Nonenzymatic fibrinolytic reaction to the intravenous administration of small doses of Salmonella endotoxin to rabbits

Intravenous injection of a low dose of Salmonella endotoxin (10 micrograms/kg bw) into rabbits results in an increase in the non-enzymatic fibrinolytic activity of blood at early stages of a pathological process followed by depression of this response at later stages of the pathology. At higher degrees of non-enzymatic fibrinolysis activation the morphological and ultrastructural changes in renal tissues caused by endotoxin injection are the least pronounced. Intravenous injection of heparin after injection of a lethal dose of Salmonella endotoxin (100-200 micrograms/kg) enhances non-enzymatic fibrinolysis activation and decreases the morphological and ultrastructural lesions in renal tissues.     

Process of fibrin depolymerization and non-enzymatic fibrinolysis in rabbits receiving atherogenic rations with addition of antioxidants

The rabbits were kept on atherogenic ration for 2 months. This diet contained 0.3 mg/kg of cholesterol. In blood plasma of animals the authors observed a sharply reduced non-enzymatic fibrinolysis and depolymerization activity of non-stabilized fibrin. The addition of antioxidants and alpha-tocopherol (10 + 10 mg/kg) for 1 month to the atherogenic ration protected from the disturbance of the system hemostasis and normalized the depolymerization of non-stabilized fibrin.     

Fluctuations in pulmonary fibrin decomposing activities (plasmin and non-plasmin activities) in an endotoxin DIC model in rats

Non-plasmin fibrinolysis enzyme was extracted from the lung and spleen of conventional rats (Thrombos. Haemostas., 1979), although the enzyme was not found in germfree rats, suggesting the possibility that the enzyme may participate in the defence mechanism of the body. The present study was made in an attempt to determine the behavior of non-plasmin fibrinolysis enzyme of the lung tissue in the DIC model of conventional rats induced by a single injection of bacterial endotoxin. The plasminogen-activator activity of the lung tissue, and the fibrinogen level, platelet count, urea nitrogen and plasminogen-activator activity in the blood were also measured. Examination of the lung tissue in the DIC rats indicated a remarkable increase in non-plasmin fibrinolysis activity and a disappearance of plasminogen-activator activity. Inhibitor studies using t-AMCHA and DFP demonstrated that the increased non-plasmin fibrinolysis activity was not derived from activated plasmin, but from serine protease. The disappearance of plasminogen-activator activity in the lung and increase of plasminogen-activator activity in the blood suggested a release of the activator from the lung into the blood due to the endotoxin injection.     

The contribution of leukocyte proteases to fibrinolysis

Polymorphonuclear leukocytes accumulate within blood clots and may contribute to fibrinolysis. The primary fibrinolytic enzymes of neutrophils are cathepsin G and elastase. Fibrin can be exposed to these granular enzymes as a result of cell lysis, phagocytosis of fibrin, or secretion of the enzymes from the cells. Neutrophil secretion occurs in association with blood coagulation and is dependent upon a plasma factor(s) and calcium. After secretion, the enzymes can degrade fibrin within a plasma environment. This is demonstrated by the inhibition of fibrinolysis by specific inhibitors of elastase and the augmentation of fibrinolysis by neutralization of the primary plasma inhibitor of elastase, alpha 1-proteinase inhibitor. A radioimmunoassay which discriminates elastase from plasmic degradation products of fibrinogen has been developed. In this assay, elastase elicited degradation products of fibrin(ogen) were detected in certain pathophysiologic plasma samples. Taken together, these findings indicate a role for leukocyte proteases in physiological fibrinolysis.     

Effect of thymalin and heterotransfusion on blood coagulation and fibrinolysis in thymectomized rats

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.     

Clinical studies on the fibrinolytic action of pentosan polysulfate

The influence on fibrinolysis of the heparin-like substance Polyanion SP 54 is described. In vitro tests showed an increase of fibrinolysis by activation of the endogenous pathway via factor XII and prekallikrein. In vivo an increase of the availability of tissue plasminogen activator was assumed in addition. When different ways of administration of Polyanion SP 54 were tested an enhancement of fibrinolysis was also found after oral application of the substance. In a long term test the stimulation of fibrinolysis after oral therapy did not diminish within 12 months. A trial on patients with cerebral ischemic attacks and diminished fibrinolysis is not yet concluded but permits the assumption of a considerable diminution of ischemic attacks during therapeutic use of Polyanion SP 54.     

