Fonction ventriculaire gauche après revascularisation pour occlusion d'une coronaire d'une durée de 1-2 heures [Left ventricular function following revascularization for occlusion of a coronary artery lasting 1 to 2 hours].

The time-lag between coronary occlusion and irreversible damage to the myocardium is ill-defined in man. In 10 patients the changes in left ventricular function have been studied after coronary occlusion during diagnostic or therapeutic cardiac catheterization of 1-2 hours' duration. Revascularization was achieved either surgically or through intracoronary streptokinase infusion. The interval between occlusion and onset of extracorporal circulation or reopening was 61 to 119 minutes. Despite enzyme elevation (CPK, CK-MB, SGOT) and appearance of Q-waves in 5 patients, no significant alteration of left ventricular function was noted on repeat cardiac catheterization 10 to 230 days after the accident. These observations, suggest that coronary occlusion of 1-2 hours' duration fails to produce significant irreversible damage to the myocardium despite electrocardiographic and enzymatic signs of myocardial infarction.

Diagnostic value of MRI for the detection of suspected placental invasion: Does it depend on observers' experience?

Purpose: To evaluate the diagnostic value of specific MR features for detection of suspected placental invasion according to observers' experience.Methods and Materials: Our study population included 25 pregnant women (mean age 35.16) investigated by prenatal MRI. In twelve out of them placental invasion was histopathologically proven, the 13 other women (52%) without placental invasion served as control group. Multiplanar T1- and T2-weighted sequences had been performed mostly without IV contrast injection (1.5 T). MR examinations of the two groups were rendered anonymous, mixed, then independently and retrospectively reviewed by two senior and two junior radiologists in view of 8 MR features indicating placentar invasion including the degree. Results were compared with surgical diagnosis (placenta normal/increta/accreta/percreta). Interobserver agrement between senior and junior readers were calculated. Stepwise logistic regression and receiver operating (ROC) curvers were performed.Results: Demographics between the two groups were not statistically different. Overall sensitivity and specificity for detecting placentar invasion was 90.9% and 75.0% for senior readers, and 81.8% and 61.8% for junior readers respectively. The most significant MR features indicating placentar invasion were T2 hypointense placental bands, followed by placenta praevia, focally interrupted myometrial border, posterior placental insertion, and heterogeneous placental signal. For each of the evaluated MR features the interobserver agreement kappa between the two senior readers was superior than that between the junior readers, ranging from bad (<0.4) to good (0.4-0.75).Conclusions: MRI can be a reliable and reproducible tool for detection of suspected placentar invasion, however very variable according to the observers' experience.

Nedd4-2 modulates renal Na+-Cl- cotransporter via the aldosterone-SGK1-Nedd4-2 pathway.

Regulation of renal Na(+) transport is essential for controlling blood pressure, as well as Na(+) and K(+) homeostasis. Aldosterone stimulates Na(+) reabsorption by the Na(+)-Cl(-) cotransporter (NCC) in the distal convoluted tubule (DCT) and by the epithelial Na(+) channel (ENaC) in the late DCT, connecting tubule, and collecting duct. Aldosterone increases ENaC expression by inhibiting the channel's ubiquitylation and degradation; aldosterone promotes serum-glucocorticoid-regulated kinase SGK1-mediated phosphorylation of the ubiquitin-protein ligase Nedd4-2 on serine 328, which prevents the Nedd4-2/ENaC interaction. It is important to note that aldosterone increases NCC protein expression by an unknown post-translational mechanism. Here, we present evidence that Nedd4-2 coimmunoprecipitated with NCC and stimulated NCC ubiquitylation at the surface of transfected HEK293 cells. In Xenopus laevis oocytes, coexpression of NCC with wild-type Nedd4-2, but not its catalytically inactive mutant, strongly decreased NCC activity and surface expression. SGK1 prevented this inhibition in a kinase-dependent manner. Furthermore, deficiency of Nedd4-2 in the renal tubules of mice and in cultured mDCT(15) cells upregulated NCC. In contrast to ENaC, Nedd4-2-mediated inhibition of NCC did not require the PY-like motif of NCC. Moreover, the mutation of Nedd4-2 at either serine 328 or 222 did not affect SGK1 action, and mutation at both sites enhanced Nedd4-2 activity and abolished SGK1-dependent inhibition. Taken together, these results suggest that aldosterone modulates NCC protein expression via a pathway involving SGK1 and Nedd4-2 and provides an explanation for the well-known aldosterone-induced increase in NCC protein expression.

