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Biomedical subjects

I M Kiselev

Publications and source records attributed to I M Kiselev.

10 recordsLinked to original sources
PubMed1983

Implanted artificial heart with radioisotope power source.

An atomic artificial heart for orthotopic implantation was developed with the following characteristics: volume, 1.2 L; weight, 1.5 kg; radioisotope power, 45 W; operating life, up to 5 years; hemodynamics, similar to natural hemodynamics. The artificial heart includes a thermal drive with systems for regulating power, feeding steam into the cylinders, return of the condensate to the steam generator, and delivery of power to the ventricles and heat container. The artificial heart is placed in an artificial pericardium partially filled with physiologic solution. It uses a steam engine with two operating cylinders that separately drive the left and right ventricles. There is no electronic control system in the proposed design. The operation of the heat engine is controlled, with preservation of autoregulation by the vascular system of the body. The separate drives for the ventricles is of primary importance as it provides for operation of the artificial heart through control of cardiac activity by venous return. Experimental testing on a hydromechanical bench demonstrated effective autoregulation.

Electric Power Supplies↗
PubMed1983

Prospects for using implanted systems of assisted circulation and artificial heart with a radioisotope power source (biomedical, thermal, and radiation aspects).

The capacity of dogs to diffuse heat (up to 50 W) from an artificial heart and to tolerate prolonged intracorporeal ionizing radiation from a radioisotope power source (238Pu) was investigated, using electrical models of vascular blood heat exchangers that permit reproduction of elimination and heat transmission in autonomous systems. It was shown that up to 50 W can be discharged at temperatures of the wall-blood interface that do not exceed 43 degrees C. Clotting indexes, concentration of total protein, hemolysis, and serum enzyme activity during 1-1.5 months of heating remained within physiologically normal limits. A specific power load of up to 1.5 W/kg at ambient temperatures of 18-20 degrees C revealed no evidence of changes in heat production. By measuring the distribution of power of the dose absorbed around a 45-W plutonium source it was possible to estimate dose loads on critical organs and to assess overall risk of death from malignant tumors induced by radiation over a 10-year period: 6-12% for males and 8-14% for females. It is not very probable that use of the artificial heart with a radioisotope power source will be limited by thermal and radiational effects.

Animals↗
PubMed1982

[Effect of thymectomy and polypeptide thymus factor on development of alimentary reflex in rats].

The effects of thymectomy and polypeptide thymus factor on the formation of alimentary instrumental reflex were studied in rat experiments. It was shown that 8-9 months after thymectomy the percentage of rats trained the alimentary instrumental reflex decreased from 85.7 +/- 9.7 (sham-operated animals) to 22.2 +/- 14.7 (thymectomized animals). By the same time T lymphocytes had been completely eliminated from the spleen. The motor activity and its pattern were similar in the sham-operated and thymectomized animals. Daily administration of the polypeptide thymus factor (thymarine) intramuscularly to the rats at a rate of 1 mg per animal for 10 days recovered the percentage of the trained animals to the control levels.

Animals↗
PubMed1979

[Impulse synchronization in the mechanisms of adaptive plasticity of neuronal populations of the posterior hypothalamus].

An increase in the firing rate induced minimization of the reward (a weak electrical skin stimulation) and altered the neuronal activity patterns in the posterior hypothalamus. The estimation of the expected random coincidence functions between the two neuronal activity trains belonging to adjacent cells showed the synchronization both in high- and low-frequency ranges. In the process of adaptive alterations of the neuronal activity, fluctuations of the expected randon coincidence coefficients occurred.

Adaptation, Physiological↗
PubMedDate not supplied

Biofeedback control of systemic arterial pressure.

The central mechanisms and possibilities of biofeedback of the systemic arterial pressure have been investigated in experiments on cats, rabbits, and rats. The adaptive processes were followed in association with minimization of electrodermal reinforcement during the development of shifts in relation to the level and bioelectrical structure of the AP, as well as the impulse activity of hypothalamic neurons.

Adaptation, Physiological↗
PubMedDate not supplied

[Stable shifts in systemic arterial pressure in a controlled experiment with feedback].

On the bases of experiments with bio-control feed-back connection (automatically triggering electro-cutaneous, stimulation), a model evolved permitting to achieve stable directed changes in the levels of the systemic arterial pressure (AP) in curarized rabbits and cats. Two variants of reactions are possible: 1) gradual formation of a new raised or lowered level of AP with its pronounced retention after the end of learning, and 2) reaction of following type with directed rise in AP, which is observed only during learning. It is found that the stable shifts of the AP level are accompanied by changes in the periodicity of the third order AP waves, the heart rate showing no significant changes. It is assumed that the changes in the characteristics of the third order waves reflect the rearrangement of the mechanisms providing for homeostasis.

Animals↗