Biomedical subjects

L Ksinantova

Publications and source records attributed to L Ksinantova.

8 recordsLinked to original sources

PubMed2003

The response of endocrine system to stress loads during space flight in human subject.

The responses of endocrine system to the exposure to stress-work load and hormonal changes during oral glucose tolerance tests were studied in the Slovak astronaut before (three weeks before flight), during (on the 4th and the 6th days of space flight), and after space flight (1-3 days and 15-17 days after space flight) on board of space station MIR. Blood samples during the tests were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Preflight workload produced an increase of plasma norepinephrine and a moderate elevation of epinephrine levels. Plasma levels of insulin, growth hormone, prolactin and cortisol were not markedly changed immediately or 10 min after the end of work load. The higher increases of plasma growth hormone, prolactin and catecholamine levels were noted after workload during space flight as compared to preflight response. The higher plasma glucose and insulin levels were noted during the oral glucose tolerance test in space flight and also in the post flight period. Plasma epinephrine levels were slightly decreasing during glucose tolerance test; however, plasma norepinephrine levels were not changed. The similar patterns of catecholamine levels during glucose tolerance test were found when compared the preflight, in-flight and post flight values. These data demonstrate the changes of the dynamic responses of endocrine system to stress-work and metabolic loads during space flight in human subject.

Adaptation, Physiological↗

PubMed2003

Thyroid function and cholesterol level: paradoxical findings in large groups of population with high cholesterol food intake.

OBJECTIVE: To compare the levels of serum cholesterol with thyroid function as estimated by the level of thyrotropin and free thyroxine with possible participation of thyroperoxidase antibodies in large number of adults examined within large field surveys focused on the evaluation of thyroid status of Slovak rural population. SUBJECTS AND METHODS: Serum level of cholesterol and thyrotropin (TSH) was estimated in a total of 2786 adults. In addition, in 2038 of them also the level of free thyroxine (FT4), total triiodothyronine (TT3), cholesterol, triglycerides and phospholipids was measured. The levels of TSH, anti-TPO and FT4 were estimated by supersensitive electrochemiluminiscent immunoassay using the automatic system Elecsys (Roche, Switzerland). RESULTS: A total of 2786 adults was stratified into 7 groups according to the range of TSH level as related to generally recognized level of thyroid function, e.g. 1. TSH <0.10 mU/L (overt hyperthyroidism, N=41), 2. TSH 0.11-0.30 mU/L (overt or subclinical hyperthyroidism, N=149), 3. TSH 0.31-2.50 mU/L (normal level, N=1750), 4. TSH 2.51-4.50 ("high normal" level, N=607), 5 TSH 4.51-6.50 (mild or incipient subclinical hypothyroidism, N=137), 6. TSH 6.51-10.00 mU/L (mild hypothyroidism, N=50), 7. TSH 10.01-99.00 mU/L (severe hypothyroidism, N=53). The average levels of cholesterol in all groups were very similar ranging from 5.53 to 6.17 mmol/L and no interrelations with TSH level were found. In addition, no considerable differences between these groups were found when considering the levels of medians, upper quartiles and 90th percentiles of individual groups. When male and female subjects were divided into age groups according to the decades, an age dependent increase of cholesterol level was found in both sexes. The fraction of 2038 subjects was divided into the same TSH related groups as defined above. Similarly as above, no considerable differences in cholesterol, triglycerides and phospholipids level were observed. However, the levels of FT4 and TT3 were significantly decreasing with the increase of TSH level which confirmed the continuing decrease of thyroid function. The frequency of positive anti-TPO in subjects with TSH >6.5 mU/l (71/86 = 82.5%) was significantly higher than that in subjects with TSH <6.5 mU/l (468/1952 = 23.9%). CONCLUSIONS: No difference in the level of cholesterol and triglycerides was found in large groups of rural adults from Slovakia with various thyroid function as estimated by the level of TSH, FT4, TT3 and anti-TPO. It is assumed that this interrelation resulted from very high cholesterol intake due to inappropriate general nutritional status of rural population resulting from the consumption of unhealthy foods.

