In a previous work we have shown that heparin, in the presence of ozone (O3), promotes a dose-dependent platelet aggregation, while after Ca2+ chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor...

A case is reported of a 49-year-old woman with a mild bleeding tendency. Her bleeding time, platelet count and size, plasma ristocetin cofactor activity, von Willebrand factor (vWF) antigen, and vWF multimeric pattern are all within normal limits. Spontaneous platelet aggregation is observed when citrated platelet-rich plasma (PRP) is stirred in an aggregometer cuvette. This aggregation is comp...

Background—After activation, platelets adhere to neutrophils via P-selectin and b2-integrin. The molecular mechanisms and adhesion events in whole blood exposed to venous levels of hydrodynamic shear in the absence of exogenous activation remain unknown. Methods and Results—Whole blood was sheared at '100 s. The kinetics of neutrophil-platelet adhesion and neutrophil aggregation were measured i...

Background: The short life time of human platelet units has led to a chronic shortage of fresh platelets in blood transfusion centers. Many approaches have been investigated experimentally to produce new hemostatically active platelet products that are capable of long term storage. Infusible platelet membrane (IPM) prepared from fresh or outdated human platelets have been developed as an altern...

General Considerations D espite the essential role of platelets in arterial thrombogenesis, personalized antiplatelet therapy based on platelet function tests (PFTs) did not improve clinical outcome after coronary revascularization and did not predict recurrent ischemic or bleeding events in individual patients. To understand why these point-of-care PFTs have yielded so little clinical benefit,...

A method for washing platelets by albumin density gradient separation has been modified to prepare platelet rich plasma of thrombocytopenic patients for platelet aggregation studies. The concentration procedure, consisting of centrifuging platelets into a specific gravity gradient between plasma and 40-45% aqueous solution of bovine albumin, does not affect platelet aggregation adversely. Plate...

Platelet hyperactivity plays an important role in arterial thrombosis and atherosclerosis. The present study was aimed to investigate the effects of different extracts of propolis and components of flavonoids on platelet aggregation. Platelet-rich plasma was prepared and incubated in vitro with different concentrations of the tested extracts and components of flavonoids. Platelets aggregation w...

In this study, we investigated whether (1) collagen-induced platelet aggregation is associated with a burst of H2O2, (2) this oxidant species is involved in the activation of platelets, and (3) the pathways of platelet activation are stimulated by H2O2. Collagen-induced platelet aggregation was associated with production of H2O2, which was abolished by catalase, an enzyme that destroys H2O2. H2...

Von Willebrand factor (vWF) has been implicated to function as a cofactor in platelet aggregation induced by thrombotic thrombocytopenic purpura (TTP) plasma. To investigate further this role of vWF, we have used rabbit monospecific anti-FVIII/vWF antibodies and a monoclonal antibody to platelet glycoprotein lb (GP Ib) that blocks the ristocetin-induced platelet aggregation. The monoclonal anti...

UNLABELLED Background and Purpose- Hyperlipidemia is associated with platelet hyperreactivity. We hypothesized that L-4F, an apolipoprotein A-I mimetic peptide, would inhibit platelet aggregation in hyperlipidemic mice. METHODS AND RESULTS Injecting L-4F into apolipoprotein E (apoE)-null and low-density lipoprotein receptor-null mice resulted in a significant reduction in platelet aggregation...