-chloroform method and real-time PCR was performed. Serum of each patient was collected and was measured by ELISA. RESULTS: Some of the cumulus samples were stained by STS antibody. The expression of STS mRNA in all samples was confirmed by quantitative RT-PCR. Although there was no significant correlation between the level of STS mRNA and the serum levels of estradiol, progesterone and LH, there was a statistically significant negative correlation between the level of STS mRNA expression and the serum level of FSH (n = 105, p = 0.018, r = -0.22). CONCLUSION: These results have demonstrated for the first time the expression of STS in cumulus cells by immunohistological stainings and real-time RT-PCR. STS expression in cumulus cells may be related to the control of the local steroidal environment in the oocyte. Serum FSH may control STS mRNA expression from the results of RT-PCR, although the correlation was low.",1
"Otsuka, Yukiko, Yanaihara, Atsushi, Iwasaki, Shinji, Hasegawa, Junichi, Yanaihara, Takumi, Okai, Takashi",2
Computed tomography in diagnosis and management of aneurysm of the vein of Galen.,0
"A case of aneurysm of the vein of Galen is presented to demonstrate the value of computed tomography, not only as a diagnostic procedure, but also in the overall management of the condition.",1
"Macpherson, P, Teasdale, G M, Lindsay, K W",2
Muscle fibre excitability and resting membrane potential in hamster muscular dystrophy.,0
Measurements of resting potential carried out in vivo in the dystrophic hamster and also measurements of muscle excitability showed no difference between dystrophy and healthy animals.,1
"Lenman, J A, Tulley, M",2
Malignant fibrous histocytoma producing spinal cord compression.,0
"Three cases of malignant fibrous histiocytoma presented as primary paraspinal tumours causing extradural spinal cord compression. Study of these cases suggests that pain relief is considerable after laminectomy but pain may recur with further tumour growth. Total removal is unrealistic and diagnosis, difficult. The prognosis in terms of continuing neurological deficit after surgery followed by local radiotherapy appears poor.",1
"Teddy, P J, Esiri, M M",2
Multiple sclerosis presenting with acute remitting psychiatric symptoms.,0
"Two patients are described in whom acute symptoms of apparently primary psychiatric disease could be diagnosed in retrospect as due to multiple sclerosis. In both patients the initial symptoms recovered completely. In a third patient, also presenting with mental symptoms, this diagnosis would not have been suspected on clinical grounds but is suggested by the results of modern diagnostic techniques.",1
"Matthews, W B",2
Clinical factors associated with dementia in ischaemic stroke.,0
"71 patients with an ischaemic stroke were studied. The patients were separated into two groups on the basis of the results of clinical investigation, computed tomography and psychological testing (WAIS). 40 patients showed an early dementia and 31 were without mental impairment. The mean age was 57 years in the demented group and 54 years in the non-demented group. The mean duration of the history of cerebrovascular disease was also not statistically different in both groups. The frequency of strokes was identical since 50% of the patients in both groups had more than one stroke. The history of neurological symptoms together with the neurological deficits seen on admission were distributed evenly. The dominant hemisphere was more often diseased in the demented group. Bilateral symptoms were also more common in the demented stroke patients. The WAIS showed a similar IQ in both groups but the deterioration index was significantly altered in the demented group. Hypertension was the only risk factor which differed between both groups. Cardiac disease, diabetes, viscosity and fibrinogen did not differ in both groups. The CT showed more normal scans in the non-demented group, the distribution of atrophy on its own and infarction in the left or right hemisphere were both inconclusive, whilst patients with bilateral infarcts were more common in the dementia group. Also, generalised atrophy in combination with an infarct was found more often in the demented patients.",1
"Ladurner, G, Iliff, L D, Lechner, H",2
Ultrastructural characteristics of spasm in intracerebral arterioles.,0
"Following craniotomy, three groups of cats were subjected to three different stimuli: group A hyperventilation, group B electroshock, and group C direct electric current. During electric stimuli, pial vessels were observed through a cranial window. Immediately after electric current application, some arterial vessels showed segmental spastic constriction. Tissue samples for electron-microscopy were taken from the parietal lobe and nucleus caudatus. In all three groups of animals, different types of constriction of blood vessels were observed. The respiratory alkalosis achieved by hyperventilation led to physiological constriction of the arterioles. The electric stimuli led to spastic constriction of the meningeal and intracerebral arteries and arterioles in group B and C; the entire vessel wall was greatly deformed and the vessel lumen was almost obstructed. Electroshock resulted in only moderate structural changes of the smooth muscle cells. Direct current, however, caused an extreme and bizarre smooth muscle deformation. The results show that spastic constrictions of arterioles can be clearly distinguished from physiological, that is non-spastic constriction, by morphological parameters. Electric stimulation of cerebral vessels could be an experimental condition for further investigation of intracerebral vasospasm.",1
"Roggendorf, W, Cervós-Navarro, J",2
Direct demonstration of transsynaptic degeneration in the human visual system: a comparison of retrograde and anterograde changes.,0
"Transneuronal degeneration of retinal ganglion cells was directly demonstrated in a patient who had unilateral removal of the striate cortex forty years prior to necropsy. For comparison, another case is presented showing anterograde transneuronal atrophy forty years after enucleation of one eye.",1
"Beatty, R M, Sadun, A A, Smith, L, Vonsattel, J P, Richardson, E P",2
Congophilic angiopathy of the brain: a clinical and pathological report on two siblings.,0
"Clinical and histological accounts are given of a sister and brother, dying aged 61 and 56 years respectively after illnesses lasting 5-6 years marked by a progressive mental and physical disability. The family history suggested transmission by a dominant gene. The histological findings were of a very severe congophilic angiopathy confined to the brain, spinal cord and leptomeninges and giving rise to multiple haemorrhages and softenings. There were, in addition, abundant amyloid-containing ""plaques"" of various forms, found principally in the hippocampus and cerebellar cortex. The cases are compared with similar cases in the literature, and reasons given for regarding this condition as a separate entity rather than a variant of Alzheimer's disease.",1
"Griffiths, R A, Mortimer, T F, Oppenheimer, D R, Spalding, J M",2
Linkage of autosomal dominant type I hereditary motor and sensory neuropathy to the Duffy locus on chromosome 1.,0
"Data from English families confirms the probable linkage of the loci for autosomal dominant type I hereditary motor and sensory neuropathy (HMSN) and the Duffy blood group. The locus for autosomal dominant type I HMSN is in chromosome 1 near the centromere, about 15 centimorgans from the Duffy locus. The linkage between type I HMSN and the Duffy locus and the two recombinants found between Duffy and type II HMSN support the hypothesis that there are at least two genetic variants of autosomal dominant HMSN.",1
"Guiloff, R J, Thomas, P K, Contreras, M, Armitage, S, Schwarz, G, Sedgwick, E M",2
Zinc concentrations in the cerebrospinal fluid of normal adults and patients with neurological diseases.,0
"Zinc concentrations in CSF were determined with flame atomic absorption spectrophotometry in patients assumed to have a normal CSF. No sex difference was found. There was a correlation between zinc, protein and albumin concentrations in CSF. In patients with increased protein levels in CSF or subarachnoid haemorrhage increased zinc concentrations were found.",1
"Palm, R, Hallmans, G",2
Control of soleus motoneuron excitability during muscle stretch in man.,0
"The relative contributions of intramuscular and extramuscular receptors to changes in the reflex excitability of soleus motoneurons, following muscle stretch, have been studied in man. It was found that reflex excitability was decreased by muscle stretch. The extent of the decrease was related to the amount of stretch, irrespective of whether the latter was produced by dorsiflexion of the ankle or by depression of the Achilles tendon with the ankle joint fixed. The results were unaffected by anaesthesia of the skin. It would appear that neither joint receptors nor cutaneous mechanoreceptors contribute significantly to the decrease in reflex excitability during ankle dorsiflexion and that the intramuscular receptors are mainly responsible for the effects observed.",1
"Robinson, K L, McComas, A J, Belanger, A Y",2
Cluster headaches associated with vascular malformations.,0
A vascular malformation was demonstrated in a migrainous female who had developed cluster headaches. The patient responded well to oral dihydroergotamine 1 mg twice daily.,1
"Herzeberg, L, Lenman, J A, Victoratos, G, Fletcher, F",2
Single fibre electromyographic studies in myasthenia gravis with repetitive nerve stimulation.,0
"A method is described for repetitive stimulation studies in myasthenia gravis using submaximal stimulation and single muscle fibre recording techniques. It was found that there were no impulse blockings due to neuromuscular transmission factors in normal subjects with 2 Hz stimulation, although there was a decrease or increase in the number of potentials which was caused by axonal stimulation factors. In myasthenia gravis a pathological picture was obtained, consisting of impulse blockings and facilitation at this rate in all of the eight patients studied, even those with only the ocular form of myasthenia and without surface decrement in the ADM. This technique allows study of both the minimally involved motor endplates and those with pronounced neuromuscular disturbances.",1
"Schwartz, M S, Stålberg, E",2
Epilepsy after two different neurosurgical approaches to the treatment of ruptured intracranial aneurysm.,0
"One-hundred-and-fifty-two patients who underwent surgery for intracranial aneurysm were studied to determine the incidence of postoperative epilepsy in relation to the site of the aneurysm and the type of surgical approach. The overall incidence of epilepsy was 22%. Of the 116 patients treated by the intracranial approach 27.5% developed epilepsy, in contrast with only 5% of the 36 patients who had carotid artery ligation in the neck. Epilepsy occurred most frequently (35%) with middle cerebral artery aneurysms, especially if moderate or severe operative trauma was sustained and there was postoperative dysphasia.",1
"Cabral, R J, King, T T, Scott, D F",2
Aphasic disorder in patients with closed head injury.,0
Quantitative assessment of 50 patients with closed head injury disclosed that anomic errors and word finding difficulty were prominent sequelae as nearly half of the series had defective scores on tests of naming and/or word association. Aphasic disturbance was associated with severity of brain injury as reflected by prolonged coma and injury of the brain stem.,1
"Levin, H S, Grossman, R G, Kelly, P J",2
Method for quantitative estimation of thermal thresholds in patients.,0
"A quantitative method for the examination of thermal sensibility was applied in 26 normal subjects and in patients with various neurological disorders. The stimulation technique resembled Békésy audiometry: the patient reversed the direction of the temperature change of a thermode whenever warm, cold, or thermal pain thresholds were reached. The resulting temperature curve enables a quantitative description of the subject's thermal sensibility and of the degree of impairment displayed by neurological patients.",1
"Fruhstorfer, H, Lindblom, U, Schmidt, W C",2
"Lactate dehydrogenase and aspartete transaminase of the cerebrospinal fluid in patients with brain tumours, congenital hydrocephalus, and brain abscess.",0
"The diagnostic value of CSF lactate dehydrogenase and aspartate transaminase in cases of brain tumours (except for CSF AST in the benign tumours), congenital hydrocephalus, and brain abscess is established. Tumour cyst fluids show a higher enzymatic activity than does the CSF. The two enzyme estimations do not help in differentiating the supratentorial from the infratentorial tumours. CSF AST is superior to CSF LD in discriminating the malignant and benign tumours, in so far as the AST is increases selectively in malignancy. Estimates of CSF LD are slightly superior to those of CSF AST, both in incidence of abnormality and the degree of their rise.",1
"Dharker, S R, Dharker, R S, Chaurasia, B D",2
Dysautonomia in Parkinsonism: a clinicopathological study.,0
"Necropsy studies were done on six patients with idiopathic paralysis agitans, one with multiple system atrophy including features of Parkinsonism, and one control. Autonomic functions had been evaluated during life to a varying degree. Intra-arterial blood pressure studies were carried out on two patients with paralysis agitans (cases 4 and 6) and the one with multiple system atrophy (case 7). Lewy bodies with or without cell loss were seen in the sympathetic ganglia of five cases of paralysis agitans. Three of these had orthostatic hypotension and the severity of the lesion approximately correlated with the degree of hypotension. It is concluded that the lesions of the sympathetic ganglia may play a major role in the production of orthostatic hypotension in idiopathic paralysis agitans.",1
"Rajput, A H, Rozdilsky, B",2
"Bromocriptine in Parkinsonism: long-term treatment, dose response, and comparison with levodopa.",0
"Thirty-seven patients with Parkinsonism were treated with bromocriptine 2.5-300 mg daily. Bromocriptine, alone or combined with levodopa, caused a 20-30% reduction in disability scores in 11 patients treated for one year. Tolerance did not develop during this period. Bromocriptine treatment was not of value in six patients who had previously not responded or who had lost their response to levodopa. However, in four of five patients with response swings on levodopa due to rapid changes in plasma dopa levels, the addition of bromocriptine caused a more stable response. Dose response curves to bromocriptine 12.5, 25, 50, and 100 mg and to levodopa 250, 500, 1000, and 2000 mg were studied in seven patients. Levodopa 2 g had a greater therapeutic effect and caused a greater rise in plasma growth hormone concentration than bromocriptine 100 mg. Levodopa caused emesis more commonly and hallucinations less commonly than bromocriptine. Bromocriptine appears to be a less potent stimulant than dopamine, and has both pre- and post-synaptic effects. Metoclopramide 60 mg oral was given 30 minutes before bromocriptine or levodopa to establish whether this caused dopamine-receptor blockade. Metoclopramide acted as a competitive antagonist to the anti-Parkinsonism and growth hormone effect of both drugs and in individual cases prevented emesis and hallucinations. The fall in blood pressure due to bromocriptine or levodopa was not antagonised by metoclopramide. Central and peripheral vascular dopamine receptors may be different in nature.",1
"Parkes, J D, Debono, A G, Marsden, C D",2
Weakness associated with the pathological presence of lipid in skeletal muscle: a detailed study of a patient with carnitine deficiencey.,0
A patient with muscular weakness demonstrating pathological lipid accumulation and abnormal mitochondria in skeletal muscle has been studied. The lipid accumulation and mitochondrial changes are thought to be related to the established deficiency of carnitine in this patient's muscle. The symptoms of muscular weakness associated with lipid accumulation in the skeletal muscle in the absence of complaint of muscle cramps or myglobinuria are thought to be diagnostic of carnitine deficiency. The failure of the sarcoplasmic reticulum to accumulate Ca2+ is discussed. The patient's strength responded dramatically when propranolol was added to his steroid therapy.,1
"Isaacs, H, Heffron, J J, Badenhorst, M, Pickering, A",2
Sclerosing spinal pachymeningitis. A complication of intrathecal administration of Depo-Medrol for multiple sclerosis.,0
"Reported complications of intrathecal steroid therapy include aseptic meningitis, infectious meningitis, and arachnoiditis. We report a case of sclerosing spinal pachymeningitis complicating the attempted intrathecal administration of Depo-Medrol for multiple sclerosis. The lesion is characterised by concentric laminar proliferation of neomembranes within the subdural space of the entire spinal cord and cauda equina, resulting from repeated episodes of injury and repair to the spinal dura mater by Depo-Medrol. There is clinical and laboratory evidence that Depo-Medrol produces meningeal irritation and that the vehicle is the necrotising fraction.",1
"Bernat, J L, Sadowsky, C H, Vincent, F M, Nordgren, R E, Margolis, G",2
Arterial spasm and recovery from subarachnoid haemorrhage.,0
"In a series of 120 cases of subarachnoid haemorrhage due to ruptured intracranial aneurysm the occurrence of preoperative arterial spasm was found to have no effect upon the clinical outcome. After surgery, generalised arterial spasm was found to lead to an increased probability of fatality, and to an increased probability of psychological impariment among the survivors. The occurrence of spasm only in the vessels immediately adjacent to the haemorrhage did not constitute a risk to survival. However, the presence of generalised or localised spasm led to an increased risk of neurological impairment. It is suggested that the mechanisms by which postoperative arterial spasm is responsible for fatalities and for neurological impairment are distinct.",1
"Richardson, J T",2
Histocompatibility antigens (HLA) in multiple sclerosis in Iran.,0
Thirty-five patients (19 male and 16 female) with clinically definite multiple sclerosis and 100 healthy control subjects were studied for the A and B locus of the HLA system. A significant increase of HLA A3 and A11 of the A locus and B7 of the B locus was observed in patients with multiple sclerosis compared with controls. An increase of antigen A3 was also observed in eight cases of probable multiple sclerosis. A significant increase of both A3 and B7 was observed in patients with multiple sclerosis.,1
"Lotfi, J, Nikbin, B, Derakhshan, I, Aghai, Z, Ala, F",2
Muscle hypertrophy after partial denervation: a human case.,0
"While undergoing long-term physiotherapy, a 41 year old woman with a chronic S1 radiculopathy developed progressive, painless enlargement of the weak calf. Gastrocnemius muscle biopsy disclosed changes of partial denervation and reinnervation, with small groups of type I and type II atrophic muscle fibres and abundant hypertrophic fibres of both types but mostly type II. It is postulated that, in addition to comprensatory work-induced type II muscle fibre hypertrophy, there was an element of (type I) stretched-induced hypertrophy of denervated fibres, a condition well recognised experimentally but not documented in man.",1
"Bernat, J L, Ochoa, J L",2
Myasthenia gravis: further electrophysiological and ultrastructural analysis of transmission failure in the mouse passive transfer model.,0
"Using the mouse passive transfer model the mean amplitude of miniature endplate potentials and endplate potentials of mice treated with myasthenic immunoglobulins was markedly decreased. Miniature endplate potential frequency and quantum content of endplate potentials were normal, arguing against a major presynaptic disarrangement. Under electron-microscopy no gross structural alterations of endplates were demonstrated. It is concluded that the mouse passive transfer model closely resembles human myasthenia gravis of recent onset.",1
"Toyka, K V, Birnberger, K L, Anzil, A P, Schlegel, C, Besinger, U, Struppler, A",2
Subdural haematoma and the malfunctioning shunt.,0
"Of 30 consecutive children with hydrocephalus treated by shunt implant, six developed subdural haematoma. Four of them presented with a malfunctioning shunt, and the diagnoses in all six cases were made by CT scan.",1
"Moussa, A H, Sharma, S K",2
"Global, local and focused geographic clustering for case-control data with residential histories.",0
"This paper introduces a new approach for evaluating clustering in case-control data that accounts for residential histories. Although many statistics have been proposed for assessing local, focused and global clustering in health outcomes, few, if any, exist for evaluating clusters when individuals are mobile.",1
"Jacquez, Geoffrey M, Kaufmann, Andy, Meliker, Jaymie, Goovaerts, Pierre, AvRuskin, Gillian, Nriagu, Jerome",2
Is Melanoma a stem cell tumor? Identification of neurogenic proteins in trans-differentiated cells.,0
"BACKGROUND: Although several genes and proteins have been implicated in the development of melanomas, the molecular mechanisms involved in the development of these tumors are not well understood. To gain a better understanding of the relationship between the cell growth, tumorigenesis and differentiation, we have studied a highly malignant cat melanoma cell line that trans-differentiates into neuronal cells after exposure to a feline endogenous retrovirus RD114. METHODS: To define the repertoire of proteins responsible for the phenotypic differences between melanoma and its counterpart trans-differentiated neuronal cells we have applied proteomics technology and compared protein profiles of the two cell types and identified differentially expressed proteins by 2D-gel electrophoresis, image analyses and mass spectrometry. RESULTS: The melanoma and trans-differentiated neuronal cells could be distinguished by the presence of distinct sets of proteins in each. Although approximately 60-70% of the expressed proteins were shared between the two cell types, twelve proteins were induced de novo after infection of melanoma cells with RD114 virus in vitro. Expression of these proteins in trans-differentiated cells was significantly associated with concomitant down regulation of growth promoting proteins and up-regulation of neurogenic proteins (p = < 0.001). Based on their physiologic properties, >95% proteins expressed in trans-differentiated cells could be associated with the development, differentiation and regulation of nervous system cells. CONCLUSION: Our results indicate that the cat melanoma cells have the ability to differentiate into distinct neuronal cell types and they express proteins that are essential for self-renewal. Since melanocytes arise from the neural crest of the embryo, we conclude that this melanoma arose from embryonic precursor stem cells. This model system provides a unique opportunity to identify domains of interactions between the expressed proteins that halt the tumorigenic potential of melanoma cells and drive them toward neurogenerative pathways involved in early neurogenesis. A better understanding of these proteins in a well-coordinated signaling network would also help in developing novel approaches for suppression of highly malignant tumors that arise from stem-like embryonic cells.",1
"Rasheed, Suraiya, Mao, Zisu, Chan, Jane Mc, Chan, Linda S",2
Levodopa's awakening effect on patients with Parkinsonism.,0
"The effects of levodopa on tests measuring auditory and visual perception, auditory, and visual short-term memory, verbal learning, and on attention and concentration were studied in 29 patients with Parkinsonism. Thirty-two control subjects matched with the Parkinsonism patients on age, educational level, and verbal IQ were administered the same tests to control for practice effects. Significant improvement occurred for the Parkinsonism patients in verbal learning (an intermediate memory test) and in auditory perception. These improvements were unrelated to changes in anticholinergic medications, increases in alertness or concentration, lessening of depression, or improved motor ability or control. There was no test evidence of levodopa improving visual perception, short-term auditory or visual memory, alertness or concentration. Thus, there is no objective test evidence for levodopa producing a generalized awakening or an alerting effect in Parkinsonism patients who are intellectually alert and well-orientated. Interpretation of the test findings suggests a specific awakening effect, that of improvement in intermediate memory but not in short-term memory. Overall, the Parkinsonism group scored below the control group on all tests, suggesting that cognitive impairment accompanies Parkinson's disease even in patients who are intellectually intact and well oriented.",1
"Marsh, G G, Markham, C M, Ansel, R",2
Uptake and release of  14 C-5-hydroxytryptamine by platelets in affective illness.,0
"In the search for paradigms of postulated abnormalities in indolamine function in the brain in affective disorders, 5-HT uptake and release was estimated in platelets from patients suffering from severe depressive illness. Neither of these measures was altered by the illness and the most likely explanation for the negative findings was that in this setting platelets are not a suitable model.",1
"Shaw, D M, MacSweeney, D A, Woolcock, N, Bevan-Jones, A B",2
The corneomandibular reflex.,0
"Seven patients are presented in whom a prominent corneomandibular reflex was observed. These patients all had severe cerebral and/or brain-stem disease with altered states of consciousness. Two additional patients with less prominent and inconsistent corneomandibular reflexes were seen; one had bulbar amyotrophic lateral sclerosis and one had no evidence of brain disease. The corneomandibular reflex, when found to be prominent, reflects an exaggeration of the normal. Therefore one may consider the corneomandibular hyper-reflexia as possibly due to disease of the corticobulbar system.",1
"Gordon, R M, Bender, M B",2
Late results of bulbar trigeminal tractotomy. Some remarks on recovery of sensibility.,0
"Re-examination of eight patients in whom bulbar trigeminal tractotomy had been performed 13 to 15 years previously showed that four had no complaints, and the other four had only very slight complaints about pain. In two patients a Spiller-Frazier operation had been performed after tractotomy, in two patients exairesis of the infraorbital or supraorbital nerve had been done. As bulbar trigeminal tractotomy is a major operation and the risk of recurrence is substantial, the indications for this type of operation have to remain very restricted. Theories to explain the recovery of sensation are discussed. It is possible that regeneration of transected fibres is responsible for the loss of analgesia.",1
"Moffie, D",2
Some observations on the fluttering midline echo in echoencephalography. A ballistocardiac effect and suggested cause of rupture of the septum pellucidum.,0
"In cases of hydrocephalus, echoes from the region of the cerebral median segittal plane may show a fluttering variation both in amplitude and range. Evidence is presented that, in the case studied, these movements arose from the falx cerebri and that they were caused by ballistocardiac forces presumably setting the CSF in the enlarged lateral ventricles into resonance within the enlarged cranium. Similar movements would be expected in the lateral ventricular walls as well as the septum pellucidum when the latter is imperforate. It is suggested that the lowering of the resonant frequency of the ventricular CSF in cases of hydrocephalus with both large ventricles and large heads allows ballistic and acceleratory forces applied to the hydrocephalic head to cause large pressure changes between the two lateral ventricles with consequent lateral movement of the midline structures separating them and possible rupture of the septum pellucidum, as is commonly found in hydrocephalus.",1
"White, D N, Jenkins, C O",2
Chemical epidural abscess: case report.,0
"Spinal epidural abscess accompanies blood-borne infection, vertebral osteomyelitis, or an overlying cutaneous source of infection. This report documents the development of non-infective epidural abscess where the inflammatory response was induced by the highly irritant contents (keratin and cholesterol) of an underlying epidermoid. This was associated with aseptic meningitis.",1
"Vijayan, N, Dreyfus, P M",2
Acute controlled hypotension and EEG in patients with hypertension and cerebrovascular disease.,0
"Forty-seven patients with hypertension and/or cerebrovascular disease were examined by an acute controlled hypotension test. This was performed by intravenous administration of the ganglionic blocking agent pentholonium and head-up tilting on a pivoted table with observation of the clinical neurological state and simultaneous EEG recording. Blood pressure was reduced by approximately 55% and brought to the point where signs of general cerebral ischaemia developed. By tilting back to horizontal the blood pressure returned to near the normal level. No change in focal neurological symptoms or changes in the EEG were observed, and it is concluded that the majority of hypertensive patients with or without previous stroke do tolerate normalization of their blood pressure. Controlled hypotension with tilting seems a simple and valuable test for excluding those few subjects who might not tolerate a blood pressure reduction. Whether EEG monitoring during the test increases the value of the test has not been answered.",1
"Harmsen, P, Kjaerulff, J, Skinhoj, E",2
Histochemically demonstrable fibre abnormalities in normal skeletal muscle and in muscle from carriers of Duchenne muscular dystrophy.,0
"Deltoid muscle was removed at motor point biopsy from 10 female relatives of patients with Duchenne muscular dystrophy and from seven others, with no evidence of neuromuscular disease. Transverse cryostat sections of the muscle from each case were stained for reduced diphosphopyridine nucleotide diaphorase and it was found that all contained varying numbers of degenerating type 1 fibres. The percentage of abnormal fibres in the type 1 fibre population was then calculated for each case and it was found that the muscles from the patients with dystrophic relatives contained considerably higher percentages of abnormal fibres, which also showed more severe degeneration, than did the muscles from the normal cases. There was no absolute correlation between serum creatine kinase levels and degree of pathological change, though patients with the most severe changes in their muscles had abnormally high serum creatine kinase levels. It is suggested that histochemical studies could be a useful addition to the present diagnostic tests for the carrier state in Duchenne muscular dystrophy.",1
"Morris, C J, Raybould, J A",2
Pancreatic encephalopathy.,0
"A 58 year old woman presenting with abdominal distress and a neuropsychiatric disturbance with evidence of focal neurological deficit is described. A diagnosis of pancreatic encephalopathy was made, and the patient was treated accordingly with pancreatic anti-enzymes. A survey of the literature is presented.",1
"Sharf, B, Bental, E",2
Familial cirsoid aneurysm of the scalp.,0
"One brother and one sister, of seven siblings, had cirsoid aneurysms of the occipital scalp with underlying skull defects and possible intracranial communication. Another sister had no gross scalp abnormality but radiographs of the skull revealed a small occipital bony defect. This is thought to be the first reported example of familial cirsoid aneurysm of the scalp.",1
"Khodadad, G",2
Raised intracranial pressure and cerebral blood flow. 2. Supratentorial and infratentorial mass lesions in primates.,0
"Changes in cerebral blood flow with increasing intracranial pressure were studied in anaesthetized baboons during expansion of a subdural balloon in one of two different sites. With an infratentorial balloon, cerebral blood flow bore no clear relation to intracranial pressure, but was linearly related to cerebral perfusion pressure. Apart from an initial change in some animals, cerebrovascular resistance remained constant with increasing intracranial pressure, and autoregulation appeared to be lost from the outset. With a supratentorial balloon, cerebral blood flow remained constant as intracranial pressure was increased to levels around 60 mm Hg, corresponding to a cerebral perfusion pressure range of approximately 100 to 40 mmHg. Cerebrovascular resistance fell progressively, and autoregulation appeared to be effective during this phase. At higher intracranial pressure levels (lower cerebral perfusion pressure levels), autoregulation was lost and cerebral blood flow became directly dependent on cerebral perfusion pressure. The importance of the cause of the increase in intracranial pressure on the response of the cerebral circulation and the relevance of these findings to the clinical situation are discussed.",1
"Johnston, I H, Rowan, J O, Harper, A M, Jennett, W B",2
Intracranial dissemination of pituitary adenomas.,0
Two unusual cases of pituitary adenomas giving distant secondary deposits inside the cranial cavity are presented. The authors comment on the accessible literature and the possible routes and cause of the spread. Finally they discuss the problematic nomenclature and classification of these tumours.,1
"Ogilvy, K M, Jakubowski, J",2
Normal pregnancy and successful delivery in myophosphorylase deficiency (McArdle's disease).,0
"The progress in pregnancy of a female with myophosphorylase deficiency (McArdle's disease) is described. In spite of the increased muscular effort expended, both pregnancy and labour were normal and the muscle symptoms unchanged, suggesting that compensatory mechanisms might have operated. These possible mechanisms are discussed. Women suffering from the myopathy need not expect any deterioration during pregnancy.",1
"Cochrane, P, Alderman, B",2
Post-ischaemic paraesthesiae in diabetes mellitus.,0
A quantitative assessment of post-ischaemic paraesthesiae has been made in 50 diabetic subjects and in a group of healthy age-matched controls. The results show a highly significant diminution of the paraesthetic response in the diabetic subjects. The degree of depression of the paraesthetic response was associated with the duration of the disease and the severity of the metabolic abnormality as determined by the degree of insulin dependence. Diabetics with the juvenile onset type of the disease were more adversely affected than those with the maturity onset type. There was no consistent relationship between the degree of depression of the paraesthesiae and the presence of peripheral neuropathy. The significance of these results is discussed in relation to the factors which determine the composition of the ionic micro-environment of myelinated nerve and the level of electrical excitability of the nerve fibre.,1
"Seneviratne, K N, Senanayake, N, Nimalasuriya, A",2
Cerebral circulatory and metabolic effects of hypotension produced by deep halothane anaesthesia.,0
"Hypotension to a mean blood pressure of 33 mmHg for periods of 70 to 187 minutes was induced by increasing the inspired halothane concentration in 11 baboons which were already anaesthetized with 0·5% halothane, nitrous oxide, and oxygen. During hypotension, cerebral blood flow, measured by Xenon clearance and by a carotid electromagnetic flowmeter, decreased by more than half, and sagittal sinus oxygen saturation was 46%. Cerebral oxygen uptake fell from 5·15 to 3·56 ml./100 g/min at this deeper level of halothane anaesthesia. Cerebral hyperaemia developed after hypotension in those animals which regained a mean blood pressure greater than 70 mmHg. Acidbase measurements on CSF from the cisterna magna revealed no metabolic acidosis during or after hypotension. In all four animals with intact autoregulation before hypotension, this was absent or impaired afterwards.",1
"Keaney, N P, Pickerodt, V W, McDowall, D G, Coroneos, N J, Turner, J M, Shah, Z P",2
Late residua of acute idiopathic polyneuritis.,0
"An account is given of four patients with acute idiopathic polyneuritis, leading within a few days to almost total paralysis. Two of these (cases 3 and 4) began to recover voluntary movement in the limbs in a month or less, and showed complete clinical recovery in three and 10 months respectively. The other two (cases 1 and 2) began to recover proximal limb movements after three months, reached a plateau of recovery in about two years, and never recovered movements in the distal parts of the limbs, which underwent muscular atrophy. Patient 2 died 14 years after the acute illness and was examined post mortem. The difference in recovery is explained by supposing that in patients 3 and 4 the lesions consisted predominantly of segmental demyelination, whereas in patients 1 and 2 there was extensive axon destruction at a proximal level. Recovery in the latter depended upon nerve regeneration, which restored the power of the proximal muscles, but was too slow for effective reinnervation of distal muscles. This explanation is supported by post mortem findings in patient 2. A further observation in patient 2 was of degeneration of the posterior white columns of the spinal cord, which was not due to loss of posterior root fibres. It is believed that in such cases a prognosis as to ultimate recovery of muscle power can be made about a month after the acute phase, according to whether movement has begun to return in the distal parts of the limbs. If recovery does not occur within two years it will not occur at all.",1
"Oppenheimer, D R, Spalding, J M",2
Hereditary aspects of accessory deep peroneal nerve.,0
"Hereditary aspects in the anomalous innervation of the extensor digitorum brevis muscle by the accessory deep peroneal nerve, were investigated. Utilizing electrophysiological techniques, 22% of 100 healthy unrelated individuals demonstrated this variation in innervation of one or both extensor digitorum brevis muscles. The study of family members of five of these subjects with the variation showed that 78% of relatives also had this anomalous innervation. These data suggest that hereditary factors may be significant in the occurrence of this variation and a dominant mode of inheritance may be the case.",1
"Crutchfield, C A, Gutmann, L",2
The electroencephalogram after resuscitation of cardiocirculatory arrest.,0
"Fifty-two EEGs of 31 patients were studied after resuscitation from cardiac arrest. Examples of patients with normal or mildly abnormal (category I) and severely abnormal (category II) EEGs are presented. All patients in category II died. In the patients of category I, EEGs showing no improvement or worsening indicated a fatal prognosis and possibly reflected deteriorating cardiac function caused by the basic disease process.",1
"Lemmi, H, Hubbert, C H, Faris, A A",2
The contingent negative variation and the excitability of the spinal monosynaptic reflex.,0
A method is described which permits simultaneous measurement of changes in slow electroencephalographic potentials (Contingent Negative Variation-CNV) and the excitability of the spinal monosynaptic arc (H reflex) during the foreperiod of a simple reaction time experiment. Data from 11 normal subjects show that during the development of the CNV there is an augmentation of the amplitude of the H-reflex. It is suggested that the two phenomena are controlled by a common subcortical structure.,1
"Papakostopoulos, D, Cooper, R",2
A congenital intraspinal gastroenterogenous cyst in diastematomyelia.,0
"A female neonate, with neurological signs and leucocytosis in sterile spinal fluid, was found to have anomalies of the upper thoracic vertebral bodies with a bony spur indicating diastematomyelia. The spur was removed, but symptoms recurred. Necropsy at the age of 5 months revealed an intraspinal gastroenterogenous cyst containing a perforated peptic ulcer. Analysis of eight previous reports of intraspinal enterogenous cysts, shows that, like prevertebral enterogenous cysts, they are frequently combined with defects in the vertebral bodies. This association suggests development from an embryonic ectoendodermal adhesion. Vertebral body defects are a significant pointer to the diagnosis and should not be overlooked, as curative resection is sometimes possible.",1
"Bale, P M",2
Leptomeningeal cysts diagnosed by isotope cisternography.,0
"The diagnosis of leptomeningeal cysts by isotope cisternography is described in four cases. The cysts are visualized as abnormal local collections of the radiopharmaceutical, best demonstrated 48 hours after lumbar injection. The investigation makes it possible to diagnose the cyst at an early stage, before severe clinical symptoms and changes in the bones of the skull develop. Cases of leptomeningeal cysts in various areas of the brain are described.",1
"Front, D, Minderhoud, J M, Beks, J W, Penning, L",2
Sarcoidosis of the central nervous system.,0
"Six patients with sarcoidosis of the central nervous system are described. Pathological confirmation was obtained by brain biopsy in two patients and at necropsy in two; in two patients the diagnosis was presumptive and was made on the evidence of multisystem involvement. The symptomatology, methods of diagnosis, and results of treatment are discussed.",1
"Douglas, A C, Maloney, A F",2
Symptomatic sarcoidosis of skeletal muscle.,0
Two patients with chronic sarcoid myopathy are described. Both were middle-aged females and both showed the features of pseudohypertrophy. In other aspects they contrasted markedly. In one (A.R.) the sheer volume of granuloma and its effect on muscle fibres was sufficient to explain the muscle weakness and electromyography confirmed a pure myopathy. In the other (J.W.) the muscle granuloma was sparsely distributed and an associated neuropathy contributed importantly to the disability. There was no clinical evidence of sarcoidosis of other organs in one (A.R.) but necropsy showed multisystem involvement. There was clinical and radiographic evidence of widespread sarcoidosis in the other (J.W.). Both patients showed an initial dramatic response to prednisolone. The reported literature of symptomatic muscle sarcoidosis is reviewed briefly.,1
"Douglas, A C, Macleod, J G, Matthews, J D",2
Hereditary quadriceps myopathy.,0
"A familial myopathy affecting a man, his three daughters, and one of his brothers is reported. The quadriceps muscle was predominantly involved, with aching pain as an early feature, and later prominent areas of hypertrophy projecting from patches of atrophy gave the quadriceps a most striking and unusual appearance. Presentation was in adult life, and the course was relatively benign, pelvic girdle and hand muscles becoming involved later. The evidence suggests a hereditary selective muscular dystrophy rather than polymyositis, although a hereditary form of spinal muscular atrophy could not be excluded entirely.",1
"Espir, M L, Matthews, W B",2
Histochemistry of enzyme response to trauma in the neocortex and corpus callosum of developing rat brain.,0
"The enzyme response to injury of the brain was well localized and limited. Some enzymes, even in 12 day old brain, increased rapidly, mainly in neocortical glial cells. In the corpus callosum enzymes were not significantly hyperactive before the light myelination stage. Some hyperactivity declined after 21 days. Oxidative processes and phosphate metabolism were most disturbed.",1
"Robinson, N",2
Anderson-Fabry disease: a histopathological study of three cases with observations on the mechanism of production of pain.,0
"A clinical review and histopathological study of three cases of Anderson-Fabry disease is presented and pathological changes in the central and peripheral nervous systems are reported, in some sites for the first time. These are telangiectatic changes in vessels of the sympathetic ganglia in the vertebral trunk; storage of glycolipid in pigmented cells of the substantia nigra and in anterior horn cells; and degeneration of nerve fibres in the dorsal root entry zone and substantia gelatinosa of the spinal cord. The histopathological findings suggest that in this disease pain is due to involvement of dorsal root ganglion cells with associated axonal degeneration of the small fibres in pathways subserving pain.",1
"Kahn, P",2
Hydrocephalus complicating pituitary adenoma.,0
"Hydrocephalus complicated the clinical course of four patients with pituitary adenoma. In three it was noted late, long after surgical intervention and radiotherapy had been carried out. In one patient, hydrocephalus was part of the presenting syndrome. The differential diagnosis of hypopituitarism and occult hydrocephalus is difficult. The possibility of hydrocephalus complicating a pituitary adenoma constitutes another indication for arteriography before carrying out definitive treatment, or should the clinical course be unsatisfactory at any time.",1
"Shenkin, H A, Crowley, J N",2
Arterial spasm and slowing of the cerebral circulation in the ischaemia of head injury.,0
"Carotid angiograms of 33 patients who had died during 1968 and 1969 from blunt head injury were reviewed and assessed for evidence of arterial spasm and slowing of the cerebral circulation. Spasm was found in 57·5%, a prolonged circulation time in 57·5%, and a combination of both features in 42·4% of cases. In the same group of patients there was also a high incidence of ischaemic brain damage. There appeared to be some correlation between arterial spasm and ischaemic damage in the cerebral cortex, but none in the basal ganglia or in the white matter. There was no apparent correlation between a prolonged cerebral circulation time and ischaemic brain damage.",1
"Macpherson, P, Graham, D I",2
Surgical management of an unusual carotid-cavernous fistula.,0
"A case of carotid-cavernous fistula is described associated with extradural haematoma, temporal lobe contusion, ophthalmoplegia, optic nerve injury by fracture, rhinorrhoea, orbital encephalocoele, and traumatic carotid thrombosis. The fistula was occluded by clipping of the carotid artery intracranially and also of the ophthalmic artery.",1
"Sanchis, J F, Alvarez, J A",2
Levo(-) amphetamine and dextro(+) amphetamine in the treatment of narcolepsy.,0
"The narcoleptic syndrome is a life-long and sometimes familial disorder in which there is a disturbance of the rapid eye movement phase of sleep. Patients with periodic sleep in the daytime but no other symptoms seldom develop the narcoleptic syndrome and have a separate unrelated disorder. Twelve patients with the narcoleptic syndrome were treated separately with l(-) amphetamine and d(+) amphetamine. Both drugs abolished narcolepsy, d(+) amphetamine being slightly more potent than l(-) amphetamine. In equipotent doses, unwanted effects of nervousness and insomnia were equal in frequency. No tolerance to either preparation developed during a six month period. Cataplexy was not affected by amphetamine treatment, but was abolished in two patients when clomipramine was given together with either amphetamine.",1
"Parkes, J D, Fenton, G W",2
Language after dominant hemispherectomy.,0
Linguistic and related cognitive abilities were investigated two years after dominant left hemispherectomy for cerebral malignancy in a 12 year old female. Auditory comprehension of speech was superior to other modes of language abilities with expressive speech being the least developed. Findings suggested an isolation or non-communication between the systems for speaking and for writing and visual perception. It was concluded that language mechanisms in the right hemisphere were not just at a low level of development of the functions found in the dominant hemisphere but were modified as a result of interference by preexistent spatioperceptual systems.,1
"Gott, P S",2
"Arachnodactyly, aminoaciduria, congenital cataracts, cerebellar ataxia, and delayed developmental milestones.",0
"Two male cousins are reported with arachnodactyly, selective aminoaciduria, congenital cataracts, cerebellar ataxia, and delayed developmental milestones, and a distant female relative with similar abnormalities. The syndrome is thought to be previously undescribed, though it has resemblances to Marinesco-Sjögren and Marfan's syndromes.",1
"Bhaskar, P A, Jagannathan, K, Valmikinathan, K",2
Sjögren-Larsson syndrome in two sibs with peripheral nerve involvement and bisalbuminaemia.,0
Two sibs are described with Sjögren-Larsson syndrome. Another sib died in early life with signs which appear to be indicative of the same condition. In the two cases studied we have documented signs of peripheral nerve involvement (not previously reported in the literature) which point towards a pathological process acting on ectodermal structures to a greater extent than has previously been considered.,1
"Maia, M",2
Benign aqueduct stenosis in adults.,0
A series of 55 cases is described in which hydrocephalus associated with non-neoplastic narrowing of the Sylvian aqueduct produced symptoms for the first time in adult life. The clinical features of the patients and their investigation are described and discussed.,1
"Harrison, M J, Robert, C M, Uttley, D",2
Segmental reflex pathways in spinal shock and spinal spasticity in man.,0
"Activity in three segmental pathways was compared in normal subjects, patients with spinal shock, and patients with established spinal spasticity. The Achilles tendon reflex (ATR) was used to estimate transmission in the Ia monosynaptic pathway. Evidence is produced implying that vibration activates motoneurones principally through a polysynaptic pathway. The tonic vibration reflex (TVR) was used to estimate transmission in this Ia polysynaptic pathway. The percentage of the motoneurone pool (M-response) that could be activated by these pathways was used as a measure of transmission. The H reflex (vibration)/H reflex (control) ratio was used as an estimate of the degree of presynaptic inhibition of the Ia monosynaptic pathway. The findings led to the following conclusions. (1) In spinal shock presynaptic inhibition is greater than normal, transmission in the Ia monosynaptic pathway is reduced, and in the Ia polysynaptic pathway virtually abolished. (2) In established spasticity presynaptic inhibition is impaired, transmission in the Ia monosynaptic pathway is increased, but transmission in the Ia polysynaptic pathway never recovers. (3) The failure of presynaptic inhibition associated with spasticity is a gradual process. A hypothesis to explain these findings is proposed.",1
"Ashby, P, Verrier, M, Lightfoot, E",2
Ischaemic lateral popliteal nerve palsy due to ergot intoxication.,0
A patient with ergot intoxication due to medication for migraine developed lateral popliteal nerve palsy. This is attributed to recurrent ischaemia caused by ergotamine.,1
"Perkin, G D",2
The G x U wobble base pair. A fundamental building block of RNA structure crucial to RNA function in diverse biological systems.,0
"The G x U wobble base pair is a fundamental unit of RNA secondary structure that is present in nearly every class of RNA from organisms of all three phylogenetic domains. It has comparable thermodynamic stability to Watson-Crick base pairs and is nearly isomorphic to them. Therefore, it often substitutes for G x C or A x U base pairs. The G x U wobble base pair also has unique chemical, structural, dynamic and ligand-binding properties, which can only be partially mimicked by Watson-Crick base pairs or other mispairs. These features mark sites containing G x U pairs for recognition by proteins and other RNAs and allow the wobble pair to play essential functional roles in a remarkably wide range of biological processes.",1
"Varani, G, McClain, W H",2
Coordinated response of mammalian Rad51 and Rad52 to DNA damage.,0
"Biochemical analysis has shown that mammalian Rad51 and Rad52 interact and synergize in DNA recombination reactions in vitro, but these proteins have not been shown to function together in response to DNA damage in vivo. By analysis of murine cells expressing murine Rad52 tagged with green fluorescent protein (GFP)-Rad52, we now show that DNA damage causes Rad51 and GFP-Rad52 to colocalize in distinct nuclear foci. Cells expressing GFP-Rad52 show both increased survival and an increased number of Rad51 foci, raising the possibility that Rad52 is limiting for repair. These observations provide evidence of coordinated function of Rad51 and Rad52 in vivo and support the hypothesis that Rad52 plays an important role in the DNA damage response in mammalian cells.",1
"Liu, Y, Maizels, N",2
Masked antisense: a molecular configuration for discriminating similar RNA targets.,0
"Antisense technology has great potential for the control of RNA expression, but there remain few successful applications of the technology. Expressed antisense RNA can effectively down-regulate expression of a gene over long periods, but cannot differentiate partly identical sequences, such as the mRNA of fusion genes or those with point mutants. We have designed a structured form of expressed antisense, which can discriminate between highly similar mRNA molecules. These 'masked' antisense RNAs have most of the antisense sequence sequestered within duplex elements, leaving a short single-stranded region to initiate binding to target RNA. After contacting the correct target, the structured RNA can unravel, releasing the masked antisense region to form a stable duplex with the mRNA. We demonstrate that suitable masked antisense RNA can discriminate between the two forms of BCR-ABL mRNA that result from the Philadelphia chromosomal translocations, as well as discriminating the normal BCR and ABL mRNA.",1
"Stocks, M R, Rabbitts, T H",2
Werner's syndrome protein (WRN) migrates Holliday junctions and co-localizes with RPA upon replication arrest.,0
"Individuals affected by the autosomal recessive disorder Werner's syndrome (WS) develop many of the symptoms characteristic of premature ageing. Primary fibroblasts cultured from WS patients exhibit karyotypic abnormalities and a reduced replicative life span. The WRN gene encodes a 3'-5' DNA helicase, and is a member of the RecQ family, which also includes the product of the Bloom's syndrome gene (BLM). In this work, we show that WRN promotes the ATP-dependent translocation of Holliday junctions, an activity that is also exhibited by BLM. In cells arrested in S-phase with hydroxyurea, WRN localizes to discrete nuclear foci that coincide with those formed by the single-stranded DNA binding protein replication protein A. These results are consistent with a model in which WRN prevents aberrant recombination events at sites of stalled replication forks by dissociating recombination intermediates.",1
"Constantinou, A, Tarsounas, M, Karow, J K, Brosh, R M, Bohr, V A, Hickson, I D, West, S C",2
Length recognition at the N-terminal tail for the initiation of FtsH-mediated proteolysis.,0
"FtsH-mediated proteolysis against membrane proteins is processive, and presumably involves dislocation of the substrate into the cytosol where the enzymatic domains of FtsH reside. To study how such a mode of proteolysis is initiated, we manipulated N-terminal cytosolic tails of three membrane proteins. YccA, a natural substrate of FtsH was found to require the N-terminal tail of 20 amino acid residues or longer to be degraded by FtsH in vivo. Three unrelated sequences of this segment conferred the FtsH sensitivity to YccA. An artificially constructed TM9-PhoA protein, derived from SecY, as well as the SecE protein, were sensitized to FtsH by addition of extra amino acid sequences to their N-terminal cytosolic tails. Thus, FtsH recognizes a cytosolic region of sufficient length (approximately 20 amino acids) to initiate the processive proteolysis against membrane proteins. Such a region is typically at the N-terminus and can be diverse in amino acid sequences.",1
"Chiba, S, Akiyama, Y, Mori, H, Matsuo, E, Ito, K",2
The TGF-beta family member derrière is involved in regulation of the establishment of left-right asymmetry.,0
"Although a number of genes that are involved in the establishment of left-right asymmetry have been identified, earlier events in the molecular pathway developing left-right asymmetry remain to be elucidated. Here we present evidence suggesting that the transforming growth factor-beta family member derrière is involved in the development of left-right asymmetry in Xenopus embryos. Ectopic expression of derrière on the right side can fully invert cardiac and visceral left-right orientation and nodal expression, and expression of a dominant-negative form of derrière on the left side can partially randomize the left-right orientation and nodal expression. Moreover, while expression of the dominant-negative derrière does not inhibit the activity of Vg1 directly, it can rescue the altered left-right orientation induced by Vg1. Vg1 can induce derrière in animal cap explants. These results suggest that derrière is involved in earlier molecular pathways developing the left-right asymmetry.",1
"Hanafusa, H, Masuyama, N, Kusakabe, M, Shibuya, H, Nishida, E",2
Prediction of structural domains of TAP reveals details of its interaction with p15 and nucleoporins.,0
"Vertebrate TAP is a nuclear mRNA export factor homologous to yeast Mex67p. The middle domain of TAP binds directly to p15, a protein related to the nuclear transport factor 2 (NTF2), whereas its C-terminal domain interacts with various nucleoporins, the components of the nuclear pore complex (NPC). Here, we report that the middle domain of TAP is also similar to NTF2, as well as to regions in Ras-GAP SH3 domain binding protein (G3BP) and some plant protein kinases. Based on the known three-dimensional structure of NTF2 homodimer, a heterodimerization model of TAP and p15 could be inferred. This model was confirmed by site-directed mutagenesis of residues located at the dimer interface. Furthermore, the C-terminus of TAP was found to contain a ubiquitin-associated (UBA) domain. By site-directed mutagenesis we show that a conserved loop in this domain plays an essential role in mediating TAP-nucleoporin interaction.",1
"Suyama, M, Doerks, T, Braun, I C, Sattler, M, Izaurralde, E, Bork, P",2
Caenorhabditis elegans has a single pathway to target matrix proteins to peroxisomes.,0
"All eukaryotes so far studied, including animals, plants, yeasts and trypanosomes, have two pathways to target proteins to peroxisomes. These two pathways are specific for the two types of peroxisome targeting signal (PTS) present on peroxisomal matrix proteins. Remarkably, the complete genome sequence of Caenorhabditis elegans lacks the genes encoding proteins specific for the PTS2 targeting pathway. Here we show, by expression of green fluorescent protein (GFP) reporters for both pathways, that the PTS2 pathway is indeed absent in C. elegans. Lack of this pathway in man causes severe disease due to mislocalization of PTS2-containing proteins. This raises the question as to how C. elegans has accommodated the absence of the PTS2 pathway. We found by in silico analysis that C. elegans orthologues of PTS2-containing proteins have acquired a PTS1. We propose that switching of targeting signals has allowed the PTS2 pathway to be lost in the phylogenetic lineage leading to C. elegans.",1
"Motley, A M, Hettema, E H, Ketting, R, Plasterk, R, Tabak, H F",2
Visualizing the spindle checkpoint in Drosophila spermatocytes.,0
"The spindle assembly checkpoint detects defects in spindle structure or in the alignment of the chromosomes on the metaphase plate and delays the onset of anaphase until defects are corrected. Thus far, the evidence regarding the presence of a spindle checkpoint during meiosis in male Drosophila has been indirect and contradictory. On the one hand, chromosomes without pairing partners do not prevent meiosis progression. On the other hand, some conserved components of the spindle checkpoint machinery are expressed in these cells and behave as their homologue proteins do in systems with an active spindle checkpoint. To establish whether the spindle checkpoint is active in Drosophila spermatocytes we have followed meiosis progression by time-lapse microscopy under conditions where the checkpoint is likely to be activated. We have found that the presence of a relatively high number of misaligned chromosomes or a severe disruption of the meiotic spindle results in a significant delay in the time of entry into anaphase. These observations provide the first direct evidence substantiating the activity of a meiotic spindle checkpoint in male Drosophila.",1
"Rebollo, E, González, C",2
Curbing the nuclear activities of beta-catenin. Control over Wnt target gene expression.,0
"Wnt molecules control numerous developmental processes by altering specific gene expression patterns, and deregulation of Wnt signaling can lead to cancer. Many Wnt factors employ beta-catenin as a nuclear effector. Upon Wnt stimulation, beta-catenin heterodimerizes with T-cell factor (TCF) DNA-binding proteins to form a transcriptional activator complex. As the activating subunit of this complex, beta-catenin performs dual tasks: it alleviates repression of target gene promoters and subsequently it activates them. Beta-catenin orchestrates these effects by recruiting chromatin modifying cofactors and contacting components of the basal transcription machinery. Although beta-catenin and TCFs are universal activators in Wnt signaling, their target genes display distinct temporal and spatial expression patterns. Apparently, post-translational modifications modulate the interactions between TCFs and beta-catenin or DNA, and certain transcription factors can sequester beta-catenin from TCFs while others synergize with beta-catenin-TCF complexes in a promoter-specific manner. These mechanisms provide points of intersection with other signaling pathways, and contribute to the complexity and specificity of Wnt target gene regulation.",1
"Hecht, A, Kemler, R",2
An estimate of large-scale sequencing accuracy.,0
"The accuracy of large-scale DNA sequencing is difficult to estimate without redundant effort. We have found that the mobile genetic element IS10, a component of the transposon Tn10, has contaminated a significant number of clones in the public databases, as a result of the use of the transposon in bacterial cloning strain construction. These contaminations need to be annotated as such. More positively, by defining the range of sequence variation in IS10, we have been able to determine that the rate of sequencing errors is very low, most likely surpassing the stated aim of one error or less in ten thousand bases.",1
"Hill, F, Gemünd, C, Benes, V, Ansorge, W, Gibson, T J",2
Human Cdc25 A inactivation in response to S phase inhibition and its role in preventing premature mitosis.,0
"The Cdc25 A phosphatase is required for the G1-S transition of the cell cycle and is overexpressed in human cancers. We found that it is ubiquitylated and rapidly degraded by the proteasome and that its levels increase from G1 until mitosis. By treating cells with the DNA synthesis inhibitor hydroxyurea, Cdc25 A rapidly decreased in abundance, and this was accompanied by an increase in Cdk2 phosphotyrosine content and a decrease in Cdk2 kinase activity. Cdc25 A overexpression altered the ability of cells to arrest in the presence of hydroxyurea, and caused them to undergo premature chromosome condensation. Cdc25 A overexpression could render tumor cells less sensitive to DNA replication checkpoints, thereby contributing to their genomic instability.",1
"Molinari, M, Mercurio, C, Dominguez, J, Goubin, F, Draetta, G F",2
Point mutation of bacterial artificial chromosomes by ET recombination.,0
"Bacterial artificial chromosomes (BACs) offer many advantages for functional studies of large eukaryotic genes. To utilize the potential applications of BACs optimally, new approaches that allow rapid and precise engineering of these large molecules are required. Here, we describe a simple and flexible two-step approach based on ET recombination, which permits point mutations to be introduced into BACs without leaving any other residual change in the recombinant product. Introduction of other modifications, such as small insertions or deletions, is equally feasible. The use of ET recombination to achieve site-directed mutagenesis opens access to a powerful use of BACs and is extensible to DNA molecules of any size in Escherichia coli, including the E. coli chromosome.",1
"Muyrers, J P, Zhang, Y, Benes, V, Testa, G, Ansorge, W, Stewart, A F",2
Systematic subcellular localization of novel proteins identified by large-scale cDNA sequencing.,0
"As a first step towards a more comprehensive functional characterization of cDNAs than bioinformatic analysis, which can only make functional predictions for about half of the cDNAs sequenced, we have developed and tested a strategy that allows their systematic and fast subcellular localization. We have used a novel cloning technology to rapidly generate N- and C-terminal green fluorescent protein fusions of cDNAs to examine the intracellular localizations of > 100 expressed fusion proteins in living cells. The entire analysis is suitable for automation, which will be important for scaling up throughput. For > 80% of these new proteins a clear intracellular localization to known structures or organelles could be determined. For the cDNAs where bioinformatic analyses were able to predict possible identities, the localization was able to support these predictions in 75% of cases. For those cDNAs where no homologies could be predicted, the localization data represent the first information.",1
"Simpson, J C, Wellenreuther, R, Poustka, A, Pepperkok, R, Wiemann, S",2
BRCA1 can stimulate gene transcription by a unique mechanism.,0
"Most familial breast and ovarian cancers have been linked to mutations in the BRCA1 gene. BRCA1 has been shown to affect gene transcription but how it does so remains elusive. Here we show that BRCA1 can stimulate transcription without the requirement for a DNA-tethering function in mammalian and yeast cells. Furthermore, the BRCA1 C-terminal region can stimulate transcription of the p53-responsive promoter, MDM2. Unlike many enhancer-specific activators, non-tethered BRCA1 does not require a functional TATA element to stimulate transcription. Our results suggest that BRCA1 can enhance transcription by a function additional to recruiting the transcriptional machinery to a targeted gene.",1
"Nadeau, G, Boufaied, N, Moisan, A, Lemieux, K M, Cayanan, C, Monteiro, A N, Gaudreau, L",2
The class 2 selenophosphate synthetase gene of Drosophila contains a functional mammalian-type SECIS.,0
"Synthesis of monoselenophosphate, the selenium donor required for the synthesis of selenocysteine (Sec) is catalyzed by the enzyme selenophosphate synthetase (SPS), first described in Escherichia coli. SPS homologs were identified in archaea, mammals and Drosophila. In the latter, however, an amino acid replacement is present within the catalytic domain and lacks selenide-dependent SPS activity. We describe the identification of a novel Drosophila homolog, Dsps2. The open reading frame of Dsps2 mRNA is interrupted by an UGA stop codon. The 3'UTR contains a mammalian-like Sec insertion sequence which causes translational readthrough in both transfected Drosophila cells and transgenic embryos. Thus, like vertebrates, Drosophila contains two SPS enzymes one with and one without Sec in its catalytic domain. Our data indicate further that the selenoprotein biosynthesis machinery is conserved between mammals and fly, promoting the use of Drosophila as a genetic tool to identify components and mechanistic features of the synthesis pathway.",1
"Hirosawa-Takamori, M, Jäckle, H, Vorbrüggen, G",2
Genetic disruption of mineralocorticoid receptor leads to impaired neurogenesis and granule cell degeneration in the hippocampus of adult mice.,0
"To dissect the effects of corticosteroids mediated by the mineralocorticoid (MR) and the glucocorticoid receptor (GR) in the central nervous system, we compared MR-/- mice, whose salt loss syndrome was corrected by exogenous NaCI administration, with GR-/- mice having a brain-specific disruption of the GR gene generated by the Cre/loxP-recombination system. Neuropathological analyses revealed a decreased density of granule cells in the hippocampus of adult MR-/- mice but not in mice with disruption of GR. Furthermore, adult MR-/- mice exhibited a significant reduction of granule cell neurogenesis to 65% of control levels, possibly mediated by GR due to elevated corticosterone plasma levels. Neurogenesis was unaltered in adult mice with disruption of GR. Thus, we could attribute long-term trophic effects of adrenal steroids on dentate granule cells to MR. These MR-related alterations may participate in the pathogenesis of hippocampal changes observed in ageing, chronic stress and affective disorders.",1
"Gass, P, Kretz, O, Wolfer, D P, Berger, S, Tronche, F, Reichardt, H M, Kellendonk, C, Lipp, H P, Schmid, W, Schütz, G",2
Genome-wide insertional mutagenesis in human cells by the Drosophila mobile element Minos.,0
"The development of efficient non-viral methodologies for genome-wide insertional mutagenesis and gene tagging in mammalian cells is highly desirable for functional genomic analysis. Here we describe transposon mediated mutagenesis (TRAMM), using naked DNA vectors based on the Drosophila hydei transposable element Minos. By simple transfections of plasmid Minos vectors in HeLa cells, we have achieved high frequency generation of cell lines, each containing one or more stable chromosomal integrations. The Minos-derived vectors insert in different locations in the mammalian genome. Genome-wide mutagenesis in HeLa cells was demonstrated by using a Minos transposon containing a lacZ-neo gene-trap fusion to generate a HeLa cell library of at least 10(5) transposon insertions in active genes. Multiple gene traps for six out of 12 active genes were detected in this library. Possible applications of Minos-based TRAMM in functional genomics are discussed.",1
"Klinakis, A G, Zagoraiou, L, Vassilatis, D K, Savakis, C",2
The atypical protein kinase Cs. Functional specificity mediated by specific protein adapters.,0
"Since its discovery more than 10 years ago, the atypical PKC (aPKC) subfamily has attracted great interest. A number of reports have shown that the kinases of this subfamily play critical roles in signaling pathways that control cell growth, differentiation and survival. Recently, several investigators have identified a number of aPKC-interacting proteins whose characterization is helping to unravel the mechanisms of action and functions of these kinases. These interactors include p62, Par-6, MEK5 and Par-4. The details of how these adapters serve to link the aPKCs to different receptor signaling pathways and substrates in response to specific stimuli are crucial not only for developing an understanding of the roles and functions of the aPKCs themselves, but also for more generally establishing a view of how specificity in signal transduction is achieved.",1
"Moscat, J, Diaz-Meco, M T",2
The murine SNF5/INI1 chromatin remodeling factor is essential for embryonic development and tumor suppression.,0
"The assembly of eukaryotic DNA into nucleosomes and derived higher order structures constitutes a barrier for transcription, replication and repair. A number of chromatin remodeling complexes, as well as histone acetylation, were shown to facilitate gene activation. To investigate the function of two closely related mammalian SWI/SNF complexes in vivo, we inactivated the murine SNF5/INI1 gene, a common subunit of these two complexes. Mice lacking SNF5 protein stop developing at the peri-implantation stage, showing that the SWI/SNF complex is essential for early development and viability of early embryonic cells. Furthermore, heterozygous mice develop nervous system and soft tissue sarcomas. In these tumors the wild-type allele was lost, providing further evidence that SNF5 functions as a tumor suppressor gene in certain cell types.",1
"Klochendler-Yeivin, A, Fiette, L, Barra, J, Muchardt, C, Babinet, C, Yaniv, M",2
Domain fusion between SNF1-related kinase subunits during plant evolution.,0
"Members of the conserved SNF1/AMP-activated protein kinase (AMPK) family regulate cellular responses to environmental and nutritional stress in eukaryotes. Yeast SNF1 and animal AMPKs form a complex with regulatory SNF4/AMPKgamma and SIP1/SIP2/GAL83/AMPKbeta subunits. The beta-subunits function as target selective adaptors that anchor the catalytic kinase and regulator SNF4/gamma-subunits to their kinase association (KIS) and association with the SNF1 complex (ASC) domains. Here we demonstrate that plant SNF1-related protein kinases (SnRKs) interact with an adaptor-regulator protein, AKINbetagamma, in which an N-terminal KIS domain characteristic of beta-subunits is fused with a C-terminal region related to the SNF4/AMPKgamma proteins. AKINbetagamma is constitutively expressed in plants, suppresses the yeast delta snf4 mutation, and shows glucose-regulated interaction with the Arabidopsis SnRK, AKIN11. Our results suggest that evolution of AKINbetagamma reflects a unique function of SNF1-related protein kinases in plant glucose and stress signalling.",1
"Lumbreras, V, Alba, M M, Kleinow, T, Koncz, C, Pagès, M",2
p21cip1 is required for the differentiation of oligodendrocytes independently of cell cycle withdrawal.,0
"Differentiation of most cell types requires both establishment of G1 arrest and the induction of a program related to achieving quiescence. We have chosen to study the differentiation of oligodendrocyte cells to determine the role of p27 and p21 in this process. Here we report that both p27 and p21 are required for the appropriate differentiation of these cells. p27 is required for proper withdrawal from the cell cycle, p21 is not. Instead, p21 is required for the establishment of the differentiation program following growth arrest. Similar observations were made in vivo. We show that p21-/- cells withdraw from the cell cycle similar to wild-type cells; however, early in animal life, the brain is hypomyelinated, inferring that the loss of p21 delayed myelination in the cerebellum. We found that we could complement or bypass the differentiation failure in p21-/- cells with either PD98059, an inhibitor of Mek1, or by transducing them with a tat-p16ink4a protein. We concluded that the two cdk inhibitors serve non-redundant roles in this program of differentiation, with p27 being responsible for arrest and p21 having a function in differentiation independent of its ability to control exit from the cell cycle.",1
"Zezula, J, Casaccia-Bonnefil, P, Ezhevsky, S A, Osterhout, D J, Levine, J M, Dowdy, S F, Chao, M V, Koff, A",2
Colicin A hybrids: a genetic tool for selection of type II secretion-proficient Pseudomonas strains.,0
"The gram-negative bacterium Pseudomonas aeruginosa secretes the majority of its extracellular proteins by the type II secretion mechanism, a two-step process initiated by translocation of signal peptide-bearing exoproteins across the inner membrane. The periplasmic forms are transferred across the outer membrane by a machinery consisting of 12 xcp gene products. Although the type II secretion machinery is conserved among gram-negative bacteria, interactions between the secreted proteins and the machinery are specific. The lack of a selectable phenotype has hampered the development of genetic strategies for studying type II secretion. We report a novel strategy to identify rare events, such as those that allow heterologous secretion or identification of extragenic suppressors correcting xcp defects. This is based on creating a host-vector system where the non-secretory phenotype is lethal. The original tool we designed is a hybrid protein containing elastase and the pore-forming domain of colicin A.",1
"Voulhoux, R, Lazdunski, A, Filloux, A",2
Molecular and cytological analysis of a 5.5 Mb minichromosome.,0
"Mammalian artificial chromosomes (MACs) provide a new tool for the improvement of our knowledge of chromosome structure and function. Moreover, they constitute an alternative and potentially powerful tool for gene delivery both in cultured cells and for the production of transgenic animals. In the present work we describe the molecular structure of MC1, a human minichromosome derived from chromosome 1. By means of restriction and hybridization analysis, satellite-PCR, in situ hybridization on highly extended chromatin fibres, and indirect immunofluorescence, we have established that: (i) MC1 has a size of 5.5 Mb; (ii) it consists of 1.1 Mb alphoid, 3.5 Mb Sat2 DNA, and telomeric and subtelomeric sequences at both ends; (iii) it contains an unusual region of interspersed Sat2 and alphoid DNAs at the junction of the alphoid and the Sat2 blocks; and (iv) the two alphoid blocks and the Sat2-alphoid region bind centromeric proteins suggesting that they participate in the formation of a functional kinetochore.",1
"Auriche, C, Donini, P, Ascenzioni, F",2
EGF receptor/Rolled MAP kinase signalling protects cells against activated Armadillo in the Drosophila eye.,0
"beta-catenin/Armadillo are transcriptional co-activators that mediate Wnt signalling in normal development. Activated forms of beta-catenin are oncogenic. We have constructed mutant forms of Drosophila Armadillo which correspond to common human oncogenic mutations, and find them to activate Armadillo constitutively. When expressed in the Drosophila eye, these eventually induce apoptosis in all cell types. Intriguingly, cells in the eye are resistant to the effects of activated Armadillo for a long period prior to the onset of cell death at the mid-pupal stage. This latency is conferred by EGF receptor (EGFR)/MAP kinase signalling, which prevents activated Armadillo from inducing apoptosis; when EGFR signalling naturally ceases, the cells rapidly die. Nemo, the Drosophila homologue of NLK in mice and LIT-1 in Caenorhabditis elegans, does not antagonize activated Armadillo, suggesting that the Nemo-like MAP kinases may not generally interact with Armadillo/beta-catenin. Thus, our results show that activated Armadillo is subject to a specific negative control by EGFR/Rolled MAP kinase signalling.",1
"Freeman, M, Bienz, M",2
Telomerase subunit overexpression suppresses telomere-specific checkpoint activation in the yeast yku80 mutant.,0
"Ku is a conserved heterodimeric DNA-binding protein that plays critical roles in DNA repair and telomere homeostasis. In Saccharomyces cerevisiae, deletion of YKU70 or YKU80 results in an inability to grow at 37 degrees C. This is suppressed by overexpression of several components of telomerase (EST1, EST2 and TLC1). We show that overexpression of EST2 or TLC1 in yku80 mutants does not restore efficient DNA repair, or restore normal telomere function, as measured by telomere length, single-stranded G-rich strand or transcriptional silencing. Instead, yku80 mutants activate a Rad53p-dependent DNA-damage checkpoint at 37 degrees C and this is suppressed by overexpression of EST2 or TLC1. Indeed, deletion of genes required for Rad53p activation also suppresses the yku80 temperature sensitivity. These results suggest that activation of the DNA-damage checkpoint in yku mutants at 37 degrees C does not result from reduced telomere length per se, but reflects an alteration of the telomere structure that is recognized as damaged DNA.",1
"Teo, S H, Jackson, S P",2
The Drosophila homolog of the human AF10 is an HP1-interacting suppressor of position effect variegation.,0
"In chromosomal rearrangements of acute myeloid leukaemia patients the mixed lineage leukaemia (MLL) gene, a human homolog of the Drosophila gene trithorax, is frequently fused to AF10. Here we describe the identification and a functional characterization of the Drosophila homolog dAF10. We show that dAF10 functions in heterochromatin-dependent genomic silencing of position effect variegation, a phenomenon associated with chromosomal rearrangements that cause mosaic expression of euchromatic genes when relocated next to heterochromatin. We also demonstrate that dAF10 can associate with the heterochromatin protein 1 (HP1) in vitro and in vivo. The results indicate that dAF10 is an HP1-interacting component of the heterochromatin-dependent gene silencing pathway, which either contributes to the stability of the heterochromatin complex or to its function.",1
"Linder, B, Gerlach, N, Jäckle, H",2
Homologous recombination in planta is stimulated in the absence of Rad50.,0
"Chromosomal double-strand DNA breaks must be repaired; in the absence of repair the resulting acentromeric (and telomereless) fragments may be lost and/or the broken DNA ends may recombine causing general chromosomal instability. The Rad50/Mre11/Xrs2 protein complex acts at DNA ends and is implicated in both homologous and non-homologous recombination. We have isolated a rad50 mutant of the plant Arabidopsis thaliana and show here that it has a somatic hyper-recombination phenotype in planta. This finding supports the hypothesis of a competition between homologous and illegitimate recombination in higher eukaryotes. To our knowledge, this is the first direct in vivo support for the role of this complex in chromosomal recombination in a multicellular organism and the first description of a mutation of a known gene leading to hyper-recombination in plants.",1
"Gherbi, H, Gallego, M E, Jalut, N, Lucht, J M, Hohn, B, White, C I",2
"Htm1p, a mannosidase-like protein, is involved in glycoprotein degradation in yeast.",0
"Misfolded proteins are recognized in the endoplasmic reticulum (ER), transported back to the cytoplasm and degraded by the proteasome. Processing intermediates of N-linked oligosaccharides on incompletely folded glycoproteins have an important role in their folding/refolding, and also in their targeting to proteolytic degradation. In Saccharomyces cerevisiae, we have identified a gene coding for a non-essential protein that is homologous to mannosidase I (HTM1) and that is required for degradation of glycoproteins. Deletion of the HTM1 gene does not affect oligosaccharide trimming. However, deletion of HTM1 does reduce the rate of degradation of the mutant glycoproteins such as carboxypeptidase Y, ABC-transporter Pdr5-26p and oligosaccharyltransferase subunit Stt3-7p, but not of mutant Sec61-2p, a non-glycoprotein. Our results indicate that although Htm1p is not involved in processing of N-linked oligosaccharides, it is required for their proteolytic degradation. We propose that this mannosidase homolog is a lectin that recognizes Man8GlcNAc2 oligosaccharides that serve as signals in the degradation pathway.",1
"Jakob, C A, Bodmer, D, Spirig, U, Battig, P, Marcil, A, Dignard, D, Bergeron, J J, Thomas, D Y, Aebi, M",2
Phosphorylation disrupts the central helix in Op18/stathmin and suppresses binding to tubulin.,0
"Protein phosphorylation represents a ubiquitous control mechanism in living cells. The structural prerequisites and consequences of this important post-translational modification, however, are poorly understood. Oncoprotein 18/stathmin (Op18) is a globally disordered phosphoprotein that is involved in the regulation of the microtubule (MT) filament system. Here we document that phosphorylation of Ser63, which is located within a helix initiation site in Op18, disrupts the transiently formed amphipathic helix. The phosphoryl group reduces tubulin binding 10-fold and suppresses the MT polymerization inhibition activity of Op18's C-terminal domain. Op18 represents an example where phosphorylation occurs within a regular secondary structural element. Together, our findings have implications for the prediction of phosphorylation sites and give insights into the molecular behavior of a globally disordered protein.",1
"Steinmetz, M O, Jahnke, W, Towbin, H, García-Echeverría, C, Voshol, H, Müller, D, van Oostrum, J",2
Reconstitution of Sec-dependent membrane protein insertion: nascent FtsQ interacts with YidC in a SecYEG-dependent manner.,0
"The inner membrane protein YidC is associated with the preprotein translocase of Escherichia coli and contacts transmembrane segments of nascent inner membrane proteins during membrane insertion. YidC was purified to homogeneity and co-reconstituted with the SecYEG complex. YidC had no effect on the SecA/SecYEG-mediated translocation of the secretory protein proOmpA; however, using a crosslinking approach, the transmembrane segment of nascent FtsQ was found to gain access to YidC via SecY. These data indicate the functional reconstitution of the initial stages of YidC-dependent membrane protein insertion via the SecYEG complex.",1
"van der Laan, M, Houben, E N, Nouwen, N, Luirink, J, Driessen, A J",2
Thyroid hormone regulates the obesity gene tub.,0
"Thyroid hormone T3/T4 is a major regulator of energy metabolism in vertebrates, and defects in thyroid status are frequently associated with changes in body weight. It is demonstrated here that thyroid hormone regulates in vivo and in vitro the tub gene, which when mutated in tubby mice causes obesity, insulin resistance and sensory deficits. Hypothyroidism in rats altered tub mRNA and protein in discrete brain areas. These changes could be attributed to thyroid hormone deficiency since T3/T4 treatment restored normal tub expression. T3 also upregulated tub mRNA within 4-6 h in neuronal cells in culture, suggesting that T3 is a positive regulator of tub gene expression. Thus, these results establish a novel pathway of T3 action and provide an important molecular link between thyroid status and the tubby-associated syndrome.",1
"Koritschoner, N P, Alvarez-Dolado, M, Kurz, S M, Heikenwälder, M F, Hacker, C, Vogel, F, Muñoz, A, Zenke, M",2
Sec-dependent membrane protein insertion: sequential interaction of nascent FtsQ with SecY and YidC.,0
"Recent studies identified YidC as a novel membrane factor that may play a key role in membrane insertion of inner membrane proteins (IMPs), both in conjunction with the Sec-translocase and as a separate entity. Here, we show that the type II IMP FtsQ requires both the translocase and, to a lesser extent, YidC in vivo. Using photo-crosslinking we demonstrate that the transmembrane (TM) domain of the nascent IMP FtsQ inserts into the membrane close to SecY and lipids, and moves to a combined YidC/lipid environment upon elongation. These data are consistent with a crucial role for YidC in the lateral transfer of TM domains from the Sec translocase into the lipid bilayer.",1
"Urbanus, M L, Scotti, P A, Froderberg, L, Saaf, A, de Gier, J W, Brunner, J, Samuelson, J C, Dalbey, R E, Oudega, B, Luirink, J",2
Two cyclophilin A homologs with shared and distinct functions important for growth and virulence of Cryptococcus neoformans.,0
"Cyclophilin A is the target of the immunosuppressant cyclosporin A (CsA) and is encoded by a single unique gene conserved from yeast to humans. In the pathogenic fungus Cryptococcus neoformans, two homologous linked genes, CPA1 and CPA2, were found to encode two conserved cyclophilin A proteins. In contrast to Saccharomyces cerevisiae, in which cyclophilin A mutations confer CsA resistance but few other phenotypes, cyclophilin A mutations conferred dramatic phenotypes in C. neoformans. The Cpa1 and Cpa2 cyclophilin A proteins play a shared role in cell growth, mating, virulence and CsA toxicity. The Cpa1 and Cpa2 proteins also have divergent functions. cpa1 mutants are inviable at 39 degrees C and attenuated for virulence, whereas cpa2 mutants are viable at 39 degrees C and fully virulent. cpa1 cpa2 double mutants exhibited synthetic defects in growth and virulence. Cyclophilin A active site mutants restored growth of cpa1 cpa2 mutants at ambient but not at higher temperatures, suggesting that the prolyl isomerase activity of cyclophilin A has an in vivo function.",1
"Wang, P, Cardenas, M E, Cox, G M, Perfect, J R, Heitman, J",2
SEK-1 MAPKK mediates Ca2+ signaling to determine neuronal asymmetric development in Caenorhabditis elegans.,0
"The mitogen-activated protein kinase (MAPK) pathway is a highly conserved signaling cascade that converts extracellular signals into various outputs. In Caenorhabditis elegans, asymmetric expression of the candidate odorant receptor STR-2 in either the left or the right of two bilaterally symmetrical olfactory AWC neurons is regulated by axon contact and Ca2+ signaling. We show that the MAPK kinase (MAPKK) SEK-1 is required for asymmetric expression in AWC neurons. Genetic and biochemical analyses reveal that SEK-1 functions in a pathway downstream of UNC-43 and NSY-1, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and MAPK kinase kinase (MAPKKK), respectively. Thus, the NSY-1-SEK-1-MAPK cascade is activated by Ca2+ signaling through CaMKII and establishes asymmetric cell fate decision during neuronal development.",1
"Tanaka-Hino, Miho, Sagasti, Alvaro, Hisamoto, Naoki, Kawasaki, Masato, Nakano, Shunji, Ninomiya-Tsuji, Jun, Bargmann, Cornelia I, Matsumoto, Kunihiro",2
Wnt signals are transmitted through N-terminally dephosphorylated beta-catenin.,0
"beta-catenin mediates Wnt signaling by acting as the essential co-activator for TCF transcription factors. Wnt signaling increases the half-life and therefore the absolute level of beta-catenin in responding cells. The current model states that these changes in beta-catenin stability set the threshold for Wnt signaling. However, we find that pharmacological inhibition of proteasome activity by ALLN leads to accumulation of cytosolic beta-catenin but not to increased TCF-mediated transcription. In addition, in temperature-sensitive ubiquitylation mutant CHO cells inhibition of ubiquitylation increases beta-catenin levels, but does not induce transcriptional activation of TCF reporter genes. Using an antibody specific for beta-catenin dephosphorylated at residues Ser37 and Thr41, we show that Wnt signals specifically increase the levels of dephosphorylated beta-catenin, whereas ALLN does not. We conclude that changes in the phosphorylation status of the N-terminus of beta-catenin that occur upon Wnt signaling independently affect the signaling properties and half-life of beta-catenin. Hence, Wnt signals are transduced via N-terminally dephosphorylated beta-catenin.",1
"Staal, Frank J T, van Noort, Mascha, Strous, Ger J, Clevers, Hans C",2
The Drosophila Toll-9 activates a constitutive antimicrobial defense.,0
"The Toll family of transmembrane proteins participates in signaling infection during the innate immune response. We analyzed the nine Drosophila Toll proteins and found that wild-type Toll-9 behaves similar to gain-of-function Toll-1. Toll-9 activates strongly the expression of drosomycin, and utilizes similar signaling components to Toll-1 in activating the antifungal gene. The predicted protein sequence of Toll-9 contains a tyrosine residue in place of a conserved cysteine, and this residue switch is critical for the high activity of Toll-9. The Toll-9 gene is expressed in adult and larval stages prior to microbial challenge, and the expression correlates with the high constitutive level of drosomycin mRNA in the animals. The results suggest that Toll-9 is a constitutively active protein, and implies its novel function in protecting the host by maintaining a substantial level of antimicrobial gene products to ward off the continuous challenge of microorganisms.",1
"Ooi, James Y, Yagi, Yoshimasa, Hu, Xiaodi, Ip, Y Tony",2
When repair meets chromatin. First in series on chromatin dynamics.,0
"In eukaryotic cells, the inheritance of both the DNA sequence and its organization into chromatin is critical to maintain genome stability. This maintenance is challenged by DNA damage. To fully understand how the cell can tolerate genotoxic stress, it is necessary to integrate knowledge of the nature of DNA damage, its detection and its repair within the chromatin environment of a eukaryotic nucleus. The multiplicity of the DNA damage and repair processes, as well as the complex nature of chromatin, have made this issue difficult to tackle. Recent progress in each of these areas enables us to address, both at a molecular and a cellular level, the importance of inter-relationships between them. In this review we revisit the 'access, repair, restore' model, which was proposed to explain how the conserved process of nucleotide excision repair operates within chromatin. Recent studies have identified factors potentially involved in this process and permit refinement of the basic model. Drawing on this model, the chromatin alterations likely to be required during other processes of DNA damage repair, particularly double-strand break repair, are discussed and recently identified candidates that might perform such alterations are highlighted.",1
"Green, Catherine M, Almouzni, Geneviève",2
HAT activity is essential for CBP-1-dependent transcription and differentiation in Caenorhabditis elegans.,0
"The p300/CBP family of transcriptional coactivators possesses multiple functional domains, including a histone acetyltransferase (HAT) and several activation domains. A number of models have been proposed to account for their roles in transcriptional activation, including interactions with basal transcription machinery and chromatin remodeling. However, individual contributions of these domains to transcriptional activation and their significance in living organisms remain unclear. We addressed the importance of the HAT activity of CBP-1, the worm ortholog of p300/CBP, in Caenorhabditis elegans with three different and complementary approaches. These include allele-specific RNA-mediated interference (RNAi), genetic rescue and the use of a specific chemical inhibitor of the p300/CBP HAT. Our findings demonstrate that HAT activity is of primary importance for CBP-1 to regulate transcription and to promote differentiation during C. elegans embryogenesis.",1
"Victor, Martin, Bei, Yanxia, Gay, Frederique, Calvo, Dominica, Mello, Craig, Shi, Yang",2
The processivity factor beta controls DNA polymerase IV traffic during spontaneous mutagenesis and translesion synthesis in vivo.,0
"The dinB-encoded DNA polymerase IV (Pol IV) belongs to the recently identified Y-family of DNA polymerases. Like other members of this family, Pol IV is involved in translesion synthesis and mutagenesis. Here, we show that the C-terminal five amino acids of Pol IV are essential in targeting it to the beta-clamp, the processivity factor of the replicative DNA polymerase (Pol III) of Escherichia coli. In vivo, the disruption of this interaction obliterates the function of Pol IV in both spontaneous and induced mutagenesis. These results point to the pivotal role of the processivity clamp during DNA polymerase trafficking in the vicinity of damaged-template DNA.",1
"Lenne-Samuel, Nathalie, Wagner, Jérôme, Etienne, Hélène, Fuchs, Robert P P",2
JNK functions in the non-canonical Wnt pathway to regulate convergent extension movements in vertebrates.,0
"Recent genetic studies in Drosophila identified a novel non-canonical Wnt pathway, the planar cell polarity (PCP) pathway, that signals via JNK to control epithelial cell polarity in Drosophila. Most recently, a pathway regulating convergent extension movements during gastrulation in vertebrate embryos has been shown to be a vertebrate equivalent of the PCP pathway. However, it is not known whether the JNK pathway functions in this non-canonical Wnt pathway to regulate convergent extension movements in vertebrates. In addition, it is not known whether JNK is in fact activated by Wnt stimulation. Here we show that Wnt5a is capable of activating JNK in cultured cells, and present evidence that the JNK pathway mediates the action of Wnt5a to regulate convergent extension movements in Xenopus. Our results thus demonstrate that the non-canonical Wnt/JNK pathway is conserved in both vertebrate and invertebrate and define that JNK has an activity to regulate morphogenetic cell movements.",1
"Yamanaka, Hiroaki, Moriguchi, Tetsuo, Masuyama, Norihisa, Kusakabe, Morioh, Hanafusa, Hiroshi, Takada, Ritsuko, Takada, Shinji, Nishida, Eisuke",2
Trypanosoma cruzi macrophage infectivity potentiator has a rotamase core and a highly exposed alpha-helix.,0
"The macrophage infectivity potentiator protein from Trypanosoma cruzi (TcMIP) is a major virulence factor secreted by the etiological agent of Chagas' disease. It is functionally involved in host cell invasion. We have determined the three-dimensional crystal structure of TcMIP at 1.7 A resolution. The monomeric protein displays a peptidyl-prolyl cis-trans isomerase (PPIase) core, encompassing the characteristic rotamase hydrophobic active site, thus explaining the strong inhibition of TcMIP by the immunosuppressant FK506 and related drugs. In TcMIP, the twisted beta-sheet of the core is extended by an extra beta-strand, preceded by a long, exposed N-terminal alpha-helix, which might be a target recognition element. An invasion assay shows that the MIP protein from Legionella pneumophila (LpMIP), which has an equivalent N-terminal alpha-helix, can substitute for TcMIP. An additional exposed alpha-helix, this one unique to TcMIP, is located in the C-terminus of the protein. The high-resolution structure reported here opens the possibility for the design of new inhibitory drugs that might be useful for the clinical treatment of American trypanosomiasis.",1
"Pereira, Pedro José Barbosa, Vega, M Cristina, González-Rey, Elena, Fernández-Carazo, Rafael, Macedo-Ribeiro, Sandra, Gomis-Rüth, F Xavier, González, Antonio, Coll, Miquel",2
A novel mechanism of matrix metalloproteinase-9 gene expression implies a role for keratinization.,0
"To investigate the pathophysiological role of matrix metalloproteinase (MMP)-9 in the skin, we analyzed MMP-9 expression from human keratinocytes in culture. MMP-9 and the terminal differentiation marker involucrin were co-localized in the same keratinocytes with a high concentration of Ca(2+), a potent stimulator of differentiation. We identified the novel KRE-M9 element, further downstream to the previously reported TPA responsive element in the MMP-9 promoter, and both of these two elements were shown to be important for MMP-9 transcription and Ca(2+) induction. The concomitant upregulation of MMP-9 and involucrin transcripts was probably due to the very similar gene regulatory elements, KRE-M9 and KRE-4, in their respective promoters. These results indicate a novel mechanism of transcriptional regulation for MMP-9 in the process of keratinization, implying the probable association of apoptosis and differentiation of keratinocytes in epidermal skin tissue.",1
"Kobayashi, T, Kishimoto, J, Ge, Y, Jin, W, Hudson, D L, Ouahes, N, Ehama, R, Shinkai, H, Burgeson, R E",2
Cavities and packing defects in the structural dynamics of myoglobin.,0
"Small globular proteins contain internal cavities and packing defects that reduce thermodynamic stability but seem to play a role in controlling function by defining pathways for the diffusion of the ligand/substrate to the active site. In the case of myoglobin (Mb), a prototype for structure-function relationship studies, the photosensitivity of the adduct of the reduced protein with CO, O2 and NO allows events related to the migration of the ligand through the matrix to be followed. The crystal structures of intermediate states of wild-type (wt) and mutant Mbs show the photolysed CO to be located either in the distal heme pocket (primary docking site) or in one of two alternative cavities (secondary docking sites) corresponding to packing defects accessible to an atom of xenon. These results convey the general picture that pre-existing internal cavities are involved in controlling the dynamics and reactivity of the reactions of Mb with O2 and other ligands, including NO.",1
"Brunori, M, Gibson, Q H",2
Regulation of epidermal growth factor receptor endocytosis by wortmannin through activation of Rab5 rather than inhibition of phosphatidylinositol 3-kinase.,0
"The involvement of phosphatidylinositol 3-kinase (PI3K) in membrane trafficking in mammalian cells has largely come from experiments with wortmannin. This compound inhibits endosome fusion in vitro, possibly by inhibiting the production of phosphatidylinositol (PtdIns)-3-P, which co-regulates EEA1 with Rab5. However, the results from wortmannin inhibition experiments performed in vivo differ significantly. We have recently shown that wortmannin enlarges endosomes containing the epidermal growth factor receptor (EGFR) and enhances the lysosomal degradation of EGFR. In this report, we demonstrate that addition of the PI3K reaction products does not suppress wortmannin-induced enlargement of EGFR-containing endosomes and enhancement of EGFR degradation. Moreover, the effects of wortmannin on the intracellular trafficking of EGFR mimic those of the permanently activated Rab5 mutant, Rab5 Q79L, which stimulates endosome fusion. We also found that an inactive Rab5 mutant, Rab5 S34N, blocks wortmannin-induced endosome enlargement and that wortmannin stimulates the activation of Rab5. We further showed that wortmannin reduced the membrane association of p120 Ras GTPase-activating protein (GAP) and inhibited the interaction between Rab5 and p120 Ras GAP. We conclude that wortmannin alters intracellular trafficking of EGFR by activating Rab5 rather than by inhibiting PI3K.",1
"Chen, X, Wang, Z",2
Histones H3/H4 form a tight complex with the inner nuclear membrane protein LBR and heterochromatin protein 1.,0
"We have recently shown that heterochromatin protein 1 (HP1) interacts with the nuclear envelope in an acetylation-dependent manner. Using purified components and in vitro assays, we now demonstrate that HP1 forms a quaternary complex with the inner nuclear membrane protein LBR and a sub-set of core histones. This complex involves histone H3/H4 oligomers, which mediate binding of LBR to HP1 and cross-link these two proteins that do not interact directly with each other. Consistent with previous observations, HP1 and LBR binding to core histones is strongly inhibited when H3/H4 are modified by recombinant CREB-binding protein, revealing a new mechanism for anchoring domains of under-acetylated chromatin to the inner nuclear membrane.",1
"Polioudaki, H, Kourmouli, N, Drosou, V, Bakou, A, Theodoropoulos, P A, Singh, P B, Giannakouros, T, Georgatos, S D",2
RanBP3 influences interactions between CRM1 and its nuclear protein export substrates.,0
"We investigated the role of RanBP3, a nuclear member of the Ran-binding protein 1 family, in CRM1-mediated protein export in higher eukaryotes. RanBP3 interacts directly with CRM1 and also forms a trimeric complex with CRM1 and RanGTP. However, RanBP3 does not bind to CRM1 like an export substrate. Instead, it can stabilize CRM1-export substrate interaction. Nuclear RanBP3 stimulates CRM1-dependent protein export in permeabilized cells. These data indicate that RanBP3 functions by a novel mechanism as a cofactor in recognition and export of certain CRM1 substrates. In vitro, RanBP3 binding to CRM1 affects the relative affinity of CRM1 for different substrates.",1
"Englmeier, L, Fornerod, M, Bischoff, F R, Petosa, C, Mattaj, I W, Kutay, U",2
Visualization of recombination intermediates produced by RAD52-mediated single-strand annealing.,0
"Double-strand breaks (DSBs) occur frequently during DNA replication. They are also caused by ionizing radiation, chemical damage or as part of the series of programmed events that occur during meiosis. In yeast, DSB repair requires RAD52, a protein that plays a critical role in homologous recombination. Here we describe the actions of human RAD52 protein in a model system for single-strand annealing (SSA) using tailed (i.e. exonuclease resected) duplex DNA molecules. Purified human RAD52 protein binds resected DSBs and promotes associations between complementary DNA termini. Heteroduplex intermediates of these recombination reactions have been visualized by electron microscopy, revealing the specific binding of multiple rings of RAD52 to the resected termini and the formation of large protein complexes at heteroduplex joints formed by RAD52-mediated annealing.",1
"Van Dyck, E, Stasiak, A Z, Stasiak, A, West, S C",2
Dynactin-membrane interaction is regulated by the C-terminal domains of p150(Glued).,0
"Dynactin has been proposed to link the microtubule-associated motor cytoplasmic dynein with membranous cargo; however, the mechanism by which dynactin-membrane interaction is regulated is unknown. Here we show that dynein and dynactin exist in discrete cytosolic and membrane-bound states in the filamentous fungus Neurospora crassa. Results from in vitro membrane-binding studies show that dynein and dynactin-membrane interaction is co-dependent. p150(Glued) of dynactin has been shown to interact with dynein intermediate chain and dynactin Arp1 filament; however, it is not known to play a direct role in membrane binding. In this report we describe our analysis of 43 p150(Glued) mutants, and we show that C-terminal deletions which remove the terminal coiled-coil (CC2) and basic domain (BD) result in constitutive dynactin-membrane binding. In vitro addition of recombinant p150(Glued) CC2+BD protein blocks dynactin-membrane binding. We propose that the C-terminal domains of p150(Glued) regulate dynactin-membrane binding through a steric mechanism that controls accessibility of the Arp1 filament of dynactin to membranous cargo.",1
"Kumar, S, Zhou, Y, Plamann, M",2
Ubiquitin-associated (UBA) domains in Rad23 bind ubiquitin and promote inhibition of multi-ubiquitin chain assembly.,0
"Rad23 is a DNA repair protein that promotes the assembly of the nucleotide excision repair complex. Rad23 can interact with the 26S proteasome through an N-terminal ubiquitin-like domain, and inhibits the assembly of substrate-linked multi-ubiquitin (multi-Ub) chains in vitro and in vivo. Significantly, Rad23 can bind a proteolytic substrate that is conjugated to a few ubiquitin (Ub) moieties. We report here that two ubiquitin-associated (UBA) domains in Rad23 form non-covalent interactions with Ub. A mutant that lacked either UBA sequence was capable of blocking the assembly of substrate-linked multi-Ub chains, although a mutant that lacked both UBA domains was significantly impaired. These studies suggest that the interaction with Ub is required for Rad23 activity, and that other UBA-containing proteins may have a similar function.",1
"Chen, L, Shinde, U, Ortolan, T G, Madura, K",2
Florid plaques in ovine PrP transgenic mice infected with an experimental ovine BSE.,0
"The occurrence of the variant Creutzfeldt-Jakob disease (vCJD), related to bovine spongiform encephalopathy (BSE), raises the important question of the sources of human contamination. The possibility that sheep may have been fed with BSE-contaminated foodstuff raises the serious concern that BSE may now be present in sheep without being distinguishable from scrapie. Sensitive models are urgently needed given the dramatic consequences of such a possible contamination on animal and human health. We inoculated transgenic mice expressing the ovine PrP gene with a brain homogenate from sheep experimentally infected with BSE. We found numerous typical florid plaques in their brains. Such florid plaques are a feature of vCJD in humans and experimental BSE infection in macaques. Our observation represents the first description, after a primary infection, of this hallmark in a transgenic mouse model. Moreover, these mice appear to be a promising tool in the search for BSE in sheep.",1
"Crozet, C, Bencsik, A, Flamant, F, Lezmi, S, Samarut, J, Baron, T",2
From the cradle to the grave: molecular chaperones that may choose between folding and degradation.,0
"Molecular chaperones are known to facilitate cellular protein folding. They bind non-native proteins and orchestrate the folding process in conjunction with regulatory cofactors that modulate the affinity of the chaperone for its substrate. However, not every attempt to fold a protein is successful and chaperones can direct misfolded proteins to the cellular degradation machinery for destruction. Protein quality control thus appears to involve close cooperation between molecular chaperones and energy-dependent proteases. Molecular mechanisms underlying this interplay have been largely enigmatic so far. Here we present a novel concept for the regulation of the eukaryotic Hsp70 and Hsp90 chaperone systems during protein folding and protein degradation.",1
"Höhfeld, J, Cyr, D M, Patterson, C",2
Irresistible IRES. Attracting the translation machinery to internal ribosome entry sites.,0
"Studies on the control of eukaryotic translation initiation by a cap-independent recruitment of the 40S ribosomal subunit to internal messenger RNA sequences called internal ribosome entry sites (IRESs) have shown that these sequence elements are present in a growing list of viral and cellular RNAs. Here we discuss their prevalence, mechanisms whereby they may function and their uses in regulating gene expression.",1
"Vagner, S, Galy, B, Pyronnet, S",2
RNA and sex determination in Caenorhabditis elegans. Post-transcriptional regulation of the sex-determining tra-2 and fem-3 mRNAs in the Caenorhabditis elegans hermaphrodite.,0
"The Caenorhabditis elegans hermaphrodite sequentially produces sperm and oocytes from a single pool of precursors. Therefore, the hermaphrodite's germ line is the site of two major cell fate decisions: a germ cell precursor first undergoes a mitosis/meiosis decision and then a sperm/oocyte decision. While the mitosis/meiosis decision is governed by Notch/GLP-1 signalling, the sperm/oocyte decision relies on post-transcriptional regulation of two key mRNAs, tra-2 and fem-3. This review focuses on factors that are required for the silencing of these mRNAs, which results in the sequential production of sperm and oocytes. Most factors that regulate the expression of tra-2 and fem-3 are homologous to proteins involved in RNA regulation in yeast, mammals or Drosophila, suggesting that at least some of the molecular mechanisms regulating the two worm mRNAs have been conserved throughout evolution.",1
"Puoti, A, Pugnale, P, Belfiore, M, Schläppi, A C, Saudan, Z",2
Distinct but overlapping domains of AKAP95 are implicated in chromosome condensation and condensin targeting.,0
"A-kinase (or PKA)-anchoring protein AKAP95 is a zinc-finger protein implicated in mitotic chromosome condensation by acting as a targeting molecule for the condensin complex. We have identified determinants of chromatin-binding, condensin-targeting and chromosome-condensation activities of AKAP95. Binding of AKAP95 to chromatin is conferred by residues 387-450 and requires zinc finger ZF1. Residues 525-569 are essential for condensation of AKAP95-free chromatin and condensin recruitment to chromosomes. Mutation of either zinc finger of AKAP95 abolishes condensation. However, ZF1 is dispensable for condensin targeting, whereas the C-terminal ZF2 is required. AKAP95 interacts with Xenopus XCAP-H condensin subunit in vitro and in vivo but not with the human hCAP-D2 subunit. The data illustrate the involvement of overlapping, but distinct, domains of AKAP95 for condensin recruitment and chromosome condensation and argue for a key role of ZF1 in chromosome condensation and ZF2 in condensin targeting. Moreover, condensin recruitment to chromatin is not sufficient to promote condensation.",1
"Eide, Turid, Carlson, Cathrine, Taskén, Kristin A, Hirano, Tatsuya, Taskén, Kjetil, Collas, Philippe",2
Regulation of mitochondrial D-loops by transcription factor A and single-stranded DNA-binding protein.,0
"During replication, mitochondrial DNA (mtDNA) takes on a triple-stranded structure called a D-loop. Although their physiological roles are not understood, D-loops are implicated in replication and transcription of mtDNA. Little is known about the turnover of D-loops. We investigated the effects of mitochondrial transcription factor A (TFAM) and single-stranded DNA-binding protein (mtSSB) on D-loops. In human HeLa cells, TFAM and mtSSB are, respectively, 1700- and 3000-fold more abundant than mtDNA. This level of TFAM is two orders of magnitude higher than reported previously and is sufficient to wrap human mtDNA entirely. TFAM resolves D-loops in vitro if added in similar stoichiometries. mtSSB inhibits the resolution of mtDNA by TFAM but enhances resolution by RecG, a junction-specific helicase from Escherichia coli. Hence, mtSSB functions in both stabilization and resolution. We propose that TFAM and mtSSB are cooperatively involved in stabilizing D-loops and in the maintenance of mtDNA.",1
"Takamatsu, Chihiro, Umeda, Shuyo, Ohsato, Takashi, Ohno, Tetsuji, Abe, Yoshito, Fukuoh, Atsushi, Shinagawa, Hideo, Hamasaki, Naotaka, Kang, Dongchon",2
STAG2 and Rad21 mammalian mitotic cohesins are implicated in meiosis.,0
"STAG/SA proteins are specific cohesin complex subunits that maintain sister chromatid cohesion in mitosis and meiosis. Two members of this family, STAG1/SA1 and STAG2/SA2,double dagger are classified as mitotic cohesins, as they are found in human somatic cells and in Xenopus laevis as components of the cohesin(SA1) and cohesin(SA2) complexes, in which the shared subunits are Rad21/SCC1, SMC1 and SMC3 proteins. A recently reported third family member, STAG3, is germinal cell-specific and is a subunit of the meiotic cohesin complex. To date, the meiosis-specific cohesin complex has been considered to be responsible for sister chromatid cohesion during meiosis. We studied replacement of the mitotic by the meiotic cohesin complex during mouse germinal cell maturation, and we show that mammalian STAG2 and Rad21 are also involved in several meiosis stages. Immunofluorescence results suggest that a cohesin complex containing Rad21 and STAG2 cooperates with a STAG3-specific complex to maintain sister chromatid cohesion during the diplotene stage of meiosis.",1
"Prieto, Ignacio, Pezzi, Nieves, Buesa, Jose M, Kremer, Leonor, Barthelemy, Isabel, Carreiro, Candelas, Roncal, Fernando, Martinez, Alicia, Gomez, Lucio, Fernandez, Raul, Martinez-A, Carlos, Barbero, Jose L",2
Hyperphosphorylation and insolubility of alpha-synuclein in transgenic mouse oligodendrocytes.,0
"(Oligodendro)glial cytoplasmic inclusions composed of alpha-synuclein (alpha SYN) characterize multiple system atrophy (MSA). Mature oligodendrocytes (OLs) do not normally express alpha SYN, so MSA pathology may arise from aberrant expression of alpha SYN in OLs. To study pathological deposition of alpha SYN in OLs, transgenic mice were generated in which human wild-type alpha SYN was driven by a proteolipid protein promoter. Transgenic alpha SYN was detected in OLs but no other brain cell type. At the light microscopic level, the transgenic alpha SYN profiles resembled glial cytoplasmic inclusions. Strikingly, the diagnostic hyperphosphorylation at S129 of alpha SYN was reproduced in the transgenic mice. A significant proportion of the transgenic alpha SYN was detergent insoluble, as in MSA patients. The histological and biochemical abnormalities were specific for the disease-relevant alpha SYN because control green fluorescent protein was fully soluble and evenly distributed throughout OL cell bodies and processes. Thus, ectopic expression alpha SYN in OLs might initiate salient features of MSA pathology.",1
"Kahle, Philipp J, Neumann, Manuela, Ozmen, Laurence, Muller, Veronika, Jacobsen, Helmut, Spooren, Will, Fuss, Babette, Mallon, Barbara, Macklin, Wendy B, Fujiwara, Hideo, Hasegawa, Masato, Iwatsubo, Takeshi, Kretzschmar, Hans A, Haass, Christian",2
A Toc75-like protein import channel is abundant in chloroplasts.,0
"Chloroplasts import post-translationally most of their constituent polypeptides via two distinct translocon units located in the outer and inner envelope. The protein import channel of the translocon of the outer envelope of chloroplasts, Toc75, is the most abundant protein in that membrane. We identify a novel Toc75 homologous protein, atToc75-V, a prominent protein that is clearly localized in the chloroplastic outer envelope. Phylogenetic analysis indicates that Toc75-V is more closely related to its prokaryotic ancestors than to Toc75 from plants. The presence of a second translocation channel suggests that alternative, previously unrecognized import routes into chloroplasts might exist.",1
"Eckart, Kerstin, Eichacker, Lutz, Sohrt, Karen, Schleiff, Enrico, Heins, Lisa, Soll, Jürgen",2
Initial activation of cyclin-B1-cdc2 kinase requires phosphorylation of cyclin B1.,0
"At the G(2)/M transition of the cell cycle, the cdc25c phosphatase dephosphorylates inhibitory residues of cdc2, and cyclin-B-cdc2 kinase (MPF) is activated. Phosphorylation of cyclin B1 induces its nuclear accumulation, and, since cdc25c is also believed to accumulate and activate shortly before G(2)/M in the nucleus, it has been proposed that this induces cyclin-B1-cdc2 kinase activation. We demonstrate that cyclin B1 phosphorylation has another essential function in vivo: it is required for cdc25c and MPF activation, which does not require nuclear accumulation of cyclin B1, and occurs in the cytoplasm.",1
"Peter, Marion, Le Peuch, Christian, Labbé, Jean-Claude, Meyer, April N, Donoghue, Daniel J, Dorée, Marcel",2
"NurA, a novel 5'-3' nuclease gene linked to rad50 and mre11 homologs of thermophilic Archaea.",0
"We isolated and characterized a new nuclease (NurA) exhibiting both single-stranded endonuclease activity and 5'-3' exonuclease activity on single-stranded and double-stranded DNA from the hyperthermophilic archaeon Sulfolobus acidocaldarius. Nuclease homologs are detected in all thermophilic archaea and, in most species, the nurA gene is organized in an operon-like structure with rad50 and mre11 archaeal homologs. This nuclease might thus act in concert with Rad50 and Mre11 proteins in archaeal recombination/repair. To our knowledge, this is the first report of a 5'-3' nuclease potentially associated with Rad50 and Mre11-like proteins that may lead to the processing of double-stranded breaks in 3' single-stranded tails.",1
"Constantinesco, Florence, Forterre, Patrick, Elie, Christiane",2
Merging mitochondria matters: cellular role and molecular machinery of mitochondrial fusion.,0
"Fusion is essential for mitochondrial function in a great variety of eukaryotic cell types. Yeast cells defective in mitohondrial fusion are respiration-deficient, human cells use complementation of fused mitochondria as a defence against the accumulation of oxidative damage during cellular aging and fusion is required to build an intracellular mitochondrial continuum that allows the dissipation of energy in the cell. Moreover, developmental processes such as spermatogenesis in Drosophila require regulated mitochondrial fusion. Some of the molecular mediators of mitochondrial membrane fusion have been identified in recent years. An evolutionarily conserved large GTPase in the outer membrane is essential for mitochondrial fusion, and genetic screens in yeast are revealing an increasing number of additional important genes. Mechanistic studies have provided the first insights into how the problem of faithfully fusing a double membrane-bounded organelle in a coordinated manner is solved.",1
"Westermann, Benedikt",2
The p53 tumour suppressor inhibits glucocorticoid-induced proliferation of erythroid progenitors.,0
"Hypoxia encountered at high altitude, blood loss and erythroleukemia instigate stress erythropoiesis, which involves glucocorticoid-induced proliferation of erythroid progenitors (ebls). The tumour suppressor p53 stimulates hematopoietic cell maturation and antagonizes glucocorticoid receptor (GR) activity in hypoxia, suggesting that it may inhibit stress erythropoiesis. We report that mouse fetal liver ebls that lack p53 proliferate better than wild-type cells in the presence of the GR agonist dexamethasone. An important mediator of GR-induced ebl self-renewal, the c-myb gene, is induced to higher levels in p53(-/-) ebls by dexamethasone. The stress response to anemia is faster in the spleens of p53(-/-) mice, as shown by the higher levels of colony forming units erythroids and the increase in the CD34/c-kit double positive population. Our results show that p53 antagonizes GR-mediated ebl expansion and demonstrate for the first time that p53-GR cross-talk is important in a physiological process in vivo: stress erythropoiesis.",1
"Ganguli, Gitali, Back, Jonathan, Sengupta, Sagar, Wasylyk, Bohdan",2
Drosophila tracheal system formation involves FGF-dependent cell extensions contacting bridge-cells.,0
"Development of the ectodermally derived Drosophila tracheal system is based on branch outgrowth and fusion that interconnect metamerically arranged tracheal subunits into a highly stereotyped three-dimensional tubular structure. Recent studies have revealed that this process involves a specialized cell type of mesodermal origin, termed bridge-cell. Single bridge-cells are located between adjacent tracheal subunits and serve as guiding posts for the outgrowing dorsal trunk branches. We show that bridge-cell-approaching tracheal cells form filopodia-like cell extensions, which attach to the bridge-cell surface and are essential for the tracheal subunit interconnection. The results of both dominant-negative and gain-of-function experiments suggest that the formation of cell extensions require Cdc42-mediated Drosophila fibroblast growth factor activity.",1
"Wolf, Christian, Gerlach, Nina, Schuh, Reinhard",2
A dual role for the FtsK protein in Escherichia coli chromosome segregation.,0
"FtsK is a multifunctional protein that acts in Escherichia coli cell division and chromosome segregation. Its C-terminal domain is required for XerCD-mediated recombination between dif sites that resolve chromosome dimers formed by recombination between sister chromosomes. We report the construction and analysis of a set of strains carrying different Xer recombination sites in place of dif, some of which recombine in an FtsK-independent manner. The results show that FtsK-independent Xer recombination does not support chromosome dimer resolution. Furthermore, resolution of dimers by the Cre/loxP system also requires FtsK. These findings reveal a second role for FtsK during chromosome dimer resolution in addition to XerCD activation. We propose that FtsK acts to position the dif regions, thus allowing a productive synapse between dif sites.",1
"Capiaux, Hervé, Lesterlin, Christian, Pérals, Koryn, Louarn, Jean Michel, Cornet, François",2
Peptidyl-prolyl isomerases: a new twist to transcription.,0
"Peptidyl-prolyl isomerases (PPIs) catalyse the cis-trans isomerisation of peptide bonds N-terminal to proline residues in polypeptide chains. They have roles in the folding of newly synthesised proteins and in the function of the immune system. In addition, members of the parvulin-like family of PPIs have been implicated in cell cycle control. Their activity is directed by the prior phosphorylation of target proteins in both yeast and mammalian cells. More recent data have illustrated that they may also influence other nuclear events. This review examines PPI activity in the context of eukaryotic transcriptional regulation. The findings are consistent with a two-step model of conformational control, in which the outcome depends on the transcription factor involved.",1
"Shaw, Peter E",2
A role for endogenous glucocorticoids in wound repair.,0
"Exogenous glucocorticoids are known to inhibit wound repair, but the roles and mechanisms of action of endogenous glucocorticoids during the healing process are as yet unknown. Therefore, we wounded mice expressing a DNA-binding-defective mutant version of the glucocorticoid receptor (GR(dim) mice) and also analysed fibroblasts from these animals in vitro. We found a remarkably enlarged granulation tissue with a high fibroblast density in GR(dim) mice. This difference is likely to result from an increased migratory and proliferative capacity of GR(dim) fibroblasts and from elevated expression levels of soluble factors involved in granulation tissue formation in wounds of GR(dim) mice. In spite of the larger granulation tissue seen in early wounds, late wounds appeared normal, most likely due to an enhanced ability of GR(dim) fibroblasts to contract collagen. These results demonstrate an as yet unidentified role of endogenous glucocorticoids in the regulation of wound repair.",1
"Grose, Richard, Werner, Silke, Kessler, Daniela, Tuckermann, Jan, Huggel, Katharina, Durka, Silke, Reichardt, Holger M, Werner, Sabine",2
Spontaneous muscle action potentials fail to develop without fetal-type acetylcholine receptors.,0
"In mammals, two combinations of muscle nicotinic acetylcholine receptors (AChRs) are used: alpha2betagammadelta (gamma-AChR) or alpha2betaepsilondelta (epsilon-AChR). After birth, gamma-AChRs are replaced by epsilon-AChRs (gamma/epsilon-switch). The two receptors have different conductances and open times. During perinatal period, the long open time gamma-AChRs generate random myofiber action potentials from uniquantal miniature end-plate potentials (mEPPs). epsilon-AChRs are suitable for strong adult muscle activities. Since the effect of the gamma/epsilon-switch on neuromuscular development was unclear, despite the many differences in channel characteristics, we carried out this study to generate gamma-subunit-deficient mice. Homozygotes born alive survived for 2 days in a stable condition, and were able to move their forelimbs. Endplate AChRs included epsilon-subunits, and muscle fibers had multiple neuromuscular junctions. Both pre- and postsynapses were abnormal and spontaneous action potentials generated from mEPPs were totally absent. Results suggest a requirement for gamma-AChRs in mediating synaptically-induced action potential activity critical for neuromuscular development.",1
"Takahashi, Masazumi, Kubo, Tai, Mizoguchi, Akira, Carlson, C George, Endo, Katsuaki, Ohnishi, Katsunori",2
Intranuclear degradation of nonsense codon-containing mRNA.,0
"Most vertebrate mRNAs with premature termination codons (PTCs) are specifically recognized and degraded by a process referred to as nonsense-mediated mRNA decay (NMD) while still associated with the nucleus. However, it is still a matter of debate whether PTCs can be identified by intranuclear scanning or only by ribosomes on the cytoplasmic side of the nuclear envelope. Here we show that inhibition of mRNA export by two independent approaches does not affect the downregulation of PTC-containing T-cell receptor beta transcripts in the nuclear fraction of mammalian cells, providing strong evidence for intranuclear NMD. Our results are fully consistent with recently reported evidence for nuclear translation and suggest that an important biological role for nuclear ribosomes is the early elimination of nonsense mRNA during a pioneer round of translation.",1
"Bühler, Marc, Wilkinson, Miles F, Mühlemann, Oliver",2
CARD games in apoptosis and immunity.,0
"A bewildering array of proteins containing the caspase recruitment domain (CARD) have now been identified. Previously, CARD-CARD interactions have been shown to be involved in the assembly of protein complexes that promote caspase processing and activation in the context of apoptosis. However, as the family of CARD-containing proteins has grown, it has become apparent that the majority of these proteins do not recruit caspases or promote caspase activation. Instead, many participate in NF-kappaB signalling pathways associated with innate or adaptive immune responses. Here, we suggest a simplified classification of the CARD proteins based upon their domain structures and discuss the divergent roles of these proteins in the context of host defence.",1
"Bouchier-Hayes, Lisa, Martin, Seamus J",2
Murine spermatogonial stem cells: targeted transgene expression and purification in an active state.,0
"A 400 bp fragment of the spermatogonia-specific Stra8 locus was sufficient to direct gene expression to the germinal stem cells in transgenic mice. A fractionation procedure was devised, based on immunomagnetic sorting of cells in which the promoter drives the expression of a surface functionally neutral protein tag. The purified cells expressed the known molecular markers of spermatogonia Rbm, cyclin A2 and EP-Cam, and the beta1- and alpha6-integrins characteristic of the stem cell fraction. A 700-fold enrichment in stem cells was determined by the ability of the purified fractions to re-establish spermatogenesis in germ cell-depleted recipient testes.",1
"Giuili, Galicia, Tomljenovic, Andrea, Labrecque, Nathalie, Oulad-Abdelghani, Mustapha, Rassoulzadegan, Minoo, Cuzin, François",2
The rhodanese/Cdc25 phosphatase superfamily. Sequence-structure-function relations.,0
"Rhodanese domains are ubiquitous structural modules occurring in the three major evolutionary phyla. They are found as tandem repeats, with the C-terminal domain hosting the properly structured active-site Cys residue, as single domain proteins or in combination with distinct protein domains. An increasing number of reports indicate that rhodanese modules are versatile sulfur carriers that have adapted their function to fulfill the need for reactive sulfane sulfur in distinct metabolic and regulatory pathways. Recent investigations have shown that rhodanese domains are also structurally related to the catalytic subunit of Cdc25 phosphatase enzymes and that the two enzyme families are likely to share a common evolutionary origin. In this review, the rhodanese/Cdc25 phosphatase superfamily is analyzed. Although the identification of their biological substrates has thus far proven elusive, the emerging picture points to a role for the amino-acid composition of the active-site loop in substrate recognition/specificity. Furthermore, the frequently observed association of catalytically inactive rhodanese modules with other protein domains suggests a distinct regulatory role for these inactive domains, possibly in connection with signaling.",1
"Bordo, Domenico, Bork, Peer",2
Molecular cloning and functional characterization of human vesicular glutamate transporter 3.,0
"Glutamate is the major excitatory neurotransmitter in the mammalian CNS. It is loaded into synaptic vesicles by a proton gradient-dependent uptake system and is released by exocytosis upon stimulation. Recently, two mammalian isoforms of a vesicular glutamate transporter, VGLUT1 and VGLUT2, have been identified, the expression of which enables quantal release of glutamate from glutamatergic neurons. Here, we report a novel isoform of a human vesicular glutamate transporter (hVGLUT3). The predicted amino acid sequence of hVGLUT3 shows 72% identity to both hVGLUT1 and hVGLUT2. hVGLUT3 functions as a vesicular glutamate transporter with similar properties to the other isoforms when it is heterologously expressed in a neuroendocrine cell line. Although mammalian VGLUT1 and VGLUT2 exhibit a complementary expression pattern covering all glutamatergic pathways in the CNS, expression of hVGLUT3 overlaps with them in some brain areas, suggesting molecular diversity that may account for physiological heterogeneity in glutamatergic synapses.",1
"Takamori, Shigeo, Malherbe, Pari, Broger, Clemens, Jahn, Reinhard",2
Bacteriophage-encoded cochaperonins can substitute for Escherichia coli's essential GroES protein.,0
"The Escherichia coli chaperonin machine is composed of two members, GroEL and GroES. The GroEL chaperonin can bind 10-15% of E. coli's unfolded proteins in one of its central cavities and help them fold in cooperation with the GroES cochaperonin. Both proteins are absolutely essential for bacterial growth. Several large, lytic bacteriophages, such as T4 and RB49, use the host-encoded GroEL in conjunction with their own bacteriophage-encoded cochaperonin for the correct assembly of their major capsid protein, suggesting a cochaperonin specificity for the in vivo folding of certain substrates. Here, we demonstrate that, when the cochaperonin of either bacteriophage T4 (Gp31) or RB49 (CocO) is expressed in E. coli, the otherwise essential groES gene can be deleted. Thus, it appears that, despite very little sequence identity with groES, the bacteriophage-encoded Gp31 and CocO proteins are capable of replacing GroES in the folding of E. coli's essential, housekeeping proteins.",1
"Keppel, France, Rychner, Monique, Georgopoulos, Costa",2
Plant architecture.,0
"Plant architecture is species specific, indicating that it is under strict genetic control. Although it is also influenced by environmental conditions such as light, temperature, humidity and nutrient status, here we wish to focus only on the endogenous regulatory principles that control plant architecture. We summarise recent progress in the understanding of the basic patterning mechanisms involved in the regulation of leaf arrangement, the genetic regulation of meristem determinacy, i.e. the decision to stop or continue growth, and the control of branching during vegetative and generative development. Finally, we discuss the basis of leaf architecture and the role of cell division and cell growth in morphogenesis.",1
"Reinhardt, Didier, Kuhlemeier, Cris",2
Conversion of omnipotent translation termination factor eRF1 into ciliate-like UGA-only unipotent eRF1.,0
"In eukaryotic ribosomes, termination of translation is triggered by class 1 polypeptide release factor, eRF1. In organisms with a universal code, eRF1 responds to three stop codons, whereas, in ciliates with variant codes, only one or two codon(s) remain(s) as stop signals. By mutagenesis of the Y-C-F minidomain of the N domain, we converted an omnipotent human eRF1 recognizing all three stop codons into a unipotent 'ciliate-like' UGA-only eRF1. The conserved Cys127 located in the Y-C-F minidomain plays a critical role in stop codon recognition. The UGA-only response has also been achieved by concomitant substitutions of four other amino acids located at the Y-C-F and NIKS minidomains of eRF1. We suggest that for eRF1 the stop codon decoding is of a non-linear (non-protein-anticodon) type and explores a combination of positive and negative determinants. We assume that stop codon recognition is profoundly different by eukaryotic and prokaryotic class 1 RFs.",1
"Seit-Nebi, Alim, Frolova, Ludmila, Kisselev, Lev",2
Factors affecting the direct targeting of murine leukemia virus vectors containing peptide ligands in the envelope protein.,0
"To develop a reliable strategy for cell-specific delivery of retroviral vectors, we genetically modified the envelope (Env) protein of the ecotropic Moloney murine leukemia virus. We found a site in the variable region A, where the insertion of ligands, epidermal growth factor (EGF) and stromal-derived factor-1 alpha (SDF-1 alpha), was possible without abolishing virion incorporation of the Env protein and its ecotropic entry function. The vector containing the EGF-Env did not show the EGF receptor-dependent transduction. The vector containing the SDF-1 alpha-Env, however, specifically transduced human cells expressing CXCR4, the receptor for SDF-1 alpha, at titers of 10(3)-10(4) c.f.u./ml. Further experiments showed that the CXCR4-dependent transduction was based on the specific interaction between the SDF-1 alpha moiety of the SDF-1 alpha-Env and CXCR4 and was independent of the ecotropic entry function. The direct targeting of the retroviral vector may be possible if the proper chimeric Env structure and the appropriate ligand-receptor system are employed.",1
"Katane, Masumi, Takao, Eiko, Kubo, Yoshinao, Fujita, Rika, Amanuma, Hiroshi",2
Reverse genetics in the mosquito Anopheles gambiae: targeted disruption of the Defensin gene.,0
"Anopheles gambiae, the major vector of human malaria parasite, is an important insect model to study vector-parasite interactions. Here, we developed a simple in vivo double-stranded RNA (dsRNA) knockout approach to determine the function of the mosquito antimicrobial peptide gene Defensin. We injected dsRNA into adults and observed efficient and reproducible silencing of Defensin. Analysis of the knockdown phenotype revealed that this peptide is required for the mosquito antimicrobial defense against Gram-positive bacteria. In contrast, in mosquitoes infected by Plasmodium berghei, no loss of mosquito viability and no significant effect on the development and morphology of the parasite midgut stages were observed in the absence of Defensin. We conclude that this peptide is not a major antiparasitic factor in A. gambiae in vivo. Our results open new perspectives for the study of mosquito gene function in vivo and provide a basis for genome-scale systematic functional screens by targeted gene silencing.",1
"Blandin, Stéphanie, Moita, Luis F, Köcher, Thomas, Wilm, Matthias, Kafatos, Fotis C, Levashina, Elena A",2
The ins and outs of APC and beta-catenin nuclear transport.,0
"Adenomatous polyposis coli (APC) and beta-catenin, two key interacting proteins implicated in development and cancer, were recently found to traffic into and out of the nucleus in response to internal and external signals. The two proteins can enter and exit the nucleus independently, a discovery that has prompted debate about the previously proposed role of APC as a beta-catenin chaperone. Here, we review the regulation of APC and beta-catenin subcellular localization, in particular in cancer cells. We speculate that, in non-stimulated cells, APC actively exports beta-catenin from the nucleus to the cytoplasm where its levels are regulated by degradation; and, conversely, that, in cancer cells or those stimulated by Wnt signaling, beta-catenin degradation is inhibited and the accruing protein is capable of moving between the nucleus and cytoplasm independently of APC. Models that link APC and beta-catenin transport to function are discussed.",1
"Henderson, Beric R, Fagotto, Francois",2
Inter-chromosomal recombination of Mll and Af9 genes mediated by cre-loxP in mouse development.,0
"Chromosomal translocations are crucial events in the aetiology of many leukaemias, lymphomas and sarcomas, resulting in enforced oncogene expression or the creation of novel fusion genes. The study of the biological outcome of such events ideally requires recapitulation of the tissue specificity and timing of the chromosomal translocation itself. We have used the Cre-loxP system of phage P1 to induce de novo Mll-Af9 chromosomal recombination during mouse development. loxP sites were introduced into the Mll and Af9 genes on chromosomes 9 and 4, respectively, and mice carrying these alleles were crossed with mice expressing Cre recombinase. A resulting Mll-Af9 fusion gene was detected whose transcription and splicing were verified. Thus, programmed interchromosomal recombination can be achieved in mice. This approach should allow the design of mouse models of tumorigenesis with greater biological relevance than those available at present.",1
"Collins, E C, Pannell, R, Simpson, E M, Forster, A, Rabbitts, T H",2
The 3.7 A projection map of the glycerol facilitator GlpF: a variant of the aquaporin tetramer.,0
"GlpF, the glycerol facilitator protein of Escherichia coli, is an archetypal member of the aquaporin superfamily. To assess its structure, recombinant histidine-tagged protein was overexpressed, solubilized in octylglucoside and purified to homogeneity. Negative stain electron microscopy of solubilized GlpF protein revealed a tetrameric structure of approximately 80 A side length. Scanning transmission electron microscopy yielded a mass of 170 kDa, corroborating the tetrameric nature of GlpF. Reconstitution of GlpF in the presence of lipids produced highly ordered two-dimensional crystals, which diffracted electrons to 3.6 A resolution. Cryoelectron microscopy provided a 3.7 A projection map exhibiting a unit cell comprised of two tetramers. In projection, GlpF is similar to AQP1, the erythrocyte water channel. However, the major density minimum within each monomer is distinctly larger in GlpF than in AQP1.",1
"Braun, T, Philippsen, A, Wirtz, S, Borgnia, M J, Agre, P, Kühlbrandt, W, Engel, A, Stahlberg, H",2
Fate of mat1 DNA strands during mating-type switching in fission yeast.,0
"The mating-type switching of the fission yeast, Schizosaccharomyces pombe, is highly regulated. Two consecutive asymmetric divisions are required to produce one mating-type switched cell among the four progeny. Using DNA density-gradient centrifugation we demonstrate that one-fourth of the mat1 DNA is not replicated by the conventional semi-conservative mode, but instead both DNA strands are synthesized de novo. Our data are consistent with a gene conversion event, initiated by a site- and strand-specific DNA break (SSB). We further demonstrate that the virgin switched mat1-containing chromatid no longer contained the nick, while it is reintroduced during the lagging strand synthesis of the mat1 locus on the sister chromatid. This finding establishes at the molecular level a firm experimental link between the phenotype and genotype in the process of asymmetric mating-type switching during mitotic divisions.",1
"Arcangioli, B",2
RNA degradation buffers asymmetries of transcription in Arabidopsis mitochondria.,0
"To understand better the relative contributions of transcriptional and post-transcriptional processes towards the regulation of gene expression in plant mitochondria, we compared the steady state levels of RNAs with the respective transcriptional activities. All of the protein and rRNA coding genes of the Arabidopsis mitochondrial genome and several orfs were analyzed by run-on and northern experiments. rRNAs constitute the bulk of the steady state RNA in Arabidopsis mitochondria, but are (different from maize mitochondria) not equally prominent among the run-on transcripts. Their relatively low rate of active transcription is apparently compensated by their high stability. Run-on transcription values differ significantly between genes coding for different subunits of the same protein complex. The steady state RNA levels are considerably more homogeneous, indicating that high variations of transcription rates are counterbalanced by post-transcriptional processes. The relative amounts of the steady state transcripts for the different subunits in a given protein complex reflect the relative stoichiometries of the protein subunits much more closely than the respective transcriptional activities. Post-transcriptional RNA processing and stability thus contribute significantly to the regulation of gene expression in Arabidopsis mitochondria.",1
"Giegé, P, Hoffmann, M, Binder, S, Brennicke, A",2
Membrane raft microdomains mediate lateral assemblies required for HIV-1 infection.,0
"HIV-1 infection triggers lateral membrane diffusion following interaction of the viral envelope with cell surface receptors. We show that these membrane changes are necessary for infection, as initial gp120-CD4 engagement leads to redistribution and clustering of membrane microdomains, enabling subsequent interaction of this complex with HIV-1 co-receptors. Disruption of cell membrane rafts by cholesterol depletion before viral exposure inhibits entry by both X4 and R5 strains of HIV-1, although viral replication in infected cells is unaffected by this treatment. This inhibitory effect is fully reversed by cholesterol replenishment of the cell membrane. These results indicate a general mechanism for HIV-1 envelope glycoprotein-mediated fusion by reorganization of membrane microdomains in the target cell, and offer new strategies for preventing HIV-1 infection.",1
"Mañes, S, del Real, G, Lacalle, R A, Lucas, P, Gómez-Moutón, C, Sánchez-Palomino, S, Delgado, R, Alcamí, J, Mira, E, Martínez-A, C",2
The DNA segregation mechanism of Epstein-Barr virus nuclear antigen 1.,0
"Latent Epstein-Barr virus (EBV) genomes are maintained in human cells as low copy number episomes that are thought to be partitioned by attachment to the cellular mitotic chromosomes through the viral EBNA1 protein. We have identified a human protein, EBP2, which interacts with the EBNA1 sequences that govern EBV partitioning. Here we show that, in mitosis, EBP2 localizes to the condensed cellular chromosomes producing a staining pattern that is indistinguishable from that of EBNA1. The localization of EBNA1 proteins with mutations in the EBP2 binding region was also examined. An EBNA1 mutant (delta325-376) disrupted for EBP2 binding and segregation function was nuclear but failed to attach to the cellular chromosomes in mitosis. Our results indicate that amino acids 325-376 mediate the binding of EBNA1 to mitotic chromosomes and strongly suggest that EBNA1 mediates EBV segregation by attaching to EBP2 on the cellular mitotic chromosomes.",1
"Wu, H, Ceccarelli, D F, Frappier, L",2
Inducible chromosomal translocation of AML1 and ETO genes through Cre/loxP-mediated recombination in the mouse.,0
"Transgenic mice have been used to explore the role of chromosomal translocations in the genesis of tumors. But none of these efforts has actually involved induction of a translocation in vivo. Here we report the use of Cre recombinase to replicate in vivo the t(8;21) translocation found in human acute myeloid leukemia (AML). As in the human tumors, the murine translocation fuses the genes AML1 and ETO. We used homologous recombination to place loxP sites at loci that were syntenic with the break points for the human translocation. Cre activity was provided in mice by a transgene under the control of the Nestin promoter, or in cultured B cells by infecting with a retroviral vector encoding Cre. In both instances, Cre activity mediated interchromosomal translocations that fused the AML1 and ETO genes. Thus, reciprocal chromosomal translocations that closely resemble rearrangements found in human cancers can be achieved in mice.",1
"Buchholz, F, Refaeli, Y, Trumpp, A, Bishop, J M",2
Synergy between estrogen receptor alpha activation functions AF1 and AF2 mediated by transcription intermediary factor TIF2.,0
"The activation function AF2 in the ligand-binding domain of estrogen receptors ER alpha and ER beta signals through the recruitment of nuclear receptor coactivators. Recent evidence indicates that coactivators, such as the transcription intermediary factor TIF2, also bind to and transactivate the N-terminal AF1 function of the two ERs. We have generated TIF2 mutant proteins that are deficient in either AF1 or AF2 interaction and use these mutants to investigate the relative contribution of both AFs to TIF2 recruitment and transactivation. We observe that TIF2 is capable of interacting simultaneously with both the isolated N- and C-terminus of ER alpha in transfected mammalian cells and in vitro, indicating that TIF2 can bridge both receptor domains. The concomitant interaction of TIF2 with both AFs results in synergistic activation of transcription. Thus, synergy between ER alpha AF1 and AF2 is a result of the cooperative recruitment of TIF2 and/or other members of the p160 coactivator family.",1
"Benecke, A, Chambon, P, Gronemeyer, H",2
Regulation of intracellular dynamics of Smad4 by its leucine-rich nuclear export signal.,0
"Smad family proteins play a pivotal role in transmitting the transforming growth factor-beta (TGF-beta) superfamily signals from the cell surface to the nucleus. In response to ligand stimulation, Smad4 forms a complex with respective receptor-specific Smads, and the complex translocates into the nucleus and regulates gene expression. Thus, the nuclear entry of the Smad complex is one of the key steps in signal transduction. However, little is known about regulatory mechanisms for nucleocytoplasmic transport of Smads. Here we report identification of a functional, leucine-rich nuclear export signal (NES) in Smad4, which regulates subcellular distribution of Smad4. We then show evidence suggesting that the NES-dependent cytoplasmic localization of Smad4 is important for ensuring optimal TGF-beta responsivenesses in transcriptional activation. Moreover, we show that the NES of Smad4 is specifically inactivated by the stimulus-dependent hetero-oligomerization with receptor-specific Smads during the TGF-beta-induced nuclear translocation of Smad4. Taken together, these results suggest an important regulatory role of the NES of Smad4 in TGF-beta signaling.",1
"Watanabe, M, Masuyama, N, Fukuda, M, Nishida, E",2
Mini- and microsatellite expansions: the recombination connection.,0
"It is widely accepted that the large trinucleotide repeat expansions observed in many neurological diseases occur during replication. However, genetic recombination has emerged as a major source of instability for tandem repeats, including minisatellites, and recent studies raise the possibility that it may also be responsible for trinucleotide repeat expansions. We will review data connecting tandem repeat rearrangements and recombination in humans and in eukaryotic model organisms, and discuss the possible role of recombination in trinucleotide repeat expansions in human neurological disorders.",1
"Richard, G F, Pâques, F",2
"TIF-IA, the factor mediating growth-dependent control of ribosomal RNA synthesis, is the mammalian homolog of yeast Rrn3p.",0
"Cells carefully modulate the rate of rRNA transcription in order to prevent an overinvestment in ribosome synthesis under less favorable nutritional conditions. In mammals, growth-dependent regulation of RNA polymerase I (Pol I) transcription is mediated by TIF-IA, an essential initiation factor that is active in extracts from growing but not starved or cycloheximide-treated mammalian cells. Here we report the molecular cloning and functional characterization of recombinant TIF-IA, which turns out to be the mammalian homolog of the yeast factor Rrn3p. We demonstrate that TIF-IA interacts with Pol I in the absence of template DNA, augments Pol I transcription in vivo and rescues transcription in extracts from growth-arrested cells in vitro.",1
"Bodem, J, Dobreva, G, Hoffmann-Rohrer, U, Iben, S, Zentgraf, H, Delius, H, Vingron, M, Grummt, I",2
Decoding apparatus for eukaryotic selenocysteine insertion.,0
"Decoding UGA as selenocysteine requires a unique tRNA, a specialized elongation factor, and specific secondary structures in the mRNA, termed SECIS elements. Eukaryotic SECIS elements are found in the 3' untranslated region of selenoprotein mRNAs while those in prokaryotes occur immediately downstream of UGA. Consequently, a single eukaryotic SECIS element can serve multiple UGA codons, whereas prokaryotic SECIS elements only function for the adjacent UGA, suggesting distinct mechanisms for recoding in the two kingdoms. We have identified and characterized the first eukaryotic selenocysteyl-tRNA-specific elongation factor. This factor forms a complex with mammalian SECIS binding protein 2, and these two components function together in selenocysteine incorporation in mammalian cells. Expression of the two functional domains of the bacterial elongation factor-SECIS binding protein as two separate proteins in eukaryotes suggests a mechanism for rapid exchange of charged for uncharged selenocysteyl-tRNA-elongation factor complex, allowing a single SECIS element to serve multiple UGA codons.",1
"Tujebajeva, R M, Copeland, P R, Xu, X M, Carlson, B A, Harney, J W, Driscoll, D M, Hatfield, D L, Berry, M J",2
Whole-genome analysis reveals a strong positional bias of conserved dMyc-dependent E-boxes.,0
"Myc is a transcription factor with diverse biological effects ranging from the control of cellular proliferation and growth to the induction of apoptosis. Here we present a comprehensive analysis of the transcriptional targets of the sole Myc ortholog in Drosophila melanogaster, dMyc. We show that the genes that are down-regulated in response to dmyc inhibition are largely identical to those that are up-regulated after dMyc overexpression and that many of them play a role in growth control. The promoter regions of these targets are characterized by the presence of the E-box sequence CACGTG, a known dMyc binding site. Surprisingly, a large subgroup of (functionally related) dMyc targets contains a single E-box located within the first 100 nucleotides after the transcription start site. The relevance of this E-box and its position was confirmed by a mutational analysis of a selected dMyc target and by the observation of its evolutionary conservation in a different Drosophila species, Drosophila pseudoobscura. These observations raise the possibility that a subset of Myc targets share a distinct regulatory mechanism.",1
"Hulf, Toby, Bellosta, Paola, Furrer, Michael, Steiger, Dominik, Svensson, David, Barbour, Andrew, Gallant, Peter",2
"Targeted disruption of Tgif, the mouse ortholog of a human holoprosencephaly gene, does not result in holoprosencephaly in mice.",0
"5'-TG-3'-interacting factor or transforming growth factor beta (TGF-beta)-induced factor (TGIF) belongs to a family of evolutionarily conserved proteins that are characterized by an atypical three-amino-acid loop extension homeodomain. In vitro studies have implicated TGIF as a transcriptional repressor and corepressor in retinoid and TGF-beta signaling pathways that regulate several important biological processes. Heterozygous nonsense and missense mutations of the human TGIF gene have been associated with holoprosencephaly, the most common congenital malformation of the forebrain. In mice, Tgif mRNA is expressed ubiquitously in the ventricular neuroepithelium at embryonic day 10.5 (E10.5) but displays a medial to lateral gradient in the developing cerebral cortex at E12.5. The expression quickly declines by E14.5. The spatiotemporal expression profile of Tgif is consistent with its involvement in midline forebrain development. To better understand the function of Tgif in forebrain patterning and proliferation in vivo, we generated mice lacking Tgif by targeted deletion of exons 2 and 3, which encode 98% of the amino acids. Tgif(-)(/)(-) mice had no detectable Tgif protein by Western blotting. Surprisingly, however, these mice were viable and fertile. In addition, there were no discernible derangements in any of the major organ systems, including the forebrain. Overall our results point to a possible functional redundancy of Tgif, potentially provided by the closely related Tgif2.",1
"Shen, Jun, Walsh, Christopher A",2
Interaction of paxillin with poly(A)-binding protein 1 and its role in focal adhesion turnover and cell migration.,0
"We have previously identified poly(A)-binding protein 1 (PABP1) as a ligand for paxillin and shown that the paxillin-PABP1 complex undergoes nucleocytoplasmic shuttling. By targeting the paxillin-binding subdomain sequences in PABP1, we have generated mutants of PABP1 that do not bind to cellular paxillin. Here we report that paxillin association is necessary for efficient nuclear export of PABP1 and that RNA interference of paxillin drives the nuclear accumulation of PABP1. Furthermore, ablation of paxillin-PABP1 association impeded a number of indices of cell motility including spreading on fibronectin, cell migration on two-dimensional matrices, and transmigration in Boyden chambers. These data indicate that PABP1 must associate with paxillin in order to be efficiently transported from the nucleus to the cytoplasm and that this event is necessary for cells to remodel their focal adhesions during cell migration.",1
"Woods, Alison J, Kantidakis, Theodoros, Sabe, Hisataka, Critchley, David R, Norman, Jim C",2
The human stress-activated protein kin17 belongs to the multiprotein DNA replication complex and associates in vivo with mammalian replication origins.,0
"The human stress-activated protein kin17 accumulates in the nuclei of proliferating cells with predominant colocalization with sites of active DNA replication. The distribution of kin17 protein is in equilibrium between chromatin-DNA and the nuclear matrix. An increased association with nonchromatin nuclear structure is observed in S-phase cells. We demonstrated here that kin17 protein strongly associates in vivo with DNA fragments containing replication origins in both human HeLa and monkey CV-1 cells. This association was 10-fold higher than that observed with nonorigin control DNA fragments in exponentially growing cells. In addition, the association of kin17 protein to DNA fragments containing replication origins was also analyzed as a function of the cell cycle. High binding of kin17 protein was found at the G(1)/S border and throughout the S phase and was negligible in both G(0) and M phases. Specific monoclonal antibodies against kin17 protein induced a threefold inhibition of in vitro DNA replication of a plasmid containing a minimal replication origin that could be partially restored by the addition of recombinant kin17 protein. Immunoelectron microscopy confirmed the colocalization of kin17 protein with replication proteins like RPA, PCNA, and DNA polymerase alpha. A two-step chromatographic fractionation of nuclear extracts from HeLa cells revealed that kin17 protein localized in vivo in distinct protein complexes of high molecular weight. We found that kin17 protein purified within an approximately 600-kDa protein complex able to support in vitro DNA replication by means of two different biochemical methods designed to isolate replication complexes. In addition, the reduced in vitro DNA replication activity of the multiprotein replication complex after immunodepletion for kin17 protein highlighted for a direct role in DNA replication at the origins.",1
"Miccoli, Laurent, Frouin, Isabelle, Novac, Olivia, Di Paola, Domenic, Harper, Francis, Zannis-Hadjopoulos, Maria, Maga, Giovanni, Biard, Denis S F, Angulo, Jaime F",2
Dok-R mediates attenuation of epidermal growth factor-dependent mitogen-activated protein kinase and Akt activation through processive recruitment of c-Src and Csk.,0
"Dok-R has previously been shown to associate with the epidermal growth factor receptor (EGFR) and become tyrosine phosphorylated in response to EGF stimulation. The recruitment of Dok-R to the EGFR, which is mediated through its phosphotyrosine binding (PTB) domain, results in attenuation of mitogen-activated protein kinase (MAPK) activation. Dok-R's ability to attenuate EGF-driven MAPK activation is independent of its ability to recruit rasGAP, a known attenuator of MAPK activity, suggesting an alternate Dok-R-mediated pathway. Herein, we have determined the structural determinants within Dok-R that are required for its ability to attenuate EGF signaling and to associate with c-Src and with the Src family kinase (SFK)-inhibitory kinase, Csk. We demonstrate that Dok-R associates constitutively with c-Src through an SH3-dependent interaction and that this association is essential to Dok-R's ability to attenuate c-Src activity and diminish MAPK and Akt/PKB activity. We further illustrate that EGF-dependent phosphorylation of Dok-R requires SFK activity and, more specifically, that SFK-dependent phosphorylation of tyrosine 402 on Dok-R facilitates the inducible recruitment of Csk. We propose that recruitment of Csk to Dok-R serves to bring Csk to c-Src and down-regulate its activity, resulting in a concomitant attenuation of MAPK and Akt/PKB activity. Furthermore, we demonstrate that Dok-R can abrogate c-Src's ability to protect the breast cancer cell line SKBR3 from anoikis and that an association with c-Src and Csk is required for this activity. Collectively these results demonstrate that Dok-R acts as an EGFR-recruited scaffolding molecule that processively assembles c-Src and Csk to attenuate signaling from the EGFR.",1
"Van Slyke, Paul, Coll, Mariano Loza, Master, Zubin, Kim, Harold, Filmus, Jorge, Dumont, Daniel J",2
Direct p53 transcriptional repression: in vivo analysis of CCAAT-containing G2/M promoters.,0
"In response to DNA damage, p53 activates G(1)/S blocking and apoptotic genes through sequence-specific binding. p53 also represses genes with no target site, such as those for Cdc2 and cyclin B, key regulators of the G(2)/M transition. Like most G(2)/M promoters, they rely on multiple CCAAT boxes activated by NF-Y, whose binding to DNA is temporally regulated during the cell cycle. NF-Y associates with p53 in vitro and in vivo through the alphaC helix of NF-YC (a subunit of NF-Y) and a region close to the tetramerization domain of p53. Chromatin immunoprecipitation experiments indicated that p53 is associated with cyclin B2, CDC25C, and Cdc2 promoters in vivo before and after DNA damage, requiring DNA-bound NF-Y. Following DNA damage, p53 is rapidly acetylated at K320 and K373 to K382, histones are deacetylated, and the release of PCAF and p300 correlates with the recruitment of histone deacetylases (HDACs)-HDAC1 before HDAC4 and HDAC5-and promoter repression. HDAC recruitment requires intact NF-Y binding sites. In transfection assays, PCAF represses cyclin B2, and a nonacetylated p53 mutant shows a complete loss of repression potential, despite its abilities to bind NF-Y and to be recruited on G(2)/M promoters. These data (i) detail a strategy of direct p53 repression through associations with multiple NF-Y trimers that is independent of sequence-specific binding of p53 and that requires C-terminal acetylation, (ii) suggest that p53 is a DNA damage sentinel of the G(2)/M transition, and (iii) delineate a new role for PCAF in cell cycle control.",1
"Imbriano, Carol, Gurtner, Aymone, Cocchiarella, Fabienne, Di Agostino, Silvia, Basile, Valentina, Gostissa, Monica, Dobbelstein, Matthias, Del Sal, Giannino, Piaggio, Giulia, Mantovani, Roberto",2
"Inhibition of human Chk1 causes increased initiation of DNA replication, phosphorylation of ATR targets, and DNA breakage.",0
"Human checkpoint kinase 1 (Chk1) is an essential kinase required to preserve genome stability. Here, we show that Chk1 inhibition by two distinct drugs, UCN-01 and CEP-3891, or by Chk1 small interfering RNA (siRNA) leads to phosphorylation of ATR targets. Chk1-inhibition triggered rapid, pan-nuclear phosphorylation of histone H2AX, p53, Smc1, replication protein A, and Chk1 itself in human S-phase cells. These phosphorylations were inhibited by ATR siRNA and caffeine, but they occurred independently of ATM. Chk1 inhibition also caused an increased initiation of DNA replication, which was accompanied by increased amounts of nonextractable RPA protein, formation of single-stranded DNA, and induction of DNA strand breaks. Moreover, these responses were prevented by siRNA-mediated downregulation of Cdk2 or the replication initiation protein Cdc45, or by addition of the CDK inhibitor roscovitine. We propose that Chk1 is required during normal S phase to avoid aberrantly increased initiation of DNA replication, thereby protecting against DNA breakage. These results may help explain why Chk1 is an essential kinase and should be taken into account when drugs to inhibit this kinase are considered for use in cancer treatment.",1
"Syljuåsen, Randi G, Sørensen, Claus Storgaard, Hansen, Lasse Tengbjerg, Fugger, Kasper, Lundin, Cecilia, Johansson, Fredrik, Helleday, Thomas, Sehested, Maxwell, Lukas, Jiri, Bartek, Jiri",2
Tyrosine phosphorylation regulates maturation of receptor tyrosine kinases.,0
"Constitutive activation of receptor tyrosine kinases (RTKs) is a frequent event in human cancer cells. Activating mutations in Fms-like tyrosine kinase 3 (FLT-3), notably, internal tandem duplications in the juxtamembrane domain (FLT-3 ITD), have been causally linked to acute myeloid leukemia. As we describe here, FLT-3 ITD exists predominantly in an immature, underglycosylated 130-kDa form, whereas wild-type FLT-3 is expressed predominantly as a mature, complex glycosylated 150-kDa molecule. Endogenous FLT-3 ITD, but little wild-type FLT-3, is detectable in the endoplasmic reticulum (ER) compartment. Conversely, cell surface expression of FLT-3 ITD is less efficient than that of wild-type FLT-3. Inhibition of FLT-3 ITD kinase by small molecules, inactivating point mutations, or coexpression with the protein-tyrosine phosphatases (PTPs) SHP-1, PTP1B, and PTP-PEST but not RPTPalpha promotes complex glycosylation and surface localization. However, PTP coexpression has no effect on the maturation of a surface glycoprotein of vesicular stomatitis virus. The maturation of wild-type FLT-3 is impaired by general PTP inhibition or by suppression of endogenous PTP1B. Enhanced complex formation of FLT-3 ITD with the ER-resident chaperone calnexin indicates that its retention in the ER is related to inefficient folding. The regulation of RTK maturation by tyrosine phosphorylation was observed with other RTKs as well, defines a possible role for ER-resident PTPs, and may be related to the altered signaling quality of constitutively active, transforming RTK mutants.",1
