Thrombosis et diathesis haemorrhagica最新文献

The uptake and binding of antimitotic alkaloid colchicine has been demonstrated in washed preparations of human pletelets. A silicone oil technique was adapted so that both uptake and binding of 14C-colchicine were examined in the same platelet preparations. The time dependence and amount of colchicine taken up and bound by different pletelet preparations during a 90 to 120 min incubation period were highly reproducible. Both colchicine uptake and binding by intact platelets, and colchicine binding by preparations of lysed platelets were specific and temperature dependent. Colchicine uptake was slowly reversible. Magnesium and GTP enhanced colchicine binding by lysed platelet preparations but calcium decreased binding. exposure of platelets to either cold (4 degrees C) or to thrombin, which disrupt platelet microtubules, produced significant increases in colchicine uptake and binding. The thrombin effect was maximal at 37 degrees C and resulted in a greater increase in uptake and binding than that produced by either cold treatment alone or, by cold treatment followed by incubation with thrombin at 37 degrees C. The amount of increase in uptake and binding produced by thrombin was independent of both thrombin (1--5 Units/10(9) platelets) and colchicine concentrations (1--50 X 10(-6) M). It is postulated that thrombin may initiate the formation, or make available, colchicine binding sites (microtubule subunits) within platelets.

The formation of fibrin clots or circulating soluble fibrin is accompanied by the appearance of fibrinopeptides. Measurement of the fibrinopeptide concentration in plasma can provide important information on the rate of conversion of fibrinogen to fibrin by thrombin. This rate varies under different physiologic and pathologic conditions. Fibrinopeptide A is a better molecular marker of the conversion than fibrinopeptide B since it is the first peptide to be cleaved by thrombin. A radioimmunoassay technique has been developed for the quantitative determination of human fibrinopeptide A. The procedure detects human fibrinopeptide A at a concentration of approximately 0.05 ng/ml. The variation of fibrinopeptide A content in normal persons may reflect its rapid formation and catabolism. A significantly increased concentration of this peptide was found in a patient during defibrination therapy with a purified enzyme from the venom of Agkistrodon rhodostoma and in patients suffering from retinal vascular occlusions.

The presence of fetal red cells in the maternal circulation and the serum FDP content of 73 women was followed serially throughout a normal pregnancy. There was a signigicant increase in the mean serum FDP levels in late pregnancy, which was due to episodic elevations occurring in approximately 65% of women. These transient elevations appeared to increase in frequency and severity as pregnancy progressed. There was also an increase in the number of occasions fetal red cells were detected in the maternal circulation in the later months of pregnancy, but his phenomenon did not appear to be associated in any way to the serum FDP elevations. It is concluded that the episodic rises in serum FDP occurring in normal pregnancy are not related to episodes of occult disseminated intravascular coagulation secondary to placental haemorrhage as was previously hypothesized. Their etiology and clinical significance remain unknown.

Collagen-induced platelet aggregation is associated with the release of ADP and the catabolism of radioactive ATP. These studies demonstrate that the amount of human platelet ADP released and ATP catabolized increase with time of stirring of the collagen-platelet rich plasma (PRP) mixture and with increasing amounts of collagen. These changes in adenine nucleotides occurred simultaneously with the aggregation. No early changes preceding aggregation were noted. Stirring the collagen-PRP mixture maximized ADP release and ATP catabolism; some ADP release and ATP catabolism occurred with minimal agitation. Incubation of PRP with metabolid poisons (2-deoxyglucose with either KCN or oligomycin), which lowered platelet ATP content, also reduced collagen-induced release of ADP and aggregation. However, platelet adhesion to collagen was unaffected by metabolic poisons. These data suggest that collagen directly stimulates ADP release. The demonstration of release in EDTA-PRP further suggest that platelet aggregation is not required for collagen-induced ADP release.

The potato protease inhibitors inhibit intrinsic prothrombin activators and trypsin activation of prothrombin. The inhibitors 5a and 5b are responsible for the intrinsic prothrombin activator inhibition. This inhibition is progressive. No inhibition by these inhibitors of tissue thromboplastin activation of prothrombin or thrombin activity was observed.