[TESTING THE PROTECTIVE PROPERTIES OF ARGON DURING SUBACUTE EXPOSURE TO HYPOXIC HYPOXIA].

Previously it has been shown that argon has a stimulating effect on biological processes including, specifically, strong protective properties during exposure to acute (1-4 hrs.) hypoxic hypoxia. Experiments with animals under hypoxia gradually growing over 3 to 7 days may give insight into mechanisms of the argon protective action. Purpose of the work was to explore character and severity of developing disorders, to attempt their prognosis and to test potentiality of argon as a protector from the effects of subacute hypoxic exposure. In two series of experiments Wistar male rats were housed in pressure chambers with different rates of O2 reduction without argon and with argon in concentration of 32-38%. Oxygen reduction from 20.9 to 9.0% in 3 days led to the death of 50% animals. Oxygen reduction to 12.0% in 7 days and one day in low-oxygen atmosphere was harmless for animals. Argon in air makes the response to hypoxia almost twice as sharp on virtually every level (red blood system, physiological, morphological and biochemical shifts) validating the concept that argon acts as a stimulator. In context of the most critical processes of adaptation to hypoxia--activation of blood formation and lipid metabolism--this sharpening of the response results in depletion of body resources and instigates irreversible shifts.

[Mechanisms of natural variability at adaptation of human physiological systems to conditions of space flight].

This article analyzes the physiological data using the principle of invariant relationships, to reveal the mechanisms of adaptive variability. It was used physical-chemical, biochemical, and hormonal blood parameters of cosmonauts who have committed short-term and long space flights. These results suggest that application of the methods of fractal geometry to quantitative estimates of homeostasis allows to allocate the processes depending on the increase/decrease of adaptive variability and fix the state of stability or instability of certain physiological regulatory subsystems, due to mobility and to reduce the level of stability which remains stable internal structure of relationships throughout the body.

[Profile of sex steroids in healthy volunteers' urine during experiment in isolated object].

The quantitative determination a number of endogenous steroids and their metabolites in urine of healthy volunteers by means of gas chromatography - mass spectrometry was performed. The dynamic of steroid profile of healthy individuals as well as possible ranges of several endogenous steroid parameters have been investigated. Samples were obtained during 105-days experiment with 6 volunteers in isolated on ground modules where were modeling the main life conditions which could influence the steroid profile: meal volume and composition, water consumption, motion activity, air composition and temperature, rate sleep - wakefulness and emotional tension. The parameters of urine steroid profile of healthy volunteer which were affected by life conditions in isolated object were revealed. The parameters of individual and group variability of steroid profile and its dependence from definite experiment conditions - change of salt consumption periods, autonomy of vital activity were detected.

[Choice of statistical approaches and analysis of blood serum proteome profiles in an experiment with 24-hour head-down tilt (-15 degrees)].

Variability analysis of normal human proteoma requires a valid and crisp algorithm for mass-spectrometry data analysis. The goal was to test methods of statistical analysis of blood serum proteoma profiles in an experiment with 24-hr. HDT using the small sample nonparametric criteria. The investigation revealed peaks that appear to be a molecular response of organism to simulated microgravity. Further identification of fiducially mobile peaks with the help of tandem mass-spectrometry will enable disclosure of subtle mechanisms of adaptation to the spaceflight factors and improvement of human health evaluation in space missions of varying length.

[Cluster analysis applicability to fitness evaluation of cosmonauts on long-term missions of the International space station].

Cluster analysis was applied to evaluate locomotion training (running and running intermingled with walking) of 13 cosmonauts on long-term ISS missions by the parameters of duration (min), distance (m) and intensity (km/h). Based on the results of analyses, the cosmonauts were distributed into three steady groups of 2, 5 and 6 persons. Distance and speed showed a statistical rise (p < 0.03) from group 1 to group 3. Duration of physical locomotion training was not statistically different in the groups (p = 0.125). Therefore, cluster analysis is an adequate method of evaluating fitness of cosmonauts on long-term missions.

[Body fluids ratio and postural stability of head-down tilted apes in the periods of transition into the active vertical position].

It is known that the hypokinetic syndrome and alteration of the hydrostatic component by microgravity distort functioning of various body systems. Prevention of the adverse effects is achieved through implementation of a variety of physical exercises during tilting, and periodic transition into the upright position. The investigation was performed with 11 Macaques (Macaca mulatta) 3 to 5 yrs. of age and 3.2-7.2 kg of weight. Brief (for 30 to 120 min 4 or 5 times a wk.) transition into the active upright position had a positive effect on the body liquids ratio modification in the course of 27-d HDT (-5 degrees). This was concluded from a less pronounced loss in the amount of extracellular liquid and its interstitial component. In addition, another positive result of this manipulation was less, in terms of volume and speed, significant gravity-dependent blood flow toward the lower limbs during 10 minutes of standing test at the end of the experiment as compared with their controls w/o the preventive manipulation.

