bluuebunny/crossref_metadata_2025_split huggingface dataset:
A randomized trial comparing phosphorylcholine‐coated stenting with balloon angioplasty as well as abciximab with placebo for restenosis reduction in small coronary arteries
Authors: Hausleiter J. , Kastrati A. , Mehilli J. , Schühlen H. , Pache J. , Dotzer F. , Glatthor C. , Siebert S. , Dirschinger J. , Schömig A. ,   for the ISAR‐SMART‐2 investigators
Published: October 2004

Abstract.Objective.  The objective of this randomized trial was to assess the antirestenotic effects of phosphorylcholine (PC)‐coated stents as well as of abciximab in small coronary arteries when compared with percutaneous transluminal coronary angioplasty (PTCA) and placebo respectively.Background.  Stent coating with PC has been shown to reduce protein absorption and platelet activation which may reduce the risk of restenosis. Furthermore, on the basis of nondedicated studies abciximab is believed to reduce the risk of restenosis after coronary interventions.Methods.  A total of 502 patients with lesions situated in small coronary arteries (vessel diameter ≤2.5 mm) were randomly assigned to be treated with either PC‐coated stents (n = 253) or PTCA (n = 249) and with either abciximab (n = 251) or placebo (n = 251) with the use of a 2 × 2 factorial design. All patients were pretreated with 600 mg clopidogrel. The primary end‐point was the incidence of angiographic restenosis (≥50% diameter stenosis) at follow‐up; death or myocardial infarction, and target vessel revascularization (TVR), were assessed as secondary end‐points.Results.  Angiographic restenosis did not differ between patients treated with PC‐coated stents or with PTCA (39.0% vs. 34.2%; P = 0.30) and between patients receiving abciximab or placebo (39.3% vs. 34.3%; P = 0.29). Similarly, the need for TVR at 1‐year follow‐up did not differ between patients receiving PC‐coated stents or PTCA (20.2% vs. 20.5%; P = 0.98) as well as between patients treated with abciximab or placebo (18.7% vs. 21.9%; P = 0.44).Conclusions.  PC‐coated stents and abciximab failed to reduce the incidence of angiographic restenosis after percutaneous coronary intervention of small coronary arteries. These data strengthen the belief that future studies on prevention of restenosis in small coronary arteries should focus on drug‐eluting stents.
Discordant penetrance of the trait for familial amyloidotic polyneuropathy in two pairs of monozygotic twins
Authors: Holmgren G. , Wikström L. , Lundgren H.‐E. , Suhr O. B. 
Published: October 2004

Abstract.Background.  Familial amyloidotic polyneuropathy (FAP) is caused by mutated transthyretin in which valine at position 30 is substituted by methionine (ATTR Val30Met). FAP is inherited as an autosomal dominant trait with variable penetrance.Cases.  Two pairs of DNA confirmed monozygotic twin brothers, 63 and 37 years of age respectively, who are heterozygous for the ATTR Val30Met gene, have been identified in Sweden. In the first twin pair (A), the onset of typical FAP symptoms occurred at the age of 48 for twin A1, whilst his twin brother (A2) is still free from FAP symptoms 13 years later.In the second pair of twins (B), the onset of polyneuropathy occurred at the age of 34 for the proband (B1), whilst his brother (B2) is healthy 3 years after the onset of his brother's disease.Discussion.  In the following, a detailed description of the clinical presentation of the Swedish twin pairs is provided together with a discussion of possible environmental factors initiating the onset of the disease.
Hormone replacement therapy and cardiovascular disease: increased risks of venous thromboembolism and stroke, and no protection from coronary heart disease
Authors: Lowe G. D. O. 
Published: October 2004

