Effect of cigarette smoking on endothelial cell functions and platelet vessel wall interaction

To study the effect of smoking on endothelial cell function and platelet vessel wall interaction, plasma plasminogen activator [tPA] [chromogenic substrate] were estimated, plasminogen Willebr and factor [vWF] antigen level, as well as platelet counts and skin bleeding time [template method] in 50 male heavy smokers [more than 20 cigarettes per day]. Fifty healthy nonsmokers served as the control group. The tPA activity and vWF antigen levels were significantly increased, and a more pronounced increased in PAI activity was observed in smokers than in the control group. No significant differences were recorded in the platelet count of the smoking and nonsmoking subjects. The skin bleeding time showed significant negative correlation with number of cigarettes smoked per day. Therefore, it seems enhanced platelet adhesion and disturbed endothelial fibrinolytic function may be responsible for the association of cigarette smoking with atherosclerosis and cardiovascular disease

Circulating platelet aggregates indices and coagulation profile in pre-eclampsia

Variable hemostatic parameters were investigated in 30 preeclamptic women [classified into mild and severe cases] and in 15 normal healthy pregnant women. Each was subjected to the following: BT, CT, PT, PTT, FDPs, plasma fibrinogen platelet count and detection of circulating platelet aggregates indices. In cases of mild preeclampsia, a highly significant prolongation of BT, reduction of platelet count, increase in plasma fibrinogen, FDPs and decrease in the circulating platelet aggregates indices were found. In cases of severe preeclampsia, the following was detected: A highly significant prolongation of BT, CT, PTT, reduction in plasma fibrinogen level, platelet count and in the circulating platelet aggregates indices. Significant increase in FDPs and prolongation of PT were also found. In conclusion, increased circulating platelet aggregates indicating platelet hyperactivation were found in preeclampsia. Fibrinogen level was found to be the basic indicator for the degree of compensation in preeclampsia as most cases with low fibrinogen had a bleeding tendency

Platelet dysfunction in malaria.

Platelet function tests including platelet aggregation, PF3, bleeding time and clot retraction were studied in 48 malarial patients. The suppression of platelet aggregation was demonstrated in both P. vivax and P. falciparum infection. However, this abnormality was more prominent in malarial patients who had systemic complications and bleeding. The recovery of the impaired platelet aggregation was observed at period of 7 and 14 days after parasitemia in malarial patients without and with systemic complications. The correlation between the suppression of platelet aggregation and thrombocytopenia was observed. From this study, bleeding in malaria are operated by two mechanisms: thrombocytopenia and severely depressed platelet aggregation.