bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiological and metabolic actions of mycophenolate mofetil on cultured newborn rat cardiomyocytes in normoxia and in simulated ischemia
Authors: Bès Sandrine , Tatou Etienne , Vandroux David , Tissier Cindy , Rochette Luc , Athias Pierre 
Published: May 2004

AbstractMycophenolate mofetil (MMF) is a new immunosuppressive drug used to reduce acute rejection after heart transplantation. As with other immunosuppressive drugs, MMF therapy is associated with several adverse effects. However, the direct effects of MMF on myocardial tissue has not been yet evaluated. The aim of the work was thus to evaluate the effects of MMF on isolated cardiomyocytes (CM) in normal conditions and in an in vitro model of simulated ischemia (SI; substrate‐free hypoxia) and reperfusion (R; reoxygenation). Myocyte‐enriched cultures were prepared from newborn rat heart ventricles. The transmembrane potentials were recorded using conventional microelectrodes and the cell contractions were monitored with a photoelectric device. In basal conditions, MMF (10−6and 10−5 m) exerted no significant effects on the survival and on the electrical and contractile activities of CM in culture, even during long‐term exposure (up to 48 h). SI per se led to a gradual decrease and then an abortion of the spontaneous automaticity and electromechanical activity of CM. Pretreating CM with either 10−6or 10−5 mMMF was able to reduce the SI‐induced cell dysfunctions. The presence of MMF at these concentrations did not hamper the post‐SI functional recovery of CM during reoxygenation. At 10−5 m, MMF applied during reoxygenation only permitted a better recovery of CM. However, the mitochondrial function after reoxygenation, as assessed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5 diphenyl‐tetrazolium bromide (MTT) test, was not significantly influenced by the addition of MMF before as well as after ischemia. Conversely, MMF was able to reduce in this model the postischemic rise in xanthine and hypoxanthine. These data from CM‐enriched model show that MMF: (i) had no cytotoxic effect, (ii) displayed a cytoprotective effect during SI, and (iii) exerted its beneficial effect at least partly through the decrease in the xanthine oxidase‐dependent free radical production.
Level of evidence and therapeutic evaluation: need for more thoughts
Authors: Bossard Nadine , Boissel François‐Henri , Boissel Jean‐Pierre 
Published: May 2004

AbstractThe practice of evidence‐based medicine requires a tool to assess and discriminate available data based on objective grounds, thus facilitating access to reliable information. The level of evidence, conceptually and practically embedded in scientific activity, allows comparing the results from multiple studies testing an identical hypothesis along the lines of at least two dimensions. The first dimension deals with the design of the study, i.e. the extent to which bias is avoided or managed, the second with the quality of incorporated data. A third dimension specific to therapeutic evaluation focuses on the clinical relevance of the tested hypothesis. The concern of the final user of the information is thus put to the fore. Indeed, a general practitioner will be interested in the benefit for its patients whereas the concern of a biologist might significantly diverge from the former matter. The bulk of existing scales of level of evidence concentrate on methodology. Some may include the second dimension but none embrace the three of them. Seldom considered are matters regarding reproducibility and procedure. This is all the more unfortunate as reproducibility is a cornerstone of scientific progress. Moreover, scales used for overviews fail to take into account the methodology designed to produce the synthesis. Inconsistent existing scales prevent the emergence of a generally agreed standard. Therefore, there is a need to further specify the concept of level of evidence in therapy evaluation and design scales encompassing the three above‐mentioned dimensions: methodology of experiment, quality of data, and clinical relevance of the primary criterion.
Polyphenolic compounds from Cognac induce vasorelaxation in vitro and decrease post‐ischaemic cardiac infarction after an oral administration
Authors: Ralay Ranaivo H. , Diebolt M. , Schott C. , Andriantsitohaina R. 
Published: May 2004