Adult↗

PubMed2002

Effect of simulated microgravity on endocrine response to insulin-induced hypoglycemia in physically fit men.

Adaptation to microgravity is associated with alteration in some endocrine functions. In the present longitudinal study, the counterregulatory hormonal response to insulin-induced hypoglycemia (ITT, 0.1 IU/kg short acting insulin i. v.) was evaluated under simulated microgravity conditions in 15 physically fit subjects. ITT was performed at the beginning of the investigation, and again after completion of 6 weeks of endurance training and after a subsequent period of 4 days of head-down bed rest at a backward tilt of 6 degrees from the horizontal. Endurance training showed a significant increase in maximal aerobic capacity in previously well-trained subjects (increase by 12 %), as well as on attenuation of counterregulatory response of epinephrine to hypoglycemia. After 4 days of bed rest, basal concentrations of plasma norepinephrine was diminished (p < 0.002) and plasma renin activity was enhanced (p < 0.02). After bed rest, decreased responses of the two catecholamines (norepinephrine, p < 0.001; epinephrine, p < 0.001), growth hormone (p < 0.001), and cortisol (p < 0.05) were observed. Response of plasma renin activity after bed rest was increased (p < 0.01). This longitudinal study indicated that 4 days of bed rest in endurance-trained subjects induced increased response of PRA to hypoglycemia and attenuation of other counterregulatory neuroendocrine responses.

Adult↗

PubMed2002

Hyperprolactinemia does not influence hypothalamic-pituitary-adrenocortical function during hypoglycemia in women.

Elevated plasma prolactin and mild hypocortisolemia have been observed in patients with rheumatic disorders. This study was designed to assess the potential inhibitory effect of hyperprolactinemia on hypothalamic-pituitary-adrenocortical function. Hypoglycemia was induced by intravenous insulin injection (0.1 IU/kg) in 10 female volunteers of fertile age during their follicular phase twice: 60 min after either domperidone (10 mg orally) or placebo administration. Blood samples were collected from an indwelling catheter inserted into the cubital vein at -60, 0, 30, 45, 60 and 90 min. The concentrations of prolactin, adrenocorticotropic hormone (ACTH), cortisol, epinephrine, norepinephrine and glucose were measured in plasma. Domperidone administration significantly increased plasma prolactin concentrations (71 +/- 11 ng/ml vs. 14 +/- 6 ng/ml; p <0.001), while basal plasma concentrations of ACTH, cortisol, norepinephrine and epinephrine were unaffected. Insulin-induced hypoglycemia resulted in a significant rise in the mean plasma ACTH levels from 10 +/- 1 pg/ml (domperidone) and 11 +/- 1 pg/ml (controls) to 148 +/- 19 pg/ml (domperidone) and 139 +/- 12 pg/ml (controls) at 45 min (p < 0.001), in plasma cortisol from 407 +/- 62 nmol/l (domperidone) and 391 +/- 42 nmol/l (controls) to 925 +/- 60 nmol/l (domperidone) and 810 +/- 52 nmol/l (controls) at 60 min (p < 0.001), and in plasma epinephrine from 40 +/- 26 pg/ml (domperidone) and 16 +/- 3 pg/ml (controls) to 274 +/- 55 pg/ml (domperidone) and 352 +/- 61 pg/ml (controls) at 30 min; (p < 0.001). The significant increase in ACTH, cortisol and epinephrine responses to hypoglycemia was similar in both groups. We observed mild norepinephrine response to hypoglycemia but this was irrespective of the medication. In conclusion, pharmacologically-induced hyperprolactinemia did not induce significant changes of hypothalamic-pituitary-adrenocortical function and did not influence sympathoadrenal activity in healthy young women.

Adrenal Cortex↗

PubMed2002

Responses of sympathoadrenal and renin angiotensin systems to stress stimuli in humans during real and simulated microgravity.