Abstract.Hormone replacement therapy (HRT) was increasingly promoted over the last 40 years to improve quality of life, and to reduce the risks of osteoporotic fractures and coronary heart disease (CHD). In recent years, observational studies, randomized trials and systematic reviews of such trials have shown that HRT does not reduce, but actually increases cardiovascular risk. HRT increases the relative risks of venous thromboembolism (twofold), and of fatal or disabling stroke (by 50%); whilst increasing the early risk of myocardial infarction and having no protective effect against CHD on longer term use. Possible mechanisms for these increased cardiovascular risks include down‐regulation of several inhibitory pathways of blood coagulation, resulting in increased coagulation activation, which promotes venous and arterial thrombosis. The implications for prescription are discussed, as are lessons for future evaluation of health care interventions.
The rate of fertilization in male mating tactics of the polygynous grey seal
Authors: LIDGARD D. C. , BONESS D. J. , BOWEN W. D. , McMILLAN J. I. , FLEISCHER R. C. 
Published: October 2004

AbstractStudies using molecular markers have shown that some grey seal males may be gaining success through exhibiting alternative mating tactics. We estimated the probability of fertilization success of grey seal males exhibiting the primary tactic of female defence and one alternative tactic of mating with departing females on Sable Island, Nova Scotia, Canada, during the breeding seasons of 1997–2002. Although the fertilization rate of the primary tactic (27–43%) was greater than that of the alternative tactic (10–12%), these low rates indicate the potential fitness value of alternative mating tactics in this size‐dimorphic pinniped species.
Geological barriers and restricted gene flow in the holarctic skipperHesperia comma(Hesperiidae)
Authors: FORISTER M. L. , FORDYCE J. A. , SHAPIRO A. M. 
Published: October 2004

AbstractPatterns of genetic variation within a species may be a consequence of historical factors, such as past fragmentation, as well as current barriers to gene flow. Using sequence data from the mitochondrial cytochrome oxidase subunit II region (COII) and the nuclear genewingless, we conducted a phylogeographical study of the holarctic skipperHesperia commato elucidate patterns of genetic diversity and to infer historical and contemporary processes maintaining genetic variation. One hundred and fifty‐one individuals were sampled from throughout North America and Eurasia, focusing on California and adjacent regions in the western United States where morphological diversity is highest compared to the rest of the range. Analyses of sequence data obtained from both genes revealed a well‐supported division between the Old and New World. Within western North America,winglessshows little geographical structure, while a hierarchical analysis of genetic diversity of COII sequences indicates three major clades: a western clade in Oregon and Northern California, an eastern clade including the Great Basin, Rocky Mountains and British Columbia, and a third clade in southern California. The Sierra Nevada and the Transverse Ranges appear to be the major barriers to gene flow forH. commain the western United States. Relatively reduced haplotype diversity in Eurasia compared to North America suggests that populations on the two continents have been affected by different historical processes.
Bacterial cell division and the septal ring
Authors: Weiss David S. 
Published: October 2004

SummaryCell division in bacteria is mediated by the septal ring, a collection of about a dozen (known) proteins that localize to the division site, where they direct assembly of the division septum. The foundation of the septal ring is a polymer of the tubulin‐like protein FtsZ. Recently, experiments using fluorescence recovery after photobleaching have revealed that the Z ring is extremely dynamic. FtsZ subunits exchange in and out of the ring on a time scale of seconds even while the overall morphology of the ring appears static. These findings, together with in vitro studies of purified FtsZ, suggest that the rate‐limiting step in turnover of FtsZ polymers is GTP hydrolysis. Another component of the septal ring, FtsK, is involved in coordinating chromosome segregation with cell division. Recent studies have revealed that FtsK is a DNA translocase that facilitates decatenation of sister chromosomes by TopIV and resolution of chromosome dimers by the XerCD recombinase. Finally, two murein hydrolases, AmiC and EnvC, have been shown to localize to the septal ring of Escherichia coli, where they play an important role in separation of daughter cells.
Why is transcription coupled to translation in bacteria?
Authors: Gowrishankar J. , Harinarayanan R. 
Published: October 2004

SummaryActive mechanisms exist to prevent transcription that is uncoupled from translation in the protein‐coding genes of bacteria, as exemplified by the phenomenon of nonsense polarity. Bacterial transcription–translation coupling may be viewed as one among several co‐transcriptional processes, including those for mRNA processing and export in the eukaryotes, that operate in the various life forms to render the nascent transcript unavailable for formation of otherwise deleterious R‐loops in the genome.
SsaM and SpiC interact and regulate secretion of Salmonella Pathogenicity Island 2 type III secretion system effectors and translocators
Authors: Yu Xiu‐Jun , Liu Mei , Holden David W. 
Published: October 2004

