Caractérisation de l'impact rénal à court et long terme du choc hémorragique expérimental murin

La présence d'une insuffisance rénale aiguë (IRA) est un marqueur indépendant de surmortalité dans de nombreuses pathologies médico-chirurgicales. La première cause d'IRA organique est la nécrose tubulaire aiguë ischémique (NTAI). L'absence d'efficacité, chez l'Homme, des thérapeutiques pourtant testées avec succès chez l'animal pourrait être liée aux carences des modèles expérimentaux de nécrose tubulaire. En effet, ces modèles (clampage artère rénale, dose massive de drogues tubulo-toxiques) proposent une approche caricaturale de l'IRA qui prévient tout mécanisme physiologique d'adaptation. Notre objectif était d'élaborer un nouveau modèle d'IRA par choc hémorragique à pression contrôlée chez la souris C57/Bl6 et d'en étudier les conséquences rénales. Nous avons dans un premier temps mis au point le modèle de choc hémorragique et montré qu'une durée de choc de deux heures à 35 mmHg de pression artérielle moyenne est susceptible de créer une IRA par NTAI. Nous avons dans un deuxième temps étudié les répercussions rénales de ce choc et ainsi observé un impact fonctionnel moléculaire et structurel prédominant entre le 2ème jour (J) et J6 en post choc mais persistant à J21 avec la mise en évidence d'une fibrose rénale et d'anomalies fonctionnelles physiologiques tubulaires rénales. L'existence d'une hypoxie rénale dans les suites du choc nous a amené à étudier son impact dans une population de souris diabétiques de type 2 obèse (db/db). Nous avons en effet confirmé que les reins de souris diabétiques présentaient une hypoxie avant toute agression et que le choc hémorragique aboutissait à un impact fonctionnel plus sévère et une réponse à l'hypoxie différente chez les souris diabétiques. Enfin, la difficulté d'évaluation de la fonction de filtration rénale chez le muridé nous a conduits à effectuer une étude de corrélation entre les marqueurs historiques (créatininémie, urée plasmatique), la cystatine C et le gold standard (la clearance de l'inuline plasmatique) chez 80 souris. Dans cette note technique située en annexe, nous avons pu confirmer que ni l'urée ni la créatininémie par la technique colorimétrique n'étaient des marqueurs fiables chez la souris. La créatininémie par la technique immunoenzymatique et surtout la cystatine c sont mieux corrélées au DFG évalué par la clearance de l'inuline. Au total nous avons décrit un nouveau modèle d'agression rénale chez des souris sauvages C57/Bl6 et une population de souris diabétiques de type 2. Nous avons également mis en évidence l'intérêt de la cystatine C chez la souris en tant que marqueur d'estimation du DFG a contrario des marqueurs historiques (créatininémie par la technique colorimétrique et urée plasmatique).Acute renal failure (ARF) is an independent mortality marker in numerous medical or surgical pathologies. The leading cause of organic ARF is ischemic acute tubular necrosis. The lack of efficacy in humans of therapeutic yet successfully tested in animals may be related to the deficiencies in experimental models of tubular necrosis. Indeed, these models (renal artery clamping, massive dose of tubulo-toxic drugs) propose a caricatural mechanism of ARF and prevent any physiological mechanism of adaptation. Our goal was to develop, in mice, a new model of ARF induced by pressure controlled hemorrhagic shock and to decipher its kidney impact. We initially developed the model of hemorrhagic shock and showed that two hours shock duration at 35 mmHg of mean arterial pressure is likely to create an organic ARF. Then, we tested the impact of this shock on kidney and observed a molecular and functional impact predominant between day (D) 2 and D6 after shock but still present at D21 with renal fibrosis and renal tubular dysfunction. The existence of renal hypoxia in the aftermath of shock led us to study its impact in a population of obese type 2 diabetic mice (db/db). We have indeed confirmed that diabetic mice kidneys already exhibit hypoxia before any aggression and that hemorrhagic shock led to a more severe functional impact and a different response to hypoxia in diabetic mice. At least, because evaluating glomerular filtration (GFR) in mice is hazardous, we have performed a correlation study between the historical markers (serum creatinin, plasma urea), cystatin c and measured GFR. We have confirmed that neither urea nor creatinin obtained by the colorimetric technique are reliable markers in mice. Nevertheless, creatinin obtained by immuno colorimetric assay and particularly cystatin C are better correlated with measured GFR. Altogether, we have described a new model of ARF in two different mice populations: control C57/Bl6 and type 2 diabetic obese mice. We also highlight that cystatin C in mice is more accurate for estimating GFR that historical markers (serum creatinin by the colorimetric technique and plasma urea)

