[The structure and mechanical properties of the human pulmonary trunk and its valves].

The histological structure and mechanical properties of the pulmonary trunk and its valves were studied in 35 complexes of the pulmonary artery of man. The valvular apparatus of the pulmonary trunk is formed by anatomical elements with different morphological structures. In it there are elements which might be considered from standpoints of biomechanics as membranous (pulmonary trunk, sinuses, cusps) and shaft (fibrous ring, commissural shafts, arcuate crests) elements, the commissural shafts representing a combination of structures forming a closed spatial inter-related construction--a natural elastic framework of the pulmonary trunk root and the sheath elements are morphologically interrelated and fixed on this framework.

[The morphological justification for the use of collagenoplasty in progressive myopia].

A morphological study in 20 rabbits was performed in order to investigate the response of the eye tissues and the changes in the collagen spongious preparations implanted into the episcleral space. Aseptic inflammation developing in the episcleral space was local and did not have influence on the state of the retina and choroid. The collagen implants underwent lysis, resorption and were gradually replaced by the connective tissue with the development of the episcleral scar that increased the thickness of the sclera from 1.

New cardiac bioprostheses: theory, experiments, and 10 years of clinical use.

The biological valve "BAKS" has the following specific features: (1) it is practically devoid of immunogenicity due to fermentative-chemical treatment; (2) it is completely treated with glutaraldehyde through gradual soaking in solutions of increasing concentration; (3) the biological part is fashioned taking into account the biomechanics of the aortic root; (4) the polypropylene stent is functional due to the use of the principles of bionics in valve construction; and (5) practically no thromboemboli occur, because of the special morphologic organization of the cuff and the distant location of the bioprosthesis leaflets from the stent edge. In the Department of Heart Surgery of the National Research Center of Surgery, "BAKS" valves have been used in 237 patients undergoing isolated mitral valve replacement for rheumatic heart disease. Of these 35% were younger than 35 years, 93.

[Collagen plastic surgery in progressive myopia].

The technique of surgery is as follows: 4 implants of wetted and squeezed out collagen sponge, 7-8 x 20-22 mm in size, 2-2.5 mm thick, are introduced into Tenon's space to fill the gaps between the rectus muscles; a standard sterile hemostatic sponge or a colocyl sponge in employed. Experimental studies have shown the development of new episcleral connective tissue at the sites where the sponge has been introduced, the thickness of this tissue exceeding 1.

[Fibrinoid and fibrinoid necrosis in the morphogenesis of chronic stomach ulcers (electron and light microscopy)].

The stomach surgically removed from 38 patients because of chronic ulcers are studied. The fibrinoid necrosis zone observed at the bottom of 30 ulcers is formed of two layers out of which the superficial layer only is necrotic while the deep one represent a fibrinoid swelling. The latter consists of the network of collagen fibers and fibrin elements with surviving connective tissue cells.

[Morphological evaluation of the viability of silicon-lavsan tracheal prostheses].

Time course of the healing process in the tracheal wall during silicon-lavsan tracheal grafting was investigated in experiments on 108 dogs with a new model of tracheal prosthesis. The formation of granulation tissue was noted as a result of postoperative inflammatory reaction in the prosthetic area. The tracheal epithelial layer adjacent to the anastomoses was hypertrophic and acquired the features of squamous epithelium.

[Compensation of experimental insular insufficiency by altering the portal blood flow].

Experimental insular insufficiency and hyperglycemia in dogs was induced by subtotal resection of the pancreas. The diverting of venous blood from the pancreas into the systemic circulation via the spleno-caval venous anastomosis promoted a reduction of insulin metabolization in the liver on the first passage. This led to an increase in peripheral blood insulin and rapid compensation for hyperglycehia induced by resection of 80% pancreas.

[Second set method for determining the immunogenicity of heart valves].

The "second set" method was used on inbred rats to study immunogenicity of the heart valves treated with a proteolytic enzyme and glutaric aldehyde and to compare it with immunogenicity of the valves treated with glutaric aldehyde alone according to Hancock's method. The valves treated by the enzyme and 0.2-0.

[Experimental basis fur using D-penicillamine in liver cirrhosis].

The therapeutic action of D-penicillamine (D-PA) in experimental liver cirrhosis was examined comprehensively and compared to that of prednisolone. D-RA primarily depressed fibrillogenesis, preventing the appearance of scar lesions in liver tissue. The drug exerted a beneficial effect on excretory and albumin-synthetizing function of the liver and had a protective action of oxidation function of liver mitochondria and the content of cytochromes.

[Evaluation of the results of neurorrhaphy using microsurgical and ordinary technics (experimental study)].

For comparative assessment of an ordinary epineural suture and neurorrhaphy with the use of neurosurgical techniques operations were conducted on rabbits with a subsequent histological examination. It was established that the granulation tissue containing fine collagen fibers formed more rapidly when microsurgical techniques were used than in the controls. Besides, the rate of growth of the nerve elements in the region of the anastomosis was higher and by the end of the study the newly formed myelin axons acquired a clear linear direction.

[Fibroblast-fibroclast: The ultrastructural mechanisms of resorption of collagen fibers in involution of the connective tissue].

Using various experimental models (postpartum involution of the uterus, resolution of a subcutaneous scar which replaced the collagen implant and connective-tissue capsule following the removal of a foreign body) and electron-microscopy and histochemical methods of investigation intra- and extracellular resorption of th e collagenous fibres was extablished. The main role in this process was played by fibroblasts which uncer these conditions could funciton as fibroclasts phagocyting and idgesting in its cytoplasma collagenous fibrillas with the help of lysosomal enzymes. Desintegration of fibroclasts, enriching the medium with these enzymes, stimulated the extracellular lysis of the collagenous fibrillas.