SummaryThe type III secretion system (TTSS) encoded by Salmonella Pathogenicity Island 2 (SPI‐2) is required for systemic infection and intracellular replication of Salmonella enterica serovar Typhimurium. The SPI‐2 TTSS is activated after internalization of bacteria by host cells, and translocates effector proteins into and across the vacuolar membrane, where they interfere with several host cell functions. Here, we investigated the function of SsaM, a small protein encoded within SPI‐2. An ssaM deletion mutant had virulence and intracellular replication defects comparable to those of a SPI‐2 TTSS null mutant. Although the ssaM mutant was able to secrete the effector protein SseJ in vitro, it failed to translocate SseJ into host cells, and to secrete the translocon proteins SseB, SseC and SseD in vitro. This phenotype is similar to that of a strain carrying a mutation in the SPI‐2 gene spiC, whose product is reported to be an effector involved in trafficking of the Salmonella vacuole in macrophages. Both ssaM and spiC mutants were found to oversecrete the SPI‐2 effector proteins SseJ and PipB in vitro. Fractionation assays and immunofluorescence microscopy were used to investigate the localization of SsaM and SpiC in macrophages. No evidence for translocation of these proteins was obtained. The similar phenotypes of the ssaM and spiC mutants suggested that they might be involved in the same function. Pull‐down and co‐immune precipitation experiments showed that SpiC and SsaM interact within the bacterial cell. We propose that a complex involving SsaM and SpiC distinguishes between translocators and effector proteins, and controls their ordered secretion through the SPI‐2 TTSS.
Regulation of FlbD activity by flagellum assembly is accomplished through direct interaction with the trans‐acting factor, FliX
Authors: Muir Rachel E. , Gober James W. 
Published: October 2004

SummaryThe temporal and spatial transcription of late flagellar genes in Caulobacter crescentus is regulated by the σ54 transcriptional activator, FlbD. One requirement for FlbD activity is the assembly of a structure encoded by early, class II flagellar genes. In this report, we show that the trans‐acting factor FliX predominantly functions as a negative regulator of FlbD activity in the absence of the class II‐encoded flagellar structure. In contrast, a mutant FliX that bypasses the transcriptional requirement for early flagellar assembly is incapable of repressing FlbD in a class II flagellar mutant. Expression of this mutant allele, fliX1, does not alter the temporal pattern of FlbD‐dependent transcription. Remarkably, this mutation confers the correct cell cycle timing of hook operon transcription in a strain that cannot assemble the flagellum, indicating that the progression of flagellar assembly is a minor influence on temporal gene expression. Using a two‐hybrid assay, we present evidence that FliX regulates FlbD through a direct interaction, a novel mechanism for this class of σ54 transcriptional activator. Furthermore, increasing the cellular levels of FliX results in an increase in the concentration of FlbD, and a corresponding increase in FlbD‐activated transcription, suggesting that FliX and FlbD form a stable complex in Caulobacter. FliX and FlbD homologues are present in several polar‐flagellated bacteria, indicating that these proteins constitute an evolutionarily conserved regulatory pair in organisms where flagellar biogenesis is likely to be under control of the cell division cycle.
Modulation of the mtrCDE‐encoded efflux pump gene complex of Neisseria meningitidis due to a Correia element insertion sequence
Authors: Rouquette‐Loughlin Corinne E. , Balthazar Jacqueline T. , Hill Stuart A. , Shafer William M. 
Published: October 2004

