The cooperative effect of L-selectin clusters and velocity-dependent bond formation that stabilizes leukocyte rolling.

The role of clustered of L-selectin receptors on the leukocyte surface is discussed in connection with the postulated velocity-dependent formation of selectin-ligand tether bonds to interpret the mechanism of leukocyte tethering to, and rolling along, the vascular endothelium. The distinct feature of this step-wise process is a weak dependence of leukocyte rolling velocity on the hydrodynamic forces of ambient flow due to the increased number of selectin bonds with increasing flow shear rate and also their clustering. The contact zones on the leukocyte surface are separated by distances with distribution which corresponds to the distribution of distances of the observed L-selectin clusters.

Membrane fluidity and oxygen diffusion in cholesterol-enriched endothelial cells.

In this study, we measured the influence of cholesterol rigidification on oxygen permeability in human endothelial cell monolayer membranes (ECs). Cholesterol-induced membrane rigidification was assessed at different membrane depths by a fluorescence polarization method with diphenyl-hexatriene (DPH) and 1-(4-trimethylamino)-6-phenylhexatriene (TMA-DPH). Fluorescence quenching by oxygen was probed in preferentially labelled membrane with pyrene butyric acid (PyC4) and pyrene dodecanoic acid (PyC12), as shown with a 3D fluorescence microscope (CellScan System).

Development and evaluation of an automatic method for the study of platelet osmotic response.

Study of the osmotic resistance to hypotonic medium of platelets has often been suggested as a global test to assess the viability of these cells in transfusion or to study modification during haematological pathologies. A number of authors have analysed the behaviour of platelets in hypotonic media by a variety of methods (cell count, determinations of substances released, morphology, etc.), but most studies are currently based on the so-called "Hypotonic Shock Response" test (HSR).

[Vascular disease and cellular activation: exploration of cell adhesion phenotype by quantitative flow cytometry].

The pathogenesis of atheromatous and/or thrombotic vascular diseases involves rheological parameters, soluble mediators and cellular agents. The many studies that have tried to establish correlations between plasma factors, shear stress and the risk of ischemia have left some questions unanswered. Current exploration methods are now focusing on the determining role of cells.

[New automatic test for the study of platelet response to variations in osmotic pressure: application in the evaluation of the viability of platelet concentrates].

Studying the osmotic resistance or swelling of platelets has often been suggested as a global test to assess the viability of those cells. A number of authors have also analysed the behaviour of platelets in hypotonic media by a variety of complementary methods (cell count, morphology, determinations of substances released, photometric measurement of aggregation induced by aggregating agents, etc). Most studies are currently based on the so-called "osmotic shock response" test, which measures according to time the light transmitted through platelet-rich plasma (PRP) after dilution in distilled water.