[The structure and mechanical properties of the human pulmonary trunk and its valves]. / Stroenie i mekhanicheskie svoistva legochnogo stvola i ego klapanov u cheloveka.

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 mechanical properties of these shaft elements are formed not only at the expense of inclusion of other formations in their structure but also at the expense of changes in the density of distribution and spatial orientation of main carrier structures of sheath elements attached to them. So, the strength and rigidity of the fibrous ring were associated not only with the presence of collagenous fibers and chondroid tissue n it, but also with the regular arrangement of collagenous fibers coming to it from the sinus. Similarly, the strength of arcuate crests was in many respects dependent on dense arrangement of longitudinally oriented smooth muscles. The amount of smooth muscles in the pulmonary trunk was 1.3 and 2 times higher than that of collagenous and elastic structures which allows the pulmonary trunk of man to be referred to arteries of muscular or mixed type. It points to the necessity to take into account the influence of muscle tone on mechanical behavior of the pulmonary trunk under physiological exercise.

[The morphological justification for the use of collagenoplasty in progressive myopia]. / Morfologicheskoe obosnovanie primeneniia kollagenoplastiki pri progressiruiushchei blizorukosti.

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 1.5 to 2.5-fold during 1-2 months. These results are the basis for the successful surgical correction of the high progressing myopia.

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, 93.7% belonged to New York Heart Association functional class IV, and 24% had had a previous heart operation. The 10-year survival rate without hospital mortality was 68.94% +/- 4.86%. Total follow-up was 11,232 patient-months (range; 6 to 118 months; mean, 57 months; 97% complete). Main causes of death and reoperation were (per patient-year) infectious endocarditis, 3.2%; spontaneous bioprosthesis degeneration, 0.96%; mechanical dysfunction resulting from damage in the manufacturing of the prosthesis, 0.74%; left atrial thrombosis and/or thromboemboli, 0.5%; sudden death, 0.2%; cardiac insufficiency, 0.3%; and other, 0.4%.

[Collagen plastic surgery in progressive myopia]. / Primenenie operatsii kollagenoplastiki pri progressiruiushchei blizorukosti.

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 1.5-2.5-fold that of the rabbit sclera. Altogether 200 eyes (100 patients) with myopia of 3.5-15 diopters have been operated on. Myopia progress has been stopped in 95% of cases; vision acuity has improved by 0.14-0.15 (p less than 0.001), clinical refraction has reduced by 0.9-1.0 diopters (p less than 0.001) in 84% of patients. A significant improvement of the hemodynamics has been achieved, as well as of the eye membrane rigidity (1.5-2-fold). The complications were only negligible diplopia early after surgery in 3 cases. Collagen plastic surgery is a simple method, marked for the availability of the implanted material; it is highly effective and in fact does not involve complications, this permitting its use in progressive myopia of more than 4.0-5.0 diopters.

[Fibrinoid and fibrinoid necrosis in the morphogenesis of chronic stomach ulcers (electron and light microscopy)]. / Fibrinoid i fibrinoidnyi nekroz v morfogeneze khronicheskikh iazv zheludka (élektronnaia i svetovaia mikroskopiia).

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. Two processes going into the opposite directions take place on the border between the fibrinoid zone and granulation tissue: the spread of the fibrinoid to the granulation tissue and its organization by the granulation tissue elements. Interrelationship between these processes as well as the intensity of the fibrinoid necrosis rejection from the surface determines the thickness of the zone. Fibrinoid prevents the stomach wall digestion but at the same time inhibits the ulcer healing.

[Morphological evaluation of the viability of silicon-lavsan tracheal prostheses]. / Morfologisheskaia otsenka vzhivleniia silikon-lavsanovogo proteza trakhei.

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. Later, after the implantation the prosthesis was surrounded by a thick fibrous capsula. In anastomoses, at tracheal tissue--implant border there was a poorly expressed inflammatory reaction, which had a local character and was compatible with 3 and more years of life in most experimental animals.

[Compensation of experimental insular insufficiency by altering the portal blood flow]. / Kompensatsiia éksperimental'noi insuliarnoi nedostatochnosti putem izmeneniia portal'nogo krovotoka.

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. No gross morphological changes in the liver were revealed during 4 months after anastomosis establishment. A decrease in the glycogen content in the liver and peripheral muscles was noted after blood shunting. The subtotal resection of the pancreas coupled with pancreatic duct ligation resulted in gross fibrotic changes in the pancreas and atrophy of the exocrine tissue. On the other hand, the endocrine tissue gets hypertrophied, being less prone to fibrosis.

[Second set method for determining the immunogenicity of heart valves]. / Metodika "second set" v otsenke immunogennosti klapanov serdtsa.

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 0.2-0.5% glutaric aldehyde did not lead to the body sensitization in contrast to the valves exposed to 0.5% glutaric aldehyde alone. During transplantation of the latter ones, there were signs of the immunologic response on the part of the recipients and calcification of valvular tissue 70 days after subcutaneous implantation. It is assumed that pretreatment with the enzyme makes it possible to appreciably reduce immunogenicity of the heart valves.

[Experimental basis fur using D-penicillamine in liver cirrhosis]. / Eksperimental'noe obosnovanie primeneniia D-penitsillamina pri tsirroze pecheni.

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. Unlike D-PA, prednisolone primarily reduced the manifestations of auto-immunization. The remainder of the tests have revealed no essential differences in the action of the drugs. The risk of prednisolone overdosage and side effects it produces have been recorded.

[Evaluation of the results of neurorrhaphy using microsurgical and ordinary technics (experimental study)]. / Otsenka rezul'tatov nevrografii s primeneniem mikrokhirurgicheskoi i obychnoi metodik (éksperimental'noe issledovanie).

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]. / Fibroblast-fibroklast: Ul'trastrukturnye mekhanizmy rezorptsii kollagenovykh volokon pri involiutsii soedinitel'noi tkani

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. This lysis was particularly intensive in the presence of an inflammatory process, and even could take place before the intracellular resorption. In macrophages no intracellular lysis was observed, however, they could phagocyte denaturated collagen, deprived of structural orgainzation.