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Biomedical subjects

B V Morukov

Publications and source records attributed to B V Morukov.

At least 19 recordsLinked to original sources
PubMed2006

[The endogenous regulation of the cytokine disbalance in humans subjected to simulated spaceflight environment].

Confinement is one of the stress-inducing factors which humans face in such terrestrial environments as those in polar winter-over expeditions, submarines, and is inevitable in space flights. Confinement regime (CR) itself includes a number of stress factors (e.g. psychological compatibility between crew members, microbiological contamination etc.), which have been shown to alter human immunity. Two groups of total seven subjects spent 110 days in closed-habitat chamber as part of SFINCSS (Stimulation of Flight of International Crew on Space Station) study. Distribution of T-cell subsets, NK-, B-cells, and monocytes in whole blood was assessed. Secretion of type I (IL-2, IFN-gamma, TNF-beta) and type II (IL-4, IL-10) cytokines in the LPS/PHA activated whole blood cell culture was assessed. Significant alterations in type I / type II cytokine equilibrium were observed during and after confinement. The data show that stress factors associated with confinement may lead to disbalance between cell-mediated and humoral immune reactions.

Cytokines↗
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

[Prophylaxis of the unfavorable shifts in mineral turnover in bones during extended exposure to the conditions reproducing the physiological effects of microgravity].

Effectiveness of the countermeasures and methods for mitigation of the unfavorable effects of microgravity on mineral turnover and properties of bones was evaluated in simulation experiments with animals (penal immobilization, suspension) and with participation of human subjects (37 to 120-d head-down bed rest). The experiments with rats were aimed at testing pharmaceutical preparations (bisphosphonates), determining doses, plan and way of administration. Preparations of this group differ considerably in their action on osteogenesis, mostly because of specifics of the chemical structure. Nonetheless, optimization of the course of treatment masked significantly side effects without detriment to the preventive action. Head-down bed rest was used to test effectiveness of physical exercises (PE) as a main countermeasure against the microgravity impacts. Both standard and experimental PE regimens were tested. Several groups of test-subjects combined PE with consumption of xidifon (a bisphosphonate). In addition, mineral supplements (potassium and calcium) were used. The PE + xidifon combination and regulation of mineral intake with foods was found to reduce calcium losses during 370-d bed rest and prevent a material degradation of strength of bone samples, and essentially rehabilitate shifts in the hormonal regulation of calcium turnover and calciuretic function of the kidney.

Animals↗
PubMed2003

[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.

Astronauts↗
PubMed2003

[Effects of ibandronate on the osteopenia process in tail-suspended rats].

Histological and histomorphometric effects of ibandronate on the metaphyseal spongiosis in tibia were studied in tail-suspended rats and their controls in a 30-d experiment. Ten- to twenty-day course of ibandronate at a dose of 6 micrograms/kg of the body mass per diem altered the architectonics of metaphyseal spongiosis and increased materially the total spongiosis volume no matter whether those were suspended rats or controls. Spongiosis growth was a result of a sharp deterioration of resorption and spongy bone remodelling due to ibandronate. The substance also exhibited a strong durable action inferring that it might be used for prevention of osteopenia for lack of loading on the musculoskeletal system.

Adrenal Glands↗
PubMed2001

The risk of renal stone formation during and after long duration space flight.

BACKGROUND: The formation of a renal stone during space flight may have serious negative effects on the health of the crewmember and the success of the mission. Urinary biochemical factors and the influence of dietary factors associated with renal stone development were assessed during long duration Mir Space Station missions. METHODS: Twenty-four-hour urine samples were collected prior to, during and following long duration space flight. The relative urinary supersaturation of calcium oxalate, calcium phosphate (brushite), sodium urate, struvite and uric acid were determined. RESULTS: Changes in the urinary biochemistry of crewmembers during long duration spaceflight demonstrated increases in the supersaturation of the stone-forming salts. In-flight hypercalciuria was evident in a number of individual crewmembers and 24-hour dietary fluid intake and urine volume were significantly lower. During flight, there was a significant increase in brushite supersaturation. CONCLUSIONS: These data suggest acute effects of space flight and postflight changes in the urinary biochemistry favoring increased crystallization in the urine. The effects of dietary intake, especially fluid intake, may have a significant impact on the potential for renal stone formation. Efforts are now underway to assess the efficacy of a countermeasure to mitigate the increased risk.