Usefulness of human coagulation and fibrinolysis assays in domestic pigs

Pigs are often used as animal models in research on blood coagulation and fibrinolysis. The usefulness of the assays applied within this field, and the knowledge of reference intervals are therefore essential and of utmost importance. In the study reported here, we investigated the applicability of commercial human coagulation and fibrinolysis assays for use with porcine plasma. In total, 22 functional and immunologic assays were applied to plasma obtained from domestic pigs, and the following blood coagulation and fibrinolysis variables were measured: prothrombin time, activated partial thromboplastin time, tissue factor, tissue factor pathway inhibitor, factor VII, protein C, protein S, prothrombin fragment 1+2, antithrombin, thrombin-antithrombin complexes, fibrinogen, soluble fibrin, urokinase-type plasminogen activator, plasmin inhibitor, plasminogen activator inhibitor 1, and D-dimer. We found that 11 of 12 functional assays, but only 3 of 10 immunoassays, were applicable to porcine plasma, and we determined the normal range of these variables. We conclude that human functional assays are useful in porcine plasma, whereas only a few immunologic assays can be used. However, precautions must be taken in interpretation of the results and in extrapolation toward human results because possible differences between porcine and human values can be due to species variations and/or methodologic errors.     

Depletion of fibrinolysis activators as a result of continuous stress

The dynamics of disorders in haemostasis and fibrinolysis upon continuous stress was studied in model experiments with rats exposed to emotional-pain-stress. It was shown that the plasminogen activator (PA) is released into the blood within the first few minutes of exposure to stress. Four hours after cessation of continuous stress (6 hours) the enzyme depletion and fibrinolysis depression occurred. Such stress-induced changes in the blood system function can be regarded as a risk factor in the development of thrombosis.     

Effect of methanol-induced oxidative stress on the neuroimmune system of experimental rats

It is well known that the nervous system has increased susceptibility to methanol intoxication. The present study reveals the effect of methanol intoxication on antioxidant status, lipid peroxidation and DNA integrity in hypothalamic-pituitary-adrenal (HPA) axis organs and spleen. Non-specific and specific immune functions were analyzed. In addition, open field behavior, plasma corticosterone level and blood methanol level were estimated. Male Wistar albino rats were intoxicated with methanol (2.37 g/kg b.wt., i.p.) for 1 day, 15 and 30 days. Administration of methanol showed significant increase in enzymatic (superoxide dismutase, catalase, glutathione peroxidase), non-enzymatic (reduced glutathione and Vitamin C) antioxidants and lipid peroxidation (LPO) in hypothalamus and adrenal gland of day 1 group. However, decrease in enzymatic and non-enzymatic antioxidants with concomitant increase in LPO level were observed in 15 and 30 days groups. Plasma corticosterone level was significantly increased in day 1 and 15 days groups whereas, 30 days methanol intoxication group showed considerable decrease in corticosterone level compared with control animals. Cell-mediated immune response of footpad thickness was significantly decreased with an increased leukocyte migration inhibition. Humoral immune response of antibody titers was elevated in methanol-intoxicated groups. Neutrophil functions, adherence and phagocytic index (PI) were found to be significantly decreases. Furthermore, significant increase in the avidity index and nitro blue tetrozolium reduction was observed in the methanol exposed animals. Day 1 methanol exposed group showed increased PI compared to the control ones. Methanol exposure for 30 days showed an increased DNA fragmentation in the hypothalamus, adrenal glands, and spleen. In conclusion, exposure to methanol-induced oxidative stress disturbs the HPA-axis function altering the level of corticosterone, which lead to varied non-specific and specific immune response in experimental rats.     

Constitutional features of the reaction of the hemostatic system to a physical load

This study involves 72 young men with various levels of working efficiency and elucidates the relationship between human morphological constitution by the type of age-related evolution of the organism and parameters affecting hemostasis. As suggested by V.G. Shtefko, the measured value of the trochanteric index (TI) is compared to the reaction of the hemostatic system to graded moderate veloergometric load. It was found that decreased coagulability and activation of fibrinolysis take place in untrained men with high TI values in response to a load, while stimulation of blood coagulation and inhibition of its fibrinolytic activity occurs in men with low TI values. There is a significant correlation between the TI value and reaction of the hemocoagulation system to a load. Under the impact of a load, hemocoagulation and fibrinolysis are stimulated in persons with a relatively high working efficiency and high TI values, and coagulation is inhibited and fibrinolysis is more often stimulated in those with low TI values. Our conclusion is that a more favorable and stable response of the hemostatic system to a physical load takes place in subjects with the normo- and hyperevolutive constitutional types in conditions of both low and relatively high working efficiency levels. Low TI values, combined with low working efficiency level, are a risk factor for the development of thromboembolism complications in men, and these may be provoked by physical activity.     

