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Biomedical subjects

A M Genin

Publications and source records attributed to A M Genin.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[Activation of external respiration and level of alveolar PCO2 in pilots in flight].

The paper discusses the emergence of spontaneous hypocapnia in real aircraft flights. The flying personnel were taken under study. The hypocapnic state was diagnosed on the basis of the CO2 concentration in the alveolar air measured by a special device. In flight the CO2 concentration in the alveolar air decreased insignificantly (by 5 min Hg on the average). In emergency situations the external respiration was activated to a greater extent. It is suggested that the alveolar Pco2 level is indicative of the emotional stress.

Aerospace Medicine↗
PubMedDate not supplied

[Hypobaric nitrogen-oxygen atmosphere as a method of preventing altitude decompression sickness].

It has been shown experimentally that the development of altitude decompression disease at 250 and 180 mm Hg can be prevented by preliminary desaturation in the nitrogen-oxygen hypobaric atmosphere (60% N2 and 40% O2 at 550 mm Hg). This has been demonstrated in 38 experiments on 21 test subjects. The use of this atmosphere in space cabin prevents the development of decompression disease upon a decrease of the cabin pressure to 250 mm Hg and upon extravehicular activity in a space suit with 180--200 mm Hg.

Adult↗
PubMedDate not supplied

[The physicochemical properties of hydrogen and its use as an indifferent component in breathing mixtures under high pressure].

Data on a possible use of hydrogen as a part of the breathing mixtures during deep diving are presented; advantages and disadvantages of hydrogen application in the undersea research and diving practice are evaluated. Perspectives and trends with respect to a safe hydrogen use under high pressure in combination with oxygen and other inert gases are discussed.

Chemical Phenomena↗
PubMedDate not supplied

[Functional state of various physiological systems of the human body during respiration of neon-oxygen mixture at depth up to 400 meters].

Hyperbaric neon-oxygen mixture has been studied for the effect of its high density under pressure of 41 ata on basic physiological functions of human organism. Typical changes of the cardiorespiratory system and tissue respiration parameters are revealed. Changes in physical working capacity are shown. Exposure to gaseous medium of high pressure and density is accompanied by the development of some compensatory-adaptive reactions. The possibility to perform mid-hard physical work is attained with overstrain of respiration and circulation function.

Adaptation, Physiological↗
PubMedDate not supplied

[Status of human hemodynamics during water immersion in different postures of immersion].

Central and peripheral hemodynamics was investigated in 16 essentially healthy volunteers who performed a routine tilt test or a tilt test in water immersion. Unlike tilt tests carried out before water immersion, the supine to up-right transfer in water did not change cardiac rhythm, cardiac output, leg blood flow or other circulation parameters. The fact that there are no posture-related circulation changes in water immersion suggests that the horizontal and upright positions in water can be viewed as hemodynamically similar.

Adult↗
PubMedDate not supplied

[Effect of short-term head-down tilt hypokinesia on the dynamics of the cardiorespiratory indices during graduated physical loading].

Seven healthy volunteers were exposed to head-down tilt at -15 degrees for 5 h. Before and after exposure they exercised on a bicycle ergometer in the supine and seated positions. During the study their respiration function, gas exchange, and arterialized blood parameters were measured. It was found that after exposure the physical aerobic performance diminished. The changes detected suggest that a lower exercise tolerance can be caused not only by a decreased circulating blood volume but also by increased energy expenditures of the cardiorespiratory system itself.

Adult↗
PubMedDate not supplied

[Catecholamines and the enzymes of their synthesis in the adrenal medulla of rats after a flight on the Cosmos-936 biosatellite].

In the adrenals of weightless and centrifuged rats flown for 18.5 days onboard the biosatellite Cosmos-936 indicators of the activity of the adrenomedullary system, i.e. the content of catecholamines and activity of the enzymes involved in their synthesis--tyrosine hydroxylase and dopamine-beta-hydroxylase--were measured. It was found that none of the indicators changed postflight. These findings show that a prolonged exposure of rats to weightlessness does not act as a strong stressor for the adrenomedullary system.

Adrenal Medulla↗
PubMedDate not supplied

[Results of medical research in the performance of the long-term manned flights of the Saliut-6 program].