Acute hepatitis due to brivudin: a case report.

BACKGROUND/AIMS: Brivudin is licensed in several European countries for the treatment of herpetic infections, and is considered safe (approximately 1% of patients with transient elevation of liver enzymes) in large multicenter trials. METHODS: We report a case of acute brivudin hepatitis documented with a liver biopsy in detail. RESULTS: Liver biopsy demonstrated acute liver injury with a predominant cytolytic pattern and features suggestive of a drug-induced immunoallergic hepatitis. Elevated ALT levels returned to normal within weeks. CONCLUSIONS: This is the first published case of acute immunoallergic hepatitis due to brivudin.

Molecular imaging of matrix metalloproteinases in atherosclerotic plaques.

Ischaemic stroke and myocardial infarction often result from the sudden rupture of an atherosclerotic plaque. The subsequent arterial thrombosis occluding the vessel lumen has been widely indicated as the crucial acute event causing peripheral tissue ischaemia. A complex cross-talk between systemic and intraplaque inflammatory mediators has been shown to regulate maturation, remodeling and final rupture of an atherosclerotic plaque. Matrix metalloproteinases (MMPs) are proteolytic enzymes (released by several cell subsets within atherosclerotic plaques), which favour atherogenesis and increase plaque vulnerability. Thus, the assessment of intraplaque levels and activity of MMP might be of pivotal relevance in the evaluation of the risk of rupture. New imaging approaches, focused on the visualisation of inflammation in the vessel wall and plaque, may emerge as tools for individualised risk assessment and prevention of events. In this review, we summarize experimental findings of the currently available invasive and noninvasive imaging techniques, used to detect the presence and activity of MMPs in atherosclerotic plaques.

Impaired natural killing of MHC class I-deficient targets by NK cells expressing a catalytically inactive form of SHP-1.

NK cell function is negatively regulated by MHC class I-specific inhibitory receptors. Transduction of the inhibitory signal involves protein tyrosine phosphatases such as SHP-1 (SH2-containing protein tyrosine phosphatase-1). To investigate the role of SHP-1 for NK cell development and function, we generated mice expressing a catalytically inactive, dominant-negative mutant of SHP-1 (dnSHP-1). In this paper we show that expression of dnSHP-1 does not affect the generation of NK cells even though MHC receptor-mediated inhibition is partially impaired. Despite this defect, these NK cells do not kill syngeneic, normal target cells. In fact dnSHP-1-expressing NK cells are hyporesponsive toward MHC-deficient target cells, suggesting that non-MHC-specific NK cell activation is significantly reduced. In contrast, these NK cells mediate Ab-dependent cell-mediated cytotoxicity and prevent the engraftment with beta2-microglobulin-deficient bone marrow cells. A similar NK cell phenotype is observed in viable motheaten (mev) mice, which show reduced SHP-1 activity due to a mutation in the Shp-1 gene. In addition, NK cells in both mouse strains show a tendency to express more inhibitory MHC-specific Ly49 receptors. Our results demonstrate the importance of SHP-1 for the generation of functional NK cells, which are able to react efficiently to the absence of MHC class I molecules from normal target cells. Therefore, SHP-1 may play an as-yet-unrecognized role in some NK cell activation pathways. Alternatively, a reduced capacity to transduce SHP-1-dependent inhibitory signals during NK cell development may be compensated by the down-modulation of NK cell triggering pathways.

Mechanism, regulation, and ecological role of bacterial cyanide biosynthesis.