SummaryThe mtr (multiple transferable resistance) gene complex in Neisseria gonorrhoeae encodes an energy‐dependent efflux pump system that is responsible for export of anti‐bacterial hydrophobic agents. Expression of the mtrCDE operon in gonococci is negatively regulated by the MtrR protein. Hydrophobic agent resistance mediated by the mtr system is also inducible, which results from an AraC‐like protein termed MtrA. In this work, we identified and characterized a pump similar to the gonococcal mtr system in various strains of Neisseria meningitidis. Unlike the situation with gonococci, the mtr system in meningococci is not subject to the MtrR or MtrA regulatory schemes. An analysis of the promoter region of the mtrCDE operon in a panel of meningococcal strains revealed the presence of one or two classes of insertion sequence elements. A 155–159 bp insertion sequence element known as the Correia element, previously identified elsewhere in the gonococcal and meningococcal genomes, was present in the mtrCDE promoter region of all meningococcal strains tested. In addition to the Correia element, a minority of strains had a tandemly linked, intact copy of IS1301. As described previously, a binding site for the integration host factor (IHF) was present at the centre of the Correia element upstream of mtrCDE genes. IHF was found to bind specifically to this site and deletion of the IHF binding site enhanced mtrC transcription. We also identified a post‐transcriptional regulation of the mtrCDE transcript by cleavage in the inverted repeat of the Correia element, as previously described by Mazzone et al. [Gene278: 211–222 (2001)] and De Gregorio et al. [Biochim Biophys Acta 1576: 39–44 (2002)]for other Correia element. We conclude that the mtr efflux system in meningococci is subject to transcriptional regulation by IHF and post‐transcriptional regulation by cleavage in the inverted repeat of the Correia element.
A proline tRNA(CGG) gene encompassing the attachment site of temperate phage 16‐3 is functional and convertible to suppressor tRNA
Authors: Blaha Béla , Semsey Szabolcs , Ferenczi Szilamér , Csiszovszki Zsolt , Papp Péter P. , Orosz László 
Published: October 2004

SummarySeveral temperate bacteriophage utilize chromosomal sequences encoding putative tRNA genes for phage attachment. However, whether these sequences belong to genes which are functional as tRNA is generally not known. In this article, we demonstrate that the attachment site of temperate phage 16‐3 (attB) nests within an active proline tRNA gene in Rhizobium meliloti 41. A loss‐of‐function mutation in this tRNA gene leads to significant delay in switching from lag to exponential growth phase. We converted the putative Rhizobium gene to an active amber suppressor gene which suppressed amber mutant alleles of genes of 16‐3 phage and of Escherichia coli origin in R. meliloti 41 and in Agrobacterium tumefaciens GV2260. Upon lysogenization of R. meliloti by phage 16‐3, the proline tRNA gene retained its structural and functional integrity. Aspects of the co‐evolution of a temperate phage and its bacterium host is discussed. The side product of this work, i.e. construction of amber suppressor tRNA genes in Rhizobium and Agrobacterium, for the first time widens the options of genetic study.
The role of H‐NS in silencing F transfer gene expression during entry into stationary phase
Authors: Will William R. , Lu Jun , Frost Laura S. 
Published: October 2004

SummaryThe conjugative ability of the F plasmid of Escherichia coli is highly growth phase dependent, with plasmid transfer efficiency dropping rapidly as donor cells progress through the growth cycle towards stationary phase. Transfer is dependent on the expression of the plasmid transfer (tra) genes, which are controlled by three plasmid‐encoded regulatory proteins: TraJ, TraY and TraM. Here, we show that the nucleoid‐associated host protein, H‐NS, acts to repress the expression of traM and traJ as cells enter stationary phase, thereby decreasing mating ability to barely detectable levels. Sequence analysis identified regions of predicted intrinsic curvature, to which H‐NS preferentially binds, at the promoters of both traM and traJ. H‐NS binding at these regions was then confirmed by electrophoretic mobility shift and DNase I protection footprinting assays. Immunoblot assays displayed a significant increase in TraJ and TraM levels in an hns mutant strain. These findings were further supported by Northern and primer extension analyses which showed that whereas both genes were only expressed in early exponential phase in wild‐type cells, hns mutant cells exhibited drastic derepression throughout the growth cycle. Transcriptional fusion studies of the individual promoters demonstrated that H‐NS‐mediated repression was observed when the promoters of both traM and traJ were present in cis to each other. This suggests that H‐NS may bind to an extended region of the F plasmid, acting as a regional silencer of promoters for traJ and traM.
Characterization of an ABCA‐like transporter involved in vesicular trafficking in the protozoan parasite Trypanosoma cruzi
Authors: Torres Cristina , Pérez‐Victoria F. Javier , Parodi‐Talice Adriana , Castanys Santiago , Gamarro Francisco 
Published: October 2004

