PubMed Health⌕ Search

Biomedical subjects

V B Noskov

Publications and source records attributed to V B Noskov.

At least 37 records · Page 2Linked to original sources
PubMed1994

Diuretic as a means for rapid adaptation to weightlessness.

In a number of flights, cosmonauts and astronauts have experienced aggravation of their health status and general condition in the initial hours and days in a weightless environment. One of the trigger mechanisms for the onset of these unfavourable conditions at the start of space flight is a redistribution of body fluids and a blood shift towards the head. To ensure controlled hypohydration as a countermeasure to the deleterious effects of 0-g and to investigate the feasibility to control adaptation, six cosmonauts were administered lasix once a day during the first 3 days of a mission. All data of the experiment (correction test, questionnaire, hematocrit) were recorded on a special form in the logbook and transmitted to the control centre for processing. Results showed that the diuretic weakened the sensation of discomfort and improved the cosmonauts' general condition. Objective indices of the correction test indicate an increased work ability of cosmonauts. After hypohydration, circulating plasma volumes in the group were reduced by 6.8 + 1.0% on average.

Adaptation, Physiological↗
PubMed1994

New approaches to evaluate sympathoadrenal system activity in experiments on earth and in space.

In previous studies the activity of the sympathoadrenal system (SAS) in cosmonauts during space flights was evaluated by measuring plasma catecholamines (CA) levels and urinary CA and their metabolites concentrations. Plasma CA levels are accepted indicators of SAS activity, however, they are determined by the plasma clearances as well as the rates of CA release (spillover-SO) into the bloodstream. Nowadays methods are available which evaluate not only plasma levels of CA but also their release, spillover, uptake, reuptake, degradation and also CA synthesis in vivo measured by plasma levels of dihydroxyphenylalanine (DOPA). Plasma concentrations of DOPA, the CA noradrenaline (NE), adrenaline (ADR), and dopamine (DA), the deaminated catechol metabolites dihydroxyphenylglycol (DHPG) and dihydroxyphenylacetic acid (DOPAC), and the O-methylated metabolites methoxyhydroxyphenylglycol (MHPG) and homovanillic acid (HVA) were measured during immobilization stress (IMO) in conscious rats. Radiotracer methods were used to measure NE SO. IMO markedly increased arterial NE levels but NE SO was less elevated because the NE clearance was slightly reduced in IMO rats. Simultaneous measurements of plasma CA and their metabolites provide another means to obtain information about SAS function. For instance, dissociation between changes of plasma DHPG and NE levels can indicate changes in neuronal reuptake of NE. We found marked parallel increases in plasma NE and DHPG levels during acute IMO; however after repeated IMO, plasma NE levels were increased but DHPG responses were less pronounced suggesting a reduced NE reuptake. DOPA, the CA precursor, circulates in plasma at a concentration higher than NE. During stress, increased sympathoneural outflow stimulates DOPA synthesis and release into the circulation supporting the view that changes in plasma DOPA levels during stress reflect in vivo changes in the rate of CA synthesis. We propose to measure the new plasma indicators of SAS activity in cosmonauts and/or in animals before, during and after space flights.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

[Effects of a long-term space flight on human biochemical status].

Biochemical status of cosmonauts was examined during long (4-6 months) space flights. A Reflotron device and test strips with an active principle based on "dry chemistry" methods were used. Blood plasma samples were collected from the finger for later laboratory analyses. Parameters characterizing metabolic status and functions of various body systems and organs were tested in blood and plasma samples. Space flight was found associated with increased peripheral blood levels of glucose, cholesterol, triglycerides, urea, uric acid, lactate, total protein, lactate dehydrogenase and amylase activities. The detected shifts were reversible. A hypothesis on minimal levels of energy metabolism under conditions of weightlessness was confirmed by reduced malate dehydrogenase and creatine phosphokinase activities in the blood during the flights. No correlation between the detected shifts and space flight duration was revealed.

Blood↗
PubMed1994

Changes in blood and plasma composition with lower body negative pressure on the ground and in space in one subject.

