Along with this there was a significant reduction in circulating platelet aggregates.

Other authors found similar findings with regard to circulating platelet aggregates.

The above studies have attempted to assess the presence of circulating platelet aggregates.

The platelet aggregates formed in this way are fixed with formol.

Therefore the platelet-aggregate ratio would be low in the presence of circulating platelet aggregates.

Formalin fixes platelet aggregates which would be removed during the centrifugation to produce platelet-rich plasma.

With watershed strokes, platelet aggregates block the small meningeal arteries in watershed regions creating a microembolism.

These authors attempted to assess platelet function in citrated whole blood by determining the platelet aggregates formed following electromagnetic agitation for 15 minutes.

Platelets aggregate, or clump together, using fibrinogen and von Willebrand factor (vWF) as a connecting agent.

The relative contribution of platelet aggregates or atheromatous material to distal embolization and vessel occlusion in native coronary arteries is unclear.

Gryglewski et al(1978) incorporated collagen strips into extracorporeal circuits in animals and showed that prostacyclin brought about disaggregation of platelet aggregates formed on the collagen strips.

Large platelet aggregates and high molecular weight vWF multimers are removed from the circulation resulting in thrombocytopenia and diminished or absent large vWF multimers.

He has pointed out that platelet aggregates grow very rapidly and, although platelet adhesion to collagen is almost instantaneous, there is a lag period (several seconds) before aggregation proceeds (Wilner et al, 1969).

This technique has proved sensitive enough to detect pathological embolic materials such as thrombus, atheroma, and platelet aggregates, and the characteristics of the resulting signal provide information on the size of the embolus.

The platelet aggregate ratio as described by Wu and Hoak (1974) depends on the ratio of the platelet count performed on platelet-rich plasma derived from blood mixed with formalin to that in platelet-rich plasma prepared without formalin.

No significant differences were seen with the higher dose of collagen (5 μg/ml), probably because the impedance aggregometer is more sensitive to smaller platelet aggregates than to the larger aggregates which would have been induced by the high-dose collagen (Ingerman-Wojenski et al, 1982).

It has been shown that somatostatin ha sno effect on haemostasis, and particularly on platelet aggregation, with clinical doses of 250 and 500 g/h in non-diabetic subjects; only with a higher dose (750 g/h) were circulating platelet aggregates detected.