L008 Défaut de différenciation veino-lymphatique embyonnaire par modulation de l’ARN interférence

L’ARN interférence, mécanisme de régulation de l’expression des gènes, est médiée par les siARNs et les microARNs, ARN non-codants de 20 à 22 nucléotides affectant la régulation post-transcriptionnelle d’ARNm cibles avec lesquels ils s’apparient.La RNase DICER est une enzyme centrale de la biosynthèse des siARNs et microARNs. Les souris dont le gène dicer est invalidé ont un phénotype complexe, et meurent très tôt pendant le développement, notamment à cause d’un défaut d’angiogenèse.Afin d’étudier l’ARN interférence au cours de l’angiogenèse embryonnaire, des souris dont le gène dicer est floxé (mutant conditionnel) sont croisées avec des souris exprimant la recombinase Cre, de manière constitutive, sous le contrôle du promoteur du gène tie2, dirigeant ainsi son expression dans les cellules endothéliales (CE) et les cellules hématopiétiques.Nos résultats montrent que l’invalidation de dicer sous le contrôle du promoteur du gène tie2 entraine une mortalité embryonnaire suite à un œdème et des hémorragies au treizième jour du développement (E13,5). L’analyse histologique montre des vaisseaux lymphatiques remplis de sang, suggérant une mauvaise séparation du réseau sanguin et lymphatique. Cette hypothèse est étudiée par marquage des vaisseaux lymphatiques (LYVE-1) et des vaisseaux sanguins (PECAM) sur embryon entier et peaux isolées à différents stades précédant la mort.Ces embryons présentent également un problème de développement du foie, probablement dû à l’activité du promoteur tie2 dans les lignées hématopoiétiques. La mise en culture de ces foies fœtaux à E13,5 révèle une atteinte des précurseurs hématopoétiques.L’étude de ces précurseurs à des stades plus précoces (E8,5) est en cours au laboratoire.Nos résultats démontrent donc un rôle important de l’ARN interférence dans le contrôle épigénétique de l’angiogenèse et de la lymphangiogenèse embryonnaire mais également dans le développement de l’hématopoièse, suggérant son implication dans la différenciation veino-lymphangiogenèse, dont les mécanismes moléculaires seront discutés

Autoradiographic Characterization and Localization of Quisqualate Binding Sites in Rat Brain Using the Antagonist [ 3 H]6-Cyano-7-Nitroquinoxaline-2,3-Dione: Comparison with ( R,S )-[ 3 H]Α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Binding Sites

Using quantitative autoradiography, we have investigated the binding sites for the potent competitive non- N -methyl-D-aspartate (non-NMDA) glutamate receptor antagonist [ 3 H]6-cyano-7-nitro-quinoxaline-2,3-dione ([ 3 H]-CNQX) in rat brain sections. [ 3 H]CNQX binding was regionally distributed, with the highest levels of binding present in hippocampus in the stratum radiatum of CA1, stratum lucidum of CA3, and molecular layer of dentate gyrus. Scatchard analysis of [ 3 H]CNQX binding in the cerebellar molecular layer revealed an apparent single binding site with a K D = 67 ± 9.0 n M and B max = 3.56 ± 0.34 pmol/mg protein. In displacement studies, quisqualate, L-glutamate, and kainate also appeared to bind to a single class of sites. However, ( R,S )- Α -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) displacement of [ 3 H]CNQX binding revealed two binding sites in the cerebellar molecular layer. Binding of [ 3 H]AMPA to quisqualate receptors in the presence of potassium thiocyanate produced curvilinear Scatchard plots. The curves could be resolved into two binding sites with K D1 = 9.0 ± 3.5 n M , B max = 0.15 ± 0.05 pmol/mg protein, K D2 = 278 ± 50 n M , and B max = 1.54 ± 0.20 pmol/mg protein. The heterogeneous anatomical distribution of [ 3 H]CNQX binding sites correlated to the binding of L-[ 3 H]glutamate to quisqualate receptors and to sites labeled with [ 3 H]AMPA. These results suggest that the non-NMDA glutamate receptor antagonist [ 3 H]CNQX binds with equal affinity to two states of quisqualate receptors which have different affinities for the agonist [ 3 H]AMPA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65634/1/j.1471-4159.1990.tb01925.x.pd

