Interferential electromyography (iEMG) was used to investigate influence of the bone conduction sound on the Kohnstamm phenomenon (post-activation effect, PAE) in a group of neurologically and oto-neurologically healthy young and middle-aged participants (n = 15; 11 females and 4 males at the age of 21 to 61 years). Bone conduction sound at 110 Hz and 40 dB was transmitted to the tragus of both ears over 5 min before PAE, during a minute of PAE-inducing voluntary isometric activity, and prior to the PAE completion. Sequence of the «no-sound» and «sound» periods was randomized. Parameters were compared using the Wilcoxon criterion. In the «no-sound» period, PAE was observed in 13 out of 15 participants (86.7 %). In the «sound» period, PAE was observed in all participants; noteworthy, 2 participants demonstrated an additional PAE period. During the «sound» condition, PAE duration increased 35 % (p < 0.01) in 12 out of 13 participants; however, iEMG and PAE latency did not change (p > 0.05). Thus, bone conduction sound intensified the Kohnstamm effect due to the PAE prolongation that is possibly associated with activation of the reticulospinal tract.
The review dwells upon the investigations of plant growth and development in extreme environments such as the long-term studies with imitation of space missions at the IBMP Ground Experimental Facility (NEK). It was shown that the extreme environment of this pressurized habitat did not dramatically change properties of higher plants and, therefore, we can have a positive outlook on integration of greenhouses in the life support systems of advanced space vehicles and planetary bases. Approaches have been developed to investigate the operator-greenhouse-plants system with consideration for the types of human personality.
Longitudinal g-loads on a short-arm centrifuge (SAC) are considered as a promising countermeasure against orthostatic instability after space missions. Yet, safety of repeated sessions in context of cumulative effect and risks of gravitational heart deformation requires evidence and validation. Six normal male subjects (38 ± 7 y.o.) participated in five 45-min SAC runs with alternation of +1.27 and +2.06 G to feet (+Gz). Levels of ST2, NT-proBNP и D-dimer (ELISA), heart rhythm variability and blood pressure were determined prior to and after rotation. Nonparametric criteria were used for static analysis. Series of rotations did not produce significant changes in NT-proBNP, ST2 and D-dimer in the group. Individual analysis pointed to heterogeneity of the reactions which remained stable or decreased in most of the subjects. There were single instances of temporary rises of ST2 and D-dimer but not clinical manifestations. During rotation, heart rate (HR) increased and vegetative regulation shifted markedly towards sympathetic at the end of rotation. From the first to the final rotation, concordance of mean dynamic BP and HR increased. After the rotations, HR increase during the standing test was less than in control which suggested a blunted sympathetic reactivity. These results attest to the positive training effect of interval SAC rotations and absence of manifestative overdistention of cardiomyocytes, risk of thrombosis or negative dynamics of vegetative regulation. Consequently, our data confirm safety of this training protocol for healthy people; they evidence also for individual approach to assessment of g-tolerance.
Experiments with rats showed that new nicotinamide derivatives LKhT 8-22 and LKhT 12-22 at a dose of 50 mg/kg have a distinct vestibuloprotective effect demonstrated by an increased food intake after rotation in 2.4 and 1.8 times, respectively. Efficiency of these substances exceeded the reference medicine mexicor (ethylmethylhydroxypyridine succinate) in equal dose in 1.7 and 1.3 times, respectively. More effective LKhT 8-22 exceeded LKhT 12-22 in 1.3 times.
Periodontium health was studied in members of year-long isolation project SIRIUS-23. Microbiological and immunological analyses of oral liquids were made to evaluate efficacy of oral gel Fagodent with bacteriophages. Participants were 6 normal people (2 men and 4 women) at the age of 26 to 38 years. Liquid samples were collected 5 days prior to isolation (baseline data), on day 14 in isolation, in every 30 days in isolation, and on day 14 after isolation. Sampling was performed before hygienic procedures and breakfast; tooth brushing was not allowed on two previous days. The participants were divided into two groups with 3 members in each. All time in isolation, one group used Fagodent daily in 2-month courses with a 30-d break between courses. The other group started using a lactoferrin-based rinse in 7-d courses on month-3 of isolation. Samples were analyzed with the use of mass-spectrometry, bacteriological and biochemical techniques. Non-pathogenic microorganisms prevailed in members of the group that used Fagodent and, therefore, enhanced their local humoral immunity. Gel and rinse both had a positive effect on the oral health of participants in this study.
