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Biomedical subjects

A K Chepurov

Publications and source records attributed to A K Chepurov.

At least 19 recordsLinked to original sources
PubMed2002

[Features of BCG-therapy in treating patients with superficial bladder cancer].

AIM: To specify features of BCG-therapy which may predict effectiveness of the treatment and optimize the treatment regimen. MATERIAL AND METHODS: Intravesical immunotherapy with imuron (a 6-week course) was conducted in 62 patients with superficial cancer of the urinary bladder who had undergone surgical treatment and were prognostically poor. 51 patients of group 1 received maintenance therapy as 3 weekly instillations each 3 months for the first year followed by once in 6 months. 11 patients of group 2 received single monthly instillations. All the patients registered their complaints, measured body temperature with fixation of maximal value. The diagnosis of the recurrence was made with control cystoscopy carried out each 3 months in the first postoperative year and later once in 6 months. RESULTS: Recurrent tumors were observed in 25 (49%) and 7 (63.6%) patients of groups 1 and 2, respectively. Side effects (high body temperature, dysuria and macrohematuria) were reported in group 1 during basic treatment. Side effects occurred also in maintenance. They were more pronounced than in group 2. CONCLUSION: Intravesical BCG-therapy causes cystitis considered a normal reaction to treatment. Fever indicates an inflammatory reaction which is rather a positive sign of immune reaction and may serve a prognostic factor.

BCG Vaccine↗
PubMed1981

[Functional activity of thrombocytes soon after implantation of an artificial heart].

Experiments on calves undergoing implantation of artificial hearts (Soviet models) under extracorporeal circulation were made to examine platelet adhesion and aggregation. It was demonstrated that the increase in platelet adhesion and aggregation set in from the 2nd hour of the artificial heart work and lasted till the end of the experiments. It was discovered that platelet aggregation correlated well with fibrinogen concentration.

Animals↗
PubMed1980

[Thromboresistant properties of hydrophilic gels].

Hydrophilic gels were made using methyl methacrylate and N-vinylpyrrolidon. Simple designs of hydrophilic gels (films, tubes) for the in vitro studying of thromboresistant properties were manufactured. On the base of measurements of blood clotting time, concentration of prothrombin complex factors fibrinogen, heparin, thromboelastography, and thrombocyte adhesion onto hydrogel surface in blood contact; it was demonstrated that a hydrophilic gel consisting of 86 mol% of methyl methacrylate, 14 mol% of N-vinylpyrrolidon and 0.652 mol% of hydrolysed N-vinylpyrrolidon has optimum thromboresistant properties. Thromboresistant was studied in the dogs during 44 operations, in which both the aorta and peripheral vessels replaced by polypropylene prostheses or by Lavsan, modified by the addition of hydrophilic gels, were applied. It was shown that hydrophilic gels decrease thrombogenesis and promote rapid endothelialization and periprosthetic tissue vascularization.

Animals↗
PubMed1980

[Thromboresistant properties of polyelectrolyte complexes based on weak polyelectrolytes].

Thrombogenic resistant polyelectrolyte compositions were obtained on the basis of weak polyelectrolytes used in different quantity proportions. The investigations were performed in vitro on rabbit blood and in vivo on 21 dogs and 5 calves in the conditions of acute and chronic experiments. The optimal compositions of polymers were selected for the implantation. The appropriate polyelectrolyte compositions on the basis of weak polyelectrolytes, and polymers modified by polyacryl acid with polyethylene piperazine (1:1, 2:1, 3:1), were found to be thrombogenic resistant and did not cause any significant blood cells damage. The investigations performed the possibility for their practical application.

Animals↗
PubMed1980

[Thromboresistent properties of hydrophilic gels].

Thromboresistant properties of hydrophilic gels prepared on the basis of copolymers of nitrogen-containing heterocyclic vinyl compounds with vinyl monomers have been investigated. Hydrophilic gels prevent fibrinogen adsorption, activation of procoagulants and adhesion of platelets. Hydrogel surfaces possess selective tropism for plasma albumin. It is believed that the thromboresistant effect of the hydrophilic gels is consequent on the competitive action of plasma albumin. Modification of the gels leads to the improvement of their thromboresistant properties.

