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Introduction. In recent years, there has been evidence not only of the widespread prevalence of the obstructive sleep apnea (OSA) in the population, but also of the progression of the disease in the dynamic follow-up of patients. The purpose of this review article is to analyze the current state of etiopathogenesis, clinics of obstructive sleep apnea and to identify more promising treatment approaches and risk factors for its development. Materials and methods. The analysis of publications was performed for the period 2016-2021 on the basis of data from Elibrary, the Federal Electronic Medical Library of the Ministry of Health of the Russian Federation, the bibliographic database of medical publications MEDLINE, created by the US National Library of Medicine. Sixty-one sources were selected for the review. Results and discussion. Obstructive sleep apnea is widely represented in the group of sleep disorders and is correlated with a number of clinical conditions: cardiovascular diseases (acute cerebrovascular disease, resistant arterial hypertension, coronary heart disease, heart rhythm disorder), endocrine system (diabetes mellitus, hypothyroidism, metabolic syndrome, obesity), ophthalmological pathology (neurooptikopathies), sudden death, etc. Severe daytime sleepiness due to OSA is not only a medical but also a social problem due to increased injury rates, accidents at work and on the road, and decreased labor productivity. Conclusion. The introduction of a comprehensive interdisciplinary approach to diagnostic standards will improve the detection and treatment of obstructive sleep apnea and improve the quality of life of patients. Change of lifestyle and use of PAP-therapy in patients with OSA is currently the most adequate direction in the treatment of this pathology. High prevalence, serious consequences for the nation's health and economy dictate the need for further study of markers of this disease for early prediction and primary prevention of cardiovascular diseases and diseases associated with obstructive sleep apnea.

The aim: to study the peculiarities of central hemodynamics and erythrocyte parameters under the influence of extreme occupational factors in firefighters with different lifetimes in the Federal Fire Service (FPS) of the Ministry of Emergency Measures for the Tver Region. Methods: 240 firefighters (age 25-47 years) were divided into three groups depending on the length of service: 1-6, 7-15, 16-25 years. Parameters of central hemodynamics were determined at the beginning of the working day shift according to the method of tetrapolar thoracic rheography. The absolute content of red blood cells in capillary blood was counted using a blood analyzer. Special techniques were used to determine deformability of their membrane. Results: most hemodynamic parameters deviated from the statutory values in the first group in comparison with other groups. This was regarded as an imbalance between the volume-time indeces of the blood circulation and the organism's needs under conditions of extreme occupational stress. Gradual formation of an adequate hemodynamic profile was detected with an increase in the length of service. This allows us to conclude about the mobile and reactive nature of hemodynamic changes in the body. Expressed hematologic changes, manifested in a decrease in the erythrocyte membrane deformability and increase in its rigidity, were found in the third group. The observed patterns at the last stage of the service probably reflect the conservative nature of negative shifts development. Conclusion: comparison of the dynamics of physiological changes in firefighters-rescuers of three groups with different service life in the Ministry of Emergency Measures revealed the reactive nature of hemodynamic changes and the conservative nature of hematological manifestations.

The emotional state of a person affects both the central level and the peripheral indices of the autonomic nervous system, particularly those of the regulation of the heart rate. Our study showed that boys with a higher level of anxiety had higher values of the latent period of the P300 evoked potential and lower indices of short-term auditory memory. Changes in the temporal and spectral components of heart rate variability under the conditions of mental workload indicate that the neurohumoral regulation of the heart rate is shifted toward the suprasegmental influences, including pituitary–hypothalamic and cortical influences.

240 hot papas (age 25-47 years) took part in the research. They were divided into three groups depending on the length of service: 1-6, 7-15, 16-25 years. Red blood cells parameters were examined by means of the blood analyzer "Micros-60 OT", membrane deformability and osmotic fragility were determined according to special techniques at the beginning and at the end of the daily shift. The morphometric parameters of hot papas' erythrocytes corresponded to normal values. The workload during the day did not lead to their significant shifts except anisocytosis in the group with work experience of 16-25 years. The influence of service duration on increase of red blood cell heterogeneity, a reduction in their total number and Hb level was found in the same group. At the beginning of the shift the membrane deformability and osmotic fragility in 0.45 % NaCl solution were significantly lower in all surveyed groups than in the control group. The average values of these parameters increased in all groups by end of the shift. However, the control group values were not achieved.

