Showing papers in "Aerospace and environmental medicine in 2011"

[Studies of the blood antioxidant system and oxygen-transporting properties of human erythrocytes during 105-day isolation].

Abstract: Effects of strict 105-d isolation on blood antioxidant status, erythrocyte membrane processes and oxygen-binding properties of hemoglobin were studied in 6 male volunteers (25 to 40 y.o.) in ground-based simulation of a mission to Mars (experiment Mars-105). The parameters were measured using venous blood samples collected during BDC, on days 35, 70 and 105 of the experiment and on days 7 and 14-15 after its completion. Methods of biochemistry (determination of enzyme activity and thin-layer chromatography) and biophysical (laser interference microscopy, Raman spectroscopy) showed changes in relative content of lipid and phospholipid fractions suggesting growth of membrane microviscosity and increase in TBA-AP (active products of lipids peroxidation interacting with thiobarbituric acid). A significant increase in glucose-6-phosphate dehydrogenase and superoxide dismutase activities against reduction of catalase activity points to both reparative processes in erythrocytes and disbalance between the number of evolving active forms of oxygen and antioxidant protection mechanisms in cells. Hemoglobin sensitivity of oxygen and blood level of oxyhemoglobin were found to increase, too. It is presumed that adaptation of organism to stresses experienced during and after the experiment may destroy balance of the antioxidant protection systems which is conducive to oxidation of membrane phospholipids, alteration of their content, increase of membrane microviscosity and eventual failure of the gas-exchange function of erythrocytes.

Expression of cytoskeleton genes in culture of human mesenchymal stromal cells in different periods of simulating the effects of microgravity

Abstract: Simulation of microgravity for cultivated multipotent mesenchymal stromal cells (MSCs) from human marrow changes transiently expression of genes associated with actin cytoskeleton; the effect fades away partially in 120 hrs. following microgravity and completely after 24-hr cell readaptation to static conditions. These changes in expression of some cytoskeleton genes seem to predetermine their reaction to simulated microgravity, and therefore inhibition of MSCs differentiation potential.

[Direct proteome profiling of human blood serum in the experiment with 5-day dry immersion].

Abstract: Purpose of the investigation was to determine changes in blood plasma proteome in healthy human subjects (n = 14, 19 to 26 y.o.) in an experiment with dry immersion (DI). Plasma samples were drawn 7 and 2 days before the exposure, on DI days 2, 3 and 5, and on days 1, 3, 7 and 15 after the experiment. Previous to direct MALDI-TOF mass-spectrometric profiling, serum samples were pre-fractionated and enriched with magnetic particles MB WCX (WCX--a weak cation exchanger) on ClinProt (Bruker Daltonics). In each spectrum, 175 MS-peaks were detected on average within the mass range from 1000 to 17,000 Da with the signal/noise ratio = 5. Student's criterion (p < 0.05) was used to define reliable differences between DI and baseline samples from 48 peaks (27.4 % of all the proteome profile peaks). On DI days 2 and 3, growth of peak areas was observed in fragments of complement system proteins C3 and C4, high-molecular kininogen and fibrinogen that can be attributed to organism adaptation to conditions of the experiment. Significant increases of the peak area of apolipoprotein CI (reduced form with segregated threonine and proline) and C4 enzymes of the complement system, and fibrinogen on the first day after the experiment can be related to changes in motor activities of the subjects.

[Biomechanics and regulation of the external respiration in the conditions of 5-day dry immersion].

Abstract: The work was concerned with evaluation of the external respiration function and regulation in healthy human subjects participating in simulation of the microgravity effects by dry immersion (DI). In the baseline data collection period, in DI (days 2 and 4) and after DI completion pulmonary volumes were registered, the ratio of thoracic and abdominal components of quiet breathing and respiratory maneuvers calculated, and parameters of respiration regulation, i.e. length of breath-holding and ability to voluntary control breathing motions, were determined. It was shown that breathing pattern did not undergo gross changes in immersion as compared with pre-DI test data; however, inspiratory reserve volume grew (p < 0.05) and expiratory RV reduced (p < 0.01). DI did not alter the ventilation function of lungs; yet, most of the subjects trended to increase the abdominal component of quiet breathing and displayed a statistically significant increase of the parameter during the maneuver made to determine the vital capacity of lungs. Maximum breath-holding, equally in the course of inspiration and expiration in DI, did not differ from baseline values. Accuracy of voluntary breathing control was better in immersion. We believe that similar to microgravity, exposure in DI produces regular alterations of pulmonary RV (partly because of changed body position), thoracic-abdominal ratio in breathing motions, and shifts in voluntary respiration regulation.

[Psychophysiological adaptation and communication behavior of human operator during 105-day isolation].

Abstract: Purpose of the study was to assess effects of 105-d isolation on language behavior and psychophysiological status of volunteered subjects. Software NOOJ was used to determine frequency of mentioning in written reports notions falling into the categories of "Needs", "Activity", "Negation" and "Social regulation". Well-being, activity and mood were assessed with the SAN questionnaire and urine cortisol measurement. Correlation of the content-analysis results with phases of adaptation to extended isolation and confinement made it possible to elicit specific features of language behavior of the small group members, at the time of simulated autonomy, specifically. Besides, the computerized content-analysis enabled a quantitative description of communication strategy as a function of psychophysiological adaptation to stressful factors of the simulation experiment.

[Experiment with 5-day dry immersion: objectives, content and structure of the investigations, methods].

Abstract: The article features the goals and objectives, and methods of an all-round experiment with 5-d dry immersion performed in 2010

Interocular asymmetry of nystagmus and motion sickness

Abstract: Binocular video nystagmography was employed to study the human vestibulo-ocular reaction to the double rotation test used in medical flight certification to assess vestibulo-vegetative stability. Purpose of the investigation was to establish an interrelation between parameters of the nystagmus reaction to rotation and severity of motion sickness (MS). The total of 135 medically certified flying men aged 23 to 47 years were subject to testing by intermittent Coriolis accelerations accumulation according to Bryanov's procedure. The vestibulo-vegetative reaction was assessed by the criteria of vegetative reactivity and protective movements. The closed-mask binocular test was performed during and after rotation, It was shown that interocular nystagmus asymmetry is linked directly with MS severity. Asymmetry coefficients are proposed for unidirectional nystagmus during inclinations (C(ai)) and straightening (C(as)) and for time of convergent rotational nystagmus during inclinations (T(ci)) and straightening (T(cs)). Coefficients C(ai) and T(ci) were found to correlate with MS severity (p < 0.05). From the data of the investigation it was deduced that the mechanism of MS during double rotation amounts to intravestibular interlabyrinthine conflict.

[Characteristics of negative pressure inspiration effect on the cardiorespiratory system of humans in the conditions of 5-day dry immersion].

Abstract: Changes in external respiration and central hemodynamics induced by negative (relative to atmospheric) inspiration pressure were studied in supine subjects before and on day-4 of a dry immersion (DI) experiment. Changes in the cardiorespiratory system as a result of negative inspiration pressure included rise of the amplitude of breathing motions and reduction of their frequency, and distinct breathing-related HR fluctuations. Combination of immersion and altered pressure in the mask caused breathing-related variations of systolic pressure and plethysmogram signal, and improved arterial blood oxygenation. These results can be useful for developing pressure-gradient methods of counteracting the adverse effects of blood redistribution toward the cranial-end.

[Renal functioning and human body liquids during 5-day dry immersion].

Abstract: Renal function and body composition, including liquids, were investigated in 14 essentially healthy male subjects during simulation of some spaceflight effects by 5-d dry immersion (DI). Noninvasive measurement of water spaces of organism was performed with the methods of bio-impedance analysis (BIA). Increase of renal excretion of liquids and appearance of negative water balance were observed. BIA revealed reductions of total body and extracellular liquids and a decrease of circulating plasma volume. This means, that DI induced hypohydration of organism. In the post-DI period, the hydration status regained its baseline level fairly soon. Lean body mass slightly decreased; adipose mass, on the contrary, exceeded baseline values. Moreover, the experiment evidenced technical impossibility to obtain valid impedansimetry data in DI.

[Metabolic effects of physical countermeasures against deficient weight-bearing in an experiment with 7-day immersion].

Abstract: Metabolic effects of physical countermeasures against deficient weight-loading were studied in three groups of 21-30 y.o. volunteers for 7-d dry immersion. Blood serum was investigated for 38 biochemical parameters that characterize myocardium, skeletal musculature, hepatobiliary system, kidney, pancreas, GI tract, prostate, and protein-nucleic, carbohydrate, electrolyte and mineral metabolism. Seven-day DI w/o countermeasures (n = 5) increased concentration of conjugated bilirubin, suppressed activities of muscular (creatine phosphokinase MM) and myocardial enzymes (CPK MB, OBDH), and caused an upward trend in cholesterol, its atherogenic LDP fraction and triglycerides. Mechanic sole stimulation (n = 6) intensified, within the physiological norm, erythrocyte hematolysis raising total bilirubin and potassium. Despite the stimulation, activity of muscle and myocardial enzymes made a decrease. Blood creatinine decreased to a less extent than in the immersed group w/o stimulation, however, lipid parameters did not rise. High-frequency stimulation of the lower leg and hip muscles in the course of immersion (n = 5) was noted to heighten the activity of muscle enzymes and potassium level in blood beyond the physiological norm. Change in creatinine did not reach a statistical significance and lipid metabolism parameters were not different from baseline values. Application of these physical methods of counteracting deficiency of weight bearing did not interfere with redistribution of body liquids due to immersion. Values of the parameters under study were mostly within the normal limits throughout the experimental exposure suggesting absence of pathological developments during DI or in consequence of physical stimulation. Therefore, the reactions were obviously of normal adaptive character.

[Plasticity of stastocyst inertial mass in terraneous gastropods helix lucorum and pomatias rivulare in altering gravitational field (microgravity, hypergravity)].

Abstract: Light and scanning electron microscopy was used to study the morphological parameters and ultrastructure of Helix lucorum statocysts and statoliths in Pomatias rivulare statocysts after 56, 93 and 110-day exposure to microgravity aboard the ISS. Increased gravity was simulated by 30-d centrifugation at 6 g. On the first day of recovery, many statoconia and statoliths were found to carry numerous warts. Moreover, statoconia grew in number significantly as compared with the ground control. On the contrary centrifugation caused massive destruction of statoconia. In a month after orbital flight and centrifugation morphology of both statoconia and stastoliths was nearly normal. These results evidence, that the gravitational field is an important factor for the abiotic medium responsible for building up the inertial mass in the equilibrium organ of animals.

[Visual-manual tracking during 5-day dry immersion].

Abstract: Level dry immersion (DI), a model of the physiological effects of microgravity, support deprivation, minimization of muscle activity and proprioceptive afferentation specifically, was used to determine the effects of low proprioceptive, tactile and support afferentation on visual-manual tracking. Hand-eye motor coordination was tested in 13 subjects in 5-d DI who tracked jerky and smooth (linear and pendulum-like horizontal and vertical, circular clockwise and counterclockwise) motions of point visual stimulus. Binocular electrooculography was used to register ocular movements and a joystick with a biological visual feedback to register manual motor acts (1 of 2 stimuli on the screen showed the actual joystick inclination). Computerized stimulation was provided with the help of virtual goggles. Evaluated parameters were latent and total reaction time, amplitude and velocity of eye and hand movements, coefficients of effectiveness (amplitudes ratio) and gain (velocity ratio). Testing was performed before DI, after 3 hours in DI, on DI days 3 and 5, during the first hours and in 3 days after DI (all subjects) and on post-DI days 5-7 (4 subjects). It was demonstrated that support deprivation and minimization of proprioceptive afferentation affect ocular tracking to a larger degree than accuracy of the manual motor act of following the visual stimulus. Manual tracking by all subjects was found more accurate than visual and did not alter significantly during tests sessions; on the contrary, visual tracking accuracy altered noticeably as in the course, so after DI.