SummaryProtozoan parasites are responsible of important healthy problems, among others malaria, leishmaniasis and trypanosomiasis. The present work reports the characterization of the first mammalian ATP‐binding cassette transporter, subfamily A (ABCA)‐like in Trypanosoma cruzi. TcABC1 is a single copy gene differentially expressed along the life cycle of the parasite, being absent in its infective form. TcABC1 localizes to the plasma membrane, flagellar pocket and intracellular vesicles. Functional studies of TcABC1 in transfected parasites suggest that the protein is implicated in intracellular trafficking, as determined by the analysis of endocytosis and exocytosis events. The accumulation of the endocytic markers FM4‐64 and NBD‐SM is increased in transfected parasites. Similarly, ectophosphatase and ectoATPase activities are increased in TcABC1 overproducers. Indeed, transmission electronic microscopy analysis showed a higher number of intracellular vesicles in TcABC1 transfectants. Taken together, these results suggest that the protein is involved in the endocytic and exocytic pathways of T. cruzi.
Structure and assembly of the pseudopilin PulG
Authors: Köhler Rolf , Schäfer Karsten , Müller Shirley , Vignon Guillaume , Diederichs Kay , Philippsen Ansgar , Ringler Philippe , Pugsley Anthony P. , Engel Andreas , Welte Wolfram 
Published: October 2004

SummaryThe pseudopilin PulG is one of several essential components of the type II pullulanase secretion machinery (the Pul secreton) of the Gram‐negative bacterium Klebsiella oxytoca. The sequence of the N‐terminal 25 amino acids of the PulG precursor is hydrophobic and very similar to the corresponding region of type IV pilins. The structure of a truncated PulG (lacking the homologous region), as determined by X‐ray crystallography, was found to include part of the long N‐terminal α‐helix and the four internal anti‐parallel β‐strands that characterize type IV pilins, but PulG lacks the highly variable loop region with a disulphide bond that is found in the latter. When overproduced, PulG forms flexible pili whose structural features, as visualized by electron microscopy, are similar to those of bacterial type IV pili. The average helical repeat comprises 17 PulG subunits and four helical turns. Electron microscopy and molecular modelling show that PulG probably assembles into left‐handed helical pili with the long N‐terminal α‐helix tightly packed in the centre of the pilus. As in the type IV pilins, the hydrophobic N‐terminal part of the PulG α‐helix is necessary for its assembly. Subtle sequence variations within this highly conserved segment seem to determine whether or not a type IV pilin can be assembled into pili by the Pul secreton.
Intestinal barrier dysfunction by enteropathogenic Escherichia coli is mediated by two effector molecules and a bacterial surface protein
Authors: Dean Paul , Kenny Brendan 
Published: October 2004

SummaryThe human intestinal pathogen, enteropathogenic Escherichia coli (EPEC), causes diarrhoeal disease by a mechanism that is dependent on the injection of effector proteins into the host cell. One effector, EspF, is reported to be required for EPEC to disrupt tight junction integrity of intestinal cells and increase the paracellular movement of molecules, which is likely to  contribute  to  diarrhoea.  Here,  we  show  that  not one but three EPEC‐encoded factors play important roles in this process. Thus, the Map (Mitochondria‐associated protein) effector is shown to: (i) be as essential as EspF for disrupting intestinal barrier function, (ii) be able to function independently of EspF, (iii) alter tight junction structure and (iv) mediate these effects in the absence of mitochondrial targeting. Additionally, the outer membrane protein Intimin is shown to be crucial for EspF and Map to disrupt the intestinal barrier function. This function of Intimin is completely independent of its interaction with its known receptor Tir, revealing a physiologically relevant requirement for Intimin interaction with alternative receptor(s). This work demonstrates that EPEC uses multiple multifunctional proteins to elicit specific responses in intestinal cells and that EPEC can control the activity of its injected effector molecules from its extracellular location.