The selectivity filter is involved in the U-type inactivation process of Kv2.1 and Kv3.1 channels

Voltage-gated potassium (Kv) channels display several types of inactivation processes, including N-, C-, and U-types. C-type inactivation is attributed to a nonconductive conformation of the selectivity filter (SF). It has been proposed that the activation gate and the channel's SF are allosterically coupled because the conformational changes of the former affect the structure of the latter and vice versa. The second threonine of the SF signature sequence (e.g., TTVGYG) has been proven to be essential for this allosteric coupling. To further study the role of the SF in U-type inactivation, we substituted the second threonine of the TTVGYG sequence by an alanine in the hKv2.1 and hKv3.1 channels, which are known to display U-type inactivation. Both hKv2.1-T377A and hKv3.1-T400A yielded channels that were resistant to inactivation, and as a result, they displayed noninactivating currents upon channel opening; i.e., hKv2.1-T377A and hKv3.1-T400A remained fully conductive upon prolonged moderate depolarizations, whereas in wild-type hKv2.1 and hKv3.1, the current amplitude typically reduces because of U-type inactivation. Interestingly, increasing the extracellular K+ concentration increased the macroscopic current amplitude of both hKv2.1-T377A and hKv3.1-T400A, which is similar to the response of the homologous T to A mutation in Shaker and hKv1.5 channels that display C-type inactivation. Our data support an important role for the second threonine of the SF signature sequence in the U-type inactivation gating of hKv2.1 and hKv3.1. SIGNIFICANCE Voltage-dependent K+ (Kv) channels generate cells' repolarizing power, which is consequently regulated by the channel's conductance. Aside from the opening or closure, Kv channels undergo inactivation that drives them into a lower or nonconductive state. Among the different inactivation processes described in Kv channels, the U-type process develops from a preopen but activated state. The molecular determinants of this process are, in contrast to the Ctype mechanism, not well characterized. Our data show that the intracellular part of the K+ selectivity filter within the pore domain is involved. An alanine for threonine substitution results in channels that do not inactivate upon opening, suggesting that an allosteric coupling between the activation gate and selectivity filter exists in U-type inactivation

IISMM – Institut d’études de l’Islam et des sociétés du monde musulman

Olivier Bouquet, maître de conférences à l’Université de Nice-Sophia AntipolisAnne-Laure Dupont, maître de conférences à l’Université Paris-IV/SorbonneBenjamin Lellouch, maître de conférences à l’Université Paris-VIII/Vincennes-Saint-DenisCatherine Mayeur-Jaouen, professeur à l’INaLCOSabrina Mervin, chargée de recherche au CNRSNicolas Michel, maître de conférences à l’Université Aix-Marseille-I/ProvenceM’hamed Oualdi, Chantai Verdeil, maîtres de conférences à l’INaLCO Histoire moderne et cont..

IISMM – Institut d’études de l’Islam et des sociétés du monde musulman

Olivier Bouquet, maître de conférences à l’Université de Nice-Sophia AntipolisAnne-Laure Dupont, maître de conférences à l’Université Paris-IV/SorbonneBenjamin Lellouch, maître de conférences à l’Université Paris-VIII/Vincennes-Saint-DenisCatherine Mayeur-Jaouen, professeur à l’INaLCOSabrina Mervin, chargée de recherche au CNRSNicolas Michel, maître de conférences à l’Université Aix-Marseille-I/ProvenceM’hamed Oualdi, Chantai Verdeil, maîtres de conférences à l’INaLCO Histoire moderne et cont..