Changes of plasma hormone levels were investigated in human subjects after exposure to physical exercise (WL) and insulin induced hypoglycemia (ITT) during space flight or after head down bed rest (HDBR). Exaggerated responses of plasma epinephrine (EPI), norepinephrine (NE) and aldosterone (ALD) were observed after WL during space flight as compared to preflight response. Hypoglycemia during space flight induced attenuated responses of EPI, NE and augmented response of ALD. Exposure to WL during HDBR was followed by significantly exaggerated responses of plasma EPI, NE, ALD, PRA and cortisol. In HDBR the responses of plasma EPI, NE and cortisol were reduced and PRA response was exaggerated during ITT. These data indicate that hormonal responses to ITT and WL are similar at real and simulated microgravity.

Comparative Study↗

PubMed2001

Effect of microgravity on plasma catecholamine responses to stressors during space flight.

The effect of microgravity on the sympathicoadrenal system (SAS) activity in humans and animals has not yet been clarified. Our previous studies suggested that the SAS activity, evaluated by circulating and/or urinary catecholamine (CA) levels in astronauts during space flights, was found to be rather unchanged. However, CA levels were measured in astronauts only at rest conditions. The aim of the present study was to investigate effect of microgravity during space flight and post-flight readaptation on responsiveness of the SAS to somatic and psychic stressors evaluated by levels of catecholamines and their metabolite in the blood of the Slovak cosmonaut during his stay on board the space station Mir.

Adaptation, Physiological↗

PubMed2001

Plasma hormone levels in human subject during stress loads in microgravity and at readaptation to Earth's gravity.

In great part of the investigations of endocrine system functions in astronauts during space flights the plasma levels of hormones and metabolites were determined only in resting conditions, usually from one blood sample collection. Such levels reflected the psychical and physical state and new hormonal homeostasis of organism at the time of blood collection, however, the functional capacity of neuroendocrine system to respond to various stress stimuli during space flight remained unknown. The aim of present investigations was to study dynamic changes of hormone levels during the stress and metabolic loads (insulin induced hypoglycemia, physical exercise and oral glucose tolerance test) at the exposure of human subject to microgravity on the space station MIR. The responses of sympatico-adrenomedullary system to these stress and workloads were presented by Kvetnansky et al.

Adaptation, Physiological↗

PubMed2000

Changes of serum TSH level during oral glucose tolerance test: comparison of morning and evening test with plain circadian TSH rhythm.

OBJECTIVE: To compare the changes of TSH level in serum during oral glucose tolerance test (OGTT) with those resulting from a plain circadian rhythm and, in addition, to compare such changes between the morning and evening hours. METHODS: Oral glucose tolerance tests were performed in groups of 8-20 adults after the oral administration of glucose (75 g in 400 ml tap water) at 8.00, 10.00 and 20.00 h. Blood samples for the estimation of TSH (supersensitive IRMA method) were taken in 30 min intervals for following 3 hours. In the same groups of subjects the blood samples were obtained between 8.00 and 13.00 h or between 20.00 and 23.00 h one week later for the assessment of plain circadian rhythm of TSH levels. RESULTS: The level of TSH in a group subjected to OGTT at 8.00 h was significantly decreased (P<0.05) between 8.30 and 10.30 h, i.e. 30-150 min after glucose administration which was parallel to the circadian decrease found in the same subjects. However, this was followed by an increase of TSH up to the original level reached at 11.00 h which was contrasting to a circadian decrease. Similar pattern was found also when OGTT was started at 10.00 h. In a group subjected to the evening OGTT at 20.00 h similar decrease of TSH level was found at 21.00 h which was contrasting to the circadian increase. However, this was followed by a remarkable increase of TSH level between 21.00 and 23.00 h which was parallel to the circadian trend, but much more abrupt than that found without the previous administration of glucose. CONCLUSIONS: In both the morning and evening OGTT a decrease of TSH level was found between 30 and 90 min after glucose administration which was followed by an increase between 90 and 180 min after that. The decrease during the morning test was parallel to the circadian trend, while the increase was opposite to that. However, an inverse figure was found in the evening test, the decrease of TSH being opposite and following increase being parallel to the circadian trend.

Adult↗