Thrombosis et diathesis haemorrhagica最新文献

Continuous observations in shcool terms have been made on the frequency of spontaneous bleeding episodes in a group of adolescent boys suffereing from haemophilia (39 cases), Christmas disease (9 cases), and von Willebrand's disease (2 cases). The observations suggest that in haemophilia other factors, besides the deficient factor VIII, affect the bleeding frequency. In the two boys with von Willebrand's disease, the lower level of factor VIII was associated with the milder symptoms; whereas in boys with Christmas disease clinical severity and laboratory results seemed to be correlated.

Twenty two patients (12 males and 10 females) from all over Israel fulfilled the criteria for establishing the diagnosis of Glanzmann's thrombasthenia. All have been observed to have a servere bleeding tendency since infancy or early childhood. In 8 out of 10 adult patients (7 females and 3 males) the bleeding manifestations have persisted over the years. In 2 adult patients major surgery was performed under platelet transfusions which appeared to prevent excessive bleeding. Pedigree analysis was possible for 21 patients who belong to 13 unrelated kindreds. Twelve kindreds are Jewish and one is Arab. Eleven of the 12 Jewish kindreds belong to the Iraqi Jewish community. Analysis of 16 sibships disclosed a corrected segregation ratio of 0.2, which is compatible with an autosomal recessive mode of inheritance. No bleeding manifestation whatsoever were observed in 30 obligatory carriers of thrombasthania, and the haemostatic functions tested in 12 of them were entirely normal.

Thrombin, while reacting in the presence of hepatin, impairs the inhibitory capacity of antithrombin III so that subsequent inhibition of thrombin or factor Xa is decreased or abolished. This adverse effect of hepatin has been observed directly with at least 1.5 Iowa units of thrombin per each unit of purified human antithrombin III participating in the reaction. The inhibitory capacity was then totally destroyed and some residual thrombin remained in the active form. With a lower enzyme/inhibitor ratio inactivation of thrombin in the presence of hepatin was fast and complete, however, a significant decrease of inhibitory capacity below that found in reaction without heparin, has been established by measuring the residual antithrombin III activity. In defibrinated human plasma at least 2 units of thrombin per each antithrombin III unit were required to demonstrate directly the adverse effect of heparin but a fast depletion of inhibitory capacity has been also observed after repeated additions of small thrombin portions into plasma heparinized in vitro or in vivo. Portions of enzyme initially added disappeared with great velocity; subsequent portions, however, accumulated building up a high thrombin level not seen in the absence of heparin. The accumulation of residual enzyme was more extensive in plasma containing about 1 heparin unit per ml than anticoagulant at lower concentrations and was particularly noticeable in antithrombin III deficient plasma. These results may have some bearings on the approach to heparin therapy in the event when thrombin continuously generates or when a marked deficiency of antithrombin III exists.

The formation of platelet aggregates which embolize to the peripheral circulation has previously been noted as a significant deleterious effect resulting from both intra- and extracorporeal artificial circulatory devices. Utilizing the stagnation point flow experiment, which permits visualization during flow of aggregate formation on first contact of blood with an artificial surface, the formation of freely floating aggregates has been observed in separated flow regions. Embolization from the separated flow has also been noted. Comparison of observed growth rates with a hydrodynamic model suggests that sufficient activation has occurred within the separated region so that platelets stick on virtually every collision. Some criteria are also suggested which correlate with the flow conditions affecting aggregate formation. At high flow rates, where freely floating aggregates do not form, significant surface thrombi are found.