"Schmidt-Arras, Dirk-E, Böhmer, Annette, Markova, Boyka, Choudhary, Chunaram, Serve, Hubert, Böhmer, Frank-D",2
Caspase-3-dependent beta-cell apoptosis in the initiation of autoimmune diabetes mellitus.,0
"beta-Cell apoptosis is a key event contributing to the pathogenesis of type 1 diabetes mellitus. In addition to apoptosis being the main mechanism by which beta cells are destroyed, beta-cell apoptosis has been implicated in the initiation of type 1 diabetes mellitus through antigen cross-presentation mechanisms that lead to beta-cell-specific T-cell activation. Caspase-3 is the major effector caspase involved in apoptotic pathways. Despite evidence supporting the importance of beta-cell apoptosis in the pathogenesis of type 1 diabetes, the specific role of caspase-3 in this process is unknown. Here, we show that Caspase-3 knockout (Casp3(-/-) mice were protected from developing diabetes in a multiple-low-dose streptozotocin autoimmune diabetes model. Lymphocyte infiltration of the pancreatic islets was completely absent in Casp3(-/-) mice. To determine the role of caspase-3-dependent apoptosis in disease initiation, a defined antigen-T-cell receptor transgenic system, RIP-GP/P14 double-transgenic mice with Casp3 null mutation, was examined. beta-cell antigen-specific T-cell activation and proliferation were observed only in the pancreatic draining lymph node of RIP-GP/P14/Casp3(+/-) mice, but not in mice lacking caspase-3. Together, our findings demonstrate that caspase-3-mediated beta-cell apoptosis is a requisite step for T-cell priming, a key initiating event in type 1 diabetes.",1
"Liadis, Nicole, Murakami, Kiichi, Eweida, Mohamed, Elford, Alisha R, Sheu, Laura, Gaisano, Herbert Y, Hakem, Razqallah, Ohashi, Pamela S, Woo, Minna",2
The distal sequence element of the selenocysteine tRNA gene is a tissue-dependent enhancer essential for mouse embryogenesis.,0
"Appropriate expression of the selenocysteine tRNA (tRNA(Sec)) gene is necessary for the production of an entire family of selenoprotein enzymes. This study investigates the consequence of disrupting an upstream enhancer region of the mouse tRNA(Sec) gene (Trsp) known as the distal sequence element (DSE) by use of a conditional repair gene targeting strategy, in which a 3.2-kb insertion was introduced into the promoter of the gene. In the absence of DSE activity, homozygous mice failed to develop in utero beyond embryonic day 7.5 and had severely decreased levels of selenoprotein transcript. Cre-mediated removal of the selection cassette recovered DSE regulation of Trsp, restoring wild-type levels of tRNA(Sec) expression and allowing the generation of viable rescued mice. Further analysis of targeted heterozygous adult mice revealed that the enhancer activity of the DSE is tissue dependent since, in contrast to liver, heart does not require the DSE for normal expression of Trsp. Similarly, in mouse cell lines we showed that the DSE functions as a cell-line-specific inducible element of tRNA(Sec). Together, our data demonstrate that the DSE is a tissue-dependent regulatory element of tRNA(Sec) expression and that its activity is vital for sufficient tRNA(Sec) production during mouse embryogenesis.",1
"Kelly, Vincent P, Suzuki, Takafumi, Nakajima, Osamu, Arai, Tsuyoshi, Tamai, Yoshitaka, Takahashi, Satoru, Nishimura, Susumu, Yamamoto, Masayuki",2
"Id2 mediates tumor initiation, proliferation, and angiogenesis in Rb mutant mice.",0
"The inhibitor of differentiation Id2 is a target of the retinoblastoma (Rb) protein during mouse embryogenesis. In Rb(+/-) mice, LOH at the wild-type Rb allele initiates pituitary adenocarcinoma, a tumor derived from embryonic melanotropes. Here we identify a critical role for Id2 in initiation, growth, and angiogenesis of pituitary tumors from Rb(+/-) mice. We show that proliferation and differentiation are intimately coupled in Rb(+/-) pituitary cells before tumor initiation. In Id2-null pituitaries, premature activation of basic helix-loop-helix-mediated transcription and expression of the cdk inhibitor p27(Kip1) impairs the proliferation of melanotropes and tumor initiation. Without Id2, Rb(+/-) mice have fewer early tumor lesions and a markedly decreased proliferation rate of the tumor foci. Expression of Id2 by pituitary tumor cells promotes growth and angiogenesis by functioning as a master regulator of vascular endothelial growth factor (VEGF). In human neuroblastoma, the N-Myc-driven expression of Id2 is sufficient and necessary for expression of VEGF. These results establish that aberrant Id2 activity directs initiation and progression of embryonal cancer.",1
"Lasorella, Anna, Rothschild, Gerson, Yokota, Yoshifumi, Russell, Robert G, Iavarone, Antonio",2
Sequence-specific DNA binding by the alphaNAC coactivator is required for potentiation of c-Jun-dependent transcription of the osteocalcin gene.,0
"Since the c-Jun coactivator alphaNAC was initially identified in a differential screen for genes expressed in differentiated osteoblasts, we examined whether the osteocalcin gene, a specific marker of terminal osteoblastic differentiation, could be a natural target for the coactivating function of alphaNAC. We had also previously shown that alphaNAC can specifically bind DNA in vitro, but it remained unclear whether the DNA-binding function of alphaNAC is expressed in vivo or if it is required for coactivation. We have identified an alphaNAC binding site within the murine osteocalcin gene proximal promoter region and demonstrated that recombinant alphaNAC or alphaNAC from ROS17/2.8 nuclear extracts can specifically bind this element. Using transient transfection assays, we have shown that alphaNAC specifically potentiated the c-Jun-dependent transcription of the osteocalcin promoter and that this activity specifically required the DNA-binding domain of alphaNAC. Chromatin immunoprecipitation confirmed that alphaNAC occupies its binding site on the osteocalcin promoter in living osteoblastic cells expressing osteocalcin. Inhibition of the expression of endogenous alphaNAC in osteoblastic cells by use of RNA interference provoked a decrease in osteocalcin gene transcription. Our results show that the osteocalcin gene is a target for the alphaNAC coactivating function, and we propose that alphaNAC is specifically targeted to the osteocalcin promoter through its DNA-binding activity as a means to achieve increased specificity in gene transcription.",1
"Akhouayri, Omar, Quélo, Isabelle, St-Arnaud, René",2
cis-regulatory logic of short-range transcriptional repression in Drosophila melanogaster.,0
"Bioinformatics analysis of transcriptional control is guided by knowledge of the characteristics of cis-regulatory regions or enhancers. Features such as clustering of binding sites and co-occurrence of binding sites have aided enhancer identification, but quantitative predictions of enhancer function are not yet generally feasible. To facilitate the analysis of regulatory sequences in Drosophila melanogaster, we identified quantitative parameters that affect the activity of short-range transcriptional repressors, proteins that play key roles in development. In addition to the previously noted distance dependence, repression is strongly influenced by the stoichiometry, affinity, spacing, and arrangement of activator binding sites. Repression is insensitive to the type of activation domain, suggesting that short-range repression may primarily affect activators at the level of DNA binding. The activity of several short-range, but not long-range, repressors is circumscribed by the same quantitative parameters. This cis-regulatory ""grammar"" may aid the identification of enhancers regulated by short-range repressors and facilitate bioinformatic prediction of the functional output of transcriptional regulatory sequences.",1
"Kulkarni, Meghana M, Arnosti, David N",2
p21-activated kinase 1 regulates microtubule dynamics by phosphorylating tubulin cofactor B.,0
"p21-activated kinase 1 (Pak1) induces cytoskeleton reorganization in part by regulating microtubule dynamics through an elusive mechanism. Using a yeast two-hybrid screen, we identified tubulin cofactor B (TCoB) (a cofactor in the assembly of the alpha/beta-tubulin heterodimers) as an interacting substrate of Pak1. Pak1 directly phosphorylated TCoB in vitro and in vivo on serines 65 and 128 and colocalized with TCoB on newly polymerized microtubules and on centrosomes. TCoB interacted with the GTPase-binding domain of Pak1 and activated Pak1 in vitro and in vivo. In contrast to wild-type TCoB, an S65A, S128A double mutant and knock-down of the endogenous TCoB or Pak1 reduced microtubule polymerization, suggesting that Pak1 phosphorylation is necessary for normal TCoB function. Overexpression of TCoB dramatically increased the number of gamma-tubulin-containing microtubule-organizing centers, a phenotype reminiscent of cells overexpressing Pak1. TCoB was overexpressed and phosphorylated in breast tumors. These findings reveal a novel role for TCoB and Pak1 in regulating microtubule dynamics.",1
"Vadlamudi, Ratna K, Barnes, Christopher J, Rayala, Suresh, Li, Feng, Balasenthil, Seetharaman, Marcus, Stevan, Goodson, Holly V, Sahin, Aysegul A, Kumar, Rakesh",2
Mismatch repair proteins are activators of toxic responses to chromium-DNA damage.,0
"Chromium(VI) is a toxic and carcinogenic metal that causes the formation of DNA phosphate-based adducts. Cr-DNA adducts are genotoxic in human cells, although they do not block replication in vitro. Here, we report that induction of cytotoxicity in Cr(VI)-treated human colon cells and mouse embryonic fibroblasts requires the presence of all major mismatch repair (MMR) proteins. Cr-DNA adducts lost their ability to block replication of Cr-modified plasmids in human colon cells lacking MLH1 protein. The presence of functional mismatch repair caused induction of p53-independent apoptosis associated with activation of caspases 2 and 7. Processing of Cr-DNA damage by mismatch repair resulted in the extensive formation of gamma-H2AX foci in G(2) phase, indicating generation of double-stranded breaks as secondary toxic lesions. Induction of gamma-H2AX foci was observed at 6 to 12 h postexposure, which was followed by activation of apoptosis in the absence of significant G(2) arrest. Our results demonstrate that mismatch repair system triggers toxic responses to Cr-DNA backbone modifications through stress mechanisms that are significantly different from those for other forms of DNA damage. Selection for Cr(VI) resistant, MMR-deficient cells may explain the very high frequency of lung cancers with microsatellite instability among chromate workers.",1
"Peterson-Roth, Elizabeth, Reynolds, Mindy, Quievryn, George, Zhitkovich, Anatoly",2
"SUMO-1 modification of PIASy, an E3 ligase, is necessary for PIASy-dependent activation of Tcf-4.",0
"We have previously shown that modification of Tcf-4, a transcription factor in the Wnt pathway, with SUMO by PIASy, a SUMO E3 ligase, enhances its transcriptional activity. Since PIASy itself was also modified with SUMO-1, we studied the role of sumoylation of PIASy in the regulation of Tcf-4. Lys(35) was found to be a sumoylation site of PIASy. PIASy(K35R), in which Lys(35) was mutated to Arg, did not enhance sumoylation of Tcf-4, although this PIASy mutant did not lose the ligase activity of sumoylation for other proteins. Wild-type PIASy and PIASy(K35R) showed a distinct distribution in the nucleus, although both were colocalized with Tcf-4. Promyelocytic leukemia protein, which is involved in transcriptional regulation, was associated with PIASy(K35R) more frequently than wild-type PIASy in the nucleus. PIASy(K35R) could not stimulate the transcriptional activity of Tcf-4 under the conditions in which wild-type PIASy enhanced it. Conjugation of SUMO-1 to the amino terminus of PIASy(K35R) neither enhanced sumoylation of Tcf-4 nor stimulated the transcriptional activity of Tcf-4. These results suggest that sumoylation of Lys(35) in PIASy determines the nuclear localization of PIASy and that it is necessary for PIASy-dependent sumoylation and transcriptional activation of Tcf-4.",1
"Ihara, Motomasa, Yamamoto, Hideki, Kikuchi, Akira",2
Human RNA polymerase II elongation in slow motion: role of the TFIIF RAP74 alpha1 helix in nucleoside triphosphate-driven translocation.,0
"The role of the RAP74 alpha1 helix of transcription factor IIF (TFIIF) in stimulating elongation by human RNA polymerase II (RNAP II) was examined using millisecond-phase transient-state kinetics. RAP74 deletion mutants RAP74(1-227), which includes an intact alpha1 helix, and RAP74(1-158), in which the alpha1 helix is deleted, were compared. Analysis of TFIIF RAP74-RAP30 complexes carrying the RAP74(1-158) deletion reveals the role of the alpha1 helix because this mutant has indistinguishable activity compared to TFIIF 74(W164A), which carries a critical point mutation in alpha1. We report adequate two-bond kinetic simulations for the reaction in the presence of TFIIF 74(1-227) + TFIIS and TFIIF 74(1-158) + TFIIS. TFIIF 74(1-158) is defective because it fails to promote forward translocation. Deletion of the RAP74 alpha1 helix results in increased occupancy of the backtracking, cleavage, and restart pathways at a stall position, indicating reverse translocation of the elongation complex. During elongation, TFIIF 74(1-158) fails to support detectable nucleoside triphosphate (NTP)-driven translocation from a stall position and is notably defective in supporting bond completion (NTP-driven translocation coupled to pyrophosphate release) during the processive transition between bonds.",1
"Zhang, Chunfen, Zobeck, Katie L, Burton, Zachary F",2
SPBP is a phosphoserine-specific repressor of estrogen receptor alpha.,0
"Multiple signaling pathways stimulate the activity of estrogen receptor alpha (ERalpha) by direct phosphorylation within its N-terminal activation function 1 (AF1). How phosphorylation affects AF1 activity remains poorly understood. We performed a phage display screen for human proteins that are exclusively recruited to the phosphorylated form of AF1 and found the stromelysin-1 platelet-derived growth factor-responsive element-binding protein (SPBP). In a purified system, SPBP bound only the in vitro-phosphorylated form of the ERalpha AF1 or the phosphoserine mimic S118E, and the interaction domain could be mapped to a 42-amino-acid fragment of SPBP. In cells, SPBP preferentially interacted with liganded and phosphorylated ERalpha. Functionally, SPBP behaved as a repressor of activated ERalpha, which extends its previously demonstrated roles as a DNA binding transactivation factor and coactivator of other transcription factors. By targeting the phosphorylated form of AF1, SPBP may contribute to attenuating and fine-tuning ERalpha activity. A functional consequence is that SPBP inhibits the proliferation of ERalpha-dependent but not ERalpha-independent breast cancer cell lines, mirroring a reported negative correlation with the ERalpha status of breast tumors.",1
"Gburcik, Valentina, Bot, Nathalie, Maggiolini, Marcello, Picard, Didier",2
Selective regulation of c-jun gene expression by mitogen-activated protein kinases via the 12-o-tetradecanoylphorbol-13-acetate- responsive element and myocyte enhancer factor 2 binding sites.,0
"To further understand how the mitogen-activated protein kinase (MAPK) signaling pathways regulate AP-1 activity, we have elucidated the physiological role of these cascades in the regulation of c-jun gene expression. c-Jun is a crucial component of AP-1 complexes and has been shown in vitro to be a point of integration of numerous signals that can differentially affect its expression as well as its transcriptional activity. Our strategy was based on the use of (i) genetically modified fibroblasts deficient in components of the MAPK cascades and (ii) pharmacological reagents. The results demonstrate that c-Jun NH(2)-terminal protein kinase (JNK) is essential for a basal level of c-Jun expression and for c-Jun phosphorylation in response to stress. In addition to JNK, p38 MAPK or ERK1/2 and ERK5 are required for mediating UV radiation- or epidermal growth factor (EGF)-induced c-Jun expression, respectively. Further studies indicate that p38 MAPK inhibits the activation of JNK in response to EGF, causing a down-regulation of c-Jun. Overall, these data provide important insights into the mechanisms that ultimately determine the function of c-Jun as a regulator of cell fate.",1
"Kayahara, Midori, Wang, Xin, Tournier, Cathy",2
The pleckstrin homology domain-containing protein CKIP-1 is involved in regulation of cell morphology and the actin cytoskeleton and interaction with actin capping protein.,0
"CKIP-1 is a pleckstrin homology domain-containing protein that interacts with protein kinase CK2. To elucidate the functions of CKIP-1, we generated human osteosarcoma cell lines with tetracycline-regulated expression of Flag-CKIP-1. Flag-CKIP-1 expression resulted in distinct changes in cellular morphology. Therefore, we examined the actin profile by immunofluorescence, quantitative measurement of phalloidin binding, and immunoblot analysis. These studies demonstrate that Flag-CKIP-1 expression resulted in increases in F-actin staining and protein levels of beta-actin. To elucidate the mechanisms behind the observed phenotype, we utilized tandem affinity purification to isolate CKIP-1 interacting proteins. Mass spectrometry analysis led to the identification of the actin capping protein subunits, CPalpha and CPbeta, as novel CKIP-1 interaction partners. Interactions were confirmed by coimmunoprecipitation and by colocalization. Furthermore, we demonstrate that Ser9 of CPalpha is phosphorylated by protein kinase CK2 in vitro, that CPalpha is phosphorylated in vivo, and that treatment with a CK2-specific inhibitor results in a decrease in CPalpha phosphorylation. Finally, we demonstrate that CKIP-1 and CK2 inhibit the activity of actin capping protein at the barbed ends of actin filaments. Overall, our results are consistent with CKIP-1 playing a role in the regulation of the actin cytoskeleton through its interactions with actin capping protein.",1
"Canton, David A, Olsten, Mary Ellen K, Kim, Kyoungtae, Doherty-Kirby, Amanda, Lajoie, Gilles, Cooper, John A, Litchfield, David W",2
A developmental switch in the response of DRG neurons to ETS transcription factor signaling.,0
"Two ETS transcription factors of the Pea3 subfamily are induced in subpopulations of dorsal root ganglion (DRG) sensory and spinal motor neurons by target-derived factors. Their expression controls late aspects of neuronal differentiation such as target invasion and branching. Here, we show that the late onset of ETS gene expression is an essential requirement for normal sensory neuron differentiation. We provide genetic evidence in the mouse that precocious ETS expression in DRG sensory neurons perturbs axonal projections, the acquisition of terminal differentiation markers, and their dependence on neurotrophic support. Together, our findings indicate that DRG sensory neurons exhibit a temporal developmental switch that can be revealed by distinct responses to ETS transcription factor signaling at sequential steps of neuronal maturation.",1
"Hippenmeyer, Simon, Vrieseling, Eline, Sigrist, Markus, Portmann, Thomas, Laengle, Celia, Ladle, David R, Arber, Silvia",2
Hospitalisation for bed rest for women with a triplet pregnancy: an abandoned randomised controlled trial and meta-analysis.,0
"BACKGROUND: This abandoned randomised controlled trial assessed the effects of hospitalisation from 24 to 30 weeks gestation for women with a triplet pregnancy on the risk of preterm birth. METHODS: Women with a triplet pregnancy and no other condition necessitating hospital admission were approached for participation in the study, and randomised to either antenatal hospitalisation (hospitalised group), or to routine antenatal care (control group). The randomisation schedule used variable blocks with stratification by parity, and a researcher not involved with clinical care contacted by telephone to determine treatment allocation by opening the next in a series of consecutively numbered, opaque, sealed envelopes. Primary study outcomes were preterm birth (defined as birth less than 37 weeks gestation) and very preterm birth (defined as birth less than 34 weeks gestation), and the development of maternal pregnancy induced hypertension. The trial was ceased prior to achieving the calculated sample size due to difficulties in recruitment. The results of this randomised controlled trial were then combined with the results of another comparing bed rest in women with a triplet pregnancy. RESULTS: Seven women with a triplet pregnancy were recruited to the trial, with three randomised to the hospitalisation group, and four to the control group. There were no statistically significant differences between the two groups for the primary outcomes birth before 37 weeks (3/3 hospitalisation group versus 4/4 control group; relative risk (RR) not estimable), birth before 34 weeks (3/3 hospitalisation group versus 2/4 control group; RR 2.00 95% Confidence Intervals (CI) 0.75-5.33) and pregnancy induced hypertension (1/3 hospitalisation group versus 1/4 control group; RR 1.33 95%CI 0.13-13.74).When the results of this trial were incorporated into a meta-analysis with the previous randomised controlled trial assessing hospitalisation and bed rest for women with a triplet pregnancy, (total sample size 26 women and 78 infants), there were no statistically significant differences identified between the two groups. CONCLUSION: The results of this trial and meta-analysis suggest no benefit of routine hospitalisation and bed rest for women with a triplet pregnancy to reduce the risk of preterm birth. The adoption or continuation of a policy of routine hospitalisation and bed rest for women with an uncomplicated triplet pregnancy cannot be recommended.",1
"Dodd, Jodie M, Crowther, Caroline A",2
Complementary and alternative medicine utilisation in NHS and private clinic settings: a United Kingdom survey of 400 infertility patients.,0
"Some evidence suggests that complementary and alternative medicine (CAM) has found increased utilisation among patients seeking infertility treatment, although there is little information available to quantify this phenomenon. This is important information as there is marketing for CAM directed to this group and professionals need to be aware of the treatments their patients are receiving. Patients attending for infertility diagnosis and treatment often ask the physician about CAM; this paper seeks to compare the prevalence of CAM use among infertility patients in National Health Service (NHS) and private clinics. This paper provides results of a survey of couples (n = 400) divided equally between NHS and private settings. Our data suggest a high use of CAM particularly among female private patients, although patients appear sceptical of the efficacy of such treatment which is consistent with the literature.",1
"Coulson, Catherine, Jenkins, Julian",2
Postpancreatectomy hemorrhage: diagnosis and treatment: an analysis in 1669 consecutive pancreatic resections.,0
To analyze clinical courses and outcome of postpancreatectomy hemorrhage (PPH) after major pancreatic surgery.,1
"Yekebas, Emre F, Wolfram, Lars, Cataldegirmen, Guellue, Habermann, Christian R, Bogoevski, Dean, Koenig, Alexandra M, Kaifi, Jussuf, Schurr, Paulus G, Bubenheim, Michael, Nolte-Ernsting, Claus, Adam, Gerhard, Izbicki, Jakob R",2
Perioperative mortality for pancreatectomy: a national perspective.,0
To analyze in-hospital mortality after pancreatectomy using a large national database.,1
"McPhee, James T, Hill, Joshua S, Whalen, Giles F, Zayaruzny, Maksim, Litwin, Demetrius E, Sullivan, Mary E, Anderson, Frederick A, Tseng, Jennifer F",2
Activities of daily living and quality of life of elderly patients after elective surgery for gastric and colorectal cancers.,0
To establish reliable standards for surgical application to elderly patients 75 years old or older with gastric or colorectal cancer with special reference to the postoperative recovery of activities of daily living (ADL) and quality of life (QOL).,1
"Amemiya, Takeshi, Oda, Koji, Ando, Masahiko, Kawamura, Takashi, Kitagawa, Yuichi, Okawa, Yayoi, Yasui, Akihiro, Ike, Hideyuki, Shimada, Hiroshi, Kuroiwa, Kojiro, Nimura, Yuji, Fukata, Shinji",2
Impact of graft type on outcome in pediatric liver transplantation: a report From Studies of Pediatric Liver Transplantation (SPLIT).,0
To examine the outcome of technical variant liver transplant techniques relative to whole organ liver transplantation in pediatric liver transplant recipients.,1
"Diamond, Ivan R, Fecteau, Annie, Millis, J Michael, Losanoff, Julian E, Ng, Vicky, Anand, Ravinder, Song, Changhong",2
Type I interferons in the treatment of pancreatic cancer: mechanisms of action and role of related receptors.,0
"We evaluated the role of type I interferons (IFNs) and IFN receptors in the regulation of cell growth in 3 human pancreatic adenocarcinoma cell lines (BxPC-3, MiaPaCa-2, and Panc-1).",1
"Vitale, Giovanni, van Eijck, Casper H J, van Koetsveld Ing, Peter M, Erdmann, Joris I, Speel, Ernst Jan M, van der Wansem Ing, Katy, Mooij, Diana M, Colao, Annamaria, Lombardi, Gaetano, Croze, Ed, Lamberts, Steven W J, Hofland, Leo J",2
Comparison of long-term outcome of laparoscopic and conventional nissen fundoplication: a prospective randomized study with an 11-year follow-up.,0
The aim of this study was to compare the long-term objective and subjective outcomes of laparoscopic and open Nissen fundoplication in a randomized clinical trial with an 11-year follow-up.,1
"Salminen, Paulina T P, Hiekkanen, Heikki I, Rantala, Arto P T, Ovaska, Jari T",2
Hepatic resection for colorectal metastases: value for risk scoring systems?,0
"Predictors of outcome in patients with metastatic colorectal cancer remain inconsistent. We aimed to identify predictors of outcome in these patients, to develop a prognostic scoring system, and to assess the general applicability of the current major risk scoring systems.",1
"Zakaria, Shaheen, Donohue, John H, Que, Florencia G, Farnell, Michael B, Schleck, Cathy D, Ilstrup, Duane M, Nagorney, David M",2
Job stress and poor sleep quality: data from an American sample of full-time workers.,0
"Given the associations between poor quality sleep and health, it is important to consider whether job stressors are related to sleep-related outcomes. Studies from Europe and Japan suggest that these stressors negatively impact sleep, but there are few studies of job stressors and sleep quality that draw upon large representative samples of workers in the USA. Using data collected via telephone interviews from a nationally representative random sample of 1715 American full-time employees, this research considers three dependent variables of past-month poor sleep quality: number of days the respondent had difficulty initiating sleep, number of days of difficulty maintaining sleep, and number of days of non-restorative sleep. Negative binomial regression was used to estimate a count data model of the associations between the frequency of these three types of poor sleep quality and the job stressors of work overload, role conflict, autonomy, and repetitive tasks, while controlling for socio-demographic characteristics. The average American worker reported 5.3 days of difficulty falling asleep, 6.6 days of trouble staying asleep, and 5.0 days of trouble waking up for work in the past month. Across the three types of poor sleep quality, work overload was positively associated with the frequency of poor sleep quality. Role conflict was positively associated with difficulty initiating sleep and non-restorative sleep. Repetitive tasks were associated with more days of difficulty initiating sleep and maintaining sleep. Job autonomy was negatively associated with non-restorative sleep. Given that sleep quality is associated with other health outcomes, future research should continue to explore the associations between job-related stressors, sleep quality, and workers' health status.",1
"Knudsen, Hannah K, Ducharme, Lori J, Roman, Paul M",2
Long-term outcome of children born after a first-trimester measurement of nuchal translucency at the 99th percentile or greater with normal karyotype: a prospective study.,0
This study was undertaken to assess the long-term outcome of children born after a first-trimester measurement of nuchal translucency (NT) at the 99th percentile or greater during routine first-trimester screening in an unselected population.,1
"Senat, Marie-Victoire, Bussières, Laurence, Couderc, Sophie, Roume, Joelle, Rozenberg, Patrick, Bouyer, Jean, Ville, Yves",2
Teachers' ratings of the academic performance of children with epilepsy.,0
"The present study examined how knowledge of a child's seizure condition is related to teachers' assessment of the child's academic ability. Children with epilepsy were divided into two groups based on teachers' awareness of the children's seizure condition (Label). The children's achievement was assessed using the Woodcock Johnson Tests of Achievement-Revised (WJ-R), and the teacher's ratings were obtained from the Child Behavior Checklist Teacher Report Form (TRF) (Source). A 2 (Source) x 2 (Label) mixed-design analysis of covariance (controlling for IQ and how well the teacher knew the child) revealed a significant interaction, F(1,121)=4.22, P=0.04. For the WJ-R there was no effect of Label on Achievement, but on the TRF lower scores were observed for children who were labeled. These results support the hypothesis that some teachers might underestimate the academic abilities of children with epilepsy.",1
"Katzenstein, Jennifer M, Fastenau, Philip S, Dunn, David W, Austin, Joan K",2
Aggression and quantitative MRI measures of caudate in patients with chronic schizophrenia or schizoaffective disorder.,0
"Caudate dysfunction is implicated in schizophrenia. However, little is known about the relationship between aggression and caudate volumes. Forty-nine patients received magnetic resonance imaging scanning in a double-blind treatment study in which aggression was measured. Caudate volumes were computed using a semiautomated method. The authors measured aggression with the Overt Aggression Scale and the Positive and Negative Syndrome Scale. Larger caudate volumes were associated with greater levels of aggression. The relationship between aggression and caudate volumes may be related to the iatrogenic effects of long-term treatment with typical antipsychotic agents or to a direct effect of schizophrenic processes on the caudate.",1
"Hoptman, Matthew J, Volavka, Jan, Czobor, Pál, Gerig, Guido, Chakos, Miranda, Blocher, Joseph, Citrome, Leslie L, Sheitman, Brain, Lindenmayer, Jean-Pierre, Lieberman, Jeffrey A, Bilder, Robert M",2
A compact multiphoton 3D imaging system for recording fast neuronal activity.,0
"We constructed a simple and compact imaging system designed specifically for the recording of fast neuronal activity in a 3D volume. The system uses an Yb:KYW femtosecond laser we designed for use with acousto-optic deflection. An integrated two-axis acousto-optic deflector, driven by digitally synthesized signals, can target locations in three dimensions. Data acquisition and the control of scanning are performed by a LeCroy digital oscilloscope. The total cost of construction was one order of magnitude lower than that of a typical Ti:sapphire system. The entire imaging apparatus, including the laser, fits comfortably onto a small rig for electrophysiology. Despite the low cost and simplicity, the convergence of several new technologies allowed us to achieve the following capabilities: i) full-frame acquisition at video rates suitable for patch clamping; ii) random access in under ten microseconds with dwelling ability in the nominal focal plane; iii) three-dimensional random access with the ability to perform fast volume sweeps at kilohertz rates; and iv) fluorescence lifetime imaging. We demonstrate the ability to record action potentials with high temporal resolution using intracellularly loaded potentiometric dye di-2-ANEPEQ. Our design proffers easy integration with electrophysiology and promises a more widespread adoption of functional two-photon imaging as a tool for the study of neuronal activity. The software and firmware we developed is available for download at http://neurospy.org/ under an open source license.",1
"Vucinić, Dejan, Sejnowski, Terrence J",2
Attenuation of cocaine-seeking by GABA B receptor agonists baclofen and CGP44532 but not the GABA reuptake inhibitor tiagabine in baboons.,0
"The current study evaluated the effects of drugs that increase GABA levels by activation of GABA(B) receptors (baclofen and CGP44532) or by inhibition of GABA reuptake (tiagabine) on the reinstatement of extinguished lever responding produced by priming doses of cocaine in baboons (i.e., cocaine-seeking). Cocaine self-injection was established and maintained under a fixed ratio (FR10) schedule of reinforcement during daily 2h sessions. Lever responding was extinguished by substituting vehicle (saline) for cocaine until the number of self-injections decreased to 10 or less per session for two consecutive sessions (defined as extinction). Once extinction occurred, priming doses of cocaine (0.1-3.2mg/kg, i.v.) were administered during extinction conditions. Administration of priming doses of cocaine significantly increased cocaine-seeking in a dose-dependent manner. Cocaine-seeking produced by priming doses of cocaine were attenuated by pretreatment with baclofen (N=5) or CGP44532 (N=5) but not tiagabine (N=3). The doses of baclofen (0.32 mg/kg), and CGP445532 (0.32 mg/kg) that reduced cocaine-seeking produced by cocaine priming doses did not reinstate cocaine-seeking and did not produce overt effects when administered alone. These data indicate that GABA(B) agonists may reduce relapse to cocaine taking.",1
"Weerts, Elise M, Froestl, Wolfgang, Kaminski, Barbara J, Griffiths, Roland R",2
Enrollment in a brain magnetic resonance study: results from the Women's Health Initiative Memory Study Magnetic Resonance Imaging Study (WHIMS-MRI).,0
The rates of enrollment of volunteers for brain magnetic resonance imaging (MRI) studies vary by demographic and clinical characteristics. We use data from a large MRI study to identify factors associated with differential enrollment and to examine potential biases this may produce in study results.,1
"Jaramillo, Sarah A, Felton, Deborah, Andrews, Leeann, Desiderio, Lisa, Hallarn, Rose K, Jackson, Sharon D, Coker, Laura H, Robinson, Jennifer G, Ockene, Judith K, Espeland, Mark A",2
Clinical spectrum and histopathologic features of chronic hepatitis C infection in children.,0
To define the natural history and outcomes of children infected with hepatitis C virus (HCV) at birth or in early childhood.,1
"Mohan, Parvathi, Colvin, Camilla, Glymph, Chevelle, Chandra, Roma R, Kleiner, David E, Patel, Kantilal M, Luban, Naomi L C, Alter, Harvey J",2
Nucleotide receptor signaling in murine macrophages is linked to reactive oxygen species generation.,0
"Macrophage activation is critical in the innate immune response and can be regulated by the nucleotide receptor P2X7. In this regard, P2X7 signaling is not well understood but has been implicated in controlling reactive oxygen species (ROS) generation by various leukocytes. Although ROS can contribute to microbial killing, the role of ROS in nucleotide-mediated cell signaling is unclear. In this study, we report that the P2X7 agonists ATP and 3'-O-(4-benzoyl) benzoic ATP (BzATP) stimulate ROS production by RAW 264.7 murine macrophages. These effects are potentiated in lipopolysaccharide-primed cells, demonstrating an important interaction between extracellular nucleotides and microbial products in ROS generation. In terms of nucleotide receptor specificity, RAW 264.7 macrophages that are deficient in P2X7 are greatly reduced in their capacity to generate ROS in response to BzATP treatment (both with and without LPS priming), thus supporting a role for P2X7 in this process. Because MAP kinase activation is key for nucleotide regulation of macrophage function, we also tested the hypothesis that P2X7-mediated MAP kinase activation is dependent on ROS production. We observed that BzATP stimulates MAP kinase (ERK1/ERK2, p38, and JNK1/JNK2) phosphorylation and that the antioxidants N-acetylcysteine and ascorbic acid strongly attenuate BzATP-mediated JNK1/JNK2 and p38 phosphorylation but only slightly reduce BzATP-induced ERK1/ERK2 phosphorylation. These studies reveal that P2X7 can contribute to macrophage ROS production, that this effect is potentiated upon lipopolysaccharide exposure, and that ROS are important participants in the extracellular nucleotide-mediated activation of several MAP kinase systems.",1
"Pfeiffer, Zachary A, Guerra, Alma N, Hill, Lindsay M, Gavala, Monica L, Prabhu, Usha, Aga, Mini, Hall, David J, Bertics, Paul J",2
There's no place like (a) home: ontological security among persons with serious mental illness in the United States.,0
"As the homelessness 'crisis' in the United States enters a third decade, few are as adversely affected as persons with serious mental illness. Despite recent evidence favoring a 'housing first' approach, the dominant 'treatment first' approach persists in which individuals must climb a ladder of program requirements before becoming eligible for an apartment of their own. Drawing upon the concept of 'ontological security', this qualitative study examines the subjective meaning of 'home' among 39 persons who were part of a unique urban experiment that provided New York City's homeless mentally ill adults with immediate access to independent housing in the late 1990s. The study design involved purposively sampling from the experimental (housing first) group (N=21) and the control (treatment first) group (N=18) and conducting two life history interviews with each participant. Markers of ontological security-constancy, daily routines, privacy, and having a secure base for identity construction-provided sensitizing concepts for grounded theory analyses designed to also yield emergent, or new, themes. Findings revealed clear evidence of the markers of ontological security among participants living in their own apartments. This study expands upon previous research showing that homeless mentally ill persons are capable of independent living in the community. The emergent theme of 'what's next' questions and uncertainty about the future points to the need to address problems of stigma and social exclusion that extend beyond the minimal achievement of having a 'home'.",1
"Padgett, Deborah K",2
Memory trace stabilization leads to large-scale changes in the retrieval network: a functional MRI study on associative memory.,0
"Spaced learning with time to consolidate leads to more stabile memory traces. However, little is known about the neural correlates of trace stabilization, especially in humans. The present fMRI study contrasted retrieval activity of two well-learned sets of face-location associations, one learned in a massed style and tested on the day of learning (i.e., labile condition) and another learned in a spaced scheme over the course of one week (i.e., stabilized condition). Both sets of associations were retrieved equally well, but the retrieval of stabilized association was faster and accompanied by large-scale changes in the network supporting retrieval. Cued recall of stabilized as compared with labile associations was accompanied by increased activity in the precuneus, the ventromedial prefrontal cortex, the bilateral temporal pole, and left temporo-parietal junction. Conversely, memory representational areas such as the fusiform gyrus for faces and the posterior parietal cortex for locations did not change their activity with stabilization. The changes in activation in the precuneus, which also showed increased connectivity with the fusiform area, are likely to be related to the spatial nature of our task. The activation increase in the ventromedial prefrontal cortex, on the other hand, might reflect a general function in stabilized memory retrieval. This area might succeed the hippocampus in linking distributed neocortical representations.",1
"Takashima, Atsuko, Nieuwenhuis, Ingrid L C, Rijpkema, Mark, Petersson, Karl Magnus, Jensen, Ole, Fernández, Guillén",2
Low-frequency stimulation induces a pathway-specific late phase of LTP in the amygdala that is mediated by PKA and dependent on protein synthesis.,0
"Activity-dependent changes in synaptic efficacy are thought to be the key cellular mechanism for the formation and storage of both explicit and implicit memory. Different patterns of stimulation can elicit different changes in the efficiency on excitatory synaptic transmission. Here, we examined the synaptic changes in the amygdala of adult mice produced by low-frequency stimulation (1 Hz, 15 min, LFS). We first compared the synaptic changes induced by LFS in three different synaptic pathways of amygdala: cortical-lateral amygdala, thalamic-lateral amygdala, and lateral-basolateral amygdala pathways. We find that the plastic changes induced by LFS are different between synaptic pathways. Low-frequency stimulation selectively elicits a slow onset and protein synthesis-dependent late-phase LTP in the cortical-lateral amygdala pathway, but not in the thalamic-lateral or lateral-basolateral pathways. We next analyzed LTP induced by LFS in the cortical-lateral amygdala pathway and found that three PKA-coupling neurotransmitter receptors are involved: 5-HT4, Dopamine D1, and beta-adrenergic receptors. Antagonists of these receptors block the LFS L-LTP, but the effects of agonists of these receptors are clearly different. These results indicate that the threshold for the induction of LFS L-LTP is different among these pathways and that the maintenance of LFS L-LTP requires a cross-talk among multiple neurotransmitters.",1
"Huang, Yan-You, Kandel, Eric R",2
Temporal requirement of C/EBPbeta in the amygdala following reactivation but not acquisition of inhibitory avoidance.,0
"Following learning, a memory is fragile and undergoes a protein synthesis-dependent consolidation process in order to become stable. Established memories can again become transiently sensitive to disruption if reactivated and require another protein synthesis-dependent process, known as reconsolidation, in order to persist. Here, we show that, in the basolateral amygdala (BLA), protein synthesis is necessary for both consolidation and reconsolidation of inhibitory avoidance (IA) memory, while the expression of the transcription factor CCAAT enhancer binding protein beta (C/EBPbeta) is essential only for the reconsolidation process. Moreover, the critical roles of both protein synthesis and C/EBPbeta following IA reactivation are temporally restricted, as they are necessary only for recent but not old IA memories. These results, together with previous findings showing that in the hippocampus both protein synthesis and C/EBPbeta expression are required for consolidation but not reconsolidation of IA indicate that the stabilization process that takes place either after training or memory retrieval engages distinct neural circuits. Within these circuits, the C/EBPbeta-dependent molecular pathway appears to be differentially recruited.",1
"Milekic, Maria H, Pollonini, Gabriella, Alberini, Cristina M",2
Ectopic granule cells of the rat dentate gyrus.,0
"Granule cells of the mammalian dentate gyrus normally form a discrete layer, and virtually all granule cells migrate to this location. Exceptional granule cells that are positioned incorrectly, in 'ectopic' locations, are rare. Although the characteristics of such ectopic granule cells appear similar in many respects to granule cells located in the granule cell layer, their rare occurrence has limited a full evaluation of their structure and function. More information about ectopic granule cells has been obtained by studying those that develop after experimental manipulations that increase their number. For example, after severe seizures, the number of ectopic granule cells located in the hilus increases dramatically. These experimentally-induced ectopic granule cells may not be equivalent to normal ectopic granule cells necessarily, but the vastly increased numbers have allowed much more information to be obtained. Remarkably, the granule cells that are positioned ectopically develop intrinsic properties and an axonal projection that are similar to granule cells that are located normally, i.e., in the granule cell layer. However, dendritic structure and synaptic structure/function appear to differ. These studies have provided new insight into a rare type of granule cell in the dentate gyrus, and the plastic characteristics of dentate granule cells that appear to depend on the location of the cell body.",1
"Scharfman, Helen, Goodman, Jeffrey, McCloskey, Daniel",2
Constructing evidence-based treatment strategies using methods from computer science.,0
"This paper details a new methodology, instance-based reinforcement learning, for constructing adaptive treatment strategies from randomized trials. Adaptive treatment strategies are operationalized clinical guidelines which recommend the next best treatment for an individual based on his/her personal characteristics and response to earlier treatments. The instance-based reinforcement learning methodology comes from the computer science literature, where it was developed to optimize sequences of actions in an evolving, time varying system. When applied in the context of treatment design, this method provides the means to evaluate both the therapeutic and diagnostic effects of treatments in constructing an adaptive treatment strategy. The methodology is illustrated with data from the STAR*D trial, a multi-step randomized study of treatment alternatives for individuals with treatment-resistant major depressive disorder.",1
"Pineau, Joelle, Bellemare, Marc G, Rush, A John, Ghizaru, Adrian, Murphy, Susan A",2
Menstrual bleeding patterns following levonorgestrel emergency contraception.,0
"Multiple trials by the World Health Organization have established levonorgestrel as the gold standard in hormonal emergency contraception (EC). However, changes in menstrual patterns following EC have been observed; thus, we undertook this prospective study to identify and determine the characteristics of these changes.",1
"Gainer, Erin, Kenfack, Bruno, Mboudou, Emile, Doh, Anderson Sama, Bouyer, Jean",2
Repressor of temperate mycobacteriophage L1 harbors a stable C-terminal domain and binds to different asymmetric operator DNAs with variable affinity.,0
"Lysogenic mode of life cycle of a temperate bacteriophage is generally maintained by a protein called 'repressor'. Repressor proteins of temperate lambdoid phages bind to a few symmetric operator DNAs in order to regulate their gene expression. In contrast, repressor molecules of temperate mycobacteriophages and some other phages bind to multiple asymmetric operator DNAs. Very little is known at present about the structure-function relationship of any mycobacteriophage repressor.",1
"Ganguly, Tridib, Bandhu, Amitava, Chattoraj, Partho, Chanda, Palas K, Das, Malabika, Mandal, Nitai C, Sau, Subrata",2
Physical and social availability of alcohol for young enlisted naval personnel in and around home port.,0
"Heavy alcohol consumption rates are higher in the young adult military enlisted population than among civilians of the same age. The literature on alcohol availability, both generally and specifically with respect to work-related drinking, establishes clear links between ease of access, alcohol consumption rates and alcohol-related problems.",1
"Moore, Roland S, Ames, Genevieve M, Cunradi, Carol B",2
The pectoralis minor length test: a study of the intra-rater reliability and diagnostic accuracy in subjects with and without shoulder symptoms.,0
Postural abnormality and muscle imbalance are thought to contribute to pain and a loss of normal function in the upper body. A shortened pectoralis minor muscle is commonly identified as part of this imbalance. Clinical tests have been recommended to test for shortening of this muscle. The aim of this study was to evaluate the intra-rater reliability and diagnostic accuracy of the pectoralis minor length test.,1
"Lewis, Jeremy S, Valentine, Rachel E",2
Bismarck or Beveridge: a beauty contest between dinosaurs.,0
"Health systems delivery systems can be divided into two broad categories: National Health Services (NHS) on the one hand and Social Security (based) Health care systems (SSH) on the other hand. Existing literature is inconclusive about which system performs best. In this paper we would like to improve the evidence-base for discussion about pros and cons of NHS-systems versus SSH-system for health outcomes, expenditure and population satisfaction.",1
"van der Zee, Jouke, Kroneman, Madelon W",2
The effect of column purification on cDNA indirect labelling for microarrays.,0
"The success of the microarray reproducibility is dependent upon the performance of standardized procedures. Since the introduction of microarray technology for the analysis of global gene expression, reproducibility of results among different laboratories has been a major problem. Two of the main contributors to this variability are the use of different microarray platforms and different laboratory practices. In this paper, we address the latter question in terms of how variation in one of the steps of a labelling procedure affects the cDNA product prior to microarray hybridization.",1
"Molas, M Lia, Kiss, John Z",2
Molecular biology of cantharidin in cancer cells.,0
"Herbal medicine is one of the forms of traditional medical practice. Traditional Chinese medicine (TCM) and traditional Vietnamese medicine (TVM) are well-known for their long-standing tradition of herbal medicine. Secreted by many species of blister beetle, most notably by the 'Spanish fly' (Lytta vesicatoria), cantharidin inhibits protein phosphatases 1 and 2A (PP1, PP2A). Blister beetle has been used in Asian traditional medicine to treat Molluscum contagiosum virus (MCV) infections and associated warts, and is now also used for cancer treatment. A combination of both genomic and postgenomic techniques was used in our studies to identify candidate genes affecting sensitivity or resistance to cantharidin. Cantharidin was not found to be related to multidrug resistance phenotype, suggesting its potential usefulness for the treatment of refractory tumors. Oxidative stress response genes diminish the activity of cantharidin by inducing DNA strand breaks which may be subject to base excision repair and induce apoptosis in a p53- and Bcl2-dependent manner. Cantharidin is one of many natural products used in traditional Chinese medicine and traditional Vietnamese medicine for cancer treatment. Combined methods of pharmaceutical biology and molecular biology can help elucidate modes of action of these natural products.",1
"Rauh, Rolf, Kahl, Stefan, Boechzelt, Herbert, Bauer, Rudolf, Kaina, Bernd, Efferth, Thomas",2
Collective properties of evolving molecular quasispecies.,0
"RNA molecules, through their dual appearance as sequence and structure, represent a suitable model to study evolutionary properties of quasispecies. The essential ingredient in this model is the differentiation between genotype (molecular sequences which are affected by mutation) and phenotype (molecular structure, affected by selection). This framework allows a quantitative analysis of organizational properties of quasispecies as they adapt to different environments, such as their robustness, the effect of the degeneration of the sequence space, or the adaptation under different mutation rates and the error threshold associated.",1
"Stich, Michael, Briones, Carlos, Manrubia, Susanna C",2
Optical and electrical recording of neural activity evoked by graded contrast visual stimulus.,0
"Brain activity has been investigated by several methods with different principles, notably optical ones. Each method may offer information on distinct physiological or pathological aspects of brain function. The ideal instrument to measure brain activity should include complementary techniques and integrate the resultant information. As a ""low cost"" approach towards this objective, we combined the well-grounded electroencephalography technique with the newer near infrared spectroscopy methods to investigate human visual function.",1
"Rovati, Luigi, Salvatori, Giorgia, Bulf, Luca, Fonda, Sergio",2
Beta-adrenergic modulation of oddball responses in humans.,0
"Detection of salient or motivationally significant stimuli is of adaptive importance. The neurophysiological correlates of this detection have been extensively studied in 'oddball' paradigms. Much theoretical data supports the role of noradrenergic systems in generating oddball responses. We combine psychopharmacology and functional neuroimaging to demonstrate modulation of neuronal responses to oddball nouns by the beta-adrenergic antagonist propranolol. Critically, responses in regions implicated in oddball detection, namely right ventrolateral prefrontal cortex and temporoparietal junction (TPJ), were abolished by propranolol. Thus, oddball responses depend on modulatory adrenergic inputs, mediated via beta-adrenergic receptors.",1
"Strange, Bryan A, Dolan, Raymond J",2
The role of hydrophobic interactions in positioning of peripheral proteins in membranes.,0
"Three-dimensional (3D) structures of numerous peripheral membrane proteins have been determined. Biological activity, stability, and conformations of these proteins depend on their spatial positions with respect to the lipid bilayer. However, these positions are usually undetermined.",1
"Lomize, Andrei L, Pogozheva, Irina D, Lomize, Mikhail A, Mosberg, Henry I",2
Intimal pulmonary artery sarcoma presenting as dyspnea: case report.,0
We report a case of pulmonary sarcoma which is a rare cause of the common symptom of dyspnea.,1
"Hsing, Jeff M, Thakkar, Snehal G, Borden, Ernest C, Budd, George T",2
In silico comparative genomic analysis of GABAA receptor transcriptional regulation.,0
"Subtypes of the GABAA receptor subunit exhibit diverse temporal and spatial expression patterns. In silico comparative analysis was used to predict transcriptional regulatory features in individual mammalian GABAA receptor subunit genes, and to identify potential transcriptional regulatory components involved in the coordinate regulation of the GABAA receptor gene clusters.",1
"Joyce, Christopher J",2
Toward accurate high-throughput SNP genotyping in the presence of inherited copy number variation.,0
"The recent discovery of widespread copy number variation in humans has forced a shift away from the assumption of two copies per locus per cell throughout the autosomal genome. In particular, a SNP site can no longer always be accurately assigned one of three genotypes in an individual. In the presence of copy number variability, the individual may theoretically harbor any number of copies of each of the two SNP alleles.",1
"Macconaill, Laura E, Aldred, Micheala A, Lu, Xincheng, Laframboise, Thomas",2
The encounter with God in myth and madness.,0
It is well known how often psychiatric patients report religious experiences. These are especially frequent in schizophrenic and epileptic patients as the subject of their delusions. The question we pose is: are there differences between this kind of religious experiences and those we find in religious texts or in the mythological tradition?,1
"Doerr, Otto, Velásquez, Oscar",2
HIV-associated adipose redistribution syndrome (HARS): etiology and pathophysiological mechanisms.,0
"Human immunodeficiency virus (HIV)-associated adipose redistribution syndrome (HARS) is a fat accumulation disorder characterized by increases in visceral adipose tissue. Patients with HARS may also present with excess truncal fat and accumulation of dorsocervical fat (""buffalo hump""). The pathophysiology of HARS appears multifactorial and is not fully understood at present. Key pathophysiological influences include adipocyte dysfunction and an excessive free fatty acid release by adipocyte lipolysis. The contributory roles of free fatty acids, cytokines, hormones including cortisol, insulin and the growth hormone-adipocyte axis are significant. Other potential humoral, paracrine, endocrine, and neural influences are also discussed.",1
"Lichtenstein, Kenneth, Balasubramanyam, Ashok, Sekhar, Rajagopal, Freedland, Eric",2
Usual choline and betaine dietary intake and incident coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) study.,0
"Low dietary intake of the essential nutrient choline and its metabolite betaine may increase atherogenesis both through effects on homocysteine methylation pathways as well as through choline's antioxidants properties. Nutrient values for many common foods for choline and betaine have recently become available in the U.S. nutrient composition database. Our objective was to assess the association of dietary intake of choline and betaine with incident coronary heart disease (CHD), adjusting for dietary intake measurement error.",1
"Bidulescu, Aurelian, Chambless, Lloyd E, Siega-Riz, Anna Maria, Zeisel, Steven H, Heiss, Gerardo",2
GM and KM immunoglobulin allotypes in the Galician population: new insights into the peopling of the Iberian Peninsula.,0
"The current genetic structure of Iberian populations has presumably been affected by the complex orography of its territory, the different people and civilizations that settled there, its ancient and complex history, the diverse and persistent sociocultural patterns in its different regions, and also by the effects of the Iberian Peninsula representing a refugium area after the last glacial maximum. This paper presents the first data on GM and KM immunoglobulin allotypes in the Galician population and, thus, provides further insights into the extent of genetic diversity in populations settled in the geographic extremes of the Cantabrian region of northern Spain. Furthermore, the genetic relationships of Galicians with other European populations have been investigated.",1
"Calderón, Rosario, Lodeiro, Rosa, Varela, Tito A, Fariña, José, Ambrosio, Beatriz, Guitard, Evelyne, González-Martín, Antonio, Dugoujon, Jean M",2
Metabolic network visualization eliminating node redundance and preserving metabolic pathways.,0
"The tools that are available to draw and to manipulate the representations of metabolism are usually restricted to metabolic pathways. This limitation becomes problematic when studying processes that span several pathways. The various attempts that have been made to draw genome-scale metabolic networks are confronted with two shortcomings: 1- they do not use contextual information which leads to dense, hard to interpret drawings, 2- they impose to fit to very constrained standards, which implies, in particular, duplicating nodes making topological analysis considerably more difficult.",1
"Bourqui, Romain, Cottret, Ludovic, Lacroix, Vincent, Auber, David, Mary, Patrick, Sagot, Marie-France, Jourdan, Fabien",2
Modulation of nuclear internalization of Tat peptides by fluorescent dyes and receptor-avid peptides.,0
"The nuclear internalization of biomolecules by Tat peptide provides a mechanism to deliver drugs to cells. However, translocation of molecular imaging probes to the nucleus may induce undesirable mutagenesis. To assess the feasibility of retaining its cell permeating effect without nuclear translocation, Tat-peptide was conjugated with a somatostatin receptor (STR)-avid ligand (Oct) and labeled with fluorescent dyes. The results show that Tat-Oct-5-FAM (fluorescein 5'-carboxylic acid) remained in the cytoplasm of STR-positive AR42J cells. Co-incubation of Tat-Oct-5-FAM with ATP induced nuclear translocation. These data suggest that both dye and Oct-STR endocytosis complex could modulate nuclear internalization of Tat peptides.",1
"Shen, Duanwen, Liang, Kexian, Ye, Yunpeng, Tetteh, Elizabeth, Achilefu, Samuel",2
Imputation-based analysis of association studies: candidate regions and quantitative traits.,0
"We introduce a new framework for the analysis of association studies, designed to allow untyped variants to be more effectively and directly tested for association with a phenotype. The idea is to combine knowledge on patterns of correlation among SNPs (e.g., from the International HapMap project or resequencing data in a candidate region of interest) with genotype data at tag SNPs collected on a phenotyped study sample, to estimate (""impute"") unmeasured genotypes, and then assess association between the phenotype and these estimated genotypes. Compared with standard single-SNP tests, this approach results in increased power to detect association, even in cases in which the causal variant is typed, with the greatest gain occurring when multiple causal variants are present. It also provides more interpretable explanations for observed associations, including assessing, for each SNP, the strength of the evidence that it (rather than another correlated SNP) is causal. Although we focus on association studies with quantitative phenotype and a relatively restricted region (e.g., a candidate gene), the framework is applicable and computationally practical for whole genome association studies. Methods described here are implemented in a software package, Bim-Bam, available from the Stephens Lab website http://stephenslab.uchicago.edu/software.html.",1
"Servin, Bertrand, Stephens, Matthew",2
Genome-wide association scan shows genetic variants in the FTO gene are associated with obesity-related traits.,0
"The obesity epidemic is responsible for a substantial economic burden in developed countries and is a major risk factor for type 2 diabetes and cardiovascular disease. The disease is the result not only of several environmental risk factors, but also of genetic predisposition. To take advantage of recent advances in gene-mapping technology, we executed a genome-wide association scan to identify genetic variants associated with obesity-related quantitative traits in the genetically isolated population of Sardinia. Initial analysis suggested that several SNPs in the FTO and PFKP genes were associated with increased BMI, hip circumference, and weight. Within the FTO gene, rs9930506 showed the strongest association with BMI (p = 8.6 x10(-7)), hip circumference (p = 3.4 x 10(-8)), and weight (p = 9.1 x 10(-7)). In Sardinia, homozygotes for the rare ""G"" allele of this SNP (minor allele frequency = 0.46) were 1.3 BMI units heavier than homozygotes for the common ""A"" allele. Within the PFKP gene, rs6602024 showed very strong association with BMI (p = 4.9 x 10(-6)). Homozygotes for the rare ""A"" allele of this SNP (minor allele frequency = 0.12) were 1.8 BMI units heavier than homozygotes for the common ""G"" allele. To replicate our findings, we genotyped these two SNPs in the GenNet study. In European Americans (N = 1,496) and in Hispanic Americans (N = 839), we replicated significant association between rs9930506 in the FTO gene and BMI (p-value for meta-analysis of European American and Hispanic American follow-up samples, p = 0.001), weight (p = 0.001), and hip circumference (p = 0.0005). We did not replicate association between rs6602024 and obesity-related traits in the GenNet sample, although we found that in European Americans, Hispanic Americans, and African Americans, homozygotes for the rare ""A"" allele were, on average, 1.0-3.0 BMI units heavier than homozygotes for the more common ""G"" allele. In summary, we have completed a whole genome-association scan for three obesity-related quantitative traits and report that common genetic variants in the FTO gene are associated with substantial changes in BMI, hip circumference, and body weight. These changes could have a significant impact on the risk of obesity-related morbidity in the general population.",1
"Scuteri, Angelo, Sanna, Serena, Chen, Wei-Min, Uda, Manuela, Albai, Giuseppe, Strait, James, Najjar, Samer, Nagaraja, Ramaiah, Orrú, Marco, Usala, Gianluca, Dei, Mariano, Lai, Sandra, Maschio, Andrea, Busonero, Fabio, Mulas, Antonella, Ehret, Georg B, Fink, Ashley A, Weder, Alan B, Cooper, Richard S, Galan, Pilar, Chakravarti, Aravinda, Schlessinger, David, Cao, Antonio, Lakatta, Edward, Abecasis, Gonçalo R",2
Semi-automatic classification of skeletal morphology in genetically altered mice using flat-panel volume computed tomography.,0
"Rapid progress in exploring the human and mouse genome has resulted in the generation of a multitude of mouse models to study gene functions in their biological context. However, effective screening methods that allow rapid noninvasive phenotyping of transgenic and knockout mice are still lacking. To identify murine models with bone alterations in vivo, we used flat-panel volume computed tomography (fpVCT) for high-resolution 3-D imaging and developed an algorithm with a computational intelligence system. First, we tested the accuracy and reliability of this approach by imaging discoidin domain receptor 2- (DDR2-) deficient mice, which display distinct skull abnormalities as shown by comparative landmark-based analysis. High-contrast fpVCT data of the skull with 200 microm isotropic resolution and 8-s scan time allowed segmentation and computation of significant shape features as well as visualization of morphological differences. The application of a trained artificial neuronal network to these datasets permitted a semi-automatic and highly accurate phenotype classification of DDR2-deficient compared to C57BL/6 wild-type mice. Even heterozygous DDR2 mice with only subtle phenotypic alterations were correctly determined by fpVCT imaging and identified as a new class. In addition, we successfully applied the algorithm to classify knockout mice lacking the DDR1 gene with no apparent skull deformities. Thus, this new method seems to be a potential tool to identify novel mouse phenotypes with skull changes from transgenic and knockout mice on the basis of random mutagenesis as well as from genetic models. However for this purpose, new neuronal networks have to be created and trained. In summary, the combination of fpVCT images with artificial neuronal networks provides a reliable, novel method for rapid, cost-effective, and noninvasive primary screening tool to detect skeletal phenotypes in mice.",1
"Dullin, Christian, Missbach-Guentner, Jeannine, Vogel, Wolfgang F, Grabbe, Eckhardt, Alves, Frauke",2
Detection of Chlamydia pneumoniae in a bilateral orbital mucosa-associated lymphoid tissue lymphoma.,0
To detect Chlamydia pneumoniae (C. pneumoniae) gene in a patient with bilateral orbital musoca-associated lymphoid tissue (MALT) lymphoma.,1
"Shen, Defen, Yuen, Hunter K L, Galita, Dan A, Chan, Nongnart R, Chan, Chi-Chao",2
Linkages between child abuse and attention-deficit/hyperactivity disorder in girls: behavioral and social correlates.,0
The objectives of this study were to examine whether girls with attention-deficit/hyperactivity disorder (ADHD) are at increased risk of having histories of abuse and to assess whether the presence of an abuse history may constitute a distinct subgroup of youth with ADHD.,1
"Briscoe-Smith, Allison M, Hinshaw, Stephen P",2
B7-1 and 4-1BB ligand expression on a myeloma cell line makes it possible to expand autologous tumor-specific cytotoxic T cells in vitro.,0
The aim of this study was to confer an antigen-presenting cell (APC) ability on multiple myeloma cell lines (HMCLs) using B7-1 and/or 4-1BBL gene transfer.,1
"Lu, Zhao-Yang, Condomines, Maud, Tarte, Karin, Nadal, Laure, Delteil, Marie Claude, Rossi, Jean François, Ferrand, Christophe, Klein, Bernard",2
Cell cycle features of primate embryonic stem cells.,0
"Using flow cytometry measurements combined with quantitative analysis of cell cycle kinetics, we show that rhesus monkey embryonic stem cells (ESCs) are characterized by an extremely rapid transit through the G1 phase, which accounts for 15% of the total cell cycle duration. Monkey ESCs exhibit a non-phasic expression of cyclin E, which is detected during all phases of the cell cycle, and do not growth-arrest in G1 after gamma-irradiation, reflecting the absence of a G1 checkpoint. Serum deprivation or pharmacological inhibition of mitogen-activated protein kinase kinase (MEK) did not result in any alteration in the cell cycle distribution, indicating that ESC growth does not rely on mitogenic signals transduced by the Ras/Raf/MEK pathway. Taken together, these data indicate that rhesus monkey ESCs, like their murine counterparts, exhibit unusual cell cycle features in which cell cycle control mechanisms operating during the G1 phase are reduced or absent.",1
"Fluckiger, Anne-Catherine, Marcy, Guillaume, Marchand, Mélanie, Négre, Didier, Cosset, François-Loïc, Mitalipov, Shoukhrat, Wolf, Don, Savatier, Pierre, Dehay, Colette",2
Suppression of apoptosis by enhanced protein adsorption on polymer/hydroxyapatite composite scaffolds.,0
"Bone tissue engineering is a promising alternative to bone grafting. Scaffolds play a critical role in tissue engineering. Composite scaffolds made of biodegradable polymers and bone mineral-like inorganic compounds have been reported to be advantageous over plain polymer scaffolds by our group and others. In this study, we compared cellular and molecular events during the early periods of osteoblastic cell culture on poly(l-lactic acid)/hydroxyapatite (PLLA/HAP) composite scaffolds with those on plain PLLA scaffolds, and showed that PLLA/HAP scaffolds improved cell survival over plain PLLA scaffolds. Most cells (MC3T3-E1) on PLLA/HAP scaffolds survived the early culture. In contrast, about 50% of the cells initially adhered to the plain PLLA scaffolds were detached within the first 12h and showed characteristics of apoptotic cell death, which was confirmed by TUNEL staining and caspase-3 activation. To investigate the mechanisms, we examined the adsorption of serum protein and adhesion molecules to the scaffolds. The PLLA/HAP scaffold adsorbed more than 1.4 times of total serum protein and much greater amounts of serum fibronectin and vitronectin than pure PLLA scaffolds. Similarly, significantly larger amounts of individual adhesion proteins and peptides (fibronectin, vitronectin, RGD, and KRSR) were adsorbed on the PLLA/HAP scaffolds than on the PLLA scaffolds, which resulted in higher cell density on the PLLA/HAP scaffolds. Furthermore, beta1 and beta3 integrins and phosphorylation of Fak and Akt proteins in the cells on the PLLA/HAP scaffolds were significantly more abundent than those on PLLA scaffolds, which suggest that enhanced adsorption of serum adhesion proteins to PLLA/HAP scaffolds protect the cells from apoptosis possibly through the integrin-FAK-Akt pathway. These results demonstrate that biomimetic composite scaffolds are advantageous for bone tissue engineering.",1
"Woo, Kyung Mi, Seo, Jihye, Zhang, Ruiyun, Ma, Peter X",2
The influence of human respiratory epithelia on Pseudomonas aeruginosa gene expression.,0
"The opportunistic pathogen Pseudomonas aeruginosa can cause acute or chronic infections in humans. Little is known about the initial adaptation of P. aeruginosa to host tissues and the factors that determine whether a P. aeruginosa-epithelial cell interaction will manifest as an acute or a chronic infection. To gain insights into the initial phases of P. aeruginosa infections and to identify P. aeruginosa genes regulated in response to respiratory epithelia, we exposed P. aeruginosa to cultured primary differentiated human airway epithelia. We used a P. aeruginosa strain that causes acute damage to the epithelia and a mutant with defects in Type III secretion and in rhamnolipid synthesis. The mutant did not cause rapid damage to epithelia as did the wildtype. We compared the transcriptomes of the P. aeruginosa wildtype and the mutant to each other and to P. aeruginosa grown under other conditions, and we discovered overlapping sets of differentially expressed genes in the wildtype and mutant exposed to epithelia. A recent study reported that exposure of P. aeruginosa to epithelia is characterized by a repression of the bacterial iron-responsive genes. These findings were suggestive of ample iron availability during infection. In contrast, we found that P. aeruginosa shows an iron-starvation response upon exposure to epithelial cells. This observation highlights the importance of the iron starvation response in both acute and chronic infections and suggests opportunities for therapy.",1
"Chugani, Sudha, Greenberg, E P",2
Expression of microRNAs is dynamically regulated during cardiomyocyte hypertrophy.,0
"MicroRNAs (miRNAs) are a recently discovered class of approximately 22-nucleotide regulatory RNAs that post-transcriptionally regulate gene expression. We have recently demonstrated that muscle-specific miRNAs miR-1 and miR-133 play an important role in modulating muscle proliferation and differentiation. Here, we investigate the involvement of miRNAs in cardiac hypertrophy. We analyzed the global expression of miRNAs in agonist-induced hypertrophic cardiomyocytes as well as in pressure overload-induced hypertrophic hearts and found the miRNA expression profile altered in those hypertrophic conditions. We further show that inhibition of endogenous miR-21 or miR-18b augments hypertrophic growth. Conversely, introduction of functional miR-21 or miR-18b into cardiomyocytes represses myocyte hypertrophy. Together, our studies point to miRNAs as critical regulators of cardiac hypertrophy.",1
"Tatsuguchi, Mariko, Seok, Hee Young, Callis, Thomas E, Thomson, J Michael, Chen, Jian-Fu, Newman, Martin, Rojas, Mauricio, Hammond, Scott M, Wang, Da-Zhi",2
TRP channels and Ca2+ signaling.,0
"There is a rapidly growing interest in the family of transient receptor potential (TRP) channels because TRP channels are not only important for many sensory systems, but they are crucial components of the function of neurons, epithelial, blood and smooth muscle cells. These facts make TRP channels important targets for treatment of diseases arising from the malfunction of these channels in the above cells and for treatment of inflammatory pain. TRP channels are also important for a growing number of genetic diseases arising from mutations in various types of TRP channels. The Minerva-Gentner Symposium on TRP channels and Ca(2+) signaling, which took place in Eilat, Israel (February 24-28, 2006) has clearly demonstrated that the study of TRP channels is a newly emerging field of biomedicine with prime importance. In the Eilat symposium, investigators who have contributed seminal publications and insight into the TRP field presented their most recent, and in many cases still unpublished, studies. The excellent presentations and excitement generated by them demonstrated that much progress has been achieved. Nevertheless, it was also evident that the field of TRP channels is still in its infancy in comparison to other fields of ion channels, and even the fundamental knowledge of the gating mechanism of TRP channels is still unsolved. The beautiful location of the symposium, together with informal intensive discussions among the participants, contributed to the success of this meeting.",1
"Minke, Baruch",2
Insights on TRP channels from in vivo studies in Drosophila.,0
"Transient receptor potential (TRP) channels mediate responses in a large variety of signaling mechanisms. Most studies on mammalian TRP channels rely on heterologous expression, but their relevance to in vivo tissues is not entirely clear. In contrast, Drosophila TRP and TRP-like (TRPL) channels allow direct analyses of in vivo function. In Drosophila photoreceptors, activation of TRP and TRPL is mediated via the phosphoinositide cascade, with both Ca2+ and diacylglycerol (DAG) essential for generating the light response. In tissue culture cells, TRPL channels are constitutively active, and lipid second messengers greatly facilitate this activity. Inhibition of phospholipase C (PLC) completely blocks lipid activation of TRPL, suggesting that lipid activation is mediated via PLC. In vivo studies in mutant Drosophila also reveal an acute requirement for lipid-producing enzyme, which may regulate PLC activity. Thus, PLC and its downstream second messengers, Ca2+ and DAG, constitute critical mediators of TRP/TRPL gating in vivo.",1
"Minke, Baruch, Parnas, Moshe",2
Formation of singlet oxygen from solutions of vitamin E.,0
"Vitamin E offers protection against oxidative stress and is an efficient quencher of singlet oxygen. A recent report suggests that photo-excitation of vitamin E results in the formation of a triplet state (Naqvi et al. Photochem Photobiol Sci 2, 381 (2003)). This leads to the possibility of the triplet state of vitamin E being able to sensitize singlet oxygen and if this is the case it would be counter productive in terms of the biological protective function of vitamin E. We report the production of singlet oxygen, detected by 1270 nm luminescence, from pulsed laser excitation (308 nm) of vitamin E and an analogue, 2,2,5,7,8-pentamethyl-6-hydroxy-chroman (PMHC), with quantum yields between ~0.1 and 0.2. The luminescence was identified as singlet oxygen from self-quenching by vitamin E with solvent-dependent rate constants similar to published values. Whilst the beneficial antioxidant aspects of vitamin E are well established, these results indicate that vitamin E when directly excited can sensitize singlet oxygen formation and may, therefore, be capable of inducing biochemical and biological damage. The results are discussed in relation to recent reports on the deleterious effects of vitamin E dietary supplementation and pro-oxidant effects of vitamin E.",1
"Dad, Shakeela, Bisby, Roger H, Clark, Ian P, Parker, Anthony W",2
Identifying sedentary subgroups: the National Cancer Institute's Health Information National Trends Survey.,0
Developing effective interventions for the 24% to 28% of U.S. adults who are sedentary requires a better understanding of the factors related to sedentary lifestyles as well as the communication channels to reach various subgroups. This study identified key sociodemographic and health communication characteristics of various subgroups with high rates of inactivity using signal detection methodology.,1
"Atienza, Audie A, Yaroch, Amy L, Mãsse, Louise C, Moser, Richard P, Hesse, Bradford W, King, Abby C",2
Busulfan-conditioned bone marrow transplantation results in high-level allogeneic chimerism in mice made tolerant by in utero hematopoietic cell transplantation.,0
"In utero hematopoietic cell transplantation (IUHCT) is a non-ablative approach that achieves mixed allogeneic chimerism and donor-specific tolerance. However, clinical application of IUHCT has been limited by minimal engraftment. We have previously demonstrated in the murine model that low-level allogeneic chimerism achieved by IUHCT can be enhanced to near-complete donor chimerism by postnatal minimally myeloablative total body irradiation (TBI) followed by same-donor bone marrow transplantation. Because of concerns of toxicity related to even low-dose TBI in early life, we wondered if a potentially less toxic strategy utilizing a single myelosuppressive agent, Busulfan (BU), would provide similar enhancement of engraftment.",1
"Ashizuka, Shuichi, Peranteau, William H, Hayashi, Satoshi, Flake, Alan W",2
"Identifying students with self-report of asthma and respiratory symptoms in an urban, high school setting.",0
"Strategies for identifying urban youth with asthma have not been described for high school settings. African-American high school students are rarely included in asthma studies, despite a high risk of asthma mortality when compared to other age and race groups. Identification and follow-up of children with uncontrolled respiratory symptoms are necessary to reduce the burden of asthma morbidity and mortality, especially in underserved areas. We describe a process used to identify high school students who could benefit from intervention based on self-report of asthma and/or respiratory symptoms, and the costs associated with symptom-identification. Letters announcing a survey were mailed to parents of 9th-11th graders by an authorized vendor managing student data for the school district. Scan sheets with student identifiers were distributed to English teachers at participating schools who administered the survey during a scheduled class. Forms were completed by 5,967 of the 7,446 students assigned an English class (80% response). Although prevalence of lifetime asthma was 15.8%, about 11% of students met program criteria for enrollment through report of an asthma diagnosis and recent symptoms, medication use, or health care utilization. Another 9.2% met criteria by reported symptoms only. Cost of symptom-identification was $5.23/student or $32.29/program-eligible student. There is a need for school-based asthma programs targeting urban adolescents, and program initiation will likely require identification of students with uncontrolled symptoms. The approach described was successfully implemented with a relatively high response rate. Itemized expenses are presented to facilitate modifications to reduce costs. This information may benefit providers, researchers, or administrators targeting similar populations.",1
"Joseph, Christine L M, Baptist, Alan P, Stringer, Sonja, Havstad, Suzanne, Ownby, Dennis R, Johnson, Christine Cole, Williams, L Keoki, Peterson, Edward L",2
"Comparison of chronic toxicity and carcinogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in 2-year bioassays in female Sprague-Dawley rats.",0
"The cancer bioassay for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) conducted by the Dow Chemical company in the mid 70s has been used extensively for conducting quantitative cancer risk assessments for human exposure to TCDD. More recently the National Toxicology Program (NTP) conducted a cancer bioassay of similar design as part of its evaluation of the dioxin toxic equivalency factor methodology. This report compares the design and the results of these two cancer bioassays. This comparison confirms, in most cases, previously published and widely used carcinogenic response characteristics with respect to dose, time course, organ selectivity, tumor type and maximum intensity of TCDD-induced carcinogenicity and toxicity in the Sprague-Dawley rat. Specifically, increases in the incidences of neoplasms were seen in both studies in the liver, lung and oral mucosa. The most notable difference was the significant increase in the incidence of cholangiocarcinoma of the liver seen in the NTP study but not in the Dow study. The experimental designs for the two studies are similar but some protocol parameters differed, such as vehicle, dosing schedule, diet and rat sub-strain utilized. Differences in the shapes of the dose response curves for several neoplasms were noted between the studies, with the NTP study showing non-linearity for all neoplasms. This may result from differences in the experimental protocols as well as divergence in the biological behavior of the different stocks of Sprague-Dawley rat strains used.",1
"Walker, Nigel J, Wyde, Michael E, Fischer, Lawrence J, Nyska, Abraham, Bucher, John R",2
Single- and multi-photon excited fluorescence from serotonin complexed with beta-cyclodextrin.,0
"The fluorescence of serotonin on binding with beta-cyclodextrin has been studied using both steady state and time-resolved methods. Steady state fluorescence intensity of serotonin at 340 nm showed approximately 30% increase in intensity on binding with K(A) approximately 60 dm(3) mol(-1) and the fluorescence lifetimes showed a corresponding increase. In contrast, the characteristic green fluorescence ('hyperluminescence') of serotonin observed upon multiphoton near-infrared excitation with sub-picosecond pulses was resolved into two lifetime components assigned to free and bound serotonin. The results are of interest in relation to selective imaging and detection of serotonin using the unusual hyperluminescence emission and in respect to recent determinations of serotonin by capillary electrophoresis in the presence of cyclodextrin. The results also suggest that hyperluminescence occurs from multiphoton excitation of a single isolated serotonin molecule.",1
"Bisby, Roger H, Botchway, Stanley W, Dad, Shakeela, Parker, Anthony W",2
Basic mechanisms of oxidative stress and reactive oxygen species in cardiovascular injury.,0
"The development of vascular disease has its origins in an initial insult to the vessel wall by biological or mechanical factors. The disruption of homeostatic mechanisms leads to alteration of the original architecture of the vessel and its biological responsiveness, contributing to acute or chronic diseases such as stroke, hypertension, and atherosclerosis. Endothelial dysfunction, macrophage infiltration of the vessel wall, and proliferation and migration of smooth muscle cells all involve different types of reactive oxygen species produced by various vessel wall components. Although basic science and animal research have clearly established the role of reactive oxygen species in the progression of vascular disease, the failure of clinical trials with antioxidant compounds has underscored the need for better antioxidant therapies and a more thorough understanding of the role of reactive oxygen species in cardiovascular physiology and pathology.",1
"Papaharalambus, Christopher A, Griendling, Kathy K",2
Small heat shock proteins protect against alpha-synuclein-induced toxicity and aggregation.,0
"Protein misfolding and inclusion formation are common events in neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD) or Huntington's disease (HD). Alpha-synuclein (aSyn) is the main protein component of inclusions called Lewy bodies (LB) which are pathognomic of PD, Dementia with Lewy bodies (DLB), and other diseases collectively known as LB diseases. Heat shock proteins (HSPs) are one class of the cellular quality control system that mediate protein folding, remodeling, and even disaggregation. Here, we investigated the role of the small heat shock proteins Hsp27 and alphaB-crystallin, in LB diseases. We demonstrate, via quantitative PCR, that Hsp27 messenger RNA levels are approximately 2-3-fold higher in DLB cases compared to control. We also show a corresponding increase in Hsp27 protein levels. Furthermore, we found that Hsp27 reduces aSyn-induced toxicity by approximately 80% in a culture model while alphaB-crystallin reduces toxicity by approximately 20%. In addition, intracellular inclusions were immunopositive for endogenous Hsp27, and overexpression of this protein reduced aSyn aggregation in a cell culture model.",1
"Outeiro, Tiago Fleming, Klucken, Jochen, Strathearn, Katherine E, Liu, Fang, Nguyen, Paul, Rochet, Jean-Christophe, Hyman, Bradley T, McLean, Pamela J",2
Reactive oxygen species signaling in vascular smooth muscle cells.,0
"Reactive oxygen species (ROS) have been shown to function as important signaling molecules in the cardiovascular system. Vascular smooth muscle cells (VSMCs) contain several sources of ROS, among which the NADPH oxidases are predominant. In VSMCs, ROS mediate many pathophysiological processes, such as growth, migration, apoptosis and secretion of inflammatory cytokines, as well as physiological processes, such as differentiation, by direct and indirect effects at multiple signaling levels. Therefore, it becomes critical to understand the different roles ROS play in the physiology and pathophysiology of VSMCs.",1
"Clempus, Roza E, Griendling, Kathy K",2
Body mass index cut offs to define thinness in children and adolescents: international survey.,0
"To determine cut offs to define thinness in children and adolescents, based on body mass index at age 18 years.",1
"Cole, Tim J, Flegal, Katherine M, Nicholls, Dasha, Jackson, Alan A",2
Limitations of rapid HIV-1 tests during screening for trials in Uganda: diagnostic test accuracy study.,0
To evaluate the limitations of rapid tests for HIV-1.,1
"Gray, Ronald H, Makumbi, Fredrick, Serwadda, David, Lutalo, Tom, Nalugoda, Fred, Opendi, Pius, Kigozi, Godfrey, Reynolds, Steven J, Sewankambo, Nelson K, Wawer, Maria J",2
The effect of androgen deprivation therapy on periodontal disease in men with prostate cancer.,0
We tested the hypothesis that men undergoing androgen deprivation therapy as treatment for prostate cancer are at greater risk for periodontitis and tooth loss.,1
"Famili, Pouran, Cauley, Jane A, Greenspan, Susan L",2
Hypoglycemia activates arousal-related neurons and increases wake time in adult rats.,0
"Hypoglycemia resulting from excess of exogenous or endogenous insulin elicits central nervous system activation that contributes to counterregulatory hormone secretion. In adult humans without diabetes, hypoglycemia occurring during sleep usually produces cortical activation with awakening. However, in adult humans with type 1 diabetes, hypoglycemic arousal appears blunted or absent. We hypothesized that insulin injection sufficient to produce hypoglycemia would induce awakening in adult male rats. Polysomnographic studies were carried out to characterize the effect of insulin injection on measures of sleep and waking during a circadian time of increased sleep. Compared to a baseline day, insulin treatment more than doubled the time spent awake, from 18.4+/-2.6% after saline injection to 48.0+/-5.5% after insulin. Insulin injection also reduced rapid eye movement sleep (REMS) from 27.3+/-1.8% to 5.6+/-1.3%. The percent of time in non-REM sleep (NREMS) sleep was not different between saline and insulin days, however, NREMS after insulin was fragmented, with increased number and decreased duration of episodes. These electrophysiological data indicate that insulin-induced hypoglycemia is an arousing stimulus in rats, as in nondiabetic adult humans. We also studied the effect of insulin on activation of selected arousal-related neurons using immunohistochemical detection of Fos. Fos-immunoreactivity increased in orexin (OX) neurons after insulin, from 8.7+/-4.9% after saline injection to 37+/-9% after insulin. Basal forebrain cholinergic nuclei also showed increased Fos-immunoreactivity after insulin. These correlated behavioral and histological data provide targets for future studies of the neural pathways underlying hypoglycemic arousal.",1
"Tkacs, Nancy C, Pan, Yanhua, Sawhney, Gagan, Mann, Graziella L, Morrison, Adrian R",2
Correlates of suicidal ideation and attempt among female sex workers in China.,0
"The purpose of this study was to explore the factors associated with suicidal ideation and attempt among female sex workers (FSWs) in China. A cross-sectional survey was administered among 454 FSWs in a rural county of Guangxi, China. About 14% of FSWs had thought of suicide and 8% had attempted suicide in the past 6 months. Multiple logistic regression analyses indicated that those FSWs who were dissatisfied with life, abused alcohol, were deceived or forced into commercial sex, and had stable sexual partners were more likely to report suicidal ideation. Female sex workers who had multiple stable partners, experienced sexual coercion, and worried about an inability to make enough money were more likely to report a suicide attempt. These FSWs who entered commercial sex because of financial needs or who were influenced by the peers were less likely to report a suicide attempt. Our data suggested that the rates of suicidal ideation and attempts were high among FSWs in China, and there were multiple factors associated with their suicidality. Future health education and promotion efforts among FSWs need to take into consideration substance abuse, interpartner conflict, and psychological stress.",1
"Hong, Yan, Li, Xiaoming, Fang, Xiaoyi, Zhao, Ran",2
Psychiatric disorders in inhalant users: results from The National Epidemiologic Survey on Alcohol and Related Conditions.,0
"To examine the prevalence and correlates of mood, anxiety, and personality disorders among lifetime inhalant users.",1
"Wu, Li-Tzy, Howard, Matthew Owen",2
A PCR-based method for detection and quantification of small RNAs.,0
"Recent cloning efforts have identified hundreds of thousands of small RNAs including micro RNAs (miRNAs), Piwi-interacting RNAs (piRNAs), and small nucleolar RNAs (snoRNAs). These non-coding small RNAs need to be further validated and characterized by detecting and quantifying their expression in different tissues and during different developmental courses. A simple, accurate, and sensitive method for small RNA expression profiling is in high demand. Here, we report such a PCR-based method.",1
"Ro, Seungil, Park, Chanjae, Jin, Jingling, Sanders, Kenton M, Yan, Wei",2
Evaluation of patients treated with natalizumab for progressive multifocal leukoencephalopathy.,0
Progressive multifocal leukoencephalopathy (PML) was reported to have developed in three patients treated with natalizumab. We conducted an evaluation to determine whether PML had developed in any other treated patients.,1
"Yousry, Tarek A, Major, Eugene O, Ryschkewitsch, Caroline, Fahle, Gary, Fischer, Steven, Hou, Jean, Curfman, Blanche, Miszkiel, Katherine, Mueller-Lenke, Nicole, Sanchez, Esther, Barkhof, Frederik, Radue, Ernst-Wilhelm, Jäger, Hans R, Clifford, David B",2
Lack of extracellular superoxide dismutase (EC-SOD) in the microenvironment impacts radiation-induced changes in neurogenesis.,0
"Ionizing irradiation results in significant alterations in hippocampal neurogenesis that are associated with cognitive impairments. Such effects are influenced, in part, by alterations in the microenvironment within which the neurogenic cells exist. One important factor that may affect neurogenesis is oxidative stress, and this study was done to determine if and how the extracellular isoform of superoxide dismutase (SOD3, EC-SOD) mediated radiation-induced alterations in neurogenic cells. Wild-type (WT) and EC-SOD knockout (KO) mice were irradiated with 5 Gy and acute (8-48 h) cellular changes and long-term changes in neurogenesis were quantified. Acute radiation responses were not different between genotypes, suggesting that the absence of EC-SOD did not influence mechanisms responsible for acute cell death after irradiation. On the other hand, the extent of neurogenesis was decreased by 39% in nonirradiated KO mice relative to WT controls. In contrast, while neurogenesis was decreased by nearly 85% in WT mice after irradiation, virtually no reduction in neurogenesis was observed in KO mice. These findings show that after irradiation, an environment lacking EC-SOD is much more permissive in the context of hippocampal neurogenesis. This finding may have a major impact in developing strategies to reduce cognitive impairment after cranial irradiation.",1
"Rola, Radoslaw, Zou, Yani, Huang, Ting-Ting, Fishman, Kelly, Baure, Jennifer, Rosi, Susanna, Milliken, Heather, Limoli, Charles L, Fike, John R",2
Modulation of Bone Morphogenetic Protein (BMP) 2 gene expression by Sp1 transcription factors.,0
"Changes in Bone Morphogenetic Protein (BMP) 2 gene expression and activity have been linked to many pathological conditions including cancer, osteoarthritis, and birth defects. BMP2 gene polymorphisms have been linked to osteoporosis and osteoarthritis. Sp1 and related proteins are widely expressed regulators of gene expression whose transcription activating abilities vary in different cells and on different genes. We present data indicating that the ratio of Sp1 and Sp3 isoforms varies in cells that express or do not express BMP2. Furthermore, the orientation of Sp1 sites conserved between four orders of mammals influences BMP2 expression. Together our data indicate that the stoichiometry and orientation of Sp1 and Sp3 complexes on the BMP2 promoter influence BMP2 expression.",1
"Xu, Junwang, Rogers, Melissa B",2
Mechanisms of action of glucagon-like peptide 1 in the pancreas.,0
"Glucagon-like peptide 1 (GLP-1) is a hormone that is encoded in the proglucagon gene. It is mainly produced in enteroendocrine L cells of the gut and is secreted into the blood stream when food containing fat, protein hydrolysate, and/or glucose enters the duodenum. Its particular effects on insulin and glucagon secretion have generated a flurry of research activity over the past 20 years culminating in a naturally occurring GLP-1 receptor (GLP-1R) agonist, exendin 4 (Ex-4), now being used to treat type 2 diabetes mellitus (T2DM). GLP-1 engages a specific guanine nucleotide-binding protein (G-protein) coupled receptor (GPCR) that is present in tissues other than the pancreas (brain, kidney, lung, heart, and major blood vessels). The most widely studied cell activated by GLP-1 is the insulin-secreting beta cell where its defining action is augmentation of glucose-induced insulin secretion. Upon GLP-1R activation, adenylyl cyclase (AC) is activated and cAMP is generated, leading, in turn, to cAMP-dependent activation of second messenger pathways, such as the protein kinase A (PKA) and Epac pathways. As well as short-term effects of enhancing glucose-induced insulin secretion, continuous GLP-1R activation also increases insulin synthesis, beta cell proliferation, and neogenesis. Although these latter effects cannot be currently monitored in humans, there are substantial improvements in glucose tolerance and increases in both first phase and plateau phase insulin secretory responses in T2DM patients treated with Ex-4. This review will focus on the effects resulting from GLP-1R activation in the pancreas.",1
"Doyle, Máire E, Egan, Josephine M",2
"SET-CAN, the product of the t(9;9) in acute undifferentiated leukemia, causes expansion of early hematopoietic progenitors and hyperproliferation of stomach mucosa in transgenic mice.",0
"Leukemia-specific chromosome translocations involving the nucleoporin CAN/NUP214 lead to expression of different fusion genes including DEK-CAN, CAN-ABL, and SET-CAN. DEK-CAN and CAN-ABL1 are associated with acute myeloid leukemia and T-cell acute lymphoblastic leukemia, respectively, whereas SET-CAN was identified in a patient with acute undifferentiated leukemia. In addition, SET is overexpressed in solid tumors of the breast, uterus, stomach, and rectum. Ectopic expression of SET-CAN inhibits vitamin-D(3)-induced differentiation of the human promonocytic U937cells, whereas ectopic SET expression induces differentiation. Here, we assessed the leukemogenic potential of SET-CAN in the hematopoietic system of transgenic mice. Although SET-CAN mice showed expansion of an early progenitor cell pool and partial depletion of lymphocytes, the animals were not leukemia-prone and did not show shortening of disease latency after retroviral tagging. This suggests that SET-CAN expression in acute undifferentiated leukemia might determine the primitive phenotype of the disease, whereas secondary genetic lesions are necessary for disease development. Surprisingly, SET-CAN mice developed spontaneous hyperplasia of the stomach mucosa, which coincided with overexpression of beta-catenin and vastly increased numbers of proliferating gastric mucosa cells, suggesting a role of SET-CAN in proliferation of certain epithelial cells.",1
"Ozbek, Ugur, Kandilci, Ayten, van Baal, Sjozef, Bonten, Jacqueline, Boyd, Kelli, Franken, Patrick, Fodde, Riccardo, Grosveld, Gerard C",2
Epithelial cell adhesion molecule: more than a carcinoma marker and adhesion molecule.,0
"The epithelial cell adhesion molecule (EpCAM, CD326) is a glycoprotein of approximately 40 kd that was originally identified as a marker for carcinoma, attributable to its high expression on rapidly proliferating tumors of epithelial origin. Normal epithelia express EpCAM at a variable but generally lower level than carcinoma cells. In early studies, EpCAM was proposed to be a cell-cell adhesion molecule. However, recent insights revealed a more versatile role for EpCAM that is not limited only to cell adhesion but includes diverse processes such as signaling, cell migration, proliferation, and differentiation. Cell surface expression of EpCAM may actually prevent cell-cell adhesion. Here, we provide a comprehensive review of the current knowledge on EpCAM biology in relation to other cell adhesion molecules. We discuss the implications of the newly identified functions of EpCAM in view of its prognostic relevance in carcinoma, inflammatory pathophysiology, and tissue development and regeneration as well as its role in normal epithelial homeostasis.",1
"Trzpis, Monika, McLaughlin, Pamela M J, de Leij, Lou M F H, Harmsen, Martin C",2
Doppel induces degeneration of cerebellar Purkinje cells independently of Bax.,0
"Doppel (Dpl) is a prion protein paralog that causes neurodegeneration when expressed ectopically in the brain. To investigate the cellular mechanism underlying this effect, we analyzed Dpl-expressing transgenic mice in which the gene for the proapoptotic protein Bax had been deleted. We found that Bax deletion does not alter either clinical symptoms or Purkinje cell degeneration in Dpl transgenic mice. In addition, we observed that degenerating Purkinje cells in these animals do not display DNA fragmentation or caspase-3 activation. Our results suggest that non-Bax-dependent pathways mediate the toxic effects of Dpl in Purkinje cells, highlighting a possible role for nonapoptotic mechanisms in the death of these neurons.",1
"Dong, Jiaxin, Li, Aimin, Yamaguchi, Naohiro, Sakaguchi, Suehiro, Harris, David A",2
Interferon-gamma induces chronic active myocarditis and cardiomyopathy in transgenic mice.,0
"Chronic heart failure is associated with an activation of the immune system characterized among other factors by the cardiac synthesis and serum expression of proinflammatory cytokines. There is unequivocal clinical and experimental evidence that the cytokine tumor necrosis factor-alpha is involved in the development of chronic heart failure, but a putative cardiotoxic potential of the proinflammatory cytokine interferon (IFN)-gamma remains primarily unknown. To investigate this issue we analyzed the cardiac phenotype of SAP-IFN-gamma transgenic mice, which constitutively express IFN-gamma in their livers and hence exhibit high circulating serum levels of this cytokine. SAP-IFN-gamma mice spontaneously developed chronic active myocarditis, characterized by the infiltration of not only CD4(+) and CD8(+) T cells but also Mac2(+) (galectin 3(+)) macrophages and CD11c(+) dendritic cells, eventually culminating in cardiomyopathy. Echocardiographic analyses exhibited a left ventricular dilation and impaired systolic function induced by IFN-gamma overexpression. IFN-gamma-mediated cardiotoxicity was associated with high-level cardiac transcription of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-12 and the macrophage-attracting chemokines MCP1 and MIP1-alpha. Myotoxic IFN-gamma effects could not be detected in smooth or striated muscle tissue, suggesting cardiomyocellular specificity of the toxic IFN-gamma effect. The precise mechanism of IFN-gamma cardiotoxicity remains to be elucidated.",1
"Reifenberg, Kurt, Lehr, Hans-Anton, Torzewski, Michael, Steige, Gisela, Wiese, Elena, Küpper, Ines, Becker, Christoph, Ott, Sibylle, Nusser, Petra, Yamamura, Ken-Ichi, Rechtsteiner, Gerd, Warger, Tobias, Pautz, Andrea, Kleinert, Hartmut, Schmidt, Albrecht, Pieske, Burkert, Wenzel, Philip, Münzel, Thomas, Löhler, Jürgen",2
Complex regulation of pulmonary inflammation and fibrosis by CCL18.,0
"Elevated pulmonary levels of CCL18 have been associated with influx of T lymphocytes, collagen accumulation, and a decline in lung function in pulmonary fibrosis patients. We previously reported that overexpression of CCL18 in mouse lungs triggers selective infiltration of T lymphocytes and moderate lymphocyte-dependent collagen accumulation. We hypothesized that in combination with bleomycin injury, overexpression of CCL18 will worsen the severity of lung inflammation and fibrosis. Mice were infected with a replication-deficient adenovirus encoding CCL18 and then instilled with bleomycin; control mice were challenged with either CCL18 overexpression or bleomycin. Additive effects of CCL18 overexpression and bleomycin injury were observed on pulmonary inflammation, particularly on T-cell infiltration, and increased levels of tumor necrosis factor-alpha, interferon-gamma, matrix metalloproteinase (MMP)-2, and MMP-9. Despite the additive effect on inflammation, CCL18 overexpression unexpectedly attenuated the bleomycin-induced collagen accumulation. Pulmonary levels of active transforming growth factor-beta1 mirrored the changes in collagen levels. Depletion of T cells with antilymphocyte serum or pharmacological inhibition of MMPs with GM6001 abrogated accumulation of collagen and increases in the levels of tumor necrosis factor-alpha, interferon-gamma, and active transforming growth factor-beta1. Thus, CCL18-stimulated T-lymphocytic infiltration is by itself mildly profibrotic to a healthy lung, whereas it partially protects against lung fibrosis in an inflammatory profibrotic pulmonary milieu.",1
"Pochetuhen, Kerill, Luzina, Irina G, Lockatell, Virginia, Choi, Jung, Todd, Nevins W, Atamas, Sergei P",2
Further characterization of ribosome binding to thylakoid membranes.,0
"Previous work indicated more polysomes bound to pea (Pisum sativum cv Progress No. 9) thylakoids in light than in the dark, in vivo (LE Fish, AT Jagendorf 1982 Plant Physiol 69: 814-825). With isolated intact chloroplasts incubated in darkness, addition of MgATP had no effect but 24 to 74% more RNA was thylakoid-bound at pH 8.3 than at pH 7. Thus, the major effect of light on ribosome-binding in vivo may be due to higher stroma pH. In isolated pea chloroplasts, initiation inhibitors (pactamycin and kanamycin) decreased the extent of RNA binding, and elongation inhibitors (lincomycin and streptomycin) increased it. Thus, cycling of ribosomes is controlled by translation, initiation, and termination. Bound RNA accounted for 19 to 24% of the total chloroplast RNA and the incorporation of [(3)H]leucine into thylakoids was proportional to the amount of this bound RNA. These data support the concept that stroma ribosomes are recruited into thylakoid polysomes, which are active in synthesizing thylakoid proteins.",1
"Hurewitz, J, Jagendorf, A T",2
Nitrate-induced changes in protein synthesis and translation of RNA in maize roots.,0
"Nitrate regulation of protein synthesis and RNA translation in maize (Zea mays L. var B73) roots was examined, using in vivo labeling with [(35)S]methionine and in vitro translation. Nitrate enhanced the synthesis of a 31 kilodalton membrane polypeptide which was localized in a fraction enriched in tonoplast and/or endoplasmic reticulum membrane vesicles. The nitrate-enhanced synthesis was correlated with an acceleration of net nitrate uptake by seedlings during initial exposure to nitrate. Nitrate did not consistently enhance protein synthesis in other membrane fractions. Synthesis of up to four soluble polypeptides (21, 40, 90, and 168 kilodaltons) was also enhanced by nitrate. The most consistent enhancement was that of the 40 kilodalton polypeptide. No consistent nitrate-induced changes were noted in the organellar fraction (14,000g pellet of root homogenates). When roots were treated with nitrate, the amount of [(35)S]methionine increased in six in vitro translation products (21, 24, 41, 56, 66, and 90 kilodaltons). Nitrate treatment did not enhance accumulation of label in translation products with a molecular weight of 31,000 (corresponding to the identified nitrate-inducible membrane polypeptide). Incubation of in vitro translation products with root membranes caused changes in the SDS-PAGE profiles in the vicinity of 31 kilodaltons. The results suggest that the nitrate-inducible, 31 kilodalton polypeptide from a fraction enriched in tonoplast and/or endoplasmic reticulum may be involved in regulating nitrate accumulation by maize roots.",1
"McClure, P R, Omholt, T E, Pace, G M, Bouthyette, P Y",2
Consequence of Absence of Nitrate Reductase Activity on Photosynthesis in Nicotiana plumbaginifolia Plants.,0
"Chlorate-resistant Nicotiana plumbaginifolia (cv Viviani) mutants were found to be deficient in the nitrate reductase apoprotein (NR(-)nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild-type Nicotiana tabacum plants. The grafts of mutant plants were chlorotic compared to the grafts of wild type. Mutant leaves did not accumulate nitrogen and nitrate but contained less malate and more glutamine than wild leaves. They exhibited a slight increase of the proportion of the light-harvesting chlorophyll a/b protein complexes and a lowering of the efficiency of energy transfer between these complexes and the active centers. After a 3 second (14)CO(2) pulse, the total (14)C incorporation of the mutant leaves was approximately 20% of that of the control. The (14)C was essentially recovered in ribulose bisphosphate in these plants. It was consistent with a decline of ribulose bisphosphate carboxylase activity observed in the mutant. After a 3 second (14)CO(2) pulse followed by a 60 second chase with normal CO(2), (14)C was mainly accumulated in starch which was labeled more in the mutant than in the wild type. These results confirm the observation that in the nitrate reductase deficient leaves, chloroplasts were loaded with large starch inclusions preceding disorganization of the photosynthetic apparatus.",1
"Saux, C, Lemoine, Y, Marion-Poll, A, Valadier, M H, Deng, M, Morot-Gaudry, J F",2
Compositional and Thermal Properties of Thylakoid Polar Lipids of Nerium oleander L. in Relation to Chilling Sensitivity.,0
"The polar lipid classes from thylakoids of Nerium oleander L. were studied with the aim of relating changes in their composition and thermal behavior with reported changes in the transition temperature of their polar lipids and chilling sensitivity of their leaves. With an increase in growth temperature, the transition temperature of phosphatidylglycerol increased from 16 degrees C to 26 degrees C, and for sulfoquinovosyldiacylglycerol from 19 degrees C to 24 degrees C. Transitions in the other lipid classes were below -10 degrees C for plants grown at both growth temperature. The major changes in the molecular species of phosphatidylglycerol, with increasing growth temperature, were an increase in 1-oleoyl-2-palmitoyl phosphatidylglycerol from 21 to 39% and a decrease in 1-oleoyl-2-trans-3-hexadecanoic phosphatidylglycerol from 51 to 25%. Although the disaturated species increased from 8 to 23%, the maximum was less than that reported for chilling-sensitive plants. There was no change in the sum of the palmitic, hexadeca-trans-3-enoic and stearic acids. Dipalmitoyl sulfoquinovosyldiacylglycerol increased from 12 to 20% and 1-linolenoyl-2-palmitoyl sulfoquinovosyldiacylglycerol decreased from 40 to 30%. It is concluded that the increase in the transition temperature of the polar lipids and the sensitivity of acclimated oleander plants to chilling could not be predicted by the absolute sum of the saturated fatty acids or disaturated molecular species in phosphatidylglycerol. The polar lipid transition appears to be a product of mixing of both high and low melting-point lipids.",1
"Orr, G R, Raison, J K",2
Characterization of the Proteinase that Initiates the Degradation of the Trypsin Inhibitor in Germinating Mung Beans (Vigna radiata).,0
"The proteinase (proteinase F) responsible for the initial proteolysis of the mung bean (Vigna radiata) trypsin inhibitor (MBTI) during germination has been purified 1400-fold from dry beans. The enzyme acts as an endopeptidase, cleaving the native inhibitor, MBTI-F, to produce the first modified inhibitor form, MBTI-E. The cleavage of the Asp76-Lys77 peptide bond of MBTI-F occurs at a pH optimum of 4.5, with the tetrapeptide Lys-Asp-Asp-Asp being released. Proteinase F exhibited no activity against the modified inhibitor forms MBTI-E and MBTI-C. Vicilin, the major storage protein of the mung bean, does not serve as a substrate for proteinase F between pH 4 and 7. Proteinase F is inhibited by phenylmethylsulfonyl fluoride, chymostatin, p-hydroxymercuribenzoate, and p-chlorophenylsulfonate, but not by iodoacetate and CuCl(2). It is not activated by dithiothreitol, and is stable for extended periods of time (10 months, 4 degrees C, pH 4.0) in the absence of reducing agents. An apparent molecular weight of 65,000 was found for proteinase F by gel filtration. Subcellular fractionation in glycerol suggests that greater than 85% of the proteinase F activity is found in the protein bodies of the ungerminated mung bean. The same studies indicate that at least 56% of the MBTI of the seed is also localized in the protein bodies.",1
"Wilson, K A, Tan-Wilson, A L",2
Specific peroxidase isoenzymes are correlated with organogenesis.,0
"We have examined isoperoxidase patterns obtained from buffer-, salt-, and enzyme-extractable fractions and correlated them with histological changes in tobacco (Nicotiana tabacum L., cv Wisc. 38) ;epidermal' explants induced to produce either callus, vegetative buds, or floral buds. By utilizing a combination of extraction and electrophoretic procedures different from any hitherto used for this kind of investigation, we were able to resolve 47 isoperoxidases distributed between the three types of fractions. The majority of these isoperoxidases were common to all explants regardless of their developmental fate. Correspondingly, a number of histological changes were observed in all explants (e.g. the initiation of cell division by day 2, lignin deposition by day 4, and the formation of clustered tracheary elements by day 8). We have made correlations between 25 isoperoxidases and specific developmental events based on the time when certain isoperoxidases were detected relative to observed histological changes: 3 were correlated with desuppressed/sustained cell division, 3 to 6 with lignification/tracheary element maturation, 7 with callus formation, 1 with localized suppression of growth, 3 with determinate axial organization, 4 with leaf development, and 1 with stamen development. These results suggest that a continued investigation using this system could lead to a better understanding of the role of specific isoperoxidases in different developmental processes.",1
"Kay, L E, Basile, D V",2
"Fructose 2,6-bisphosphate and plant carbohydrate metabolism.",0
"The control of the fructose 2,6-bisphosphate (Fru2,6P(2)) concentration and its possible role in controlling carbohydrate synthesis and degradation are discussed. This regulator metabolite is involved in the fine tuning of photosynthetic metabolism, and in controlling photosynthetic partitioning, and may also be involved in the response to hormones, wounding, and changing water relations. Study of the mechanisms controlling Fru2,6P(2) concentrations could reveal insights into how these responses are mediated. However, the detailed action of Fru2,6P(2) requires more attention, especially in respiratory metabolism where the background information about the compartmentation of metabolism between the plastid and cytosol is still inadequate, and the potential role of pyrophosphate has to be clarified.",1
"Stitt, M",2
Effect of Ear Removal on CO(2) Exchange and Activities of Ribulose Bisphosphate Carboxylase/Oxygenase and Phosphoenolpyruvate Carboxylase of Maize Hybrids and Inbred Lines.,0
"The effects of ear removal on gas exchange traits, chlorophyll, and leaf N profiles, and activities of ribulose 1,5-bisphosphate carboxylase/oxygenase and phosphoenolpyruvate carboxylase were examined using four maize hybrids (B73 x Mo17, B73 x LH38, FS854, and CB59G x LH38) and four inbred lines (B73, Mo17, LH38, and CB59G) as experimental material. A diverse genotypic response to ear removal was observed which was generally typified by (a) greatly accelerated loss of chlorophyll, leaf N, enzyme activities, and CO(2) exchange relative to controls for B73, B73 x Mo17, and B73 x LH38, (b) intermediate rate of decline for leaf constituents for FS854, LH38, and Mo17, or (c) loss of leaf constituents at similar or slower rates than for control plants for CB59G and CB59G x LH38. For all genotypes which had accelerated senescence relative to controls, loss of CO(2) exchange activity was correlated with increased internal CO(2) concentrations. Thus, it was concluded that metabolic factors and not stomatal effects were responsible for loss of CO(2) exchange activity. Loss of chlorophyll, leaf N, and enzyme activities correlated well with loss of CO(2) exchange activity only for some of the genotypes. Accelerated leaf senescence in response to ear removal for the inbred line B73 and the hybrids B73 x Mo17 and B73 x LH38, as well as the apparent delayed leaf senescence for the inbred line CB59G and the hybrid CB59G x LH38 show that the contrasting responses to ear removal, rapid versus delayed senescence, can be transmitted as dominant traits to F(1) hybrids. The intermediate response by some genotypes, and the dominance of contrasting senescence traits, suggested a relatively complex inheritance for expression of the ear removal response.",1
"Crafts-Brandner, S J, Poneleit, C G",2
Phytochrome Chromophore Biosynthesis : Both 5-Aminolevulinic Acid and Biliverdin Overcome Inhibition by Gabaculine in Etiolated Avena sativa L. Seedlings.,0
"Etiolated Avena sativa L. seedlings grown in the presence of gabaculine (5-amino-1,3-cyclohexadienylcarboxylic acid) contained reduced levels of phytochrome as shown by spectrophotometric and immunochemical assays. Photochromic phytochrome levels in gabaculine-grown plants were estimated to be 20% of control plants, while immunoblot analysis showed that the phytochrome protein moiety was present at approximately 50% of control levels. Gabaculine-grown seedlings administered either 5-aminolevulinic acid or biliverdin exhibited a rapid increase of spectrophotometrically detectable phytochrome. Phytochrome concentrations estimated immunochemically did not similarly increase throughout treatment with either compound. Similar experiments with 5-amino[4-(14)C] levulinic acid showed radiolabeling of phytochrome with kinetics that paralleled the spectrally detected increase. These results are consistent with (a) the intermediacy of both 5-aminolevulinic acid and biliverdin in the biosynthetic pathway of the phytochrome chromophore and (b) the lack of coordinate regulation of chromophore and apoprotein synthesis in Avena seedlings.",1
"Elich, T D, Lagarias, J C",2
"Transport and Compartmentation of 1-Aminocyclopropane-1-Carboxylic Acid and Its Structural Analog, alpha-Aminoisobutyric Acid, in Tomato Pericarp Slices.",0
"The uptakes of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor to ethylene, and its structural analog, alpha-aminoisobutyric acid (alphaAIB) by tomato pericarp slices were investigated. Both uptakes show a biphasic (saturable-linear) dependence on external concentration of the transported amino acid. At low concentrations, ACC uptake is competitively inhibited by alphaAIB and vice versa. Both uptakes also are inhibited by other neutral amino acids but not by acidic or basic amino acids. ACC and alphaAIB uptakes are metabolically dependent and are increased with time of tissue incubation. alphaAIB efflux patterns from pericarp slices indicated three distinct alphaAIB compartments having efflux kinetics consistent with those for cell wall, cytoplasm, and vacuole. The bulk of the alphaAIB taken up by pericarp tissue is sequestered into the vacuole. The ability of pericarp tissue to accumulate alphaAIB in the vacuole declines with fruit development.",1
"Saftner, R A, Baker, J E",2
A role for ca in the elicitation of rishitin and lubimin accumulation in potato tuber tissue.,0
"Calcium and strontium ions enhanced rishitin but not lubimin accumulation in tuber tissue of potato (Solanum tuberosum cv Kennebec) treated with arachidonic acid (AA). The same cations in the presence of poly-l-lysine (PL) enhanced the accumulation of lubimin more than rishitin. In contrast, Mg(2+) did not affect AA-elicited rishitin and lubimin accumulation and inhibited the accumulation of these compounds following application of PL. AA-elicited potato tuber tissue remained sensitive to the stimulatory effects of Ca(2+) and Sr(2+) up to 24 h after application of AA, but PL-elicited tuber tissue was sensitive to Ca(2+) and Sr(2+) for only 6 hours after PL application. Ethyleneglycol-bis (beta-aminoethyl ether)-N,N'-tetraacetic acid and La(3+) both inhibited rishitin and lubimin accumulation elicited by AA. The inhibition by either agent was overcome by the addition of Ca(2+). Calcium was more effective in overcoming lanthanum inhibition when applied simultaneously than when applied 12 hours later. Lanthanum was only effective in inhibiting rishitin and lubimin accumulation when applied within 3 hours of the application of AA. Inhibition of phytoalexin accumulation was greater when La(3+) was applied simultaneously with AA compared to La(3+) application after AA application to discs. These observations suggest that the mobilization of calcium may play a central regulatory role in the expression of phytoalexin accumulation following elicitation in potato tissue.",1
"Zook, M N, Rush, J S, Kuć, J A",2
Influence of light on the ferredoxin-dependent glutamate synthase in maize leaves.,0
The ferredoxin (Fd)-dependent glutamate synthase (EC 1.4.7.1) and NADH-dependent glutamate synthase (EC 1.4.1.14) activities are carried out by two immunochemically distinct enzyme proteins in maize leaves (Zea mays W64A and W182E). Continuous irradiation of etiolated tissue at 75 micro einsteins per square meter per second for 24 hours resulted in a 3-fold increase on a fresh weight basis in the activity of the Fd-dependent glutamate synthase and a slight decrease in the activity of the NADH-dependent enzyme. There was also a significant increase of the Fd-glutamate synthase protein during greening of etiolated tissue.,1
"Suzuki, A, Audet, C, Oaks, A",2
Relationship between Respiration and CAM-Cycling in Peperomia camptotricha.,0
Mature leaves of well-watered Peperomia camptotricha show Crassulacean acid metabolism (CAM). Young leaves show CAM-cycling in which CO(2) uptake occurs during the day concomitant with a marked diurnal fluctuation of organic acids as in CAM. Evidence is presented suggesting that respiration is the source of CO(2) for nocturnal acid synthesis in leaves exhibiting CAM-cycling. Respiratory quotients for these leaves were consistently much less than unity despite the fact that the leaves metabolize starch. The conservation of CO(2) by refixation into acids at night represents about 17% of the total photosynthetically fixed CO(2) and about 50% of the total respiratory CO(2).,1
"Patel, A, Ting, I P",2
Use of a light-induced respiratory transient to measure the optical cross section of photosystem I in chlorella.,0
"A method has been developed whereby the magnitude of a transient in O(2) uptake attributable to photosystem (PS) I activity, following single-turnover laser flashes of varying energy, can be used to measure the optical cross section of PSI. As measurements are made under the identical physiological conditions for which the cross section of PSII has previously been determined (AC Ley, DC Mauzerall 1982 Biochim Biophys Acta 680: 96-105), it is now possible to simultaneously measure the cross section of both photosystems in intact, photosynthetically competent cells, without the use of inhibitors or artificial mediators of electron transport. Plots of light-saturation behavior of the respiratory oscillation following pulses at 596 nanometers indicate a mean optical cross section similar to that of PSII at this wavelength, but suggest significant heterogeneity in the cross section of PSI. If this method measures only PSI activity, this result implies that there exist units with different numbers of identical chromophores, or units having populations of chromophores with different absorption spectra.",1
"Greenbaum, N L, Ley, A C, Mauzerall, D C",2
Boron stem infusions stimulate soybean yield by increasing pods on lateral branches.,0
"Studies were carried out to determine if supplemental B (H(3)BO(3)) and Ca (CaCl(2)) injected via a stem infusion technique into soybeans could stimulate yield by increasing pods on lateral branches, seed number, and overall seed yield. Boron treatments caused a significant 84.8% increase in the number of lateral pods/plant and a 17.6% increase in total seed weight/plant. This corresponded to a seed yield of 4170 kilograms per hectare in the B-treated plants compared to 3540 kilograms per hectare in the injected control plants, indicating that B deficiency may have been a factor in limiting yield of control plants. Ca treatments tended to accentuate the negative yield effects of apparent B deficiency.",1
"Schon, M K, Blevins, D G",2
Comparison of tissue preparation methods for assay of nicotinamide coenzymes.,0
"To prepare tissues for analysis of NAD(+), NADH, NADP(+), and NADPH, common practice is to freeze samples in liquid nitrogen, often followed by freeze-drying, before extraction in HCl or NaOH. With cucumber (Cucumis sativus L.) cotyledons, prefreezing in liquid nitrogen or slower freezing to -20 degrees C yielded substantially lower values for NADH and NADPH than obtained from samples homogenized immediately in acid or base. Freeze-drying after freezing in liquid nitrogen generally caused even lower values of those coenzymes. We suggest that direct extraction is more likely to yield accurate results with cotyledons and other plant parts.",1
"Zhao, Z, Hu, X, Ross, C W",2
Drought-Induced Changes in Protein Patterns of Brassica napus var. oleifera Roots.,0
"Drought-induced changes in two-dimensional silver stained protein patterns of Brassica napus L. var. oleifera M. root system were detected both at quantitative and qualitative levels. Particularly, 13 new polypeptides of low molecular weight were evidenced in the drought-stressed tap root, 12 of which were also present in the short tuberized roots, a specific drought-induced root type. The reversibility of these modifications, observed after 3 days rehydration, suggests that they might be involved in drought tolerance.",1
"Vartanian, N, Damerval, C, de Vienne, D",2
Transport Properties of the Tomato Fruit Tonoplast : II. Citrate Transport.,0
"Citrate transport across the membrane of tomato fruit tonoplast vesicles was investigated. In the tonoplast vesicles, [(14)C]methylamine uptake was stimulated 10-fold by MgATP and strongly inhibited by NO(3) (-). Under identical experimental conditions, [(14)C]citrate uptake was inhibited by 5 millimolar free Mg(2+), and this inhibition was reversed in the presence of ATP, presumably by ATP chelation of free Mg(2+). No evidence was obtained in support of energy-linked ATP stimulation of citrate uptake. Citrate uptake showed saturation kinetics, and was inhibited by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid and by other organic acids. The pH-dependence of uptake suggested that citrate(3-) was the transported species. Our results indicate that citrate transport across the tomato fruit tonoplast occurs by facilitated diffusion of citrate(3-). The carrier shares some features in common with anion channels in that it is relatively nonspecific for organic acids and is inhibitable by 4,4'-diisothyocyano-2,2'-stilbenedisulfonic acid.",1
"Oleski, N, Mahdavi, P, Bennett, A B",2
Isolation and Characterization of ABA-Insensitive Cell Lines of Carrot.,0
"While abscisic acid (ABA) exerts multiple effects on somatic embryogenesis, the most pronounced of these effects is the arrestment of torpedo-stage embryos, preventing them from developing into plantlets. In order to understand the mechanism of ABA inhibition of plantlet formation, we have isolated seven ABA-insensitive cell lines capable of developing into plantlets in the presence of ABA. These ABA-insensitive cell lines, whose frequency of appearance is 7 x 10(-6), have been isolated from a haploid cell line of Daucus carota L. var Juwarot. Surprisingly, all seven cell lines exhibit auxin insensitivity as evidenced by their ability to produce heart-stage embryos in various auxins including 2,4-dichlorophenoxyacetic acid (2,4-D), naphthalene acetic acid, and indolacetic acid. Three of the cell lines, ABA 1, ABA 15, and ABA 17, have been further characterized. We found that all three showed lower levels of ABA uptake which may be the cause of ABA insensitivity. However, the uptake of 2,4-D is higher in the three cell lines than in the wild type. The basis of the interaction between ABA and 2,4-D responses is discussed.",1
"Borkird, C, Sung, Z R",2
"Rapid phytochrome regulation of wheat seedling extension: light pretreatment extends coupling time, increases response lag, and decreases light sensitivity.",0
"Rapid effects of light on wheat seedling extension growth were monitored by sensitive transducer techniques. Seedlings grown in complete darkness responded to light by a marked deceleration of extension growth after a mean latent period of 10.4 minutes. Pulses (5 minutes) of red (660 nanometers), green (530 nanometers), and far-red (730 nanometers) light caused marked extension rate depression, and the red effect could not be reversed by 730 nanometers far-red. Pulses of 1 second red (72 micromoles per square meter) were effective, and were reversible by immediate long wavelength (759 nanometers) far-red. Seedlings pretreated with 2 minute broadband green light (0.6 micromole per square meter), 28 hours prior to the experimental light treatments, displayed similar extension rate decelerations in response to red light, but after a longer mean lag of 23.75 minutes. No response was observed with red light treatments of less than 1 minute, and the effects of 5 minutes of red light were fully reversible by 5 minutes of 730 nanometers far-red. Fluence-response curves showed that nonpretreated seedlings were approximately 100 times more sensitive to far-red-absorbing form of phytochrome than were those given prior light treatment. Although the fluence-response relationship for nonpretreated seedlings matched the photoconversion kinetics of phytochrome reasonably well, that for the pretreated seedlings indicated a requirement for repeated photoconversions for maximum action. The results are discussed in relation to the possibility that phytochrome may regulate the availability, or the activity, of a component of its own transduction chain.",1
"Smith, H, Jackson, G M",2
High-temperature sensitivity and its acclimation for photosynthetic electron transport reactions of desert succulents.,0
"Photosynthetic electron transport reactions of succulent plants from hot deserts are able to tolerate extremely high temperatures and to acclimate to seasonal increases in temperature. In this study, we report the influence of relatively long, in vivo, high-temperature treatments on electron transport reactions for two desert succulents, Agave deserti and Opuntia ficus-indica, species which can tolerate 60 degrees C. Whole chain electron transport averaged 3 degrees C more sensitive to a 1-hour high-temperature treatment than did PSII (Photosystem II) which in turn averaged 3 degrees C more sensitive than did PSI. For plants maintained at day/night air temperatures of 30 degrees C/20 degrees C, treatment at 50 degrees C caused these reactions to be inhibited an average of 39% during the first hour, an additional 31% during the next 4 hours, and 100% by 12 hours. Upon shifting the plants from 30 degrees C/20 degrees C to 45 degrees C/35 degrees C, the high temperatures where activity was inhibited 50% increased 3 degrees C to 8 degrees C for the three electron transport reactions, the half-times for acclimation averaging 5 days for A. deserti and 4 days for O. ficus-indica. For the 45 degrees C/35 degrees C plants treated at 60 degrees C for 1 hour, PSI activity was reduced by 54% for A. deserti and 36% for O. ficus-indica. Acclimation leads to a toleration of very high temperatures without substantial disruption of electron transport for these desert succulents, facilitating their survival in hot deserts. Indeed, the electron transport reactions of these species tolerate longer periods at higher temperatures than any other vascular plant so far reported.",1
"Chetti, M B, Nobel, P S",2
Regulation of Phosphoenolpyruvate Carboxylase from Crassula argentea: Further Evidence on the Dimer-Tetramer Interconversion.,0
"Phosphoenolpyruvate carboxylase in Crassulacean acid metabolism plants during the day exists in dimeric form the activity of which is strongly inhibited by malate. Enzyme purified from Crassula leaves collected during the day and stored at -70 degrees C for 49 days shows a steady progression of change from dimer to tetramer, and this change in oligomeric state is accompanied by a decrease in the sensitivity of the enzyme to inhibition by malate. At 10 minutes preincubation of enzyme after 11 days storage-which is composed of an equilibrium mixture of dimer and tetramer-with malate causes most of the enzyme to be converted to dimer and increases the sensitivity of the enzyme to malate inhibition during assay. Preincubation with phosphoenolpyruvate shifts the equilibrium toward the tetrameric form and reduces the maximal inhibition produced by 5 millimolar malate to less than 20%. However, none of the treatments used resulted in shifting the oligomerization equilibrium completely in either direction. Thus the question of whether some covalent modification of the enzyme, such as phosphorylation, is required to permit complete changes in equilibrium remains open.",1
"Wu, M X, Wedding, R T",2
Influence of internal sugar levels on apoplasmic retrieval of exogenous sucrose in source leaf tissue.,0
"Sugar levels in Beta vulgaris leaves were increased by heat-girdling the petiole and returning the plant to the controlled-environment chamber for 10 and 34 hours. After 10 hours, sucrose influx into the treated leaves was similar to the controls, although sucrose levels increased from 2.1 to 5.3 micromoles per milligram chlorophyll. However, after a 34-hour treatment, sucrose levels increased from 2.1 to 11.5 micromoles per milligram chlorophyll. In this instance, sucrose influx decreased relative to the untreated controls. Decreasing sugar levels by DCMU treatment resulted in a small stimulation of sucrose influx. A similar DCMU treatment applied to leaves of Allium cepa also resulted in an increase in sucrose influx. However, in A. cepa we could not attribute this increase to a lowering of sugar levels, as the kinetic profiles obtained from control leaves did not vary from each other throughout the day, despite considerable changes in sugar levels. Additionally, it appeared that sucrose uptake in onion may be set at some point and remains invariant throughout the day. Similar studies were also conducted on discs cut from mature leaves of Spinacia oleracea var America. Between 1 and 8 hours after the onset of the photoperiod, the sucrose content of the spinach leaves increased from 2.6 to 9.3 micromoles per milligram chlorophyll. A comparison of the kinetic profiles obtained from leaf discs, taken at these times, indicated that sucrose uptake was not influenced by these changes in internal sugar levels. The relationship between the above findings and ;trans' inhibition of exogenous sucrose uptake is discussed. Although intermediate changes in sugar levels in sugar beet leaves did not appear to affect sucrose influx, autoradiographic studies revealed that these changes dramatically affected the partitioning of exogenously supplied [(14)C]sucrose. Our results indicate that while intermediate changes in internal sugar levels have little effect on sucrose influx across the plasmalemma, they may dramatically affect partitioning between the phloem and the mesophyll vacuole.",1
"Wilson, C, Lucas, W J",2
Influence of chloroplast development on the activation of the diphenyl ether herbicide acifluorfen-methyl.,0
"The activity of acifluorfen-methyl (AFM); methyl 5-(2-chloro-4-[trifluoromethyl] phenoxy)-2-nitrobenzoate in excised cucumber cotyledons (Cucumis sativus L.) was examined. AFM induced membrane disruption, was significantly greater when etiolated cotyledons were illuminated 16 hours at 150 microeinsteins per square meter per second photosynthetically active radiation versus incubation under illumination of 4-fold greater intensity. These results were unexpected since the loss of membrane integrity is initiated by photodynamic reactions. Untreated, etiolated cotyledons were not able to accumulate chlorophyll under the higher light intensity while control and herbicide treated cotyledons greened significantly under the lower intensity illumination suggesting that some process associated with greening stimulated AFM activity. Inhibition of greening by cycloheximide also reduced AFM activity. Intermittent lighting induced greening in AFM treated cotyledons without causing any detectable loss of plasmalemma integrity. Utilization of this system for pretreatment of cotyledons prior to continuous illumination revealed that activity was greater when tissue was greened in the presence of AFM than when herbicide treatments were made after a greening period of the same duration. The results indicate that the pigments in situ in etiolated tissue are sufficient, without greening, to initiate membrane disruption by AFM. However, greening increases the herbicidal efficacy greatly. Furthermore, the stimulation appears to be due to specific interactions between AFM and the developing plastid and is not attributable solely to an increase in endogenous photosensitizers.",1
"Halling, B P, Peters, G R",2
Gibberellin-mediated synergism of xylogenesis in lettuce pith cultures.,0
"Major gibberellins (GAs) in lettuce (Lactuca sativa L. cv Romaine) pith explants have been identified by gas chromatography-mass spectrometry (GC-MS) or GC-selected ion monitoring (GC-SIM) as GA(1), 3-epi-GA(1), GA(8), GA(19), and GA(20). Treatment of pith explants with indole-3-acetic acid (IAA) (57 micromolar) plus kinetic (0.5 micromolar) induced xylogenesis. In this xylogenic treatment, the concentration of a biologically active, polar GA-like substance(s) increased during the first 2 days of culture, although all of the above GAs decreased (as measured by GC-SIM). In non-xylogenic treatments, where explants were cultured without exogenous hormones, or with IAA or kinetin alone, the concentration of the biologically active, polar GA-like substance(s) decreased during the first two days of culture, as did all of the above GAs (as measured by GC-SIM). Treatment of pith explants with exogenous GA(1) alone did not induce xylogenesis, but GA(1) at very low concentrations (0.0014 and 0.003 micromolar) synergized xylogenesis in the IAA plus kinetin-treated cultures. These results suggest that changes in the concentration of certain endogenous GAs may be involved in xylogenesis mediated by IAA plus kinetin in lettuce pith cultures.",1
"Pearce, D, Miller, A R, Roberts, L W, Pharis, R P",2
Interaction of indoleacetic Acid with its inositol and glucoside conjugates in Avena coleoptile curvature.,0
"Avena coleoptile curvature is promoted by indoleacetic acid (IAA) IAA-glucoside, and IAA-inositol when these substances are applied in agar to the decapitated apical end of deseeded plantlets. Absorption of [(3)H]IAA-inositol over a wide range of concentrations during the 20 hour period of incubation is only 20 to 50% of the applied amount, compared with 85 to 92% of uptake of the applied [(3)H]IAA at equimolar concentrations. The absorption of IAA-glucoside could not be readily measured. The stimulation by both IAA-conjugates is very similar to that of free IAA at low concentrations (0.2 and 0.4 micromolar), but much less at higher concentrations. The interaction of free IAA with IAA-glucoside is additive or synergistic (depending on concentration). The interaction of free IAA with IAA-inositol is an inhibition (i.e. less than additive). The simultaneous application of equimolar concentrations of free IAA does not change the chromatographic pattern of the metabolic products of [(3)H] IAA-inositol. One of the more polar metabolites of [(3)H]IAA-inositol has chromatographic characteristics similar to the major polar metabolite of free [(3)H]IAA on an isocratically eluted reversed phase C(18) high performance liquid chromatography system that separates a number of IAA sugar and amino acid conjugates from each other, and from free IAA.",1
"Wodzicki, T J, Pharis, R P, Wodzicki, A B",2
Altered Gene Expression during Auxin-Induced Root Development from Excised Mung Bean Seedlings.,0
"Changes in the pattern of protein synthesis and in the translatable mRNA population have been examined during auxin-induced root development from excised mung bean seedlings. Several proteins, predominantly of low molecular weight and high pI, as shown by two-dimensional polyacrylamide gel electrophoresis, are synthesized specifically by auxin-treated tissue. These auxin-induced proteins appear between 6 and 12 hours of auxin treatment, reach a maximum at 24 hours, and decline at 48 hours. Untreated seedlings (placed in Hoagland solution), known to produce small number of roots at the cut end probably due to endogeneous auxin accumulated at the cut end through basipetal transport, show low level synthesis of auxin-specific proteins. Antiauxin treatment that completely inhibits auxin-induced rooting also prevents the appearance of auxin-induced proteins. The induction of a group of three to four proteins appears to be specific to antiauxin treatment. In vitro translation of mRNA from auxin-treated tissue, but not of mRNA from antiauxin-treated tissue, yields several polypeptides of low molecular weight and high pI. Since the auxin-induced proteins precede root development and are synthesized transitorily, it is likely that they play some regulatory role during the initiation of root development. The result show that auxin-induced root formation involves altered gene expression.",1
"Dhindsa, R S, Dong, G, Lalonde, L",2
Fluxes of h and k in corn roots : characterization and stoichiometries using ion-selective microelectrodes.,0
"We report here on an experimental system that utilizes ion-selective microelectrodes to measure the electrochemical potential gradients for H(+) and K(+) ions within the unstirred layer near the root surface of both intact 4-day-old corn seedlings and corn root segments. Analysis of the steady state H(+) and K(+) electrochemical potential gradients provided a simultaneous measure of the fluxes crossing a localized region of the root surface. Net K(+) influx values obtained by this method were compared with unidirectional K(+) ((86)Rb(+)) influx kinetic data; at any particular K(+) concentration, similar values were obtained by either technique. The ionspecific microelectrode system was then used to investigate the association between net H(+) efflux and net K(+) influx. Although the computed H(+):K(+) stoichiometry is dependent upon the choice of diffusion coefficients, the values obtained were extremely variable, and net K(+) influx rarely appeared to be charge-balanced by H(+) efflux. In contrast to earlier studies, we found the cortical membrane potential to be highly K(+) sensitive within the micromolar K(+) concentration range. Simultaneous measurements of membrane potential and K(+) influx, as a function of K(+) concentration, revealed similar K(m) values for the depolarization of the potential (K(m) 6-9 micromolar K(+)) and net K(+) influx (K(m) 4-7 micromolar K(+)). These data suggest that K(+) may enter corn roots via a K(+)-H(+) cotransport system rather than a K(+)/H(+) antiporter.",1
"Newman, I A, Kochian, L V, Grusak, M A, Lucas, W J",2
Factors affecting the level of kanamycin resistance in transformed sunflower cells.,0
"A 230 base pair DNA segment containing the sequences 5' to the 700 to 750 nucleotide (nt) transcript 7' (ORF 3; RF Barker, KB Idler, DV Thompson, JD Kemp 1983 Plant Mol Biol 2: 335-350) of the octopine tumor inducing plasmid pTiA6 has been isolated. This region has (a) 180 base pairs of DNA upstream of the TATA box, (b) the start of RNA synthesis, and (c) the entire 5' untranslated region of the gene. We have fused this presumed promoter fragment to the neomycin phosphotransferase II (NPTII) gene from Tn5 in a plant expression cassette. After recombination into a tumor inducing plasmid delivery plasmid, this cassette confers selectable kanamycin resistance to transformed sunflower cells. Removal of the out-of-frame ATG in the 5' leader sequence of the NPTII gene by two different modifications increased both the levels of NPTII enzyme activity and the ID(50) for kanamycin in the tumor cells. The promoter region of the transcript 7 gene gives levels of kanamycin resistance equivalent to the nopaline synthase promoter and octopine synthase promoter when used in the same constructions and assayed in the same tissues.",1
"Nutter, R, Everett, N, Pierce, D, Panganiban, L, Okubara, P, Lachmansingh, R, Mascarenhas, D, Welch, H, Mettler, I, Pomeroy, L, Johnson, J, Howard, J",2
Flavone limitations to root nodulation and symbiotic nitrogen fixation in alfalfa.,0
"Transcription of the nodABC genes in Rhizobium meliloti is required for root nodule formation in alfalfa (Medicago sativa L.) and occurs when specific compounds, such as the flavone luteolin, are supplied by the host plant. Results reported here indicate how luteolin in the root and rhizosphere can affect subsequent N(2) fixation and plant growth. Previous experiments with ;Hairy Peruvian 32' (HP32), an alfalfa population produced from ;Hairy Peruvian' (HP) by two generations of selection for increased N(2) fixation and growth, found that HP32 had more root nodules and fixed more N(2) than the parental HP population. In the present study, flavonoid extracts of HP32 seedling roots are shown to contain a 60% higher concentration of compounds that induce transcription of a nodABC-lacZ fusion in R. meliloti than comparable extracts of HP roots. Chromatographic data indicated that HP32 roots had a 77% higher concentration of luteolin than HP roots. Adding 10 micromolar luteolin to the rhizosphere of HP seedlings increased nodulation, N(2) fixation, total N, and total dry weight but had no effect on nitrate assimilation. These data show that normal levels of flavone nodulation signals in the rhizosphere of HP alfalfa can limit root nodulation, symbiotic N(2) fixation, and seedling growth and suggest that one mechanism for increasing N(2) fixation can be the genetic enhancement of specific biochemical signals which induce nodulation genes in Rhizobium.",1
"Kapulnik, Y, Joseph, C M, Phillips, D A",2
Intracellular localization of heat shock proteins in maize.,0
"The intracellular distribution of the maize root heat shock proteins (hsp) was studied as a step toward understanding their physiological function. Linear sucrose density centrifugation was employed to separate organelles so the relative quantities of hsp in different subcellular compartments could be analyzed in a single preparation. Gradient fractions were assayed for the presence of hsp by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and for marker enzyme activities. Analyses of 15 to 60% gradients showed five hsp to be organelle associated. Hsp 25 and 72 were in fractions containing closely equilibrating Golgi and endoplasmic reticulum marker activities, while hsp 18, 29, and 72 were in fractions containing overlapping plasma membrane, mitochondria, and glyoxysomal marker activities. Hsp larger than 72 kilodaltons were not present in gradient fractions. A second fractionation scheme achieved better separation of the two sets of closely equilibrating organelles. When a 13,000g centrifugation step to remove mitochondria was employed prior to gradient centrifugation, hsp 29 was absent from the gradient fractions. If the buoyant density of the endoplasmic reticulum was shifted by either maintaining the ribosomes on the membrane or removing them, a corresponding shift in the equilibrium positions of hsp 25 and 72 occurred. Hsp 18 and 70 remained in plasma membrane-containing fractions irrespective of these treatments.",1
"Cooper, P, Ho, T H",2
Alcohol Dehydrogenase and Pyruvate Decarboxylase Activity in Leaves and Roots of Eastern Cottonwood (Populus deltoides Bartr.) and Soybean (Glycine max L.).,0
"Pyruvate decarboxylase (PDC, EC 4.1.1.1) and alcohol dehydrogenase (ADH, EC 1.1.1.1) are responsible for the anaerobic production of acetaldehyde and ethanol in higher plants. In developing soybean embryos, ADH activity increased upon imbibition and then declined exponentially with development, and was undetectable in leaves by 30 days after imbibition. PDC was not detectable in soybean leaves. In contrast, ADH activity remained high in developing cottonwood seedlings, with no decline in activity during development. ADH activity in the first fully expanded leaf of cottonwood was 230 micromoles NADH oxidized per minute per gram dry weight, and increased with leaf age. Maximal PDC activity of cottonwood leaves was 10 micromoles NADH oxidized per minute per gram dry weight. ADH activity in cottonwood roots was induced by anaerobic stress, increasing from 58 to 205 micromoles NADH oxidized per minute per gram dry weight in intact plants in 48 hours, and from 38 to 246 micromoles NADH oxidized per minute per gram dry weight in detached roots in 48 hours. Leaf ADH activity increased by 10 to 20% on exposure to anaerobic conditions. Crude leaf enzyme extracts with high ADH activity reduced little or no NADH when other aldehydes, such as trans-2-hexenal, were provided as substrate. ADH and PDC are constitutive enzyme in cottonwood leaves, but their metabolic role is not known.",1
"Kimmerer, T W",2
Leaf magnesium alters photosynthetic response to low water potentials in sunflower.,0
"We grew sunflower (Helianthus annuus L.) plants in nutrient solutions having nutritionally adequate but low or high Mg(2+) concentrations and determined whether photosynthesis was effected as leaf water potentials (psi(w)) decreased. Leaf Mg contents were 3- to 4-fold higher in the plants grown in high Mg(2+) concentrations (10 millimolar) than in those grown in low concentrations (0.25 millimolar). These contents were sufficient to support maximum growth, plant dry weight, and photosynthesis, and the plants appeared normal. As low psi(w) developed, photosynthesis was inhibited but moreso in high Mg leaves than in low Mg leaves. The effect was particularly apparent under conditions of light- and CO(2)-saturation, indicating that the chloroplast capacity to fix CO(2) was altered. The differential inhibition observed in leaves of differing Mg contents was not observed in leaves having differing K contents, suggesting that the effect may have been specific for Mg. Because Mg(2+) inhibits photophosphorylation and coupling factor activities at concentrations likely to occur as leaves dehydrate, Mg may play a role in the inhibition of chloroplast reactions at low psi(w), especially in leaves such as sunflower that markedly decrease in water content as psi(w) decreases.",1
"Rao, I M, Sharp, R E, Boyer, J S",2
Photosynthesis by intact isolated chloroplasts on solid support.,0
"A new approach to measurements of photosynthesis by isolated chloroplasts has been devised. Intact isolated chloroplasts were trapped in the cavities of membrane filters. The thin layers of chloroplasts so obtained were assayed for O(2) evolution and CO(2) assimilation in leaf-chambers. Photosynthetic gas exchange could be demonstrated to take place either in a closed or a flow-through system. The chloroplasts were morphologically intact as shown by light or scanning electron microscopy and displayed stable rates of photosynthesis in the presence of phosphate and alkaline phosphatase. The methods described open the way to in vitro measurement of photosynthesis, by chloroplasts under conditions more closely resembling those in leaves.",1
"Cerovic, Z G, Cheesbrough, J K, Walker, D A",2
"Sucrose phosphatase associated with vacuole preparations from red beet, sugar beet, and immature sugarcane stem.",0
"The specific phosphatase, sucrose phosphate phosphohydrolase (sucrose phosphatase, EC 3.1.3.24) was present in vacuole preparations from storage tissue of red beet (Beta vulgaris L.), sugar beet (Beta vulgaris L. cultivar Kawemono), and immature sugarcane (Saccharum spp. hybrid, cultivar NCO 310). In red beet vacuole preparations the specific activity of sucrose phosphatase, using the naturally occurring vacuole marker, betanin, as reference, was higher than the specific activity of cytoplasmic markers, phosphoenolpyruvate carboxylase and glucose 6-phosphate dehydrogenase, suggesting that sucrose phosphatase is associated with the vacuoles. High speed centrifugation of lysed vacuoles did not result in precipitation of the enzyme indicating that the enzyme is not tightly bound to the tonoplast. Sucrose phosphatase was more sensitive to inhibition by sodium vanadate and less sensitive to ammonium molybdate than was the nonspecific phosphatase which was also present in the extracts. Sucrose phosphatase might be part of the group translocator proposed recently to operate in the tonoplast of sugarcane and red beet.",1
"Hawker, J S, Smith, G M, Phillips, H, Wiskich, J T",2
"Substrate Specificities of N-Acetylglucosaminyl-, Fucosyl-, and Xylosyltransferases that Modify Glycoproteins in the Golgi Apparatus of Bean Cotyledons.",0
"As part of their posttranslational maturation process, newly synthesized glycoproteins that contain N-linked oligosaccharide side chains pass through the Golgi apparatus, where some of their oligosaccharides become modified by carbohydrate processing reactions. In this paper, we report the presence of Golgi-localized enzymes in plant cells (Phaseolus vulgaris cotyledons) that transfer GlcNAc, fucosyl, and xylosyl residues to the oligosaccharide side chains of glycoproteins. All three enzyme activities are involved in the transformation of high mannose side chains into complex glycans. As judged by acceptor specificity studies, at least two GlcNAc residues can be added to the nonreducing side of high mannose oligosaccharides, which have been trimmed by alpha-mannosidase(s). A Man(5)(GlcNAc)(2)-peptide serves as the acceptor for the first GlcNAc added. The second GlcNAc can be added only after the prior removal of two additional mannose residues, ultimately yielding (GlcNAc)(2)Man(3)(GlcNAc)(2)-peptide. Fucosyltransferase can transfer fucose to GlcNAcMan(5)(GlcNAc)(2)Asn, GlcNAcMan(3)(GlcNAc)(2)Asn, and (GlcNAc)(2)Man(3)(GlcNAc)(2)Asn; xylosyltransferase exhibits significant activity toward the latter two substrates only. These results suggest an overlapping sequence of oligosaccharide modification in the Golgi apparatus that, in regard to GlcNAc and fucose additions, is analogous to pathways of oligosaccharide processing reported for animal cells. To our knowledge, this is the first report characterizing a xylosyltransferase involved in N-linked oligosaccharide modification, an activity that is apparently absent in most animal cells.",1
"Johnson, K D, Chrispeels, M J",2
Protein Synthesis in Bromegrass (Bromus inermis Leyss) Cultured Cells during the Induction of Frost Tolerance by Abscisic Acid or Low Temperature.,0
"Bromus inermis Leyss cell cultures treated with 75 micromolar abscisic acid (ABA) at both 23 and 3 degrees C developed more freezing resistance than cells cultured at 3 degrees C. Protein synthesis in cells induced to become freezing tolerant by ABA and low temperature was monitored by [(14)C]leucine incorporation. Protein synthesis continued at 3 degrees C, but net cell growth was stopped. Most of the major proteins detected at 23 degrees C were synthesized at 3 degrees C. However, some proteins were synthesized only at low temperatures, whereas others were inhibited. ABA showed similar effects on protein synthesis at both 23 and 3 degrees C. Comparative electrophoretic analysis of [(14)C]leucine labeled protein detected the synthesis of 19, 21 and 47 kilodalton proteins in less than 8 hours after exposure to exogenous ABA. Proteins in the 20 kilodalton range were also synthesized at 3 degrees C. In addition, a 31 kilodalton protein band showed increased expression in freezing resistant ABA treated cultures after 36 hours growth at both 3 and 23 degrees C. Quantitative analysis of [(14)C]leucine labeled polypeptides in two-dimensional gels confirmed the increased expression of the 31 kilodalton protein. Two-dimensional analysis also resolved a 72 kilodalton protein enriched in ABA treated cultures and identified three proteins (24.5, 47, and 48 kilodaltons) induced by low temperature growth.",1
"Robertson, A J, Gusta, L V, Reaney, M J, Ishikawa, M",2
Correlation between calmodulin activity and gravitropic sensitivity in primary roots of maize.,0
"Recent evidence indicates a role for calcium and calmodulin in the gravitropic response of primary roots of maize (Zea mays, L.).  We examined this possibility by testing the relationship between calmodulin activity and gravitropic sensitivity in roots of the maize cultivars Merit and B73 x Missouri 17.  Roots of the Merit cultivar require light to the gravitropically competent.  The gravitropic response of the Missouri cultivar is independent of light.  The occurrence of calmodulin in primary roots of these maize cultivars was tested by affinity gel chromatography followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with bovine brain calmodulin as standard.  The distribution of calmodulin activity was measured using both the phosphodiesterase and NAD kinase assays for calmodulin.  These assays were performed on whole tissue segments, crude extracts, and purified extracts.  In light-grown seedlings of the Merit cultivar or in either dark- or light-grown seedlings of the Missouri cultivar, calmodulin activity per millimeter of root tissue was about 4-fold higher in the apical millimeter than in the subtending 3 millimeters.  Calmodulin activity was very low in the apical millimeter of roots of dark-grown (gravitropically nonresponsive) seedlings of the Merit cultivar.  Upon illumination, the calmodulin activity in the apical millimeter increased to a level comparable to that of light-grown seedlings and the roots became gravitropically competent.  The time course of the development of gravitropic sensitivity following illumination paralleled the time course of the increase in calmodulin activity in the apical millimeter of the root.  The results are consistent with the suggestion that calmodulin plays an important role in the gravitropic response of roots.",1
"Stinemetz, C L, Kuzmanoff, K M, Evans, M L, Jarrett, H W, Evans, M L",2
Studies on genetic male-sterile soybeans : v. Effects of male-sterility on the function and glycerolipid composition of chloroplast thylakoids.,0
"Soybean (Glycine max L. Merr.) germplasm, isogenic except for loci controlling male sterility (ms(1)), was utilized to study the effects of reproductive development on certain aspects of photosynthesis. Plants were sampled at various times between flowering (77 days after transplanting) and maturity (147 days after transplanting). During that period photosynthetic rates declined more rapidly in the male-sterile genotypes than male-fertile genotypes; and after 105 days, the sterile genotypes maintained low but relatively constant carbon exchange rates. The decline of leaf photosynthesis in the male-sterile genotype occurred concomitantly with an inhibition of the photosynthetic electron transport chain associated with photosystem II. Changes in photosystem I activities, cytochrome f levels, and chlorophyll a/b ratios per se were not responsible for the decline in whole leaf photosynthesis. These conditions were independent of the source of nitrogen nutrition. Lipid analyses of the thylakoids revealed that a loss of phosphatidylglycerol was highly correlated with the inhibition of photosystem II activity. These results suggested a relation between the decline in leaf carbon exchange and the decline in photosynthetic electron transport activity.",1
"Burke, J J, Kalt-Torres, W, Burton, J W, Wilson, R F",2
Endogenous NO(3) in the Root as a Source of Substrate for Reduction in the Light.,0
"An experiment was conducted to investigate the reduction of endogenous NO(3) (-), which had been taken up by plants in darkness, during the course of the subsequent light period. Vegetative, nonnodulated soybean plants (Glycine max [L]. Merrill, ;Ransom') were exposed to 1.0 millimolar (15)NO(3) (-) for 12 hours in darkness and then returned to a solution containing 1.0 millimolar (14)NO(3) (-) for the 12 hours ;chase' period in the light. Another set of plants was exposed to (15)NO(3) (-) during the light period to allow a direct comparison of contributions of substrate from the endogenous and exogenous sources. At the end of the (15)NO(3) (-) exposure in the dark, 70% of the absorbed (15)NO(3) (-) remained unreduced, and 83% of this unreduced NO(3) (-) was retained in roots. The pool of endogenous (15)NO(3) (-) in roots was depleted at a steady rate during the initial 9 hours of light and was utilized almost exclusively in the formation of insoluble reduced-N in leaves. Unlabeled endogenous NO(3) (-), which had accumulated in the root prior to the previous dark period, also was depleted in the light. When exogenous (15)NO(3) (-) was supplied during the light period, the rate of assimilation progressively increased, reflecting an increased rate of uptake and decreased accumulation of NO(3) (-) in the root tissue. The dark-absorbed endogenous NO(3) (-) in the root was the primary source of substrate for whole-plant NO(3) (-) reduction in the first 6 hours of the light period, and exogenous NO(3) (-) was the primary source of substrate thereafter. It is concluded that retention of NO(3) (-) in roots in darkness and its release in the following light period is an important whole-plant regulatory mechanism which serves to coordinate delivery of substrate with the maximal potential for NO(3) (-) assimilation in photosynthetic tissues.",1
"Rufty, T W, Volk, R J, Mackown, C T",2
Ward pharmacy: a foundation for prescribing audit?,0
To determine the extent and nature of prescription monitoring incidents by hospital pharmacists and to derive a performance indicator to allow prescription monitoring to be compared among hospitals in North West Thames region.,1
"Batty, R, Barber, N",2
Evidence for validity of a health status measure in assessing short term outcomes of cholecystectomy.,0
To assess the validity of the Nottingham health profile (NHP) as an indicator of short term outcome of cholecystectomy.,1
"Bardsley, M J, Venables, C W, Watson, J, Goodfellow, J, Wright, P D",2
Improving management of asthma: closing the loop or progressing along the audit spiral?,0
To assess whether the management of asthma has improved from three consecutive surveys.,1
"Bucknall, C E, Robertson, C, Moran, F, Stevenson, R D",2
Clinical complaints and their handling: a time for change?,0
To assess the performance of the hospital complaints procedure for complaints proceeding to peer review and the quality of responses to complainants.,1
"Donaldson, L J, Cavanagh, J",2
Management of coeliac disease: a changing diagnostic approach but what value in follow up?,0
To assess the management of patients with coeliac disease in relation to a change in diagnostic method from jejunal suction biopsy to endoscopic biopsy.,1
"Acalovschi, M, Jayanthi, V, Probert, C S, Mayberry, J F",2
Use of an east end children's accident and emergency department for infants: a failure of primary health care?,0
To ascertain why parents use an accident and emergency department for health care for their infants.,1
"Bedford, H E, Jenkins, S M, Shore, C, Kenny, P A",2
Total joint replacement: implication of cancelled operations for hospital costs and waiting list management.,0
To identify aspects of provision of total joint replacements which could be improved.,1
"Mangan, J L, Walsh, C, Kernohan, W G, Murphy, J S, Mollan, R A, McMillen, R, Beverland, D E",2
Prospective audit comparing ambulatory day surgery with inpatient surgery for treating cataracts.,0
To compare the cost effectiveness and safety of inpatient cataract surgery (with one night in hospital postoperatively) with ambulatory day case surgery under local anaesthesia.,1
"Percival, S P, Setty, S S",2