Animals↗
PubMed1978

[Interrelationship between contact coagulation, surface charge and roughness].

The negative surface charge and the mechanically even surface were found in vitro to hinder the blood hypercoagulation, fibrin absorption, and thrombocytes hyperadhesion. The surface negative electrical charge of 6--10(-9)Cl/cm2 and the surface of the 9--14th class of mechanical evenness seem to be optimal for prophylaxis of thrombosis at the blood-surface border. The surface negative electrical charge reduces the possibility of thrombosis on mechanically rough surface.

Biophysical Phenomena↗
PubMed1978

[Structural-functional organization of hemostatic clots].

The studies were carried out to verify the hypothesis on the structural-functional organization of the hemostatic clot. For this purpose the influence of the platelets and their aggregate condition on the mechanical properties of the clot was investigated. Redistribution of platelets into aggregated, caused by addition of ADP and mixing, led to the inhibition of the clot retraction. This was reflected in the form of reduction of am on the thromboelastogram. Simultaneous recording of thrombloelastogram, coagulbbogram, and platelet degranulation demonstrated that processes of viscid metamorphosis of platelets and fibrin filaments sedimentation were followed by active clot contraction. The clot is a fibrin-platelet structure whose nodes contain blood platelets, and cells--the rest blood elements. The clot retraction takes place due to contractile properties of platelets.

Adenosine Diphosphate↗
PubMed1977

[Blood coagulation upon contact between blood and polymeric materials possessing electretic protperties].

Hemocoagulation peculiarities were studied on polymeric materials with the electretic properties. Negative polarity of the electretic polymeres promoted fibrinogenemia and hypoadhesia of platelets in comparison with the electretic materials with positive polarity and polymeres possessing no static electricity. It is supposed that fibrin sorption and platelet hyperadhesion played the main role in thrombogenesis on implanted polymeres.

Blood Coagulation↗
PubMed1977

[Influence of cation dyes on blood coagulation].

Experiments on rabbits showed that intravenous injection of dyestuffs of the thionine series (toluidine blue, azur A, 1:9 dimethylene blue) was accompanied by hypofibrinogenemia, a decrease in the concentration of prothrombin complex factors, thrombocytopenia and the lowering of the blood platelets adhesion against the background of delayed blood thrombogenesis. The blood heparin tolerance and the amount of free heparin were sharply lowered. The authors consider that the hypocoagulative effect of cationic dyestuffs on the blood was caused by the thrombocytopenia and by the lowering of the platelet aggregation activity.

Animals↗
PubMed1975

[Characteristics of hemocoagulation in different periods of the development of a venous intravascular thrombus].

Experiments were conducted on rabbits. A study was made of peculiarities of blood coagulation and of the functional changes in platelets at the period of the thrombus organization, and also at various stages after its formation in the femoral vein. It appeared that at the period of the thrombus formation and during the first 5 minutes after its organization there occurred hypercoagulation changes in the blood and hypocoagulation of the plasma against the background of decrease in fibrinogen, hyperfibrinolysis, hyperheparinemia and thrombocytopenia. One to three days after the thrombosis of the femoral vein the blood hypercoagulation capacity becomes less pronounced. At this time thrombocytosis, an increase in fibrinogen content, hypoheparinemia and inhibition of fibrinolysis are observed. In the authors' opinion, hemocoagulation changes in venous thrombosis were chiefly caused by the hypercoagulation activity of the blood formed elements.

Animals↗
PubMed1975

[Adhesion of blood platelets to electric-featuring polymers].

The authors studied the effect of electric potential arising on the plastic surface upon the blood clotting process. The study was performed according to the Breddin method. The study concerned fluorosilicone rubber, fluoroplast, polyester, polyethylene and polyvinyl chloride with various surface potentials. The authors found that the negatively charged blood platelets adhere to negatively charged plastic surfaces only to a low extent and undergo no disintegration and agglomeration. To the surfaces of the same plastics being electrically neutral, only small aggregates of blood platelets adhere. On the other hand, on the positively charged surfaces the accumulation of blood platelets takes place with concurrent aggregation and disintegration, thus initiating the thrombus formation. The authors observed the intensity of these changes using blood platelet adhesion index and fluorescence microscope.

Blood Coagulation↗