The problem of estimation of the organism adaptable opportunities under stressful influences

The human organism testing in conditions of modern scientific and technical progress constant stressful influences (industrial, social, psycho-emotional) was carried out for continuous adaptation to the environment: changing of the level of functioning of separate systems and a corresponding tension of regulatory mechanisms occurred. In the article, theoretical bases and methodology of studying the adaptable capacities of the organism are considered. The prenosological diagnostics was used for studying functional conditions on the verge of norm and pathology. The heart rate variability analysis was used based on mathematical model of functional conditions. Concrete technologies and results of evaluation of the adaptation capacities of the organism in space and aviation medicine are presented as well as in applied physiology.     

Study of the autonomic regulation of blood circulation during a long-term space flight

The five-year experience of experimentation in the autonomic regulation of blood circulation on board the International Space Station is presented. The heart rate variability (HRV) analysis was the basic methodical approach in these investigations. The probabilistic approach to the estimation of the risk of pathology under long-term spaceflight conditions based on HRV analysis is described. The individual type of autonomic regulation was taken into account in the analysis of the results of the investigations. The type of regulation inherent in every cosmonaut under the conditions of weightlessness has been shown to be retained during subsequent flights. New scientific data on the relationship between the character of the adaptive response of the body to spaceflight factors and the individual type of autonomic response have been obtained. Staying in weightlessness has been shown to be connected with the readjustment of regulatory systems and with transition to the zone of prenosological states. Adaptation responses in weightlessness are characterized by the increased tension of the regulatory systems and the preservation of sufficient functional reserves. The mobilization of additional resources is required after returning to earth, due to which the functional reserve of the mechanisms of regulation decreases. Cosmonauts with the vagotonic and normosympathotonic types of autonomic regulation appear to be the most resistant. The knowledge of the type of autonomic regulation allows us to judge the potential response of the cosmonaut to spaceflight factors. The likelihood estimates were calculated, and the risk categories were determined by the results of HRV analysis in the last months of the flight. Three pathology risk groups were identified. In conclusion, the theoretical and applied significance of the experiments was considered.     

Autonomic regulation and mental activity in children during school studies under unfavorable climatic conditions of the middle ob

Autonomic regulation and mental activity were studied in first-grade 7-year-old children under the Middle Ob climatic conditions. The study disclosed some features peculiar to adaptive alterations in children’s organisms and revealed both the degree of tension of the regulatory systems and changes in mental activity that described the “cost” of adaptation to school studies. Adaptation to school process depended on alteration of the regulatory mechanisms which had different expression at certain school periods and on changes in the relationship between sympathico-parasympathetic effects and the central regulation system, which were accompanied by different changes in mental activity. The adaptation mechanisms in most northern children were rather tense due to the unfavorable climatic effect on their organism.     

The reflection of compensation processes in the structure of the EEG spatial-temporal relationships in patients with disordered brain regulatory mechanisms]

Studies of intercentral relations of electrical activity in the cerebral cortex of the patients with hypophysis tumours under the conditions of chronic (before operation) and acute (after tumour ablation, early post-operative period) influence of the focus on the regulatory brain systems allowed to reveal definite changes of spectral-coherent EEG characteristics, reflecting the functional state of the cerebral adaptive-compensatory apparatus. It has been shown that reciprocal character of changes of various forms of the brain electrical activity and their intercentral relations is one of manifestations of development of the processes of cerebral compensation. At the same time, global fall of the EEG intercentral relations indicating the disintegration of the cerebral functional connections, reflects a loss of CNS compensatory mechanisms. The revealed EEG-characteristics at the present time are applied in Burdenko Institute of Neurosurgery for diagnostic-prognostic estimation of the brain functional state in patients during pre- and post-operative period.     

Adaptation in Sport: Present State, Problems, Prospects

The current state of the problem of adaptation in sport, its theoretical and practical aspects, and also prospects of its development are considered. Specific features of the mechanisms and regularities of adaptation to exercise were studied in athletes over 15 years. Four stages of adaptive rearrangements are proposed: physiological tension of the organism, adaptation, dysadaptation, and readaptation. Each stage is characterized by specific functional changes and regulatory and energy provision. The concept of a special functional system of adaptation in athletes is based theoretically and confirmed experimentally. Knowledge of the regularities of the development of this system allows us to efficiently and variously influence its links to accelerate adaptation to exercise and to increase training, i.e., to control the adaptation process.     

The evolution of flight in bats: narrowing the field of plausible hypotheses

The evolution of flapping flight in bats from an arboreal gliding ancestor appears on the surface to be a relatively simple transition. However, bat flight is a highly complex functional system from a morphological, physiological, and aerodynamic perspective, and the transition from a gliding precursor may involve functional discontinuities that represent evolutionary hurdles. In this review, I suggest a framework for a comprehensive treatment of the evolution of complex functional systems that emphasizes a mechanistic understanding of the initial state, the final state, and the proposed transitional states. In this case, bats represent the final state and extant mammalian gliders are used as a model for the initial state. To explore possible transitional states, I propose a set of criteria for evaluating hypotheses about the evolution of flight in vertebrates and suggest methods by which we can advance our understanding of the transition from gliding to flapping flight. Although it is impossible ever to know with certainty the sequence of events landing to flapping flight, the field of possibilities can be narrowed to those that maintain the functional continuity of the wing and result in improved aerodynamic performance across this transition. The fundamental differences between gliding and flapping flight should not necessarily be seen as evidence that this transition could not occur; rather, these differences point out compelling aspects of the aerodynamics of animal wings that require further investigation.     