AbstractThe effects of Cognac polyphenolic compounds (CPC) on aorta and isolated heart, the consequences of oral administration on haemodynamic parameters, vascular reactivity and cardiac recovery after ischaemia were investigated. CPC induced an endothelium‐dependent vasorelaxation on rat‐isolated aorta. This effect was prevented by the nitric oxide (NO) synthase inhibitor, NG‐nitro‐l‐arginine‐methyl ester, but not by the cyclo‐oxygenase inhibitor, indomethacin, suggesting the implication of NO pathway. On isolated rat hearts, CPC induced positive inotropic, chronotropic, and lusitropic effect at 10−4–10−2 g/L while at 10−1 g/L, it had negative lusitropic effect and other parameters returned to baseline values. Oral administration of 40 mg/kg of CPC for 2 weeks did not modify systolic blood pressure and heart rate of rats throughout the treatment. CPC treatment did not affect ex vivo response of isolated thoracic aorta either to the contractile agent noradrenaline or to the endothelial‐relaxant agent, acetylcholine. Isolated hearts from treated rats were submitted to 30‐min global ischaemia followed by 120 min of reperfusion. Post‐ischaemic recovery of functional cardiac parameters was not modified by treatment with CPC. Infarct size measured after the reperfusion in heart from CPC‐treated rats was significantly decreased in comparison with hearts from control group. We conclude that in vitro, CPC had NO‐dependent vasorelaxant effects and stimulated cardiac function. Oral treatment with CPC appeared to have no impact in vivo on blood pressure, heart rate of the rats or on cardiac contractility ex vivo; however, it could decrease the infarct size after an ischaemia–reperfusion.
Endothelium‐dependent contractions to acetylcholine, ATP and the calcium ionophore A 23187 in aortas from spontaneously hypertensive and normotensive rats
Authors: Yang Di , Gluais Pascale , Zhang Ji Nan , Vanhoutte Paul M. , Félétou Michel 
Published: May 2004

AbstractThe present study was designed to determine whether or not an increase in endothelial intracellular concentration of calcium ([Ca2+]i) evokes endothelium‐dependent contractions in the aorta from normotensive Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR). Acetylcholine, adenosine triphosphate (ATP) and the calcium ionophore, A 23187, produced endothelium‐dependent relaxations in isolated aortic rings of both WKY and SHR. These relaxations in response to the three agonists were significantly smaller in the SHR when compared with the WKY. Endothelium‐dependent contractions to acetylcholine, ATP and A 23187 were observed only in the aorta isolated from the SHR. In the presence of NG‐nitro‐L‐arginine, an NO synthase inhibitor, the endothelium‐dependent contractions in response to acetylcholine, ATP and A 23187 were potentiated significantly in the aorta SHR and were unmasked in that of WKY. However, the contractions were still significantly greater in SHR than in WKY. These contractions were abolished by indomethacin and valeryl salicylate (two cyclo‐oxygenase inhibitors) as well as by S 18886 (a TP‐receptor antagonist), indicating that the endothelium‐dependent contraction produced by the three agonists share the same characteristics. The results of the present study indicate that the release/generation of endothelium‐derived contracting factor, requires an increase in endothelial [Ca2+]i.
ERRATUM
Authors: Yang J. Q. , Morin S. , Verstuyft C. , Fan L. A. , Zhang Y. , Xu ChP. , Barbu V. , Funck‐Brentano C. , Jaillon P. , Becquemont L. 
Published: May 2004

FCP 17:3 (2003); pp. 373–376.The name of one of the contributing authors to this paper was omitted from the list of authors that appeared on page 373. The correct list of authors and affiliations are printed below:
Differential Gene Expression in Response to Hydrogen Peroxide and the Putative PerR Regulon ofSynechocystissp. Strain PCC 6803
Authors: Li Hong , Singh Abhay K. , McIntyre Lauren M. , Sherman Louis A. 
Published: May 2004

ABSTRACTWe utilized a full genome cDNA microarray to identify the genes that comprise the peroxide stimulon in the cyanobacteriumSynechocystissp. strain PCC 6803. We determined that a gene (slr1738) encoding a protein similar to PerR inBacillus subtiliswas induced by peroxide. We constructed a PerR knockout strain and used it to help identify components of the PerR regulon, and we found that the regulatory properties were consistent with the hypothesis that PerR functions as a repressor. This effort was guided by finding putative PerR boxes in positions upstream of specific genes and by careful statistical analysis. PerR and sll1621 (ahpC), which codes for a peroxiredoxin, share a divergent promoter that is regulated by PerR. We found thatisiA, encoding a Chl protein that is induced under low-iron conditions, was strongly induced by a short-term peroxide stress. Other genes that were strongly induced by peroxide includedsigD,sigB, and genes encoding peroxiredoxins and Dsb-like proteins that have not been studied yet in this strain. A gene (slr1894) that encoded a protein similar to MrgA inB. subtiliswas upregulated by peroxide, and a strain containing anmrgAknockout mutation was highly sensitive to peroxide. A number of genes were downregulated, including key genes in the chlorophyll biosynthesis pathway and numerous regulatory genes, including those encoding histidine kinases. We used PerR mutants and a thioredoxin mutant (TrxA1) to study differential expression in response to peroxide and determined that neither PerR nor TrxA1 is essential for the peroxide protective response.
Interactions between the Nitrogen Signal Transduction Protein PII and
N
-Acetyl Glutamate Kinase in Organisms That Perform Oxygenic Photosynthesis
Authors: Burillo Sergio , Luque Ignacio , Fuentes Inmaculada , Contreras Asunción 
Published: May 2004