The biological significance of non-enzymatic reaction of menadione with plasma thiols: enhancement of menadione-induced cytotoxicity to platelets by the presence of blood plasma.

To test the hypothesis that the non-enzymatic reaction of quinones with thiols in plasma can generate reactive oxygens (ROS), thereby leading to potentiated cellular toxicity, we have studied the effect of a representative quinone compound, menadione, on plasma isolated from rats. The experimental results are as follows: (1) menadione generated ROS via non-enzymatic reaction with protein thiols in plasma; (2) the presence of plasma increased menadione-induced cytotoxicity to platelets; (3) pretreatment of plasma with a thiol-depleting agent significantly suppressed menadione-induced ROS and cytotoxicity. These results suggest that the non-enzymatic reaction of menadione with plasma thiols could be an important process in quinone-induced cellular toxicity.     

Magnetoelastic transducers for monitoring coagulation, clot inhibition, and fibrinolysis

Magnetoelastic transduction has been used to detect and monitor the viscosity changes that occur during the biological reactions of coagulation and fibrinolysis. Magnetoelastic sensors can be used, because the characteristic resonance frequency of the magnetoelastic strip shifts in response to the changes in fluid viscosity. At a set frequency, the output signal can be obtained over time to develop a coagulation and/or dissolution profile, which display the change in viscosity of a plasma sample that has undergone either coagulation or fibrinolysis. For coagulation screening, an exogenous tissue factor is added to an anticoagulated plasma sample to initiate coagulation. Further studies were performed to investigate fibrinolysis through the addition of plasmin. Plasmin is used in two different ways-as a competitive inhibitor before the initiation of clotting and also as a protease to dissolve the previously formed clot. This method is a viable option for the monitoring of processes that are paramount to maintaining hemostasis.     

A novel growth factor in rat spleen which promotes proliferation of hepatocytes in primary culture

We have identified a factor from adult rat spleen which stimulates the proliferation of rat hepatocytes. The activity was found in the spleen soluble matrix fraction (1,300xg supernatant of inter-cellular fraction). No activity was found in the spleen cell homogenate, in the spleen insoluble matrix fraction or rat serum. After 4 days of incubation with the spleen factor, the cell number increased 4-fold higher than that at inoculation. The growth stimulation were observed in both fetal bovine serum supplemented medium and hormonally defined medium which contains insulin, epidermal growth factor, glucagon, growth hormone and prolactin. The level of activity in the spleen soluble matrix was not affected by partial hepatectomy or trypsinization. These data indicate that the spleen factor is different from previously characterized effectors of hepatocyte proliferation. The novel factor has been named spleen derived growth factor (SDGF).     

The state of hemolysis under the effect of a noninfectious natural stressor with a deficit of insulin

An influence of animals immobilization with lack of insulin on the condition of systems depended on factor XII was investigated on the experiments under forty-five rabbits. It was determined that the immobilization causes deep violations in the "polysystem" of factor XII that was expressed in discordance of processes of coagulation, fibrinolysis, kininogenesis.     

Deep venous thrombosis of the arm: a study of coagulation and fibrinolysis.

Sixty consecutive patients with phlebographically verified deep venous thrombosis of the upper arm were studied for disorders of coagulation and fibrinolysis. No appreciable increase in abnormalities of the factor VIII complex, antithrombin III, or inhibitors of activators of fibrinolysis were found. A decreased fibrinolytic defence mechanism, evident either as a deficient release capacity of fibrinolytic activators from the vein during stasis or as decreased fibrinolytic activity in the vein wall as determined histochemically, was found in 26 out of 53 patients studied (49%). It is concluded that deep venous thrombosis of the upper arm is a multifactorial disease. An impaired fibrinolytic defence mechanism is one of the factors that may be of pathogenetic importance.     

