Enhancing the fibrinolytic activity of rt-PA appears to be a difficult task. Both heparin and pure thrombin inhibitors, such as hirudin, have failed to enhance the fibrinolytic activity of rt-PA. Third-generation plasminogen activators, hybrids and mutants of t-PA and single-chain urokinase plasminogen activator (scu-PA), showed only minor, if any, advantages over rt-PA in terms of…
Discussion This study confirms that thrombolysis is the net result of 2 opposing processes, lysis of preformed fibrin and accretion of new fibrin on the lysing thrombus. In this study, increasing bolus doses of rt-PA were injected into rabbits with experimental venous thrombi, and both fibrinolysis and thrombus growth were evaluated. The results confirmed the…
Results The results of the fibrinolysis experiments are shown in Figure 1. Saline produced 11% ±2% thrombolysis. Increasing doses of rt-PA produced increasing thrombolytic effects. The observed lysis rates were 24% ±3%, 41% ±3%, 66% ±6%, and 81% ±7% for the 4 increasing doses of rt-PA, respectively. These lysis rates would correspond to a final…
The extent of fibrinolysis was calculated 3 h after the injection of rt-PA bolus as the ratio between the radioactivity remaining in the vein segment and that originally incorporated in the thrombus. Efforts were made to avoid overestimation of the fibrinolysis, a common pitfall with this animal model. The cotton swabs, syringes, and needles were…
After 3 h the venous segments containing the thrombi were tied off and split open longitudinally, and the remaining thrombi were removed. The radioactivity of the circulating fibrinogen was estimated from the mean of the blood samples collected at hourly intervals throughout the infusion. The ratio of the radioactivity of the thrombus to that of…
White New Zealand rabbits of both sexes were anesthetized by the injection of sodium pentobarbital (30 mg/kg) via the marginal ear vein. Additional pentobarbital are given when needed to maintain anesthesia. Through a paramedial incision in the neck, the left jugular vein was exposed, isolated, and cleared over a distance of 2 cm. Small side…
Study of Relative Role of Lysis of Preformed Fibrin and Accretion of New Fibrin on Thrombi in Determining Thrombus Size after rt-PA Bolus The aim of this study was to evaluate in a rabbit vein thrombosis model the relative role of lysis of preformed fibrin and accretion of new fibrin on thrombi in determining the…
Thus, reducing thrombus size requires a favorable net balance between lysis of fibrin and accretion of new fibrin on the thrombus. As these 2 processes appear to be concomitant more than sequential, a favorable balance will positively influence the lysis of the thrombus, in addition to reducing the risk of its reextension after thrombolysis.
To date, this possibility appears to be unrealistic. However, it has been postulated that, at least in patients with acute myocardial infarction, hemostatic plugs are likely to be older than the thrombi responsible for the acute occlusion of the coronary artery. Kanamasa et al assessed in dogs whether the relative rate of lysis of fresh…
Indeed, the bleeding time, an index of in vivo platelet function, is prolonged in patients receiving streptokinase or rt-PA, and this prolongation is positively correlated with the hemorrhagic risk. It has been observed, both in vitro41 and in vivo, that plasminogen activators exert a biphasic effect on platelet function. An initial activation step is followed,…
© 2011 - 2024 buy-asthma-inhalers-online.com. All rights reserved.
