Biomedical subjects

A I Grigoriev

Publications and source records attributed to A I Grigoriev.

At least 19 recordsLinked to original sources

PubMed2004

Effect of space flight and head-down bedrest on neuroendocrine response to metabolic stress in physically trained subjects.

The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the 5th day of SF, on the 2nd and 16th days after the landing in the first Slovak astronaut, and before and on the 5th day of prolonged subsequent head-down (-6 degrees) bed rest (BR) in 15 military aircraft pilots. Blood samples during the test were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Insulin hypoglycemia was induced by i.v. administration of 0.1 IU/kg BW insulin (Actrapid HM) in bolus. Insulin administration led to a comparable hypoglycemia in pre-flight, in-flight conditions and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in pre-flight studies. However, an evidently reduced EPI response was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, insulin-induced hypoglycemia activates the adrenomedullary system to less extent than at conditions of the Earth gravitation. Post-flight changes in EPI and NE levels did not significantly differ from those of pre-flight since SF was relatively short (8 days) and the readaptation to Earth gravitation was fast. It seems, that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of deconditioning effect of 5 days bed rest on stress response. Thus, the data indicate that catecholamine responses to ITT are reduced after exposure to real as well as simulated microgravity.

Adult↗

PubMed2004

Investigation of erythrocyte shape, plasma membrane fluidity and conformation of haemoglobin haemoporphyrin under the influence of long-term space flight.

The investigation of long-term space flight (SF) effect on the blood cells function is of great importance for modern space biology and medicine. We established that the number of discocytes decreased in the period of early rehabilitation after long-term SF. After SF plasma membrane fluidity and phospholipid content decreased and cholesterol content increased. After SF the amount of haemoglobin decreased and the parameters characterizing haemoglobin haemoporyphyrin (HH) conformation changed. We suppose that erythrocyte shape, membrane fluidity and HH conformation are among factors affecting oxygen transfer during and after space flight.

Cholesterol↗

PubMed2003

The response of endocrine system to stress loads during space flight in human subject.

The responses of endocrine system to the exposure to stress-work load and hormonal changes during oral glucose tolerance tests were studied in the Slovak astronaut before (three weeks before flight), during (on the 4th and the 6th days of space flight), and after space flight (1-3 days and 15-17 days after space flight) on board of space station MIR. Blood samples during the tests were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Preflight workload produced an increase of plasma norepinephrine and a moderate elevation of epinephrine levels. Plasma levels of insulin, growth hormone, prolactin and cortisol were not markedly changed immediately or 10 min after the end of work load. The higher increases of plasma growth hormone, prolactin and catecholamine levels were noted after workload during space flight as compared to preflight response. The higher plasma glucose and insulin levels were noted during the oral glucose tolerance test in space flight and also in the post flight period. Plasma epinephrine levels were slightly decreasing during glucose tolerance test; however, plasma norepinephrine levels were not changed. The similar patterns of catecholamine levels during glucose tolerance test were found when compared the preflight, in-flight and post flight values. These data demonstrate the changes of the dynamic responses of endocrine system to stress-work and metabolic loads during space flight in human subject.

Adaptation, Physiological↗

PubMed2002

Goals of biomedical support of a mission to Mars and possible approaches to achieving them.

The main medical and biological problems associated with a piloted mission to Mars are discussed. Prerequisites for the mission are described, based on our experience with biomedical support of prolonged piloted missions. The most important factors are developing countermeasures against the prolonged effects of microgravity and hypogravity; solving a complex of psychological problems; developing methods to protect against cosmic radiation; and creating effective and reliable life support systems. Some aspects of the likely risks involved in such a mission are also reviewed.

Aerospace Medicine↗

PubMed2002

Responses of sympathoadrenal and renin angiotensin systems to stress stimuli in humans during real and simulated microgravity.

Changes of plasma hormone levels were investigated in human subjects after exposure to physical exercise (WL) and insulin induced hypoglycemia (ITT) during space flight or after head down bed rest (HDBR). Exaggerated responses of plasma epinephrine (EPI), norepinephrine (NE) and aldosterone (ALD) were observed after WL during space flight as compared to preflight response. Hypoglycemia during space flight induced attenuated responses of EPI, NE and augmented response of ALD. Exposure to WL during HDBR was followed by significantly exaggerated responses of plasma EPI, NE, ALD, PRA and cortisol. In HDBR the responses of plasma EPI, NE and cortisol were reduced and PRA response was exaggerated during ITT. These data indicate that hormonal responses to ITT and WL are similar at real and simulated microgravity.

Comparative Study↗

PubMed2001

Effect of microgravity on plasma catecholamine responses to stressors during space flight.

The effect of microgravity on the sympathicoadrenal system (SAS) activity in humans and animals has not yet been clarified. Our previous studies suggested that the SAS activity, evaluated by circulating and/or urinary catecholamine (CA) levels in astronauts during space flights, was found to be rather unchanged. However, CA levels were measured in astronauts only at rest conditions. The aim of the present study was to investigate effect of microgravity during space flight and post-flight readaptation on responsiveness of the SAS to somatic and psychic stressors evaluated by levels of catecholamines and their metabolite in the blood of the Slovak cosmonaut during his stay on board the space station Mir.

Adaptation, Physiological↗

PubMed2001

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.

Adaptation, Physiological↗

PubMed2000

Orthostatic tolerance and hormonal changes in women during 120 days of head-down bed rest.

BACKGROUND: Women will be included as mission specialists in the upcoming International Space Station program. This paper describes the changes in volume-regulating hormones and determines the degree of degradation in orthostatic tolerance in a group of women after 120 d of bed rest. The aim of this study was to test a countermeasure program to be used by women during long-duration spaceflights. METHODS: For 120 d of -6 degrees head-down bed rest (HDBR), eight healthy women were assigned either to a no-countermeasure (No-CM, n = 4), or to a countermeasure (CM, n = 4) group. In the countermeasure group, exercise began after 2 wk, pharmacological agents were given during the 1st and 3rd mo, and the "Centaur" suit was worn on the last day of bed rest and during the day time for several days after bed rest. Diet supplements were taken during the 1st and 4th mo of HDBR. Tilt tests were run before and after HDBR. RESULTS: After the HDBR, none of the CM subjects, had pre-syncopal or syncopal symptoms during tilt tests: BP was well maintained in the CM group, while heart rate and BP changed in the No-CM group. In plasma, atrial natriuretic peptide (ANP) increased in both groups and remained high throughout HDBR, while aldosterone increased and remained elevated in the No-CM group. Natriuresis was decreased during HDBR. CONCLUSION: The CM protocols used during this study were efficient and prevented orthostatic intolerance for the four CM subjects. It would be necessary to obtain more data regarding this set of CM protocols on female subjects to lead to statistical and formal conclusions.

Adult↗

PubMed1999

Endocrine status and LBNP-induced hormone changes during a 438-day spaceflight: a case study.

We investigated basal levels and lower body negative pressure (LBNP)-induced changes of volume regulating (PRA, aldosterone, AVP, ANP99-126) and other stress-sensitive hormones (catecholamines, cortisol, ACTH) in venous plasma from one cosmonaut before (-45 d), during (3, 170, 287, 430 d) and after (+4, +90 d) a record-breaking long-term (438 d) spaceflight. Blood was taken at the beginning and immediately after ending LBNP (-15/-30/-35 mm Hg for 15/15/10 min, respectively) preflight supine, inflight, and postflight supine. PRA, aldosterone, and vasopressin levels stayed within normal boundaries during the entire flight and after landing. Catecholamines exceeded reference limits (epinephrine > 140 pg x ml(-1), norepinephrine >1000 pg x ml(-1) 5 and 9 mo inflight, and 4 d postflight. ANP and cGMP were lower inflight (p<0.04) than pre- or postflight. Cortisol and ACTH were not consistently altered. LBNP-induced hormonal changes were not different (p>0.05) in microgravity and 1-G. Based on data from one cosmonaut, we conclude that long-term spaceflight up to 430 d duration appeared to lower plasma ANP and cGMP during flight and occasionally elevate catecholamine levels, without significantly altering LBNP-induced relative hormone changes as compared with those observed on the ground.

Adaptation, Physiological↗

PubMed1998

Life support systems and optimal isotope composition in cosmonaut habitats for long-term missions.

Differences in the isotope content of the biogenous chemicals of cosmonaut habitats are given a theoretical consideration. Rationale is given to the hypothesis according to which the biochemical and biophysical processes in plants. animals, and humans must be impacted by the isotopes of all the biogenous chemicals in cosmonaut habitats. Organisms were found to persistently make preference of lighter fractions of stable isotopes from the biogenous chemicals. In most of the compounds the light fraction of stable isotopes constitutes the greater portion by mass. However, the optimal isotope composition of biogenous chemicals is still unknown and necessitates biochemical, toxicological, biological and other kinds of research. The functions of a life support system should also include production and maintenance of an optimal isotope composition for habitats, i.e. water, oxygen, food stuffs in order to improve metabolism in and performance of cosmonauts.

Ecological Systems, Closed↗

PubMed1998

Manned interplanetary missions: prospective medical problems.