In one cosmonaut, we investigated lower body negative pressure (LBNP)-induced capillary fluid shifts which we hypothesized would be changed by microgravity (micrograms) adaptation. Sound pulse velocity (SV) was determined in whole blood and plasma samples, using a new method that could detect 0.1% protein concentration changes. Experiments were performed 3 months preflight (supine), during space flight (6th day in orbit), and postflight (supine; 4th day after landing). Antecubital blood was taken at the beginning (3 min: time a) and after shut-down (+2 min: time b) of 40 min LBNP (-15/-30/-35 mm Hg for 15/15/10 min, respectively), since in control experiments with multiple sampling on Earth, the largest difference (increase) between blood and plasma SV was observed between a and b. Our cosmonaut had a 1.6 m/s increase in blood sound pulse velocity (BSV) preflight and a 4.0 m/s increase postflight, whereas BSV stayed unchanged in flight. Plasma sound pulse velocity (PSV) increased 1.2 m/s preflight and 1.7 m/s postflight, whereas PSV did not rise (-0.4 m/s) in flight. This would indicate profoundly altered LBNP-induced fluid dynamics in flight, compared to control (1-g) conditions. On the 4th day postflight, blood and plasma sound velocity increased more with LBNP than preflight, indicating greater hemoconcentration than under control conditions. In summary, the data suggest: 1) altered fluid shifts between blood and interstitial compartments during LBNP with 6 d adaptation to microgravity; and 2) increased hemoconcentration during LBNP early after a 10-d spaceflight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[The interstitial organ in weightlessness: a clinico-physiologic model].

We performed an experiment within the 1991 Austromir mission, 3 months preflight, on the 6th inflight and 4th postflight days, respectively. Primary goal was to measure changes in venous blood and plasma sound velocity (BSV, PSV) with lower body suction (LBNP). Contrasting earth-based findings, there was no increase in BSV nor PSV with LBNP inflight. Postflight, the elevation in both values was greater than expected. Taken together with LBNP data from the German 1992 Mir cosmonaut, we propose the hypothesis that the dynamics of tissue fluid exchange is profoundly influenced by m-g adaptation. A further goal of the experiment was to determine volume- and stress-sensitive hormones. The results need validation by additional flight data and might be considered as an important contribution to our understanding of the normal functioning and pathophysiology of the interstitial organ.

Adaptation, Physiological↗
PubMed1992

Changes of hormones regulating electrolyte metabolism after space flight and hypokinesia.

The changes of hormones in plasma involved in the body fluid regulation were studied in human subjects during and after space flights in relation to redistribution of body fluids in the state of weightlessness. Since hypokinesia was used as a model for simulation of some effects of the stay in microgravity the plasma hormone levels in rats exposed to hypokinesia were also investigated. Plasma aldosterone values showed great individual variations during the first inflight days, the increased levels were observed with prolongation of space flights. The important elevation was found in the recovery period, however it was interesting to note, that in some cosmonauts with repeated exposure to space flight, the postflight plasma aldosterone levels were not elevated. The urine excretion of aldosterone was increased inflight, however in postflight period the decrease or increase were found in the first 1-5 days. The increase of plasma renin activity was observed in flight and postflight period. The rats were exposed to hypokinesia (forced restriction of motor activity) for 1, 7 and 60 days and urine was collected during last 24 hours. The animals were sacrificed and the concentration of electrolytes and of levels of corticosterone, aldosterone (A), ANF and plasma-renin activity (PRA) were determined in plasma. In urine excretion of sodium and potassium were estimated. An important increase of plasma renin activity and aldosterone concentration was found after short-term hypokinesia (1 day). These hormonal values appear to decrease with time (7 days) and are not significantly different from controls after long-term hypokinesia (60 days). A decrease of values ANF in plasma was observed after 1 and 7 days hypokinesia. After prolonged hypokinesia a decrease of sodium plasma concentration was observed. The excretion of sodium in urine was higher in long-term hypokinetic animals. There were no significant changes of plasma potassium levels in rats exposed to hypokinesia, however the urinary excretion of potassium was elevated. In rats exposed to hypokinesia for 7 and 60 days an increase of urine osmolality was observed. The results of hormone and electrolyte determination in plasma of cosmonauts after space flight and in experimental animals after hypokinesia suggested that in evaluation of relations between the changes of hormone levels and electrolyte in plasma and urine other factors like emotional stress working load; altered diurnal cycles should be considered in interpretation of homeostatic response of fluid and electrolyte metabolism to space flight conditions.

Aldosterone↗
PubMed1991

Activity of the sympathoadrenal system in cosmonauts during 25-day space flight on station Mir.

