PubMed Health⌕ Search

Biomedical subjects

N G Lakota

Publications and source records attributed to N G Lakota.

17 recordsLinked to original sources
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↗
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↗
PubMedDate not supplied

[Effectiveness of pharmacological preparations in physical exertion].

The effect of some drugs used as stimulants of physical performance was measured. The effectiveness was assessed in animals (mice) by means of the Kiplinger swimming procedure and in humans with the aid of the PWC170 test and physiological parameters (respiration rate, pulse rate, oxygen consumption, oxyhemogram, blood flow rate, rate of oxygen consumption by skin -- Epstein constant). Ephedrine, strychnine, indocete and eleuterococcus were used as stimulants. In animal and human experiments the best results were obtained from the use of an ephedrine-strychnine mixture; the dose for mice -- 0,03 and 0.01 mg/kg, for men -- 0.3 and 0.0015 mg/kg twice a day per os for 10-15 days.

Animals↗
PubMedDate not supplied

[Patterns in the change in the body state of dogs during a breakdown of the atmosphere regeneration system in a pressurized space].

Experiments were carried out on dogs kept in a sealed chamber. Changes in the O2 and CO2 concentrations as well as variations of physiological functions, the so-called survival curves, were studied under the conditions of terminated O2 supply and CO2 utilization. The criteria of investigation, mathematical and physiological analysis were chosen from the point of view of predicting hazardous states during failures of the environmental control system. Tolerance limits during slow and rapid changes of the environment, phases of changes of the body state and mechanisms of a combined effect of increasing hypercapnia and hypoxia were considered.

Air Conditioning↗
PubMedDate not supplied

[Effectiveness and mechanisms of the protective action of sidnocarb in experimental weightlessness and cooling].

Twenty-one subjects took part in experiments with acute cooling (maximally allowable time for swimming in ice-cold water and two-day exposure to winter field conditions) or two-day exposure to microgravity (simulated by water immersion). They were divided into a placebo group (5, 5 and 6 man-exposures) and a sydnocarb group (6, 6 and 4 man-exposures) and examined by biochemical, radioimmune and radioligand methods. It was found that physiological responses to cold and microgravity effects as well as sydnocarb were similar. During cold exposures the thermal steady-state was achieved by taking maximum daily doses of the drug. In thermoneutral water immersion body temperature fall was controlled by therapeutic doses of the drug. Body temperature decline beginning with immersion day 2 can be related to the endogenous decline of heat production due to a new functioning level which is well known in gravitational physiology, i. e. this is the effect of microgravity per se. With respect to old and new information about the pharmacological properties of sydnocarb, mechanisms of its high thermoregulatory effects on CNS structures responsible for heat production and heat loss are discussed.

Body Temperature Regulation↗
PubMedDate not supplied

[Activity of the sympathetico-adrenal system in humans during modeling of weightlessness].

The state of the sympathico-adrenal system (SAS) before and during three days of suited immersion was investigated in six male subjects on the basis of renal excretion of adrenaline (A), noradrenaline (NA), dopamine (DA) and DOPA according to Vasilyev. Computer-aided analysis of the experimental data by the method of principal components showed that the SAS was functionally stressed in all subjects. Suited immersion that simulated hemodynamic, metabolic and vestibulo-motor effects of microgravity helped to distinguish between men with sustained and lowered capabilities of the SAS which are largely determined by the A-, NA-, and mixed type of its function. Clinical manifestations of A-crises in all subjects pointed to central genesis of SAS reactions to simulated microgravity. A correlation between the decline of SAS reserve capabilities and the level of the vestibulo-autonomic syndrome during suited immersion as well as drastic decrease of physical work capacity after immersion was established. It is emphasized that correction of unstable states of the SAS functional activity acquires special importance.

Adrenal Glands↗
PubMedDate not supplied

[Pharmacologic correction of the effect of cold on man].

The effect of pharmacological stimulants and prescriptions on the thermal status of man and their possible use to extend the exposure to the cold environment were investigated. The effectiveness of the following drugs and prescriptions was assessed: sydnocarb, phenamine, indopan; glutamic acid + lagochilus + ephedrine; sydnocarb + glutamic acid (sydnogluton); ephedrine + glutamic acid + strychnine. The test subjects were kept in air (in a thermal chamber) at -20 degrees C or in water at 0 to 2.5 degrees C (resting or swimming). The most effective treatment was provided by sydnocarb (effective doses were 10 mg X 2 or 30 mg X 5 in air or water, respectively) and sydnogluton (sydnocarb 30 mg + glutamic acid 0.25 g X 5 in cold water). When compared to placebo, sydnocarb (or sydnogluton) assured better thermal parameters of the body in cold water and longer (by 2-6 hrs) exposure which increased to 20 hrs.

Amphetamine↗
PubMedDate not supplied

[Comparative effectiveness of different biologically active compounds during physical loading].

Over 30 drugs and recipes were assessed in 440 provocative bicycle ergometry tests (PWC170) and individual tolerance (IT) tests proposed by the authors in which 63 healthy volunteers participated. In the study the IT test was physiologically substantiated, and performance evaluation based on PWC170, when heart rate influencing drugs were taken, was shown to be incorrect. In the course of normal and forced breathing (gas exchange measurements) quantitative variations of PWC170 were recorded. On the basis of the study the combination of the two tests, having criterion properties and subjected to the rank evaluation, can be recommended as a method for determining physical work capacity and testing drug efficiency. During an exposure to adverse environments or functional, humoral or integrative stresses the following drugs can be prescribed: drugs classified as adaptogens of the USSR flora; multicomponent tonic recipes, containing aminoacids, metabolites, adaptogens, vitamins and metal compounds: recipes containing aminoacids and anabolics as well as low doses of CNS stimulants. It is suggested that pretreatment with aminoacids and anabolics assuring the basal energy potential enhances the effective influence of stimulants on the energy forming capacity and neuromuscular function without nerve cell breakdown in cases of extremely heavy loads and ensuing fatigue.

Adult↗
PubMedDate not supplied

[The stabilization of heat maintenance in the human body by administering sydnogluton].

Sydnocarb plus glutamic acid (sydnogluton) was given in doses from mean therapeutical to large daily doses to volunteers during exercises under the conditions of experimental microgravitation and cold exposures. Clinical and physiological findings, thermo- and spirometric evidence, and biochemical and radioimmunoassays led the authors to the conclusion that sydnogluton showed psychostimulating, thermogenic, and actoprotective effects.

Body Temperature Regulation↗
PubMedDate not supplied

[Functional changes of the cardiovascular system and their pharmacological correction during suited immersion].

In the course of 126 man/exposures of 3 hours to 3 days in duration, in which 39 test subjects took part, circulation responses to the upright and supine body position during suited immersion as well as orthostatic and exercise tolerance after immersion were investigated. During 24 man/exposures for 2 days the subjects were administered per os placebo or one of the four neurotrophic drugs: sydnocarb, sydnogluton, sydstrigluton, estrigluton. Clinical observations, instrumented data and methodical features of the immersion model used give evidence that the suited immersion has advantages over currently used procedures simulating the effects of hypogravity. The drugs allowed cardiovascular correction that increased aerobic capacity of the body and enhanced cardiovascular orthostatic and exercise tolerance.

Cardiovascular Diseases↗