Biomedical subjects

I M Larina

Publications and source records attributed to I M Larina.

At least 19 recordsLinked to original sources

PubMed2006

[The influence of space flights on water-electrolytes turnover and its regulation].

A study of water-electrolyte exchange, the condition of water milieu of the organism, and the volume- and electrolyte homeostasis regulation in space flights, and also in postflight period has shown the important role of the water-salt homeostasis in adaptation of the human and animal organism to weightlessness. Obviously, downturn of food consumption, renal excretion and the intestine output seem to be caused by suppression of activity of mechanisms of ion deposition. The most intensive changes of the liquid milieu volumes occur in the first days of weightlessness or in its ground simulation. And, with prolonged duration, the changes of extracellular liquid volume and the volume of plasma do not extend. After termination of long space flights, activation of renin-aldosterone systems occurs as well as a decrease in efficiency of antidiuretic hormone, misbalance of pressor/unpressor prostanoids. In the period of re-adaptation after space flights, development of desensitization of kidneys to endogenous ADH occurs. This is the basis for researches directed to improvement of the existing scheme of correction of the hydrogenous status of the astronaut organism in the closing stage of flight.

Animals↗

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↗

PubMed2005

[Serum creatine kinase levels and the number of sarcolemmal dystrophin disruptions in human skeletal muscle fibers under conditions of weightlessness simulation].

9 male volunteers took part in the experiment. They were divided in two groups. 5 volunteers (control group) have been in "dry" immersion for 7 days. 4 volunteers (stimulated group) in addition to "dry" immersion were treated with artificial support stimulation. We investigated the number of muscle fibers with the disruptions of sarcolemmal dystrophin and serum creatine kinase levels. 7-day "dry" immersion did not change the mean number of muscle fibers with dystrophin disruptions, it led to significant decrease of serum creatine kinase levels and did not influence on the sensitivity of sarcolemma to injury. Artificial support stimulation did not influence on these parameters.

Adult↗

PubMed2004

Hormonal changes during long-term isolation.

Confinement and inactivity induce considerable psychological and physiological modifications through social and sensory deprivation. The aim of the SFINCSS-99 experiment was to determine the cardiovascular and hormonal pattern of blood volume regulation during long-term isolation and confinement. Simulation experiments were performed in pressurized chambers similar in size to the volumes of modern space vehicles. Group I consisted of four Russian male volunteers, who spent 240 days in a 100-m(3 )chamber. Group II included four males (one German and three Russians) who spent 110 days in isolation (200-m(3) module). The blood samples, taken before, during and after the isolation period, were used to determine haematocrit (Ht), growth hormone (GH), active renin, aldosterone, and osmolality levels. From the urine samples, electrolytes, osmolality, nitrites, nitrates, cortisol, antidiuretic hormone (ADH), aldosterone, normetanephrine and metanephrine levels were determined. The increase in plasma volume (PV) that is associated with a tendency for a decrease in plasma active renin is likely to be due to decreased sympathetic activity, and concords with the changes in urinary catecholamine levels during confinement. Urinary catecholamine levels were significantly higher during the recovery period than during confinement. This suggests that the sympathoadrenal system was activated, and concords with the increase in heart rate. Vascular resistance is determined by not only the vasoconstrictor but also vasodilator systems. The ratio of nitrite/nitrate in urine, as an indicator of nitric oxide release, did not reveal any significant changes. Analysis of data suggests that the duration of the isolation was a main factor involved in the regulation of hormones.

Adaptation, Physiological↗

PubMed2004

Serum creatine kinase levels and the number of sarcolemmal dystrophin disruptions in human skeletal muscle fibers under conditions of 7-day "dry" immersion.

9 male volunteers took part in the experiment. They were divided in two groups. 5 volunteers (control group) have been in "dry" immersion for 7 days. 4 volunteers (stimulated group) in addition to "dry" immersion were treated with artificial support stimulation. We investigated the number of muscle fibers with the disruptions of sarcolemmal dystrophin and serum creatine kinase levels. 7-day "dry" immersion does not change the mean number of muscle fibers with dystrophin disruptions, it leads to significant decrease of serum creatine kinase levels and does not influence on the sensitivity of sarcolemma to injury. Artificial support stimulation does not influence on these parameters.