The present review aimed to suggest approaches to prospective medical problems related to the health maintenance of space crews during future manned interplanetary, particularly Martian, missions up to 2-3 years with a possible stay on a planet with gravity different from that on Earth. The approaches are based on knowledge so far obtained from our analysis of the medical support of long-term orbital flights up to one year, as well as on the consideration of specific conditions of interplanetary missions. These specific conditions include not only long-term exposure to microgravity, but also a prolonged stay of unpredictable duration (2-3 years) on board a spacecraft or on a planet without direct contact with Earth, and living in a team with a risk of psychological incompatibility and the impossibility of an urgent return to Earth. These conditions necessitate a highly trained medical person in the crew, diagnostic tools and equipment, psychophysiological support, countermeasures, as well as the means for urgent, including surgical, treatment on board a spacecraft or on a planet. In this review, the discussion was focused on the following predictable medical problems during an interplanetary mission; 1) unfavorable effects of prolonged exposure to microgravity, 2) specific problems related to Martian missions, 3) medical monitoring, 4) countermeasures, 5) psychophysiological support and 6) the medical care system.

Adaptation, Physiological↗

PubMed1998

[Clinical and physiological evaluation of bone changes among astronauts after long-term space flights].

Results of the joint Russian/US studies of the effect of microgravity on bone tissues in 18 cosmonauts on return from 4.5- to 14.5-month long missions are presented. Dual-energy x-ray gamma-absorbtiometry (QDR-1000 W, Hologic, USA) was used to measure bone mineral density (BMD, g/cm2) and mineral content (BMC, g) in the whole body, the scalp including cervical vertebra, arms, ribs, sternal and lumbar regions of the spinal column, pelvis and legs. A clearly defined dependence of topography of changes upon the position of a skeletal segment in the gravity vector was established. The greatest BMD losses have been observed in the skeleton of the lower body, i.e. in pelvic bones (-11.99 +/- 1.22%), lumbar vertebra (-5.63 +/- 0.817%), and in proximal femur, particularly in the femoral neck (-8.17 +/- 1.24%). Bones of the upper skeleton were either unchanged (insignificant) or showed a positive trend. Overall changes in bone mass of the whole skeleton of male cosmonauts during the period of about 6 months on mission made up -1.41 +/- 0.406% and suggest the mean balance of calcium over flight equal to -227 +/- 62.8 mg/day. Reasoning is given to qualify these states of cosmonauts' bone tissues as local osteopenia. On the literature and results of authors' clinical evidence, discussed is availability of the densitometric data for predicting risk of trauma. A biological nature of the changes under observation is hypothesized.

Astronauts↗

PubMed1998

Specific glucocorticoid binding at different levels of human motor activity.

We studied the number of glucocorticoid receptors and dissociation constant in isolated human lymphocytes as well as blood concentrations of hormones produced by the hypothalamic-hypophyseal-adrenocortical system in three experimental series: at normal (17 subjects), decreased (10 subjects, a 360-d head-down bed rest) and increased (8 subjects, physical exercise on bicycle ergometer) levels of motor activity. In the first series we found that the number of glucocorticoid receptors and dissociation constant did not depend on the season, on the age of subjects nor on cortisol concentrations in blood. In the second series we observed the following: at the end of the first month of bed rest the number of glucocorticoid receptors and receptor affinity significantly increased; at the beginning of the third month of bed rest specific glucocorticoid binding significantly decreased and circadian rhythms of adrenocorticotropin and cortisol in blood varied markedly; at the end of the sixth month of bed rest the number of glucocorticoid receptors returned to prebed rest levels and dissociation constant decreased. In the third series physical exercises that induced an activation of the hypothalamic-hypophyseal-adrenocortical system (maximal physical exercises and prolonged submaximal exercises at 70% of maximal oxygen uptake) led to a significant increase in the number of glucocorticoid receptors without changes of dissociation constant. These results indicate that both a decrease and an increase of human motor activity resulted in significant changes of specific glucocorticoid binding which were not influenced by changes of circulating hormone concentrations in blood but by some other factors affected by physical activity.

Adaptation, Physiological↗

PubMed1997

Biochemical and morphological stress-reactions in humans and animals in microgravity.

This article is a literary review focused on the problem of the stress-effect of microgravity. Based on the all-round analysis of data from manned missions and space experiments with rats it is concluded that microgravity as a permanent factor of space flight does not produce an intense chronic stress in either humans or animals. On the other hand, microgravity is responsible for deconditioning of a number of vital systems and of the organism as a whole. On return to Earth, the deconditioned bodies of humans and animals exaggerate the usual terrestrial loads due to gravity forces and respond by acute gravitational stress.

Adaptation, Physiological↗

PubMed1997

Immune organs and haemopoietic system under modelling of the mission factors.

