[Value of enzymuria during antibacterial therapy].

International audienceEnzymuria is a well known parameter of evaluation of drugs nephrotoxicity, particularly of antibiotics. Alanine aminopeptidase (AAP), gamma-glutamyltransferase (GGT) and N-acetyl-bêta-D-glucosaminidase activities were measured in native urine. This study included 19 patients treated by an association of netilmicin-vancomycin. Enzymuria was measured on 24 hours urines at J0 then every two days during treatment. Enzymuria increased 24 or 48 hours after the beginning of the treatment. The Principal Components Analysis (PCA) of the results of enzymuria, seric urea and creatininemia shows the presence of two groups of responses. The first principal component exhibits two populations: the patients with pathological seric urea and pathological seric creatinine and the others. The PCA does not allow this discrimination using only the results of enzymuria; in contrast, with these results, the patients may be classified by the PCA on the basis of treatment duration. The enzymuria allows the clear identification of nephrotoxic drugs but does not allow the prediction of renal injury or of its aggravation

Fitness and competitive growth advantage of new gentamicin-susceptible MRSA clones spreading in French hospitals

International audienc

Mitigation of the diagenesis risk in biological apatite δ18O interpretation

International audienceThe assessment of the potential blurring effect of diagenetic processes represents the greatest challenge for geochemists whose purpose is to reconstruct environmental parameters based on isotopic proxies. Numerous studies performed on phosphatic remains from terrestrial and marine sedimentary deposits have shown post-depositional isotopic modifications due to exchange reactions with surrounding waters. If diagenesis may be diagnosed through several lines of evidence such as mineralogical or chemical modifications of the pristine in vivo apatite after burial in soils and sediments, diagenesis does not prove that bioapatite phosphate exchanged oxygen isotopes with aqueous fluids. Therefore, we propose a new method of detection of diagenetic alteration of bioapatite phosphate based on a statistical approach designed to analyze sample collections. The approach requires that phosphatic remains belonged to animals living during a short time interval and within an environment characterized by steady air or water temperature and the δ18O of ambient water. We show that the distribution of bioapatite phosphate δ18O follows a normal distribution resulting from the combination of independent factors such as those related to the genetics, environment and analytical measurements. In the case of oxygen isotope exchange between the bioapatite phosphate and various amounts of circulating aqueous fluids, our numerical simulations reveal that the distributions of bioapatite phosphate δ18O are asymmetric with shapes depending on the temperature of reaction and the composition of the reacting aqueous fluid. This new statistical tool based on mass balance equations and Monte Carlo simulations is considered valuable to mitigate the diagenesis risk in the interpretation of bioapatite phosphate δ18O as paleoecological and paleoclimatic proxies

La latence bactérienne (modélisation et hypothèses biologiques)

Les microbiologistes utilisent classiquement deux paramètres pour caractériser la croissance bactérienne : le temps de latence ([lambda] ) et le taux de croissance maximum ([mu] max). Dans de nombreux domaines, il est essentiel de pouvoir estimer précisément ces paramètres. Des difficultés d'estimation de ([lambda)] ? ont été mises en évidence notamment du fait du manque de connaissance biologique sur le phénomène de la latence. La méthodologie proposée au cours de ce travail et le développement du logiciel Rfit, ont permis d'analyser les propriétés mathématiques et statistiques des modèles de croissance. Les performances de ces modèles sont inégales et la nature des jeux de données influence grandement la qualité des estimations de ([lambda)]. Par ailleurs, l'hypothèse du rôle central des ribosomes et des opérons ARNr dans la latence bactérienne a été explorée. Les résultats montrent qu'il existe une importante corrélation entre la cinétique d'accumulation des ribosomes et la durée de la phase de latence.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Mise au point d'un nouveau milieu pour la détermination des CMI de M. Tuberculosis aux antituberculeux de première ligne (Pyrazinamide exclu) (travail effectué dans le Laboratoire de bactériologie du Centre Hospitalier Lyon-Sud sous la dir. du Pr. J.P. Flandrois)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF