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Biomedical subjects

B V Afonin

Publications and source records attributed to B V Afonin.

At least 19 recordsLinked to original sources
PubMed2003

[Modified methods of percutaneous electrogastroenterography].

In 62 normal males and females gastrointestinal (GI) electrical activity was evaluated before and after standard breakfast with the method of epicutaneous electrogastroenterography (EGEG) with the use of AgCl electrodes and original hard- and software "Gastroenterograph" developed by the authors. Spectral analysis (SA) of GI electrical potentials enabled quantification of the electrical activity of the stomach, duodenum, jejunum, ileum and the whole of the small intestine. The stomach and the small intestine were main contributors to the total GI electrical activity during fasting. Changes in the functional activity of the digestive system after the meal were characterized by increases in selected SA parameters (length of the spectral curve and area underneath), dissociation between their values and redistribution of ratios in different GI segments.

Action Potentials↗
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

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↗
PubMed1987

[Functioning of the pituitary-adrenal system during the vestibulo-vegetative syndrome and administration of dalargin and nalorphine].

Changes in ACTH, cortisol, beta-endorphin have been investigated during vestibulo-vegetative syndrome (VVS) and injections of dalargin (leu-enkephalin analog) and nalorphine (agonist-antagonist of opioid receptors) in 9 volunteers with low level vestibulo-vegetative stability. Cumulative coriolis acceleration test during rotations on a special chair was used for VVS modelling. Dalargin (1-4 mg), nalorphine (5 mg) and placebo (NaCl solution) were injected intravenously 5-15 min before rotation. A significant increase in ACTH, cortisol and beta-endorphin plasma levels has been observed. Mean positive linear correlation (r greater than +0.6) between ACTH and beta-endorphin and ACTH and cortisol was noted immediately after the test only when dalargin was injected. It is suggested that in VVS there develops a hormonal conflict, i. e. an adequate hormonal release is disturbed.

Autonomic Nervous System Diseases↗
PubMed1982

[Results of endocrinolgic studies of the 3rd international crew of the scientific orbital station complex; Soyuz 29 - Salyut 6 - Soyuz 31 (joint space flight enterprise of the USSR - GDR). 2. Hormones and biologically active substances in blood].

Cortisol, insulin, somatotropin, thyreotropin, thyroxine, triiodothyronine, testosterone, aldosterone, c-AMP, c-GMP, prostaglandins (PGF1-x, PGF2-x, PGA + E), and renin concentrations in serum or plasma of the venous blood of the third international crew of the scientific orbital complex of "Soyuz 29 - Salyut 6 - Soyuz 31" were determined following the 7-day space flight. The increased activity of the renin-angiotensin-aldosterone system before the flight as well as variations in the pressor/depressor prostaglandin ratios indicate an increased strain during the pre-flight period. During the first stage of the post-flight period some parameters were changed due to the landing process and the returning to earth gravity. The associated physical load and the onset of reactions for enhancement of the orthostatic tolerance resulted in an increase of cyclic nucleotid and thyroxine concentrations. The relatively higher levels of the pressor PGs of group F in comparison with the prostaglandins A + E could be evaluated as a compensatory reaction for enhancement of the orthostatic tolerance. The cortisol and STH concentrations increased with growing motor activity. The variations seen after the 7-day space flight were essentially within the reference areas. It may be assumed that the readaptation was not yet totally accomplished by the 8th day after landing.

Endocrine Glands↗
PubMedDate not supplied

[Prebiotics--promising alimentary preventors of digestion dysfunctions caused by adverse environmental factors].

Prevention and treatment of digestive dysfunction due to hostile environments can be effected by prebiotics i.e. carbohydrates undigestible by the upper GI tract but favorable to selective stimulation of the growth and metabolizing activity of nonpathogenic commensal microflora. There are empiric evidence of the prebiotics positive action on GI cells and tissues, large intestine micro-ecology, mineral and lipid metabolism, and the immune status of humans and animals. Therefore, there is good reason to seek to develop brand new foods that would contain prebiotics, and recommendations on their use in common and extraordinary conditions.

Environmental Exposure↗
PubMedDate not supplied

[Status of water-electrolyte homeostasis and the systems of hormonal regulation during 237-day space flight].

On mission days 216-219 two crewmembers collected urine and recorded their food and water consumption during three days on end. The cosmonaut-physician withdrew blood samples from the vein and finger. In addition, he made venipuncture to himself and drew blood. Urine and blood samples were frozen and returned to the ground for analysis. In spite of individual variations of each cosmonaut, they all showed a trend for water and sodium retention which was provided by adequate hormonal rearrangement, i. e. increased production of ADH and aldosterone. No disorders in calcium and phosphorus metabolism were seen. Immediately postflight the cosmonauts displayed typical changes in fluid-electrolyte balance and renal function that suggested body dehydration and adjustment to Earth's gravity.

11-Hydroxycorticosteroids↗
PubMedDate not supplied

[Role of active vitamin D3 metabolites in regulating calcium metabolism in rats during hypokinesia].

The rats exposed to prolonged hypokinesia showed hypocalciemia, lower PTH and higher calcitonin concentrations in the serum, decreased calcium absorption in the small intestine, and a trend toward nephro- and arteriocalcinosis. Prophylactic administration of 24,25-hydroxy D3. 1,25-hydroxy D3 and their combinations enhanced calcium absorption and alleviated hypocalciemia. The changes in the hormonal regulation of calcium homeostasis can be viewed as a factor responsible for calcium metabolic disorders associated with hypokinesia.

24,25-Dihydroxyvitamin D 3↗
PubMedDate not supplied

[Morphological and biochemical analysis of the organs and tissues of rats following a 30-day exposure to increased gravitational forces of 1.1 and 2.0 G].

During 30 days rats were centrifuged at 1.1 and 2.0 G. On centrifugation day 30 the rats showed body mass losses, decrease of plasma ACTH, activation of the renin-angiotensin-aldosterone system (RAAS) and ultrastructural changes in the mossy fiber terminals in the nodulus cortex which were indicative of the state of excitation (at 1.1 G) or excess excitation (at 2.0 G) in the system of the utriculus receptor cell and vestibular ganglion neuron (RCN). On the 2nd day after centrifugation the ultrastructural changes in the terminals pointed to a lower activity of the RCN system which was below the physiological norm. As compared to centrifugation day 30, the RAAS became more active on the 2nd day of recovery. On the 7th day of recovery (after centrifugation at 1.1 G) the RCN ultrastructure, RAAS and ACTH concentrations returned to the normal. The general trends of the RAAS and RCN changes seen on the 2nd day of recovery and identified by other authors at an acute stage of adaptation to microgravity suggest that the data obtained on the 2nd day of recovery may be used to analyze certain effects which develop during an acute stage of adaptation to microgravity in mammalian organs and systems responsible for the perception of modified gravity and their adaptation to a new level of gravity.

Adaptation, Physiological↗
PubMedDate not supplied

[Homeostatic reactions of the blood of experimental rats after "Kosmos-1667" flight].

Biochemical analysis of blood of rats sacrificed 4 to 8 hours after Cosmos-1667 flight revealed a significant increase of corticosterone, decrease of 11-dehydroxycortisol, testosterone, total and bound thyroxine, and increase of glucose, phosphate, creatinine, alanine aminotransferase and total antioxidative activity. Changes in hormonal concentrations, glucose content and stimulation of antioxidant defense system were associated with a moderate gravitational stress. Increases in the creatinine and inorganic phosphate concentrations can be viewed as specific effects of microgravity related to musculo-skeletal or fluid-electrolyte changes.

Animals↗
PubMedDate not supplied

[Effect of short-term space flights on the activity of the renin-angiotensin-aldosterone system and on the blood concentration of cyclic nucleotides and prostaglandins].

After short-term flights renal excretion of aldosterone increased, thus suggesting its enhanced production and metabolism. An adequate increase of aldosterone synthesis was accompanied by an increase of its concentration in blood. An inadequate activation of mineralocorticoids manifested as a lower concentration of blood aldosterone and a greater excretion of aldosterone in the urine. These differences in the mineralocorticoid activity were determined by the renin-angiotensin system whose activity was associated not only with fluid-electrolyte metabolism but also with changes in the concentration of cyclic nucleotides and prostaglandins that reflect the vascular tone and sympatho-adrenal activity. An increased activity of the renin-angiotensin system seen in most cosmonauts at an acute stage of readaptation was correlated with a higher concentration of cAMP and a lower concentration of depressor prostaglandins. The activity of the renin-angiotensin system declined in parallel with the decrease of the blood content of cAMP.

Adaptation, Physiological↗
PubMedDate not supplied

[Thyroid and C-cell system function during prolonged rotation (morphobiochemical research)].

The thyroid and parathyroid glands of 65 Wistar rats centrifuged for 30 days at 1.1 and 2.0 G were examined histologically and biochemically. The centrifugation led to a higher activity to C-cells, an increased rate of thyro-calcitonin (TCT) synthesis and excretion, i.e. C-cell degranulation, and a significant (two-fold) increase of TCT in plasma. The stimulation effect of the TCT-producing system persisted during 7-post-rotation days and was very distinct in the animals exposed to 2.0 G. There were no morphological changes in the parathyroid glands or in the PTH concentration in the plasma.

Animals↗