The activity of the sympathoadrenal system in cosmonauts was studied by measuring plasma and urinary catecholamines and their metabolites and conjugates. The appliance Plasma 02 was used for collecting, processing, and storing blood and urine samples from the cosmonauts during the course of a 25-day flight on board the station Mir. Plasma and urine concentrations of adrenaline (A), noradrenaline (NA), and dopamine (DA) as well as urinary levels of vanillylmandelic acid (VMA) and homovanillic acid (HVA), and plasma levels of catecholamine sulphates were determined before, during and after the space flight. Plasma NA levels were slightly elevated on day 9 and plasma A on day 20, whereas plasma DA levels were unchanged. However, most of the changes were within the normal range of control values. Sulphates of plasma catecholamines did not change during flight but they were significantly elevated after landing. Urinary levels of A, NA, DA, VMA, and HVA were comparable with preflight values but were elevated at the different intervals studied after landing. The results obtained suggest that in the short period of about 9 days of the cosmonaut's stay in space the sympathoadrenal system was slightly activated indicating a mild stressful influence of the initial period of flight. This short-term space flight compared to long-term flight did not as markedly activate the sympathoadrenal system during the process of re-adaptation to Earth's gravity after landing. Our data suggest that weightlessness is not a stressful factor activating the sympathoadrenal system but it sensitizes the responsiveness of this system during the re-adaptation period after space flight.

Adaptation, Physiological↗
PubMed1991

Effect of space flights on plasma hormone levels in man and in experimental animal.

An important increase of plasma hormone levels like insulin, TSH and aldosterone was observed in human subjects after space flights, however in the changes of plasma content of ACTH, cortisol, adrenaline and noradrenaline the individual variations were observed in relation to number and duration of space flight. For evaluation of the effects of these changes in plasma hormone levels on metabolic processes also the experiments with small animals subjected to space flights on a board of biosatellite of Cosmos series were running. An elevation of plasma levels of corticosterone, adrenaline, noradrenaline and insulin was found in rats after the space flights of duration from 7 to 20 days. It was demonstrated, that the increase of corticosterone in plasma is followed by the activation of enzymes involved in the amino acid metabolism in rat liver (tyrosine aminotransferase, tryptophanpyrolase, alanine aminotransferase and aspartate aminotransferase). After a short recovery period (2 to 6 days) the plasma corticosterone concentration and also the activity of liver enzymes returned to control levels. The exposition of animals to stress stimuli during this revcovery period showed higher response of corticosterone levels in flight rats as compared to intact controls. The increase of plasma catecholamine levels was not followed by elevation of lipolysis in adipose tissue. This is due to lower response of adipose tissue to catecholamine because a decrease of the stimulation of lipolysis by noradrenaline was observed in animals after space flight. The increase of insulin was not followed by adequate decrease of glucose concentration suggesting a disturbances in glucose utilization similarly as in cosmonauts after a long-term space flight. These results showed that changes in plasma hormone levels, observed after space flight, affected the regulation of metabolic processes in tissues.

Animals↗
PubMed1991

Mechanism of postflight decline in osmotic concentration of urine in cosmonauts.

The ratio of reabsorption of osmotically free water to osmolal clearance in individual urine voids was about the same before and after short-term spaceflights (the points fall on the same regression line). This ratio was reduced after long-term flights, so that the regression lines for pre- and postflight values have different slopes. This change in the function relating the two factors was accompanied by increased vasopressin in blood plasma and probably was caused by altered cellular reaction to vasopressin. The decrease in the effect of vasopressin may have been caused by development of hypokalemia and hypercalcemia in the cosmonauts, and decrease in cellular potassium in the outer renal medulla (this effect was observed in experiments on rats after flights on biosatellites). We established that, in addition to cAMP, cGMP and inositol trisphosphate participate in cellular reactions to vasopressin. Increases in the concentration of cGMP and decrease in the formation of inositol trisphosphate in the presence of neomycin increase the hydro-osmotic effect of vasopressin. We hypothesize that modulation of the effect of vasopressin in cosmonauts is due to change in the functional state of their kidneys.

Aerospace Medicine↗
PubMed1988

Plasma and urine catecholamine levels in cosmonauts during long-term stay on Space Station Salyut-7.