Use of methods of spectral-correlation analysis for studying the temporal and spatial organization of tissues]

Tissues within the organism represent multidimensional systems organized in time and space and having statistical dispersion in each parameter. Changes in its state may have a character of a monotonous trend and be periodical (the matter of chronobiology). The methods for detection of latent periodicities, developed in chronobiology, are applied for estimation of not only temporary but also spacial characteristics of the object. One of such methods is the calculation of the power spectrum of the autocorrelative function. Examples of its application are given.     

Emphasis of biological research for space radiation]

The paper summarized issues, current status and the recent topics in biological research of space radiation. Researches to estimate a risk associated with space radiation exposure during a long-term manned space flight, such as in the International Space Station, is emphasized because of the large uncertainty of biological effects and a complexity of the radiation environment in space. The Issues addressed are; 1) biological effects and end points in low dose radiation, 2) biological effects under low dose rate and long-term radiation exposure, 3) modification of biological responses to radiation under space environments, 4) various aspects of biological end points vs. cellular and molecular mechanisms, 5) estimation of human risk associated with radiation exposure in space flight, 6) regulations for radiation exposure limits for space workers. The paper also summarized and introduced recent progress in space related radiation researches with various biological systems.     

Some approaches to prophylactic measures in a martian expedition

Physiological and methodological principles of the organization of physical training (PT) and its computerization during a space flight to Mars under the conditions of autonomous activity of the crew, including interaction with onboard medical systems, self-maintenance of health, preventive measures, diagnostic examinations, and, if necessary, treatment, are discussed. The conditions of unusually long-term autonomous space flights make the ground-based monitoring of the state of health of crew members substantially more difficult, which calls for computerization of the control over the crew members’ health, including prophylactic measures. The situation is further complicated because it is impossible to receive the necessary information from, and transmit it to, the spacecraft in a real-time mode or to quickly return the crew to Earth in case of an emergency. Under these conditions, physical prevention should be based on an onboard automated expert system ensuring the control over the activities of all crew members aimed at optimizing their psychophysical state. The problems of the control of training, including the use of an onboard automated expert system, are discussed.     

Plasma hormone levels in human subject during stress loads in microgravity and at readaptation to Earth's gravity

In great part of the investigations of endocrine system functions in astronauts during space flights the plasma levels of hormones and metabolites were determined only in resting conditions, usually from one blood sample collection. Such levels reflected the psychical and physical state and new hormonal homeostasis of organism at the time of blood collection, however, the functional capacity of neuroendocrine system to respond to various stress stimuli during space flight remained unknown. The aim of present investigations was to study dynamic changes of hormone levels during the stress and metabolic loads (insulin induced hypoglycemia, physical exercise and oral glucose tolerance test) at the exposure of human subject to microgravity on the space station MIR. The responses of sympatico-adrenomedullary system to these stress and workloads were presented by Kvetnansky et al.     

Mechanism of antioxidant protection of an organism from oxidative stress

The analysis of the literature and authors' data concerning the mechanism of antioxidant protection of the organism under conditions of "oxygen stress" is submitted. Possible mechanisms of initiation of free radical reactions with participation of oxygen and the role of hydroxyl radicals, being one of the basic factors, determining toxic action of oxygen, are considered. The methods of estimation of antiradical activity of biologically active compounds are characterized.     

The water-salt balance and renal function in space flights and in model experiments

Study of a condition of mineral and water-electrolyte metabolism, function of kidneys, and their hormonal regulation during model experiments (hypokinesia, bed rest, immersion etc.), and also in space flights and in readaptation period, has shown a major role of water-electrolyte homeostasis during general adaptation of humans and animals to new conditions of life and to conditions of weightlessness in particular. The change in regulation of volumes of fluid milieu in an initial period of weightlessness was shown to be the consequence of redistribution of blood and hemodynamics of the shifts resulting in change of production of volume-regulation hormones, formation of negative water balance, and redistribution of fluid in the organism among various fluid compartments. At later stages of flight or long-term hypokinesia, a change of water-electrolyte homeostasis occurs with a decrease in the kidneys excretion of sodium, and diuresis, but with an increased excretion of calcium and production of ADH and RAAS hormones. Following returning to earth gravitation, the majority of astronauts have adaptive reactions, compensating for the loss extracellular fluid and mineral substances and formation of "earth" water-electrolyte homeostasis. For estimation of water-electrolyte homeostasis and the functions of kidneys in astronauts, various functional loading tests have been developed. The developed system of preventive maintenance is successfully used for abolition of adverse changes at various stages of space flight and in readaptation period.     