The major goal of biomedical investigations in prolonged (up to 6 months) manned missions was to obtain information about physiological reactions to long-term weightlessness and to carry out detailed clinical, physiological, immunological and anthropometric investigations before, during and after flight. The results obtained give evidence that man can adapt to the prolonged exposure and to maintain good health condition and high work capacity. The changes detected postflight were reversible and disappeared completely within a relatively short time period. The changes were not correlated with the flight duration. The good health condition and high performance inflight were maintained and postflight readaptation was facilitated due to a rational work-rest cycle and specific countermeasures which were modified with respect to the results of regular medical examinations. Salyut-6 medical data have demonstrated that the duration of forthcoming manned missions can be extended.

Adaptation, Physiological↗
PubMedDate not supplied

[Main results of the medical research in the Saliut 6-Soiuz program].

In 1977-1981 the Soviet Union launched 18 manned space missions under the Salyut-6--Soyuz program which included five flights of prime crews for 96, 140, 175, 185, and 75 days and eleven flights of visiting crews. Altogether 30 cosmonauts, including 9 crewmembers from other than the USSR socialist countries, took part in the program. Emphasis was given to the medical investigations, since their purpose was not only to assess the health status of the crewmembers and to investigate their responses to prolonged weightlessness, but also to identify the maximum allowable flight time.

Body Weight↗
PubMedDate not supplied

[Reliability and effectiveness of monitoring the stroke and minute volume of the heart by Kubicek's rheographic method].

Simultaneous measurements by the Fick direct method and the Kubicek rheographic method of cardiac output of 20 men with ischemic heart disease have shown that both methods are well correlated (r = 0.76, k = 0.92, n = 41). The reproducibility of the Kubicek data was slightly better than the Fick data (on the average +/- 6% instead of +/- 9-10%). An attempt of increasing the correlation of the Kubicek data with the Fick data by correcting the specific resistance with respect to the hematocrit data and the chest perimeter failed. In order to provide the necessary accuracy of the Kubicek method, it is required that the procedure be stringent and the five variables in the formula for calculating cardiac output be precisely measured. The cardiac output values determined simultaneously by the Kubicek method and by x-ray contrast ventriculography showed a better correlation (r = 0.88, k = 0.97, n = 15).

Adult↗
PubMedDate not supplied

[Principal results of physiological experiments with mammals aboard biosatellite "Cosmos-936"].

The program of the 18.5-day flight of the biosatellite Cosmos-936 included studies of physiological effects of prolonged weightlessness (20 rats) and artificial gravity (10 rats). The latter produced a normalizing effect on the function of the myocardium, musculo-skeletal system and excretory system. Simultaneously, artificial gravity exerted an adverse effect on the functions dependent on several sensors, primarily optic, vestibular and motor sensors. It is postulated that the adverse effects are associated with a relatively high rate of rotation and a short arm of the centrifuge.

Animals↗
PubMedDate not supplied

[Human tolerance to rotation at different levels of increased gravitation].

The effects of acceleration of different value (up to 2 g) on the level of motion sickness, vestibular and postural reactions to rotation were studied. The experiments were carried out in a centrifuge equipped with a cabin that could be mounted at a different distance from the axis of rotation. Three experimental runs were conducted with a rate of rotation of 15.3 and accelerations values of 1.09, 1.6 and 2.0 g. Vestibular stimulation was produced by head movements of a predetermined number. It was found that with increase in the acceleration value the level of motion sickness decreased and the nystagmic reaction and balance dysfunction enhanced.

Adaptation, Physiological↗
PubMedDate not supplied

Physiological mechanisms of adaptation to weightlessness. Data from experiments with animals in earth-orbit biosatellites.

Four experiments were carried out with mammals (white laboratory rats) in Kosmos biosatellites. The experimental results indicate that rather prolonged weightlessness does not cause pathological changes in internal organs. Changes were discovered in the metabolic and hormonal status of the organisms, allowing us to consider an 18-22-day space flight as a moderately stressful activity. Changes in the musculoskeletal system involved atrophy of particular muscle groups, adaptive transformation of the contractile properties of some of them, osteoporosis, and decreased durability of bony tissue. There was a decrease in the ATPase activity of myocardial myosin, and there were changes in the erythrocytic system: decreased erythrocytic hemopoietic activity, increased levels of spontaneous hemolysis of erythrocytes, etc. All the described changes were reversible, and examination of the animals 25 days after their return to Earth showed practically complete normalization of the parameters studied.

Adaptation, Physiological↗