Creatine Kinase↗

PubMed2003

[Antidiuretic reaction of the human and rat kidney to peroral administration of arginine-vasopressin and desmopressin].

Water in amount of 5 ml/100 g body weight was administered through a gastric probe into the stomach in alert rats; subjects-volunteers drank 20 ml of water per 1 kg of body weight. This resulted in diuresis at the peak of which the excreted water fraction reached 23% in rats and 12.4% in human subjects, whereas excretion of the osmotically free water amounted to 0.103 +/- 0.018 ml/min/100 g body weight and 10.0 +/- 1.8 ml/min/1.73 m2 of the body surface, respectively. These data indicate a practically complete inhibition of the arginine vasopressin secretion. On intragastric administration of 10 micrograms of arginine vasopressin or 0.2 microgram of desmopressin, with water in rats, a prolonged and quite obvious antidiuretic response occurred, with a marked increase of reabsorption of the osmotically free water in kidneys. A direct correlation has been found between the dose of the intragastrically administered vasopressin in the dose range from 0.1 to 10 micrograms/100 g body weight and a decrease of clearance of the osmotically free water. In subjects volunteers, an antidiuretic reaction to administration of 0.2 mg of desmopressin with water, was found. The data obtained provide a direct proof of intestinal absorption of nanopeptides without loss of their physiological activity. Significance of the data obtained for physiology of digestion and for clinical medicine, is discussed.

Administration, Oral↗

PubMed2003

[Hormonal regulation of metabolism in the human body in microgravity and during simulation of its physiological effects].

The paper presents results of investigations into the effects of space flight and simulation experiments of various length on the hormonal regulation of metabolism in the human body. Microgravity was shown to instigate shifts on different levels of the hormonal regulation and consequent adjustment of metabolism to this new environment. For instance, adaptation occurs on the level of basal secretory activity resulting in altered metabolism and formation of a pool of hormones. Metabolism readaptation to the Earth's gravity is dependent on polymorphic processes in the system of hormonal regulation developing in the course of time. Trends in the hormonal regulation of water-electrolyte metabolism during early adaptation point to inequality of contributions of the antidiuretic hormone, natriuretic peptide, and the renin-angiotensin-aldosterone system. In the ground-based simulations responses of the hormonal regulation of water-electrolyte metabolism differ in intensity and types of hormones involved. Temperature variation can modify reactions of the comosis and volume regulating hormones at the beginning of adaptation. Physical-chemical regulation of calcium homeostasis in microgravity reveals itself by a rapid decline of the calcium-binding ability of blood buffers and, later on, degradation of the relative ability of extraplasmic structures to bind calcium. Qualitative and quantitative changes in the diurnal rhythm of the suprarenal steroidogenesis are indicative of modification of intensity of reactions of the main biosynthetic sequences. Countermeasures used by test-subjects in these investigations loosened significantly the aldosterone-secreting biosynthetic sequences but were favorable to the synthesis of testosterone and hydrocortisone. Some of the highly variable processes of hormonal regulation were mute to the diurnal rhythms in the pre-flight and preexperimental periods.

Adaptation, Physiological↗

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↗

PubMed2000

[Protein turnover during and after extended space flight].

A 15N-glycine tracer technique was used to study protein turnover in four Russian cosmonauts and two U.S. astronauts who had spent long time aboard the Russian orbital station MIR. As was shown, in space flight protein synthesis falls by 46% on the average, which substantially exceeds estimations made on the basis of data about bed-rested human subjects. Reduction in protein synthesis during space flight is connected with the negative energy balance; therefore, it appears imperative to keep balance between energy intake (foodstuffs) and expenditure by cosmonauts on long-term mission.

Circadian Rhythm↗

PubMed2000

[The role of individual reaction s of thermal and water-electrolyte metabolism to suited immersion].