Literary and experimental data on the character of changes in immune organs and lymphoid tissue of respiratory system and digestive system in laboratory animals during the mission factors model area given. Inhibition of reproductive function in bone marrow, thymus and spleen under irradiation of gamma-rays and accelerated carbon ions, tensity of immune response in the lymphoid structures of larynx, trachea and bronchi under the influence of acetaldehyde vapors and decrease of lymphoid tissue square on histological series in spleen and small intestine with an increase of concentration of microbial bodies in the drinking water were estimated.

Acetaldehyde↗

PubMed1997

Education programme on aerospace and environmental medicine for medical faculty of Lomonosov Moscow State University.

The problems and approaches to organisation of the education process in the field of aerospace and environmental medicine for medical students are discussed. Original education developed on the basis of Russian experience in space biology and physiology, environmental medicine, aerospace medicine and medical support during spaceflight. The main goals of these programs are to acquaint students with: interaction of living organisms with natural and artificial surroundings, including space flight conditions; the physiological reactions on extreme environmental factors; basic mechanisms of human adaptation to space flight and particularly to microgravity; the current research in space medicine and new telecommunication technologies. All programs are formed in accordance with contemporary progress in life sciences and revealed a result of the interdisciplinary approach to education process.

Aerospace Medicine↗

PubMed1997

Medical monitoring in long-term space missions.

The following principles, derived from the experience of medical support during past spaceflights, can provide a basis for a system of health monitoring and diagnosis during long-term and interplanetary missions: a system of preflight medical screening; medical screening on a systemic basis, which may include purposeful diagnosis in subsystems following the method of hierarchic structure; use of an individual approach; correction of the medical program with respect to the space crew status; assessment of the interrelations of the entire complex of parameters; utilization of the methods of correlation, classification and identification to elicit interrelations between different functions; evaluation of shifts in body functions and their adequacy to ambient conditions; continuity of medical examinations during all pre-flight stages, during flight and after completion of flight; analysis of information and anamnestic data by means of data bases; confidentiality of medical conclusions. Discussed are a classification of unfavorable microgravity-related syndromes, possible impairments due to abnormal situations, and some approaches to the prediction of the risk of various diseases, in relation to the construction of a conceptual diagnostic model for interplanetary missions. In the interest of medical monitoring special significance is attributed to the knowledge of individual norms for each crew member and of his unique peculiarities. Such data can be compiled by means of statistical analysis (single and multidimensional analysis) of the results of medical examinations and of observations during selection, training and tests. Selection of necessary physiological parameters, functional loads and data processing techniques which can be used in combination with other data sources for inflight diagnosis should be based on the following principles: the use of informative, non-invasively registered parameters and functional tests to reveal adverse states or most probable diseases; the possibility to assess the dynamics of physiological parameters and the status of the regulatory systems, and to predict possible developments in the body; the possibility to check the efficiency of countermeasures; the possibility to differentiate a physiological state adapted to the current environment from a pathological state; the possibility to differentiate between specific and non-specific reactions; the possibility to differentiate defensive, adaptive or compensatory phenomena from pathological manifestations. This paper describes the application of single- and multidimensional, statistical methods to process diagnostic information, to reduce the vector dimension of the chosen parameters, and to classify and identify individual and crew physiological standards providing the ability to assign an individual to a suitable team. Thus it will be possible to acquire comprehensive and statistically reliable information in compact format, and thus to perform a more incisive analysis and diagnosis of various states by comparing them with the baseline preflight data. These theoretical considerations constitute the basis for a conceptual model for medical diagnosis in long-term orbital and interplanetary missions. The paper contains a section dealing with the practical aspects of medical monitoring and diagnostic examinations during Mir missions. The program of medical monitoring for long-term Mir missions incorporates on-line monitoring during intravehicular and extravehicular activities, routine daily examinations, periodic extensive medical examinations accomplished on schedule or an indication. The Mir program includes cardiovascular investigations at rest and during functional loading, testing of the cosmonaut muscular systems, validation of the standard training protocols, occasional blood and urine analysis, incl. serum immunoglobulins, and blood cell counts. (ABSTRACT TRUNCATED)

Animals↗

PubMed1997

[The theory and practice of medical support of long-term space missions].

The present paper gives the basis for a conceptual model of diagnostics in long-duration, including interplanetary, manned missions, and describes the strategy of medical support of the MIR crews. Classification of the microgravity-induced syndromes (states) and health problems due to e possible technical failures are cited as constituents of the conceptual model of medical support system for interplanetary missions. In the light he above, principles of diagnostics during interplanetary missions are discussed and applicability of some statistical, including multidimensional methods to the diagnostic data analysis is considered.

Aerospace Medicine↗