Survey of outpatient sputum cytology: influence of written instructions on sample quality and who benefits from investigation.,0
To evaluated quality of outpatient sputum cytology and whether written instructions to patients improve sample quality and to identify variables that predict satisfactory samples.,1
"Tsang, K W, Bentley, A M, Mann, J S, Belcher, J, Pantin, C F",2
The nucleotide sequence of the large ribosomal RNA gene and the adjacent tRNA genes from rat mitochondria.,0
"We have sequenced the Eco R(1) fragment D from rat mitochondrial DNA. It contains one third of the tRNA (Val) gene (the remaining part has been sequenced from the 3' end of the Eco R(1) fragment A) the complete gene for the large mt 16S rRNA, the tRNA (Leu) gene and the 5' end of an unidentified reading frame. The mt gene for the large rRNA from rat has been aligned with the homologous genes from mouse and human using graphic computer programs. Hypervariable regions at the center of the molecule and highly conserved regions toward the 3' end have been detected. The mt gene for tRNA Leu is of the conventional type and its primary structure is highly conserved among mammals. The mt gene for tRNA(Val) shows characteristics similar to those of other mt tRNA genes but the degree of homology is lower. Comparative studies confirm that AGA and AGG are read as stop codons in mammalian mitochondria.",1
"Saccone, C, Cantatore, P, Gadaleta, G, Gallerani, R, Lanave, C, Pepe, G, Kroon, A M",2
Nucleotide sequence of the lexA gene of Escherichia coli K-12.,0
"A number of E. coli genes exhibit increased expression when the cellular DNA is damaged. In undamaged cells, lexA repressor limits the extent of their transcription, whereas, in damaged cells, the repressor is cleaved by a cellular protease, the product of the recA gene. We have sequenced 943 base pairs of cloned E. coli DNA containing the lexA gene. A regulatory region has been identified, followed by a translational open reading frame which encodes a polypeptide of 202 amino acids with a molecular weight of 22,300. The protein contains a single alanyl-glycyl peptide near its middle. This peptide is also found in certain phage repressors which are cleaved by the recA protease and has been shown to be the site of cleavage in these repressors. We have determined the nucleotide sequence of a portion of the lexA3 gene, whose product is 100-fold less susceptible to recA protease than the wild type repressor. We report a single base change (G to A) which alters the unique alanine-glycine sequence to alanine-aspartic acid.",1
"Markham, B E, Little, J W, Mount, D W",2
An improved procedure for utilizing terminal transferase to add homopolymers to the 3' termini of DNA.,0
"Terminal deoxynucleotidyl transferase (E.C.2.7.7.3.1.) from calf thymus was used to add homopolymer tails to duplex DNA with 3' protruding, even, or 3' recessive ends. A gel electrophoresis method was employed to analyze the tail length and the percent of DNA with tails. In all the tailing reactions, dA, dT, and dC tails from CoCl2-containing buffer were longer than those from MnCl2 - or MgCl2 - containing buffers, whereas dG tails from MnCl2 -containing buffer were the longest. By varying the ratio of dNTP over DNA terminus and the concentration of terminal transferase, optimal conditions were found for adding dG or dC tails of 10-25 nucleotides in length and dA and dT tails of 20-40 nucleotides in length to duplex DNA with all types of 3' termini.",1
"Deng, G, Wu, R",2
Reiterated sequences within the intron of an immediate-early gene of herpes simplex virus type 1.,0
"We describe the nucleotide sequence of a herpes simplex virus type 1 DNA fragment containing the intron of the immediate-early mRNA-5 (IE mRNA-5) gene. The location of the intron within this fragment was determined by a Berk & Sharp nuclease S1 protection analysis, and by cloning and sequencing cDNA containing sequences overlapping t he IE mRNA-5 splice point. We found that the 149 base pair (bp) intron contained four copies of an identical 23 bp GC rich tandem repeat followed by a further reiteration consisting of the first 15 bp only.",1
"Watson, R J, Umene, K, Enquist, L W",2
Genetic recombination: recA protein promotes homologous pairing between duplex DNA molecules without strand unwinding.,0
"The recA protein of Escherichia coli promotes pairing in vitro between covalent circular duplex DNA and homologous circular duplex DNA containing a single stranded region. We have used a filter binding assay to investigate the frequency of homologous pairing between gapped and intact duplex DNA when unwinding of the free 3' and 5' ends of the gapped molecules was blocked. In order to obtain DNA without free ends, the gapped DNA was treated with trimethylpsoralen and 360 nm light so as to introduce about 6 crosslinks per DNA molecule and the double stranded regions on either side of the gaps were then digested up to the first crosslinks with exonuclease III and lambda exonuclease. This treatment did not diminish the frequency of homologous pairing, an observation which is difficult to reconcile with models for recombination requiring strand unwinding before pairing.",1
"Cassuto, E, West, S C, Podell, J, Howard-Flanders, P",2
Can compassion be taught?,0
"Socrates (in the Meno) denied that virtues like courage could be taught, whereas Protagoras defended this claim. Compassion is discussed below in this context; it is distinguished from related, but different, moral qualities, and the role of imagination is emphasised. 'Sympathy's and role-modelling views of compassion's acquisition are criticised. Compassion can indeed be taught, but neither by the example of a few, isolated physicians nor by creation of Departments of Compassion. In replying to one standard objection to teaching compassion, it is emphasised that scientific competence and compassion aren't mutually exclusive.",1
"Pence, G E",2
Attitudes to research ethical committees.,0
"A questionnaire on the attitudes towards the functions of research ethical committees was sent to members of selected research ethical committees in Wessex and some controls. Almost all respondents felt there was a need for ethical review of research projects; 42 per cent thought there was a need for some training before joining a committee; 67 per cent thought the system could be improved and 47 per cent thought that monitoring or follow-up procedures should be adopted. Ethical committees were thought to be purely advisory, as opposed to mandatory, by 33 per cent, and 63 per cent thought they should restrict their review to ethical problems as opposed to scientific or design problems. Views about the function of non-medical members ranged from 'none at all' to 'very important'. Of the 10 controls who were asked whether they would become a member of an ethical committee if asked, seven said that on balance they would and the reasons stated varied from the view that it was a 'very important committee' to the feeling that it was 'a necessary but irksome job'.",1
"Allen, P, Waters, W E",2
Research on human subjects: Australian ethics committees take tentative steps.,0
"Australian medical researchers are attempting to formulate a response to some of the ethical issues in medical research. The debate over the in vitro fertilisation programme has highlighted some community concern about research ethics and the role of the ethics committee. While very little is known about Australian ethics committees, it appears that a two-tiered approach comprising both ethical review and scientific review is acceptable to the research community. However, this approach plus some problems with the nature of informed consent, begs the question of the role of these committees in the broader context of medical research in the community. Important aspects of a seminar for members of hospital ethics committees are reported.",1
"Osborne, L W",2
Informed consent: what does it mean?,0
"The editorial in the September 1982 issue of this journal and many articles before and since have addressed the problem of informed consent. Is it possible? Is it a useful concept? Is there anything new to be said about it? In this article the basic rationale of the rule (patient autonomy) is explained and the extent of the rule explored. Various exceptions have been offered by the law and an attempt is made to catalogue the chief of these. A number of specially vulnerable groups are then identified, the most important, and vexed, being children. How can informed consent be secured in the case of young patients? Finally, a few problems are mentioned in an attempt to get this subject back to reality. The appeal to the principle primum non nocere may be medical paternalism in disguise. Informed consent is the competing principle that reminds us of the primacy of human autonomy. A pointer is given to the future: even the use of sound recordings to explain medical procedures and to activate informed consent so that it may become a reality and not just a lawyer's myth, should be considered.",1
"Kirby, M D",2
Experimentation with human subjects: a critique of the views of Hans Jonas.,0
"The ethics of experimentation on human subjects has become the subject of much debate among medical scientists and philosophers. Ethical problems and conflicts of interest become especially serious when research subjects are recruited from the class of patients. Are patients who are ill and suffering in a position to give voluntary and informed consent? Are there inevitable conflicts of interest and moral obligation when a personal physician recruits his own patients for an experiment designed partly to advance scientific knowledge and only partly as therapy for those patients? The views of the eminent American ethicist Hans Jonas on these issues are briefly summarised and criticised, and some moral guidelines are then proposed to regulate experimentation on human subjects.",1
"Schafer, A",2
Basic problems in controlled trials.,0
"On the basis of critical discussions which have taken place in recent years in the Federal Republic of Germany, certain methodological, ethical and legal problems arising in relation to controlled trials are discussed. Because of methodological inconsistencies inherent in the experimental approach, the efficacy of a drug must in any case be judged by physicians. This leads to major ethical and even--at least in Germany--legal problems which impose considerable limits on the feasibility of controlled trials in Germany. Editor's note: This paper is written at the invitation of the journal, following the considerable controversy on the ethics of clinical trials in the European Journal of Clinical Pharmacology (8-11). A critical commentary follows the paper with a short response from the authors and a further response from the commentator.",1
"Burkhardt, R, Kienle, G",2
Debate: euthanasia--a physician's viewpoint.,0
"Discussion about euthanasia is often confused because of a failure to distinguish between deliberate death acceleration and letting nature take its course. There is a need to reiterate the traditional principles upon which the care of the dying should be based, including the need for the doctor to practise medicine in the knowledge that eventually all his patients will die. It follows that a doctor does not have a duty to preserve life at all costs. The care of the patient with far-advanced cancer has improved considerably in many areas as a result of the establishment of hospices and domiciliary support teams. Treating the patient as a person is the key to a successful doctor-patient relationship. An analytical approach is necessary to control pain and other symptoms. Care of the relatives is also fundamental. Voluntary euthanasia and 'assisted suicide' represent an extreme solution to a situation which demands a far more comprehensive and compassionate approach. The need is not for a change in the law but for a change of emphasis in medical education.",1
"Twycross, R G",2
The MODY1 gene HNF-4alpha regulates selected genes involved in insulin secretion.,0
"Mutations in the gene encoding hepatocyte nuclear factor-4alpha (HNF-4alpha) result in maturity-onset diabetes of the young (MODY). To determine the contribution of HNF-4alpha to the maintenance of glucose homeostasis by the beta cell in vivo, we derived a conditional knockout of HNF-4alpha using the Cre-loxP system. Surprisingly, deletion of HNF-4alpha in beta cells resulted in hyperinsulinemia in fasted and fed mice but paradoxically also in impaired glucose tolerance. Islet perifusion and calcium-imaging studies showed abnormal responses of the mutant beta cells to stimulation by glucose and sulfonylureas. These phenotypes can be explained in part by a 60% reduction in expression of the potassium channel subunit Kir6.2. We demonstrate using cotransfection assays that the Kir6.2 gene is a transcriptional target of HNF-4alpha. Our data provide genetic evidence that HNF-4alpha is required in the pancreatic beta cell for regulation of the pathway of insulin secretion dependent on the ATP-dependent potassium channel.",1
"Gupta, Rana K, Vatamaniuk, Marko Z, Lee, Catherine S, Flaschen, Reed C, Fulmer, James T, Matschinsky, Franz M, Duncan, Stephen A, Kaestner, Klaus H",2
Impaired humoral immunity in X-linked lymphoproliferative disease is associated with defective IL-10 production by CD4+ T cells.,0
"X-linked lymphoproliferative disease (XLP) is an often-fatal immunodeficiency characterized by hypogammaglobulinemia, fulminant infectious mononucleosis, and/or lymphoma. The genetic lesion in XLP, SH2D1A, encodes the adaptor protein SAP (signaling lymphocytic activation molecule-associated [SLAM-associated] protein); however, the mechanism(s) by which mutations in SH2D1A causes hypogammaglobulinemia is unknown. Our analysis of 14 XLP patients revealed normal B cell development but a marked reduction in the number of memory B cells. The few memory cells detected were IgM(+), revealing deficient isotype switching in vivo. However, XLP B cells underwent proliferation and differentiation in vitro as efficiently as control B cells, which indicates that the block in differentiation in vivo is B cell extrinsic. This possibility is supported by the finding that XLP CD4(+) T cells did not efficiently differentiate into IL-10(+) effector cells or provide optimal B cell help in vitro. Importantly, the B cell help provided by SAP-deficient CD4(+) T cells was improved by provision of exogenous IL-10 or ectopic expression of SAP, which resulted in increased IL-10 production by T cells. XLP CD4(+) T cells also failed to efficiently upregulate expression of inducible costimulator (ICOS), a potent inducer of IL-10 production by CD4(+) T cells. Thus, insufficient IL-10 production may contribute to hypogammaglobulinemia in XLP. This finding suggests new strategies for treating this immunodeficiency.",1
"Ma, Cindy S, Hare, Nathan J, Nichols, Kim E, Dupré, Loic, Andolfi, Grazia, Roncarolo, Maria-Grazia, Adelstein, Stephen, Hodgkin, Philip D, Tangye, Stuart G",2
Effect of fathers' age and birth order on occurrence of congenital heart disease.,0
The aim was to examine if there is an effect of fathers' age and of birth order on the occurrence of congenital heart disease.,1
"Zhan, S Y, Lian, Z H, Zheng, D Z, Gao, L",2
Partial gastrectomy and subsequent gastric cancer risk.,0
The aim was to analyse the relationship between partial gastrectomy and gastric cancer risk.,1
"La Vecchia, C, Negri, E, D'Avanzo, B, Moller, H, Franceschi, S",2
Evaluation of pure tone audiometry and impedance screening in infant schoolchildren.,0
The aims were (1) to evaluate impedance measurements against pure tone audiometry as a screening method for the detection of middle ear changes associated with hearing loss in infant school children; (2) to estimate the costs of the health authority of each method.,1
"Holtby, I, Forster, D P",2
Loss and representativeness in a 43 year follow up of a national birth cohort.,0
The aim was to describe rates of loss and assessment of representativeness during 43 years of a national birth cohort study.,1
"Wadsworth, M E, Mann, S L, Rodgers, B, Kuh, D J, Hilder, W S, Yusuf, E J",2
Mortality among female manual workers.,0
The aim was to determine whether female manual workers have higher mortality than other women.,1
"Gunnarsdóttir, H, Rafnsson, V",2
Uptake of preventive health care among Mediterranean migrants in Belgium.,0
The aim was to investigate the influence of ethnicity on the demand for preventive care by Mediterranean migrants in Belgium.,1
"Van der Stuyft, P, Woodward, M, Amstrong, J, De Muynck, A",2
Factors associated with constipation in a community based sample of people aged 70 years and over.,0
The aim was to determine the prevalence and factors associated with constipation in elderly people.,1
"Campbell, A J, Busby, W J, Horwath, C C",2
Changing trend of neural tube defects in eastern Turkey.,0
The aim was to study the relationship between birth prevalence of neural tube defect (including anencephaly) in Eastern Turkey before and after the Chernobyl disaster.,1
"Güvenc, H, Uslu, M A, Güvenc, M, Ozekici, U, Kocabay, K, Bektaş, S",2
"Sunlight exposure, antioxidant status, and cataract in Hong Kong fishermen.",0
"The aim was to test whether cataract is associated with higher lifetime exposure to sunlight, and whether antioxidants protect against cataract.",1
"Wong, L, Ho, S C, Coggon, D, Cruddas, A M, Hwang, C H, Ho, C P, Robertshaw, A M, MacDonald, D M",2
Mortality among injecting drug users: a critical reappraisal.,0
The aim was to quantify all cause mortality among injecting drug users.,1
"Frischer, M, Bloor, M, Goldberg, D, Clark, J, Green, S, McKeganey, N",2
Trends in body mass index and prevalence of obesity in Swedish men 1980-89.,0
"To assess changes in the body mass index (BMI, weight (kg)/height2 (m2) and in the prevalence of obesity in Swedish men during the 1980s.",1
"Kuskowska-Wolk, A, Bergström, R",2
Magnitude and causes of mortality differences between married and unmarried men.,0
"To determine the effect of marital status on mortality for men. In particular, to examine whether subgroups of unmarried men (widowed, single, and divorced/separated men) have a similar mortality to married men.",1
"Ben-Shlomo, Y, Smith, G D, Shipley, M, Marmot, M G",2
Randomised controlled trial in northern England of the effect of a person knowing their own serum cholesterol concentration.,0
To test the hypotheses that the knowledge that the serum cholesterol concentration is raised (> or = 6.5 mmol/l) will lead to a reduction in the concentration after education intervention and that the knowledge that the concentration is not raised does not lead to an increase in the serum cholesterol concentration after education intervention.,1
"Elton, P J, Ryman, A, Hammer, M, Page, F",2
Recurrence of acute otitis media at preschool age in Sweden.,0
The probability of recurrence of acute otitis media during the preschool years was investigated.,1
"Rasmussen, F",2
An outbreak of illness among schoolchildren in London: toxic poisoning not mass hysteria.,0
"To determine the cause of an outbreak of acute gastrointestinal illness that occurred shortly after lunch in children attending a school in London, UK.",1
"Aldous, J C, Ellam, G A, Murray, V, Pike, G",2
Childhood socioeconomic status and risk of cardiovascular disease in middle aged US women: a prospective study.,0
To examine prospectively the relationship of childhood socioeconomic status and risk of cardiovascular disease in middle aged women.,1
"Gliksman, M D, Kawachi, I, Hunter, D, Colditz, G A, Manson, J E, Stampfer, M J, Speizer, F E, Willett, W C, Hennekens, C H",2
Emotional reactions in women attending a UK colposcopy clinic.,0
"To assess the emotional responses of women attending a colposcopy clinic for investigation of an abnormal cervical smear, and to elicit the women's views on the screening service and colposcopy clinic.",1
"Gath, D H, Hallam, N, Mynors-Wallis, L, Day, A, Bond, S A",2
"Levels of mortality, education, and social conditions in the 107 local education authority areas of England.",0
"To investigate the relationships between education, social conditions, and mortality.",1
"Morris, J N, Blane, D B, White, I R",2
"An epidemiological study after a water contamination incident near Worcester, England in April 1994.",0
"To investigate whether exposure to tap water contaminated in a major river pollution incident with 2 ethyl 5,5 dimethyl 1,3 dioxane (EDD) and 2 ethyl 4 methyl 1,3 dioxolane (EMD) was associated with an increase of self reported symptoms. To assess the extent of association between noticing the water had an unusual taste or odour and self reported symptoms.",1
"Fowle, S E, Constantine, C E, Fone, D, McCloskey, B",2
Epidemiology and patterns of hospital use after parasuicide in the south west of England.,0
"To describe the epidemiology, management, and outcome of parasuicide in the south west of England.",1
"Gunnell, D J, Brooks, J, Peters, T J",2
Suicide from the Clifton Suspension Bridge in England.,0
To examine the epidemiology of suicide by jumping from the Clifton Suspension Bridge and its impact on local patterns of suicide.,1
"Nowers, M, Gunnell, D",2
Psychosocial resources and persistent smoking in early pregnancy--a population study of women in their first pregnancy in Sweden.,0
"To test the stress hypothesis by characterising women during their first pregnancy who continue to smoke in early pregnancy in comparison with women who quit smoking, with special reference to psychosocial factors like social network, social support, demands, and control in work and daily life.",1
"Dejin-Karlsson, E, Hanson, B S, Ostergren, P O, Ranstam, J, Isacsson, S O, Sjöberg, N O",2
Features of infant exposure to tobacco smoke in a cohort study in Tasmania.,0
To document changes in smoking style around infants over time and to identify factors associated with the smoking hygiene of mothers and others.,1
"Ponsonby, A L, Couper, D, Dwyer, T",2
Cancer risk and prognosis in Norway: comparing women in their first marriage with women who have never married.,0
The difference in risk of cancer between never married women and married women in their first marriage and whether survival from cancer was any different between the two groups were studied.,1
"Kvikstad, A, Vatten, L J",2
Housing conditions and mental health in a disadvantaged area in Scotland.,0
To examine the mental health impact of different aspects of poor housing.,1
"Hopton, J L, Hunt, S M",2
Epidemiological survey of rheumatic heart disease among school children in the Shimla Hills of northern India: prevalence and risk factors.,0
"To determine the prevalence of rheumatic heart disease (RHD) and study the relationship of this disease to factors such as age, sex, housing, and socioeconomic status in Shimla town and the adjoining rural area.",1
"Thakur, J S, Negi, P C, Ahluwalia, S K, Vaidya, N K",2
Age specific sensitivity and sojourn time in a breast cancer screening programme (DOM) in The Netherlands: a comparison of different methods.,0
To estimate age dependent sensitivity and sojourn time in a breast cancer screening programme by different methods.,1
"Brekelmans, C T, Westers, P, Faber, J A, Peeters, P H, Collette, H J",2
Breast screening: a randomised controlled trial in UK general practice of three interventions designed to increase uptake.,0
To determine the relative effectiveness of three interventions designed to increase the uptake of breast screening.,1
"Sharp, D J, Peters, T J, Bartholomew, J, Shaw, A",2
"Response of women aged 65-74 to invitation for screening for breast cancer by mammography: a pilot study in London, UK.",0
"To investigate the response and benefits to be gained from mammographic screening for breast cancer in women aged 65-74, who are not normally invited for screening.",1
"Horton Taylor, D, McPherson, K, Parbhoo, S, Perry, N",2
Comparing survey data on functional disability: the impact of some methodological differences.,0
To examine the impact of some differences in survey methodology on the prevalence of functional disability in population based surveys of the elderly.,1
"Picavet, H S, van den Bos, G A",2
Estimating the point accuracy of population registers using capture-recapture methods in Scotland.,0
To estimate the point accuracy of adult registration on the community health index (CHI) by comparing it with the electoral register (ER) and the community charge register (CCR).,1
"Garton, M J, Abdalla, M I, Reid, D M, Russell, I T",2
Research on injury prevention: time for an international agenda?,0
To propose an initial agenda for a systematic international research strategy designed to meet the information needs of injury prevention worldwide.,1
"Stone, D H",2
Effect of diet and physical exercise intervention programmes on coronary heart disease risk in smoking and non-smoking men in Sweden.,0
"To investigate differences between smokers and non-smokers in health behaviour, cardiovascular risk factors, coronary heart disease (CHD) risks, health knowledge, health attitudes, and compliance with a CHD prevention programme.",1
"Näslund, G K, Fredrikson, M, Hellénius, M L, de Faire, U",2
Prevalence of self reported stroke in a population in northern England.,0
The aim of this study was to determine the prevalence of stroke survivors in a health district population aged 55 years and over.,1
"Geddes, J M, Fear, J, Tennant, A, Pickering, A, Hillman, M, Chamberlain, M A",2
The effects of illness on quality of life: findings from a survey of households in Great Britain.,0
"To obtain national population norms on pertinent domains of quality of life, and the relative importance of these domains to people with reported longstanding illness.",1
"Bowling, A",2
The prediction of different experiences of longterm illness: a longitudinal approach in Sweden.,0
"To analyse the role played by socioeconomic factors and self rated general health in the prediction of the reporting of severe longterm illness, and the extent to which these factors explain social class differences in the reporting of such illness.",1
"Blank, N, Diderichsen, F",2
"Child pedestrian injury rates: the importance of ""exposure to risk"" relating to socioeconomic and ethnic differences, in Auckland, New Zealand.",0
"To examine how child pedestrian exposure to risk, as measured by the mean number of streets crossed, varies according to indices of material disadvantage and ethnic group.",1
"Roberts, I, Norton, R, Taua, B",2
"Importance of participation rate in sampling of data in population based studies, with special reference to bone mass in Sweden.",0
"To study the effects of participation rate in sampling on ""normative"" bone mass data.",1
"Düppe, H, Gärdsell, P, Hanson, B S, Johnell, O, Nilsson, B E",2
Hand searching the Journal of Epidemiology and Community Health as part of th Cochrane Collaboration.,0
To identify randomised controlled trials (RCTs) published in the Journal of Epidemiology and Community Health and to explore the contribution of these to the evaluation of public health issues.,1
"Milne, R, Thorogood, M",2
"Using length of stay and inactive days in the hospital to assess appropriateness of utilisation in Barcelona, Spain.",0
To compare the level of inappropriate utilisation of a teaching hospital in two different calendar years and to analyse the relationship between changes in appropriateness of utilisation and changes in average length of stay.,1
"Alonso, J, Muñoz, A, Antó, J M",2
"Hospital volume, calendar age, and short term outcomes in patients undergoing repair of abdominal aortic aneurysms: the Ontario experience, 1988-92.",0
"To determine, for abdominal aortic aneurysm surgery, whether a previously reported relationship between hospital case volume and mortality rate was observed in Ontario hospitals and to assess the potential impact of age on the mortality rate for elective surgery.",1
"Wen, S W, Simunovic, M, Williams, J I, Johnston, K W, Naylor, C D",2
Estimating life expectancy using an age-cohort model in Taiwan.,0
"Life expectation is a valuable summary index in public health and actuarial science. The life expectancies published in the vital statistics, however, are derived from the ""current"" rather than from the ""cohort"" life table. The former is based on a strong assumption of constant mortality in the population, whereas the latter calls for a recording of the mortality experience of a group of individuals, which is often an impossible task. Thus, a method of calculating cohort life expectancy without actual follow up is much needed.",1
"Lee, W C, Hsieh, R L",2
"Agreement between the Takeda UA-731 automatic blood pressure measuring device and the manual mercury sphygmomanometer: an assessment under field conditions in Newcastle upon Tyne, UK.",0
To assess agreement between two Takeda UA-731 automatic blood pressure measuring devices (referred to as machines A and B) and two manual mercury sphygmomanometers.,1
"Cartwright, C, Unwin, N, Stephenson, P",2
Discounting the future: influence of the economic model.,0
To consider the effect of the economic discount rate on health care policy and the rationale for discounting the collective future of society generally.,1
"West, R R",2
Race and self assessed health status: the role of socioeconomic factors in the USA.,0
"To estimate relative odds ratios and to ascertain the relative contribution of each socioeconomic covariate in explaining racial disparities in self assessed health status (for example, global health perceptions and functional limitations of daily activities).",1
"Ren, X S, Amick, B C",2
"Risk factors, falls, and fracture of the distal forearm in Manchester, UK.",0
"To determine the risk factors associated with fracture of the distal forearm, and to evaluate the influence of falls on these risks.",1
"O'Neill, T W, Marsden, D, Adams, J E, Silman, A J",2
Estimating the incidence of coeliac disease with capture-recapture methods within four geographic areas in Italy.,0
To estimate the incidence rate of newly diagnosed cases of coeliac disease in Italy.,1
"Corrao, G, Usai, P, Galatola, G, Ansaldi, N, Meini, A, Pelli, M A, Castellucci, G, Corazza, G R",2
Spatial clustering of childhood cancers in Great Britain.,0
"Firstly, to identify spatially close pairs and triplets of childhood leukaemias and cancers in Britain. Secondly, to compare pair frequencies with random expectations, identify excesses, and measure the diameters of any clusters. Thirdly, to infer possible causes.",1
"Knox, E G, Gilman, E A",2
"The effectiveness of health systems in influencing avoidable mortality: a study in Valencia, Spain, 1975-90.",0
To measure variations in the Holland and Charlton classifications of avoidable death causes and to estimate the effect of the Spanish national health system on avoidable mortality.,1
"Albert, X, Bayo, A, Alfonso, J L, Cortina, P, Corella, D",2
"Can regional variation in ""avoidable"" mortality be explained by deaths outside hospital? A study from Sweden, 1987-90.",0
This study aimed to calculate the proportion of deaths outside hospital in Sweden for some conditions for which the acute medical management may be important to the outcome and to analyse whether the proportion of deaths outside hospital can explain regional variations in mortality from these causes of death.,1
"Westerling, R",2
"Challenges of monitoring use of secondary care at local level: a study based in London, UK.",0
To provide those working at district level with practical guidance on using hospital data linked to small geographic areas to explore patterns of care.,1
"Chenet, L, McKee, M",2
Modelling inequality in reported long term illness in the UK: combining individual and area characteristics.,0
To assess the nature of the relation between health and social factors at both the aggregated scale of geographical areas and the individual scale.,1
"Shouls, S, Congdon, P, Curtis, S",2
Evidence for the sensitivity of the SF-36 health status measure to inequalities in health: results from the Oxford healthy lifestyles survey.,0
"The short form 36 (SF-36) health questionnaire may not be appropriate for population surveys assessing health gain because of the low responsiveness (sensitivity to change) of domains on the measure. An hypothesised health gain of respondents in social class V to that of those in social class I indicated only marginal improvement in self reported health. Subgroup analysis, however, showed that the SF-36 would indicate dramatic changes if the health of social class V could be improved to that of social class I.",1
"Jenkinson, C, Layte, R, Coulter, A, Wright, L",2
General practice on a new housing estate. 1956.,0
"An analysis has been carried out of the records kept for the year 1953 by six doctors practising on a new housing estate near London. The population of the estate is described in terms of age, sex, and social class. 76 per cent. of the registered patients consulted a doctor at some time during the year, the consultation rate per person being 4.1 based on the average registered population; females had more consultations than males; 80 per cent. of all consultations were made by people under the age of 45. One-sixth of the patients accounted for about half of the consultations, and 30 per cent. of the consultations were made by the 7 per cent. of registered patients who consulted twelve or more times in the year. The consultation rates showed a slight, but statistically significant, social gradient, with more consultations among patients in the lower social classes. The illness rate was 26 per person, and was higher among males in infancy and old age, and among females between the ages of 5 and 64. A method of estimating the duration of sickness in terms of the period under medical care was employed. This showed that 70 per cent. of all illnesses were dealt with in single consultations, and that only 3 per cent. of illnesses were under care for more than 90 days. Over half of the practice population were under care for less than 5 days, and only 8 per cent. for more than 90 days. The proportion of patients having more than 30 days sickness generally increased with age, but there was a slight fall among the women aged 65 and over. Certificates were issued at the rate of about one for every five consultations, two-thirds of these being necessitated by the requirements of the National Insurance regulations. Prescriptions were issued at the rate of about one per consultation, the prescription rate being 41 per person. Only 5 per cent. of the practice population consulted the doctor but did not obtain a prescription. About 30 per cent. of the patients who consulted a doctor were referred outside the practices, 80 per cent. of all referrals being to hospitals, either as inpatients or as out-patients. The person-hospital referral rate was 20 per 100, and there were 31 referrals for every 100 registered patients. Males over 65 had the highest rates for consultations, illnesses, prescriptions, and referrals. The reason for this is discussed. The value of record-keeping by general practitioners is stressed, together with the need for a generally accepted method of expressing rates in studies of this kind.",1
"Brotherston, J H, Chave, S P, Cledwyn-Davies, A, Hunter, A S, Lindsay, D A, Scott, A, Thomson, C B, Trimmer, E J",2
Further thoughts on the aluminum-Alzheimer's disease link.,0
"STUDY OBJECTIVE AND METHOD: The results of studies on aluminum (Al) and Alzheimer's disease (AD) from groups in Newcastle, UK and Ontario, Canada were compared in order to explain why the former were unable to detect a link while the latter could, and to suggest alternative ways of examining the data.",1
"Forbes, W F, McLachlan, D R",2
"Body size and mortality in women: a 29 year follow up of 12,000 pregnant women in northern Finland.",0
"To examine the association between body height, body mass index (BMI), and mortality in fertile women of childbearing age.",1
"Läärä, E, Rantakallio, P",2
Health and social precursors of unemployment in young men in Great Britain.,0
To identify health and socioeconomic factors in childhood that are precursors of unemployment in early adult life and to examine the hypothesis that young men who become unemployed are more likely to have accumulated risks to health during childhood.,1
"Montgomery, S M, Bartley, M J, Cook, D G, Wadsworth, M E",2
Mature maternity: long term associations in first children born to older mothers in 1970 in the UK.,0
"To identify the physical, behavioural, medical, and educational outcomes in first children born to women aged 30 or more compared with those born to younger women.",1
"Pollock, J I",2
"The admission of Asian patients to intensive therapy units and its implications for kidney donation: a preliminary report from Coventry, UK.",0
To determine the relative admission rates of Asian and non-Asian patients to intensive therapy units (ITUs) in Coventry and to explore the implications of these rates for the transplantation of organs to Asian people.,1
"Exley, C, Sim, J, Reid, N G, Booth, L, Jackson, S, West, N",2
Non-urgent care in the hospital medical emergency department in France: how much and which health needs does it reflect?,0
The goal was to describe the use of the medical emergency department as a source of non-urgent medical care in order to assess unmet health care needs among its users. The specific objectives were thus to assess the proportion of emergency department visits for non-urgent medical care and to describe those who used the department for this reason.,1
"Lang, T, Davido, A, Diakité, B, Agay, E, Viel, J F, Flicoteaux, B",2
Targeted hepatitis B vaccination--a cost effective immunisation strategy for the UK?,0
To compare the potential cost effectiveness of vaccination against hepatitis B virus (HBV) targeted at genitourinary clinic (GU) attendees with that of universal infant vaccination.,1
"Williams, J R, Nokes, D J, Anderson, R M",2
Factors associated with birth weight in Sweden: the study of men born in 1913.,0
To analyse factors associated with birth weight and to evaluate the validity of obstetrical data.,1
"Eriksson, M, Cnattingius, S, Svärdsudd, K, Tibblin, G",2
Socioeconomic status and lung cancer incidence in men in The Netherlands: is there a role for occupational exposure?,0
To evaluate the influence of occupational exposure to carcinogens in explaining the association between socioeconomic status and lung cancer.,1
"van Loon, A J, Goldbohm, R A, Kant, I J, Swaen, G M, Kremer, A M, van den Brandt, P A",2
"Social class and cancer survival in Turin, Italy.",0
"This study aimed to investigate social differences in cancer survival in residents of Turin, Italy.",1
"Rosso, S, Faggiano, F, Zanetti, R, Costa, G",2
"Evaluation of specialists' outreach clinics in general practice in England: process and acceptability to patients, specialists, and general practitioners.",0
"The wider study aimed to evaluate specialists' outreach clinics in relation to their costs, processes, and effectiveness, including patients' and professionals' attitudes. The data on processes and attitudes are presented here.",1
"Bowling, A, Stramer, K, Dickinson, E, Windsor, J, Bond, M",2
"Predictors of returning for second round screening at a population based mammographic screening programme in Melbourne, Australia.",0
To examine factors associated with returning for second round mammography screening.,1
"Cockburn, J, Schofield, P, White, V, Hill, D, Russell, I",2
Methodology for assessing the prevalence of angina in primary care using practice based information in northern England.,0
The study aimed to consider the value of nitrate prescriptions issued by general practices as an indicator of coronary heart disease and to compare this with the use of coronary heart disease registers.,1
"Bottomley, A",2
Systematic identification of twins by computerised searches of NHS patient registers in the UK.,0
"This study aimed to assess the feasibility, sensitivity, and specificity of a systematic search of the NHS central register for twins of the same sex.",1
"Strachan, D P, Burnett, A C",2
Trends in stroke mortality in Greater London and south east England--evidence for a cohort effect?,0
To examine time trends in stroke mortality in Greater London compared with the surrounding South East Region of England.,1
"Maheswaran, R, Strachan, D P, Elliott, P, Shipley, M J",2
"Lifelong exposures and the potential for stroke prevention: the contribution of cigarette smoking, exercise, and body fat.",0
"To examine the potential for stroke prevention by avoidance of hazards related to lifestyle. Assessment of the lifelong contribution of both individual and combined exposures was a particular feature of the study. An estimate was sought of the proportion (population attributable risk fraction) of strokes likely to be caused by one or a combination of cigarette smoking, lack of exercise, and obesity.",1
"Shinton, R",2
Hazard proximities of childhood cancers in Great Britain from 1953-80.,0
"Firstly, to examine relationships between the birth and death addresses of children dying from leukaemia and cancer in Great Britain, and the sites of potential environmental hazards; and secondly to measure relative case densities close to, and at increasing distances from, different hazard types.",1
"Knox, E G, Gilman, E A",2
Deaths from cirrhosis in Poland and Hungary: the impact of different alcohol policies during the 1980s.,0
To compare patterns of deaths from cirrhosis in Poland and Hungary in the context of differing alcohol policies in the 1980s.,1
"Varvasovsky, Z, Bain, C, McKee, M",2
"Effects of preventive health services on survival of the elderly living in a community in Osaka, Japan.",0
"To examine the relationships between the use of preventive health services--such as health checks, basic health examination/cancer screening, and daily preventive health practices--and survival of elderly people living in the community.",1
"Nakanishi, N, Tatara, K, Tatatorige, T, Murakami, S, Shinsho, F",2
Asthma and thunderstorms: description of an epidemic in general practice in Britain using data from a doctors' deputising service in the UK.,0
To describe the areas affected and the scale of an epidemic of thunderstorm associated asthma on the night of 24/25 June 1994 and to explore the spatial and temporal relationship between the thunderstorm and the associated epidemic.,1
"Higham, J, Venables, K, Kupek, E, Bajekal, M, Kopek, E",2
Weight gain during the first year of life in relation to maternal smoking and breast feeding in Norway.,0
To assess the weight gain during the first year of life in relation to maternal smoking during pregnancy and the duration of breastfeeding.,1
"Nafstad, P, Jaakkola, J J, Hagen, J A, Pedersen, B S, Qvigstad, E, Botten, G, Kongerud, J",2
Cardiovascular risk factor profile in subjects with familial predisposition to myocardial infarction in Denmark.,0
To identify possible modifiable mediators of familial predisposition to myocardial infarction (MI) by assessing the risk factor profile in individuals without MI in relation to parental occurrence of MI.,1
"Hippe, M, Vestbo, J, Bjerg, A M, Borch-Johnsen, K, Appleyard, M, Hein, H O, Andersen, P K, Jensen, G, Sørensen, T I",2
Nutritional assessment of two famine prone Ethiopian communities.,0
To compare two ethnically distinct Ethiopian populations (Oromo Arsi in Elka in the Rift Valley and Anyuak in Punjido in Gambella) for two widely used anthropometric indices of protein-energy malnutrition: body mass index < 18.5 and arm muscle circumference < 80% of the median of the US NHANES reference data.,1
"Alemu, T, Lindtjørn, B",2
Estimating potential savings in cancer deaths by eliminating regional and social class variation in cancer survival in the Nordic countries.,0
"To examine equity in the health care system with regard to cancer patient care by estimating the level of systematic regional variation in cancer survival in the Nordic countries. Specifically, those cancer sites which exhibit high levels of systematic regional variation in survival and hence inequity were identified. Estimating the reduction in cancer deaths which could be achieved by eliminating this variation so that everyone receives effective care will provide a readily interpretable measure of the amount of systematic regional variation. A comprehensive analysis of regional variation in survival has not previously been conducted so appropriate statistical methodology must be developed.",1
"Dickman, P W, Gibberd, R W, Hakulinen, T",2
Community mothers' programme: extension to the travelling community in Ireland.,0
"To see whether the community mothers' programme, using lay volunteer mothers to deliver a childhood development programme, could be extended successfully to the travelling community in Ireland.",1
"Fitzpatrick, P, Molloy, B, Johnson, Z",2
Strategies for the prevention of psychiatric disorder in primary care in south London.,0
"To compare the potential impact of high risk and population based approaches to the prevention of psychiatric disorder, using a representative sample of general practice attenders as the target population.",1
"Weich, S, Lewis, G, Churchill, R, Mann, A",2
"Prospective versus retrospective measurement of change in health status: a community based study in Geneva, Switzerland.",0
To compare prospective and retrospective measurements of change in health status.,1
"Perneger, T V, Etter, J F, Rougemont, A",2
"Validation of a short telephone administered questionnaire to evaluate dietary interventions in low income communities in Montreal, Canada.",0
"To validate an adaptation of a short questionnaire measuring behaviour related to selecting low fat diets. The questionnaire was adapted for telephone use in a low income, low education population.",1
"Gray-Donald, K, O'Loughlin, J, Richard, L, Paradis, G",2
How should interventions to reduce inequalities in health be evaluated?,0
The effectiveness of interventions which have been proposed or are currently in progress to reduce socioeconomic inequalities in health is largely unknown. This paper aims to develop guidelines for evaluating these interventions.,1
"Mackenbach, J P, Gunning-Schepers, L J",2
"Suicide in the 12 months after discharge from psychiatric inpatient care, Scotland 1968-92.",0
"To investigate the rate of suicide in the 12 months after discharge from psychiatric hospital and to determine its relationship to age, diagnosis, and period.",1
"Geddes, J R, Juszczak, E, O'Brien, F, Kendrick, S",2
Fatal methadone and heroin overdoses: time trends in England and Wales.,0
"Although the total number of self poisonings in England and Wales has dropped by 32%, the number involving methadone and/or heroin rose by 900% in 1974-92. Because of concern about the role of methadone in this increase, the part played by methadone and heroin in poisoning deaths in England and Wales in 1974-92 was investigated.",1
"Neeleman, J, Farrell, M",2
Results of a pilot study of endoscopic screening of first degree relatives of colorectal cancer patients in Italy.,0
"Screening recommendations for colorectal cancer include sigmoidoscopy in asymptomatic, average risk persons aged 50 and over and colonoscopy every three to five years in high risk groups. Little is known about the eligible population's compliance with endoscopic screening. This is the first Italian report of an endoscopic screening programme for colorectal cancer patients' relatives.",1
"Colombo, L, Corti, G, Magrì, F, Marocchi, A, Brambilla, P, Crespi, C, Manieri, L, Ghezzi, S, Giannone, D, Merlino, L, Mocarelli, P",2
"Has regional variation in mortality rates declined since 1931, and in all age groups, in Britain? A re-analysis using formal statistical modelling.",0
"To examine changes in regional variance in all cause mortality rates in Great Britain from 1931-91 using formal statistical modelling procedures, and to follow up the suggestion by Illsley and Le Grand that there has been a reduction over time in the regional variance in younger but not older age groups.",1
"Ecob, R, Robertson, C, Watt, G",2
What happened to life expectancy in Spain in the 1980s?,0
"Life expectancy at birth in Spain improved between 1972 and 1982, by 2.5 years for males and 3.2 years for females. This slowed considerably in the following decade, with increases of only 0.5 and 1.7 years respectively.",1
"Chenet, L, McKee, M, Otero, A, Ausin, I",2
"Prediction of coronary heart disease mortality in Busselton, Western Australia: an evaluation of the Framingham, national health epidemiologic follow up study, and WHO ERICA risk scores.",0
"To evaluate the performance of the Framingham, national health epidemiologic follow up study, and the WHO ERICA risk scores in predicting death from coronary heart disease (CHD) in an Australian population.",1
"Knuiman, M W, Vu, H T",2
Laypersons' evaluation of health: an exploratory study of an Australian population.,0
"The importance of 33 aspects of health was evaluated by 677 people as part of a postal random population survey conducted in Adelaide, South Australia. Principal factors analysis suggested that the respondents' evaluations could be represented along four dimensions to do with: the avoidance of illness; feeling healthy; healthy lifestyle; and disease prevention activities. Generally, women, persons in older age groups, and persons in lower social status and education groups evaluated health more highly than others. These and other findings suggest that health evaluations depend upon illness experience and social roles. These findings have implications for health education, mass communication and medical practice.",1
"Worsley, A",2
Default in the outpatient treatment of tuberculosis in two hospitals in Northern India.,0
The purpose of the study was to examine default rates in tuberculosis treatment in two hospitals in north India with different follow up arrangements.,1
"Reed, J B, McCausland, R, Elwood, J M",2
Will a breast screening programme change the workload and referral practice of general practitioners?,0
The aim of the study was to consider possible changes in the clinical activities of general practitioners whose patients are registered in a breast cancer screening programme.,1
"Ashby, J, Buxton, M, Gravelle, H",2
Investigation of spacial clustering of rare diseases: childhood malignancies in North Humberside.,0
The aims of the study were (1) to test for uniformity of distribution of childhood leukaemias and other malignancies; and (2) to consider the aetiological implications of unusual distributions.,1
"Alexander, F, Cartwright, R, McKinney, P A, Ricketts, T J",2
Childhood morbidity and adulthood ill health.,0
The aim of the study was to investigate the relationship between the state of health in childhood and ill health in early adult life.,1
"Power, C, Peckham, C",2
"Race, consanguinity and social features in Birmingham babies: a basis for prospective study.",0
The aim of the study was to investigate the influence of consanguinity on children's health.,1
"Bundey, S, Alam, H, Kaur, A, Mir, S, Lancashire, R J",2
High density lipoprotein cholesterol concentration as a predictor of coronary heart disease in West Indian men.,0
The aim of the study was to determine whether the inverse association between high density lipoprotein cholesterol concentration and risk of coronary heart disease described in people of European stock was also present in other racial groups.,1
"Miller, G J, Beckles, G L, Maude, G H, Carson, D C, Price, S G",2
Risk of death from cardiovascular disease and chronic bronchitis determined by place of birth in England and Wales.,0
The aim of the study was to examine the relation between place of birth within England and Wales and cause of death.,1
"Osmond, C, Barker, D J, Slattery, J M",2
"Upper respiratory tract infection in children, domestic temperatures, and humidity.",0
The aim of the study was to seek for a possible association between the incidence of upper respiratory tract infections and air temperature and humidity in the home.,1
"Ross, A, Collins, M, Sanders, C",2
Head injuries in accident and emergency departments. How different are children from adults?,0
The aim of the study was to examine the differences between child and adult patients attending accident and emergency departments after recent head injuries.,1
"Brookes, M, MacMillan, R, Cully, S, Anderson, E, Murray, S, Mendelow, A D, Jennett, B",2
"Geographical variation in cancer patient survival in Finland: chance, confounding, or effect of treatment?",0
"The aim was to determine whether survival of cancer patients in Finland varies with their place of residence, and if so, what proportion of the variation might be due to health services rather than to confounding variables.",1
"Karjalainen, S",2
"A cohort analysis of breast cancer, uterine corpus cancer, and childbearing pattern in Norwegian women.",0
The aim was to study the influence of childbearing pattern on the incidence of breast cancer and uterine corpus cancer.,1
"Tretli, S, Haldorsen, T",2
Is preterm delivery still related to physical working conditions in pregnancy?,0
"The aim was to determine the relationship between working conditions during pregnancy, women's occupation, and preterm birth.",1
"Saurel-Cubizolles, M J, Subtil, D, Kaminski, M",2
"Prevalence of neural tube defects in 20 regions of Europe and the impact of prenatal diagnosis, 1980-1986. EUROCAT Working Group.",0
"The aims were (1) to determine whether in Europe, 1980-86, geographical differences in total prevalence of neural tube defects persist; (2) to examine the stability of total prevalence rates over time; (3) to evaluate the impact of prenatal diagnosis in terms of frequency and timing of termination of pregnancy.",1
The quality of health services research in medical practice in the United Kingdom.,0
The aim was to determine the scope and quality of published health services research concerned with medical practice in the United Kingdom.,1
"Fowkes, F G, Garraway, W M, Sheehy, C K",2
Treatment of early rheumatoid arthritis with rifampicin.,0
"Following a report that seven of 20 patients with rheumatoid arthritis (RA) had come into clinical and laboratory remission after treatment with rifampicin, and that six of the seven responders had a disease duration of less than three years, 21 patients with classical or definite RA of recent onset were treated with 600 mg rifampicin and 300 mg isoniazid daily for six months. Fourteen of 21 patients completed six months' treatment, but there was no significant improvement in the mean values of the clinical and laboratory parameters measured. The improvement suggested by preliminary studies in patients with early RA is not seen in this larger group. In patients with a disease duration of less than 18 months, however, there was a significant decrease in the erythrocyte sedimentation rate and the serum concentrations of C reactive protein after treatment for six months, although there was no significant clinical improvement. Future studies of this drug in patients with RA should concentrate on this group.",1
"Cox, N L, Prowse, M V, Maddison, M C, Maddison, P J",2
"Antibodies to histones in systemic lupus erythematosus: prevalence, specificity, and relationship to clinical and laboratory features.",0
"Antibodies to histones (AHA) are commonly found in patients with systemic lupus erythematosus (SLE). However, the full profile of AHA and their clinical associations remains unclear. A total of 111 patients with SLE were studied, including 13 patients in whom multiple serum samples were available over several years. IgM, IgG, and IgA antibodies to total core histones, histone complexes, and individual histones were determined by highly sensitive enzyme linked immunosorbent assays (ELISAs). Antibodies to histones were detected in 74% of serum samples, though only at low levels in half of these. Antibodies to each of the individual histones (H1, H2A, H2B, H3, H4) occurred with similar frequencies except for IgG and IgA antibodies to H4, which were uncommon. In contrast, antibodies to the histone complexes H2A-H2B and H3-H4 were detected in only two serum samples and thus do not appear to be a feature of SLE. All three major isotypes of AHA were common and usually occurred with similar frequencies to one another for the various histone specificities. There were few clinical or laboratory associations with AHA; the strongest was between IgG antibodies to total core histones and antibodies to native DNA. Similarly, there was no association between the presence of AHA and disease activity. However, for the patients as a group and in one patient alone, periods of SLE disease activity were associated with higher levels of AHA. Although the profile of antibodies to individual histones varied with time, no profile was identified that corresponded with any specific disease manifestations. It is concluded from this study that although AHA are common in patients with SLE, their clinical value in this syndrome must, at present, be considered limited.",1
"Cohen, M G, Pollard, K M, Webb, J",2
Relation between creatinine and uric acid excretion.,0
"The relation between creatinine and uric acid metabolism was analysed in 77 male patients with primary gout and 62 healthy male subjects. Significant positive correlations between 24 hour urinary creatinine and uric acid excretion were shown in both groups. The mean urinary creatinine and uric acid excretions in the patients with gout were significantly increased as compared with those of normal male controls. These results suggest that there is a close correlation between creatinine and uric acid synthesis. In addition, it seems that accelerated uric acid synthesis seen in some patients with gout is due to increased creatinine synthesis.",1
"Nishida, Y",2
Computerised infrared thermography and isotopic bone scanning in tennis elbow.,0
"Thirty five cases of tennis elbow (17 unilateral, nine bilateral) were studied with infrared thermography and isotopic bone scanning. A hot focus was visualised in 16 of 17 cases of unilateral tennis elbow (94%) and in all nine cases of bilateral tennis elbow (100%) on infrared thermography, and abnormal increased epicondylar activity seen in 12 of 17 (71%) and eight of 18 (44%) cases respectively with isotopic bone scanning. Unilateral visual cooling (somatosympathetic responses) occurred in seven of 13 cases of unilateral tennis elbow (54%) with infrared thermography, and reduced perfusion in seven of 12 (58%) of similar cases with blood pool isotopic bone scanning. Computerised temperature assessments showed statistically significant side to side temperature differences when 17 active tennis elbows were compared with the opposite normal elbows for spot temperatures, proximal and distal forearm gradients. Similar temperature assessments in 18 bilateral tennis elbows compared with 17 normal elbows showed significant temperature differences for elbow spot temperatures and distal forearm gradients, but not for proximal gradients.",1
"Thomas, D, Siahamis, G, Marion, M, Boyle, C",2
Systemic lupus erythematosus complicated by tricuspid stenosis and regurgitation: successful treatment by valve transplantation.,0
Clinical tricuspid stenosis has not previously been reported in patients with systemic lupus erythematosus (SLE). A 25 year old woman with active SLE presented with signs of severe right ventricular failure. Cardiac catheterisation confirmed the diagnosis of tricuspid stenosis and regurgitation together with mitral regurgitation. This patient underwent successful tricuspid and mitral valve replacement.,1
"Ames, D E, Asherson, R A, Coltart, J D, Vassilikos, V, Jones, J K, Hughes, G R",2
Recovery from pulmonary hypertension in an adolescent with mixed connective tissue disease.,0
"This paper describes the case of an 11 year old girl who presented with mixed connective tissue disease which was complicated by the development of pulmonary hypertension. This case is unique with respect to the young age of onset, the serial non-invasive method used to follow the disease process, and the favourable response to treatment with vasodilator and anti-inflammatory drugs.",1
"Friedman, D M, Mitnick, H J, Danilowicz, D",2
Systemic lupus erythematosus in men: clinical and immunological characteristics.,0
"Although systemic lupus erythematosus (SLE) has traditionally been considered a disease of women, men may also be affected. Thirty of 261 patients (12%) with SLE seen in this hospital were men. Arthritis was less common as a first symptom in the men, although this group of patients had discoid lesions and serositis more often than the women. During the follow up a lower incidence of arthritis and malar rash and a higher incidence of other skin complications including discoid lesions and subcutaneous lupus erythematosus was found in the men. The incidence of nephropathy, neurological disease, thrombocytopenia, vasculitis, and serositis, was similar in the two groups. No significant immunological differences were found between men and women. These features indicate that several gender associated clinical differences may be present in patients with SLE.",1
"Font, J, Cervera, R, Navarro, M, Pallarés, L, López-Soto, A, Vivancos, J, Ingelmo, M",2
Autoantibodies in chronic arthritis of childhood: relations with each other and with histocompatibility antigens.,0
"Studies have shown the presence of either antibodies to histone or anticardiolipin antibodies in some forms of childhood chronic arthritis. The relation between these autoantibodies has not been previously reported, however, and the immunogenetics of their association with childhood arthritis has not been studied.",1
"Malleson, P N, Fung, M Y, Petty, R E, Mackinnon, M J, Schroeder, M L",2
Impact of disablement due to rheumatic disorders in a British population: estimates of severity and prevalence from the Calderdale Rheumatic Disablement Survey.,0
"A survey of rheumatic disablement in the population has enabled the comparative impact of self reported causes of disability to be studied. One in three households in Calderdale, West Yorkshire, United Kingdom was screened in 1986 with a postal questionnaire (87% response rate), followed by in depth interviews with a sample of subjects reporting disability in conjunction with a rheumatic disorder (608 interviews). Severity of disablement was assessed using the physical independence handicap classification. The estimated prevalence of disability in conjunction with reported rheumatic disorders is 82/1000 population aged at least 16 years (95% confidence interval (CI) 77 to 87). Arthritis (mainly osteoarthritis) is the most commonly reported cause (47/1000 population; 95% CI 43 to 51), followed by back or neck disorders (25/1000; 95% CI 23 to 28), soft tissue disorders (18/1000; 95% CI 15 to 20), and rheumatoid arthritis (RA) (4/1000; 95% CI 3 to 5). A total of 30% reported more than one category of rheumatic disorder (mean number 1.3) and 63% reported non-rheumatic comorbidity. Current joint symptoms were reported by 98%, current antirheumatic drugs (including analgesics) by 70%, and severe pain by 62%. Overall 82% of subjects had seen their general practitioner in the past year, and 71% reported having attended an outpatient clinic; 26% reported current outpatient clinic attendance, and 15% a hospital inpatient stay during the previous year. Forty six per cent reported some dependence, with 12% reporting being dependent on a daily basis. Rheumatoid arthritis was the most disabling disorder with 73% dependent. Taking into account prevalence, osteoarthritis and back disorders are the most, and RA the least, common causes of dependence and incapacitating pain in the population. This challenges stereotypes and raises questions about the organisation and priorities for specialist services and for research.",1
"Badley, E M, Tennant, A",2
Synergism between muramyl dipeptide and lipopolysaccharide in the inhibition of glycosaminoglycan synthesis in cultured rat costal chondrocytes.,0
"The effect of synthetic muramyl dipeptide on glycosaminoglycan synthesis in cultured rat costal chondrocytes was examined. Muramyl dipeptide alone had no effect on the glycosaminoglycan synthesis of rat chondrocytes, whereas Escherichia coli lipopolysaccharide and interleukin 1 alpha inhibited glycosaminoglycan synthesis in a dose dependent manner. Muramyl dipeptide, when added to chondrocyte cultures in the presence of lipopolysaccharide, enhanced the lipopolysaccharide induced inhibition of glycosaminoglycan synthesis in a dose dependent manner. Adjuvant active analogues of muramyl dipeptide, but not adjuvant inactive analogues, also enhanced the lipopolysaccharide induced inhibition of glycosaminoglycan synthesis. In combination with muramyl dipeptide, to inhibit glycosaminoglycan synthesis, lipopolysaccharide could be replaced with the synthetic lipid A, an active principle of lipopolysaccharide. These results show that the muramyl dipeptide portion of bacterial peptidoglycan enhances the susceptibility of rat chondrocytes to the lipid A portion of bacterial lipopolysaccharide, and therefore the interaction between chondrocytes and bacterial cell wall components might be involved in damaging the cartilage in inflammatory joint diseases.",1
"Ikebe, T, Hirata, M, Yanaga, F, Koga, T",2
Paget's disease of bone treated with a five day course of oral tiludronate.,0
"Chloro-4-phenyl thiomethylene bisphosphonate (tiludronate) is a new drug which can be used as an inhibitor of bone resorption. As it remains in bone for a long time, and as mineralisation defects have only been seen at doses much higher than those required to decrease osteoclastic activity, it could be given at high doses over a short period of time. Eighteen patients with Paget's disease of bone were randomly allocated to three therapeutic groups receiving respectively 600, 800, and 1200 mg/day tiludronate for five days. Serum alkaline phosphatase activity and the urinary hydroxyproline/creatinine ratio were quickly and drastically reduced in all three groups. A significant reduction of serum alkaline phosphatases and the hydroxyproline/creatinine ratio was still present six months after the five day therapeutic course, reflecting a sustained activity of tiludronate even after stopping treatment. Dose dependent short and long term reductions of bone turnover rate were observed. Biochemical assessment of haematological, renal, or hepatic tolerance did not show any toxicity of tiludronate. Fifty per cent of patients treated by a dose of 1200 mg/day reported gastrointestinal disturbances, however, making this dosage unsuitable for clinical practice.",1
"Reginster, J Y, Lecart, M P, Deroisy, R, Ethgen, D, Zegels, B, Franchimont, P",2
Acquired Brown's syndrome in a patient with systemic lupus erythematosus.,0
"A 27 year old woman with systemic lupus erythematosus (SLE) developed vertical diplopia with an apparent bilateral inferior oblique muscle palsy, resulting in a limitation of elevation of the globe in adduction. It resolved with systemic steroid treatment. A transient tenosynovitis affecting the superior oblique tendons was the probable underlying pathological mechanism. This is the first described case of Brown's syndrome associated with SLE.",1
"Alonso-Valdivielso, J L, Alvarez Lario, B, Alegre López, J, Sedano Tous, M J, Buitrago Gómez, A",2
Antinuclear antibodies in routine analysis: the relevance of putative clinical associations.,0
"Defined antinuclear antibodies (ANA), such as antibodies to Ro/SS-A, La/SS-B, Sm, and nRNP, are often present in serum samples from patients with systemic lupus erythematosus (SLE) or other connective tissue diseases (CTD). Most data on associations between the presence of these antibodies and defined disease features have been obtained with the use of predefined groups of patients. In this work the issue of disease associations was approached from a different angle: patients suspected of having CTD were selected on the presence of these ANA in their serum samples and clinical data were subsequently scored according to a defined protocol. It was then tried to relate measured ANA and clinical symptoms. No correlation was observed between the presence of antibodies to Ro/SS-A and specific clinical symptoms. The presence of antibodies to La/SS-B was associated with the diagnosis of Sjögren's syndrome combined with leukocytopenia. In patients positive for antibodies to Sm a significantly increased incidence of skin lesions, such as butterfly rashes and discoid lesions, was seen, together with signs of myocarditis. Myocarditis was also found to be associated with the presence of antibodies to nRNP. The data presented in this study show that previously reported associations of these ANA with clinical symptoms are not confirmed when unselected patients are used.",1
"Swaak, A J, Huysen, V, Smeenk, R J",2
Possible clearance of effete polymorphonuclear leucocytes from synovial fluid by cytophagocytic mononuclear cells: implications for pathogenesis and chronicity in inflammatory arthritis.,0
"A feature common to all forms of chronic inflammatory arthritis, irrespective of the possible underlying cause, is the persistent exudation of large numbers of polymorphonuclear leucocytes (PMNL) into synovial fluid. These cells possess potent degradative enzymes and proinflammatory mediators, and their removal is vital to normal inflammatory resolution. A major route of disposal of extravasated PMNL appears to be programmed cell death (apoptosis), followed by their rapid recognition, and intact phagocytosis, by mature tissue macrophages. Such macrophages, containing PMNL (cytophagocytic mononuclear cells (CPM)), long recognised in synovial fluid as Reiter cells, are commonly found in reactive arthritis, spondyloarthritis, and crystal arthritides, but only rarely in rheumatoid disease. In a retrospective analysis of 187 knee synovial fluid cytospins, the relation between the formation of CPM and the presence of apoptotic (pyknotic) PMNL was investigated. As long as the synovial fluid examined was fresh there was a high correlation between numbers of CPM (as a percentage of macrophages) and pyknotic numbers of PMNL in fluids containing CPM. This suggests that the formation of CPM occurs in vivo and is involved in the disposal of PMNL. Numbers of pyknotic PMNL increased rapidly in stored synovial fluid without a significant change in numbers of CPM, and were highest in synovial fluid which did not contain CPM. The presence or absence of CPM, or their disease associations, could not be explained simply by limiting numbers of macrophages, or apoptotic PMNL in synovial fluid. These findings are consistent with a regulatory role for CPM in synovial fluid, where they may be important in preventing autolysis of PMNL, and thus local tissue damage.",1
"Jones, S T, Denton, J, Holt, P J, Freemont, A J",2
Methotrexate osteopathy in rheumatic disease.,0
To determine whether two adults with stress fractures receiving low weekly doses of methotrexate had methotrexate osteopathy.,1
"Preston, S J, Diamond, T, Scott, A, Laurent, M R",2
Patients with antiphospholipid antibodies and venous thrombosis should receive long term anticoagulant treatment.,0
To determine whether the finding of antiphospholipid antibodies in patients with venous thromboembolic episodes should influence the duration of treatment with anticoagulant drugs by mouth.,1
"Derksen, R H, de Groot, P G, Kater, L, Nieuwenhuis, H K",2
A double blind randomised trial of low power laser treatment in rheumatoid arthritis.,0
To define the value of low power laser treatment in small joint rheumatoid arthritis.,1
"Heussler, J K, Hinchey, G, Margiotta, E, Quinn, R, Butler, P, Martin, J, Sturgess, A D",2
Hydroxychloroquine and sulphasalazine alone and in combination in rheumatoid arthritis: a randomised double blind trial.,0
To compare the effects of hydroxychloroquine and sulphasalazine alone and in combination in rheumatoid arthritis.,1
"Faarvang, K L, Egsmose, C, Kryger, P, Pødenphant, J, Ingeman-Nielsen, M, Hansen, T M",2
Effects of methotrexate on glycosaminoglycan production by scleroderma fibroblasts in culture.,0
To determine the effects of increasing concentrations of methotrexate on the proliferation and glycosaminoglycan (GAG) synthesis of cultured dermal fibroblasts from patients with scleroderma.,1
"van den Hoogen, F H, van der Kraan, P M, Boerbooms, A M, van den Berg, W B, van Lier, H J, van de Putte, L B",2
Complement activating properties of monoreactive and polyreactive IgM rheumatoid factors.,0
"To estimate the complement activating properties of monoclonal, monoreactive, and polyreactive IgM rheumatoid factors derived from Epstein-Barr virus transformed B cells isolated from peripheral blood and synovial tissue of patients with rheumatoid arthritis (RA).",1
"Sato, Y, Sato, R, Watanabe, H, Kogure, A, Watanabe, K, Nishimaki, T, Kasukawa, R, Kuraya, M, Fujita, T",2
Release of cartilage oligomeric matrix protein (COMP) into joint fluid after knee injury and in osteoarthritis.,0
The release of fragments of cartilage oligomeric matrix protein (COMP) and aggrecan into knee joint fluid and serum after joint injury and in post-traumatic and primary osteoarthritis was monitored in a cross-sectional study.,1
"Lohmander, L S, Saxne, T, Heinegård, D K",2
Rotator cuff degeneration and lateral epicondylitis: a comparative histological study.,0
"Rotator cuff tendinitis and lateral epicondylitis are common in clinical practice but the underlying pathology is poorly understood. The study examined both normal and biopsy tendon specimens histologically, to determine the mechanisms involved in tendon degeneration.",1
"Chard, M D, Cawston, T E, Riley, G P, Gresham, G A, Hazleman, B L",2
Chlamydia pneumoniae--a new causative agent of reactive arthritis and undifferentiated oligoarthritis.,0
"To examine whether reactive arthritis (ReA) known to occur after a urogenital infection with Chlamydia trachomatis can also follow an infection with Chlamydia pneumoniae, a recently described species of Chlamydiae that is a common cause of respiratory tract infections.",1
"Braun, J, Laitko, S, Treharne, J, Eggens, U, Wu, P, Distler, A, Sieper, J",2
A randomised controlled trial of the effect of hormone replacement therapy on disease activity in postmenopausal rheumatoid arthritis.,0
To assess the effects of hormone replacement therapy (HRT) on disease activity in postmenopausal rheumatoid arthritis (RA).,1
"Hall, G M, Daniels, M, Huskisson, E C, Spector, T D",2
Rheumatoid-susceptible alleles of HLA-DRB1 are genetically recessive to non-susceptible alleles in the progression of bone destruction in the wrists and fingers of patients with RA.,0
To assess the relationship between HLA-DRB1 genotypes and the progression of bone destruction in Japanese patients with RA.,1
"Toda, Y, Minamikawa, Y, Akagi, S, Sugano, H, Mori, Y, Nishimura, H, Arita, S, Sugino, Y, Ogawa, R",2
The European Community Study Group on diagnostic criteria for Sjögren's syndrome. Sensitivity and specificity of tests for ocular and oral involvement in Sjögren's syndrome.,0
"To establish a definitive set of diagnostic criteria in a multicentre European study a selected number of oral and ocular tests were performed on a large number of patients with Sjögrens Syndrome (SS) and controls. The diagnostic accuracy of each test for patients with primary and secondary SS and for controls at different ages, was studied.",1
"Vitali, C, Moutsopoulos, H M, Bombardieri, S",2
Serum transferrin receptors in rheumatoid arthritis.,0
Serum transferrin receptors (sTfR) were determined in patients affected by rheumatoid arthritis (RA) to verify a possible relationship with the degree of anaemia and with the severity of the inflammatory disease.,1
"Zoli, A, Altomonte, L, Mirone, L, Magaró, M, Ricerca, B M, Storti, S, Candido, A, Bizzi, M",2
Sociodemographic factors and the outcome of rheumatoid arthritis in young women.,0
To investigate the impact of sociodemographic factors on the outcome of rheumatoid arthritis (RA).,1
"Vliet Vlieland, T P, Buitenhuis, N A, van Zeben, D, Vandenbroucke, J P, Breedveld, F C, Hazes, J M",2
"Immunolocalisation studies on six matrix metalloproteinases and their inhibitors, TIMP-1 and TIMP-2, in synovia from patients with osteo- and rheumatoid arthritis.",0
To assess the likely importance of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in the arthritic process.,1
"Hembry, R M, Bagga, M R, Reynolds, J J, Hamblen, D L",2
Radiolabelled lymphocyte migration in rheumatoid synovitis.,0
"To study the ability of technetium-99m hexamethyl propylene amineoxime (HMPAO) labelled lymphocyte scintigraphy to quantify synovial inflammation, and to analyse the kinetics of lymphocyte retention in the joints of patients with rheumatoid arthritis (RA).",1
"Jorgensen, C, Couret, I, Bologna, C, Rossi, M, Sany, J",2
Prevalence and clinical features of lumbar zygapophysial joint pain: a study in an Australian population with chronic low back pain.,0
To determine the prevalence of pain arising from the zygapophysial joint in patients with chronic low back pain and to determine whether any clinical features could distinguish patients with and without such pain.,1
"Schwarzer, A C, Wang, S C, Bogduk, N, McNaught, P J, Laurent, R",2
Treatment of carrageenan induced arthritis by the platelet activating factor antagonist BN 50730.,0
To evaluate the role of platelet activating factor (PAF) in the early stage of arthritis.,1
"Hilliquin, P, Natour, J, Aissa, J, Guinot, P, Laoussadi, S, Benveniste, J, Menkes, C J, Arnoux, B",2
Neovascularisation and the induction of cell adhesion molecules in response to degradation products from orthopaedic implants.,0
To characterise the cellular interactions and the mechanisms involved in the recruitment of inflammatory macrophages and T cells to the bone implant interface in 30 patients with aseptically loosened orthopaedic prostheses.,1
"al-Saffar, N, Mah, J T, Kadoya, Y, Revell, P A",2
Gold induced nephropathy in rheumatoid arthritis and HLA class II genes.,0
"To elucidate the role of HLA-DRB, -DQA, and -DQB genes in patients with rheumatoid arthritis (RA) who developed gold induced nephropathy.",1
"Sakkas, L I, Chikanza, I C, Vaughan, R W, Welsh, K I, Panayi, G S",2
Experimental arthritis in rats induced by intra-articular injection of IgE aggregates: evidence for arthritogenic role of complexed IgE.,0
"An experimental arthritis model in the rat was used to study the arthritogenic potential of complexed IgE. IgE aggregates were produced in vitro by cross linking monoclonal rat IgE by dimethyl suberimidate and were injected into the knee joints. Animals which had not been injected and animals injected with phosphate buffered saline served as controls. The concentration of histamine in tissues, diffusion into the joint of bovine serum albumin labelled with iodine-125 injected intravenously, and the histology of the joints were studied. There was a significant decrease in the concentration of histamine in synovial tissue 8 and 24 hours after the injection of the IgE aggregates. A decreased number of stainable mast cells were found 8, 24, and 48 hours after exposure. A moderate hyperplasia of the synovial lining layer was also noted. These results provide further evidence for the arthritogenic potential of complexed IgE, especially in the initiation of arthritis through activation of mast cells.",1
"de Clerck, L S, Struyf, N J, Bridts, C H, van Marck, E A, Breedveld, F C, Devries, E, Bazin, H, Stevens, W J",2
Differential metabolism of 25-hydroxyvitamin D3 by cultured synovial fluid macrophages and fibroblast-like cells from patients with arthritis.,0
"Differential metabolism of 25-hydroxyvitamin D3 (25(OH)D3) has been shown for macrophages and fibroblast-like cells (possibly synoviocytes) cultured for two to 50 days after isolation from the synovial fluid of 12 patients with various forms of inflammatory arthritis. Macrophages synthesised the active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the synthesis of which was increased by bacterial lipopolysaccharide, a known macrophage activating factor. In contrast, fibroblast-like cells formed 24, 25-dihydroxyvitamin D3 (24,25(OH)2D3), synthesis of which was stimulated by 1,25(OH)2D3 and inhibited by lipopolysaccharide. The synthesis of 1,25(OH)2D3 and 24,25(OH)2D3 by macrophages and fibroblast-like cells respectively was inhibited by ketoconazole, indicating that both hydroxylases are dependent on cytochrome P-450. Mean (SEM) synovial fluid and serum 25(OH)D3 concentrations were 16.7 (1.7) and 22.2 (2.6) ng/ml and those of 1,25(OH)2D3 were 29.4 (4.8) and 43.3 (4.0) pg/ml respectively. In most cases concentrations were lower in synovial fluid than in paired serum samples, but in two patients 1,25(OH)2D3 concentrations were greater in synovial fluid than in serum, suggesting local synthesis within the affected joints.",1
"Hayes, M E, Bayley, D, Still, P, Palit, J, Denton, J, Freemont, A J, Cooper, R G, Mawer, E B",2
Rheumatoid synovitis and joint disease. Relationship between arthroscopic and histological changes.,0
"Arthroscopic and histological synovial features have been studied in forty-two patients with classical or definite rheumatoid arthritis. A total index of disease activity as judged arthroscopically correlates significantly with a total index of histological activity. In those patients who have dense, waxy looking villi, the intensity of the villus-proliferation is associated with lymphocytic infiltration of the synovium. No relationship between synovial lining cell proliferation and cartilage disease nor between sparsity of lymphocyte infiltration and cartilage disease could be established.",1
"Yates, D B, Scott, J T",2
Lack of correlation of synovial histology with joint damage in rheumatoid arthritis.,0
"Twenty-two patients with rheumatoid arthritis (RA) involving the knee were studied. The systemic features of the disease were graded and the extent of knee involvement was quantified in terms of the clinical, radiological, and arthroscopic appearances. Adequate synovial biopsies were obtained from 21 patients. In these patients no correlation could be found between the severity of any of the features on histological examination nor between any of these features and the extent of local joint damage, inflammation, or the severity of the systemic disease.",1
"Henderson, D R, Jayson, M I, Tribe, C R",2
"Development of periarticular osteophytes in experimentally induced osteoarthritis in the dog. A study using microradiographic, microangiographic, and fluorescent bone-labelling techniques.",0
"(1) The development of periarticular osteophytes in experimental osteoarthritis in the dog degins as early as 3 days after induction of the disease process. (2) Development of the osteophytes is still proceeding 48 weeks after induction. (3) The common site for development of the osteophyte is at the marginal zone where synovial membrane merges with fibrocartilage. (4) At this site the osteophyte begins as a deposition of outside the existing femoral bone cortex. (5) Further deposition of new bone and resorption lead to a remodelling which ultimately produces a mature osteophyte having a trabecular bone structure and free communication with the bone marrow spaces of the femur. (6) In some dogs there is also hyperplasia of bone with remodelling which takes place beneath the cartilage of the nonarticulating face of the trochlear ridge. This develops a mature trabecular structure later in the disease process and may become confluent with the osteophyte at the marginal zone. (7) The bone changes are not confined to development of the osteophyte. The whole distal end of the femur appears to have a marked increase in bone turnover, and there is also evidence of increased bone metabolism in the contralateral limb. (8) Dye injection techniques have shown that an increase in vascularity is associated with this development of new bone, and it is suggested that the results indicate the possible importance of a vascular component in the pathogenesis of osteoarthritis.",1
"Gilbertson, E M",2
Development with age of human articular cartilage surface structure. A survey by interference microscopy of the lateral femoral condyle.,0
"The weight-bearing surfaces of the lateral femoral condyles taken from twenty normal human cadavers aged 0-47 years have been examined by reflected light interference microscopy (RLIM) and by scanning electron microscope (SEM). The surfaces appeared normal by naked eye examination. The presence of both 200-400 mum diameter secondary undulations and small ovoid 20-45 mum diameter tertiary hollows was confirmed in all specimens using both techniques. Measurements by RLIM showed that the tertiary hollows increase significantly in depth and diameter with increasing age. A further order of quaternary surface irregularities was shown. Small irregular ridges, 130-275 nm deep and 1-4 mum diameter, were found with increasing frequency on specimens obtained from persons aged 21 years. These quaternary irregularities are thought to be due to exposure of superficial fibre bundles after the loss, with age, of surface ground substance.",1
"Longmore, R B, Gardner, D L",2
Liver disease in rheumatoid arthritis and Sjøgren's syndrome. Prospective study using biochemical and serological markers of hepatic dysfunction.,0
"Inter-relationships of biochemical and immunological tests of liver function have been studied in a prospective study of 216 patients with rheumatoid arthritis (RA), 32 patients with Sjogren's syndrome, and 27 patients with the sicca syndrome, and these results have been compared with those obtained 289 patients with osteoarthrosis or with a form of seronegative polyarthropathy. In general the prevalence of abnormalities in serum alkaline phosphatase, bromsulphthalein excretion, smooth muscle antibody, and mitochondrial antibody in the former three groups was higher than in patients with osteoarthrosis. Patients with Sjogren's syndrome with RA had a higher prevalence of abnormalities of bromsulphthalein excretion, salivary duct antibody than patients with the sicca syndrome. Patients with RA had a higher pervalence of rheumatoid factor than those with the sicca syndrome. Patients with a positive smooth muscle or mitochondrial antibody were found to have a higher prevalence of hepatomegaly and splenomegaly, of abnormal liver function tests, of other autoantibodies, and of histological abnromalitis of liver than those in whom these tests were negative.",1
"Webb, J, Whaley, K, MacSween, R N, Nuki, G, Dick, W C, Buchanan, W W",2
Transformation of human lymphocytes in vitro by autologous and allogeneic rheumatoid synovial fluids.,0
"To assess the possible participation of cellular immune mechanisms in the pathogenesis of rheumatoid arthritis (RA) in vitro studies of the blastogenicity of rheumatoid and non-rheumatoid synovial fluids for human peripheral blood lymphocytes were conducted. In autologous cultures it was found that 13 of 19 rheumatoid fluids induced significant lymphocyte blastogenesis, whereas only 1 of 13 nonrheumatoid fluids induced such a response. In allogeneic cultures rheumatoid fluids induce significant blastogenesis of RA lymphocytes in 18 of 23 experiments, and of non-RA lymphocytes in 8 of 18 experiments. By contrast, nonrheumatoid fluids induced significant blastogenesis of RA lymphocytes in 2 of 13 experiments, and of non-RA lymphocytes in 1 of 14 experiments. The blastogenicity of fluids was found to correlate significantly with the presence therein of immunofluorescent intracellular inclusions of immunoglobulin and complement. These studies support the concept that the presence of immune complexes in the majority of rheumatoid synovial fluids might render the latter blastogenic for human lymphocytes in vivo, thereby perpetuating rheumatoid synovitis.",1
"Kinsella, T D",2
Antibody-mediated leucocyte cytotoxicity to Chang human liver cells in rheumatoid arthritis and other diseases.,0
"The incidence of an IgG-antibody which induces lymphocyte cytotoxicity to Chang human liver cells in culture was estimated in the sera of patients with rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, psoriatic arthritis, Crohn's disease, ulcerative colitis, and in healthy controls. It was found in 4.1% of control subjects and in 31% of patients with rheumatoid arthritis. None of the other patient groups differed from the control group. This may be the first demonstration of an antibody response to an antigen or antigens which is almost entirely confined to patients with rheumatoid arthritis. The possibility that an antigenic similarity exists between the rheumatoid synovial membrane and Chang cells is currently under investigation.",1
"Panayi, G S",2
Synthesis of glycosaminoglycan in adult human articular cartilage in organ culture from patients with rheumatoid arthritis.,0
"Hyaline cartilage was obtained from patients undergoing synovectomy of the knee joint for rheumatoid arthritis. Eroded cartilage from beneath the invading pannus and relatively normal cartilage from the same joint were maintained in organ culture for three days. During the first 48 hours in culture the explants were exposed to 35SO4 in the medium. The equivalent layers of normal and eroded cartilage were analysed for DNA uronic acid and 35SO4 incorporation. There was a decrease in the DNA and uronic acid of the eroded cartilage, although only the latter reached statistical significance. The uptake of radioactive sulphate was significantly greater in explants taken from the eroded site than from normal areas. This increase in metabolic activity could well be a protective phenomenon.",1
"Jacoby, R K, Jayson, M I",2
"Diminished mixed lymphocyte reaction in ankylosing spondylitis, relatives, and normal individuals all with HL-A 27.",0
"The mixed lymphocyte reaction against a pool of blocked lymphocytes was studied in individuals with and without HL-A 27, including controls, spouses, parents, sibs, and offspring, and patients with ankylosing spondylitis. In controls without HL-A 27 the mean increment of counts perminute was 46,630 compared with 29,860 in asymptomatic controls and relatives with HL-A 27 and 26,277 in spondylitic patients with HL-A 27. The mean response was also reduced to 34,902 in sibs and offspring without HL-A 27, and to 20,916 in three patients with spondylitis in the absence of HL-A 27.",1
"Nikbin, B, Brewerton, D A, James, D C, Hobbs, J R",2
"Serum immunoreactive gastrin: specificity for rheumatoid arthritis, bimodality of distribution, and failure of effect of anti-inflammatory drugs.",0
"A significant rise in immunoreactive gastrin in a proportion of patients with rheumatoid arthritis is confirmed. Such a rise does not seem to occur in other inflammatory or tissue destructive diseases. The patients with raised immunoreactive gastrin appear to form a separate population but the factors determining this separation remain obscure. Anti-inflammatory drugs, at least during short-term administration have no influence on immunoreactive gastrin concentrations.",1
"Rooney, P J, Grennan, D M, Sturrock, R D, Brooks, P M, Dick, W C",2
Post-mortem study of the hip joint. III. Correlations between observations.,0
"Correlations between alterations in hip joints, described in a post-mortem study, have established the independence of limited and progressive alterations, and in addition have shown that there is a weak association between limited alterations and osteophytes and a strong one between progressive alterations and osteophytes. Nevertheless limited alterations may rarely undergo progressive damage. Cysts relate strongly to osteophytes but only moderately with progressive alterations. Limited alterations of both head and acetabulum can be subdivided. Some implications of these findings are discussed.",1
"Byers, P D, Contepomi, C A, Farkas, T A",2
Detection of IgG rheumatoid factor by concanavalin A treatment and complement fixation with IgG rheumatoid factor.,0
"Concanavalin A (Con A) froms precipitates with carbohydrate-rich protein such as IgM, IgD, IgE, and IgA. Since IgG contains little carbohydrate and does not react with Con A, the activity of IgG-rheumatoid factor (RF) can be measured in the supernate of the Con A-treated serum. When the latex fixation test (LFT) and the sensitized sheep cell agglutination test (SSCA) were perfromed in the supernate for the detection of IgG-RF, LFT was positive in 32-1% of sera, out of 137 sera originally positive for LFT, and SSCA was positive in 18-5% of sera, out of 119 sera originally positive for SSCA. IgG-RF exhibited lower complement fixing ability than IgM-RF and correlated with agglutination titres of IgG-RF, while the CH50 of the original serum did not correlate with haemolytic activities of either IgM-RF or IgG-RF.",1
"Tanimoto, K, Moritoh, T, Azuma, T, Horiuchi, Y",2
Rubella virus and rheumatoid arthritis.,0
A collection of synovial fibroblasts from 19 patients with rheumatoid arthritis (RA) and 12 patients with osteoarthrosis or other non-RA disease has been examined for rubella virus antigens by immunofluorescence and radioimmunoassay with negative results. Eluates of synovial membrane prepared under conditions likely to dissociate antigen-antibody complexes have shown no rubella antibody. A serological survey of RA patients and those with other forms of arthritis has shown no differences in the frequency or levels of rubella haemagglutination-inhibiting antibody. These results provide little support for various hypotheses that a persistent infection with rubella virus underlies or initiates the rheumatoid process.,1
"Hart, H, Marmion, B P",2
Is persisting antigen responsible for the chronicity of experimental allergic arthritis?,0
"Animals were injected intra-articularly with antigen after prior immunization with that antigen in Freund's incomplete adjuvant in order to precipitate immune complexes in the surfaces of menisci, ligaments, and cartilage. On reimmunization with antigen in Freund's complete adjuvant 10 weeks later, generally an arthritis limited to the intercondylar fossa developed; but on intra-articular injection of antigen a second time a widespread arthritis developed in that joint. Thus immune deviation had not occurred and animals were in an immunological condition such as to be capable of developing widespread arthritis given the correct intra-articular stimulus. It is concluded that antigen, persisting as immune complexes, plays no part in maintaining widespread monarthritis, presumably owing to its inability to participate in a delayed hypersensitivity reaction as a result of sequestration.",1
"Fox, A, Glynn, L E",2
Somatomedin activity in synovial fluid.,0
"Abnormalities of synovial fluid, as a lubricant and nutrient, may have relevance to the causation of certain articular diseases. The somatomedin activity in normal synovial fluid obtained from the knee joint of the ox has been studied and compared with the activity in serum from the same animal. The porcine costal cartilage bioassay of Van den Brande and Du Caju (1974) has been used with the isotopes 35S-sulphate and 3H-thymidine. The mean potency ratio of ox synovial fluid in terms of ox serum for 35S-sulphate incorporation was 0-28 (range 0-19-0-47) and for 3H-thymidine incorporation 0-35 (range 0-21-0-63). A significant correlation was found between the somatomedin activity (as measured by 35S-sulphate incorporation) and the total protein and albumin concentrations in the ox synovial fluids and the ox sera, but there was no significant relationship between the somatomedin potency ratios and the globulin concentrations. The possible relevance of these findings to injury and disease in synovial joint is discussed.",1
"Coates, C L, Burwell, R G, Buttery, P J, Walker, G, Woodward, P M",2
Palindromic rheumatism. Clinical and serum complement study.,0
"A review of 39 patients diagnosed as suffering from palindromic rheumatism showed that 17 cases had evolved into typical rheumatoid arthritis (RA), while 22 had remained palindromic. The pattern of palindromic attacks in the two groups gave no grounds for regarding palindromic rheumatism as a separate condition from RA with palindromic onset. At the first attendance minor clinical or radiological changes, raised erythrocyte sedimentation rate, and positive serology were more common along those patients who were about to develop the picture of RA. Rheumatoid disease developing in patients with a palindromic onset was at least as severe as that among other patients with RA. 5 patients gave a history suggestive of fluid retention during the palindromic episodes, suggesting that attacks might be related to circulating immune complexes and altered vascular permeability. However, samples of blood obtained from 6 patients both during and between attacks showed no reduction in any of a variety of complement components tested.",1
"Wajed, M A, Brown, D L, Currey, H L",2
Effect of intra-articular corticosteroid injections on primate cartilage.,0
"An attempt was made to ascertain whether intra-articular corticosteroids exert a harmful effect on primate cartilage. The knee joints of 10 Macaca irus monkeys were subjected to either one, two, or six injections of 20 mg methyl prednisolone or an equal number of control injections over a 12-week period. Minor degenerative changes of many femoral condyles were shown by India ink staining and by a system of histochemical grading. Changes in the joints injected with corticosteroid were not significantly different from those seen in control joints. The findings were in striking contrast to the severe degeneration reported by others in rabbit joints injected with corticosteroid. The experiment did not support the contention that intra-articular corticosteroids invariably have a deleterious effect on primate cartilage.",1
"Gibson, T, Burry, H C, Poswillo, D, Glass, J",2
Cathepsin B as a marker of the dedifferentiated chondrocyte phenotype.,0
"Rabbit articular cartilage does not secrete cathepsin B in organ culture. By established methods for modulating the chondrocyte phenotype in vitro, however, the synthesis, intracellular storage, and secretion of cathepsin B were followed up over a period of two months. With chondrocytes grown in monolayer cultures both the intracellular pool of the enzyme and its secretion were very small initially, but increased progressively to a factor of 110 after eight weeks. The secretion of cathepsin B was strongly depressed after transferring the cells from monolayer to collagen gel cultures. In contrast, collagenase was secreted in almost the same amounts during the whole period in both monolayer and collagen gel cultures. The cells cultured in collagen gels secreted more collagenase than those grown in monolayers. The reversible switch of cathepsin B secretion suggests that this enzyme, unlike collagenase, is a marker of the dedifferentiated chondrocyte phenotype. Cathepsin B was localised within cultured chondrocytes using antibodies raised against rabbit liver cathepsin B and shared with it many catalytic properties. Its Mr, however, was higher (34,000 compared with 27,000) and showed an unusual resistance to denaturation at neutral-alkaline pH, which may confer on this enzyme an important role in the degradation of cartilage matrix.",1
"Baici, A, Lang, A, Hörler, D, Knöpfel, M",2
Sociological and psychological predictors of STD infection in homosexual men: a study of four countries.,0
"I investigated over 600 homosexual men in four countries (Sweden, Finland, Ireland, and Australia) regarding the number of times they had contracted a sexually transmitted disease (STD) and several psychological variables including masculinity and feminity, sex role conservatism, relationships with parents, number of sexual partners, attitudes towards homosexuality, and involvement in the homosexual subculture. Using multiple linear regression in each country, it was found that 19-42% of the variance of number of times infected could be accounted for by psychosocial factors, seven of which were common to all countries. The number of sexual partners was not a significant variable in any country. These data strongly suggest that numbers of infections in homosexual men are best predicted by psychological factors, and this has considerable implications for preventative and treatment programmes for homosexuals.",1
"Ross, M W",2
Parotitis with secondary syphilis: a case report.,0
Painless swelling of the parotid salivary gland was observed in a patient presenting with secondary syphilis. This case is of special interest to venereologists and surgeons as parotitis associated with syphilis may be mistaken for common tumours of the parotid glands. A diagnosis of syphilitic parotitis should be considered in patients presenting with swollen parotid salivary glands in countries where syphilis is prevalent.,1
"Hira, S K, Hira, R S",2
Preterm labour in association with Neisseria gonorrhoeae: case reports.,0
"We describe two cases of spontaneous rupture of the membranes, followed by premature labour at 32 and 34 weeks' gestation, in association with gonococcal infection.",1
"Lacey, C J, Milne, J D",2
Automation of a flocculation test for syphilis on Groupamatic equipment.,0
"A flocculation reaction employing a cardiolipid antigen was used for syphilis screening on Groupamatic equipment in parallel with conventional screening reactions: Kolmer CF, RPCF, Kahn, Kline, and RPR. The positive samples were confirmed by FTA-200, FTA-ABS, TPI, and in some cases by TPHA. There were 5,212 known samples which had already been tested by all methods and of which 1,648 were positive, and 58,636 screened samples including 65 positives. Half of the samples in the first series were taken without anticoagulant; the remainder were collected in potassium EDTA. The percentage of false positives with the Groupamatic was about 1-4 per cent. The percentage of false negatives among positve (greater than or equal+) samples varied from 0-18 to 1-3 per cent.; on the other hand the sensitivity was less good for samples giving doubtful and/or dissociated reactions in conventional screening reactions. The specificity and sensitivity of this technique are acceptable for a blood transfusion centre. The reproducibility is excellent and the automatic reading of results accurate. Additional advantages are rapidity (340 samples processed per hour); simultaneous performance of eleven other immunohaematological reactions; no contamination between samples; automatic reading, interpretation, and print-out of results; and saving of time because samples are not filed sequentially and are automatically identified when the results are obtained. Although the importance of syphilis in blood transfusion seems small, estimates of the risk are difficult and further investigations are planned.",1
"Garretta, M, Paris-Hamelin, A, Gener, J, Muller, A, Matte, C, Vaisman, A",2
Sickle cell disease in Sicily.,0
"The chemical and physical properties of haemoglobin S derived from homozygotes for this haemoglobin in Sicily were examined, as well as some erythrocytic characteristics. Sicilian Hb S was identical to that found in USA black patients in electrophoretic mobility on both starch and citrate agar media, solubility, mechanical precipitation rate of oxyhaemoglobins, and minimum gelling concentration, as well as by peptide mapping and amino-acid analysis of all beta-chain peptides. Taken together with the presence in Sicily of African blood group markers and certain historical considerations, it seems clear that the source of Hb S in Sicily is Africa. While the clinical severity in nine Sicilian children did not seem remarkably different from the disease in the USA, the most severe and fatal complications were not seen. Mean Hb F Was 10.5% and 2,3-diphosphoglycerate (2,3-DPG) values were higher in Sicilian homozygotes than in black USA counterparts (21.79 mumol/g Hb vs 15.16). Red cell AT values were also slightly higher in Sicilian patients. The presence of concomitant thalassaemia was excluded by both family studies and globin chain synthetic ratios. In conclusion, haemoglobin S in Sicilian homozygotes is identical to Hb S found in USA blacks. Although the severity of the disease seems quite similar in both groups of patients, other erythrocytic properties were found to be different. Whether these factors influence severity remains to be elucidated.",1
"Roth, E F, Schiliro, G, Russo, A, Musumeci, S, Rachmilewitz, E, Neske, V, Nagel, R",2
Dermatoglyphic findings in Poland's syndrome.,0
The dermatoglyphs of four cases of Poland's syndrome were investigated and compared with those of previously reported cases.,1
"Atasu, M",2
"Gonadal dysgenesis in a 46,XY female mosaic for double autosomal trisomies 8 and 21.",0
"The proband was evaluated at 19 years of age because of primary amenorrhoea and, on chromosomal analysis, was found to have a 46,XY karyotype in 75% of her cells and 48,XY, +8, +21 in 25% of her cells. She appeared normal at birth and exhibited normal intellectual and physical development until puberty when secondary sexual differentiation failed. This young women showed none of the dysmorphic features associated with either trisomy 8 or trisomy 21. Her XY gonadal dysgenesis was manifested by late developmental problems of amenorrhoea, sexual infantilism, and gonadal neoplasia.",1
"Sulewski, J M, Thao-phuong-Dang, S, Ward, R L",2
A genetic study of Duchenne muscular dystrophy in West Midlands.,0
"A study of Duchenne muscular dystrophy has shown an approximate prevalence of the disease among schoolboys to be 1 in 4000. Fifty-four families were available for genetic studies. In 19 families there were further affected cases and in 34 families the index patients was an isolated case. The proportion of affected brothers was 0.22 (11 of 50). There were 142 female relatives who had a risk of 1 in 10 or worse of being carriers: 66 of these were aged under 16. As genetic counselling is being increasingly requested by these families, and expansion of genetic services is envisaged. A genetic register, with frequent contact with families by ancillary staff, similar to that in Edinburgh, is considered desirable for the West Midlands.",1
"Bundey, S",2
Risks to the offspring of patients with some common congenital heart defects.,0
"The families of 424 adult index patients with ventricular septal defect, right ventricular outflow tract obstruction, or combinations of these two abnormalities, were visited and interviewed, and whenever possible the children of index patients were examined clinically. Congenital heart defects were present in 9 of 308 children, 8 of 899 sibs, 4 of 840 parents, and 4 of 731 nephews and nieces of the index patients. The last three figures are likely to be underestimates owing to the design of the study. Comparison of pairs of affected relatives suggests that the group of lesions studied may have genetic determinants in common.",1
"Dennis, N R, Warren, J",2
Feasibility of neonatal screening for Duchenne muscular dystrophy.,0
"During the period November 1976 to September 1980, 2703 babies born in one Edinburgh hospital were screened in the neonatal period by estimation of their serum creatine kinase levels for Duchenne muscular dystrophy. Among the 2336 male babies tested, none proved to be affected and only 16 required second specimens to be obtained. Overall the false positive rate in the study was 0.78%. This study confirms that neonatal screening for Duchenne muscular dystrophy is feasible in a British hospital setting and is here most conveniently carried out on the 5th day of life along with routine testing for phenylketonuria.",1
"Skinner, R, Emery, A E, Scheuerbrandt, G, Syme, J",2
Effect of exercise on serum creatine kinase in carriers of Duchenne muscular dystrophy.,0
"In order to evaluate the effect of exercise on serum creatine kinase levels, blood samples were obtained from 17 normal females and 12 Duchenne muscular dystrophy carriers before and 9 hours after moderately strenuous exercise. The results revealed that after exercise serum creatine kinase levels may be better indicators of carrier status than resting levels. The mean serum creatine kinase levels before and after exercise, as well as the mean increases, were found to be significantly greater in Duchenne muscular dystrophy carriers than in normal control subjects.",1
"Gaines, R F, Pueschel, S M, Sassaman, E A, Driscoll, J L",2
The genetic status of mothers of isolated cases of Duchenne muscular dystrophy.,0
"Classical genetic theory, based on assumed equal mutation rates in males and females, predicts that one-third of all cases of Duchenne muscular dystrophy (DMD) in a generation are born as new mutants to non-carrier mothers. Furthermore, less than half the mothers of apparently isolated cases appear to be carriers on the basis of raised serum creatine kinase levels. We have analysed the pedigrees of 61 families of DMD boys seen in the Duke Neuromuscular Research Clinic and 45 DMD families followed at the University of Virginia. The frequency of affected boys among the next born male sibs of 37 initially isolated DMD cases in two clinic populations was significantly greater than predicted by Haldane's theory (p = 0.029) and the estimated proportion of new mutant cases in the combined clinic population of 106 families was 0.127 (SE 0.111). The absence of affected males in earlier generations in families of isolated cases may be explained in part by a high ratio of male to female stillbirths and infant deaths, which was more than three times that of the normal population in this study. These data suggest that new mutant cases are less common than expected and current predictions may underestimate genetic risks in mothers of isolated cases.",1
"Lane, R J, Robinow, M, Roses, A D",2
Dissection of the aorta in Turner's syndrome.,0
Three deaths from dissection of the aorta in a series of 157 adult women with Turner's syndrome are reported. These are greatly in excess of the numbers expected. None of the three patients had a coarctation of the aorta. One had aortic regurgitation but there was no reason to believe that the aorta in the other two patients had been subjected to unusual haemodynamic stresses. Cystic medial necrosis of the aorta was described in two patients on whom necropsies were carried out. It is concluded that there is probably a greatly increased risk of dissection of the aorta in Turner's syndrome even in the absence of any other abnormality of the aorta and aortic valve. Previously reported cases of aortic dissection in Turner's syndrome are discussed.,1
"Price, W H, Wilson, J",2
Ten genetic polymorphisms in bladder cancer.,0
"Data are presented on a group of cases of primary carcinoma of the bladder, detailing red cell surface blood group antigenic phenotypes, serum haptoglobin phenotypes, and some red cell isoenzyme phenotypes. Account is taken of the stage of the disease at presentation. The results are compared with corresponding phenotype frequencies in groups of presumed healthy persons originating either in Yorkshire or County Durham. Differences in relative incidences were found in the haptoglobin, phosphoglucomutase (PGM), and some other systems. These are both differences between all cases and controls and between particular stages at presentation and controls.",1
"Cartwright, R A, Adib, R, Appleyard, I, Coxon, J G, Glashan, R W, Richards, B, Robinson, M R, Sunderland, E, Barham-Hall, D",2
The origin of ovarian teratomas.,0
"Chromosome and enzyme markers have been studied in 21 benign ovarian teratomas from 14 patients. Markers heterozygous in the patient were completely homozygous in 52% of the teratomas and completely heterozygous in 19%. The remainder showed a mixture of the two, 10% having homozygous centromeres with some heterozygous enzyme markers and 19% having heterozygous centromeres and some homozygous enzyme markers. These results suggest that benign ovarian teratomas in the present series arise from germ cells in a number of different ways. Those with heterozygous centromeres probably arise by failure of meiosis I. Some tumours with homozygous centromeres must arise by failure of meiosis II, but because of the low level of heterozygous enzyme markers in this group a substantial number are thought to arise by duplication of a mature ovum to give an entirely homozygous genotype, genetically the female equivalent of the complete hydatidiform mole.",1
"Parrington, J M, West, L F, Povey, S",2
What is the incidence of holoprosencephaly?,0
"The incidence of holoprosencephaly with normal chromosomes has been estimated at between 1 in 16 000 and 1 in 53 394 live births. It has been found that during a 3-year period in the Bristol and Weston Health District there were six cases of holoprosencephaly, two of which were familial, and these cases are described. This represents an incidence of 1 in 5200 and during the preceding 3-year period the incidence in the same area was 1 in 14 520 births.",1
"Saunders, E S, Shortland, D, Dunn, P M",2
Concordant monozygotic twins with bilateral renal agenesis.,0
We report the unique observation of monozygotic twins concordant for bilateral renal agenesis.,1
"Yates, J R, Mortimer, G, Connor, J M, Duke, J E",2
A computerised data base for the diagnosis of rare dysmorphic syndromes.,0
A system is described for the computerised storage and retrieval of information on rare dysmorphic syndromes. The clinician can ask a microcomputer for a list of syndromes with any logical combination of physical abnormalities. A descriptive title and full references are also provided on request. Similar systems would be applicable to other medical specialties.,1
"Winter, R M, Baraitser, M, Douglas, J M",2
Discordant sex in one of three monozygotic triplets.,0
"A case is reported of monozygotic triplets, discordant for phenotypic sex, in which the female presented at birth with the features of Turner's syndrome. Chromosomal analyses showed homogeneous 46,XY karyotypes in the lymphocytes of the three sibs, while a 45,X non-mosaic chromosome constitution was detected in skin fibroblasts of the female triplet. It is suggested that mitotic non-disjunction or anaphase lag occurring early during embryonic development accounted for the occurrence of monosomy X in one cell line of the affected triplet. Previous observations of monozygotic twin pairs discordant for chromosome constitutions are reviewed.",1
"Dallapiccola, B, Stomeo, C, Ferranti, G, Di Lecce, A, Purpura, M",2
Cell surface abnormality in clones of skin fibroblasts from a carrier of Duchenne muscular dystrophy.,0
"We have previously reported that skin fibroblasts from patients with Duchenne muscular dystrophy (DMD) have a lower intercellular adhesiveness than control cells, and that cells from carriers of DMD have normal adhesiveness instead of the expected intermediate value. We have now cloned skin fibroblasts from a carrier of DMD (subject AS) who is also heterozygous for G6PD B/G6PD Mediterranean and determined the intercellular adhesiveness and G6PD phenotypes of the clones. G6PD activity was determined using the 2d-G6P/G6P ratio method. Normal cells had a percentage utilisation of 7.31% and uncloned cells from AS a value of 25.16%. Of 16 clones, 15 had normal values (mean 8.72%) while one clone was G6PD Med with a value of 57.5%. Mean intercellular adhesiveness of normal and uncloned cells from AS were 2.95 and 2.90 respectively. Of 11 clones tested, nine had normal values of adhesiveness (mean 3.1) and all these clones were G6PD B. The single G6PD Med clone had a value of 0.88, compared with 1.39 for DMD cells. We have no explanation at present for the single clone that was G6PD B but DMD-like on aggregation.",1
"Hillier, J, Jones, G E, Statham, H E, Witkowski, J A, Dubowitz, V",2
Gene mapping and chromosome 19.,0
"Chromosome 19 is currently the most fully mapped of the smaller chromosomes, with about 40 loci assigned to it (HGM8). Major inherited disorders on this chromosome include myotonic dystrophy and familial hypercholesterolaemia. Other loci include five blood groups, a cluster of apolipoprotein genes, and the receptors for insulin and polio virus. A number of cloned genes and random DNA sequences identify polymorphisms which, together with blood group and other protein polymorphisms, have been used to establish a framework for ordering the loci and estimating genetic distances. Hybrid cell lines allow loci to be assigned to one of eight different regions and a detailed genetic map of the chromosome will be possible in the near future.",1
"Shaw, D J, Brook, J D, Meredith, A L, Harley, H G, Sarfarazi, M, Harper, P S",2
"A computer programme for estimation of genetic risk in X linked disorders, combining pedigree and DNA probe data with other conditional information.",0
"A computer programme is presented for calculating the recurrence risk in X linked disorders, combining pedigree and DNA probe data with other conditional information such as carrier detection tests. The methods of computation are shown in the given examples. The programme can be used with either a single DNA probe or two 'flanking' DNA probes for both familial and isolated case pedigrees. For isolated case families the mutation rate at the disease locus can be taken into account in conjunction with the DNA probe data.",1
"Sarfarazi, M, Williams, H",2
Mouse homologues of human hereditary disease.,0
"Details are given of 214 loci known to be associated with human hereditary disease, which have been mapped on both human and mouse chromosomes. Forty two of these have pathological variants in both species; in general the mouse variants are similar in their effects to the corresponding human ones, but exceptions include the Dmd/DMD and Hprt/HPRT mutations which cause little, if any, harm in mice. Possible reasons for phenotypic differences are discussed. In most pathological variants the gene product seems to be absent or greatly reduced in both species. The extensive data on conserved segments between human and mouse chromosomes are used to predict locations in the mouse of over 50 loci of medical interest which are mapped so far only on human chromosomes. In about 80% of these a fairly confident prediction can be made. Some likely homologies between mapped mouse loci and unmapped human ones are also given. Sixty six human and mouse proto-oncogene and growth factor gene homologies are also listed; those of confirmed location are all in known conserved segments. A survey of 18 mapped human disease loci and chromosome regions in which the manifestation or severity of pathological effects is thought to be the result of genomic imprinting shows that most of the homologous regions in the mouse are also associated with imprinting, especially those with homologues on human chromosomes 11p and 15q. Useful methods of accelerating the production of mouse models of human hereditary disease include (1) use of a supermutagen, such as ethylnitrosourea (ENU), (2) targeted mutagenesis involving ES cells, and (3) use of gene transfer techniques, with production of 'knockout mutations'.",1
"Searle, A G, Edwards, J H, Hall, J G",2
Comparison of the relative levels of the 3243 (A-->G) mtDNA mutation in heteroplasmic adult and fetal tissues.,0
"In this report, levels of the 3243 A to G mtDNA mutation associated with the mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome were measured in different heteroplasmic tissues of subjects in a kindred including adults with variable clinical phenotypes and a fetus. The relative proportions of mutant mtDNA varied widely (0.03 to 0.67) between identical tissues of the six different subjects and between different tissues of the same subjects. In the one adult for whom sufficient data were available there was an apparent correlation between the distribution of mutant mtDNA and clinical presentation. A woman without neurological symptoms who died prematurely with a cardiomyopathy and lactic acidosis had higher proportions of mutant in heart (0.49, SD 0.02), skeletal muscle (0.56, SD 0.01), and liver (0.55, SD 0.12) than in other tissues studied (for example, kidney, 0.03, SD 0.01). A strikingly different result was found in a 24 week old fetus in whom there was little variation in heteroplasmy in different tissues (average proportion of mutant mtDNA in six tissues, 0.53, SD 0.02). These observations add cardiomyopathy to the growing list of presenting features of the 3243 mtDNA mutation. The unique results from the fetus suggest also that selection pressures acting on either wild type or 3243 mutant mtDNA (rather than variation from replicative segregation of the heteroplasmic mtDNA) may be responsible primarily for the variable levels of 3243 mutant mtDNA in different heteroplasmic tissues of adults.",1
"Matthews, P M, Hopkin, J, Brown, R M, Stephenson, J B, Hilton-Jones, D, Brown, G K",2
The estimation of risks from the induction of recessive mutations after exposure to ionising radiation.,0
"Since recent assessments of genetic risks from radiation have concentrated on harmful dominant effects, a quantitative assessment of risks from recessives is needed. Presumably, harmful recessives can arise at all loci coding for essential proteins (perhaps 10 000), but mutation to dominant alleles is likely to be a property of relatively few loci. While many recessives doubtless remain to be discovered, those known at present tend to have earlier and more severe effects than dominants. Induced recessive mutations can cause harm by partnership with a defective allele already established in the population; partnership with another recessive mutation induced at the same locus; the formation of homozygous descendants, that is, identity by descent; and heterozygous effects. Calculations based on a combination of data from observations on human populations and from mouse experiments suggest that an extra genetically significant dose of 1 cGy (centiGray, equivalent to 1 rad) X or gamma irradiation received by each parent in a stable population with a million liveborn offspring would induce up to 1200 extra recessive mutations. From partnership effects, about one extra case of recessive disease would be expected in the following 10 generations. Homozygosity resulting from identity by descent could not normally occur until the fourth generation after exposure but, on certain assumptions, about ten extra cases of recessive disease would be expected from this cause by the tenth generation. In the same period, about 250 recessive alleles would be eliminated in heterozygotes (that is, Muller's 'genetic deaths') given 2.5% heterozygous disadvantage. These deleterious heterozygous effects should not be combined with those of dominants, as has been done in some previous risk estimates. It is considered unlikely that many radiation induced recessives would show heterozygous advantage. Certain dominants (combined frequently at least 10(-3)) should be excluded from calculations of mutational risk because they are unlikely to be maintained by mutation.",1
"Searle, A G, Edwards, J H",2
Molecular characterisation of chromosome 4p deletions resulting in Wolf-Hirschhorn syndrome.,0
"We present three patients with Wolf-Hirschhorn syndrome with small cytogenetic deletions of 4p16. One case is a de novo translocation and two cases represent de novo deletions. Using molecular techniques we determined the extent of these deletions and attempted to ascertain parental origin. Case 1 had a deletion of 4p16.3 with a breakpoint proximal to D4S10, case 2 had a larger deletion including D4S62 in 4p16.2, and case 3 had the largest deletion which included D4S240, but not the Raf2 locus in 4p16.1. The parental origin of the deletion in case 3 was paternal; the other two cases were indeterminable. Our results show that these three deletions include the currently proposed Wolf-Hirschhorn syndrome critical region within the most distal 2 Mb of 4p16.3 and offer supportive evidence for continuous terminal deletions.",1
"Estabrooks, L L, Lamb, A N, Aylsworth, A S, Callanan, N P, Rao, K W",2
Origin of a regressed myotonic dystrophy allele.,0
"A new case of regression of the CTG copy number in the myotonic dystrophy allele was observed in a 7 year old boy. His affected father had an expanded allele of about 100 repeats in his lymphocyte DNA while the child showed a 60 repeat allele, of the same size as the present in the grandfather. Analysis of the father's sperm DNA allowed us to detect an expanded fragment of approximately the same size (62 repeats) as that present in the child's and grandfather's lymphocytes. This fragment was not detectable in the father's lymphocytes. Thus the regression is constitutive in the child, being already present in his father's germline. It is therefore likely that the regressed allele is present in all the tissues of the child, allowing a favourable prognosis.",1
"Giordano, M, De Angelis, M S, Mutani, R, Richiardi, P M",2
Application of three intragenic DNA polymorphisms for carrier detection in haemophilia B.,0
"In the west of Scotland use of a single intragenic restriction fragment length polymorphism (F9(VIII)/TaqI) allowed definitive genetic counselling for 45% of females at risk of being carriers for haemophilia B. Two further intragenic RFLPs, F9(VIII)/XmnI) and F9(VIII)/DdeI, have been applied to this population and by using all three polymorphisms the carrier status could be determined in 68% of females at risk. Linkage disequilibrium was apparent between these three RFLPs, and in the west of Scotland the single most clinically useful polymorphism was F9(VIII)/TaqI followed by F9(VIII)/DdeI and then F9(VIII)/XmnI. Overall, prenatal diagnosis by DNA analysis could be offered to 31 of 37 (84%) carriers (obligate and detected) in these families.",1
"Connor, J M, Pettigrew, A F, Shiach, C, Hann, I M, Lowe, G D, Forbes, C D",2
Mutations linked to the pro alpha 2(I) collagen gene are responsible for several cases of osteogenesis imperfecta type I.,0
"We have analysed six South African families with osteogenesis imperfecta type I using three DNA polymorphisms associated with the pro alpha 2(I) collagen gene. In four of these families linkage of the pro alpha 2(I) gene and the osteogenesis imperfecta phenotype was suggested, whereas in the remaining two families there was a lack of linkage. No distinct correlation could be made between the phenotypic features of the families studied and linkage or lack of linkage to the pro alpha 2(I) gene. Two different haplotypes were found to be associated with the mutant pro alpha 2(I) alleles. These findings suggest that molecular heterogeneity exists within osteogenesis imperfecta type I and that in a significant proportion of cases the defect is linked to the pro alpha 2(I) gene.",1
"Wallis, G, Beighton, P, Boyd, C, Mathew, C G",2
Genetic disorders of collagen.,0
"Osteogenesis imperfecta, Ehlers-Danlos syndrome, and Marfan syndrome form a group of genetic disorders of connective tissue. These disorders exhibit remarkable clinical heterogeneity which reflects their underlying biochemical and molecular differences. Defects in collagen types I and III have been found in all three syndromes.",1
"Tsipouras, P, Ramirez, F",2
Ring XY bivalent: a new phenomenon at metaphase I of meiosis in man.,0
The unusual appearance of a ring XY bivalent at metaphase I of meiosis is reported in some cells of an oligospermic human male. Higher than usual frequencies of ring configuration in the XY pair were also observed during prophase I. The defect could be attributable to loss of some DNA sequences from the distal heterochromatic tip of the Y chromosome long arm.,1
"Chandley, A C, Hargreave, T B, McBeath, S, Mitchell, A R, Speed, R M",2
The profile of major congenital abnormalities in the United Arab Emirates (UAE) population.,0
"The aim of this study was to establish the profile of major congenital malformations in the United Arab Emirates (UAE) population which has a high rate of consanguinity. All births with birth weight above 500 g in the three hospitals in the Al Ain Medical District of UAE were prospectively studied from January 1992 to January 1994. About 98% of the births in the district occur in these three hospitals. Detailed family history and clinical and relevant laboratory investigations were recorded in each case. Necropsy was not permitted. The major malformations were classified as multiple or isolated single system abnormalities as well as genetic or non-genetic disorders. Of the 16,419 births which occurred during the two year period, 173 (10.5/1000 births) had major malformations, 90 (52%) had multiple malformations, and 83 (47.97%) had involvement of a single system. Of the infants with multiple malformations, 43 had recognised syndromes, most of which are autosomal recessive disorders with a high frequency of rare syndromes. Twenty eight (31%) had chromosomal abnormalities. The most common systems involved in infants with isolated single system malformations include gastrointestinal (33), central nervous system (17), and cardiovascular (10). While the consanguinity rate was similar (57% v 54%), the frequency of first cousin marriages was much higher (51% v 30%) in the study group compared with the figures for the general population. The consanguinity rate was highest among the syndrome cases, and related parents were more likely to have infants with multiple malformations than an isolated single system abnormality with a relative risk of 1.69 (95% CL 1.27-2.24). Genetic factors could be implicated in 116 (67%) of the 173 cases of major malformations and 49 (28%) were potentially preventable. The study suggests that genetic disorders account for a significant proportion of congenital malformation in the UAE and, thus, a genetic service should be provided as part of the preventive cae programme.",1
"al-Gazali, L I, Dawodu, A H, Sabarinathan, K, Varghese, M",2
Recurrence risk for germinal mosaics revisited.,0
"A formula to calculate recurrence risk for germline mosaicism published by Hartl in 1971 has been updated to include marker information. For practical genetic counselling new, more elaborate tables are given.",1
"van der Meulen, M A, van der Meulen, M J, te Meerman, G J",2
Absence of linkage between familial neural tube defects and PAX3 gene.,0
"Neural tube defects (NTD) are among the most common and disabling birth defects. The aetiology of NTD is unknown and their genetics are complex. The majority of NTD cases are sporadic, isolated, nonsyndromic, and generally considered to be multifactorial in origin. Recently, PAX3 (formerly HuP2, the human homologue of mouse Pax-3), on chromosome 2q35-37, was suggested as a candidate gene for NTD because mutations of Pax-3 cause the mouse mutant Splotch (Sp), an animal model for human NTD. Mutations in PAX3 were also identified in patients with Waardenburg syndrome type 1 (WS1). At least eight patients with both WS1 and NTD have been described suggesting pleiotropy or a contiguous gene syndrome. Seventeen US families and 14 Dutch families with more than one affected person with NTD were collected and 194 people (50 affected) from both data sets were genotyped using the PAX3 polymorphic marker. The data were analysed using affecteds only linkage analysis. The lod scores were -7.30 (US), -3.74 (Dutch), and -11.04 (combined) at theta = 0.0, under the assumption of the autosomal dominant model. For the recessive model, the lod scores were -3.30 (US), -1.46 (Dutch), and -4.76 (combined) at theta = 0.0. Linkage between PAX3 and familial NTD was excluded to 9.9 cM on either side of the gene for the dominant model and to 3.63 cM on either side of the gene for the recessive model in the families studied. No evidence of heterogeneity was detected using the HOMOG program. Our data indicate that PAX3 is not a major gene for NTD.",1
"Chatkupt, S, Hol, F A, Shugart, Y Y, Geurds, M P, Stenroos, E S, Koenigsberger, M R, Hamel, B C, Johnson, W G, Mariman, E C",2
Non-expression of a common mutation in the 21-hydroxylase gene: implications for prenatal diagnosis and carrier testing.,0
"Mutation analysis in the family of a child with 21-hydroxylase deficiency showed that the father and affected child were homozygous for a mutation, A/C655G, believed to activate a cryptic splice site in intron 2 of the 21-hydroxylase gene. The father, who was clinically asymptomatic, showed no biochemical evidence of disease. These results create problems for the management of future pregnancies in such families and for the interpretation of the risk associated with carrier status for this mutation.",1
"Rumsby, G, Massoud, A F, Avey, C, Brook, C G",2
Analysis of parent of origin specific DNA methylation at SNRPN and PW71 in tissues: implication for prenatal diagnosis.,0
"Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are distinct developmental disorders caused by absence of paternal or maternal contributions of the chromosome region 15q11-q13, resulting from deletions, uniparental disomy (UPD), or rare imprinting mutations. Molecular cytogenetic diagnosis is currently performed using a combination of fluorescence in situ hybridisation (FISH), DNA polymorphism analysis, and DNA methylation analysis. Only methylation analysis will detect all three categories of PWS abnormalities, but its reliability in tissues other than peripheral blood has not been examined extensively. Therefore, we examined the methylation status at the CpG island of the small nuclear ribonucleoprotein associated polypeptide N (SNRPN) gene and at the PW71 locus using normal and abnormal lymphoblast (LB) cell lines (n = 48), amniotic fluid (AF) cell cultures (n = 25), cultured chorionic villus samples (CVS, n = 17), and fetal tissues (n = 18) by Southern blot analysis with methylation sensitive enzymes. Of these samples, 20 LB cell lines, three AF cultures, one CVS, and 15 fetal tissues had been previously diagnosed as having deletions or UPD by other molecular methods. Methylation status at SNRPN showed consistent results when compared with FISH or DNA polymorphism analysis using all cell types tested. However, the methylation pattern for PW71 was inconsistent when compared with other tests and should therefore not be used on tissues other than peripheral blood. We conclude that SNRPN, but not PW71, methylation analysis may be useful for diagnosis of PWS/AS on LB cell lines, cultured amniotic fluid, or chorionic villus samples and will allow, for the first time, prenatal diagnosis for families known to carry imprinting centre defects.",1
"Kubota, T, Aradhya, S, Macha, M, Smith, A C, Surh, L C, Satish, J, Verp, M S, Nee, H L, Johnson, A, Christan, S L, Ledbetter, D H",2
Exclusion of one pedigree affected by adult onset primary open angle glaucoma from linkage to the juvenile glaucoma locus on chromosome 1q21-q31.,0
"A locus for autosomal dominant juvenile onset primary open angle glaucoma (POAG) was recently assigned to chromosome region 1q21-q31. In the present study, a large Greek family with autosomal dominant adult onset POAG was investigated using microsatellite markers. Exclusion of linkage of the adult onset POAG gene to the region D1S194-D1S191 was obtained in this pedigree. Therefore, the data provide evidence that juvenile and adult onset POAG are genetically distinct disease entities.",1
"Avramopoulos, D, Kitsos, G, Economou-Petersen, E, Grigoriadou, M, Vassilopoulos, D, Papageorgiou, C, Psilas, K, Petersen, M B",2
Fragile X syndrome is less common than previously estimated.,0
"In 1986, a population study of school children in the city of Coventry gave an overall prevalence in males and females for fragile X syndrome of 1/952. The 29 children diagnosed as having fragile X syndrome in this study have been re-evaluated with molecular diagnostic techniques. Eighteen of the original 29 children have been found not to have the expansion of the FMR1 gene associated with fragile X syndrome. Revised prevalence figures have been calculated giving rise to an overall prevalence figure of 1/2720 (range 1/2198-1/3089). If the four children lost to follow up are also assumed not to have the fragile X syndrome, the revised prevalence figure was 1/5714 (range 1/4762-1/6349). Clinical review of boys with severe mental retardation from this and a subsidiary study show that the clinical features of head circumference greater than the 50th centile, testicular volume greater than the 50th centile, and IQ between 35 and 70 remain helpful in distinguishing boys with fragile X syndrome from those who have non-specific mental retardation.",1
"Morton, J E, Bundey, S, Webb, T P, MacDonald, F, Rindl, P M, Bullock, S",2
Maternal uniparental disomy 7 in Silver-Russell syndrome.,0
"Silver-Russell syndrome (SRS) is characterised by intrauterine and postnatal growth failure accompanied by a variable number of dysmorphic features. It is usually sporadic although a few familial cases have been described. In a prospective study of 33 patients with sporadic SRS, we have studied the parent of origin of chromosome 7 using variable number tandem repeat (VNTR) or microsatellite repeat markers and have identified two patients with maternal uniparental disomy of chromosome 7 (mUPD7). In one family, inconsistent inheritance of paternal alleles of markers on chromosomes other than 7 led to their exclusion from further study. The probands were clinically mild and symmetrical, but showed no gross clinical differences from the 30 patients with chromosome 7 derived from both parents.",1
"Preece, M A, Price, S M, Davies, V, Clough, L, Stanier, P, Trembath, R C, Moore, G E",2
Refinement of the laminin alpha2 chain locus to human chromosome 6q2 in severe and mild merosin deficient congenital muscular dystrophy.,0
"About half of the children with classical congenital muscular dystrophy (CMD) show an absence in their skeletal muscle of laminin alpha2 chain, one of the components of the extracellular matrix protein, merosin. Linkage analysis implicated the laminin alpha2 chain gene (LAMA2) on chromosome 6q2, now confirmed by the discovery of mutations in the laminin alpha2 chain gene. We have further investigated the location of the LAMA2 locus on chromosome 6q2, using both linkage analysis in nine informative families and homozygosity mapping in 13 consanguineous families. Four of these families only had mild or moderate down regulation of laminin alpha2 chain expression and a milder phenotype; the rest had no protein or only a trace. Haplotype analysis in all the informative families, including those with partial laminin alpha2 expression, was compatible with linkage to chromosome 6q2. This observation expands the spectrum of the phenotype secondary to laminin alpha2 chain deficiency. Our results suggest that the LAMA2 locus is more centromeric than previously proposed. Recombinant events place the locus between markers D6S470 and D6S1620 in an interval of less than 3 cM.",1
"Naom, I S, D'Alessandro, M, Topaloglu, H, Sewry, C, Ferlini, A, Helbling-Leclerc, A, Guicheney, P, Weissenbach, J, Schwartz, K, Bushby, K, Philpot, J, Dubowitz, V, Muntoni, F",2
A simplified assay for the arylamine N-acetyltransferase 2 polymorphism validated by phenotyping with isoniazid.,0
"Human arylamine N-acetyltransferase (NAT) activity is determined by two distinct genes, NAT1 and NAT2, and the classical acetylation polymorphism in NAT2 has been associated with a variety of disorders, including lupus erythematosus and arylamine induced cancers. Over 50% of the white population exhibit a slow acetylator phenotype. The genetic basis of the defect has been identified and several DNA based assays are available for genotyping studies. We present here a simplified, rapid PCR based assay for the identification of the major slow acetylator genotypes and validate it using isoniazid as probe drug. This assay was 100% predictive of phenotype. The three genotypes (homozygous mutated, heterozygous, and homozygous rapid) corresponded to a trimodal distribution of Ac-INH/INH metabolic ratios (slow, intermediate, and rapid) without overlapping.",1
"Smith, C A, Wadelius, M, Gough, A C, Harrison, D J, Wolf, C R, Rane, A",2
Diamond-Blackfan anaemia in a girl with a de novo balanced reciprocal X;19 translocation.,0
"A 7 year old girl is described with congenital hypoplastic anaemia (Diamond-Blackfan anaemia, DBA) and an apparently balanced reciprocal translocation, 46,XX,t(X;19)(p21;q13). The girl has associated features including short stature, unilateral kidney hypoplasia, and a branchial cyst. Fluorescent in situ hybridisation (FISH) studies with 19q specific cosmids showed that the chromosome 19 breakpoint is located between the RYR1 and the XRCC11 loci spanning a physical region of 5 Mb. There is no family history of DBA and the parents and two healthy sibs have normal karyotypes. This is the first report of a balanced translocation associated with DBA and we suggest that the distinct phenotype has resulted from a de novo disruption of a functional gene. DBA can be inherited as an autosomal trait and our observation may indicate a candidate gene for the disorder in the 19q13 region.",1
"Gustavsson, P, Skeppner, G, Johansson, B, Berg, T, Gordon, L, Kreuger, A, Dahl, N",2
Effects of consanguineous marriage on reproductive outcome in an Arab community in Israel.,0
"Intrafamilial marriage is favoured by the Arab community in Israel, almost all of whom live in villages populated by a few (< 20) founding families. A previous study in Taibe, a large Arab village located 30 km from Tel Aviv, showed a significantly high malformation rate among infants of consanguineous parents. The present study examines the reproductive consequences of parental consanguinity in 610 families from the same village, selected retrospectively through infants routinely seen in the local well baby clinic. All mothers were interviewed with regard to previous pregnancy outcomes, including abortions, stillbirths, and neonatal or infant deaths, as well as the degree of consanguinity. In addition, we analysed the anthropometric measurements of the probands. The incidence of infant deaths was significantly higher in the inbred group (p < 0.001). No significant increase in fetal loss between the inbred and outbred groups was observed. There were no differences in anthropometric features, except for a lower birth weight in the consanguineous group (p < 0.035). This study, combined with our previous studies of the same population, indicates a prominent public health problem associated with consanguineous marriage in the Arab community and a need for specific genetic counselling.",1
"Jaber, L, Merlob, P, Gabriel, R, Shohat, M",2
Genetic heterogeneity of Meckel syndrome.,0
"Meckel syndrome (MKS) is a lethal, autosomal recessive condition characterised by an occipital meningoencephalocele, enlarged kidneys with multicystic dysplasia, fibrotic changes of the liver in the portal area with ductal proliferation, and postaxial polydactyly. Recently, a MKS gene has been mapped to chromosome 17q21-q24 in Finnish families, with no evidence of locus heterogeneity in this population. Here, we report the exclusion of chromosome 17q21-q24 in eight typical MKS families of North African and Middle Eastern ancestry and provide evidence for genetic heterogeneity of this condition.",1
"Roume, J, Ma, H W, Le Merrer, M, Cormier-Daire, V, Girlich, D, Genin, E, Munnich, A",2
Multiple congenital anomalies including the Rieger eye malformation in a boy with interstitial deletion of (4) (q25-->q27) secondary to a balanced insertion in his normal father: evidence for haplotype insufficiency causing the Rieger malformation.,0
"A 7 year old boy with minor facial anomalies, the Rieger eye malformation, reduced vision, genital anomalies, and severe mental retardation had deletion of the segment 4q24-->q26. His phenotypically normal father had a balanced insertion of that segment into the distal long arm of chromosome 6: 46,XY,ins(6;4)(q26;q24q26). Microsatellite loci flanking the RIEG gene on 4q25 were deleted giving indirect evidence of deletion of this locus. This finding and the normal ocular findings in the insertion carrier father show that haplotype insufficiency can cause the Rieger eye malformation.",1
"Schinzel, A, Brecevic, L, Dutly, F, Baumer, A, Binkert, F, Largo, R H",2
"A new locus for non-syndromal, autosomal recessive, sensorineural hearing loss (DFNB16) maps to human chromosome 15q21-q22.",0
"Non-syndromal, recessive deafness (NSRD) is the most common form of inherited deafness or hearing impairment in humans. NSRD is genetically heterogeneous and it has been estimated that as many as 35 different loci may be involved. We report the mapping of a novel locus for autosomal recessive, non-syndromal deafness (DFNB16) in three consanguineous families originating from Pakistan and the Middle East. Using multipoint analysis (HOMOZ/MAPMAKER) a maximum combined lod score of 6.5 was obtained for the interval D15S1039-D15S123. Recombination events and haplotype analysis define a 12-14 cM critical region between the markers D15S1039 and D15S155 on chromosome 15q15-q21.",1
"Campbell, D A, McHale, D P, Brown, K A, Moynihan, L M, Houseman, M, Karbani, G, Parry, G, Janjua, A H, Newton, V, al-Gazali, L, Markham, A F, Lench, N J, Mueller, R F",2
Dentato-olivary dysplasia in sibs: an autosomal recessive disorder?,0
"The cases of a brother and sister with dentato-olivary dysplasia are described. Both had severe developmental delay, severe epilepsy of early onset, evolving hypertonic quadriplegia, and death in early childhood. Postmortem examination of the brain in one child showed a particular form of dentato-olivary dysplasia. These children show many features in common with previously described cases of this condition, but this is the first report of occurrence in sibs.",1
"Martland, T, Harding, B N, Morton, R E, Young, I",2
"Evidence for a cryptic 46,XX cell line in a 45,X/46,X,psu idic(Xq) patient with normal reproduction.",0
"Gonadal dysgenesis resulting in primary infertility is one of the most common features of Turner syndrome. There have been a number of cases described of pregnancy in 45,X subjects, but whether or not the fertility is associated with a 46,XX cell line in the germ cells is not known. We describe a 45,X/46,X,psu idic(Xq) female with normal fertility, in whom a cryptic 46,XX cell line was found in the germ cells.",1
"James, R S, Sharp, A J, Cockwell, A E, Coppin, B, Jacobs, P A",2
Complete situs inversus and broad thumbs and big toes with postaxial polydactyly.,0
"A healthy, non-consanguineous couple had a son with complete situs inversus viscerum (including dextrocardia but without other cardiac defects), broad thumbs and big toes, postaxial polydactyly, average intelligence and length proportion of the extremities, and a normal face. The common cause of these defects may have a role in the origin of sidedness and symmetry in morphogenesis.",1
"Czeizel, A E, Göblyös, P",2
A linkage survey of 20 dominant retinitis pigmentosa families: frequencies of the nine known loci and evidence for further heterogeneity.,0
"Autosomal dominant retinitis pigmentosa (ADRP) is caused by mutations in two known genes, rhodopsin and peripherin/Rds, and seven loci identified only by linkage analysis. Rhodopsin and peripherin/Rds have been estimated to account for 20-31% and less than 5% of ADRP, respectively. No estimate of frequency has previously been possible for the remaining loci, since these can only be implicated when families are large enough for linkage analysis. We have carried out such analyses on 20 unrelated pedigrees with 11 or more meioses. Frequency estimates based on such a small sample provide only broad approximations, while the above estimations are based on mutation detection in much larger clinic based patient series. However, when markers are informative, linkage analysis cannot fail to detect disease causation at a locus, whereas mutation detection techniques might miss some mutations. Also diagnosing dominant RP from a family history taken in a genetic clinic may not be reliable. It is therefore interesting that 10 (50%) of the families tested have rhodopsin-RP, suggesting that, in large clearly dominant RP pedigrees, rhodopsin may account for a higher proportion of disease than had previously been suspected. Four (20%) map to chromosome 19q, implying that this is the second most common ADRP locus. One maps to chromosome 7p, one to 17p, and one to 17q, while none maps to 1cen, peripherin/Rds, 8q, or 7q. Three give exclusion of all of these loci, showing that while the majority of dominant RP maps to the known loci, a small proportion derives from loci yet to be identified.",1
"Inglehearn, C F, Tarttelin, E E, Plant, C, Peacock, R E, al-Maghtheh, M, Vithana, E, Bird, A C, Bhattacharya, S S",2
"Peutz-Jeghers disease: most, but not all, families are compatible with linkage to 19p13.3.",0
"A locus for Peutz-Jeghers syndrome (PJS) was recently mapped to chromosome 19p13.3. Each of 12 families studied was compatible with linkage to the marker D19S886. We have analysed 20 further families and found that the majority of these are consistent with a PJS gene on 19p13.3. Three families were, however, unlinked to 19p13.3 and none of the available PJS polyps from these families showed allele loss at D19S886. There were no obvious clinicopathological or ethnic differences between the 19p13.3 linked and unlinked families. There appears, therefore, to be a major PJS locus on chromosome 19p13.3 and the possibility exists of a minor locus (or loci) elsewhere.",1
"Olschwang, S, Markie, D, Seal, S, Neale, K, Phillips, R, Cottrell, S, Ellis, I, Hodgson, S, Zauber, P, Spigelman, A, Iwama, T, Loff, S, McKeown, C, Marchese, C, Sampson, J, Davies, S, Talbot, I, Wyke, J, Thomas, G, Bodmer, W, Hemminki, A, Avizienyte, E, de la Chapelle, A, Aaltonen, L, Tomlinson, I",2
Familial persistent pulmonary hypertension of the newborn resulting from misalignment of the pulmonary vessels (congenital alveolar capillary dysplasia).,0
"Misalignment of the pulmonary veins with congenital alveolar capillary dysplasia, although rare, has been reported as a cause of persistent pulmonary hypertension of the newborn. Reported cases have been mainly sporadic. Familial occurrence has been reported in only three instances. We present affected sibs with this condition. In addition to pulmonary abnormalities, urogenital abnormalities, including ureteric and urethral obstruction, seem to be common. Autosomal recessive inheritance is suggested.",1
"Vassal, H B, Malone, M, Petros, A J, Winter, R M",2
Uncloned expanded CAG/CTG repeat sequences in autosomal dominant cerebellar ataxia (ADCA) detected by the repeat expansion detection (RED) method.,0
"In some neurodegenerative diseases, genetic anticipation correlates with expansions of the CAG/CTG repeat sequence above the normal range through the generations of a pedigree. Among these neurodegenerative diseases are late onset autosomal dominant cerebellar ataxias (ADCA). ADCA are genetically heterogeneous disorders with different cloned genes for spinocerebellar ataxia type 1 (SCA1), type 2 (SCA2), type 3 or Machado-Joseph disease (SCA3/MJD), and type 6 (SCA6). Another related dominant ataxia, dentatorubral-pallidoluysian atrophy (DRPLA), also shows CAG/CTG repeat expansions. Genetic anticipation has been reported for all of them except for the recently cloned SCA6 gene. Other, as yet undetected SCA genes may show the same features. We have used the repeat expansion detection (RED) method to detect repeat expansions directly in DNA samples from ADCA patients not resulting from known genes. Our sample consists of 19 affected index cases, corresponding to 52.8% of our ADCA families without CAG/CTG repeat expansions in the SCA1, SCA2, SCA3/MJD, SCA6, or DRPLA genes. Eighty-nine percent of the index cases had expansions of a CAG/CTG sequence greater than 40 repeats by RED, while these were observed in only 26.9% of 78 healthy subjects from the general population (p < 0.0001). The distribution of RED fragments in controls and ADCA patients also shows significant differences with the Mann-Whitney U test (U = 376.5, p = 0.0007). Moreover, there was a significant inverse correlation between the size of expansion and the age of onset (r = -0.54, p = 0.018). These results show CAG/CTG repeat expansions of over 40 repeats in our sample of ADCA families not resulting from known SCA genes.",1
"Pujana, M A, Volpini, V, Gratacós, M, Corral, J, Banchs, I, Sánchez, A, Genís, D, Cervera, C, Estivill, X",2
P67L: a cystic fibrosis allele with mild effects found at high frequency in the Scottish population.,0
"Only three mutant cystic fibrosis (CF) alleles have to date been established as conferring a dominant mild effect on affected subjects who are compound heterozygotes. We now add a fourth, P67L, which occurs on about 1.4% of Scottish CF chromosomes. Among 13 patients (12 unrelated) with this allele, the average age at diagnosis was 22.5 +/- 11.3 years. None of the cases had consistently raised sweat chloride concentrations, the average value being 57 +/- 9 mmol/l; 77% of the patients were pancreatic sufficient. When compared to three other established mild CF alleles, R117H, A455E, and 3849 + 10kb C-T, a compound heterozygote for P67L has minimal disease and clinical suspicions are unlikely to be confirmed other than by DNA typing.",1
"Gilfillan, A, Warner, J P, Kirk, J M, Marshall, T, Greening, A, Ho, L P, Hargreave, T, Stack, B, McIntyre, D, Davidson, R, Dean, J C, Middleton, W, Brock, D J",2
Paternally inherited deletion of CSH1 in a patient with Silver-Russell syndrome.,0
"In a continuing study on the aetiology of Silver-Russell syndrome (SRS), we detected a patient with a heterozygous deletion in the growth hormone gene cluster (17q22-q24). The deletion of the chorionic somatomammotrophin hormone 1 (CSH1) gene was inherited from the patient's father. The patient shows typical symptoms of SRS. Though deletions of CSH1 have been reported without any phenotypic consequences, the heterozygous deletion might be involved in the aetiology of SRS in the case presented here. Apart from other observations in SRS, like maternal uniparental disomy 7, changes in the genomic region 17q22-qter might be responsible for the expression of this syndrome for at least some of the patients, leading to the heterogeneity of SRS.",1
"Eggermann, T, Eggermann, K, Mergenthaler, S, Kuner, R, Kaiser, P, Ranke, M B, Wollmann, H A",2
"Knowledge, views, and experience of 25 women with myotonic dystrophy.",0
"Twenty-five affected women of reproductive age known to the North West Regional Genetics Family Register (NWRGFR) were interviewed. A semistructured questionnaire, completed by the interviewer, was used to assess understanding and experience of the clinical and genetic aspects of myotonic dystrophy (MD) and attitudes to prenatal diagnosis (PND). Characteristic features of MD (muscle weakness and wasting and myotonia) were well known. Knowledge of other features and complications reflected experience. All subjects were aware that MD is inherited, but only 56% (14/25) knew the risk to their own children and subjects tended to overestimate this risk. Anticipation and maternal transmission of congenital myotonic dystrophy (CMD) were often misunderstood. Almost half of the subjects (12/25) perceived themselves to be moderately or severely affected and 40% (10/25) felt that their symptoms restricted daily life. Feelings of devastation, depression, worry about the future, and guilt at the risk of transmission to their children were described. Many subjects (10/25) said that the worst aspect of MD is the risk of transmission to their children. Over half (14/25) said that the risk of transmitting MD had influenced or would influence their own reproduction. Three-quarters of subjects who felt that MD had influenced their reproductive decisions (9/12) chose to limit their family or have no children; only 25% (3/12) requested PND. Subjects felt that the lack of information concerning clinical severity made PND for MD difficult to consider.",1
"Faulkner, C L, Kingston, H M",2
Familial occurrence of congenital incomplete prepyloric mucosal diaphragm.,0
"Incomplete prepyloric mucosal diaphragm (IPMD) is an uncommon congenital anomaly that leads to gastric outlet obstruction in infancy and childhood. This report describes the occurrence of IPMD in six children in a closely knit tribal family from a geographically isolated desert town with a small population in the Sahara. Their records showed similarities of clinical, radiological, operative, and histopathological features. These features, as well as its occurrence in brothers, sisters, and cousins, suggest that this unusual anomaly is transmitted as an autosomal recessive trait.",1
"Gahukamble, D B",2
"A new recognisable syndrome in three sibs with congenital heart disease, round face with depressed nasal bridge, short stature, and developmental retardation.",0
"We report three sibs with congenital heart disease, round face with depressed nasal bridge, small mouth, short stature, developmental retardation, relatively dark skin, and high axial triradius. The chromosomes of the three patients were normal and the parents were unrelated, healthy, and of normal intelligence. The mother denied infections, drinking, drug intake, or exposure to known teratogenic agents during each pregnancy.",1
"Sonoda, T, Ohdo, S, Madokoro, H, Ohba, K",2
Sickness absence after inguinal herniorrhaphy.,0
"Eight hundred and ninety-nine men were studied, aged 16-65 inclusive, who underwent an elective inguinal herniorrhaphy during 1970 and 1971 in eight hospitals in Wessex, and under nine consultant surgeons. There was a significant variation in postoperative inpatient stay and total sickness absence between hospitals and between consultants. The physical activity involved in the patient's occupation, his age at operation, previous sickness absence, bilateral herniorrhaphy, attendance at follow-up outpatients' clinic, type of repair, and the influence exerted by three hospitals and two consultants accounted for only 21% of the variation in total sickness absence. The general practitioners who had referred patients to the hospitals for herniorrhaphy, and the consultant surgeons who carried out the operations, were sent a questionnaire to ascertain their attitudes towards follow-up outpatient appointments and the various factors identified in the first part of the study as significantly influencing total sickness absence. A higher proportion of GPs who felt that an outpatient appointment was necessary before return to work was found in relation to the patients who had the longest mean total sickness absences than among the GPs who looked after the patients with shorter total sickness absences.",1
"Griffiths, M, Oblin, M E, Acheson, E D",2
Deaths from ischaemic heart disease and infant mortality in England and Wales.,0
"Death rates from ischaemic heart disease (IHD) in English and Welsh counties are correlated, in both men and women, with the infant mortality rates of those counties when the individuals whose deaths are considered were young, thus confirming previous findings in Norway. In England and Wales, however, there is an equally good correlation between deaths from IHD and infant mortality patterns up to and including that for the same time period as the IHD deaths. The British data provide no grounds for concluding from these relationships that living conditions during early life per se bear a causal relationship to deaths from IHD.",1
"Williams, D R, Roberts, S J, Davies, T W",2
A study of persons aged 65 and over in the Leeds Metropolitan District.,0
"A study of the elderly living in the community and in institutional care in the Leeds Metropolitan District is outlined. Four populations of persons aged 65 and over were examined: those living in their own homes; in sheltered housing; in social services aged persons' hostels (Part III accommodation); and in hospitals. Findings on one key concept--coping ability--are discussed. Those living in their own homes were most able to cope. Many living in institutions were well able to cope in the community according to the criteria of mobility and functional ability. The relationship between age, morbidity, and coping ability were examined. Women were more likely to report the presence of a long-term illness than men. Housebound respondents in the community were twice as likely to be suffering from non-traumatic locomotor disorders, eyesight disorders, and cerebrovascular disease than respondents in the community sample taken as a whole.",1
"McDonnell, H, Long, A F, Harrison, B J, Oldman, C",2
Anencephaly and spina bifida (ASB) and retroversion.,0
"Despite the wealth of epidemiological material of the last decade, birth defects are still the chief cause of perinatal mortality and no significant breakthrough in understanding or reduction has yet been seen. Many proposed aetiological factors are still being evaluated. This report suggests a possible, simple, remediable factor in the aetiology of defects of the central nervous system.",1
"Buckley, M R",2
A mathematical model of a heroin epidemic: implications for control policies.,0
"An exponential model based on the infectious disease model of Kermack and McKendrick has been simplified to illustrate how the use of heroin spreads in epidemic fashion. A numerical simulation is arranged to show how the dynamics of spread are influenced by the original number of users, rates of conversion, and time of removal from the drug scene of those secondarily affected. The spread is significantly increased by small increases of those originally affected, in which case reduction of spread requires a large increase in rate of removal. The model indicates a strategy for intervention which is discussed in relation to policies for control of drug abuse.",1
"Mackintosh, D R, Stewart, G T",2
Neurotrophins promote revascularization by local recruitment of TrkB+ endothelial cells and systemic mobilization of hematopoietic progenitors.,0
"The neurotrophin brain-derived neurotrophic factor (BDNF) is required for the maintenance of cardiac vessel wall stability during embryonic development through direct angiogenic actions on endothelial cells expressing the tropomysin receptor kinase B (TrkB). However, the role of BDNF and a related neurotrophin ligand, neurotrophin-4 (NT-4), in the regulation of revascularization of the adult tissues is unknown. To study the potential angiogenic capacity of BDNF in mediating the neovascularization of ischemic and non-ischemic adult mouse tissues, we utilized a hindlimb ischemia and a subcutaneous Matrigel model. Recruitment of endothelial cells and promotion of channel formation within the Matrigel plug by BDNF and NT-4 was comparable to that induced by VEGF-A. The introduction of BDNF into non-ischemic ears or ischemic limbs induced neoangiogenesis, with a 2-fold increase in the capillary density. Remarkably, treatment with BDNF progressively increased blood flow in the ischemic limb over 21 days, similar to treatment with VEGF-A. The mechanism by which BDNF enhances capillary formation is mediated in part through local activation of the TrkB receptor and also by recruitment of Sca-1+CD11b+ pro-angiogenic hematopoietic cells. BDNF induces a potent direct chemokinetic action on subsets of marrow-derived Sca-1+ hematopoietic cells co-expressing TrkB. These studies suggest that local regional delivery of BDNF may provide a novel mechanism for inducing neoangiogenesis through both direct actions on local TrkB-expressing endothelial cells in skeletal muscle and recruitment of specific subsets of TrkB+ bone marrow-derived hematopoietic cells to provide peri-endothelial support for the newly formed vessels.",1
"Kermani, Pouneh, Rafii, Dahlia, Jin, David K, Whitlock, Paul, Schaffer, Wendy, Chiang, Anne, Vincent, Loic, Friedrich, Matthias, Shido, Koji, Hackett, Neil R, Crystal, Ronald G, Rafii, Shahin, Hempstead, Barbara L",2
The DEAD-box RNA helicase Vad1 regulates multiple virulence-associated genes in Cryptococcus neoformans.,0
"The study of fungal regulatory networks is essential to the understanding of how these pathogens respond to host environmental signals with effective virulence-associated traits. In this study, a virulence-associated DEAD-box RNA helicase-encoding gene (VAD1) was isolated from a mutant defective in the virulence factor laccase. A Deltavad1 mutant exhibited a profound reduction in virulence in a mouse model that was restored after reconstitution with WT VAD1. Loss of VAD1 resulted in upregulation of NOT1, a gene encoding a global repressor of transcription. NOT1 was found to act as an intermediary transcriptional repressor of laccase. Vad1 was located within macromolecular complexes that formed cytoplasmic granular bodies in mature cells and during infection of mouse brain. In addition, VAD1 was shown by in situ hybridization to be expressed in the brain of an AIDS patient coinfected with C. neoformans. To understand the role of VAD1 in virulence, a functional genomics approach was used to identify 3 additional virulence determinants dependent on VAD1: PCK1, TUF1, and MPF3, involved in gluconeogenesis, mitochondrial protein synthesis, and cell wall integrity, respectively. These data show that fungal virulence-associated genes are coordinately regulated and that an analysis of such transcriptomes allows for the identification of important new genes involved in the normal growth and virulence of fungal pathogens.",1