Role of individual reactions of thermal and water-electrolyte metabolism and their relation to the mechanisms of hormonal control were studied during suited immersion (SI). The investigation consisted of 177 man/exposures from 3 hrs up to 3 days of 46 male volunteers. Parameters of mass, heat and water-electrolyte metabolism, and hormonal control were determined on a background of monitoring consumption of special ratios. Based on the complex evaluation of tolerance of weight-free SI for 1 to 3 days, parameters of thermal and hydroionic homeostasis were found to be the predictor variables. Extreme types of reactions to SI were in the ratio of 1:4 (tolerant/intolerant subjects). An extreme reaction appears to be an individual constitutional characteristic of the body the dimensions of which are equal during repeated immersion. As for the water-electrolyte parameters, extreme levels of SI tolerance were significantly different in the amount and velocity of renal excretion of liquids and liquid losses due to perspiration (897 +/- 253 ml and 2010 +/- 218 ml in SI tolerant and intolerant subjects, serotonin variability in everyday life and serotonin dynamics during SI (significant increase in tolerant subjects and no dynamics in intolerant subjects after 24 hrs in SI). The complex evaluation of the reaction showed nonstationary thermal state and reduction of oral temperature by 1 degree C in SI intolerant subjects after initial 1-1.5 days of exposure. In the course of 3 days, the negative water balance showed an increase; body mass losses were in parallel with the development of motion sickness and hyperventilation, and disturbance in the rhythm of the sympathoadrenal activity. The renin-aldosterone system reacted most actively out of all the hormonal systems and did not adapt to SI within a day and a half. Thermal state of SI tolerant subjects was stationary during 1-1.5-d immersion; oral temperature dropped by 0.2-0.4 degree C, liquid losses and AP deviations were relatively small and blood osmolality remained unchanged on a background of stable adaptive reactions of various components of the neuroendocrine system. Adaptation to SI occurred in the period from one day to a day and a half.

Adaptation, Physiological↗

PubMed2000

Vertical and horizontal posture during suited immersion: similarity and differences according to some body functions.

The role of axial body orientation was weighed during acute adaptation to suit immersion (SI) in 3 hr vertical (SIv, n=4) exposure series, and 3 d experiments in which six volunteers participated in both SIv and SIh. Various types of SI recruited different hormonal mechanisms to induce similar reactions of the water-electrolyte metabolism (WEM). Changes in the body position relative to the gravity vector modified equally strength and dynamics of the WEM regulation. The experimental data suggest that osmo- and volume-regulation reactions to SIv shown the response to the actual volumetric stimulus against the "distributed" weight-bearing reaction. They are less vigorous as compared to SIh and do not reach maximum within 3 hrs. Physiological reactions to SIh were marked by greater effects of ADH on the kidney when compared with dry immersion, and an additional stimulation of aldosterone secretion by the sympathetic nervous system and/or ACTH. SIh caused rapid and more heavy symptoms of motion sickness that correlated with body mass reduction, negative water balance, degradation of tolerance of classic physical tests executed after SI. Three-days SIv, as opposed to SIh, resulted in more profound hypervolemia in the upper body of the test-subjects.

Adaptation, Physiological↗

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↗

PubMed1999

[Mechanisms of early changes in water-electrolyte metabolism in man in various ground-based models of the effects of microgravity].

Analysed was an array of data amassed in 4 series of experiments with simulated microgravity effects (HDT (-6 degrees); dry and suited immersions in horizontal and vertical position). Water-electrolyte turnover in blood and urine and hormonal controls have been under study. It was demonstrated that irrespective of the body axis position relative to the gravity vector in the immersion models, reactions of the active regulation of the water--electrolyte metabolism were noted already within the initial hours, i.e. more rapidly than in HDT. During the early phase of adaptation to the immersion models, some ostensibly similar responses were governed by different hormonal controls. Unlike the dry immersion, the suited immersion tests with various body positioning modified not only the strength but the dynamics of the water-electrolyte regulation, too. Findings also included differences in the dynamics osmo- and volumoregulation in the vertical and horizontal suited immersion tests which are, possibly, reflective of recruitment of different stimulating mechanisms and efficiency of organs-targets.

