PubMed Health⌕ Search

Biomedical subjects

I A Nichiporuk

Publications and source records attributed to I A Nichiporuk.

17 recordsLinked to original sources
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↗
PubMed1999

[Results of studies of carbohydrate metabolism and ultrasonography of the pancreas in man after continuous anti-orthostatic hypokinesia].

Data on the hypokinesia-induced transformation of the glycemic profile and ultrasonic changes in the pancreas structure are presented. The AOH study gave further evidence of transforming glycemic curves. Moreover, increased sizes of tail and head of the pancreas and a decrease in its echogeneity were observed in all test-subjects. Structural changes in the pancreas were confirmed by biochemical investigations which revealed increased levels of blood enzymes and activation of insulin secretion. Increases in the liver size, thickness of the wall of the stomach, diameter of the splenic vein were indicative of progressing venous plethora in the portal vein system. It was shown that venous plethora are the main cause for changes in the upper GI, and in the pancreas state in particular, which can be qualified as dysfunctional. These structural changes in the pancreas could suppress its functional activity manifested by increases in blood enzymes and hormones and transformation of the glycemic profile during the glucose load.

Adult↗
PubMed1998

Male reproductive system in conditions of bed-rest in a head-down tilt.

Study of reproductive function in simulating experiments is important as for expansion of our theoretical knowledge in the field of gravitational physiology and space biology and for the decision of applied problems in space and clinical medicine. Long-term bed rest in a head-down tilt--6 degrees (BRHDT)--antiorthostatic hypokinesia is a wide spread method for ground-based simulation of space flight's conditions (mainly of hemodynamical effects of microgravity and restriction of locomotor activity). The aim of the present research was to study a reproductive function in males during 60-120 day BRHDT.

Adult↗
PubMed1998

Psychophysiological and neuroendocrine interrelations in conditions of antiorthostatic hypokinesia.

The study of psychophysiological status' interaction and interrelation with parameters of a neurohumoral regulation is important for perfection of medical and psychological support of high serviceability of the crew-members in conditions of space flight. Long-term bed rest in a head-down tilt (BRHDT, antiorthostatic hypokinesia) is used for simulation of prolonged influence of microgravity on a human body in ground-based conditions. The main objective of the present work was to reveal main links of psychophysiological state with neurohumoral parameters in BRHDT.

Bed Rest↗
PubMed1998

Ultrasonic research of abdominal organs in conditions of long-term antiorthostatic hypokinesia.

Change in functional activity of digestive system in space flight usually is associated with phenomenon of hypokinesia which takes place in microgravity. However, it is marked that the reorganization of a gastrointestinal tract in space flight occurs on a background of the phenomenon of venous plethora in abdominal cavity, which can also result in changes of functional activity in organs of digestive system. Insignificant amount of studies of venous plethora in abdominal cavity carried out in conditions of space flight does not allow to create a complete picture of this phenomenon. Hemodynamical changes comparable to microgravity are well-simulated in conditions of a long-term antiorthostatic hypokinesia (AH)--bed-rest in a head-down tilt. The present research was performed with the aim to study venous plethora in abdominal cavity in conditions of long-term AH.

Abdomen↗
PubMed1998

[Dynamic changes in the reactivity of the hormonal system regulation with the impact by LBNP sessions in long-term space mission].

Experiment INTERSTITIUM was performed on days 3, 170, 287, and 430 of the long-term MIR mission of the Russian cosmonaut-physician in order to evaluate reactivity of the system of hormonal regulation of homeostasis during LBNP sessions. Data of the experiment displayed different types of reaction of the volume controls to LBNP at the onset (F-3), in the course of and soon after recovery (R-4) from the extended mission which are signs of specific phases of adaptive shifts in the organism of cosmonaut. Exaggerated reactivity of the hormonal systems during LBNP in flight suggests more significant consequences of the test for the cardiovascular system of human in microgravity. The most expressed hormonal reaction to LBNP was documented at the very beginning of the postflight period. Plasma cGMP was materially reduced in the process of the mission and remained quite low on R-4; return of nucleotides to the norm was observed no earlier than on R-90. Complete recovery from the space mission took three months when the hormonal reaction to LBNP was same as prior to launch.

Hormones↗
PubMed1997

[Metabolism, intensity of lipid peroxidation and the antioxidant defense system in humans during chamber experiments with long-term isolation].