[Tissue-specific reaction of the mucous coat of herbals' small gut under the influence of spaceflight factors on board biosat "Foton M3"].

Abstract: Methods of light-optical microscopy, morpho- and cytometry and histochemisty were used to study the epithelial lining of herbal's small gut after 12-day flight in biosat "Foton M3". Changes in mucous coat histoarchitectonics included branching of villi and cystic lumps lined with prismatic epithelium. Shortening of the mucous membrane villi was accompanied by reduction of prismatic epithelium height, increase in the number of goblet cells and change of their dislocation, stimulation of excretion of biosynthesis products on the brush border surface pointing to impairment of the interstitial barrier function. Nothing evidenced change in mitotic index of the crypts epithelium in animals of the vivarium control, in the Kontur facility simulating the flight condition, and in the space flown herbals. There was a minor individual variability of changes in the epithelium mucous membrane due to the simulated flight factors.

Dynamics of calcium utilization for skeleton formation in Japanese quail embryos under the microgravity condition

Abstract: Tibia and femur osteogenesis was studied in embryonic lower limbs developed in microgravity. The maximal difference in ash content of shell in the flight and control groups was registered on days 4, 10 and 14 amounting to 10.27; 9.56 and 12.95% respectively. Shell analysis for calcium showed the largest difference between the groups on day 4 (8.94 mg). However, this difference was not seen already on days 14 and 16. Hence, according to the results of the investigation, although shell calcium utilization and osteogenesis in flight embryos of the Japanese quail were retarded, by the time of hatching the morphological and chemical parameters of the lower limb bones were essentially same as of the ground controls.

Histogenesis of the liver of Japanese quail embryos developed in the conditions of microgravity

Abstract: The article reports the results of histogenetic studies of the liver extracted from Japanese quail embryos and hatchlings that had passed the embryonic and postnatal development in microgravity. Comparison of the liver from the flight and laboratory embryos showed identity of organogenesis and histogenesis processes in space and on Earth. However, it should be noted that early histogenetic development of the space embryo liver had been retarded which was concluded from an enlarged lumen in bile capillaries and loose arrangement of epithelium girders as compared with the control On day-10 post flight, the flight embryos exhibited liver induration through narrowing of sinusoids lumen. Haemopoietic zones became less numerous. By the end of embryonic development these histological differences of the flight and control liver disappeared essentially. Organogenesis and histogenesis of the liver obtained from the hatchlings that had spent 5 days in microgravity did not depart from the norm. However, inability of the birds to adapt to microgravity and ensuing starvation was the reason for dystrophic changes in the liver, venous congestion and increased histoleucocytic activity. All the liver changes faded away soon alter the hatchlings were settled in favorable life conditions

Radiation protectors within the radiation safety system for extended duration exploration missions

Abstract: Radiation environment in extended duration exploration missions is scrutinized in the context of the probability of the risks of deterministic and stochastic effects of radiation Though the probability of severe radiation damage due to solar flare is very low, nonetheless it is requisite that the crew must be provided with appropriate, including pharmacological safeguards The current nomenclature of radiation protectors composes short-term agents against acute radiation damage Among the others, preparation B-190 is distinguished by particularly high effectiveness and universal action, and good tolerance even when organism is exposed to the extreme factors of space flight Regimen of B-290 therapy alone and with combination with aminothiol preparations have been developed to render treatment following multiple solar events Effectiveness of radioprotectors can be increased substantially by local shielding of the abdomen and pelvis The most promising nonspecific stimulators of total resistance of organism are riboxin (inosin) and combined preparation aminotetravit as well as vitamins tocopherol and retinol Therapy combining B-190 with riboxin and aminotetravit is also under discussion Cytokine neipogen is also viewed as a candidate agent for early therapy Concern is raised about possible development of chronic oxidative stress in long-duration exploration missions Highlighted is the significance of adequate nutrition supplemented with fresh vegetables as a source of the most valuable bioflavonoids Antioxidants L-selenomethionine and melatonin proved their effectiveness against heavy nuclei of galactic radiation An open issue is how to make natural antioxidants beneficial to oxidative stress control and attenuation of low-intensity galactic radiation