Efficiency of a patented method for decontamination of sanitary and hygienic wastes using carbon dioxide was tested in the SIRIUS-23 project aimed to imitate a long-term mission to the Moon. The decontaminator is intended for disinfection or killing of microbial organisms to a preset level in a critical/subcritical state. To perform the investigation, sanitary and hygienic wastes were picked out from the household refuse which was subject to sterilization and biodegradation. Content and amount of airlocked refuse and mass of specific fractions were determined. Total mass of the waste for decontamination made up 6 kg. Preliminary tests demonstrated ability of the decontaminator to eradicate unsanitary microorganisms, including spore-forming bacilli. Testing was performed with cultures of Staphylococcus aureus, Escherichia coli, Candidaalbicans, Bacillus subtilis. Level of decontamination (CO2 within 50 bars, 50–70 °C, f 30-60 minutes) was verified by inoculation on special purpose nutrient media according to the ISO and Russian standard (GOST) guidelines. These results may help in designing life support systems, regeneration and waste management units for remote space missions and habitable bases on the Moon and Mars.
Association between physical and cognitive performance in the condition of monotony is still not fully understood. Purpose of this work is to describe bioelectrical activity of the brain cortex and efficiency of cognitive tasks after physical loading in participants in ground-based model 12-month experiment SIRIUS-23. SIRIUS-23 involved 6 subjects (4 females and 2 men). Sessions were performed at the beginning of each mesocycle of physical locomotor exercises approximately once a month. The test consisted of the gradual loading up to 15 km/h on the active treadmill and a battery of cognitive tests. EEG was registered before and after exercise in each second session, and after completion of the cognitive test. The cognitive battery included the Stroop test, number memory test, moving target test, Gorbov-Schulte red-black tables, and Torrance test. Results of the cognitive tests showed significant individual differences (p < 0.05). Physically strong participants completed these cognitive tests with better results. EEG analysis points to individual differences of the rhythm index and mean alpha-range. Additionally, these indices rose after physical loading and decreased following cognitive testing. Decline of individual alpha-peak frequencies observed during experimental sessions suggests tiredness. After physical loading, mean EEG coherence made an increase in alpha-power between the central and frontal regions.
In space flight, the human organism is subjected to various hostilities such as microgravity, ionizing radiation and volatile organic compounds (VOCs). About 140 VOCs were detected in the ISS atmosphere including toxic benzene and phenol which impend the bone marrow (BM). State of the BM progenitor cells determines homeostasis of the bone tissues and blood forming system critical for the body adaptation to extreme environments. Our purpose was to assess effects of the 15-day exposure to VOCs on the progenitor cells isolated from Wistar rats’ femoral BM. The results showed a reduction of BM cellularity, inhibition of the proliferative, clonogenic and osteogenic activities and enhanced adipogenesis of stromal BM precursors. Hemopoietic colonies decreased in number. Expression of proresobtive genes increased on the background of the proinflammatory paracrine profile. VOCs affect the progenitor cells of both the stromal and hemopoietic BM differons.
Electrocardiography (ECG) is the most important method of clinical examination used broadly in all medical branches, aviation medicine included. The paper discusses the existing ECG standards and key requirements for examination of the civil aviation personnel.
The article presents results of studying whether a short-term stay in high mountains (3500 m) affects implementation of an arithmetic test. Participants were 6 normal females. We measured the body functional parameters (SpO₂, HR, CO₂, blood glucose) and assessed test results by the number of solved problems (Nsolved) and correctly solved problems (Ncorrect), and derived indicators of quality and success. A significant SpO₂ reduction and HR increase pointed to hypoxia. Values of Nsolved and Ncorrect decreased by 15–30 % and 19–65 %, respectively, and evidence for decline of the ability to solve problems and do it correctly. These results demonstrate the negative effect of high-altitude hypoxia on cognition, solving arithmetic problems, under time constraint specifically.
