SummaryThe morphology of coagula obtained in the cone in cone viscometer is studied in two cases of Waldenstrom’s macroglobulinaemia. Whereas the structures obtained in normal individuals have the features of in vivo thrombosis, the platelet masses usually obtained are not present in the two patients studied. It is postulated that disturbance of platelet aggregation as demonstrated may account for the bleeding diathesis in some cases of Waldenstrom’s macroglobulinaemia.
A controlled trial was undertaken to assess the " Thrombotest " method and compare it to the Quick's one-stage prothrombin time estimation in the patients attending the anticoagulant service of the Royal Prince Alfred Hospital. Two major groups of patients with isch
Summary
A cone‐in‐cone rotational viscometer is used to produce artificial in vitro thrombosis and lysis is stimulated with streptokinase. It is shown that the coagula lyse, but platelet masses in these remain unaffected. The implications of this finding are discussed with regard to the knowledge of platelet aggregation, the theories of vessel wall repair and atherosclerosis and its importance in thrombolytic therapy.
SummaryA study of blood coagulation was carried out by observing changes in the blood viscosity of blood coagulating in the cone-in-cone viscometer. The clots were investigated by microscopic techniques.Immediately after blood is obtained by venepuncture, viscosity of blood remains constant for a certain “latent” period. The duration of this period depends not only on the intrinsic properties of the blood sample, but also on temperature and rate of shear used during blood storage. An increase of temperature decreases the clotting time ; also, an increase in the rate of shear decreases the clotting time.It is confirmed that morphological changes take place in blood coagula as a function of the velocity gradient at which such coagulation takes place. There is a progressive change from the red clot to white thrombus as the rates of shear increase. Aggregation of platelets increases as the rate of shear increases.This pattern is maintained with changes of temperature, although aggregation of platelets appears to be increased at elevated temperatures.Intravenously added heparin affects the clotting time and the aggregation of platelets in in vitro coagulation.
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