Modifications in Coagulation Parameters Induced by Treatment Associating Urokinase (2000 u CTA/kg/h) with Heparin

Twenty-nine patients with deep venous thrombosis of the lower limbs were treated for 48 hours by intravenous infusion of urokinase (2000 u CTA/kg/h) and heparin (5 mg/kg/24 h).

Plasma coagulation parameters were measured every 12 hours. After 36 hours of therapy the following results were obtained – decrease in: fibrinogen levels (9% fall), plasminogen (40% decrease), α2-macroglobulin (9% decrease, but no change during the first 12 hours) and fast acting α2-antiplasmin (60% decrease); bidimensional electrophoresis consistently revealed 2 spikes during treatment: the first corresponded to complexed plasmin-fast acting α2-antiplasmin, the second corresponded to free, unconsumed fast acting α2-antiplasmin. Levels of α1-antitrypsin increased by 20% whereas the antithrombin III level remained stable. FDP levels increased slightly. Recalcified plasma coagulation times progressively increased.

Therapeutic results were evaluated on phlebography and showed, after 48 hours urokinase administration, improvement in 6 patients and no improvement in 17 cases. Consumption of plasminogen and production of FDP were both greater in the improved patient group.

The authors discuss these results and suggest that the dosage level of urokinase used in this study should be modified; it is concluded that a therapeutic regimen associating a loading dose with higher hourly administration levels is needed to achieve neutralization of fast acting α2-antiplasmin, a prerequisite to development of thrombolytic activity.

Binding of 99mTc Plasminogen on Fibrin

Binding of plasminogen to fibrin was studied in vitro and in vivo using 99mTc Glu- and Lys-plasminogen.

Binding of Glu-plasminogen on the clot was not observed in vitro, and in vivo in the dog.

Conversely, the binding of Lys-plasminogen to fibrin displays a linear relationship to the concentration of Lys-plasminogen, up to doses exceeding equimolarity; thus suggesting the existence of several Lys-plasminogen binding sites on fibrin. Binding levels were identical, regardless of whether plasminogen was incubated in normal plasma or in plasma devoid of antiplasmin. In the dog, Lys-plasminogen bound specifically to the clot, however, clot sites could not be localized by scintigraphy in the dog or in man.

Binding of 99mTc plasminogen on fibrin

Binding of plasminogen to fibrin was studied in vitro and in vivo using 99mTc Glu- and Lys-plasminogen. Binding of Glu-plasminogen on the clot was not observed in vitro, and in vivo in the dog. Conversely, the binding of Lys-plasminogen to fibrin displays a linear relationship to the concentration of Lys-plasminogen, up to doses exceeding equimolarity; thus suggesting the existence of several Lys-plasminogen binding sites on fibrin. Binding levels were identical, regardless of whether plasminogen was incubated in normal plasma or in plasma devoid of antiplasmin. In the dog, Lys-plasminogen bound specifically to the clot, however, clot sites could not be localized by scintigraphy in the dog or in man.

Effects of insulin on erythrocyte deformability in diabetics--relationship between erythrocyte deformability and platelet aggregation

Erythrocyte deformability was studied by the filtration technique of Reid & Dormandy using whole blood and washed erythrocytes from insulin-dependent diabetics (IDD) under insulin delivery by an artificial pancreas (AP). The same technique was employed to study deformability in vitro using normal erythrocytes incubated in the presence of insulin. Results of this study show that in IDD the initially poor erythrocyte deformability is improved within hours of insulin administration. Improved deformability was accompanied by increased levels of intra-erythrocyte ATP but without changes in levels of HbG and 23 DPG. Incubation of erythrocytes in medium containing glucose showed that deformability was significantly improved in the presence of insulin. These results indicate that insulin favourably affects erythrocyte deformability in IDD. Before and after 24 hours treatment by AP, platelet aggregation was studied in IDD by the technique of Born using platelet-rich plasma (PRP) and by a modified Breddin technique using PRP, whole blood or whole blood treated by chlorpromazine and mixtures of erythrocytes from IDD with normal PRP. Platelet hyperaggregation was only found in the presence of erythrocytes from untreated diabetics. Chlorpromazine, at a dose (10 mumole) which inhibits haemolysis without inducing platelet hyperaggregation, eliminated the above anomaly. In conclusion, it is conceivable that the insulin-induced correction of poor erythrocyte deformability eliminates excessive fragility of erythrocytes and their haemolysis wit release of ADP, thus avoiding platelet hyperaggregation.

[A study of platelet abnormalities in obese subjects (author's transl)]

In 81 obese subjects the following studies were performed: --measurement of fat mass and its distribution in the body, --exploration of carbohydrate tolerance and lipid plasma level, --assessment of platelet aggregation and coagulation activity, --investigation of the chemical composition of platelet phospholipids. Platelet hyperactivity was demonstrated in certain patients, as evidenced by the presence of irreversible platelet aggregation with low doses of aggregation agents and by an increase in platelet coagulant activity; the latter phenomenon was not accompanied by a change in the biochemical composition of platelet phospholipids. Results of this work showed that platelet activity was not related to body weight and displayed no correlation or a slightly negative one to fat mass excess. Platelet activity was significantly increased in cases where obesity predominated in the upper body (hyperandroid obesity). The classical association of diabetes and atherosclerosis with hyperandroid obesity did not allow us to distinguish between the relative importance of hyperandroid obesity and diabetes in the observed platelet hyperactivity. Regardless of the causal mechanism involved, the relationship between platelet hyperactivity and upper body fat excess should be kept in mind.