"Panepinto, John, Liu, Lide, Ramos, Jeanie, Zhu, Xudong, Valyi-Nagy, Tibor, Eksi, Saliha, Fu, Jianmin, Jaffe, H Ari, Wickes, Brian, Williamson, Peter R",2
Genetic causes of human heart failure.,0
"Factors that render patients with cardiovascular disease at high risk for heart failure remain incompletely defined. Recent insights into molecular genetic causes of myocardial diseases have highlighted the importance of single-gene defects in the pathogenesis of heart failure. Through analyses of the mechanisms by which a mutation selectively perturbs one component of cardiac physiology and triggers cell and molecular responses, studies of human gene mutations provide a window into the complex processes of cardiac remodeling and heart failure. Knowledge gleaned from these studies shows promise for defining novel therapeutic targets for genetic and acquired causes of heart failure.",1
"Morita, Hiroyuki, Seidman, Jonathan, Seidman, Christine E",2
Mitochondrial energy metabolism in heart failure: a question of balance.,0
"The mitochondrion serves a critical role as a platform for energy transduction, signaling, and cell death pathways relevant to common diseases of the myocardium such as heart failure. This review focuses on the molecular regulatory events and downstream effector pathways involved in mitochondrial energy metabolic derangements known to occur during the development of heart failure.",1
"Huss, Janice M, Kelly, Daniel P",2
"Oxygen, oxidative stress, hypoxia, and heart failure.",0
"A constant supply of oxygen is indispensable for cardiac viability and function. However, the role of oxygen and oxygen-associated processes in the heart is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death. As oxygen is a major determinant of cardiac gene expression, and a critical participant in the formation of ROS and numerous other cellular processes, consideration of its role in the heart is essential in understanding the pathogenesis of cardiac dysfunction.",1
"Giordano, Frank J",2
NO/redox disequilibrium in the failing heart and cardiovascular system.,0
"There is growing evidence that the altered production and/or spatiotemporal distribution of reactive oxygen and nitrogen species creates oxidative and/or nitrosative stresses in the failing heart and vascular tree, which contribute to the abnormal cardiac and vascular phenotypes that characterize the failing cardiovascular system. These derangements at the integrated system level can be interpreted at the cellular and molecular levels in terms of adverse effects on signaling elements in the heart, vasculature, and blood that subserve cardiac and vascular homeostasis.",1
"Hare, Joshua M, Stamler, Jonathan S",2
Learning from failure: congestive heart failure in the postgenomic age.,0
"The prognosis of heart failure is worse than that of most cancers, but new therapeutic interventions using stem and other cell-based therapies are succeeding in the fight against it, and old drugs, with new twists, are making a comeback. Genetically engineered animal models are driving insights into the molecular mechanisms that cause hearts to fail, accelerating drug discoveries, and inspiring cell-based therapeutic interventions for both acquired and inheritable cardiac diseases.",1
"Benjamin, Ivor J, Schneider, Michael D",2
Unlocking the DEAD-box: a key to cryptococcal virulence?,0
The DEAD-box RNA helicases are enzymes involved in many critical aspects of RNA metabolism within both eukaryotic and prokaryotic organisms. Several studies have shown that these proteins may have important functions in mediating microbial pathogenesis. A new study in this issue of the JCI identifies the first DEAD-box RNA helicase in the pathogenic fungus Cryptococcus neoformans and proposes novel roles for this family of proteins in the development and progression of cryptococcosis.,1
"Heung, Lena J, Del Poeta, Maurizio",2
Vascular remodeling and the kallikrein-kinin system.,0
"Remodeling of the arterial wall occurs mainly as a consequence of increased wall stress caused by hypertension. In this issue of the JCI, Azizi et al. report that in humans with a kallikrein gene polymorphism that lowers kallikrein activity, the brachial artery undergoes eutrophic inward remodeling in the absence of hypertension or other hemodynamic changes. It has also been reported that alterations of the kallikrein-kinin system are associated with formation of aortic aneurysms. Conversely, after vascular injury, kinins mediate the beneficial effect of angiotensin-converting enzyme inhibitors that prevent neointima formation. These findings raise the intriguing possibility that decreased kallikrein-kinin system activity may play an important role in the pathogenesis of vascular remodeling and disease, while increased activity may have a beneficial effect.",1
"Carretero, Oscar A",2
Cervical cancer in Finland and South Wales: implications of end results data on the natural history.,0
"The population-based cancer registry data on patients with cervical cancer in Finland and South Wales in 1960--69 were analysed for survival. Patients with carcinoma-in-situ experienced essentially the normal life expectancy. Those with invasive carcinoma experienced 75% of normal post-registration life expectancy in Finland but only 45% in South Wales. The difference was due to higher frequency and to better survival of patients with localised carcinoma in Finland, which was attributed to the fact that in Wales the mean age of the population is higher than that in Finland, and also to the longer delya in Wales from first symptoms to diagnosis among women with localised cancer. The differences in mean age by clinical stage and in survival combined with the duration of symptoms support the hypothesis that speed of tumour growth is a major determinant of clinical stage at diagnosis.",1
"Hakama, M, West, R",2
Acceptors and rejectors of an invitation to undergo breast screening compared with those who referred themselves.,0
"All women aged 50--79 were invited by two group practices to undergo screening and 57% accepted. Women of the same age range in other practices, who referred themselves, were also screened. Interview with random samples of 100 invited screened women (acceptors), 100 invited unscreened women (rejectors), and 50 self-referred women enabled comparisons to be made of personal and social characteristics, previous health behaviour, and beliefs about cancer in the three groups. Self-referral was associated with lower age, higher social class, and higher educational levels. Women accepting invitations included more who had previously used other screening procedures, for example, cervical smears and chest x rays, than those rejecting invitations. Previous use of screening was even more among self-referred women. Acceptance of screening was associated with belief in the possibilities of curing cancer.",1
"Hobbs, P, Smith, A, George, W D, Sellwood, R A",2
A randomised controlled trial of the effect of the provision of free school milk on the growth of children.,0
"A randomised controlled study was carried out of the effect on growth of the provision of free milk supplements to schoolchildren aged 7 and 8. In selecting children for this study, the aim was to identify those whose socioeconomic circumstances might place them at a disadvantage for growth. Five hundred and eighty-one-children were selected from schools where a high proportion of the pupils received free school meals, and from families with four or more children. The subjects were randomly allocated to receive a third of a pint (190 ml) of free milk daily for six school terms or to a control group. The mean difference in height gain at the end of twenty-one-and-a-half months was 3% or 2.93 mm (P less than 0.05) in favour of the children provided with free milk. The mean difference in weight gain was 130 g (P greater than 0.05) in their favour. The height and weight gain associated with the provision of free mild was very small in the study population, and it is therefore likely that the benefit to growth of providing free milk for the whole unselected population of schoolchildren of these ages would be even smaller.",1
"Baker, I A, Elwood, P C, Hughes, J, Jones, M, Moore, F, Sweetnam, P M",2
"Treatment of elderly adults with impaired hearing: resources, outcome, and efficiency.",0
The general relationship between treatment and response is illustrated with reference to the response of elderly people to rehabilitation treatment after a hearing aid has been prescribed. The evidence of the effects of treatment is reviewed and a tentative empirical relationship is proposed between treatment input (therapist time) and effect (hours of use of the hearing aids). This illustrates a rapid improvement in the effect of treatment for up to about one hour of therapist time but very little improvement with increasing input thereafter. The resource implications are discussed and it is concluded that an input of an average of one hour of follow-up would be a very worthwhile investment and should be a priority for expenditure by health authorities.,1
"Ward, P R",2
The behavioural characteristics of local authority home residents referred to a geriatric psychiatry service.,0
"With increasing demands upon a geriatric psychiatry service, the priorities for day care and long-term hospital care have had to be re-examined. As a result, old people already in local authority residential care are receiving lower priority than those still in the community. In this study we suggest that certain behavioural characteristics and, in particular, incontinence, may present the caring staff of residential homes with special difficulties. We conclude that adequate assessment is essential to ensure that residents are suited to the level of facilities supplied.",1
"Masterton, G, Holloway, E M, Timbury, G C",2
Assessment of the intake of dietary fibre from cereal foods: an epidemiological approach.,0
"In a study evaluating the intake of dietary fibre from cereal foods the results obtained from a standard 7-day weighed record were compared with simpler methods. This showed that weighing was unnecessary to obtain a valid measure of intake. There was also a low ratio of within-subject to between-subject variation: thus four days of recording are all that are required. The 4-day unweighed record is cheaper, less complex, and may be expected to produce higher completion rates than the 7-day weighed record.",1
"Silman, A J",2
Congenital malformations and maternal occupation in Finland: multivariate analysis.,0
"The Finnish Register of Congenital Malformations was used in a multivariate analysis to explore the associations between maternal occupation in industry and children born with central nervous system (CNS) or musculoskeletal or oral cleft malformations. Possible confounding factors were selected in preliminary screening of risk indicators for malformations. These factors included characteristics of the mother, the child, and the family; maternal illnesses; an maternal medication at the time of pregnancy. Tobacco smoking was a confounding factor for all type of malformations; number of children born to the mother, maternal age, malformations in the family, number of rooms occupied by the family, sex of the child, threatened abortion, and continuous medication of the mother during the first trimester confounded the association for certain type of malformations. After adjusting for confounding factors, maternal occupation in industrial trades significantly correlated with CNS, oral cleft, and musculoskeletal malformation in the offspring. Maternal occupation in industry and construction only was significantly associated with CNS malformations in the offspring but the associations with oral cleft and musculoskeletal malformations were not significant.",1
"Hemminki, K, Mutanen, P, Saloniemi, I, Luoma, K",2
Childhood cancer and parental occupation in Finland.,0
"A case-control study was conducted of the occupations of parents of children under 15 with diagnosed malignancies. The total series contained all childhood cancers cases reported to the Finnish Cancer Registry during the period 1959-75. The parental occupations, recorded at the time of pregnancy, were collected from maternity welfare centres. The cases were analysed as a singly group or as subgroups according to the diagnoses-brain tumours, leukaemia, and all other malignancies. The maternal occupations found more frequently among cases than controls included farmers' wives (1959-68 only), pharmacists, saleswomen, bakers, and factory work of an vehicle driving, machine repair, painting, and the work of men who gave an academic degree as their occupation. Some of these occupations involve possible exposure to harmful chemicals, although chance correlations cannot be excluded.",1
"Hemminki, K, Saloniemi, I, Salonen, T, Partanen, T, Vainio, H",2
"Assessment of the ""E' book as a tool for drug monitoring.",0
"For two years, the following records were linked for 10 453 people: (1) basic attributes; (2) details of prescriptions; and (3) information about illnesses recorded by general practitioners (GPs) in an ""E' book. Analyses were performed to reveal association between drugs and diagnoses. Although the ""E' book has certain disadvantages for drug monitoring, the methods proved to be capable of detecting adverse effects of drugs. Unfortunately the number of practitioners using ""E' books would be too small for detection of most serious hazards such as the induction of cancer. Hence it is concluded that the first priority should be to establish a record linkage scheme covering hospital admissions, obstetric deliveries, and deaths.",1
"Skegg, D C, Richards, S M, Doll, R",2
Comparison of cause of death coding on death certificates with coding in the Royal College of General Practitioners Oral Contraception Study.,0
"A comparison has been made between the coding of the cause of death by (a) the Royal College of General Practitioners (RCGP) during the Oral Contraception Study and (b) the Office of Population Censuses and Surveys (OPCS) or the General Register Office for Scotland (GRO) on death certificates for the same subjects. Broad grouping of the International Classification of Diseases (ICD) showed close agreement between RCGP and OPCS or GRO coding for all deaths which occurred from the start of the Oral Contraception Study in 1968 up to December 1978. Moreover, where discrepancies occurred there were no systematic differences between ever-users of oral contraceptive and non-users. Detailed examinations of discrepancies in the coding of the causes of those deaths included in the RCGP publication of October 1977 shows that our previous estimate of mortality risk associated with oral contraceptives would not be materially altered by the use of death certificate information.",1
"Wingrave, S J, Beral, V, Adelstein, A M, Kay, C R",2
Young mentally handicapped adults in three London boroughs: prevalence and degree of disability.,0
"A survey of 282 young adults, mentally handicapped on an administrative definition, was undertaken in th London Boroughs of Hounslow, Hammersmith, and Ealing between October 1978 and April 1980. The prevalence of mental handicap in the age group born between 1958 and 1963 was calculated, and variations were shown between the three boroughs and within the borough of Ealing. The findings suggested that the prevalence of severe mental handicap in this area is not markedly different from rates found in other British studies, but the administrative prevalence is inflated because numbers of mildly handicapped school leavers subsequently use the services for the mentally handicapped. Subjects were classified according to behavioural disabilities: young people in residential care were more likely to be severely incontinent, not literate, and without speech, but overall there was no relationship between degree of disability and placement in residential care.",1
"Mitchell, S J, Woodthorpe, J",2
The effect of fluoridation on the dental health of urban Scottish Schoolchildren.,0
"A comparison was made of the dental health of children aged 4-5 and 9-10 in two Scottish towns, one with fluoridated drinking water and the other without. Striking differences were observed. A 44% reduction in decayed, missing, and filled deciduous teeth was found in 4-5 year-olds in the fluoridated compared with the non-fluoridated town and a 50% reduction in decayed, missing, and filled permanent teeth was recorded for the 9-10-year-olds. Larger percentage differences were found for the anterior teeth: a 65% reduction in deciduous incisors and canines, and an 81% reduction in permanent incisors and canines. Fluoridation of public water supplies in urban areas of Scotland would be a safe and effective way of dramatically improving dental health.",1
"Blinkhorn, A S, Brown, M D, Attwood, D, Downer, M C",2
The prevalence of multiple sclerosis in the Outer Hebrides compared with north-east Scotland and the Orkney and Shetland Islands.,0
"Multiple sclerosis has been reported to have a high prevalence in the Orkney and Shetland Islands and in Caithness in comparison with the highlands of Scotland and the Outer Hebrides-the Western Isles. For this reason a survey was undertaken in the Outer Hebrides and 25 probable and 30 probable and possible patients with multiple sclerosis were found. This is an increase from eight and 11 respectively found in 1954. The present prevalence rate of 97.3 per 100 000 for probable and possible multiple sclerosis is not significantly different from that found in a recent study in the Grampian region in north-east Scotland. Repeated studies in small populations generally show increasing prevalence of multiple sclerosis because some patients are missed in the earlier studies, and over a long period of time there may also be some increase in survival time. This increase has been found in the Orkney and Shetland Islands, in north-east Scotland, and also in the Outer Hebrides.",1
"Dean, G, Goodall, J, Downie, A",2
Respiratory illness in British schoolchildren and atmospheric smoke and sulphur dioxide 1973-7. I: cross-sectional findings.,0
"The relation between respiratory illness and atmospheric smoke and sulphur dioxide (SO2) was investigated from 1973 to 1977 in children aged 6 to 11 from a random sample of 28 areas in England and Scotland. Cross-sectional results are presented for 1975, and results from other years briefly summarised. In 1975 there were 19 areas with data on pollution and in these areas the sample included 5787 children of white ethnic origin of whom 4116 (71%) had complete information of respiratory illness and other variables considered in the analysis. After allowing for the effects of age, social class, population density, type of fuel used for cooking in the home, and season of examination, the prevalence of respiratory illness in both sexes was in the home, and season of examination, the prevalence of respiratory illness in both sexes was positively associated with the levels of smoke over the range of annual means 8 to 51 microgram/m3 )P less than or equal to 0.05). No relation was found between illness and annual means of SO2 ranging from 12 to 114 microgram/m3. Similar results were found in other years, and in 1977, when information of tobacco smoking at home was collected, the association between illness and atmospheric smoke appeared to be independent of smoking within the home. The levels of smoke were much lower than those at which effects on health hve previously been reported so the association is unlikely to be causative. We postulate that higher levels of atmospheric pollution at an earlier period in some areas may have predisposed children living there to respiratory illness during their primary school years. Alternatively, some other characteristics of the polluted areas may explain the findings.",1
"Melia, R J, Florey, C D, Swan, A V",2
Respiratory illness in British schoolchildren and atmospheric smoke and sulphur dioxide 1973-7. II: longitudinal findings.,0
"A study was set up to investigate the effects of annual changes in the levels of atmospheric smoke and SO2 on changes in health from 1973 to 1977 in primary schoolchildren from 28 randomly selected areas of England and Scotland.  Changes in health were measured by taking the change in number of respiratory conditions reported from one annual examination to the next. The number of areas with data on pollution in each period was 5,9,17, and 14 respectively and within these areas the response rate varied from 65% to 74%. Altogether 857, 1436, 2702, and 2036 children respectively who were of white ethnic origin, aged 6 to 11, and had complete data on sex, social class, and changes in health were studied in each period. In 1973-4 the levels of pollution were highest and showed the greatest decline. The greatest annual mean change in smoke was a decrease from 71.9 to 50.5 microgram/m3 and in SO2 a decrease from 94.2 to 47.6 microgram/m3. However, no relation was found between improvement in health and decreasing levels of pollution. In subsequent years, when the levels of pollution were lower and showed smaller changes, change in health was also unrelated to changes in pollution. Thus no evidence was found to suggest that the levels measured during the study were harmful to health.",1
"Melia, R J, Florey, C D, Chinn, S",2
Prognosis of falls in old people at home.,0
"One hundred and twenty-five people aged 65 and over in the Birmingham area who fell at home were followed up for one year after the fall had been reported by the general practitioner. They were compared with 125 control subjects matched for age and sex and drawn from the same doctors' lists. Two months after the fall, one control and 11 fallers had died. One year after the fall, eight controls and 32 fallers had died. The main factor associated with increased mortality was impaired mobility before the index fall.",1
"Wild, D, Nayak, U S, Isaacs, B",2
"Optimising the age, number of tests, and test interval for cervical screening in Canada.",0
"Different approaches to screening for cancer of the cervix by cervical cytology have been evaluated using a computer simulation model developed by Knox and data on the natural history of carcinoma-in-situ (or worse) from a cohort study of women screened in British Columbia, 1949-69. The natural history input parameters and the output parameters without screening were modified to reflect the earlier onset of carcinoma-in-situ in younger cohorts now being experienced in British Columbia, resulting in simulated mortality from carcinoma of the cervix approximately 50% greater than that experienced in Canada in 1955. The simulations showed that the sensitivity of the test and the proportion of women in the population who accept invitations to attend for screening materially influence the extent to which programmes reduce mortality. Missed screens also have an important impact. With a 75% test sensitivity, and an 80% population acceptance, a programme designed to reduce mortality by 90% would commence at age 25, involve triennial screens to age 52, or triennial screens to age 40 and quinquennial screens to age 60, a total of 10 tests in a lifetime. A repeat test at age 26 contributes nothing to the mortality benefit. Nevertheless, additional modifications of the natural history specifications to accommodate high-risk younger women would require a more frequent schedule of examinations under the age of 35, though at a substantial 'cost' in terms of the total number of examinations required in a population.",1
"Shun-Zhang, Y, Miller, A B, Sherman, G J",2
Area variations in infant mortality 1975-7.,0
"Infant mortality rates vary from area to area. Part of this variation is due to the socioeconomic characteristics of the area and part to other factors including the obstetric, paediatric, and community health services. Four social indicators associated with infant deaths are used to control for some of the variations in socioeconomic characteristics and residual variation is then examined. The four social indicators are the level of unemployment, the proportion of large families, the proportion of lone-parent families, and the level of overcrowding.",1
"Bradshaw, J, Edwards, H, Lawton, D, Staden, F, Weale, J, Weekes, A",2
School meals and the rate of growth of primary school children.,0
"The effect of school meals on the rate of growth was assessed in two sets of children over one, two, and three-year periods in England and Scotland between 1973 and 1979. In all analyses children were subdivided into three groups: poor, not poor, and undefined, according to a set of questions on social circumstances. The rate of growth was assessed for children receiving school meals, lunches prepared at home, and those who changed scheme during the study period. No relation between rate of growth and uptake of school meals was found at any of the levels of poverty in England. In Scotland there was some indication in the poor group that children who received school meals had a smaller rate of growth than children having lunches prepared at home. There was inconclusive evidence that children from the poorer sectors of the community whose mother's worked outside the home may benefit from the school meals system. Although children selected for welfare support were smaller than other children, in so far as the design of the study allowed school meals during the 1970s did not increase the rate of growth of primary school children in any social stratum.",1
"Rona, R J, Chinn, S, Smith, A M",2
Concentration of 18:1 and 16:1 transunsaturated fatty acids in the adipose body tissue of decedents dying of ischaemic heart disease compared with controls: analysis by gas liquid chromatography.,0
"Proportions of ""lower"" 16:1 and 18:1 trans acids (TL) and ""higher"" C20 and C22 trans acids (TH) in samples of depot fat taken at postmortem examination from 136 people who had died of ischaemic heart disease (cases) and from those who had died of unrelated causes (controls) have been determined. Whereas mean percentages of TH are virtually identical for cases and controls, the mean value of TL was significantly higher for the case specimens. Although these lower trans acids are present in small amounts in ruminant-animal fat, they are more characteristic of commercially hydrogenated fats. We conclude, therefore, that the cases consumed on average a higher proportion of those hydrogenated fats rich in 16:1 trans and 18:1 trans acids and a lower proportion of ruminant fat than did the controls.",1
"Thomas, L H, Winter, J A, Scott, R G",2
Concentration of transunsaturated fatty acids in the adipose body tissue of decedents dying of ischaemic heart disease compared with controls.,0
"The constituents of the fat of 136 decedents who had died of ischaemic heart disease are compared with the constituents of the fat from 95 controls who had died from other causes. The cases had a lower concentration of fatty acids (L) characteristic of ruminant animal fat and a higher concentration of total transunsaturated acids (T), but the concentrations of certain higher (C20 and C22 mostly monoenoic) acids (H) were similar. The ratio T/L was higher in the cases, which suggests that the cases may have consumed more hydrogenated fats in life than had the controls. The ratio T/L increased linearly with H within both the case and control specimens, which suggests in view of the similarity in the mean levels of H that the difference in trans contents may be concentrated in the lower (18:1 and 16:1) trans acids.",1
"Thomas, L H, Winter, J A, Scott, R G",2
Risk indicators of reduction limb defects.,0
"The birth of a child with a reduction limb defect (RLD) was evaluated in relation to vaginal bleeding, threatened abortion, and other complications of pregnancy, placental weight, birth weight, family history, parental age, and the outcome of previous pregnancies. The material consisted of 453 cases of reduction limb defect and an equal number of non-malformed controls matched for time and place. The children were born in Finland during 1964-77. The cases with reduction limb defect without additional malformations were analysed separately. Statistically significant associations were found between the occurrence of reduction limb defect and the following risk indicators: vaginal bleeding, threatened abortion, duration of gestation under 37 weeks, placental weight 400 g or less, birth weight 2500 g or less, and any type of malformation in the relatives. Vaginal bleeding indicated the risk of reduction limb defect to be increased about fourfold; short gestation indicated about twofold risk of reduction limb defect as an isolated malformation. Both low placental weight and low birth weight were associated to a threefold risk of an isolated reduction limb defect. These factors of an abnormal pregnancy indicated even higher risk of reduction limb defect with additional malformations. Preliminary genetic analysis suggests that hereditary factors play no major part in the aetiology of reduction limb defects.",1
"Aro, T, Heinonen, O P, Saxén, L",2
Prediction of duration of breast feeding in primiparas.,0
"A random sample of 617 primiparas was identified from birth notifications over a 12 month period and 534 of these were interviewed four weeks after confinement. Those breast feeding at the time of interview were contacted again at four months and those still breast feeding then were contacted at six and a half months. Duration of breast feeding was found to be significantly associated with five interassociated personal characteristics of the mother and with specific aspects of her knowledge and attitudes regarding breast feeding. In hospital the timing of the first breast feed and difficulties with subsequent feeds, were important indicators; while at home the use of additional formula feeds was associated with a reduced prevalence of breast feeding by 18 weeks. A combination of older maternal age at confinement and older age at leaving school showed a tenfold increase of prevalence rates in breast feeding at 16 weeks between groups of mothers. The use of these two factors alone may thus help doctors, midwives, and health visitors in assessing the risk of premature termination of breast feeding and in planning programmes of preventive care.",1
"Wright, H J, Walker, P C",2
Family type and accidents in preschool children.,0
"Children living in single-parent families or stepfamilies were found to be more likely to suffer accidental injuries in their first five years of life than children living with two natural parents. Frequent household moves, low maternal age, and perceived poor behaviour in the child were all more strongly associated with overall accident rates than family type, and these disadvantages were more common in atypical families. Family type appeared to be the most important influence on hospital admission after accidents. Overall, there was a close similarity in accident rates between children of single-parent families and stepfamilies, and both groups were more at risk than children living with both natural parents.",1
"Wadsworth, J, Burnell, I, Taylor, B, Butler, N",2
"Antenatal care in Maputo, Mozambique.",0
"Mozambique, within its plan for overall social and economic change, has given priority to primary health care with a principal focus on maternal and child health. In 1980 an antenatal control form was introduced into all Maputo's antenatal clinics to monitor pregnancies and to help direct specialist care to mothers at greatest risk--a strategy known by WHO as the ""risk approach."" In this study three health centres were selected from contrasting areas of the city. Almost 1000 completed antenatal forms were analysed to determine incidence of risk and to evaluate the implementation of this strategy. It was found that: (1) a considerable number of women at risk were identified, referred, and successfully monitored through their pregnancy. (2) Of those women at risk who were identified by the health centres, fewer than half were actually referred for specialist care. (3) Those women at greatest risk were not the highest users of the services, and many of them underused the services compared with those at lower risk. (4) The level of risk and child mortality varied with a measure of urban quality of the areas in which the centres were located.",1
"Jelley, D, Madeley, R J",2
Multiple sclerosis and birth order.,0
"Studies on the birth order of patients with multiple sclerosis have yielded contradictory conclusions. Most of the sets of data, however, have been tested by biased tests. Data that have been submitted to unbiased tests seem to suggest that cases are more likely to occur in early birth ranks. This should be tested on further samples and some comments are offered on how this should be done.",1
"James, W H",2
"Social class mortality differentials: artefact, selection or life circumstances?",0
"Data from 10 years follow up of mortality in the OPCS Longitudinal Study are used to relate deaths of men in 1976-81 to their social class as recorded by the 1971 census. Explanations of social class mortality differentials are critically reviewed in the light of these new data. The similarity between the class differentials observed for men aged 15-64 years in this study and those reported in the 1970-2 Decennial Supplement on Occupational Mortality indicate that the published gradients were not in fact grossly distorted by numerator denominator biases. Distortions to gradients observed in the early years of the longitudinal study and ascribed to selective health related mobility out of employment from the principal social classes to the permanently sick had largely worn off after five years of follow up. Sharp gradients at ages over 75 years, similar to those at younger ages, suggest that, for men aged over 50 years, selective health related mobility between social classes does not contribute to differentials in mortality.",1
"Fox, A J, Goldblatt, P O, Jones, D R",2
Mortality ratios and life expectancy in X chromatin positive males.,0
In a prospective study of 466 X chromatin positive males an increase in mortality of about 50% has been observed. The increase is associated with a loss of about five years in life span. There is no convincing evidence that the increase is concentrated at any particular age group but this possibility could not be excluded. No effect of mode of ascertainment could be demonstrated. From this study we conclude that it is likely that the mortality experienced by chromatin positive males in general is at least 115% of that experienced by normal men and could be more than 200%.,1
"Price, W H, Clayton, J F, Collyer, S, de Mey, R",2
"Childhood cancer in the Northern Region, 1968-82: incidence in small geographical areas.",0
The place of residence of all cases of childhood cancer occurring in the Northern Region from 1968 to 1982 has been analysed by electoral wards. The wards have been ranked according to rate and Poisson probability. Both rankings show a wide geographical scatter throughout the region of areas with an apparent excess incidence of cancer. These areas are not confined to the Cumbrian coast.,1
"Craft, A W, Openshaw, S, Birch, J M",2
Mortality from congenital malformations by mother's country of birth.,0
"Mortality from congenital malformations by mother's country of birth was examined in England and Wales between the years 1976 and 1980, based on stillbirths and infant deaths. There were 18 870 stillbirths and infant deaths attributed to congenital malformations in this period, of which 2 375 (13%) were to mothers born outside the United Kingdom. There were excess deaths from malformations among Pakistani, Indian/Bangladeshi, African, and Irish mothers. In contrast, West Indian mothers had a consistent deficit in deaths from malformations over the study period. The significance of these findings is discussed.",1
"Balarajan, R, McDowall, M",2
The demand for health: theory and applications.,0
"The concern of this paper lies with the economic theory of the ""demand for health"". It develops a conceptual apparatus for analysing the interaction of socioeconomic determinants of health and indicates how this can be used to shed light on a variety of topical policy issues such as socioeconomic inequalities in health and the design of prevention policies. It is written with the aim of making what has hitherto been a mathematically sophisticated literature accessible to the non-economist.",1
"Wagstaff, A",2
Comparison of chiropractic and hospital outpatient management of low back pain: a feasibility study. Report of a working group.,0
"This is the report of a feasibility study of a randomised controlled trial of chiropractic and hospital outpatient management for low back pain of mechanical origin. Preparations for the study included an approach to the General Medical Council for guidance about the intended collaboration between medically qualified and heterodox practitioners, detailed communication with local general practitioners, and the provision of a Medical Research Council (MRC) grant to cover payments to the chiropractors for work carried out in the course of the study. A total of 238 patients were considered, 197 of whom had initially presented to Northwick Park Hospital and the remaining 41 to the chiropractic clinic in Harrow. Only 6% of the patients presenting to the hospital refused to enter. The single most frequent reason for ineligibility in the hospital patients was freedom from pain at the time of the first hospital visit (23%). A variety of medical contraindications accounted for the exclusion of a further 24% of hospital patients. Patients presenting to the chiropractic group tended to have had shorter current episodes of back pain but to have had more NHS treatment in the past than those presenting to hospital. The commonest reason for exclusion among those presenting to the chiropractic clinic was refusal to enter (34%). Only 5% of the chiropractic patients were ineligible for medical reasons. Overall, 16% of those presenting to hospital and 44% of those presenting to the chiropractors were eligible and willing to enter the randomised treatment phase of the study. Of the 50 patients who entered the treatment phase, all but seven completed treatment and the six weekly self-completed assessments of progress. Patients whose current episodes had lasted less than a month progressed significantly more rapidly than those with longer current episodes. It is likely that sufficient numbers of patients with low back pain are prepared to take part in a formal randomized controlled trial. The organization and working methods for such a trial appear to be feasible. A full scale multicentre trial should aim to include about 2000 patients.",1
Parental occupations and cancer: a review of the literature.,0
"Parental occupation is a suspected risk factor in the occurrence of childhood cancer. Fourteen epidemiological studies investigating a possible association are reviewed and observations are found to be contradictory. Several reports show significant associations for occupations involving exposure to hydrocarbons, lead or chemicals and occupations of social classes I and II. Conversely, some studies find no association at all. Methodological variations do not account for the contrasting results so further investigation is required.",1
"Arundel, S E, Kinnier-Wilson, L M",2
Effect of a lactation nurse on the success of breast-feeding: a randomised controlled trial.,0
"An evaluation of a lactation nurse by means of a randomised controlled trial is described. The lactation nurse was employed to assist, support, and encourage mothers during the early weeks after parturition in hospital and at home. All mothers who breast-fed at least once were entered into the trial. Altogether 649 mothers were interviewed 12 months later to establish the duration of breast-feeding and to enquire after practices of and attitudes towards infant feeding. The lactation nurse significantly extended the duration of breast-feeding, particularly during the first four weeks and among women of lower social class. Although she did not reduce problems or change practices significantly, all the trends were consistently in the right direction. Mothers in the experimental group were more satisfied with the help they received than were mothers in the control group. It seems likely that the lactation nurse by consistent advice, assistance, support, and encouragement enabled mothers to cope more successfully with difficulties and that this led to significantly fewer ending breast-feeding prematurely.",1
"Jones, D A, West, R R",2
Social and family factors in childhood hospital admission.,0
"The relation between social, economic, and family life event measures and rates of hospital admission during the period from birth to 5 years was studied in a birth cohort of New Zealand children. Both family social background and family life events made a significant contribution to the variability in the risk of hospital admission. However, economic factors made no significant contribution to rates of admission when the correlated effects of family social background and life events were taken into account. In addition, the effects of family life events on risks of admission appeared to be far more marked than the effects of family social background. Possible explanations of the consistent association between life events and rates of morbidity during early childhood are discussed.",1
"Fergusson, D M, Horwood, L J, Shannon, F T",2
Increase in hospital admissions for torsion of testis.,0
"Data from Hospital Activity Analysis (HAA) for the Wessex Health Region show a 70% increase in hospital admissions for torsion of the testis between 1971 and 1982. The frequency of emergency admission leading to orchidopexy doubled, but there was no increase in the rate of emergency admission followed by orchidectomy. Detailed investigation of records from Southampton hospitals suggests that the trend cannot be explained by errors in the ascertainment of cases by HAA. The rise in admissions could result from a greater awareness of the diagnosis among general practitioners leading to more frequent referral of mild cases, but it seems more likely that it reflects a real increase in the incidence of the disorder.",1
"Nelms, M, Coggon, D",2
"Reduction of tar, nicotine and carbon monoxide intake in low tar smokers.",0
"Blood nicotine, cotinine, and carboxyhaemoglobin (COHb) concentrations were measured in 392 smokers (255 women and 137 men) of ""middle tar"" (17-22 mg), ""low to middle"" (11-16 mg), and ""low tar"" (less than 11 mg) cigarettes. Since tar intake cannot yet be measured directly, we devised an index to estimate it based on the use of measured levels of an intake marker (eg, blood nicotine) and the ratio of the tar to marker yields of the cigarettes. This approach was validated by its ability to enhance the prediction of levels of one marker by use of another. In a practical test, using COHb and the CO/nicotine yield ratio of the cigarettes, the mean blood nicotine concentration of the low tar smokers was predicted to be 31.9 ng/ml compared with the measured mean of 31.8 ng/ml. Our main findings were that despite substantial compensatory increases in inhalation, the low tar smokers took in about 25% less tar, about 15% less nicotine, and about 10% less carbon monoxide than smokers of middle and low to middle tar cigarettes. These results indicate that low tar cigarettes of the type available in Britain since the late 1970s are likely to prove less harmful than other brands. Monitoring of smoke intakes could supplement epidemiological approaches and provide earlier evidence of whether changing cigarette designs lead to any significant dosage reduction that could affect the risk of disease.",1
"Russell, M A, Jarvis, M J, Feyerabend, C, Saloojee, Y",2
Prevalence of goitre and hypothyroidism in Southern Tanzania: effect of iodised oil on thyroid hormone deficiency.,0
"In the Southern Highlands of Tanzania the prevalence of endemic goitre due to iodine deficiency is in the range of 90% and hypothyroidism in the range of 50% of schoolchildren. The present study confirms these data and documents the beneficial effect of Lipiodol injections on thyroid function in children around the age of puberty compared with untreated children from the same villages. On the other hand, a decrease in the prevalence of goitre could not be shown. A beneficial effect is shown for infants of mothers who received iodine during pregnancy. It seems that this form of supplementation is sufficient for breast fed children for more than three years, even when a second child has been delivered in the meantime. In contrast, older siblings of these babies may become hypothyroid when breast feeding is stopped. The determination of thyroid autoantibodies in iodine treated and untreated children and in young adults showed no increasing prevalence of positive findings thus excluding iodine induced chronic thyroiditis at least in the young target population.",1
"Wächter, W, Mvungi, M, König, A, Pickardt, C R, Scriba, P C",2
Lifestyle changes in long term survivors of acute myocardial infarction.,0
"A retrospective questionnaire and interview study of 10 year survivors of uncomplicated myocardial infarction examined smoking, diet, exercise, weight, medication, and treatment since discharge from hospital in 1973-4 and made comparisons with controls (using the same questionnaire) and with normal populations (as reported by others). Long term survivors of myocardial infarction previously smoked more than controls; made more dietary changes than controls; and presently eat less butter, sugar, cake, and biscuits and drink less milk than controls; previously weighed more than controls; exercised less than controls both previously and presently; use more 'non-cardiac' as well as 'cardiac' drugs than controls; and are more depressed and more anxious than controls.",1
"West, R R, Evans, D A",2
Phlegm production and lung function among cigarette smokers changing tar groups during the 1970s.,0
"In 1971-3 data on smoking habits, cigarette brand smoked, morning phlegm production, and lung function were recorded for factory workers as part of the Heart Disease Prevention Project. These men were reassessed in 1984 and those who had always smoked cigarettes from the same tar group were compared with those who had dropped one tar group (mean decreases of 6.6 mg tar, 0.1 mg nicotine) and two tar groups (mean decreases of 11.9 mg tar, 0.5 mg nicotine). Over the 13 years, men who had dropped one tar group were significantly more likely (p less than 0.05) to stop producing phlegm, but the effect was less marked for those who had dropped two tar groups. The mean fall in FEV1 was similar in all three groups, but 95% confidence limits showed that although dropping one tar group could be associated with at most a saving of 84 ml over the follow up period, there could be little extra benefit from dropping two tar groups. In 1984, all three groups of smokers excreted similar amounts of nicotine metabolites in the urine, suggesting that men who had dropped two tar groups compensated for the reduced nicotine yield of their cigarettes. This could account for the lack of a dose response relationship between reduction in the tar yield of cigarettes and cessation of phlegm and fall in FEV1.",1
"Peach, H, Hayward, D M, Ellard, D R, Morris, R W, Shah, D",2
Community hospitals in Oxfordshire: their effect on the use of specialist inpatient services.,0
"About one-third of the general practices in the Oxfordshire Health District have access to beds in community hospitals as well as district general hospitals. Hospital Activity Analysis data were used to calculate the average number of hospital beds occupied daily by patients registered with each general practice in the district. Practices with and without access to community hospitals were compared to determine whether such access was associated with a reduction in the use of beds in general medical, geriatric, and other specialties, and an increase in overall utilisation rates. The rate of use of general medical and geriatric beds in district general hospitals by practice populations with access to community hospitals was about half that of populations without such access. Utilisation rates overall, combining the use of beds in both district general hospitals and community hospitals, were a little higher in populations with access to both community hospitals and district general hospitals than in those with access to district general hospitals only.",1
"Baker, J E, Goldacre, M, Gray, J A",2
The natural history of asthma in childhood.,0
"The incidence and prognosis of childhood asthma and wheezing illness (AW) was studied using data obtained at ages 7, 11, and 16 from a national cohort of 8806 children born in 1958. By the age of 16, 24.7% were reported to have experienced at least one episode of AW. In 18.3% AW had started before the age of 8, but only 4.2% continued to have symptoms in later childhood. A further 3.6% began to have AW between the ages of 8 and 11, and 2.8% began between the ages of 12 and 16. Of those with AW at age 7, 28.3% had symptoms at 11 and 16.5% at 16; these proportions were about doubled if AW at 7 had been severe. The associations between natural history and a large number of perinatal, social, environmental, and medical factors were examined. Those which predicted the onset of AW after the age of 7 were: male sex of child; mother aged 15-19 at child's birth; history of pneumonia, whooping cough, throat or ear infections or tonsillectomy; eczema, allergic rhinitis; and periodic vomiting or abdominal pain.",1
"Anderson, H R, Bland, J M, Patel, S, Peckham, C",2
Distribution of episodes of mental illness in general practice: results from the Second National Morbidity Survey.,0
"The Second National Morbidity Survey, conducted in England and Wales between 1970 and 1976, contains a unique body of information on episodes of mental illness experienced by individuals registered in a representative sample of general practices around the country. This information is used to construct the episode distribution among the individuals surveyed. The Poisson and negative binomial distributions are then used to model the episodes. The Poisson model gives a very poor fit but the negative binomial model is found to fit the data very well. Deviations of the observed data from this model are discussed. The possibility of applying this model at the local practice level is then considered.",1
"Smeeton, N C",2
The elderly at home: indices of disability.,0
"The physical status of all people aged 75 and over living in and around Melton Mowbray was assessed by the responses to a series of questions on the activities of daily living that the respondents could perform. Three methods of producing an index of disability from these separate questions are investigated: principal component analysis, Guttman scaling, and a variation of Guttman scaling known as severity grading. All the methods produced very similar rankings of persons, confirming the suggestion of Bebbington that the choice of scaling method is of little consequence. Two scales emerged: one measuring physical ability and the other the level of urinary and faecal incontinence.",1
"Jagger, C, Clarke, M, Davies, R A",2
Use of the Nottingham Health Profile with patients after a stroke.,0
"The Nottingham Health Profile (NHP) is easy to use with stroke patients and may be used with those who cannot manage more complicated mood questionnaires, such as the General Health Questionnaire (GHQ). Stroke patients rate their health, and especially emotions and feelings of social isolation, as much worse than that of people of similar age. NHP emotion scores correlate with objective measures of disability, length of hospital stay, and GHQ scores. The NHP is a valid indicator of depressed mood, and combining its components into a total score gives the greatest accuracy in detecting depression. Patients with high scores at one month continued to report large numbers of problems at six months after their stroke. Many patients experienced pain, disturbed sleep, and social isolation, which are important, potentially treatable problems not usually considered in the management of stroke patients. Many patients with problems did not see their general practitioner or any other source of help, and additional follow up was needed.",1
"Ebrahim, S, Barer, D, Nouri, F",2
Further evidence of a fall in blood lead levels in Wales.,0
"Random samples of residents in North Wales, some of whom had been seen in 1976 and others in 1981, were seen again in 1984. Blood lead estimations indicated that there had been a fall of about 5% per year. This is similar to the fall we estimated from two previous studies in Wales and is comparable to changes described in the USA and New Zealand.",1
"Elwood, P, Toothill, C",2
Blood pressures higher in the home than in the clinic in rural Kenya.,0
"The conditions under which blood pressures (BPs) are recorded are critical, and it has been demonstrated several times that BPs measured in the home are lower than those measured in the clinic. However, these comparisons are based on home BPs measured by the patients or their friends and relatives and clinic BPs measured by doctors and nurses. To our knowledge, no comparison of home and clinic BPs measured by the same observer has been reported, and we present the results of such a study which is the first to demonstrate higher BPs in the home environment, perhaps reflecting the unacculturated nature of the study population.",1
"Poulter, N R, Lury, J D, Thompson, A V",2
Blood pressure and salt intake in Malawi: an urban rural study.,0
"A significant difference between the blood pressures of rural and urban Malawians was found in both sexes, was present at the age of 15 years, and was associated with obesity but not with smoking, alcohol consumption, occupation or housing. Pulse rate was significantly lower in the urban group. These differences were accompanied by low potassium and sodium intake although the sodium intake in the urban group was double that in the rural group. No direct relation between blood pressure and urinary electrolytes was found.",1
"Simmons, D, Barbour, G, Congleton, J, Levy, J, Meacher, P, Saul, H, Sowerby, T",2
Seasonal variations in cryptorchidism.,0
The month of birth of boys undergoing orchidopexy in the Oxfordshire Health District during the years 1974-83 was analysed. A significant seasonal variation with a peak in April was found for those boys operated upon by paediatric surgeons at a young age (0-4). Possible causes of this variation and its relationship to the aetiology of cryptorchidism are discussed.,1
"Jackson, M B, Swerdlow, A J",2
Recent trends in mortality due to testicular cancer in Ireland: a comparison with England and Wales.,0
"In the period 1961-84, the number of deaths in Ireland due to the testis cancer rose by 64%. This was due both to significant male population expansion (25.3%) and to an increased mortality rate. In the 25-34 years age group, one of the groups at highest risk, the mortality rate rose by 123%. In contrast, in England and Wales, although the male population has risen by 8.5% since 1961, the number of deaths has decreased by 17%. This is due to falling mortality rates, for example an 18% decrease in those aged 25-34 years. The highest rate of all occurred in those Irish over 75 years old. The changing Irish trends appear to lag behind those in England and Wales by some decades, and this raises important aetiological considerations.",1
"Thornhill, J A, Conroy, R M, Kelly, D G, Walsh, A, Fennelly, J J, Fitzpatrick, J M",2
Maternal smoking and low birthweight: implications for antenatal care.,0
"The incidence of low birthweight has been related to smoking prevalence in each social group using published data for 1984. The attributable risk of low birthweight has been estimated, based on a relative risk of 2 for mothers who smoke during pregnancy. Assuming 12.5% of cigarette smokers stopped smoking during pregnancy, 18.1% of all low weight births were caused by maternal smoking in 1984. The percentage for most social groups was similar. The overall attributable risk from smoking was estimated to be 12.7 low weight births per 1000 total births, with a further 12.1 per 1000 due to other factors acting in a socioeconomic gradient. We estimate that the minimum attainable low birthweight incidence in 1984 was 45.4 per 1000 total births, based on the lowest observed incidence, corrected for smoking prevalence, which was in social group II. We recommend the addition of maternal smoking information to the Korner maternity clinical options data set, to enable an accurate assessment of the risks and to provide local monitoring of initiatives to reduce smoking prevalence during pregnancy.",1
"Simpson, R J, Armand Smith, N G",2
"Ethnic group differences in low birthweight of live singletons in Singapore, 1981-3.",0
"All singleton live births occurring in Singapore in the three years 1981-3 were computed, and birthweight was examined in the different ethnic groups (Chinese, Malay, and Indian). Overall the proportions of babies of very low birthweight (less than 1500 g) and low birthweight (less than 2500 g) were: Chinese 0.3% and 6.1%, Malays 0.4% and 8.5%, and Indians 0.5% and 10.0%. The important finding was that in all gestational periods and virtually all maternal age and live birth order groups Indians had the highest proportion of very low and low birthweight babies. However for prematurity Indians at 6.7% had a higher rate than Chinese (5.1%) but lower than Malays (9.9%). Likewise for neonatal mortality Indians at 8.7 per 1000 live births were between Chinese (7.1) and Malays (9.1). The evidence seems to indicate that the reason for Indians having a higher proportion of low birthweight babies is partly ethnic/genetic, and the cut-off point of 2500 g should perhaps be lowered for babies from the Indian subcontinent when international comparisons are being made.",1
"Hughes, K, Tan, N R, Lun, K C",2
Early oral contraceptive use and breast cancer: theoretical effects of latency.,0
"Many cancers and other chronic diseases are associated with a long delay between exposure to a putative risk factor and subsequent diagnosis. This presents well recognised problems in the elucidation of suspected risk factors by epidemiological methods. In this paper we discuss the interpretation in epidemiological studies of the effect of a possible risk factor when population exposure is recent and rapidly changing. An important contemporary example concerns the study of early oral contraceptive (OC) use in relation to the subsequent risk of breast cancer. Computer simulations reported here indicate that plausible delays in the manifestation of any effect on breast cancer incidence make it difficult to exclude early OC use as a risk factor for breast cancer, even when large well conducted epidemiological studies show no apparent increased risk. Methods for detecting a 'latent' effect are discussed.",1
"McPherson, K, Coope, P A, Vessey, M P",2
Perinatal outcomes and related factors: social class differences within and between geographical areas.,0
"This paper makes use of the opportunity provided by comparable obstetric data bases to examine area and social class variations in perinatal outcome and associated factors in areas smaller than those usually reported. Analyses are based on singleton births to primiparous residents in the catchment areas of the Aberdeen Maternity and Neonatal Database (n = 4948) and the Cardiff Births Survey (n = 11893) between 1976 and 1981. The factors considered relate to the obstetric population (height, age, and smoking), obstetric practice (induction and assisted delivery), and perinatal outcome (curtailed gestation, low birthweight, and perinatal death). Our analysis confirms the existence of both area and social class differences and suggests that, except in the case of teenage pregnancy and smoking, the association observed between those factors and area and social class are largely independent of each other.",1
"Elbourne, D, Pritchard, C, Dauncey, M",2
Distribution of body weight and height: comparison of estimates based on self-reported and observed measures.,0
"The distribution of weight in the adult population aged 20-69 years was examined by comparison of estimates obtained from the 1985 Health Promotion Survey and the 1981 Canada Fitness Survey. The Health Promotion Survey obtained information on self-reported weight and height, and the Canada Fitness Survey utilised measured weight and height. The classification of respondents into weight categories followed the recommendations of the 1973 Fogarty Conference on Obesity. Values of the Quetelet index defined as W/H2, where W = kilograms and H = metres, were used to define four weight categories: underweight, acceptable weight, overweight, and obese. The comparisons of prevalence estimates of the various weight categories indicate that self-reported weight and height leads to a systematic weight misclassification bias. The implications of this bias for epidemiological studies are discussed and suggestions are offered to handle the bias.",1
"Millar, W J",2
"Heart rate, employment status, and prevalent ischaemic heart disease confound relation between cereal fibre intake and blood pressure.",0
"Cross sectional data from a survey of 2512 men aged 45-49 years were used to examine the confounding effects of heart rate, employment, and ischaemic heart disease (IHD) on the relation between cereal fibre intake and blood pressure. Daily cereal fibre intake (g/day) was associated with systolic pressure (r = -0.053, p less than 0.01), diastolic pressure (r = -0.057, p less than 0.01), and heart rate (r = -0.071, p less than 0.01). The associations were strengthened in employed men and inapparent in unemployed men. Unemployed men had more IHD than employed men. Persons with any manifestation of IHD had significantly higher blood pressure and heart rates but ate less cereal fibre (7.0 v 7.9 g/day, p less than 0.001) than those without IHD, regardless of employment status. In employed men, after adjustment for age, body mass index, prevalent IHD, and heart rate, systolic pressure changed -0.186 mmHg (95% CI = -0.362, -0.009) and diastolic pressure changed -0.111 mmHg (95% CI = 0.228, 0.005) for each gram of cereal fibre eaten daily. The association between cereal fibre and blood pressure was inapparent in unemployed men. Heart rate, employment, and prevalent IHD confound the association between cereal fibre intake and blood pressure. Future work concerning this relationship will have to account for the effects of these variables.",1
"Lichtenstein, M J, Burr, M L, Fehily, A M, Yarnell, J W",2
Edinburgh breast education campaign on breast cancer and breast self-examination: was it worth while?,0
"A health education campaign was carried out at the start of a large trial of screening for breast cancer in Edinburgh. After preliminary studies the campaign concentrated on talks to small groups of women by specially trained health visitors. Over a year, 12,000 women attended. Systematic evaluation after 12 months showed that selected women who heard the talks were more knowledgeable about breast cancer, and a random sample of women in Edinburgh had a small but significant improvement in knowledge compared with women in Aberdeen. However, the random sample did not report an increase in the practice of breast self-examination (BSE) and there was no increase in workload for general practitioners. It is suggested that BSE is more likely to be accepted if combined with a physical examination.",1
"Roberts, M M, Robinson, S E, French, K, Proudfoot, A, Talbot, H, Elton, R A",2
Mortality and causes of death in females with extra X chromosomes and males with extra Y chromosomes.,0
A prospective study of mortality in females with extra X chromosomes and males with extra Y chromosomes is reported. Among the 94 females who survived infancy and were then observed on average for 16 years there were 24 deaths compared with an expected mortality of 10.7. The greater than twofold increase is highly significant (p less than 0.005). The deaths were due to a variety of diseases but no significant increase from any single cause could be identified. Among 136 males with extra Y chromosomes observed on average for 12 years there were 10 deaths. This number is not significantly greater than the expected 6.4. No increase in mortality from a single cause was observed.,1
"Price, W H, Clayton, J F, Collyer, S, De Mey, R",2
Epidemiology of multiple sclerosis in the north-east (Grampian region) of Scotland--an update.,0
"The north-east of Scotland (Grampian Region) has undergone three incidence and prevalence surveys, including the present one, since 1970. Results from these indicate a true increase in the prevalence of the disease in the region. The incidence of the disease has remained continuously high and shows a slightly upward trend. Literature on the subject of repeated surveys in different regions of the world has been reviewed in detail. The need for a prevalence study from the south of the British Isles has been emphasised in order to enable one to judge if the increase in Scotland is in keeping with the pattern in the whole of the British Isles. The familial incidence of the disease was noted to be virtually unchanged between the three surveys. Certain other aspects of aetiological significance have been analysed, viz, clustering of patients at birth or at onset of the disease; ages of occurrence of childhood viral infections such as measles, mumps, chickenpox and rubella; and the role of canine distemper infection.",1
"Phadke, J G, Downie, A W",2
Multiple sclerosis and motor neurone disease: survival and how certified after death.,0
"This study assesses the outcome of a random sample of patients with multiple sclerosis (MS) and motor neurone disease (MND) selected from a previous study carried out between the years 1960 and 1972. Of the MND patients who are now dead, 20% of the women and 27% of the men lived longer than five years after hospitalised diagnosis, and two of these patients lived up to 19 years after diagnosis in hospital. Also, 10.7% of the random sample of MND patients were still alive in June 1985. Of the MS deaths 26.4% and of the MND deaths 20.4% did not have these respective conditions recorded on the death certificates.",1
"O'Malley, F, Dean, G, Elian, M",2
Incidence of motor neurone disease in the northern region.,0
"The incidence of motor neurone disease in the Northern Region was studied for the year 1981 by means of hospital activity analysis records and questionnaire. The crude incidence rate was 2.2 per 100,000. This was not significantly different from the rate determined by using death certification. The age standardised incidence ratio for the region was 163 using the 1976 population and deaths from motor neurone disease in England and Wales as the reference. The female to male ratio was 1:1.8 and the average age of diagnosis was 63 years. No meaningful intraregional variation was observed. Thus mortality appears to reflect incidence fairly accurately.",1
"Qizilbash, N, Bates, D",2
Association of infant alimentary and respiratory illness with parental smoking and other environmental factors.,0
"The incidences of alimentary and respiratory illnesses were observed during the first year of life in 1565 infants born in Tayside during 1980. Significant correlations (p less than 0.05) were found between each of these outcomes and parental smoking, maternal age, social class, method of infant feeding, and heating fuels. Multiple logistic regression indicated a significant independent effect of parental smoking was related separately to alimentary and to respiratory outcomes, the relative risks being of similar strength.",1
"Ogston, S A, Florey, C D, Walker, C H",2
Relation between cigarette smoking and use of hormonal replacement therapy for menopausal symptoms.,0
"The aim of this study was to characterise new users of hormonal replacement therapy (HRT) for the relief of menopausal symptoms and to compare these women with never-users of HRT; 402 new users and 804 never-users were studied. Hot flushes were the most common symptom in both users and non-users and were the most frequent reason for prescribing HRT. The prevalence of menopausal symptoms in non-users of HRT was high although substantially lower than that in users. HRT users were more likely to be current cigarette smokers than were never-users. There was also, within smokers, a significant relation between the number of cigarettes smoked and the likelihood of using HRT. This relation between HRT use and smoking could result from an anti-oestrogen effect of smoking, intensifying menopausal symptoms. Of potential clinical relevance is the suggestion that a proportion of women using HRT may be doing so in order to alleviate smoking-induced symptoms. Users of HRT were also more likely to have used oral contraceptives than were never-users; this relation was probably behavioural.",1
"Greenberg, G, Thompson, S G, Meade, T W",2
The Copenhagen case-control study of bladder cancer: role of smoking in invasive and non-invasive bladder tumours.,0
"A population based study of 388 cases of bladder cancer including papillomas and 787 controls in Greater Copenhagen confirmed the role of smoking in the aetiology of bladder cancer. Significantly increased relative risks were found for persons who had smoked only cigarettes (RR = 2.9; both sexes combined) and for mixed smokers including cigarettes (RR = 3.6; both sexes combined). Multiple logistic regression analysis showed significant influences of the amount (pack years) of cigarettes smoked and a reduced risk among persons who had stopped smoking. No significant effects of smoking pipe or cigars/cigarillos were apparent, and the present study does not confirm previous suggestions of associations between the smoking of cigars/cigarillos and bladder cancer in Denmark. Only a slight increase in relative risk with the amount smoked was found. The influence of smoking on bladder cancer risk was similar for tumours in stages T1 and T2-4 at diagnosis and also for tumours of grades 1-2 and grades 3-4 at diagnosis.",1
"Jensen, O M, Wahrendorf, J, Blettner, M, Knudsen, J B, Sørensen, B L",2
Epidemiology of AIDS--statistical analyses.,0
"Some central questions concerning the epidemiology of AIDS are addressed by statistical analyses. Applying standard maximum likelihood theory to reported cases of transfusion-associated AIDS in the US, the mean and standard deviation of incubation time for AIDS are estimated to be about 60 and 19 months, respectively. If these parameters are applied to the data from the San Francisco CDC cohort study, we find a good correspondence between estimated and reported cases of AIDS when the probability factor p is 0.27-meaning that about 27% of those infected with HIV are expected to develop AIDS during a period of 8-10 years. Application of the incubation time model and the probability factor p to the data on transfusion-associated AIDS makes it possible to estimate the number of transfusion-associated infections with HIV from 1978 to 1984. These estimates give an exponential increase in the number of cases, with a relative increase of 2.74 each year. It seems reasonable to assume that this increase reflects the spread of the virus within this period.",1
"Iversen, O J, Engen, S",2
High appendicectomy rates in Ireland: why?,0
Age-specific appendicectomy rates for Ireland have recently been reported to be substantially higher than those for Scotland. We attempted to determine the reason for this difference. Records of 940 appendectomies performed in one urban and one rural centre in Ireland over a 12 month period were examined to establish the frequency of acute appendicitis. Appendicitis rates were derived from these data. Appendicectomy rates are higher in Ireland because the incidence of acute appendicitis is greater than in Scotland or England and Wales and are not the result of variations in medical practice.,1
"Attwood, S E, Cafferkey, M T, West, A B",2
Economic aspects of an epidemic of haemorrhagic conjunctivitis in a rural community.,0
"The estimated economic loss due to an epidemic of acute haemorrhagic conjunctivitis in 1981 in a rural community of Goa studied by house-to-house survey of 7230 families is reported. Thirty-five per cent of families were affected and in 62% of these families more than three persons developed conjunctivitis. The affected were forced to be absent from work resulting in a reduction of the work force (loss of 7735 man days) and loss of income (Rs 1,33,300). The type of treatment followed and estimates of treatment cost are described. The economic consequences to the country of this widespread epidemic are described.",1
"Srinivasa, D K, D'Souza, V",2
Does G6PD deficiency protect against cancer? A critical review.,0
"Previous observations on the lower mortality for cancer experienced in populations with a higher frequency of G6PD deficiency support biochemical studies on the role of G6PD during cell proliferation. The general agreement among experimental studies prevented a deeper analysis of the sources of what has been called ""epidemiological evidence of the protective role of G6PD deficiency against cancer"". This review analyses the methods and findings in those papers, stressing their limitations and emphasising that no final conclusions can be drawn from them. Preliminary results of ongoing epidemiological studies of G6PD deficiency and cancer are presented, although they do not prove or disprove the hypothesis that G6PD deficiency protects against cancer.",1
"Cocco, P",2
Risk factors for breast cancer with applications to selection for the prevalence screen.,0
"There have been many studies of individual risk factors for breast cancer; most of the factors concerned may be broadly grouped into demographic and dietary, reproductive history, endocrine related, family history of breast cancer, and previous history of breast disease. Some of these studies have examined the combined effect of these factors. The present case-control study does this in the context of a randomised controlled trial of breast cancer screening. The relative risks that we have obtained are, in general, of similar magnitude to those in other reports. The relevance of the results to a screening programme is discussed.",1
"Alexander, F E, Roberts, M M, Huggins, A",2
Unemployment and mortality: a small area analysis.,0
"It has been claimed that unemployment affects the health and thus the mortality of the unemployed, their families, and other members of their communities. This paper examines the relation between mortality and the unemployment experiences of small areas which vary in the extent to which their unemployment levels have changed in recent years. Quarterly numbers of unemployed, classified by age, sex, duration of unemployment, and unemployment office for 1977-81, have been aggregated to correspond to Family Practitioner Committee areas (FPCs), for which population and mortality data had been collected for a different study. There was little variation in long term (greater than 6 months) unemployment trends prior to July 1980, but subsequently there were large variations between FPCs in the rate of increase in unemployment rates. Mortality data for suicide, ischaemic heart disease, cerebrovascular disease, and all causes were examined for the period 1975-83. When the mortality trends of FPCs with different unemployment experiences were compared, no statistically significant differences in trends were found, although areas with greater increases in unemployment appeared to have slightly worse mortality trends for suicide, ischaemic heart disease, cerebrovascular disease, and total mortality for men in the younger age groups. If changes in the level of unemployment do have an effect on changes in trends in mortality levels, this effect is not of sufficient magnitude to be statistically significant with the sample available, in spite of the fact that it included the whole of England and Wales.",1
"Charlton, J R, Bauer, R, Thakhore, A, Silver, R, Aristidou, M",2
Toxicity of car exhausts and opportunity for suicide: comparison between Britain and the United States.,0
"The rate of car exhaust suicides in the United States has declined following the introduction of emission controls in the mid-1960s, though not as much as the decline in CO emitted by cars. In Britain, where emission controls have not been introduced, the rate of these suicides, initially much lower than in the United States, has greatly increased since the beginning of the 1970s and is now about double that of the United States. This rise cannot be explained simply on the basis of an increase in the opportunities for suicide as represented by an increase in the number of cars but may be due to increased knowledge of the method. While these results are interpreted as generally supporting the potential for opportunity-reducing preventive measures, they also demonstrate that much more research is needed into the complex nature of the opportunity structure for suicide.",1
"Clarke, R V, Lester, D",2
Birthday and date of death.,0
"The relation between birthday and date of death has so far been studied from two different perspectives: birthdays were either conceived of as emotionally invested deadlines motivating people to ward off their death which causes a 'dip' in death rates before their birthday, or they were considered as stressful events leading to an increase of mortality on or after their birthday. Using a collection of biographies of famous people from the whole world and another of well-known Swiss citizens we tested hypotheses derived from these assumptions. Neither the 'death-dip' hypotheses nor the 'birthday stress' hypothesis was supported by our results.",1
"Angermeyer, M C, Kühn, L, Osterwald, P",2
Changes in blood pressure and body weight over ten years in men selected for glucose intolerance.,0
"Relative changes in body weight and blood pressure over ten years of observation are reported in men recruited for a trial of therapy in relation to the natural history of glucose intolerance. Half were recommended a diet restricting carbohydrate to 120 g daily (diet group) and half were recommended to 'limit use of table sugar' (no diet). In both groups average weight and blood pressure fell over the 12 to 18 months after treatment allocation, the decline being proportionately greater for both variables in the diet group. Subsequently, average weight remained constant up to the end of the ten year study, but blood pressure levels rose, though remaining below baseline levels in the diet group. Statistical analysis of changes in blood pressure and weight between initial (pre-treatment) and third follow-up visit measurement indicated that the proportional change in blood pressure was related principally to change in weight, with little relation to initial level of blood pressure. Although a reduction in weight results in a fall in blood pressure, it does not necessarily prevent a subsequent age related increase in blood pressure.",1
"Jarrett, R J, Keen, H, Murrells, T",2
Tailoring health services to the needs of individual communities.,0
"In order to assess the need for community health services in different neighbourhoods within Greater Glasgow, it was decided to present a wide variety of health information for each community as a set of summary profiles. These profiles clearly demonstrate that the same areas have the highest standardised mortality ratios, the least favourable socioeconomic circumstances, the highest hospital admission rates, and the poorest child health characteristics. The greatest benefit in overall health would be achieved by targeting community resources on these disadvantaged communities. Adoption of this policy should reduce existing inequalities in health, and we argue that such 'positive discrimination' is implied in the formulae used in Great Britain for allocation of revenue expenditure for community services. The health profiles that we describe provide the baseline information necessary to target community services to particular communities according to objective measures, and to evaluate the effectiveness of new and existing methods of health promotion.",1
"Womersley, J, McCauley, D",2
Effect of socioeconomic status on survival from cervical cancer in Sheffield.,0
"The relation between age at registration, socioeconomic status, and survival from cervical cancer for women resident in Sheffield was examined using the 556 such cases registered with the Trent Cancer Registry from 1971 to 1984. The address and electoral ward at registration were used to categorize the socioeconomic status of 99% of the women. Five year survival for all cases was 49%, increasing age having a predictable deleterious effect. Socioeconomic status seemed to have little effect on survival, especially when the covarying effect of age had been taken into account. It is hypothesised that the survival inequalities for cervical cancer demonstrated elsewhere have largely been prevented in Sheffield by good access to effective treatment from the National Health Service.",1
"Milner, P C, Watts, M",2
"Atopy, smoking, and chronic bronchitis.",0
"The aim was to test the hypothesis that atopy increases the occurrence of chronic bronchitis. Relations between atopy, smoking, and chronic bronchitis were studied in farmers. The data were from two successive postal surveys and a skin prick tested subsample. The cross-sectional study consisted of 9017 farmers. Those 6899 farmers who did not have chronic bronchitis at the beginning and who continued farming were followed for three years. A sample of 150 farmers was skin-tested with 36 allergens. The prevalence of chronic bronchitis (rate per 1000), standardised for age and sex, was 41 in non-atopic non-smokers, 101 in atopic non-smokers, 106 in non-atopic smokers, and 257 in atopic smokers (effect of atopy: p less than 0.001; effect of smoking: p less than 0.001). The standardised incidence rates of chronic bronchitis (per 1000 farming years) were 14, 34, 36, and 50, respectively (atopy: p less than 0.001; smoking p less than 0.001). The relative risk of chronic bronchitis, calculated from the incidence data adjusting for the effects of age, sex, smoking or atopy by logistic regression analysis was 2.2 for atopy (95% confidence interval 1.8-2.7) and 2.3 for smoking (1.8-2.9). Only 20 farmers had chronic bronchitis in the skin-tested subjects; the results were consistent with the findings in the surveys but did not reach statistical significance for atopy. In conclusion, atopy and smoking have independent and additive effects on the occurrence of chronic bronchitis at least in dusty farming work.",1
"Terho, E O, Husman, K, Vohlonen, I, Heinonen, O P",2
Maternal drug histories and congenital malformations: limb reduction defects and oral clefts.,0
"In a case control study, prescription data were examined for the three months before the last menstrual period and for the first trimester of pregnancy in (a) 115 mothers of children with limb reduction defects, (b) 676 mothers of children with oral cleft, and (c) an equal number of control mothers of normal babies from the same doctor's practice for each case. In the limb reduction study, the study mothers were prescribed more drugs generally although this did not reach statistical significance, nor were there significant differences between study and control mothers for individual groups of drugs. In the oral cleft study, significantly more drugs were prescribed to study mothers in the three months before the last menstrual period, and a similar trend, which did not reach statistical significance, was observed in the first trimester. Anticonvulsant drugs were prescribed significantly more frequently to study mothers during the whole period of the study. A significant association was also demonstrated between oral contraceptives taken in the three months before the last menstrual period and oral cleft, but doubt must remain concerning this relationship; the risk is not well understood and is likely to be nonspecific. A number of other significant associations were identified, although their importance in practice is uncertain in view of the confounding factors that may affect a study of this kind.",1
"Hill, L, Murphy, M, McDowall, M, Paul, A H",2
Partial sight and blindness in children of the 1970 birth cohort at 10 years of age.,0
"The prevalence and causes of partial sight and blindness (best corrected distant visual acuity of 6/24 or less) have been studied in a nationally representative sample of 15,000 10-year-old children. The prevalence of blindness (acuity less than 6/60) was between 3.4 and 4.0/10,000. All these children had been registered as blind; less than half were in schools for the blind, the remainder were all in other special schools. The prevalence of partial sight (acuity less than or equal to 6/24 greater than or equal to 6/60) was between 5.4 and 8.7/10,000; less than half of these children were in schools for the visually handicapped or partially sighted; most were in ordinary schools; half were neither registered as partially sighted nor ascertained as in need of special education for visual handicap. The most common cause of partial sight or blindness in this cohort was congenital cataract; the second most common was congenital nystagmus. The study identified a number of children whose best acuity on examination was 6/24 or less who had either no ophthalmological diagnosis or who had been diagnosed as suffering from a refractive error. These children have been included in the study because at the time of the survey they had either not been prescribed spectacles or they had spectacles which they were not wearing; the functional visual level of these children was therefore equivalent to that of those defined as partially sighted.",1
"Stewart-Brown, S L, Haslum, M N",2
Lactation and cancer risk: is there a relation specific to breast cancer?,0
"Relations between previous lactation experience and risks of cancer of the breast and other sites were investigated after follow-up of 50,274 parous women from 1961 through 1980. Among women with complete information on lactation, 5102 developed cancer and, of these, 1136 were diagnosed with breast cancer. Analyses of associations with mean duration of lactation per birth and duration for each of the three first births suggested a nonlinear relation to breast cancer. The highest risk was observed for those with intermediate duration of breast feeding, whereas lower risks were found among those with very short or very long duration. For all nongenital cancers combined, decreased risks were observed among those with the longest duration of breast feeding. However, among cancers of specific sites, a significant inverse association was found for pancreatic cancer only. The overall impression given by our data is that breast feeding is not strongly related to risks of breast cancer or any other common cancer.",1
"Kvåle, G, Heuch, I",2
Repeatability of a questionnaire to assess respiratory symptoms in smokers.,0
"To evaluate the repeatability of a questionnaire designed to assess change in respiratory symptoms 90 smokers were interviewed on two occasions. The questionnaire included questions from the Medical Research Council questionnaire on respiratory symptoms, questions on acute chest illness and cough and phlegm production in the preceding two weeks, a modification of Field's card system for estimating frequency of cough, and an objective assessment of the presence of phlegm--the loose cough sign. The study was carried out in two parts. During the first part 30 male smokers were interviewed by one observer and then re-interviewed 1 to 2 hours later by a different observer. During the second part 60 subjects were interviewed and then after a period of 1 to 10 days re-interviewed by the same observer. The results showed that the within-subject variation representing the measurement error for Field's card system was 15.1% of the between-subject variation and was adequately Normal to justify the use of standard analytical techniques. Similar results were obtained from questions on cough and phlegm scored between 1 and 5, although the variation in this case was rather less Normal. In general, the between-observer, within-observer, and within-subject repeatability were satisfactory for all parts of the questionnaire with the exception of the loose cough sign which had a relatively low prevalence. There was no evidence of an observer order effect and there were no important systematic differences due to lapses in time or different observers.The findings indicate that the techniques such as the cough scoring system may be used to permit studies of respiratory symptoms via questionnaire methods to be much smaller than those required to detect equivalent differences in prevalences.",1
"Withey, C H, Price, C E, Swan, A V, Papacosta, A O, Hensley, M J",2
High density lipoprotein cholesterol and longevity.,0
"In the Twin Cities Prospective Study, executive men aged 45 to 55 and ""healthy"" at the entry examinations in 1948 were re-examined yearly to 1975. Follow-up through 1983 lost only one man. High density lipoprotein cholesterol (HDL) in the serum was measured in 1955 with a method checked with recent standard methods. Among 217 men, 130 were dead by 1983, 56 from coronary heart disease (CHD) and 27 from neoplasms. Survivors did not differ in mean HDL from the men who died but they had higher values than the men dead from CHD. Men dead from neoplasms had significantly higher HDL than men dead from CHD. Men dying early did not differ in HDL from those dying later but they had higher blood pressures. HDL was unrelated to age at death from all causes but was related to age at death from CHD. HDL was not related to age, total cholesterol, smoking, or respiratory function but was negatively correlated with measures of body fatness. Multiple regression and multiple logistic analyses showed no difference in HDL between survivors and men dead from all causes, but men dead from CHD tended to have lower HDL. The data indicate that longevity is not related to HDL in middle age.",1
"Keys, A",2
A comparison of methods for increasing compliance within a general practitioner based screening project for colorectal cancer and the effect on practitioner workload.,0
"Screening for colorectal cancer by testing for faecal occult blood (FOBT) is effective for early diagnosis, but the success of a screening programme also depends on compliance. The aims of this study were to assess the effect of health education on compliance and to assess any addition to general practitioner workload that resulted. Altogether 3860 patients were recruited and randomly allocated to test or control group. The test group was further divided into subgroups, some of which received health education. Compliance with FOBT was 54.7% (210/384) in the subgroup receiving only the doctor's letter, which fell to 48.1% (743/1544) in the group receiving health education. General practitioner consultation rates were similar in test and control groups.",1
"Pye, G, Christie, M, Chamberlain, J O, Moss, S M, Hardcastle, J D",2
Urinary iodine excretion correlates with milk iodine content in seven British towns.,0
"In February and May 1986, weekly samples of whole pasteurised milk were collected from the 24 dairies supplying seven British towns. A random sample of 96 women aged 25-64 was drawn from general practitioners' lists in each town, and catch specimens of early morning urine were collected by post from 194 subjects in February and from 186 subjects in May. Median milk iodine concentration was significantly greater in February (235 micrograms/l) than in May (119 micrograms/l). The median urine iodine concentration (expressed per g of creatinine) was also greater in February (106 micrograms/g) than in May (78 micrograms/g). There was a strong and statistically significant correlation between milk and urine iodine concentrations in the seven towns in February (Spearman's r = 0.79, p = 0.04). Within the towns, the change in milk iodine levels between February and May was positively associated with the change in the iodine:creatinine ratio over the same period. There is concern that an excess of dietary iodine may be harmful to some individuals. Should it prove desirable to reduce iodine intakes at the community level, the present results suggest that this could be achieved by a reduction in milk iodine levels, which can be readily brought about by adjusting the levels of iodine in cattle feed.",1
"Nelson, M, Phillips, D I, Morris, J A, Wood, T J",2
Changing mortality patterns in Nauruans: an example of epidemiological transition.,0
"An analysis of mortality data for the years 1982-5 was carried out for the Micronesian population (aged 15 years and over) of the central Pacific Island, Nauru. Among males, the most common causes of death were circulatory system disorders (33.3%), accidents (25.2%), and diabetes mellitus (12.1%). The majority of accidents occurred in the 15-34 year age group and involved motor vehicles. Among females, neoplasms (almost all lung and cervix) (22.4%), circulatory system disorders (20.7%), and diabetes mellitus (17.2%) were the most common causes of death. When accidents are excluded, 59.4% of deaths were in persons with diabetes. Compared with Australia, mortality rates in almost all age groups were at least five times higher for males and females for a comparable period. Nauruan life expectancy (39.5 years for men and 48.5 years for women) is one of the lowest in the world. These data confirm the high mortality associated with diabetes mellitus in Nauruans as evidenced in earlier studies. Modernization of this society through the affluence acquired by the mining of phosphate has led to serious public health problems relating to non-communicable diseases so that the mortality trends now mirror those of developed societies.",1
"Schooneveldt, M, Songer, T, Zimmet, P, Thoma, K",2
Bifunctional rhodamine probes of Myosin regulatory light chain orientation in relaxed skeletal muscle fibers.,0
"The orientation of the regulatory light chain (RLC) region of the myosin heads in relaxed skinned fibers from rabbit psoas muscle was investigated by polarized fluorescence from bifunctional rhodamine (BR) probes cross-linking pairs of cysteine residues introduced into the RLC. Pure 1:1 BR-RLC complexes were exchanged into single muscle fibers in EDTA rigor solution for 30 min at 30 degrees C; approximately 60% of the native RLC was removed and stoichiometrically replaced by BR-RLC, and >85% of the BR-RLC was located in the sarcomeric A-bands. The second- and fourth-rank order parameters of the orientation distributions of BR dipoles linking RLC cysteine pairs 100-108, 100-113, 108-113, and 104-115 were calculated from polarized fluorescence intensities, and used to determine the smoothest RLC orientation distribution-the maximum entropy distribution-consistent with the polarized fluorescence data. Maximum entropy distributions in relaxed muscle were relatively broad. At the peak of the distribution, the ""lever"" axis, linking Cys707 and Lys843 of the myosin heavy chain, was at 70-80 degrees to the fiber axis, and the ""hook"" helix (Pro830-Lys843) was almost coplanar with the fiber and lever axes. The temperature and ionic strength of the relaxing solution had small but reproducible effects on the orientation of the RLC region.",1
"Brack, Andrew S, Brandmeier, Birgit D, Ferguson, Roisean E, Criddle, Susan, Dale, Robert E, Irving, Malcolm",2
Chlamydomonas sensory rhodopsins A and B: cellular content and role in photophobic responses.,0
"Two retinylidene proteins, CSRA and CSRB, have recently been shown by photoelectrophysiological analysis of RNAi-transformants to mediate phototaxis signaling in Chlamydomonas reinhardtii. Here we report immunoblot detection of CSRA and CSRB apoproteins in C. reinhardtii cells enabling assessment of the cellular content of the receptors. We obtain 9 x 10(4) CSRA and 1.5 x 10(4) CSRB apoprotein molecules per cell in vegetative cells of the wild-type strain 495, a higher value than that for functional receptor cellular content estimated previously from photosensitivity measurements and retinal extraction yields. Exploiting our ability to control the CSRA/CSRB ratio by transformation with receptor gene-directed RNAi, we report analysis of the CSRA and CSRB roles in the photophobic response of the organism by action spectroscopy with automated cell tracking/motion analysis. The results show that CSRA and CSRB each mediate the photophobic swimming response, a second known retinal-dependent photomotility behavior in C. reinhardtii. Due to the different light saturation and spectral properties of the two receptors, CSRA is dominantly responsible for photophobic responses, which appear at high light intensity.",1
"Govorunova, Elena G, Jung, Kwang-Hwan, Sineshchekov, Oleg A, Spudich, John L",2
Ultrafast conformational dynamics in cyclic azobenzene peptides of increased flexibility.,0
"Structural changes of peptides containing the azobenzene dye 4-aminomethyl-phenylazobenzoic acid (AMPB) are studied with ultrafast spectroscopy. AMPB peptides are a new class of molecules where the photoisomerizable dye azobenzene is linked to the peptide moiety via a flexible methylene spacer. The ultrafast reactions in the femtosecond to nanosecond time domain are investigated for the optical switch AMPB, a linear and cyclic octapeptide, and a bicyclic octapeptide containing an additional disulfide bridge. These molecules with increasing conformational constraints are studied for the cis to trans and the trans to cis photoreactions. For the cis to trans reaction the isomerization of the chromophore occurs fast in the 1-ps range, whereas it is slower (10-ps range) in the trans to cis reaction. In all peptides the structural changes of the chromophore lead to modifications in the peptide structure in the 10-ps-1-ns time range. The results indicate that the chromophore AMPB acts simultaneously as a fast molecular switch and as a sensor for initial conformational dynamics in the peptide. Experiments in the mid-infrared range where the structural changes of the peptide backbone are directly observed demonstrate that the essential part of the structural dynamics in the bicyclic AMPB peptide occurs faster than 10 ns.",1
"Wachtveitl, J, Spörlein, S, Satzger, H, Fonrobert, B, Renner, C, Behrendt, R, Oesterhelt, D, Moroder, L, Zinth, W",2
In vitro self-assembly of the light harvesting pigment-protein LH2 revealed by ultrafast spectroscopy and electron microscopy.,0
"Controlled ensemble formation of protein-surfactant systems provides a fundamental concept for the realization of nanoscale devices with self-organizing capability. In this context, spectroscopic monitoring of pigment-containing proteins yields detailed structural information. Here we have studied the association behavior of the bacterial light-harvesting protein LH2 from Rhodobacter spheroides in an n,n-dimethyldodecylamine-n-oxide/water environment. Time-resolved studies of the excitation annihilation yielded information about aggregate sizes and packing of the protein complexes therein. The results are compared to transmission electron microscopy images of instantaneously frozen samples. Our data indicate the manifestation of different phases, which are discussed with respect to the thermodynamic equilibrium in ternary protein-surfactant-water systems. Accordingly, by varying the concentration the formation of different types of aggregates can be controlled. Conditions for the appearance of isolated LH2 complexes are defined.",1
"Schubert, Axel, Stenstam, Anna, Beenken, Wichard J D, Herek, Jennifer L, Cogdell, Richard, Pullerits, Tõnu, Sundström, Villy",2
Time-resolved resonance raman structural studies of the pB' intermediate in the photocycle of photoactive yellow protein.,0
"Time-resolved resonance Raman spectroscopy is used to obtain chromophore vibrational spectra of the pR, pB', and pB intermediates during the photocycle of photoactive yellow protein. In the pR spectrum, the C8-C9 stretching mode at 998 cm(-1) is approximately 60 cm(-1) lower than in the dark state, and the combination of C-O stretching and C7H=C8H bending at 1283 cm(-1) is insensitive to D2O substitution. These results indicate that pR has a deprotonated, cis chromophore structure and that the hydrogen bonding to the chromophore phenolate oxygen is preserved and strengthened in the early photoproduct. However, the intense C7H=C8H hydrogen out-of-plane (HOOP) mode at 979 cm(-1) suggests that the chromophore in pR is distorted at the vinyl and adjacent C8-C9 bonds. The formation of pB' involves chromophore protonation based on the protonation state marker at 1174 cm(-1) and on the sensitivity of the COH bending at 1148 cm(-1) as well as the combined C-OH stretching and C7H=C8H bending mode at 1252 cm(-1) to D2O substitution. The hydrogen out-of-plane Raman intensity at 985 cm(-1) significantly decreases in pB', suggesting that the pR-to-pB' transition is the stage where the stored photon energy is transferred from the distorted chromophore to the protein, producing a more relaxed pB' chromophore structure. The C=O stretching mode downshifts from 1660 to 1651 cm(-1) in the pB'-to-pB transition, indicating the reformation of a hydrogen bond to the carbonyl oxygen. Based on reported x-ray data, this suggests that the chromophore ring flips during the transition from pB' to pB. These results confirm the existence and importance of the pB' intermediate in photoactive yellow protein receptor activation.",1
"Pan, Duohai, Philip, Andrew, Hoff, Wouter D, Mathies, Richard A",2
Dynamic properties of the N-terminal swapped dimer of ribonuclease A.,0
"Bovine pancreatic ribonuclease (RNase A) forms two 3-dimensional domain-swapped dimers with different quaternary structures. One dimer is characterized by the swapping of the C-terminal region (C-Dimer) and presents a rather loose structure. The other dimer (N-Dimer) exhibits a very compact structure with exchange of the N-terminal helix. Here we report the results of a molecular dynamics/essential dynamics (MD/ED) study carried out on the N-Dimer. This investigation, which represents the first MD/ED analysis on a three-dimensional domain-swapped enzyme, provides information on the dynamic properties of the active site residues as well as on the global motions of the dimer subunits. In particular, the analysis of the flexibility of the active site residues agrees well with recent crystallographic and site-directed mutagenesis studies on monomeric RNase A, thus indicating that domain swapping does not affect the dynamics of the active sites. A slight but significant rearrangement of N-Dimer quaternary structure, favored by the formation of additional hydrogen bonds at subunit interface, has been observed during the MD simulation. The analysis of collective movements reveals that each subunit of the dimer retains the functional breathing motion observed for RNase A. Interestingly, the breathing motion of the two subunits is dynamically coupled, as they open and close in phase. These correlated motions indicate the presence of active site intercommunications in this dimer. On these bases, we propose a speculative mechanism that may explain negative cooperativity in systems preserving structural symmetry during the allosteric transitions.",1
"Merlino, Antonello, Vitagliano, Luigi, Ceruso, Marc Antoine, Mazzarella, Lelio",2
Conformational transitions in beta-lactoglobulin induced by cationic amphiphiles: equilibrium studies.,0
"The conformational transition from the native state in water (""beta-state"") to a state containing a considerable amount of alpha-helices (""alpha-state"") was studied for the protein beta-lactoglobulin (BLG), from bovine milk, in several colloidal solutions containing mixed micelles or spontaneous vesicles. These aggregates were formed in the bicationic system containing the surfactant dodecyltrimethylammonium chloride (DTAC) and the lipid didodecyldimethylammonium bromide (DDAB). The beta-->alpha transition in BLG, investigated by far-ultraviolet circular dichroism spectroscopy, is induced to the same protein alpha-state by pure and mixed DDAB/DTAC micelles or vesicles. This implies a similar interaction mechanism of BLG with DDAB or DTAC, once the colloidal aggregates are formed. In premicelle DTAC solutions, the fraction of alpha-helix is lower and increases with the DTAC concentration. DDAB and DTAC also promote conformational changes in the protein tertiary structure that expose the tryptophans to a less constrained environment. These unfolding transitions were investigated by near-ultraviolet circular dichroism and steady-state fluorescence spectroscopies. In equilibrium conditions, it was found that higher DTAC (and, probably, DDAB) concentrations are needed to induce the beta-->alpha transition than to unfold the protein. beta-Lactoglobulin may therefore be considered as a model for protein-surfactant and protein-lipid interactions.",1
"Viseu, Maria Isabel, Carvalho, Teresa Isabel, Costa, Sílvia M B",2
Detection and characterization of partially unfolded oligomers of the SH3 domain of alpha-spectrin.,0
"For the purpose of equilibrium and kinetic folding-unfolding studies, the SH3 domain of alpha-spectrin (spc-SH3) has long been considered a classic two-state folding protein. In this work we have indeed observed that the thermal unfolding curves of spc-SH3 measured at pH 3.0 by differential scanning calorimetry, circular dichroism, and NMR follow apparently the two-state model when each unfolding profile is considered individually. Nevertheless, we have found that protein concentration has a marked effect upon the thermal unfolding profiles. This effect cannot be properly explained in terms of the two-state unfolding model and can only be interpreted in terms of the accumulation of intermediate associated states in equilibrium with the monomeric native and unfolded states. By chemical cross-linking and pulsed-field gradient NMR diffusion experiments we have been able to confirm the existence of associated states formed during spc-SH3 unfolding. A three-state model, in which a dimeric intermediate state is assumed to be significantly populated, provides the simplest interpretation of the whole set of thermal unfolding data and affords a satisfactory explanation for the concentration effects observed. Whereas at low concentrations the population of the associated intermediate state is negligible and the unfolding process consequently takes place in a two-state fashion, at concentrations above approximately 0.5 mM the population of the intermediate state becomes significant at temperatures between 45 degrees C and 80 degrees C and reaches up to 50% at the largest concentration investigated. The thermodynamic properties of the intermediate state implied by this analysis fall in between those of the unfolded state and the native ones, indicating a considerably disordered conformation, which appears to be stabilized by oligomerization.",1
"Casares, Salvador, Sadqi, Mourad, López-Mayorga, Obdulio, Conejero-Lara, Francisco, van Nuland, Nico A J",2
The efficiency of different salts to screen charge interactions in proteins: a Hofmeister effect?,0
"Understanding the screening by salts of charge-charge interactions in proteins is important for at least two reasons: a), screening by intracellular salt concentration may modulate the stability and interactions of proteins in vivo; and b), the in vitro experimental estimation of the contributions from charge-charge interactions to molecular processes involving proteins is generally carried out on the basis of the salt effect on process energetics, under the assumption that these interactions are screened out by moderate salt concentrations. Here, we explore experimentally the extent to which the screening efficiency depends on the nature of the salt. To this end, we have carried out an energetic characterization of the effect of NaCl (a nondenaturing salt), guanidinium chloride (a denaturing salt), and guanidinium thiocyanate (a stronger denaturant) on the stability of the wild-type form and a T14K variant of Escherichia coli thioredoxin. Our results suggest that the efficiency of different salts to screen charge-charge interactions correlates with their denaturing strength and with the position of the constituent ions in the Hofmeister rankings. This result appears consistent with the plausible relation of the Hofmeister rankings with the extent of solute accumulation/exclusion from protein surfaces.",1
"Perez-Jimenez, Raul, Godoy-Ruiz, Raquel, Ibarra-Molero, Beatriz, Sanchez-Ruiz, Jose M",2
Force spectroscopy of the double-tethered concanavalin-A mannose bond.,0
"We present the measurement of the force required to rupture a single protein-sugar bond using a methodology that provides selective discrimination between specific and nonspecific binding events and helps verify the presence of a single functional molecule on the atomic force microscopy tip. In particular, the interaction force between a polymer-tethered concanavalin-A protein (ConA) and a similarly tethered mannose carbohydrate was measured as 47 +/- 9 pN at a bond loading rate of approximately 10 nN/s. Computer simulations of the polymer molecular configurations were used to determine the angles that the polymers could sweep out during binding and, in conjunction with mass spectrometry, used to separate the angular effects from the effects due to a distribution of tether lengths. We find that when using commercially available polymer tethers that vary in length from 19 to 29 nm, the angular effects are relatively small and the rupture distributions are dominated by the 10-nm width of the tether length distribution. In all, we show that tethering both a protein and its ligand allows for the determination of the single-molecule bond rupture force with high sensitivity and includes some validation for the presence of a single-tethered functional molecule on the atomic force microscopy tip.",1
"Ratto, Timothy V, Langry, Kevin C, Rudd, Robert E, Balhorn, Rodney L, Allen, Michael J, McElfresh, Michael W",2
Probing the Q-proton pathway of ba3-cytochrome c oxidase by time-resolved Fourier transform infrared spectroscopy.,0
"In cytochrome c oxidase, the terminal respiratory enzyme, electron transfers are strongly coupled to proton movements within the enzyme. Two proton pathways (K and D) containing water molecules and hydrophobic amino acids have been identified and suggested to be involved in the proton translocation from the mitochondrial matrix or the bacterial cytoplasm into the active site. In addition to the K and D proton pathways, a third proton pathway (Q) has been identified only in ba3-cytochrome c oxidase from Thermus thermophilus, and consists of residues that are highly conserved in all structurally known heme-copper oxidases. The Q pathway starts from the cytoplasmic side of the membrane and leads through the axial heme a3 ligand His-384 to the propionate of the heme a3 pyrrol ring A, and then via Asn-366 and Asp-372 to the water pool. We have applied FTIR and time-resolved step-scan Fourier transform infrared (TRS2-FTIR) spectroscopies to investigate the protonation/deprotonation events in the Q-proton pathway at ambient temperature. The photolysis of CO from heme a3 and its transient binding to CuB is dynamically linked to structural changes that can be tentatively attributed to ring A propionate of heme a3 (1695/1708 cm(-1)) and to deprotonation of Asp-372 (1726 cm(-1)). The implications of these results with respect to the role of the ring A propionate of heme a3-Asp372-H2O site as a proton carrier to the exit/output proton channel (H2O pool) that is conserved among all structurally known heme-copper oxidases, and is part of the Q-proton pathway in ba3-cytochrome c oxidase, are discussed.",1
"Koutsoupakis, Constantinos, Soulimane, Tewfik, Varotsis, Constantinos",2
Experimental and computational studies of the desensitization process in the bovine rhodopsin-arrestin complex.,0
"The deactivation of the bovine G-protein-coupled receptor, rhodopsin, is a two-step process consisting of the phosphorylation of specific serine and threonine residues in the cytoplasmic tail of rhodopsin by rhodopsin kinase. Subsequent binding of the regulatory protein arrestin follows this phosphorylation. Previous results find that at least three phosphorylatable sites on the rhodopsin tail (T340) and at least two of the S338, S334, or S343 sites are needed for complete arrestin-mediated deactivation. Thus, to elucidate the details of the interaction between rhodopsin with arrestin, we have employed both a computational and an in vitro experimental approach. In this work, we first simulated the interaction of the carboxy tail of rhodopsin with arrestin using a Monte Carlo simulated annealing method. Since at this time phosphorylation of specific serines and threonines is not possible in our simulations, we substitute either aspartic or glutamic acid residues for the negatively charged phosphorylated residues required for binding. A total of 17 simulations were performed and analysis of this shows specific charge-charge interactions of the carboxy tail of rhodopsin with arrestin. We then confirmed these computational results with assays of comparable constructed rhodopsin mutations using our in vitro assay. This dual computational/experimental approach indicates that sites S334, S338, and T340 in rhodopsin and K14 and K15 on arrestin are indeed important in the interaction of rhodopsin with arrestin, with a possible weaker S343 (rhodopsin)/K15 (arrestin) interaction.",1
"Ling, Y, Ascano, M, Robinson, P, Gregurick, S K",2
High metal concentrations are required for self-association of synaptotagmin II.,0
"Several members of the synaptotagmin (syt) family of vesicle proteins have been proposed to act as Ca2+ sensors on synaptic vesicles. The mechanism by which calcium activates this class of proteins has been the subject of controversy, yet relatively few detailed biophysical studies have been reported on how isoforms other than syt I respond to divalent metal ions. Here, we report a series of studies on the response of syt II to a wide range of metal ions. Analytical ultracentrifugation studies demonstrate that Ca2+ induces protein dimerization upon exposure to 5 mM Ca2+. Whereas Ba2+, Mg2+, or Sr2+ do not potentiate self-association as strongly as Ca2+, Pb2+ triggers self-association of syt II at concentrations as low as 10 microM. Partial proteolysis studies suggest that the various divalent metals cause different changes in the conformation of the protein. The high calcium concentrations required for self-association of syt II suggest that the oligomerized state of this protein is not a critical intermediate in vesicle fusion; however, low-affinity calcium sites on syt II may play a critical role in buffering calcium at the presynaptic active zone. In addition, the high propensity of lead to oligomerize syt II offers a possible molecular explanation for how lead interferes with calcium-evoked neurotransmitter release.",1
"García, Ricardo A, Godwin, Hilary Arnold",2
Conformation of prion protein repeat peptides probed by FRET measurements and molecular dynamics simulations.,0
"We report the combined use of steady-state fluorescence resonance energy transfer (FRET) experiments and molecular dynamics (MD) simulations to investigate conformational distributions of the prion protein (PrP) repeat system. FRET was used for the first time to probe the distance, as a function of temperature and pH, between a donor Trp residue and an acceptor dansyl group attached to the N-terminus in seven model peptides containing one to three repeats of the second decarepeat of PrP from marsupial possum (PHPGGSNWGQ)nG, and one and two human PrP consensus octarepeats (PHGGGWGQ)nG. In multirepeat peptides, single-Trp mutants were made by replacing other Trp(s) with Phe. As previous work has shown PrP repeats do not adopt a single preferred stable conformation, the FRET values are averages reflecting heterogeneity in the donor-acceptor distances. The T-dependence of the conformational distributions, and derived average dansyl-Trp distances, were obtained directly from MD simulation of the marsupial dansyl-PHPGGSNWGQG peptide. The results show excellent agreement between the FRET and MD T-dependent distances, and demonstrate the remarkable sensitivity and reproducibility of the FRET method in this first-time use for a set of disordered peptides. Based on the results, we propose a model involving cation-pi or pi-pi His-Trp interactions to explain the T- (5-85 degrees C) and pH- (6.0, 7.2) dependencies on distance, with HW i, i + 4 or WH i, i + 4 separations in sequence being more stable than HW i, i + 6 or WH i, i + 6 separations. The model has peptides adopting loosely folded conformations, with dansyl-Trp distances very much less than estimates for fully extended conformations, for example, approximately 16 vs. 33, approximately 21 vs. 69, and approximately 22 vs. 106 A for 1-3 decarepeats, and approximately 14 vs. 25 and approximately 19 vs. 54 A for 1-2 octarepeats, respectively. The study demonstrates the usefulness of combining FRET with MD, a combination reported only once previously. Initial ""mapping"" of the conformational distribution of flexible peptides by simulation can assist in designing and interpreting experiments using steady-state intensity methods, and indicating how time-resolved or anisotropy methods might be used.",1
"Gustiananda, Marsia, Liggins, John R, Cummins, Peter L, Gready, Jill E",2
Self-association process of a peptide in solution: from beta-sheet filaments to large embedded nanotubes.,0
"Lanreotide is a synthetic octapeptide used in the therapy against acromegaly. When mixed with pure water at 10% (w/w), Lanreotide (acetate salt) forms liquid crystalline and monodisperse nanotubes with a radius of 120 A. The molecular and supramolecular organization of these structures has been determined in a previous work as relying on the lateral association of 26 beta-sheet filaments made of peptide noncovalent dimers, the basic building blocks. The work presented here has been devoted to the corresponding self-association mechanisms, through the characterization of the Lanreotide structures formed in water, as a function of peptide (acetate salt) concentration (from 2% to 70% (w/w)) and temperature (from 15 degrees C to 70 degrees C). The corresponding states of water were also identified and quantified from the thermal behavior of water in the Lanreotide mixtures. At room temperature and below 3% (w/w) Lanreotide acetate in water, soluble aggregates were detected. From 3% to 20% (w/w) long individual and monodisperse nanotubes crystallized in a hexagonal lattice were evidenced. Their molecular and supramolecular organizations are identical to the ones characterized for the 10% (w/w) sample. Heating induces the dissolution of the nanotubes into soluble aggregates of the same structural characteristics as the room temperature ones. The solubilization temperature increases from 20 degrees C to 70 degrees C with the peptide concentration and reaches a plateau between 15% and 25% (w/w) in peptide. These aggregates are proposed to be the beta-sheet filaments that self-associate to build the walls of the nanotubes. Above 20% (w/w) of Lanreotide acetate in water, polydisperse embedded nanotubes are formed and the hexagonal lattice is lost. These embedded nanotubes exhibit the same molecular and supramolecular organizations as the individual monodisperse nanotubes formed at lower peptide concentration. The embedded nanotubes do not melt in the range of temperature studied indicating a higher thermodynamic stability than individual nanotubes. In parallel, the thermal behaviors of water in mixtures containing 2-80% (w/w) in peptide have been studied by differential scanning calorimetry, and three different types of water were characterized: 1), bulk water melting at 0 degrees C, 2), nonfreezing water, and 3), interfacial water melting below 0 degrees C. The domains of existence and coexistence of these different water states are related to the different Lanreotide supramolecular structures. All these results were compiled into a binary Lanreotide-water phase diagram and allowed to propose a self-association mechanism of Lanreotide filaments into monodisperse individual nanotubes and embedded nanotubes.",1
"Valéry, C, Artzner, F, Robert, B, Gulick, T, Keller, G, Grabielle-Madelmont, C, Torres, M-L, Cherif-Cheikh, R, Paternostre, M",2
Modeling sample disorder in site-specific dichroism studies of uniaxial systems.,0
"Site-specific infrared dichroism is an emerging method capable of proposing a model for the backbone structure of a transmembrane alpha-helix within a helical bundle. Dichroism measurements of single, isotopically enhanced vibrational modes (e.g., Amide I 13C=18O or Gly CD2 stretching modes) can yield precise orientational restraints for the monomer helix protomer that can be used as refinement constraints in model building of the entire helical bundle. Essential, however, for the interpretation of the dichroism measurements, is an accurate modeling of the sample disorder. In this study we derive an enhanced and more realistic modeling of the sample disorder based on a Gaussian distribution of the chromophore around a particular angle. The enhanced utility of the Gaussian model is exemplified by the comparative data analysis based on the aforementioned model to previously employed models.",1
"Kass, Itamar, Arbely, Eyal, Arkin, Isaiah T",2
Graphical analysis of mass and anisotropy changes observed by plasmon-waveguide resonance spectroscopy can provide useful insights into membrane protein function.,0
"Plasmon-waveguide resonance spectroscopy is a recently developed optical method that allows characterization of mass and structural changes in two-dimensionally ordered thin films (e.g., proteolipid membranes) deposited onto a sensor surface. Full analysis of these systems involves fitting theoretical curves (obtained using Maxwell's equations) to experimental spectra measured using s- and p-polarized excitation. This allows values to be obtained for refractive indices and optical extinction coefficients in these two directions, as well as a value for film thickness, thereby providing information about mass density and anisotropy changes. This is a time-consuming process that works well for simple systems in which only a single conformational event occurs, but cannot distinguish between events involving multiple conformations that proceed either sequentially or in a parallel series of events. This article describes a graphical method that can distinguish between mass density and anisotropy changes in a simpler, more rapid procedure, even for processes that proceed via multiple conformational events. This involves measurement of plasmon-waveguide resonance spectral shifts obtained upon molecular interactions occurring in deposited films with both s- and p-polarized excitation, and transforming these from an (s-p) coordinate system into a (mass-structure) coordinate system. This procedure is illustrated by data obtained upon the binding of a small peptide, penetratin, to solid-supported lipid bilayer membranes.",1
"Salamon, Zdzislaw, Tollin, Gordon",2
Correcting confocal acquisition to optimize imaging of fluorescence resonance energy transfer by sensitized emission.,0
"Imaging of fluorescence resonance energy transfer (FRET) between suitable fluorophores is increasingly being used to study cellular processes with high spatiotemporal resolution. The genetically encoded Cyan (CFP) and Yellow (YFP) variants of Green Fluorescent Protein have become the most popular donor and acceptor pair in cell biology. FRET between these fluorophores can be imaged by detecting sensitized emission. This technique, for which CFP is excited and transfer is detected as emission of YFP, is sensitive, fast, and straightforward, provided that proper corrections are made. In this study, the detection of sensitized emission between CFP and YFP by confocal microscopy is optimized. It is shown that this FRET pair is best excited at 430 nm. We identify major sources of error and variability in confocal FRET acquisition including chromatic aberrations and instability of the excitation sources. We demonstrate that a novel correction algorithm that employs online corrective measurements yields reliable estimates of FRET efficiency, and it is also shown how the effect of other error sources can be minimized.",1
"van Rheenen, Jacco, Langeslag, Michiel, Jalink, Kees",2
Probing single-stranded DNA conformational flexibility using fluorescence spectroscopy.,0
"Single-stranded DNA (ssDNA) is an essential intermediate in various DNA metabolic processes and interacts with a large number of proteins. Due to its flexibility, the conformations of ssDNA in solution can only be described using statistical approaches, such as flexibly jointed or worm-like chain models. However, there is limited data available to assess such models quantitatively, especially for describing the flexibility of short ssDNA and RNA. To address this issue, we performed FRET studies of a series of oligodeoxythymidylates, (dT)N, over a wide range of salt concentrations and chain lengths (10 < or = N < or = 70 nucleotides), which provide systematic constraints for testing theoretical models. Unlike in mechanical studies where available ssDNA conformations are averaged out during the time it takes to perform measurements, fluorescence lifetimes may act here as an internal clock that influences fluorescence signals depending on how fast the ssDNA conformations fluctuate. A reasonably good agreement could be obtained between our data and the worm-like chain model provided that limited relaxations of the ssDNA conformations occur within the fluorescence lifetime of the donor. The persistence length thus estimated ranges from 1.5 nm in 2 M NaCl to 3 nm in 25 mM NaCl.",1
"Murphy, M C, Rasnik, Ivan, Cheng, Wei, Lohman, Timothy M, Ha, Taekjip",2
Photoisomerization and photoionization of the photoactive yellow protein chromophore in solution.,0
"Dispersed pump-dump-probe spectroscopy has the ability to characterize and identify the underlying ultrafast dynamical processes in complicated chemical and biological systems. This technique builds on traditional pump-probe techniques by exploring both ground- and excited-state dynamics and characterizing the connectivity between constituent transient states. We have used the dispersed pump-dump-probe technique to investigate the ground-state dynamics and competing excited-state processes in the excitation-induced ultrafast dynamics of thiomethyl p-coumaric acid, a model chromophore for the photoreceptor photoactive yellow protein. Our results demonstrate the parallel formation of two relaxation pathways (with multiple transient states) that jointly lead to two different types of photochemistry: cis-trans isomerization and detachment of a hydrated electron. The relative transition rates and quantum yields of both pathways have been determined. We find that the relaxation of the photoexcited chromophores involves multiple, transient ground-state intermediates and the chromophore in solution does not generate persistent photoisomerized products, but instead undergoes photoionization resulting in the generation of detached electrons and radicals. These results are of great value in interpreting the more complex dynamical changes in the optical properties of the photoactive yellow protein.",1
"Larsen, Delmar S, Vengris, Mikas, van Stokkum, Ivo H M, van der Horst, Michael A, de Weerd, Frank L, Hellingwerf, Klaas J, van Grondelle, Rienk",2
Interresidual distance determination by four-pulse double electron-electron resonance in an integral membrane protein: the Na+/proline transporter PutP of Escherichia coli.,0
Proximity relationships within three doubly spin-labeled variants of the Na+/proline transporter PutP of Escherichia coli were studied by means of four-pulse double electron-electron resonance spectroscopy. The large value of 4.8 nm for the interspin distance determined between positions 107 in loop 4 and 223 in loop 7 strongly supports the idea of these positions being located on opposite sides of the membrane. Significant smaller values of between 1.8 and 2.5 nm were found for the average interspin distances between spin labels attached to the cytoplasmic loops 2 and 4 (position 37 and 107) and loops 2 and 6 (position 37 and 187). The large distance distribution widths visible in the pair correlation functions reveal a high flexibility of the studied loop regions. An increase of the distance between positions 37 and 187 upon Na+ binding suggests ligand-induced structural alterations of PutP. The results demonstrate that four-pulse double electron-electron resonance spectroscopy is a powerful means to investigate the structure and conformational changes of integral membrane proteins reconstituted in proteoliposomes.,1
"Jeschke, Gunnar, Wegener, Christoph, Nietschke, Monika, Jung, Heinrich, Steinhoff, Heinz-Jürgen",2
Rho mediates the shear-enhancement of endothelial cell migration and traction force generation.,0
"The migration of vascular endothelial cells in vivo occurs in a fluid dynamic environment due to blood flow, but the role of hemodynamic forces in cell migration is not yet completely understood. Here we investigated the effect of shear stress, the frictional drag of blood flowing over the cell surface, on the migration speed of individual endothelial cells on fibronectin-coated surfaces, as well as the biochemical and biophysical bases underlying this shear effect. Under static conditions, cell migration speed had a bell-shaped relationship with fibronectin concentration. Shear stress significantly increased the migration speed at all fibronectin concentrations tested and shifted the bell-shaped curve upwards. Shear stress also induced the activation of Rho GTPase and increased the traction force exerted by endothelial cells on the underlying substrate, both at the leading edge and the rear, suggesting that shear stress enhances both the frontal forward-pulling force and tail retraction. The inhibition of a Rho-associated kinase, p160ROCK, decreased the traction force and migration speed under both static and shear conditions and eliminated the shear-enhancement of migration speed. Our results indicate that shear stress enhances the migration speed of endothelial cells by modulating the biophysical force of tractions through the biochemical pathway of Rho-p160ROCK.",1
"Shiu, Yan-Ting, Li, Song, Marganski, William A, Usami, Shunichi, Schwartz, Martin A, Wang, Yu-Li, Dembo, Micah, Chien, Shu",2
Longitudinal diffusion in retinal rod and cone outer segment cytoplasm: the consequence of cell structure.,0
"Excitation signals spread along photoreceptor outer segments away from the site of photon capture because of longitudinal diffusion of cGMP, a cytoplasmic second messenger. The quantitative features of longitudinal diffusion reflect the anatomical structure of the outer segment, known to be profoundly different in rod and cone photoreceptors. To explore how structural differences affect cytoplasmic diffusion and to assess whether longitudinal diffusion may contribute to the difference in signal transduction between photoreceptor types, we investigated, both theoretically and experimentally, the longitudinal diffusion of small, hydrophilic molecules in outer segments. We developed a new theoretical analysis to explicitly compute the longitudinal diffusion constant, Dl, in terms of outer segment structure. Using time-resolved fluorescence imaging we measured Dl of Alexa488 and lucifer yellow in intact, single cones and validated the theoretical analysis. We used numerical simulations of the theoretical model to investigate cGMP diffusion in outer segments of various species. At a given time interval, cGMP spreads further in rod than in cone outer segments of the same dimensions. Across all species, the spatial spread of cGMP at the peak of the dim light photocurrent is 3-5 microm in rod outer segments, regardless of their absolute size. Similarly the cGMP spatial spread is 0.7-1 microm in cone outer segments, independently of their dimensions.",1
"Holcman, David, Korenbrot, Juan I",2
Role of sarcoplasmic reticulum and mitochondria in Ca2+ removal in airway myocytes.,0
"The aim of this study was to use both a theoretical and experimental approach to determine the influence of the sarco-endoplasmic Ca2+-ATPase (SERCA) activity and mitochondria Ca2+ uptake on Ca2+ homeostasis in airway myocytes. Experimental studies were performed on myocytes freshly isolated from rat trachea. [Ca2+]i was measured by microspectrofluorimetry using indo-1. Stimulation by caffeine for 30 s induced a concentration-graded response characterized by a transient peak followed by a progressive decay to a plateau phase. The decay phase was accelerated for 1-s stimulation, indicating ryanodine receptor closure. In Na2+-Ca2+-free medium containing 0.5 mM La3+, the [Ca2+]i response pattern was not modified, indicating no involvement of transplasmalemmal Ca2+ fluxes. The mathematical model describing the mechanism of Ca2+ handling upon RyR stimulation predicts that after Ca2+ release from the sarcoplasmic reticulum, the Ca2+ is first sequestrated by cytosolic proteins and mitochondria, and pumped back into the sarcoplasmic reticulum after a time delay. Experimentally, we showed that the [Ca2+]i decay after Ca2+ increase was not altered by the SERCA inhibitor cyclopiazonic acid, but was slightly but significantly modified by the mitochondria uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone. The experimental and theoretical results indicate that, although Ca2+ pumping back by SERCA is active, it is not primarily involved in [Ca2+]i decrease that is due, in part, to mitochondrial Ca2+ uptake.",1
"Roux, Etienne, Marhl, Marko",2
Diastolic calcium release controls the beating rate of rabbit sinoatrial node cells: numerical modeling of the coupling process.,0
"Recent studies employing Ca2+ indicators and confocal microscopy demonstrate substantial local Ca2+ release beneath the cell plasma membrane (subspace) of sinoatrial node cells (SANCs) occurring during diastolic depolarization. Pharmacological and biophysical experiments have suggested that the released Ca2+ interacts with the plasma membrane via the ion current (INaCa) produced by the Na+/Ca2+ exchanger and constitutes an important determinant of the pacemaker rate. This study provides a numerical validation of the functional importance of diastolic Ca2+ release for rate control. The subspace Ca2+ signals in rabbit SANCs were measured by laser confocal microscopy, averaged, and calibrated. The time course of the subspace [Ca2+] displayed both diastolic and systolic components. The diastolic component was mainly due to the local Ca2+ releases; it was numerically approximated and incorporated into a SANC cellular electrophysiology model. The model predicts that the diastolic Ca2+ release strongly interacts with plasma membrane via INaCa and thus controls the phase of the action potential upstroke and ultimately the final action potential rate.",1
"Maltsev, Victor A, Vinogradova, Tatiana M, Bogdanov, Konstantin Y, Lakatta, Edward G, Stern, Michael D",2
Theoretical investigation of the neuronal Na+ channel SCN1A: abnormal gating and epilepsy.,0
"Epilepsy is a paroxysmal neurological disorder resulting from abnormal cellular excitability and is a common cause of disability. Recently, some forms of idiopathic epilepsy have been causally related to genetic mutations in neuronal ion channels. To understand disease mechanisms, it is crucial to understand how a gene defect can disrupt channel gating, which in turn can affect complex cellular dynamic processes. We develop a theoretical Markovian model of the neuronal Na+ channel NaV1.1 to explore and explain gating mechanisms underlying cellular excitability and physiological and pathophysiological mechanisms of abnormal neuronal excitability in the context of epilepsy. Genetic epilepsy has been shown to result from both mutations that give rise to a gain of channel function and from those that reduce the Na+ current. These data may suggest that abnormal excitation can result from both hyperexcitability and hypoexcitability, the mechanisms of which are presumably distinct, and as yet elusive. Revelation of the molecular origins will allow for translation into targeted pharmacological interventions that must be developed to treat syndromes resulting from divergent mechanisms. This work represents a first step in developing a comprehensive theoretical model to investigate the molecular mechanisms underlying runaway excitation that cause epilepsy.",1
"Clancy, Colleen E, Kass, Robert S",2
"Spontaneously formed monodisperse biomimetic unilamellar vesicles: the effect of charge, dilution, and time.",0
"Using small-angle neutron scattering and dynamic light scattering, we have constructed partial structural phase diagrams of lipid mixtures composed of the phosphatidylcholines dimyristoyl and dihexanoyl doped with calcium ions (Ca2+) and/or the negatively charged lipid, dimyristoyl phosphatidylglycerol (DMPG). For dilute solutions (lipid concentration < or =1 wt %), spontaneously forming unilamellar vesicles (ULVs) were found, and their polydispersity was determined to be approximately 20%. The stability of the Ca2+- or DMPG-doped ULVs was monitored over a period of 4 days and their structural parameters (e.g., average outer radius, <Ro>) were found to be insensitive to the lipid concentration (Clp). However, doping the dimyristoyl/dihexanoyl system with both Ca2+ and DMPG resulted in ULVs whose <Ro> was found to be Clp dependent. The <Ro> of DMPG-doped ULVs remained unchanged over an extended period of time (at least 4 days), a good indication of their stability.",1
"Nieh, M-P, Harroun, T A, Raghunathan, V A, Glinka, C J, Katsaras, J",2
Pulling-speed-dependent force-extension profiles for semiflexible chains.,0
"We present theory and simulations to describe nonequilibrium stretching of semiflexible chains that serve as models of DNA molecules. Using a self-consistent dynamical variational approach, we calculate the force-extension curves for worm-like chains as a function of the pulling speed, v(0). Due to nonequilibrium effects the stretching force, which increases with v(0), shows nonmonotonic variations as the persistence length increases. To complement the theoretical calculations we also present Langevin simulation results for extensible worm-like chain models for the dynamics of stretching. The theoretical force-extension predictions compare well with the simulation results. The simulations show that, at high enough pulling speeds, the propagation of tension along the chain conformations transverse to the applied force occurs by the Brochard-Wyart's stem-flower mechanism. The predicted nonequilibrium effects can only be observed in double-stranded DNA at large ( approximately 100 microm/s) pulling speeds.",1
"Lee, Nam-Kyung, Thirumalai, D",2
Dynamic receptor team formation can explain the high signal transduction gain in Escherichia coli.,0
"Evolution has provided many organisms with sophisticated sensory systems that enable them to respond to signals in their environment. The response frequently involves alteration in the pattern of movement, either by directed movement, a process called taxis, or by altering the speed or frequency of turning, which is called kinesis. Chemokinesis has been most thoroughly studied in the peritrichous bacterium Escherichia coli, which has four helical flagella distributed over the cell surface, and swims by rotating them. When rotated counterclockwise the flagella coalesce into a propulsive bundle, producing a relatively straight ""run,"" and when rotated clockwise they fly apart, resulting in a ""tumble"" which reorients the cell with little translocation. A stochastic process generates the runs and tumbles, and in a chemoeffector gradient, runs that carry the cell in a favorable direction are extended. The cell senses spatial gradients as temporal changes in receptor occupancy and changes the probability of counterclockwise rotation (the bias) on a fast timescale, but adaptation returns the bias to baseline on a slow timescale, enabling the cell to detect and respond to further concentration changes. The overall structure of the signal transduction pathways is well characterized in E. coli, but important details are still not understood. Only recently has a source of gain in the signal transduction network been identified experimentally, and here we present a mathematical model based on dynamic assembly of receptor teams that can explain this observation.",1
"Albert, Réka, Chiu, Yu-Wen, Othmer, Hans G",2
Release currents of IP(3) receptor channel clusters and concentration profiles.,0
We simulate currents and concentration profiles generated by Ca(2+) release from the endoplasmic reticulum (ER) to the cytosol through IP(3) receptor channel clusters. Clusters are described as conducting pores in the lumenal membrane with a diameter from 6 nm to 36 nm. The endoplasmic reticulum is modeled as a disc with a radius of 1-12 microm and an inner height of 28 nm. We adapt the dependence of the currents on the trans Ca(2+) concentration (intralumenal) measured in lipid bilayer experiments to the cellular geometry. Simulated currents are compared with signal mass measurements in Xenopus oocytes. We find that release currents depend linearly on the concentration of free Ca(2+) in the lumen. The release current is approximately proportional to the square root of the number of open channels in a cluster. Cytosolic concentrations at the location of the cluster range from 25 microM to 170 microM. Concentration increase due to puffs in a distance of a few micrometers from the puff site is found to be in the nanomolar range. Release currents decay biexponentially with timescales of <1 s and a few seconds. Concentration profiles decay with timescales of 0.125-0.250 s upon termination of release.,1
"Thul, R, Falcke, M",2
The facilitated probability of quantal secretion within an array of calcium channels of an active zone at the amphibian neuromuscular junction.,0
"A Monte Carlo analysis has been made of the phenomenon of facilitation, whereby a conditioning impulse leaves nerve terminals in a state of heightened release of quanta by a subsequent test impulse, this state persisting for periods of hundreds of milliseconds. It is shown that a quantitative account of facilitation at the amphibian neuromuscular junction can be given if the exocytosis is triggered by the combined action of a low-affinity calcium-binding molecule at the site of exocytosis and a high-affinity calcium-binding molecule some distance away. The kinetic properties and spatial distribution of these molecules at the amphibian neuromuscular junction are arrived at by considering the appropriate values that the relevant parameters must take to successfully account for the experimentally observed amplitude and time course of decline of F1 and F2 facilitation after a conditioning impulse, as well as the growth of facilitation during short trains of impulses. This model of facilitation correctly predicts the effects on facilitation of exogenous buffers such as BAPTA during short trains of impulses. In addition, it accounts for the relative invariance of the kinetics of quantal release due to test-conditioning sequences of impulses as well as due to change in the extent of calcium influx during an impulse.",1
"Bennett, M R, Farnell, L, Gibson, W G",2
Facilitation through buffer saturation: constraints on endogenous buffering properties.,0
"Synaptic facilitation (SF) is a ubiquitous form of short-term plasticity, regulating synaptic dynamics on fast timescales. Although SF is known to depend on the presynaptic accumulation of Ca(2+), its precise mechanism is still under debate. Recently it has been shown that at certain central synapses SF results at least in part from the progressive saturation of an endogenous Ca(2+) buffer (Blatow et al., 2003), as proposed by Klingauf and Neher (1997). Using computer simulations, we study the magnitude of SF that can be achieved by a buffer saturation mechanism (BSM), and explore its dependence on the endogenous buffering properties. We find that a high SF magnitude can be obtained either by a global saturation of a highly mobile buffer in the entire presynaptic terminal, or a local saturation of a completely immobilized buffer. A characteristic feature of BSM in both cases is that SF magnitude depends nonmonotonically on the buffer concentration. In agreement with results of Blatow et al. (2003), we find that SF grows with increasing distance from the Ca(2+) channel cluster, and increases with increasing external Ca(2+), [Ca(2+)](ext), for small levels of [Ca(2+)](ext). We compare our modeling results with the experimental properties of SF at the crayfish neuromuscular junction, and find that the saturation of an endogenous mobile buffer can explain the observed SF magnitude and its supralinear accumulation time course. However, we show that the BSM predicts slowing of the SF decay rate in the presence of exogenous Ca(2+) buffers, contrary to experimental observations at the crayfish neuromuscular junction. Further modeling and data are required to resolve this aspect of the BSM.",1
"Matveev, Victor, Zucker, Robert S, Sherman, Arthur",2
A mechanistic model of the actin cycle.,0
"We have derived a broad, deterministic model of the steady-state actin cycle that includes its major regulatory mechanisms. Ours is the first model to solve the complete nucleotide profile within filaments, a feature that determines the dynamics and geometry of actin networks at the leading edges of motile cells, and one that has challenged investigators developing models to interpret steady-state experiments. We arrived at the nucleotide profile through analytic and numerical approaches that completely agree. Our model reproduces behaviors seen in numerous experiments with purified proteins, but allows a detailed inspection of the concentrations and fluxes that might exist in these experiments. These inspections provide new insight into the mechanisms that determine the rate of actin filament treadmilling. Specifically, we find that mechanisms for enhancing Pi release from the ADP.Pi intermediate on filaments, for increasing the off rate of ADP-bound subunits at pointed ends, and the multiple, simultaneous functions of profilin, make unique and essential contributions to increased treadmilling. In combination, these mechanisms have a theoretical capacity to increase treadmilling to levels limited only by the amount of available actin. This limitation arises because as the cycle becomes more dynamic, it tends toward the unpolymerized state.",1
"Bindschadler, M, Osborn, E A, Dewey, C F, McGrath, J L",2
Elastic instability in growing yeast colonies.,0
The differential adhesion between cells is believed to be the major driving force behind the formation of tissues. The idea is that an aggregate of cells minimizes the overall adhesive energy between cell surfaces. We demonstrate in a model experimental system that there exist conditions where a slowly growing tissue does not minimize this adhesive energy. A mathematical model demonstrates that the instability of a spherical shape is caused by the competition between elastic and surface energies.,1
"Nguyen, Baochi, Upadhyaya, Arpita, van Oudenaarden, Alexander, Brenner, Michael P",2
The sonic hedgehog signaling system as a bistable genetic switch.,0
"Sonic hedgehog (Shh) controls critical cellular decisions between distinct fates in many systems, particularly in stem cells. The Shh network functions as a genetic switch, and we have theoretically and computationally analyzed how its structure can endow it with the ability to switch fate choices at a threshold Shh concentration. The network is composed of a positive transcriptional feedback loop embedded within a negative signaling feedback loop. Specifically, positive feedback by the transcription factor Gli, which upregulates its own expression, leads to a switch that can adopt two distinct states as a function of Shh. However, Gli also upregulates the signaling repressor Patched, negative feedback that reins in the strong Gli autoregulatory loop. Mutations that have been associated with cancer are predicted to yield an irreversible switch to a high Gli state. Finally, stochastic simulation reveals the negative Patched feedback loop serves a critical function of dampening Gli fluctuations to reduce spontaneous state switching and preserve the network's robust, switch-like behavior. Tightly linked positive and negative feedback loops are present in many signaling systems, and the Shh system is therefore likely representative of a large set of gene regulation networks that control stem cell fate throughout development and into adulthood.",1
"Lai, Karen, Robertson, Matthew J, Schaffer, David V",2
Stability and the evolvability of function in a model protein.,0
"Functional proteins must fold with some minimal stability to a structure that can perform a biochemical task. Here we use a simple model to investigate the relationship between the stability requirement and the capacity of a protein to evolve the function of binding to a ligand. Although our model contains no built-in tradeoff between stability and function, proteins evolved function more efficiently when the stability requirement was relaxed. Proteins with both high stability and high function evolved more efficiently when the stability requirement was gradually increased than when there was constant selection for high stability. These results show that in our model, the evolution of function is enhanced by allowing proteins to explore sequences corresponding to marginally stable structures, and that it is easier to improve stability while maintaining high function than to improve function while maintaining high stability. Our model also demonstrates that even in the absence of a fundamental biophysical tradeoff between stability and function, the speed with which function can evolve is limited by the stability requirement imposed on the protein.",1
"Bloom, Jesse D, Wilke, Claus O, Arnold, Frances H, Adami, Christoph",2
Atomic mean-square displacements in proteins by molecular dynamics: a case for analysis of variance.,0
"Information on protein internal motions is usually obtained through the analysis of atomic mean-square displacements, which are a measure of variability of the atomic positions distribution functions. We report a statistical approach to analyze molecular dynamics data on these displacements that is based on probability distribution functions. Using a technique inspired by the analysis of variance, we compute unbiased, reliable mean-square displacements of the atoms and analyze them statistically. We applied this procedure to characterize protein thermostability by comparing the results for a thermophilic enzyme and a mesophilic homolog. In agreement with previous experimental observations, our analysis suggests that the proteins surface regions can play a role in the different thermal behavior.",1
"Maragliano, Luca, Cottone, Grazia, Cordone, Lorenzo, Ciccotti, Giovanni",2
Modeling electron transfer thermodynamics in protein complexes: interaction between two cytochromes c(3).,0
"Redox protein complexes between type I and type II tetraheme cytochromes c(3) from Desulfovibrio vulgaris Hildenborough are here analyzed using theoretical methodologies. Various complexes were generated using rigid-body docking techniques, and the two lowest energy complexes (1 and 2) were relaxed using molecular dynamics simulations with explicit solvent and subjected to further characterization. Complex 1 corresponds to an interaction between hemes I from both cytochromes c(3). Complex 2 corresponds to an interaction between the heme IV from type I and the heme I from type II cytochrome c(3). Binding free energy calculations using molecular mechanics, Poisson-Boltzmann, and surface accessibility methods show that complex 2 is more stable than complex 1. Thermodynamic calculations on complex 2 show that complex formation induces changes in the reduction potential of both cytochromes c(3), but the changes are larger in the type I cytochrome c(3) (the largest one occurring on heme IV, of approximately 80 mV). These changes are sufficient to invert the global titration curves of both cytochromes, generating directionally in electron transfer from type I to type II cytochrome c(3), a phenomenon of obvious thermodynamic origin and consequences, but also with kinetic implications. The existence of processes like this occurring at complex formation may constitute a natural design of efficient redox chains.",1
"Teixeira, Vitor H, Baptista, António M, Soares, Cláudio M",2
Radial arrangement of chromosome territories in human cell nuclei: a computer model approach based on gene density indicates a probabilistic global positioning code.,0
"Numerous investigations in the last years focused on chromosome arrangements in interphase nuclei. Recent experiments concerning the radial positioning of chromosomes in the nuclear volume of human and primate lymphocyte cells suggest a relationship between the gene density of a chromosome territory (CT) and its distance to the nuclear center. To relate chromosome positioning and gene density in a quantitative way, computer simulations of whole human cell nuclear genomes of normal karyotype were performed on the basis of the spherical 1 Mbp chromatin domain model and the latest data about sequence length and gene density of chromosomes. Three different basic assumptions about the initial distribution of chromosomes were used: a statistical, a deterministic, and a probabilistic initial distribution. After a simulated decondensation in early G1, a comparison of the radial distributions of simulated and experimentally obtained data for CTs Nos. 12, 18, 19, and 20 was made. It was shown that the experimentally observed distributions can be fitted better assuming an initial probabilistic distribution. This supports the concept of a probabilistic global gene positioning code depending on CT sequence length and gene density.",1
"Kreth, G, Finsterle, J, von Hase, J, Cremer, M, Cremer, C",2
Model of creation and evolution of stable electropores for DNA delivery.,0
"Electroporation, in which electric pulses create transient pores in the cell membrane, is becoming an important technique for gene therapy. To enable entry of supercoiled DNA into cells, the pores should have sufficiently large radii (>10 nm), remain open long enough for the DNA chain to enter the cell (milliseconds), and should not cause membrane rupture. This study presents a model that can predict such macropores. The distinctive features of this model are the coupling of individual pores through membrane tension and the electrical force on the pores, which is applicable to pores of any size. The model is used to explore the process of pore creation and evolution and to determine the number and size of pores as a function of the pulse magnitude and duration. Next, our electroporation model is combined with a heuristic model of DNA uptake and used to predict the dependence of DNA uptake on pulsing parameters. Finally, the model is used to examine the mechanism of a two-pulse protocol, which was proposed specifically for gene delivery. The comparison between experimental results and the model suggests that this model is well-suited for the investigation of electroporation-mediated DNA delivery.",1
"Smith, Kyle C, Neu, John C, Krassowska, Wanda",2
Structural restraints and heterogeneous orientation of the gramicidin A channel closed state in lipid bilayers.,0
"Although there have been several decades of literature illustrating the opening and closing of the monovalent cation selective gramicidin A channel through single channel conductance, the closed conformation has remained poorly characterized. In sharp contrast, the open-state dimer is one of the highest resolution structures yet characterized in a lipid environment. To shift the open/closed equilibrium dramatically toward the closed state, a lower peptide/lipid molar ratio and, most importantly, long-chain lipids have been used. For the first time, structural evidence for a monomeric state has been observed for the native gramicidin A peptide. Solid-state NMR spectroscopy of single-site (15)N-labeled gramicidin in uniformly aligned bilayers in the L(alpha) phase have been observed. The results suggest a kinked structure with considerable orientational heterogeneity. The C-terminal domain is well structured, has a well-defined orientation in the bilayer, and appears to be in the bilayer interfacial region. On the other hand, the N-terminal domain, although appearing to be well structured and in the hydrophobic core of the bilayer, has a broad range of orientations relative to the bilayer normal. The structure is not just half of the open-state dimer, and neither is the structure restricted to the surface of the bilayer. Consequently, the monomeric or closed state appears to be a hybrid of these two models from the literature.",1
"Mo, Y, Cross, T A, Nerdal, W",2
Cysteine scanning of MscL transmembrane domains reveals residues critical for mechanosensitive channel gating.,0
"The mechanosensitive channel of large conductance (MscL), a bacterial channel, is perhaps the best characterized mechanosensitive protein. A structure of the Mycobacterium tuberculosis ortholog has been solved by x-ray crystallography, but details of how the channel gates remain obscure. Here, cysteine scanning was used to identify residues within the transmembrane domains of Escherichia coli MscL that are crucial for normal function. Utilizing genetic screens, we identified several mutations that induced gain-of-function or loss-of-function phenotypes in vivo. Mutants that exhibited the most severe phenotypes were further characterized using electrophysiological techniques and chemical modifications of the substituted cysteines. Our results verify the importance of residues in the putative primary gate in the first transmembrane domain, corroborate other residues previously noted as critical for normal function, and identify new ones. In addition, evaluation of disulfide bridging in native membranes suggests alterations of existing structural models for the ""fully closed"" state of the channel.",1
"Levin, Gal, Blount, Paul",2
Functional effects of auxiliary beta4-subunit on rat large-conductance Ca(2+)-activated K(+) channel.,0
"Large-conductance calcium-activated potassium (BK(Ca)) channels are composed of the pore-forming alpha-subunit and the auxiliary beta-subunits. The beta4-subunit is dominantly expressed in the mammalian central nervous system. To understand the physiological roles of the beta4-subunit on the BK(Ca) channel alpha-subunit (Slo), we isolated a full-length complementary DNA of rat beta4-subunit (rbeta4), expressed heterolgously in Xenopus oocytes, and investigated the detailed functional effects using electrophysiological means. When expressed together with rat Slo (rSlo), rbeta4 profoundly altered the gating characteristics of the Slo channel. At a given concentration of intracellular Ca(2+), rSlo/rbeta4 channels were more sensitive to transmembrane voltage changes. The activation and deactivation rates of macroscopic currents were decreased in a Ca(2+)-dependent manner. The channel activation by Ca(2+) became more cooperative by the coexpression of rbeta4. Single-channel recordings showed that the increased Hill coefficient for Ca(2+) was due to the changes in the open probability of the rSlo/rbeta4 channel. Single BK(Ca) channels composed of rSlo and rbeta4 also exhibited slower kinetics for steady-state gating compared with rSlo channels. Dwell times of both open and closed events were significantly increased. Because BK(Ca) channels are known to modulate neuroexcitability and the expression of the beta4-subunit is highly concentrated in certain subregions of brain, the electrophysiological properties of individual neurons should be affected profoundly by the expression of this second subunit.",1
"Ha, Tal Soo, Heo, Moon-Sun, Park, Chul-Seung",2
Water dynamics and dewetting transitions in the small mechanosensitive channel MscS.,0
"The dynamics of confined water in capillaries and nanotubes suggests that gating of ion channels may involve not only changes of the pore geometry, but also transitions between water-filled and empty states in certain locations. The recently solved heptameric structure of the small mechanosensitive channel of Escherichia coli, MscS, has revealed a relatively wide (7-15 A) yet highly hydrophobic transmembrane pore. Continuum estimations based on the properties of pore surface suggest low conductance and a thermodynamic possibility of dewetting. To test the predictions we performed molecular dynamics simulations of MscS filled with flexible TIP3P water. Irrespective to the initial conditions, several independent 6-ns simulations converged to the same stable state with the pore water-filled in the wider part, but predominantly empty in the narrow hydrophobic part, displaying intermittent vapor-liquid transitions. The polar gain-of-function substitution L109S in the constriction resulted in a stable hydration of the entire pore. Steered passages of Cl(-) ions through the narrow part of the pore consistently produced partial ion dehydration and required a force of 200-400 pN to overcome an estimated barrier of 10-20 kcal/mole, implying negligibly low conductance. We conclude that the crystal structure of MscS does not represent an open state. We infer that MscS gate, which is similar to that of the nicotinic ACh receptor, involves a vapor-lock mechanism where limited changes of geometry or surface polarity can locally switch the regime between water-filled (conducting) and empty (nonconducting) states.",1
"Anishkin, Andriy, Sukharev, Sergei, Sukharev, S",2
Short class I major histocompatibility complex cytoplasmic tails differing in charge detect arbiters of lateral diffusion in the plasma membrane.,0
"Directed and Brownian movement of class I major histocompatibility complex (MHC) molecules on cell membranes is implicated in antigen presentation. Previous studies indicated that the class I MHC cytoplasmic tail imposes constraints on the molecule's diffusion. Here we used single particle tracking to study the mobility of the wild-type mouse H-2L(d) class I MHC molecule and of seven cytoplasmic tail variants. Six of the variants have cytoplasmic tails of four or seven residues (differing in net charge), and one is tailless, yet all are susceptible to confinement in membrane domains. However, truncation of the cytoplasmic tail to 0-4 residues decreases the proportion of particles exhibiting confined diffusion and increases the proportion exhibiting simple diffusion. Particularly for the truncated mutants (tail length of 0-7 residues), many of the particles have complex trajectories and do not move at a constant speed or in the same mode of diffusion throughout the observation period. Several particles of the tailless H-2L(d) mutant display a type of directed diffusion that is rarely observed for other H-2L(d) mutants. Taken together, these data show that even short cytoplasmic tails can influence markedly class I MHC mobility and that cytoplasmic tail length and sequence affect the molecule's diffusion in the membrane.",1
"Capps, G George, Pine, Samuel, Edidin, Michael, Zúñiga, Martha C",2
Liquid domains in vesicles investigated by NMR and fluorescence microscopy.,0