This review presents modern data on the biorhythms of cardiac activity in healthy individuals and pathological conditions. The article presents the changes in the indices of the cardiovascular system during the day. There are diurnal patterns in changes of heart rate. As in healthy persons and in patients suffering from arterial hypertension bimodality circadian rhythm of blood pressure was revealed. It is emphasized that circadian fluctuations in blood pressure may be associated with the participation of melatonin in the regulation of this indicator of cardiovascular activity. In healthy people circadian fluctuations of intervals duration and the height of ECG waves have been revealed. The people belonging to a certain chronotype influence diurnal variations of indicators of heart rate variability. The results of seasonal fluctuations of indicators of cardiac activity as well as the analysis of the frequency of disease recurrence in different periods of the year, the seasons and during the day are presented. The article describes research data on the effect of natural abiotic stress factors - geomagnetic disturbances on chronostructure biorhythms of the heart. The changes in blood pressure and heart rate in the voltage amplification of the magnetic field of the Earth have been covered. The statistical data proving connection between the heliogeomagnetic activity and an increase in the number cardiovascular accidents have been presented. Using the basic regularities of chronobiology allows us to predict the risk of developing various diseases, primarily cardiovascular diseases, which are the main reason of mortality in the world.

The article compares different authors' methods of diagnosis of connective tissue dysplasia in children on the basis of phenotypic and visceral markers. The benign joint hypermobility syndrome in children of different ages in Tver was diagnosed using the Beighton method: it was detected in 71% of children under 7 years old and in 31.1% of older children. The benign joint hypermobility syndrome is typical of practically all children from 3 to 4 years old and of the majority of children from 5 to 7 years old, which indicates that increased flexibility is a physiologic standard for this age and that the Beighton method does not detect accurately the abnormality of connective tissue in children under 7 years old. 120 children have been examined for presence and severity of connective tissue dysplasia using three different ways at the same time and also using different authors' methods and diagnostic tables. The method of T.I. Cadurina detects presence of connective tissue dysplasia 1.5 times more often than the methods of T. Milkowska-Dimitrova and A. Karkashov. The results when using the method of L.N. Abbakumova are in between. The conclusion of the article shows that diagnosis of connective tissue dysplasia in children cannot be based only on identification of the benign joint hypermobility syndrome, and the methods of diagnosis of connective tissue pathology taking into account not only external but also internal markers are more accurate. Common methods of calculating frequency of connective tissue pathology in children must be applied in all regions of our country.

Experiments in cats revealed a clear-cut dependence of the early complex (up to 100 msec) of evoked potentials recorded in the caudate nucleus and temporal cortex on biological relevance of the stimulus (presence or absence of alimentary signal), with constant physical parameters. The early complex of evoked potentials can reflect activity of the mechanisms preventing non-specific motor response to exteroceptive stimulus, although it does not exclude processing the stimulus-carried information during generation of evoked potentials.

Aim : To assess the frequency of occurrence and the intensity of hypermobility of joints in children and teenagers of Tver in comparison with other regions of the Russian Federation. Patients and methods : 564 children and teenagers at the age from 3 to 17 years were examined. The presence of hypermobility of joints was determined by Beighton method. Anthropometrical measurements were taken, physical development of children was assessed. Results : The hypermobility of joints is characteristic practically for all children at the age of 3–4 years and most of children of 5–7 years. On average it meets in 71% of children of a preschool age and 31% of school students of Tver, making 35–40% in children of midchildhood; it is noted in every fourth child of 13–15 years and every tenth 16–17-year-old teenager. The hypermobility of joints of girls is 20% more than of boys. The high-grade hypermobility is characteristic for tall and thin teenagers; in midchildhood the children who in comparison with agemates are smaller in growth and weight are more flexible. The article presents the comparison of own data with the results of other similar researches. Conclusion : The frequency of occurrence of hypermobility of joints considerably differs in different age groups of children. The increased flexibility is physiological norm for the majority of preschool children, further it decreases in direct ratio to the age of a child.

In 27 men who had undergone chronic intoxication with carbon disulfide, the shock ejection, heart rate, minute blood volume, phase analysis of left ventricular systole were examined; the amplitude-time parameters were determined: the rate of cardiac output, the rate of pressure rise and the rate of cardiac relaxation. The parameters of hemodynamics at rest and their change in response to increasing static strengthening of the right hand were studied. The most informative parameters for detecting heart failure in chronic carbon disulfide intoxication were amplitude-time parameters.