Adult↗
PubMed1999

Calcium metabolism before, during, and after a 3-mo spaceflight: kinetic and biochemical changes.

The loss of bone during spaceflight is considered a physiological obstacle for the exploration of other planets. This report of calcium metabolism before, during, and after long-duration spaceflight extends results from Skylab missions in the 1970s. Biochemical and endocrine indexes of calcium and bone metabolism were measured together with calcium absorption, excretion, and bone turnover using stable isotopes. Studies were conducted before, during, and after flight in three male subjects. Subjects varied in physical activity, yet all lost weight during flight. During flight, calcium intake and absorption decreased up to 50%, urinary calcium excretion increased up to 50%, and bone resorption (determined by kinetics or bone markers) increased by over 50%. Osteocalcin and bone-specific alkaline phosphatase, markers of bone formation, increased after flight. Subjects lost approximately 250 mg bone calcium per day during flight and regained bone calcium at a slower rate of approximately 100 mg/day for up to 3 mo after landing. Further studies are required to determine the time course of changes in calcium homeostasis during flight to develop and assess countermeasures against flight-induced bone loss.

Calcium↗
PubMed1999

[Calcium metabolism characteristics in microgravity].

The results of research of calcium exchange parameters at cosmonauts taken part in long space flights (SF) onboard of orbital stations "SALUT" and "MIR" within 1978-1998 were generalized. The analysis of data received during observation of 44 cosmonauts (18 of them have taken part in long SF twice) was done. The observation was carried out before and after SF by duration 30-438 days. The content of a total calcium in blood serum was increased basically by the increase of its ionized fraction after flights of moderate (3-6 months) and large duration (6-14 months) along with the significant increase of PTH and decrease of calcitonin levels. The content of osteocalcin after SF was increased. Three cosmonauts participated in research of calcium kinetics using stable isotopes before, in time and after a 115-day SF. Reduction of intestinal absorption, excretion through a gastrointestinal tract, and increase of calcium excretion with urine were marked in time of SF. In early postflight period a level of intestinal absorption, on the average, was much lower than in SF, and the calcium removal through intestine was increased. Both renal and intestinal excretion of calcium were not normalized in 3.5-4.5 months after end of SF. Increase of resorbtive processes in bone tissues which induced negative bone balance during flight was observed in all test subjects, proceeding from estimations of speed of the basic calcium flows made on the basis of mathematical modeling. The conclusion about decrease in speed of bone tissue remodeling and strengthening of its resorption proves to be true by data of research of biochemical and endocrine markers.

Bone and Bones↗
PubMed1998

Effects of the 120 days of head-down bed rest on cytokine secretion and its in vitro modulation by glucocorticoids.

Antiorthostatic hypokinesia or head-down bed rest (HDBR), is a ground-based model system used to simulate some of the physioloical responses observed during space flight. Several studies involving humans and animals have demonstrated the effects of HDBR on different physioloical systems. HDBR produced a large thoracic fluid shift similar to that reported for space flight. Exposure to the combination of -6 degrees HDBR, emotional stress, and hypergravity led to an elevation of plasma histamine and serotinin and a dramatic decrease in the concentration of prostaglandins E, F2-alpha, and erthropoietin. These responses indicated the HDBR produces significant alterations in the neuroendocrine regulatory pathways. The proliferative response of immune cells in response to activators was significantly enhanced in antiorthostatically suspended mice; plasma corticosterone also was higher but splenic natural killer cell cytotoxicity remained unchanged after suspension. Bone-resporbing activity of supernatatants increased in mitogen-stimulated PBMC cultures of subjects exposed to -5 degrees HDBR for 370 days of HDBR. Proliferative activity of PBMCs had declined at the end of a 320-day HDBR and during the initial days of recovery, but the numbers of active rosette-forming T cells increased. These and other results suggest that most stress-induced immune changes are neuroendocrine modulated, and that corticosteroids play a significant role in this modulation. It is expected that HDBR-induced immune changes could result from similar mechanisms. In this study, we investigated the effect of 120 days of HDBR on Type-1 vs. Type-2 cytokine equilibrium in mitogen-activated PBMC culture, and how these reactions may correlate with changes in the neuroendocrine status.

Adult↗
PubMed1997

[Dynamics of the hematological shifts in females during antiorthostatic hypokinesia].