ABSTRACT

PII, one of the most conserved signal transduction proteins, is believed to be a key player in the coordination of nitrogen assimilation and carbon metabolism in bacteria, archaea, and plants. However, the identity of PII receptors remains elusive, particularly in photosynthetic organisms. Here we used yeast two-hybrid approaches to identify new PII receptors and to explore the extent of conservation of PII signaling mechanisms between eubacteria and photosynthetic eukaryotes. Screening of
Synechococcus
sp. strain PCC 7942 libraries with PII as bait resulted in identification of
N
-acetyl glutamate kinase (NAGK), a key enzyme in the biosynthesis of arginine. The integrity of Ser49, a residue conserved in PII proteins from organisms that perform oxygenic photosynthesis, appears to be essential for NAGK binding. The effect of
glnB
mutations on NAGK activity is consistent with positive regulation of NAGK by PII. Phylogenetic and yeast two-hybrid analyses strongly suggest that there was conservation of the NAGK-PII regulatory interaction in the evolution of cyanobacteria and chloroplasts, providing insight into the function of eukaryotic PII-like proteins.
The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence
Authors: Christiansen Janne K. , Larsen Marianne H. , Ingmer Hanne , Søgaard-Andersen Lotte , Kallipolitis Birgitte H. 
Published: May 2004

ABSTRACTIn gram-negative bacteria, the RNA-binding protein Hfq has emerged as an important regulatory factor in a variety of physiological processes, including stress resistance and virulence. InEscherichia coli, Hfq modulates the stability or the translation of mRNAs and interacts with numerous small regulatory RNAs. Here, we studied the role of Hfq in the stress tolerance and virulence of the gram-positive food-borne human pathogenListeria monocytogenes. We present evidence that Hfq is involved in the ability ofL. monocytogenesto tolerate osmotic and ethanol stress and contributes to long-term survival under amino acid-limiting conditions. However, Hfq is not required for resistance to acid and oxidative stress. Transcription ofhfqis induced under various stress conditions, including osmotic and ethanol stress and at the entry into the stationary growth phase, thus supporting the view that Hfq is important for the growth and survival ofL. monocytogenesin harsh environments. The stress-inducible transcription ofhfqdepends on the alternative sigma factor σB, which controls the expression of numerous stress- and virulence-associated genes inL. monocytogenes.Infection studies showed that Hfq contributes to pathogenesis in mice, yet plays no role in the infection of cultured cell lines. This study provides, for the first time, information on the role of Hfq in the stress tolerance and virulence of a gram-positive pathogen.
Stress Response Gene Regulation in
Chlamydia
Is Dependent on HrcA-CIRCE Interactions
Authors: Wilson Adam C. , Tan Ming 
Published: May 2004

ABSTRACT

HrcA is a transcriptional repressor that regulates stress response genes in many bacteria by binding to the CIRCE operator. We have previously shown that HrcA regulates the promoter for the
dnaK
heat shock operon in
Chlamydia
. Here we demonstrate that HrcA represses a second heat shock promoter that controls the expression of
groES
and
groEL
, two other major chlamydial heat shock genes. The CIRCE element of
C. trachomatis groEL
is the most divergent of known bacterial CIRCE elements, and HrcA had a decreased ability to bind to this nonconsensus operator and repress transcription. We demonstrate that the CIRCE element is necessary and sufficient for transcriptional regulation by chlamydial HrcA and that the inverted repeats of CIRCE are the binding sites for HrcA. Addition of a CIRCE element upstream of a non-heat-shock promoter allowed this promoter to be repressed by HrcA, showing in principle that a chlamydial promoter can be genetically modified to be inducible. These results demonstrate that HrcA is the regulator of the major chlamydial heat shock operons, and we infer that the mechanism of the heat shock response in
Chlamydia
is derepression. However, derepression is likely to involve more than a direct effect of increased temperature as we found that HrcA binding to CIRCE and HrcA-mediated repression were not altered at temperatures that induce the heat shock response.
A Cambialistic Superoxide Dismutase in the Thermophilic Photosynthetic Bacterium
Chloroflexus aurantiacus
Authors: Lancaster Vanessa L. , LoBrutto Russell , Selvaraj Fabiyola M. , Blankenship Robert E. 
Published: May 2004