[Effects of medium with elevated partial pressure of argon and nitrogen on morphology of Escherichia coli colonies].

The purpose was to study morphological specifics of microbial colonies cultivated in argon-containing gas medium. Investigated were computerized images of the colonies of museum strains Escherichia coil K-12. It was found that combination of elevated argon pressure (1 ata) and nitrogen pressure (1.8 ata) increased the maximal density of microbial colonies and decreased the colony size as compared with cultivation in argon only.

[Prevention of the adverse effects of head-down tilting on the infrastructure of body fluids and postural stability of primates by exposure to g-loads]. / Profilaktika neblagopriiatnogo vliianiia antiortostaticheskoi gipokinezii na infrastrukturu zhidkostnykh sred organizma i postural'nuiu ustoichivost' obez'ian s pomoshch'iu gravitatsionnykh vozdeistvii.

Experiments with 24 primates (Macaca mulatta) demonstrated that head-down tilting (-5 degrees) altered their hydration status as was manifested by a significant diminution of the amount of extracellular fluids, the interstitial fraction specifically. Blood circulation in leg muscles reduced almost in half In addition, return of the animals to the orthostatic position at the end of the experiment did not cause so intensive blood redistribution in leg vessels as in the group of tilted but not rotated animals.

[Blood plasma volume dynamics in monkeys during immersion]. / Dinamika ob"ema plazmy u obez'ian v usloviiakh immersii.

Dynamics of blood plasma volume (PV) was studied with indirect methods (hematocrit count, hemoglobin, total protein and high-molecular protein) during 9-d immersion of monkeys Macaca mulatta. The animals were donned in waterproof suits, motor restrained in space seat liners and immersed down to the xiphisternum. Two monkeys were immersed in the bath at one time. The suits were changed every day under ketamine (10 mg/kg of body mass). There were two groups with 12 animals in each. The first group was kept in the bath 3 days and the second--9 days. Prior to the experiment, the animals had been trained to stay in the seat liner put down into the dry bath. It was shown that already two days of exposure to the hydrostatic forces (approximately 15 mm Hg) and absence of negative pressure breathing reduced PV by 18-20% on the average in all animals. Subsequent PV dynamics was individual by character; however, PV deficit persisted during 4 days of immersion in the whole group. In this period, albumin filtration was increased significantly, whereas high-molecular protein filtration was increased to a less degree. During the remaining days in immersion PV regained normal values. Ten days of readaptation (reclined positioning of monkeys brought back into cage) raised VP beyond baseline values. This phenomenon can be attributed to the necessity to provide appropriate venous return and sufficient blood supply of organs and tissues following extension of blood vessels capacity.

[Mathematical algorithm for evaluation of the human cardio-respiratory homeostatic function]. / Matematicheskii algoritm otsenki gomeostaticheskoi funktsii kardiorespiratornoi sistemy u cheloveka.

Mathematical algorithm of the cardiorespiratory homeostasis was determined by oxygen demand (VO2) and carbon dioxide production (VCO2) during maximal physical loading on the bicycle ergometer; calculated and measured parameters of the physical capacity were compared in experiments with long-term (110- to 240-d) isolation of human subjects. Aerobic capacity was evaluated during incremental physical testing in the sitting position on bicycle Elema-Siemens 380-B. The following parameters were measured: peak (maximal loading) heart rate (HRpeak) and VO2, work time, and VO2 at 15 points on the Borg load scale, total aerobic test time and some others. Analysis of the homeostatic function of the cardiorespiratory system with the integral H = (h(u)du failed to state statistically reliable differences (p > 0.05) before and after isolation in group-1; however, it evidenced an increased homeostatic ability (p < 0.05) in group-2 and a decreased homeostatic ability in group-3 after isolation. Hence, the proposed mathematical algorithm showed a good agreement with the aerobic capacity parameters measured using classic methods. There was a high correlation (p < 0.05) between the homeostatic function and aerobic capacity in the groups of subjects and, therefore, determination of the cardiorespiratory homeostatic function can be considered an additional evaluative criterion.

Effect of static and dynamic influences on receptors of equilibrium organ of Helix lucorum after 163-day orbital flight in "Mir" station.