The purpose of the present study was to perform comprehensive hematological investigations of females in a 120-day head-down (-5 degrees) bed rest and in the period of recovery. Morphometric, cytochemical parameters of erythrocytes and lymphocytes, erythropoietic activity and turnover of iron were analyzed in 8 female subjects assigned into two groups of 4. In group A, countermeasures were applied throughout the experiment; in group B, they were used only in the recovery period. Shifts observed in a number of parameters of the turnover of iron and morphometry of the blood cells are most likely adaptive by nature and demonstrate the reaction of blood to the hypokinesia and recovery factors.

Adult↗
PubMed1997

[Effect of 120-day antiorthostatic hypokinesia on the reproductive function in women].

Original data on the peculiarities of adaptation to and functional status of the reproductive system in long-term antiorthostatic hypokinesia (AOH) have been obtained. The studies involved eight healthy female volunteers aged 26-37 years who were exposed to the head-down tilt (-6 degrees) for 120 days. The test subjects were divided into 2 groups of 4 persons each. In Group A, the countermeasures, i.e. physical exercise and pharmacological means, were used. In Group B, at no time did the test subjects use the countermeasures throughout the 120-day AOH. With and without the countermeasures, hypokinesia was found to impact the female reproductive system developing clinical symptoms of deficiency of the menstrual lutein phase and giving rise to small inclusions of functional fluids in the ovaries. Within 6 months after AOH, the ovarial function of the test subjects was fully recovered which may be indicative of the functional character of changes. These changes can be explained by dissociation of the functional relations in the hypothalamo-hypophyseal-ovarial system manifested by increases in the plasmic concentrations of luteinizing hormone (LH) against normal levels of follicle-stimulating hormone (FSH) and prolactin, and moderately increased levels of testosterone, relative hyperestrogenemia and hypoprogesteronemia. These clinical and hormonal developments are contrary to the observations usually made in various models of stress. Similarity of the hormonal profiles under hypokinesia and long-term immersion of female swimmers may be ascribed to common mechanisms underlying the disturbance of the reproductive function.

Adaptation, Physiological↗
PubMed1996

Endocrine, renal, and circulatory influences on fluid and electrolyte homeostasis during weightlessness: a joint Russian-U.S. project.

Microgravity is known to have a substantial effect on fluid homeostasis. The research described here was planned as part of the first joint Russian-U.S. science program carried out during a Shuttle flight. The aim of the program was to study the nature of the changes in fluid homeostasis induced by microgravity, as well as to determine the possible mechanisms underlying the regulation of fluid balance under conditions of spaceflight. To determine the effects of spaceflight on the homeostasis of fluid and electrolytes, measurements were taken of total body water, extracellular fluid plasma volumes, levels of regulatory hormones, and nutrient consumption before, during, and after a nine-day flight. Changes in renal function were studied before and after the flight. In these 2 subjects, weightlessness was not associated with a decreased extracellular fluid volume. However, there were the characteristic decreases in plasma atrial natriuretic peptide concentrations, and increases in plasma and urinary cortisol. Results indicated decreased urine volume, even through the first 48 hours of flight. Fluid volumes and glomerular filtration rate were increased after landing, probably related to the saline-loading countermeasure used by Shuttle crewmembers. The information obtained as a result of this research will facilitate the development of future research programs, as well as preventive measures for future long-duration spaceflights.

Body Water↗
PubMed1994

Water and electrolyte studies during long-term missions onboard the space stations SALYUT and MIR.

This contribution summarizes the results of investigations of water-electrolyte metabolism and its hormonal regulation conducted in cosmonauts who performed long-term space flights (from 18 to 366 days) aboard the space stations Salyut and Mir and compares them with the results obtained during various NASA flights. The role of the kidneys in ion metabolism regulation was assessed by various water-salt load tests before and after flights. In addition, the results of a year-long space flight and of medical experiments performed during the 237- and 241-day missions by the physicians and cosmonaut-researchers Atkov and Polyakov are reviewed in detail. In spite of interindividual variations, metabolic, and endocrine studies during prolonged space flights showed a reduction in body mass, usually with a reduction in body water and electrolytes and considerable changes in blood hormone concentrations and urinary hormone excretion. These changes reflect the processes of extended adaptation to a new environment. It is likely that shifts in electrolyte metabolism in weightlessness are primarily due to metabolic changes that diminish the tissue ability for ion retention and to concomitant changes in the endocrine status. The postflight examinations revealed changes in fluid-electrolyte metabolism and in the function of the kidneys which indicated a hypohydration status and a stimulation of hormonal systems responsible for fluid-electrolyte homeostasis in order to readapt to the normal gravitation. Postflight decline in osmotic concentration of urine in cosmonauts was accompanied by an altered response to antidiuretic hormone and was probably caused by changes in the functional state of the kidneys. We conclude that detailed knowledge of the alterations in water-electrolyte metabolism and its hormonal regulation on different stages of space flight are important prerequisites for the development of countermeasures to space deconditioning and thus for increased human efficiency in space. In addition, these data contribute to an increase in our general knowledge on the regulation of kidney function.

