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Biomedical subjects

L L Razumova

Publications and source records attributed to L L Razumova.

18 recordsLinked to original sources
PubMed1986

[Structural and chemical transformations of heat-processed polyacrylonitrile fibers and characteristic parameters of their interactions with thrombocytes and plasma proteins].

A suitable for analysis of the effect of structural and chemical changes on haemocompatibility of polymers is polyacrylonitrilics (PNA), which, depending on the thermo-processing (temperature, medium), make a number of materials, differing in structure and properties. A comparative analysis of physical and chemical initial properties as well as of thermically processed PNA fibres was made. By the methods of radioisotope and of fluoroscent spectroscopy the kinetics of early stages of adsorption of plasma albumine (AS) and of plasma fibrinogen (FG), the kinetics of desorption of pre-adsorbed plasma albumine in a model solution, and thrombocyte adhesion of the PNA surface were studied. The extreme nature of the irreversability degree in albumine and fibrinogen adsorption, the effective coefficients of the albumine desorption speed, and the number of bound thrombocytes at the temperature increase in thermal processing were found, and better quantitative criteria of haemocompatibility in vitro for PNA, processed thermally in the air. The achieved results can be explained by occurrence of, in a number of studied PNA fibres, an optimum ratio of the dispertion and polar superficial surrounding energy.

Absorption↗
PubMed1979

[X-ray diffraction analysis of disintegration of polyglycolic acid suture material both in vivo and in model media].

Examined were the structural variations of polyglycolic acid surgical suture material by X-ray diffraction methods subsequent to sejour in vivo and in several model mediums. After a long stay in vivo, water and buffer at pH 2 the following structural variations in the polymer were observed: diminution of macroperiod, and certain increase of crystallinity. Rather profound, ten times faster destruction of suture material in alkaline medium at pH 12 did not cause the variation of macroperiod and crystallinity. Even in the case of extensive destruction with mass losses approaching 90% and variation of crystalline structure of the polymer was not observed. These data confirm the theory described previously by the authors on the existence of two possible methods of polymer destruction in aggressive mediums passing through total volume and on the plastic surface only.

Animals↗
PubMedDate not supplied

[X-ray diffraction studies of muscles].

A brief account of the modern state of X-ray diffraction studies of muscles is presented. Recently many investigaters payed particular attention to concrete changes taking place in structural-executive (protofibrillar) apparatus of muscles at the change of their state. The drawback of these works is the necessity of interpreting the data on the basis of model ideas having definite variability. Our studies here presented differe by the approach to the problem and to a certain extent by the methods applied. Our main task was to study the dynamics of structural changes in muscles while the latter perform their working function. Special attention was payed to the studies of muscles at different shortening eithor on living or fixed samples. The effect of some conventional fixators on structural parameters evaluated by X-ray analysis was studied for the first time. A means of stroboscopic accumulation of X-ray diffraction patterns for periodic fast processes was developed. One of our main tasks was to find the range of applicability sliding mechanism hypothesis for describing muscle shortening. It was observed that the sliding mechanism held true for the desscription of the structure of muscles shortened in a physiological range. X-ray diffraction patterns were obtained which were different for the shortenings according to the sliding mechanism and those with A-disc shortening and during supercontraction. The limits of the sliding model were evaluated by some of these characteristics for muscle of different composition and properties. The problem of the forces realizing muscle shortening is discussed, some of the author's studies being taken into account. Muscle should be assessed as a complex heteromorph biological object and as a complex liquid crystalline system to create the models of its molecular structure and to elucidate the precise mechanism of its functional activity.

Animals↗
PubMedDate not supplied

[X-ray diffraction study of muscles in disease].

Structural parameters of muscles in some diseases have been studied using X-ray diffraction methods. Fixed parts of muscles dissected in the operation correcting the vertebrate shape were used as samples in the case of patients III-IV stage of scoliosis muscles. The sarcomere protofibrillar lattice in muscles was found to be retained until the destruction of the muscle tissue; no differences between the muscles from the convex and concave sides of the vertebrate were observed. This seems to be an evidence of functional inertia of the diseased muscles and of their atrophy. Fixed parts of myocardial muscles taken during surgical correction were used as samples in investigating the Tetralogy of Fallot heart disease in children. A disturbance of packing parameters of the protofibrillar apparatus was observed in a significant part of the apparatus volume. In the case of critical experimental heart deficiency in dogs the protofibrillar lattice structure was retained, probably due to its resistance nature.

Animals↗