A few bacterial species are known to produce and excrete hydrogen cyanide (HCN), a potent inhibitor of cytochrome c oxidase and several other metalloenzymes. In the producer strains, HCN does not appear to have a role in primary metabolism and is generally considered a secondary metabolite. HCN synthase of proteobacteria (especially fluorescent pseudomonads) is a membrane-bound flavoenzyme that oxidizes glycine, producing HCN and CO2. The hcnABC structural genes of Pseudomonas fluorescens and P. aeruginosa have sequence similarities with genes encoding various amino acid dehydrogenases/oxidases, in particular with nopaline oxidase of Agrobacterium tumefaciens. Induction of the hcn genes of P. fluorescens by oxygen limitation requires the FNR-like transcriptional regulator ANR, an ANR recognition sequence in the -40 region of the hcn promoter, and nonlimiting amounts of iron. In addition, expression of the hcn genes depends on a regulatory cascade initiated by the GacS/GacA (global control) two-component system. This regulation, which is typical of secondary metabolism, manifests itself during the transition from exponential to stationary growth phase. Cyanide produced by P. fluorescens strain CHA0 has an ecological role in that this metabolite accounts for part of the biocontrol capacity of strain CHA0, which suppresses fungal diseases on plant roots. Cyanide can also be a ligand of hydrogenases in some anaerobic bacteria that have not been described as cyanogenic. However, in this case, as well as in other situations, the physiological function of cyanide is unknown.

Calcineurin inhibitors activate the proto-oncogene Ras and promote protumorigenic signals in renal cancer cells.

The development of cancer is a major problem in immunosuppressed patients, particularly after solid organ transplantation. We have recently shown that calcineurin inhibitors (CNI) used to treat transplant patients may play a critical role in the rapid progression of renal cancer. To examine the intracellular signaling events for CNI-mediated direct tumorigenic pathway(s), we studied the effect of CNI on the activation of proto-oncogenic Ras in human normal renal epithelial cells (REC) and renal cancer cells (786-0 and Caki-1). We found that CNI treatment significantly increased the level of activated GTP-bound form of Ras in these cells. In addition, CNI induced the association of Ras with one of its effector molecules, Raf, but not with Rho and phosphatidylinositol 3-kinase; CNI treatment also promoted the phosphorylation of the Raf kinase inhibitory protein and the downregulation of carabin, all of which may lead to the activation of the Ras-Raf pathway. Blockade of this pathway through either pharmacologic inhibitors or gene-specific small interfering RNA significantly inhibited CNI-mediated augmented proliferation of renal cancer cells. Finally, it was observed that CNI treatment increased the growth of human renal tumors in vivo, and the Ras-Raf pathway is significantly activated in the tumor tissues of CNI-treated mice. Together, targeting the Ras-Raf pathway may prevent the development/progression of renal cancer in CNI-treated patients.

Identification of CT46/HORMAD1, an immunogenic cancer/testis antigen encoding a putative meiosis-related protein.

Transcripts with ESTs derived exclusively or predominantly from testis, and not from other normal tissues, are likely to be products of genes with testis-restricted expression, and are thus potential cancer/testis (CT) antigen genes. A list of 371 genes with such characteristics was compiled by analyzing publicly available EST databases. RT-PCR analysis of normal and tumor tissues was performed to validate an initial selection of 20 of these genes. Several new CT and CT-like genes were identified. One of these, CT46/HORMAD1, is expressed strongly in testis and weakly in placenta; the highest level of expression in other tissues is &lt;1% of testicular expression. The CT46/HORMAD1 gene was expressed in 31% (34/109) of the carcinomas examined, with 11% (12/109) showing expression levels &gt;10% of the testicular level of expression. CT46/HORMAD1 is a single-copy gene on chromosome 1q21.3, encoding a putative protein of 394 aa. Conserved protein domain analysis identified a HORMA domain involved in chromatin binding. The CT46/HORMAD1 protein was found to be homologous to the prototype HORMA domain-containing protein, Hop1, a yeast meiosis-specific protein, as well as to asy1, a meiotic synaptic mutant protein in Arabidopsis thaliana.