Effect of the thymus on the activity of immunoreactive peptides

Influence of the thymic gland on the biology activity of peptide mediators--cytomedins, has been studied in the content of different organs. The peptide which was obtained from the liver, spleen and muscle of sham-operated animals enhanced immune response on the sheep red cells, lengthened indexes of thromboelastography, and activated fibrinolysis after its administration to the thymectomized rats. The peptides from organs of thymectomized animals lost this ability. These findings confirm the hypothesis on the regulating function of the thymic gland in the synthesis and activity of cytomedins in the tissues.     

Pathophysiology of thrombophilic states

The coagulation system can be considered as a balance in which clotting and fibrinolysis have to be in a state of equilibrium. Increased fibrin formation or decreased fibrinolysis can predispose to thromboembolic diseases. Derailments in the clotting system leading to thrombosis center around the regulatory mechanisms, antithrombin III, protein C, protein S and possibly heparin cofactor II. Many cases of congenital or acquired deficiencies or abnormalities or antithrombin III, protein C and S have been described, all predisposing to thrombotic events. Alterations of the fibrinolytic system can also be associated with thromboembolisms. In particular, abnormalities of plasminogen, tissue plasminogen activator release and elevated tissue plasminogen activator inhibitor levels seem to be associated with thromboses. Conceivably also factor XIIa (Hageman factor) and prekallikrein deficiencies, when associated with thrombosis, exert their mechanism through the fibrinolytic system. Finally, about 50% of patients with lupus anticoagulant seem to suffer from thromboembolic disorders. The pathophysiology of this particular association is not known with certainty. Undoubtedly, there will be more disturbances discovered in the hemostasis system that are associated with increased intravascular fibrin formation. The understanding of these derailments is at this time only in its earliest stages of development.     

The vascular wall and fibrinolysis--pathologic aspects

The plasminogen activating factor of tissue detectable by fibrinolysis autography is diminished in varicosis with and without postthrombotic syndrome, in diabetic nephropathy, in viral pneumonia and after short-term cyclophosphamide therapy. The only condition in which an increase of this factor can be observed is mechanical damage of tissue. The importance of the findings for pathogenesis and therapy is stressed. Whether the results are influenced by inhibitors of extrinsic plasminogen activation is discussed.     

Dynamic changes of fibrin architecture during fibrin formation and intrinsic fibrinolysis of fibrin-rich clots

Clotting and fibrinolysis are initiated simultaneously in vivo, and fibrinolysis usually occurs without any individualized lysis front (intrinsic fibrinolysis). We have developed a novel model to assess whether morphological changes resulting from intrinsic fibrinolysis are similar to those previously reported at the lysis front using externally applied lytic agents. Fibrin assembly and fibrinolysis were followed in real-time by confocal microscopy using gold-labeled fibrinogen molecules. An increase in fiber absorbance (30%, p < 0.01) and a decrease in fiber diameter (60%, p < 0.01) due to the ongoing accumulation and packing of fibrin molecules were the most significant detectable features occurring during fibrin assembly. Similar features with a similar magnitude were observed during fibrin dissolution, but in the reverse order and with a 3-fold increase in duration. Then, lysing fibers were progressively transected laterally, and thinner fibers were cleaved at a 2.5-fold faster rate than thicker fibers (p < 0.001). Frayed lysing fibers were seen to interact progressively with adjoining fibers (agglomeration), leading to a 76 and 88% increase in the network pore diameter (p < 0.05) and fiber diameter (p < 0.01), respectively. At the maximum decrease in fiber absorbance (46%, p < 0.05), the network suddenly collapsed with the release of large fragments that gradually vanished. Morphological changes of fibrin that occur during intrinsic fibrinolysis are similar as those observed next to the lysis front, although they are not restricted spatially to the clot/surrounding milieu interface but are observed through the entire clot.     

Coagulation factors and fibrinolytic system in subretinal liquid in patients with rheumatogenous retinal detachment

The work deals with estimation of some factors of blood coagulation and fibrinolytic systems, which include antithrombin III, factor X, prothrombin, plasminogen, protein C concentrations in the subretinal fluid of the patients with rhegmatogenous retinal detachment retina. The tendency to increase of the blood coagulation and fibrinolysis factor levels, except protein C, was revealed in the patients with complicated forms of the disease. The investigations mentioned above are capable of serving as a diagnostical and forecasting test characterizing the rhegmatogenous retinal detachment retina and surgical treatment proceeding.