"We use (2)H-NMR, (1)H-MAS NMR, and fluorescence microscopy to detect immiscibility in three particular phospholipid ratios mixed with 30% cholesterol: 2:1 DOPC/DPPC, 1:1 DOPC/DPPC, and 1:2 DOPC/DPPC. Large-scale (>160 nm) phase separation into liquid-ordered (L(o)) and liquid-crystalline (L(alpha)) phases is observed by both NMR and fluorescence microscopy. By fitting superimposed (2)H-NMR spectra, we quantitatively determine that the L(o) phase is strongly enriched in DPPC and moderately enriched in cholesterol. Tie-lines estimated at different temperatures and membrane compositions are based on both (2)H-NMR observations and a previously published ternary phase diagram. (2)H- and (1)H-MAS NMR techniques probe significantly smaller length scales than microscopy experiments (submicron versus micron-scalp), and complex behavior is observed near the miscibility transition. Fluorescence microscopy of giant unilamellar vesicles shows micrometer-scale domains below the miscibility transition. In contrast, NMR of multilamellar vesicles gives evidence for smaller ( approximately 80 nm) domains just below the miscibility transition, whereas large-scale demixing occurs at a lower temperature, T(low). A transition at T(low) is also evident in fluorescence microscopy measurements of the surface area fraction of ordered phase in giant unilamellar vesicles. Our results reemphasize the complex phase behavior of cholesterol-containing membranes and provide a framework for interpreting (2)H-NMR experiments in similar membranes.",1
"Veatch, S L, Polozov, I V, Gawrisch, K, Keller, S L",2
Tension in tubulovesicular networks of Golgi and endoplasmic reticulum membranes.,0
"The endoplasmic reticulum (ER) and Golgi have robust bidirectional traffic between them and yet form distinct membrane compartments. Membrane tubules are pulled from large aggregates of ER or Golgi by microtubule motors to form ER tubulovesicular networks or Golgi tubules both in vivo and in vitro. The physical properties of membranes are critical for membrane traffic and organelle morphology. For example, tension applied to membranes can create tethers, drive membrane flow, and set the diameter of the tubules. Here, we formed ER and Golgi membrane networks in vitro and used optical tweezers to measure directly, for the first time, the membrane tensions of these organelles to clarify the possible role of tension in membrane flow. We report that higher forces are needed to form tethers from ER (18.6 +/- 2.8 pN) than from Golgi (11.4 +/- 1.4 pN) membrane tubules in vitro. Since ER tubules are smaller in diameter than Golgi tubules, it follows that Golgi networks have a lower tension than ER. The lower tension of the ER could be an explanation of how Golgi tubules can be rapidly drawn into the ER by tension-driven flow after fusion, as is observed in vivo.",1
"Upadhyaya, Arpita, Sheetz, Michael P",2
Bimodal distribution and fluorescence response of environment-sensitive probes in lipid bilayers.,0
"A remarkable heterogeneity is often observed in the spectroscopic properties of environment-sensitive fluorescence probes in phospholipid bilayers. To explain its origin, we provided a detailed investigation of the fluorescence excitation and emission spectra of 4'-dimethylamino-3-hydroxyflavone (probe F) in bilayer vesicles with the variations of fatty acid composition, polar heads, temperature, and cholesterol content. Probe F, due to excited-state intramolecular proton transfer, exhibits two bands in emission that are differently sensitive to intermolecular interactions-thereby allowing us to distinguish universal (dipole-dipole) and specific (H-bonding) interactions within the bilayer. Spectroscopic, quenching, and anisotropy data suggest the presence of two forms of probe F at different locations in the bilayer: an H-bond free form located below sn(1)-carbonyls and an H-bonded form located at the polar membrane interface. We provide a quantitative analysis of the distribution of the probe between these two locations as well as the polarity of these locations, and show that both the distribution and the polarity contribute to the probe response. Moreover, analysis of literature data on other environment-sensitive probes (Prodan, Laurdan, Nile Red, NBD lipids, etc.) in lipid bilayers allows us to suggest that the bimodal distribution in the lipid bilayer is probably a general feature of low-polar molecules with polar groups capable of H-bonding interactions.",1
"Klymchenko, Andrey S, Duportail, Guy, Demchenko, Alexander P, Mély, Yves",2
Nonequilibrium behavior in supported lipid membranes containing cholesterol.,0
"We investigate lateral organization of lipid domains in vesicles versus supported membranes and monolayers. The lipid mixtures used are predominantly DOPC/DPPC/Chol and DOPC/BSM/Chol, which have been previously shown to produce coexisting liquid phases in vesicles and monolayers. In a monolayer at an air-water interface, these lipids have miscibility transition pressures of approximately 12-15 mN/m, which can rise to 32 mN/m if the monolayer is exposed to air. Lipid monolayers can be transferred by Langmuir-Schäfer deposition onto either silanized glass or existing Langmuir-Blodgett supported monolayers. Micron-scale domains are present in the transferred lipids only if they were present in the original monolayer before deposition. This result is valid for transfers at 32 mN/m and also at lower pressures. Domains transferred to glass supports differ from liquid domains in vesicles because they are static, do not align in registration across leaflets, and do not reappear after temperature is cycled. Similar static domains are found for vesicles ruptured onto glass surfaces. Although supported membranes on glass capture some aspects of vesicles in equilibrium (e.g., gel-liquid transition temperatures and diffusion rates of individual lipids), the collective behavior of lipids in large liquid domains is poorly reproduced.",1
"Stottrup, Benjamin L, Veatch, Sarah L, Keller, Sarah L",2
Energetics of vesicle fusion intermediates: comparison of calculations with observed effects of osmotic and curvature stresses.,0
"We reported previously the effects of both osmotic and curvature stress on fusion between poly(ethylene glycol)-aggregated vesicles. In this article, we analyze the energetics of fusion of vesicles of different curvature, paying particular attention to the effects of osmotic stress on small, highly curved vesicles of 26 nm diameter, composed of lipids with negative intrinsic curvature. Our calculations show that high positive curvature of the outer monolayer ""charges"" these vesicles with excess bending energy, which then releases during stalk expansion (increase of the stalk radius, r(s)) and thus ""drives"" fusion. Calculations based on the known mechanical properties of lipid assemblies suggest that the free energy of ""void"" formation as well as membrane-bending free energy dominate the evolution of a stalk to an extended transmembrane contact. The free-energy profile of stalk expansion (free energy versus r(s)) clearly shows the presence of two metastable intermediates (intermediate 1 at r(s) approximately 0 - 1.0 nm and intermediate 2 at r(s) approximately 2.5 - 3.0 nm). Applying osmotic gradients of +/-5 atm, when assuming a fixed trans-bilayer lipid mass distribution, did not significantly change the free-energy profile. However, inclusion in the model of an additional degree of freedom, the ability of lipids to move into and out of the ""void"", made the free-energy profile strongly dependent on the osmotic gradient. Vesicle expansion increased the energy barrier between intermediates by approximately 4 kT and the absolute value of the barrier by approximately 7 kT, whereas compression decreased it by nearly the same extent. Since these calculations, which are based on the stalk hypothesis, correctly predict the effects of both membrane curvature and osmotic stress, they support the stalk hypothesis for the mechanism of membrane fusion and suggest that both forms of stress alter the final stages, rather than the initial step, of the fusion process, as previously suggested.",1
"Malinin, Vladimir S, Lentz, Barry R",2
Role of cholesterol in the formation and nature of lipid rafts in planar and spherical model membranes.,0
"Sterols play a crucial regulatory and structural role in the lateral organization of eukaryotic cell membranes. Cholesterol has been connected to the possible formation of ordered lipid domains (rafts) in mammalian cell membranes. Lipid rafts are composed of lipids in the liquid-ordered (l(o)) phase and are surrounded with lipids in the liquid-disordered (l(d)) phase. Cholesterol and sphingomyelin are thought to be the principal components of lipid rafts in cell and model membranes. We have used fluorescence microscopy and fluorescence recovery after photobleaching in planar supported lipid bilayers composed of porcine brain phosphatidylcholine (bPC), porcine brain sphingomyelin (bSM), and cholesterol to map the composition-dependence of l(d)/l(o) phase coexistence. Cholesterol decreases the fluidity of bPC bilayers, but disrupts the highly ordered gel phase of bSM, leading to a more fluid membrane. When mixed with bPC/bSM (1:1) or bPC/bSM (2:1), cholesterol induces the formation of l(o) phase domains. The fraction of the membrane in the l(o) phase was found to be directly proportional to the cholesterol concentration in both phospholipid mixtures, which implies that a significant fraction of bPC cosegregates into l(o) phase domains. Images reveal a percolation threshold, i.e., the point where rafts become connected and fluid domains disconnected, when 45-50% of the total membrane is converted to the l(o) phase. This happens between 20 and 25 mol % cholesterol in 1:1 bPC/bSM bilayers and between 25 and 30 mol % cholesterol in 2:1 bPC/bSM bilayers at room temperature, and at approximately 35 mol % cholesterol in 1:1 bPC/bSM bilayers at 37 degrees C. Area fractions of l(o) phase lipids obtained in multilamellar liposomes by a fluorescence resonance energy transfer method confirm and support the results obtained in planar lipid bilayers.",1
"Crane, Jonathan M, Tamm, Lukas K",2
Domain formation in phosphatidylinositol monophosphate/phosphatidylcholine mixed vesicles.,0
"Phosphoinositides have been shown to control membrane trafficking events by targeting proteins to specific cellular sites, which requires a tight regulation of phosphoinositide generation and turnover as well as a high degree of compartmentalization. To shed light on the processes that lead to the formation of phosphoinositide-enriched microdomains, phosphatidylcholine/phosphatidylinositol monophosphate (phosphatidylinositol-3-phosphate (PI-3P), -4-phosphate (PI-4P), or -5-phosphate (PI-5P)) mixed vesicles were investigated by calorimetric (DSC) Fourier transform infrared spectroscopic (FTIR), and fluorescence resonance energy transfer (FRET) measurements. The experiments furnished results consistent with a pH-dependent formation of phosphatidylinositol monophosphate-enriched microdomains. The domain formation was most pronounced between pH approximately 7 and approximately 9.5, whereas slightly acidic pH values (pH 4) resulted in the disintegration of the domains. This pH-dependent phosphatidylcholine/phosphatidylinositol monophosphate demixing was observed for the gel phase (FTIR experiments) as well as for the fluid lipid phase (FRET measurements). The observed microdomains are presumably stabilized by hydroxyl/hydroxyl as well as hydroxyl/phosphomonoester and phosphodiester interactions. While the pH dependence of the mutual phosphatidylinositol monophosphate interaction was largely the same for all investigated phosphatidylinositol monophosphates, it turned out that the relative stability of phosphatidylinositol monophosphate-enriched microdomains (pH 7-9.5) was governed by the position of the phosphomonoester group at the inositol ring (PI-4P > PI-5P > PI-3P). Demixing was also observed for phosphatidylcholine/phosphatidylinositol mixed vesicles; however, in this case the microdomain formation was only slightly affected by pH changes.",1
"Redfern, Duane A, Gericke, Arne",2
Structural and functional roles of desmin in mouse skeletal muscle during passive deformation.,0
"Mechanical interactions between desmin and Z-disks, costameres, and nuclei were measured during passive deformation of single muscle cells. Image processing and continuum kinematics were used to quantify the structural connectivity among these structures. Analysis of both wild-type and desmin-null fibers revealed that the costamere protein talin colocalized with the Z-disk protein alpha-actinin, even at very high strains and stresses. These data indicate that desmin is not essential for mechanical coupling of the costamere complex and the sarcomere lattice. Within the sarcomere lattice, significant differences in myofibrillar connectivity were revealed between passively deformed wild-type and desmin-null fibers. Connectivity in wild-type fibers was significantly greater compared to desmin-null fibers, demonstrating a significant functional connection between myofibrils that requires desmin. Passive mechanical analysis revealed that desmin may be partially responsible for regulating fiber volume, and consequently, fiber mechanical properties. Kinematic analysis of alpha-actinin strain fields revealed that knockout fibers transmitted less shear strain compared to wild-type fibers and experienced a slight increase in fiber volume. Finally, linkage of desmin intermediate filaments to muscle nuclei was strongly suggested based on extensive loss of nuclei positioning in the absence of desmin during passive fiber loading.",1
"Shah, Sameer B, Davis, Jennifer, Weisleder, Noah, Kostavassili, Ioanna, McCulloch, Andrew D, Ralston, Evelyn, Capetanaki, Yassemi, Lieber, Richard L",2
"Cross-bridge number, position, and angle in target zones of cryofixed isometrically active insect flight muscle.",0
"Electron micrographic tomograms of isometrically active insect flight muscle, freeze substituted after rapid freezing, show binding of single myosin heads at varying angles that is largely restricted to actin target zones every 38.7 nm. To quantify the parameters that govern this pattern, we measured the number and position of attached myosin heads by tracing cross-bridges through the three-dimensional tomogram from their origins on 14.5-nm-spaced shelves along the thick filament to their thin filament attachments in the target zones. The relationship between the probability of cross-bridge formation and axial offset between the shelf and target zone center was well fitted by a Gaussian distribution. One head of each myosin whose origin is close to an actin target zone forms a cross-bridge most of the time. The probability of cross-bridge formation remains high for myosin heads originating within 8 nm axially of the target zone center and is low outside 12 nm. We infer that most target zone cross-bridges are nearly perpendicular to the filaments (60% within 11 degrees ). The results suggest that in isometric contraction, most cross-bridges maintain tension near the beginning of their working stroke at angles near perpendicular to the filament axis. Moreover, in the absence of filament sliding, cross-bridges cannot change tilt angle while attached nor reach other target zones while detached, so may cycle repeatedly on and off the same actin target monomer.",1
"Tregear, Richard T, Reedy, Mary C, Goldman, Yale E, Taylor, Kenneth A, Winkler, Hanspeter, Franzini-Armstrong, Clara, Sasaki, Hiroyuki, Lucaveche, Carmen, Reedy, Michael K",2
Myosin regulatory domain orientation in skeletal muscle fibers: application of novel electron paramagnetic resonance spectral decomposition and molecular modeling methods.,0
"Reorientation of the regulatory domain of the myosin head is a feature of all current models of force generation in muscle. We have determined the orientation of the myosin regulatory light chain (RLC) using a spin-label bound rigidly and stereospecifically to the single Cys-154 of a mutant skeletal isoform. Labeled RLC was reconstituted into skeletal muscle fibers using a modified method that results in near-stoichiometric levels of RLC and fully functional muscle. Complex electron paramagnetic resonance spectra obtained in rigor necessitated the development of a novel decomposition technique. The strength of this method is that no specific model for a complex orientational distribution was presumed. The global analysis of a series of spectra, from fibers tilted with respect to the magnetic field, revealed two populations: one well-ordered (+/-15 degrees ) with the spin-label z axis parallel to actin, and a second population with a large distribution (+/-60 degrees ). A lack of order in relaxed or nonoverlap fibers demonstrated that regulatory domain ordering was defined by interaction with actin rather than the thick filament surface. No order was observed in the regulatory domain during isometric contraction, consistent with the substantial reorientation that occurs during force generation. For the first time, spin-label orientation has been interpreted in terms of the orientation of a labeled domain. A Monte Carlo conformational search technique was used to determine the orientation of the spin-label with respect to the protein. This in turn allows determination of the absolute orientation of the regulatory domain with respect to the actin axis. The comparison with the electron microscopy reconstructions verified the accuracy of the method; the electron paramagnetic resonance determined that axial orientation was within 10 degrees of the electron microscopy model.",1
"Baumann, Bruce A J, Liang, Hua, Sale, Ken, Hambly, Brett D, Fajer, Piotr G",2
Slow calcium signals after tetanic electrical stimulation in skeletal myotubes.,0
"The fluorescent calcium signal from rat myotubes in culture was monitored after field-stimulation with tetanic protocols. After the calcium signal sensitive to ryanodine and associated to the excitation-contraction coupling, a second long-lasting calcium signal refractory to ryanodine was consistently found. The onset kinetics of this slow signal were slightly modified in nominally calcium-free medium, as were both the frequency and number of pulses during tetanus. No signal was detected in the presence of tetrodotoxin. The participation of the dihydropyridine receptor (DHPR) as the voltage sensor for this signal was assessed by treatment with agonist and antagonist dihydropyridines (Bay K 8644 and nifedipine), showing an enhanced and inhibitory response, respectively. In the dysgenic GLT cell line, which lacks the alpha1(S) subunit of the DHPR, the signal was absent. Transfection of these cells with the alpha1(S) subunit restored the slow signal. In myotubes, the inositol 1,4,5-trisphosphate (IP(3)) mass increase induced by a tetanus protocol preceded in time the slow calcium signal. Both an IP(3) receptor blocker and a phospholipase C inhibitor (xestospongin C and U73122, respectively) dramatically inhibit this signal. Long-lasting, IP(3)-generated slow calcium signals appear to be a physiological response to activity-related fluctuations in membrane potential sensed by the DHPR.",1
"Eltit, José M, Hidalgo, Jorge, Liberona, José L, Jaimovich, Enrique",2
Low-resolution reconstruction of a synthetic DNA holliday junction.,0
"We have studied the low-resolution solution conformation of a Holliday (or four-way) DNA junction by using small-angle x-ray scattering, sedimentation velocity, and computational modeling techniques. The scattering data were analyzed in two independent ways: firstly, by rigid-body modeling of the scattering data using previously suggested models for the Holliday junction (HJ), and secondly, by ab initio reconstruction methods. The models found by both methods agree with experimentally determined sedimentation coefficients and are compatible with the results of previous studies using different techniques, but provide a more direct and accurate determination of the solution conformation of the HJ. Our results show that addition of Mg(2+) alters the conformation of the HJ from an extended to a stacked arrangement.",1
"Nöllmann, Marcelo, Stark, W Marshall, Byron, Olwyn",2
Specific versus nonspecific binding of cationic PNAs to duplex DNA.,0
"Although peptide nucleic acids (PNAs) are neutral by themselves, they are usually appended with positively charged lysine residues to increase their solubility and binding affinity for nucleic acid targets. Thus obtained cationic PNAs very effectively interact with the designated duplex DNA targets in a sequence-specific manner forming strand-invasion complexes. We report on the study of the nonspecific effects in the kinetics of formation of sequence-specific PNA-DNA complexes. We find that in a typical range of salt concentrations used when working with strand-invading PNAs (10-20 mM NaCl) the PNA binding rates essentially do not depend on the presence of nontarget DNA in the reaction mixture. However, at lower salt concentrations (<10 mM NaCl), the rates of PNA binding to DNA targets are significantly slowed down by the excess of unrelated DNA. This effect of nontarget DNA arises from depleting the concentration of free PNA capable of interacting with DNA target due to adhesion of positively charged PNA molecules on the negatively charged DNA duplex. As expected, the nonspecific electrostatic effects are more pronounced for more charged PNAs. We propose a simple model quantitatively describing all major features of the observed phenomenon. This understanding is important for design of and manipulation with the DNA-binding polycationic ligands in general and PNA-based drugs in particular.",1
"Abibi, Ayome, Protozanova, Ekaterina, Demidov, Vadim V, Frank-Kamenetskii, Maxim D",2
Monte Carlo simulations of locally melted supercoiled DNAs in 20 mM ionic strength.,0
"Mesoscopic models of unmelted and locally melted supercoiled DNAs in 20 mM ionic strength are simulated over a range of linking difference from deltal = 0 to -26 turns, or superhelix density from sigma = 0 to -0.062. A domain containing m = 0, 28, or 56 melted basepairs (out of 4349 total) is modeled simply by a region of suitable length with substantially reduced torsion and bending elastic constants. Average structural properties are calculated from the saved configurations, and a reversible work protocol is used to calculate the supercoiling free energy, The cross-writhe between duplex and melted regions (defined herein) is found to be negligibly small. The total writhe, radius of gyration, and ordered elements of the diagonalized inertial tensor are found to be nearly universal functions of the residual linking difference (deltal(r)) associated with the duplex region, independent of m. However, deformability of the tertiary structure, as manifested by the variance of those same properties, is not a universal function of deltal(r)), but depends upon m.delta (SC) varies with deltal(r)) more strongly than deltal(r)) (2)due to the low ionic strength. The twist energy parameter, E (T) obtained from the simulated delta G(SC), deltal(r)), and net twisting strain of the melted region T (D), is found to be independent of m, hence also of the torsion and bending elastic constants of the melted region. However, E(T) increases linearly with -deltalr), which leads to 1). a small overestimation of E (T) for any given deltal(r)) when E(T) is determined from the observed deltal and deltal (r) by the protocol of Bauer and Benham; and 2). a significant enhancement of the apparent slope, -dE(T)/d(T), obtained via the protocol of Bauer and Benham, relative to the actual slope at fixed delta l(r). After taking these two effects into account, the theoretical and experimental values E(T) and -dE(T)/d(T) values agree rather well. For the larger deltal the melted regions are found preferentially in the linker domains between interwound arms, rather than in the apical regions at the ends of interwound arms.",1
"Sucato, Christopher A, Rangel, David P, Aspleaf, Dan, Fujimoto, Bryant S, Schurr, J Michael",2
Insight into the structural role of carotenoids in the photosystem I: a quantum chemical analysis.,0
"The structural stabilization role of carotenoids in the formation of photosynthetic pigment-protein complexes is investigated theoretically. The pi-pi stacking and CH-pi interactions between beta-carotenes and their surrounding chlorophylls (and/or aromatic residues) in Photosystem I (PS1) from the cyanobacterium Synechococcus elongatus were studied by means of the supermolecular approach at the level of the second-order Møller-Plesset perturbation method. PS1 features a core integral antenna system consisting of 22 beta-carotenes intertwined with 90 chlorophyll molecules. The binding environments of all 22 beta-carotenes were systematically analyzed. For 21 out of the 22 cases, one or more chlorophyll molecules exist within van der Waals' contacts of the beta-carotene molecule. The calculated strengths of pi-pi stacking interactions between the conjugated core of beta-carotene and the aromatic tetrapyrrole rings of chlorophyll are substantial, ranging from -3.54 kcal/mol for the perpendicular-positioned BCR4004...CHL1217 pair to -16.01 kcal/mol for the parallel-oriented BCR4007...CHL1122 pair. A strong dependence of the pi-pi stacking interaction energies on the intermolecular configurations of the two interacting pi-planes is observed. The parallel-oriented beta-carotene and chlorophyll pair is energetically much more stable than the perpendicular-positioned pair. The larger the extent of pi-pi overlapping, the stronger the interaction strength. In many cases, the beta-ring ends of beta-carotene molecules are found to interact with the tetrapyrrole rings of chlorophyll via CH-pi interactions. For the latter interactions, the calculated interaction strengths vary from -7.03 to -11.03 kcal/mol, depending on the intermolecular configuration. This work leads to the conclusion that pi-pi stacking and CH-pi interactions between beta-carotene and their surrounding chlorophylls and aromatic residues play an essential role in binding beta-carotenes in PS1 from S. elongatus. Consequently, the molecular basis of the structural stabilization function of carotenoids in formation of the photosynthetic pigment-protein complexes is established.",1
"Wang, Yanli, Mao, Lisong, Hu, Xiche",2
Role of Arg-72 of pharaonis Phoborhodopsin (sensory rhodopsin II) on its photochemistry.,0
"Pharaonis phoborhodopsin (ppR, or pharaonis sensory rhodopsin II, NpsRII) is a sensor for the negative phototaxis of Natronomonas (Natronobacterium) pharaonis. Arginine 72 of ppR corresponds to Arg-82 of bacteriorhodopsin, which is a highly conserved residue among microbial rhodopsins. Using various Arg-72 ppR mutants, we obtained the following results: 1). Arg-72(ppR) together possibly with Asp-193 influenced the pK(a) of the counterion of the protonated Schiff base. 2). The M-rise became approximately four times faster than the wild-type. 3). Illumination causes proton uptake and release, and the pH profiles of the sequence of these two proton movements were different between R72A mutant and the wild-type; it is inferred that Arg-72 connects the proton transfer events occurring at both the Schiff base and an extracellular proton-releasing residue (Asp-193). 4). The M-decays of Arg-72 mutants were faster ( approximately 8-27 folds at pH 8 depending on mutants) than the wild-type, implying that the guanidinium prevents the proton transfer from the extracellular space to the deprotonated Schiff base. 5), The proton-pumping activities were decreased for mutants having increased M-decay rates, but the extent of the decrease was smaller than expected. The role of Arg-72 of ppR on the photochemistry was discussed.",1
"Ikeura, Yukako, Shimono, Kazumi, Iwamoto, Masayuki, Sudo, Yuki, Kamo, Naoki",2
Electrochromic shift of chlorophyll absorption in photosystem I from Synechocystis sp. PCC 6803: a probe of optical and dielectric properties around the secondary electron acceptor.,0
"Nanosecond absorption dynamics at approximately 685 nm after excitation of photosystem I (PS I) from Synechocystis sp. PCC 6803 is consistent with electrochromic shift of absorption bands of the Chl a pigments in the vicinity of the secondary electron acceptor A(1). Based on experimental optical data and structure-based simulations, the effective local dielectric constant has been estimated to be between 3 and 20, which suggests that electron transfer in PS I is accompanied by considerable protein relaxation. Similar effective dielectric constant values have been previously observed for the bacterial photosynthetic reaction center and indicate that protein reorganization leading to effective charge screening may be a necessary structural property of proteins that facilitate the charge transfer function. The data presented here also argue against attributing redmost absorption in PS I to closely spaced antenna chlorophylls (Chls) A38 and A39, and suggest that optical transitions of these Chls, along with that of connecting chlorophyll (A40) lie in the range 680-695 nm.",1
"Dashdorj, Naranbaatar, Xu, Wu, Martinsson, Peter, Chitnis, Parag R, Savikhin, Sergei",2
"Conformation and dynamics of the [3-(13)C]Ala, [1-(13)C]Val-labeled truncated pharaonis transducer, pHtrII(1-159), as revealed by site-directed (13)C solid-state NMR: changes due to association with phoborhodopsin (sensory rhodopsin II).",0
"We have recorded (13)C NMR spectra of the [3-(13)C]Ala, [1-(13)C]Val-labeled pharaonis transducer pHtrII(1-159) in the presence and absence of phoborhodopsin (ppR or sensory rhodopsin II) in egg phosphatidylcholine or dimyristoylphosphatidylcholine bilayers by means of site-directed (amino acid specific) solid-state NMR. Two kinds of (13)C NMR signals of [3-(13)C]Ala-pHtrII complexed with ppR were clearly seen with dipolar decoupled magic angle spinning (DD-MAS) NMR. One of these resonances was at the peak position of the low-field alpha-helical peaks (alpha(II)-helix) and is identified with cytoplasmic alpha-helices protruding from the bilayers; the other was the high-field alpha-helical peak (alpha(I)-helix) and is identified with the transmembrane alpha-helices. The first peaks, however, were almost completely suppressed by cross-polarization magic angle spinning (CP-MAS) regardless of the presence or absence of ppR or by DD-MAS NMR in the absence of ppR. This is caused by an increased fluctuation frequency of the cytoplasmic alpha-helix from 10(5) Hz in the uncomplexed states to >10(6) Hz in the complexed states, leading to the appearance of peaks that were suppressed because of the interference of the fluctuation frequency with the frequency of proton decoupling (10(5) Hz), as viewed from the (13)C NMR spectra of [3-(13)C]Ala-labeled pHtrII. Consistent with this view, the (13)C DD-MAS NMR signals of the cytoplasmic alpha-helices of the complexed [3-(13)C]Ala-pHtrII in the dimyristoylphosphatidylcholine (DMPC) bilayer were partially suppressed at 0 degrees C due to a decreased fluctuation frequency at the low temperature. In contrast, examination of the (13)C CP-MAS spectra of [1-(13)C]Val-labeled complexed pHtrII showed that the (13)C NMR signals of the transmembrane alpha-helix were substantially suppressed. These spectral changes are again interpreted in terms of the increased fluctuation frequency of the transmembrane alpha-helices from 10(3) Hz of the uncomplexed states to 10(4) Hz of the complexed states. These findings substantiate the view that the transducers alone are in an aggregated or clustered state but the ppR-pHtrII complex is not aggregated. We show that (13)C NMR is a very useful tool for achieving a better understanding of membrane proteins which will serve to clarify the molecular mechanism of signal transduction in this system.",1
"Yamaguchi, Satoru, Shimono, Kazumi, Sudo, Yuki, Tuzi, Satoru, Naito, Akira, Kamo, Naoki, Saitô, Hazime",2
"The role of cholesterol in the activity of pneumolysin, a bacterial protein toxin.",0
"The mechanism via which pneumolysin (PLY), a toxin and major virulence factor of the bacterium Streptococcus pneumoniae, binds to its putative receptor, cholesterol, is still poorly understood. We present results from a series of biophysical studies that shed light on the interaction of PLY with cholesterol in solution and in lipid bilayers. PLY lyses cells whose walls contain cholesterol. Using standard hemolytic assays we have demonstrated that the hemolytic activity of PLY is inhibited by cholesterol, partially by ergosterol but not by lanosterol and that the functional stoichiometry of the cholesterol-PLY complex is 1:1. Tryptophan (Trp) fluorescence data recorded during PLY-cholesterol titration studies confirm this ratio, reveal a significant blue shift in the Trp fluorescence peak with increasing cholesterol concentrations indicative of increasing nonpolarity in the Trp environment, consistent with cholesterol binding by the tryptophans, and provide a measure of the affinity of cholesterol binding: K(d) = 400 +/- 100 nM. Finally, we have performed specular neutron reflectivity studies to observe the effect of PLY upon lipid bilayer structure.",1
"Nöllmann, Marcelo, Gilbert, Robert, Mitchell, Timothy, Sferrazza, Michele, Byron, Olwyn",2
The influence of solvent composition on global dynamics of human butyrylcholinesterase powders: a neutron-scattering study.,0
"A major result of incoherent elastic neutron-scattering experiments on protein powders is the strong dependence of the intramolecular dynamics on the sample environment. We performed a series of incoherent elastic neutron-scattering experiments on lyophilized human butyrylcholinesterase (HuBChE) powders under different conditions (solvent composition and hydration degree) in the temperature range from 20 to 285 K to elucidate the effect of the environment on the enzyme atomic mean-square displacements. Comparing D(2)O- with H(2)O-hydrated samples, we were able to investigate protein as well as hydration water molecular dynamics. HuBChE lyophilized from three distinct buffers showed completely different atomic mean-square displacements at temperatures above approximately 200 K: a salt-free sample and a sample containing Tris-HCl showed identical small-amplitude motions. A third sample, containing sodium phosphate, displayed highly reduced mean-square displacements at ambient temperature with respect to the other two samples. Below 200 K, all samples displayed similar mean-square displacements. We draw the conclusion that the reduction of intramolecular protein mean-square displacements on an Angstrom-nanosecond scale by the solvent depends not only on the presence of salt ions but also on their type.",1
"Gabel, F, Weik, M, Doctor, B P, Saxena, A, Fournier, D, Brochier, L, Renault, F, Masson, P, Silman, I, Zaccai, G",2
"Structure and solvation of melittin in 1,1,1,3,3,3-hexafluoro-2-propanol/water.",0
"Fluorinated alcohols can induce peptides and proteins to take up helical conformations. Nuclear Overhauser effect (NOE) spectroscopy experiments and analysis of C(alpha)H proton chemical shifts show that the conformation of melittin in 35% hexafluoro-2-propanol/water is alpha-helical from residues Ile-2 to Val-8 and from Leu-13 to Gln-25. As has been found in other solvent systems, the two helical regions are not colinear; the interhelix angle (73 +/- 15 degrees ) in 35% 1,1,1,3,3,3-hexafluoro-2-propanol/water is smaller than the angle found in other fluoroalcohol-water mixtures or in the crystal. Intermolecular (1)H(19)F and (1)H(1)H nuclear Overhauser effects were used to explore interaction of solvent components with melittin dissolved in this solvent mixture. The NOEs observed indicate that fluoroalcohol and water molecules are both tightly bound to the peptide in the vicinity of the interhelix bend. For the remainder of the molecule, solute-solvent NOEs are consistent with preferential solvation of the peptide by the fluoroalcohol component of the solvent mixture.",1
"Gerig, J T",2
Temperature derivative fluorescence spectroscopy as a tool to study dynamical changes in protein crystals.,0
"Motions through the energy landscape of proteins lead to biological function. At temperatures below a dynamical transition (150-250 K), some of these motions are arrested and the activity of some proteins ceases. Here, we introduce the technique of temperature-derivative fluorescence microspectrophotometry to investigate the dynamical behavior of single protein crystals. The observation of glass transitions in thin films of water/glycerol mixtures allowed us to demonstrate the potential of the technique. Then, protein crystals were investigated, after soaking the samples in a small amount of fluorescein. If the fluorophore resides within the crystal channels, temperature-dependent changes in solvent dynamics can be monitored. Alternatively, if the fluorophore binds to the protein, local dynamical transitions within the biomolecule can be probed directly. A clear dynamical transition was observed at 175 K in the active site of crystalline human butyrylcholinesterase. The results suggest that the dynamics of crystalline proteins is strongly dependent on solvent composition and confinement in the crystal channels. Beyond applications in the field of kinetic crystallography, the highly sensitive temperature-derivative fluorescence microspectrophotometry technique opens the way to many studies on the dynamics of biological nanosamples.",1
"Weik, Martin, Vernede, Xavier, Royant, Antoine, Bourgeois, Dominique",2
Theoretical analysis of twist/bend ratio and mechanical moduli of bacterial flagellar hook and filament.,0
"Certain motile bacteria employ rotating flagella for propulsion. The relative flexibility of two key components of the flagellum, filament and hook, is partially responsible for the mechanistic workings of this motor. A new computational method, the quantized elastic deformational model, was employed in this article to calculate the dimensionless twist/bend ratio (EI/GJ) of the filament and hook, providing a quantitative means to compare their relative stiffness. Both ratios were much <1.0, an average of 0.0440 for the filament and 0.0512 for the hook, indicating that within each structure bending is favored over twisting. These two ratios, along with previous experimental measurements, allowed us to propose a theoretical Young's modulus (E) between 10(6) and 10(7) dyn/cm(2) for the hook. This value is orders of magnitude smaller than experimentally determined Young's moduli of the filament, hence in agreement with empirical evidence linking compliance in the flagellum mainly to the hook.",1
"Flynn, Terence C, Ma, Jianpeng",2
Substrate-dependent morphology of supramolecular assemblies: fibrillin and type-VI collagen microfibrils.,0
"Substrate hydrophobicity/hydrophilicity has previously been shown to affect the morphology and biological function of isolated proteins. We have employed atomic force microscopy to investigate substrate dependent morphologies of two biochemically distinct native supramolecular assemblies: fibrillin and type-VI collagen microfibrils. These morphologically heterogeneous microfibrillar systems are found in many vertebrate tissues where they perform structural and cell-signaling roles. Fibrillin microfibrils adsorbed to a hydrophilic mica substrate adopted a diffuse morphology. Fibrillin microfibrils adsorbed to mica coated with poly-L-lysine or to borosilicate glass substrates had a more compact morphology and a directional asymmetry to the bead, which was not present on mica alone. Intermediate morphologies were observed along a substrate gradient. The classical double-beaded appearance of type-VI collagen microfibrils was evident on mica coated with poly-L-lysine and on glass. On hydrophilic mica, morphology was severely disrupted and there was a major conformational reorganization along the whole collagen microfibril repeat. These observations of substrate dependent conformation have important implications for the interpretation of data from in vitro protein interaction assays and cellular signaling studies. Furthermore, conformational changes may be induced by local charge environments in vivo, revealing or hiding binding sites.",1
"Sherratt, Michael J, Holmes, David F, Shuttleworth, C Adrian, Kielty, Cay M",2
Multiphoton-excited serotonin photochemistry.,0
"We report photochemical and photophysical studies of a multiphoton-excited reaction of serotonin that previously has been shown to generate a photoproduct capable of emitting broadly in the visible spectral region. The current studies demonstrate that absorption of near-infrared light by an intermediate state prepared via three-photon absorption enhances the photoproduct formation yield, with the largest action cross sections ( approximately 10(-19) cm(2)) observed at the short-wavelength limit of the titanium:sapphire excitation source. The intermediate state is shown to persist for at least tens of nanoseconds and likely to be different from a previously reported oxygen-sensitive intermediate. In addition, the two-photon fluorescence action spectrum for the fluorescent photoproduct was determined and found to have a maximum at approximately 780 nm (3.2 eV). A general mechanism for this photochemical process is proposed.",1
"Gostkowski, Michael L, Allen, Richard, Plenert, Matthew L, Okerberg, Eric, Gordon, Mary Jane, Shear, Jason B",2
Noninvasive auto-photoreduction used as a tool for studying structural changes in heme-copper oxidases by FTIR spectroscopy.,0
"We demonstrate an efficient Fourier transform infrared (FTIR) spectroscopic method, termed ""auto-photoreduction,"" that uses anaerobic photo-induced internal electron transfer to monitor reaction-initiated changes of heme-copper oxidases. It can be applied without the use of either expensive electrochemical equipment, or caged compounds, which cause significant background signals. At high irradiation power, carbon monoxide is released from high-spin heme a of cytochrome c oxidase and heme o from cytochrome bo(3). Photochemistry is initiated at wavelengths <355 nm, and the photochemical action spectrum has a maximum of 290 nm for cytochrome bo(3), which is consistent with the possible intermediate involvement of tyrosinate or an activated state of tyrosine. We propose that the final electron donors are proton channel water molecules. In the pH range of 4-9, the noninvasive auto-photoreduction method yields highly reproducible FTIR redox difference spectra within a broad range, resolving a number of vibrational changes outside the amide I region (1600-1640 cm(-1)). Furthermore, it provides details of redox-induced changes in the spectral region between 1600 and 1100 cm(-1). The auto-photoreduction method should be universally applicable to heme proteins.",1
"Bettinger, Karin, Prutsch, Alexander, Vogtt, Karsten, Lübben, Mathias",2
Mean-square displacement relationship in bioprotectant systems by elastic neutron scattering.,0
"Neutron intensity elastic scans on trehalose, maltose, and sucrose/H(2)O mixtures as a function of concentration, temperature, and exchanged wave vector are presented. The experimental findings show a crossover in molecular fluctuations between harmonic and anharmonic dynamical regimes. A new operative definition for the degree of fragility of glass-forming systems is furnished by using explicitly the connection between viscosity and mean-square displacement. The procedure is tested for the investigated mixtures and for a set of glass-forming systems. In this frame, the stronger character of trehalose/H(2)O mixture indicates a better attitude in respect to maltose and sucrose/H(2)O mixtures to encapsulate biostructures in a more rigid matrix.",1
"Magazù, S, Maisano, G, Migliardo, F, Mondelli, C",2
Imaging the activity and localization of single voltage-gated Ca(2+) channels by total internal reflection fluorescence microscopy.,0
"The patch-clamp technique has enabled functional studies of single ion channels, but suffers limitations including lack of spatial information and inability to independently monitor currents from more than one channel. Here, we describe the use of total internal reflection fluorescence microscopy as an alternative, noninvasive approach to optically monitor the activity and localization of multiple Ca(2+)-permeable channels in the plasma membrane. Images of near-membrane Ca(2+) signals were obtained from >100 N-type channels expressed within restricted areas (80 x 80 micro m) of Xenopus oocytes, thereby permitting simultaneous resolution of their gating kinetics, voltage dependence, and localization. Moreover, this technique provided information inaccessible by electrophysiological means, demonstrating that N-type channels are immobile in the membrane, show a patchy distribution, and display diverse gating kinetics even among closely adjacent channels. Total internal reflection fluorescence microscopy holds great promise for single-channel recording of diverse voltage- and ligand-gated Ca(2+)-permeable channels in the membrane of neurons and other isolated or cultured cells, and has potential for high-throughput functional analysis of single channels.",1
"Demuro, Angelo, Parker, Ian",2
Tissue electroporation: quantification and analysis of heterogeneous transport in multicellular environments.,0
"Although electroporation is gaining increased attention as a technology to enhance clinical chemotherapy and gene therapy of tissues, direct measurements of electroporation-mediated transport in multicellular environments are lacking. In this study, we used multicellular tumor spheroids of DU145 prostate cancer cells as a model tissue to measure the levels and distribution of molecular uptake in a multicellular environment as a function of electrical and other parameters. These measurements, and subsequent analysis, were used to test the hypothesis that cells in a multicellular environment respond to electroporation in a heterogeneous manner that differs from isolated cells in suspension due to differences in cell state, local solute concentration, and local electric field. In support of the hypothesis, molecular uptake was consistently lower for cells within spheroids than cells in dilute suspension and was spatially heterogeneous, with progressively less uptake observed for cells located deeper within spheroid interiors. Reduced uptake and heterogeneity can be explained quantitatively by accounting for the effects of cell size on transmembrane voltage and cell volume, limited extracellular solute reservoir, heterogeneous field strength due to influence of neighboring cells, and diffusional lag times.",1
"Canatella, Paul J, Black, Matthew M, Bonnichsen, David M, McKenna, Conor, Prausnitz, Mark R",2
Dynamic elastic modulus of porcine articular cartilage determined at two different levels of tissue organization by indentation-type atomic force microscopy.,0
"Cartilage stiffness was measured ex vivo at the micrometer and nanometer scales to explore structure-mechanical property relationships at smaller scales than has been done previously. A method was developed to measure the dynamic elastic modulus, |E(*)|, in compression by indentation-type atomic force microscopy (IT AFM). Spherical indenter tips (radius = approximately 2.5 microm) and sharp pyramidal tips (radius = approximately 20 nm) were employed to probe micrometer-scale and nanometer-scale response, respectively. |E(*)| values were obtained at 3 Hz from 1024 unloading response curves recorded at a given location on subsurface cartilage from porcine femoral condyles. With the microsphere tips, the average modulus was approximately 2.6 MPa, in agreement with available millimeter-scale data, whereas with the sharp pyramidal tips, it was typically 100-fold lower. In contrast to cartilage, measurements made on agarose gels, a much more molecularly amorphous biomaterial, resulted in the same average modulus for both indentation tips. From results of AFM imaging of cartilage, the micrometer-scale spherical tips resolved no fine structure except some chondrocytes, whereas the nanometer-scale pyramidal tips resolved individual collagen fibers and their 67-nm axial repeat distance. These results suggest that the spherical AFM tip is large enough to measure the aggregate dynamic elastic modulus of cartilage, whereas the sharp AFM tip depicts the elastic properties of its fine structure. Additional measurements of cartilage stiffness following enzyme action revealed that elastase digestion of the collagen moiety lowered the modulus at the micrometer scale. In contrast, digestion of the proteoglycans moiety by cathepsin D had little effect on |E(*)| at the micrometer scale, but yielded a clear stiffening at the nanometer scale. Thus, cartilage compressive stiffness is different at the nanometer scale compared to the overall structural stiffness measured at the micrometer and larger scales because of the fine nanometer-scale structure, and enzyme-induced structural changes can affect this scale-dependent stiffness differently.",1
"Stolz, Martin, Raiteri, Roberto, Daniels, A U, VanLandingham, Mark R, Baschong, Werner, Aebi, Ueli",2
The effect of alpha-actinin on the length distribution of F-actin.,0
"Actin filament length distribution in cells is often regulated to fit specific tasks. In comparison to the well-studied regulation of the average filament length (e.g., using capping proteins), controlling the width of the distribution is less well understood. We utilize two complementary methods to measure the effect of alpha-actinin on the width of the distribution of lengths of F-actin in vitro. Analyzing transmission electron micrographs shows that crosslinking by alpha-actinin reduces the width of the length distribution of F-actin, decreasing the coefficient of variation by two- to threefold. Analysis of fluorescence data from depolymerization assays confirms this observation. We suggest a mechanistic molecular model in which a local (weak) stabilization of crosslinked monomers in the filament is the physical origin of the decrease in the variance of lengths. Although alpha-actinin is known to bind reversibly to F-actin, our model shows that even weak binding can produce this effect, and that in fact it persists throughout a wide range of binding strengths.",1
"Biron, D, Moses, E",2
Specific recognition of macroscopic objects by the cell surface: evidence for a receptor density threshold revealed by micrometric particle binding characteristics.,0
"The establishment of specific molecular bonds between a cell and a facing surface is involved in many physiological and technological situations. Using micrometric magnetic particles, we have explored the formation of specific molecular bonds between the cell and surfaces bearing complementary ligands under passive conditions. Streptavidin-coated particles were targeted to the cell surface of a B-cell line through a specific biotinylated antibody against the CD19 receptor. Flow cytometry, optical microscopy, and micropipette experimental techniques have been used. Main findings have been that cell surface receptor density acted like a switch for particle capture with a threshold value found here equal to 1.6 x 10(3) receptor/ microm(2). This led to exclusion from binding of the cells of lowest receptor density. The density threshold was modulated by the length of the binding link and the physics of the cell/particle collision. We suggest that the shear stress is one of the main determinants of the characteristics of binding. We also show that several thousand receptors were involved in the cell particle contact at the end of the binding process, although only eight bonds are required for the initial capture of a particle. A passive binding inhibition process due to link concentration by the initial contact was proposed to account for the small number of particles per cell.",1
"Sarda, Stéphanie, Pointu, David, Pincet, Frédéric, Henry, Nelly",2
Shape memory of human red blood cells.,0
"The human red cell can be deformed by external forces but returns to the biconcave resting shape after removal of the forces. If after such shape excursions the rim is always formed by the same part of the membrane, the cell is said to have a memory of its biconcave shape. If the rim can form anywhere on the membrane, the cell would have no shape memory. The shape memory was probed by an experiment called go-and-stop. Locations on the membrane were marked by spontaneously adhering latex spheres. Shape excursions were induced by shear flow. In virtually all red cells, a shape memory was found. After stop of flow and during the return of the latex spheres to the original location, the red cell shape was biconcave. The return occurred by a tank-tread motion of the membrane. The memory could not be eliminated by deforming the red cells in shear flow up to 4 h at room temperature as well as at 37 degrees C. It is suggested that 1). the characteristic time of stress relaxation is >80 min and 2). red cells in vivo also have a shape memory.",1
"Fischer, Thomas M",2
Cytomechanical properties of papaver pollen tubes are altered after self-incompatibility challenge.,0
"Self-incompatibility (SI) in Papaver rhoeas triggers a ligand-mediated signal transduction cascade, resulting in the inhibition of incompatible pollen tube growth. Using a cytomechanical approach we have demonstrated that dramatic changes to the mechanical properties of incompatible pollen tubes are stimulated by SI induction. Microindentation revealed that SI resulted in a reduction of cellular stiffness and an increase in cytoplasmic viscosity. Whereas the former cellular response is likely to be the result of a drop in cellular turgor, we hypothesize that the latter is caused by as yet unidentified cross-linking events. F-actin rearrangements, a characteristic phenomenon for SI challenge in Papaver, displayed a spatiotemporal gradient along the pollen tube; this suggests that signal propagation occurs in a basipetal direction. However, unexpectedly, local application of SI inducing S-protein did not reveal any evidence for localized signal perception in the apical or subapical regions of the pollen tube. To our knowledge this represents the first mechanospatial approach to study signal propagation and cellular responses in a well-characterized plant cell system. Our data provide the first evidence for mechanical changes induced in the cytoplasm of a plant cell stimulated by a defined ligand.",1
"Geitmann, Anja, McConnaughey, William, Lang-Pauluzzi, Ingeborg, Franklin-Tong, Vernonica E, Emons, Anne Mie C",2
"A structural model of EmrE, a multi-drug transporter from Escherichia coli.",0
"Using a recently reported computational method, we describe an approach to model the structure of EmrE, a proton coupled multi-drug transporter of Escherichia coli. EmrE is the smallest ion-coupled transporter known; it functions as an oligomer and each monomer comprises four transmembrane segments. Because of its size, EmrE provides a unique experimental paradigm. The computational method does not afford a unique solution for the monomer. The experimental constraints available were used to select the most likely structure and to dock two monomers together to yield a dimer. The model is further validated by modeling of Hsmr, an EmrE homolog with a remarkable amino acid composition with over 40% of Ala and Val. The Hsmr model is similar to that of EmrE, with the majority of the Ala or Val residues facing the lipid. In addition, the model of EmrE features a putative substrate-binding site very similar to that observed in BmrR, a transcription activator of multi-drug transporters, with a similar substrate profile. The two crucial residues that couple proton fluxes with substrate binding in the homo-dimer of EmrE, Glu-14, have a spatial arrangement that agrees with proposed molecular mechanisms of transport.",1
"Gottschalk, Kay-Eberhard, Soskine, Misha, Schuldiner, Shimon, Kessler, Horst",2
The dependence of all-atom statistical potentials on structural training database.,0
"An accurate statistical energy function that is suitable for the prediction of protein structures of all classes should be independent of the structural database used for energy extraction. Here, two high-resolution, low-sequence-identity structural databases of 333 alpha-proteins and 271 beta-proteins were built for examining the database dependence of three all-atom statistical energy functions. They are RAPDF (residue-specific all-atom conditional probability discriminatory function), atomic KBP (atomic knowledge-based potential), and DFIRE (statistical potential based on distance-scaled finite ideal-gas reference state). These energy functions differ in the reference states used for energy derivation. The energy functions extracted from the different structural databases are used to select native structures from multiple decoys of 64 alpha-proteins and 28 beta-proteins. The performance in native structure selections indicates that the DFIRE-based energy function is mostly independent of the structural database whereas RAPDF and KBP have a significant dependence. The construction of two additional structural databases of alpha/beta and alpha + beta-proteins further confirmed the weak dependence of DFIRE on the structural databases of various structural classes. The possible source for the difference between the three all-atom statistical energy functions is that the physical reference state of ideal gas used in the DFIRE-based energy function is least dependent on the structural database.",1
"Zhang, Chi, Liu, Song, Zhou, Hongyi, Zhou, Yaoqi",2
Highly organized but pliant active site of DNA polymerase beta: compensatory mechanisms in mutant enzymes revealed by dynamics simulations and energy analyses.,0
"To link conformational transitions noted for DNA polymerases with kinetic results describing catalytic efficiency and fidelity, we investigate the role of key DNA polymerase beta residues on subdomain motion through simulations of five single-residue mutants: Arg-283-Ala, Tyr-271-Ala, Asp-276-Val, Arg-258-Lys, and Arg-258-Ala. Since a movement toward a closed state was only observed for R258A, we suggest that Arg(258) is crucial in modulating motion preceding chemistry. Analyses of protein/DNA interactions in the mutant active site indicate distinctive hydrogen bonding and van der Waals patterns arising from compensatory structural adjustments. By comparing closed mutant complexes with the wild-type enzyme, we interpret experimentally derived nucleotide binding affinities in molecular terms: R283A (decreased), Y271A (increased), D276V (increased), and R258A (decreased). Thus, compensatory interactions (e.g., in Y271A with adjacent residues Phe(272), Asn(279), and Arg(283)) increase the overall binding affinity for the incoming nucleotide although direct interactions may decrease. Together with energetic analyses, we predict that R258G might increase the rate of nucleotide insertion and maintain enzyme fidelity as R258A; D276L might increase the nucleotide binding affinity more than D276V; and R283A/K280A might decrease the nucleotide binding affinity and increase misinsertion more than R283A. The combined observations regarding key roles of specific residues (e.g., Arg(258)) and compensatory interactions echo the dual nature of polymerase active site, namely versatility (to accommodate various basepairs) and specificity (for preserving fidelity) and underscore an organized but pliant active site essential to enzyme function.",1
"Yang, Linjing, Beard, William A, Wilson, Samuel H, Broyde, Suse, Schlick, Tamar",2
Multisite phosphorylation and network dynamics of cyclin-dependent kinase signaling in the eukaryotic cell cycle.,0
"Multisite phosphorylation of regulatory proteins has been proposed to underlie ultrasensitive responses required to generate nontrivial dynamics in complex biological signaling networks. We used a random search strategy to analyze the role of multisite phosphorylation of key proteins regulating cyclin-dependent kinase (CDK) activity in a model of the eukaryotic cell cycle. We show that multisite phosphorylation of either CDK, CDC25, wee1, or CDK-activating kinase is sufficient to generate dynamical behaviors including bistability and limit cycles. Moreover, combining multiple feedback loops based on multisite phosphorylation do not destabilize the cell cycle network by inducing complex behavior, but rather increase the overall robustness of the network. In this model we find that bistability is the major dynamical behavior of the CDK signaling network, and that negative feedback converts bistability into limit cycle behavior. We also compare the dynamical behavior of several simplified models of CDK regulation to the fully detailed model. In summary, our findings suggest that multisite phosphorylation of proteins is a critical biological mechanism in generating the essential dynamics and ensuring robust behavior of the cell cycle.",1
"Yang, Ling, MacLellan, W Robb, Han, Zhangang, Weiss, James N, Qu, Zhilin",2
Lipid bilayer pressure profiles and mechanosensitive channel gating.,0
"The function of membrane proteins often depends on the proteins' interaction with their lipid environment, spectacularly so in the case of mechanosensitive channels, which are gated through tension mediated by the surrounding lipids. Lipid bilayer tension is distributed quite inhomogeneously, but neither the scale at which relevant variation takes place nor the effect of varying lipid composition or tension has yet been investigated in atomic detail. We calculated lateral pressure profile distributions in lipid bilayers of various composition from all-atom molecular dynamics simulations totaling 110.5 ns in length. Reproducible pressure profile features at the 1 A length scale were determined. Lipids with phosphatidylcholine headgroups were found to shift the lateral pressure out of the hydrophobic core and into the headgroup region by an amount that is independent of area per lipid. POPE bilayers simulated at areas smaller than optimal exerted dramatically higher lateral pressure in a narrow region at the start of the aliphatic chain. Stretching of POPC bilayers increased tension predominantly in the same region. A simple geometric analysis for the gating of the mechanosensitive channel MscL suggests that pressure profiles affect its gating through the second moment of the profile in a tension-independent manner.",1
"Gullingsrud, Justin, Schulten, Klaus",2
Two-state model for outer hair cell stiffness and motility.,0
"With discovery of the protein prestin and the gathering evidence linking it to outer hair cell electromotility, the working mechanism of outer hair cells is becoming clearer. Recent experiments have established the voltage-dependent stiffness of outer hair cells and given an insight into the nature of variation of stiffness with respect to voltage. These and earlier experiments are used to analyze and develop models of outer hair cell response. In this article, recent modeling efforts have been reconciled and placed into a common mechanics-based framework. The constitutive models are analyzed with regard to their capability to replicate experimental results. We extend the area motor model to include elastic constants dependent on motor state. The modified model successfully captures stiffness variations of outer hair cells and capacitance changes with respect to voltage.",1
"Deo, Niranjan, Grosh, Karl",2
"Simulations of a membrane-anchored peptide: structure, dynamics, and influence on bilayer properties.",0
"A three-dimensional structure of a model decapeptide is obtained by performing molecular dynamics simulations of the peptide in explicit water. Interactions between an N-myristoylated form of the folded peptide anchored to dipalmitoylphosphatidylcholine fluid phase lipid membranes are studied at different applied surface tensions by molecular dynamics simulations. The lipid membrane environment influences the conformational space explored by the peptide. The overall secondary structure of the anchored peptide is found to deviate at times from its structure in aqueous solution through reversible conformational transitions. The peptide is, despite the anchor, highly mobile at the membrane surface with the peptide motion along the bilayer normal being integrated into the collective modes of the membrane. Peptide anchoring moderately alters the lateral compressibility of the bilayer by changing the equilibrium area of the membrane. Although membrane anchoring moderately affects the elastic properties of the bilayer, the model peptide studied here exhibits conformational flexibility and our results therefore suggest that peptide acylation is a feasible way to reinforce peptide-membrane interactions whereby, e.g., the lifetime of receptor-ligand interactions can be prolonged.",1
"Jensen, Morten Ø, Mouritsen, Ole G, Peters, Gunther H",2
Modeling amyloid beta-peptide insertion into lipid bilayers.,0
"Inspired by recent suggestions that the Alzheimer's amyloid beta peptide (Abeta) can insert into cell membranes and form harmful ion channels, we model insertion of the 40- and 42-residue forms of the peptide into cell membranes using a Monte Carlo code which is specific at the amino acid level. We examine insertion of the regular Abeta peptide as well as mutants causing familial Alzheimer's disease, and find that all but one of the mutants change the insertion behavior by causing the peptide to spend more simulation steps in only one leaflet of the bilayer. We also find that Abeta42, because of the extra hydrophobic residues relative to Abeta40, is more likely to adopt this conformation than Abeta40 in both wild-type and mutant forms. We argue qualitatively why these effects happen. Here, we present our results and develop the hypothesis that this partial insertion increases the probability of harmful channel formation. This hypothesis can partly explain why these mutations are neurotoxic simply due to peptide insertion behavior. We further apply this model to various artificial Abeta mutants which have been examined experimentally, and offer testable experimental predictions contrasting the roles of aggregation and insertion with regard to toxicity of Abeta mutants. These can be used through further experiments to test our hypothesis.",1
"Mobley, David L, Cox, Daniel L, Singh, Rajiv R P, Maddox, Michael W, Longo, Marjorie L",2
Kinetic analysis of a model for double substrate cycling: highly amplified ADP (and/or ATP) quantification.,0
"A mathematical description has been made of an enzyme amplification mechanism involving the coupling of two substrate cycles. In this amplification system one of the noncycling products of a first substrate cycle acts as a trigger molecule that continuously feeds a second substrate cycle. Time-concentration equations describing the evolution of the species involved in the system have been obtained. The model is illustrated by the quantification of nanomolar levels of ADP (and/or ATP) in a continuous assay involving the enzymes L-lactate dehydrogenase and L-lactate oxidase to cycle the pyruvate accumulated in a first enzymatic cycle constituted by the enzymes pyruvate kinase and hexokinase. Progress curves were seen to be parabolic, and, according to the kinetic equations obtained, followed second-order polynomials of the reaction time. Mathematical equations for minimizing the cost of the assays are also given. The model is applicable to the amplified analytical determination of low levels of a metabolite or an enzyme activity, and its amplification capacity, together with the simplicity of determining kinetic parameters, enable it to be employed in enzyme immunoassays to increase the magnitude of the measured response.",1
"Valero, Edelmira, Varon, Ramon, Garcia-Carmona, Francisco",2
"Functional properties of the Drosophila melanogaster inositol 1,4,5-trisphosphate receptor mutants.",0
"The inositol (1,4,5)-trisphosphate receptor (InsP(3)R) is an intracellular calcium (Ca(2+)) release channel that plays a crucial role in cell signaling. In Drosophila melanogaster a single InsP(3)R gene (itpr) encodes a protein (DmInsP(3)R) that is approximately 60% conserved with mammalian InsP(3)Rs. A number of itpr mutant alleles have been identified in genetic screens and studied for their effect on development and physiology. However, the functional properties of wild-type or mutant DmInsP(3)Rs have never been described. Here we use the planar lipid bilayer reconstitution technique to describe single-channel properties of embryonic and adult head DmInsP(3)R splice variants. The three mutants chosen in this study reside in each of the three structural domains of the DmInsP(3)R-the amino-terminal ligand binding domain (ug3), the middle-coupling domain (wc703), and the channel-forming region (ka901). We discovered that 1), the major functional properties of DmInsP(3)R (conductance, gating, and sensitivity to InsP(3) and Ca(2+)) are remarkably conserved with the mammalian InsP(3)R1; 2), single-channel conductance of the adult head DmInsP(3)R isoform is 89 pS and the embryonic DmInsP(3)R isoform is 70 pS; 3), ug3 mutation affects sensitivity of the DmInsP(3)Rs to activation by InsP(3), but not their InsP(3)-binding properties; 4), wc703 channels have increased sensitivity to modulation by Ca(2+); and 5), homomeric ka901 channels are not functional. We correlated the results obtained in planar lipid bilayer experiments with measurements of InsP(3)-induced Ca(2+) fluxes in microsomes isolated from wild-type and heterozygous itpr mutants. Our study validates the use of D. melanogaster as an appropriate model for InsP(3)R structure-function studies and provides novel insights into the fundamental mechanisms of the InsP(3)R function.",1
"Srikanth, Sonal, Wang, Zhengnan, Tu, Huiping, Nair, Shalima, Mathew, M K, Hasan, Gaiti, Bezprozvanny, Ilya",2
Peptaibol zervamicin IIb structure and dynamics refinement from transhydrogen bond J couplings.,0
"Zervamicin IIB (Zrv-IIB) is a channel-forming peptaibol antibiotic of fungal origin. The measured transhydrogen bond (3h)J(NC') couplings in methanol solution heaving average value of -0.41 Hz indicate that the stability of the Zrv-IIB helix in this milieu is comparable to the stability of helices in globular proteins. The N-terminus of the peptide forms an alpha-helix, whereas 3(10)-helical hydrogen bonds stabilize the C-terminus. However, two weak transhydrogen bond peaks are observed in a long-range HNCO spectrum for HN Aib(12). Energy calculations using the Empirical Conformation Energy Program for Peptides (ECEPP)/2 force field and the implicit solvent model show that the middle of the peptide helix accommodates a bifurcated hydrogen bond that is simultaneously formed between HN Aib(12) and CO Leu(8) and CO Aib(9). Several lowered (3h)J(NC') on a polar face of the helix correlate with the conformational exchange process observed earlier and imply dynamic distortions of a hydrogen bond pattern with the predominant population of a properly folded helical structure. The refined structure of Zrv-IIB on the basis of the observed hydrogen bond pattern has a small ( approximately 20 degrees ) angle of helix bending that is virtually identical to the angle of bending in dodecylphosphocholine (DPC) micelles, indicating the stability of a hinge region in different environments. NMR parameters ((1)HN chemical shifts and transpeptide bond (1)J(NC') couplings) sensitive to hydrogen bonding along with the solvent accessible surface area of carbonyl oxygens indicate a large polar patch on the convex side of the helix formed by three exposed backbone carbonyls of Aib(7), Aib(9), and Hyp(10) and polar side chains of Hyp(10), Gln(11), and Hyp(13). The unique structural features, high helix stability and the enhanced polar patch, set apart Zrv-IIB from other peptaibols (for example, alamethicin) and possibly underlie its biological and physiological properties.",1
"Shenkarev, Z O, Balashova, T A, Yakimenko, Z A, Ovchinnikova, T V, Arseniev, A S",2
Cholera toxin assault on lipid monolayers containing ganglioside GM1.,0
"Many bacterial toxins bind to and gain entrance to target cells through specific interactions with membrane components. Using neutron reflectivity, we have characterized the structure of mixed DPPE:GM(1) lipid monolayers before and during the binding of cholera toxin (CTAB(5)) or its B-subunit (CTB(5)). Structural parameters such as the density and thickness of the lipid layer, extension of the GM(1) oligosaccharide headgroup, and orientation and position of the protein upon binding are reported. The density of the lipid layer was found to decrease slightly upon protein binding. However, the A-subunit of the whole toxin is clearly located below the B-pentameric ring, away from the monolayer, and does not penetrate into the lipid layer before enzymatic cleavage. Using Monte Carlo simulations, the observed monolayer expansion was found to be consistent with geometrical constraints imposed on DPPE by multivalent binding of GM(1) by the toxin. Our findings suggest that the mechanism of membrane translocation by the protein may be aided by alterations in lipid packing.",1
"Miller, C E, Majewski, J, Faller, R, Satija, S, Kuhl, T L",2
SP-B and SP-C alter diffusion in bilayers of pulmonary surfactant.,0
"The hydrophobic proteins SP-B and SP-C promote rapid adsorption of pulmonary surfactant to an air/water interface by an unknown mechanism. We tested the hypothesis that these proteins accelerate adsorption by disrupting the structure of the lipid bilayer, either by a generalized increase in fluidity or by a focal induction of interfacial boundaries within the bilayer. We used fluorescence recovery after photobleaching to measure diffusion of nitrobenzoxadiazolyl-dimyristoyl-phosphatidylethanolamine between 11 and 54 degrees C in multilayers containing the complete set of lipids and proteins in calf lung surfactant extract (CLSE), or the complete set of neutral and phospholipids without the proteins. Above 35 degrees C, Arrhenius plots of diffusion were parallel for CLSE and neutral and phospholipids, but shifted to lower values for CLSE, suggesting that the proteins rigidify the lipid bilayer rather than producing the proposed increase in membrane fluidity. The slopes of the Arrhenius plots for CLSE were steeper below 35 degrees C, suggesting that the proteins induce phase separation at that temperature. The mobile fraction fell below 27 degrees C, consistent with a percolation threshold of coexisting gel and liquid-crystal phases. The induction of lateral phase separation in CLSE, however, does not correlate with apparent changes in adsorption kinetics at this temperature. Our results suggest that SP-B and SP-C accelerate adsorption through a mechanism other than the disruption of surfactant bilayers, possibly by stabilizing a high-energy, highly curved adsorption intermediate.",1
"Schram, Vincent, Hall, Stephen B",2
Molecular dynamics analysis of structural factors influencing back door pi release in myosin.,0
"The back door has been proposed to be an exit pathway from the myosin active site for phosphate (P(i)) generated by adenosine 5'-triphosphate hydrolysis. We used molecular dynamics simulations to investigate the interaction of P(i) with the back door and the plausibility of P(i) release via this route. Molecular dynamics simulations were performed on the Dictyostelium motor domain with bound Mg.adenosine 5'-diphosphate (ADP) and P(i), modeled upon the Mg.ADP.BeF(x) and Mg.ADP.V(i) structures. Simulations revealed that the relaxation of ADP and free P(i) from their initial positions reduced the diameter of the back door via motions of switch 1 and switch 2 located in the upper and lower 50-kDa subdomains, respectively. In neither simulation could P(i) freely diffuse out the back door. Water molecules, however, could flux through the back door in the Mg.ADP.BeF(x)-based simulation but not in the Mg.ADP.V(i)-based simulation. In neither structure was water observed fluxing through the main (front door) entrance. These observations suggest that the ability of P(i) to leave via the back door is linked tightly to conformational changes between the upper and lower 50-kDa subdomains. The simulations offer structural explanations for (18)O-exchange with P(i) at the active site, and P(i) release being the rate-limiting step in the myosin adenosine 5'-triphosphatase.",1
"Lawson, J David, Pate, Edward, Rayment, Ivan, Yount, Ralph G",2
Interaction of horse heart and thermus thermophilus type c cytochromes with phospholipid vesicles and hydrophobic surfaces.,0
"The binding of horse heart cytochrome c (cyt-c) and Thermus thermophilus cytochrome c(552) (cyt-c(552)) to dioleoyl phosphatidylglycerol (DOPG) vesicles was investigated using Fourier transform infrared (FTIR) spectroscopy and turbidity measurements. FTIR spectra revealed that the tertiary structures of both cytochromes became more open when bound to DOPG vesicles, but this was more pronounced for cyt-c. Their secondary structures were unchanged. Turbidity measurements showed important differences in their behavior bound to the negatively charged DOPG vesicles. Both cytochromes caused the liposomes to aggregate and flocculate, but the ways they did so differed. For cyt-c, more than a monolayer was adsorbed onto the liposome surface prior to aggregation due to charge neutralization, whereas cyt c(552) caused aggregation at a protein/lipid ratio well below that required for charge neutralization. Therefore, although cyt-c may cause liposomes to aggregate by electrostatic interaction, cyt-c(552) does not act in this way. FTIR-attenuated total reflection spectroscopy (FTIR-ATR) revealed that cyt-c lost much of its secondary structure when bound to the hydrophobic surface of octadecyltrichlorosilane, whereas cyt-c(552) folds its domains into a beta-structure. This hydrophobic effect may be the key to the difference between the behaviors of the two cytochromes when bound to DOPG vesicles.",1
"Bernad, Sophie, Oellerich, Silke, Soulimane, Tewfik, Noinville, Sylvie, Baron, Marie-Helène, Paternostre, Maite, Lecomte, Sophie",2
Phosphate binding in the active site of alkaline phosphatase and the interactions of 2-nitrosoacetophenone with alkaline phosphatase-induced small structural changes.,0
"To monitor structural changes during the binding of Pi to the active site of mammalian alkaline phosphatase in water medium, reaction-induced infrared spectroscopy was used. The interaction of Pi with alkaline phosphatase was triggered by a photorelease of ATP from the inactive P(3)-[1-(2-nitrophenyl)]ethyl ester of ATP. After photorelease, ATP was sequentially hydrolyzed by alkaline phosphatase giving rise to adenosine and three Pi. Although a phosphodiesterase activity was detected prior the photorelease of ATP, it was possible to monitor the structural effects induced by Pi binding to alkaline phosphatase. Interactions of Pi with alkaline phosphatase were evidenced by weak infrared changes around 1631 and at 1639 cm(-1), suggesting a small distortion of peptide carbonyl backbone. This result indicates that the motion required for the formation of the enzyme-phosphate complex is minimal on the part of alkaline phosphatase, consistent with alkaline phosphatase being an almost perfect enzyme. Photoproduct 2-nitrosoacetophenone may bind to alkaline phosphatase in a site other than the active site of bovine intestinal alkaline phosphatase and than the uncompetitive binding site of L-Phe in bovine intestinal alkaline phosphatase, affecting one-two amino acid residues.",1
"Zhang, Le, Buchet, René, Azzar, Gérard",2
The intermediate filament architecture as determined by X-ray diffraction modeling of hard alpha-keratin.,0
"Despite investigation since the 1950s, the molecular architecture of intermediate filaments has not yet been fully elucidated. Reliable information about the longitudinal organization of the molecules within the filaments and about the lateral interfilament packing is now available, which is not the case for the transverse architecture. Interesting results were recently obtained from in vitro microscopy observations and cross-linking of keratin, desmin, and vimentin analyses. The structural features that emerge from these analyses could not be fully representative of the in vivo architecture because intermediate filaments are subject to polymorphism. To bring new light to the transverse intermediate filament architecture, we have analyzed the x-ray scattering equatorial profile of human hair. Its comparison with simulated profiles from atomic models of a real sequence has allowed results to be obtained that are representative of hard alpha-keratin intermediate filaments under in vivo conditions. In short, the alpha-helical coiled coils, which are characteristic of the central rod of intermediate filament dimers, are straight and not supercoiled into oligomers; the radial density across the intermediate filament section is fairly uniform; the coiled coils are probably assembled into tetrameric oligomers, and finally the oligomer positions and orientations are not regularly ordered. These features are discussed in terms of filament self-assembling and structural variability.",1
"Er Rafik, Meriem, Doucet, Jean, Briki, Fatma",2
Competing hydrophobic and screened-coulomb interactions in hepatitis B virus capsid assembly.,0
"Recent experiments show that, in the range from approximately 15 to 45 degrees C, an increase in the temperature promotes the spontaneous assembly into capsids of the Escherichia coli-expressed coat proteins of hepatitis B virus. Within that temperature interval, an increase in ionic strength up to five times that of standard physiological conditions also acts to promote capsid assembly. To explain both observations we propose an interaction of mean force between the protein subunits that is the sum of an attractive hydrophobic interaction, driving the self-assembly, and a repulsive electrostatic interaction, opposing the self-assembly. We find that the binding strength of the capsid subunits increases with temperature virtually independently of the ionic strength, and that, at fixed temperature, the binding strength increases with the square root of ionic strength. Both predictions are in quantitative agreement with experiment. We point out the similarities of capsid assembly in general and the micellization of surfactants. Finally we make plausible that electrostatic repulsion between the native core subunits of a large class of virus suppresses the formation in vivo of empty virus capsids, that is, without the presence of the charge-neutralizing nucleic acid.",1
"Kegel, Willem K, Schoot Pv, Paul van der",2
Studies of chi(2)/chi(3) tensors in submicron-scaled bio-tissues by polarization harmonics optical microscopy.,0
"Optical second- and third-harmonic generations have attracted a lot of attention in the biomedical imaging research field recently due to their intrinsic sectioning ability and noninvasiveness. Combined with near-infrared excitation sources, their deep-penetration ability makes these imaging modalities suitable for tissue characterization. In this article, we demonstrate a polarization harmonics optical microscopy, or P-HOM, to study the nonlinear optical anisotropy of the nanometer-scaled myosin and actin filaments inside myofibrils. By using tight focusing we can avoid the phase-matching condition due to micron-scaled, high-order structures in skeletal muscle fibers, and obtain the submicron-scaled polarization dependencies of second/third-harmonic generation intensities on the inclination angle between the long axes of the filaments and the polarization direction of the linear polarized fundamental excitation laser light. From these dependencies, detailed information on the tensor elements of the second/third-order nonlinear susceptibilities contributed from the myosin/actin filaments inside myofibrils can thus be analyzed and obtained, reflecting the detailed arrangements and structures of the constructing biomolecules. By acquiring a whole, nonlinearly sectioned image with a submicron spatial resolution, we can also compare the polarization dependency and calculate the nonlinear susceptibilities over a large area of the tissue at the same time-which not only provides statistical information but will be especially useful with complex specimen geometry.",1
"Chu, Shi-Wei, Chen, Szu-Yu, Chern, Gia-Wei, Tsai, Tsung-Han, Chen, Yung-Chih, Lin, Bai-Ling, Sun, Chi-Kuang",2
Photobleaching-corrected FRET efficiency imaging of live cells.,0
"Fluorescent resonance energy transfer (FRET) imaging techniques can be used to visualize protein-protein interactions in real-time with subcellular resolution. Imaging of sensitized fluorescence of the acceptor, elicited during excitation of the donor, is becoming the most popular method for live FRET (3-cube imaging) because it is fast, nondestructive, and applicable to existing widefield or confocal microscopes. Most sensitized emission-based FRET indices respond nonlinearly to changes in the degree of molecular interaction and depend on the optical parameters of the imaging system. This makes it difficult to evaluate and compare FRET imaging data between laboratories. Furthermore, photobleaching poses a problem for FRET imaging in timelapse experiments and three-dimensional reconstructions. We present a 3-cube FRET imaging method, E-FRET, which overcomes both of these obstacles. E-FRET bridges the gap between the donor recovery after acceptor photobleaching technique (which allows absolute measurements of FRET efficiency, E, but is not suitable for living cells), and the sensitized-emission FRET indices (which reflect FRET in living cells but lack the quantitation and clarity of E). With E-FRET, we visualize FRET in terms of true FRET efficiency images (E), which correlate linearly with the degree of donor interaction. We have defined procedures to incorporate photobleaching correction into E-FRET imaging. We demonstrate the benefits of E-FRET with photobleaching correction for timelapse and three-dimensional imaging of protein-protein interactions in the immunological synapse in living T-cells.",1
"Zal, Tomasz, Gascoigne, Nicholas R J",2
Information bounds and optimal analysis of dynamic single molecule measurements.,0
"Time-resolved single molecule fluorescence measurements may be used to probe the conformational dynamics of biological macromolecules. The best time resolution in such techniques will only be achieved by measuring the arrival times of individual photons at the detector. A general approach to the estimation of molecular parameters based on individual photon arrival times is presented. The amount of information present in a data set is quantified by the Fisher information, thereby providing a guide to deriving the basic equations relating measurement uncertainties and time resolution. Based on these information-theoretical considerations, a data analysis algorithm is presented that details the optimal analysis of single-molecule data. This method natively accounts and corrects for background photons and cross talk, and can scale to an arbitrary number of channels. By construction, and with corroboration from computer simulations, we show that this algorithm reaches the theoretical limit, extracting the maximal information out of the data. The bias inherent in the algorithm is considered and its implications for experimental design are discussed. The ideas underlying this approach are general and are expected to be applicable to any information-limited measurement.",1
"Watkins, Lucas P, Yang, Haw",2
The fast tumble signal in bacterial chemotaxis.,0
"We have analyzed repellent signal processing in Escherichia coli by flash photorelease of leucine from photolabile precursors. We found that 1). response amplitudes of free-swimming cell populations increased with leucine jump concentration, with an apparent Hill coefficient of 1.3 and a half-maximal dose of 14.4 microM; 2). at a 0-0.5 mM leucine concentration jump sufficient to obtain a saturation motile response, the swimming cell response time of approximately 0.05 s was several-fold more rapid than the motor response time of 0.39 +/- 0.18 s measured by following the rotation of cells tethered by a single flagellum to quartz coverslips; and 3). the motor response time of individual cells was correlated with rotation bias but not cell size. These results provide information on amplification, rate-limiting step, and flagellar bundle mechanics during repellent signal processing. The difference between the half-maximal dose for the excitation response and the corresponding value reported for adaptation provides an estimate of the increase in the rate of formation of CheYP, the phosphorylated form of the signal protein CheY. The estimated increase gives a lower limit receptor kinase coupling ratio of 6.0. The magnitude and form of the motor response time distribution argue for it being determined by the poststimulus switching probability rather than CheYP turnover, diffusion, or binding. The temporal difference between the tethered and swimming cell response times to repellents can be quantitatively accounted for and suggests that one flagellum is sufficient to cause a measurable change of direction in which a bacterium swims.",1
"Khan, Shahid, Jain, Sanjay, Reid, Gordon P, Trentham, David R",2
"Beta-1 integrin-mediated adhesion may be initiated by multiple incomplete bonds, thus accounting for the functional importance of receptor clustering.",0
"The regulation of cell integrin receptors involves modulation of membrane expression, shift between different affinity states, and topographical redistribution on the cell membrane. Here we attempted to assess quantitatively the functional importance of receptor clustering. We studied beta-1 integrin-mediated attachment of THP-1 cells to fibronectin-coated surfaces under low shear flow. Cells displayed multiple binding events with a half-life of the order of 1 s. The duration of binding events after the first second after arrest was quantitatively accounted for by a model assuming the existence of a short-time intermediate binding state with 3.6 s(-1) dissociation rate and 1.3 s(-1) transition frequency toward a more stable state. Cell binding to surfaces coated with lower fibronectin densities was concluded to be mediated by single molecular interactions, whereas multiple bonds were formed <1 s after contact with higher fibronectin surface densities. Cell treatment with microfilament inhibitors or a neutral antiintegrin antibody decreased bond number without changing aforementioned kinetic parameters whereas a function enhancing antibody increased the rate of bond formation and/or the lifetime of intermediate state. Receptor aggregation was induced by treating cells with neutral antiintegrin antibody and antiimmunoglobulin antibodies. A semiquantitative confocal microscopy study suggested that this treatment increased between 40% and 100% the average number of integrin receptors located in a volume of approximately 0.045 microm(3) surrounding each integrin. This aggregation induced up to 2.7-fold increase of the average number of bonds. Flow cytometric analysis of fluorescent ligand binding showed that THP-1 cells displayed low-affinity beta-1 integrins with a dissociation constant in the micromolar range. It is concluded that the initial step of cell adhesion was mediated by multiple incomplete bonds rather than a single equilibrium-state ligand receptor association. This interpretation accounts for the functional importance of integrin clustering.",1
"Vitte, Joana, Benoliel, Anne-Marie, Eymeric, Philippe, Bongrand, Pierre, Pierres, Anne",2
Bilayer conformation of fusion peptide of influenza virus hemagglutinin: a molecular dynamics simulation study.,0
"Unraveling the conformation of membrane-bound viral fusion peptides is essential for understanding how those peptides destabilize the bilayer topology of lipids that is important for virus-cell membrane fusion. Here, molecular dynamics (MD) simulations were performed to investigate the conformation of the 20 amino acids long fusion peptide of influenza hemagglutinin of strain X31 bound to a dimyristoyl phosphatidylcholine (DMPC) bilayer. The simulations revealed that the peptide adopts a kinked conformation, in agreement with the NMR structures of a related peptide in detergent micelles. The peptide is located at the amphipathic interface between the headgroups and hydrocarbon chains of the lipid by an energetically favorable arrangement: The hydrophobic side chains of the peptides are embedded into the hydrophobic region and the hydrophilic side chains are in the headgroup region. The N-terminus of the peptide is localized close to the amphipathic interface. The molecular dynamics simulations also revealed that the peptide affects the surrounding bilayer structure. The average hydrophobic thickness of the lipid phase close to the N-terminus is reduced in comparison with the average hydrophobic thickness of a pure dimyristoyl phosphatidylcholine bilayer.",1
"Huang, Qiang, Chen, Cheng-Lung, Herrmann, Andreas",2
Molecular dynamics simulations of the lipid bilayer edge.,0
"Phospholipid bilayers have been intensively studied by molecular dynamics (MD) simulation in recent years. The properties of bilayer edges are important in determining the structure and stability of pores formed in vesicles and biomembranes. In this work, we use molecular dynamics simulation to investigate the structure, dynamics, and line tension of the edges of bilayer ribbons composed of pure dimyristoylphosphatidylcholine (DMPC) or palmitoyl-oleoylphosphatidylethanolamine (POPE). As expected, we observe a significant reorganization of lipids at and near the edges. The treatment of electrostatic effects is shown to have a qualitative impact on the structure and stability of the edge, and significant differences are observed in the dynamics and structure of edges formed by DMPC and palmitoyl-oleoylphosphatidylethanolamine. From the pressure anisotropy in the simulation box, we calculate a line tension of approximately 10-30 pN for the DMPC edge, in qualitative agreement with experimental estimates for similar lipids.",1
"Jiang, Frank Y, Bouret, Yann, Kindt, James T",2
Three roads to islet bursting: emergent oscillations in coupled phantom bursters.,0
"Glucose-induced membrane potential and Ca(2+) oscillations in isolated pancreatic beta-cells occur over a wide range of frequencies, from >6/min (fast) to <1/min (slow). However, cells within intact islets generally oscillate with periods of 10-60 s (medium). The phantom bursting concept addresses how beta-cells can generate such a wide range of frequencies. Here, we explore an updated phantom bursting model to determine how heterogeneity in a single parameter can explain both the broad frequency range observed in single cells and the rarity of medium oscillations. We then incorporate the single-cell model into an islet model with parameter heterogeneity. We show that strongly coupled islets must be composed of predominantly medium oscillating single cells or a mixture of fast and slow cells to robustly produce medium oscillations. Surprisingly, we find that this constraint does not hold for moderate coupling, and that robustly medium oscillating islets can arise from populations of single cells that are essentially all slow or all fast. Thus, with coupled phantom bursters, medium oscillating islets can be constructed out of cells that are either all fast, all slow, or a combination of the two.",1
"Zimliki, Charles L, Mears, David, Sherman, Arthur",2
On the theory of noncovalent binding.,0
"It is widely accepted that the binding constant of a receptor and ligand can be written as a two-body integral involving the interaction energy of the receptor and the ligand. Interestingly, however, three different theories of binding in the literature dictate three distinct integrals. The present study uses theory, as well as simulations of binding experiments, to test the validity of the three integrals. When binding is measured by a signal that detects the ligand in the binding site, the most accurate results are obtained by an integral of the Boltzmann factor, where the bound complex is defined in terms of an exclusive binding region. A novel prediction of this approach, that expanding a ligand can increase its binding constant, is borne out by the simulations. The simulations also show that abnormal binding isotherms can be obtained when the region over which the signal is detected deviates markedly from the exclusion zone. Interestingly, the binding constant measured by equilibrium dialysis, rather than by monitoring a localized signal, can yield a binding constant that differs from that obtained from a signal measurement, and that is matched best by the integral of the Mayer factor.",1
"Mihailescu, Mihail, Gilson, Michael K",2
Effects of ryanoids on spontaneous and depolarization-evoked calcium release events in frog muscle.,0
"The effects of ryanoids on calcium sparks and transients were studied in voltage-clamped cut frog muscle fibers with a laser scanning confocal microscope. For each ryanoid employed, several sequential effects were observed, including: a), transient increases in spontaneous spark frequency; b), conversions of sparks to long-lasting steady glows; and c), occasional interruptions of the glows. The ratio of the amplitude of the glow induced by a ryanoid to that of the precursory spark followed the order: ryanodol > ryanodine > C(10)-O(eq)-glycyl-ryanodine > C(10)-O(eq)-beta-alanyl-ryanodol. This sequence of glow amplitudes parallels that of the subconductances induced by these ryanoids in single-channel studies, suggesting that the glows reflect Ca(2+) fluxes through semiopen calcium release channels. Ryanoids also abolished depolarization-evoked sparks elicited with small pulses, and transformed the calcium release during depolarization to a uniform nonsparking fluorescence signal. The ratio of this signal, averaged spatially, to that of the control followed the order: ryanodol < ryanodine < C(10)-O(eq)-glycyl-ryanodine < C(10)-O(eq)-beta-alanyl-ryanodol, implying an inverse relationship with the amplitudes of ryanoid-induced glows. The observation that depolarization-evoked calcium release can occur after ryanoid suppression of calcium sparks suggests the possibility of a new strategic approach for treating skeletal muscle diseases resulting from leaky calcium release channels.",1
"Hui, Chiu Shuen, Besch, Henry R, Bidasee, Keshore R",2
AFM visualization of mobile influenza A M2 molecules in planar bilayers.,0
"We report the observation of influenza A M2 (M2) incorporated in a dipalmitoylphosphatidylcholine (DPPC) supported planar bilayer on mica, formed by use of a modified vesicle fusion method from proteoliposomes and visualized with contact mode atomic force microscopy. Incubation of proteoliposomes in a hyperosmotic solution and increased DPPC/M2 weight ratios improved supported planar bilayer formation by M2/DPPC proteoliposomes. M2's extra-bilayer domains were observed as particles estimated to protrude 1-1.5 nm above the bilayer surface and <4 nm in diameter. Particle density was 5-18% of the nominal tetramer density. Movement of observable M2 particles was independent of the probe tip. The mean lateral diffusion coefficient (D) of M2 was 4.4 +/- 1.0 x 10(-14) cm(2)/s. Eighty-two percent of observable particles were mobile on the observable timescale (D > 6 x 10(-15) cm(2)/s). Protein-protein interactions were also observed directly.",1
"Hughes, Travis, Strongin, Bradley, Gao, Fei Philip, Vijayvergiya, Viksita, Busath, David D, Davis, Robert C",2
Properties of a self-assembled phospholipid membrane supported on lipobeads.,0
"The overall objective of our work was to make a hydrogel-supported phospholipid bilayer that models a cytoskeleton-supported cell membrane and provides a platform for studying membrane biology. Previously, we demonstrated that a pre-Lipobead, consisting of phospholipids covalently attached to the surface of a hydrogel, could give rise to a Lipobead when incubated with liposomes because the attached phospholipids promote self-assembly of a phospholipid membrane on the pre-Lipobead. We now report the properties of that Lipobead membrane. The lateral diffusion coefficient of fluorescently labeled phosphatidylcholine analogs in the membrane was measured by fluorescence recovery after photobleaching and was found to decrease as the surface anchor density and hydrogel crosslinking density increased. Results from the quenching of phosphatidylcholine analogs suggest that the phospholipid membrane of the Lipobead was composed mostly of a semipermeable lipid bilayer. However, the diffusional barrier properties of the Lipobead membrane were demonstrated by the entrapment of 1.5-3.0 K dextran molecules in the hydrogel core after liposome fusion. This hydrogel-supported bilayer membrane preparation shows promise as a new platform for studying membrane biology and for high throughput drug screening.",1
"Ng, Charlene C, Cheng, Yu-Ling, Pennefather, Peter S",2
A molecular view on the interaction of the trojan peptide penetratin with the polar interface of lipid bilayers.,0
"Penetratin belongs to the family of Trojan peptides that effectively enter cells and therefore can be used as cargoes for agents that are unable to penetrate the cell membrane. We applied polarized infrared spectroscopy in combination with the attenuated total reflection technique to extract information before penetratin binding to lipid membranes with molecular resolution. The amide I band of penetratin in the presence of zwitterionic dimyristoylphosphatidylcholine and of anionic lipid membranes composed of dioleoylphosphatidylcholine and dioleoylphosphatidylglycerol shows the characteristics of an antiparallel beta-sheet with a small fraction of turns. Both signatures have been interpreted in terms of a hairpin conformation. The infrared linear dichroism of the amide I band indicates that the peptide chain orients in an oblique fashion whereas the plane of the sheet aligns virtually parallel with respect to the membrane surface. The weak effect of the peptide on dimyristoylphosphatidylcholine gives indication of its superficial binding where the charged lysine and arginine side chains form H-bonds to the phosphate oxygens of the surrounding lipids. The determinants for internalization of penetratin appear to be a peptide sequence with a distribution of positively charged residues along a beta-sheet conformation, which enables the anchoring of the peptide in the polar part of the membranes and the effective compensation of anionic lipid charges.",1
"Binder, Hans, Lindblom, Göran",2
The JAK-STAT signaling network in the human B-cell: an extreme signaling pathway analysis.,0
"Large-scale models of signaling networks are beginning to be reconstructed and corresponding analysis frameworks are being developed. Herein, a reconstruction of the JAK-STAT signaling system in the human B-cell is described and a scalable framework for its network analysis is presented. This approach is called extreme signaling pathway analysis and involves the description of network properties with systemically independent basis vectors called extreme pathways. From the extreme signaling pathways, emergent systems properties of the JAK-STAT signaling network have been characterized, including 1), a mathematical definition of network crosstalk; 2), an analysis of redundancy in signaling inputs and outputs; 3), a study of reaction participation in the network; and 4), a delineation of 85 correlated reaction sets, or systemic signaling modules. This study is the first such analysis of an actual biological signaling system. Extreme signaling pathway analysis is a topologically based approach and assumes a balanced use of the signaling network. As large-scale reconstructions of signaling networks emerge, such scalable analyses will lead to a description of the fundamental systems properties of signal transduction networks.",1
"Papin, Jason A, Palsson, Bernhard O",2
Conformation of peptides in lipid membranes studied by x-ray grazing incidence scattering.,0
"Although the antimicrobial, fungal peptide alamethicin has been extensively studied, the conformation of the peptide and the interaction with lipid bilayers as well as the mechanism of channel gating are still not completely clear. As opposed to studies of the crystalline state, the polypeptide structures in the environment of fluid bilayers are difficult to probe. We have investigated the conformation of alamethicin in highly aligned stacks of model lipid membranes by synchrotron-based x-ray scattering. The (wide-angle) scattering distribution has been measured by reciprocal space mappings. A pronounced scattering signal is observed in samples of high molar peptide/lipid ratio which is distinctly different from the scattering distribution of an ideal helix in the transmembrane state. Beyond simple models of ideal helices, the data is analyzed in terms of models based on atomic coordinates from the Brookhaven Protein Data Bank, as well as from published molecular dynamics simulations. The results can be explained by assuming a wide distribution of helix tilt angles with respect to the membrane normal and a partial insertion of the N-terminus into the membrane.",1
"Spaar, Alexander, Münster, Christian, Salditt, Tim",2
Evolution of a rippled membrane during phospholipase A2 hydrolysis studied by time-resolved AFM.,0
"The sensitivity of phospholipase A(2) (PLA(2)) for lipid membrane curvature is explored by monitoring, through time-resolved atomic force microscopy, the hydrolysis of supported double bilayers in the ripple phase. The ripple phase presents a corrugated morphology. PLA(2) is shown to have higher activity toward the ripple phase compared to the gel phase in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes, indicating its preference for this highly curved membrane morphology. Hydrolysis of the stable and metastable ripple structures is monitored for equimolar DMPC/1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)-supported double bilayers. As shown by high-performance liquid chromatography results, DSPC is resistant to hydrolysis at this temperature, resulting in a more gradual hydrolysis of the surface that leads to a change in membrane morphology without loss of membrane integrity. This is reflected in an increase in ripple spacing, followed by a sudden flattening of the lipid membrane during hydrolysis. Hydrolysis of the ripple phase results in anisotropic holes running parallel to the ripples, suggesting that the ripple phase has strip regions of higher sensitivity to enzymatic attack. Bulk high-performance liquid chromatography measurements indicate that PLA(2) preferentially hydrolyzes DMPC in the DMPC/DSPC ripples. We suggest that this leads to the formation of a flat gel-phase lipid membrane due to enrichment in DSPC. The results point to the ability of PLA(2) for inducing a compositional phase transition in multicomponent membranes through preferential hydrolysis while preserving membrane integrity.",1
"Leidy, Chad, Mouritsen, Ole G, Jørgensen, Kent, Peters, Günther H",2
Freely diffusing single hairpin ribozymes provide insights into the role of secondary structure and partially folded states in RNA folding.,0
"Single-molecule fluorescence resonance energy transfer studies of freely diffusing hairpin ribozymes with different combinations of helical junction and loop elements reveal striking differences in their folding behavior. We examined a series of six different ribozymes consisting of two-, three- and four-way junction variants, as well as corresponding constructs with one of the two loops removed. Our results highlight the varying contributions of preformed secondary structure elements to tertiary folding of the hairpin ribozyme. Of the three helical junction variants studied, the four-way junction strongly favored folding to a docked conformation of the two loops, required for catalytic activity. Moreover, the four-way junction was uniquely able to fold to a similar compact structure even in the absence of specific loop-loop docking interactions. A key feature of the data is the observation of broadening/tailing in the fluorescence resonance energy transfer histogram peak for a single-loop mutant of the four-way junction at higher Mg(2+) concentrations, not observed for any of the other single-loop variants. This feature is consistent with interconversion between compact and extended structures, which we estimate takes place on the 100-micros timescale using a simple model for the peak shape. This unique ability of the four-way junction ribozyme to populate an undocked conformation with native-like structure (a quasi-docked state) likely contributes to its greater tertiary structure stability, with the quasi-docked state acting as an intermediate and facilitating the subsequent formation of the specific hydrogen bonding network during docking of the two loops. The inability of two- and three-way junction ribozymes to fully populate a docked conformation reveals the importance of correct helical junction geometry as well as loop elements for effective ribozyme folding.",1
"Pljevaljcić, Goran, Millar, David P, Deniz, Ashok A",2
The hydrodynamics of DNA electrophoretic stretch and relaxation in a polymer solution.,0
"Theories of DNA electrophoretic separations generally treat the DNA as a free draining polymer moving in an electric field at a rate that depends on the effective charge density of the molecule. Separations can occur in sieving media ranging from ultradilute polymer solutions to tightly cross-linked gels. It has recently been shown that DNA is not free-draining when both electric and nonelectric forces simultaneously act on the molecule, as occurs when DNA collides with a polymer during electrophoretic separations. Here we show that a semidilute polymer solution screens the hydrodynamic interaction that results from the application of these forces. Fluorescently labeled DNA tethered at one end in a semidilute solution of hydroxyl-ethyl cellulose stretch more in an electric field than they stretch in free solution, and approach free-draining behavior. The steady stretching behavior is predicted without adjustable parameters by a theory developed by Stigter using a hydrodynamic screening length found from effective medium theory. Data on the relaxation of stretched molecules after the electric field is removed agree with the Rouse model prediction, which neglects hydrodynamic interactions. The slowest relaxation time constant, tau(R), scales with chain length as tau(R) approximately L(1.9+/-0.17) when analyzed by the data collapse method, and as tau(R) approximately L(2.17+/-0.17) when analyzed by multiexponential fit.",1
"Ferree, Sean, Blanch, Harvey W",2
Crystal structures of two cyanobacterial response regulators in apo- and phosphorylated form reveal a novel dimerization motif of phytochrome-associated response regulators.,0
"The structures of two response regulators (RRs) from the cyanobacterium Calothrix PCC7601, RcpA and RcpB, were solved to 1.9- and 1.75-A resolution, respectively. RcpA was found in phosphorylated and RcpB in nonphosphorylated form. Both RRs are members of phytochrome-associated, light-sensing two-component signal transduction pathways, based on histidine kinase-mediated receptor autophosphorylation and phosphorelay to a RR. Despite the overall folding similarity to CheY-type RRs ((beta/alpha)(5)-motif), RcpA and RcpB form homodimers, irrespective of their phosphorylation state, giving insight into a signal transduction putatively different from that of other known RRs. Dimerization is accomplished by a C-terminal extension of the RR polypeptide chain, and the surface formed by H4, beta 5, and H5, which constitute a hydrophobic contact area with distinct interactions between residues of either subunit. Sequence alignments reveal that the identified dimerization motif is archetypal for phytochrome-associated RRs, making them a novel subgroup of CheY-type RRs. The protein structures of RcpA and RcpB are compared to the recently presented protein structure of Rcp1 from Synechocystis.",1
"Benda, C, Scheufler, C, Tandeau de Marsac, N, Gärtner, W",2
A quantitative XANES analysis of the calcium high-affinity binding site of the purple membrane.,0
"In this article we report x-ray absorption measurements of Ca(2+)-substituted bacteriorhodopsin. We present a detailed study of the absorption spectrum close to the absorption edge that is very sensitive to the site geometry. We combined ab initio calculations of the x-ray absorption cross section based on a full multiple scattering approach, with a best fit of the experimental data performed by changing the cluster geometry. The Ca(2+)-bacteriorhodopsin environment is composed of six oxygen atoms showing a distorted orthorhombic symmetry, whereas the Ca(2+) in water solution has a regular octahydrated first sphere of coordination. Our results are in good agreement with previous molecular models suggesting that the high-affinity cationic site could be in the proximity of the retinal pocket. Our results provide strong direct evidence of the specific binding site of the metal cation in bacteriorhodopsin.",1
"Sepulcre, Francesc, Proietti, M Grazia, Benfatto, Maurizio, Della Longa, Stefano, García, Joaquin, Padrós, Esteve",2
The density and refractive index of adsorbing protein layers.,0
"The structure of the adsorbing layers of native and denatured proteins (fibrinogen, gamma-immunoglobulin, albumin, and lysozyme) was studied on hydrophilic TiO(2) and hydrophobic Teflon-AF surfaces using the quartz crystal microbalance with dissipation and optical waveguide lightmode spectroscopy techniques. The density and the refractive index of the adsorbing protein layers could be determined from the complementary information provided by the two in situ instruments. The observed density and refractive index changes during the protein-adsorption process indicated the presence of conformational changes (e.g., partial unfolding) in general, especially upon contact with the hydrophobic surface. The structure of the formed layers was found to depend on the size of the proteins and on the experimental conditions. On the TiO(2) surface smaller proteins formed a denser layer than larger ones and the layer of unfolded proteins was less dense than that adsorbed from the native conformation. The hydrophobic surface induced denaturation and resulted in the formation of thin compact protein films of albumin and lysozyme. A linear correlation was found between the quartz crystal microbalance measured dissipation factor and the total water content of the layer, suggesting the existence of a dissipative process that is related to the solvent molecules present inside the adsorbed protein layer. Our measurements indicated that water and solvent molecules not only influence the 3D structure of proteins in solution but also play a crucial role in their adsorption onto surfaces.",1
"Vörös, Janos",2
A new method of identifying the site of tyrosyl radicals in proteins.,0
"Protein-bound tyrosyl radicals catalyze many important enzymatic reactions. They can also initiate oxidative damage to cells. Here we report a new method of computer simulation of tyrosyl radical electron paramagnetic resonance spectra. The method enables the determination of the rotational conformation of the phenoxyl ring in a radical with unprecedented accuracy (approximately 2 degrees ). When coupled with a new online database, all tyrosine residues in a protein can be screened for that particular conformation. For the first time we show relationships between the spin density on atom C1 (rho(C1)) and the principal g-factors measured by electron paramagnetic resonance spectroscopy (rho(C1) on g(x) is shown to be linear). The new method enables the accurate determination of rho(C1) in all known tyrosyl radicals, evaluates the likelihood of a hydrogen bond, and determines the possibility of a rho(C1) distribution in the radicals. This information, together with the accurately determined rotational conformation, is frequently sufficient to allow for an unambiguous identification of the site of radical formation. The possibility of a similar relationship between rho(C) and g(x) in other radicals, e.g., tryptophanyl, is discussed.",1
"Svistunenko, Dimitri A, Cooper, Chris E",2
A nanosensor for transmembrane capture and identification of single nucleic Acid molecules.,0
"We have engineered a nanosensor for sequence-specific detection of single nucleic acid molecules across a lipid bilayer. The sensor is composed of a protein channel nanopore (alpha-hemolysin) housing a DNA probe with an avidin anchor at the 5' end and a nucleotide sequence designed to noncovalently bind a specific single-stranded oligonucleotide at the 3' end. The 3' end of the DNA probe is driven to the opposite side of the pore by an applied electric potential, where it can specifically bind to oligonucleotides. Reversal of the applied potential withdraws the probe from the pore, dissociating it from a bound oligonucleotide. The time required for dissociation of the probe-oligonucleotide duplex under this force yields identifying characteristics of the oligonucleotide. We demonstrate transmembrane detection of individual oligonucleotides, discriminate between molecules differing by a single nucleotide, and investigate the relationship between dissociation time and hybridization energy of the probe and analyte molecules. The detection method presented in this article is a candidate for in vivo single-molecule detection and, through parallelization in a synthetic device, for genotyping and global transcription profiling from small samples.",1
"Nakane, Jonathan, Wiggin, Matthew, Marziali, Andre",2
Placing single-molecule T4 lysozyme enzymes on a bacterial cell surface: toward probing single-molecule enzymatic reaction in living cells.,0
"The T4 lysozyme enzymatic hydrolyzation reaction of bacterial cell walls is an important biological process, and single-molecule enzymatic reaction dynamics have been studied under physiological condition using purified Escherichia coli cell walls as substrates. Here, we report progress toward characterizing the T4 lysozyme enzymatic reaction on a living bacterial cell wall using a combined single-molecule placement and spectroscopy. Placing a dye-labeled single T4 lysozyme molecule on a targeted bacterial cell wall by using a hydrodynamic microinjection approach, we monitored single-molecule rotational motions during binding, attachment to, and dissociation from the cell wall by tracing single-molecule fluorescence intensity time trajectories and polarization. The single-molecule attachment duration of the T4 lysozyme to the cell wall during enzymatic reactions was typically shorter than the photobleaching time under physiological conditions. Applying single-molecule fluorescence polarization measurements to characterize the binding and motions of the T4 lysozyme molecules, we observed that the motions of wild-type and mutant T4 lysozyme proteins are essentially the same whether under an enzymatic reaction or not. The changing of the fluorescence polarization suggests that the motions of the T4 lysozyme are associated with orientational rotations. This observation also suggests that the T4 lysozyme binding-unbinding motions on cell walls involve a complex mechanism beyond a single-step first-order rate process.",1
"Hu, Dehong, Lu, H Peter",2
Controlled pseudopod extension of human neutrophils stimulated with different chemoattractants.,0
"The formation of pseudopods and lamellae after ligation of chemoattractant sensitive G-protein coupled receptors (GPCRs) is essential for chemotaxis. Here, pseudopod extension was stimulated with chemoattractant delivered from a micropipet. The chemoattractant diffusion and convection mass transport were considered, and it is shown that when the delivery of chemoattractant was limited by diffusion there was a strong chemoattractant gradient along the cell surface. The diffusion-limited delivery of chemoattractant from a micropipet allowed for maintaining an almost constant chemoattractant concentration at the leading edge of single pseudopods during their growth. In these conditions, the rate of pseudopod extension was dependent on the concentration of chemoattractant in the pipet delivering chemoattractant. The pseudopod extension induced using micropipets was oscillatory even in the presence of a constant delivery of chemoattractant. This oscillatory pseudopod extension was controlled by activated RhoA and its downstream effector kinase ROCK and was abolished after the inhibition of RhoA activation with Clostridium botulinium C3 exoenzyme (C3) or the blocking of ROCK activation with Y-27632. The ability of the micropipet assay to establish a well-defined chemoattractant distribution around the activated cell over a wide range of molecular weights of the used chemoattractants allowed for comparison of the effect of chemoattractant stimulation on the dynamics of pseudopod growth. Pseudopod growth was stimulated using N-formylated peptide (N-formyl-methionyl-leucyl-phenylalanine (fMLP)), platelet activating factor (PAF), leukotriene B4 (LTB(4)), C5a anaphylotoxin (C5a), and interleukin-8 (IL-8), which represent the typical ligands for G-protein coupled chemotactic receptors. The dependence of the rate of pseudopod extension on the concentration of these chemoattractants and their equimolar mixture was measured and shown to be similar for all chemoattractants. The inhibition of the activity of phosphoinositide-3 kinase (PI3K) with wortmannin showed that 72%-80% of the rate of pseudopod extension induced with N-formyl-methionyl-leucyl-phenylalanine, platelet activating factor, and leukotriene B4 was phosphoinositide-3 kinase-dependent, in contrast to 55% of the rate of pseudopod extension induced with interleukin-8. The dependence of the rate of pseudopod extension on the concentration of individual chemoattractants and their equimolar mixture suggests that there is a common rate-limiting mechanism for the polymerization of cytoskeletal F-actin in the pseudopod region induced by G-protein coupled chemoattractant receptors.",1
"Zhelev, Doncho V, Alteraifi, Abdullatif M, Chodniewicz, David",2
Analysis of functional coupling: mitochondrial creatine kinase and adenine nucleotide translocase.,0
"The mechanism of functional coupling between mitochondrial creatine kinase (MiCK) and adenine nucleotide translocase (ANT) in isolated heart mitochondria is analyzed. Two alternative mechanisms are studied: 1), dynamic compartmentation of ATP and ADP, which assumes the differences in concentrations of the substrates between intermembrane space and surrounding solution due to some diffusion restriction and 2), direct transfer of the substrates between MiCK and ANT. The mathematical models based on these possible mechanisms were composed and simulation results were compared with the available experimental data. The first model, based on a dynamic compartmentation mechanism, was not sufficient to reproduce the measured values of apparent dissociation constants of MiCK reaction coupled to oxidative phosphorylation. The second model, which assumes the direct transfer of substrates between MiCK and ANT, is shown to be in good agreement with experiments--i.e., the second model reproduced the measured constants and the estimated ADP flux, entering mitochondria after the MiCK reaction. This model is thermodynamically consistent, utilizing the free energy profiles of reactions. The analysis revealed the minimal changes in the free energy profile of the MiCK-ANT interaction required to reproduce the experimental data. A possible free energy profile of the coupled MiCK-ANT system is presented.",1
"Vendelin, Marko, Lemba, Maris, Saks, Valdur A",2
"The influence of short-chain alcohols on interfacial tension, mechanical properties, area/molecule, and permeability of fluid lipid bilayers.",0
"We used micropipette aspiration to directly measure the area compressibility modulus, bending modulus, lysis tension, lysis strain, and area expansion of fluid phase 1-stearoyl, 2-oleoyl phosphatidylcholine (SOPC) lipid bilayers exposed to aqueous solutions of short-chain alcohols at alcohol concentrations ranging from 0.1 to 9.8 M. The order of effectiveness in decreasing mechanical properties and increasing area per molecule was butanol>propanol>ethanol>methanol, although the lysis strain was invariant to alcohol chain-length. Quantitatively, the trend in area compressibility modulus follows Traube's rule of interfacial tension reduction, i.e., for each additional alcohol CH(2) group, the concentration required to reach the same area compressibility modulus was reduced roughly by a factor of 3. We convert our area compressibility data into interfacial tension values to: confirm that Traube's rule is followed for bilayers; show that alcohols decrease the interfacial tension of bilayer-water interfaces less effectively than oil-water interfaces; determine the partition coefficients and standard Gibbs adsorption energy per CH(2) group for adsorption of alcohol into the lipid headgroup region; and predict the increase in area per headgroup as well as the critical radius and line tension of a membrane pore for each concentration and chain-length of alcohol. The area expansion predictions were confirmed by direct measurements of the area expansion of vesicles exposed to flowing alcohol solutions. These measurements were fitted to a membrane kinetic model to find membrane permeability coefficients of short-chain alcohols. Taken together, the evidence presented here supports a view that alcohol partitioning into the bilayer headgroup region, with enhanced partitioning as the chain-length of the alcohol increases, results in chain-length-dependent interfacial tension reduction with concomitant chain-length-dependent reduction in mechanical moduli and membrane thickness.",1
"Ly, Hung V, Longo, Marjorie L",2
Fluorescence correlation spectroscopy relates rafts in model and native membranes.,0
"The lipid raft model has evoked a new perspective on membrane biology. Understanding the structure and dynamics of lipid domains could be a key to many crucial membrane-associated processes in cells. However, one shortcoming in the field is the lack of routinely applicable techniques to measure raft association without perturbation by detergents. We show that both in cell and in domain-exhibiting model membranes, fluorescence correlation spectroscopy (FCS) can easily distinguish a raft marker (cholera toxin B subunit bound to ganglioside (GM1) and a nonraft marker (dialkylcarbocyanine dye diI)) by their decidedly different diffusional mobilities. In contrast, these markers exhibit only slightly different mobilities in a homogeneous artificial membrane. Performing cholesterol depletion with methyl-beta-cyclodextrin, which disrupts raft organization, we find an analogous effect of reduced mobility for the nonraft marker in domain-exhibiting artificial membranes and in cell membranes. In contrast, cholesterol depletion has differential effects on the raft marker, cholera toxin B subunit-GM1, rendering it more mobile in artificial domain-exhibiting membranes but leaving it immobile in cell membranes, where cytoskeleton disruption is required to achieve higher mobility. Thus, fluorescence correlation spectroscopy promises to be a valuable tool to elucidate lipid raft associations in native cells and to gain deeper insight into the correspondence between model and natural membranes.",1
"Bacia, Kirsten, Scherfeld, Dag, Kahya, Nicoletta, Schwille, Petra",2
"Effect of nanomolar concentrations of sodium dodecyl sulfate, a catalytic inductor of alpha-helices, on human calcitonin incorporation and channel formation in planar lipid membranes.",0
"Human Calcitonin (hCt) is a peptide hormone which has a regulatory action in calcium-phosphorus metabolism. It is currently used as a therapeutic tool in bone pathologies such as osteoporosis and Paget's disease. However, due to its amphiphilic property tends to form a gelatinous solution in water which consists of fibrils that limits its therapeutic use. Here we show that sodium dodecyl sulfate (SDS), an anionic detergent able to induce and stabilize alpha-helices in polypeptides, at a monomeric concentration ranging between 0.26 mM-5 pM (all concentrations are below the CMC), increases the rate and number of hCt channel formation in planar lipid membranes, at both high and low hCt concentrations, with a maximum increase at a molecular hCt/SDS ratio of 1000:1. This effect could be interpreted as a counteraction to the fibrillation process of hCt molecules by removing molecules available for aggregation from the fluid; furthermore, this action, independently of channel formation in the cell membrane, could improve the peptide-receptor interaction. The action of SDS could be attributable to the strength of the sulfate negative charge and the hydrophobic chain; in fact, a similar effect was obtained with lauryl sarcosine and not with a neutral detergent such as n-dodecyl-beta-D-maltoside. The very low molecular ratio between SDS and peptide is suggestive of a possible catalytic action of SDS that could induce alpha-helices, the appropriate structures for interacting with the membrane. Moreover, in the experimental conditions investigated, the addition of SDS does not modify the membrane's electrical properties and most of the channel properties. This finding may contribute to the knowledge of environment-folding diseases due to protein and peptides.",1
"Micelli, Silvia, Meleleo, Daniela, Picciarelli, Vittorio, Stoico, Maria G, Gallucci, Enrico",2
"Lamellar organization of pigments in chlorosomes, the light harvesting complexes of green photosynthetic bacteria.",0
"Chlorosomes of green photosynthetic bacteria constitute the most efficient light harvesting complexes found in nature. In addition, the chlorosome is the only known photosynthetic system where the majority of pigments (BChl) is not organized in pigment-protein complexes but instead is assembled into aggregates. Because of the unusual organization, the chlorosome structure has not been resolved and only models, in which BChl pigments were organized into large rods, were proposed on the basis of freeze-fracture electron microscopy and spectroscopic constraints. We have obtained the first high-resolution images of chlorosomes from the green sulfur bacterium Chlorobium tepidum by cryoelectron microscopy. Cryoelectron microscopy images revealed dense striations approximately 20 A apart. X-ray scattering from chlorosomes exhibited a feature with the same approximately 20 A spacing. No evidence for the rod models was obtained. The observed spacing and tilt-series cryoelectron microscopy projections are compatible with a lamellar model, in which BChl molecules aggregate into semicrystalline lateral arrays. The diffraction data further indicate that arrays are built from BChl dimers. The arrays form undulating lamellae, which, in turn, are held together by interdigitated esterifying alcohol tails, carotenoids, and lipids. The lamellar model is consistent with earlier spectroscopic data and provides insight into chlorosome self-assembly.",1
"Psencík, J, Ikonen, T P, Laurinmäki, P, Merckel, M C, Butcher, S J, Serimaa, R E, Tuma, R",2
Total internal reflection with fluorescence correlation spectroscopy: nonfluorescent competitors.,0
"Total internal reflection with fluorescence correlation spectroscopy is a method for measuring the surface association/dissociation rate constants and absolute densities of fluorescent molecules at the interface of a planar substrate and solution. This method can also report the apparent diffusion coefficient and absolute concentration of fluorescent molecules very close to the surface. Theoretical expressions for the fluorescence fluctuation autocorrelation function when both surface association/dissociation kinetics and diffusion through the evanescent wave, in solution, contribute to the fluorescence fluctuations have been published previously. In the work described here, the nature of the autocorrelation function when both surface association/dissociation kinetics and diffusion through the evanescent wave contribute to the fluorescence fluctuations, and when fluorescent and nonfluorescent molecules compete for surface binding sites, is described. The autocorrelation function depends in general on the kinetic association and dissociation rate constants of the fluorescent and nonfluorescent molecules, the surface site density, the concentrations of fluorescent and nonfluorescent molecules in solution, the solution diffusion coefficients of the two chemical species, the depth of the evanescent field, and the size of the observed area on the surface. Both general and approximate expressions are presented.",1
"Lieto, Alena M, Thompson, Nancy L",2
Dynamic light scattering microscopy. A novel optical technique to image submicroscopic motions. I: theory.,0
"The theoretical basis of an optical microscope technique to image dynamically scattered light fluctuation decay rates (dynamic light scattering microscopy) is developed. It is shown that relative motions between scattering centers even smaller than the optical resolution of the microscope are sufficient to produce significant phase variations resulting in interference intensity fluctuations in the image plane. The timescale and time dependence for the temporal autocorrelation function of these intensity fluctuations is derived. The spatial correlation distance, which reports the average distance between constructive and destructive interference in the image plane, is calculated and compared with the pixel size, and the distance dependence of the spatial correlation function is derived. The accompanying article in this issue describes an experimental implementation of dynamic light scattering microscopy.",1
"Dzakpasu, Rhonda, Axelrod, Daniel",2
Microviscoelasticity of the apical cell surface of human umbilical vein endothelial cells (HUVEC) within confluent monolayers.,0
"We studied the local viscoelasticity of the apical membrane of human umbilical vein endothelial cells within confluent layers by magnetic tweezers microrheometry. Magnetic beads are coupled to various integrins by coating with fibronectin or invasin. By analyzing the deflection of beads evoked by various force scenarios we demonstrate that the cell envelope behaves as a linear viscoelastic body if forces up to 2 nN are applied for short times (<20 s) but can respond in an adaptive way if stress pulses are applied longer (>30 s). The time-dependent shear relaxation modulus G(t) exhibits three time regimes: a fast response (t < 0.05 s) where the relaxation modulus G(t) obeys a power law G(t) approximately t(-0.82+/-0.02); a plateau-like behavior (at 0.05 s < t < 0.15 s); and a slow flow-like response which is, however, partially reversible. Strain field mapping experiments with colloidal probes show that local forces induce a strain field exhibiting a range of zeta = 10 +/- 1 microm, but which could only be observed if nonmagnetic beads were coupled to the cell surface by invasin. By application of the theory of elasticity of planar bodies we estimated a surface shear modulus of 2.5 x10(-4) N/m. By assuming a thickness of the actin cortex of approximately 0.5 microm we estimate a Young modulus micro approximately 400 Pa for the apical membrane. The value agrees with a plateau modulus of an entangled or weakly cross-linked actin network of an actin concentration of 100 microM (mesh size 0.2 microm). This result together with our observation of a strong reduction of the shear modulus by the actin destabilizing agent latrunculin A suggests that the shear modulus measured by our technique is determined by the actin cortex. The effect of two ligands inducing actin stress fiber formation and centripetal contraction of cells (associated with the formation of gaps in the confluent cell monolayer) on the viscoelastic responses were studied: histamine and lysophosphatidic acid (LPA). Histamine evoked a dramatic increase of the cell stiffness by >1 order of magnitude within <30 s, which is attributed to a transient rise of the intracellular Ca(2+) level, since DMSO exerted a similar effect. The stiffening is accompanied by a concomitant rounding of the cells as observed by microinterferometry and relaxes partially in the timescale of 5 min, whereas gaps between cells close after approximately 30 min. LPA did not exert a remarkable and reproducible effect other than an occasional very weak transient increase of the shear stiffness, which shows that the gap formation activated by LPA is mediated by a different mechanism than that induced by histamine.",1
"Feneberg, Wolfgang, Aepfelbacher, Martin, Sackmann, Erich",2
Imaging neuronal seal resistance on silicon chip using fluorescent voltage-sensitive dye.,0
"The electrical sheet resistance between living cells grown on planar electronic contacts of semiconductors or metals is a crucial parameter for bioelectronic devices. It determines the strength of electrical signal transduction from cells to chips and from chips to cells. We measured the sheet resistance by applying AC voltage to oxidized silicon chips and by imaging the voltage change across the attached cell membrane with a fluorescent voltage-sensitive dye. The phase map of voltage change was fitted with a planar core-coat conductor model using the sheet resistance as a free parameter. For nerve cells from rat brain on polylysine as well as for HEK293 cells and MDCK cells on fibronectin we find a similar sheet resistance of 10 MOmega. Taking into account the independently measured distance of 50 nm between chip and membrane for these cells, we obtain a specific resistance of 50 Omegacm that is indistinguishable from bulk electrolyte. On the other hand, the sheet resistance for erythrocytes on polylysine is far higher, at approximately 1.5 GOmega. Considering the distance of 10 nm, the specific resistance in the narrow cleft is enhanced to 1500 Omegacm. We find this novel optical method to be a convenient tool to optimize the interface between cells and chips for bioelectronic devices.",1
"Braun, Dieter, Fromherz, Peter",2
Na/K pump-induced [Na](i) gradients in rat ventricular myocytes measured with two-photon microscopy.,0
"Via the Na/Ca and Na/H exchange, intracellular Na concentration ([Na](i)) is important in regulating cardiac Ca and contractility. Functional data suggest that [Na](i) might be heterogeneous in myocytes that are not in steady state, but little direct spatial information is available. Here we used two-photon microscopy of SBFI to spatially resolve [Na](i) in rat ventricular myocytes. In vivo calibration yielded an apparent K(d) of 27 +/- 2 mM Na. Similar resting [Na](i) was found using two-photon or single-photon ratiometric measurements with SBFI (10.8 +/- 0.7 vs. 11.1 +/- 0.7 mM). To assess longitudinal [Na](i) gradients, Na/K pumps were blocked at one end of the myocyte (locally pipette-applied K-free extracellular solution) and active in the rest of the cell. This led to a marked increase in [Na](i) at sites downstream of the pipette (where Na enters the myocyte and Na/K pumps are blocked). [Na](i) rise was smaller at upstream sites. This resulted in sustained [Na](i) gradients (up to approximately 17 mM/120 microm cell length). This implies that Na diffusion in cardiac myocytes is slow with respect to trans-sarcolemmal Na transport rates, although the mechanisms responsible are unclear. A simple diffusion model indicated that such gradients require a Na diffusion coefficient of 10-12 microm(2)/s, significantly lower than in aqueous solutions.",1
"Despa, Sanda, Kockskämper, Jens, Blatter, Lothar A, Bers, Donald M",2
Signaling in small subcellular volumes. I. Stochastic and diffusion effects on individual pathways.,0
"Many cellular signaling events occur in small subcellular volumes and involve low-abundance molecular species. This context introduces two major differences from mass-action analyses of nondiffusive signaling. First, reactions involving small numbers of molecules occur in a probabilistic manner which introduces scatter in chemical activities. Second, the timescale of diffusion of molecules between subcellular compartments and the rest of the cell is comparable to the timescale of many chemical reactions, altering the dynamics and outcomes of signaling reactions. This study examines both these effects on information flow through four protein kinase regulatory pathways. The analysis uses Monte Carlo simulations in a subcellular volume diffusively coupled to a bulk cellular volume. Diffusion constants and the volume of the subcellular compartment are systematically varied to account for a range of cellular conditions. Each pathway is characterized in terms of the probabilistic scatter in active kinase levels as a measure of ""noise"" on the pathway output. Under the conditions reported here, most signaling outcomes in a volume below one femtoliter are severely degraded. Diffusion and subcellular compartmentalization influence the signaling chemistry to give a diversity of signaling outcomes. These outcomes may include washout of the signal, reinforcement of signals, and conversion of steady responses to transients.",1
"Bhalla, Upinder S",2
Molecular Dynamics Simulations of Micelle Formation around Dimeric Glycophorin A Transmembrane Helices.,0
"Insertion and formation of membrane proteins involves the interaction of protein helices with one another in lipid environments. Researchers have studied glycophorin A (GpA) transmembrane helices embedded in sodium dodecyl sulfate (SDS) micelles to identify contacts significant for helix dimerization. However, a detailed picture of the conformation and dynamics of the GpA-SDS system cannot be obtained solely through experiment. Molecular dynamics simulations of SDS and a GpA dimer can provide an atomic-level picture of SDS aggregation and helix association. We report 2.5-ns simulations of GpA wild-type and mutants in a preformed micelle as well as a 32-ns simulation showing the formation of a complete micelle around wild-type GpA from an initially random placement of SDS molecules in an aqueous environment. In the latter case, an initial instability of GpA helices in water is reversed after the helices become surrounded by SDS. The properties of the spontaneously formed micelle surrounding the GpA are indistinguishable from those of the preformed micelle surrounding the GpA dimer.",1
"Braun, Rosemary, Engelman, Donald M, Schulten, Klaus",2
A molecular dynamics study of Ca(2+)-calmodulin: evidence of interdomain coupling and structural collapse on the nanosecond timescale.,0
"A 20-ns molecular dynamics simulation of Ca(2+)-calmodulin (CaM) in explicit solvent is described. Within 5 ns, the extended crystal structure adopts a compact shape similar in dimension to complexes of CaM and target peptides but with a substantially different orientation between the N- and C-terminal domains. Significant interactions are observed between the terminal domains in this compact state, which are mediated through the same regions of CaM that bind to target peptides derived from protein kinases and most other target proteins. The process of compaction is driven by the loss of helical structure in two separate regions between residues 75-79 and 82-86, the latter being driven by unfavorable electrostatic interactions between acidic residues. In the first 5 ns of the simulation, a substantial number of contacts are observed between the first helix of the N-terminal domain and residues 74-77 of the central linker. These contacts are correlated with the closing of the second EF-hand, indicating a mechanism by which they can lower calcium affinity in the N-terminal domain.",1
"Shepherd, Craig M, Vogel, Hans J",2
A model of the closed form of the nicotinic acetylcholine receptor m2 channel pore.,0
"The nicotinic acetylcholine receptor is a neurotransmitter-gated ion channel in the postsynaptic membrane. It is composed of five homologous subunits, each of which contributes one transmembrane helix--the M2 helix--to create the channel pore. The M2 helix from the delta subunit is capable of forming a channel by itself. Although a model of the receptor was recently proposed based on a low-resolution, cryo-electron microscopy density map, we found that the model does not explain much of the other available experimental data. Here we propose a new model of the M2 channel derived solely from helix packing and symmetry constraints. This model agrees well with experimental results from solid-state NMR, chemical reactivity, and mutagenesis experiments. The model depicts the channel pore, the channel gate, and the residues responsible for cation specificity.",1
"Kim, Sanguk, Chamberlain, Aaron K, Bowie, James U",2
Hydration of enzyme in nonaqueous media is consistent with solvent dependence of its activity.,0
"Water plays an important role in enzyme structure and function in aqueous media. That role becomes even more important when one focuses on enzymes in low water media. Here we present results from molecular dynamics simulations of surfactant-solubilized subtilisin BPN' in three organic solvents (octane, tetrahydrofuran, and acetonitrile) and in pure water. Trajectories from simulations are analyzed with a focus on enzyme structure, flexibility, and the details of enzyme hydration. The overall enzyme and backbone structures, as well as individual residue flexibility, do not show significant differences between water and the three organic solvents over a timescale of several nanoseconds currently accessible to large-scale molecular dynamics simulations. The key factor that distinguishes molecular-level details in different media is the partitioning of hydration water between the enzyme and the bulk solvent. The enzyme surface and the active site region are well hydrated in aqueous medium, whereas with increasing polarity of the organic solvent (octane --> tetrahydrofuran --> acetonitrile) the hydration water is stripped from the enzyme surface. Water stripping is accompanied by the penetration of tetrahydrofuran and acetonitrile molecules into crevices on the enzyme surface and especially into the active site. More polar organic solvents (tetrahydrofuran and acetonitrile) replace mobile and weakly bound water molecules in the active site and leave primarily the tightly bound water in that region. In contrast, the lack of water stripping in octane allows efficient hydration of the active site uniformly by mobile and weakly bound water and some structural water similar to that in aqueous solution. These differences in the active site hydration are consistent with the inverse dependence of enzymatic activity on organic solvent polarity and indicate that the behavior of hydration water on the enzyme surface and in the active site is an important determinant of biological function especially in low water media.",1
"Yang, Lu, Dordick, Jonathan S, Garde, Shekhar",2
Hill coefficient for estimating the magnitude of cooperativity in gating transitions of voltage-dependent ion channels.,0
"A frequently used measure for the extent of cooperativity in ligand binding by an allosteric protein is the Hill coefficient, obtained by fitting data of initial reaction velocity (or fractional binding saturation) as a function of substrate concentration to the Hill equation. Here, it is demonstrated that the simple two-state Boltzmann equation that is widely used to fit voltage-activation data of voltage-dependent ion channels is analogous to the Hill equation. A general empiric definition for a Hill coefficient (n(H)) for channel gating transitions that is analogous to the logarithmic potential sensitivity function of Almers is derived. This definition provides a novel framework for interpreting the meaning of the Hill coefficient. In considering three particular and simple gating schemes for a voltage-activated cation channel, the relation of the Hill coefficient to the magnitude and nature of cooperative interactions along the reaction coordinate of channel gating is demonstrated. A possible functional explanation for the low value of the Hill coefficient for gating transitions of the Shaker voltage-activated K(+) channel is suggested. The analogy between the Hill coefficients for ligand binding and for channel gating transitions further points to a unified conceptual framework in analyzing enzymes and channels behavior.",1
"Yifrach, Ofer",2
"Effect of ADP on Na(+)-Na(+) exchange reaction kinetics of Na,K-ATPase.",0
"The whole-cell voltage-clamp technique was used in rat cardiac myocytes to investigate the kinetics of ADP binding to phosphorylated states of Na,K-ATPase and its effects on presteady-state Na(+)-dependent charge movements by this enzyme. Ouabain-sensitive transient currents generated by Na,K-ATPase functioning in electroneutral Na(+)-Na(+) exchange mode were measured at 23 degrees C with pipette ADP concentrations ([ADP]) of up to 4.3 mM and extracellular Na(+) concentrations ([Na](o)) between 36 and 145 mM at membrane potentials (V(M)) from -160 to +80 mV. Analysis of charge-V(M) curves showed that the midpoint potential of charge distribution was shifted toward more positive V(M) both by increasing [ADP] at constant Na(+)(o) and by increasing [Na](o) at constant ADP. The total quantity of mobile charge, on the other hand, was found to be independent of changes in [ADP] or [Na](o). The presence of ADP increased the apparent rate constant for current relaxation at hyperpolarizing V(M) but decreased it at depolarizing V(M) as compared to control (no added ADP), an indication that ADP binding facilitates backward reaction steps during Na(+)-Na(+) exchange while slowing forward reactions. Data analysis using a pseudo three-state model yielded an apparent K(d) of approximately 6 mM for ADP binding to and release from the Na,K-ATPase phosphoenzyme; a value of 130 s(-1) for k(2), a rate constant that groups Na(+) deocclusion/release and the enzyme conformational transition E(1) approximately P --> E(2)-P; a value of 162 s(-1)M(-1) for k(-2), a lumped second-order V(M)-independent rate constant describing the reverse reactions; and a Hill coefficient of approximately 1 for Na(+)(o) binding to E(2)-P. The results are consistent with electroneutral release of ADP before Na(+) is deoccluded and released through an ion well. The same approach can be used to study additional charge-moving reactions and associated electrically silent steps of the Na,K-pump and other transporters.",1
"Peluffo, R Daniel",2
Dynamics of membrane nanotubulation and DNA self-assembly.,0
"A localized point-like force applied perpendicular to a vesicular membrane layer, using an optical tweezer, leads to membrane nanotubulation beyond a threshold force. Below the threshold, the force-extension curve shows an elastic response with a fine structure (serrations). Above the threshold the tubulation process exhibits a new reversible flow phase for the multilamellar membrane, which responds viscoelastically. Furthermore, with an oscillatory force applied during tubulation, broad but well-resolved resonances occur in the flow phase, presumably matching the time scales associated with the vesicle-nanotubule coupled system. These nanotubules, anchored to the optical tweezer also provide, for the first time, a direct probe of the real-time dynamics of DNA self-assembly on membranes. Our studies are a step in the direction of analyzing the dynamics of membrane self-assembly and artificial nanofluidic membrane networks.",1
"Roopa, T, Kumar, N, Bhattacharya, S, Shivashankar, G V",2
NMR Studies of lipid lateral diffusion in the DMPC/gramicidin D/water system: peptide aggregation and obstruction effects.,0
"The PFG-NMR method has been used in macroscopically oriented bilayers to investigate the effect of the peptide gramicidin D on the lateral diffusion of dimyristoylphosphatidylcholine. By varying both the temperature (21-35 degrees C) and the gramicidin content (0-5 mol %) we have introduced solid obstacles into the lipid liquid crystalline bilayer. It was shown that the obstruction effect exerted by the peptide can be described with several different theoretical models, each based on different premises, and that the fit of the models to experimental data gave reasonable results. We found that each gramicidin molecule was surrounded by approximately one layer of bound lipids and that the obstruction from gel phase patches can be described as small solid obstacles. No evidence of linear aggregates of gramicidin, such as those reported by atomic force microscopy in the gel phase, was found.",1
"Orädd, Greger, Lindblom, Göran",2
Physics of RecA-mediated homologous recognition.,0
"To accomplish its DNA strand exchange activities, the Escherichia coli protein RecA polymerizes onto DNA to form a stiff helical nucleoprotein filament within which the DNA is extended by 50%. Homology search and recognition occurs between ssDNA within the filament and an external dsDNA molecule. We show that stretching the internal DNA greatly enhances homology recognition by increasing the probability that the homologous regions of a stretched DNA molecule and a parallel, unstretched DNA molecule will be ""in register"" at some position. We also show that the stretching and stiffness of the filament act together to ensure that initiation of homologous exchange between the substrate DNA molecules at one position precludes initiation of homologous exchange at any other position. This prevents formation of multiple exchange site ""topological traps"" which would prevent completion of the exchange reaction and resolution of the products.",1
"Klapstein, Kevin, Chou, Tom, Bruinsma, Robijn",2
Michaelis-Menten kinetics under spatially constrained conditions: application to mibefradil pharmacokinetics.,0
"Two different approaches were used to study the kinetics of the enzymatic reaction under heterogeneous conditions to interpret the unusual nonlinear pharmacokinetics of mibefradil. Firstly, a detailed model based on the kinetic differential equations is proposed to study the enzymatic reaction under spatial constraints and in vivo conditions. Secondly, Monte Carlo simulations of the enzyme reaction in a two-dimensional square lattice, placing special emphasis on the input and output of the substrate were applied to mimic in vivo conditions. Both the mathematical model and the Monte Carlo simulations for the enzymatic reaction reproduced the classical Michaelis-Menten (MM) kinetics in homogeneous media and unusual kinetics in fractal media. Based on these findings, a time-dependent version of the classic MM equation was developed for the rate of change of the substrate concentration in disordered media and was successfully used to describe the experimental plasma concentration-time data of mibefradil and derive estimates for the model parameters. The unusual nonlinear pharmacokinetics of mibefradil originates from the heterogeneous conditions in the reaction space of the enzymatic reaction. The modified MM equation can describe the pharmacokinetics of mibefradil as it is able to capture the heterogeneity of the enzymatic reaction in disordered media.",1
"Kosmidis, Kosmas, Karalis, Vangelis, Argyrakis, Panos, Macheras, Panos",2
A computational model of the human left-ventricular epicardial myocyte.,0
"A computational model of the human left-ventricular epicardial myocyte is presented. Models of each of the major ionic currents present in these cells are formulated and validated using experimental data obtained from studies of recombinant human ion channels and/or whole-cell recording from single myocytes isolated from human left-ventricular subepicardium. Continuous-time Markov chain models for the gating of the fast Na(+) current, transient outward current, rapid component of the delayed rectifier current, and the L-type calcium current are modified to represent human data at physiological temperature. A new model for the gating of the slow component of the delayed rectifier current is formulated and validated against experimental data. Properties of calcium handling and exchanger currents are altered to appropriately represent the dynamics of intracellular ion concentrations. The model is able to both reproduce and predict a wide range of behaviors observed experimentally including action potential morphology, ionic currents, intracellular calcium transients, frequency dependence of action-potential duration, Ca(2+)-frequency relations, and extrasystolic restitution/post-extrasystolic potentiation. The model therefore serves as a useful tool for investigating mechanisms of arrhythmia and consequences of drug-channel interactions in the human left-ventricular myocyte.",1
"Iyer, Vivek, Mazhari, Reza, Winslow, Raimond L",2
A model of effective diffusion and tortuosity in the extracellular space of the brain.,0
"Tortuosity of the extracellular space describes hindrance posed to the diffusion process by a geometrically complex medium in comparison to an environment free of any obstacles. Calculating tortuosity in biologically relevant geometries is difficult. Yet this parameter has proved very important for many processes in the brain, ranging from ischemia and osmotic stress to delivery of nutrients and drugs. It is also significant for interpretation of the diffusion-weighted magnetic resonance data. We use a volume-averaging procedure to obtain a general expression for tortuosity in a complex environment. A simple approximation then leads to tortuosity estimates in a number of two-dimensional (2D) and three-dimensional (3D) geometries characterized by narrow pathways between the cellular elements. It also explains the counterintuitive fact of lower diffusion hindrance in a 3D environment. Comparison with Monte Carlo numerical simulations shows that the model gives reasonable tortuosity estimates for a number of regular and randomized 2D and 3D geometries. Importantly, it is shown that addition of dead-end pores increases tortuosity in proportion to the square root of enlarged total extracellular volume fraction. This conclusion is further supported by the previously described tortuosity decrease in ischemic brain slices where dead-end pores were partially occluded by large macromolecules introduced into the extracellular space.",1
"Hrabe, Jan, Hrabetová, Sabina, Segeth, Karel",2
Conductance studies on trichotoxin_A50E and implications for channel structure.,0
"Trichotoxin_A50E is an 18-residue peptaibol whose crystal structure has recently been determined. In this study, the conductance properties of trichotoxin_A50E have been investigated in neutral planar lipid bilayers. The macroscopic current-voltage curves disclose a moderate voltage-sensitivity and the concentration-dependence suggests the channels are primarily hexameric. Under ion gradients, shifts of the reversal potential indicate that cations are preferentially transported. Trichotoxin displays only one single-channel conductance state in a given experiment, but an ensemble of experiments reveals a distribution of conductance levels. This contrasts with the related peptaibol alamethicin, which produces multiple channel levels in a single experiment, indicative of recruitment of additional monomers into different multimeric-sized channels. Based on these conductance measurements and on the recently available crystal structure of trichotoxin_A50E, which is a shorter and straighter helix than alamethicin, a tightly-packed hexameric model structure has been constructed for the trichotoxin channel. It has molecular dimensions and surface electrostatic potential compatible with the observed conductance properties of the most probable and longer-lived channel.",1
"Duclohier, H, Alder, G M, Bashford, C L, Brückner, H, Chugh, J K, Wallace, B A",2
Nanometer localization of single green fluorescent proteins: evidence that myosin V walks hand-over-hand via telemark configuration.,0
"Myosin V is a homodimeric motor protein involved in trafficking of vesicles in the cell. It walks bipedally along actin filaments, moving cargo approximately 37 nm per step. We have measured the step size of individual myosin heads by fusing an enhanced green fluorescent protein (eGFP) to the N-terminus of one head of the myosin dimer and following the motion with nanometer precision and subsecond resolution. We find the average step size to be 74.1 nm with 9.4 nm (SD) and 0.3 nm (SE). Our measurements demonstrate nanometer localization of single eGFPs, confirm the hand-over-hand model of myosin V procession, and when combined with previous data, suggest that there is a kink in the leading lever arm in the waiting state of myosin V. This kink, or ""telemark skier"" configuration, may cause strain, which, when released, leads to the powerstroke of myosin, throwing the rear head forward and leading to unidirectional motion.",1
"Snyder, Gregory E, Sakamoto, Takeshi, Hammer, John A, Sellers, James R, Selvin, Paul R",2
Cardiac length dependence of force and force redevelopment kinetics with altered cross-bridge cycling.,0
"We examined the influence of cross-bridge cycling kinetics on the length dependence of steady-state force and the rate of force redevelopment (k(tr)) during Ca(2+)-activation at sarcomere lengths (SL) of 2.0 and 2.3 microm in skinned rat cardiac trabeculae. Cross-bridge kinetics were altered by either replacing ATP with 2-deoxy-ATP (dATP) or by reducing [ATP]. At each SL dATP increased maximal force (F(max)) and Ca(2+)-sensitivity of force (pCa(50)) and reduced the cooperativity (n(H)) of force-pCa relations, whereas reducing [ATP] to 0.5 mM (low ATP) increased pCa(50) and n(H) without changing F(max). The difference in pCa(50) between SL 2.0 and 2.3 microm (Delta pCa(50)) was comparable between ATP and dATP, but reduced with low ATP. Maximal k(tr) was elevated by dATP and reduced by low ATP. Ca(2+)-sensitivity of k(tr) increased with both dATP and low ATP and was unaffected by altered SL under all conditions. Significantly, at equivalent levels of submaximal force k(tr) was faster at short SL or increased lattice spacing. These data demonstrate that the SL dependence of force depends on cross-bridge kinetics and that the increase of force upon SL extension occurs without increasing the rate of transitions between nonforce and force-generating cross-bridge states, suggesting SL or lattice spacing may modulate preforce cross-bridge transitions.",1
"Adhikari, Bishow B, Regnier, Michael, Rivera, Anthony J, Kreutziger, Kareen L, Martyn, Donald A",2
Alternative N-terminal regions of Drosophila myosin heavy chain tune muscle kinetics for optimal power output.,0
"We assessed the influence of alternative versions of a region near the N-terminus of Drosophila myosin heavy chain on muscle mechanical properties. Previously, we exchanged N-terminal regions (encoded by alternative exon 3s) between an embryonic (EMB) isoform and the indirect flight muscle isoform (IFI) of myosin, and demonstrated that it influences solution ATPase rates and in vitro actin sliding velocity. Because each myosin is expressed in Drosophila indirect flight muscle, in the absence of other myosin isoforms, this allows for muscle mechanical and whole organism locomotion assays. We found that exchanging the flight muscle specific exon 3 region into the embryonic isoform (EMB-3b) increased maximum power generation (P(max)) and optimal frequency of power generation (f(max)) threefold and twofold compared to fibers expressing EMB, whereas exchanging the embryonic exon 3 region into the flight muscle isoform (IFI-3a) decreased P(max) and f(max) to approximately 80% of IFI fiber values. Drosophila expressing IFI-3a exhibited a reduced wing beat frequency compared to flies expressing IFI, which optimized power generation from their kinetically slowed flight muscle. However, the slower wing beat frequency resulted in a substantial loss of aerodynamic power as manifest in decreased flight performance of IFI-3a compared to IFI. Thus the N-terminal region is important in tuning myosin kinetics to match muscle speed for optimal locomotory performance.",1
"Swank, Douglas M, Kronert, William A, Bernstein, Sanford I, Maughan, David W",2
Time-resolved visible and infrared study of the cyano complexes of myoglobin and of hemoglobin I from Lucina pectinata.,0
"The dynamics of the ferric CN complexes of the heme proteins Myoglobin and Hemoglobin I from the clam Lucina pectinata upon Soret band excitation is monitored using infrared and broad band visible pump-probe spectroscopy. The transient response in the UV-vis spectral region does not depend on the heme pocket environment and is very similar to that known for ferrous proteins. The main feature is an instantaneous, broad, short-lived absorption signal that develops into a narrower red-shifted Soret band. Significant transient absorption is also observed in the 360-390 nm range. At all probe wavelengths the signal decays to zero with a longest time constant of 3.6 ps. The infrared data on MbCN reveal a bleaching of the C triple bond N stretch vibration of the heme-bound ligand, and the formation of a five-times weaker transient absorption band, 28 cm(-1) lower in energy, within the time resolution of the experiment. The MbC triple bond N stretch vibration provides a direct measure for the return of population to the ligated electronic (and vibrational) ground state with a 3-4 ps time constant. In addition, the CN-stretch frequency is sensitive to the excitation of low frequency heme modes, and yields independent information about vibrational cooling, which occurs on the same timescale.",1