A 163-day orbital flight increased the baseline impulse activity of statocyst receptor cells in terrestrial pulmonata snail Helix lucorum. The maximum of reaction to step static stimuli (changes in body position in the range from 0 to 180 degrees) was significantly shifted by 30 degrees from gravitational vertical, while the reaction to dynamic stimuli (dumped sinusoidal oscillations) faded more rapidly than in control animals.

[Electrophysiological characteristics of the statocyst receptor cells in snails Helix lucorum following exposure to microgravity in unmanned spacecraft "Foton" and piloted space station "Mir"]. / Elektrofiziologicheskie kharakteristiki retseptornykh kletok statotsista ulitok Helix lucorum, éksponirovannykh v nevesomosti na avtomaticheskom kosmicheskom apparate "Foton" i pilotiruemom orbital'nom komplekse "Mir".

Following 16-, 53-, 73- and 163-d orbiting, the background pulsation of the statocyst receptor cells (statoreceptors), the equilibrium organ in land pulmonary snails Helix lucorum, was found increased. Alteration of the body spatial position (2-min tilt at 90 degrees toward the upsilateral side) in the space-flown snails was noted to occur with delayed dying away of the pulsation rate. During stepwise (30 degrees) tilts in the range from 0 to 180 degrees, the maximum of the reaction was shifted by 30 degrees from the gravitational vertical; during dynamic tilting (sine decaying oscillations) the reaction subsides more rapidly as compared with the control animals. Absence of changes in pulsation of receptor cells in statocysts deprived of feedback with the nervous centers may be suggestive of inactivation of the efferent innervation in consequence of exposure to microgravity.

[Development of multidimensional scaling methods in biomedical research]. / Razvitie metoda mnogomernogo shkalirovaniia primenitel'no k praktike mediko-biologicheskikh issledovanii.

Analyzed were different approaches to the construction of multidimensional scales to be used in comparison of experimental biomedical data. Pinpointed were weak points of the existing models. Multidimensional scaling algorithms can be adapted by substituting the notion of "measure of nearness" between characteristics studied with the dispersion analysis which is the most valuable part of the multidimensional methods--orthogonal scaling (from one up to three scales). Integral criterion D2 1,2 allows evaluation of both individual and typological reactions of the body systems to various factors.

[Stimulation of bone fracture healing in rats under the support load deficit]. / Stimuliatsiia zazhivleniia perelomov kostei u krys pri defitsite opornykh nagruzok.

Experiment with rats the hind limbs of which were deprived of support loads (tail suspension) for two weeks following operational fracture of fibular bones evidenced inhibited callus formation and lowered strength of bone fragments consolidation. Injection of anabolic steroid retabolite to the traumatized animals together with limited support loading was favorable to the bone callus formation and consolidation of fragments. This measure also distinctly increased the functional activity of adenohypophysial somatotrophs (growth hormone producers) and thyroid C-cells (calcitonine producers). The direct dependence of bone fracture healing on the somatotropic function of the adenohypophysis suggests that the favorable effect of retabolite combined with the support loading is at least partly achieved through the somatorophic function of the adenohypophysis.

[Prediction of the body resistance to chronic irradiation by different dose rates using the generalized logarithmic index]. / Prognoz ustoichivosti organizma pri khronicheskom oblucheniia s razlichnoi moshchnost'iu dozy s ispol'zovaniem obobshchennogo logarifmicheskogo pokazatelia.

Patterns of radiation damage development and reparation of the blood-forming system in mice and rats were outlined from calculated values of the generalized logarithmic index for chronic irradiation by different dose rates. Dynamics of the generalized index in the course of chronic irradiation makes the basis for predicting deviations in the resistance of animals during next irradiation session.

[The influence of hypokinesia on the mother-fetus system]. / Vliianie gipokinezii na sistemy "mat'-plod".

In experiments with rats effects of hypokinesia on the course of pregnancy and the mother-fetus system were investigated. Immobilization in penal-type cages of female rats on days 8 through to 19 of pregnancy gave rise to significant shifts in mother's organism, i.e. retarded body mass gain, mass reductions in thymus, spleen, liver, some other organs, and adipose tissue. Rates of prenatal fatality in the experimental group were not changed; yet, fetuses were behind the control by the values of body mass, ossification ranges, development of analyzers and other parameters. Quantities of liquid, sodium, magnesium and calcium per one gram of dry tissue were equal in the experimental and control fetuses. Comparison of the data with results of the embryological experiment with rats aboard the space "shuttle" suggests that immobilization is more baneful for the mother-fetus system than microgravity of the same length.