The functional state of the sympathoadrenal system and the autonomic regulation of the cardiac rhythm in younger schoolchildren

A comparative analysis of functional states of the sympathoadrenal system (SAS) and its reactions to isometric muscular effort was performed in seven-year-old schoolchildren of both sexes with different types of cardiac regulation. Children with a predominance of sympathetic influences displayed a higher excretion of noradrenaline and a lower excretion of dopamine than their counterparts with normal or vagal tone. A graded isometric exercise changed the functional state of the SAS in a manner dependent on the initial autonomic tone, baseline excretion of catecholamines, and sex. Boys displayed more strained reactions of the SAS than girls did, which was associated with a decrease in its reserve potential, especially pronounced in the states of vagal and normal tones. This suggests imperfect mechanisms of adaptation to static loads.     

Autonomic tone in branches of the respiratory-hemodynamic system of junior schoolchildren

Periodic variations in the cardiac, vascular, and respiratory branches of the respiratory-hemodynamic system (RHDS) were studied in children 8–11 years of age at rest using spectral analysis. By analogy with studying the autonomous regulation of the cardiac rhythm, the averaged pattern of the autonomic tone (BAT) was determined in all RHDS branches. We aimed at studying various combinations of the autonomic balance (AB) in the same pattern and identifying individual typological peculiarities of the BAT patterns of the RHDS. Groups of children with different autonomic RHDS patterns were determined using cluster analysis; these groups differed significantly in many spectral and hemodynamic parameters.     

Influence of prolonged stress on cerebral hemodynamics

The author has investigated the impact of psychological and socio-economic factors on cerebral hemodynamics and development of cerebrovascular disease (CVD). A group of 120 war sufferers with signs of post-traumatic stress disorder and adaptation disturbances, and 120 persons of the control group with no traumatic war experience have been studied. The blood flow velocity and various parameters of spectral frequency analysis have been measured, using the method of transcranial doppler sonography (TCD). A greater number of hemodynamical changes has been found in the group of subjects than in the control group (p < 0.05), in which increase of vasospasm is statistically significant probably as a result of predomination of the sympathetic system stimulation and nicotinic effect on the brain blood vessels. Flow disturbances are relatively more frequent in older subjects, which suggests the rapid development of the atherosclerotic process. The results suggest that exposure to prolonged stress and bad socio-economic factors, through different neurobiological mechanisms, increased the risk for stroke.     

Scaling vs. nonscaling methods of assessing autonomic tone in streptozotocin-induced diabetic rats

We studied heart rate variability in rats by power scaling spectral analysis (PSSA), autoregressive modeling (AR), and detrended fluctuation analysis (DFA), assessed stability by coefficient of variation between consecutive 6-h epochs, and then compared cross-correlation among techniques. These same parameters were checked from baseline conditions through acute and chronic disease states (streptozotocin-induced diabetes) followed by therapeutic intervention (insulin). Cross-correlation between methods over the entire time period was r = 0.94 (DFA and PSSA), r = 0.81 (DFA and AR), and r = 0.77 (AR and PSSA). Under baseline conditions the scaling parameter measured by DFA and PSSA and the high-frequency (HF) component measured by AR fluctuated around an average value, but these fluctuations were different for the three methods. After diabetes induction, a strong correlation was found between the HF power and the short-term scaling parameter. Despite their differences in methodology, DFA and PSSA assess changes in parasympathetic tone as detected by autoregressive modeling.     

The initial tone of arteries determines the magnitude of depressor responses caused by nitroglycerin

The correlation analysis revealed a direct (within the range 80 to 120 mm Hg) further transforming into a reverse (within the range 121 to 160 mm Hg) dependence of the blood pressure depressor shifts on the initial mean arterial pressure in anaesthetised rats. Within the physiological range of arterial pressure (70 to 130 mm Hg) there is no difference in responses to nitro-glycerine from their initial values. The mechanisms of dependence of the systemic vascular responses on initial tone of arterial vessels, are discussed.     

The effect of initial bioenergetic state on the cryostability of yeast cells

The cryostability of Saccharomyces cerevisiae cells decreased when they were cultivated under anaerobic conditions in a liquid growth medium YEPD as compared to the culture grown under aerobic conditions. The effect of cultivation conditions on the different cryostability of S. cerevisiae cells is discussed. The initial state of their bioenergetics was shown to influence the cryostability of yeast cells.     

Influence of the renal artery ostium flow diverter on hemodynamics and atherogenesis

The structure and function of the renal artery ostium flow diverter on the caudal side of the renal branch point were previously reported; in this study, we further evaluate the diverter?s possible functions. The protrusion of this structure into the abdominal aorta suggests that the diverter may preferentially direct blood flow to the renal arteries, and that it may also influence flow patterns and recirculation known to be involved in atherogenesis. Three-dimensional computational fluid dynamics (CFD) simulations of steady and pulsatile blood flow are performed to investigate the influence of diverter size and position, and vascular geometry, on the flow patterns and fluid mechanical forces in the neighborhood of the diverter. CFD results show that the flow diverter does affect the blood distribution; depending on the diverter?s position, the flow to the renal arteries may be increased or reduced. Calculated results also demonstrate the diverter?s effect on the wall shear stress (WSS) distribution, and suggest that the diverter contributes to an atherogenic environment in the abdominal aorta, while being atheroprotective in the renal arteries themselves. These results support previous clinical findings, and suggest directions for further clinical study. The results of this work have direct implications in understanding the physiological significance of the diverter, and its potential role in the pathophysiological development of atherosclerosis.     

Effects of polymodal rhythmic sensory influences on the human CNS state and autonomic functions

It was shown that polymodal rhythmic sensory influences (light, sound, vibratory-tactile), being a measure of neurocorrection, may be used for correction of the human psychophysiological state. The effectiveness of the method shows up in the positive influence on the mental sphere of a person, causing a decrease in the level of anxiety and improving the subjective well-being, and on the cognitive and autonomic functions. Polymodal rhythmic sensory influences are means of increasing the effectiveness of human intellectual activity, because it increases concentration in proportion to the increase in the parasympathetic activity induced by polymodal sensory stimuli.     

Influence of illumination on autonomic thermoregulation and choice of clothing

This study was conducted to investigate how different levels of illumination below 1,000 lx would affect the autonomic and behavioral temperature regulation of humans. Seven healthy college-aged women (20+/-0 years) volunteered to participate in this study. They were exposed to a temperature of 26 degrees C in 320 lx for 30 min ('Equilibrium') followed by 700 lx or 70 lx for 30 min (stage 1). After stage 1, they were exposed to 20 degrees C for 30 min in the same illumination as in stage 1 (stage 2). In stage 2 the subjects were instructed to select and wear the clothing they needed for their thermal comfort. The data obtained were analyzed by paired t-test and repeated measures of analysis of variance. Forearm skin blood flow tended to remain steady in 700 lx but decreased markedly in 70 lx in stage 1. There were no significant differences between subjective thermal responses of the subjects experiencing 700 lx or 70 lx in both stages although the subjects felt cooler in stage 2 than in stage 1. The subjects were likely to prefer wearing heavier clothing in 70 lx than in 700 lx. It was concluded that vasoconstriction in the upper limbs occurred more strongly in dim light, which might result in different clothing preferences in a cool environment from those associated with brighter light intensity.