NEUROPHYSIOLOGICAL STATE OF HUMANS IN LONG-DURATION ISOLATION.

During the 520-d imitation of isolation and confinementin a long-duration exploration mission, the neuroufunctional state of 6 crewmembers was studied by synchronous registration of cerebral electrical (EEG) and energy (permanent potential level (PPL)) activities of the brain. Two baseline investigations predicted high adaptability of all crew members and low probability of depletion of the adaptation reserve in the experiment. During isolation, dynamics of neurofunctional correlates of the cerebral activity was generally proportionate to the factors the crewmembers were affected by. Events epochal to the crew gave rise to physiological reactions both of the metabolic and electrical activity of the brain. On week 54, crew physiological adaptation to the experimental environment was manifested by decreases in PPL without interhemispheric asymmetry and absolute a-power. All through the experiment none of the crew members showed signs of a distinct stress-reaction (a-activity asymmetry with a significant PPL decrease) supporting our prediction of low probability of adaptation reserve depletion in participants in the 520-day isolation and confinement study.

[Effects of the 520-day isolation on the functional state of the cardiovascular system].

Purpose of the work was to study the cardiovascular effects of simulated factors in a 520-day crewed mission to Mars, and to validate the diagnostic value of the ultrasonic investigation of microcirculation and endothelium-dependent dilation of the right brachial artery in 6 male volunteers at the age of 28 to 39 years. It appears that 520-d isolation affected intracardiac hemodynamics and endothelium function more dramatically compared with 105-d isolation, increasing the risk of atherosclerosis. These findings add insight into the "cost of human adaptation" to very long isolation.

[Express diagnostics of microbial status of humans in 14- and 105-day isolation].

Automated digital image microscopy was used to evaluate skin microbial populations in 14- and 105-day isolation experiments within the Mars-500 project.

[Evaluation of efficiency of automated analysis of microflora from test-subjects during 7-day dry immersion].

Microbial contamination of integument was evaluated in test-subjects volunteered for 7-day immersion with the purpose to evaluate a technology of automated analysis of human microbiocinosis. Integument microflora was investigated in the baseline data collection period and on day-7 of immersion with the help of the standard bacteriological method and using a prototyped automated analyzer. The investigation showed the possibilities of the automated analyzer to provide operating data about human microflora.

[Investigation of cardiovascular adaptation to postural passive test in the course of selecting candidates for special contingent].

Selection of candidates for special contingent is made with the focus on evaluation of cardiovascular functioning and adaptability to stresses, and detection of pre-disease shifts in CV regulation. Hemodynamics regulation was assessed by tilt testing of 15 essentially healthy men at the age of 18 to 34. The tilt table was initially at 0 degrees (baseline), turned at +75 degrees (20 min), and then back to 0 degrees for 5-min recovery. Simultaneously with the standard measurements of ECG and blood pressure, the myocardium state was registered with the use of KardioVizor-06; cerebral circulation was evaluated using rheoencephalography and microcirculation vessels, -ultrasonic Doppler. Three human subjects exhibited hypotensive reactions to the tilt test and two showed hypertensive reactions. However, no changes were present on ECG records. Hence, in-depth investigation of the CV reaction to tilt test is capable to reveal incipient regulatory disorders and their trend, and to assess adaptability to stresses.

[Screening-diagnostics of the myocardium during test-loading on bicycle ergometer].

Diagnostic and prognostic potentiality of KardioVizor-06 (KV) in early detection of deviations in the myocardium electrophysiological parameters was assessed with the standard functional test on bicycle ergometer. The investigation was performed with participation of 10 essentially healthy subjects of different age groups. Data obtained with KV (baseline, test and recovery) were compared and contrasted with the results of standard ECG (12 leads) and BP methods. Data agreement was observed in 90% of cases; KV undervalued test tolerance in 10% of cases. Close examination of ECG verified the presence of incipient deviations in the myocardium. Therefore, unlike other methods, the technology provides unique information and foretells pathology discerning transient functional disorders. High noise immunity of the automated analysis of ECG dispersing changes makes the device applicable directly during functional loading tests.