Adaptation, Physiological↗

PubMed1997

Psycho-physiological monitoring in real and simulated space flight conditions.

Earlier in simulating experiments from long isolation of small group in hermetic cabin we were found out the significant interrelation between changes physiological parameters and subjective appraisal of a condition, activity regulating systems of organism, individual variability of a colour choice, and also quality of operator's activity. On the basis of these results we develop a method of psychophysiological monitoring. The important component of a method is study of the variational characteristics of registered parameters, with the purpose of reception of the information about character of transients in organism. The present research is carried out in conditions of 135-daily isolation in a breadboard model MIR station (experiment HUBES). Its PURPOSE was study of dynamic psycho-emotional condition, simultaneously with study physiological and biochemical parameters, describing process of adaptation to complex conditions of ability to live. Besides were analyzed the results of circadian rhythm's researches during space flights of 6 Russian cosmonauts (duration from 70 till 182 days) on orbital MIR station.

Adaptation, Physiological↗

PubMed1997

Muscle atrophy and hormonal regulation in women in 120 day bed rest.

It is known, that exposures to real and simulated weightlessness results in pronounced reduction of the cross-sectional area (CSA) of slow-twitch(ST) and fast-twitch(FT) fibers of mammalian muscle. After space flights of various durations, head-down tilt bedrest, and 7-days of dry immersion sufficient [correction of isufficient] reductions of CSA of both fiber types were observed in man and in the majority of these cases the atrophy levels of ST and FT fibers were similar. It is well-known, that elevated contractile activities of muscle system attenuate muscle atrophy development. It remains still unclear which fiber type is more susceptible to training effects. Among physiological mechanisms involved in the process of microgravity-induced atrophy development which are supposed to be the most important are the profound decrease of a mechanical tension of muscle fibers in situ and alterations in hormonal control of muscle protein metabolism. But it is not known yet if the hormonal changes in the course of exposure to gravitational unloading match somehow the time-course of muscle fiber size reduction. The aim of the study was to investigate the time-course of muscle fiber atrophy development and changes in plasma hormone levels in the course of long-duration BR with and without high-intensity locomotor interval physical training.

Adenosine Triphosphatases↗

PubMed1996

Energy substrates, hormone responses and glucocorticoid binding in lymphocytes during intense physical exercise in humans following phosphocreatine administration.

Eight healthy untrained male volunteers pedalled a cycle ergometer according to two exercise protocols: the first involved step-wise increasing physical exercise to maximal (MPE); the second involved prolonged (35 min) submaximal physical exercise (PPE) at 70% of the individual's maximal oxygen uptake. Each volunteer performed these exercise twice, following either an intravenous injection of phosphocreatine (PCr) or a placebo of an isotonic NaCl solution. Anaerobic threshold (AT) was determined from the point of departure of the ventilatory response from linearity and from the sudden increase in venous blood lactate concentrations during MPE. After exercise following placebo administration we observed increases in concentrations of blood substrates, plasma adrenocorticotropin (ACTH), growth hormone and cortisol and in the number of glucocorticoid receptors in lymphocytes without changes in the dissociation constant. Intravenous administration of PCr (starting 1 day before exercise) led to an increase in the total workload (on average by 5.8%) and in AT (on average by 6.8%) during MPE and to a better tolerance of exercise during PPE. Following PCr administration we observed lower blood lactate concentrations and different patterns of some enzyme activities, less pronounced changes in plasma ACTH and cortisol concentrations and in glucocorticoid binding in lymphocytes, but no changes in plasma growth hormone concentrations compared to the placebo. The results showed that intense physical exercise led not only to increases in blood hormone concentrations but also to an increase in the density of glucocorticoid receptors in lymphocytes. Intravenous PCr injection led to smaller changes in ACTH and cortisol concentrations as well as to a lower activation of glucocorticoid binding in lymphocytes.

Adrenocorticotropic Hormone↗