J-M Pasquet

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Annexin V, a protein with a high affinity and a strict specificity for aminophospholipids at physiologic calcium concentrations, was used to probe platelet activation and the development of procoagulant activity. Platelet secretion was studied in parallel using VH10, a murine monoclonal antibody specific for GMP-140, an alpha-granule membrane glycoprotein.(More)
We have related the release of procoagulant microparticles from platelets to calcium movement and the activation of the Ca(2+)-dependent protease calpain. The effects of the Ca(2+)-ATPase inhibitors thapsigargin, cyclopiazonic acid and 2.5-di-(t-butyl)-1,4-benzohydroquinone were compared with those of the Ca2+ ionophore A23187. Whereas all three(More)
The Scott syndrome is a rare inherited haemorrhagic disorder characterized by the inability of blood cells to expose aminophospholipids and to shed microparticles. We have had the opportunity to study a recently reported French patient with this syndrome and have confirmed by means of a fluorescence assay for transbilayer lipid movement a reduced(More)
The development of procoagulant activity and microparticle formation during platelet activation is known to depend on an increase in cytosolic Ca2+ levels. We have studied the mechanisms leading to these events using FITC-labeled recombinant annexin V, a protein which binds with a high affinity to aminophospholipids, in flow cytometry. In particular, we(More)
BACKGROUND Scleroderma skin overexpresses the platelet-derived growth factor receptor beta-subunit (PDGFR-beta) in dermal vessels and PDGFR-beta messenger RNA in cultured fibroblasts. Moreover, increased levels of PDGF and stimulatory autoantibodies to PDGFR have been identified in the serum of scleroderma patients. OBJECTIVE Imatinib being an inhibitor(More)
Phosphatidylserine exposure and microvesicle release give rise to procoagulant activity during platelet activation. We have previously shown that whereas the Ca2+ ionophore A23187 and 2,5-di-(t-butyl)-1, 4-benzohydroquinone, a Ca2+-ATPase inhibitor, induce phosphatidylserine exposure, only the former triggers microvesicle release. We now report that(More)
Thrombin generation is the culminating event of the coagulation cascade. It is initiated after the expression of tissue factor by endothelial cells and monocytes exposed to thrombogenic stimuli. Anionic phospholipids, chiefly phosphatidylserine, are necessary for the optimal activity of tissue factor and completion of the clotting process. They display a(More)
Microparticles are released during in vitro platelet activation and have been detected in vivo in several pathologies. Their characterization is of interest as they may play a potential role in hemostasis. Here, we report the formation of microparticles as the result of increases in intracellular Ca2+ brought about by inhibition of Ca(2+)-ATPases. They were(More)
We have used flow cytometry to compare the temporal relationship between cytoplasmic Ca(2+)-fluxes and micro-vesiculation during platelet activation. Changes in fluorescence of the Ca(2+)-dye, fluo-3, and in forward light scatter as a measure of the decrease in platelet size that accompanies micro-vesiculation, were assessed simultaneously. In other(More)
Our study investigated the effect of the antithrombotic drug clopidogrel (75 mg/d for 7 days) on the ultrastructure of platelet aggregates induced by ADP or 2-methylthio-ADP (2-MeS-ADP) in citrated platelet-rich plasma and examined the activation state of the GP IIb/IIIa complexes. Results were compared with those obtained for patient M.L., who has a(More)