ABSTRACT

Superoxide dismutase from the thermophilic anoxygenic photosynthetic bacterium
Chloroflexus aurantiacus
was cloned, purified, and characterized. This protein is in the manganese- and iron-containing family of superoxide dismutases and is able to use both manganese and iron catalytically. This appears to be the only soluble superoxide dismutase in
C. aurantiacus
. Iron and manganese cofactors were identified by using electron paramagnetic resonance spectroscopy and were quantified by atomic absorption spectroscopy. By metal enrichment of growth media and by performing metal fidelity studies, the enzyme was found to be most efficient with manganese incorporated, yet up to 30% of the activity was retained with iron. Assimilation of iron or manganese ions into superoxide dismutase was also found to be affected by the growth conditions. This enzyme was also found to be remarkably thermostable and was resistant to H
2
O
2
at concentrations up to 80 mM. Reactive oxygen defense mechanisms have not been previously characterized in the organisms belonging to the phylum
Chloroflexi
. These systems are of interest in
C. aurantiacus
since this bacterium lives in a hyperoxic environment and is subject to high UV radiation fluxes.
Mechanism of Intrinsic Resistance to Vancomycin in
Clostridium innocuum
NCIB 10674
Authors: David Véronique , Bozdogan Bülent , Mainardi Jean-Luc , Legrand Raymond , Gutmann Laurent , Leclercq Roland 
Published: May 2004

ABSTRACT

We have studied the basis for intrinsic resistance to low levels of vancomycin in
Clostridium innocuum
NCIB 10674 (MIC = 8 μg/ml). Analysis by high-pressure liquid chromatography (HPLC) and mass spectrometry of peptidoglycan nucleotide precursors pools revealed the presence of two types of UDP-MurNac-pentapeptide precursors constitutively produced, an UDP-MurNAc-pentapeptide with a serine at the C terminus which represented 93% of the pool and an UDP-MurNAc-pentapeptide with an alanine at the C terminus which represented the rest of the pool.
C. innocuum
cell wall muropeptides containing pentapeptide[Ser], either dialanine substituted on the epsilon amino group of lysine or not, were identified and represented about 10% of the monomers while only 1% of pentapeptide[
d
-Ala] monomers were found. The sequence of a 2,465-bp chromosomal fragment from
C. innocuum
was determined and revealed the presence of

ddl
c. innocuum

and
C. innocuum
racemase genes putatively encoding homologues of
d
-Ala:
d
-X ligases and amino acid racemases, respectively. Analysis of the pool of precursors of
Enterococcus faecalis
JH2-2, containing cloned

ddl
c. innocuum

and
C. innocuum
racemase genes showed in addition to the UDP-MurNAc-pentapeptide[
d
-Ala], the presence of an UDP-MurNAc-pentapeptide[
d
-Ser] precursor. However, the expression of low-level resistance to vancomycin was observed only when both genes were cloned in
E. faecalis
JH2-2 together with the

vanXY
c

gene from
Enterococcus gallinarum
BM4174 which encodes a
d
,
d
-peptidase which eliminates preferentially the high affinity vancomycin UDP-MurNAc-pentapeptide [
d
-Ala] precursors produced by the host. We conclude that resistance to vancomycin in
C. innocuum
NCIB 10674 was related to the presence of the two chromosomal

ddl
c. innocuum

and
C. innocuum
racemase genes allowing the synthesis of a peptidoglycan precursor terminating in serine with low affinity for vancomycin.
Cloning and Functional Analysis by Gene Disruption of a Gene Encoding a γ-Butyrolactone Autoregulator Receptor fromKitasatospora setae
Authors: Choi Sun-Uk , Lee Chang-Kwon , Hwang Yong-Il , Kinoshita Hiroshi , Nihira Takuya 
Published: May 2004

