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Prostaglandin E2 (PGE2) is produced by activated platelets and by several other cells, including capillary endothelial cells. PGE2 exerts a dual effect on platelet aggregation: inhibitory, at high, supraphysiologic concentrations, and potentiating, at low concentrations. No information exists on the biochemical mechanisms through which PGE2 exerts its(More)
Granules containing acid hydrolases have been detected in human platelets but have not been thoroughly characterized. We have studied the activity and characteristics of glycohydrolases present in normal human platelets, evaluated their release upon stimulation with thrombin, and assessed the contribution of platelet - released lysosomal contents to the(More)
Washed intact human platelets were prelabelled with [3H]arachidonic acid ([3H]AA) and stimulated with thrombin or with AlF4-, a known unspecific activator of G-proteins. Both stimuli induced the liberation of [3H]AA, the release of beta-thromboglobulin (beta-TG) and platelet aggregation. PMA did not induce liberation of [3H]AA although it induced beta-TG(More)
OBJECTIVE To determine the effect of interferon-alpha for severe, zidovudine-resistant, HIV-1-related thrombocytopenia. DESIGN Prospective, randomized, double-blind, placebo-controlled, multicenter, crossover trial. SETTING Outpatient clinics in Central Northern Italy. PATIENTS 15 sequential patients positive for HIV-1 with platelet counts less than(More)
Exposure of human platelets to U46619, a thromboxane (Tx) A2 mimetic, desensitizes the TxA2/prostaglandin (PG) H2 receptor and sensitizes adenylylcyclase to stimuli, such as PGI2 or PGD2. This phenomenon may occur in vivo in conditions associated with platelet activation. Tx synthase inhibitors produce a rediversion of arachidonic acid metabolism toward the(More)
Glanzmann's thrombasthenia is an autosomal, recessive, inherited haemorrhagic disorder due to the lack of the glycoprotein IIb/IIIa (GP IIb/IIIa) complex of the platelet membrane. The disease is characterized by a prolonged bleeding time and by a severe haemorrhagic mucocutaneous diathesis. The only possible antihaemorrhagic therapeutic measure is the(More)
Picotamide is a dual thromboxane (Tx) A2 receptor antagonist/Tx synthase inhibitor although some observations suggest an anti-vasoconstrictor effect independent of TxA2 inhibition/antagonism. The aim of our study was to assess whether picotamide antagonises vascular contractions induced by different vasoactive substances in vitro. Picotamide inhibited(More)
We studied the prevalence, clinical spectrum and epidemiologic features of thrombocytopenia among 442 (333 male, 109 female) HIV infected patients. Thrombocytopenia was defined as a platelet count < 100,000/mmc and severe if platelet count was < or = 30,000/mmc. Intravenous drug abusers were 83% (369/442). At the first clinical evaluation according to(More)
PROBLEM Our study evaluated the number and function of platelets for thromboxane A2/prostaglandin H2 (TxA2/PGH2) and the platelet response to TxA2 receptor agonists in normal and hypertensive pregnancy. In addition, correlations between platelet membrane lipid composition and TxA2 receptor number and function were evaluated. METHODS Ten normotensive(More)
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