Functional analysis of the 5' flanking sequence of a vaccinia virus late gene.

A series of mutations, including 5' and 3' deletions, as well as insertions were introduced into the 5' flanking nucleotide sequence of a vaccinia virus late gene. This DNA has been shown previously to contain all the necessary elements for correct regulation of the gene most probably transcribed by the viral RNA polymerase. To facilitate the assays, the mutated DNA was fused to the chloramphenicol acetyltransferase gene and inserted into the genome of live vaccinia virus. The effects of the mutations on expression of the chimeric gene were studied by both enzyme assays and nuclease S1 analysis. The results showed that 5' deletions up to about 15 bp from the putative initiation site of transcription still yielded high levels of gene expression. All mutations, however, that deleted the authentic late mRNA start site, abolished promoter activity.

Insertion vélamenteuse du cordon et grossesse gémellaire

Problématique : L'insertion vélamenteuse du cordon ombilical est reportée dans environ 1% des grossesses uniques et semble associée à de sévères complications obstétricales. Mais l'étude de cette insertion reste encore lacunaire en ce qui concerne les grossesses gémellaires. Depuis quelques années, ces dernières sont en augmentation et doivent être considérées comme des grossesses à risque. En effet, les jumeaux occupent une place toujours plus importante dans les unités de néonatologie, du fait de la morbidité particulière de ces grossesses. Ces dernières peuvent de plus s'accompagner d'autres anomalies qui peuvent influencer la croissance des jumeaux déjà prétérités par rapport aux bébés uniques. Parmi celles-ci, l'insertion vélamenteuse du cordon. Existe-il une association entre grossesse gémellaire et insertion vélamenteuse ? Quelles seraient les conséquences de ce type d'insertion sur l'évolution de la grossesse ?¦Objectifs : Evaluer l'incidence de la survenue d'une insertion vélamenteuse du cordon ombilical dans les grossesses gémellaires par rapport aux grossesses uniques et la différence de cette incidence entre placentas monochoriaux et bichoriaux. Analyser les conséquences majeures qui peuvent lui être associées.¦Méthode : Analyse rétrospective de tous les placentas de grossesses gémellaires reçus pour examen à l'institut universitaire de pathologie anatomique (IUPA) de Lausanne entre janvier 2000 et septembre 2010, ainsi que du suivi périnatal des enfants issus de ces grossesses.¦Résultats : 722 placentas issus de grossesses gémellaires ont été reçus et analysés à l'IUPA. L'insertion vélamenteuse du cordon est rencontrée dans plus de 17% des grossesses gémellaires. Elle représente plus de 9% de toutes les insertions lors de ces grossesses. Elle est retrouvée dans 35% des cas lorsque le placenta est monochorial et dans 10% des cas lorsque le placenta est bichorial.¦Notre étude a démontré une influence significative de l'insertion vélamenteuse sur l'âge gestationnel, le poids du placenta, la croissance foetale (poids > taille > PC), la durée d'hospitalisation et la mortalité. La monochorialité est le seul facteur de risque à avoir été mis en évidence.¦Conclusion : Avec l'augmentation de l'âge maternel et le recours de plus en plus fréquent aux traitements de fertilité, le nombre de grossesses gémellaires devrait s'accroitre dans les années à venir et, avec elles, le nombre d'insertions vélamenteuses du cordon. Cependant, le diagnostic d'une telle insertion ne peut être que suspecté lors d'un examen ultrasonographique en cours de grossesse. Il est donc difficile de l'identifier avant la naissance et ainsi de prévoir ses conséquences. Mais en étant conscient des complications éventuelles que peut engendrer cette insertion, nous serions plus à même d'y faire face.

Leishmania major: differential regulation of the surface metalloprotease in amastigote and promastigote stages.