Erratum: Epidemiology and factors associated with diarrhoea among children under five years of age in the Engela District in the Ohangwena Region, Namibia

No abstract available

DIVERSITY OF MICROBIAL STRAINS INVOLVED IN COCOA FERMENTATION FROM SUD-COMOÉ (COTE D’IVOIRE) BASED ON BIOCHEMICAL PROPERTIES

The cocoa pulp fermentation is one of keys step for obtaining a quality chocolate. However, microflora involved in this process is complex and variable that leads to inconsistent production efficiency on cocoa quality. Here we investigate the diversity of microflora implicated in Sud-Comoé (area of Côte d’Ivoire) cocoa fermentation based on their biochemical properties. During fermentation, yeasts, Lactic Acid Bacteria (LAB) and Acetic Acid Bacteria (AAB) reached maximum load at 36, 24 and 72 h respectively and decreased rapidly while the rate of Bacillus load increased throughout the fermentative process to reach a peak at 144 h. Among the Bacillus strains, 62.22, 87.5 and 33.7 % were able to produce pectinolytic enzymes, acid and citrate lyase respectively. Concerning yeasts strains, 25.43 % showed pectinolytic enzymes production capacity and all of these isolates were able to ferment glucose and fructose while 52 % were able to produce gas from sucrose. Population of LAB was predominant by homofermentative group with proportion at 85.96 % while AAB were dominated by genera Acetobacter with 88.78 %. Therefore, this study shows the diversity of biochemical properties of tested microbial strains indicating a diversity of microbiota involved in Sud-Comoé cocoa fermentation

Septic AKI in ICU patients. diagnosis, pathophysiology, and treatment type, dosing, and timing: a comprehensive review of recent and future developments

Evidence is accumulating showing that septic acute kidney injury (AKI) is different from non-septic AKI. Specifically, a large body of research points to apoptotic processes underlying septic AKI. Unravelling the complex and intertwined apoptotic and immuno-inflammatory pathways at the cellular level will undoubtedly create new and exciting perspectives for the future development (e.g., caspase inhibition) or refinement (specific vasopressor use) of therapeutic strategies. Shock complicating sepsis may cause more AKI but also will render treatment of this condition in an hemodynamically unstable patient more difficult. Expert opinion, along with the aggregated results of two recent large randomized trials, favors continuous renal replacement therapy (CRRT) as preferential treatment for septic AKI (hemodynamically unstable). It is suggested that this approach might decrease the need for subsequent chronic dialysis. Large-scale introduction of citrate as an anticoagulant most likely will change CRRT management in intensive care units (ICU), because it not only significantly increases filter lifespan but also better preserves filter porosity. A possible role of citrate in reducing mortality and morbidity, mainly in surgical ICU patients, remains to be proven. Also, citrate administration in the predilution mode appears to be safe and exempt of relevant side effects, yet still requires rigorous monitoring. Current consensus exists about using a CRRT dose of 25 ml/kg/h in non-septic AKI. However, because patients should not be undertreated, this implies that doses as high as 30 to 35 ml/kg/h must be prescribed to account for eventual treatment interruptions. Awaiting results from large, ongoing trials, 35 ml/kg/h should remain the standard dose in septic AKI, particularly when shock is present. To date, exact timing of CRRT is not well defined. A widely accepted composite definition of timing is needed before an appropriate study challenging this major issue can be launched

β-Lactam Resistance Response Triggered by Inactivation of a Nonessential Penicillin-Binding Protein