To identify the complex mechanisms of psychophysiological adaptation of a multinational crew (three women and three men) during prolonged isolation in a containment facility during the 120-day SIRIUS-19 experiment, a comprehensive analysis of the dynamics of neurophysiological (using electroencephalography) and neurosemantic (using neurosemantic psychodiagnostics) indicators was conducted. The obtained data were viewed as a manifestation of complex psychophysiological adaptation to extreme conditions of activity and habitat. Constant tension caused by the combined effects of environmental factors, emotional experiences of separation from the familiar social context, lack of privacy, and the intercultural nature of intra-group interactions among the international crew members was directly reflected in the dynamics of electroencephalographic indicators. Periods of relative stabilization of the functional state of the brain, observed primarily in the second half of isolation, indicated the development of new adaptive strategies and psychological defenses.
The paper contains analysis of the facilities of software products for calculation and management of radiation doses accumulated by civil flight personnel. The software products were distributed in 4 classes, i.e. elementary, mean complexity, professional and scientific. The first two classes can be used by passengers and crew members for approximate calculation of doses accumulated in air travels. Professional software is used by international air transport companies for systematic analysis, management and monitoring of crew doses. Scientific software is used to correlate dose values received in the near-Earth atmosphere with latitudes and longitudes, solar activity and flight parameters. In Russia, there are two available internet resources: Calculation of Radiation Doses Accumulated in Air Travels developed at the Institute of Space Researches and RUSCOSMICS© developed at the IZMIRAN Polar Geophysics Institute. Both resources allow calculation of ionizing radiation doses and dose rates at flight altitudes of 1 to 20 km in various geographic coordinates.
Further enhancement of the spacecrew medical system requires in-depth study of the pain phenomenon. The paper discusses our investigation of the head-down bed rest (HDT) as a model of the microgravity effect on human pain sensitivity. The investigation involved 11 human test-subjects at the age of 26 to 36 years. The integrated study of pain sensitivity was performed both with and without artificial gravity (rotation on a short-arm centrifuge, SAC) as a countermeasure. Methods to evaluate pain sensitivity and peripheral nervous system reactivity included the pressure pain threshold (PPT), heat pain threshold (HPT), and electroneuromyography (ENMG). The statistically significant increase of the pain threshold (p < 0.05) was caused, probably, by the shift of body liquids toward the cranium which is a typical effect of space and modeled microgravity. The results showed that concentration on subjective pain symptoms may lead sometimes to distortion of a diagnostic picture and underestimation of pathologies developing in missions or after return.
Within the framework of the Russian space experiment «Interactions», original methods for studying group interaction were developed: the computerized method «Personal Self-perception and attitudes» (PSPA) to analyze the emotional attitude of subjects to the social environment and the method «Homeostat» to evaluate the effectiveness of interaction between cosmonauts when performing joint operator’ activities. The article presents the results obtained during the cross-flights of the Soyuz and Crew Dragon spacecraft with the participation of 14 Russian crew members during the expeditions ISS 68–3. The main objectives of the experiment are as follows: to determine individual and group values and the degree of group identification (cohesion); to study changes in group cohesion and the effectiveness of interaction within space crews during space flight. The results made it possible to identify the most significant categories of values common to all subjects. The priority of these values is an important requirement for forming a cohesive team. The increase in the importance of the values of Benevolence and Hedonism for the cosmonauts who flew on Crew Dragon, revealed after the completion of the flight, was most likely due to a younger age and lack of space flight experience. For the first time, a study of the group interaction effectiveness methodology conducted on board the ISS using the Homeostat, made it possible to compare the dynamics of the solving joint tasks effectiveness with the level of cohesion assessed using the PSPA methodology.
Smooth muscle tissue, the basic component of the gastrointestinal organs, is the focus of interest in space gastroenterology. Integrins are receptors of cell adhesion which are expressed undoubtedly in all types of cells, including smooth myocytes. Integrins collaborate with the extracellular matrix and intercell signaling and participate directly in adaptation to microgravity. So far, this function of the smooth muscle has been overlooked by space gastroenterology. Purpose is to investigate expression of alpha integrins (α5) in smooth myocytes from the stomach and jejunum of 35 male Mongolian gerbils after the 12-day Foton-M3 mission. Morphological analysis of the gastrointestinal organs consisted of the immunohistochemical detection of α5 using rabbit mononuclear antibodies [EPR7854] ab150361, dilution 1:400 (Abcam, GB). Photography of microslides was made in 25 fields under the ZEISS Axio Imager.А2 microscope using objective 100×. Analysis was performed using ImageJ 1.51J. Result was expressed as a percentage of the total slide area. Our investigation revealed a decrease of α5 expression in muscle coats of the stomach and jejunum from the space-flown gerbils which suggests weakening of interactions between the cells and extracellular matrix, and a consequent reduction of myocytes contractility. Investigations into the fundamental role of integrins in gastrointestinal adaptation to microgravity can be of use to develop methods of mitigating the risk of hypotrophy in cosmonaut’s gastrointestinal muscles.
