[Structural-functional characteristics of cervical vessels in hypertensive patients under changed atmospheric pressure].

The ultrasonic location technique was used to measure intima-media thickness (IMT), as well as internal systolic diameter of and linear blood velocity in the cervical arteries in people with initial hypertension. Correlation analysis elicited a temporal contingency between these parameters and daily average values of atmospheric pressure. Thus, common carotid artery IMT tended to increase on high-pressure days. Besides, diameters of the common and internal carotid arteries, and vertebral artery were narrowed and, consequently, linear blood velocity in these vessels increased. This relationship is more evident in men than women and in elderly subjects than young. These results are suggestive of a vasoconstrictive action of high atmospheric pressure on these arteries. The relationship is not universal, as it is nonlinear for diameter of the internal carotid artery and inverse for the external one. This implies different sensitivity of arteries to the factor under study and possible blood redistribution in the arterial basin depending on external pressure. The relationship was observed equally on the day of investigation and previous days, which points to its temporal stability.

[Comparative analysis of gas exchange and cardiorespiratory systems reactions to increasing normobaric hypoxia and physical load of swimmers and skiers].

Qualification comparable groups of young men engaged in cyclic kinds of sports were tested with stepwise accruing loads on bicycle ergometer and 25-minute exponential increasing normobaric hypoxia to final concentration of 10% oxygen. Group of skiers, having the greatest values of the maximal oxygen consumption at muscular work, show the relaxed cardiorespiratory reactions and more falling of blood oxygen in the hypoxia. The swimmers, having restrictions of ventilatory function in the course of trainings, form preadaptation to hypoxia with changes of external respiration and gas exchange functions that allows at hypoxia to better oxygen sate the blood in lungs. The joint assessment of aerobic capacity at physical work and physiological reactions to hypoxia shows the direct relation between individual maximal oxygen consumption and the descent rate of blood oxygen saturation at accruing hypoxia that can be useful at an assessment of a sportsman functional state and its correction at training processes.

[Heliogeophysical correlates of early biodemographic variables in the south of western Siberia].

In order to verify associations between solar and geomagnetic activities and perinatal variables the monthly distributions of population characters in Novosibirsk region over the period 1980-2001 were compared by stepwise correlation analysis with monthly averaged physical parameters at lags from 0 to 10 months. Three indices used were as follows: the number of sunspots, solar flux at 10.7 cm wavelength and Ak index measured at local ionospheric station near Novosibirsk city. Official data on the number of single and multiple live births, stillbirths and infant deaths at the age under one year by the type of population and sex were provided by State Statistical Committee. All three physical parameters positively correlated with the number of single births and infant mortality rate and negatively with twin births in both populations, urban and rural, irrespective of lags. The direct association between Ak index and relative number of stillbirths in urban setting was mostly pronounced at a lag of 5 months. The number of live births increased along with Ak index due to the enhanced proportion of female births whereas the number of stillbirths after the increase in solar and geomagnetic activities elevated because of male deaths.

[Response of arterial blood haemoglobin saturation to short-term intermittent normobaric hypoxia in humans].

The paper presents experimental data supporting a hypothesis that the changes of arterial blood haemoglobin saturation during breathing the hypoxic gas mixture (10-13% O2) can be fitted by exponential function. The formal description of the saturation curves allowed verifying their stages and evaluating interindividual variability. It is suggested that the parameters of exponents can be used when estimating an individual hypoxic resistance of a human organism.

[Solar phase effect on elasticity of the brachial artery and blood flow in humans].

Single and double examinations of normal males and females in the course of 11-year solar cycle with the use of oscillovasometry and occlusive plethysmography established a direct correlation between the effective diastolic radius of the brachial artery and solar activity characteristics on the day of examination, i.e. number of solar spots and intensity of radiation with the 10.7 cm wavelength. Other blood flow parameters demonstrated opposite correlations with the factors in males and females. As solar activity increased, females displayed linear decrements of arterial elasticity and regional peripheral resistance and growth of the volumetric blood flow velocity equally at rest and at the peak of post-occlusion reactive hyperemia. In males, the correlations had the reversed sign. Besides, males were noted to reduce venous reserve and venous outflow from antebrachial muscles proportionally to the increase of Wolf number. It is inferred that elevated solar activity may be responsible for impairment of the feeling of well-being of people with reduced cardiovascular reserve, particularly in space tight or at high altitudes in the absence of or under weak protection of the geomagnetic field and ozone layer.

[Diurnal variation in glucose tolerance in rats after experimental changes in glucocorticoid rhythm]. / Sutochnye kolebaniia tolerantnosti k gliukoze u krys pri éksperimental'nom izmenenii gliukokortikoidnogo ritma.

Control rats manifested an unmarked circadian rhythm in blood sugar during evening hours. The morning-evening difference in blood sugar increased after adrenalectomy, disappeared after weekly substitution therapy with cortisol and was inverted after evening injections of cortisol to rats with intact adrenals. Evening injections of the hormone were also more efficacious from the standpoint of glucose tolerance modulation.

[Role of photoperiodicity and circadian rhythm of glucocorticoids in synchronizing the fluctuations in free-radical oxidation of lipids in rats]. / Rol' fotoperiodiki i sutochnogo ritma gliukokortikoidov v sinkhronizatsii kolebanii svobodnoradikal'nogo okisleniia lipidov u krys.

A biphasic circadian rhythm in the content of liver lipid peroxidation products has been demonstrated in male Wistar rats housed under the conditions of 12L: 12D, with 3 hours of morning and evening twilight. Maxima of the concentration of the products were observed in the morning and early at night. The rhythm of lipid anti-oxidative activity was found in an anti-phase. Inversion of both the L: D cycle and glucocorticoid circadian rhythms (cortisol injections) led after 14-16 days to the same shifts in the rhythm of anti-oxidative activity. The data indicate that glucocorticoids modulate the diurnal rhythms of lipid anti-oxidative activity and may be responsible for the shifts in the rhythms of free radical oxidation, induced by inversion of the L: D cycle.

[Circadian rhythms of 11-hydroxycorticosteroid excretion in rats administered cortisol at different times of the day]. / Sutochnye ritmy ékskretsii 11-oksikortikosteroidov u krys pri vvedenii kortizola v raznoe vremia sutok.

Male Wistar rats housed under the conditions of 12L : 12D, 24 +/- 1 degree C and free access to food and water received isotonic sodium chloride solution or cortisol in doses of 2 and 4 mg/kg, respectively. Daily stress or cortisol injections in the morning or evening are the synchronizers of 11-hydroxycorticosteroid excretion rhythm. Morning stress leads to the increase of the 12-hour rhythm. On the contrary, evening stress or cortisol administration during maximal endogenous secretion of corticosteroids are associated with the elevation of circadian periodicity. Exogenic changes in the rhythmic organization of the hypothalamo-hypophyseal-adrenocortical system are followed by activation of adaptive processes involved in the normalization of the initially modified glucocorticoid rhythm.