Kosmicheskaia biologiia i aviakosmicheskaia meditsina最新文献

The effect of three exposures to Coriolis acceleration on the frequency and amplitude of fasting stomach contractions was investigated in 6 resistant and 16 susceptible to motion sickness test subjects. After tests all of them underwent gastroduodenoscopy and 4 subjects from each group were subjected to echography to measure gall bladder contractility in response to glucose-milk loads. After tests the motor activity of the stomach increased slightly in resistant subjects due to an increase of the amplitude and a slight decrease of biopotential frequency. During gastroscopy antral and pyloric sphincters were closed. In the stomach there was an insignificant amount of contents without gall. In the susceptible group, the motor activity was, on the contrary, inhibited due to a significant decline of the wave amplitude and frequency (by 40% and 11%, respectively). In the stomach, one or both sphincters were widely open; it also contained a large amount of gastric juice and gall. In 36% of susceptible and 17% resistant subjects, diaphragmatic hernia (at the esophageal opening) was found. Ultrasonic examination of the gall bladder showed that susceptible subjects developed its faster and stronger contraction when compared to resistant subject in response to glucose-milk loading. This pointed to a more prolonged duration of the gall excretion phase. Reactive changes of the gastroduodenal zone in response to motion tests facilitated duodenal-gastric reflux and major gastrointestinal symptoms of motion sickness.

This paper shows that the method of water and air purification using immobilized cells and enzymes can be applied in regenerative life support systems in a habitable enclosed environment. This method is based on selective and adaptive functions of enzymic systems of microorganisms to assimilate organic components of the medium to be eliminated. Advantages of biocatalysis are low energy requirements and mild temperatures of purification leading to practically complete elimination of the substrate. Due to immobilization, cells and enzymes constitute an independent component which can be added to any continuously operating system of purification without generating a specific interface which is crucially important in microgravity. This allows the process of purification to be controllable. The resulting water and air meet biological requirements because they are formed under the influence of living organisms as in natural biogeocenoses. The production of ecologically pure water and air is highly important for long-duration space missions, especially for flights to Mars.

In the course of 126 man/exposures of 3 hours to 3 days in duration, in which 39 test subjects took part, circulation responses to the upright and supine body position during suited immersion as well as orthostatic and exercise tolerance after immersion were investigated. During 24 man/exposures for 2 days the subjects were administered per os placebo or one of the four neurotrophic drugs: sydnocarb, sydnogluton, sydstrigluton, estrigluton. Clinical observations, instrumented data and methodical features of the immersion model used give evidence that the suited immersion has advantages over currently used procedures simulating the effects of hypogravity. The drugs allowed cardiovascular correction that increased aerobic capacity of the body and enhanced cardiovascular orthostatic and exercise tolerance.

Nine test subjects performed 4 dives in a He-O2 atmosphere at 3.5 MPa for 3-21 days. Their external respiration and gas exchange were measured at rest and maximum physical load. At rest the basic respiratory parameters remained unaltered. However respiratory reserves decreased under the influence of increased gas density. At a maximum workload the power of which proved lowered the ventilation gain was inadequate. This led to CO2 retention in the body and, consequently, to subjects' refusal to continue physical work. Prolonged exposure to 3.5 MPa caused the most significant respiratory changes during the first 3 days and their slight normalization and constancy during subsequent 2.5 weeks. This was, probably, associated with a slight pO2 increase in the breathing gas.

This is an overview of investigations performed in actual and simulated flights to study the effects of microgravity and acceleration, space cabin and space suit artificial atmosphere on the respiratory function. The conceptual prediction of the effects that the space environment produces on the respiratory system suggests the following changes in respiration, gas exchange, and acid-base equilibrium: respiration biomechanics; gas diffusion and ventilation-perfusion ratios in the lungs; regulation of respiration and function of respiratory muscles; lung hydration and blood filling; respiratory changes in acid-base equilibrium and blood gases. Besides, the combined effect of microgravity, acceleration, low barometric pressure and modified gas composition may cause lung atelectases and concomitant disorders in pulmonary ventilation and gas exchange. These changes may have an adverse effect on the health condition and physical work capacity.