Lettuce seeds (Lactuca sativa L.) along with passive detectors were exposed at the high-altitude VOSTOK station in the Antarctic over a year. Dose equivalent was 5–7 mSv which exceeds the annual population exposure (1 mSv) recommended by the International Commission on Radiological Protection (ICRP). On return to the laboratory, the seeds were germinated and ana-telophase cytogenetic analysis of first mitosis of root meristem was carried out. The percentage of cells with chromosomal aberrations and the percentage of chromosomal bridges and fragments increased by a factor of 2.4. Also, mean number of dividing cells on the ana-telophase stage reduced by 24 %. After 34 month storage in laboratory condition seeds exposed in Antarctic were germinated once again. The length of sprouts decreased in comparison to the length of sprouts grown from storage control seeds; the length of root and hypocotyl reduced by 11 % and 12 %. The number of seeds germinated on the first day after steeping decreased by 25%. The subject of radiation-induced aging is discussed.
The series of surveys presents the results of ontogenetic and physiological investigations of Arabidopsis and rapid cycling Brassica rapa, wheat, peas and mizuna lettuce crops cultivated in a variety of plant growth chambers aboard space vehicles. This article concerns, specifically, the advances of Russian and international investigators in understanding of and how microgravity and other spaceflight factors influence growth, development and metabolism in Brassica rapa L. Space experiments led to the conclusion that microgravity does not affect Вrassica rapa growth and development. Moreover, microgravity does not impede formation of viable seeds and growth of next plant generations. Experiments with Вrassica rapa made an important input in space plant biology as they resulted in quantitative evaluation of the consequences of ethylene presence in the cabin air for plant growth and development, determination of changes in the composition of seed storage elements and secondary metabolites.
Delayed effects of proton irradiation (2 Gy, single exposure of the head) were studied in Wistar rats. Within the near-term period (1-2 months) we observed elevated excitation and impairment of the conditioned active avoidance response. Expected life span of the irradiated rats finally.
Near-infrared spectroscopy (NIRS) is gaining in popularity in biomedical investigations. This technique is based on registration of photons emitted by skin-mounted IR-source which after multiple scattering return to the photodetector located next to the source. IR-spectroscopy helps determine changes in concentrations of the oxygenated and de-oxygenated forms of hemoglobin in small vessels located in tissue area under study. These changes may appear because of vasomotor responses, elevated metabolic activity of the tissue, changes in tissue blood content due to the gravitational factor or other effects. Owing to its ease of use and compatibility with various methods of measuring other physiological indices, NIRS can be applied to investigate dynamics of the muscle and brain blood accumulation during different functional tests. The paper considers the basic principles of NIRS and provides examples of its use for monitoring blood flow in the brain during respiratory hypercapnia and in skeletal muscles in the course of intense aerobic work.
Ganglion cells of the retina were studied as potential biomarkers of chronic stress in pilots of highly maneuverable aircrafts. We examined 120 pilots at the age of 24 to 45 years with flight time total from 52 to 1600 hours. Their controls were 79 men at the age of 24 to 45 years who did not have dangerous professions. Stress level in pilots was evaluated by biochemical markers including ESR, total cholesterol, high density lipids (HDL) and low density lipids (LDL). Stress tolerance index was calculated from the leucogram formula developed by L.H. Garkavi. Optic coherent tomography (OCT) was performed using RTVue-100 (Optovue, USA). Protocols of scanning the optic nerve head (ONH), optic nerve disc (3D Disc), ganglion cells complex (GCC) applied and their results were compared with the biochemical markers of the chronic stress. The observed considerable global loss of the ganglion cells (GLV%) reproduces specifics of the central nervous system adaptation to the extreme factors of piloting. The loss did not correlate with the biochemical status and was depended significantly on the total flight hours, pilot’s «training».