[Microcirculation stream modeling: hydromechanic and acoustic models].

The objective was to attempt mathematical modeling of ultrasonic scanning tissue section in order to discern signals from erythrocytes and leucocytes that is displayed as Doppler images. Hydromechanic and acoustic microcirculation models have been constructed for a 20 MHz ultrasonic sensor. Results of the modeling showed that ultrasonic blood cells differentiation will require complex analysis of amplitude and frequency parameters of echoed signal.

[Development of an automated microbiological analyzer].

An automated hematological analyzer, prototype of a quick microbiological diagnostics system, was tested positively for the ability to differentiate microbial cells (six test-strains with different morphological and tinctorial properties) by geometry and dye intensity.

[Prevention of altitude decompression sickness during simulation of egress from the cabin of space vehicle with hypobaric artificial atmosphere]. / Profilaktika vysotnoi dekompressionnoi bolezni pri imitatsii vykhodov iz kabiny kosmicheskogo korablia s gipobaricheskoi iskusstvennoi gazovoi atmosferoi.

Based on the proposed semiempiric nomograms, the study was aimed at selection and investigation of normoxic N2-O2 hypobaric atmosphere (HA) at 93-73 kPa, and evaluation of effectiveness of the gas mixture against the altitude decompression sickness (ADS) during 6-hr simulation of extravehicular activities at 37 kPa without prebreathing. Subjects were 22 healthy males from 20 to 50 yr. old. In all, 115 experiments were performed. Twenty-four hours in HA at 93 kPa and subsequent transition to 37 kPa led up to development of ADS symptoms by one subject in one of 27 experiments (3.7%), and emergence of venous gas bubbles (USI) with the intensity of 2, 70, and 19 points by the Spenser scale in 9 experiments (33.3%). Lower HA pressures (86 kPa, 80 kPa and 73 kPa) did not give rise to ADS though the occurrence of venous GB distinctly tended downward (30.6%, 14.3% and 11.8%) and so did the intensity of their entry into the pulmonary circulation (2, 40, 18 points; 1, 80, 19 points, and 2, 00, 15 points, respectively). Minimal ADS risk was observed in HA at 80 kPa and 73 kPa and did not reach 4% at the confidence level of 95%.

[The assessment of the risk of altitude decompression sickness during simulation of repeated (with 12 hour interval) exits into open space]. / Otsenka riska vysotnoi dekompressionnoi bolezni pri imitatsii povtornykh (s 12-chasovym intervalom) vykhodov v otkrytyi kosmos]

Purpose of the investigation was to assess contribution of repeated (with a 12-hr interval) decompression to the risk of altitude decompression sickness (ADS) by simulation of 6-hr extravehicular activities (EVA) of space crewmembers in altitude chamber. The protocol included "ascents" of 6 essentially healthy male subjects at the age of 24 to 51 to the altitude of 7,600 m (37 kPa) following 30-min prebreathing (elimination of nitrogen from the body by breathing pure oxygen through a mask at the ambient pressure of 73 kPa = 2,600 m). Each subject participated in 2 experimental exposures: first initial and then repeated decompression. None of 24 "ascents" produced clinical signs of ADS. Comparison of the data concerning frequency and time points of detection by ultrasonic Doppler equipment of gas bubbles (GB) in the venous bed during decompression with initial, maximal and mean values of US signal intensity failed to state a significant difference between them. Data of the investigation were confronted with anticipated length of GB dispersion in body tissues.

[The monitoring of gas bubbles with a pulsed Doppler ultrasonic locator in humans working in a space suit]. / Monitoring gazovykh puzyr'kov ul'trazvukovym impul'sno-dopplerovskim lokatorom u cheloveka pri rabote v skafandre.

Presented are results of gas bubbles monitoring in decompressed humans with the use of an ultrasonic pulse-Doppler locator (PDL). Unlike the classic Doppler bubbles detectors with continuous US emission, PDL is adjusted for reception of echo from a chosen volume of the right ventricle cavity; thus, the clutter due to cardiac beats and human locomotion is successfully rejected. During simulation of Russian EVAs, venous gas bubbles were detected in 3 out of 5 experiments with test-subjects clothed in everyday wear and in 2 out of 3 experiments with suited test-subjects.