Aerospace Medicine↗
PubMed1992

Effect of exercise and bisphosphonate on mineral balance and bone density during 360 day antiorthostatic hypokinesia.

As we enter a phase of space exploration that will involve long-duration flights, there is a need to use ground-based models to study the long-term effects of countermeasures to prevent the loss of bone mineral in microgravity. Mineral balances, hormone levels, and bone density were measured for 360 days in nine bed rest subjects treated with an exercise program used by cosmonauts. Four of these subjects received the bisphosphonate, ethane-1-hydroxy-1-disphosphonate, 900 mg daily, a drug known to inhibit bone resorption. Compared to a 120 day control period, the bisphosphonate combined with exercise reduced negative calcium balances by 50% for the first 120 days, 80% for the second 120 days, and 69% during the third 120 days. Exercise alone had no effect until the second 120 day period, when calcium balance improved 52%. Negative phosphorus balances were not affected by either treatment. Magnesium balances were negative during the first 120 days and returned to nearly normal during the last 240 days in both groups. The combined exercise and bisphosphonate treatment prevented increases in serum ionized calcium and decreases in plasma calcitonin during the first 120 days, as well as trends toward decreases in the mineral density of the femoral neck. These results suggest that bisphosphonates can be efficiently used together with exercise to reduce calcium loss and prevent some of the changes in mineral metabolism during long-term simulated microgravity.

Adult↗
PubMed1989

Effects of a bisphosphonate (1-hydroxy ethylidene-1,1 bisphosphonic acid) on osteoclast number during prolonged bed rest in healthy humans.

Acute osteoporosis is known to occur after immobilization in spinal cord injured patients and is related to an early increase in osteoclastic bone resorption. Whether osteoporosis develops in healthy immobilized human patients is still a matter of controversy. Furthermore, acute osteoporosis was thought to be a good model to study the effects of weightlessness on the human skeleton and to adapt preventive procedures. A bed rest experiment was developed in the USSR on 15 healthy human volunteers to determine the precise effects on bone structure and cell activities. A preventive protocol, including an anti-osteoclastic drug (1-hydroxyethylidene-1,1 bisphosphonic acid; K salt) was investigated. Two transiliac bone biopsies were performed on the 15 individuals before and at the end of the 120-day bed rest period. Undecalcified bone biopsies were studied with automatic and semi-automatic image analyzers specially devoted to bone histomorphometry. Trabecular bone volume, osteoid amount, and eroded surfaces were measured. Osteoclast number was measured after histochemical identification of tartrate-resistant acid phosphatase. After the bed rest period, an insignificant bone loss was observed in healthy humans while osteoclast number was highly increased. In bisphosphonate-treated subjects, osteoclast number was markedly reduced and so was osteoid amount. Bisphosphonates were shown to present a highly cytotoxic activity on osteoclasts, a finding that has never been demonstrated in normal subjects.

Adult↗
PubMed1989

Calcium homeostasis in prolonged hypokinesia.

Calcium metabolism, its hormonal regulation and renal calciuretic function were investigated in 20 healthy volunteers during 120- and 182-day head-down tilt studies. The content of total and ionized calcium and parathyroid hormone was found to increase during the study. The concentration of calcitonin increased at an early stage of exposure and decreased thereafter. This resulted in negative calcium balance which was on the average 5, 6g per month. Measurements of iliac bone biopsies showed calcium decrease and phosphorus increase.

Adult↗
PubMed1989

Microgravity-induced changes in human bone strength.

A decrease of spongy tissue strength of iliac bone has been identified in healthy men under conditions of simulated weightlessness (bed rest). Countermeasures have significantly prevented this decrease. Additional investigations have indicated probability of degenerative-destructive bone change development under conditions of usual human activity as a consequence of bone strength decrease.

Animals↗