"Helbing, Jan, Bonacina, Luigi, Pietri, Ruth, Bredenbeck, Jens, Hamm, Peter, van Mourik, Frank, Chaussard, Frédéric, Gonzalez-Gonzalez, Alejandro, Chergui, Majed, Ramos-Alvarez, Cacimar, Ruiz, Carlos, López-Garriga, Juan",2
All-optical constant-force laser tweezers.,0
"Optical tweezers are a powerful tool for the study of single biomolecules. Many applications require that a molecule be held under constant tension while its extension is measured. We present two schemes based on scanning-line optical tweezers to accomplish this, providing all-optical alternatives to force-clamp traps that rely on electronic feedback to maintain constant-force conditions for the molecule. In these schemes, a laser beam is rapidly scanned along a line in the focal plane of the microscope objective, effectively creating an extended one-dimensional optical potential over distances of up to 8 microm. A position-independent lateral force acting on a trapped particle is created by either modulating the laser beam intensity during the scan or by using an asymmetric beam profile in the back focal plane of the microscope objective. With these techniques, forces of up to 2.69 pN have been applied over distances of up to 3.4 microm with residual spring constants of <26.6 fN/microm. We used these techniques in conjunction with a fast position measurement scheme to study the relaxation of lambda-DNA molecules against a constant external force with submillisecond time resolution. We compare the results to predictions from the wormlike chain model.",1
"Nambiar, Rajalakshmi, Gajraj, Arivalagan, Meiners, Jens-Christian",2
Micro-volume couette flow sample orientation for absorbance and fluorescence linear dichroism.,0
"Linear dichroism (LD) can be used to study the alignment of absorbing chromophores within long molecules. In particular, Couette flow LD has been used to good effect in probing ligand binding to DNA and to fibrous proteins. This technique has been previously limited by large sample requirements. Here we report the design and application of a new micro-volume Couette flow cell that significantly enhances the potential applications of flow LD spectroscopy by reducing the sample requirements for flow linear dichroism to 25 microL (with concentrations such that the absorbance maximum of the sample in a 1-cm pathlength cuvette is approximately 1). The micro-volume Couette cell has also enabled the measurement of fluorescence-detected Couette flow linear dichroism. This new technique enables the orientation of fluorescent ligands to be probed even when their electronic transitions overlap with those of the macromolecule and conversely. The potential of flow-oriented fluorescence dichroism and application of the micro-volume Couette LD cell are illustrated by the collection of data for DNA with minor groove and intercalating ligands: DAPI, Hoechst, and ethidium bromide. As with conventional fluorescence, improved sensitivity compared with absorbance LD is to be expected after instrumentation optimization.",1
"Marrington, Rachel, Dafforn, Timothy R, Halsall, David J, Rodger, Alison",2
Coordinated behavior of mitochondria in both space and time: a reactive oxygen species-activated wave of mitochondrial depolarization.,0
"Reactive oxygen species (ROS) can trigger a transient burst of mitochondrial ROS production via ROS activation of the mitochondrial permeability transition pore (MPTP), a phenomenon termed ROS-induced ROS release (RIRR). The goal of this study was to investigate if the generation of ROS in a discrete region of a cardiomyocyte could serve to propagate RIRR-mediated mitochondrial depolarizations throughout a cell. Our experiments revealed that localized RIRR activated either RIRR-mediated fluctuations in mitochondrial membrane potential (time period: 3-10 min) or a traveling wave of depolarization of the cell's mitochondria (velocity: approximately 5 microm/min). Both phenomena appeared to be mediated by the mitochondrial permeability transition pore and eventually encompassed the majority of the mitochondrial population of both isolated rat and rabbit cardiomyocytes. Furthermore, depolarization was often reversible; the waves of depolarization were then followed by a rapid (approximately 40 microm/min) repolarization wave of the mitochondria. We show that the RIRR can function to communicate the mitochondrial permeability transition from one mitochondrion to another in the isolated adult cardiomyocyte.",1
"Brady, Nathan R, Elmore, Steven P, van Beek, Johannes J H G M, Krab, Klaas, Courtoy, Pierre J, Hue, Louis, Westerhoff, Hans V",2
A Brownian dynamics study of the interaction of Phormidium laminosum plastocyanin with Phormidium laminosum cytochrome f.,0
"The interaction of Phormidium laminosum plastocyanin (PC) with P. laminosum cytochrome f (cyt f) was studied using Brownian dynamics (BD) simulations. Few complexes and a low rate of electron transfer were observed for wild-type PC. Increasing the positive electrostatic field on PC by the addition of a Zn(2+) ion in the neighborhood of D44 and D45 on PC (as found in crystal structure of plastocyanin) increased the number of complexes formed and the calculated rates of electron transfer as did PC mutations D44A, D45A, E54A, and E57A. Mutations of charged residues on Phormidium PC and Phormidium cyt f were used to map binding sites on both proteins. In both the presence and absence of the Zn(2+) ion, the following residues on PC interact with cyt f: D44, D45, K6, D79, R93, and K100 that lie in a patch just below H92 and Y88 and D10, E17, and E70 located on the upper portion of the PC molecule. In the absence of the Zn(2+) ion, K6 and K35 on the top of the PC molecule also interact with cyt f. Cyt f residues involved in binding PC, in the absence of the Zn(2+) ion, include E165, D187, and D188 that are located on the small domain of cyt f. The orientation of PC in the complexes was quite random in accordance with NMR results. In the presence of the Zn(2+) ion, K53 and E54 in the lower patch of the PC molecule also interact with cyt f and PC interacts with E86, E95, and E123 on the large domain of cyt f. Also, the orientation of PC in the complexes was much more uniform than in the absence of the Zn(2+) ion. The difference may be due to both the larger electrostatic field and the greater asymmetry of the charge distribution on PC observed in the presence of the Zn(2+) ion. Hydrophobic interactions were also observed suggesting a model of cyt f-PC interactions in which electrostatic forces bring the two molecules together but hydrophobic interactions participate in stabilizing the final electron-transfer-active dock.",1
"Gross, Elizabeth L",2
A mitochondrial oscillator dependent on reactive oxygen species.,0
"We describe a unique mitochondrial oscillator that depends on oxidative phosphorylation, reactive oxygen species (ROS), and mitochondrial inner membrane ion channels. Cell-wide synchronized oscillations in mitochondrial membrane potential (Delta Psi(m)), NADH, and ROS production have been recently described in isolated cardiomyocytes, and we have hypothesized that the balance between superoxide anion efflux through inner membrane anion channels and the intracellular ROS scavenging capacity play a key role in the oscillatory mechanism. Here, we formally test the hypothesis using a computational model of mitochondrial energetics and Ca(2+) handling including mitochondrial ROS production, cytoplasmic ROS scavenging, and ROS activation of inner membrane anion flux. The mathematical model reproduces the period and phase of the observed oscillations in Delta Psi(m), NADH, and ROS. Moreover, we experimentally verify model predictions that the period of the oscillator can be modulated by altering the concentration of ROS scavengers or the rate of oxidative phosphorylation, and that the redox state of the glutathione pool oscillates. In addition to its role in cellular dysfunction during metabolic stress, the period of the oscillator can be shown to span a wide range, from milliseconds to hours, suggesting that it may also be a mechanism for physiological timekeeping and/or redox signaling.",1
"Cortassa, Sonia, Aon, Miguel A, Winslow, Raimond L, O'Rourke, Brian",2
Models of the structure and voltage-gating mechanism of the shaker K+ channel.,0
"In the preceding, accompanying article, we present models of the structure and voltage-dependent gating mechanism of the KvAP bacterial K+ channel that are based on three types of evidence: crystal structures of portions of the KvAP protein, theoretical modeling criteria for membrane proteins, and biophysical studies of the properties of native and mutated voltage-gated channels. Most of the latter experiments were performed on the Shaker K+ channel. Some of these data are difficult to relate directly to models of the KvAP channel's structure due to differences in the Shaker and KvAP sequences. We have dealt with this problem by developing new models of the structure and gating mechanism of the transmembrane and extracellular portions of the Shaker channel. These models are consistent with almost all of the biophysical data. In contrast, much of the experimental data are incompatible with the ""paddle"" model of gating that was proposed when the KvAP crystal structures were first published. The general folding pattern and gating mechanisms of our current models are similar to some of our earlier models of the Shaker channel.",1
"Durell, Stewart R, Shrivastava, Indira H, Guy, H Robert",2
Torque generation by the Fo motor of the sodium ATPase.,0
"Based on recent structural and functional findings, we have constructed a mathematical model for the sodium-driven Fo motor of the F1Fo-ATPase from the anaerobic bacterium Propionigenium modestum. The model reveals the mechanochemical principles underlying the Fo motor's operation, and explains all of the existing experimental data on wild-type and mutant Fo motors. In particular, the model predicts a nonmonotonic dependence of the ATP hydrolysis activity on the sodium concentration, a prediction confirmed by new experiments. To explain experimental observations, the positively charged stator residue (R227) must assume different positions in the ATP synthesis and hydrolysis directions. This work also illustrates how to extract a motor mechanism from dynamical experimental observations in the absence of complete structural information.",1
"Xing, Jianhua, Wang, Hongyun, von Ballmoos, Christoph, Dimroth, Peter, Oster, George",2
Uniform sampling of steady-state flux spaces: means to design experiments and to interpret enzymopathies.,0
"Reconstruction of genome-scale metabolic networks is now possible using multiple different data types. Constraint-based modeling is an approach to interrogate capabilities of reconstructed networks by constraining possible cellular behavior through the imposition of physicochemical laws. As a result, a steady-state flux space is defined that contains all possible functional states of the network. Uniform random sampling of the steady-state flux space allows for the unbiased appraisal of its contents. Monte Carlo sampling of the steady-state flux space of the reconstructed human red blood cell metabolic network under simulated physiologic conditions yielded the following key results: 1), probability distributions for the values of individual metabolic fluxes showed a wide variety of shapes that could not have been inferred without computation; 2), pairwise correlation coefficients were calculated between all fluxes, determining the level of independence between the measurement of any two fluxes, and identifying highly correlated reaction sets; and 3), the network-wide effects of the change in one (or a few) variables (i.e., a simulated enzymopathy or fixing a flux range based on measurements) were computed. Mathematical models provide the most compact and informative representation of a hypothesis of how a cell works. Thus, understanding model predictions clearly is vital to driving forward the iterative model-building procedure that is at the heart of systems biology. Taken together, the Monte Carlo sampling procedure provides a broadening of the constraint-based approach by allowing for the unbiased and detailed assessment of the impact of the applied physicochemical constraints on a reconstructed network.",1
"Price, Nathan D, Schellenberger, Jan, Palsson, Bernhard O",2
How does averaging affect protein structure comparison on the ensemble level?,0
"Recent algorithmic advances and continual increase in computational power have made it possible to simulate protein folding and dynamics on the level of ensembles. Furthermore, analyzing protein structure by using ensemble representation is intrinsic to certain experimental techniques, such as nuclear magnetic resonance. This creates a problem of how to compare an ensemble of molecules with a given reference structure. Recently, we used distance-based root-mean-square deviation (dRMS) to compare the native structure of a protein with its unfolded-state ensemble. We showed that for small, mostly alpha-helical proteins, the mean unfolded-state Calpha-Calpha distance matrix is significantly more nativelike than the Calpha-Calpha matrices corresponding to the individual members of the unfolded ensemble. Here, we give a mathematical derivation that shows that, for any ensemble of structures, the dRMS deviation between the ensemble-averaged distance matrix and any given reference distance matrix is always less than or equal to the average dRMS deviation of the individual members of the ensemble from the same reference matrix. This holds regardless of the nature of the reference structure or the structural ensemble in question. In other words, averaging of distance matrices can only increase their level of similarity to a given reference matrix, relative to the individual matrices comprising the ensemble. Furthermore, we show that the above inequality holds in the case of Cartesian coordinate-based root-mean-square deviation as well. We discuss this in the context of our proposal that the average structure of the unfolded ensemble of small helical proteins is close to the native structure, and demonstrate that this finding goes beyond the above mathematical fact.",1
"Zagrovic, Bojan, Pande, Vijay S",2
A model of the putative pore region of the cardiac ryanodine receptor channel.,0
"Using the bacterial K+ channel KcsA as a template, we constructed models of the pore region of the cardiac ryanodine receptor channel (RyR2) monomer and tetramer. Physicochemical characteristics of the RyR2 model monomer were compared with the template, including homology, predicted secondary structure, surface area, hydrophobicity, and electrostatic potential. Values were comparable with those of KcsA. Monomers of the RyR2 model were minimized and assembled into a tetramer that was, in turn, minimized. The assembled tetramer adopts a structure equivalent to that of KcsA with a central pore. Characteristics of the RyR2 model tetramer were compared with the KcsA template, including average empirical energy, strain energy, solvation free energy, solvent accessibility, and hydrophobic, polar, acid, and base moments. Again, values for the model and template were comparable. The pores of KcsA and RyR2 have a common motif with a hydrophobic channel that becomes polar at both entrances. Quantitative comparisons indicate that the assembled structure provides a plausible model for the pore of RyR2. Movement of Ca2+, K+, and tetraethylammonium (TEA+) through the model RyR2 pore were simulated with explicit solvation. These simulations suggest that the model RyR2 pore is permeable to Ca2+ and K+ with rates of translocation greater for K+. In contrast, simulations indicate that tetraethylammonium blocks movement of metal cations.",1
"Welch, William, Rheault, Shana, West, Duncan J, Williams, Alan J",2
Exchange of gating properties between rat cx46 and chicken cx45.6.,0
"Cx46 and Cx50 are coexpressed in lens fiber cells where they form fiber-fiber gap junctions. Recent studies have shown that both proteins play a critical role in maintaining lens transparency. Although both Cx46 and Cx50 (or its chicken ortholog, Cx45.6) show a high degree of sequence homology, they exhibit marked differences in gap junctional channel gating, unitary gap junctional channel conductance, and hemichannel gating. To better understand which regions of the protein are responsible for these functional differences, we have constructed a series of chimeric Cx46-Cx45.6 gap junctional proteins in which a single transmembrane or intracellular domain of Cx45.6 was replaced with the corresponding domain of Cx46, expressed them in Xenopus oocyte pairs or N2A cells, and examined the resulting gap junctional conductances. Our results showed that four out of six of the chimeras induced high levels of gap junctional coupling. Of these chimeras, only Cx45.6-46NT showed significant changes in voltage-dependent gating properties. Exchanging the N-terminus had multiple effects. It slowed the inactivation kinetics of the macroscopic junctional currents so that they resembled those of Cx46, reduced the voltage sensitivity of the steady-state junctional conductance, and decreased the conductance of single gap junctional channels. Additional point mutations identified a uniquely occurring arginine in the N-terminus of Cx46 as the main determinant for the change in voltage-dependent gating.",1
"Tong, Jun-Jie, Liu, Xiaoqin, Dong, Lixian, Ebihara, Lisa",2
K+ activation of kir3.1/kir3.4 and kv1.4 K+ channels is regulated by extracellular charges.,0
"K+ activates many inward rectifier and voltage-gated K+ channels. In each case, an increase in K+ current through the channel can occur despite a reduced driving force. We have investigated the molecular mechanism of K+ activation of the inward rectifier K+ channel, Kir3.1/Kir3.4, and the voltage-gated K+ channel, Kv1.4. In the Kir3.1/Kir3.4 channel, mutation of an extracellular arginine residue, R155, in the Kir3.4 subunit markedly reduced K+ activation of the channel. The same mutation also abolished Mg2+ block of the channel. Mutation of the equivalent residue in Kv1.4 (K532) abolished K+ activation as well as C-type inactivation of the Kv1.4 channel. Thus, whereas C-type inactivation is a collapse of the selectivity filter, K+ activation could be an opening of the selectivity filter. K+ activation of the Kv1.4 channel was enhanced by acidic pH. Mutation of an extracellular histidine residue, H508, that mediates the inhibitory effect of protons on Kv1.4 current, abolished both K+ activation and the enhancement of K+ activation at acidic pH. These results suggest that the extracellular positive charges in both the Kir3.1/Kir3.4 and the Kv1.4 channels act as ""guards"" and regulate access of K+ to the selectivity filter and, thus, the open probability of the selectivity filter. Furthermore, these data suggest that, at acidic pH, protonation of H508 inhibits current through the Kv1.4 channel by decreasing K+ access to the selectivity filter, thus favoring the collapse of the selectivity filter.",1
"Claydon, T W, Makary, S Y, Dibb, K M, Boyett, M R",2
Structural calorimetry of main transition of supported DMPC bilayers by temperature-controlled AFM.,0
"Atomic force microscopy at high temperature resolution (DeltaT < or approximately 0.1 K) provided a quantitative structural calorimetry of the transition from the fluid (Lalpha)- to the gel (Pbeta')-phase of supported dimyristoylphosphatidylcholine bilayers. Besides a determination of the main transition temperature (T0) and the van't Hoff transition enthalpy (DeltaHvH), the structural analysis in the nm-scale at T close to T0 of the ripple phase allowed an experimental estimation of the area of cooperative units from small lipid domains. Thereby, the corresponding transition enthalpy (DeltaH) of single molecules could be determined. The lipid organization and the corresponding parameters T0 and DeltaHvH (DeltaH) were modulated by heptanol or external Ca2+ and compared with physiological findings. The size of the cooperative unit was not significantly affected by the presence of 1 mM heptanol. The observed linear relationship of DeltaHvH and T0 was discussed in terms of a change in heat capacity.",1
"Enders, O, Ngezahayo, A, Wiechmann, M, Leisten, F, Kolb, H-A",2
Evidence for a novel mechanism of time-resolved flavin fluorescence depolarization in glutathione reductase.,0
"Time-resolved flavin fluorescence anisotropy studies on glutathione reductase (GR) have revealed a remarkable new phenomenon: wild-type GR displays a rapid process of fluorescence depolarization, that is absent in mutant enzymes lacking a nearby tyrosine residue that blocks the NADPH-binding cleft. Fluorescence lifetime data, however, have shown a more rigid active-site structure for wild-type GR than for the tyrosine mutants. These results suggest that the rapid depolarization in wild-type GR originates from an interaction with the flavin-shielding tyrosine, and not from restricted reorientational motion of the flavin. A novel mechanism of fluorescence depolarization is proposed that involves a transient charge-transfer complex between the tyrosine and the light-excited flavin, with a concomitant change in the direction of the emission dipole moment of the flavin. This interaction is likely to result from side-chain relaxation of the tyrosine in the minor fraction of enzyme molecules in which this residue is in an unsuitable position for immediate fluorescence quenching at the moment of excitation. Support for this mechanism is provided by binding studies with NADP+ and 2'P-5'ADP-ribose that can intercalate between the flavin and tyrosine and/or block the latter. Fluorescence depolarization analyses as a function of temperature and viscosity confirm the dynamic nature of the process. A comparison with fluorescence depolarization effects in a related flavoenzyme indicates that this mechanism of flavin fluorescence depolarization is more generally applicable.",1
"van den Berg, Petra A W, van Hoek, Arie, Visser, Antonie J W G",2
Direct discrimination between models of protein activation by single-molecule force measurements.,0
"The limitations imposed on the analyses of complex chemical and biological systems by ensemble averaging can be overcome by single-molecule experiments. Here, we used a single-molecule technique to discriminate between two generally accepted mechanisms of a key biological process--the activation of proteins by molecular effectors. The two mechanisms, namely induced-fit and population-shift, are normally difficult to discriminate by ensemble approaches. As a model, we focused on the interaction between the nuclear transport effector, RanBP1, and two related complexes consisting of the nuclear import receptor, importin beta, and the GDP- or GppNHp-bound forms of the small GTPase, Ran. We found that recognition by the effector proceeds through either an induced-fit or a population-shift mechanism, depending on the substrate, and that the two mechanisms can be differentiated by the data.",1
"Nevo, Reinat, Brumfeld, Vlad, Elbaum, Michael, Hinterdorfer, Peter, Reich, Ziv",2
Correct diffusion coefficients of proteins in fluorescence correlation spectroscopy. Application to tubulin oligomers induced by Mg2+ and Paclitaxel.,0
"In view of recent warnings for artifacts in fluorescence correlation spectroscopy, the diffusion coefficient of a series of labeled proteins in a wide range of molecular mass (43-670 kD) was determined and shown to be correct with respect to published values and the theory. Fluorescence correlation spectroscopy was then applied to the study of fluorescently labeled tubulin and its oligomerization in vitro induced by Mg2+ ions, paclitaxel, and a fluorescent derivative of paclitaxel (Flutax2). By applying relations derived from the theory of Oosawa, we were able to determine the association constant of the oligomers induced by Mg2+. With Flutax2 our experiments show that at nanomolar concentration, the fluorescent derivative is able to recruit tubulin dimers and to form oligomers of defined size. Flutax2 does not bind to microtubules preformed with paclitaxel, but it becomes preferentially incorporated into microtubules when Flutax2 oligomers are preformed, and microtubule formation is induced by paclitaxel addition. This shows that their incorporation into microtubules is faster than the displacement of the prebound drug. Experiments using fluorescently labeled tubulin and (unlabeled) paclitaxel confirm the induction of tubulin oligomers at limiting paclitaxel concentrations.",1
"Krouglova, Tatiana, Vercammen, Jo, Engelborghs, Yves",2
Atomic model of the Thermus thermophilus 70S ribosome developed in silico.,0
"The ribosome is a large molecular complex that consists of at least three ribonucleic acid molecules and a large number of proteins. It translates genetic information from messenger ribonucleic acid and makes protein accordingly. To better understand ribosomal function and provide information for designing biochemical experiments require knowledge of the complete structure of the ribosome. For expanding the structural information of the ribosome, we took on the challenge of developing a detailed Thermus thermophilus ribosomal structure computationally. By combining information derived from the low-resolution x-ray structure of the 70S ribosome (providing the overall fold), high-resolution structures of the ribosomal subunits (providing the local structure), sequences, and secondary structures, we have developed an atomic model of the T. thermophilus ribosome using a homology modeling approach. Our model is stereochemically sound with a consistent single-species sequence. The overall folds of the three ribosomal ribonucleic acids in our model are consistent with those in the low-resolution crystal structure (root mean-square differences are all <1.9 angstroms). The large overall interface area (approximately 2500 angstroms2) of intersubunit bridges B2a, B3, and B5, and the inherent flexibility in regions connecting the contact residues are consistent with these bridges serving as anchoring patches for the ratcheting and rolling motions between the two subunits during translocation.",1
"Tung, Chang-Shung, Sanbonmatsu, Kevin Y",2
Birth and growth kinetics of brome mosaic virus microcrystals.,0
"The early steps of crystal nucleation and growth in Brome Mosaïc virus and polyethylene glycol mixtures were analyzed using time-resolved x-ray scattering (at the European Synchrotron Radiation Facility, Grenoble, France). The system was chosen as a crystallization model since the phase diagram of the macromolecule/polymer mixture was known to present, at high polymer concentration, a solid, precipitated phase made of the synchronized formation of a large number of microcrystals. The precipitation and crystallization of the samples was induced by the controlled mixing of virus and polymer using a stopped-flow device. Appearance and growth of Bragg diffraction peaks were used to follow the crystal nucleation and growth as a function of time, virus and polymer concentration, and polymer size. In all samples, the crystallization starts after a few seconds and proceeds for approximately 1-20 min until there is almost no virus left in the solution. The crystalline system was found to be face-centered cubic, with a unit cell size of 391 angstroms. The data analysis allowed us to show the presence of viruses in only two states, in solution or in crystals, revealing that the formation of periodic order proceeds without any detectable intermediate amorphous state.",1
"Casselyn, Marina, Tardieu, Annette, Delacroix, Hervé, Finet, Stéphanie",2
Secondary structure and secondary structure dynamics of DNA hairpins complexed with HIV-1 NC protein.,0
"Reverse transcription of the HIV-1 RNA genome involves several complex nucleic acid rearrangement steps that are catalyzed by the HIV-1 nucleocapsid protein (NC), including for example, the annealing of the transactivation response (TAR) region of the viral RNA to the complementary region (TAR DNA) in minus-strand strong-stop DNA. We report herein single-molecule fluorescence resonance energy transfer measurements on single immobilized TAR DNA hairpins and hairpin mutants complexed with NC (i.e., TAR DNA/NC). Using this approach we have explored the conformational distribution and dynamics of the hairpins in the presence and absence of NC protein. The data demonstrate that NC shifts the equilibrium secondary structure of TAR DNA hairpins from a fully ""closed"" conformation to essentially one specific ""partially open"" conformation. In this specific conformation, the two terminal stems are ""open"" or unwound and the other stems are closed. This partially open conformation is arguably a key TAR DNA intermediate in the NC-induced annealing mechanism of TAR DNA.",1
"Cosa, Gonzalo, Harbron, Elizabeth J, Zeng, Yining, Liu, Hsiao-Wei, O'Connor, Donald B, Eta-Hosokawa, Chie, Musier-Forsyth, Karin, Barbara, Paul F",2
Biomechanics of Schlemm's canal endothelial cells: influence on F-actin architecture.,0
"Aqueous humor drains from the eye through Schlemm's canal, a small endothelial-lined collecting duct. Schlemm's canal endothelial cells may be important in controlling the pressure within the eye (and hence are of interest in glaucoma), and are subject to an unusual combination of shear stress and a basal-to-apical pressure gradient. We sought to characterize this biomechanical environment and determine its effects on F-actin architecture in situ. A theoretical model of flow in Schlemm's canal was used to estimate shear stresses applied to endothelial cells by flowing aqueous humor. Alignment of Schlemm's canal endothelial cells in human eyes was quantified by scanning electron microscopy. F-actin architecture was visualized by fluorescent labeling and compared for closely adjacent cells exposed to different biomechanical environments. We found that, despite the relatively low flow rate of aqueous humor, shear stresses experienced by Schlemm's canal endothelial cells could reach those in the arterial system. Schlemm's canal endothelial cells showed a statistically significant preferential alignment, consistent with a shear-mediated effect. Schlemm's canal endothelial cells subjected to a basal-to-apical pressure gradient due to transendothelial flow showed a prominent marginal band of F-actin with relatively few cytoplasmic filaments. Adjacent cells not subject to this gradient showed little marginal F-actin, with a denser cytoplasmic random network. We conclude that Schlemm's canal endothelial cells experience physiologically significant levels of shear stress, promoting cell alignment. We speculate that this may help control the calibre of Schlemm's canal. F-actin distribution depends critically on the presence or absence of transendothelial flow and its associated pressure gradient. In the case of this pressure gradient, mechanical reinforcement around the cell periphery by F-actin seems to be critical.",1
"Ethier, C Ross, Read, A Thomas, Chan, Darren",2
Q-band EPR of the S2 state of photosystem II confirms an S = 5/2 origin of the X-band g = 4.1 signal.,0
"Disagreement has remained about the spin state origin of the g = 4.1 EPR signal observed at X-band (9 GHz) from the S2 oxidation state of the Mn cluster of Photosystem II. In this study, the S2 state of PSII-enriched membrane fragments was examined at Q-band (34 GHz), with special interest in low-field signals. Light-induced signals at g = 3.1 and g = 4.6 were observed. The intensity of the signal at g = 3.1 was enhanced by the presence of F- and suppressed by the presence of 5% ethanol, indicating that it was from the same spin system as the X-band signal at g = 4.1. The Q-band signal at g = 4.6 was also enhanced by F-, but not suppressed by 5% ethanol, making its identity less clear. Although it can be accounted for by the same spin system, other sources for the signal are considered. The observation of the signal at g = 3.1 agrees well with a previous study at 15.5 GHz, in which the X-band g = 4.1 signal was proposed to arise from the middle Kramers doublet of a near rhombic S = 5/2 system. Zero-field splitting values of D = 0.455 cm(-1) and E/D = 0.25 are used to simulate the spectra.",1
"Haddy, Alice, Lakshmi, K V, Brudvig, Gary W, Frank, Harry A",2
Circular dichroism of carotenoids in bacterial light-harvesting complexes: experiments and modeling.,0
"In this work we investigate the origin and characteristics of the circular dichroism (CD) spectrum of rhodopin glucoside and lycopene in the light-harvesting 2 complex of Rhodopseudomonas acidophila and Rhodospirillum molischianum, respectively. We successfully model their absorption and CD spectra based on the high-resolution structures. We assume that these spectra originate from seven interacting transition dipole moments: the first corresponds to the 0-0 transition of the carotenoid, whereas the remaining six represent higher vibronic components of the S2 state. From the absorption spectra we get an estimate of the Franck-Condon factors of these transitions. Furthermore, we investigate the broadening mechanisms that lead to the final shape of the spectra and get an insight into the interaction energy between carotenoids. Finally, we examine the consequences of rotations of the carotenoid transition dipole moment and of deformations in the light-harvesting 2 complex rings. Comparison of the modeled carotenoid spectra with modeled spectra of the bacteriochlorophyll QY region leads to a refinement of the modeling procedure and an improvement of all calculated results. We therefore propose that the combined carotenoid and bacteriochlorophyll CD can be used as an accurate reflection of the overall structure of the light-harvesting complexes.",1
"Georgakopoulou, S, van Grondelle, R, van der Zwan, G",2
"Calculation of cyclodextrin binding affinities: energy, entropy, and implications for drug design.",0
"The second generation Mining Minima method yields binding affinities accurate to within 0.8 kcal/mol for the associations of alpha-, beta-, and gamma-cyclodextrin with benzene, resorcinol, flurbiprofen, naproxen, and nabumetone. These calculations require hours to a day on a commodity computer. The calculations also indicate that the changes in configurational entropy upon binding oppose association by as much as 24 kcal/mol and result primarily from a narrowing of energy wells in the bound versus the free state, rather than from a drop in the number of distinct low-energy conformations on binding. Also, the configurational entropy is found to vary substantially among the bound conformations of a given cyclodextrin-guest complex. This result suggests that the configurational entropy must be accounted for to reliably rank docked conformations in both host-guest and ligand-protein complexes. In close analogy with the common experimental observation of entropy-enthalpy compensation, the computed entropy changes show a near-linear relationship with the changes in mean potential plus solvation energy.",1
"Chen, Wei, Chang, Chia-En, Gilson, Michael K",2
An all-atom force field for tertiary structure prediction of helical proteins.,0
"We have developed an all-atom free-energy force field (PFF01) for protein tertiary structure prediction. PFF01 is based on physical interactions and was parameterized using experimental structures of a family of proteins believed to span a wide variety of possible folds. It contains empirical, although sequence-independent terms for hydrogen bonding. Its solvent-accessible surface area solvent model was first fit to transfer energies of small peptides. The parameters of the solvent model were then further optimized to stabilize the native structure of a single protein, the autonomously folding villin headpiece, against competing low-energy decoys. Here we validate the force field for five nonhomologous helical proteins with 20-60 amino acids. For each protein, decoys with 2-3 A backbone root mean-square deviation and correct experimental Cbeta-Cbeta distance constraints emerge as those with the lowest energy.",1
"Herges, T, Wenzel, W",2
Functional characterization of a small conductance GIRK channel in rat atrial cells.,0
"Muscarinic K+ (KACh) channels are key determinants of the inhibitory synaptic transmission in the heart. These channels are heterotetramers consisting of two homologous subunits, G-protein-gated inwardly rectifying K+ (GIRK)1 and GIRK4, and have unitary conductance of approximately 35 pS with symmetrical 150 mM KCl solutions. Activation of atrial KACh channels, however, is often accompanied by the appearance of openings with a lower conductance, suggesting a functional heterogeneity of G-protein-sensitive ion channels in the heart. Here we report the characterization of a small conductance GIRK (scGIRK) channel present in rat atria. This channel is directly activated by Gbetagamma subunits and has a unitary conductance of 16 pS. The scGIRK and KACh channels display similar affinities for Gbetagamma binding and are frequently found in the same membrane patches. Furthermore, Gbetagamma-activated scGIRK channels--like their KACh counterparts--exhibit complex gating behavior, fluctuating among four functional modes conferred by the apparent binding of a different number of Gbetagamma subunits to the channel. The electrogenic efficacy of the scGIRK channels, however, is negligible compared to that of KACh channels. Thus, Gbetagamma subunits employ the same signaling strategy to regulate two ion channels that are apparently endowed with very different functions in the atrial membrane.",1
"Nikolov, Emil N, Ivanova-Nikolova, Tatyana T",2
Negatively charged residues in the N-terminal of the AID helix confer slow voltage dependent inactivation gating to CaV1.2.,0
"The E462R mutation in the fifth position of the AID (alpha1 subunit interaction domain) region in the I-II linker is known to significantly accelerate voltage-dependent inactivation (VDI) kinetics of the L-type CaV1.2 channel, suggesting that the AID region could participate in a hinged-lid type inactivation mechanism in these channels. The recently solved crystal structures of the AID-CaVbeta regions in L-type CaV1.1 and CaV1.2 channels have shown that in addition to E462, positions occupied by Q458, Q459, E461, K465, L468, D469, and T472 in the rabbit CaV1.2 channel could also potentially contribute to a hinged-lid type mechanism. A mutational analysis of these residues shows that Q458A, Q459A, K465N, L468R, D469A, and T472D did not significantly alter VDI gating. In contrast, mutations of the negatively charged E461, E462, and D463 to neutral or positively charged residues increased VDI gating, suggesting that the cluster of negatively charged residues in the N-terminal end of the AID helix could account for the slower VDI kinetics of CaV1.2. A mutational analysis at position 462 (R, K, A, G, D, N, Q) further confirmed that E462R yielded faster VDI kinetics at +10 mV than any other residue with E462R > E462K approximately E462A > E462N > wild-type approximately E462Q approximately E462G > E462D (from the fastest to the slowest). E462R was also found to increase the VDI gating of the slow CEEE chimera that includes the I-II linker from CaV1.2 into a CaV2.3 background. The fast VDI kinetics of the CaV1.2 E462R and the CEEE + E462R mutants were abolished by the CaVbeta2a subunit and reinstated when using the nonpalmitoylated form of CaVbeta2a C3S + C4S (CaVbeta2a CS), confirming that CaVbeta2a and E462R modulate VDI through a common pathway, albeit in opposite directions. Altogether, these results highlight the unique role of E461, E462, and D463 in the I-II linker in the VDI gating of high-voltage activated CaV1.2 channels.",1
"Dafi, Omar, Berrou, Laurent, Dodier, Yolaine, Raybaud, Alexandra, Sauvé, Rémy, Parent, Lucie",2
A statistical thermodynamic model applied to experimental AFM population and location data is able to quantify DNA-histone binding strength and internucleosomal interaction differences between acetylated and unacetylated nucleosomal arrays.,0
"Imaging of nucleosomal arrays by atomic force microscopy allows a determination of the exact statistical distributions for the numbers of nucleosomes per array and the locations of nucleosomes on the arrays. This precision makes such data an excellent reference for testing models of nucleosome occupation on multisite DNA templates. The approach presented here uses a simple statistical thermodynamic model to calculate theoretical population and positional distributions and compares them to experimental distributions previously determined for 5S rDNA nucleosomal arrays (208-12,172-12). The model considers the possible locations of nucleosomes on the template, and takes as principal parameters an average free energy of interaction between histone octamers and DNA, and an average wrapping length of DNA around the octamers. Analysis of positional statistics shows that it is possible to consider interactions between nucleosomes and positioning effects as perturbations on a random positioning noninteracting model. Analysis of the population statistics is used to determine histone-DNA association constants and to test for differences in the free energies of nucleosome formation with different types of histone octamers, namely acetylated or unacetylated, and different DNA templates, namely 172-12 or 208-12 5S rDNA multisite templates. The results show that the two template DNAs bind histones with similar affinities but histone acetylation weakens the association of histones with both templates. Analysis of locational statistics is used to determine the strength of specific nucleosome positioning tendencies by the DNA templates, and the strength of the interactions between neighboring nucleosomes. The results show only weak positioning tendencies and that unacetylated nucleosomes interact much more strongly with one another than acetylated nucleosomes; in fact acetylation appears to induce a small anticooperative occupation effect between neighboring nucleosomes.",1
"Solis, F J, Bash, R, Yodh, J, Lindsay, S M, Lohr, D",2
Association of a model transmembrane peptide containing gly in a heptad sequence motif.,0
"A peptide containing glycine at a and d positions of a heptad motif was synthesized to investigate the possibility that membrane-soluble peptides with a Gly-based, left-handed helical packing motif would associate. Based on analytical ultracentrifugation in C14-betaine detergent micelles, the peptide did associate in a monomer-dimer equilibrium, although the association constant was significantly less than that reported for the right-handed dimer of the glycophorin A transmembrane peptide in similar detergents. Fluorescence resonance energy transfer (FRET) experiments conducted on peptides labeled at their N-termini with either tetramethylrhodamine (TMR) or 7-nitrobenz-2-oxa-1,3-diazole (NBD) also indicated association. However, analysis of the FRET data using the usual assumption of complete quenching for NBD-TMR pairs in the dimer could not be quantitatively reconciled with the analytical ultracentrifugation-measured dimerization constant. This led us to develop a general treatment for the association of helices to either parallel or antiparallel structures of any aggregation state. Applying this treatment to the FRET data, constraining the dimerization constant to be within experimental uncertainty of that measured by analytical ultracentrifugation, we found the data could be well described by a monomer-dimer equilibrium with only partial quenching of the dimer, suggesting that the helices are most probably antiparallel. These results also suggest that a left-handed Gly heptad repeat motif can drive membrane helix association, but the affinity is likely to be less strong than the previously reported right-handed motif described for glycophorin A.",1
"Lear, James D, Stouffer, Amanda L, Gratkowski, Holly, Nanda, Vikas, Degrado, William F",2
Checking the pH-induced conformational transition of prion protein by molecular dynamics simulations: effect of protonation of histidine residues.,0
"The role of acidic pH in the conversion of human prion protein to the pathogenic isoform is investigated by means of molecular dynamics simulations, focusing the attention on the effect of protonation of histidine residues on the conformational behavior of human PrPC globular domain. Our simulations reveal a significant loss of alpha-helix content under mildly acidic conditions, due to destructuration of the C-terminal part of HB (thus suggesting a possible involvement of HB into the conformational transition leading to the pathogenic isoform) and a transient lengthening of the native beta-sheet. Protonation of His-187 and His-155 seems to be crucial for the onset of the conformational rearrangement. This finding can be related to the existence of a pathogenic mutation, H187R, which is associated with GSS syndrome. Finally, the relevance of our results for the location of a Cu2+-binding pocket in the C-terminal part of the prion is discussed.",1
"Langella, Emma, Improta, Roberto, Barone, Vincenzo",2
Sampling the self-assembly pathways of KFFE hexamers.,0
"The formation of amyloid fibrils is often encountered in Alzheimer's disease, type II diabetes, and transmissible spongiform encephalopathies. In the last few years, however, mounting evidence has suggested that the soluble oligomers of amyloid-forming peptides are also cytotoxic agents. Understanding the early pathway steps of amyloid self-assembly at atomic detail might therefore be crucial for the development of specific inhibitors to prevent amyloidosis in humans. Using the activation-relaxation technique and a generic energy model, we study in detail the aggregation of a hexamer of KFFE peptide. Our simulations show that a monomer remains disordered, but that six monomers placed randomly in an open box self-associate to adopt, with various orientations, three possible distant low-energy structures. Two of these structures show a double-layer beta-sheet organization, in agreement with the structure of amyloid fibrils as observed by x-ray diffraction, whereas the third one consists of a barrel-like curved single-layer hexamer. Based on these results, we propose a bidirectional growth mode of amyloid fibril, involving alternate lateral and longitudinal growths.",1
"Wei, Guanghong, Mousseau, Normand, Derreumaux, Philippe",2
A single-molecule technique to study sequence-dependent transcription pausing.,0
"We present a technique that allows sequence-dependent analysis of transcription elongation using single-molecule optical trapping techniques. Observation of individual molecules of RNA polymerase (RNAP) allows determination of elongation kinetics that are difficult or impossible to accurately obtain from bulk studies, and provides high temporal resolution of the RNAP motion under a calibrated mechanical load. One limitation of previous single molecule studies was the difficulty in correlating the observed motion of RNAP with its actual position on the DNA template to better than approximately 100 bp. In this work, we improved the spatial precision of optical trapping studies of transcription to approximately 5 bp by using runoff transcription as an unambiguous marker of RNAP template position. This runoff method was sufficient to unequivocally locate and study a single known pause sequence (DeltatR2). By applying various loads to assist RNAP forward translocation, we specifically investigated elongation kinetics within this pause region and found that the dwell time at the pause sequence decreased with increasing assisting load. This observation is consistent with bulk biochemical studies that suggest RNAP reverse translocates, or ""backtracks,"" at the DeltatR2 pause sequence.",1
"Shundrovsky, Alla, Santangelo, Thomas J, Roberts, Jeffrey W, Wang, Michelle D",2
A model membrane protein for binding volatile anesthetics.,0
"Earlier work demonstrated that a water-soluble four-helix bundle protein designed with a cavity in its nonpolar core is capable of binding the volatile anesthetic halothane with near-physiological affinity (0.7 mM Kd). To create a more relevant, model membrane protein receptor for studying the physicochemical specificity of anesthetic binding, we have synthesized a new protein that builds on the anesthetic-binding, hydrophilic four-helix bundle and incorporates a hydrophobic domain capable of ion-channel activity, resulting in an amphiphilic four-helix bundle that forms stable monolayers at the air/water interface. The affinity of the cavity within the core of the bundle for volatile anesthetic binding is decreased by a factor of 4-3.1 mM Kd as compared to its water-soluble counterpart. Nevertheless, the absence of the cavity within the otherwise identical amphiphilic peptide significantly decreases its affinity for halothane similar to its water-soluble counterpart. Specular x-ray reflectivity shows that the amphiphilic protein orients vectorially in Langmuir monolayers at higher surface pressure with its long axis perpendicular to the interface, and that it possesses a length consistent with its design. This provides a successful starting template for probing the nature of the anesthetic-peptide interaction, as well as a potential model system in structure/function correlation for understanding the anesthetic binding mechanism.",1
"Ye, Shixin, Strzalka, Joseph, Churbanova, Inna Y, Zheng, Songyan, Johansson, Jonas S, Blasie, J Kent",2
Helical packing patterns in membrane and soluble proteins.,0
"This article presents the results of a detailed analysis of helix-helix interactions in membrane and soluble proteins. A data set of interacting pairs of helices in membrane proteins of known structure was constructed and a structure alignment algorithm was used to identify pairs of helices in soluble proteins that superimpose well with pairs of helices in the membrane-protein data set. Most helix pairs in membrane proteins are found to have a significant number of structural homologs in soluble proteins, although in some cases, primarily involving irregular helices, no close homologs exist. An analysis of geometric relationships between interacting helices in the two sets of proteins identifies some differences in the distributions of helix length, interfacial area, packing angle, and distance between the polypeptide backbones. However, a subset of soluble-protein helix pairs that are close structural homologs to membrane-protein helix pairs exhibits distributions that mirror those observed in membrane proteins. The larger average interface size and smaller distance of closest approach seen for helices in membrane proteins appears due in part to a relative enrichment of alanines and glycines, particularly as components of the AxxxA and GxxxG motifs. It is argued that membrane helices are not on average more tightly packed than helices in soluble proteins; they are simply able to approach each other more closely. This enables them to interact over longer distances, which may in turn facilitate their remaining in contact over much of the width of the lipid bilayer. The close structural similarity seen between some pairs of helices in membrane and soluble proteins suggests that packing patterns observed in soluble proteins may be useful in the modeling of membrane proteins. Moreover, there do not appear to be fundamental differences between the magnitude of the forces that drive helix packing in membrane and soluble proteins, suggesting that strategies to make membrane proteins more soluble by mutating surface residues are likely to encounter success, at least in some cases.",1
"Gimpelev, Marina, Forrest, Lucy R, Murray, Diana, Honig, Barry",2
Visualization and mechanical manipulations of individual fibrin fibers suggest that fiber cross section has fractal dimension 1.3.,0
"We report protocols and techniques to image and mechanically manipulate individual fibrin fibers, which are key structural components of blood clots. Using atomic force microscopy-based lateral force manipulations we determined the rupture force, FR, f fibrin fibers as a function of their diameter, D, in ambient conditions. As expected, the rupture force increases with increasing diameter; however, somewhat unexpectedly, it increases as FR approximately D1.30+/-0.06. Moreover, using a combined atomic force microscopy-fluorescence microscopy instrument, we determined the light intensity, I, of single fibers, that were formed with fluorescently labeled fibrinogen, as a function of their diameter, D. Similar to the force data, we found that the light intensity, and thus the number of molecules per cross section, increases as I approximately D1.25+/-0.11. Based on these findings we propose that fibrin fibers are fractals for which the number of molecules per cross section increases as about D1.3. This implies that the molecule density varies as rhoD approximately D -0.7, i.e., thinner fibers are denser than thicker fibers. Such a model would be consistent with the observation that fibrin fibers consist of 70-80% water and only 20-30% protein, which also suggests that fibrin fibers are very porous.",1
"Guthold, M, Liu, W, Stephens, B, Lord, S T, Hantgan, R R, Erie, D A, Taylor, R M, Superfine, R",2
Rheological analysis and measurement of neutrophil indentation.,0
"Aspects of neutrophil mechanical behavior relevant to the formation of adhesive contacts were assessed by measuring the dependence of the contact area between the cell and a spherical substrate under controlled loading. Micropipettes were used to bring neutrophils into contact with spherical beads under known forces, and the corresponding contact area was measured over time. The neutrophil was modeled as a viscous liquid drop with a constant cortical tension. Both the equilibrium state and the dynamics of the approach to equilibrium were examined. The equilibrium contact area increased monotonically with force in a manner consistent with a cell cortical tension of 16-24 pN/microm. The dynamic response matched predictions based on a model of the cell as a growing drop using published values for the effective viscosity of the cell. The contact pressure between the cell and substrate at equilibrium is predicted to depend on the curvature of the contacting substrate, but to be independent of the impingement force. The approach to equilibrium was rapid, such that the time-averaged stress for a two-second impingement was within 20% of the equilibrium value. These results have implications for the role of mechanical force in the formation of adhesive contacts.",1
"Lomakina, E B, Spillmann, C M, King, M R, Waugh, R E",2
Disposition of calcium release units in agarose gel for an optimal propagation of Ca2+ signals.,0
"Clusters of calcium-loaded sarcoplasmic reticulum (SR) vesicles in agarose gel were previously shown to behave as an excitable medium that propagates calcium waves. In a 3D-hexagonal disposition, the distance between neighboring spheres (which may stand for SR vesicles) is constant and the relationship between distance and vesicular protein concentration is expected to be nonlinear. To obtain a distribution of SR vesicles at different protein concentrations as homogeneous as possible, liquid agarose gels were carefully stirred. Electron micrographs, however, did not confirm the expected relationship between inter-SR vesicle distance and vesicular protein concentration. Light micrographs, to the contrary, resulted in a protein concentration-dependent disposition of clusters of SR vesicles, which is described by a linear function. Stable calcium waves in agarose gel occurred at SR vesicle protein concentrations between 7 and 16 g/l. At lower protein concentrations, local calcium oscillations or abortive waves were observed. The velocities of calcium waves were optimum at approximately 12 g/l and amounted to nearly 60 microm/s. The corresponding distance of neighboring calcium release units was calculated to be approximately 4 microm. The results further show that calcium signaling in the described reaction-diffusion system is optimal in a relatively small range of diffusion lengths. A change by +/-2 microm resulted in a reduction of the propagation velocity by 40%. It would appear that 1), the distance between calcium release units (clusters of ryanodine receptors in cells) is a sensitive parameter concerning propagation of Ca2+ signals; and 2), a dysfunction of the reaction-diffusion system in living cells, however, might have a negative effect on the spreading of intracellular calcium signals, thus on the cell's function.",1
"Wussling, Manfred H P, Aurich, Ines, Knauf, Oliver, Podhaisky, Helmut, Holzhausen, Hans-Jürgen",2
Computational protein design is a challenge for implicit solvation models.,0
"Increasingly complex schemes for representing solvent effects in an implicit fashion are being used in computational analyses of biological macromolecules. These schemes speed up the calculations by orders of magnitude and are assumed to compromise little on essential features of the solvation phenomenon. In this work we examine this assumption. Five implicit solvation models, a surface area-based empirical model, two models that approximate the generalized Born treatment and a finite difference Poisson-Boltzmann method are challenged in situations differing from those where these models were calibrated. These situations are encountered in automatic protein design procedures, whose job is to select sequences, which stabilize a given protein 3D structure, from a large number of alternatives. To this end we evaluate the energetic cost of burying amino acids in thousands of environments with different solvent exposures belonging, respectively, to decoys built with random sequences and to native protein crystal structures. In addition we perform actual sequence design calculations. Except for the crudest surface area-based procedure, all the tested models tend to favor the burial of polar amino acids in the protein interior over nonpolar ones, a behavior that leads to poor performance in protein design calculations. We show, on the other hand, that three of the examined models are nonetheless capable of discriminating between the native fold and many nonnative alternatives, a test commonly used to validate force fields. It is concluded that protein design is a particularly challenging test for implicit solvation models because it requires accurate estimates of the solvation contribution of individual residues. This contrasts with native recognition, which depends less on solvation and more on other nonbonded contributions.",1
"Jaramillo, Alfonso, Wodak, Shoshana J",2
Shape transitions and lattice structuring of ceramide-enriched domains generated by sphingomyelinase in lipid monolayers.,0
"Sphingomyelinases (SMases) hydrolyze the membrane constituent sphingomyelin (SM) to phosphocholine and ceramide (Cer). Growing evidence supports that SMase-induced SM-->Cer conversion leads to the formation of lateral Cer-enriched domains which drive structural reorganization in lipid membranes. We previously provided visual evidence in real-time for the formation of Cer-enriched domains in SM monolayers through the action of the neutral Bacillus cereus SMase. In this work, we disclose a succession of discrete morphologic transitions and lateral organization of Cer-enriched domains that underlay the SMase-generated surface topography. We further reveal how these structural parameters couple to the generation of two-dimensional electrostatic fields, based upon the specific orientation of the lipid dipole moments in the Cer-enriched domains. Advanced image processing routines in combination with time-resolved epifluorescence microscopy on Langmuir monolayers revealed: 1), spontaneous nucleation and circular growth of Cer-enriched domains after injection of SMase into the subphase of the SM monolayer; 2), domain-intrinsic discrete transitions from circular to periodically undulating shapes followed by a second transition toward increasingly branched morphologies; 3), lateral superstructure organization into predominantly hexagonal domain lattices; 4), formation of super-superstructures by the hexagonal lattices; and 5), rotationally and laterally coupled domain movement before domain border contact. All patterns proved to be specific for the SMase-driven system since they could not be observed with Cer-enriched domains generated by defined mixtures of SM/Cer in enzyme-free monolayers at the same surface pressure (pi = 10 mN/m). Following the theories of lateral shape transitions, dipolar electrostatic interactions of lipid domains, and direct determinations of the monolayer dipole potential, our data show that SMase induces a domain-specific packing and orientation of the molecular dipole moments perpendicular to the air/water interface. In consequence, protein-driven generation of specific out-of-equilibrium states, an accepted concept for maintenance of transmembrane lipid asymmetry, must also be considered on the lateral level. Lateral enzyme-specific out-of-equilibrium organization of lipid domains represents a new level of signal transduction from local (nm) to long-range (microm) scales. The cross-talk between lateral domain structures and dipolar electrostatic fields adds new perspectives to the mechanisms of SMase-mediated signal transduction in biological membranes.",1
"Härtel, Steffen, Fanani, María Laura, Maggio, Bruno",2
Cholesterol depletion suppresses the translational diffusion of class II major histocompatibility complex proteins in the plasma membrane.,0
"Glycosylphosphatidylinositol (GPI)-linked and native major histocompatibility complex class II I-E(k) were used as probes to determine the effect of varying cholesterol concentration on the mobility of proteins in the plasma membrane. These proteins were imaged in Chinese hamster ovary cells using single-molecule fluorescence microscopy. Observed diffusion coefficients of both native and GPI-linked I-E(k) proteins were found to depend on cholesterol concentration. As the cholesterol concentration decreases the diffusion coefficients decrease by up to a factor of 7 for native and 5 for GPI-linked I-E(k). At low cholesterol concentrations, after sphingomyelinase treatment, the diffusion coefficients are reduced by up to a factor of 60 for native and 190 for GPI-linked I-E(k). The effect is reversible on cholesterol reintroduction. Diffusion at all studied cholesterol concentrations, for both proteins, appears to be predominantly Brownian for time lags up to 2.5 s when imaged at 10 Hz. A decrease in diffusion coefficients is observed for other membrane proteins and lipid probes, DiIC12 and DiIC18. Fluorescence recovery after photobleaching measurements shows that the fraction of immobile lipid probe increases from 8 to approximately 40% after cholesterol extraction. These results are consistent with the previous work on cholesterol-phospholipid interactions. That is, cholesterol extraction destroys liquid cholesterol-phospholipid complexes, leaving solid-like high melting phospholipid domains that inhibit the lateral diffusion of membrane components.",1
"Vrljic, Marija, Nishimura, Stefanie Y, Moerner, W E, McConnell, Harden M",2
Mechanical properties of single myosin molecules probed with the photonic force microscope.,0
"To characterize elastic properties and geometrical parameters of individual, whole myosin molecules during their interaction with actin we sparsely adsorbed myosin molecules to nanometer-sized microspheres. Thermally driven position fluctuations of these microspheres were recorded with the three-dimensional detection scheme of the photonic force microscope. Upon binding of single myosin molecules to immobilized actin filaments in the absence of ATP, these thermally driven position fluctuations of the microspheres change significantly. From three-dimensional position fluctuations stiffness and geometrical information of the tethering molecule can be derived. Axial stiffness was found to be asymmetric, approximately 0.04 pN/nm for extension, approximately 0.004 pN/nm for compression. Observed stiffness of whole myosin molecules is much less than estimated for individual myosin heads in muscle fibers or for single-molecule studies on myosin fragments. The stiffness reported here, however, is identical to stiffness found in other single-molecule studies with full-length myosin suggesting that the source of this low stiffness is located outside the myosin head domain. Analysis of geometrical properties of tethering myosin molecules by Brownian dynamics computer simulations suggests a linker length of approximately 130 nm that is divided by a free hinge located approximately 90 nm above the substrate. This pivot location coincides with myosin's hinge region. We demonstrate the general applicability of thermal fluctuation analysis to determine elastic properties and geometrical factors of individual molecules.",1
"Scholz, Tim, Altmann, Stephan M, Antognozzi, Massimo, Tischer, Christian, Hörber, J-K Heinrich, Brenner, Bernhard",2
Interhelical spacing in liquid crystalline spermine and spermidine-DNA precipitates.,0
"The structure of polyamines-DNA precipitates was studied by x-ray diffraction. Precise measurements of the interhelix distance a(H) were obtained at different NaCl, polyamine, and DNA concentrations. Most of the results were obtained using spermine and few others using spermidine. The precipitates are liquid crystalline, either hexagonal and/or cholesteric, with an interhelical spacing that depends on the ionic concentrations and on the polyamine type. In our experimental conditions, the spacing varies from 28.15 to 33.4 angstroms. This variation is interpreted in terms of different ionic components that are present inside the precipitates and that are thought to regulate the value of the cohesive energy of DNA. These results are discussed in relation to the biological processes requiring a closeness of double helices and to the role played by polyamine analogs in cancer therapy.",1
"Raspaud, E, Durand, D, Livolant, F",2
Investigation of ligand binding to the multidrug resistance protein EmrE by isothermal titration calorimetry.,0
"Escherichia coli multidrug resistance protein E (EmrE) is an integral membrane protein spanning the inner membrane of Escherichia coli that is responsible for this organism's resistance to a variety of lipophilic cations such as quaternary ammonium compounds (QACs) and interchelating dyes. EmrE is a 12-kDa protein of four transmembrane helices considered to be functional as a multimer. It is an efflux transporter that can bind and transport cytoplasmic QACs into the periplasm using the energy of the proton gradient across the inner membrane. Isothermal titration calorimetry provides information about the stoichiometry and thermodynamic properties of protein-ligand interactions, and can be used to monitor the binding of QACs to EmrE in different membrane mimetic environments. In this study the ligand binding to EmrE solubilized in dodecyl maltoside, sodium dodecyl sulfate and reconstituted into small unilamellar vesicles is examined by isothermal titration calorimetry. The binding stoichiometry of EmrE to drug was found to be 1:1, demonstrating that oligomerization of EmrE is not necessary for binding to drug. The binding of EmrE to drug was observed with the dissociation constant (K(D)) in the micromolar range for each of the drugs in any of the membrane mimetic environments. Thermodynamic properties demonstrated this interaction to be enthalpy-driven with similar enthalpies of 8-12 kcal/mol for each of the drugs in any of the membrane mimetics.",1
"Sikora, Curtis W, Turner, Raymond J",2
A rapid fluorescence assay for FtsZ assembly indicates cooperative assembly with a dimer nucleus.,0
"FtsZ is the major cytoskeletal protein operating in bacterial cell division. FtsZ assembles into protofilaments in vitro, and there has been some controversy over whether the assembly is isodesmic or cooperative. Assembly has been assayed previously by sedimentation and light scattering. However, these techniques will under-report small polymers. We have now produced a mutant of Escherichia coli FtsZ, L68W, which gives a 250% increase in tryptophan fluorescence upon polymerization. This provides a real-time assay of polymer that is directly proportional to the concentration of subunit interfaces. FtsZ-L68W is functional for cell division, and should therefore be a valid model for studying the thermodynamics and kinetics of FtsZ assembly. We assayed assembly at pH 7.7 and pH 6.5, in 2.5 mM EDTA. EDTA blocks GTP hydrolysis and should give an assembly reaction that is not complicated by the irreversible hydrolysis step. Assembly kinetics was determined with a stopped-flow device for a range of FtsZ concentrations. When assembly was initiated by adding 0.2 mM GTP, fluorescence increase showed a lag, followed by nucleation, elongation, and a plateau. The assembly curves were fit to a cooperative mechanism that included a monomer activation step, a weak dimer nucleus, and elongation. Fragmentation was absent in the model, another characteristic of cooperative assembly. We are left with an enigma: how can the FtsZ protofilament, which appears to be one-subunit thick, assemble with apparent cooperativity?",1
"Chen, Yaodong, Bjornson, Keith, Redick, Sambra D, Erickson, Harold P",2
HERG channel (dys)function revealed by dynamic action potential clamp technique.,0
"The human ether-a-go-go-related gene (HERG) encodes the rapid component of the cardiac delayed rectifier potassium current (I(Kr)). Per-Arnt-Sim domain mutations of the HERG channel are linked to type 2 long-QT syndrome. We studied wild-type and/or type 2 long-QT syndrome-associated mutant (R56Q) HERG current (I(HERG)) in HEK-293 cells, at both 23 and 36 degrees C. Conventional voltage-clamp analysis revealed mutation-induced changes in channel kinetics. To assess functional implication(s) of the mutation, we introduce the dynamic action potential clamp technique. In this study, we effectively replace the native I(Kr) of a ventricular cell (either a human model cell or an isolated rabbit myocyte) with I(HERG) generated in a HEK-293 cell that is voltage-clamped by the free-running action potential of the ventricular cell. Action potential characteristics of the ventricular cells were effectively reproduced with wild-type I(HERG), whereas the R56Q mutation caused a frequency-dependent increase of the action potential duration in accordance with the clinical phenotype. The dynamic action potential clamp approach also revealed a frequency-dependent transient wild-type I(HERG) component, which is absent with R56Q channels. This novel electrophysiological technique allows rapid and unambiguous determination of the effects of an ion channel mutation on the ventricular action potential and can serve as a new tool for investigating cardiac channelopathies.",1
"Berecki, Géza, Zegers, Jan G, Verkerk, Arie O, Bhuiyan, Zahurul A, de Jonge, Berend, Veldkamp, Marieke W, Wilders, Ronald, van Ginneken, Antoni C G",2
Fluorescence imaging of two-photon linear dichroism: cholesterol depletion disrupts molecular orientation in cell membranes.,0
"The plasma membrane of cells is an ordered environment, giving rise to anisotropic orientation and restricted motion of molecules and proteins residing in the membrane. At the same time as being an organized matrix of defined structure, the cell membrane is heterogeneous and dynamic. Here we present a method where we use fluorescence imaging of linear dichroism to measure the orientation of molecules relative to the cell membrane. By detecting linear dichroism as well as fluorescence anisotropy, the orientation parameters are separated from dynamic properties such as rotational diffusion and homo energy transfer (energy migration). The sensitivity of the technique is enhanced by using two-photon excitation for higher photo-selection compared to single photon excitation. We show here that we can accurately image lipid organization in whole cell membranes and in delicate structures such as membrane nanotubes connecting two cells. The speed of our wide-field imaging system makes it possible to image changes in orientation and anisotropy occurring on a subsecond timescale. This is demonstrated by time-lapse studies showing that cholesterol depletion rapidly disrupts the orientation of a fluorophore located within the hydrophobic region of the cell membrane but not of a surface bound probe. This is consistent with cholesterol having an important role in stabilizing and ordering the lipid tails within the plasma membrane.",1
"Benninger, Richard K P, Onfelt, Björn, Neil, Mark A A, Davis, Daniel M, French, Paul M W",2
Modeling the effect of deregulated proliferation and apoptosis on the growth dynamics of epithelial cell populations in vitro.,0
"We present a three-dimensional individual cell-based, biophysical model to study the effect of normal and malfunctioning growth regulation and control on the spatial-temporal organization of growing cell populations in vitro. The model includes explicit representations of typical epithelial cell growth regulation and control mechanisms, namely 1), a cell-cell contact-mediated form of growth inhibition; 2), a cell-substrate contact-dependent cell-cycle arrest; and 3), a cell-substrate contact-dependent programmed cell death (anoikis). The model cells are characterized by experimentally accessible biomechanical and cell-biological parameters. First, we study by variation of these cell-specific parameters which of them affect the macroscopic morphology and growth kinetics of a cell population within the initial expanding phase. Second, we apply selective knockouts of growth regulation and control mechanisms to investigate how the different mechanisms collectively act together. Thereby our simulation studies cover the growth behavior of epithelial cell populations ranging from undifferentiated stem cell populations via transformed variants up to tumor cell lines in vitro. We find that the cell-specific parameters, and in particular the strength of the cell-substrate anchorage, have a significant impact on the population morphology. Furthermore, they control the efficacy of the growth regulation and control mechanisms, and consequently tune the transition from controlled to uncontrolled growth that is induced by the failures of these mechanisms. Interestingly, however, we find the qualitative and quantitative growth kinetics to be remarkably robust against variations of cell-specific parameters. We compare our simulation results with experimental findings on a number of epithelial and tumor cell populations and suggest in vitro experiments to test our model predictions.",1
"Galle, Jörg, Loeffler, Markus, Drasdo, Dirk",2
Mitochondrial Ca2+ dynamics reveals limited intramitochondrial Ca2+ diffusion.,0
"To reveal heterogeneity of mitochondrial function on the single-mitochondrion level we have studied the spatiotemporal dynamics of the mitochondrial Ca2+ signaling and the mitochondrial membrane potential using wide-field fluorescence imaging and digital image processing techniques. Here we demonstrate first-time discrete sites--intramitochondrial hotspots--of Ca2+ uptake after Ca2+ release from intracellular stores, and spreading of Ca2+ rise within the mitochondria. The phenomenon was characterized by comparison of observations in intact cells stimulated by ATP and in plasma membrane permeabilized or in ionophore-treated cells exposed to elevated buffer [Ca2+]. The findings indicate that Ca2+ diffuses laterally within the mitochondria, and that the diffusion is limited for shorter segments of the mitochondrial network. These observations were supported by mathematical simulation of buffered diffusion. The mitochondrial membrane potential was investigated using the potentiometric dye TMRM. Irradiation-induced fluctuations (flickering) of TMRM fluorescence showed synchronicity over large regions of the mitochondrial network, indicating that certain parts of this network form electrical syncytia. The spatial extension of these syncytia was decreased by 2-aminoethoxydiphenyl borate (2-APB) or by propranolol (blockers of nonclassical mitochondrial permeabilities). Our data suggest that mitochondria form syncytia of electrical conductance whereas the passage of Ca2+ is restricted to the individual organelle.",1
"Gerencser, Akos A, Adam-Vizi, Vera",2
Measurements of DNA lengths remaining in a viral capsid after osmotically suppressed partial ejection.,0
"The effect of external osmotic pressure on the extent of DNA ejection from bacteriophage-lambda was recently investigated (Evilevitch et al., 2003). The total length of DNA ejected was measured via the 260-nm absorption by free nucleotides, after opening of the capsids in the presence of varying amounts of polyethylene glycol 8000 and DNase I. As a function of osmolyte concentration, this absorption was shown to decrease progressively, ultimately vanishing completely for a sufficiently high external osmotic pressure. In this work we report the results of both sedimentation and gel analysis of the length of DNA remaining inside the capsids, as a function of osmolyte concentration. It is confirmed in this way that the progressive inhibition of DNA ejection corresponds to partial ejection from all of the capsids.",1
"Evilevitch, Alex, Gober, James W, Phillips, Martin, Knobler, Charles M, Gelbart, William M",2
Homology modeling and molecular dynamics simulations of transmembrane domain structure of human neuronal nicotinic acetylcholine receptor.,0
"A three-dimensional model of the transmembrane domain of a neuronal-type nicotinic acetylcholine receptor (nAChR), (alpha4)2(beta2)3, was constructed from a homology structure of the muscle-type nAChR recently determined by cryo-electron microscopy. The neuronal channel model was embedded in a fully hydrated DMPC lipid bilayer, and molecular-dynamics simulations were performed for 5 ns. A comparative analysis of the neuronal- versus muscle-type nAChR models revealed many conserved pore-lining residues, but an important difference was found near the periplasmic mouth of the pore. A flickering salt-bridge of alpha4-E266 with its adjacent beta2-K260 was observed in the neuronal-type channel during the course of the molecular-dynamics simulations. The narrowest region, with a pore radius of approximately 2 A formed by the salt-bridges, does not seem to be the restriction site for a continuous water passage. Instead, two hydrophobic rings, formed by alpha4-V259, alpha4-L263, and the homologous residues in the beta2-subunits, act as the gates for water flow, even though the region has a slightly larger pore radius. The model offers new insight into the water transport across the (alpha4)2(beta2)3 nAChR channel, and may lead to a better understanding of the structures, dynamics, and functions of this family of ion channels.",1
"Saladino, Alexander C, Xu, Yan, Tang, Pei",2
Rapid intracellular TEA block of the KcsA potassium channel.,0
Intracellular tetraethylammonium (TEA) inhibition was studied at the single-channel level in the KcsA potassium channel reconstituted in planar lipid bilayers. TEA acts as a fast blocker (resulting in decreased current amplitude) with an affinity in the 75 mM range even at high bandwidth. Studies over a wide voltage range reveal that TEA block has a complex voltage-dependence that also depends on the ionic conditions. These observations are examined in the context of permeation models to extend our understanding of the coupling between permeant ions and TEA blockade.,1
"Kutluay, Esin, Roux, Benoît, Heginbotham, Lise",2
"Functional characterization of mammalian inositol 1,4,5-trisphosphate receptor isoforms.",0
"Inositol 1,4,5-trisphosphate receptors (InsP3R) play a key role in intracellular calcium (Ca2+) signaling. Three mammalian InsP3R isoforms--InsP3R type 1 (InsP3R1), InsP3R type 2 (InsP3R2), and InsP3R type 3 (InsP3R3) are expressed in mammals, but the functional differences between the three mammalian InsP3R isoforms are poorly understood. Here we compared single-channel behavior of the recombinant rat InsP3R1, InsP3R2, and InsP3R3 expressed in Sf9 cells, reconstituted into planar lipid bilayers and recorded with 50 mM Ba2+ as a current carrier. We found that: 1), for all three mammalian InsP3R isoforms the size of the unitary current is 1.9 pA and single-channel conductance is 74-80 pS; 2), in optimal recording conditions the maximal single-channel open probability for all three mammalian InsP3R isoforms is in the range 30-40%; 3), in optimal recording conditions the mean open dwell time for all three mammalian InsP3R isoforms is 7-8 ms, the mean closed dwell time is approximately 10 ms; 4), InsP3R2 has the highest apparent affinity for InsP(3) (0.10 microM), followed by InsP3R1 (0.27 microM), and then by InsP3R3 (0.40 microM); 5), InsP3R1 has a high-affinity (0.13 mM) ATP modulatory site, InsP3R2 gating is ATP independent, and InsP3R3 has a low-affinity (2 mM) ATP modulatory site; 6), ATP modulates InsP3R1 gating in a noncooperative manner (n(Hill) = 1.3); 7), ATP modulates InsP3R3 gating in a highly cooperative manner (n(Hill) = 4.1). Obtained results provide novel information about functional properties of mammalian InsP3R isoforms.",1
"Tu, Huiping, Wang, Zhengnan, Nosyreva, Elena, De Smedt, Humbert, Bezprozvanny, Ilya",2
Effect of graded hydration on the dynamics of an ion channel peptide: a fluorescence approach.,0
"Water plays an important role in determining the folding, structure, dynamics, and, in turn, the function of proteins. We have utilized a combination of fluorescence approaches such as the wavelength-selective fluorescence approach to monitor the effect of varying degrees of hydration on the organization and dynamics of the functionally important tryptophan residues of gramicidin in reverse micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate. Our results show that tryptophans in gramicidin, present in the single-stranded beta6.3 conformation, experience slow solvent relaxation giving rise to red-edge excitation shift (REES). In addition, changes in fluorescence polarization with increasing excitation or emission wavelength reinforce that the gramicidin tryptophans are localized in motionally restricted regions of the reverse micelle. Interestingly, the extent of REES is found to be independent of the [water]/[surfactant] molar ratio (w(o)). We attribute this to heterogeneity in gramicidin tryptophan localization. Fluorescence intensity and mean fluorescence lifetime of the gramicidin tryptophans show significant reductions with increasing w(o) indicating sensitivity to increased polarity. Since the dynamics of hydration is related to folding, structure, and eventually function of proteins, we conclude that REES could prove to be a potentially sensitive tool to explore the dynamics of proteins under conditions of changing hydration.",1
"Kelkar, Devaki A, Chattopadhyay, Amitabha",2
Disentangling ligand migration and heme pocket relaxation in cytochrome P450cam.,0
"In this work we show that ligand migration and active site conformational relaxation can occur independently of each other in hemoproteins. The complicated kinetics of carbon monoxide rebinding with cytochrome P450cam display up to five distinct processes between 77 K and 300 K. They were disentangled by using a combination of three approaches: 1), the competition of the ligand with xenon for the occupation of internal protein cavities; 2), the modulation of the amount of distal steric hindrance within the heme pocket by varying the nature of the substrate; and 3), molecular mechanics calculations to support the proposed heme-substrate relaxation mechanism and to seek internal cavities. In cytochrome P450cam, active site conformational relaxation results from the displacement of the substrate toward the heme center upon photodissociation of the ligand. It is responsible for the long, puzzling bimodal nature of the rebinding kinetics observed down to 77 K. The relaxation rate is strongly substrate-dependent. Ligand migration is slower and is observed only above 135 K. Migration and return rates are independent of the substrate.",1
"Tetreau, Catherine, Mouawad, Liliane, Murail, Samuel, Duchambon, Patricia, Blouquit, Yves, Lavalette, Daniel",2
Pressure equilibrium and jump study on unfolding of 23-kDa protein from spinach photosystem II.,0
"Pressure-induced unfolding of 23-kDa protein from spinach photosystem II has been systematically investigated at various experimental conditions. Thermodynamic equilibrium studies indicate that the protein is very sensitive to pressure. At 20 degrees C and pH 5.5, 23-kDa protein shows a reversible two-state unfolding transition under pressure with a midpoint near 160 MPa, which is much lower than most natural proteins studied to date. The free energy (DeltaG(u)) and volume change (DeltaV(u)) for the unfolding are 5.9 kcal/mol and -160 ml/mol, respectively. It was found that NaCl and sucrose significantly stabilize the protein from unfolding and the stabilization is associated not only with an increase in DeltaG(u) but also with a decrease in DeltaV(u). The pressure-jump studies of 23-kDa protein reveal a negative activation volume for unfolding (-66.2 ml/mol) and a positive activation volume for refolding (84.1 ml/mol), indicating that, in terms of system volume, the protein transition state lies between the folded and unfolded states. Examination of the temperature effect on the unfolding kinetics indicates that the thermal expansibility of the transition state and the unfolded state of 23-kDa protein are closer to each other and they are larger than that of the native state. The diverse pressure-refolding pathways of 23-kDa protein in some conditions were revealed in pressure-jump kinetics.",1
"Tan, Cui-Yan, Xu, Chun-He, Wong, Jun, Shen, Jian-Ren, Sakuma, Shinsuke, Yamamoto, Yasusi, Lange, Reinhard, Balny, Claude, Ruan, Kang-Cheng",2
An analysis of core deformations in protein superfamilies.,0
"An analysis is presented on how structural cores modify their shape across homologous proteins, and whether or not a relationship exists between these structural changes and the vibrational normal modes that proteins experience as a result of the topological constraints imposed by the fold. A set of 35 representative, well-populated protein families is studied. The evolutionary directions of deformation are obtained by using multiple structural alignments to superimpose the structures and extract a conserved core, together with principal components analysis to extract the main deformation modes from the three-dimensional superimposition. In parallel, a low-resolution normal mode analysis technique is employed to study the properties of the mechanical core plasticity of these same families. We show that the evolutionary deformations span a low dimensional space of 4-5 dimensions on average. A statistically significant correspondence exists between these principal deformations and the approximately 20 slowest vibrational modes accessible to a particular topology. We conclude that, to a significant extent, the structural response of a protein topology to sequence changes takes place by means of collective deformations along combinations of a small number of low-frequency modes. The findings have implications in structure prediction by homology modeling.",1
"Leo-Macias, Alejandra, Lopez-Romero, Pedro, Lupyan, Dmitry, Zerbino, Daniel, Ortiz, Angel R",2
Unfolding studies on soybean agglutinin and concanavalin a tetramers: a comparative account.,0
"The unfolding pathway of two very similar tetrameric legume lectins soybean agglutinin (SBA) and Concanavalin A (ConA) were determined using GdnCl-induced denaturation. Both proteins displayed a reversible two-state unfolding mechanism. The analysis of isothermal denaturation data provided values for conformational stability of the two proteins. It was found that the DeltaG of unfolding of SBA was much higher than ConA at all the temperatures at which the experiments were done. ConA had a T(g) 18 degrees C less than SBA. The higher conformational stability of SBA in comparison to ConA is largely due to substantial differences in their degrees of subunit interactions. Ionic interactions at the interface of the two proteins especially at the noncanonical interface seem to play a significant role in the observed stability differences between these two proteins. Furthermore, SBA is a glycoprotein with a GlcNac2Man9 chain attached to Asn-75 of each subunit. The sugar chain in SBA lies at the noncanonical interface of the protein, and it is found to interact with the amino acid residues in the adjacent noncanonical interface. These interactions further stabilize SBA with respect to ConA, which is not glycosylated.",1
"Sinha, Sharmistha, Mitra, Nivedita, Kumar, Gyanendra, Bajaj, Kanika, Surolia, Avadhesha",2
Real-time measurements of actin filament polymerization by total internal reflection fluorescence microscopy.,0
"Understanding the mechanism of actin polymerization and its regulation by associated proteins requires an assay to monitor polymerization dynamics and filament topology simultaneously. The only assay meeting these criteria is total internal reflection fluorescence microscopy (Amann and Pollard, 2001; Fujiwara et al., 2002). The fluorescence signal is fourfold stronger with actin labeled on Cys-374 with Oregon green rather than rhodamine. To distinguish growth at barbed and pointed ends we used image drift correction and maximum intensity projections to reveal points where single N-ethylmaleimide inactivated myosins attach filaments to the glass coverslip. We estimated association rates at high actin concentrations and dissociation rates near and below the critical actin concentration. At the barbed end, the association rate constant for Mg-ATP-actin is 7.4 microM(-1) s(-1) and the dissociation rate constant is 0.89 s(-1). At the pointed end the association and dissociation rate constants are 0.56 microM(-1) s(-1) and 0.19 s(-1). When vitamin D binding protein sequesters all free monomers, ADP-actin dissociates from barbed ends at 1.4 s(-1) and from pointed ends at 0.16 s(-1) regardless of buffer nucleotide.",1
"Kuhn, Jeffrey R, Pollard, Thomas D",2
Measuring unfolding of proteins in the presence of denaturant using fluorescence correlation spectroscopy.,0
"IFABP is a small (15 kDa) protein consisting mostly of antiparallel beta-strands that surround a large cavity into which ligands bind. We have previously used FCS to show that the native protein, labeled with fluorescein, exhibits dynamic fluctuation with a relaxation time of 35 micros. Here we report the use of FCS to study the unfolding of the protein induced by guanidine hydrochloride. Although the application of this technique to measure diffusion coefficients and molecular dynamics is straightforward, the FCS results need to be corrected for both viscosity and refractive index changes as the guanidine hydrochloride concentration increases. We present here a detailed study of the effects of viscosity and refractive index of guanidine hydrochloride solutions to calibrate FCS data. After correction, the increase in the diffusion time of IFABP corresponds well with the unfolding transition monitored by far ultraviolet circular dichroism. We also show that the magnitude of the 35 micros phase, reflecting the conformational fluctuation in the native state, decreases sharply as the concentration of denaturant increases and the protein unfolds. Although FCS experiments indicate that the unfolded state at pH 2 is rather compact and native-like, the radius in the presence of guanidine hydrochloride falls well within the range expected for a random coil.",1
"Chattopadhyay, Krishnananda, Saffarian, Saveez, Elson, Elliot L, Frieden, Carl",2
"Thin bio-artificial tissues in plane stress: the relationship between cell and tissue strain, and an improved constitutive model.",0
"Constitutive models are needed to relate the active and passive mechanical properties of cells to the overall mechanical response of bio-artificial tissues. The Zahalak model attempts to explicitly describe this link for a class of bio-artificial tissues. A fundamental assumption made by Zahalak is that cells stretch in perfect registry with a tissue. We show this assumption to be valid only for special cases, and we correct the Zahalak model accordingly. We focus on short-term and very long-term behavior, and therefore consider tissue constituents that are linear in their loading response (although not necessarily linear in unloading). In such cases, the average strain in a cell is related to the macroscopic tissue strain by a scalar we call the ""strain factor"". We incorporate a model predicting the strain factor into the Zahalak model, and then reinterpret experiments reported by Zahalak and co-workers to determine the in situ stiffness of cells in a tissue construct. We find that, without the modification in this article, the Zahalak model can underpredict cell stiffness by an order of magnitude.",1
"Marquez, J Pablo, Genin, Guy M, Zahalak, George I, Elson, Elliot L",2
The relationship between cell and tissue strain in three-dimensional bio-artificial tissues.,0
"Continuum constitutive laws are needed to ensure that bio-artificial tissue constructs replicate the mechanical response of the tissues they replace, and to understand how the constituents of these constructs contribute to their overall mechanical response. One model designed to achieve both of these aims is the Zahalak model, which was modified by Marquez and co-workers to incorporate inhomogeneous strain fields within very thin tissues. When applied to reinterpret previous measurements, the modified Zahalak model predicted higher values of the continuum stiffness of fibroblasts than earlier estimates. In this work, we further modify the Zahalak model to account for inhomogeneous strain fields in constructs whose cell orientations have a significant out-of-plane component. When applied to reinterpret results from the literature, the new model shows that estimates of continuum cell stiffness might need to be revised upward. As in this article's companion, we updated the average cell strain by defining a correction factor (""strain factor""), based upon the elastic response. Three different cell orientation distributions were studied. We derived an approximate scaling model for the strain factor, and validated it against exact and self-consistent (mean-field) solutions from the literature for dilute cell concentrations, and Monte Carlo simulations involving three-dimensional finite element analyses for high cell concentrations.",1
"Marquez, J Pablo, Genin, Guy M, Zahalak, George I, Elson, Elliot L",2
Elucidating protein thermodynamics from the three-dimensional structure of the native state using network rigidity.,0
"Given the three-dimensional structure of a protein, its thermodynamic properties are calculated using a recently introduced distance constraint model (DCM) within a mean-field treatment. The DCM is constructed from a free energy decomposition that partitions microscopic interactions into a variety of constraint types, i.e., covalent bonds, salt-bridges, hydrogen-bonds, and torsional-forces, each associated with an enthalpy and entropy contribution. A Gibbs ensemble of accessible microstates is defined by a set of topologically distinct mechanical frameworks generated by perturbing away from the native constraint topology. The total enthalpy of a given framework is calculated as a linear sum of enthalpy components over all constraints present. Total entropy is generally a nonadditive property of free energy decompositions. Here, we calculate total entropy as a linear sum of entropy components over a set of independent constraints determined by a graph algorithm that builds up a mechanical framework one constraint at a time, placing constraints with lower entropy before those with greater entropy. This procedure provides a natural mechanism for enthalpy-entropy compensation. A minimal DCM with five phenomenological parameters is found to capture the essential physics relating thermodynamic response to network rigidity. Moreover, two parameters are fixed by simultaneously fitting to heat capacity curves for histidine binding protein and ubiquitin at five different pH conditions. The three free parameter DCM provides a quantitative characterization of conformational flexibility consistent with thermodynamic stability. It is found that native hydrogen bond topology provides a key signature in governing molecular cooperativity and the folding-unfolding transition.",1
"Jacobs, Donald J, Dallakyan, Sargis",2
Disruption of protein-mediated DNA looping by tension in the substrate DNA.,0
"Protein-mediated DNA looping is important in a variety of biological processes, including gene regulation and genetic transformation. Although the biochemistry of loop formation is well established, the mechanics of loop closure in a constrained cellular environment has received less attention. Recent single molecule measurements show that mechanical constraints have a significant impact on DNA looping and motivate the need for a more comprehensive characterization of the effects of tension. By modeling DNA as a wormlike chain, we calculate how continuous stretching of the substrate DNA affects the loop formation probability. We find that when the loop size is >100 bp, a tension of 500 fN can increase the time required for loop closure by two orders of magnitude. This force is small compared to the piconewton forces that are associated with RNA polymerases and other molecular motors, indicating that intracellular mechanical forces might affect transcriptional regulation. In contrast to existing theory, we find that for loops <200 bp, the effect of tension is partly dependent on the relative orientation of the DNA-binding domains in the linker protein. Our results provide perspective on recent DNA looping experiments and suggestions for future micromechanical studies.",1
"Blumberg, Seth, Tkachenko, Alexei V, Meiners, Jens-Christian",2
Domain formation induced by the adsorption of charged proteins on mixed lipid membranes.,0
"Peripheral proteins can trigger the formation of domains in mixed fluid-like lipid membranes. We analyze the mechanism underlying this process for proteins that bind electrostatically onto a flat two-component membrane, composed of charged and neutral lipid species. Of particular interest are membranes in which the hydrocarbon lipid tails tend to segregate owing to nonideal chain mixing, but the (protein-free) lipid membrane is nevertheless stable due to the electrostatic repulsion between the charged lipid headgroups. The adsorption of charged, say basic, proteins onto a membrane containing anionic lipids induces local lipid demixing, whereby charged lipids migrate toward (or away from) the adsorption site, so as to minimize the electrostatic binding free energy. Apart from reducing lipid headgroup repulsion, this process creates a gradient in lipid composition around the adsorption zone, and hence a line energy whose magnitude depends on the protein's size and charge and the extent of lipid chain nonideality. Above a certain critical lipid nonideality, the line energy is large enough to induce domain formation, i.e., protein aggregation and, concomitantly, macroscopic lipid phase separation. We quantitatively analyze the thermodynamic stability of the dressed membrane based on nonlinear Poisson-Boltzmann theory, accounting for both the microscopic characteristics of the proteins and lipid composition modulations at and around the adsorption zone. Spinodal surfaces and critical points of the dressed membranes are calculated for several different model proteins of spherical and disk-like shapes. Among the models studied we find the most substantial protein-induced membrane destabilization for disk-like proteins whose charges are concentrated in the membrane-facing surface. If additional charges reside on the side faces of the proteins, direct protein-protein repulsion diminishes considerably the propensity for domain formation. Generally, a highly charged flat face of a macroion appears most efficient in inducing large compositional gradients, hence a large and unfavorable line energy and consequently lateral macroion aggregation and, concomitantly, macroscopic lipid phase separation.",1
"Mbamala, Emmanuel C, Ben-Shaul, Avinoam, May, Sylvio",2
Functional interaction of CaV channel isoforms with ryanodine receptors studied in dysgenic myotubes.,0
"The L-type Ca(2+) channels Ca(V)1.1 (alpha(1S)) and Ca(V)1.2 (alpha(1C)) share properties of targeting but differ by their mode of coupling to ryanodine receptors in muscle cells. The brain isoform Ca(V)2.1 (alpha(1A)) lacks ryanodine receptor targeting. We studied these three isoforms in myotubes of the alpha(1S)-deficient skeletal muscle cell line GLT under voltage-clamp conditions and estimated the flux of Ca(2+) (Ca(2+) input flux) resulting from Ca(2+) entry and release. Surprisingly, amplitude and kinetics of the input flux were similar for alpha(1C) and alpha(1A) despite a previously reported strong difference in responsiveness to extracellular stimulation. The kinetic flux characteristics of alpha(1C) and alpha(1A) resembled those in alpha(1S)-expressing cells but the contribution of Ca(2+) entry was much larger. alpha(1C) but not alpha(1A)-expressing cells revealed a distinct transient flux component sensitive to sarcoplasmic reticulum depletion by 30 microM cyclopiazonic acid and 10 mM caffeine. This component likely results from synchronized Ca(2+)-induced Ca(2+) release that is absent in alpha(1A)-expressing myotubes. In cells expressing an alpha(1A)-derivative (alpha(1)Aas(1592-clip)) containing the putative targeting sequence of alpha(1S), a similar transient component was noticeable. Yet, it was considerably smaller than in alpha(1C), indicating that the local Ca(2+) entry produced by the chimera is less effective in triggering Ca(2+) release despite similar global Ca(2+) inward current density.",1
"Schuhmeier, Ralph Peter, Gouadon, Elodie, Ursu, Daniel, Kasielke, Nicole, Flucher, Bernhard E, Grabner, Manfred, Melzer, Werner",2
"Simulation studies of protein-induced bilayer deformations, and lipid-induced protein tilting, on a mesoscopic model for lipid bilayers with embedded proteins.",0
"Biological membranes are complex and highly cooperative structures. To relate biomembrane structure to their biological function it is often necessary to consider simpler systems. Lipid bilayers composed of one or two lipid species, and with embedded proteins, provide a model system for biological membranes. Here we present a mesoscopic model for lipid bilayers with embedded proteins, which we have studied with the help of the dissipative particle dynamics simulation technique. Because hydrophobic matching is believed to be one of the main physical mechanisms regulating lipid-protein interactions in membranes, we considered proteins of different hydrophobic length (as well as different sizes). We studied the cooperative behavior of the lipid-protein system at mesoscopic time- and lengthscales. In particular, we correlated in a systematic way the protein-induced bilayer perturbation, and the lipid-induced protein tilt, with the hydrophobic mismatch (positive and negative) between the protein hydrophobic length and the pure lipid bilayer hydrophobic thickness. The protein-induced bilayer perturbation was quantified in terms of a coherence length, xi(P), of the lipid bilayer hydrophobic thickness profile around the protein. The dependence on temperature of xi(P), and the protein tilt-angle, were studied above the main-transition temperature of the pure system, i.e., in the fluid phase. We found that xi(P) depends on mismatch, i.e., the higher the mismatch is, the longer xi(P) becomes, at least for positive values of mismatch; a dependence on the protein size appears as well. In the case of large model proteins experiencing extreme mismatch conditions, in the region next to the so-called lipid annulus, there appears an undershooting (or overshooting) region where the bilayer hydrophobic thickness is locally lower (or higher) than in the unperturbed bilayer, depending on whether the protein hydrophobic length is longer (or shorter) than the pure lipid bilayer hydrophobic thickness. Proteins may tilt when embedded in a too-thin bilayer. Our simulation data suggest that, when the embedded protein has a small size, the main mechanism to compensate for a large hydrophobic mismatch is the tilt, whereas large proteins react to negative mismatch by causing an increase of the hydrophobic thickness of the nearby bilayer. Furthermore, for the case of small, peptidelike proteins, we found the same type of functional dependence of the protein tilt-angle on mismatch, as was recently detected by fluorescence spectroscopy measurements.",1
"Venturoli, Maddalena, Smit, Berend, Sperotto, Maria Maddalena",2
"2H-NMR study and molecular dynamics simulation of the location, alignment, and mobility of pyrene in POPC bilayers.",0
"The alignment of pyrene in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer was investigated using two different approaches, namely solid-state (2)H-NMR spectroscopy and molecular dynamics (MD) simulations. Quadrupolar splittings from (2)H-NMR spectra of deuterated pyrene-d(10) in an oriented lipid bilayer give information about the orientation of C-D bonds with respect to the membrane normal. From MD simulations, geometric information is accessible via trajectories. By defining molecular and bond order parameters, the data from MD trajectories and NMR spectra can be compared straightforwardly. To ensure that the results from both methods are comparable, parameters of the experimental and the simulation setup were chosen to be as similar as possible. From simulations, we saw that pyrene prefers a position inside the lipid membrane near the headgroups and has no tendency to diffuse from one monolayer of the membrane to the other. The results from simulation and NMR show that the normal of the molecular plane is aligned nearly perpendicular to the bilayer normal. The long axis of pyrene lies preferentially parallel to the bilayer normal within a range of +/-30 degrees . The results from the two different methods are remarkably consistent. The good agreement can be explained by the fact that the different kind of motions of a pyrene molecule are already averaged within a few nanoseconds, which is the timescale covered by the MD simulation.",1
"Hoff, Barbara, Strandberg, Erik, Ulrich, Anne S, Tieleman, D Peter, Posten, Clemens",2
Membrane lateral mobility obstructed by polymer-tethered lipids studied at the single molecule level.,0
"Obstructed long-range lateral diffusion of phospholipids (TRITC-DHPE) and membrane proteins (bacteriorhodopsin) in a planar polymer-tethered 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer is studied using wide-field single molecule fluorescence microscopy. The obstacles are well-controlled concentrations of hydrophobic lipid-mimicking dioctadecylamine moieties in the polymer-exposed monolayer of the model membrane. Diffusion of both types of tracer molecules is well described by a percolating system with different percolation thresholds for lipids and proteins. Data analysis using a free area model of obstructed lipid diffusion indicates that phospholipids and tethered lipids interact via hard-core repulsion. A comparison to Monte Carlo lattice calculations reveals that tethered lipids act as immobile obstacles, are randomly distributed, and do not self-assemble into large-scale aggregates for low to moderate tethering concentrations. A procedure is presented to identify anomalous subdiffusion from tracking data at a single time lag. From the analysis of the cumulative distribution function of the square displacements, it was found that TRITC-DHPE and W80i show normal diffusion at lower concentrations of tethered lipids and anomalous diffusion at higher ones. This study may help improve our understanding of how lipids and proteins in biomembranes may be obstructed by very small obstacles comprising only one or very few molecules.",1
"Deverall, M A, Gindl, E, Sinner, E-K, Besir, H, Ruehe, J, Saxton, M J, Naumann, C A",2
Strong binding of myosin heads stretches and twists the actin helix.,0
"Calculation of the size of the power stroke of the myosin motor in contracting muscle requires knowledge of the compliance of the myofilaments. Current estimates of actin compliance vary significantly introducing uncertainty in the mechanical parameters of the motor. Using x-ray diffraction on small bundles of permeabilized fibers from rabbit muscle we show that strong binding of myosin heads changes directly the actin helix. The spacing of the 2.73-nm meridional x-ray reflection increased by 0.22% when relaxed fibers were put into low-tension rigor (<10 kN/m(2)) demonstrating that strongly bound myosin heads elongate the actin filaments even in the absence of external tension. The pitch of the 5.9-nm actin layer line increased by approximately 0.62% and that of the 5.1-nm layer line decreased by approximately 0.26%, suggesting that the elongation is accompanied by a decrease in its helical angle (approximately 166 degrees) by approximately 0.8 degrees. This effect explains the difference between actin compliance revealed from mechanical experiments with single fibers and from x-ray diffraction on whole muscles. Our measurement of actin compliance obtained by applying tension to fibers in rigor is consistent with the results of mechanical measurements.",1
"Tsaturyan, Andrey K, Koubassova, Natalia, Ferenczi, Michael A, Narayanan, Theyencheri, Roessle, Manfred, Bershitsky, Sergey Y",2
Cerebrospinal fluid in the diagnosis of multiple sclerosis: a consensus report.,0
"The Committee of the European Concerted Action for Multiple Sclerosis (Charcot Foundation) organised five workshops to discuss CSF analytical standards in the diagnosis of multiple sclerosis. This consensus report from 12 European countries summarises the results of those workshops. It is hoped that neurologists will confer with their colleagues in clinical chemistry to arrange the best possible local practice. The most sensitive method for the detection of oligoclonal immunoglobulin bands is isoelectric focusing. The same amounts of IgG in parallel CSF and serum samples are used and oligoclonal bands are revealed with IgG specific antibody staining. All laboratories performing isoelectric focusing should check their technique at least annually using ""blind"" standards for the five different CSF and serum patterns. Quantitative measurements of IgG production in the CNS are less sensitive than isoelectric focusing. The preferred method for detection of blood-CSF barrier dysfunction is the albumin quotient. The CSF albumin or total protein concentrations are less satisfactory. These results must be interpreted with reference to the age of the patient and the local method of determination. Cells should be counted. The normal value is no more than 4 cells/microliters. Among evolving optional tests, measurement of the combined local synthesis of antibodies against measles, rubella, and/or varicella zoster could represent a significant advance if it offers higher specificity (not sensitivity) for identifying chronic rather than acute inflammation. Other tests that may have useful correlations with clinical indices include those for oligoclonal free light chains, IgM, IgA, or myelin basic protein concentrations.",1
"Andersson, M, Alvarez-Cermeño, J, Bernardi, G, Cogato, I, Fredman, P, Frederiksen, J, Fredrikson, S, Gallo, P, Grimaldi, L M, Grønning, M",2
"Spectrum of primary intracerebral haemorrhage in Perth, Western Australia, 1989-90: incidence and outcome.",0
"In a population based register of stroke (n = 536) compiled in Perth, Western Australia during an 18 month period in 1989-90, 60 cases (11%) of primary intracerebral haemorrhage were identified among 56 persons (52% men). The mean age of these patients was 68 (range 23-93) and 46 (77%) events were first ever strokes. The crude annual incidence was 35 per 100,000, with a peak in the eighth decade, and a male predominance. Deep and lobar haemorrhages each accounted for almost one third of all cases. The clinical presentations included sudden coma (12%), headache (8%), seizures (8%), and pure sensory-motor stroke (3%). Primary intracerebral haemorrhage was the first presentation of leukaemia in two cases (both fatal) and it followed an alcoholic binge in four cases. 55% had a history of hypertension. 16 (27%) patients, half of whom had a history of hypertension, were taking antiplatelet agents, and one patient was taking warfarin. There were only two confirmed cases of amyloid angiopathy. The overall 28 day case fatality was 35%, but this varied from 100% for haemorrhages in the brainstem to 22% for those in the basal ganglionic or thalamic region. Other predictors of early death were intraventricular extension of blood, volume of haematoma, mass effect, and coma and severe paresis at onset. Although based on small numbers, these data confirm the heterogeneous nature of primary intracerebral haemorrhage, but they also suggest a different clinical spectrum of this type of stroke in the community compared with the experience of specialist neurological units.",1
"Anderson, C S, Chakera, T M, Stewart-Wynne, E G, Jamrozik, K D",2
Sensory conduction study in chronic sensory ataxic neuropathy.,0
"Sensory conduction was studied in six patients with chronic sensory ataxic neuropathy of an idiopathic type and associated with Sjögren's syndrome. Motor nerve conduction velocities were normal in most cases, but sensory nerve potentials could not be evoked in a routine peripheral nerve conduction study. Cortical and cervical somatosensory evoked potentials (SEPs) and evoked potentials from Erb's point were barely recorded by median nerve stimulation at the wrist. When the median nerve was stimulated at more proximal points, clear potentials were recorded from Erb's point, but cortical SEPs were still hardly elicited. Thus the sensory nerves are centrally and peripherally involved in this condition, and the involvement is more prominent in the distal portion in the peripheral nerve. These findings suggest that central-peripheral distal axonopathy is a process involved in this illness and that the dorsal root ganglia may be primarily involved, in accord with previous pathological studies.",1
"Kachi, T, Sobue, G, Yamamoto, M, Igata, A",2
Surgical treatment of brain metastases of lung cancer: retrospective analysis of 89 cases.,0
"The records of 89 patients who underwent surgery for solitary or multiple parenchymal brain metastases of lung cancer at the Osaka Center for Adult Diseases between 1978 and 1990 were reviewed with follow up until March 1992. The aim of this retrospective analysis was to identify prognostic features that were associated with a favourable outcome. The benefits of brain tumour surgery were evaluated in terms of the cause of death (brain metastasis, tumour in another organ, or treatment related) as well as the postoperative changes in functional state indicated by the Karnofsky scale. The overall mean survival time was 11.6 months, and the one and two year survival rates were 24% and 8%. The brain lesion itself was the cause of death in only 19% of the patients; the other 81% died of systemic disease. Functional state improved after surgical excision of the brain tumour in 36%, remained unchanged in 53%, and worsened in 11%. These data suggest that surgical intervention is beneficial for patients with parenchymal brain metastases. Variables significantly associated with a favourable prognosis included surgical excision of the primary lesion, adenocarcinoma as the histological diagnosis, the use of adjuvant treatment, especially chemotherapy, a preoperative score of over 80% on the Karnofsky scale, and metastasis confined to the brain with no extracranial metastatic foci or residual primary tumour. Additional but non-significant contributors to a good prognosis included age under 65 or 70 years, early tumour stage (stage 1), curative lung cancer surgery, a single metastatic brain tumour (v multiple lesions), a solid tumour (v cystic), and a supratentorial location of the brain metastasis. The disease free interval and the cerebrospinal fluid cytology were not significant prognostic factors. On the basis of these findings, it is concluded that the surgical removal of brain metastases of lung cancer should be undertaken if the primary tumour has already been removed whether or not there are extracranial metastases, and that postoperative chemotherapy should generally be given.",1
"Nakagawa, H, Miyawaki, Y, Fujita, T, Kubo, S, Tokiyoshi, K, Tsuruzono, K, Kodama, K, Higashiyama, M, Doi, O, Hayakawa, T",2
The earliest cognitive change in a person with familial Alzheimer's disease: presymptomatic neuropsychological features in a pedigree with familial Alzheimer's disease confirmed at necropsy.,0
"Comprehensive, longitudinal neuropsychological assessments are reported in a person ""at risk"" from autosomal dominant, necropsy confirmed familial Alzheimer's disease. The first assessment showed a moderately selective verbal memory deficit in the context of mild general intellectual impairment. Subsequent testing showed the progressive deterioration of visual memory and a mild decline of perceptual and spatial skills. Language and literacy skills, however, remained comparatively intact. The neuropsychological profiles obtained at each assessment are presented in profile maps. These permit direct longitudinal comparison of cognitive function, and may serve in the comparison of different potential cases of familial Alzheimer's disease. This case sought medical attention for memory difficulties 26 months after the first neuropsychological assessment. These results mark the first cognitive manifestations in a pedigree with familial Alzheimer's disease which, in this case, were seen presymptomatically. The findings are discussed in relation to neuropsychological studies of affected cases, and in terms of their reflecting the heterogeneous nature of familial Alzheimer's disease.",1
"Newman, S K, Warrington, E K, Kennedy, A M, Rossor, M N",2
Peripheral neuropathy associated with primary Sjögren's syndrome.,0
"Clinical and electrophysiological signs of peripheral neuropathy were found in 10 of 46 patients (21.7%) with primary Sjögren's syndrome, symmetric polyneuropathy in seven (mainly sensory in five, mainly autonomic in two), sensory neuronopathy in two patients, and mononeuropathy multiplex in one patient. Peripheral neuropathy was the presenting manifestation in five patients (10.9%). Onset of the disease after 50 years was significantly more common in the polyneuropathy group (six of seven) than in non-neuropathic patients with primary Sjögren's syndrome (14 of 36; p = 0.034). No other difference in clinical or laboratory variables between neuropathic and non-neuropathic patients with primary Sjogren's syndrome was found. Neurophysiological study showed variable findings predominantly suggesting an axonopathy. Nerve biopsy showed moderate remyelination and regeneration in four patients, and fibre loss, mainly of large size, in three. Necrotising vasculitis was not seen but alterations of the endoneurial microvessels were prominent.",1
"Gemignani, F, Marbini, A, Pavesi, G, Di Vittorio, S, Manganelli, P, Cenacchi, G, Mancia, D",2
Rest tremor and extrapyramidal symptoms after midbrain haemorrhage: clinical and 18F-dopa PET evaluation.,0
A 25 year old man had an acute subarachnoid haemorrhage due to the rupture of a right peduncular subthalamic arteriovenous malformation. Seven months later he developed a left rest tremor associated with mild bilateral extrapyramidal symptoms and responsive to levodopa treatment. Surface EMG recording showed synchronous activity of agonist and antagonist muscles in the left limbs. A PET 18F-dopa study showed a large decrease of the Ki value in the right striatum. One year after the stroke a persistent postural component developed in the tremor.,1
"Defer, G L, Remy, P, Malapert, D, Ricolfi, F, Samson, Y, Degos, J D",2
Apomorphine induced cognitive changes in Parkinson's disease.,0
"Auditory event related potentials (ERPs) and visual evoked potentials (VEPs) were recorded from eight patients with Parkinson's disease, before and after a single dose of apomorphine. To assess the treatment effects, the patients' motor state, Benton visual retention test (BVRT), and digit span tests were also examined. After apomorphine, although motor performance improved, the ERP latencies were delayed and the N2-P3 ERP amplitude was significantly diminished by comparison with pretreatment values. These data suggest that apomorphine induces, besides its motor effects in patients with Parkinson's disease, a slowing down of cognitive processing. Preferential stimulation of dopamine autoreceptors in mesocortical and mesolimbic systems may represent a neural mechanism for these effects. Also, the posttreatment BVRT rotation errors significantly increased, suggesting an apomorphine induced impairment of visuospatial perception.",1
"Růzicka, E, Roth, J, Spacková, N, Mecír, P, Jech, R",2
"Transient epileptic amnesia differentiated from psychogenic ""fugue"": neuropsychological, EEG, and PET findings.",0
"A patient had repeated episodes of transient loss of memory, which had been attributed to psychogenic causes. Preservation of his sense of personal identity and the presence of repetitive questioning indicated an organic basis, however, and the multiplicity of the attacks and their brief duration suggested an epileptic aetiology. Although three standard EEGs, CT and MRI were all normal, two sleep EEGs confirmed bilateral foci in the temporal lobes. The attacks responded to an anticonvulsant. A fluoro-deoxyglucose PET scan, performed a few months after the most recent attack, was normal. The patient also had impaired anterograde memory that persisted six months after recovery from the acute attacks.",1
"Kopelman, M D, Panayiotopoulos, C P, Lewis, P",2
"Loss of non-phosphorylated neurofilament immunoreactivity, with preservation of tyrosine hydroxylase, in surviving substantia nigra neurons in Parkinson's disease.",0
"The distribution of neurofilament immunoreactivity in the substantia nigra was examined by immunohistochemistry in five patients dying with Parkinson's disease and six control patients dying without neurological disease. In controls, pigmented neurons in the substantia nigra were intensively labelled by SMI32, a monoclonal antibody to non-phosphorylated neurofilament protein. In the substantia nigra from patients who had Parkinson's disease, there was a pronounced reduction of SMI32 labelling intensity in surviving pigmented neurons. By contrast, tyrosine hydroxylase immunoreactivity in surviving pigmented neurons was normal. SMI32 labelling was normal in regions of the brainstem not affected by the neuropathological process of Parkinson's disease. Findings with either antibodies to phosphorylated neurofilament, or enzymatic dephosphorylation followed by SMI32 labelling, indicated that loss of SMI32 immunostaining in Parkinson's disease was not due to masking of the neurofilament epitopes by phosphorylation. Our results indicate that neurofilament proteins are particularly likely to be disrupted or destroyed by the neuropathological process of Parkinson's disease. Nevertheless, the normal appearance of tyrosine hydroxylase indicates that protein synthesising systems may be intact in surviving neurons. Loss of neurofilament immunoreactivity may prove a sensitive neuropathological marker for characterisation of degenerating neurons in Parkinson's disease.",1
"Gai, W P, Vickers, J C, Blumbergs, P C, Blessing, W W",2
Benign form of multiple sclerosis: MRI evidence for less frequent and less inflammatory disease activity.,0
"Data from two serial studies comparing the MRI activity of two groups of 11 patients, one with early relapsing-remitting (mean disease duration 3.5 years), the other benign (mean disease duration 22 years) multiple sclerosis are presented. Those with benign disease developed fewer new or enlarging lesions, and such lesions that occurred had a lower incidence of gadolinium enhancement, a marker of inflammation. These results, when considered in conjunction with other published studies, suggest that both the frequency of new lesions and the amount of inflammation within them influence the development of disability in multiple sclerosis.",1
"Kidd, D, Thompson, A J, Kendall, B E, Miller, D H, McDonald, W I",2
Infarcts in the territory of the lateral branch of the posterior inferior cerebellar artery.,0
"The territory of the lateral branch of the posterior inferior cerebellar artery (1PICA) supplies the anterolateral region of the caudal part of the cerebellar hemisphere. Because infarcts in the territory of the 1PICA have rarely been studied specifically, 10 patients with this type of infarct are reported. An 1PICA infarct was isolated in only three patients, whereas it was associated with brainstem infarct in four, with occipital infarct in one, and with multiple infarcts in two patients. The most common symptom at onset was acute unsteadiness and gait ataxia without rotatory vertigo (six patients). Unilateral cerebellar dysfunction was found in all patients, with limb ataxia (nine patients), dysdiadochokinesia (five patients), and ipsilateral body sway (four patients), but dysarthria and primary position nystagmus were notably absent. In the patients with a coexisting infarct in the brainstem, cranial nerve and sensorimotor dysfunction was prominent and often masked the signs of cerebellar dysfunction. Unlike other infarcts in the PICA territory, 1PICA territory infarcts were mainly associated with vertebral artery atherosclerosis (six patients), whereas cardiac embolism was less common (three patients). Unilateral limb ataxia without dysarthria or vestibular signs suggests isolated 1PICA territory infarction and should allow its differentiation from other cerebellar infarcts.",1
"Barth, A, Bogousslavsky, J, Regli, F",2
Dysaesthesiae induced by physiological and electrical activation of posterior column afferents after stroke.,0
"Six of 48 stroke patients had functionally limiting dysaesthesiae induced by repetitive light touch, joint movement, or neuromuscular electrical stimulation (NMS). Only one of these six patients had a thalamic lesion. Quantitative sensory testing showed substantial impairment of pain and temperature sensation in all six patients, whereas light touch, vibration and position sense, and graphaesthesia were normal (three patients) or relatively spared (three patients). By contrast, none of 15 stroke patients in whom NMS did not evoke dysaesthesiae had clinical evidence of dissociated sensory loss. Conscious perception of joint movement and light touch is mediated mainly by the same population of large myelinated fibres activated preferentially by low intensity electrical stimulation. It is suggested that activation of these non-nociceptive, presumably dorsal column, afferents may contribute to dysaesthesiae in some patients with sensory loss after stroke.",1
"Triggs, W J, Berić, A",2
Visually and memory guided saccades in a case of cerebellar saccadic dysmetria.,0
"Saccades under four specific test conditions (visually guided, visually remembered, vestibular remembered, and cervical remembered) were studied in a 38 year old man with ocular dysmetria due to an angioma of the dorsal cerebellar vermis. The aim of the study was to investigate if the saccadic disorder was specific to certain subsets of saccades elicited by different sensory modalities. The experiments showed that initial saccades were equally hypermetric in all four conditions and that final eye position was normal in all memory guided saccade tests. Eye movements differed after the initial saccade, however. Whereas corrective saccades were seen in most visually guided and visually remembered experiments, postsaccadic centripetal drifts were documented in non-visual (vestibular and cervical) remembered saccades. These results indicate that the cerebellar vermis modulates the amplitude of the initial saccade (pulse size of saccadic innervation) independently of the saccadic task. The finding that post-saccadic drift never occurred when saccades were programmed using visual positional information suggests that the dorsal vermis may participate in the process of pulse step integration of saccades elicited by memorised vestibulo-cervical information.",1
"Kanayama, R, Bronstein, A M, Shallo-Hoffmann, J, Rudge, P, Husain, M",2
Preserved leftward movement in left unilateral spatial neglect due to frontal lesions.,0
"Three patients with left unilateral spatial neglect after predominantly frontal lobe lesions were asked to extend a horizontal line leftwards to double its original length. In this line extension task, they readily executed movements in or towards the contralesional left space. They performed the task in the left and right hemispaces as well as in the midline. The mean extension lengths did not differ significantly among these three spatial conditions. These results suggest that directional hypokinesia takes little part in left unilateral spatial neglect due to frontal lobe lesions. It is considered that the patients could execute leftward movements as the task oriented their attention sufficiently to the left. Two of the three patients, like reported cases with frontal neglect, showed a typical exploratory deficit for the left space in the line cancellation test. Such a deficit found in the traditional tasks, however, does not mean the presence of directional hypokinesia. All three patients showed visual extinction on double simultaneous stimulation. An attentional mechanism seems to play a predominant part in unilateral spatial neglect due to frontal lesions.",1
"Ishiai, S, Watabiki, S, Lee, E, Kanouchi, T, Odajima, N",2
Accidental transmission of Creutzfeldt-Jakob disease by dural cadaveric grafts.,0
"Four patients who received dural grafts of cadaveric origin in the course of posterior fossa procedures subsequently developed Creutzfeldt-Jakob disease (CJD). The interval from dural placement to clinical onset of CJD ranged from 16 months to nine years. Initial clinical presentation consisted of cerebellar symptoms, with dementia and myoclonus developing in later stages of the disease. EEGs showed diffuse slowing that evolved to a periodic activity pattern. CT and MRI were unremarkable in the early stages but pronounced cerebral and cerebellar atrophy with widened sulci and collections of fluid over the convexities were seen in the late stages of disease. The diagnosis was histologically proved by brain biopsy in all four cases. Molecular genetic analysis showed that the four patients were homozygous for methionine at codon 129 of the PrP gene. From this experience, and from six previous descriptions of this occurrence in the literature, it is manifest that awareness of the means of iatrogenic transmission of CJD, and the adoption of preventive measures, constitute the only effective way to stop the spread of CJD among patients who have neurosurgery.",1
"Martínez-Lage, J F, Poza, M, Sola, J, Tortosa, J G, Brown, P, Cervenáková, L, Esteban, J A, Mendoza, A",2
Post-traumatic syringomyelia.,0
"Post-traumatic syringomyelia was previously thought to be an infrequent but serious sequel to spinal cord injury. Clinical and CT studies have shown an incidence of between 1% and 5%, but more recently MRI has suggested an incidence of up to 22%. Twenty spinal cords have been examined after death from two days to 43 years after injury. Four had syrinxes, 20% of the series, approaching the incidence found by MRI. The acute and chronic pathological changes after trauma are described. Post-traumatic syringomyelia seems to develop from cores of necrotic tissue (myelomalacic cores) rather than lysis of haematoma. The mechanism of extension of syrinxes remains unexplained.",1
"Squier, M V, Lehr, R P",2
Amygdalar sclerosis: preoperative indicators and outcome after temporal lobectomy.,0
"Isolated amygdalar sclerosis (AS) in the presence of an intact hippocampus has been described in a subset of patients who have undergone a temporal lobectomy for the relief of seizures. Clinical observation suggested that these patients might be distinguishable, before and after operation, from those with typical mesial temporal sclerosis, which implies combined amygdalar and hippocampal sclerosis (AHS). From a three year series, all 11 patients classified as having AS were included in this study. These patients were compared with a group of 20 randomly chosen patients with AHS. The groups were found to be well matched in duration of ongoing seizures, full scale IQ, and duration of follow up (mean 19 months). Compared with patients with AHS, patients in the AS group were less likely to have had a seizure in early childhood, a variety of auras, EEG abnormalities localised to one temporal lobe, or an abnormal MRI before operation. They also performed better on preoperative memory tests. At follow up, patients in the AS group were less likely to be seizure free and more likely to have a deterioration in memory after undergoing anterior temporal lobectomy, including part of the hippocampus. The results show that there are preoperative indicators of mesial temporal pathology that are also of prognostic importance given the differences in outcome between the two pathological groups.",1
"Miller, L A, McLachlan, R S, Bouwer, M S, Hudson, L P, Munoz, D G",2
"Muscle strength, voluntary activation, twitch properties, and endurance in patients with fibromyalgia.",0
"Previous studies have shown decreased voluntary muscle strength and endurance in patients with fibromyalgia. The aim of this study was to determine to what extent this is due to lack of exertion. The twitch interpolation technique was used to determine the degree of central activation and estimate the ""true"" quadriceps muscle strength in patients with fibromyalgia and age and sex matched controls. Subjects hereafter performed an endurance test consisting of repetitive contractions at 50% of estimated ""true"" muscle strength of four seconds duration followed by a six second rest until exhaustion, or maximally for 40 minutes. Twitch decline and increases in mean rectified EMG were used as objective markers of fatigue. The estimated ""true"" muscle strength was 82 (SD 26) Nm in 20 patients with fibromyalgia compared with 133 Nm (SD 28) Nm in the 21 controls (p < 0.001). The ""true"" muscle strength per cm2 midthigh cross sectional area was lower 0.50 (SD 0.15) Nm/cm2 in the patients compared with 0.74 (SD 0.15) Nm/cm2 in the controls (p < 0.001). The decline over time in twitch sizes was similar in the two groups. The mean rectified EMG signal at a fixed force level of 50% of ""true"" muscle strength increased similarly in the two groups. Relaxation rates and contraction rates also increased equally in the two groups. In conclusion, a reduction of the estimated muscle strength per area unit of about 35% was found in the patients with fibromyalgia. This might be secondary to physical inactivity or neuroendocrine factors. No differences in changes in the neurophysiological indices associated with fatigue were found between the two groups.",1
"Nørregaard, J, Bülow, P M, Danneskiold-Samsøe, B",2
Two species of antiganglioside antibodies in a patient with a pharyngeal-cervical-brachial variant of Guillain-Barré syndrome.,0
A patient with a pharyngeal-cervical-brachial variant of Guillain-Barré syndrome had anti-GT1a and anti-GD1a antibodies (IgG) in the serum. The activities of anti-GT1a antibodies were stronger than anti-GD1a antibodies and their activities declined later in the clinical course. These two different antibodies bound independently to each ganglioside in an absorption study with polystyrene beads coated with GT1a or GD1a.,1
"Mizoguchi, K, Hase, A, Obi, T, Matsuoka, H, Takatsu, M, Nishimura, Y, Irie, F, Seyama, Y, Hirabayashi, Y",2
Initial enlargement of the opposite pupil as a false localising sign in intraparenchymal frontal haemorrhage.,0
"Ipsilateral third nerve palsy with early pupillary enlargement is an important sign of transtentorial herniation from a supratentorial mass lesion. A case of frontal, intraparenchymal haemorrhage is reported in which the first ocular manifestation of transtentorial herniation was enlargement of the contralateral pupil. The ipsilateral pupil dilated only after complete oculomotor palsy of the contralateral eye. After partial frontal lobectomy and removal of blood clot, the ipsilateral third nerve recovered before the contralateral third nerve. Clinical findings localised the contralateral third nerve lesion to an extra-axial site. The possible mechanisms of contralateral third nerve compression are discussed. This seems to be the first example of pupillary enlargement as a false localising sign from a contralateral, supratentorial, intraparenchymal mass lesion.",1
"Chen, R, Sahjpaul, R, Del Maestro, R F, Assis, L, Young, G B",2
Right hemisphere learning disability associated with left hemisphere dysfunction: anomalous dominance and development.,0
"Two patients are described with the social emotional processing disorder, a developmental syndrome usually ascribed to right hemisphere dysfunction. In these two patients however, neurological examinations, EEG, and neuroimaging studies were all consistent with left hemisphere dysfunction. Both patients were left handed and had findings suggestive of anomalous dominance for language. It is proposed that early left hemisphere injury may have resulted in functional reorganisation that allowed sparing of language and motor skills but interfered with the development of functions that the right hemisphere normally subserves.",1
"Sandson, T A, Manoach, D S, Price, B H, Rentz, D, Weintraub, S",2
"Acute arsenic poisoning: absence of polyneuropathy after treatment with 2,3-dimercaptopropanesulphonate (DMPS).",0
"Two men aged 19 and 21 years ingested 1 g and 4 g respectively from 3 kg of a white crystalline powder that they thought was a substance of abuse. It was later identified as almost pure arsenic trioxide. Both had nausea and vomiting and one developed acute renal failure. Each was treated with 2,3-dimercaptopropanesulphonate (DMPS), and made a full recovery with no evidence of prolonged renal or neurological impairment. The DMPS-arsenic complex is probably associated with lower penetration into the CNS and as a consequence treatment with DMPS may result in lower acute and chronic neurotoxicity than treatment with the currently standard recommended chelating agent dimercaprol (British Anti-Lewisite; BAL).",1
"Moore, D F, O'Callaghan, C A, Berlyne, G, Ogg, C S, Davies, H A, House, I M, Henry, J A",2
Botulinum toxin treatment for lower limb extensor spasticity in chronic hemiparetic patients.,0
"Twelve chronic hemiparetic outpatients with pronounced lower limb extensor spasticity were injected with 400 units of botulinum toxin A, EMG guided into the soleus, tibialis posterior, and both heads of the gastrocnemius muscles. Botulinum toxin A caused a definite reduction of plantar flexor spasticity, in 10 patients two weeks after the injection, as assessed by the Ashworth scale. Four of the patients were able to achieve active dorsiflexion of their affected ankle. Gait analysis including the measurement of vertical ground reaction forces showed a statistically significant (p < 0.01) improvement in velocity, stride length, stance symmetry, and the length of the force point of action under the affected foot. Qualitative improvements on the force diagrams indicated a better loading, advancement of the body, and push off of the affected limb in seven patients. Eight weeks after the injection the effects waned.",1
"Hesse, S, Lücke, D, Malezic, M, Bertelt, C, Friedrich, H, Gregoric, M, Mauritz, K H",2
"Peroneal muscular atrophy with pyramidal tract features (hereditary motor and sensory neuropathy type V): a clinical, neurophysiological, and pathological study of a large kindred.",0
"A large family with autosomal dominant inheritance of peroneal muscular atrophy, associated with extensor plantar responses in some cases, has been studied. Onset was usually in the first two decades and spasticity was not a feature. Nerve conduction studies in 21 cases and light and electron microscope findings on six sural nerve biopsies were similar to those in hereditary motor and sensory neuropathy type II.",1
"Frith, J A, McLeod, J G, Nicholson, G A, Yang, F",2
Elementary visual hallucinations in migraine and epilepsy.,0
"A comparison of the elementary visual hallucinations of 50 patients with migraine and 20 patients with occipital epileptic seizures showed that epileptic seizures are predominantly multi-coloured with circular or spherical patterns as opposed to the predominantly black and white linear patterns of migraine. This simple clinical symptom of the elementary visual hallucinations may be helpful in distinguishing between classic or basilar migraine and visual partial epileptic seizures, particularly in children. Claims that epileptic seizures are triggered or caused by migraine may be artificial, reflecting problems in the differential diagnosis between the two diseases.",1
"Panayiotopoulos, C P",2
"Initial letter and semantic category fluency in Alzheimer's disease, Huntington's disease, and progressive supranuclear palsy.",0
"Ten patients with dementia of Alzheimer's type, 10 patients with progressive supranuclear palsy, and 10 patients with Huntington's disease were compared on two types of verbal fluency task--namely, initial letter fluency and category (semantic) fluency. The groups were carefully matched for overall level of dementia on the dementia rating scale, and were compared with 25 age matched normal controls. The controls found letter fluency more difficult than category fluency, and this relative pattern of performance was repeated in the progressive supranuclear palsy and Huntington's disease groups, although both groups were significantly impaired on both tasks. By contrast, patients with Alzheimer's disease performed just as poorly as the progressive supranuclear palsy and Huntington's disease groups on the category tasks, but were significantly less impaired at letter fluency, performing at near normal levels on this task. From these results, it is suggested that the performances of patients with progressive supranuclear palsy and Huntington's disease relate largely to initiation and retrieval problems secondary to disruption of frontostriatal circuits, whereas in Alzheimer's disease, the poorer performance on category fluency is due principally to the breakdown of semantic knowledge, which probably reflects temporal neocortical involvement.",1
"Rosser, A, Hodges, J R",2
Investigation of unilateral sensory or motor symptoms: frequency of neurological pathology depends on side of symptoms.,0
"The records of 82 patients who had undergone inpatient neurological investigation for unilateral motor symptoms, sensory symptoms, or both, without definite neurological signs, were reviewed. Diagnosis of a physical disorder was more frequent if symptoms were on the right side rather than on the left (odds ratio (OR) = 7.7, 95% confidence interval (95% CI) 2.6-23), and in males than in females (OR = 3.0, 95% CI 1.1-8.3).",1
"Rothwell, P",2
Multimodal electrophysiological studies including motor evoked potentials in patients with locked-in syndrome: report of six patients.,0
"Clinical and electrophysiological findings in six patients with locked-in syndrome are reported. Motor evoked potentials (MEPs) after magnetic stimulation of the motor cortex were absent in four patients, none of whom recovered clinically. In two patients, MEPs could be obtained from the severely paretic limbs and almost full motor recovery followed. Somatosensory evoked potentials were altered in four of the patients, and brainstem auditory evoked potentials were altered in two of four patients examined, showing a clinically unsuspected tegmental involvement. The EEG showed a predominance of reactive alpha activity in all patients, documenting a preserved consciousness. It is concluded that a multimodal electrophysiological approach, in addition to clinical assessment, can be helpful in diagnosing locked-in syndrome, estimating the extension of the underlying brainstem dysfunction, and predicting functional outcome.",1
"Bassetti, C, Mathis, J, Hess, C W",2
Spontaneous thrombosis of an arteriovenous malformation.,0
A patient with a spontaneously thrombosed arteriovenous malformation (AVM) presented with epilepsy. The CT and MRI appearances were of an intrinsic cerebral neoplasm with extensive surrounding vasogenic cerebral oedema and a mass effect. Histopathology confirmed a large thrombosed AVM. The natural history of AVMs and spontaneous thrombosis are reviewed.,1
"Guazzo, E P, Xuereb, J H",2
Apolipoprotein E polymorphism in Japanese patients with Alzheimer's disease or vascular dementia.,0
"Apolipoprotein E (ApoE) plays a key part in lipid metabolism both in the liver, and in the CNS. To clarify the association of ApoE polymorphism with Alzheimer's disease and vascular dementia in Japan, 13 patients with early onset (age > or = 65) sporadic Alzheimer's disease, 40 patients with late onset (age < or = 65) sporadic Alzheimer's disease, 19 patients with vascular dementia, and 49 non-demented control subjects were analysed. The results showed a significantly increased frequency of the epsilon 4 allele in the patients with late onset sporadic Alzheimer's disease (0.25), but not in the patients with early onset sporadic Alzheimer's disease (0.04) or in the patients with vascular dementia (0.13) compared with controls (0.09). The raised frequency of the epsilon 4 allele in the patients with late onset sporadic Alzheimer's disease was of a lower magnitude than that in United States and Canadian studies. This may in part be due to a lower epsilon 4 frequency in the normal Japanese population and reflect the lower morbidity from Alzheimer's disease in Japan.",1
"Kawamata, J, Tanaka, S, Shimohama, S, Ueda, K, Kimura, J",2
Transient topographical amnesia.,0
"Ten healthy middle aged or elderly women experienced isolated episodes of topographical amnesia without an obvious aetiology. It is likely a benign cognitive disorder, similar to transient global amnesia.",1
"Stracciari, A, Lorusso, S, Pazzaglia, P",2
"Effectiveness of shunting in patients with normal pressure hydrocephalus predicted by temporary, controlled-resistance, continuous lumbar drainage: a pilot study.",0
"From 1984 to 1992 15 consecutive cases of normal pressure hydrocephalus were included in this pilot study. A series of tests included CT of the brain, grading of the cognitive mental state with the mini-mental state examination; urodynamic studies, and gait evaluation. These tests were carried out on admission, and repeated on day 1, day 3, and day 5 after controlled-resistance, continuous lumbar drainage (CRCLD). During this period, eight patients showed significant improvements of cognitive mental state, urodynamic studies, or gait and were regarded as CRCLD responders; the remaining seven patients were regarded as CRCLD non-responders. The CRCLD was routinely removed on day 6 after the drainage procedure and a ventriculoperitoneal (VP) or a lumboperitoneal (LP) shunt was randomly selected for each patient. The tests were repeated one week after shunting and a year later. All the CRCLD responders continued to benefit from shunting at one week and one year after the procedure irrespective of the type of shunting they received. By comparison, none of the CRCLD non-responders showed any improvement a year after the shunting. In conclusion, CRCLD proved to be a safe and effective way to predict the effectiveness of shunting in patients with normal pressure hydrocephalus.",1
"Chen, I H, Huang, C I, Liu, H C, Chen, K K",2
Anterior spinal hernia: an increasingly recognised cause of thoracic cord dysfunction.,0
"Two cases of anterior spinal hernia are presented. The medical literature is reviewed, the syndrome characterised, and its cause and treatment discussed. The patient is typically middle aged with a history of stepwise slowly progressive mid-thoracic anterior hemicord syndrome manifesting as hemianalgesia below the affected segment, followed by contralateral lower limb spasticity that develops into an asymmetric paraparesis with sparing of dorsal column sensation. Radiological investigation demonstrates an enlarged dorsal arachnoid space in association with an apparently focally narrowed thoracic cord, kinked towards the anterior dura. At operation the cord is found to be prolapsed into an anterolateral dural diverticulum. The most likely cause of this syndrome is anterior spinal artery segmental branch ischaemia, in a cord chronically incarcerated in a congenital anterior meningocele. This readily treatable condition should be considered in all cases of thoracic cord dysfunction and surgical repair effected early to prevent stepwise progression to paraplegia.",1
"White, B D, Firth, J L",2
"Extrapyramidalism in Alzheimer's disease: prevalence, psychiatric, and neuropsychological correlates.",0
"The prevalence and clinical correlates of extrapyramidal signs in a consecutive series of 78 patients with Alzheimer's disease attending a neurology clinic, and 20 age comparable normal controls, were examined. Based on the unified Parkinson's disease rating scale (UPDRS) findings, 18 patients (23%) met criteria for parkinsonism, 44 (56%) had isolated extrapyramidal signs, and 16 (21%) had no extrapyramidal signs. Whereas the control group showed a similar prevalence of isolated extrapyramidal signs (57%), none of them showed parkinsonism. No significant differences were found for age, sex, duration of illness, and severity of dementia among the three Alzheimer's disease groups. Patients with Alzheimer's disease-parkinsonism, however, showed a significantly higher frequency of major depression and dysthymia and significantly higher Hamilton depression scores than patients with isolated or no extrapyramidal signs. Patients with Alzheimer's disease-parkinsonism also showed significantly more deficits on frontal lobe related tasks such as the Wisconsin card sorting test, trail making test, and verbal fluency, as well as on tests of constructional praxis and abstract reasoning than patients with Alzheimer's disease but no extrapyramidal signs. In conclusion, the study showed a specific association between Alzheimer's disease and parkinsonism, as well as significant relations between parkinsonism, deficits in executive functions, and depression among patients with Alzheimer's disease.",1
"Merello, M, Sabe, L, Teson, A, Migliorelli, R, Petracchi, M, Leiguarda, R, Starkstein, S",2
A neuropsychological instrument adding to the description of patients with suspected cortical dementia: the Milan overall dementia assessment.,0
"A new, short, neuropsychologically oriented test for dementia assessment--the Milan Overall Dementia Assessment (MODA)--is described. Age and education adjusted norms based on 217 healthy controls are given. A validation study on 312 outpatients suspected of dementia (121 with probable Alzheimer's disease) showed that the MODA differentiated patients with cognitive impairment from normal subjects more effectively than did the DSM III-R. The correlation between the MODA and the mini mental state examination was 0.63 in controls and 0.84 in patients with Alzheimer's dementia. The MODA test-retest reliability was 0.83. The test proved to be well suited to longitudinal studies.",1
"Brazzelli, M, Capitani, E, Della Sala, S, Spinnler, H, Zuffi, M",2
Ability to modulate walking cadence remains intact in Parkinson's disease.,0
"Gait hypokinesia (slowness) is a characteristic feature of Parkinson's disease. It is not clear, however, whether the slowness is due to a problem in regulation of the timing of consecutive steps or the control of stride size. Examination of cadence control for slow to medium walking speeds has shown an increase in step frequency that was a compensation for reduced stride length. In this investigation the ability of Parkinsonian patients to modulate their cadence (steps per minute) at the fast walking speeds exhibited by age and height matched controls was examined. The findings indicated that cadence control remains unaffected throughout its entire range in Parkinson's disease and that gait hypokinesia is directly attributable to an inability to internally generate sufficiently large steps.",1
"Morris, M E, Iansek, R, Matyas, T A, Summers, J J",2
A patient with one limb interstitial myositis with localised lipoatrophy presenting with severe cramps and fasciculations.,0
"A case of interstitial myositis associated with a localised lipoatrophy is reported. The patient is a 24 year old man who presented with severe painful cramps and fasciculations localised to one limb. The rarity of both disorders, and their likely common autoimmune mechanism, suggest that this is not a chance association.",1
"Créange, A, Renard, J L, Millet, P, Boisnic, S, Felten, D, Béquet, D, Hauw, J J",2
Multiple sclerosis in island populations: prevalence in the Bailiwicks of Guernsey and Jersey.,0
"The aim of this study was to establish for the first time the prevalence of multiple sclerosis in the Bailiwicks of Guernsey and Jersey, as representing the most southerly part of the British Isles. All patients with multiple sclerosis in the Channel Islands resident on prevalence day were identified by contacting all medical practices, Multiple Sclerosis, and Action Research for Multiple Sclerosis societies by letter and visits. The crude overall prevalence rates were 113/100,000 (95% confidence interval (95% CI) 90.3-135.7) and 86.7/100,000 (95% CI 63.3-110.0) for the Bailiwicks of Jersey and Guernsey respectively. When standardised to the age and sex structure of a previously reported Northern Ireland population the standardised prevalence ratios were 120.2/100,000 (95% CI 96.0-144.3) for Jersey and 95.6/100,000 (95% CI 69.9-121.3) for the Bailiwick of Guernsey. When compared with recent studies in the northern United Kingdom the prevalence rates for multiple sclerosis in the Channel Islands lend some support to the proposed latitudinal gradient in the British Isles although the standardised prevalence ratio in the Bailiwick of Jersey is similar to those found in recent studies of southern Britain. The standardised prevalence rates of probable and definite multiple sclerosis for the male populations were 37.3/100,000 (95% CI 17.9-56.7) for the Bailiwick of Guernsey and 45.5/100,000 (95% CI 26.3-64.7) for the Bailiwick of Jersey whereas the standardised prevalence rates for the female populations were 97.5/100,000 (95% CI 73.9-143.5) and 139.5/100,000 (95% CI 112.6-181.2) respectively. Thus there is a striking and unexplained 43% higher prevalence of probable and definite multiple sclerosis in the female population of Jersey compared with that of the Bailiwick of Guernsey. This seems to be due to an unusually low prevalence of the disease among the female population of the Bailiwick of Guernsey compared with that of the United Kingdom mainland.",1
"Sharpe, G, Price, S E, Last, A, Thompson, R J",2
Brain magnetic resonance imaging and multimodal evoked potentials in benign and secondary progressive multiple sclerosis.,0
"Brain MRI and multimodal evoked potentials (EPs) were obtained for 13 patients with benign multiple sclerosis and 13 patients with secondary progressive multiple sclerosis, matched for age and duration of the disease, to investigate the nature of the disability in multiple sclerosis. Patients with secondary progressive multiple sclerosis had significantly greater lesion loads for five of seven periventricular regions and for three of nine regions separate from the ventricles. Patients with secondary progressive multiple sclerosis also had more severe infratentorial atrophy scores (p = 0.04), whereas there were no differences between the two groups in number and extent of enhancing lesions. The frequencies were significantly higher and severities greater for multimodal EP abnormalities of all the modalities in patients with secondary progressive multiple sclerosis. At least one EP component was absent in 12 (92%) patients with secondary progressive multiple sclerosis but in only one patient (8%) with benign multiple sclerosis (p < 0.001). There was neurophysiological evidence for cervical cord involvement in eight (61%) patients with secondary progressive multiple sclerosis and in one with benign multiple sclerosis (p < 0.01). These data indicate that the total amount of lesions, the distribution, and the nature of the pathological process might all account for the development of disability in multiple sclerosis.",1
"Filippi, M, Campi, A, Mammi, S, Martinelli, V, Locatelli, T, Scotti, G, Amadio, S, Canal, N, Comi, G",2
"Neuropsychological impairments in chronic fatigue syndrome, multiple sclerosis, and depression.",0
"To examine the degree and nature of cognitive impairments in chronic fatigue syndrome, a comprehensive neuropsychological battery was given to patients with chronic fatigue syndrome, multiple sclerosis, depressed patients, and healthy controls. The battery included tests of attention and concentration, information processing speed, verbal and visual memory, intellectual ability, and concept formation. Measures of depression and anxiety were also obtained. The chronic fatigue syndrome group did not differ from the depressed group in overall neuropsychological performance, but differed from the multiple sclerosis and control groups. The most significant impairment was in information processing speed in the chronic fatigue syndrome group. Depression and anxiety were not related to neuropsychological performance. The influence of reduced information processing on other areas of cognition is discussed.",1
"DeLuca, J, Johnson, S K, Beldowicz, D, Natelson, B H",2
Which factors predict cognitive decline in Parkinson's disease?,0
"The study assessed cognitive decline in non-demented, non-depressed patients with well defined Parkinson's disease and determined the predictive value for cognitive decline of different motor symptoms. Motor disability was measured with the Unified Parkinson's disease rating scale, impairment in activities of daily living, levodopa test, and long term clinical follow up. Neuropsychological evaluations included modified mini mental state, fluency, Wechsler logical memory, Wisconsin card sorting test, and the Montgomery and Asberg depression rating scale. Fifty three patients fulfilling clinical criteria for idiopathic Parkinson's disease were studied. Cognitive performance on initial testing was significantly correlated with education and disease duration but not with age at disease onset. Cognitive performance on retesting after three years of follow up was significantly reduced. This reduction was significantly greater in the late onset group, in patients with isolated dystonic dyskinesiae, and in patients with a lower percentage of motor improvement on levodopa. Cognitive decline in idiopathic Parkinson's disease may depend on both the prevalence of non-dopaminergic lesions and the topography of dopaminergic denervation. Predictive factors for cognitive decline, especially in executive tasks, relate more to non-dopaminergic than to dopaminergic lesions.",1
"Caparros-Lefebvre, D, Pécheux, N, Petit, V, Duhamel, A, Petit, H",2
Inherited Creutzfeldt-Jakob disease in a British family associated with a novel 144 base pair insertion of the prion protein gene.,0
"A case of familial Creutzfeldt-Jakob disease associated with a 144 base pair insertion in the open reading frame of the prion protein gene is described. Sequencing of the mutated allele showed an arrangement of six octapeptide repeats, distinct from that of a recently described British family with an insertion of similar size. Thirteen years previously the brother of the proband had died from ""Huntington's disease"", but re-examination of his neuropathology revealed spongiform encephalopathy and anti-prion protein immunocytochemistry gave a positive result. The independent evolution of at least two distinct pathological 144 base pair insertions in Britain is proposed. The importance of maintaining a high index of suspicion of inherited Creutzfeldt-Jakob disease in cases of familial neurodegenerative disease is stressed.",1
"Nicholl, D, Windl, O, de Silva, R, Sawcer, S, Dempster, M, Ironside, J W, Estibeiro, J P, Yuill, G M, Lathe, R, Will, R G",2
"Bilateral simultaneous optic neuropathy in adults: clinical, imaging, serological, and genetic studies.",0
"To elucidate the cause(s) of acute or subacute bilateral simultaneous optic neuropathy (BSON) in adult life, a follow up study of 23 patients was performed with clinical assessment, brain MRI, HLA typing, and mitochondrial DNA analysis. The results of CSF electrophoresis were available from previous investigations in 11 patients. At follow up, five (22%) had developed clinically definite multiple sclerosis, four (17%) had mitochondrial DNA point mutations indicating a diagnosis of Leber's hereditary optic neuropathy (LHON). The remaining 14 patients (61%) still had clinically isolated BSON a mean of 50 months after the onset of visual symptoms: three of 14 (21%) had multiple MRI white matter lesions compatible with multiple sclerosis, three of 14 (21%) had the multiple sclerosis associated HLA-DR15/DQw6 haplotype, and one of seven tested had CSF oligoclonal IgG bands; in total only five (36%) had one or more of these risk factors. The low frequency of risk factors for the development of multiple sclerosis in these 14 patients suggests that few will develop multiple sclerosis with more prolonged follow up. It is concluded that: (a) about 20% of cases of BSON without affected relatives are due to LHON; (b) multiple sclerosis develops after BSON in at least 20% of cases, but the long term conversion rate is likely to be considerably less than the rate of over 70% seen after an episode of acute unilateral optic neuritis in adult life.",1
"Morrissey, S P, Borruat, F X, Miller, D H, Moseley, I F, Sweeney, M G, Govan, G G, Kelly, M A, Francis, D A, Harding, A E, McDonald, W I",2
Verbal fluency in dementia of frontal lobe type and dementia of Alzheimer type.,0
"This study compares semantic (category) and letter-initial verbal fluency performance in dementia of frontal lobe type, dementia of Alzheimer type, and control subjects matched for age, sex, and level of education. As well as demographic characteristics, patients were matched for severity of dementia as estimated by the mini mental scale (23.2 (SD 4.9)). All patients with dementia of frontal lobe type had a frontal hypoperfusion on single photon emission computed tomography whereas patients with dementia of Alzheimer type showed mainly posterior deficits. Patients had significantly lower verbal fluency than controls but those with dementia of frontal lobe type did not differ from those with dementia of Alzheimer type in the number of words generated, intrusions, or preservations. Category fluency was more impaired than letter fluency in both dementias. No correlation between frontal index, frontal/parietal index, and fluency was found. Verbal fluency tests are sensitive tools for detecting dementia but do not seem useful in distinguishing between patients with dementia of Alzheimer type and those with dementia of frontal lobe type in early disease.",1
"Pasquier, F, Lebert, F, Grymonprez, L, Petit, H",2
An improved diagnostic assay for Lambert-Eaton myasthenic syndrome.,0
"A new immunoprecipitation assay has been established for detecting antibodies to voltage-gated calcium channels (VGCCs) in Lambert-Eaton myasthenic syndrome (LEMS), using 125I-omega-conotoxin MVIIC, which binds to P-type VGCCs, to label extracts of human cerebellum. Fifty six of 66 serum samples (85%) from patients with clinically and electrophysiologically definite LEMS were positive for the presence of VGCC antibodies, defined as a titre > 3 SD above the mean for the healthy controls (n = 10). All disease controls (n = 40) were negative. This sensitive immunoassay should prove valuable in the diagnosis of LEMS.",1
"Motomura, M, Johnston, I, Lang, B, Vincent, A, Newsom-Davis, J",2