Divergent and convergent mechanisms of the integrative activity of the mammalian brain

Convergent intercellular synaptic interaction is actualized, mainly, by two neurotransmitter systems: glutamate- and GABA-ergic (excitatory and inhibitory postsynaptic potentials, respectively). Fast and slow postsynaptic receptors of glutamate- and GABA-ergic synapses are described. All other brain systems are divergent neuromodulators. Modulators are released into the intercellular space and simultaneously interact with a large population of neurons. A hypothesis of divergent modulatory integration is described: the divergently functioning neuromodulators actualize stable functional states of the brain via appropriate long-term modification-inducing receptors. These stable states are a biochemical basis of the motivational and emotional states. Mechanisms of the secondary nuclear signaling triggered by the long-term modification-inducing receptors consolidate the stable states. The hypothesis of divergent modulatory integration is substantiated in the paper on the basis of the evidence obtained by the author and his collaborates. The haloperidol catalepsy and pentile-netetrazole kindling are considered as a behavioral model of the divergent modulatory integration. The experimental data suggest that divergently functioning neuromodulators actualize and consolidate general motivational and emotional states via the appropriate long-term modification-inducing receptors. The consolidation is structurally-specific. The motivational and emotional states concomitant of learning and memory are a specific variation of the general motivational and emotional state depending on the learning situation.     

Physiological basis of differences in the body tolerance to submaximal physical load to capacity in healthy young individuals

A complex approach to studying the physiological basis of the individual and typological features of functional states and tolerance of physical load in healthy young individuals using superslow physiological processes (SSPP) was elaborated. Statistically significant differences were found in the values of central hemodynamics, physicochemical homeostasis, the level of oxygen consumption by the tissues and general nonspecific adaptation reactions of the body. These reactions correlated with differences in the integral values of the wakefulness level, as judged by the SSPP data, in healthy individuals tolerant of physical fatigue and quickly fatigued individuals at rest and after a two-step individually submaximal physical stress to capacity. The possibilities of the use of this approach to substantiate the physiological significance of SSPP in the differential diagnosis of the optimal level of wakefulness, the state of physical tension, the state of fatigue, and asthenic states of a different degree of severity in healthy individuals with regulatory and homeostatic control inherent in these states were revealed.     

Antioxidative system of the organism and thermo-initiated chemiluminescence method for quantitative evaluation of its state

Evolutionary stages of the development of an antioxidative system within the human organism are shortly considered and the technique for measurement of blood plasma parameters, which reflect the state of antioxidative homeostasis, based on thermo-initiated chemiluminescence of azo compounds in the presence of luminol, is described. Parameters suitable for quantitative estimation of the degree of oxidative stress and the efficiency control of causal and adjuvant antioxidative therapy in the course of primary and secondary prevention of civilization illnesses are recommended. A special attention is focused on sports activities as the most accessible and effective way of achieving the specified preventive purposes.     

Behavioral and functional vestibular disorders after space flight: I. Mammals

The review presents data on functional disorders in mammals caused by changes in the vestibular system after space flight. These data show that the mammalian vestibular system responds to weightlessness dissimilarly at different ontogenetic stages. During the embryonic period, orbital space flight conditions have a little effect on the developing vestibular system and even promote normal fetal development. During the early postnatal period, when optimal sensorymotor tactics arise, long-term exposure to space flight conditions leads to the development of novel, “extraterrestrial”, sensory-motor programs that may fixate in CNS for life. In adult individuals, substantial vestibular changes and disorders may occur immediately after landing depending on the weightlessness duration. An adult organism has to solve two concurrent and mutually conflicting problems: to adapt to weightlessness and not to adapt to it in order to facilitate readaptation after return. Thus, individuals have to counteract weightlessness to retain a maximum of their pre-flight health status. The means of such a counteraction have to be adjusted according to the weightlessness duration. It is noteworthy, however, that not all functional changes occurring in adult individuals under weightlessness can be adequately accounted for. Some of them can assume a chronic or even pathological character. The review raises for the first time the question of necessity to include into the scope of studies the effect of weightlessness on a senile (senescent) organism and its vestibular system. We believe that development of space gerontology as a special branch of space biology and medicine is undoubtedly of interest and may become practically important in the future in view of the ever-growing age of space explorers.     

Role of interaction of metabolism pathways of formaldehyde and nitric oxide in the mechanism of their toxic effect. 3. Main metabolism sites of formaldehyde and nitric oxide mediating their effect

Data are presented concerning the basic metabolism sites, the reaction paths crossing in them and regulatory and toxical effect of formaldehyde and nitric oxide being mediated through them. In particular, they include: glutathione-formaldehyde-dependent dehydrogenase path of S-nitrosoglutathione reduction, semi-carbaside-sensitive amino-oxidase (SSAO) and NO-synthase systems; transformation of thioproline and metallothioneines, including nitrosation reactions. Possibilities of hexamethylenetetramine synthesis in the organism as well as its metabolism in conditions of formaldehyde hyperproduction and nitrosative stress are discussed. The role of metabolism sites, common for formaldehyde and nitrogen oxide, in the mechanisms of toxical effect of these compounds and development of pathologic states is considered.