Actiprotective and antihypoxic action of new heteroaromatic antioxidants

Abstract: Expernents with mice showed that most of 15 new heteroaromatic antioxidant compounds possess aciprotective and antixopixic properties. Based on results of treadmill and swimming tests, actiprotective action of IBKhF-1, 11 and 14 surpassed greatly bemythil and bromanthane in ordinary conditions. Inhibitor of gluconeogenase tryptophan cancelled largely the stimulatting action of highly effective and active IBKhF-1, 2 and 11 on physical performance during treadmill exercise. Consequently, gluconeogenesis activation is one of the major components of the actiprotective action of these antioxidants. In addition, IBKhF-1, 11 and 14 excelled bemythil and bromanthane in the extreme conditions of running in hyperthermia and swimming in acute hypoxia combined with hypercapnia. IBKhF-2 and 14 were better than amtisol (standard antihypoxic agent) and bemythil against acute hypoxia in pressure chamber, whereas IBKhF-4 and 14 excelled these agents in thermal chamber.

[Investigation of the evacuatory function of the gastrointestinal tract in 5-day dry immersion].

Abstract: Six male volunteers for dry immersion (DI) modeling the microgravity effects on human organism were subjects in the GI evacuatory function investigation. The investigation was aimed to evaluate liquid food evacuation from the stomach (13C-acetate test) and time of chymus orocecal transit (H2-inulin test). The 13C-acetate test did not reveal changes in stomach evacuatory activity after 4 days in DI. The H2-inulin test demonstrated shortening of chymus transit along the small intestine and extension of chymus passage from the ileum to cecum. Subsequent reduction of inulin metabolism in the large intestine suggested inhibited passage of these GI segments. The results showed that stability of liquid evacuation from the stomach and acceleration of chymus transit along the small intestine hinder evacuation of the large intestine content which is the primary cause for inhibition of GI evacuatory activity in DI.

Theoretical analysis of causes for prolonged delay of decompression sickness onset in divers

Abstract: The analysis of probable causes for anomalously prolonged latent time of developing decompression sickness in divers after completion of air dives was carried out in the content of the theory of formation and subsequent evolution of gas bubbles in body tissues. This phenomenon gives grounds to consider that certain of the decompression bubbles have a prolonged lifetime and gradually increase their affect on adjacent tissues. The main causes of increasing the lifetime of these bubbles are the increase of their sires due to the reduction of tissue perfusion during decompression and the coalescence them to one another, as well the encrustation of bubbles by a layer of intercellular fluid elements that reduces the rate of nitrogen diffusion from bubbles to tissues and retards their dissolution. The bubble layer decreases also the gas pressure inside bubbles due to reduction of the surface tension action of intercellular fluid that results in additional reduction of the diffusion flow of nitrogen from bubbles and the rate of their dissolution. Moreover, taken alone, the process of bubble layer formation seems as one of the main mechanisms of tissue lesions by gas bubbles.

[Effect of 24-hour sleep deprivation on the oculomotor reactions of human operator].

Abstract: The article presents the results of oculomotor reaction investigations during 24-hour sleep deprivation of 10 normal male subjects aged 25 to 30 yrs. Video nistagmograph VNG System VO-25 was used for binocular registration of eye movements. The proposed video procedures for assessment of the functional ability of human operator are a balancing test, investigation of saccadic and smooth tracking eye movements. The balancing test is designed to determine the nystagmic activity, the saccade test, latency, peak velocity and precision of saccades, and the smooth tracking test, standard errors in tracking velocity and displacement In addition to video oculography, velocity of a simple sensorimotor reaction was measured and the self-rating scale of well-being, alertness and mood (SAN) was employed. The balancing test showed balancing nystagmus; occurrence of this nystagmus grew high with desynchronosis. Saccades registered during sleep deprivation pointed to a considerable decline of velocity, less noticeable extension of latency and degradation of precision. Sleep deprivation reduced values of the mean coefficient of gain and increased the standard error in velocity and displacement of smooth eye tracking.