Idiopathic orbital inflammation (orbital inflammatory pseudotumour): an unusual cause of transient ischaemic attack.,0
"A patient with idiopathic inflammation of the right orbit, established by biopsy, developed episodes of transient left sensorimotor hemiparesis. Neuroimaging showed intracranial extension of the disease with pronounced narrowing of the right internal carotid artery in its intracavernous portion. Oral cyclophosphamide induced gradual improvement. Transient ischaemic attack is rarely found in association with orbital disease and indicates possible intracranial extension.",1
"Borruat, F X, Vuilleumier, P, Ducrey, N, Fankhauser, H, Janzer, R C, Regli, F",2
Serial proton magnetic resonance spectroscopy in a patient with the interval form of carbon monoxide poisoning.,0
"Serial proton magnetic resonance spectroscopy (1H-MRS) studies were performed from immediately after the appearance of sequelae in a patient with the interval form of carbon monoxide (CO) poisoning. The volume of interest was set over the frontal lobe white matter. In the early period a persistent increase in choline was found, which was thought to reflect the course of progressive demyelination. The appearance of lactate and decrease in N-acetylaspartate reflected the point at which neuron injury became irreversible. These were followed later by the finding of irreversible changes on MRI and single photon emission computed tomography. The findings suggest that 1H-MRS may be a useful modality to determine neuron viability and prognosis early in the course of the interval form of CO poisoning.",1
"Murata, T, Itoh, S, Koshino, Y, Omori, M, Murata, I, Sakamoto, K, Isaki, K, Kimura, H, Ishii, Y",2
Hyperfibrinolysis during intracranial surgery: effect of high dose aprotinin.,0
"A patient undergoing intracranial surgery developed disseminated intravascular coagulation with life threatening peroperative bleeding. Thromboelastography established the diagnosis of hyperfibrinolysis, usually a fatal complication of a neurosurgical operation. With the administration of a high dose regimen of aprotinin (Trasylol) the haemorrhage was controlled and the hyperfibrinolytic state reversed. Evaluation of blood samples from the jugular bulb suggested that there was a pronounced local release of tissue plasminogen activator into the circulation.",1
"Palmer, J D, Francis, D A, Roath, O S, Francis, J L, Iannotti, F",2
Multivariate analysis of predictive factors of multiple sclerosis course with a validated method to assess clinical events.,0
"The clinical data of 309 patients with definite multiple sclerosis were recorded in the European data base for multiple sclerosis (EDMUS) to determine the prognostic significance of several demographic and clinical variables. An interview with closed questions structured according to standardised criteria of disease phases and courses was used to assess the clinical course. The reliability was evaluated by four trained neurologists in a sample of 33 patients with multiple sclerosis. Both the within and between rater agreement on data collection was fair to high for the historical variables (K = 0.33-1). Between rater agreement was more variable for the evaluation of 12 different EDMUS event categories (K = 0.3-0.95). The predictive model for the time to reach a secondary progression showed that an age at onset older than 25 (p = 0.006) and an event at onset followed by disability > or = 3 on the Kurtzke expanded disability status scale (EDSS; p = 0.004) were the most unfavourable clinical variables in 249 patients with relapsing remitting (180) or relapsing progressive (69) courses. In the 69 patients with relapsing progressive disease, the time to reach severe disability (EDSS > or = 6) was negatively influenced by a first interval between attacks shorter than one year, a number of bouts with EDSS > 2 in the first two years of the disease, and involvement of the pyramidal system at onset (p < 0.05). In 60 patients with chronic progressive disease this outcome was negatively influenced by pyramidal, brainstem, and sensory involvement at onset (p < 0.01).",1
"Trojano, M, Avolio, C, Manzari, C, Calò, A, De Robertis, F, Serio, G, Livrea, P",2
Kinematic properties of upper limb trajectories in idiopathic torsion dystonia.,0
"The kinematic properties of upper limb trajectories of simple reaching movements have been analysed in patients with idiopathic torsion dystonia (ITD). The velocity profiles differed from those of neurologically healthy subjects by being less symmetric. In several patients movement execution was slow due to a longer deceleration time. This phenomenon was even more conspicuous in the absence of visual feedback from the limb and was accompanied by a significant decrease in the final accuracy. These findings show that patients with ITD have deficits in central motor mechanisms beyond abnormal muscle activation patterns. Similarities between kinematic properties of patients with ITD and patients with Parkinson's disease including the deterioration of motor performance in ITD in the absence of visual feedback from the limb, suggest the existence of abnormalities in sensorimotor integration in both diseases.",1
"Inzelberg, R, Flash, T, Schechtman, E, Korczyn, A D",2
Progressive neuronal degeneration of childhood with liver disease (Alpers' disease) presenting in young adults.,0
"Two unrelated and previously healthy girls, aged 17 and 18, presented with a subacute encephalopathy, visual and sensory symptoms and signs, and prominent seizures that were difficult to control. Brain MRI showed lesions (high signal on T2 weighted images) in the occipital lobes and thalamus; EEG showed slow wave activity with superimposed polyspikes. Inexorable downhill progression led to death in hepatic failure within eight months of onset. Histopathological findings in both patients ((a) chronic hepatitis with prominent bile duct proliferation, fatty change, and fibrosis; (b) in the brain a patchy destruction of the cerebral cortex, predominantly involving striate cortex) were characteristic of progressive neuronal degeneration of childhood with liver disease--Alpers-Huttenlocher syndrome--a rare autosomal recessive disorder usually seen in infants and young children.",1
"Harding, B N, Alsanjari, N, Smith, S J, Wiles, C M, Thrush, D, Miller, D H, Scaravilli, F, Harding, A E",2
Vascular ataxic hemiparesis: a re-evaluation.,0
"Ataxic hemiparesis is commonly considered as one of the ""typical"" lacunar syndromes. Using the prospective stroke registries from Lausanne and Besançon, 100 patients were selected consecutively (73% men, 27% women; age 64.7 (SD 13.6) years) with a first stroke and ataxic hemiparesis (hemiparesis or pyramidal signs and ipsilateral incoordination without sensory loss). Brain CT or MRI was performed on all patients. A primary haemorrhage was present in 5%, an infarct in 72%, isolated leukoaraiosis in 9%, and no apparent abnormality in 14%. The locations of lesions were the internal capsule (39%), pons (19%), thalamus (13%), corona radiata (13%), lentiform nucleus (8%), cerebellum (superior cerebellar artery territory) (4%), and frontal cortex (anterior cerebral artery territory) (4%). The clinical features of ataxic hemiparesis with different locations were almost identical. Only minor associated signs allowed the localisation of the lesions (paraesthesiae with a lesion in the thalamus; nystagmus or dysarthria with a cerebellar or pontine location). Crural paresis with homolateral ataxia was seen only with cortical paramedian frontal lesions. Presumed hypertensive small artery disease was not always found, but was still the leading cause of stroke, being present in 59% of the patients and in 62% of those with small deep infarcts. A potential source of embolism (arterial or cardiac) was found in one fourth of the patients. Therefore no definite association can be made between ataxic hemiparesis and lacunar infarction. In particular, so called uncommon lesion locations may not be rare. After extensive investigations a diagnosis of lacunar infarct can be retained in only slightly more than half of the cases.",1
"Moulin, T, Bogousslavsky, J, Chopard, J L, Ghika, J, Crépin-Leblond, T, Martin, V, Maeder, P",2
Intraventricular recombinant tissue plasminogen activator for lysis of intraventricular haemorrhage.,0
"A prospective series of 20 patients with moderate to severe intraventricular haemorrhage (IVH) was studied for the effect of intraventricular administration of recombinant tissue plasminogen activator (rt-PA) on reduction of haematoma volume and prognosis. On the day of haemorrhage ventriculostomy was performed and 2 to 5 mg of rt-PA were injected via the external ventricular drainage, followed by drainage closure for two hours. In 14 patients rt-PA treatment was repeated. Computed tomography showed complete clot lysis or substantial reduction of intraventricular haematoma volume in 19 patients within 96 hours; the clearance of the third and fourth ventricle preceded the clearance of the lateral ventricles. Decrease of ventricular enlargement was seen in all but one patient with initial ventricular dilatation. Increase of haematoma volume and ventricular size was found in one patient. Outcome was minor or no neurological deficit in nine patients, disabling neurological deficit in six patients, and vegetative status in four patients. One patient did not survive the IVH. Intraventricular treatment with rt-PA seems effective in rapid lysis of intraventricular haematoma and normalisation of impaired CSF circulation. This treatment may contribute to an improvement in prognosis of moderate to severe IVH.",1
"Rohde, V, Schaller, C, Hassler, W E",2
Comparison of executive and visuospatial memory function in Huntington's disease and dementia of Alzheimer type matched for degree of dementia.,0
"Groups of patients with Hungington's disease and probable dementia of Alzheimer type (DAT) matched for level of dementia on the basis of mini mental state examination scores were compared in several tests of visual memory and tests sensitive to frontal lobe dysfunction. Whereas recall of patients with DAT tended to be worse on the Kendrick object learning test, the two groups were equivalent on tests of sensorimotor ability and delayed matching to sample performance. By contrast, the patients with Huntington's disease were significantly worse on tests of pattern and spatial recognition, simultaneous matching to sample, visuospatial paired associates, and on three tests sensitive to frontal lobe dysfunction--namely, the Tower of London test of planning, spatial working memory, and a visual discrimination learning and reversal paradigm. The impairments in these tests, however, did not always qualitatively resemble those seen in patients with frontal lobe damage and may be more characteristic of primary neostriatal deficit. In the visual discrimination paradigm the patients with Hungtington's disease were significantly worse than the patients with DAT at the simple reversal stage, where they displayed significant preservation to the previously rewarded alternative. The results are consistent with the hypothesis that patients with Huntington's disease exhibit deficits in tests sensitive to frontostriatal dysfunction and that this form of intellectual deterioration is qualitatively distinct from that seen in Alzheimer's disease.",1
"Lange, K W, Sahakian, B J, Quinn, N P, Marsden, C D, Robbins, T W",2
"Pen injected apomorphine against off phenomena in late Parkinson's disease: a double blind, placebo controlled study.",0
"The effect, therapeutic dose range, and pharmacokinetics of apomorphine, given as subcutaneous injections by a single use pen, were evaluated in the treatment of off phenomena in 22 patients with idiopathic Parkinson's disease. At study entry a placebo controlled apomorphine test was performed, and apomorphine doses were then individually titrated (mean 3.4 (range 0.8-6.0) mg) and compared with placebo in a double blind cross over phase. With apomorphine compared with placebo the mean daily duration of off periods was reduced by 51% as assessed by the patients and by 58% as assessed by the staff. The severity of off periods was also significantly reduced. The effect was unchanged after a maintenance phase of eight weeks. At study termination 13 of 14 patients were able to inject themselves and 11 of 14 patients found that their feeling of freedom had increased. The most common adverse events were nausea, subcutaneous nodules, and increased frequency of involuntary movements. Pharmacokinetics were linear and did not change with repeat dosing. The tmax ranged from five to 45 minutes (16 patients). It is concluded that pen injected apomorphine is a valuable treatment for patients with advanced Parkinson's disease with on-off phenomena.",1
"Ostergaard, L, Werdelin, L, Odin, P, Lindvall, O, Dupont, E, Christensen, P B, Boisen, E, Jensen, N B, Ingwersen, S H, Schmiegelow, M",2
Magnetic resonance spectroscopic study of parkinsonism related to boxing.,0
"Proton magnetic resonance spectroscopy, localised to the lentiform nucleus, was carried out in three ex-professional boxers who developed a parkinsonian syndrome, six patients with idiopathic Parkinson's disease, and six age matched controls. The three ex-boxers all showed a pronounced reduction in the absolute concentration of N-acetylaspartate compared with the patients with idiopathic Parkinson's disease and the control group. This reduction is likely to reflect neuronal loss occurring in the putamen and globus pallidus and supports the hypothesis that the extrapyramidal syndrome that may occur in ex-boxers is a distinct entity from idiopathic Parkinson's disease.",1
"Davie, C A, Pirtosek, Z, Barker, G J, Kingsley, D P, Miller, P H, Lees, A J",2
"Hereditary cerebral haemorrhage with amyloidosis, Dutch type (HCHWA-D): clinicopathological studies.",0
"Clinical and neuropathological findings are reported in 63 patients with hereditary cerebral haemorrhage with amyloid angiopathy. Patients had mostly recurrent strokes, and at least 80% of these were haemorrhages. Almost a third of the patients died within a year of their first and only recorded haemorrhage, half of them within two weeks. This angiopathy was restricted to the cerebral and cerebellar cortex and its covering leptomeninges. As the most important consequence, haemorrhagic infarcts and haemorrhages occurred in the subcortical white matter--that is, the region most vulnerable to impaired cortical circulation. Further development of these subcortical lesions gives rise to the fatal haemorrhages seen at necropsy. In so far as dementia occurs this is likely to result from multiple microinfarcts or haemorrhages. In most cases preamyloid lesions or diffuse plaques and early plaques were seen. No other type of plaque or neurofibrillary degeneration was found. The plaques occur in conjunction with the angiopathy, but may not occur even when the angiopathy is severe. In one patient plaques were totally absent. Angiopathy and plaques may be the result of the same mutation, the expression of which is governed by tissue factors or phenotypic differences between individual subjects.",1
"Wattendorff, A R, Frangione, B, Luyendijk, W, Bots, G T",2
Outcome in conversion disorder: a follow up study.,0
"Fifty six patients who had been admitted with a conversion disorder other than pseudoseizures were interviewed; mostly by telephone. The median interval was 4.5 years. If a patient had improved during a stay in hospital the eventual outcome was good in 96%, against only 30% in the others (risk ratio 3.2 (95% CI 1.8-5.6)). Rapid improvement was, in turn, related to recent onset of the symptoms. Two patients (4%) subsequently developed an organic deficit that, in retrospect, might be related to the initial episode.",1
"Couprie, W, Wijdicks, E F, Rooijmans, H G, van Gijn, J",2
Prediction of outcome in severe head injury based on recognition of sleep related activity in the polygraphic electroencephalogram.,0
"This study shows that the continuing presence of activity similar to normal sleep in the EEG in conjunction with the EEG polygraph (EEGP) can be used to determine the severity of brain damage after head injury. Recordings were taken within seven days of head injury from 154 unselected patients after resuscitation and emergency surgery. Sixteen patients with ongoing seizures were excluded. In the remaining 138 patients the presence of activity in the EEG, EEGP, or both, which can also be recognised in normal alertness and sleep, was noted. Particular attention was paid to the presence or absence of arousal related phasic activity involving EEG, motor, and autonomic changes. The traces were allocated to one of five groups: group 1, wakeful traces with normal alpha in at least one hemisphere; group 2, sleep-like traces with K complexes responsive to stimulation; group 3, traces with phasic activity related to abnormal spontaneous arousal including EEG changes; group 4, traces with abnormal spontaneous arousal activity without EEG changes; group 5, traces with no spontaneous arousal activity. The mean follow up was 21.5 months. Groups 2 and 3 were significantly associated with a good outcome and group 5 with death or a vegetative state. Comparison between the EEG/EEGP findings and the Glasgow coma scale at the time of the recording showed the EEG/EEGP to be the better predictor of outcome, particularly for individual patients.",1
"Evans, B M, Bartlett, J R",2
SPECT in the localisation of extratemporal and temporal seizure foci.,0
"The yield of ictal, postictal, and interictal SPECT was compared in the localisation of seizure foci in 177 patients with partial epilepsy. In 119 patients with known unilateral temporal lobe epilepsy ictal SPECT (97% correct localisation) was superior to postictal SPECT (71% correct), which was better than interictal studies (48% correct). Similarly, in cases of known or suspected extratemporal epilepsy the yield of ictal SPECT studies was high (92%). By contrast, the yield of postictal studies was much lower (46%) and usually only very early postictal studies were diagnostic. Interictal SPECT was of little value. The accuracy of ictal SPECT in localising temporal lobe seizures is now well established. Extratemporal seizures are often brief and difficult to localise. This report shows that ictal SPECT also has a high diagnostic yield in a wide range of extratemporal epilepsies. The brevity of many extratemporal seizures means that true ictal SPECT examinations can be difficult to achieve, but the high diagnostic yield justifies the special organisational effort needed to obtain such studies.",1
"Newton, M R, Berkovic, S F, Austin, M C, Rowe, C C, McKay, W J, Bladin, P F",2
Dexamethasone treatment for acute bacterial meningitis: how strong is the evidence for routine use?,0
"A methodological appraisal of the published randomised controlled trials on the use of dexamethasone as an adjunct treatment in acute bacterial meningitis was carried out to examine whether the available evidence is strong enough to support the routine use of the drug. Studies were eligible for inclusion if they were published in indexed journals after 1966, written in English, and were randomised controlled trials with dexamethasone as adjunct to antimicrobials in patients with acute bacterial meningitis. All studies were extracted and their adherence to eight methodological principles was graded as adequate, inadequate, or unclear. A sensitivity analysis was done to examine the robustness of the conclusions. Seven studies met the eligibility criteria. No report adhered to all the principles. Major threats to validity of the conclusions included potential bias in analysis in all the studies, and lack of adjustment for baseline imbalances in four. Inadequate reporting of adverse effects hindered risk-benefit analysis. Sensitivity analysis showed that the numbers of patients withdrawn from analysis were enough to invalidate the conclusions. It is concluded that the available evidence is not strong enough to support a routine use of dexamethasone in acute bacterial meningitis. Further research is needed to determine the effect of a policy to use dexamethasone early in the management of suspected acute bacterial meningitis. Future studies should adopt a pragmatic approach, be methodologically rigorous, and meticulously measure the risk as well as the benefit of this policy.",1
"Prasad, K, Haines, T",2
Prevalence and clinical correlates of pathological affective display in Alzheimer's disease.,0
"This study examined the prevalence and correlates of pathological affect in Alzheimer's disease. A consecutive series of 103 patients with Alzheimer's disease were examined with a comprehensive psychiatric assessment that included the pathological laughing and crying scale (PLACS). Forty patients (39%) showed pathological affect: 25% showed crying episodes, and 14% showed laughing or mixed (laughing and crying) episodes. Patients with pathological affect crying showed significantly higher depression scores and a significantly higher frequency of major depression and dysthymia than patients with no pathological affect. Patients with mixed pathological affect showed significantly more subcortical atrophy on CT than patients with pathological affect crying. Forty seven per cent of the patients with pathological affect had no congruent mood disorder, and they showed a significantly longer duration of illness and more severe anosognosia than patients with pathological affect that was congruent with an underlying mood disorder. The study validates the PLACS, and shows the high prevalence of pathological affect in Alzheimer's disease.",1
"Starkstein, S E, Migliorelli, R, Tesón, A, Petracca, G, Chemerinsky, E, Manes, F, Leiguarda, R",2
Frontotemporal dementia and Alzheimer's disease: retrospective differentiation using information from informants.,0
"The study examined the feasibility of differentiating frontotemporal dementia from Alzheimer's disease on the basis of retrospective historical information obtained from relatives of patients. A structured questionnaire was devised of patients' symptoms, with emphasis on those cognitive and neuropsychiatric features found in earlier prospective clinical studies to distinguish the two conditions. The questionnaire was given to close relatives of deceased patients in whom the diagnosis of non-Alzheimer's frontotemporal degeneration of Alzheimer's disease had been verified at necropsy. The interviewer had no previous contact or knowledge of those patients, nor clinical experience of patients with frontotemporal dementia. The questionnaire elicited a distinct profile of responses for the two diagnostic groups with emphasis on early personality change, unconcern, and socially inappropriate behaviour in frontotemporal dementia and disturbance in memory and topographical orientation prominent in patients with Alzheimer's disease. A scoring system separated out individual patients with frontotemporal dementia from those with Alzheimer's disease. It is concluded that it is possible to obtain useful information about the precise pattern of dementia from informants even many years after the patient's death. The questionnaire provides the foundation of a diagnostic instrument for use in family history studies of dementia.",1
"Barber, R, Snowden, J S, Craufurd, D",2
Multiple sclerosis in the north Cambridgeshire districts of East Anglia.,0
"The Cambridgeshire multiple sclerosis register was established in 1989 and initially reported a prevalence of 130/10(5) population for south and east Cambridgeshire (south Cambs). This survey has now been extended to the northern county districts where there were 449 patients with multiple sclerosis in population of 378,959 on 1 July 1993 (118/10(5); 95% confidence interval (95% CI) 108-130). Four hundred and four had either definite or probable disease (107/10(5); 95% CI: 98-118). This matches the highest figures in the series of seven epidemiological surveys carried out in southern England over the past decade. Comparison with these and other studies indicates that no latitudinal gradient of disease is found in southern England despite spanning four degrees of latitude.",1
"Robertson, N, Deans, J, Fraser, M, Compston, D A",2
Attention related performance in two cognitively different subgroups of patients with multiple sclerosis.,0
"To evaluate the underlying mechanisms of cognitive decline in multiple sclerosis, two clinically and demographically matched multiple sclerosis groups differing in cognitive status were assessed with attention related tasks. In addition to the attention tests recommended by the Cognitive Function Study Group of the American National Multiple Sclerosis Society, a test of sustained attention was used to evaluate the role of possible fatigue on cognitive performance. The cognitively mildly deteriorated group was slower than the cognitively preserved group and the controls on all tests of attention. The mildly deteriorated group did not, however, consistently differ from the other groups in the error scores of the attention tests. The preserved group exhibited slowness at the end of the visual vigilance test, but no deficits were found on the other attention related tests in this group. It is suggested that dissociable kinds of processing slowness are the origin of the deficits found on the attention tests in the two multiple sclerosis groups. Our preserved group exhibited signs of motor and fatigue related slowness, whereas the mildly deteriorated group also had extensive cognitive slowness. As sensitive indicators of cognitive slowness, attentional tests should be included in evaluation of the cognitive status of patients with multiple sclerosis.",1
"Kujala, P, Portin, R, Revonsuo, A, Ruutiainen, J",2
Sexual function in women with advanced multiple sclerosis.,0
"Changes in sexual function in 47 women with advanced multiple sclerosis are described. Twenty eight (59.6%) of the women reported decreased sexual desire. Seventeen (36.2%) reported decreased lubrication. Five (10.6%) others did not know if they lubricated or not. Eighteen women (38.3%) reported diminished orgasmic capacity and six (12.8%) others had never had an orgasm. Sensory dysfunction in the genital area was experienced by 61.7% of the women and 76.6% had weakness of the pelvic muscles. Sixty six per cent had bowel problems and 89.4% had bladder dysfunction. The changes in sexual function correlated both with neurological symptoms from the sacral segments, such as weakness of the pelvic floor and bladder and bowel dysfunction, and to other symptoms such as ataxia and vertigo as well as with age and the occurrence of amenorrhoea. A significant correlation was found between expanded disability status scale (EDSS) score and cohabitation. Problems with sexual function were reported significantly more often by women with lower EDSS scores. Most women (83%) found the interview a positive experience.",1
"Hulter, B M, Lundberg, P O",2
Cerebellar border zone infarcts are often associated with presumed cardiac sources of ischaemic stroke.,0
"It has been suggested that most border zone cerebellar infarcts are embolic infarcts or infarcts due to hypercoagulatble states. The aim of this study was to test this hypothesis. Risk factors for the presumed mechanism of stroke (TOAST criteria) were studied in 14 consecutive patients (nine men, five women; age range 29-84 years) with a total of 17 border zone cerebellar infarcts. The presumed cause of stroke was ""cardioembolism"" in nine patients. Three patients had a dissection of the vertebral artery. Two patients had a negative diagnostic investigation, and one had a cardiac arrest. These findings support the hypothesis that cardioembolism is a frequent mechanism of border zone cerebellar infarcts.",1
"Mounier-Vehier, F, Degaey, I, Leclerc, X, Leys, D",2
Sequence of the superoxide dismutase 1 (SOD 1) gene in familial Parkinson's disease.,0
"Mutations in the superoxide dismutase 1 (SOD1) gene have been detected in affected members of some families with familial amyotrophic lateral sclerosis. To evaluate the possibility of a shared genetic defect in amyotrophic lateral sclerosis and Parkinson's disease, the SOD1 gene was sequenced in index patients with familial Parkinson's disease from 23 families. No changes were detected.",1
"Bandmann, O, Davis, M B, Marsden, C D, Harding, A E",2
The LIM/homeodomain protein Islet1 recruits Janus tyrosine kinases and signal transducer and activator of transcription 3 and stimulates their activities.,0
"Islet1 (Isl1) belongs to the LIM homeodomain transcription factor family. Its roles in differentiation of motor neurons and organogenesis of pancreas and heart have been revealed. However, less is known about its regulatory mechanism and the target genes. In this study, we identified interactions between Isl1 and Janus tyrosine kinase (JAK), as well as signal transducer and activator of transcription (Stat)3, but not Stat1 and Stat5, in mammalian cells. We found that Isl1 not only forms a complex with Jak1 and Stat3 but also triggers the tyrosine phosphorylation of Jak1 and its kinase activity, thereby elevating the tyrosine phosphorylation, DNA binding activity, and target gene expression of Stat3. In vivo, the tyrosine-phosphorylated Stat3 was colocalized with Isl1 in the nucleus of the mouse motor neurons in spinal cord after nerve injury. Correspondingly, electroporation of Isl1 and Stat3 into the neural tube of chick embryos resulted in the activation of a reporter gene expression controlled by a Stat3 regulatory sequence, and cotransfection of Isl1 and Stat3 promoted the proliferation of the mouse motor neuron cells. Our data suggest a novel role of Isl1 as an adaptor for Jak1 and Stat3 and reveal a possible functional link between LIM homeodomain transcription factors and the Jak-Stat pathway.",1
"Hao, Aijun, Novotny-Diermayr, Veronica, Bian, Wei, Lin, Baohong, Lim, Cheh Peng, Jing, Naihe, Cao, Xinmin",2
Atg11 links cargo to the vesicle-forming machinery in the cytoplasm to vacuole targeting pathway.,0
"Proteins are selectively packaged into vesicles at specific sites and then delivered correctly to the various organelles where they function, which is critical to the proper physiology of each organelle. The precursor form of the vacuolar hydrolase aminopeptidase I is a selective cargo molecule of the cytoplasm to vacuole targeting (Cvt) pathway and autophagy. Precursor Ape1 along with its receptor Atg19 forms the Cvt complex, which is transported to the pre-autophagosomal structure (PAS), the putative site of Cvt vesicle formation, in a process dependent on Atg11. Here, we show that this interaction occurs through the Atg11 C terminus; subsequent recruitment of the Cvt complex to the PAS depends on central regions within Atg11. Atg11 was shown to physically link several proteins, although the timing of these interactions and their importance are unknown. Our mapping shows that the Atg11 coiled-coil domains are involved in self-assembly and the interaction with other proteins, including two previously unidentified partners, Atg17 and Atg20. Atg11 mutants defective in the transport of the Cvt complex to the PAS affect the localization of other Atg components, supporting the idea that the cargo facilitates the organization of the PAS in selective autophagy. These findings suggest that Atg11 plays an integral role in connecting cargo molecules with components of the vesicle-forming machinery.",1
"Yorimitsu, Tomohiro, Klionsky, Daniel J",2
Ase1p organizes antiparallel microtubule arrays during interphase and mitosis in fission yeast.,0
"Proper microtubule organization is essential for cellular processes such as organelle positioning during interphase and spindle formation during mitosis. The fission yeast Schizosaccharomyces pombe presents a good model for understanding microtubule organization. We identify fission yeast ase1p, a member of the conserved ASE1/PRC1/MAP65 family of microtubule bundling proteins, which functions in organizing the spindle midzone during mitosis. Using fluorescence live cell imaging, we show that ase1p localizes to sites of microtubule overlaps associated with microtubule organizing centers at both interphase and mitosis. ase1Delta mutants fail to form overlapping antiparallel microtubule bundles, leading to interphase nuclear positioning defects, and premature mitotic spindle collapse. FRAP analysis revealed that interphase ase1p at overlapping microtubule minus ends is highly dynamic. In contrast, mitotic ase1p at microtubule plus ends at the spindle midzone is more stable. We propose that ase1p functions to organize microtubules into overlapping antiparallel bundles both in interphase and mitosis and that ase1p may be differentially regulated through the cell cycle.",1
"Loïodice, Isabelle, Staub, Jayme, Setty, Thanuja Gangi, Nguyen, Nam-Phuong T, Paoletti, Anne, Tran, P T",2
Identification of xenopus CENP-A and an associated centromeric DNA repeat.,0
"Kinetochores are the proteinaceous complexes that assemble on centromeric DNA and direct eukaryotic chromosome segregation. The mechanisms by which higher eukaryotic cells define centromeres are poorly understood. Possible molecular contributors to centromere specification include the underlying DNA sequences and epigenetic factors such as binding of the centromeric histone centromere protein A (CENP-A). Frog egg extracts are an attractive system for studying centromere definition and kinetochore assembly. To facilitate such studies, we cloned a Xenopus laevis homologue of CENP-A (XCENP-A). We identified centromere-associated DNA sequences by cloning fragments of DNA that copurified with XCENP-A by chromatin immunoprecipitation. XCENP-A associates with frog centromeric repeat 1 (Fcr1), a 174-base pair repeat containing a possible CENP-B box. Southern blots of partially digested genomic DNA revealed large ordered arrays of Fcr1 in the genome. Fluorescent in situ hybridization with Fcr1 probes stained most centromeres in cultured cells. By staining lampbrush chromosomes, we specifically identified the 11 (of 18) chromosomes that stain consistently with Fcr1 probes.",1
"Edwards, Nathaniel S, Murray, Andrew W",2
Sequestration of pRb by cyclin D3 causes intranuclear reorganization of lamin A/C during muscle cell differentiation.,0
"The A-type lamins that localize in nuclear domains termed lamin speckles are reorganized and antigenically masked specifically during myoblast differentiation. This rearrangement was observed to be linked to the myogenic program as lamin speckles, stained with monoclonal antibody (mAb) LA-2H10, were reorganized in MyoD-transfected fibroblasts induced to transdifferentiate to muscle cells. In C2C12 myoblasts, speckles were reorganized early during differentiation in cyclin D3-expressing cells. Ectopic cyclin D3 induced lamin reorganization in C2C12 myoblasts but not in other cell types. Experiments with adenovirus E1A protein that can bind to and segregate the retinoblastoma protein (pRb) indicated that pRb was essential for the cyclin D3-mediated reorganization of lamin speckles. Cyclin D3-expressing myoblasts displayed site-specific reduction of pRb phosphorylation. Furthermore, disruption of lamin structures by overexpression of lamins inhibited expression of the muscle regulatory factor myogenin. Our results suggest that the reorganization of internal lamins in muscle cells is mediated by key regulators of the muscle differentiation program.",1
"Mariappan, Indumathi, Parnaik, Veena K",2
SNX9 regulates dynamin assembly and is required for efficient clathrin-mediated endocytosis.,0
"Dynamin, a central player in clathrin-mediated endocytosis, interacts with several functionally diverse SH3 domain-containing proteins. However, the role of these interactions with regard to dynamin function is poorly defined. We have investigated a recently identified protein partner of dynamin, SNX9, sorting nexin 9. SNX9 binds directly to both dynamin-1 and dynamin-2. Moreover by stimulating dynamin assembly, SNX9 stimulates dynamin's basal GTPase activity and potentiates assembly-stimulated GTPase activity on liposomes. In fixed cells, we observe that SNX9 partially localizes to clathrin-coated pits. Using total internal reflection fluorescence microscopy in living cells, we detect a transient burst of EGFP-SNX9 recruitment to clathrin-coated pits that occurs during the late stages of vesicle formation and coincides spatially and temporally with a burst of dynamin-mRFP fluorescence. Transferrin internalization is inhibited in HeLa cells after siRNA-mediated knockdown of SNX9. Thus, our results establish that SNX9 is required for efficient clathrin-mediated endocytosis and suggest that it functions to regulate dynamin activity.",1
"Soulet, Fabienne, Yarar, Defne, Leonard, Marilyn, Schmid, Sandra L",2
The carboxyl terminus of VEGFR-2 is required for PKC-mediated down-regulation.,0
"Vascular endothelial growth factor receptor-2 (VEGFR-2/Flk-1) is a receptor tyrosine kinase (RTK) whose activation regulates angiogenesis. The regulatory mechanisms that attenuate VEGFR-2 signal relay are largely unknown. Our study shows that VEGFR-2 promotes phosphorylation of c-Cbl, but activation, ubiquitylation, and down-regulation of VEGFR-2 are not influenced by c-Cbl activity. A structure-function analysis of VEGFR-2 and pharmacological approach revealed that down-regulation of VEGFR-2 is mediated by a distinct mechanism involving PKC. A tyrosine mutant VEGFR-2, defective in PLC-gamma1 activation underwent down-regulation efficiently in response to ligand stimulation, suggesting that activation of classical PKCs are not involved in VEGFR-2 down-regulation. Further studies showed that the ectodomain of VEGFR-2 is dispensable for PKC-dependent down-regulation. Progressive deletion of the carboxyl-terminal domain showed that at least 39 amino acids within the carboxyl-terminal domain, immediately C-terminal to the kinase domain, is required for efficient PKC-mediated down-regulation of VEGFR-2. Mutation of serine sites at 1188 and 1191, within this 39 amino acid region, compromised the ability of VEGFR-2 to undergo efficient ligand-dependent down-regulation. Altogether the results show that the regulatory mechanisms involved in the attenuation of VEGFR-2 activation is mediated by nonclassical PKCs and the presence of serine sites in the carboxyl terminal of VEGFR-2.",1
"Singh, Amrik J, Meyer, Rosana D, Band, Hamid, Rahimi, Nader",2
The yeast phosphotyrosyl phosphatase activator is part of the Tap42-phosphatase complexes.,0
"Phosphotyrosyl phosphatase activator PTPA is a type 2A phosphatase regulatory protein that possesses an ability to stimulate the phosphotyrosyl phosphatase activity of PP2A in vitro. In yeast Saccharomyces cerevisiae, PTPA is encoded by two related genes, RRD1 and RRD2, whose products are 38 and 37% identical, respectively, to the mammalian PTPA. Inactivation of either gene renders yeast cells rapamycin resistant. In this study, we investigate the mechanism underling rapamycin resistance associated with inactivation of PTPA in yeast. We show that the yeast PTPA is an integral part of the Tap42-phosphatase complexes that act downstream of the Tor proteins, the target of rapamycin. We demonstrate a specific interaction of Rrd1 with the Tap42-Sit4 complex and that of Rrd2 with the Tap42-PP2Ac complex. A small portion of PTPA also is found to be associated with the AC dimeric core of PP2A, but the amount is significantly less than that associated with the Tap42-containing complexes. In addition, our results show that the association of PTPA with Tap42-phosphatase complexes is rapamycin sensitive, and importantly, that rapamycin treatment results in release of the PTPA-phosphatase dimer as a functional phosphatase unit.",1
"Zheng, Yin, Jiang, Yu",2
Spontaneous intracranial hypotension.,0
The clinical features and radiological appearances of spontaneous intracranial hypotension are described in three patients and the medical literature is reviewed. Awareness of this condition and its differentiation from more sinister meningitic processes is important to avoid unnecessary invasive investigations and to allow prompt diagnosis and effective treatment.,1
"Renowden, S A, Gregory, R, Hyman, N, Hilton-Jones, D",2
Early and severe sensory loss in three adult siblings with hexosaminidase A and B deficiency (Sandhoff disease).,0
"Three siblings in their sixth and seventh decade with hexosaminidase A and B deficiency (adult form of GM2-gangliosidosis, variant O) developed early and severe sensory loss in addition to chronic motor neuron disease and cerebellar ataxia. Prominent mechanoallodynia was a manifesting symptom in two siblings. It is suggested that sensory deficits are due to a central-peripheral dying back axonopathy. The early and dominant sensory disturbances extend the clinical range of GM2-gangliosidosis.",1
"Schnorf, H, Gitzelmann, R, Bosshard, N U, Spycher, M, Waespe, W",2
Parietal kinetic ataxia without proprioceptive deficit.,0
"A patient with acute onset ""classic"" cerebellar ataxia of the right arm without clinically detectable deep sensory loss is reported, in relation to an acute posterior parietal infarct. Wild back and forth swaying of the arm, giving away, or worsening by suppression of vision were not seen. The lesion involved area 5, parts of area 7, the angular gyrus, the middle and posterior parieto-occipital gyri, and posterior parts of the superior and middle temporal gyri. The paracentral lobule, commonly thought to be responsible for parietal ataxia, was spared. Thus posterior parietal lesions can mimick cerebellar ataxia, possibly by severing specific projections to the ventrolateral thalamic nuclei. On the basis of previous studies in primates, the superior parietal gyrus may play a major part in the ataxia presented by this patient.",1
"Ghika, J, Bogousslavsky, J, Uske, A, Regli, F",2
Comparison of triple dose versus standard dose gadolinium-DTPA for detection of MRI enhancing lesions in patients with primary progressive multiple sclerosis.,0
"This study was performed to evaluate whether a triple dose of gadolinium-DTPA (Gd-DTPA) increases the sensitivity of brain MRI for detecting enhancing lesions in patients with primary progressive multiple sclerosis (PPMS). T1 weighted brain MRI was obtained for 10 patients with PPMS in two sessions. In the first session, one scan was obtained five to seven minutes after the injection of 0.1 mmol/kg Gd-DTPA (standard dose). In the second session, six to 24 hours later, one scan before and two scans five to seven minutes and one hour after the injection of 0.3 mmol/kg Gd-DTPA (triple dose) were obtained. Four enhancing lesions were detected in two patients when the standard dose of Gd-DTPA was used. The numbers of enhancing lesions increased to 13 and the numbers of patients with such lesions to five when the triple dose of Gd-DTPA was used and to 14 and six in the one hour delayed scans. The mean contrast ratio for enhancing lesions detected with the triple dose of Gd-DTPA was higher than those for lesions present in both the standard dose (P < 0.0009) and the one hour delayed scans (P = 0.04). These data indicate that with a triple dose of Gd-DTPA many more enhancing lesions can be detected in patients with PPMS. This is important both for planning clinical trials and for detecting the presence of inflammation in vivo in the lesions of such patients.",1
"Filippi, M, Campi, A, Martinelli, V, Colombo, B, Yousry, T, Canal, N, Scotti, G, Comi, G",2
New phenotype of the cerebral autosomal dominant arteriopathy mapped to chromosome 19: migraine as the prominent clinical feature.,0
"A survey was carried out on a large family presenting the symptoms of familial arteriopathy (CADASIL) recently mapped to chromosome 19. This is characterised clinically by recurrent subcortical infarcts developing into pseudobulbar palsy and subcortical dementia, and radiologically by early MRI abnormalities. To characterise this familial condition, 43 members older than 20 years and spreading over four generations were studied clinically (31 living, 12 deceased), genetically, and radiologically by MRI (n = 31). Twenty out of 43 were found to be clinically symptomatic and of these 13 out of 31 had MRI abnormalities. Genetic studies mapped this condition to the locus of CADASIL (lod score > 3). The natural history suggests a chronological clinicoradiological staging of this phenotype of CADASIL: stage I between 20 and 40 years with frequent migraine-like episodes and well delineated lesions of the white matter; stage II between 40 and 60 years with stroke-like episodes, bipolar or monopolar-like psychotic disorders, coalescent lesions of the white matter, and well delineated lesions of the basal ganglia; and stage III over 60 years with subcortical dementia, pseudobulbar palsy, diffuse leukoencephalopathy, and multiple well delineated lesions of the basal ganglia. This phenotype differs from the other two previously described by high frequency of migraine, frequency of psychotic disorders, and early neurological manifestations. The new acronym ""cerebral autosomal dominant arteriopathy with subcortical infarcts, leukoencephalopathy, and migraine"" (CADASILM) is proposed to better describe this particular subvariety of CADASIL.",1
"Vérin, M, Rolland, Y, Landgraf, F, Chabriat, H, Bompais, B, Michel, A, Vahedi, K, Martinet, J P, Tournier-Lasserve, E, Lemaitre, M H",2
The silent period induced by transcranial magnetic stimulation in muscles supplied by cranial nerves: normal data and changes in patients.,0
"The silent period induced by transcranial magnetic stimulation of the sensorimotor cortex (Magstim 200, figure of eight coil, loop diameter 7 cm) in active muscles supplied by cranial nerves (mentalis, sternocleidomastoid, and genioglossus) was studied in 14 control subjects and nine patients with localised lesions of the sensorimotor cortex. In the patients, measurements of the silent period were also made in the first dorsal interosseus and tibialis anterior muscles. In the controls, there was a silent period in contralateral as well as ipsilateral cranial muscle and the duration of the silent period increased with increasing stimulus intensities. The mean duration of the silent period was around 140 ms in contralateral mentalis muscle and around 90 ms in contralateral sternocleidomastoid muscle at 1.2 x threshold stimulation strengths. Whereas the duration of the silent period in ipsilateral mentalis muscle was shorter than on the contralateral side it was similar on both sides in sternocleidomastoid muscle. In patients with focal lesions of the face associated primary motor cortex and corresponding central facial paresis, the silent period in mentalis muscle was shortened whereas it was unchanged or prolonged in limb muscles (first dorsal interosseus, tibialis anterior) with stimulation over the affected hemisphere. By contrast, in a patient with a lesion within the parietal cortex, the silent period in mentalis muscle was prolonged with stimulation of the affected side.",1
"Werhahn, K J, Classen, J, Benecke, R",2
Clinical and [18F] dopa PET findings in early Parkinson's disease.,0
"Twenty seven patients with recent onset (mean symptom duration 22 (SD 14) months, Hoehn and Yahr score 1.8 (SD 0.7)) Parkinson's disease were studied with [18F]dopa PET. There was a correlation between putamen influx (Ki) and clinical rating, but not symptom duration. In 11 patients with hemi-Parkinson's disease of recent onset there were significant differences between normal (mean 0.0123 (SD 0.0023)), asymptomatic (mean 0.0099 (0.0020)) and symptomatic (mean 0.0070 (00.014)) putamen Kis. This suggests that Parkinson's disease has a widely variable rate of progression, and is most compatible with a short preclinical period. Symptom onset was estimated at a putamen Ki of between 57% and 80% of normal. Most ipsilateral putamen Ki values in early asymmetric Parkinson's disease fell within the normal range. The implication is that either the disease is not established in the ipsilateral putamen or that the technique is insufficiently sensitive to detect it. Discriminant analysis completely separated the normal and Parkinson's disease cohorts, but when a discriminant function from a previous study was used predictively four of the 27 patients with Parkinson's disease were incorrectly classified as normal.",1
"Morrish, P K, Sawle, G V, Brooks, D J",2
Botulinum toxin F in the treatment of torticollis clinically resistant to botulinum toxin A.,0
"Two reports have shown a Japanese preparation of botulinum toxin type F (BTX-F) to be an effective alternative for patients with torticollis who develop clinical resistance to botulinum toxin type A (BTX-A). A group of patients with torticollis, comprising five secondary non-responders and one primary non-responder, were treated with a preparation of BTX-F produced in the UK (Speywood Pharmaceuticals). A low dose of BTX-F (220 mouse units (MU) in total) was given into clinically affected neck muscles, followed six weeks later by an injection of a total of 520 MU. Antibodies to BTX-A (mouse protection assay) were present in all secondary non-responders but not in the primary non-responder. No patients developed atrophy after injection of Dysport BTX-A (40 MU) into the left extensor digitorum brevis muscle whereas pronounced atrophy occurred in all patients after injection of 40 MU of BTX-F into the right extensor digitorum brevis muscle. Three patients improved subjectively after treatment with 220 MU BTX-F and five (all secondary non-responders) after the subsequent dose of 520 MU (two considerably), with reduced Tsui scores, but group scores were only significantly changed after the higher dose. The primary non-responder remained unchanged after both doses of BTX-F. One patient reported mild dysphagia with 520 MU BTX-F. Mean duration of improvement with 520 MU BTX-F was five (range 4-6)weeks. Thus BTX-F provides benefit for BTX-A non-responders with few side effects but for a shorter period than BTX-A, possibly due to relative underdosing. As with BTX-A, biological sensitivity to BTX-F does not necessarily predict a clinical response.",1
"Sheean, G L, Lees, A J",2
"Incidence, management, and outcome of post-traumatic syringomyelia. In memory of Mr Bernard Williams.",0
To determine the incidence of clinically diagnosable post-traumatic syringomyelia (PTS).,1
"el Masry, W S, Biyani, A",2
Aspirin at any dose above 30 mg offers only modest protection after cerebral ischaemia.,0
"There is continuing debate about the relative efficacy of low (< 100 mg per day), medium (300 to 325 mg per day), and high (> 900 mg per day) doses of aspirin in patients after a transient ischaemic attack or non-disabling stroke. The purpose of this study was to resolve the issue. Thus a minimeta-analysis was performed on data from 10 randomised trials of aspirin only v control treatment in 6171 patients after a transient ischaemic attack or nondisabling stroke. The data on the trials were listed in an appendix of the report on the second cycle of the Antiplatelet Trialists' Collaboration. There was virtually no difference in relative risk reduction for low, medium, and high doses of aspirin (13%, 9%, and 14% respectively). This equivalence corresponds with the results of the UK-TIA trial in a direct comparison of 300 and 1200 mg. The Dutch TIA trial showed no difference in efficacy of 30 and 283 mg. It is concluded that aspirin at any dose above 30 mg daily prevents 13% (95% confidence interval 4-21) of vascular events and that there is a need for more efficacious drugs.",1
"Algra, A, van Gijn, J",2
Intracranial intraparenchymal schwannomas: a series of eight cases.,0
"Intraparenchymal schwannomas of the CNS are extremely rare. Between 1979 and 1993 400 cases of intracranial schwannomas were operated on and among them were eight patients with intraparenchymal schwannomas comprising 2% of intracranial benign nerve sheath tumours. Four of them were located in the cerebral hemispheres and two each in the brain stem and in the cerebellum. In two cases, there was associated neurofibromatosis (NF-1 and NF-2, one case each). The age ranged from 6 months to 45 years with a male/female ratio of 3:1 and, surprisingly, six of them were in the left cerebral or cerebellar hemisphere.",1
"Sharma, M C, Karak, A K, Gaikwad, S B, Mahapatra, A K, Mehta, V S, Sudha, K",2
Multiple acute infarcts in the posterior circulation.,0
"to evaluate clinical, radiological, and prognostic features of patients with multiple acute infarcts in remote arterial territories of the posterior circulation.",1
"Bernasconi, A, Bogousslavsky, J, Bassetti, C, Regli, F",2
An audit of aneurysmal subarachnoid haemorrhage: earlier resuscitation and surgery reduces inpatient stay and deaths from rebleeding.,0
To audit the outcome in patients with subarachnoid haemorrhage (SAH) after a change in management strategy.,1
"Whitfield, P C, Moss, H, O'Hare, D, Smielewski, P, Pickard, J D, Kirkpatrick, P J",2
"The ""Gulf War syndrome"". Is there evidence of dysfunction in the nervous system?",0
"In a pilot study, 14 Gulf War veterans were randomly selected from a large list of those with unexplained illness, to compare the functional integrity of the peripheral and central nervous system with a group of 13 healthy civilian control subjects using predetermined outcome measures. The controls were matched closely for age, sex, handedness, and physical activity. Outcome measures included scoring of symptoms and clinical neurological signs, quantitative sensory testing of heat, cold and vibration sensibilities, motor and sensory nerve conduction studies on upper and lower limbs, needle EMG of distal and proximal muscles and multimodality evoked potential (visual, brainstem, and somatosensory) studies. Three measurements, all related to peripheral nerve function (cold threshold (P = 0.0002), sural nerve latency (P = 0.034), and median nerve sensory action potential (P = 0.030) were abnormal in the veterans compared with the controls. There may be a dysfunction in the veterans but more studies are required to investigate the findings further and to characterise the dysfunction if confirmed.",1
"Jamal, G A, Hansen, S, Apartopoulos, F, Peden, A",2
"Incidence of intracranial tumours in the Lothian region of Scotland, 1989-90.",0
To determine the incidence of primary and secondary intracranial tumours in the Lothian region of south east Scotland.,1
"Counsell, C E, Collie, D A, Grant, R",2
Startle provoked epileptic seizures:features in 19 patients.,0
To define the clinical characteristics of a group of patients with startle provoked epileptic seizures (SPES).,1
"Manford, M R, Fish, D R, Shorvon, S D",2
Nerve conduction studies in adrenomyeloneuropathy.,0
"Adrenomyeloneuropathy (AMN) is an X linked metabolic disorder presenting with progressive spastic paraparesis in the third to fifth decade of life. Although peripheral neuropathy is also present in most patients, prominent pyramidal signs may make its clinical recognition difficult. The objective was to characterise the peripheral neuropathy in patients with AMN by nerve conduction studies.",1
"Chaudhry, V, Moser, H W, Cornblath, D R",2
Memory without context: amnesia with confabulations after infarction of the right capsular genu.,0
"To explore the mechanism of an amnesia marked by confabulations and lack of insight in a patient with an infarct of the right inferior capsular genu. The confabulations could mostly be traced back to earlier events, indicating that the memory disorder ensued from an inability to store the temporal and spatial context of information acquisition rather than a failure to store new information.",1
"Schnider, A, Gutbrod, K, Hess, C W, Schroth, G",2
A special form of cerebral lacunae: expanding lacunae.,0
"The case of a 42 year old man with headache, blurred vision, and diplopia allowed the description of a particular form of cerebral lacunae-that is, expanding lacunae. Brain MRI showed hydrocephalus and multiple lesions in the thalamomesencephalic region. The radiological features of these lesions were similar to the histological brain coronal section of a case reported in 1983 in which expanding lacunae were related to a dilatation of the perivascular spaces and a focal segmental necrotising angiitis. The role of the lymphatic drainage of the brain is discussed to explain the dilatation of the perivascular spaces. The hypothesis of a hydrodynamic factor being responsible for the expanding character of the lacunae was suggested by the location of the lesions and the influence of various clinical events on the symptomatology.",1
"Homeyer, P, Cornu, P, Lacomblez, L, Chiras, J, Derouesné, C",2
Cognitive impairment after acute encephalitis: comparison of herpes simplex and other aetiologies.,0
To compare the cognitive defects after acute acyclovir treated herpes simplex encephalitis with those after other types of acute encephalitis.,1
"Hokkanen, L, Poutiainen, E, Valanne, L, Salonen, O, Iivanainen, M, Launes, J",2
Ictal cerebral perfusion related to EEG in drug resistant focal epilepsy of childhood.,0
"To evaluate the EEG changes during seizures in children with drug resistant focal epilepsy who demonstrate hypoperfusion at the ""seizure focus"" interictally, but no perfusion change during the seizure.",1
"Cross, J H, Boyd, S G, Gordon, I, Harper, A, Neville, B G",2
Pulsed high dose dexamethasone treatment in chronic inflammatory demyelinating polyneuropathy: a pilot study.,0
Six cycles of dexamethasone (40 mg per day for four sequential days) every 28 days induced remissions in 10 patients with idiopathic thrombocytopenic purpura (ITP). Whether the same results could be achieved in 10 patients with chronic inflammatory demyelinating polyneuropathy (CIDP) was investigated by comparing the Rivermead mobility index (RMI) before and after six cycles of treatment. Three patients discontinued treatment: one because of severe nausea and vomiting and two because of neurological deterioration. All seven patients who completed treatment improved on the RMI. One of these patients had a relapse within two months after the last cycle and six patients were in remission six months after the last dexamethasone cycle. Pulsed high dose dexamethasone induced remissions ranged from at least 15 to 23 months. This treatment needs to be tested against standard treatment in a randomised study.,1
"Molenaar, D S, van Doorn, P A, Vermeulen, M",2
Recurrent neck pain as a variant of migraine: description of four cases.,0
"Four patients who had recurrent attacks of idiopathic unilateral neck pain and tenderness of the ipsilateral carotid artery are described. Two patients had never had headache. The other two had migraine without aura. All patients had dilatation of extracranial arteries during the attacks (telethermographic examination), oculosympathetic hypofunction (pupillary tests), and positive responses to vasoactive drugs which are commonly used for migraine treatment. Recurrent neck pain involving the carotid artery seems to be a variant form of migraine that may occur alone or in association with headache in patients with involvement of extracranial arteries.",1
"De Marinis, M, Accornero, N",2
Chromatin and RNAi factors protect the C. elegans germline against repetitive sequences.,0
"Protection of genomes against invasion by repetitive sequences, such as transposons, viruses, and repetitive transgenes, involves strong and selective silencing of these sequences. During silencing of repetitive transgenes, a trans effect (""cosuppression"") occurs that results in silencing of cognate endogenous genes. Here we report RNA interference (RNAi) screens performed to catalog genes required for cosuppression in the Caenorhabditis elegans germline. We find factors with a putative role in chromatin remodeling and factors involved in RNAi. Together with molecular data also presented in this study, these results suggest that in C. elegans repetitive sequences trigger transcriptional gene silencing using RNAi and chromatin factors.",1
"Robert, Valérie J P, Sijen, Titia, van Wolfswinkel, Josien, Plasterk, Ronald H A",2
Ddb1 controls genome stability and meiosis in fission yeast.,0
"The human UV-damaged DNA-binding protein Ddb1 associates with cullin 4 ubiquitin ligases implicated in nucleotide excision repair (NER). These complexes also contain the signalosome (CSN), but NER-relevant ubiquitination targets have not yet been identified. We report that fission yeast Ddb1, Cullin 4 (Pcu4), and CSN subunits Csn1 and Csn2 are required for degradation of the ribonucleotide reductase (RNR) inhibitor protein Spd1. Ddb1-deficient cells have >20-fold increased spontaneous mutation rate. This is partly dependent on the error-prone translesion DNA polymerases. Spd1 deletion substantially reduced the mutation rate, suggesting that insufficient RNR activity accounts for approximately 50% of observed mutations. Epistasis analysis indicated that Ddb1 contributed to mutation avoidance and tolerance to DNA damage in a pathway distinct from NER. Finally, we show that Ddb1/Csn1/Cullin 4-mediated Spd1 degradation becomes essential when cells differentiate into meiosis. These results suggest that Ddb1, along with Cullin 4 and the signalosome, constitute a major pathway controlling genome stability, repair, and differentiation via RNR regulation.",1
"Holmberg, Christian, Fleck, Oliver, Hansen, Heidi A, Liu, Cong, Slaaby, Rita, Carr, Antony M, Nielsen, Olaf",2
Olfactory blocking and odorant similarity in the honeybee.,0
"Blocking occurs when previous training with a stimulus A reduces (blocks) subsequent learning about a stimulus B, when A and B are trained in compound. The question of whether blocking exists in olfactory conditioning of proboscis extension reflex (PER) in honeybees is under debate. The last published accounts on blocking in honeybees state that blocking occurs when odors A and B are similar (the ""similarity hypothesis""). We have tested this hypothesis using four odors (1-octanol, 1-nonanol, eugenol, and limonene) chosen on the basis of their chemical and physiological similarity (experiment 1). We established a generalization matrix that measured perceptual similarity. Bees in the ""block group"" were first trained with an odor A and, in the second phase, with the mixture AB. Bees in the ""novel group"" (control group) were first trained with an odor N and, in the second phase, with the mixture AB. After conditioning, bees in both groups were tested for their response to B. We assayed all 24 possible combinations for the four odors standing for A, B, and N. We found blocking in four cases, augmentation in two cases, and no difference in 18 cases; odor similarity could not account for these results. We also repeated the experiments with those six odor combinations that gave rise to the similarity hypothesis (experiment 2: 1-hexanol, 1-octanol, geraniol) and found augmentation in one and no effect in five cases. Thus, blocking is not a consistent phenomenon, nor does it depend on odor similarity.",1
"Guerrieri, Fernando, Lachnit, Harald, Gerber, Bertram, Giurfa, Martin",2
Transgenic mice expressing a truncated form of CREB-binding protein (CBP) exhibit deficits in hippocampal synaptic plasticity and memory storage.,0
"Deletions, translocations, or point mutations in the CREB-binding protein (CBP) gene have been associated with Rubinstein-Taybi Syndrome; a human developmental disorder characterized by retarded growth and reduced mental function. To examine the role of CBP in memory, transgenic mice were generated in which the CaMKII alpha promoter drives expression of an inhibitory truncated CBP protein in forebrain neurons. Examination of hippocampal long-term potentiation (LTP), a form of synaptic plasticity thought to underlie memory storage, revealed significantly reduced late-phase LTP induced by dopamine-regulated potentiation in hippocampal slices from CBP transgenic mice. However, four-train induced late-phase LTP is normal. Behaviorally, CBP transgenic mice exhibited memory deficits in spatial learning in the Morris water maze and deficits in long-term memory for contextual fear conditioning, two hippocampus-dependent tasks. Together, these results demonstrate that CBP is involved in specific forms of hippocampal synaptic plasticity and hippocampus-dependent long-term memory formation.",1
"Wood, Marcelo A, Kaplan, Michael P, Park, Alice, Blanchard, Edward J, Oliveira, Ana M M, Lombardi, Thomas L, Abel, Ted",2
Glutamate receptor antagonist infusions into the basolateral and medial amygdala reveal differential contributions to olfactory vs. context fear conditioning and expression.,0
"The basolateral amygdala's involvement in fear acquisition and expression to visual and auditory stimuli is well known. The involvement of the basolateral and other amygdala areas in fear acquisition and expression to stimuli of other modalities is less certain. We evaluated the contribution of the basolateral and medial amygdala to olfactory and to context fear and fear conditioning by infusing into these areas the NMDA receptor antagonist AP5, the AMPA/kainate receptor antagonist NBQX, or vehicle prior to either odor-shock pairings or fear-potentiated startle testing. Pre-training AP5 infusions into the basolateral amygdala disrupted fear conditioning to the odor but not the context conditioned stimulus (CS). Pre-test NBQX infusions disrupted fear-potentiated startle to the odor but not context CS. Neither compound blocked fear conditioning when infused into the medial amygdala prior to training, but pre-test NBQX infusions did block fear-potentiated startle. The results confirm and extend recent findings suggesting a role for the basolateral amygdala in olfactory fear and fear conditioning, reveal an unexpected dissociation of the basolateral amygdala's involvement in discrete cue versus context fear and fear conditioning, and implicate for the first time the medial amygdala in fear-potentiated startle.",1
"Walker, David L, Paschall, Gayla Y, Davis, Michael",2
Acute stress facilitates trace eyeblink conditioning in C57BL/6 male mice and increases the excitability of their CA1 pyramidal neurons.,0
"The effects of stress (restraint plus tail shock) on hippocampus-dependent trace eyeblink conditioning and hippocampal excitability were examined in C57BL/6 male mice. The results indicate that the stressor significantly increased the concentration of circulating corticosterone, the amount and rate of learning relative to nonstressed conditioned mice, and the excitability of CA1 hippocampal pyramidal neurons. Behaviorally, there was no effect of the stressor on control mice that received unpaired presentations of the tone and periorbital shock, i.e., neither stressed nor nonstressed control mice showed an increase in conditioned responding that was above baseline levels. Biophysically, the stressor significantly decreased the amplitude of the post-burst afterhyperpolarization (AHP) and decreased spike frequency accommodation relative to cells from nonstressed control mice. The effect was significant for mice that were stressed either 1 h or 24 h earlier. The results suggest that the stressor increases the excitability of hippocampal pyramidal neurons and that the mechanism underlying this increase may contribute to the more rapid acquisition of hippocampally dependent eyeblink conditioning.",1
"Weiss, Craig, Sametsky, Evgeny, Sasse, Astrid, Spiess, Joachim, Disterhoft, John F",2
Expression of the immediate-early gene-encoded protein Egr-1 (zif268) during in vitro classical conditioning.,0
"Expression of the immediate-early genes (IEGs) has been shown to be induced by activity-dependent synaptic plasticity or behavioral training and is thought to play an important role in long-term memory. In the present study, we examined the induction and expression of the IEG-encoded protein Egr-1 during an in vitro neural correlate of eyeblink classical conditioning. The results showed that Egr-1 protein expression as determined by immunocytochemistry and Western blot analysis rapidly increased during the early stages of conditioning and remained elevated during the later stages. Further, expression of Egr-1 protein required NMDA receptor activation as it was blocked by bath application of AP-5. These findings suggest that the IEG-encoded proteins such as Egr-1 are activated during relatively simple forms of learning in vertebrates. In this case, Egr-1 may have a functional role in the acquisition phase of conditioning as well as in maintaining expression of conditioned responses.",1
"Mokin, Maxim, Keifer, Joyce",2
Intrahippocampal muscimol shifts learning strategy in gonadally intact young adult female rats.,0
"Learning strategy preferences depend upon circulating estrogen levels, with enhanced hippocampus-sensitive place learning coinciding with elevated estrogen levels. The effects of estrogen on strategy may be mediated by fluctuations in GABAergic function, given that inhibitory tone in the hippocampus is low when estrogen is high. We investigated the effects on learning strategy of intrahippocampal injections of a GABA(A) agonist in gonadally intact female rats. On the day of training, rats received 0.3 microL intrahippocampal infusions of muscimol (0.26 nmol or 2.6 nmol) or saline 20 min prior to training on a T-maze in which place (hippocampus-sensitive) or response (striatum-sensitive) strategies offer effective solutions. Muscimol treatment increased the use of the response strategy in a dose-dependent manner without influencing learning speed, indicating that muscimol modulated strategy and not learning ability. Furthermore, the muscimol-related shift to response strategies varied across the estrous cycle. The results indicate that increasing inhibition in the hippocampus biases rats away from hippocampus-sensitive place learning strategies and toward hippocampus-insensitive response learning strategies without a learning deficit. Furthermore, rats at proestrus demonstrated the most dramatic shift in learning strategy following muscimol treatment compared with control conditions, while rats at estrus demonstrated the most complete bias toward response strategies. The enhanced use of hippocampus-sensitive strategies at proestrus likely results from reduced hippocampal inhibition.",1
"McElroy, Molly W, Korol, Donna L",2
A latent consolidation phase in auditory identification learning: time in the awake state is sufficient.,0
"Large gains in performance, evolving hours after practice has terminated, were reported in a number of visual and some motor learning tasks, as well as recently in an auditory nonverbal discrimination task. It was proposed that these gains reflect a latent phase of experience-triggered memory consolidation in human skill learning. It is not clear, however, whether and when delayed gains in performance evolve following training in an auditory verbal identification task. Here we show that normal-hearing young adults trained to identify consonant-vowel stimuli in increasing levels of background noise showed significant, robust, delayed gains in performance that became effective not earlier than 4 h post-training, with most participants improving at more than 6 h post-training. These gains were retained for over 6 mo. Moreover, although it has been recently argued that time including sleep, rather than time per se, is necessary for the evolution of delayed gains in human perceptual learning, our results show that 12 h post-training in the waking state were as effective as 12 h, including no less than 6 h night's sleep. Altogether, the results indicate, for the first time, the existence of a latent, hours-long, consolidation phase in a human auditory verbal learning task, which occurs even during the awake state.",1
"Roth, Daphne Ari-Even, Kishon-Rabin, Liat, Hildesheimer, Minka, Karni, Avi",2
Extinction and renewal of Pavlovian modulation in human sequential Feature Positive discrimination learning.,0
"Using a conditioned suppression task, we investigated extinction and renewal of Pavlovian modulation in human sequential Feature Positive (FP) discrimination learning. In Experiment 1, in context a participants were first trained on two FP discriminations, X-->A+/A- and Y-->B+/B-. Extinction treatment was administered in the acquisition context a (aaa group) or in a new context b (aba group), and comprised X-->A- extinction and Y- control trials. Discriminative X-->A/A responding was lost in both groups when tested in the extinction context, but partially recovered in the aba and not in the aaa group when tested in the acquisition context, suggesting extinction and renewal of extinguished modulation. The same was observed for the Y-->B/B control pair, however, questioning whether the loss of discriminative X-->A/A responding represented genuine extinction of modulation. In Experiment 2, including only aba groups, participants were trained in context a on two FP discriminations, X-->A+/A- and Y-->B+/B-, after which the group ""Extinction"" was exposed to X-->A- extinction trials in context b, whereas the group ""Control"" was exposed to X- control trials; concurrently, both groups received further Y-->B+/B- training. In the group Control, differential Y-->B/B and X-->A/A responding were acquired and maintained throughout the experiment. In the group Extinction, while Y-->B/B responding was also maintained throughout, differential X-->A/A responding disappeared because of X-->A- extinction treatment when tested in the extinction context b, but partially reappeared when tested in the acquisition context a. This evidences aba-renewal of extinguished modulation.",1
"Baeyens, Frank, Vansteenwegen, Debora, Beckers, Tom, Hermans, Dirk, Kerkhof, Ineke, De Ceulaer, Annick",2
A simple neural network model of the hippocampus suggesting its pathfinding role in episodic memory retrieval.,0
"The goal of this work is to extend the theoretical understanding of the relationship between hippocampal spatial and memory functions to the level of neurophysiological mechanisms underlying spatial navigation and episodic memory retrieval. The proposed unifying theory describes both phenomena within a unique framework, as based on one and the same pathfinding function of the hippocampus. We propose a mechanism of reconstruction of the context of experience involving a search for a nearly shortest path in the space of remembered contexts. To analyze this concept in detail, we define a simple connectionist model consistent with available rodent and human neurophysiological data. Numerical study of the model begins with the spatial domain as a simple analogy for more complex phenomena. It is demonstrated how a nearly shortest path is quickly found in a familiar environment. We prove numerically that associative learning during sharp waves can account for the necessary properties of hippocampal place cells. Computational study of the model is extended to other cognitive paradigms, with the main focus on episodic memory retrieval. We show that the ability to find a correct path may be vital for successful retrieval. The model robustly exhibits the pathfinding capacity within a wide range of several factors, including its memory load (up to 30,000 abstract contexts), the number of episodes that become associated with potential target contexts, and the level of dynamical noise. We offer several testable critical predictions in both spatial and memory domains to validate the theory. Our results suggest that (1) the pathfinding function of the hippocampus, in addition to its associative and memory indexing functions, may be vital for retrieval of certain episodic memories, and (2) the hippocampal spatial navigation function could be a precursor of its memory function.",1
"Samsonovich, Alexei V, Ascoli, Giorgio A",2
HIV-1 resistance conferred by siRNA cosuppression of CXCR4 and CCR5 coreceptors by a bispecific lentiviral vector.,0
"BACKGROUND: RNA interference (RNAi) mediated by small interfering RNAs (siRNAs) has proved to be a highly effective gene silencing mechanism with great potential for HIV/AIDS gene therapy. Previous work with siRNAs against cellular coreceptors CXCR4 and CCR5 had shown that down regulation of these surface molecules could prevent HIV-1 entry and confer viral resistance. Since monospecific siRNAs targeting individual coreceptors are inadequate in protecting against both T cell tropic (X4) and monocyte tropic (R5) viral strains simultaneously, bispecific constructs with dual specificity are required. For effective long range therapy, the bispecific constructs need to be stably transduced into HIV-1 target cells via integrating viral vectors. RESULTS: To achieve this goal, lentiviral vectors incorporating both CXCR4 and CCR5 siRNAs of short hairpin design were constructed. The CXCR4 siRNA was driven by a U6 promoter whereas the CCR5 siRNA was driven by an H1 promoter. A CMV promoter driven EGFP reporter gene is also incorporated in the bispecific construct. High efficiency transduction into coreceptor expressing Magi and Ghost cell lines with a concomitant down regulation of respective coreceptors was achieved with lentiviral vectors. When the siRNA expressing transduced cells were challenged with X4 and R5 tropic HIV-1, they demonstrated marked viral resistance. HIV-1 resistance was also observed in bispecific lentiviral vector transduced primary PBMCs. CONCLUSIONS: Both CXCR4 and CCR5 coreceptors could be simultaneously targeted for down regulation by a single combinatorial lentiviral vector incorporating respective anti-coreceptor siRNAs. Stable down regulation of both the coreceptors protects cells against infection by both X4 and R5 tropic HIV-1. Stable down regulation of cellular molecules that aid in HIV-1 infection will be an effective strategy for long range HIV gene therapy.",1
"Anderson, Joseph, Akkina, Ramesh",2
What does the marriage of Open Access with online publication bring?,0
"Open Access online publishing is the trend of the future for unrestricted rapid and international dissemination of knowledge. Several journals are published on acquired immune deficiency syndrome (AIDS) research, but none of them appear to be Open Access. To eliminate or to abate the scourge of AIDS, it is important that the knowledge acquired through research be disseminated as soon as possible. The Open Access journal, AIDS Research and Therapy, is intended to fill this knowledge gap by online publication of basic, preclinical, and clinical research articles.",1
"Gupta, Kailash C",2
Lentiviral transduction of Tar Decoy and CCR5 ribozyme into CD34+ progenitor cells and derivation of HIV-1 resistant T cells and macrophages.,0
"BACKGROUND: RNA based antiviral approaches against HIV-1 are among the most promising for long-term gene therapy. These include ribozymes, aptamers (decoys), and small interfering RNAs (siRNAs). Lentiviral vectors are ideal for transduction of such inhibitory RNAs into hematopoietic stem cells due to their ability to transduce non-dividing cells and their relative refractiveness to gene silencing. The objective of this study is to introduce an HIV-1 Tar aptamer either alone or in combination with an anti-CCR5 ribozyme into CD34+ hematopoietic progenitor cells via an HIV-based lentiviral vector to derive viral resistant progeny T cells and macrophages. RESULTS: High efficiency and sustained gene transfer into CD34+ cells were achieved with lentiviral vector constructs harboring either Tar decoy or Tar decoy in combination with CCR5 ribozyme. Cells transduced with these constructs differentiated normally into T-lymphocytes in vivo in thy/liv grafts of SCID-hu mice, and into macrophages in vitro in the presence of appropriate growth factors. When challenged in vitro, the differentiated T lymphocytes and macrophages showed marked resistance against HIV-1 infection. CONCLUSIONS: Viral resistant transgenic T cells and macrophages that express HIV-1 Tar aptamer either alone or in combination with an anti-CCR5 ribozyme could be obtained by lentiviral gene transduction of CD34+ progenitor cells. These results showed for the first time that expression of these anti-HIV-1 transgenes in combination do not interfere with normal thymopoiesis and thus have set the stage for their application in stem cell based gene therapy for HIV/AIDS.",1
"Banerjea, Akhil, Li, Ming-Jie, Remling, Leila, Rossi, John, Akkina, Ramesh",2
The Journal of Inflammation.,0
"Welcome to the Journal of Inflammation, the first open-access, peer-reviewed, online journal to focus on all aspects of the study of inflammation and inflammatory conditions. While research into inflammation has resulted in great progress in the latter half of the 20th century, the rate of progress is rapidly accelerating. Thus there is a need for a vehicle through which this very diverse research can be made readily available to the scientific community. The Journal of Inflammation, a peer reviewed journal, provides the ideal vehicle for such rapid dissemination of information. The Journal of Inflammation covers the full range of underlying cellular and molecular mechanisms involved, not only in the production of the inflammatory responses but, more importantly in clinical terms, in the healing process as well. This includes molecular, cellular, animal and clinical studies related to the study of inflammatory conditions and responses, and all related aspects of pharmacology, such as anti-inflammatory drug development, trials and therapeutic developments, etc. All articles published in the Journal of Inflammation are immediately listed in PubMed, and access to published articles is universal and free through the internet.",1
"Punchard, Neville A, Whelan, Cliff J, Adcock, Ian",2
The role of mast cells and fibre type in ischaemia reperfusion injury of murine skeletal muscles.,0
"BACKGROUND: Ischaemia reperfusion (IR) injury of skeletal muscle, is a significant cause of morbidity following trauma and surgical procedures, in which muscle fibre types exhibit different susceptibilities. The relative degree of mast cell mediated injury, within different muscle types, is not known. METHODS: In this study we compared susceptibility of the fast-twitch, extensor digitorum longus (EDL), mixed fast/slow-twitch gastrocnemius and the predominately slow-twitch soleus, muscles to ischemia reperfusion (IR) injury in four groups of mice that harbour different mast cell densities; C57/DBA mast cell depleted (Wf/Wf), their heterozygous (Wf/+) and normal littermates (+/+) and control C57BL/6 mice. We determined whether susceptibility to IR injury is associated with mast cell content and/or fibre type and/or mouse strain. In experimental groups, the hind limbs of mice were subjected to 70 minutes warm tourniquet ischemia, followed by 24 h reperfusion, and the muscle viability was assessed on fresh whole-mount slices by the nitroblue tetrazolium (NBT) histochemical assay. RESULTS: Viability was remarkably higher in the Wf/Wf strain irrespective of muscle type. With respect to muscle type, the predominately slow-twitch soleus muscle was significantly more resistant to IR injury than gastrocnemius and the EDL muscles in all groups. Mast cell density was inversely correlated to muscle viability in all types of muscle. CONCLUSION: These results show that in skeletal muscle, IR injury is dependent upon both the presence of mast cells and on fibre type and suggest that a combination of preventative therapies may need to be implemented to optimally protect muscles from IR injury.",1
"Bortolotto, Susan K, Morrison, Wayne A, Messina, Aurora",2
"Cancer, inflammation and the AT1 and AT2 receptors.",0
"The critical role of inappropriate inflammation is becoming accepted in many diseases that affect man, including cardiovascular diseases, inflammatory and autoimmune disorders, neurodegenerative conditions, infection and cancer.This review proposes that cancer up-regulates the angiotensin II type 1 (AT1) receptor through systemic oxidative stress and hypoxia mechanisms, thereby triggering chronic inflammatory processes to remodel surrounding tissue and subdue the immune system. Based on current literature and clinical studies on angiotensin receptor inhibitors, the paper concludes that blockade of the AT1 receptor in synergy with cancer vaccines and anti-inflammatory agents should offer a therapy to regress most, if not all, solid tumours.With regard to cancer being a systemic disease, an examination of supporting evidence for a systemic role of AT1 in relationship to inflammation in disease and injury is presented as a logical progression. The evidence suggests that regulation of the mutually antagonistic angiotensin II receptors (AT1 and AT2) is an essential process in the management of inflammation and wound recovery, and that it is an imbalance in the expression of these receptors that leads to disease.In consideration of cancer induced immune suppression, it is further postulated that the inflammation associated with bacterial and viral infections, is also an evolved means of immune suppression by these pathogens and that the damage caused, although incidental, leads to the symptoms of disease and, in some cases, death.It is anticipated that manipulation of the angiotensin system with existing anti-hypertensive drugs could provide a new approach to the treatment of many of the diseases that afflict mankind.",1
"Smith, Gary Robert, Missailidis, Sotiris",2
Suppression of neutrophil accumulation in mice by cutaneous application of geranium essential oil.,0
"BACKGROUND: Previous studies suggested that essential oils suppressed the adherence response of human neutrophils in vitro and that intraperitoneal application of geranium oil suppressed the neutrophil accumulation into peritoneal cavity in vivo. Usually, essential oils are applied through skin in aromatherapy in inflammatory symptoms. The purpose of this study is to assess the effects of cutaneous application of essential oils on the accumulation of neutrophils in inflammatory sites in skin of mice. METHODS: Inflammation with accumulation of inflammatory cells was induced by injection of curdlan, a (1-->3)-beta-D-glucan in skin or peritoneal cavity of mice. Essential oils were applied cutaneously to the mice immediately and 3 hr after intradermal injection of curdlan. The skin with inflammatory lesion was cut off 6 hr after injection of curdlan, and the homogenates were used for myeloperoxidase (MPO: a marker enzyme of neutrophil granule) assay. RESULTS: The MPO activity of the skin lesion induced by curdlan was suppressed dose-dependently by cutaneous application of geranium oil. Other oils such as lavender, eucalyptus and tea tree oils also suppressed the activity, but their activities seemed weaker than geranium. Juniper oil didn't suppress the activity CONCLUSION: Cutaneous application of essential oils, especially geranium oil, can suppress the inflammatory symptoms with neutrophil accumulation and edema.",1
"Maruyama, Naho, Sekimoto, Yuka, Ishibashi, Hiroko, Inouye, Shigeharu, Oshima, Haruyuki, Yamaguchi, Hideyo, Abe, Shigeru",2
"Particle and Fibre Toxicology, a new journal to meet a real need.",0
"This Editorial is to announce Particle and Fibre Toxicology, a new Open Access, peer-reviewed, online journal published by BioMed Central. The field of particle and fibre toxicology has a long and famous history stretching from Agricola and Paracelsus in the 15th and 16th century to the challenges of the 21st century-nanoparticles, nanotubes and particulate matter (PM10) to name just three. Throughout this time there has been no single journal dedicated to the toxicology of particles and fibres and this is finally corrected by the launch of Particle and Fibre Toxicology. The rationale for Particle and Fibre Toxicology rests on this need for a single multi-disciplinary journal that can cover all research relevant to particle and fibre toxicology, from Hygiene studies, through particle generation and characterisation, to animal, cell and human toxicology studies, dosimetry and modelling. The editorial also deals with the philosophy and practicalities of Open Access publishing, the journal's peer-review policy and conflict-of-interest. Particle and Fibre Toxicology is aimed at bringing together multi-disciplinary research findings towards a better understanding of how particles and fibres adversely affect the lungs and the body generally. We hope that the launch of the new journal will aid in the advance of this important discipline to the greater benefit of occupational and public health and invite scientists working in this key discipline to submit their research.",1
"Donaldson, Ken, Borm, Paul",2
Whole genome shotgun sequencing of Brassica oleracea and its application to gene discovery and annotation in Arabidopsis.,0
"Through comparative studies of the model organism Arabidopsis thaliana and its close relative Brassica oleracea, we have identified conserved regions that represent potentially functional sequences overlooked by previous Arabidopsis genome annotation methods. A total of 454,274 whole genome shotgun sequences covering 283 Mb (0.44 x) of the estimated 650 Mb Brassica genome were searched against the Arabidopsis genome, and conserved Arabidopsis genome sequences (CAGSs) were identified. Of these 229,735 conserved regions, 167,357 fell within or intersected existing gene models, while 60,378 were located in previously unannotated regions. After removal of sequences matching known proteins, CAGSs that were close to one another were chained together as potentially comprising portions of the same functional unit. This resulted in 27,347 chains of which 15,686 were sufficiently distant from existing gene annotations to be considered a novel conserved unit. Of 192 conserved regions examined, 58 were found to be expressed in our cDNA populations. Rapid amplification of cDNA ends (RACE) was used to obtain potentially full-length transcripts from these 58 regions. The resulting sequences led to the creation of 21 gene models at 17 new Arabidopsis loci and the addition of splice variants or updates to another 19 gene structures. In addition, CAGSs overlapping already annotated genes in Arabidopsis can provide guidance for manual improvement of existing gene models. Published genome-wide expression data based on whole genome tiling arrays and massively parallel signature sequencing were overlaid on the Brassica-Arabidopsis conserved sequences, and 1399 regions of intersection were identified. Collectively our results and these data sets suggest that several thousand new Arabidopsis genes remain to be identified and annotated.",1
"Ayele, Mulu, Haas, Brian J, Kumar, Nikhil, Wu, Hank, Xiao, Yongli, Van Aken, Susan, Utterback, Teresa R, Wortman, Jennifer R, White, Owen R, Town, Christopher D",2
Chromosome triplication found across the tribe Brassiceae.,0
"We have used an approximately 8.7-Mb BAC contig of Arabidopsis thaliana Chromosome 4 to trace homeologous chromosome regions in 21 species of the family Brassicaceae. Homeologs of this segment could be identified in all tested species. Painting of pachytene chromosomes of Calepina, Conringia, and Sisymbrium species (2n = 14, 16), traditionally placed in tribe Brassiceae, showed one homeologous copy of the Arabidopsis contig, while the remaining taxa of the tribe (2n = 14-30) revealed three, and three Brassica species (2n = 34, 36, and 38) and Erucastrum gallicum (2n = 30) had six copies corresponding to the 8.7-Mb segment. The multiple homeologous copies corresponded structurally to the Arabidopsis segment or were rearranged by inversions and translocations within the diploidized genomes. These chromosome rearrangements accompanied by chromosome fusions/fissions led to the present-day chromosome number variation within the Brassiceae. Phylogenetic relationships based on the chloroplast 5'-trnL (UAA)-trnF(GAA) region and estimated divergence times based on sequence data of the chalcone synthase gene are congruent with comparative painting data and place Calepina, Conringia, and Sisymbrium outside the clade of Brassiceae species with triplicated genomes. Most likely, species containing three or six copy pairs descended from a common hexaploid ancestor with basic genomes similar to that of Arabidopsis. The presumed hexaploidization event occurred after the Arabidopsis-Brassiceae split, between 7.9 and 14.6 Mya.",1
"Lysak, Martin A, Koch, Marcus A, Pecinka, Ales, Schubert, Ingo",2
Ancient haplotypes resulting from extensive molecular rearrangements in the wheat A genome have been maintained in species of three different ploidy levels.,0
"Plant genomes, in particular grass genomes, evolve very rapidly. The closely related A genomes of diploid, tetraploid, and hexaploid wheat are derived from a common ancestor that lived <3 million years ago and represent a good model to study molecular mechanisms involved in such rapid evolution. We have sequenced and compared physical contigs at the Lr10 locus on chromosome 1AS from diploid (211 kb), tetraploid (187 kb), and hexaploid wheat (154 kb). A maximum of 33% of the sequences were conserved between two species. The sequences from diploid and tetraploid wheat shared all of the genes, including Lr10 and RGA2 and define a first haplotype (H1). The 130-kb intergenic region between Lr10 and RGA2 was conserved in size despite its activity as a hot spot for transposon insertion, which resulted in >70% of sequence divergence. The hexaploid wheat sequence lacks both Lr10 and RGA2 genes and defines a second haplotype, H2, which originated from ancient and extensive rearrangements. These rearrangements included insertions of retroelements and transposons deletions, as well as unequal recombination within elements. Gene disruption in haplotype H2 was caused by a deletion and subsequent large inversion. Gene conservation between H1 haplotypes, as well as conservation of rearrangements at the origin of the H2 haplotype at three different ploidy levels indicate that the two haplotypes are ancient and had a stable gene content during evolution, whereas the intergenic regions evolved rapidly. Polyploidization during wheat evolution had no detectable consequences on the structure and evolution of the two haplotypes.",1
"Isidore, Edwige, Scherrer, Beatrice, Chalhoub, Boulos, Feuillet, Catherine, Keller, Beat",2
Novel specificities emerge by stepwise duplication of functional modules.,0
"A functional module can be defined as a spatially or chemically isolated set of functionally associated components that accomplishes a discrete biological process. Modularity is a key attribute of cellular systems, but the mechanisms that underlie the evolution of functional modules are largely unknown. Duplication of modules has been shown to be an efficient mechanism for the generation of functional innovation in the field of artificial intelligence, but has not been studied in biological networks. Therefore, we ask whether module duplication occurs in cellular networks. We developed a generic framework for the analysis of module duplication, and use it in a large-scale analysis of Saccharomyces cerevisiae protein complexes. Protein complexes are well defined, experimentally derived, functional modules. We observe that at least 6%-20% of the protein complexes have strong similarity to other complexes; thus a considerable fraction has evolved by duplication. Our results indicate that many complexes evolved by step-wise partial duplications. We show that duplicated complexes retain the same overall function, but have different binding specificities and regulation, revealing that duplication of these modules is associated with functional specialization.",1
"Pereira-Leal, José B, Teichmann, Sarah A",2
ECgene: genome-based EST clustering and gene modeling for alternative splicing.,0
"With the availability of the human genome map and fast algorithms for sequence alignment, genome-based EST clustering became a viable method for gene modeling. We developed a novel gene-modeling method, ECgene (Gene modeling by EST Clustering), which combines genome-based EST clustering and the transcript assembly procedure in a coherent and consistent fashion. Specifically, ECgene takes alternative splicing events into consideration. The position of splice sites (i.e., exon-intron boundaries) in the genome map is utilized as the critical information in the whole procedure. Sequences that share any splice sites are grouped together to define an EST cluster in a manner similar to that of the genome-based version of the UniGene algorithm. Transcript assembly is achieved using graph theory that represents the exon connectivity in each cluster as a directed acyclic graph (DAG). Distinct paths along exons correspond to possible gene models encompassing all alternative splicing events. EST sequences in each cluster are subclustered further according to the compatibility with gene structure of each splice variant, and they can be regarded as clone evidence for the corresponding isoform. The reliability of each isoform is assessed from the nature of cluster members and from the minimum number of clones required to reconstruct all exons in the transcript.",1
"Kim, Namshin, Shin, Seokmin, Lee, Sanghyuk",2
Closing in on the C. elegans ORFeome by cloning TWINSCAN predictions.,0
"The genome of Caenorhabditis elegans was the first animal genome to be sequenced. Although considerable effort has been devoted to annotating it, the standard WormBase annotation contains thousands of predicted genes for which there is no cDNA or EST evidence. We hypothesized that a more complete experimental annotation could be obtained by creating a more accurate gene-prediction program and then amplifying and sequencing predicted genes. Our approach was to adapt the TWINSCAN gene prediction system to C. elegans and C. briggsae and to improve its splice site and intron-length models. The resulting system has 60% sensitivity and 58% specificity in exact prediction of open reading frames (ORFs), and hence, proteins-the best results we are aware of any multicellular organism. We then attempted to amplify, clone, and sequence 265 TWINSCAN-predicted ORFs that did not overlap WormBase gene annotations. The success rate was 55%, adding 146 genes that were completely absent from WormBase to the ORF clone collection (ORFeome). The same procedure had a 7% success rate on 90 Worm Base ""predicted"" genes that do not overlap TWINSCAN predictions. These results indicate that the accuracy of WormBase could be significantly increased by replacing its partially curated predicted genes with TWINSCAN predictions. The technology described in this study will continue to drive the C. elegans ORFeome toward completion and contribute to the annotation of the three Caenorhabditis species currently being sequenced. The results also suggest that this technology can significantly improve our knowledge of the ""parts list"" for even the best-studied model organisms.",1
"Wei, Chaochun, Lamesch, Philippe, Arumugam, Manimozhiyan, Rosenberg, Jennifer, Hu, Ping, Vidal, Marc, Brent, Michael R",2
Simplified fluorescent multiplex PCR method for evaluation of the T-cell receptor V beta-chain repertoire.,0
Evaluation of the T-cell receptor (TCR) V beta-chain repertoire by PCR-based CDR3 length analysis allows fine resolution of the usage of the TCR V beta repertoire and is a sensitive tool to monitor changes in the T-cell compartment. A multiplex PCR method employing 24 labeled upstream V beta primers instead of the conventionally labeled downstream C beta primer is described.,1
"Fernandes, Sanjit, Chavan, Surendra, Chitnis, Vivek, Kohn, Nina, Pahwa, Savita",2
Real-time reverse transcription-PCR quantitation of substance P receptor (NK-1R) mRNA.,0
"The substance P (SP)-preferring receptor, neurokinin-1 receptor (NK-1R), has an important role in inflammation, immune regulation, and viral infection. We applied a newly developed real-time reverse transcription (RT)-PCR assay to quantify NK-1R mRNA in human neuronal cell line (NT-2N), a human B-cell line (IM9), monocyte-derived macrophages (MDM), peripheral blood lymphocytes (PBL), and human astroglioma cells (U87 MG). The NK-1R real-time RT-PCR assay has a sensitivity of 100 mRNA copies, with a dynamic range of detection between 10(2) and 10(7) copies of NK-1R gene transcripts per reaction. This assay is highly reproducible, with an intraassay coefficient variation of threshold cycle (Ct) of less than 1.9%. The NK-1R real-time RT-PCR is highly sensitive for quantitative determination of NK-1R mRNA in human immune cells (MDM and PBL) that express low levels of NK-1R mRNA. In addition, the assay has the ability to accurately quantitate the dynamic changes in NK-1R mRNA expression in interleukin-1beta-stimulated U87 MG. These data indicate that the NK-1R real-time RT-PCR has potential for a wide application in investigation of NK-1R expression at the mRNA level under physiological and pathological conditions in both the central nervous system and the immune system.",1
"Lai, Jian-Ping, Douglas, Steven D, Wang, Yan-Jian, Ho, Wen-Zhe",2
Assessment by flow cytometry of cytokine production in malnourished children.,0
"Malnutrition in children is associated with an increased risk of infection and death. Multiple abnormalities in the immune response, including cytokine production, in protein energy-malnourished children have been described and could account for the increased severity and frequency of infections. In this study, we used flow cytometry to investigate the effects of malnutrition on the production of cytokines (interleukin-2 [IL-2], gamma interferon [IFN-gamma], IL-4, and IL-10) in CD4+ and CD8+ cells and the activation capability (as indicated by CD69+ and CD25+ cells). CD4+ and CD8+ cells from malnourished children showed increased production of IL-4 and IL-10 cytokines and decreased production of IL-2 and IFN-gamma cytokines compared to that in cells from well-nourished, uninfected and well-nourished, infected children. In addition, malnourished children showed impaired activation capability, since the fluorescence intensity of CD69+ and CD25+ cells was lower than that in cells from well-nourished, uninfected and well-nourished, infected children. These results indicate that malnutrition alters the capacity of CD4+ and CD8+ cells to produce IL-2, IFN-gamma, IL-4, and IL-10 in response to stimulus. We concluded that both cytokine production and activation capacity were impaired in malnourished children. This functional impairment may be involved in the failure to develop a specific immune response and the predisposition to infection in these children.",1
"Rodríguez, Leonor, González, Cristina, Flores, Luis, Jiménez-Zamudio, Luis, Graniel, Jaime, Ortiz, Rocío",2
Identification of the gene encoding a 38-kilodalton immunogenic and protective antigen of Streptococcus suis.,0
"In our continued effort to search for a Streptococcus suis protein(s) that can serve as a vaccine candidate or a diagnostic reagent, we constructed and screened a gene library with a polyclonal antibody raised against the whole-cell protein of S. suis type 2. A clone that reacted with the antibody was identified and characterized. Analysis revealed that the gene encoding the protein is localized within a 2.0-kbp EcoRI DNA fragment. The nucleotide sequence contained an open reading frame that encoded a polypeptide of 445 amino acid residues with a calculated molecular mass of 46.4 kDa. By in vitro protein synthesis and Western blot experiments, the protein exhibited an electrophoretic mobility of approximately 38 kDa. At the amino acid level the deduced primary sequence shared homology with sequences of unknown function from Streptococcus pneumoniae (89%), Streptococcus mutans (86%), Lactococcus lactis (80%), Listeria monocytogenes (74%), and Clostridium perfringens (64%). Except for strains of serotypes 20, 26, 32, and 33, Southern hybridization analysis revealed the presence of the gene in strains of other S. suis serotypes and demonstrated restriction fragment length differences caused by a point mutation in the EcoRI recognition sequence. We confirmed expression of the 38-kDa protein in the hybridization-positive isolates using specific antiserum against the purified protein. The recombinant protein was reactive with serum from pigs experimentally infected with virulent strains of S. suis type 2, suggesting that the protein is immunogenic and may serve as an antigen of diagnostic importance for the detection of most S. suis infections. Pigs immunized with the recombinant 38-kDa protein mounted antibody responses to the protein and were completely protected against challenge with a strain of a homologous serotype, the wild-type virulent strain of S. suis type 2, suggesting that it may be a good candidate for the development of a vaccine that can be used as protection against S. suis infection. Analysis of the cellular fractions of the bacterium by Western blotting revealed that the protein was present in the surface and cell wall extracts. The functional role of the protein with respect to pathogenesis and whether antibodies against the antigen confer protective immunity against diseases caused by strains of other pathogenic S. suis capsular types remains to be determined.",1
"Okwumabua, Ogi, Chinnapapakkagari, Sharmila",2
Rapid competitive enzyme-linked immunosorbent assay for detection of antibodies to peste des petits ruminants virus.,0
"Peste des petits ruminants (PPR) is a contagious viral disease of small ruminants that is of economic importance in Africa, the Middle East, and Asia. We developed a rapid competitive enzyme-linked immunosorbent assay (rapid c-ELISA) for the diagnosis and surveillance of PPR. This assay detects PPR virus (PPRV) antibodies in serum samples by quantifying the amount of monoclonal antibody (MAb) P-3H12 after 30 min of incubation of a serum-MAb conjugate mixture on plates coated with a PPRV recombinant nucleocapsid protein (rPPRV-N). We tested 249 PPRV-positive serum samples and 733 PPRV-negative serum samples from field ruminants. The threshold of percent inhibition (PI) was determined to be <50 on the basis of the mean PI plus 3 standard deviations for sera from PPRV-negative ruminants. The relative specificity and sensitivity of the rapid c-ELISA were 98.5% (722 of 733 serum samples) and 93.4% (234 of 249 serum samples), respectively. The rapid c-ELISA sensitively detected PPRV antibodies in hyperimmune sera (virus neutralization test [VNT] titer, >512), even at dilutions > or = 512 in normal goat serum, and as early as 6 to 13 days postinfection from 12 goats, each of which was infected with one of the four PPRV lineages. Hyperimmune sera from animals experimentally vaccinated with rinderpest virus gave positive results by the rapid c-ELISA when the rinderpest virus VNT titers were >512, although the rapid c-ELISA titers were very low (2 to 16). However, the rapid c-ELISA was negative when the rinderpest virus VNT titer was < or = 128. The rapid c-ELISA developed in the present work provides a short turnaround time and could be a useful tool for the diagnosis of PPR and screening for PPRV in the field.",1
"Choi, Kang-Seuk, Nah, Jin-Ju, Ko, Young-Joon, Kang, Shien-Young, Jo, Nam-In",2
Development and evaluation of a Western blot kit for diagnosis of schistosomiasis.,0
"We evaluated the performance of Western blot (WB) analysis using commercially available antigen strips and compared the results with those of indirect hemagglutination (IHA) and indirect immunofluorescence (IFAT) for the serodiagnosis of human schistosomiasis. The antigen preparation was a crude extract of Schistosoma mansoni. The WB profile characteristics of schistosomiasis were characterized by comparing the results for 58 serum samples from patients with parasitologically proven S. mansoni (n = 12) and S. haematobium (n = 46) infections and 37 individuals with probable cases of schistosomiasis but with only positive serology results. The specificity of WB analysis was assessed by testing 12 serum samples from healthy subjects, 67 serum samples from patients with other proven helminthic and protozoan infections, and 16 serum samples from patients with autoantibodies. Six immunodominant bands (65, 70, 80, 95, 110, and 120 kDa) were revealed with sera from patients with schistosomiasis. The presence of three or more bands in the range 65 to 120 kDa, with the exception of the 100-kDa band, was considered diagnostic for Schistosoma infection and had a specificity of 100% in our series. In patients with proven schistosomiasis, the sensitivity of WB analysis was 84.5%, whereas those of IFAT and IHA were 65.5 and 72.9%, respectively. For serologically proven cases, the sensitivity of WB analysis was 97.3%. The overall sensitivity and specificity for both groups of patients were 89.5 and 100%, respectively, with positive and negative predictive values of 100 and 91.3%, respectively. We conclude that WB analysis is a useful technique for the immunological diagnosis of schistosomiasis.",1
"Sulahian, Annie, Garin, Yves Jean François, Izri, Arezki, Verret, Caroline, Delaunay, Pascal, van Gool, Tom, Derouin, Francis",2
Simultaneous serodetection of 10 highly prevalent mouse infectious pathogens in a single reaction by multiplex analysis.,0
"Under current practices of mouse colony maintenance, sera from mice are analyzed for antibodies against several widespread infectious pathogens by conventional immunoassays, generally enzyme-linked immunosorbent assay (ELISA). To test for multiple agents, these methods consume large volumes of mouse serum and are laborious and time-consuming. More efficient immunoassays, using small amounts of sample, are therefore needed. Accordingly, we have developed a novel multiplex diagnostic system that employs fluorescent microbeads, coated with purified antigens, for simultaneous serodetection of 10 mouse infectious agents. Individually identifiable, fluorescent microbeads were coated with antigens from Sendai virus, mouse hepatitis virus, Theiler's mouse encephalomyelitis virus/GDVII strain, mouse minute virus, mouse cytomegalovirus, respiratory enteric orphan virus (Reo-3 virus), mouse parvovirus, calf rotavirus for epizootic diarrhea virus of infant mice, vaccinia virus for ectromelia virus, and Mycoplasma pulmonis. Standard sera, singly positive for antibodies to individual infectious agents, were generated by inoculation of BALB/cj and C57BL/6j mice. Sera from these experimentally infected mice, as well as sera from naturally infected mice, were analyzed using a mixture of microbeads coated with antigens of the 10 infectious agents listed above. Results demonstrated that the multiplex assay was at least as sensitive and specific as ELISA for serodetection. Importantly, the multiplex assay required only 1 microliter of serum for simultaneous serodetection of the 10 mouse infectious agents in one reaction vessel. Thus, this multiplex microbead assay is a reliable, efficient, and cost-effective diagnostic modality that will impact serosurveillance of mice used in research.",1
"Khan, Imran H, Kendall, Lon V, Ziman, Melanie, Wong, Scott, Mendoza, Sara, Fahey, James, Griffey, Stephen M, Barthold, Stephen W, Luciw, Paul A",2
Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia.,0
"Using the MAP1-B enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of The Gambia to determine the Ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. About half (51.6%) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9% and 100%. The highest seroprevalence was detected in the western part of the country (88.1% in the Western Division and 62.1% in the Lower River Division). Sheep in the two easterly divisions (Central River and Upper River divisions) showed the lowest seroprevalence of 29.3% and 32.4%, respectively, while those in the North Bank Division showed an intermediate prevalence of 40.6%. In goats, less than one-third (30.3%) of 679 animals tested were positive. The highest seroprevalence was detected in goats in the North Bank Division (59%) and Western Division (44.1%). Goats in the Lower River Division showed an intermediate level of 21.9%, whereas the lowest rates were found in the eastern part of the country (4.8% in the Central River Division and 2.3% in the Upper River Division). At nearly all sites, seroprevalence rates were higher in sheep than in goats. The results show a gradient of increasing heartwater risk for susceptible small ruminants from the east to the west of The Gambia. These findings need to be taken into consideration when future livestock-upgrading programs are implemented.",1
"Faburay, Bonto, Munstermann, Susanne, Geysen, Dirk, Bell-Sakyi, Lesley, Ceesay, Ansumana, Bodaan, Christa, Jongejan, Frans",2
Prospective evaluation of a whole-blood test using Mycobacterium tuberculosis-specific antigens ESAT-6 and CFP-10 for diagnosis of active tuberculosis.,0
"A new immunodiagnostic test based on the Mycobacterium tuberculosis-specific antigens CFP-10/ESAT-6(QFT-RD1) has been launched as an aid in the diagnosis of latent tuberculosis (TB) infection (LTBI). The aim of this study was to evaluate this test for the diagnosis of active TB. Eighty-two patients with suspicion of TB and 39 healthy BCG-vaccinated persons were enrolled. Forty-eight had active TB, 25 did not, and 9 were excluded. Sensitivity and specificity of the test for active TB were evaluated in a prospective blinded manner in patients suspected of TB. The sensitivity of the QFT-RD1 was 85% (40/48; confidence interval [CI], 75 to 96), and it was higher than the sensitivity of microscopy, 42% (20/48; CI, 27 to 56; P = 0.001), and culture, 59% (27/46; CI, 44 to 73; P = 0.009). Of patients with extrapulmonary TB, 92% (12/13) were QFT-RD1 positive, whereas only 31% (4/13) were positive by microscopy and 42% (5/12) by culture (P < 0.05), and 87% (13/15) of those who were negative by both microscopy and culture were QFT-RD1 positive. By combining microscopy and culture with the QFT-RD1 test, sensitivity increased to 96% (CI, 90 to 102). Ten of 25 (40%) non-TB patients were QFT-RD1 positive, resulting in a specificity of 60%. However, 80% (8/10) of these had risk-factors for TB, indicating latent infection in this group. In healthy controls, only 3% (1/39) were QFT-RD1 positive. In conclusion, the QFT-RD1 test is sensitive for diagnosis of TB, especially in patients with negative microscopy and culture. The accuracy of the QFT-RD1 test will vary with the prevalence of LTBI. We suggest that the QFT-RD1 test could be a very useful supplementary tool for the diagnosis of TB.",1
"Ravn, Pernille, Munk, Martin E, Andersen, Ase B, Lundgren, Bettina, Lundgren, Jens D, Nielsen, Lars N, Kok-Jensen, Axel, Andersen, Peter, Weldingh, Karin",2
Immunization with recombinant surface antigen P50 of Babesia gibsoni expressed in insect cells induced parasite growth inhibition in dogs.,0
This is a report of a vaccine trial directed against Babesia gibsoni infection in dogs with the use of the recombinant antigen P50. Dogs immunized with P50 showed partial protection manifested as a significantly low level of parasitemia. The results indicated that P50 is a primary vaccine candidate molecule against canine B. gibsoni infection.,1
"Fukumoto, Shinya, Tamaki, Yoh, Shirafuji, Hiroaki, Harakawa, Shinji, Suzuki, Hiroshi, Xuan, Xuenan",2
Retrospective serological investigation of severe acute respiratory syndrome coronavirus antibodies in recruits from mainland China.,0
"Different assays were used to analyze 1,621 serum specimens collected from military recruits from the People's Republic of China in 2002 for severe acute respiratory syndrome (SARS) coronavirus antibodies. The results demonstrated that the subjects either had rarely been exposed to the virus before the 2003 SARS outbreak or had not been exposed but the nucleocapsid protein cross-reacted with other antibodies in humans.",1
"Yu, Sumeng, Qiu, Maofeng, Chen, Zeliang, Ye, Xiaobo, Gao, Yaling, Wei, Aimin, Wang, Xiaoyi, Yang, Ling, Wang, Jin, Wen, Jie, Song, Yajun, Pei, Decui, Dai, Erhei, Guo, Zhaobiao, Cao, Cheng, Wang, Jian, Yang, Ruifu",2
Reference values of CD4 T lymphocytes in human immunodeficiency virus-negative adult Nigerians.,0
"A cross-sectional study that involved secondary analysis of data collected from 681 pregnant women and 183 miners (94 men and 89 women; ratio of men to women, 1:0.95) in Jos, Nigeria, was carried out to determine the reference ranges for CD4(+)-cell counts in healthy HIV-negative adult Nigerians. The main results of interest were CD4(+)-cell counts and odds ratios (ORs) of low CD4(+)-cell counts, defined as below 350 cells per microl. CD4(+)-cell counts were similar in men and nonpregnant women, with a mean (standard deviation) of 828 (203) cells per microl, but pregnant women had a lower value of 771 (250) cells per microl. None of the factors assessed was related to the odds of having a low CD4(+)-cell count among men and nonpregnant women, but age, age of marriage, and alcohol usage were significant predictors in pregnant women. Compared to pregnant women less than 20 years old, older women had significantly lower odds of a low CD4(+)-cell count (ORs were 0.06 for women aged 20 to 29 years and 0.22 for those aged 30 to 39 years). When compared with those pregnant women who were married before 20 years of age, those who married at 20 to 29 years and 30 to 39 years had odds ratios of 6.41 and 9.40, respectively. Previous alcohol use was also associated with low CD4(+)-cell counts (OR, 5.15). The 95% confidence interval for CD4(+)-cell counts in healthy adult Nigerians is 547 to 1,327 cells per microl, and this is the first time this has been determined.",1
"Aina, Olumuyiwa, Dadik, Jelpe, Charurat, Manhattan, Amangaman, Patience, Gurumdi, Silas, Mang, Edwina, Guyit, Ruth, Lar, Ndam, Datong, Pam, Daniyam, Comfort, Kanki, Phyllis, Abimiku, Alash'le",2
Persisting humoral antiviral immunity within the Japanese population after the discontinuation in 1976 of routine smallpox vaccinations.,0
"Concerns have arisen recently about the possible use of smallpox for a bioterrorism attack. Routine smallpox vaccination was discontinued in Japan in 1976; however, it is uncertain exactly how long vaccination-induced immunity lasts. We sought to evaluate the seroprevalence and intensity of anti-smallpox immunity among representatives of the present Japanese population. The subjects included 876 individuals who were born between 1937 and 1982. Vaccinia virus-specific immunoglobulin G (IgG) levels were measured by enzyme-linked immunosorbent assay (ELISA), and 152 of 876 samples were also tested for the presence of neutralizing antibodies. Of the subjects who were born before 1962, between 1962 and 1968, and between 1969 and 1975, 98.6, 98.6, and 66.0%, respectively, still retained the vaccinia virus-specific IgG with ELISA values for optical density at 405 nm (OD(405)) of > or = 0.10. The corresponding figures for retained IgGs with OD405 values of > or = 0.30 were 91.0, 90.3, and 58.2%, respectively. Neutralizing antibodies were also maintained. The sera with OD(405) values of > or = 0.30 showed 89% sensitivity and a 93% positive predictive value for detection of neutralizing antibodies (> or = 4). Thus, approximately 80% of persons born before 1969 and 50% of those born between 1969 and 1975 were also found to have maintained neutralizing antibodies against smallpox. A considerable proportion of the previous vaccinated individuals still retain significant levels of antiviral immunity. This long-lasting immunity may provide some protective benefits in the case of reemergence of smallpox, and the disease may not spread as widely and fatally as generally expected.",1
"Hatakeyama, Shuji, Moriya, Kyoji, Saijo, Masayuki, Morisawa, Yuji, Kurane, Ichiro, Koike, Kazuhiko, Kimura, Satoshi, Morikawa, Shigeru",2
Differential detection of five mouse-infecting helicobacter species by multiplex PCR.,0
"Several species of helicobacter have been isolated from laboratory mice, including H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius, which appear to be the most common. The most widely used published method for molecular detection of these agents is PCR amplification of a conserved region of 16S rRNA, but differential speciation requires restriction enzyme digestion of the amplicons. This study was undertaken to determine PCR conditions that would simultaneously and specifically identify each of the five common species without restriction enzyme analyses. First, we designed novel and specific PCR primers for H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius, using sequences from the heterologous regions of 16S rRNA. Because of comigration of amplified products, we next identified P17, an H. bilis-specific protein; P25, an H. hepaticus-specific protein; and P30, an H. muridarum-specific protein by screening genomic DNA expression libraries of each species. Primers were designed from these three genes, plus newly designed, species-specific 16S rRNA primers for H. rodentium and H. typhlonius that could be utilized for a five-plex PCR. The sizes of the amplicons from H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius were 435, 705, 807, 191, and 122 bp, respectively, allowing simultaneous detection and effective discrimination among species.",1
"Feng, Sunlian, Ku, Karin, Hodzic, Emir, Lorenzana, Edward, Freet, Kim, Barthold, Stephen W",2
Rapid immunofluorescence microscopy for diagnosis of melioidosis.,0
"An immunofluorescent (IF) method that detects Burkholderia pseudomallei in clinical specimens within 10 min was devised. The results of this rapid method and those of an existing IF method were prospectively compared with the culture results for 776 specimens from patients with suspected melioidosis. The sensitivities of both IF tests were 66%, and the specificities were 99.5 and 99.4%, respectively.",1
"Wuthiekanun, Vanaporn, Desakorn, Varunee, Wongsuvan, Gumphol, Amornchai, Premjit, Cheng, Allen C, Maharjan, Bina, Limmathurotsakul, Direk, Chierakul, Wirongrong, White, Nicholas J, Day, Nicholas P J, Peacock, Sharon J",2
Korean red ginseng slows depletion of CD4 T cells in human immunodeficiency virus type 1-infected patients.,0
"We have previously showed that long-term intake of Korean red ginseng (KRG) delayed disease progression in human immunodeficiency virus type 1 (HIV-1)-infected patients. In the present study, to investigate whether this slow progression was affected by KRG intake alone or in combination with HLA factor, we analyzed clinical data in 68 HIV-1-infected patients who lived for more than 5 years without antiretroviral therapy. The average KRG intake over 111.9 +/- 31.3 months was 4,082 +/- 3,928 g, and annual decrease in CD4 T cells was 35.0 +/- 28.7/microl. Data analysis showed that there are significant inverse correlations between the HLA prognostic score (0.29 +/- 1.19) and annual decrease in CD4 T cells (r = -0.347; P < 0.01) as well as between the amount of KRG intake and annual decrease in CD4 T cells (r = -0.379; P < 0.01). In addition, KRG intake significantly slowed the decrease in CD4 T cells even when influence of HLA class I was statistically eliminated (repeated-measure analysis of variance; P < 0.05). We also observed significant correlation between KRG intake and a decrease in serum-soluble CD8 antigen level (r = 0.62; P < 0.001). In conclusion, these data show that KRG intake independently and significantly affected the slow depletion of CD4 T cells irrespective of HLA class I.",1
"Sung, Heungsup, Kang, Sang-Moo, Lee, Moo-Song, Kim, Tai Gyu, Cho, Young-Keol",2
Management of Critically Ill Patients with Severe Acute Respiratory Syndrome (SARS).,0
"Severe acute respiratory syndrome (SARS) is frequently complicated with acute respiratory failure. In this article, we aim to focus on the management of the subgroup of SARS patients who are critically ill. Most SARS patients would require high flow oxygen supplementation, 20-30% required intensive care unit (ICU) or high dependency care, and 13-26% developed acute respiratory distress syndrome (ARDS). In some of these patients, the clinical course can progress relentlessly to septic shock and/or multiple organ dysfunction syndrome (MODS). The management of critically ill SARS patients requires timely institution of pharmacotherapy where applicable and supportive treatment (oxygen therapy, noninvasive and invasive ventilation). Superimposed bacterial and other opportunistic infections are common, especially in those treated with mechanical ventilation. Subcutaneous emphysema, pneumothoraces and pneumomediastinum may arise spontaneously or as a result of positive ventilatory assistance. Older age is a consistently a poor prognostic factor. Appropriate use of personal protection equipment and adherence to infection control measures is mandatory for effective infection control. Much of the knowledge about the clinical aspects of SARS is based on retrospective observational data and randomized-controlled trials are required for confirmation. Physicians and scientists all over the world should collaborate to study this condition which may potentially threaten human existence.",1
"Lau, Arthur Chun-Wing, Yam, Loretta Yin-Chun, So, Loletta Kit-Ying",2
Discriminating between elderly and young using a fractal dimension analysis of centre of pressure.,0
"The aim of this project was to evaluate the use of a new analysis technique, fractal dimension analysis, for quantification of quiet stance centre of pressure (COP). By using a fractal dimension analysis of COP, it might be possible to gain more information about control during quiet stance than traditional analyses have previously allowed. The current project considered a group of young healthy participants and a group of elderly healthy participants to compare traditional measures of COP against a fractal dimension analysis of COP. Results indicated that both types of analyses are able to distinguish between eyes open and eyes closed in the elderly group. However, the fractal dimension analysis more accurately detected differences between the participant groups when standing with their eyes closed. Based on these results it is suggested that fractal dimension analysis is more informative about posture control than traditional measures. It is suggested that a fractal dimension type of analysis can be incorporated into clinical testing to identify patients with pathologies.",1
"Doyle, Tim L A, Dugan, Eric L, Humphries, Brendan, Newton, Robert U",2
Study of the early steps of the Hepatitis B Virus life cycle.,0
"Hepatitis B virus (HBV) is a human pathogen, causing the serious liver disease. Despite considerable advances in the understanding of the natural history of HBV disease, most of the early steps in the virus life cycle remain unclear. Virus attachment to permissive cells, fusion and penetration through cell membranes and subsequent genome release, are largely a mystery. Current knowledge on the early steps of HBV life cycle has mostly come from molecular cloning, expression of individual genes and studies of the infection of duck hepatitis B virus (DHBV) with duck primary duck hepatocytes. However, considering of the difference of the surface protein of HBV and DHBV both in the composition and sequence, the degree to which information from DHBV applies to human HBV attachment and entry may be limited. A major obstacle to the study HBV infection is the lack of a reliable and sensitive in vitro infection system. We have found that the digestion of HBV and woodchuck hepatitis virus (WHBV) by protease V8 led to the infection of HepG2 cell, a cell line generally is refractory for their infection [Lu et al. J Virol. 1996. 70. 2277-2285 . Lu et al. Virus Research. 2001. 73(1): 27-4].. Further studies showed that a serine protease inhibitor Kazal (SPIK) was over expressed in the HepG2 cells. Therefore, it is possible that to silence the over expressed SPIK and thus to reinstate the activity of indispensable cellular proteases can result in the restoration of the susceptibility of HepG2 cells for HBV infection. The establishing a stable cell line for study of the early steps of HBV life cycle by silencing of SPIK is discussed.",1
"Lu, Xuanyong, Block, Timothy",2
"The Syndrome of Frontonasal Dysplasia, Callosal Agenesis, Basal Encephalocele, and Eye Anomalies - Phenotypic and Aetiological Considerations.",0
"We report ten sporadic cases of Brazilian patients with facial midline defects, callosal agenesis, basal encephalocele, and ocular anomalies. This very rare cluster of anomalies has been well reported before. However, only until recently it is recognized as a syndrome belonging to frontonasal dysplasia spectrum. The ten cases confirm a distinct clinical entity and help to define the phenotype more precisely than previously. Up to now etiology remains unknown, although we conjecture that it is due to a mutation in TGIF gene.",1
"Richieri-Costa, Antonio, Guion-Almeida, Maria Leine",2
The primary prevention of birth defects: Multivitamins or folic acid?,0
"Periconceptional use of folic acid alone or in multivitamin supplements is effective for the primary prevention of neural-tube defects. The Hungarian randomized and two-cohort controlled trials showed that periconceptional multivitamin supplementation can reduce the occurrence of some other structural birth defects, i.e. congenital abnormalities. These findings were supported by many, but not all observational studies. Recently there have been two main debated questions. The first one is whether the use of folic acid alone or folic acid-containing multivitamins is better. The second one is connected with the dilemma of whether high dose of folic acid (e.g. 5 mg) might be better than a daily multivitamin with 0.4 - 0.8 mg of folic acid. Comparison of the pooled data of two Hungarian trials using a multivitamin containing 0.8 mg folic acid and the data of the Hungarian Case-Control Surveillance of Congenital Abnormalities using high dose of folic acid seemed to be appropriate to answer these questions. Multivitamins containing 0.4 - 0.8 mg of folic acid were more effective for the reduction of neural-tube defects than high dose of folic acid. Both multivitamins and folic acid can prevent some part of congenital cardiovascular malformations. Only multivitamins were able to reduce the prevalence at birth of obstructive defects of urinary tract, limb deficiencies and congenital pyloric stenosis. However, folic acid was effective in preventing some part of rectal/anal stenosis/atresia, and high dose of folic acid had effect in preventing some orofacial clefts. The findings are consistent that periconceptional multivitamin and folic acid supplementation reduce the overall occurrence of congenital abnormalities in addition to the demonstrated effect on neural-tube defects.",1
"Czeizel, Andrew E",2
Inhibition of calmodulin-dependent phosphodiesterase induces apoptosis in human leukemic cells.,0
"Cytosolic extracts from a human lymphoblastoid B-cell line, RPMI-8392, established from a patient with acute lymphocytic leukemia, contain two major forms of cyclic nucleotide phosphodiesterase (PDE): Ca2+-calmodulin dependent PDE (PDE1) and cAMP-specific PDE (PDE4). In contrast, normal quiescent human peripheral blood lymphocytes (HPBL) are devoid of PDE1 activity [Epstein, P. M., Moraski, S., Jr., and Hachisu, R. (1987) Biochem. J. 243, 533-539]. Using reverse transcription-polymerase chain reaction (RT-PCR), we show that the mRNA encoding the 63-kDa form of PDE1 (PDE1B1) is expressed in RPMI-8392 cells, but not in normal, resting HPBL. This mRNA is, however, induced in HPBL following mitogenic stimulation by phytohemagglutinin (PHA). Also using RT-PCR, the full open reading frame for human PDE1B1 cDNA was cloned from RPMI-8392 cells and it encodes a protein of 536 amino acids with 96% identity to bovine, rat, and mouse species. RT-PCR also identifies the presence of PDE1B1 in other human lymphoblastoid and leukemic cell lines of B- (RPMI-1788, Daudi) and T-(MOLT-4, NA, Jurkat) cell origin. Inhibition of PDE1 or PDE4 activity by selective inhibitors induced RPMI-8392 cells, as well as the other cell lines, to undergo apoptosis. Culture of RPMI-8392 cells with an 18-bp phosphorothioate antisense oligodeoxynucleotide, targeted against the translation initiation region of the RPMI-8392 mRNA, led to a specific reduction in the amount of PDE1B1 mRNA after 1 day, and its disappearance after 2 days, and induced apoptosis in these cells in a sequence specific manner. This suggests that PDEs, particularly PDE1B1, because its expression is selective, may be useful targets for inducing the death of leukemic cells.",1
"Jiang, X, Li, J, Paskind, M, Epstein, P M",2
"Zoidogamy in fossil gymnosperms: The centenary of a concept, with special reference to prepollen of late Paleozoic conifers.",0
"This year is the centenary of the surprising discovery in 1896 of zoidogamy in extant cycadophytes and Ginkgo. But by coincidence, also in the same year, the concept of prepollen was introduced. The morphology of prepollen was considered justification for the probable production of motile antherozoids in extinct gymnosperms. In this paper, the history of the prepollen concept is briefly outlined. It is emphasized that, in addition to well-known examples in pteridosperms and cordaitaleans, a prepollen condition also occurred among late Paleozoic conifers.",1
"Poort, R J, Visscher, H, Dilcher, D L",2
Discovery of an algal mitochondrial carbonic anhydrase: molecular cloning and characterization of a low-CO2-induced polypeptide in Chlamydomonas reinhardtii.,0
"In green unicellular algae, several polypeptides are induced upon exposure to limiting CO2. We report here on the localization and characterization of one of these, a 22-kDa polypeptide in Chlamydomonas reinhardtii. This nuclear-encoded polypeptide is induced in the mitochondria by a lowering of the partial pressure of CO2 in the growth medium from 5% to air CO2 levels. Sequencing of two different cDNA clones coding for the polypeptide identified it as a 20.7-kDa beta-type carbonic anhydrase (CA; carbonate dehydratase, carbonate hydro-lyase, EC 4.2.1.1). The two clones differ in their nucleotide sequences but code for identical proteins, showing that this CA is encoded by at least two genes. Northern blot hybridization reveals that mRNA transcripts are only present in cells transferred to air CO2 levels. A comparison of the deduced amino acid sequence with those of other beta-CAs shows the largest degree of similarity with CA from the cyanobacterium Synechocystis (50% identity and 66% similarity). To our knowledge, this is the first identification and characterization of a mitochondrial CA from a photosynthetic organism.",1
"Eriksson, M, Karlsson, J, Ramazanov, Z, Gardeström, P, Samuelsson, G",2
Use of surface-enhanced laser desorption ionization-time-of-flight to identify heat shock protein 70 isoforms in closely related species of the virilis group of Drosophila.,0
"The 70-kDa heat shock protein (Hsp) family in all Drosophila species includes 2 environmentally inducible family members, Hsp70 and Hsp68. Two-dimensional gel electrophoresis revealed an unusual pattern of heat shock-inducible proteins in the species of the virilis group. Trypsin fingerprinting and microsequencing of tryptic peptides using ProteinChip Array technology identified the major isoelectric variants of Hsp70 family, including Hsp68 isoforms that differ in both molecular mass and isoelectric point from those in Drosophila melanogaster. The peculiar electrophoretic mobility is consistent with the deduced amino acid sequence of corresponding hsp genes from the species of the virilis group.",1
"Zatsepina, Olga G, Karavanov, Alexander A, Garbuz, David G, Shilova, Victoria, Tornatore, Peter, Evgen'ev, Michael B",2
Effects of hypoxia on stress proteins in the piglet heart at birth.,0
"Hypoxia at birth represents a very stressful event that can result in severe lifelong consequences in different tissues, including those of the heart. Heat shock and other associated stress proteins are involved in cellular protection, but their roles are not clearly defined at the time of birth. Newborn piglets were subjected to 5% oxygen and 95% nitrogen for either 1 or 4 hours. They were allowed to recover over periods of 1 to 68 hours. The relative levels of alphaB-crystallin, HspB8, Hsp20, Hsp27, Hsp60, and Hsp70 as well as nitric oxide synthases (NOS) (endothelial NOS, inducible NOS, neuronal NOS) were examined by Western blot analysis. Surprisingly, alphaB-crystallin expression was drastically increased in animals submitted to hypoxia. The hypoxia-associated factor HIFlalpha was also strongly and rapidly overexpressed. Heme oxygenase 1 was also increased. To a lesser extent, neuronal NOS was also increased in the left ventricle of animals submitted to hypoxia. This work clearly shows that the Hsp chaperone alphaB-crystallin is strongly overexpressed in the left ventricle of animals submitted to hypoxia. This observation dissociates the response to low oxygenation of alphaB-crystallin and other stress-associated proteins including Hsp27, and it indicates that heme oxygenase is not alone among HSPs in its oxygen-related gene expression.",1
"Louapre, Pamela, Grongnet, Jean F, Tanguay, Robert M, David, Jean C",2
Factors governing the substrate recognition by GroEL chaperone: a sequence correlation approach.,0
"The chaperonin GroEL binds to a large number of polypeptides, prevents their self-association, and mediates appropriate folding in a GroES and adenosine triphosphate-dependent manner. But how the GroEL molecule actually recognizes the polypeptide and what are the exact GroEL recognition sites in the substrates are still poorly understood. We have examined more than 50 in vivo substrates as well as well-characterized in vitro substrates, for their binding characteristics with GroEL. While addressing the issue, we have been driven by the basic concept that GroES, being the cochaperonin of GroEL, is the best-suited substrate for GroEL, as well as by the fact that polypeptide substrate and GroES occupy the same binding sites on the GroEL apical domain. GroES interacts with GroEL through selective hydrophobic residues present on its mobile loop region, and we have considered the group of residues on the GroES mobile loop as the key element in choosing a substrate for GroEL. Considering the hydrophobic region on the GroES mobile loop as the standard, we have attempted to identify the homologous region on the peptide sequences in the proteins of our interest. Polypeptides have been judged as potential GroEL substrates on the basis of the presence of the GroES mobile loop-like hydrophobic segments in their amino acid sequences. We have observed 1 or more GroES mobile loop-like hydrophobic patches in the peptide sequence of some of the proteins of our interest, and the hydropathy index of most of these patches also seems to be approximately close to that of the standard. It has been proposed that the presence of hydrophobic patches having substantial degree of hydropathy index as compared with the standard segment is a necessary condition for a peptide sequence to be recognized by GroEL molecules. We also observed that the overall hydrophobicity is also close to 30% in these substrates, although this is not the sufficient criterion for a polypeptide to be assigned as a substrate for GroEL. We found that the binding of aconitase, alpha-lactalbumin, and murine dihydrofolate reductase to GroEL falls in line with our present model and have also predicted the exact regions of their binding to GroEL. On the basis of our GroEL substrate prediction, we have presented a model for the binding of apo form of some proteins to GroEL and the eventual formation of the holo form. Our observation also reveals that in most of the cases, the GroES mobile loop-like hydrophobic patch is present in the unstructured region of the protein molecule, specifically in the loop or beta-sheeted region. The outcome of our study would be an essential feature in identifying a potential substrate for GroEL on the basis of the presence of 1 or more GroES mobile loop-like hydrophobic segments in the amino acid sequence of those polypeptides and their location in three-dimensional space.",1
"Chaudhuri, Tapan K, Gupta, Prateek",2
Clonogenicity of human leukemic cells protected from cell-lethal agents by heat shock protein 70.,0
"Pretreatment of human leukemia THP-1 cells with heat shock protein Hsp70 (Hsp70) protected them from the cell-lethal effects of the topoisomerase II inhibitor, lucanthone and from ionizing radiation. Cell viability was scored in clonogenic assays of single cells grown in liquid medium containing 0.5% methyl cellulose. Colonies were observed and rapidly scored after staining with the tetrazolium salt, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. The frequency of abasic sites in the deoxyribonucleic acid (DNA) of THP-1 cells was reduced when these cells were treated with Hsp70. Hsp70 is presumed to have protected the cells by promoting repair of cell DNA, in agreement with previous studies that showed that Hsp70 enhanced base excision repair by purified enzymes. The shoulders of radiation dose-response curves were enhanced by pretreatment of cells with Hsp70 and, importantly, were reduced when cells were transfected with ribonucleic acid designed to silence Hsp70. Hsp70 influenced repair of sublethal damage after radiation.",1
"Bases, Robert",2
Expression of heat shock proteins and heat shock protein messenger ribonucleic acid in human prostate carcinoma in vitro and in tumors in vivo.,0
"Heat shock proteins (HSPs) are thought to play a role in the development of cancer and to modulate tumor response to cytotoxic therapy. In this study, we have examined the expression of hsf and HSP genes in normal human prostate epithelial cells and a range of prostate carcinoma cell lines derived from human tumors. We have observed elevated expressions of HSF1, HSP60, and HSP70 in the aggressively malignant cell lines PC-3, DU-145, and CA-HPV-10. Elevated HSP expression in cancer cell lines appeared to be regulated at the post-messenger ribonucleic acid (mRNA) levels, as indicated by gene chip microarray studies, which indicated little difference in heat shock factor (HSF) or HSP mRNA expression between the normal and malignant prostate cell lines. When we compared the expression patterns of constitutive HSP genes between PC-3 prostate carcinoma cells growing as monolayers in vitro and as tumor xenografts growing in nude mice in vivo, we found a marked reduction in expression of a wide spectrum of the HSPs in PC-3 tumors. This decreased HSP expression pattern in tumors may underlie the increased sensitivity to heat shock of PC-3 tumors. However, the induction by heat shock of HSP genes was not markedly altered by growth in the tumor microenvironment, and HSP40, HSP70, and HSP110 were expressed abundantly after stress in each growth condition. Our experiments indicate therefore that HSF and HSP levels are elevated in the more highly malignant prostate carcinoma cells and also show the dominant nature of the heat shock-induced gene expression, leading to abundant HSP induction in vitro or in vivo.",1
"Tang, Dan, Khaleque, Md Abdul, Jones, Ellen L, Theriault, Jimmy R, Li, Cheng, Wong, Wing Hung, Stevenson, Mary Ann, Calderwood, Stuart K",2
CD95-mediated alteration in Hsp70 levels is dependent on protein stabilization.,0
"Engagement of death receptors induces caspase activation and apoptosis. A recent study reported altered protein expression, including increased Hsp70 levels during CD95-mediated apoptosis. Here, we examined the mechanism underlying increased Hsp70 levels in cells challenged with a monoclonal antibody directed against the CD95 receptor. Levels of Hsp70 were found to increase in a dose-dependent manner, occurring independently of either heat shock factor 1 activation or the accumulation of Hsp70 messenger ribonucleic acid (mRNA), suggesting the involvement of posttranslational modifications. Inhibition of translation and de novo protein synthesis by cycloheximide resulted in Hsp70 protein levels diminishing over time in control cells, whereas its level remained constant during CD95 signaling. In addition, death receptor activation through exposure of cells to tumor necrosis factor-related apoptosis-inducing ligand did not alter Hsp70 levels. These findings demonstrate that receptor-specific signaling through the CD95 increases the stability of Hsp70 protein, rather than mRNA, when compared with control cells. The results describe a novel mechanism of heat shock protein accumulation, where increased protein stability and reduced turnover, is the mechanism by which Hsp70 accumulates in cells during CD95-mediated apoptosis.",1
"Concannon, Caoimhín G, FitzGerald, Una, Holmberg, Carina I, Szegezdi, Eva, Sistonen, Lea, Samali, Afshin",2
Zebrafish Hsp70 is required for embryonic lens formation.,0
"Heat shock proteins (Hsps) were originally identified as proteins expressed after exposure of cells to environmental stress. Several Hsps were subsequently shown to play roles as molecular chaperones in normal intracellular protein folding and targeting events and to be expressed during discrete periods in the development of several embryonic tissues. However, only recently have studies begun to address the specific developmental consequences of inhibiting Hsp expression to determine whether these molecular chaperones are required for specific developmental events. We have previously shown that the heat-inducible zebrafish hsp70 gene is expressed during a distinct temporal window of embryonic lens formation at normal growth temperatures. In addition, a 1.5-kb fragment of the zebrafish hsp70 gene promoter is sufficient to direct expression of a gfp reporter gene to the lens, suggesting that the hsp70 gene is expressed as part of the normal lens development program. Here, we used microinjection of morpholino-modified antisense oligonucleotides (MOs) to reduce Hsp70 levels during zebrafish development and to show that Hsp70 is required for normal lens formation. Hsp70-MO-injected embryos exhibited a small-eye phenotype relative to wild-type and control-injected animals, with the phenotype discernable during the second day of development. Histological and immunological analysis revealed a small, underdeveloped lens. Numerous terminal deoxynucleotidyl transferase-mediated dUTP-fluoroscein nick-end labeling (TUNEL)-positive nuclei appeared in the lens of small-eye embryos after 48 hours postfertilization (hpf), whereas they were no longer apparent in untreated embryos by this age. Lenses transplanted from hsp70-MO-injected embryos into wild-type hosts failed to recover and retained the immature morphology characteristic of the small-eye phenotype, indicating that the lens phenotype is lens autonomous. Our data suggest that the lens defect in hsp70-MO-injected embryos is predominantly at the level of postmitotic lens fiber differentiation, a result supported by the appearance of mature lens organization in these embryos by 5 days postfertilization, once morpholino degradation or dilution has occurred.",1
"Evans, Tyler G, Yamamoto, Yoshiyuki, Jeffery, William R, Krone, Patrick H",2
Expression of mdr49 and mdr65 multidrug resistance genes in larval tissues of Drosophila melanogaster under normal and stress conditions.,0
"In situ expression of 2 multidrug resistance genes, mdr49 and mdr65, of Drosophila melanogaster was examined in wild-type third instar larval tissues under physiological conditions and after heat shock or colchicine feeding. Expression of these 2 genes was also examined in tumorous tissues of lethal (2) giant larvae I(2)gl4 mutant larvae. These 2 mdr genes show similar constitutive expression in different larval tissues under physiological conditions. However, they are induced differentially by endogenous (tumorous growth) and exogenous stresses (colchcine feeding or heat shock): whereas heat shock and colchicine feeding induce mdr49, tumorous condition is accompanied by enhanced expression of mdr49 and mdr65 genes.",1
"Tapadia, Madhu G, Lakhotia, S C",2
"HLA-DR regulation and the influence of GM-CSF on transcription, surface expression and shedding.",0
"Low surface HLA-DR expression is a feature in sepsis. However, the mechanisms that regulate HLA-DR expression have not been elucidated. The current study investigates regulation of HLA-DR gene transcription, post transcriptional events and shedding of surface HLA-DR, as well as the regulation of HLA-DR by GM-CSF and an immunomodulatory cytokine. Plasma and PBMC were collected from septic patients and healthy volunteers. An ELISA was developed to measure soluble HLA. PCR techniques were used to determine HLA-DR mRNA levels, and flow cytometry and fluorescent microscopy were used for measurement of surface expressed and intracellular HLA-DR. Septic patients fulfilling the criteria of the American College of Chest Physicians (ACCP) for sepsis were recruited for the study (n=70). HLA-DR was measured on three consecutive days, days seven and fourteen. Patients were excluded from the study if on immunosuppressive therapy. Results: Higher levels of shed HLA-DR were found in the plasma of septic patients compared to healthy controls. The level of HLA-DR mRNA was significantly lower in septic patients compared to healthy controls, however an increased intracellular HLA-DR expression was observed. When HL-60 cells were treated with GM-CSF, gene transcription, surface expression and shedding of HLA-DR were all up-regulated. These results indicate that the mechanisms involved in the regulation of HLA-DR in sepsis include shedding of HLA-DR from the cell surface and regulation of HLA-DR gene transcription. Post-translational processing of HLA-DR was also seen to be compromised. GM-CSF was shown to regulate HLA-DR at all these levels.",1
"Perry, Sara E, Mostafa, Sobhy M, Wenstone, Richard, Shenkin, Alan, McLaughlin, Paul J",2
Anti-tumorigenic and Pro-apoptotic effects of CKBM on gastric cancer growth in nude mice.,0
"Natural botanical products can be integrated with western medicine to optimize the treatment outcome, increase immune function and minimize the side effects from western drug treatment. CKBM is a combination of herbs and yeasts formulated based on traditional Chinese medicinal principles. Previous study has demonstrated that CKBM is capable of improving immune responsiveness through the induction of cytokine mediators, such as TNF-alpha and IL-6. In this study, we aimed to investigate the effect of this immunomodulatory drug on gastric cancer growth using a human xenograft model. Gastric cancer tissues were implanted subcutaneously into athymic nude mice followed by a 14-day or 28-day of CKBM treatment. Results showed that higher doses of CKBM (0.4 or 0.8 ml/mouse/day) produced a dose-dependent inhibitory effect on gastric tumor growth after 28-day drug treatment. This was associated with a decrease of cellular proliferation by 30% with concomitant increase in apoptosis by 97% in gastric tumor cells when compared with the control group. In contrast, CKBM showed no effect on angiogenesis in gastric tumors. This study demonstrates the anti-tumorigenic action of CKBM on gastric cancer probably via inhibition of cell proliferation and induction of apoptosis, and provides future potential targets of this drug candidate on cancer therapy.",1
"Shin, Vivian Yvonne, So, Wallace Hau-Leung, Liu, Edgar Shiu-Lam, Wu, Ying-Jye, Pang, Shiu-Fun, Cho, Chi-Hin",2
An Increased Risk of Osteoporosis during Acquired Immunodeficiency Syndrome.,0
"Osteoporosis is characterized by decreased bone mineral density and mechanistic imbalances of bone tissue that may result in reduced skeletal strength and an enhanced susceptibility to fractures. Osteoporosis in its most common form affects the elderly (both sexes) and all racial groups of human beings. Multiple environmental risk factors like acquired immune deficiency syndrome (AIDS) are believed to be one of the causes of osteoporosis. Recently a high incidence of osteoporosis has been observed in human immunodeficiency virus (HIV) infected individuals. The etiology of this occurrence in HIV infections is controversial. This problem seems to be more frequent in patients receiving potent antiretroviral therapy. In AIDS, the main suggested risk factors for the development of osteoporosis are use of protease inhibitors, longer duration of HIV infection, lower body weight before antiretroviral therapy, high viral load. Variations in serum parameters like osteocalcin, c-telopeptide, levels of elements like Calcium, Magnesium, Phosphorus, concentration of vitamin-D metabolites, lactate levels, bicarbonate concentrations, amount of alkaline phosphatase are demonstrated in the course of development of osteoporosis. OPG/RANKL/RANK system is final mediator of bone remodeling. Bone mineral density (BMD) test is of added value to assess the risk of osteoporosis in patients infected with AIDS. The biochemical markers also aid in this assessment. Clinical management mostly follows the lines of treatment of osteoporosis and osteopenia.",1
"Annapoorna, N, Rao, G Venkateswara, Reddy, N S, Rambabu, P, Rao, K R S Samabasiva",2
Comparative study of serum Na(+ )and K(+ ) levels in senile cataract patients and normal individuals.,0
"Many factors such as aging, changes in blood electrolytes levels, and possibly family history are involved in senile cataract formation. Changes in serum electrolytes levels can induce changes in aqueous electrolytes levels and effect on lens metabolism and probably cataract formation. In this paper, we study serum level of Na(+ )and K(+) in senile cataract patients and normal individuals. Methods and materials: 155 senile cataract patients scheduled for cataract surgery in eye clinic of Rasoul hospital and 155 normal individuals were selected. Serum Na(+) and K(+) levels were measured by Flame Photometry technique and means compared between two groups by t-test. Results: 1. Mean serum Na(+) level in senile cataract patients and normal individuals was 144.96 +/- 6.04 mEq/lit and 140.88 +/- 2.27 mEq/lit respectively, and there was statistically significant difference (P<0.0001). 2. Mean serum K(+) level in senile cataract patients and normal individuals was 4.20 +/- 0.34 mEq/lit and 4.15 +/- 0.32 mEq/lit respectively, and there was no statistically significant difference. Conclusion: Serum Na(+ )level in senile cataract patients was higher than normal individuals in this study. This result might suggest that diets with high Na(+) content are a risk factor for age-related cataract formation, as high Na(+) content of the diet leads to high level of serum Na(+), which in turn contributes to formation of age-related cataract.",1
"Mirsamadi, Mansour, Nourmohammadi, Issa, Imamian, Manuchehr",2
A review of anatomical and mechanical factors affecting vertebral body integrity.,0
"Background: The aetiology of osteoporotic vertebral fracture is multifactorial and may be conceptualised using a systems framework. Previous studies have established several correlates of vertebral fracture including reduced vertebral cross-sectional area, weakness in back extensor muscles, reduced bone mineral density, increasing age, worsening kyphosis and recent vertebral fracture. Alterations in these physical characteristics may influence biomechanical loads and neuromuscular control of the trunk and contribute to changes in subregional bone mineral density of the vertebral bodies. Methods: This review discusses factors that have received less attention in the literature, which may contribute to the development of vertebral fracture. A literature review was conducted using electronic databases including Medline, Cinahl and ISI Web of Science to examine the potential contribution of trabecular architecture, subregional bone mineral density, vertebral geometry, muscle force, muscle strength, neuromuscular control and intervertebral disc integrity to the aetiology of osteoporotic vertebral fracture. Interpretation: A better understanding of factors such as biomechanical loading and neuromuscular control of the trunk may help to explain the high incidence of subsequent vertebral fracture after sustaining an initial vertebral fracture. Consideration of these issues may be important in the development of prevention and management strategies.",1
"Briggs, Andrew M, Greig, Alison M, Wark, John D, Fazzalari, Nicola L, Bennell, Kim L",2
Elevated plasma homocysteine is positively associated with age independent of C677T mutation of the methylenetetrahydrofolate reductase gene in selected Egyptian subjects.,0
"This study aimed to evaluate the plasma homocysteine (tHcy) and folate levels as well as the methylenetetrahydrofolate reductase (MTHFR) C677T mutation in Egyptian subjects. Fasting total homocysteine (tHcy) and the (MTHFR) C677T mutation were evaluated in 50 healthy young control males (age 35-50 years, Gp1), 50 elderly males age ranged between 50-75 years without any cardiovascular diseases (Gp2) and 50 age matched elderly male patients (Gp3) with myocardial infarction. There was a significant elevation of plasma tHcy in the patients group and Gp2 compared to the young control group (Gp1). The total plasma homocysteine (tHcy) in the control group, Gp2 and the patients group were 17.99 +/- 9.76, 39.9 +/- 20.06 and 43.8 +/- 13.13 mumol/L respectively. The frequency of the TT genotype was 12% in the patient group compared with 8 % in the young healthy controls and elderly subjects (Gp2). The CT genotype constituted 36%, 48% and 44% in the control group, Gp2 and the patients group respectively. There was no significant difference in the occurrence of the TT genotype between the studied groups. Plasma tHcy correlated positively with age, total cholesterol, urea, creatinine, glucose levels and carotid intimal thickness (CIT). Conclusion: The MTHFR mutation does not seem to be associated with either high tHcy or the occurrence of cardiovascular diseases in the studied patients. However, elevated plasma tHcy level positively correlates with age in the studied subjects.",1
"El-Sammak, Mohamed, Kandil, Mona, El-Hifni, Safaa, Hosni, Randa, Ragab, Mahmoud",2
Monte Carlo Commissioning of Low Energy Electron Radiotherapy Beams using NXEGS Software.,0
"This work is a report on the commissioning of low energy electron beams of a medical linear accelerator for Monte Carlo dose calculation using NXEGS software (NXEGS version 1.0.10.0, NX Medical Software, LLC). A unique feature of NXEGS is automated commissioning, a process whereby a combination of analytic and Monte Carlo methods generates beam models from dosimetric data collected in a water phantom. This study uses NXEGS to commission 6, 9, and 12 MeV electron beams of a Varian Clinac 2100C using three applicators with standard inserts. Central axis depth-dose, primary axis and diagonal beam profiles, and output factors are the measurements necessary for commissioning of the code. We present a comparison of measured dose distributions with the distributions generated by NXEGS, using confidence limits on seven measures of error. We find that confidence limits are typically less than 3% or 3 mm, but increase with increasing source to surface distance (SSD) and depth at or beyond R(50). We also investigate the dependence of NXEGS' performance on the size and composition of data used to commission the program, finding a weak dependence on number of dose profiles in the data set, but finding also that commissioning data need be measured at only two SSDs.",1
"Both, Joseph A, Pawlicki, Todd",2
Gene Therapy: The Potential Applicability of Gene Transfer Technology to the Human Germline.,0
"The theoretical possibility of applying gene transfer methodologies to the human germline is explored. Transgenic methods for genetically manipulating embryos may in principle be applied to humans. In particular, microinjection of retroviral vector appears to hold the greatest promise, with transgenic primates already obtained from this approach. Sperm-mediated gene transfer offers potentially the easiest route to the human germline, however the requisite methodology is presently underdeveloped. Nuclear transfer (cloning) offers an alternative approach to germline genetic modification, however there are major health concerns associated with current nuclear transfer methods. It is concluded that human germline gene therapy remains for all practical purposes a future possibility that must await significant and important advances in gene transfer technology.",1
"Smith, Kevin R",2
Tyrosine kinase - Role and significance in Cancer.,0
"Tyrosine kinases are important mediators of the signaling cascade, determining key roles in diverse biological processes like growth, differentiation, metabolism and apoptosis in response to external and internal stimuli. Recent advances have implicated the role of tyrosine kinases in the pathophysiology of cancer. Though their activity is tightly regulated in normal cells, they may acquire transforming functions due to mutation(s), overexpression and autocrine paracrine stimulation, leading to malignancy. Constitutive oncogenic activation in cancer cells can be blocked by selective tyrosine kinase inhibitors and thus considered as a promising approach for innovative genome based therapeutics. The modes of oncogenic activation and the different approaches for tyrosine kinase inhibition, like small molecule inhibitors, monoclonal antibodies, heat shock proteins, immunoconjugates, antisense and peptide drugs are reviewed in light of the important molecules. As angiogenesis is a major event in cancer growth and proliferation, tyrosine kinase inhibitors as a target for anti-angiogenesis can be aptly applied as a new mode of cancer therapy. The review concludes with a discussion on the application of modern techniques and knowledge of the kinome as means to gear up the tyrosine kinase drug discovery process.",1
"Paul, Manash K, Mukhopadhyay, Anup K",2
Chloroplast Biogenesis 49 : Differences among Angiosperms in the Biosynthesis and Accumulation of Monovinyl and Divinyl Protochlorophyllide during Photoperiodic Greening.,0
"Various angiosperms differed in their monovinyl and divinyl protochlorophyllide biosynthetic capabilities during the dark and light phases of photoperiodic growth. Some plant species such as Cucumis sativus L., Brassica juncea (L.) Coss., Brassica kaber (DC.) Wheeler, and Portulaca oleracea L. accumulated mainly divinyl protochlorophyllide at night. Monocotyledonous species such as Avena sativa L., Hordeum vulgare L., Triticum secale L., Zea mays L., and some dicotyledonous species such as Phaseolus vulgaris L., Glycine max (L.) Merr., Chenopodium album L., and Lycopersicon esculentum L. accumulated mainly monovinyl protochlorophyllide at night.Under low light intensities meant to simulate the first 60 to 80 minutes following daybreak divinyl protochlorophyllide appeared to contribute much more to chlorophyll formation than monovinyl protochlorophyllide in species such as Cucumis sativus L. Under the same light conditions, species which accumulated mainly monovinyl protochlorophyllide at night appeared to form chlorophyll preferably via monovinyl protochlorophyllide.THESE RESULTS WERE INTERPRETED IN TERMS OF: (a) a differential contribution of monovinyl and divinyl protochlorophyllide to chlorophyll formation at daybreak in various plant species; and (b) a differential regulation of the monovinyl and divinyl protochlorophyllide biosynthetic routes by light and darkness.",1
"Carey, E E, Rebeiz, C A",2
"Analysis of Guard Cell Viability and Action in Senescing Leaves of Nicotiana glauca (Graham), Tree Tobacco.",0
"In an attempt to determine whether low epidermal conductances to water vapor diffusion of senescing leaves were caused by internal changes in guard cells or by factors external to guard cells, stomatal behavior was examined in intact senescing and nonsenescing leaves of Nicotiana glauca (Graham), tree tobacco, grown in the field or in an environmental chamber. Conductances of senescing leaves were 5 to 10% of the maximum conductances of nonsenescing leaves of the same plant, yet guard cell duplexes isolated from epidermal peels of senescing leaves developed full turgor in the light in solutions containing KCl, and sodium cobaltinitrite staining showed that K(+) accumulated as turgor developed. Ninety-five per cent of the guard cells isolated from senescing leaves concentrated neutral red and excluded trypan blue. Intercellular leaf CO(2) concentrations of senescing and nonsenescing leaves of chamber-grown plants were not significantly different (about 240 microliters per liter), but the potassium contents of adaxial and abaxial epidermes of senescing leaves taken from plants grown in the field were less than half those of nonsenescing leaves. We conclude that guard cells do not undergo the orderly senescence process that characteristically takes place in mesophyll tissue during whole-leaf senescence and that the reduced conductances of senescing leaves are produced by factors external to guard cells.",1
