Whole blood aggregation and plasma lyso-PAF related to smoking and atherosclerosis

Cigarette smoking increases the mean platelet volume in elderly patients with risk factors for atherosclerosis

To study the effects of cigarette smoking and atherosclerosis on platelet size, we measured the mean platelet volume (MPV) and other platelet parameters in 142 elderly smokers and nonsmokers with or without atherosclerotic risk factors. The MPV and the platelet count were highest and their inverse correlation was strongest in the atherosclerotic smokers (r = 0.54, P < 0.05) when compared with the nonsmoking and non-atherosclerotic groups. A 10% decrease of MPV was found in 8 smoking subjects in the atherosclerotic group, who successfully discontinued smoking (P < 0.05). These results suggest that smoking may increase platelet consumption in atherosclerotic vessels and that subsequently megakaryocytes are activated to produce larger platelets, which are more active. Thus, an increase in MPV due to smoking may also contribute to the acceleration of atherosclerosis and should be considered as a risk factor for atherosclerotic disease.

Platelet-activating factor and P-selectin activities in thrombotic and nonthrombotic Behçet’s patients

OBJECTIVE

The aim of this study was to compare plasma Platelet-activating factor (PAF) and P-selectin (CD62P) activities in Behçet's disease patients with and without thrombosis.

METHODS

In this cross-sectional and descriptive study, 30 consecutive Behçet's patients were included, 15 of them with venous thrombosis. All patients were also divided into two subgroups according to the presence or absence of clinical activity. Plasma PAF levels, basal and Ca++ ionophore (A23187)-induced leukocyte (cellular) PAF activities, and platelet-rich plasma DeltaCD62P activity (the mean fluorescent density difference between CD62P phycoerythrin-positive and -negative stains) were evaluated.

RESULTS

In the thrombotic group, plasma PAF (P=0.001), basal leukocyte PAF (P=0.017), induced leukocyte PAF (P=0.024), and DeltaCD62P (P=0.023) levels were significantly higher than in the nonthrombotic group. In the whole group of Behçet's patients, there was a positive correlation between plasma PAF and DeltaCD62P levels (r=0.533, P=0.002). When we compared clinically active and inactive patients with respect to the above parameters, there was no significant difference, irrespective of thrombosis. Plasma PAF (P=0.001), basal leukocyte PAF (P=0.004), and DeltaCD62P (P=0.038) levels were significantly higher in the presence of both clinical activity and thrombosis than of clinical activity alone.

CONCLUSION

Platelet-activating factor and CD62P may contribute to endothelial injury and thrombosis development in Behçet's disease. These two parameters seem related to the presence of thrombosis rather than clinical activity.

Platelet activating factor acetylhydrolase activity in the urine of patients with renal disease

Platelet activating factor has been demonstrated in blood and urine and has a broad range of effects on kidney function. The kidney possesses the enzymes responsible for PAF synthesis as well as the specific acetylhydrolase which deactivates PAF. We used a radioactive assay to measure PAF-acetylhydrolase activity in urine samples obtained from normal individuals and patients with various nephropathies. Activity was detected in the majority of normal urines with a mean + 2 SD = 0.70 nmol/30 min/ml. Activity exceeding this value was measured in the urines of 11 of 14 patients with diabetes mellitus, 14 of 22 with glomerulonephritis, and 5 of 16 with hypertensive renal disease. Further study is necessary to relate urine hydrolase activity to specific functional and structural abnormalities of the kidney.