Content of energy substrates in fibers of postural muscle soleus and its antagonist in the condition of support deprivation

Abstract: The investigation had the purpose to measure energy substrates in different fibers of 3- and 14-d suspended postural m. soleus and its main antagonist - anterior tibial muscle in rats. Hindlimb suspension served as a model of gravitational unloading. After suspension, left m. soleus or anterior tibial muscle was extracted. Serial cross-sections were subject to histochemical staining by Oil Red O (Sigma) for determination of intracellular triglycerides or by Schiff's reagent and iododic acid (Sigma-ALDRICH) for determination of glycogen and simultaneous immunohistochemical fibers typing by antibodies to heavy types I and II myosin chains (NCL-MHCs and NCL-MHCf, Novocastra). Analysis of intracellular energy substrates showed that both types of fibers in the anterior tibial muscle had accumulated triglycerides by week-2 of suspension. At the same time, glycogen level in equally slow and fast fibers of m. soleus and fast fibers anterior tibial muscle decreased substantially after 3 days of suspension but returned to baseline value by day 14. These changes are likely to be linked with altered activity of the muscles and hormonal factor.

[Examination of the morphofunctional properties of red blood cells of humans in 5-day dry immersioin].

Abstract: Blood of six normal male volunteers sampled before, immediately after and in 7 days since 5-d dry immersion was analyzed for morphological parameters, erythrocyte metabolism, lipids and phospholipids levels. The experimental exposure was shown to increase the erythrocyte count. Also, upward trends were displayed by hemoglobin and PCV on the first day after the experiment; a significant decrease in adenosine triphosphate and low level of reduced glutathione could be an outcome of enhanced oxidation in cell due to, maybe, LPO activation. There was a downward trend in the phospholipids fraction of erythrocyte membrane against steady levels of cholesterol and its ethers which might be linked with the reliable growth of the fraction of nonesterified fatty acids on day 1 and triglycerides on days 1 and 7 post the experiment.

[Some clinical outcomes of fractional gamma-irradiation of primates].

Abstract: The investigation with macaque-rhesus males aged 3 to 5 years was aimed at evaluation of the effects of 2 patterns of fractional gamma-irradiation ending up with an equal effective residual dose of 100 sGy Irradiation was carried out on gamma-ray unit GOBO-60 with a 137Cs source and certified activity of 72 g-eq Ra Rectal temperature, heart rate, blood pressure and body mass were followed up over the period of 9 months Rate of body mass gain in primates irradiated with the total gamma-dose of 250 cSv was lower as compared to the group that received the total dose of 132 cSv Repeated irradiation 3 months later elevated the body mass gain and elevated rectal temperature considerably only in the primates that had been initially irradiated at 250 cSV Fractional gamma-irradiation had no effect on HR or BP

Style of communication between mission control centers and space crews

Abstract: The article deals with a pilot investigation into the audio communication of cosmonauts with ground controllers. The purpose was to verify in space flight the patterns and trends revealed in model tests of intergroup communication, and to pinpoint the signature of multinational crew communication with 2 national mission control centers (MCCs). The investigation employed authors' content-analysis adapted to the scenario of long-duration mission. The investigation resulted in a phenomenon of double-loop ground-orbit communication, divergence, difference in opinion predictable from the concept formulated by G.T.Beregovoi. Also, there was a notable difference of expressions used by controllers of 2 MCCs.

[Analysis of the relationships between the psychophysiological status and system of adaptive immunity in the conditions of 5-day dry immersion].