Fatty acid composition of plasma lipids and erythrocyte membranes during simulated extravehicular activity.

Ten subjects (from 27 to 41 years) have been participated in 32 experiments. They were decompressed from ground level to 40-35 kPa in altitude chamber when breathed 100% oxygen by mask and performed repeated cycles of exercises (3.0 Kcal/min). The intervals between decompressions were 3-5 days. Plasma lipid and erythrocyte membrane fatty acid composition was evaluated in the fasting venous blood before and immediately after hypobaric exposure. There were 7 cases decompression sickness (DCS). Venous gas bubbles (GB) were detected in 27 cases (84.4%). Any significant changes in the fatty acid composition of erythrocyte membranes and plasma didn't practically induce after the first decompression. However, by the beginning of the second decompression the total lipid level in erythrocyte membranes decreased from 54.6 mg% to 40.4 mg% in group with DCS symptoms and from 51.2 mg% to 35.2 mg% (p<0.05) without DCS symptoms. In group with DCS symptoms a tendency to increased level of saturated fatty acids in erythrocyte membranes (16:0, 18:0), the level of the polyunsaturated linoleic fatty acid (18:2) and arachidonic acid (20:4) tended to be decreased by the beginning of the second decompression. Insignificant changes in blood plasma fatty acid composition was observed in both groups. The obtained biochemical data that indicated the simulated extravehicular activity (EVA) condition is accompanied by the certain changes in the blood lipid metabolism, structural and functional state of erythrocyte membranes, which are reversible. The most pronounced changes are found in subjects with DCS symptoms.

[Fatty acid composition of the lipids in human blood plasma and erythrocyte membranes during simulation of extravehicular activities of cosmonauts]. / Zhirnokislotnyi sostav lipidov plazmy krovi i membran éritrotsitov u cheloveka v usloviiakh, imitiruiushchikh vnekorabel'nuiu deiatel'nost' kosmonavtov.

Dynamics of the lipoacidic content of total plasma lipids and erythtocyte membranes was studied in 32 experiments with ten apparently healthy male subjects aged 27 to 41 years who were exposed to repeated decompression from the normal ground down to 40-35 kPa. For two hours of exposure to lowered pressure the subjects were breathing pure oxygen in mask and performing incremental physical work mimicking loading of the upper extremities of cosmonauts doing extravehicular activities (EVA) at the energy cost of 3 kcal/min. Decompression sessions were repeated with intervals from 3 to 5 days. In seven experiments, the subjects developed symptoms of the decompression sickness (DCS). Penetration of gas bubbles (GB) into the pulmonary artery was registered in 27 cases (84.4%). In 24 cases maximal intensity of the US signals from GB reached 3 to 4 Spencer's points. No changes in the lipidoacidic content of blood plasma or erythrocyte membranes were determined following the first exposure to decompression. BY the onset of repeated decompression, total number of lipids in erythrocyte membranes decreased from 54.6 to 40.4 mg% in the group of subjects who had not displayed DCS symptoms (n = 5) and from 51.2 to 35.2 mg% (p < 0.05) in the group of subjects with DCS symptoms (n = 5). In the subjects with DCS, polyunsaturated linoleic acid (18:2) tended to decrease against the upward trend of saturated fatty acids (16:0, 18:0). In these subjects, arachidonic acid in erythrocyte membranes (20:4) decreased following each decompression exposure and significantly increased (p < 0.05) in-between. In both groups, blood plasma showed slight fluctuations in the lipoacidic contents. These data suggest that exposure to the variety of the EVA-simulating factors may entail quite distinct but reversible modifications in the lipid metabolism in blood and the structural/functional state of erythrocyte membranes. The most marked alterations were observed in the subjects with the DCS symptoms during high intensity of US signals from GB in the venous blood flow.