The activity of the sympathetic adrenal system in cosmonauts exposed to a stay in space lasting for about half a year has so far been studied only by measuring catecholamine levels in plasma and urine samples taken before space flight and after landing. The device "Plasma 01", specially designed for collecting and processing venous blood from subjects during space flight on board the station Salyut-7 rendered it possible for the first time to collect and freeze samples of blood from cosmonauts in the course of a long-term 237-day space flight. A physician-cosmonaut collected samples of blood and urine from two cosmonauts over the period of days 217-219 of their stay in space. The samples were transported to Earth frozen. As indicators of the sympathetic adrenal system activity, plasma and urine concentrations of epinephrine and norepinephrine as well as urine levels of the catecholamine metabolites metanephrine, normetanephrine, and vanillylmandelic acid were determined before, during and after space flight. On days 217-219 of space flight plasma epinephrine and norepinephrine levels were slightly increased, yet not substantially different from normal. During stress situations plasma norepinephrine and epinephrine levels usually exhibit a manifold increase. On days 217-219 of space flight norepinephrine and epinephrine levels in urine were comparable with pre-flight values and the levels of their metabolites were even significantly decreased. All the parameters studied, particularly plasma norepinephrine as well as urine norepinephrine, normetanephrine, and vanillylmandelic acid, reached the highest values 8 days after landing. The results obtained suggest that, in the period of days 217-219 of the cosmonauts stay in space in the state of weightlessness, the sympathetic adrenal system is either not activated at all or there is but a slight activation induced by specific activities of the cosmonauts, whereas in the process of re-adaptation after space flight on Earth this system is considerably more markedly activated.

Adrenal Glands↗
PubMedDate not supplied

[The pharmacodynamic and pharmacokinetic characteristics of furosemide and furesis].

The object of the work was comparative study of the special features of the pharmacodynamic and pharmacokinetic properties of the diuretics furosemide and furesis in an ambulant regimen with the subject lying in an antiorthostatic position. Six practically healthy males were examined. They were given per os either 40 mg furosemide or one tablet of furesis (49 mg furosemide and 50 mg triamterine). Blood from the vein and urine were repeatedly tested.

Adult↗
PubMedDate not supplied

[Water-salt metabolism and its hormonal regulation studied in the 2nd joint Soviet-French space flight].

During a 25-day space mission of French cosmonaut on board Mir station, the joint Soviet-French Czecho-Slovak experiment "Minilab" has been conducted in order to evaluate a fluid-electrolyte metabolism status and its hormonal control at different flight stages and early postflight. In cosmonaut venous blood was drawn twice, and 24-hour urine samples were collected on mission Days 5 and 19. With the aid of Plasma-02 equipment the blood plasma and urinary samples were treated, frozen and maintained aboard the station. Postflight, frozen samples were delivered to the laboratory for further analyses. In-flight, urinary excretion of fluid and sodium decreased by 25-35%. On mission Day 9, the blood plasma levels of vasopressin increased by 450% and on Day 20 by 700% as opposed to the baseline levels, blood aldosterone content was also elevated with an increased renal excretion of both hormones. Blood plasma renin activity elevated two-fold, and atrio-natriuretic factor (ANF) content practically did not differ from a baseline value. In-flight circulating plasma volume (CPV) decreased by 20%. Postflight, there occurred the body hypohydration and activation of the hormonal systems providing a retention of body fluids and electrolytes to restore an adequate CPV and fluid-electrolyte homeostatic as a whole.

Adaptation, Physiological↗
PubMedDate not supplied

[Investigations of human body liquids in long-duration space flight].

The hydration status of a Russian member on a six-month ISS mission was evaluated by bio-impedancemetry during monthly sessions of experiment Sprut (Octopus). Body liquids tended to diminish gradually and measured minimum values on the landing day. By the end of mission the total volume of liquids reduced by 18.9 %; the intracellular and extracellular portions lost 19.0 and 20.4 %, respectively. Time history of specific body liquids was identical in flight. Reductions in the body mass and lean mass (according to impedancemetry) reached 6.9 % and 8.0 %, respectively. These results point to a decrease in the human body hydration status during long-duration space flight concurrent to losses in the muscle mass. In two weeks after landing there was an implicit trend toward regaining the pre-flight hydration status and body mass; yet, both parameters were still below pre-flight values.

Electric Impedance↗