"Ozuna, R, Yera, R, Ortega, K, Tallman, G",2
Relationship between Stress-Induced ABA and Proline Accumulations and ABA-Induced Proline Accumulation in Excised Barley Leaves.,0
"When excised second leaves from 2-week-old barley (Hordeum vulgare var Larker) plants were incubated in a wilted condition, abscisic acid (ABA) levels increased to 0.6 nanomole per gram fresh weight at 4 hours then declined to about 0.3 nanomole per gram fresh weight and remained at that level until rehydrated. Proline levels began to increase at about 4 hours and continued to increase as long as the ABA levels were 0.3 nanomole per gram fresh weight or greater. Upon rehydration, proline levels declined when the ABA levels fell below 0.3 nanomole per gram fresh weight.Proline accumulation was induced in turgid barley leaves by ABA addition. When the amount of ABA added to leaves was varied, it was observed that a level of 0.3 nanomole ABA per gram fresh weight for a period of about 2 hours was required before proline accumulation was induced. However, the rate of proline accumulation was slower in ABA-treated leaves than in wilted leaves at comparable ABA levels. Thus, the threshold level of ABA for proline accumulation appeared to be similar for wilted leaves where ABA increased endogenously and for turgid leaves where ABA was added exogenously. However, the rate of proline accumulation was more dependent on ABA levels in turgid leaves to which ABA was added exogenously than in wilted leaves.Salt-induced proline accumulation was not preceded by increases in ABA levels comparable to those observed in wilted leaves. Levels of less than 0.2 nanomole ABA per gram fresh weight were measured 1 hour after exposure to salt and they declined rapidly to the control level by 3 hours. Proline accumulation commenced at about 9 hours. Thus, ABA accumulation did not appear to be involved in salt-induced proline accumulation.",1
"Stewart, C R, Voetberg, G",2
Effect of calmodulin antagonists on auxin-induced elongation.,0
"Coleoptile segments of oat (Avena sativa var Cayuse) and corn (Zea mays L. var Patriot) were incubated in different concentrations of calmodulin antagonists in the presence and absence of alpha-naphthaleneacetic acid. The calmodulin antgonists (chlorpromazine (CP), trifluoperazine, and fluphenazine) inhibited the auxin-induced elongation at 5 to 50 micromolar concentrations. Chlorpromazine sulfoxide, an analog of chlorpromazine, did not have significant effect on the elongation of oat and corn coleoptiles. A specific inhibitor of calmodulin N-(6-aminohexyl)5-chloro-1-naphthalenesulfonamide hydrochloride (W-7, a naphthalenesulfonamide derivative) inhibited coleoptile elongation, while its inactive analog N-(6-aminohexyl)-1-naphthalenesulfonamide hydrochloride (W-5) was ineffective at similar concentrations. During a 4-hour incubation period, coleoptile segments accumulated significant quantities of (3)H-CP. About 85 to 90% of auxin-induced growth was recovered after 4 hours of preincubation with CP or 12 hours with W-7 and transferring coleoptiles to buffer containing NAA. Leakage of amino acids from coleoptiles increased with increasing concentration of CP, showing a rapid and significant increase above 20 micromolar CP. The amount of amino acids released in the presence of W-7 and W-5 was significantly lower than the amount released in the presence of CP. Both W-5 and W-7 increased amino acid release but only W-7 inhibited auxin-induced growth. Calmodulin activity measured by phosphodiesterase activation did not differ significantly between auxin-treated and control coleoptile segments. These results suggest the possible involvement of calmodulin in auxin-induced coleoptile elongation.",1
"Raghothama, K G, Mizrahi, Y, Poovaiah, B W",2
Starch Branching Enzymes from Maize : Immunological Characterization using Polyclonal and Monoclonal Antibodies.,0
"Spleen cells from mice immunized with starch branching enzymes were fused with cells from the mouse myeloma Sp2/0-AG14 cell line to form hybridomas. Those hybridomas producing antibodies against the branching enzyme were screened by the enzyme-linked immunosorbent assay using purified branching enzyme as the antigen. Three monoclonal cell lines (1A1D7, 1A1C3 and 4D2A9D8) were found to produce antibodies which showed positive enzyme-linked immunosorbent assay reactions with maize branching enzyme I in addition to branching enzymes IIa and IIb. Three other monoclonal cell lines (4D2D10, 4D2F9, and 2A6C12) were also selected which were found to produce antibodies showing positive enzyme-linked immunosorbent assay reactions with branching enzymes IIa and IIb only.Amino acid composition and peptide maps obtained after trypsin or chymotrypsin digestion show that there is no difference between branching enzyme IIa and IIb but they are significantly different from branching enzyme I which, along with immunological data, suggests that only two forms of starch branching enzyme may be present in maize kernels.Immunological cross-reaction was also found between the starch branching enzyme from maize kernels and the glycogen branching enzyme from Escherichia coli using polyclonal antibodies against starch branching enzyme I or IIa and IIb or E. coli glycogen branching enzyme, suggesting some immunological similarities between maize starch branching enzymes and E. coli glycogen branching enzyme.",1
"Singh, B K, Preiss, J",2
A novel method of natural cryoprotection : intracellular glass formation in deeply frozen populus.,0
"Correlating measurements from differential scanning calorimetry, freeze-fracture freeze-etch electron microscopy, and survival of twigs after two-step cooling experiments, we provide strong evidence that winter-hardened Populus balsamifera v. virginiana (Sarg.) resists the stresses of freezing below -28 degrees C by amorphous solidification (glass formation) of most of its intracellular contents during slow cooling (</=5 degrees C per hour). It is shown that other components of the intracellular medium go through glass transitions during slow cooling at about -45 degrees C and below -70 degrees C. This ;three glass' model was then used to predict the results of differential scanning calorimetry, freeze-fracture freeze-etch electron microscopy, and biological experiments. This model is the first definitive explanation for the resistance of a woody plant to liquid N(2) temperatures even if quench cooling (1200 degrees C per minute) begins at temperatures as high as -20 degrees C and warming is very slow (</=5 degrees C per hour). It is also the first time high temperature natural intracellular glass formation has been demonstrated.",1
"Hirsh, A G, Williams, R J, Meryman, H T",2
"Enzymic Properties of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase Purified from Rice Leaves.",0
"The enzymic properties of ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase purified from rice (Oryza sativa L.) leaves were studied. Rice RuBPcarboxylase, activated by preincubation with CO(2) and Mg(2+) like other higher plant carboxylases, had an activation equilibrium constant (K(c)K(Mg)) of 1.90 x 10(5) to 2.41 x 10(5) micromolar(2) (pH 8.2 and 25 degrees C). Kinetic parameters of carboxylation and oxygenation catalyzed by the completely activated enzyme were examined at 25 degrees C and the respective optimal pHs. The K(m)(CO(2)), K(m)(RuBP), and V(max) values for carboxylation were 8 micromolar, 31 micromolar, and 1.79 units milligram(-1), respectively. The K(m)(O(2)), K(m)(RuBP), and V(max) values for oxygenation were 370 micromolar, 29 micromolar, and 0.60 units milligram(-1), respectively.Comparison of rice leaf RuBP carboxylase with other C(3) plant carboxylases showed that it had a relatively high affinity for CO(2) but the lowest catalytic turnover number (V(max)) among the species examined.",1
"Makino, A, Mae, T, Ohira, K",2
Correct targeting of the bean storage protein phaseolin in the seeds of transformed tobacco.,0
"The storage protein phaseolin accumulates during seed development in protein bodies in cotyledons of the common bean Phaseolus vulgaris. Hall et al. (In L Van Vloten-Doting, TC Hall, eds, Molecular Form and Function of the Plant Genome, 1985 Plenum Press, In press) recently reported the expression of a gene coding for phaseolin and the accumulation of phaseolin protein in developing seeds of tobacco plants regenerated from transformed callus cells. The protein did not accumulate in other organs of the plants. Mature seeds from normal and transformed tobacco plants were obtained and the subcellular distribution of phaseolin in the seeds was examined using both light and electron microscopic immunocytochemical methods. Phaseolin was found in six of seven transformed tobacco embryos examined, but was present in only one endosperm of five. When present, phaseolin was located exclusively in the protein bodies of the embryonic and endospermic cells. Furthermore, phaseolin was restricted solely to the amorphous matrix of the protein bodies and was excluded from the globoid and proteinaceous crystalloid components of these organelles. The subcellular location of phaseolin in seeds from transformed tobacco plants is similar to that seen in mature seeds of the common bean indicating that in the transformed cells the protein is targeted to the right subcellular compartment.",1
"Greenwood, J S, Chrispeels, M J",2
Surface properties of right side-out plasma membrane vesicles isolated from barley roots and leaves.,0
"Highly purified plasma membrane vesicles were obtained from roots and leaves of 7-day-old light-grown barley (Hordeum vulgare L. cv Kristina) seedlings by partitioning of crude microsomal fractions in a dextran-polyethylene glycol two-phase system. Sodium dodecylsulfate polyacrylamide gel electrophoresis showed the polypeptide composition of plasma membranes from the two organs to be qualitatively similar, but with different relative amounts of some of the polypeptides. Between 80 and 100% of the K(+),Mg(2+)-ATPase activity was latent indicating that the vesicles were sealed and right side-out. The isoelectric points of the outer surface of root and leaf plasma membranes as determined by cross-partitioning were similar and quite acidic-about pH 3.6. In contrast, the net negative surface charge density at pH 7.0 as measured by 9-aminoacridine fluorescence differed significantly, being -29 mC.m(-2) for the leaf plasma membrane and only -19 mC.m(-2) for the root plasma membrane. As isolated, both types of plasma membrane vesicles had Ca(2+) and Mg(2+) bound to the outer surface as shown by the combined use of chelators and 9-aminoacridine fluorescence; however, the leaf plasma membrane had a relatively higher proportion of Ca(2+) bound (0.57) than did the root plasma membrane (0.45). This difference probably reflects differences in the in vivo conditions as no chelator was present during the isolation procedure. Also Ni(2+) could bind to the root vesicles as indicated by the effect of Ni(2+) on 9-aminoacridine fluorescence, and by the binding of (63)Ni(2+) (44 nanomoles bound per milligram protein) at 100 micromolar NiCl(2).",1
"Körner, L E, Kjellbom, P, Larsson, C, Møller, I M",2
Isolation of Bundle Sheath Cell Chloroplasts from the NADP-ME Type C(4) Plant Zea mays: Capacities for CO(2) Assimilation and Malate Decarboxylation.,0
"Bundle sheath chloroplasts have been isolated from Zea mays leaves by a procedure involving enzymic digestion of mechanically prepared strands of bundle sheath cells followed by gentle breakage and filtration. The resulting crude chloroplast preparation was enriched by Percoll density layer centrifugation to yield intact chloroplasts (about 20 micrograms chlorophyll per 10-gram leaf tissue) with high metabolic activities. Based on activities of marker enzymes in the chloroplast and bundle sheath cell extracts, the chloroplasts were essentially free of contamination by other organelles and cytoplasmic material, and were generally about 70% intact. Chlorophyll a/b ratios were high (about 10). With appropriate substrates these chloroplasts displayed high rates of malate decarboxylation, measured as pyruvate formation, and CO(2) assimilation (maximum rates approximately 5 and 3 micromoles per minute per milligram chlorophyll, respectively). These activities were light dependent, linear for at least 20 minutes at 30 degrees C, and displayed highest rates at pH 8.0. High metabolic rates were dependent on addition of an exogenous source of carbon to the photosynthetic carbon reduction cycle (3-phosphoglycerate or dihydroxyacetone phosphate) and a nucleotide (ATP, ADP, or AMP), as well as aspartate. Generally, neither malate decarboxylation nor CO(2) assimilation occurred substantially in the absence of the other activity indicating a close relationship between these processes. Presumably, NADPH required for the photosynthetic carbon reduction cycle is largely supplied during the decarboxylation of malate by NADP-malic enzyme. The results are discussed in relation to the role of bundle sheath chloroplasts in C(4) photosynthesis by species of the NADP-malic enzyme type.",1
"Jenkins, C L, Boag, S",2
Studies on Conditions for Cell Division and Embryogenesis in Isolated Pollen Culture of Nicotiana rustica.,0
"A method for the induction of a high rate of cell division and embryogenesis of Nicotiana rustica pollen was developed. Binucleate pollen grains were fractionated by Percoll density gradient (35/45%) centrifugation and cultured in 0.4 molar mannitol at 30 degrees C (the first culture). After 3 days in culture pollen was recollected by a second Percoll fractionation (0/30%) and transferred to and cultured in a medium containing the Murashige-Skoog macro-elements, 0.4 molar mannitol, 40 millimolar galactose, 3 millimolar glutamine, and 5 micromolar ABA for 10 days (the second culture). The cell population consisting of about 80% dividing pollen was transferred to a Murashige-Skoog medium containing 0.4 molar mannitol, 3 millimolar glutamine, and no phytohormone (the third culture), where about 40% of dividing pollen developed into embryos or embryogenic calli.",1
"Kyo, M, Harada, H",2
Isolation of serine:glyoxylate aminotransferase from cucumber cotyledons.,0
"Serine:glyoxylate aminotransferase, a marker enzyme for leaf peroxisomes, has been purified to homogeneity from cucumber cotyledons (Cucumis sativus cv Improved Long Green). The isolation procedure involved precipitation with polyethyleneimine, a two-step ammonium sulfate fractionation (35 to 45%), gel filtration on Ultrogel AcA 34, and ion exchange chromatography on diethylaminoethyl-cellulose, first in the presence of pyridoxal-5-phosphate, and then in its absence. The enzyme was purified approximately 690-fold to a final specific activity of 34.4 units per milligram. Electrophoresis of the purified enzyme on sodium dodecyl sulfate-polyacrylamide gels revealed two polypeptide bands with apparent molecular weights of approximately 47,000 and 45,000. Both polypeptides coeluted with enzyme activity under all chromatographic conditions investigated, both were localized to the peroxisome, and both accumulated in cotyledons as enzyme activity increased during development. The two polypeptides appear not to be structurally related, since they showed little immunological cross-reactivity and gave rise to different peptide fragments when subjected to partial proteolytic digestion. Antiserum raised against either the denatured enzyme or the 45,000-dalton polypeptide did not react with any other polypeptides present in a crude cotyledonary homogenate. The purified enzyme also had alanine:glyoxylate aminotransferase activity, but was about twice as active with serine as the amino donor.",1
"Hondred, D, Hunter, J M, Keith, R, Titus, D E, Becker, W M",2
Leaf k interaction with water stress inhibition of nonstomatal-controlled photosynthesis.,0
"The relationship between leaf K(+) concentration, in vitro dehydration, and nonstomatal-controlled photosynthesis was investigated using leaf slices that were vacuum infiltrated with media containing varying sorbitol concentrations. The leaf slices were from plants either supplied with complete or K(+)-deficient medium throughout a 35-day growth period. During this time, leaf K(+) concentration, water potential, osmotic potential, and turgor pressure were monitored. Leaf K(+) concentration averaged 239 micomoles per gram (fresh weight) in control plants, and dropped to 74.3 micromoles per gram (fresh weight) in K(+)-deficient plants. Less negative osmotic potentials and resultant turgor loss in K(+)-deficient plants indicated that the osmotically active pool of cellular K(+) was lower in those plants.The decrease in leaf K(+) concentration enhanced the dehydration inhibition of photosynthesis. For example, increasing sorbitol from 0.33 to 0.5 molar during incubation inhibited photosynthesis in the controls by 14% or less. This same protocol resulted in an inhibition of photosynthesis by as much as 41% in K(+)-deficient tissue. In contrast to the data obtained with leaf slices, dehydration inhibition of isolated chloroplast photosynthesis was not affected by K(+) status of parent plant material. These data are consistent with the hypothesis that one effect of leaf K(+) deficiencies on photosynthetic response to dehydration may be mediated by extra-choloroplastic factors.Ammonium ions, which facilitate stromal alkalinization, reversed the increased sensitivity of K(+)-deficient leaf slice photosynthesis to cell dehydration. However, NH(4) (+) had no effect on photosynthesis of K(+)-deficient leaf slices under nonhypertonic conditions. These data suggest that endogenous extra-chloroplastic K(+) may modulate dehydration inhibition of photosynthesis, possibly by facilitating stromal alkalinization.",1
"Berkowitz, G A, Whalen, C",2
Temperature Dependence of Carbon Isotope Fractionation in CAM Plants.,0
"The carbon isotope fractionation associated with nocturnal malic acid synthesis in Kalanchoë daigremontiana and Bryophyllum tubiflorum was calculated from the isotopic composition of carbon-4 of malic acid, after appropriate corrections. In the lowest temperature treatment (17 degrees C nights, 23 degrees C days), the isotope fractionation for both plants is -4 per thousand (that is, malate is enriched in (13)C relative to the atmosphere). For K. daigremontiana, the isotope fractionation decreases with increasing temperature, becoming approximately 0 per thousand at 27 degrees C/33 degrees C. Detailed analysis of temperature effects on the isotope fractionation indicates that stomatal aperture decreases with increasing temperature and carboxylation capacity increases. For B. tubiflorum, the temperature dependence of the isotope fractionation is smaller and is principally attributed to the normal temperature dependences of the rates of diffusion and carboxylation steps. The small change in the isotopic composition of remaining malic acid in both species which is observed during deacidification indicates that malate release, rather than decarboxylation, is rate limiting in the deacidification process.",1
"Deleens, E, Treichel, I, O'leary, M H",2
"Localization, purification, and characterization of shikimate oxidoreductase-dehydroquinate hydrolyase from stroma of spinach chloroplasts.",0
"The stroma of chloroplasts is probably the sole site of the shikimate pathway enzymes shikimate oxidoreductase/dehydroquinate hydrolyase (SORase/DHQase) in spinach leaves. (a) The chromatographic behavior of the bifunctional protein SORase/DHQase on several separation materials with extracts from stroma compared with leaf extracts showed only one peak of enzymic activity originating from the stroma. (b) Polyacrylamide gel electrophoresis (PAGE) of these extracts followed by specific staining resulted in the same pattern without a band of extraplastidic enzyme. (c) In protoplast fractionation experiments it was shown that SORase/DHQase was present only in the soluble chloroplast protein fraction.An improved purification procedure for SORase/DHQase from stroma of chloroplasts, yield 40%, 1600 times as pure, gave essentially one protein band on sodium dodecyl sulfate-PAGE. Our results demonstrate that both enzyme functions are carried out by a single polypeptide. Nondenaturing PAGE exhibited a pattern of four bands with SORase/DHQase showing that they differ in charge but not in their molecular weight. Molecular weight was determined to be 67 kilodaltons (gel filtration) and 59 kilodaltons (PAGE) for all four forms. It was proven they were not due to artifacts. The four forms show similar kinetic properties, their K(m) and pH optima differing only very slightly. Response to some metabolites is reported.",1
"Fiedler, E, Schultz, G",2
Phosphatidylglycerol synthesis in pea chloroplasts: pathway and localization.,0
"Isolated intact pea chloroplasts synthesized phosphatidylglycerol from either [(14)C]acetate or [(14)C]glycerol 3-phosphate. Both time-course and pulse-chase labeling studies demonstrated a precursor-product relationship between newly synthesized phosphatidic acid and newly synthesized phosphatidylglycerol.The synthesis both of CDP-diacylglycerol from exogenous phosphatidic acid and CTP, and of phosphatidylglycerol from exogenous CDP-diacylglycerol and glycerol 3-phosphate, could be assayed in fractions obtained from disrupted chloroplasts. Moreover, the enzymes catalyzing these reactions were localized in the inner envelope membrane. Exogenous phosphatidic acid was incorporated into phosphatidylglycerol, but only following its incorporation into CDP-diacylglycerol. Finally, radio-active phosphatidic acid synthesized in the envelope membranes from [(14)C]palmitoyl-ACP and 1-oleoyl-glycerol 3-phosphate was sequentially incorporated into labeled CDP-diacylglycerol and phosphatidylglycerol upon the addition of appropriate substrates and cofactors. Thus, we have demonstrated that (a) the synthesis of phosphatidylglycerol in chloroplasts occurs by the pathway: phosphatidic acid --> CDP-diacylglycerol -->--> phosphatidylglycerol, and (b) phosphatidylglycerol synthesis is located in the inner envelope membrane.",1
"Andrews, J, Mudd, J B",2
Proteolytic activity in anther extracts of fertile and cytoplasmic male sterile petunia.,0
"Proteolytic activity is compared in anther extracts from Petunia parodii fertile and cytoplasmic male sterile lines. It is characterized relative to developmental stage of the anthers, effect of variable incubation times, pH of isolation buffers, and degradation of marker proteins. In fertile anthers, proteolytic activity increases at the end of microsporogenesis and peaks early in microgametogenesis. Degradation is most severe in extracts of fertile anthers and in high molecular weight proteins and reaches its maximum within 20 minutes. Degradation of marker proteins is greatest at pH 5.6 to 8.0 in fertile anther extracts and is eliminated under strong acid conditions (pH 2.8 to 4.0) in both fertile and cytoplasmic male sterile anther extracts. Marker proteins degrade more severely in extracts of fertile anthers; however, the order of substrate sensitivity-myosin > phosphorylase b > bovine serum albumin and ovalbumin > beta-galactosidase-is the same in extracts from fertile and cytoplasmic male sterile anthers.",1
"Wu, F S, Murry, L E",2
Reduced phytic Acid content does not have an adverse effect on germination of soybean seeds.,0
"Altering the level of phytic acid phosphorus by nutritional means had no effect on the ability of soybean (Glycine max L. [Merr.], cv ;Williams 79') seeds to germinate under laboratory or greenhouse conditions. Dry matter moved out of the cotyledons at similar rates whether the germinating seeds initially contained low (0.19), medium (0.59), or high (1.00 milligram per seed) phytic acid phosphorus. Growth of roots and shoots from 3 to 9 days after planting was similar for seeds containing low and medium levels of phytic acid phosphorus. The medium level of phytic acid resembles that found in field-grown seed, so it is clear that soybean seeds normally contain a phosphorus reserve far above that needed for germination and early seedling growth.",1
"Raboy, V, Hudson, S J, Dickson, D B",2
Effect of Triacontanol on Chlamydomonas: I. Stimulation of Growth and Photosynthetic CO(2) Assimilation.,0
"Treatment of Chlamydomonas reinhardtii cells, cultured at 5% CO(2), with 1 to 1000 micrograms triacontanol (TRIA) per liter resulted in 21 to 35% increases in cell density, 7 to 31% increases in total chlorophyll, and 20 to 100% increases in photosynthetic CO(2) assimilation. The increase in CO(2) fixation with TRIA treatment occurred before, and was independent of, increases in total chlorophyll or cell number. Chlamydomonas cells responded to a broad range of TRIA concentrations that were at least one order of magnitude above the optimum concentration established for higher plants. The necessity for larger concentrations of TRIA may be due to destabilizing effects of Ca(2+) and K(+) present in the Chlamydomonas growth medium. These ions caused flocculation of the colloidally dispersed TRIA in apparent competition with binding of [(14)C]TRIA to Chlamydomonas cells. Octacosanol inhibited the effect of TRIA on photosynthetic CO(2) assimilation. TRIA treatment did not alter the distribution of (14)C-label among photosynthetic products. The effect of TRIA on photosynthetic CO(2) assimilation increased with time after treatment up to 3 days. Chlamydomonas cells that had been grown at low-CO(2) (air) did not respond to TRIA, and transfer of high-CO(2) (5%) grown cells that had responded to TRIA to a low-CO(2) atmosphere resulted in a loss of the effect of TRIA. The effect of pH on photosynthetic CO(2) assimilation indicated that CO(2) is probably the species of inorganic carbon utilized by control and TRIA-treated Chlamydomonas cells.",1
"Houtz, R L, Ries, S K, Tolbert, N E",2
"Effect of Temperature, Oxygen, and Gibberellic Acid on the Development of Photosensitivity in Oldenlandia corymbosa L. Seeds during Their Incubation in Darkness.",0
"Two successive phases can be distinguished in the development of the responsiveness to light in Oldenlandia corymbosa L. seeds during their incubation in darkness. During phase I, the responsiveness to light increases with time if there is sufficient O(2), and the higher the temperature, the faster the increase. This phase is stimulated by gibberellic acid. During the following phase (II), seeds remain responsive to light at 10 or 20 degrees C, but lose their responsiveness at higher temperature (>/=30 degrees C). This second phase depends on O(2): loss of responsiveness is accelerated at lower O(2) concentration. Phase II is only slightly affected by gibberellic acid. The results are discussed in terms of variation of phytochrome and of a reaction along the transduction chain initiated by phototransformation of this pigment, which is finally expressed in germination.",1
"Corbineau, F, Côme, D",2
The Effect of Sugars on the Binding of [Hg]-p-Chloromercuribenzenesulfonic Acid to Leaf Tissues.,0
"Replacement of mannitol with sucrose decreases the binding of [(203)Hg]-p-chloromercuribenzenesulphonic acid (PCMBS) to Vicia faba leaf discs without epidermis. This decrease is optimal for 20 minutes on incubation, is concentration-dependent, and is also found with maltose and raffinose. In parallel experiments, the addition of sucrose, maltose, and raffinose during PCMBS pretreatment was shown to increase subsequent uptake of [U-(14)C]sucrose. In contrast, d- or l-glucose, 3-O-methylglucose, galactose, fructose, palatinose, turanose, or melibiose had no effect either on PCMBS binding or on [(14)C]sucrose uptake. The sucrose-induced decrease of PCMBS binding is retained after a cold and ionic shock. Measurements of specific activities of membrane fractions prepared from tissues incubated in labeled PCMBS show that the decrease concerns the 120,000 gravity pellet, but that very mild procedures must be chosen to prevent redistribution of label in the supernatant. Altogether, the data provide new support to the hypothesis that the active site of the sucrose carrier contains a group sensitive to PCMBS.",1
"M'batchi, B, Pichelin, D, Delrot, S",2
A simple procedure to overcome polyethelene glycol toxicity on whole plants.,0
A procedure is described that can be used to minimize toxic effects of polyethylene glycol (PEG) to plants. The procedure is based on recycling nutrient solutions containing PEG-6000 through two plant cultures. Tomato plants grown in -0.3 megapascals PEG solutions used after two growth cycles exhibited minimal toxic effects. Long-term responses like dry matter production and chlorophyll content as well as short-term responses like CO(2) fixation rates and leaf conductance were severely inhibited by fresh PEG-6000 and only slightly reduced by recycled PEG-6000. Complete osmotic adjustment was obtained with tomatoes grown in recycled but not in fresh PEG solutions.,1
"Plaut, Z, Federman, E",2
High efficiency transformation of cultured tobacco cells.,0
"Tobacco calli were transformed at levels up to 50% by cocultivation of tobacco cultured cells with Agrobacterium tumefaciens harboring the binary transfer-DNA vector, pGA472, containing a kanamycin resistance marker. Transformation frequency was dependent on the physiological state of the tobacco cells, the nature of Agrobacterium strain and, less so, on the expression of the vir genes of the tumor-inducing plasmid. Maximum transformation frequency was obtained with exponentially growing plant cells, suggesting that rapid growth of plant cells is an essental factor for efficient transformation of higher plants.",1
"An, G",2
"Effects of Nitrate Application on Amaranthus powellii Wats. : I. Changes in Photosynthesis, Growth Rates, and Leaf Area.",0
"Physiological effects of different nitrate applications were studied using the C(4) plant, Amaranthus powellii Wats. Plants were grown in a controlled environment chamber and watered daily with nutrient solutions containing 45, 10, 5, or 1 millimolar nitrate. Chloride and sulfate were used to keep the cation and phosphate concentrations constant. Total leaf nitrogen concentration, chlorophyll concentration, specific leaf mass, leaf area, relative growth rate, relative leaf growth rate, unit leaf rate (increase of dry mass per unit leaf area per day), net photosynthetic rate, and incident quantum yield decreased with decreasing nitrate concentration. The per cent decrease of unit leaf rate was similar to the decrease of light-saturated net photosynthetic rate; however, the decrease in relative growth rate was less than that of unit leaf rate because leaf area ratio (leaf area per unit dry mass) increased with decreasing nitrate concentration. Essential mineral concentrations per unit leaf area were about equal among all treatments. Leaf expansion, determined by stomatal density, decreased except for the 1 millimolar treatment which showed relatively more cell expansion but less cell division. Decreased nitrate application was correlated with higher osmotic potentials and lower pressure potentials (determined by pressure-volume curves), whereas leaf water potentials were equal among treatments. Even though total leaf area and shoot mass decreased with decreasing applied nitrate, the increase of the leaf area ratio may be related to selection for the highest possible growth rate.",1
"Hunt, E R, Weber, J A, Gates, D M",2
Role of ethylene in the senescence of isolated hibiscus petals.,0
"Senescence of petals isolated from flowers of Hibiscus rosa-sinensis L. (cv Pink Versicolor) was associated with increased ethylene production. Exposure to ethylene (10 microliters per liter) accelerated the onset of senescence, as indicated by petal in-rolling, and stimulated ethylene production. Senescence was also hastened by basal application of 1-aminocyclopropane-1-carboxylic acid (ACC). Aminooxyacetic acid, an inhibitor of ethylene biosynthesis, effectively inhibited ethylene production by petals and delayed petal in-rolling. In marked contrast to these results with mature petals, immature petals isolated from flowers the day before flower opening did not respond to ethylene in terms of an increase in ethylene production or petal in-rolling. Furthermore, treatment with silver thiosulfate the day before flower opening effectively prevented petal senescence, while silver thiosulfate treatment on the morning of flower opening was ineffective. Application of ACC to both immature and mature petals greatly stimulated ethylene production indicating the presence of an active ethylene-forming enzyme in both tissues. Immature petals contained less free ACC than mature, presenescent petals and appeared to possess a more active system for converting ACC into its conjugated form. Thus, while the nature of the lack of responsiveness of immature petals to ethylene is unknown, ethylene production in hibiscus petals appears to be regulated by the control over ACC availability.",1
"Woodson, W R, Hanchey, S H, Chisholm, D N",2
Properties of the Mg-Protoporphyrin IX Monomethyl Ester (Oxidative) Cyclase System.,0
"Mg-protoporphyrin IX monomethyl ester (oxidative) cyclase, the enzyme system responsible for the formation of the chlorophyll isocyclic ring, exhibits requirements for both essential sulfhydryls and essential disulfides. It is inhibited by N-ethylmaleimide, dithiothreitol, and beta-mercaptoethanol, but not by sodium arsenite. This enzyme system shows some substrate specificity: (a) the 6-side-chain of the macrocycle can either be a methyl propionate ester, or its beta-hydroxy or beta-keto derivatives; (b) the 7-side-chain can either be a propionic acid or a methyl propionate ester; (c) both the 4-vinyl and the 4-ethyl series can serve as substrates, at least at the beta-keto ester level; (d) the activity appears to be lost if the side-chain in the 2-position is reduced from a vinyl to an ethyl.",1
"Wong, Y S, Castelfranco, P A",2
3-Deoxy-d-arabino-Heptulosonate 7-Phosphate Synthase from Carrot Root (Daucus carota) Is a Hysteretic Enzyme.,0
"Roots of carrots (Daucus carota) contain three activities of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase, the enzyme that catalyzes the first step of the shikimate pathway. The three activities, enzymes I, II, and III, are separated by chromatography on phosphocellulose. Enzyme III, purified to electrophoretic homogeneity, has a native molecular weight of 103,000 and consists of two identical subunits of 53,000 daltons each. Double reciprocal plots of reaction velocity versus substrate concentration yield K(m) values of 0.03 and 0.07 millimolar for P-enolpyruvate and erythrose-4-P, respectively. Both products, DAHP and orthophosphate, inhibit the enzyme. Enzyme III is a hysteretic enzyme that is activated by physiological concentrations of l-tryptophan and Mn(2+), both of which also partially eliminate the hysteretic lag. Feedback activation of carrot DAHP synthase by tryptophan is interpreted to be an early regulatory signal for polyphenol biosynthesis. The three carrot DAHP synthase isoenzymes share antigenic determinants.",1
"Suzich, J A, Dean, J F, Herrmann, K M",2
Studies on the photoactivation of the water-oxidizing enzyme : I. Processes limiting photoactivation in hydroxylamine-extracted leaf segments.,0
"In weak yet optimal light intensity, complete photoactivation of the water-oxidizing enzyme in NH(2)OH-extracted wheat (Triticum aestivum, var Oasis) leaf segments could be obtained only after long dark preincubation. Photoactivation was not affected by ethylenediaminetetraacetate or inhibitors of photophosphorylation and protein synthesis, but was partially inhibited by a divalent cation ionophore. Complete photoactivation required ligation of approximately 4 Mn by the water oxidizing enzyme.WITHOUT DARK PREINCUBATION, PHOTOSYSTEM II (PSII) WAS SUSCEPTIBLE TO WEAK LIGHT PHOTOINHIBITION RESULTING IN: (a) 50% maximum decrease in photooxidation of artificial electron donors by PSII: (b) increased times for the variable fluorescence rise (with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea): (c) abolishment of photoactivation: and (d) the imposition of sensitivity to inhibitors of photophosphorylation and 70S but not 80S protein synthesis on subsequent light-dependent recovery from photoinhibition and recovery of O(2) evolution. Decrease in susceptibility to photoinhibition and increase in rates of photoactivation resulting from dark preincubations proved closely correlated. Neither protein synthesis nor increases in abundances of thylakoid Mn(2+) and Ca(2+) were required for escape from photoinhibition. However, photoactivation of the wateroxidizing enzyme in NH(2)OH-extracted Chlamydomonas occurred in absence of dark preincubation and protein synthesis. Results are discussed in the context of disassembly/reassembly/resynthesis of specific PSII polypeptides.",1
"Callahan, F E, Cheniae, G M",2
Enzymic degradation of allantoate in developing soybeans.,0
"A Mn(2+)-dependent enzymic breakdown of allantoate has been detected in crude and partially purified extracts of developing soybeans. The products detected were CO(2), NH(3), glyoxylate, labile glyoxylate derivatives, and low levels of urea. Urea is initially produced at less than 10% the rate of urease-independent CO(2) release indicating that the activity is not allantoate amidinohydrolase (i.e. urea is not directly cleaved off allantoate). The urease-independent CO(2) releasing activity has an apparent K(m) of 1.0 millimolar for allantoate. Ethylenediaminetetraacetate, borate, and acetohydroxamate (all at 10 millimolar) inhibit the enzymic production of NH(3), CO(2), and labile glyoxylate derivatives from allantoate. However, the potent urease inhibitor, phenyl phosphordiamidate does not inhibit CO(2) and NH(3) release indicating that the action of acetohydroxamate is not due to its inhibition of urease. That the allantoatedegrading activity was more than 5-fold greater in seed coats than in embryos is consistent with the data of Rainbird et al. (Plant Physiol 1984 74: 329-334) which indicate that available ureides are metabolized before reaching the embryo. 2-Ethanolthio, 2'ureido, acetic acid (NH(2)COHNCHCO(2)HSCH(2)CH(2)OH), the first allantoate-derived product detected by HPLC analysis, is an addition produced of mercaptoethanol with an unidentified enzymically produced ureido intermediate that is not derived from ureidoglycolate or oxalurate.",1
"Winkler, R G, Polacco, J C, Blevins, D G, Randall, D D",2
Peroxidases and glycosidases in intercellular fluids from noninoculated and rust-affected wheat leaves : isozyme assay on nitrocellulose blots from two-dimensional gels.,0
"Proteins in intercellular washing fluid (IWF) from noninoculated and stem rust-affected wheat leaves were separated by isoelectric focusing and polyacrylamide gel electrophoresis under nondenaturing conditions, transferred to nitrocellulose membranes, and assayed in situ for peroxidase and glycosidase activity.Two infection-related peroxidase isozymes were detected in addition to more than ten that were present only in noninoculated plants. One other peroxidase isozyme was present in much higher concentration in IWF from infected leaves than in IWF from noninoculated leaves.IWF contained many polymorphic glycosidases. A new method is described to localize the glycosidase isozymes accurately on nitrocellulose blots for evaluation of their substrate specificities: each blot was developed with the appropriate p-nitrophenyl glycoside to reveal glycosidase activity, then reprobed for concanavalin A-binding glycoproteins to serve as an internal reference frame for blot-to-blot comparisons. This procedure also provided information on glycosylation of the isozymes.The locations of at least 15 (out of 37) isozymes were coincident with concanavalin A binding, including those of all 10 alpha-d-mannosidases, and of 6 beta-d-xylosidases. On five areas of the blots there was coincidence of beta-d-xylosidase and alpha-l-arabinosidase activity. Three of these areas corresponded to three of the most prominent Coomassie brilliant blue-stainable IWF proteins in gels. Isozymes that could convert p-nitrophenyl-beta-d-glucoside, -beta-d-galactoside, and/or -beta-d-fucoside revealed a complex pattern of partially overlapping substrate specificities: two isozymes utilized both glucose and fucose derivatives, one utilized all three derivatives, and several others converted only one of the three substrates. No enzymes were detected with activity on p-nitrophenyl-beta-d-galactosaminide, -beta-l-fucoside, or -alpha-d-galactoside. No additional glycosidases were detected in IWF from stem rust-affected leaves.",1
"Holden, D W, Rohringer, R",2
Light Activation of NADP-Malate Dehydrogenase in Guard Cell Protoplasts from Vicia faba L.,0
"Light-induced swelling of guard cell protoplasts (GCP) from Vicia faba was accompanied by increases in content of K(+) and malate. DCMU inhibited the increase of K(+) and malate, and consequently swelling.Effect of light on the activity of selected enzymes that take part in malate formation was studied. When isolated GCP were illuminated, NADP-malate dehydrogenase (NADP-MDH) was activated, and the activity reached a maximum within 5 minutes. The enzyme activity underwent 5- to 6-fold increase in the light. Upon turning off the light, the enzyme was inactivated in 5 minutes NAD-MDH and phosphoenolpyruvate carboxylase (PEPC) were not influenced by light. The rapid light activation of NADP-MDH was inhibited by DCMU, suggesting that the enzyme was activated by reductants from the linear electron transport in chloroplasts. An enzyme localization study by differential centrifugation indicates that NADP-MDH is located in the chloroplasts, NAD-MDH in the cytosol and mitochondria, and PEPC in the cytosol. After light activation, the activity of NADP-MDH in guard cells was 10 times that in mesophyll cells on a chlorophyll basis. The physiological significance of light-dependent activation of NADP-MDH in guard cells is discussed in relation to stomatal movement.",1
"Gotow, K, Tanaka, K, Kondo, N, Kobayashi, K, Syōno, K",2
Photosynthetic Responses to Dynamic Light Environments by Hawaiian Trees : Time Course of CO(2) Uptake and Carbon Gain during Sunflecks.,0
"Gas exchange responses to rapid changes in light were studied in a C(3) tree, Claoxylon sandwicense Muell-Arg and a C(4) tree, Euphorbia forbesii Sherff that are native to the understory of a mesic Hawaiian forest. When light was increased to 500 micromoles per meter per second following a 2 hour preexposure at 22 micromoles per meter per second, net CO(2) uptake rates and stomatal conductance gradually increased for over 1 hour in C. sandwicense but reached maximum values within 30 minutes in E. forbesii. Calculation of the intercellular CO(2) pressures indicated that the primary limitation to CO(2) uptake during this induction was nonstomatal in both species. The photosynthetic response to simulated sunflecks (lightflecks) was strongly dependent on the induction state of the leaf. Total CO(2) uptake during a lightfleck was greater and the response was faster after exposure of the leaf to high light than when the leaf had been exposed only to low light for the previous 2 hours. During a series of lightflecks, induction resulted in increased CO(2) uptake in successive lightflecks. Significant postillumination CO(2) fixation was evident and contributed substantially to the total carbon gain, especially for lightflecks of 5 to 20 seconds' duration.",1
"Pearcy, R W, Osteryoung, K, Calkin, H W",2
An investigation into the role of photosynthesis in regulating ATP levels and rates of h efflux in isolated meosphyll cells.,0
"Aerated and stirred 10-ml suspensions of mechanically isolated Asparagus sprengeri Regel mesophyll cells were used for simultaneous measurements of net H(+) efflux and steady-state ATP levels.Initial rates of medium acidification indicated values for H(+) efflux in the light and dark of 0.66 and 0.77 nanomoles H(+)/10(6) cells per minute, respectively. When the medium pH was maintained at 6.5, with a pH-stat apparatus, rates of H(+) efflux remained constant. Darkness or DCMU, however, stimulated H(+) efflux by 100% or more. Darkness increased ATP levels by 33% and a switch from dark to light reduced ATP levels by 31%. In the absence of aeration, illumination prevented the accumulation of respiratory CO(2) and the buffering capacity of the medium was about 50% less than that found in the nonilluminated nonaerated medium. As a result, rates of pH decline were similar even though the dark rate of H(+) efflux was approximately 50% greater.Proposals that photosynthesis stimulates H(+) efflux are based on changes in the rate of pH decline. The present data indicate that photosynthesis inhibits H(+) efflux and that changes in rates of pH decline should not be equated with changes in the rate of H(+) efflux.",1
"Bown, A W, Nicholls, F",2
Biosynthesis of alpha-Amylase in Vigna mungo Cotyledon.,0
"In vitro translation of RNA extracted from Vigna mungo cotyledons showed that alpha-amylase is synthesized as a polypeptide with a molecular mass of 45,000, while cotyledons contain a form of alpha-amylase with a molecular mass of 43,000. To find out whether the 45,000 molecular mass polypeptide is a precursor to the 43,000 found in vivo, the cell free translation systems were supplemented with canine microsomal membrane; when mRNA was translated in the wheat germ system supplemented with canine microsomes, the 45,000 molecular mass form was not processed to a smaller form but the precursor form was partly processed in the membrane-supplemented reticulocyte lysate system. When V. mungo RNA was translated in Xenopus oocyte system, only the smaller form (molecular mass 43,000) was detected. Involvement of contranslational glycosylation in the maturating process of the alpha-amylase was ruled out because there was no effect of tunicamycin, and the polypeptide was resistant to endo-beta-H or endo-beta-D digestion. We interpret these results to mean that the 45,000 molecular mass form is a precursor with a signal peptide or transit sequence, and that the 43,000 molecular mass is the mature form of the protein.",1
"Tomura, H, Koshiba, T",2
"Interspecific Variation in SO(2) Flux : Leaf Surface versus Internal Flux, and Components of Leaf Conductance.",0
"The objective of this study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO(2) air pollution to leaves. Variations in leaf SO(2) and H(2)O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea), Lycopersicon esculentum Mill. flacca (mutant of tomato), Geranium carolinianum L. (wild geranium), and Diplacus aurantiacus (Curtis) Jeps. (a native California shrub). Fluxes were measured using the mass-balance approach during exposure to 4.56 micromoles per cubic meter (0.11 microliters per liter) SO(2) for 2 hours in a controlled environmental chamber. Flux through adaxial and abaxial leaf surfaces with closed stomata ranged from 1.9 to 9.4 nanomoles per square meter per second for SO(2), and 0.3 to 1.3 millimoles per square meter per second for H(2)O vapor. Flux of SO(2) into leaves through stomata ranged from approximately 0 to 8.5 (dark) and 3.8 to 16.0 (light) millimoles per square meter per second. Flux of H(2)O vapor from leaves through stomata ranged from approximately 0 to 0.6 (dark) to 0.4 to 0.9 (light) millimole per square meter per second. Lycopersicon had internal flux rates for both SO(2) and H(2)O vapor over twice as high as for the other species. Stomatal conductance based on H(2)O vapor flux averaged from 0.07 to 0.13 mole per square meter per second among the four species. Internal conductance of SO(2) as calculated from SO(2) flux was from 0.04 mole per square meter per second lower to 0.06 mole per square meter per second higher than stomatal conductance. For Pisum, Geranium, and Diplacus stomatal conductance was the same or slightly higher than internal conductance, indicating that, in general, SO(2) flux could be predicted from stomatal conductance for H(2)O vapor. However, for the Lycopersicon mutant, internal leaf conductance was much higher than stomatal conductance, indicating that factors inside leaves can play a significant role in determining SO(2) flux.",1
"Olszyk, D M, Tingey, D T",2
Interaction of wheat germ ca-dependent protein kinases with calmodulin antagonists and polyamines.,0
"The two soluble Ca(2+)-dependent protein kinases resolved from wheat (Triticum aestivum) embryo (protein kinases I and II) are inhibited by the phenothiazine-derived calmodulin antagonists trifluoperazine fluphenazine, and chlorpromazine. Protein kinases I and II are also inhibited by a variety of other calmodulin antagonists (including calmidazolium, amitriptyline, and iprindole), phosphodiesterase inhibitors (including flufenamic acid and papavarine) and by lanthanides. A number of compounds that inhibit mammalian Ca(2+) - and phospholipid-activated protein kinase (protein kinase C) including quercetin, polymixin B sulfate, and polyamines (as well as phenothiazine derivatives) also inhibit protein kinases I and II. Poly-l-lysine and poly-l-ornithine activate both plant Ca(2+)-dependent protein kinases.",1
"Polya, G M, Micucci, V",2
"A role for fructose 2,6-bisphosphate in regulating carbohydrate metabolism in guard cells.",0
"Fructose 2,6-bisphosphate (Fru2,6P(2)) appears to function as a regulator metabolite in glycolysis and gluconeogenesis in animal tissues, yeast, and the photosynthetic cells of leaves. We have investigated the role of Fru2,6P(2) in guard-cell protoplasts from Vicia faba L. and Pisum sativum L. (Argenteum mutant), and in epidermal strips purified by sonication from all cells except for the guard cells. Guard-cell protoplasts were separated into fractions enriched in cytosol and in chloroplasts by passing them through a nylon net, followed by silicone oil centrifugation. The cytosol contained a pyrophosphate: fructose 6-phosphate phosphotransferase (involved in glycolysis) which was strongly stimulated by Fru2,6P(2). A cytosolic fructose 1,6-bisphosphatase (a catalyst of gluconeogenesis) was inhibited by Fru2,6P(2). There was virtually no fructose 1,6-bisphosphatase activity in guard-cell chloroplasts of V. faba. It is therefore unlikely that the starch formed in these chloroplasts originates from imported triose phosphates or phosphoglycerate.The level of Fru2,6P(2) in guard-cell protoplasts and epidermal strips was about 0.1 to 1 attomole per guard cell in the dark (corresponding to 0.05 to 0.5 nanomole per milligram chlorophyll) and increased three- to tenfold within 15 minutes in the light. Within the same time span, hexose phosphate levels in guard-cell protoplasts declined to approximately one-half, indicating that acceleration of glycolysis involved stimulation of reactions using hexose phosphates. The level of Fru2,6P(2) in guard cells appears to determine the direction in which carbohydrate metabolism proceeds.",1
"Hedrich, R, Raschke, K, Stitt, M",2
Identification and Isolation of Single Cells that Produce Somatic Embryos at a High Frequency in a Carrot Suspension Culture.,0
"A system was established in which single cells differentiated to embryos at a high frequency. Small spherical single cells from a carrot (Daucus carota L. cv ""Kurodagosun"") cell suspension culture were obtained by fractionation through sieving, using nylon screens and then density gradient centrifugation in Percoll solutions. Eighty-five to 90% of these small single cells differentiated to embryos when they were cultured in a medium containing 2,4-dichlorophenoxyacetic acid (5 x 10(-8) molar), zeatin (10(-6) molar), and mannitol (0.2 molar) for 7 days, followed by transfer to a medium containing zeatin (10(-7) molar) but no auxin. This indicates that there are at least two phases in the differentiation of embryos from single cells. The progression of the first phase required exogenous auxin, whereas that of the second phase was inhibited by the same growth regulator. The relationship between the morphology and potency for embryogenesis from single cells was discussed. The system established here is a useful one for investigation of differentiation process from a single cell to a whole plant via embryogenesis, especially in its early stage.",1
"Nomura, K, Komamine, A",2
Photoinhibition and Reactivation of Photosynthesis in the Cyanobacterium Anacystis nidulans.,0
"The susceptibility of photosynthesis to photoinhibition and its recovery were studied on cultures of the cyanobacterium Anacystis nidulans. Oxygen evolution and low temperature fluorescence kinetics were measured. Upon exposure to high light A. nidulans showed a rapid decrease in oxygen evolution followed by a quasi steady state rate of photosynthesis. This quasi steady state rate decreased with increasing photon flux density of the photoinhibitory light. Reactivation of photosynthesis in dim light after the photoinhibitory treatment was rapid: 85 to 95% recovery occurred within 2 hours. In the presence of the translation inhibitor, streptomycin (250 micrograms per milliliter), no reactivation occurred. We also found that the damage increased dramatically if the high light treatment was done with streptomycin added. A transcription inhibitor, rifampicin, did not inhibit the reactivation process. Based on these data we conclude that the photoinhibitory damage observed is the net result of a balance between the photoinhibitory process and the operation of the repairing mechanism(s).",1
"Samuelsson, G, Lönneborg, A, Rosenqvist, E, Gustafsson, P, Oquist, G",2
Role of Ca and EGTA on Stomatal Movements in Commelina communis L.,0
"Ca(2+) (0.1-1.0 millimolar) accelerated dark-induced stomatal closure and reduced stomatal apertures in the light in epidermal peels of Commelina communis L. In contrast, ethyleneglycol-bis-(beta-aminoethyl ether) N,N'tetraacetic acid (EGTA) (2 millimolar), a Ca(2+) chelator, prevented closure in the dark and accelerated opening in the light. EGTA did not promote significant opening in the dark. It is therefore concluded that EGTA does not increase ion uptake into guard cells, but rather prevents ion efflux. Addition of EGTA to incubating solutions with 10 millimolar KCl resulted in steady state apertures of 15.6 micrometers, whereas in the absence of EGTA similar apertures required 55 millimolar KCl and 150 millimolar KCl was needed in the presence of 1 millimolar CaCl(2). The results demonstrate the importance of Ca(2+) in the regulation of stomatal closure and point to a role of Ca(2+) in the regulation of K(+) efflux from stomatal guard cells.",1
"Schwartz, A",2
Photocontrol of Hypocotyl Elongation in Light-Grown Cucumis sativus L. : Responses to Phytochrome Photostationary State and Fluence Rate.,0
"The effects of the calculated photostationary state of phytochrome (phi(c)) and the photon fluence rate on the elongation growth of the hypocotyl of light-grown seedlings of Cucumis sativus L. are examined. Two threshold responses to phi(c) are found at values of 0.06 and 0.43. At phi(c) = 0.06, there is no response at any fluence rate. In the phi(c) range 0.1 to 0.43, elongation growth does not respond to changes in phi(c). Above the second threshold (phi(c) = 0.43), there is a strong response to changes in phi(c). At all values of phi(c) at and above 0.1, there is a response to fluence rate. A linear relationship can be demonstrated between a factor comprised of the logarithm of phytochrome cycling rate (a fluence-rate-dependent process) and phi(c), and the growth response.",1
"Gaba, V, Black, M",2
Factors affecting ice nucleation in plant tissues.,0
"Factors affecting the ice nucleation temperature of plants and plant tissues were examined. The mass of a sample had a marked effect on ice nucleation temperature. Small tissue samples supercooled to -10 degrees C and were not accurate predictors of the nucleation temperature of intact plants in either laboratory or field experiments. This effect was not unique to plant tissues and was observed in autoclaved and control soil samples. Ice nucleation temperatures of bean, corn, cotton, and soybean seedlings were influenced by the length of subzero exposure, presence of ice nucleation active bacteria, and leaf surface wetness. The number of factors influencing ice nucleation temperature suggested that predicting the freezing behavior of plants in the field will be complex.",1
"Ashworth, E N, Davis, G A, Anderson, J A",2
Glycine-Glomus-Rhizobium Symbiosis: II. Antagonistic Effects between Mycorrhizal Colonization and Nodulation.,0
"Soybean (Glycine max [L.] Merr.) plants grown in pot cultures were inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe and Rhizobium japonicum strain 61A118 at planting (G(1)R(1)) or at 20 days (G(20)R(20)), or with one of the endophytes after the other has colonized the host root (G(1)R(20), G(20)R(1)). Nodulated (PR(1)) and VAM (G(1)N) dipartite associations, or nonsymbiotic plants (PN) using nutrient solutions with N, P, or N + P concentrations providing endophyte-equivalent nutrient inputs were used as controls. The delayed tripartite associations received the appropriate N, P, or N + P amendment while one or both endophytes were absent during the first 20 days of growth. Prior inoculation with one endophyte significantly inhibited development of the other. Root hexose sugar concentrations were negatively correlated with VAM colonization (r = -0.89), nodule activity (r = -0.91), and root P content (r = -0.93). Nodule (r = 0.97) and root (r = 0.96) P content correlated positively with VAM colonization. Nodule weight or VAM-fungal biomass were significantly greater in associations grown with only one endophyte. Dry weights of the PN, G(1)N, PR(1), and G(20)R(20) plants were significantly greater than those of tripartite plants inoculated at planting with either or both endophytes. Interendophyte inhibition is attributed to competition for root carbohydrates, and this effect apparently also affects overall plant productivity. The objective of the study was to determine if the timing of endophyte introduction and establishment affected the development of the other symbiotic partners.",1
"Bethlenfalvay, G J, Brown, M S, Stafford, A E",2
Potassium and sodium absorption kinetics in roots of two tomato species : lycopersicon esculentum and lycopersicon cheesmanii.,0
"Excised roots of the tomato species, Lycopersicon esculentum Mill. cv Walter (the commercial species) and of Lycopersicon cheesmanii ssp. minor (Hook.) C.H. Mull. (a wild species from the Galapagos Islands), were used in comparative studies of their absorption of K(+) and Na(+). Uptake of (86)Rb-labeled K(+) and (22)Na-labeled Na(+) by excised roots of ;Walter' and L. cheesmanii varied as a function of genotype and tissue pretreatment with or without K(+). Excised roots of ;Walter' consistently absorbed more (86)Rb-labeled K(+) than those of L. cheesmanii. Absorption of K(+) from solutions ranging from 0.01 to 0.2 millimolar KCl showed saturation kinetics in both K(+)-pretreated and K(+)-depleted roots of ;Walter,' and for K(+)-depleted roots of L. cheesmanii. K(+)-pretreated roots of L. cheesmanii had exceedingly low rates of K(+) uptake with strikingly different, linear kinetics. Pretreatment with K(+) caused a decrease in rates of K(+) uptake in both genotypes. Potassium depleted roots of L. cheesmanii absorbed Na(+) at a greater rate than those of ;Walter,' whereas K(+)-pretreated roots of ;Walter' absorbed Na(+) at a greater rate than those of L. cheesmanii. The results confirm and extend previous conclusions to the effect that closely related genotypes may exhibit widely different responses to the two alkali cations, K(+) and Na(+).",1
"Wrona, A F, Epstein, E",2
Potassium transport in two tomato species : lycopersicon esculentum and lycopersicon cheesmanii.,0
"The commercial tomato, lycopersicon esculentum Mill. cv Walter, and its wild relative, Lycopersicon cheesmanii ssp. minor (Hook.) C.H. Mull., were grown for 30 days under controlled conditions and in solution culture varying in its content of Na(+) and K(+). Subsequently, (86)Rb-labeled K(+) uptake and distribution were studied. From all solutions, ;Walter' consistently absorbed (86)Rb-labeled K(+) at a higher rate in micromoles per gram fresh weight per 30 minutes than L. cheesmanii. L. cheesmanii distributed a greater proportion of the absorbed K(+) from its root to its shoot. When 0.6 millimolar NaNO(3) replaced 0.6 millimolar KNO(3) in the pretreatment solution, intact plants of both genotypes followed a similar pattern as when they were pretreated with K(+) only, but a greater percentage of the absorbed K(+) remained in the roots. Leaf slices of L. cheesmanii plants deprived of K(+) for 6 days showed a greater rate of K(+) uptake than did slices from ;Walter' plants pretreated the same way. Stem slices of L. cheesmanii, however, had a lower uptake rate than did those of ;Walter'. Both leaf and stem slices of ;Walter' plants, pretreated 6 days with 0.6 millimolar NaNO(3) substituting for 0.6 millimolar KNO(3) in their growth medium, had greater rates of (86)Rb-labeled K(+) uptake from 0.5 and 20 millimolar KCl solutions than did slices of L. cheesmanii. These marked differences in patterns of ion uptake and translocation indicate that these genotypes of tomato have evolved different mechanisms to deal with K(+) and Na(+) in their environments.",1
"Wrona, A F, Epstein, E",2
Effect of foliar applications of urea on accelerated senescence of maize induced by ear removal.,0
"Field grown maize (Zea mays L. cv B73 x Mo17) plants, with and without ears, were sprayed with urea solutions to determine whether foliar application of N could prevent or delay the accelerated loss of reduced N from the leaf and leaf senescence induced by ear removal. Urea sprays were applied at 7, 14, and 21 days after anthesis in three separate and equal applications that provided a total of 67 kilograms N per hectare or 1 gram N per plant. Treatments were arranged in a 2 x 2 factorial in a randomized complete block with five replicates. Appropriate plant and leaf samplings and assays were made.In response to spray treatments, net increases of reduced N were detected in the whole shoot and plant parts, especially the stalk of the earless plants and grain of the eared plants. There was no effect of urea spray treatment on the normal loss of N from the leaves or rate of senescence of the eared plants or on the accelerated loss of N from the leaves or rate of senescence induced by ear removal. Grain and stover yields were unaffected by the spray treatment.Apparently the plants were unable to utilize the urea N applied to the vegetation (primarily leaves) after anthesis to enhance or extend the accumulation of dry weight by either eared or earless plants.",1
"Below, F E, Crafts-Brandner, S J, Hageman, R H",2
Auxin regulation of a proton translocating ATPase in pea root plasma membrane vesicles.,0
"Pea root microsomal vesicles have been fractionated on a Dextran step gradient to give three fractions, each of which carries out ATP-dependent proton accumulation as measured by fluorescence quenching of quinacrine. The fraction at the 4/6% Dextran interface is enriched in plasma membrane, as determined by UDPG sterol glucosyltransferase and vanadate-inhibited ATPase. The vanadate-sensitive phosphohydrolase is not specific for ATP, has a K(m) of about 0.23 millimolar for MgATP, is only slightly affected by K(+) or Cl(-) and is insensitive to auxin. Proton transport, on the other hand, is more specific for ATP, enhanced by anions (NO(3) (-) > Cl(-)) and has a K(m) of about 0.7 millimolar. Auxins decrease the K(m) to about 0.35 millimolar, with no significant effect on the V(max), while antiauxins or weak acids have no such effect. It appears that auxin has the ability to alter the efficiency of the ATP-driven proton transport.",1
"Gabathuler, R, Cleland, R E",2
Hydrolysis of Intracellular Proteins in Vacuoles Isolated from Acer pseudoplatanus L. Cells.,0
"Acer pseudoplatanus cell suspension cultures were used to examine the ability of vacuoles isolated from protoplasts to hydrolyze their endogenous proteins. Total cell proteins were labeled by addition of [(3)H]leucine to the culture medium. After preparation of the protoplasts, vacuoles were isolated and were shown to be essentially free from other cellular components. Up to 30% of the [(3)H]leucine-labeled newly synthesized proteins were recovered in the vacuoles. When incubated for 6 hours at 20 degrees C, the vacuoles degraded half of these proteins. The protein breakdown was temperature and pH dependent. Analysis by electrophoresis, in denaturing polyacrylamide gels, revealed that most of the vacuolar proteins were degraded. However, some vacuolar proteins were unaffected during a 6-hour incubation period. The results indicate that vacuoles are able to acquire and degrade intracellular proteins.",1
"Canut, H, Alibert, G, Boudet, A M",2
The senescence of detached leaves of tropaeolum.,0
"The senescence of detached Tropaeolum majus leaves was compared with that described earlier for Avena. Tropaeolum was chosen as being not only a dicot but also as having a nearly circular leaf, thus needing only the smallest minimum of wounding, since wounding delays the loss of chlorophyll and protein in darkness. Tropaeolum resembles Avena in that closing the stomata osmotically or with ABA causes rapid senescence in light. As in Avena also, n-hexanol and alpha,alpha'-dipyridyl delay senescence in darkness but cause ;bleaching' of chlorophyll in light. Unlike Avena, however, kinetin and gibberellic acid, which delay senescence in the dark in both species, do so in Tropaeolum without causing any significant stomatal opening. The senescence of Tropaeolum leaves is actually promoted by fusicoccin, which powerfully delays senescence in Avena, although fusicoccin does cause stomatal opening in darkness in both species. Thus, many of the phenomena of senescence are alike in the monocot and dicot, but there are several significantly different responses to the senescence-modifying reagents. It is concluded that while stomatal closure accelerates senescence in both species, stomatal opening is not directly linked to the prevention of leaf senescence.",1
"Thimann, K V",2
A Ca/H Antiport System Driven by the Proton Electrochemical Gradient of a Tonoplast H-ATPase from Oat Roots.,0
"Two types of ATP-dependent calcium (Ca(2+)) transport systems were detected in sealed microsomal vesicles from oat roots. Approximately 80% of the total Ca(2+) uptake was associated with vesicles of 1.11 grams per cubic centimeter and was insensitive to vanadate or azide, but inhibited by NO(3) (-). The remaining 20% was vanadate-sensitive and mostly associated with the endoplasmic reticulum, as the transport activity comigrated with an endoplasmic reticulum marker (antimycin A-insensitive NADH cytochrome c reductase), which was shifted from 1.11 to 1.20 grams per cubic centimeter by Mg(2+).Like the tonoplast H(+)-ATPase activity, vanadate-insensitive Ca(2+) accumulation was stimulated by 20 millimolar Cl(-) and inhibited by 10 micromolar 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid or 50 micromolar N,N'-dicyclohexylcarbodiimide. This Ca(2+) transport system had an apparent K(m) for Mg-ATP of 0.24 millimolar similar to the tonoplast ATPase. The vanadate-insensitive Ca(2+) transport was abolished by compounds that eliminated a pH gradient and Ca(2+) dissipated a pH gradient (acid inside) generated by the tonoplast-type H(+)-ATPase. These results provide compelling evidence that a pH gradient generated by the H(+)-ATPase drives Ca(2+) accumulation into right-side-out tonoplast vesicles via a Ca(2+)/H(+) antiport. This transport system was saturable with respect to Ca(2+) (K(m) apparent = 14 micromolar). The Ca(2+)/H(+) antiport operated independently of the H(+)-ATPase since an artifically imposed pH gradient (acid inside) could also drive Ca(2+) accumulation. Ca(2+) transport by this system may be one major way in which vacuoles function in Ca(2+) homeostasis in the cytoplasm of plant cells.",1
"Schumaker, K S, Sze, H",2
The equilibrium of the reaction catalyzed by sucrose phosphate synthase.,0
The equilibrium constant for the reaction catalyzed by sucrose phosphate synthase was reported 25 years ago to be 3250 at pH 7.5. It has been redetermined and found to be about 2 in the direction of synthesis and 6 to 10 when measured in the opposite direction.,1
"Barber, G A",2
Corn mitochondrial protein synthesis in response to heat shock.,0
"Corn (Zea mays L., W23(N), OH43(N), and reciprocal single cross hybrid) seedling mitochondria respond to a 10 degrees C temperature shift (27-37 degrees C) by incorporating a greater amount of [(35)S]methionine into acid-insoluble material than mitochondria incubated at the original growing temperature (27 degrees C). This increase is in part manifested in the enhanced synthesis of a 52 kilodaltons protein. At both temperatures mitochondria of two inbreds and their reciprocal hybrids synthesize normal (N) cytoplasm proteins sensitive to chloramphenicol and insensitive to cyclohexamide treatment. The 52 kilodaltons protein is found in the supernatants of pelleted (15,000g, 5 min) mitochondria after heat shock. The role of this protein in the heat shock response is discussed in light of the implication of mitochondria as the primary cellular target to temperature stress.",1
"Nebiolo, C M, White, E M",2
A Circadian Rhythm in the Number of Daughter Cells in Synchronous Chlorella fusca var vacuolata.,0
"Chlorella fusca var vacuolata cells were transferred to continuous darkness or weak light (0.07 watts per square meter) (both were called waiting time, WT) after a 12-hour light and 12-hour dark schedule. A daily dilution is performed at the end of the light/dark schedule, resulting in always the same average production of 18 autospores per mother cell. After 12 and 24 hours of WT in darkness, the production of autospores in a subsequent light/dark schedule was 50 and 100%, respectively. If the WT was performed in weak light (0.07 watts per square meter) the lowest production was obtained, independently of the length of WT. However, an interruption of this weak light by dark pulses (3 hours) increased the autospore production by an amount that depends upon the phase of the circadian rhythm, and varied up to 70% of the control (WT in permanent darkness). If the WT (total darkness) was interrupted by light pulses of 0.5 hour (white, same as used for growth), a phase response curve of productivity resulted. Pulses between the 12th and 18th hour of WT in darkness gave a 3-hour delay of maximum; later on pulses shifted the maximum autospore production 3 hours ahead.",1
"Wu, J T, Tischner, R, Lorenzen, H",2
Effects of Irradiance on Crassulacean Acid Metabolism in the Epiphyte Tillandsia usneoides L. (Bromeliaceae).,0
"Spanish moss (Tillandsia usneoides L.) was collected in South Carolina, maintained in a greenhouse, then exposed to five levels of photosynthetic photon flux density (PPFD) for 3 weeks. Following this treatment, plants were sampled for chlorophyll concentrations, nocturnal acid accumulations, and photosynthetic responses to subsequent exposure at a range of PPFD. No acclimation to PPFD was observed; all plants exhibited similar patterns of nocturnal CO(2) uptake and acid accumulation regardless of initial PPFD treatment. These patterns revealed that at a PPFD level of approximately 200 micromoles per square meter per second (daytime integrated PPFD of 10 moles per square meter per day), CAM saturated or, in low-PPFD plants, was optimal. The results of this study indicate that adaptation to high PPFD is not necessarily a requirement of CAM.",1
"Martin, C E, Eades, C A, Pitner, R A",2
A group translocator for sucrose assimilation in tonoplast vesicles of sugarcane cells.,0
"Existence of a group translocator for sucrose transfer into vacuoles of sugarcane (Saccharum sp.) cells has been further confirmed by the use of tonoplast vesicles isolated from intact vacuoles. The group translocator depends on external UDP-Glucose (Glc) and, via a series of enzymic reactions within the tonoplast, sucrose phosphate and sucrose are deposited inside the vesicles. Fructose-6-phosphate was not required for UDP-Glc uptake, nor was it taken up. None of the other sugar phosphates tested were taken up nor were the nucleotide sugars, UDP-Galactose and ADP-Glc. The uptake of UDP-Glc was concentration-dependent with a K(m) of 1.2 millimolar and a V(max) of 83.3 nanomoles per minute per milligram protein. The optimum pH for UDP-Glc uptake was 7.0. Uptake of UDP-Glc was inhibited by para-chloromercuribenzene-sulfonic acid, UDP, and GDP; carbonyl cyanide m-chlorophenylhydrazone inhibited to a lesser extent.",1
"Maretzki, A, Thom, M",2
Compartmentation and equilibration of abscisic Acid in isolated xanthium cells.,0
"The compartmentation of endogenous abscisic acid (ABA), applied (+/-)-[(3)H]ABA, and (+/-)-trans-ABA was measured in isolated mesophyll cells of the Chicago strain of Xanthium strumarium L. The release of ABA to the medium in the presence or absence of DMSO was used to determine the equilibration of ABA in the cells. It was found that a greater percentage of the (+/-)-[(3)H]ABA and the (+/-)-trans-ABA was released into the medium than of the endogenous ABA, indicating that applied ABA did not equilibrate with the endogenous material.Therefore, in further investigations only the compartmentation of endogenous ABA was studied. Endogenous ABA was released from Xanthium cells according to the pH gradients among the various cellular compartments. Thus, darkness, high external pH, KNO(2), and droughtstress all increased the efflux of ABA from the cells. Efflux of ABA from the cells in the presence of 0.6 m mannitol occurred within 30 seconds, but only 8% of the endogenous material was released during the 20 minute treatment.",1
"Bray, E A, Zeevaart, J A",2
"Relationship of Xylem Embolism to Xylem Pressure Potential, Stomatal Closure, and Shoot Morphology in the Palm Rhapis excelsa.",0
"Xylem failure via gas embolism (cavitation) induced by water stress was investigated in the palm Rhapis excelsa (Thumb.) Henry. Xylem embolism in excised stems and petioles was detected using measurements of xylem flow resistance: a decrease in resistance after the removal of flow-impeding embolisms by a pressure treatment indicated their previous presence in the axis. Results supported the validity of the method because increased resistance in an axis corresponded with: (a) induction of embolism by dehydration, (b) increased numbers of cavitations as detected by acoustic means, (c) presence of bubbles in xylem vessels. The method was used to determine how Rhapis accommodates embolism; results suggested four ways. (a) Embolism was relatively rare because pressure potentials reach the embolism-inducing value of about -2.90 megapascals only during prolonged drought. (b) When embolism did occur in nature, it was confined to the relatively expendable leaf xylem; the stem xylem, which is critical for shoot survival, remained fully functional. (c) Even during prolonged drought, the extent of embolism is limited by complete stomatal closure, which occurred at the xylem pressure potential of -3.20 +/- 0.18 megapascals. (d) Embolism is potentially reversible during prolonged rains, since embolisms dissolved within 5 h at a pressure potential of 0.00 megapascals (atmospheric), and xylem sap can approach this pressure during rain.",1
"Sperry, J S",2
Behavior and viability of tobacco protoplasts in response to electrofusion parameters.,0
"This investigation examines responses of protoplasts in a systematic and quantitative way to the various electrical treatments used to achieve electrofusion and their individual and cumulative effect on protoplast viability. Mesophyll and cell suspension protoplasts from two species of the same genera, Nicotiana tabacum and N. rustica var brasilia were used in these experiments. Optimal frequencies for alignment of tobacco protoplasts were between 500 kilohertz and 2 megahertz at 100 volts per centimeter. Variations in frequency and voltage of the alternating current (AC) field caused predictable movements of protoplasts within an electrofusion chamber. AC frequencies below 10 hertz or above 5 megahertz significantly decreased the viability of protoplasts in the fusion chamber as estimated by fluorescein diacetate staining 1 hour after treatment. Although the direct current (DC) pulse appeared to have a slight detrimental effect on protoplast viability, this effect was not significantly different from untreated control preparations.Protoplasts from both leaf mesophyll cells and suspension cells were induced to fuse with one or more 10 to 30 microseconds DC square wave pulses of approximately 1 kilovolt per centimeter after the protoplasts had been closely appressed with an AC field.",1
"Saunders, J A, Roskos, L A, Mischke, S, Aly, M A, Owens, L D",2
Paclobutrazol Inhibits Abscisic Acid Biosynthesis in Cercospora rosicola.,0
"Three plant growth regulators, paclobutrazol, ancymidol, and decylimidazole, which are putative inhibitors of gibberellin (GA) biosynthesis, were studied to determine their effect on abscisic acid (ABA) biosynthesis in the fungus Cercospora rosicola. All three compounds inhibited ABA biosynthesis, and paclobutrazol was the most effective, inhibiting ABA 33% at 0.1 micromolar concentrations. In studies using (E,E,)-[1-(14)C] farnesyl pyrophosphate, it was shown that ancymidol blocked biosynthesis prior to farnesyl pyrophosphate (FPP), whereas paclobutrazol and decylimidazole acted after FPP. The three inhibitors did not prevent 4'-oxidation of (2Z,4E)-alpha-ionylideneacetic acid. C. rosiciola metabolized ancymidol by demethylation to alpha-cyclopropyl-alpha-(p-hydroxyphenyl)-5-pyrimidine methyl alcohol. Paclobutrazol was not metabolized by the fungus. Information that these plant growth regulators inhibit ABA as well as GA biosynthesis should prove useful in determining the full range of action of these compounds.",1
"Norman, S M, Bennett, R D, Poling, S M, Maier, V P, Nelson, M D",2
Localization of carbamoylphosphate synthetase and aspartate carbamoyltransferase in chloroplasts.,0
"The localization of carbamoylphosphate synthetase (CPSase) and aspartate carbamoyltransferase (ACTase), the first two enzymes of the pyrimidine biosynthetic pathway, in chloroplasts was investigated. In dark-grown radish (Raphanus sativus) seedlings, light induced a prominent increase in CPSase activity, but had little effect on ACTase activity. Both enzymes were found in chloroplasts isolated from radish cotyledons and leaves of spinach (Spinacia oleracea), soybean (Glycine max), and corn (Zea mays). The higher activity of ACTase relative to CPSase is discussed in relation to the instability of carbamoylphosphate, the product of the CPSase, and to the control of pyrimidine synthesis. Based on these results, the function of CPSase and ACTase in chloroplasts is discussed.",1
"Shibata, H, Ochiai, H, Sawa, Y, Miyoshi, S",2
Properties of Plasma Membrane Isolated from Chilling-Sensitive Etiolated Seedlings of Vigna radiata L.,0
"Plasma membrane was isolated in a uniform population and with a high purity from chilling-sensitive etiolated young seedlings of Vigna radiata (mung bean) utilizing an aqueous two polymer phase separation system and subsequent sucrose density gradient. The isolated plasma membrane was associated with vanadate-sensitive and KNO(3)-insensitive ATPase. The ATPase has high specificities both for substrate and Mg(2+) ion with optimum pH at 6.5. It was slightly stimulated by monovalent anions, especially Cl(-). Proton ionophores such as gramicidin D and carbonyl cyanide p-trifluoromethoxyphenylhydrazone did not stimulate the enzyme activity. The ATPase is apparently latent and highly stimulated by the addition of detergents such as Triton X-100. A maximum stimulation was achieved by the addition of 0.02% Triton X-100. After treatment with proteinase K in an isotonic buffer solution, the enzyme activity was less affected, whereas the peptides were specifically digested. Based on these facts, the isolated plasma membrane vesicles appear to be tightly sealed and in a right-side-out orientation. The plasma membrane ATPase had two inflection points at higher (18.9 degrees C) and lower (6.7 degrees C) temperatures on the Arrhenius plots of the activity. The lower inflection temperature apparently coincided with that of the anisotropy parameter of embedded 1,6-diphenyl-1,3,5-hexatriene, indicating that the membrane bound ATPase activity was affected by a phase transition of membrane lipids and/or temperature-dependent conformational changes in the enzyme molecules per se. Considering the fact that the plant material used here is highly sensitive to chilling temperatures and injured severely by exposure to temperatures below 5 degrees C for a relatively short period, the thermotropic properties of membrane molecules are considered to be involved in the mechanism of chilling injury.",1
"Yoshida, S, Kawata, T, Uemura, M, Niki, T",2
Characterization of 12-oxo-phytodienoic Acid reductase in corn: the jasmonic Acid pathway.,0
"12-Oxo-phytodienoic acid reductase, an enzyme of the biosynthetic pathway that converts linolenic acid to jasmonic acid, has been characterized from the kernel and seedlings of corn (Zea mays L.). The molecular weight of the enzyme, estimated by gel filtration, was 54,000. Optimum enzyme activity was observed over a broad pH range, from pH 6.8 to 9.0. The enzyme had a K(m) of 190 micromolar for its substrate, 12-oxo-phytodienoic acid. The preferred reductant was NADPH, for which the enzyme exhibited a K(m) of 13 micromolar, compared with 4.2 millimolar for NADH. Reductase activity was low in the corn kernel but increased five-fold by the fifth day after germination and then gradually declined.",1
"Vick, B A, Zimmerman, D C",2
Relationship between Photosynthesis and Protein Synthesis in Maize: I. Kinetics of Translocation of the Photoassimilated Carbon from the Ear Leaf to the Seed.,0
"To gain a better understanding of the biochemical basis for partitioning of photosynthetically fixed carbon between leaf and grain, a (14)CO(2) labeling study was conducted with field-grown maize plants 4 weeks after flowering. The carbon flow was monitored by separation and identification of (14)C assimilates and (14)C storage components within each tissue during the chase period (from 4 to 96 hours) following a 5 minute (14)CO(2) pulse. In the labeled ear leaf, the radioactivity strongly decreased to reach, at the end of the experiment, about 12% of the total incorporated radioactivity, mostly associated with sucrose and proteins. Nevertheless, an unexpected reincorporation of radioactivity was observed either in leaf starch or proteins, the day following the pulse. Conversely, the radioactivity in the grain increased to attain 66% of the total incorporated (14)C after a 96 hour chase. The photosynthates, mostly sucrose, organic and free amino acids, rapidly translocated towards the developing seeds, served as precursors for the synthesis of seed storage compounds, starch, and proteins. They accumulate in free form for 24 hours before being incorporated within polymerized storage components. This delay is interpreted as a necessary prerequisite for interconversions prior to the polycondensations. In the grain, the labeling of the storage molecules, either in starch or in storage protein groups (salt-soluble proteins, zein, and glutelin subgroups), was independent of their chemical nature but dependent on their pool size.",1
"Moutot, F, Huet, J C, Morot-Gaudry, J F, Pernollet, J C",2
"Ethylene-induced increase in fructose-2,6-bisphosphate in plant storage tissues.",0
"TREATMENT OF CARROT ROOTS WITH ETHYLENE LED TO: (a) a doubling of the fructose-2,6-bisphosphate content; (b) a general increase in the concentration of glycolytic intermediates; and (c) an increase in the extractable activity of fructose-6-phosphate,2-kinase, the enzyme synthesizing fructose-2,6-bisphosphate from fructose-6-phosphate and adenosine triphosphate.",1
"Stitt, M, Cséke, C, Buchanan, B",2
"Distinction between Cytosol and Chloroplast Fructose-Bisphosphate Aldolases from Pea, Wheat, and Corn Leaves.",0
"A reinvestigation of cytosol and chloroplast fructose-1,6-bisphosphate (FBP) aldolases from pea (Pisum sativum L.), wheat (Triticum aestivum L.) and corn leaves (Zea mays L.) revealed that the two isoenzymes can be separated by chromatography on diethylaminoethyl (DEAE)-cellulose although the separation was often less clear-cut than for the two aldolases from spinach leaves. Definite distinction was achieved by immunoprecipitation of the two isoenzymes with antisera raised against the respective isoenzymes from spinach leaves. The proportion of cytosol aldolase as part of total aldolase activity was 8, 9, 14, and 4.5% in spinach (Spinacia oleracea L.), pea, wheat, and corn leaves, respectively. For corn leaves we also obtained values of up to 15%. The K(m) (FBP) values were about 5-fold lower for the cytosol (1.1-2.3 micromolar concentration) than for the chloroplast enzymes (8.0-10.5 micromolar concentration). The respective K(m) (fructose-1-phosphate, F1P) values were about equal for the cytosol (1.0-2.3 millimolar concentration) and for the chloroplast aldolase (0.6-1.7 millimolar concentration). The ratio V (FIP)/V (FBP) was 0.20 to 0.27 for the cytosol and 0.07 to 0.145 for the chloroplast aldolase. Thus, cytosol and chloroplast aldolases from spinach, pea, wheat, and corn leaves differ quite considerably in the elution pattern from DEAE-cellulose, in immunoprecipitability with antisera against the respective isoenzymes from spinach leaves, and in the affinity to FBP.",1
"Schnarrenberger, C, Krüger, I",2
Water stress enhances expression of an alpha-amylase gene in barley leaves.,0
"The amylases of the second leaves of barley seedlings (Hordeum vulgare L. cv Betzes) were resolved into eight isozymes by isoelectric focusing, seven of which were beta-amylase and the other, alpha-amylase. The alpha-amylase had the same isoelectric point as one of the gibberellin-induced alpha-amylase isozymes in the aleurone layer. This and other enzyme characteristics indicated that the leaf isozyme corresponded to the type A aleurone alpha-amylase (low pI group). Crossing experiments indicated that leaf and type A aleurone isozymes resulted from expression of the same genes.In unwatered seedlings, leaf alpha-amylase increased as leaf water potential decreased and ABA increased. Water stress had no effect on beta-amylase. alpha-Amylase occurred uniformly along the length of the leaf but beta-amylase was concentrated in the basal half of the leaf. Cell fractionation studies indicated that none of the leaf alpha-amylase occurred inside chloroplasts.Leaf radiolabeling experiments followed by extraction of alpha-amylase by affinity chromatography and immunoprecipitation showed that increase of alpha-amylase activity involved synthesis of the enzyme. However, water stress caused no major change in total protein synthesis. Hybridization of a radiolabeled alpha-amylase-related cDNA clone to size fractionated RNA showed that water-stressed leaves contained much more alpha-amylase mRNA than unstressed plants. The results of these and other studies indicate that regulation of gene expression may be a component in water-stress induced metabolic changes.",1
"Jacobsen, J V, Hanson, A D, Chandler, P C",2
Chilling Sensitivity in Oryza sativa: The Role of Protein Phosphorylation in Protection against Photoinhibition.,0
"The effects of exposure to low temperature on photosynthesis and protein phosphorylation in chilling-sensitive and cold-tolerant plant species were compared. Chilling temperatures resulted in light-dependent loss of photosynthetic electron transport in chilling-sensitive rice (Oryza sativa L.) but not in cold-tolerant barley (Hordeum vulgare L.). Brief exposure to chilling temperatures (0-15 degrees C, 10 min) did not cause a significant difference in photosynthetic O(2) evolution capacity in vivo between rice and barley. Analysis of in vivo chlorophyll fluorescence in chilling-sensitive rice suggests that low temperatures cause an increased reduction of the plastoquinone pool that could result in photoinhibitory damage to the photosystem II reaction centers. Analysis of (32)P incorporation into thylakoid proteins both in vivo and in vitro demonstrated that chilling temperature inhibited protein phosphorylation in rice, but not in barley. Low temperature (77 K) fluorescence analysis of isolated thylakoid membranes indicated that state I to state II transitions occurred in barley, but not in rice subjected to chilling temperatures. These observations suggest that protein phosphorylation may play an important role in protection against photoinhibition caused by exposure to chilling temperatures.",1
"Moll, B A, Steinback, K E",2
Temperature response of plasma membranes in tuber-bearing solanum species.,0
"Permeability coefficients (Kp) of nonelectroytes were determined at several temperatures for nonacclimated and acclimated plasma membranes of the frost sensitive Solanum tuberosum and the frost resistant Solanum commersonii. In nonacclimated membranes, Kp were equal at 25 degrees C for the two species. Kp decreased with decreased temperature in both species; however, the decrease was much greater in the frost sensitive S. tuberosum than in frost resistant S. commersonii.Kp increased with cold acclimation. After acclimation the temperature sensitivity of Kp or activation energy (Ea) for S. tuberosum was similar to that of S. commersonii; however, Kp for S. tuberosum were lower than those for S. commersonii at all temperatures.The differences in Kp and activation energy indicate plasma membrane differences between the species before acclimation. After acclimation there was still a difference between the plasma membranes of the two species as well as a difference between the nonacclimated and acclimated membranes of the same species.",1
"Fennell, A, Li, P H",2
Studies on the Mechanism of Regulation of the mRNA Level for a Soybean Storage Protein Subunit by Exogenous l-Methionine.,0
"In previous studies (GL Creason et al. 1983 Biochem Biophys Res Commun 117: 658-662; LP Holowach et al. 1984 Plant Physiol 74: 576-583), we have shown that when soybean (Glycine max L. Merrill cv Provar) cotyledons are cultured in medium supplemented with l-methionine, the beta-subunit of 7S protein and beta-mRNA are absent. We have carried out further studies on the mechanism of the methionine action. In one experiment, cotyledons were cultured for 16 days with or without methionine. After 4 days, some cotyledons were transferred from methionine-supplemented to basal (no methionine) medium and vice versa. In basal medium, beta-subunit was detected at 4 days whereas in methionine-supplemented medium, no beta-subunit was present. When cotyledons were transferred from basal to methionine-supplemented medium, the beta-subunit increased within a 4 day period and then remained constant (on a per cotyledon basis). This result indicated that methionine was not acting by accelerating the degradation of the beta-subunit. Four days after transfer from supplemented to basal medium cotyledons contained beta-subunit, thus demonstrating that the inhibition was reversible. During this time, the uncombined methionine declined from 7 to 1.5 mumoles methionine per gram fresh weight. When beta-mRNA was measured by in vitro translation, functional beta-mRNA was absent in tissue that was not accumulating beta-subunit. The messenger RNA for the beta-subunit had a half-life of about 1 day in the presence of methionine. Hybridization of cotyledon mRNA with cDNA complementary to beta-mRNA revealed that the 1700 nucleotide beta-mRNA was not present in supplemented cotyledons. Thus, expression of the beta-subunit gene is controlled at the level of transcription, RNA processing, or RNA turnover, rather than at the level of translation.",1
"Holowach, L P, Madison, J T, Thompson, J F",2
Plastid DNA content in a cultured soybean line capable of photoautotrophic growth.,0
"The levels of chloroplast DNA in a cultured photoautotrophic soybean (Glycine max [L.] Merr. v Corsoy) cell line were determined by molecular hybridization. The cells were also grown photomixotrophically and heterotrophically as suspension cultures and the level of plastid DNA was found to be constant at approximately 26% of the total cellular DNA in all three growth modes. By comparison, total cellular DNA extracted from plants of the same variety used as the explant source for the cultured cells contained 12.3 to 18.9% (leaves and seeds) and 6.1 to 8.9% (roots) plastid DNA.",1
"Cannon, G, Heinhorst, S, Weissbach, A",2
Sugar utilization by developing wild type and shrunken-2 maize kernels.,0
"To characterize the movement of sugars during kernel development in maize, a newly devised in vitro kernel development scheme was utilized. Viable seeds of wild type maize (Zea mays L.) as well as the mutant shrunken-2 (sh2) were found to mature when grown in culture with reducing sugars or sucrose as the carbon source. However, wild type and sh2 kernels had greater germination, starch content, and seed weight when sucrose, rather than reducing sugars, was the carbon source. By the use of labeled sucrose it was shown that sucrose can move into endosperm tissue without intervening degradation and resynthesis. These results show that when grown in vitro the maize seed can utilize reducing sugars for development, but it prefers sucrose.",1
"Cobb, B G, Hannah, L C",2
District programme to reduce smoking: can sustained intervention by general practitioners affect prevalence?,0
"A total of 101 general practitioners in 27 practices in inner London took part in a quasi-experimental study designed to examine whether a brief intervention applied to all smokers seen by general practitioners and sustained on a continuous basis could in time have a cumulative effect and reduce the prevalence of smoking among their patients. Of 21 practices approached in our local district (Camberwell), seven were willing to undertake brief intervention with support from the smokers' clinic (SBI), four opted for intervention without support (BI), and six acted as usual care controls. A further 10 out of 12 practices approached in South Hammersmith provided an unselected group of usual care controls. A series of six cross-sectional surveys were conducted over a three-year period. Each survey consisted of all adult patients attending to see a doctor during a defined two-week period, sample sizes averaging just over 9000 per survey. The estimated decline in self-reported smoking prevalence over the 30-month period following the start of intervention was 5.5% (from 36.4% to 30.9%) in the SBI group compared with 2.1% for BI and 2.8% and 3.0% in the two usual care control groups, the decline in the SBI group being significantly greater than in the other groups which did not differ significantly between each other. These interim results provide encouraging evidence that brief intervention by general practitioners with support and back-up from a local smokers' clinic can, when sustained on a continuous basis, reach sufficient smokers to reduce smoking prevalence in their practice populations. However, firm conclusions must await longer periods of observation now that the other Camberwell practices have adopted the SBI procedures.",1
"Russell, M A, Stapleton, J A, Hajek, P, Jackson, P H, Belcher, M",2
Levels of customary physical activity among the old and the very old living at home.,0
"With an activity inventory designed specifically for use among elderly people, detailed profiles of customary physical activity were obtained from 507 old (aged 65-74 years) and 535 very old (aged 75 years and over) individuals randomly sampled from the community. Participation in four categories of activity was assessed: outdoor productive activities; indoor productive activities; leisure activities; and walking. Customary engagement in many activities was found to be low, age (old versus very old) and sex being among the most important determinants of participation. The method of assessment is described, and activity profiles normative for older age groups are presented.",1
"Dallosso, H M, Morgan, K, Bassey, E J, Ebrahim, S B, Fentem, P H, Arie, T H",2
High and low risk groups for cancer of colon and rectum in Denmark: multiplicative Poisson models applied to register linkage data.,0
"Multiplicative Poisson models were used to identify subgroups of the Danish population at high and low risk of developing cancer of the right or left side of the colon, and cancer of the rectum. The analysis was based on cross-linked data from the 1970 census and the Danish Cancer Registry, where a 10-year follow-up period yielded some 20,000 colo-rectal cancers, in approximately 2.5 million persons. The risk of cancer of the right side of the colon in longer educated men living in apartment houses was almost twice as high as in farmers living in single family houses (relative risk 1.84; 95% confidence interval 1.42-2.37). A two-fold ratio (RR 2.18; 95% CI 1.70-2.62) was also seen in the risk of cancer of the left side of the colon between men with longer education in Greater Copenhagen and farmers in Jutland. The annual number of colon cancer cases in men in Denmark could be reduced by 27% if the incidence for all men was equal to that found for the low risk group of farmers.",1
"Mellemgaard, A, Engholm, G, Lynge, E",2
"Gastro-intestinal atresias in Finland in 1970-79, indicating time-place clustering.",0
"Information on oesophageal, duodenal and rectal atresias was collected from the hospitals, malformation register and death certificates in Finland from 1970-79. The respective prevalence rates were 4.1, 1.4 and 3.6 per 10,000 births, which are among the highest rates cited in the literature. Mothers of children with oesophageal and duodenal atresias were older than the average for child-bearing women in Finland. The sex ratio (male/female) of rectal atresia patients was 2.4. About 50% of the atresia patients had associated malformations. The data indicated time-spaced clustering for atresias. Furthermore, the cases of oesophageal and duodenal atresias appeared to spread within a time period of 30 days from a province to its neighbouring provinces to the north. Spreading was not observed for rectal atresias but clustering was noted when smaller geographic areas and individual communities were analysed. Occupations involving animal contacts were overpresented among the fathers of atresia patients. The data suggest infective aetiology, probably with no known clinical symptoms and no seasonal patterns.",1
"Kyyrönen, P, Hemminki, K",2
Epidemiological aspects of suicide among the young in selected European countries.,0
"Trends in reported suicide rates were analysed for the ages 5-24 years in 21 selected European countries in 1970-74 and 1980-84. In children the precision of the rates was found to be low though there appeared to be a trend to increased suicide in boys. In adolescent and young adult males, however, there was a definite increase in suicide over the period studied, and this was much more marked than in females, in whom the rates had declined in eight countries. The Belgian situation was investigated in detail. Increases were most pronounced in 20-24 year-old males. Around 1981, about half of youth suicides were committed by firearms and medicaments, and these methods showed the largest increases in risk. The estimated under-reporting error diminished with increasing age and over the past ten years. It was larger in females, but did not bias the trends substantially. On the aggregated level, youth suicide was found most strongly associated with indicators of anomie and social isolation. The relevance of these findings in the search for determinants and for preventive strategies is discussed.",1
"Moens, G F, Haenen, W, Van de Voorde, H",2
Height and social class in middle-aged British men.,0
"A study of 7735 middle-aged British men drawn from general practices in twenty-four towns shows that there has been a progressive increase in mean height in the men who were born between 1919 and 1939. This is true for both manual and non-manual classes, but the mean heights of the two groups are significantly different and remain widely separated over this period of time. Manual workers lag twenty years behind non-manual workers in their attained height. Data from other studies indicate that this social class difference in adult height is still present in those born up to 1960. The variation in mean height between the twenty-four towns is less marked than the variation in mean height between the social classes. After social class and age have been taken into account, a ""town effect"" on height is still present. If height is accepted as an indicator of socio-economic circumstances in childhood, then there is a difference in adult height between social class groups in Great Britain which does not appear to be diminishing.",1
"Walker, M, Shaper, A G, Wannamethee, G",2
"Risk factors in chronic obstructive pulmonary malfunction and ""chronic bronchitis"" symptoms in Beijing district: a joint study between Japan and China.",0
"A cross sectional study of risk factors in respiratory diseases was carried out in August 1986, in Beijing, China. Inhabitants greater than or equal to 40 years old were selected at random from a rural area, a residential area and an industrial area, using a two stage sampling method. The analysis presented here is based on the sample population of adults who (1) were prepared to be interviewed, using the British Medical Research Council's questionnaire translated into Chinese (n = 3423) and (2) had lung function measurements at the same time (n = 3373). Obstructive lung disease was defined as forced expiratory volume in 1s (FEV1) less than 68% of forced vital capacity (FVC). Seven variables were considered as potential risk factors or confounding factors: area of residence, sex, age, cigarette smoking, history of respiratory disease, socio-economic status and familial component. A modified binary variable regression method developed by Feldstein was used for the adjustment of rate ratios. The adjusted prevalence of obstructive lung disease was highest in the rural area and lowest in the residential area(s). An increase in age, cigarette smoking, low socio-economic status and positive history of respiratory diseases were associated with significantly higher rates of impaired pulmonary function. The other measured factors did not appear to be related to impaired pulmonary function.",1
"Yamaguchi, S, Kano, K, Shimojo, N, Sano, K, Xu, X P, Watanabe, H, Kameyama, M, Santamaria, M J, Liu, S J, Wang, L H",2
"Increased obstetric activity: a new meaning to ""induced labour""?",0
"This study examines the possible reasons for increased obstetric activity in Denmark over the past 25 years. Since 1960 there has been a substantial increase in the average number of hospital admissions (from 10 to 32 per 100 deliveries), in deliveries diagnosed as complicated (from 15 to 49%), and above all in major interventions at delivery (from 4 to 22%). In spite of this increase in activity there is no evidence that the postwar trend of decreasing perinatal mortality has been further improved during the period of study. It seems possible that the rising level of activity is the result of increasing availability of new technology, decreasing numbers of deliveries and unchanged obstetric staffing levels, with an increased tendency to diagnose and intervene in ""at risk"" pregnancies. There is a need to determine how the current level of obstetric activity has arisen. Since there is evidence for an increased expectation of intervention by pregnant women, the theory of supplier induced demand may be among the leading contenders to be tested.",1
"Vallgårda, S",2
Sexual behaviour of young people and the risk of HIV infection.,0
"A survey of 16-21 year old people in Somerset was undertaken to find out about their sexual behaviour prior to mounting a local education campaign on AIDS. A representative sample of 400 people, using quota sampling in 40 randomly selected electoral wards, completed a schedule structured part self administered questionnaire. Of these, 371 (92%) considered themselves heterosexual. Nearly half (47%) of the 16 year olds had engaged in sexual intercourse, rising to 89% by the age of 21. Mean frequency of sexual intercourse among the sexually active is 62 per year. The frequency of partner change decreases with increasing age for non-virgins from 2.1 for 16 year olds to 1.5 partner changes per year for 21 year olds (mean frequency 1.7 per year, ie, a new partner every 7 months). This level of sexual activity could eventually give rise to HIV prevalence rates similar to those found in Africa, i.e., 15-100 HIV antibody positive per 1000.",1
"Bowie, C, Ford, N",2
A prospective study of some aetiological factors in limb reduction defects in Sweden.,0
"Two groups of infants with limb reduction defects were studied: all such infants born in Sweden 1983-1986, and infants with severe reduction deformities born in 1973-1981. Data on the use of oral contraceptives, intrauterine devices, and drugs, and on maternal smoking were retrieved from information collected in early pregnancy as a part of routine maternity health service records. It was not possible to substantiate the association, described repeatedly in the literature, between limb reduction defects and the use of oral contraceptives just before or in early pregnancy. Various explanations for this discrepancy are discussed. An association with maternal diabetes was seen but not with drugs used for thyroid disease. A weak and statistically non-significant association with maternal smoking was found for severe limb reduction defects.",1
"Källén, B",2
Risk factors for breast cancer by mode of diagnosis: some results from a breast cancer screening study.,0
"We have investigated factors affecting the probability that a woman with breast cancer participating in a mammographic screening programme will be diagnosed by the screen. Data from a large American case-control study, with subjects drawn from women participating in an annual screening programme, were used. During the screening programme, 409 cases were identified, the mode of diagnosis being screen detection for 331 and interval detection for 78. No significant relationships were found between mode of diagnosis and age, age at menarche, oral contraceptive use, age at first live birth, age at menopause or history of maternal breast cancer. There was a non-significant trend for particular mammographic patterns to be associated with interval detection. However relative risk of breast cancer and probability of interval detection were observed to increase about the time of the menopause. These results suggest that the 3 yearly mammography programme being introduced in the UK might be improved if an extra examination was included around the time of the menopause.",1
"Whitehead, J, Cooper, J",2
The use of hormonal replacement therapy and the risk of stroke and myocardial infarction in women.,0
To determine whether there is an association between the use of hormonal replacement therapy (HRT) and the risk of stroke and myocardial infarction (MI).,1
"Thompson, S G, Meade, T W, Greenberg, G",2
Apparent effect of immune serum globulin prophylaxis in the military on viral hepatitis incidence in the civilian population in Israel.,0
"Since 1969, extensive use of immune serum globulin in the Israel Defence Force for prophylaxis against hepatitis A virus (HAV) infection has produced a sharp decline in the incidence of the disease. However, it is not clear whether this policy has affected the susceptibility of Israeli adults to HAV infection. In this study, we examined the effect of the immunisation policy on the incidence of hepatitis A virus infection in the civilian population in the 15-44 year age group, which includes all those who have completed compulsory military service since vaccination was introduced. The incidence of viral hepatitis in the Jewish civilian population aged 15-44 increased by approximately 50% 3-4 years after the implementation of the immunisation policy. This rise was not seen in the non-Jewish population of the same age nor among Jews aged 45-64. These findings strongly suggest that the immunisation policy in the military prevents both clinical and sub-clinical disease, but has had the effect of producing more susceptible people at an older age in the civilian population.",1
"Green, M S, Block, C",2
"Skinfold thickness, body mass index and ischaemic heart disease.",0
To determine the relationship between obesity and subsequent incidence of ischaemic heart disease (IHD).,1
"Imeson, J D, Haines, A P, Meade, T W",2
"Aftermath of stroke: an epidemiological study in Melbourne, Australia.",0
"A population-based study of the incidence of stroke was carried out in an urban area of Melbourne, Australia. The 508 cases were followed up and the survivors interviewed briefly at three months and in more depth six months after the onset of stroke. Fifty-eight per cent of all subjects had survived to six months, and the strongest prognostic indicator was level of consciousness at time of maximum impairment. By six months, 25% of all cases were independent in self-care and mobile outside the home; of those patients aged under 75 years, suffering a first stroke and retaining full consciousness at the time of maximum impairment, the proportion was 50%. A very imperfect correlation was present between residual physical impairment and return to the full range of prestroke activities.",1
"Christie, D",2
North Hammersmith stroke prevention project.,0
"The North Hammersmith stroke prevention project was designed to reduce the number of deaths from stroke in this health district by improving the detection of hypertensive patients and thereafter reducing the default rate from treatment. Starting in May 1979 general practitioners in the district were asked to register hypertensive patients over the age of 40 so that the proportion of such patients in each practice was known and could be compared with the average for all practices. This confidential information was fed back every year to the individual general practitioners so that they could assess their performance. Forty of 44 eligible general practitioners agreed to participate and 29 proceeded to register patients. Over a three year period 1006 patients were registered, representing 4.3% of the project population over the age of 40. Individual practice registration rates ranged from 1.1% to 9.1%. Sixty five per cent of the registered patients were women, 34% of all registrations were in the age group 60-69, 31% in the group 50-59, 12% in the group 40-49, and 23% in the group over 70. The average blood pressure before treatment was 190/111 mm Hg. After one and two years the patients were contacted or their notes examined to ensure that they still receiving treatment. Persistant default from treatment occurred in under 12% over the three year period.",1
"Penfold, D, Styles, W M, Bulpitt, C J",2
The use of cytotoxic plant lectins in cancer therapy.,0
"As part of their defense mechanism against herbivores or phytophagous insects, many plant tissues contain lectins. Some of these lectins are potent toxins which kill animal cells by arresting protein synthesis. An attractive strategy for developing specifically cytotoxic chemotherapeutic agents is to link cell type-specific monoclonal antibodies to potent toxins. The plant protein ricin has emerged as the toxin of choice for such constructs.",1
"Lord, J M",2
Synthesis of only two heat shock proteins is required for thermoadaptation in cultured cowpea cells.,0
"Cell cultures of a heat sensitive genotype of cowpea (Vigna unguiculata) were adapted to tolerate moderate levels of heat by maintaining cells at 32, 36, and 38 degrees C over many cell generations. Cells adapted to 32 and to 36 degrees C did not produce the typical heat shock proteins (HSP). Cells adapted to 38 degrees C synthesized two new proteins, which appear to be a subset of the HSP. In many temperature sensitive organisms it is thought that HSP confer thermotolerance. However, we hypothesize that specific proteins are associated with heat tolerance in cowpea, other heat tolerant plants (species such as sorghum and millet), and adapted cells which provide them with enhanced heat tolerance. From present data we suggest two proteins (70 and 80 kilodaltons) are strongly associated with heat tolerance and heat adaptation.",1
"Heuss-Larosa, K, Mayer, R R, Cherry, J H",2
Quantification of abscisic Acid in a single maize root.,0
"Quantitative analyses of abscisic acid in the elongating zone of a single maize root (Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growth rate.",1
"Reymond, P, Saugy, M, Pilet, P E",2
"Ion-exchange chromatography separates activities synthesizing and degrading fructose 2,6-bisphosphate from C3 and C4 leaves but not from rat liver.",0
"Fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase were separated on the basis of charge from leaves of C3 (spinach, lettuce, and pea) and C4 (sorghum and amaranthus) plants but not from rat liver--a tissue known to contain a bifunctional enzyme with both activities.  [2-32P]Fructose 2,6-bisphosphate binding experiments also suggest that the major forms of these activities reside on different proteins in leaves.",1
"Macdonald, F D, Chou, Q, Buchanan, B B, Buchanan, B B",2
Contiguous organization of nitrogenase genes in a heterocystous cyanobacterium.,0
"The organization of the three structural nitrogen fixation (nif) genes that encode nitrogenase (nif K and nif D) and nitrogenase reductase (nif H) have been examined in a number of cyanobacteria. Hybridization of Anabaena 7120 nif gene probes to restriction endonuclease-digested genomic DNA has shown (a) that cyanobacteria incapable of N(2) fixation have no regions of DNA with significant homology to the three nif probes, (b) that Pseudanabaena sp., a nonheterocystous cyanobacterium, has a contiguous nif KDH gene cluster, and (c) that in contrast with other heterocystous cyanobacteria, Fischerella sp. has a contiguous nif KDH gene cluster.",1
"Saville, B, Straus, N, Coleman, J R",2
Inhibition of na/h antiport activity in sugar beet tonoplast by analogs of amiloride.,0
The effects of amiloride and a series of amiloride analogs have been tested on the Na(+)/H(+) antiport activity in intact vacuoles and tonoplast vesicles isolated from sugar beet cell suspension cultures. There is a competitive interaction between amiloride analogs and sodium. Substitution of one or both H-atoms of the 5-amino group of amiloride (apparent K(i) about 150 micromolar) resulted in a 3- to 200-fold increase in inhibitory potency of the antiport activity.,1
"Blumwald, E, Cragoe, E J, Poole, R J",2
Transient Induction of Phenylalanine Ammonia-Lyase and 4-Coumarate: CoA Ligase mRNAs in Potato Leaves Infected with Virulent or Avirulent Races of Phytophthora infestans.,0
"Infection of potato leaves with the fungal pathogen Phytophthora infestans (Pi) resulted in the rapid stimulation of phenylpropanoid metabolism. Increases in the activities of several mRNAs, including those encoding phenylalanine ammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL), were detectable within a few hours postinoculation, as demonstrated by two-dimensional gel electrophoresis of proteins synthesized in vitro. This effect was closely mimicked by application of Pi culture filtrate through cut leaf stems. PAL and 4CL mRNA activities were also rapidly and transiently induced in potato cell suspension cultures by treatments with Pi culture filtrate or arachidonic acid. This induction was exploited to generate cDNA probes complementary to PAL and 4CL mRNAs. Blot hybridizations using these probes revealed almost immediate, transient and coordinate increases in the transcription rates and subsequent changes in the amounts of PAL and 4CL mRNAs in leaves treated with Pi culture filtrate. Similar changes in the mRNA amounts were found in infected leaves of potato cultivars carrying resistance genes R1 (cv Datura) or R4 (cv Isola), independent of whether a virulent or an avirulent Pi pathotype was used for inoculation. These results are discussed in relation to recent cytological observations with the same potato cultivars and Pi pathotypes.",1
"Fritzemeier, K H, Cretin, C, Kombrink, E, Rohwer, F, Taylor, J, Scheel, D, Hahlbrock, K",2
Changes in the level of free and ester indol-3yl-acetic Acid in growing maize roots.,0
"The levels of free and ester-linked indole-3-acetic acid (IAA) in different parts of the maize root were measured using gas chromatography-mass spectrometry (selected ion monitoring). In roots of 2-day-old plants, the distribution of free and ester IAA differed both along the root and between stele and cortex. The levels of IAA and IAA esters were then measured in whole roots and in the elongation zone using roots of different ages. The level of ester IAA decreased steadily with time. In contrast, the level of free IAA in the elongation zone was found to increase after a few days of culture at which time the rate of root growth was decreasing.",1
"Saugy, M, Pilet, P E",2
Regulation by Phospholipids and Kinetic Studies of Plant Membrane-Bound UDP-Glucose Sterol beta-d-Glucosyl Transferase.,0
"Solubilization and partial purification of the microsomal UDP-glucose sterol glucosyl transferase activity from maize coleoptiles by chromatography on DEAE-cellulose resulted in a highly delipidated (>95%) and inactive enzymic preparation. Addition of sterols revealed part of the activity and subsequent addition of phospholipids further increased the activity. Negatively charged phospholipids were shown to be by far the best activators. The purification step also produced the elimination of two interfering microsomal enzymic activities: UDPase and steryl glucoside acyl transferase. The removal of these two enzymic activities was a prerequisite for kinetic studies including product-inhibition studies, since the substrates of these two latter enzymes are the products of UDPG-SGTase activity. The results of the kinetic studies strongly suggest an ordered bi-bi mechanism for the glucosylation of sterols. Finally the effect of different phospholipids on the kinetic parameters of the reaction was studied. Both phosphatidylcholine and phosphatidylglycerol significantly decrease K(m-sterol) (and not K(m-UDPglucose)) and increase the reaction V(max). The decrease of K(m-sterol) is similar with both phospholipids whereas the increase of V(max) is much greater with phosphatidylglycerol than with phosphatidylcholine.",1
"Ullmann, P, Bouvier-Navé, P, Benveniste, P",2
Subcellular Localization of Amines and Activities of Their Biosynthetic Enzymes in p-Fluorophenylalanine Resistant and Wild-Type Tobacco Cell Cultures.,0
"Three levels of free amines and the activities of their biosynthetic enzymes were measured in subcellular fractions of two cell lines of Nicotiana tabacum L. cv Xanthi. The TX4 cell line, a p-fluorophenylalanine resistant culture which accumulates high levels of cinnamoylamides, was compared to the wild-type culture TX1. In cells harvested on day 6 of the growth cycle, nearly all free putrescine, spermidine, and tyramine was found in the supernatant fraction of both cell lines. Although a consistent portion of ornithine decarboxylase activity was detected in the nuclear-enriched fractions of TX1 and TX4, the largest levels of activity were in the supernatants of both lines. In TX1, arginine decarboxylase activity was low relative to that of ornithine decarboxylase, but, in the TX4 line arginine decarboxylase levels in the cytosol were substantially elevated. Tyrosine decarboxylase was not detected in 6-day-old TX1 cells, but significant amounts of activity were measured in the 1000g and supernatant fractions of TX4. S-Adenosylmethionine decarboxylase activity was low in both cell lines and was located predominantly in the supernatant.",1
"Walker, M A, Ellis, B E, Chapple, C C, Dumbroff, E B",2
Free amino Acid content and metabolic activities of setting and aborting soybean ovaries.,0
"Fruits of soybean (Glycine max [L.] Merr.) that are destined to abscise shortly after anthesis grow more slowly than fruits that will be retained. In this work, amino acid composition, protein metabolism, and nucleic acid metabolism were studied in setting and abscising soybean ovaries from anthesis to 6 days after anthesis to provide additional evidence of chemical processes associated with abscission. Principal free amino acids were asparagine, aspartic acid, glutamic acid, serine, and glutamine. Percent aspartate and glutamate declined as the ovaries grew, with aspartate declining more in abscising and glutamate more in setting ovaries. Percent glutamate was positively correlated to percent abscission throughout the period. Proline, serine, and leucine were positively correlated to abscission from 0 to 2 days after anthesis, whereas significant negative correlations were observed at these ages for ethanolamine and arginine. (75)Se fed as selenate and (14)C fed as sucrose, glycine, and alanine were readily incorporated into soluble and insoluble proteins in a 24-hour in vitro incubation. Radioactivity of total proteins, expressed on a perovary basis, was negatively correlated with percent abscission and positively correlated with ovary weight. [(14)C]Glutamine and serine followed the opposite pattern, with greater protein labeling in abscising than in setting ovaries. When data were expressed as disintegrations per minute per milligram ovary fresh weight, protein labeling from alanine was seen to be significantly greater in abscising ovaries at anthesis and throughout the sampling period. Nucleic acid labeling from uridine was highly correlated to ovary weight; labeling from thymidine was greater in setting than abscising ovaries at anthesis and in abscising ovaries at later stages of development. It is concluded that abscising ovaries can continue amino acid metabolism almost up to the date of separation from the raceme, and that the involvement of alanine, glutamine, aspartate, glutamate, and other amino acids in soybean flower abortion deserves further study.",1
"Ghiasi, H, Paech, C, Dybing, C D",2
Plant Morphological and Biochemical Responses to Field Water Deficits: III. Effect of Foliage Temperature on the Potential Activity of Glutathione Reductase.,0
"Activity of glutathione reductase has been related to stress tolerance; however, these enzyme assays are generally conducted at 25 degrees C. Foliage temperature varies greatly in the field in response to soil water availability and ambient conditions and this may affect enzyme response. This study was conducted to determine the effect of changing foliage temperature on glutathione reductase activity of wheat under field conditions. Wheat leaf glutathione reductase was purified and the temperature response of the enzyme was determined at 2.5 degrees C intervals between 12.5 and 45 degrees C. These data, in conjunction with continuous measurements of field-grown wheat foliage temperatures, were used to compare the temperature-related changes in potential glutathione reductase activities in water stressed and control plants. Assuming saturating substrate levels, the results indicate that early in the season the daily potential enzyme activity of the irrigated and stressed plants could never have reached the daily activity predicted from the 25 degrees C (room temperature) measurements. Later in the season, the daily potential activity of the irrigated plants was lower, and the daily potential activity of the stressed plants was higher, than the activities predicted from the 25 degrees C determinations. These results suggest that a better understanding of the regulation of plant metabolism will be obtained by linking continuous temperature measurements of plant foliage with enzyme responses to temperature.",1
"Burke, J J, Hatfield, J L",2
"Glycine-Glomus-Rhizobium Symbiosis : VI. Photosynthesis in Nodulated, Mycorrhizal, or N- and P-Fertilized Soybean Plants.",0
"Soybean (Glycine max [L.] Merr. cv Hobbit) plants were grown in a growth chamber for 56 days in a phosphorus- and nitrogen-deficient soil and were colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd) Gerd. and Trappe and Rhizobium japonicum strain USDA 136, or by either organism alone, or by neither. Non-VAM plants received supplemental phosphorus and nonnodulated plants supplemental nitrogen to achieve the same rate of growth in all treatments. Plants of all four treatments had the same (P > 0.05) dry weights at harvest, but VAM plants had higher rates of CO(2) exchange (CER, P < 0.05) and lower leaf P concentrations (P < 0.01). Leaf nitrogen concentrations were lower in nodulated than in nitrogen-supplemented plants (P < 0.01) while starch concentrations were higher (P < 0.01). There was a significant negative relationship between nitrogen and starch (r = -0.989). Statistical evaluation of the data showed that some parameters (CER, leaf area and phosphorus content) were associated with phosphorus nutrition (or the presence of the VAM fungus), others (leaf fresh weight and root dry weight) with nitrogen nutrition (or the presence of Rhizobium), and some (leaf nitrogen and starch content) by both factors. The development of microsymbiont structures and nodule activity were significantly lower in the tripartite association than in plants colonized by one endophyte only. The findings suggest that endophyte effects go beyond those of simple nutrition and associated source-sink relationships.",1
"Brown, M S, Bethlenfalvay, G J",2
Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots.,0
"The recent proposal of Tipton and Thowsen (Plant Physiol 79: 432-435) that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prélude) plants. The role of O(2) in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O(2). However, in the presence of O(2) the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O(2) ([unk]), as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron transport in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O(2) ([unk]) may have in the acquisition of ferric iron by dicotyledonous plants.",1
"Cakmak, I, van de Wetering, D A, Marschner, H, Bienfait, H F",2
Alteration of Gene Expression during the Induction of Freezing Tolerance in Brassica napus Suspension Cultures.,0
"Brassica napus suspension-cultured cells can be hardened to a lethal temperature for 50% of the sample of -20 degrees C in eight days at room temperature with abscisic acid. During the induction of freezing tolerance, changes were observed in the electrophoretic pattern of [(35)S]methionine labeled polypeptides. In hardening cells, a 20 kilodalton polypeptide was induced on day 2 and its level increased during hardening. The induction of freezing tolerance with nonmaximal hardening regimens also resulted in increases in the 20 kilodalton polypeptide. The 20 kilodalton polypeptide was associated with a membrane fraction enriched in endoplasmic reticulum and was resolved as a single spot by two-dimensional electrophoresis. In vitro translation of mRNA indicate alteration of gene expression during abscisic acid induction of freezing tolerance. The new mRNA encodes a 20 kilodalton polypeptide associated with increased freezing tolerance induced by either abscisic acid or high sucrose. A 20 kilodalton polypeptide was also translated by mRNA isolated from cold-hardened B. napus plants.",1
"Johnson-Flanagan, A M, Singh, J",2
Orientation of electron transport activities in the membrane of intact glyoxysomes isolated from castor bean endosperm.,0
"Intact glyoxysomes were isolated from castor bean endosperm on isometric Percoll gradients. The matrix enzyme, malate dehydrogenase, was 80% latent in the intact glyoxysomes. NADH:ferricyanide and NADH:cytochrome c reductase activities were measured in intact and deliberately broken organelles. The latencies of these redox activities were found to be about half the malate dehydrogenase latency. Incubation of intact organelles with trypsin eliminated NADH:cytochrome c reductase activity, but did not affect NADH:ferricyanide reductase activity. NADH oxidase and transhydrogenase activities were negligible in isolated glyoxysomes. Mersalyl and Cibacron blue 3GA were potent inhibitors of NADH:cytochrome c reductase. Quinacrine, Ca(2+) and Mg(2+) stimulated NADH:cytochrome c reductase activity in intact glyoxysomes. The data suggest that some electron donor sites are on the matrix side and some electron acceptor sites are on the cytosolic side of the membrane.",1
"Luster, D G, Donaldson, R P",2
Mutations in Chlamydomonas reinhardtii Conferring Resistance to the Herbicide Sulfometuron Methyl.,0
"Chlamydomonas reinhardtii mutants resistant to the herbicide sulfometuron methyl (SM) were isolated and characterized. Growth of C. reinhardtii is sensitive to inhibition by SM at a concentration of 1 micromolar. Four mutants resistant to 10- to 100-fold higher concentrations were isolated. All possess a form of acetolactate synthase (ALS) whose specific activity in cell extracts is 100- to 1000-fold more resistant to SM than is the specific activity of wild-type enzyme. Only one mutant had abnormally low ALS specific activity in the absence of SM. All mutations were inherited as single lesions in the nuclear genome and were expressed in heterozygous diploids. The mutations in two strains mapped to linkage group IX about 30 centimorgans from streptomycin resistance and on the same side of the centromere, and in genetic crosses between mutants no segregation was observed. Accordingly, all mutations are tentatively assigned to gene smr-1. Herbicide resistance appears to be suitable as a selectable marker for molecular transformation in this organism.",1
"Hartnett, M E, Newcomb, J R, Hodson, R C",2
"Reduction State of Q and Nonradiative Energy Dissipation during Photosynthesis in Leaves of a Crassulacean Acid Metabolism Plant, Kalanchoë daigremontiana Hamet et Perr.",0
"Fluorescence was measured in leaves of the CAM plant Kalanchoë daigremontiana using a pulse modulation technique at room temperature. During a 12-h light period at 500 micromole photons per square meter per second (400-700 nanometers) in air containing 350 microbar CO(2), the component of fluorescence quenching related to the reduction state of Q, the primary electron transport acceptor of PSII, remained fairly constant and showed that only 20% of Q were in the reduced form. The reduction state was slightly increased at the onset and at the end of the light period. By contrast, the nonphotochemical component of fluorescence quenching which is a measure of the fraction of nonradiative deexcitation underwent marked diurnal changes. Nonradiative energy conversion was low during the phase of most active malic acid decarboxylation in the middle of the light period when uptake of atmospheric CO(2) was negligible, and when internal CO(2) partial pressures were higher than in air; this allowed for high rates of CO(2) reduction in the chloroplasts. Nonradiative energy conversion was high during the early and the late light period when atmospheric CO(2) was taken up and internal CO(2) partial pressures were below air level. Manipulation of the internal CO(2) partial pressure during the late light period by increasing or decreasing the external CO(2) partial pressure to 1710 and 105 microbar, respectively, led to changes in the magnitude of energy dependent fluorescence quenching which were consistent with the relationship between nonradiative energy dissipation and internal CO(2) partial pressure observed during the diurnal cycle. Again, the reduction state of Q was hardly affected by these treatments. Thus, changes in electron transport rate during the diurnal CAM cycle at a given photon flux density lead primarily to alterations in the rate of nonradiative energy dissipation, with the reduction state of Q being maintained at a relatively low and constant level. Conditions are described under which nonphotochemical dissipation of excitation energy reaches a maximum value and the reduction state of Q is increased.",1
"Winter, K, Demmig, B",2
Phytochelatin synthesis and glutathione levels in response to heavy metals in tomato cells.,0
"Cell suspension cultures of tomato, Lycopersicon esculentum Mill. cv VFNT-Cherry, produce phytochelatins (poly[gamma-glutamylcysteinyl]glycines) when exposed to cadmium. The synthesis of these peptides is accompanied by a decline in cellular levels of glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, inhibits the sustained production of phytochelatins. However, phytochelatin synthesis can occur in the presence of buthionine sulfoximine provided that sufficient glutathione is available. These results indicate that glutathione is a substrate for phytochelatin synthesis. The protein synthesis inhibitor cycloheximide does not affect the initial production of phytochelatin.",1
"Scheller, H V, Huang, B, Hatch, E, Goldsbrough, P B",2
"Osmotic adjustment, symplast volume, and nonstomatally mediated water stress inhibition of photosynthesis in wheat.",0
"At low water potential (psi(w)), dehydration reduces the symplast volume of leaf tissue. The effect of this reduction on photosynthetic capacity was investigated. The influence of osmotic adjustment on this relationship was also examined. To examine these relationships, comparative studies were undertaken on two wheat cultivars, one that osmotically adjusts in response to water deficits (;Condor'), and one that lacks this capacity (;Capelle Desprez'). During a 9-day stress cycle, when water was withheld from plants grown in a growth chamber, the relative water content of leaves declined by 30% in both cultivars. Leaf osmotic potential (psi(s)) declined to a greater degree in Condor plants. Measuring psi(s) at full turgor indicated that osmotic adjustment occurred in stressed Condor, but not in Capelle plants. Two methods were used to examine the degree of symplast (i.e. protoplast) volume reduction in tissue rapidly equilibrated to increasingly low psi(w). Both techniques gave similar results. With well-watered plants, symplast volume reduction from the maximum (found at high psi(w) for each cultivar) was the same for Condor and Capelle. After a stress cycle, volume was maintained to a greater degree at low psi(w) in Condor leaf tissue than in Capelle. Nonstomatally controlled photosynthesis was inhibited to the same degree at low psi(w) in leaf tissue prepared from well-watered Condor and Capelle plants. However, photosynthetic capacity was maintained to a greater degree at low psi(w) in tissue prepared from stressed Condor plants than in tissue from stressed Capelle plants. Net CO(2) uptake in attached leaves was monitored using an infrared gas analyzer. These studies indicated that in water stressed plants, photosynthesis was 106.5% higher in Condor than Capelle at ambient [CO(2)] and 21.8% higher at elevated external [CO(2)]. The results presented in this report were interpreted as consistent with the hypothesis that there is a causal association between protoplast (and presumably chloroplast) volume reduction at low psi(w) and low psi(w) inhibition of photosynthesis. Also, the data indicate that osmotic adjustment allows for maintenance of relatively greater volume at low psi(w), thus reducing low psi(w) inhibition of chloroplast photosynthetic potential.",1
"Gupta, A S, Berkowitz, G A",2
Bacillus thuringiensis section sign-Endotoxin Expressed in Transgenic Nicotiana tabacum Provides Resistance to Lepidopteran Insects.,0
"The crystal proteins, or section sign-endotoxins, of Bacillus thuringiensis are specifically lethal to Lepidopteran insects. We utilized a truncated and modified portion of a cloned crystal protein gene to construct a chimeric gene capable of expression in plant cells. Using an Agrobacterium tumefaciens binary vector system, we then transferred the chimeric toxin gene into tobacco (Nicotiana tabacum cv Havana 425) cells and regenerated recombinant plants. One to several copies per cell of the toxin gene are routinely present in the recombinant plants. Hybridization experiments demonstrated that these plants had a new RNA species of the size expected for the truncated toxin mRNA, and a polypeptide having the mobility expected for the truncated toxin was detected by immunoblotting. Significant variation was found in the levels of toxin-specific RNA expression between different recombinants, but the levels of hybridizing RNA in transformants correlated with the level of toxicity demonstrated against Manduca sexta (tobacco hornworm), and other Lepidopteran insects. The recombinant genes were transmitted to progeny and resistance to insects was maintained, thus demonstrating that the introduction of toxin genes into plants may be a practical method of providing protection against certain insect pests.",1
"Barton, K A, Whiteley, H R, Yang, N S",2
"Isolation and characterization of plant genes coding for acetolactate synthase, the target enzyme for two classes of herbicides.",0
"Acetolactate synthase (ALS) is the first common enzyme in the biosynthetic pathways to valine, isoleucine, and leucine. It is the target of two structurally unrelated classes of herbicides, the sulfonylureas and the imidazolinones. Genomic clones encoding ALS have been isolated from the higher plants Arabidopsis thaliana and Nicotiana tabacum, using a yeast ALS gene as a heterologous hybridization probe. Clones were positively identified by the homology of their deduced amino acid sequences with those of yeast and bacterial ALS isozymes. The tobacco and Arabidopsis ALS genes have approximately 70% nucleotide homology, and encode mature proteins which are approximately 85% homologous. Little homology is seen between the amino acid sequences of the presumptive N-terminal chloroplast transit peptides. Both plant genes lack introns. The tobacco ALS gene was isolated from a line of tobacco which is resistant to the sulfonylurea herbicides due to an alteration in ALS. The tobacco gene which was isolated codes for an ALS that is sensitive to the herbicides, as assayed by transformation of the gene into sensitive tobacco cells.",1
"Mazur, B J, Chui, C F, Smith, J K",2
Isozymes of beta-N-Acetylhexosaminidase from Pea Seeds (Pisum sativum L.).,0
"Four isozymes of beta-N-acetylhexosaminidase (beta-NAHA) from pea seeds (Pisum sativum L.) have been separated, with one, designated beta-NAHA-II, purified to apparent homogeneity by means of an affinity column constructed by ligating p-aminophenyl-N-acetyl-beta-d-thioglucosaminide to Affi-Gel 202. The other three isozymes have been separated and purified 500- to 1750-fold by chromatography on Concanavalin A-Sepharose, Zn(2+) charged immobilized metal affinity chromatography, hydrophobic chromatography, and ion exchange chromatography on CM-Sephadex. All four isozymes are located in the protein bodies of the cotyledons. The molecular weight of each isozyme is 210,000. beta-NAHA-II is composed of two heterogenous subunits. The subunits are not held together by disulfide bonds, but sulfhydryl groups are important for catalysis. All four isozymes release p-nitrophenol from both p-nitrophenyl-N-acetyl-beta-d-glucosaminide and p-nitrophenyl-N-acetyl-beta-d-galactosaminide. The ratio of activity for hydrolysis of the two substrates is pH dependent. The K(m) value for the two substrates and pH optima of the isozymes are comparable to beta-NAHAs from other plant sources.",1
"Harley, S M, Beevers, L",2
Biochemistry of Oleoresinosis : Monoterpene and Diterpene Biosynthesis in Lodgepole Pine Saplings Infected with Ceratocystis clavigera or Treated with Carbohydrate Elicitors.,0
"Elevated levels of monoterpenes and diterpene resin acids are produced in the stems of lodgepole pine (Pinus contorta var latifolia) saplings when wounded and inoculated with the blue-stain fungus Ceratocystis clavigera or when wounded and treated with a pectic fragment from tomato leaves (PIIF) or a fungal cell wall fragment (chitosan). This induced defensive response (hyperoleoresinosis) is the result of a transient rise in the ability to biosynthesize cyclic monoterpenes and diterpene resin acids as measured by the in vivo incorporation of label from [U-(14)C]sucrose relative to untreated controls, and is accompanied by a corresponding rise in the levels or activities of the relevant terpene cyclases as determined by in vitro assay using labeled acyclic precursors. The results indicate that juvenile P. contorta responds to infection and biotic elicitors much like the mature tree, and they suggest that the Pinaceae possess a mechanism for elicitor recognition and induced defense similar to that of other higher plants.",1
"Croteau, R, Gurkewitz, S, Johnson, M A, Fisk, H J",2
"Structure, Function, and Evolution of Proton-ATPases.",0
"Proton-ATPases are among the most important primary ion pumps in nature. There are three classes of these enzymes which are distinguished by their structure, function, mechanism of action, and evolution. They function in ATP formation at the expense of a protonmotive force generated by oxidative and photosynthetic electron transports, maintaining a constant pH in the cytoplasm, and forming acidic spaces in special compartments inside and outside the cell. The three classes of proton-ATPases evolved in a way that prevents functional assembly in the wrong compartment. This was achieved by a triple genetic system located in the nucleus, mitochondria and chloroplast, as well as delicate control of the proton pumping activity of the enzymes.",1
"Nelson, N",2
Effects of Previous Pollination and Stylar Ethylene on Pollen Tube Growth in Petunia hybrida Styles.,0
"The effect of ethylene on the growth rate of pollen tubes in styles of Petunia hybrida was examined. Apart from its strong inhibition of pollination-induced ethylene synthesis, aminoethoxyvinylglycine, placed on the stigma, did not impede tube growth. The inhibitors of the action of ethylene, silver thiosulfate and 2,5-norbornadiene, were similarly ineffective. Application of the ethylene precursor, 1-amino-cyclopropane-1-carboxylic acid, onto the stigma at different intervals prior to pollination evoked synthesis of ethylene, but was without effect on tube growth. However, prepollination (by 24 hours) with Nicotiana tabacum pollen, significantly enhanced tube growth of Petunia pollen. This enhancement was not counteracted by the pretreatment of stigmas with aminoethoxy-vinylglycine. It is concluded that the ethylene associated with pollination is without effect on pollen tube growth in the style, but that other pollination-induced factors may lead to an acceleration of growth.",1
"Hoekstra, F A, van Roekel, T",2
Transcription of Two Photosynthesis-Associated Nuclear Gene Families Correlates with the Presence of Chloroplasts in Leaves of the Variegated Tomato ghost Mutant.,0
"Leaves of the tomato ghost mutant show a variegated green/white phenotype due to a somatically unstable genetic block in carotenoid biosynthesis. Colored carotenoids are not synthesized in white leaves; consequently, chlorophyll is destroyed by photooxidation and the plastids formed show little development of internal membrane structures. Carotenoid biosynthesis proceeds to wild type levels in green tissue, thus chlorophyll accumulates and chloroplasts develop normally. The presence of green sectors allows for the production through tissue culture of variegated green/white plants, in which growth is supported by the photosynthetic green tissue. Thus, ghost is the first plant carotenoid mutant that can be grown to maturity. We determined the steady state mRNA levels for two nuclear gene families that code for chloroplast proteins: rbcS, which codes for the small subunit of ribulose-1-5-bisphosphate carboxylase; and cab, which codes for chlorophyll a/b binding protein. In ghost plants grown in light, the steady state mRNA levels for both gene families were low in white leaves but were similar to wild type in green leaves. Light regulation of the transcripts studied was observed in both ghost green and white leaves. Transcription experiments conducted on nuclei isolated from green and white leaves indicate that the low levels of cytoplasmic mRNAs observed in the absence of colored carotenoids and/or light are due to reduced rates of transcription. We conclude that maximum transcription of rbcS and cab genes in leaves of mature tomato plants requires both light and mature chloroplasts.",1
"Giuliano, G, Scolnik, P A",2
Inhibition of Acetyl-CoA Carboxylase Activity by Haloxyfop and Tralkoxydim.,0
"Acetyl-coenzyme A (CoA) carboxylase from maize (Zea mays L.) is inhibited by nanomolar concentrations of both haloxyfop, an aryloxyphenoxypropionate, and tralkoxydim, a cyclohexanedione herbicide. These results suggest that acetyl-CoA carboxylase, which catalyzes the first committed step in fatty acid biosynthesis, may be the target of these herbicides, contrary to an earlier report suggesting that aryloxyphenoxypropionate herbicides do not inhibit acetyl-CoA carboxylase.",1
"Secor, J, Cséke, C",2
Interference of phenolic compounds with the 1-aminocyclopropane-1-carboxylic Acid assay.,0
"The yields of ethylene from endogenous and exogenous 1-aminocyclo-propane-1-carboxylic acid (ACC) in avocado (Persea Americana Mill.) fruit pedicel extracts were very low when assayed by the method of Lizada and Yang (1979 Anal Biochem 100: 140-145). Addition of phenolic compounds, which are present in avocado tissues, to the assay mixture significantly reduced the conversion efficiency of ACC to ethylene. A negative correlation was found between the amount of the plant material in the assay mixture and the conversion efficiency of ACC to ethylene. Removal of phenolic compounds from pedicel extracts by polyvinylpolypyrrolidone, Amberlite XAD-7, and Dowex-50 column chromatography or lead acetate precipitation greatly increased the yields of thylene from ACC in these extracts. The use of polyvinylpolypyrrolidone column chromatography also enabled us to obtain more accurate estimations of endogenous ACC levels in carnation (Dianthus caryophyllus L.) petal extracts. The conversion efficiency of ACC to ethylene could be improved by increasing the concentrations of mercuric chloride and NaOCl in the assay mixture.",1
"Sitrit, Y, Riov, J, Blumenfeld, A",2
Growth and mitochondrial respiration of mungbeans (Phaseolus aureus Roxb.) germinated at low pressure.,0
"Mungbean (Phaseolus aureus Roxb.) seedlings were grown hypobarically to assess the effects of low pressure (21-24 kilopascals) on growth and mitochondrial respiration.  Control seedlings grown at ambient pressure (101 kilopascals) were provided amounts of O2 equivalent to those provided experimental seedlings at reduced pressure to factor out responses to O2 concentration and to total pressure.  Respiration was assayed using washed mitochondria, and was found to respond only to O2 concentration.  Regardless of total pressure, seedlings grown at 2 millimoles O2 per liter had higher state 3 respiration rates and decreased percentages of alternative respiration compared to ambient (8.4 millimoles O2 per liter) controls.  In contrast, seedling growth responded to total pressure but not to O2 concentration.  Seedlings were significantly larger when grown under low pressure.  While low O2 (2 millimoles O2 per liter) diminished growth at ambient pressure, growth at low pressure in the same oxygen concentration was enhanced.  Respiratory development and growth of mungbean seedlings under low pressure is unimpaired whether oxygen or air is used as the chamber gas, and further, low pressure can improve growth under conditions of poor aeration.",1
"Musgrave, M E, Gerth, W A, Scheld, H W, Strain, B R, Musgrave, M E",2
Changes in Free and Conjugated Indole 3-Acetic Acid and Abscisic Acid in Young Cotton Fruits and Their Abscission Zones in Relation to Fruit Retention during and after Moisture Stress.,0
"Experiments were conducted with field-grown cotton (Gossypium hirsutum L.) in 1985 and 1986 to determine effects of water deficit on levels of conjugated indole 3-acetic acid (IAA) and abscisic acid (ABA) in young fruits (bolls) and their abscission zones in relation to boll retention. Tissues were harvested three times during an irrigation cycle in 1985. They were harvested twice during an irrigation cycle and once after irrigation in 1986 to determine extent of recoveries of measured parameters. As reported earlier, the free IAA content of abscission zones decreased with moisture stress. Irrigation caused a partial recovery in free IAA content of abscission zones and caused a partial recovery in rate of boll retention. In contrast to free IAA, conjugated IAA increased with water deficit, both in 3-day-old bolls and in their abscission zones. Bolls contained much more ester IAA than their abscission zones. Some, but not all, of the increase in ester IAA in bolls during moisture stress could have come from a conversion of amide-linked IAA. Amide IAA decreased slightly during stress and increased after irrigation, but the concentration was low relative to ester IAA. Free and conjugated ABA both increased during stress and decreased after irrigation. However, the concentration of conjugated ABA remained relatively high in abscission zones. Ester IAA, being more resistant than free IAA to enzymic destruction during stress, may hasten recovery of fruit retention after relief of stress by providing a source of free IAA in abscission zones to inhibit continued abscission.",1
"Guinn, G, Brummett, D L",2
Effects of soil strength on the relation of water-use efficiency and growth to carbon isotope discrimination in wheat seedlings.,0
"The ratio of carbon accumulation to transpiration, W, of wheat (Triticum aestivum L.) seedlings increased with increasing soil strength, measured as soil penetrometer resistance, and this was already apparent at the two leaf stage. The ratio was negatively correlated with carbon isotope discrimination, in accord with theory. This means that decrease in intercellular partial pressure of CO(2) accounted for an important part of the increase in W with increasing soil strength. Despite a lower CO(2) concentration in the leaves at high soil strength, assimilation rate per unit leaf area was enhanced. Greater ribulose 1,5-bisphosphate carboxylase activity confirmed that photosynthetic capacity was actually increased. This pattern of opposite variation of assimilation rate and of stomatal conductance is unusual. The ratio of plant carbon mass to leaf area increased markedly with increasing soil strength, mainly because of a greater investment of carbon into roots than into shoots. A strong negative correlation was found between this ratio and carbon isotope discrimination. For a given increase in discrimination, decrease in carbon mass per leaf area was proportionally larger than decrease in assimilation rate, so that relative growth rate was positively correlated to carbon isotope discrimination.",1
"Masle, J, Farquhar, G D",2
Interrelations between Carbon Dioxide and Ethylene on the Stimulation of Cocklebur Seed Germination.,0
"Interrelations between CO(2) and C(2)H(4) on promotion of seed germination were examined in more detail at 23 degrees C with presoaked upper seeds of Xanthium pennsylvanicum Wallr. The germination-promoting effect of C(2)H(4) decreased gradually as its application time was delayed during a soaking period, whereas CO(2) was most promotive in application at 5 days of soaking, then its effect declined. CO(2) and C(2)H(4) were additive in earlier soaking periods and synergistic in later periods. Such changes in germination behavior in response to CO(2) and/or C(2)H(4) during a soaking period were closely associated with growth responsiveness of the axial tissues, but not of the cotyledonary ones. Growth responsiveness of axial tissues to CO(2) or C(2)H(4) disappeared finally during a soaking period, but their extinct responsiveness to any one of these gases was almost fully restored in the simultaneous presence of the other. The extinct responsiveness to CO(2) was partially recovered by a preexposure to C(2)H(4). This suggests that in the later period of soaking, unlike the case in a very early period of soaking, the C(2)H(4)-sensitive phase for seed germination precedes the CO(2)-sensitive phase in which CO(2) potentiated axial growth. The restoration of CO(2) responsiveness in axial growth occurred not only after C(2)H(4) treatment but also after exposure to 8 or 33 degrees C or after KCN treatment. Thus, secondarily dormant Xanthium seeds could germinate in response to CO(2) alone, when they were previously exposed for shortterms not only to C(2)H(4) but also 8 degrees C, 33 degrees C, or KCN.",1
"Esashi, Y, Kawabe, K, Isuzugawa, K, Ishizawa, K",2
Separation of Chlorophylls c(1) and c(2) from Pigment Extracts of Pavlova gyrans by Reversed-Phase High Performance Liquid Chromatography.,0
Chlorophylls c(1) and c(2) have been separated from total pigment extracts of the alga Pavlova gyrans Butcher using a reversed-phase high-performance liquid chromatography system. Pigments were separated on a 5 micrometer C(18) column (25 centimeters x 4.6 millimeters) using a gradient of methanol-acetonitrile-water. Other photosynthetic pigments were also well resolved by the system used. The separation system described may replace current thin layer chromatography methods for qualitative and quantitative determination of chlorophyll c species.,1
"Fawley, M W",2
Translocation of radiolabeled indole-3-acetic acid and indole-3-acetyl-myo-inositol from kernel to shoot of Zea mays L.,0
"Either 5-[3H]indole-3-acetic acid (IAA) or 5-[3H]indole-3-acetyl-myo-inositol was applied to the endosperm of kernels of dark-grown Zea mays seedlings.  The distribution of total radioactivity, radiolabeled indole-3-acetic acid, and radiolabeled ester conjugated indole-3-acetic acid, in the shoots was then determined.  Differences were found in the distribution and chemical form of the radiolabeled indole-3-acetic acid in the shoot depending upon whether 5-[3H]indole-3-acetic acid or 5-[3H]indole-3-acetyl-myo-inositol was applied to the endosperm.  We demonstrated that indole-3-acetyl-myo-inositol applied to the endosperm provides both free and ester conjugated indole-3-acetic acid to the mesocotyl and coleoptile.  Free indole-3-acetic acid applied to the endosperm supplies some of the indole-3-acetic acid in the mesocotyl but essentially no indole-3-acetic acid to the coleoptile or primary leaves.  It is concluded that free IAA from the endosperm is not a source of IAA for the coleoptile.  Neither radioactive indole-3-acetyl-myo-inositol nor IAA accumulates in the tip of the coleoptile or the mesocotyl node and thus these studies do not explain how the coleoptile tip controls the amount of IAA in the shoot.",1
"Chisnell, J R, Bandurski, R S, Bandurski, R S",2
Physiological Site of Ethylene Effects on Carbon Dioxide Assimilation in Glycine max L. Merr.,0
"The physiological site of ethylene action on CO(2) assimilation was investigated in intact plants of Glycine max L., using a whole-plant, open exposure system equipped witha remotely operated single-leaf cuvette. The objective of the study was met by investigating in control and ethylene-treated plants the (a) synchrony in response of CO(2) assimilation, stomatal conductance to water vapor, and substomatal CO(2) partial pressure; (b) response of CO(2) assimilation as a function of a range of substomatal CO(2) partial pressures; and (c) response of CO(2) assimilation as a function of a range of photon flux densities. After exposure to 410 micromoles per cubic meter of ethylene for 2.0 hours, CO(2) assimilation and stomatal conductance declined in synchrony, while substomatal CO(2) partial pressure remained unchanged until exposure times equaled and exceeded 3.0 hours. Because incipient changes in CO(2) assimilation occurred without a change in the CO(2) partial pressure in the leaf interior, it is concluded that both stomatal physiology and the chloroplast's CO(2) assimilatory capacity were initial sites of ethylene action. After 3.5 hours the effect of ethylene on stomatal conductance and CO(2) assimilation exhibited saturation kinetics, and the effect was substantially more pronounced for stomatal conductance than for CO(2) assimilation. Based on the response of CO(2) assimilation to a range of substomatal CO(2) partial pressures, ethylene did not affect either the CO(2) compensation point or carboxylation efficiency at subsaturating CO(2) partial pressures. Above-ambient supplies of CO(2) did not alleviate the diminished rates of CO(2) assimilation. In partitioning the limitations imposed on CO(2) assimilation in control and ethylene-treated plants, the stomatal component accounted for only 16 and 4%, respectively. The response of CO(2) assimilation to a range of photon flux densities suggests that ethylene reduced apparent quantum yield by nearly 50%. Thus, the pronounced decline in net photosynthetic CO(2) assimilation in the presence of ethylene was due more to a loss in the mesophyll tissue's intrinsic capacity to assimilate CO(2) than to a reduction in stomatal conductance.",1
"Taylor, G E, Gunderson, C A",2
Dihydroxyacetone phosphate reductase in plants.,0
"Two forms of dihydroxyacetone phosphate reductase are present in spinach, soybean, pea, and mesophyll cells of corn leaves. An improved homogenizing medium was developed to measure this activity. The enzyme was detectable only after dialysis of the 35 to 70% saturated (NH(4))(2)SO(4) fraction and the two forms were separated by chromatography on either DEAE cellulose or Sephacryl S-200. About 80% of the reductase was one form in the chloroplast and the rest was a second form in the cytosol as determined by chromatography and by fractionation of subcellular organelles. The amount of activity detectable in the chloroplast fraction was 10.7 micromoles of dihydroxyacetone phosphate reductase per hour per milligram chlorophyll from spinach leaves and 4.9 from pea leaves. The chloroplast form eluted first from DEAE cellulose and, being smaller, it eluted second from Sephacryl S-200. Activity of the chloroplast form was stimulated 3- to 5-fold by the addition of 1 millimolar dithiothreitol or 50 microgram reduced Escherichia coli thioredoxin or 4 micrograms spinach thioredoxin to the assay mixture. This stimulation was not observed with monothiols. Activity of the cytosolic form was not affected by either reduced thioredoxin or dithiothreitol.",1
"Gee, R W, Byerrum, R U, Gerber, D W, Tolbert, N E",2
Do Stomata Respond to CO(2) Concentrations Other than Intercellular?,0
"Most studies on stomatal responses to CO(2) assume that guard cells respond only to intercellular CO(2) concentration and are insensitive to the CO(2) concentrations in the pore and outside the leaf. If stomata are sensitive to the CO(2) concentration at the surface of the leaf or in the stomatal pore, the stomatal response to intercellular CO(2) concentration will be incorrect for a ;normally' operating leaf (where ambient CO(2) concentration is a constant). In this study asymmetric CO(2) concentrations for the two surfaces of amphistomatous leaves were used to vary intercellular and leaf surface CO(2) concentrations independently in Xanthium strumarium L. and Helianthus annuus L. The response of stomata to intercellular CO(2) concentration when the concentration at the leaf surface was held constant was found to be the same as the response when the surface concentration was varied. In addition, stomata did not respond to changes in leaf surface CO(2) concentration when the intercellular concentration for that surface was held constant. It is concluded that stomata respond to intercellular CO(2) concentration and are insensitive to the CO(2) concentration at the surface of the leaf and in the stomatal pore.",1
"Mott, K A",2
Disruption of the Polar Auxin Transport System in Cotton Seedlings following Treatment with the Defoliant Thidiazuron.,0
"The effect of the defoliant thidiazuron (TDZ) on basipetal auxin transport in petiole segments isolated from cotton (Gossypium hirsutum L. cv LG102) seedlings was examined using the donor/receiver agar block technique. Treatment of intact seedlings with TDZ at concentrations of 1 micromolar or greater resulted in a dose-dependent inhibition of (14)C-IAA transport in petiole segments isolated 1 or 2 days after treatment. Using 100 micromolar TDZ, the inhibition was detectable 19 hours after treatment and was complete by 27 hours. Both leaves and petiole segments exhibited a marked increase in ethylene production following treatment with TDZ at concentrations of 0.1 micromolar or greater. The involvement of ethylene in this TDZ response was evaluated by examining the effects of two inhibitors of ethylene action: silver thiosulfate, 2,5-norbornadiene. One day after treatment, both inhibitors effectively antagonized the TDZ-induced inhibition of auxin transport. Two days after TDZ treatment both inhibitors were ineffective. The decrease in IAA transport in TDZ treated tissues was associated with increased metabolism of IAA. The transport of (14)C-2,4-dichlorophenoxyacetic acid was also inhibited by TDZ treatment. This inhibition was not accompanied by increased metabolism. Incorporation of TDZ into the receiver blocks had no effect on auxin transport. The ability of the phytotropin N-1-naphthylphthalamic acid to stimulate IAA uptake from a bathing medium was reduced in TDZ-treated tissues. This reduction is thought to reflect a decline in the auxin efflux system following TDZ treatment.",1
"Suttle, J C",2
Light-Induced Proton Release by the Cyanobacterium Anabaena variabilis: Dependence on CO(2) and Na.,0
"Light-induced acidification by the cyanobacterium Anabaena variabilis is biphasic (a fast phase I and slow phase II) and shown to be sodium-dependent with an optimum concentration of 40 to 60 millimolar Na(+). Cells grown under low CO(2) concentrations at pH 9 (i.e. mainly HCO(3) (-) present in the medium) exhibited the slow phase II of proton efflux only, while cells grown under low CO(2) concentrations at pH 6.3 (i.e. CO(2) and HCO(3) (-) present) exhibited both phases. Light-induced proton release of phase I was dependent on inorganic carbon available in the bathing medium with an apparent K(m) for CO(2) of 20 to 70 micromolar. As was concluded from the CO(2) dependence of acidification measured at different pH of the bathing medium, bicarbonate inhibited phase-I acidification noncompetetively. Acidification was inhibited by acetazolamide, an inhibitor of carbonic anhydrase. Apparently, acidification of phase I is due to a light-dependent uptake of CO(2) being converted to HCO(3) (-) by a carbonic anhydrase-like function of the HCO(3) (-)-transport system (M Volokita, D Zenvirth, A Kaplan, L Reinhold 1984 Plant Physiol 76: 599-602) before or during entering the cell, thus releasing one proton per CO(2) converted to HCO(3) (-).",1
"Scherer, S, Riege, H, Böger, P",2
Translocation of Sulfate in Soybean (Glycine max L. Merr).,0
"Sulfate translocation in soybean (Glycine max L. Merr) was investigated. More than 90% of the sulfate entering the shoot system was recoverable in one or two developing trifoliate leaves. In young plants, the first trifoliate leaf contained between 10 to 20 times as much sulfate as the primary leaves, even though both types of leaf had similar rates of transpiration and photosynthesis. We conclude that most of the sulfate entering mature leaves is rapidly loaded into the phloem and translocated to sinks elsewhere in the plant. This loading was inhibited by carbonylcyanide m-chlorophenylhydrazone and selenate. At sulfate concentrations below 0.1 millimolar, more than 95% of the sulfate entering primary leaves was exported. At higher concentrations the rate of export increased but so did the amount of sulfate remaining in the leaves. Removal of the first trifoliate leaf increased two-fold the transport of sulfate to the apex, indicating that these are competing sinks for sulfate translocated from the primary leaves. The small amount of sulfate transported into the mesophyll cells of primary leaves is a result of feedback regulation by the intracellular sulfate pool, not a consequence of their metabolic inactivity. For example, treatment of plants with 2 millimolar aminotriazole caused a 700 nanomoles per gram fresh weight increase in the glutathione content of primary leaves, but had no effect on sulfate aquisition.",1
"Smith, I K, Lang, A L",2