Abstract: Relationships of the T- and B-components of adaptive immunity and the psychophysiological status were studied in 14 volunteers for the experiment with 5-d dry immersion (DI) w/o countermeasures. Comparison of frequency of deviations in immunity parameters of psychologically different subjects demonstrated the highest frequency in non-anxious and extravert individuals on day-5 in DI. These differences in immune reactions as a function of psychological type and temperament point to existence of a neuroimmune typology and, therefore, the necessity of concurrent immunologic and psychological investigations in order to develop separate measures of rehabilitation from and prevention of stress in people with polar psychological status.

The cascade scheme as a methodical platform for analysis of health risks in space flight and partially and fully analog conditions

Abstract: Space anthropoecology, a subsection of human ecology, studies various aspects of physiological, psychological, social and professional adaptation to the extreme environment of space flight and human life and work in partially- and fully analogous conditions on Earth. Both SF and simulated extreme conditions are known for high human safety standards and a substantial analytic base that secures on-line analysis of torrent of information. Management evaluation and response to germing undesired developments aimed to curb their impact on the functioning of the crew-vehicle-environment system and human health involve the complete wealth of knowledge about risks to human health and performance. Spacecrew safety issues are tackled by experts of many specialties which emphasizes the importance of integral methodical approaches to risk estimation and mitigation, setting up barriers to adverse trends in human physiology and psychology in challenging conditions, and minimization of delayed effects on professional longevity and disorders in behavioral reactions.

[Lipid peroxidation and antioxidant protection system in cosmonauts following short-term missions to the International Space Station].

Abstract: Blood serum of Russian members (n = 21) of the 8 to 12-day visiting missions to the ISS was analyzed before and after mission for products of lipid peroxidation, i.e. diene conjugates, malone dialdehyde, Schiff bases and tocopherol, the primary lipid antioxidant. No reliable change was found in the parameters postflight as compared with preflight values. It may be concluded that 14 days in orbital flight and the factors of re-entry and early recovery do not affect significantly the mechanisms of free radical lipid oxidation and functioning of the antioxidant protection system.

[Space flight and modeling experiments: new approaches to evaluation and prophylaxis].

Abstract: The article dwells on the general issues of orthostatic tolerance and new impedance methods of orthostatic test evaluation in spaceflight and simulated microgravity. The results imply that OT requires adequate body hydration and functioning of volume-regulating hormones. New pharmacological compensators of orthostatic intolerance were tested in modeling experiments. It was shown that desmopressin and water-salt supplements retain body liquid and electrolytes during bed rest and improve tolerance of the orthostatic test Therefore, simultaneous control of the hydration status and OT can be best provided through physiologically reasonable prescription of synthetic ADH analogs.

Redistribution of body liquids in the conditions of microgravity and simulation of its effects

Abstract: The review is devoted to shifting of blood and other liquids along the body axis toward the cranium end in microgravity and during simulation of the zero-g physiological effects. The body liquids redistribution excites a number of consistent physiological reactions as well as a cascade of secondary adaptation processes. Changes occur in central venous pressure and size of the heart cavities, renal function and hormonal volumoregulation entailing the adaptive shifts in body liquid segments. Hemodynamic changes in the splanchnic vascular system affect functioning of the abdominal organs. Measures of pharmacological correction expedite human adaptation to unusual environments.

[Change in sensitivity of the central respiration mechanism in the 21-hour bedrest conditions].

Abstract: The investigation was aimed at studying the mechanisms for change in the respiration center sensitivity in consequence of 21-hr bed rest with head-end tilted at -15 degrees combined with liquid loss (lasix, 20 ml) and recovery (IV infucol and glucose). Time of maximal breath-holding, capillary and venous O2 and CO2 pressure values were measured in the baseline data collection period, during and shortly after BR. Data analysis showed that extension of the maximal breath-holding time both during inspiration and expiration was statistically significant in the initial 10 minutes of tilting. Comparison of the breath-holding test data between the experimental series demonstrated that infusion of equally glucose and infucol did not affect voluntary apnea during inspiration or expiration. From BR hour 17, partial pressure of venous O2 showed a significant rise, while venous CO2 pressure decreased, also significantly. It is hypothesized that degradation of the respiration center sensitivity was connected most likely with blood pooling in the upper body and altered pressure on the baroreceptors.