Role of Fibronectin in the Adhesion of Acinetobacter baumannii to Host Cells

Adhesion to host cells is an initial and important step in Acinetobacter baumannii pathogenesis. However, there is relatively little information on the mechanisms by which A. baumannii binds to and interacts with host cells. Adherence to extracellular matrix proteins, such as fibronectin, affords pathogens with a mechanism to invade epithelial cells. Here, we found that A. baumannii adheres more avidly to immobilized fibronectin than to control protein. Free fibronectin used as a competitor resulted in dose-dependent decreased binding of A. baumannii to fibronectin. Three outer membrane preparations (OMPs) were identified as fibronectin binding proteins (FBPs): OMPA, TonB-dependent copper receptor, and 34 kDa OMP. Moreover, we demonstrated that fibronectin inhibition and neutralization by specific antibody prevented significantly the adhesion of A. baumannii to human lung epithelial cells (A549 cells). Similarly, A. baumannii OMPA neutralization by specific antibody decreased significantly the adhesion of A. baumannii to A549 cells. These data indicate that FBPs are key adhesins that mediate binding of A. baumannii to human lung epithelial cells through interaction with fibronectin on the surface of these host cells

Constitutive apoptosis in equine peripheral blood neutrophils in vitro

AbstractThe aim of this study was to characterise constitutive apoptosis in equine peripheral blood neutrophils, including assessment of factors that potentially modulate neutrophil survival through alteration of the rate of constitutive apoptosis. Cells underwent spontaneous time-dependent constitutive apoptosis when aged in culture for up to 36 h, developing the structural and functional features of apoptosis observed in many cell types, including human neutrophils. Neutrophils undergoing apoptosis also had diminished zymosan activated serum (ZAS)-stimulated chemiluminescence, but maintained responsiveness to phorbol myristate acetate (PMA). The constitutive rate of equine neutrophil apoptosis was promoted by lipopolysaccharide (LPS), tumour necrosis factor α and phagocytosis of opsonised ovine erythrocytes, while it was inhibited by dexamethasone and ZAS (a source of C5a). Formyl-Met-Leu-Phe, leukotriene B4, platelet activating factor and PMA had no demonstrable effect on equine neutrophil apoptosis. There was a difference between equine and human neutrophil apoptosis in response to LPS and the time-dependence of the response to dexamethasone

The initiation of transverse matrix cracking and longitudinal matrix cracking in composite cross-ply laminates: Analysis of a damage criterion

The results of stress field distribution in damage cross-ply laminates prompt us to elaborate an energy criterion. This criterion is based on the partial parts’s computation of the strain energy release rate associated with each damage type and for all loading modes. In the related criterion, based on the linear fracture approach, several hypotheses are used to simplify the damage criterion. The main objective with this approach is to estimate the onset of transverse and longitudinal cracking mechanisms and the development of the damage. Only results from numerical simulations are proposed for one material; numerous numerical simulations, with other materials and laminate architectures, give similar evolutions of matrix cracking damage

Flux de chaleur critiques (burn-out) de l’hydrogène et de l’azote liquides en convection forcée

Hydrogen and nitrogen liquids burn-out under forced convection. Experimental results obtained with a 3 mm dia. x 300 mm. Inconel tube at variable pressures and rates of flow. Occurrence of burn-out due to pronounced wall temperature instability at the tube outlet, as frequently associated with oscillating flow rates. Two burn-out values are obtained in certain cases at the same flow and different hydrodynamic conditions, depending on the stability of the flow. Burn-out ceases just below the critical pressure. Comparisons with other fluids.Les expériences ont été effectuées à l'aide d'un tube en inconel (diamètre 3 mm, longueur 300 mm) dans des conditions de débit et de pression largement variables. Le phénomène de «burn-out » est une limitation des flux de chaleur imposés. Il est peut-être dû à l'apparition de la caléfaction (titre de vapeur faible) ou à la désagrégation du film liquide adhérant à la paroi (titre élevé). La stabilité du régime hydrodynamique de l'écoulement est un facteur déterminant dans la manifestation du phénomène. Deux valeurs sensiblement différentes du flux de «burn-out » peuvent être déterminées pour un même écoulement donné : la valeur la plus faible correspondant au régime oscillatoire. Dans nos expériences, débit (G) et pression (P) sont les deux seules variables indépendantes (entrée à température constante). On discute l'influence de P et de G. Le phénomène de «burn-out» disparaît un peu en dessous de la pression critique.Perroud P., Rebière J., Weil Louis. Flux de chaleur critiques (burn-out) de l’hydrogène et de l’azote liquides en convection forcée. In: Les instabilités en hydraulique et en mécanique des fluides. Compte rendu des huitièmes journées de l'hydraulique. Lille, 8-10 juin 1964. Tome 2, 1965

LakeSST : Température de peau de la surface des plans d'eau français pour 1999-2016 à partir des archives Landsat

International audienceThe spatial and temporal coverage of the Landsat satellite imagery make it an ideal resource for the monitoring of water temperature over large territories at a moderate spatial and temporal scale at a low cost. We used Landsat 5 and Landsat 7 archive images to create the Lake Skin Surface Temperature (LakeSST) data set, which contains skin water surface temperature data for 442 French water bodies (natural lakes, reservoirs, ponds, gravel pit lakes and quarry lakes) for the period 1999-2016. We assessed the quality of the satellite temperature measurements by comparing them to in situ measurements and taking into account the cool skin and warm layer effects. To estimate these effects and to investigate the theoretical differences between the freshwater and seawater cases, we adapted the COARE 3.0 algorithm to the freshwater environment. We also estimated the warm layer effect using in situ data. At the reservoir of Bimont, the estimated cool skin effect was abou

LakeSST: un jeu de données de température superficielle de l'eau obtenue par satellite pour étudier le comportement des plans d'eau français

International audienceLakeSST (Lake Skin Surface Temperature) is a data set derived from Landsat thermal images, containing data for 442 French water bodies for 1999-2016. We show an example of application to study the thermal regime of the reservoir of Bimont