It has long been recognized that the modification of penicillin-binding proteins (PBPs) to reduce their affinity for β-lactams is an important mechanism (target modification) by which Gram-positive cocci acquire antibiotic resistance. Among Gram-negative rods (GNR), however, this mechanism has been considered unusual, and restricted to clinically irrelevant laboratory mutants for most species. Using as a model Pseudomonas aeruginosa, high up on the list of pathogens causing life-threatening infections in hospitalized patients worldwide, we show that PBPs may also play a major role in β-lactam resistance in GNR, but through a totally distinct mechanism. Through a detailed genetic investigation, including whole-genome analysis approaches, we demonstrate that high-level (clinical) β-lactam resistance in vitro, in vivo, and in the clinical setting is driven by the inactivation of the dacB-encoded nonessential PBP4, which behaves as a trap target for β-lactams. The inactivation of this PBP is shown to determine a highly efficient and complex β-lactam resistance response, triggering overproduction of the chromosomal β-lactamase AmpC and the specific activation of the CreBC (BlrAB) two-component regulator, which in turn plays a major role in resistance. These findings are a major step forward in our understanding of β-lactam resistance biology, and, more importantly, they open up new perspectives on potential antibiotic targets for the treatment of infectious diseases

Nomenclature for renal replacement therapy and blood purification techniques in critically ill patients: practical applications

This article reports the conclusions of the second part of a consensus expert conference on the nomenclature of renal replacement therapy (RRT) techniques currently utilized to manage acute kidney injury and other organ dysfunction syndromes in critically ill patients. A multidisciplinary approach was taken to achieve harmonization of definitions, components, techniques, and operations of the extracorporeal therapies. The article describes the RRT techniques in detail with the relevant technology, procedures, and phases of treatment and key aspects of volume management/fluid balance in critically ill patients. In addition, the article describes recent developments in other extracorporeal therapies, including therapeutic plasma exchange, multiple organ support therapy, liver support, lung support, and blood purification in sepsis. This is a consensus report on nomenclature harmonization in extracorporeal blood purification therapies, such as hemofiltration, plasma exchange, multiple organ support therapies, and blood purification in sepsis

The Intracellular Transport and Secretion of Calumenin-1/2 in Living Cells

Calumenin isoforms 1 and 2 (calu-1/2), encoded by the CALU gene, belong to the CREC protein family. Calu-1/2 proteins are secreted into the extracellular space, but the secretory process and regulatory mechanism are largely unknown. Here, using a time-lapse imaging system, we visualized the intracellular transport and secretory process of calu-1/2-EGFP after their translocation into the ER lumen. Interestingly, we observed that an abundance of calu-1/2-EGFP accumulated in cellular processes before being released into the extracellular space, while only part of calu-1/2-EGFP proteins were secreted directly after attaching to the cell periphery. Moreover, we found the secretion of calu-1/2-EGFP required microtubule integrity, and that calu-1/2-EGFP-containing vesicles were transported by the motor proteins Kif5b and cytoplasmic dynein. Finally, we determined the export signal of calu-1/2-EGFP (amino acid positions 20–46) and provided evidence that the asparagine at site 131 was indispensable for calu-1/2-EGFP stabilization. Taken together, we provide a detailed picture of the intracellular transport of calu-1/2-EGFP, which facilitates our understanding of the secretory mechanism of calu-1/2

Serum amyloid A primes microglia for ATP-dependent interleukin-1\u3b2 release

Acute-phase response is a systemic reaction to environmental/inflammatory insults and involves production of acute-phase proteins, including serum amyloid A (SAA). Interleukin-1\u3b2 (IL-1\u3b2), a master regulator of neuroinflammation produced by activated inflammatory cells of the myeloid lineage, in particular microglia, plays a key role in the pathogenesis of acute and chronic diseases of the peripheral nervous system and CNS. IL-1\u3b2 release is promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with toll-like receptor (TLR) ligands