[An experimental study of biomaterials resistant to calcinosis and thrombosis]. / Eksperimental'noe izuchenie biomaterialov, rezistentnykh k kal'tsinozu i trombozu.

Creation of hemocompatible materials resistant to calcinosis for plastic cardiosurgery call for employment of combined methods of their evaluation in experiment. The present study deals with some biochemical and physico-chemical aspects of biomaterial calcification inhibition on reduction of their porosity by means of N-vinylpyrrolidone, and also on immobilization of diphosphonates, phosphonates, and anti-aggregants. The method of radiation copolymerization was employed for immobilization of active agents. The effects of different biotissue specimens of varying modifications (pig aortal valves and cattle pericardium) and of Lavsan (polyethyleneterephthalate) on coagulation factor activation were studied in vivo (in goat) and in vitro. The specimen surface was inspected prior to and after the contact with blood and plasma using the techniques of scanning electron microscopy and photoelectron spectroscopy. The influence of the modifications on the calcium and phosphorus accumulation were studied after subcutaneous implantation of the specimens to rats, and the aggregating capacity of blood platelets was determined in incubation of Lavsan treated with an anti-aggregant. Combined studies revealed the optimal modification routine and the most active agents enabling one to obtain biomaterials that not only are resistant to calcification but also possess good hemocompatibility.

[Resistance of heart valve bioprosthesis to the proteolytic effect of collagenase and elastase]. / Izuchenie ustoichivosti bioprotezov klapanov serdtsa k proteoliticheskomu vozdeistviiu kollagenazy i élastazy.

Proteolytic destruction of pig aortal valves was studied at various steps of their preparation to implantation (native tissue, the tissue treated with terrylytine as well as with terrylytine and glutaric aldehyde) using pig pancreatic elastase and bacterial collagenase. The rate of the tissue destruction was estimated by means of monitoring an increase in content of protein and amino nitrogen in the hydrolysates. The tissue treated with terrylytine and glutaricaldehyde was 10-40-fold more resistant to proteolysis as compared with native heart valve tissue. Inadequate stabilizing effect of glutaric aldehyde on elastin, as compared with that on collagen, was found, when proteolysis of native and modified with glutaric aldehyde elastin from bovine cervical ligament and of calf skin collagen was studied using elastase and collagenase, respectively.

[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.