During its life cycle, the protozoan parasite Leishmania major alternates from an intracellular amastigote form in the mammalian host to a flagellated promastigote form in the insect vector. The expression of the surface metalloprotease (PSP) during differentiation in vitro was investigated by Western and Northern blots, by immunoprecipitation of cells metabolically labeled with [35S]methionine or labeled at the surface with radioactive iodine, and by quantification of the proteolytic activity in substrate-containing polyacrylamide gels. We report that the surface metalloprotease is down-regulated at both the mRNA and the protein level in amastigotes, where it represents less than 1% of the equivalent proteolytic activity detected in promastigotes. A significant amount of mRNA is detected 4 hr after the onset of differentiation. The expression of the protease begins at that time and reaches steady state 8 hr later. The synthesis of PSP precedes the complete morphological differentiation to the promastigote stage and the appearance of the lipophosphoglycan, another major promastigote surface component. In contrast to PSP, a family of mercaptoethanol-activated proteases present in the amastigote exists only at a reduced level in the promastigote. The confinement of the surface metalloprotease to the insect stage of the parasite suggests that it has no physiological function in the parasitism maintenance of mammalian host macrophages.

Growth and differentiation of aggregating fetal brain cells in a serum-free defined medium.

Aggregating cultures of mechanically dissociated fetal brain cells provide an excellent system for neurobiological studies of cellular growth and differentiation, but, in common with almost all culture systems, they have the disadvantage that crude serum is required in the medium. Although several cell lines have either been adapted to serum-free conditions or grown normally in serum-free media supplemented with hormones, trace elements and defined serum components, this approach has never been applied to differentiating primary cells of the central nervous system. We now describe the successful cultivation of aggregating fetal rat brain cells in a chemically defined, serum-free medium.

The functions of DNA methylation by CcrM in Caulobacter crescentus: a global approach.

DNA methylation is involved in a diversity of processes in bacteria, including maintenance of genome integrity and regulation of gene expression. Here, using Caulobacter crescentus as a model, we exploit genome-wide experimental methods to uncover the functions of CcrM, a DNA methyltransferase conserved in most Alphaproteobacteria. Using single molecule sequencing, we provide evidence that most CcrM target motifs (GANTC) switch from a fully methylated to a hemi-methylated state when they are replicated, and back to a fully methylated state at the onset of cell division. We show that DNA methylation by CcrM is not required for the control of the initiation of chromosome replication or for DNA mismatch repair. By contrast, our transcriptome analysis shows that >10% of the genes are misexpressed in cells lacking or constitutively over-expressing CcrM. Strikingly, GANTC methylation is needed for the efficient transcription of dozens of genes that are essential for cell cycle progression, in particular for DNA metabolism and cell division. Many of them are controlled by promoters methylated by CcrM and co-regulated by other global cell cycle regulators, demonstrating an extensive cross talk between DNA methylation and the complex regulatory network that controls the cell cycle of C. crescentus and, presumably, of many other Alphaproteobacteria.

Expression of B220 on activated T cell blasts precedes apoptosis.

Superantigens are bacterial or viral products that polyclonally activate T cells bearing certain TCR beta chain variable elements. For instance, Vbeta8+ T cells proliferate in response to staphylococcal enterotoxin B (SEB) in vivo and then undergo Fas- and/or TNF-mediated apoptosis. We have recently shown that apoptotic SEB-reactive T cells express the B cell marker B220. Here we report the identification of a novel subset of CD4+ B220+ T cell blasts that are the precursors of these apoptotic cells in SEB-immunized mice. Moreover, we show that the CD4- CD8- B220+ T cells that accumulate in the lymphoid organs of Fas ligand-defective gld mice stably express a form of the B220 molecule which exhibits biochemical similarities to that expressed by activated wild-type T cells, but is distinct from that displayed on the surface of B cells. Surprisingly, we also find a population of CD4+ B220+ pre-apoptotic T cells in FasL-defective gld mice, arguing that these cells can be generated in a Fas-independent fashion. Collectively, our data support a general model whereby upon activation, T cells up-regulate B220 before undergoing apoptosis. When the apoptotic mechanisms are defective, T cells presumably down-regulate their coreceptor molecules but retain expression of B220 as they accumulate in lymphoid organs.