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Neonatal hypophysectomy in chicken produces enlarged follicles of the thyroid gland, accumulation of colloids, impressed follicular epithelium, increased nucleus-cytoplasm ratio in thyrocytes, atrophied inter-follicular epithelium, depressed immunity, development of hypercoagulation and depressed fibrinolysis. When hypophysectomy is performed in one-year-old birds the impairments developing in thyroid morphology, immunity and hemostasis are less pronounced. Peptides of the anterior (Lys-Glu-Asp-Gly) and posterior (Ala-Glu-Asp-Gly) thyroid lobes injected to hypophysectomized birds prevent atrophic changes of the thyroid gland, normalize immune and hemostatic parameters.

Effects of recombinant interleukin-1 (IL-1) involved an inhibition of adhesion and thrombocyte aggregation. In heparinised blood, the IL-1 activates production of protein C (PnC), alpha 2-macroglobulin (alpha 2-MG) and alpha 1-antitrypsin (alpha 1-AT) and facilitates formation of the fibrinolysis inhibitors. In fibrinolysed blood, the IL-1 suppresses production of PnC, alpha 2-MG, alpha 1-AT, and inhibits the fibrinolysis. In a blood clot, the IL-1 suppresses production of PnC, alpha 2-MG, alpha 1-AT and activates the fibrinolysis.

An original method was used to isolate polypeptides from citrate platelet-free plasma of healthy subjects. These polypeptides were able to prolong recalcification, kaolin, kaolin-cephalin and prothrombin plasma time, sharply reduce thrombin time of standard and heparinized plasma, to inhibit fibrin self-building and stimulate fibrinolytic activity of blood. An antiheparin effect of polypeptides in adequate doses is similar to that of protamine sulfate. Polypeptide antiheparin plasma factor has molecular mass about 2000 D, its chromatographic profile coincides with that of protamine sulfate.

Hypercoagulation and fibrinolysis inhibition are seen in adult rats 6 to 6 1/2 months after thymectomy. Hemocuagulation accelerating is caused by the shortened 1st phase of the blood coagulation process. Fibrinolysis delay is partially produced by a decrease in the fibrinalytic agent concentration and smooth elevation of the antiplasmin level. The most part of the coagulogram indices and fibrinolysis activation returns to normal in operated animals following the injection of a low-molecular polypeptide thymic factor within 5 days.

Experiments on rats have shown that thymectomy brings about the development of hypercoagulation and inhibition of fibrinolysis. Heterotransfusion is accompanied by hypocoagulation and stimulation of fibrinolysis in both intact and thymectomized rats. At the same time fibrinolysis in thymectomized rats is stimulated to a lesser degree than in intact animals. Preinjection into thymectomized rats of the thymus low-molecular factor thymaline over one week does not only make blood coagulation and fibrinolysis return to normal but also leads to adequate changes in the hemostatic system in response to heterotransfusion.

An effective way of inducing high fibrinolytic potential in the thrombus area by streptase-containing leucocytes has been suggested. Leucocytes were incubated with streptase and then placed in the solution containing a fibrin clot, the latter pre-treated with anti-fibrin serum. In these conditions the rate of fibrinolysis increased drastically. The authors believe that fibrinolysis is initiated by the interaction of activated leucocytes via Fc-receptors with fibrin and the release of endo- and exogenic fibrinolytic proteases.

Experiments were made on 20 cats to show that within the first minutes intravenous administration of thrombin led to the enhancement of blood coagulation, an abrupt lowering in fibrinogen concentration, growth of antithrombin III activity and inhibition of fibrinolysis. 30-60 minutes after thrombin injection there developed a secondary hypocoagulation accompanied by the increment of the level of natural anticoagulants and by drastic enhancement of fibrinolysis. In animals given timalin in a dose of 2 mg for 5 days, the injection of thrombin produced a more remarkable increase in blood fibrinolytic activity.

It was discovered in experiments on thymectomized rats that the animals developed hypercoagulation due to the shortening of prothrombinase formation time and to the inhibition of total and Hageman-dependent euglobulin fibrinolysis 2-3 months after the operation. As compared to the intact animals, administration of histamine to the thymectomized animals led to unbalance between marked acceleration of blood coagulation and a comparatively insignificant activation of fibrinolysis. This was one of the main causes of the death of the operated on animals. Low-molecular thymus factor--thymaline--not only abolishes the shifts on the part of the hemostatic system in the thymectomized animals but also recovers adequate responses of the blood coagulation and fibrinolysis systems to histamine administration, thereby contributing to the life preservation of the experimental animals.