Blood biochemical parameters of lipid, protein, carbohydrate and energy metabolism were measured in a 135-day chamber experiment. Also, dynamics of the intensity of lipid peroxidation and status of the antioxidant defence system were evaluated. Results of the investigation showed that extended chamber isolation led to modifications of several biochemical parameters including hemoglobin, bilirubin, cholesterol and its fractions, elevated transaminase activity which are typical for long-term space mission. However, these were not accompanied by substantive changes in protein, energy and carbohydrate metabolisms, or intensity of free radical processes. Effects of prolonged stay in chamber was successfully counterbalanced by organism.

Adult↗
PubMed1997

[On-board equipment-based study of psycho-physiological and biochemical responses dynamics of operators during 135-day isolation in the "Mir" orbital station phantom].

There present the investigative findings of the dynamics of psycho-physiological and biomedical responses of the test subjects during simulated emergencies at different stages of adaptation to 135-day isolation in the Mir orbital station mock-up. Ehe main operating factor of an emergency was the 2-day sleep deprivation in combination with the continuous complex and intensive operator work which included the elements of the professional activity of the cosmonauts, among them the simulation of the regular and emergency docking of the spacecraft. By and large the observed physiological responses were characterized by moderate degree of manifestation, they were of functional character and were adequate for the investigated experimental conditions. The impaired quality of performing the applied psychophysiological tests and what is especially important the operations simulating the cosmonauts, professional activity in the extreme emergency conditions is noteworthy. Judging from some indicators the manifestation was dictated by the duration of operator isolation in the Mir orbital station mock-up and by the duration of a contingency simulation. In the degree of manifestation and in the time of development some changes in the state and working capacity of the operators were characterized by the individual differences.

Adaptation, Physiological↗
PubMed1988

Neurohumoral mechanism of space motion sickness.

This paper reviews existing hypotheses concerning the mechanisms of adaptation of the vestibular apparatus and related somatosensory systems to microgravity with reference to the flight data. Having in view theoretical concepts and experimental data accumulated in space flights, a conceptual model of the development of a funtional system responsible for the termination of vestibular dysfuntion and space motion sickness manifestations is presented. It is also shown that changes in the hormonal status during motion sickness induced by vestibular stimulation give evidence that endocrine regulation of certain functions can be involved in adaptive responses.

Adaptation, Physiological↗
PubMed1988

Hormonal status and fluid electrolyte metabolism in motion sickness.

In the first experimental series, 10 healthy male test subjects with a high susceptibility to motion sickness showed a significant increase of ACTH, cortisol, STH, prolactin, ADH, aldosterone concentrations, and plasma renin activity after vestibular tests. The 10 subjects with a moderate susceptibility exhibited a still higher increase of the hormones, except plasma renin. The 8 test subjects with a low susceptibility displayed a considerable increase in ACTH, cortisol, and STH after vestibular stimulation. In the second experimental series, the increase of STH, cortisol, ADH, aldosterone and renin occurred immediately after rotation in the moderate susceptibility subjects and an hour after exposure in the high susceptibility subjects. This may be indicative of specific immediate adaptation mechanisms or excitation transfer in the CNS in high susceptibility persons. In the third experimental animal series, the permeability of the blood-brain barrier for 125I and IgG increased after rotation. Greater concentrations of potassium, chloride, and urea in CSF are suggestive of an inhibition process activation in the CNS and, probably, of an active urea transport by the vascular plexus epithelium which maintains constant osmotic pressure of cerebral extracellular fluid and prevents hyper-hydration of CNS neurons.

Adult↗
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↗
PubMedDate not supplied

[Characteristics of motion sickness during prolonged otolith stimulation in anti-orthostatic position].

Thirty healthy volunteers were tested for an extended period of time (up to 4 hours) on modified parallel swings during a head-down tilt (-8 degrees) study. The pattern of motion sickness that developed in this situation was evaluated in terms of physiological parameters (electrocardiography, rheoencephalography, arterial pressure, respiration rate electrooculography, etc.), hormonal status, fluid-electrolyte balance, sensory function. The test subjects developed a vestibulo-hemodynamic syndrome that included vestibular disorders, spatial illusions, fluid displacement in the cranial direction, excitation of the hypothalamic-pituitary-adrenal system, changes in fluid-electrolyte balance. The resulting data may help better understand mechanisms underlying motion sickness.

Electrocardiography↗