ABSTRACTγ-Butyrolactone autoregulator receptors of the genusStreptomyceshave a common activity as DNA-binding transcriptional repressors, controlling secondary metabolism and/or morphological differentiation. A gene encoding a γ-butyrolactone autoregulator receptor was cloned from a bafilomycin B1producer,Kitasatospora setae, for the first time from a non-Streptomycesgenus of actinomycetes, and its function was evaluated by in vitro and in vivo analyses. The gene fragment was initially cloned by PCR with primers designed from two highly conserved regions ofStreptomycesautoregulator receptors (BarA, FarA, ScbR, and ArpA), followed by genomic Southern hybridization yielding a 7-kb BamHI fragment on which a 654-bp receptor gene (ksbA) was identified. The recombinant KsbA protein demonstrated clear binding activity toward3H-labeled autoregulators, especially toward [3H]SCB1, confirming thatksbAencodes a real autoregulator receptor ofK. setae. To clarify the in vivo function ofksbA, aksbA-disrupted strain was constructed by means of homologous recombination after introducing aksbAdisruption construct via transconjugation fromEscherichia coli. No difference in morphology was found between the wild-type strain and theksbAdisruptants. However, theksbAdisruptants started producing bafilomycin 18 h earlier than the wild-type strain and showed a 2.4-fold-higher accumulation of bafilomycin. The phenotype was restored to the original wild-type phenotype by complementation with intactksbA, indicating that the autoregulator receptor protein ofK. setaeacts as a primary negative regulator of the biosynthesis of bafilomycin but plays no role in cytodifferentiation ofK. setae. This indicates that, unlike the A-factor receptor ofStreptomyces griseus, the autoregulator receptor (ksbA) ofK. setaebelongs to a family of autoregulator receptors which control secondary metabolism but play no role in morphological differentiation.
Characterization of a Eukaryotic-Like Tyrosine Protein Kinase Expressed by the Shiga Toxin-Encoding Bacteriophage 933W
Authors: Tyler Jessica S. , Friedman David I. 
Published: May 2004

ABSTRACTThe Shiga toxin (Stx)-encoding bacteriophage 933W contains an open reading frame,stk, with amino acid sequence similarity to the catalytic domain of eukaryotic serine/threonine (Ser/Thr) protein kinases (PKs). Eukaryotic PKs are related by a common catalytic domain, consisting of invariant and nearly invariant residues necessary for ATP binding and phosphotransfer. We demonstrate that rather than a Ser/Thr kinase,stkencodes a eukaryotic-like tyrosine (Tyr) kinase. An affinity-purified recombinant Stk (rStk) autophosphorylates and catalyzes the phosphorylation of an artificial substrate on Tyr residues and not on Ser or Thr residues. A change of an invariant lysine within the putative catalytic domain abolishes this kinase activity, indicating that Stk uses a phosphotransfer mechanism similar to the mechanism used by eukaryotic PKs. We provide evidence suggesting thatstkis cotranscribed withcI from the phage promoter responsible for maintaining CI expression during lysogeny. Thestkgene was identified in prophages obtained from independently isolated Stx-producingEscherichia coliclinical isolates, suggesting that selective pressure has maintained thestkgene in these pathogenic bacteria.
Transcriptome Analysis of Crp-Dependent Catabolite Control of Gene Expression in
Escherichia coli
Authors: Gosset Guillermo , Zhang Zhongge , Nayyar Samir , Cuevas William A. , Saier Milton H. 
Published: May 2004

ABSTRACT
We report here the transcriptome analyses of highly expressed genes that are subject to catabolite repression or activation mediated by the cyclic AMP receptor protein (Crp). The results reveal that many operons encoding enzymes of central carbon metabolic pathways (e.g., Krebs cycle enzymes), as well as transporters and enzymes that initiate carbon metabolism, are subject to direct Crp-mediated catabolite repression. By contrast, few enzyme-encoding genes (direct regulation) but many ribosomal protein- and tRNA-encoding genes (indirect regulation) are subject to Crp-dependent glucose activation. Additionally, Crp mediates strong indirect catabolite repression of many cytoplasmic stress response proteins, including the major chaperone proteins, five ATP-dependent protease complexes, and several cold and heat shock proteins. These results were confirmed by (i) phenotypic analyses, (ii) real-time PCR studies, (iii) reporter gene fusion assays, and (iv) previously published reports about representative genes. The results serve to define and extend our appreciation of the Crp regulon.