[Effect of carcinogenic nitrogen-containing compounds on cell metabolism].

The brown frog (Rana temporaria) skin cells respiration, calcium metabolism and glycolysis, the tree frog (Hyla arborea) skin cells respiration and calcium metabolism were studied under short-term (first hours) and long-term (first days) exposure to nitrogenous compounds [N-nitroso-N-methyl urea (NMU) and thiourea (TU)]. The first direct effect of nitrogenous compounds exposure was cell breathing inhibition occurring in Rana temporaria skin cells after 28 days of exposure, and in Hyla arborea skin cells after 8 days of exposure. These changes were precided by decrease of lactate dehydrogenase (LDH) activity in Rana temporaria skin cells starting 16 days after NMU and TU introduction. The increase of intracellular calcium level was noted in tree frog skin cells 4-8 days after NMU and TU introduction, in brown frogs skin cells this parameter was unchanged.

[Functional and morphological characteristics of the digestive reaction of gastric mucosa]. / Funktsiona'no-morfologicheskaia kharakteristika pishchevaritel'noi reaktsii slizistoi obolochki zheludka.

Morphological state of connective tissue (stromal) cells of the stomach mucous membrane has been studied in healthy persons, having a habitual regime of feeding. During digestive period in the stomach mucous membrane, certain changes develop, which are considered as a digestive reaction. Three stages of the digestive reaction, having strict morphological signs are determined, their connections being stated by means of morphometry and mathematical analysis. I stage (preparatory) is characterized with a moderate vascular reaction, degranulation of mast cells under the superficial++ epithelium of the mucous membrane, with a moderate neutrophilic leukopedesis and a moderate lymphocytic infiltration; II stage (developed) is distinguished as a definitely demonstrated reaction of the microcirculatory bed, intensive degranulation of mast cells at all levels of the mucous membrane, massive discharge of neutrophilic granulocytes and lymphocytes into stroma; III stage (restorative) is characterized with a predominance of fibroblasts and fibrocytes, with reparation of mast cells, with decreasing saturation of stroma with neutrophilic granulocytes, lymphocytes, an increased number of eosinophilic granulocytes takes place. The data obtained widen our knowledge on functional morphology of the stomach mucous membrane, normal and at gastroduodenal pathology.

Automatic control systems for the artificial heart and ventricular assist device.

Automatic control systems for the artificial heart (AH) and ventricular assist device were developed using selected criteria of effectiveness, a mathematical model of regulation, and noninvasive measures of the hemodynamic parameters. The Sinus IS2 system was developed for control of the AH; its main component is a high-speed servomechanism that provides for the generation of pneumatic pulses. The servomechanism is controlled by automatic regulation with pressure feedback. Mean aortic pressure was used as the primary regulated hemodynamic parameter. The systems were tested using both a physical model and a physiologic experiment. Contractile insufficiency of the left ventricle was simulated in testing the control system for circulatory assistance. The studies demonstrate that automatic control systems function effectively by providing normal blood circulation in both the resting state and in certain transient processes occurring in a real, dynamic circulatory system.

[Study of the efficacy of assisted circulation control by mathematical and physical modeling methods]. / Issledovanie éffektivnosti reguliatsii vspomogatel'nogo krovoobrashcheniia metodami matematicheskogo i fizicheskogo modelirovaniia.

The efficiency of the assisted circulation control has been studied by mathematical and physical simulation. It has been assessed by simulating a transient process within the circulation system that imitated the left ventricular failure. The control system for regulation of the assisted circulation process based on the mathematical models is shown to be capable of maintaining the main hemodynamic parameters and the left ventricular relief at the present level in heart failure.