In vitro nuclear interactome of the HIV-1 Tat protein

<p>Abstract</p> <p>Background</p> <p>One facet of the complexity underlying the biology of HIV-1 resides not only in its limited number of viral proteins, but in the extensive repertoire of cellular proteins they interact with and their higher-order assembly. HIV-1 encodes the regulatory protein Tat (86–101aa), which is essential for HIV-1 replication and primarily orchestrates HIV-1 provirus transcriptional regulation. Previous studies have demonstrated that Tat function is highly dependent on specific interactions with a range of cellular proteins. However they can only partially account for the intricate molecular mechanisms underlying the dynamics of proviral gene expression. To obtain a comprehensive nuclear interaction map of Tat in T-cells, we have designed a proteomic strategy based on affinity chromatography coupled with mass spectrometry.</p> <p>Results</p> <p>Our approach resulted in the identification of a total of 183 candidates as Tat nuclear partners, 90% of which have not been previously characterised. Subsequently we applied <it>in silico </it>analysis, to validate and characterise our dataset which revealed that the Tat nuclear interactome exhibits unique signature(s). First, motif composition analysis highlighted that our dataset is enriched for domains mediating protein, RNA and DNA interactions, and helicase and ATPase activities. Secondly, functional classification and network reconstruction clearly depicted Tat as a polyvalent protein adaptor and positioned Tat at the nexus of a densely interconnected interaction network involved in a range of biological processes which included gene expression regulation, RNA biogenesis, chromatin structure, chromosome organisation, DNA replication and nuclear architecture.</p> <p>Conclusion</p> <p>We have completed the <it>in vitro </it>Tat nuclear interactome and have highlighted its modular network properties and particularly those involved in the coordination of gene expression by Tat. Ultimately, the highly specialised set of molecular interactions identified will provide a framework to further advance our understanding of the mechanisms of HIV-1 proviral gene silencing and activation.</p

Impact of gastrointestinal tract variability on oral drug absorption and pharmacokinetics : an UNGAP review

The absorption of oral drugs is frequently plagued by significant variability with potentially serious therapeutic consequences. The source of variability can be traced back to interindividual variability in physiology, differences in special populations (age- and disease-dependent), drug and formulation properties, or food-drug interactions. Clinical evidence for the impact of some of these factors on drug pharmacokinetic variability is mounting: e.g. gastric pH and emptying time, small intestinal fluid properties, differences in pediatrics and the elderly, and surgical changes in gastrointestinal anatomy. However, the link of colonic factors variability (transit time, fluid composition, microbiome), sex differences (male vs. female) and gut-related diseases (chronic constipation, anorexia and cachexia) to drug absorption variability has not been firmly established yet. At the same time, a way to decrease oral drug pharmacokinetic variability is provided by the pharmaceutical industry: clinical evidence suggests that formulation approaches employed during drug development can decrease the variability in oral exposure. This review outlines the main drivers of oral drug exposure variability and potential approaches to overcome them, while highlighting existing knowledge gaps and guiding future studies in this area

Description des côtes nord de Madagascar par Corby et Mayeur à la fin du XVIIIe siècle

Au xviiie siècle, le comte Benyowsky s’installe au nord-est de Madagascar au nom du Roi de France. Son « commis voyageur », Mayeur, va à sa demande sillonner le nord de l’île et laissera une brève description de Vohémar et de son voisinage.At the end of the 18th century, Benyowsky settled on the north-eastern coast of Madagascar. He sent Mayeur to enquire about different regions of the island. Mayeur gave a short but interesting description of Vohemar and the near-by region

Cinétiques plasmatiques péri-dialytiques des cytokines et de la cystatine C chez le patient présentant une insuffisance rénale aïgue dans les suites d'un choc septique

TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF