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We studied the dependence of parameters of lung volumes and the elastic properties of the lungs on changes in the central hemodynamics occurring in the initial period of passive postural changes in cats. It was found that transition from the horizontal to head-up and head-down tilting was accompanied by opposite hemodynamic changes in the cranial and caudal parts of the body. Changes in lung compliance and functional residual capacity of the lungs were opposite and linearly depended on the intensity of hemodynamic shifts, which indicates passive character of the primary disorders primarily determined by a physical factor, gravity-dependent redistribution of body fluids.

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The effect of head-down tilt on respiration and diaphragmal and parasternal muscles activity was investigated in 11 healthy subjects. The short-time (30 min) head-down tilt posture (-30 degrees relatively horizont) increased the inspiratory time (P < 0.05), decreased breathing frequency (P < 0.05), inspiratory and expiratory flow rate (P < 0.05) and increased the airway resistance (P < 0.05) compared with values in vertical posture. There were no significant changes in tidal volume and minute ventilation. Constant values of tidal volume and minute ventilation during head-down tilt were provided by increasing in EMG activity of parasternal muscles more then twice. It was established that the contribution of chest wall inspiratory muscles increased while the diaphragm's contribution decreased during head-down spontaneous breathing. Maximal inspiratory effort (Muller's maneuver) during head-down tilt evoked the opposite EMG-activity pattern: the contribution of inspiratory thoracic muscles was decreased and diaphragm's EMG-activity was increased compared with vertical posture. These results suggest that coordinate modulations in inspiratory muscles activity allows to preserve the functional possibility of human inspiratory muscles during short-time head-down tilt.

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The possibility of using intermittent hypoxic training for stimulation of physiological mechanisms underlying the compensatory hemodynamic reactions to orthostatic load was studied in animal experiments. Intermittent hypoxic training had a favorable impact on circulatory reactions, which manifested in stabilization of blood pressure and heart filling pressure and in a decrease in orthostatic hypotension during the initial period of orthostasis. We hypothesized that the positive effect of intermittent hypoxic training on the correction of negative hemodynamic shifts is determined by the training effect aimed at the increase in the vascular tone and venous return to the heart. These results can serve as validation for preventive use of intermittent hypoxic training for reducing blood draining in the lower part of the body, correction of the compensatory orthostatic reaction of the circulatory system, and hence, for improvement of orthostatic resistance.

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Assessment of immunity to poliomyelitis in adults from 8 towns of Moscow region was conducted. Low levels of population immunity against some serotypes of poliovirus in several towns have been found. At the same time, these levels were high and very high in other towns. Measurement of levels of strain-specific antibodies to vaccine and wild polioviruses demonstrated wide circulation of wild polioviruses during past decades which had significant influence on formation of immunity. Substantial number of non-immune adults represents favorable conditions for circulation of vaccine polioviruses after cessation of vaccination, which, in its turn, could result in reestablishment of their neurovirulent properties and subsequent reemergence of poliomyelitis.

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Collective poliomyelitis immunity was studied in 6339 donors from 19 towns and cities of Russia. Its stress substantially varied in different towns and cities. Studies of strain-specific antibodies to vaccine and wild viruses of poliomyelitis in donors from 4 towns established that the immune persons were more in the town where wild polioviruses had previously circulated than in those where the circulation of wild polioviruses had been limited and immunity resulted from vaccination. Circulation of vaccine viruses and reversion of their neurovirulent properties should be expected in the town where there are low collective poliomyelitis immunity rates. It is concluded that it is impossible to eradicate poliomyelitis as infection today; it is possible only to eliminate the disease if further vaccination of children is performed with live poliomyelitis vaccine.

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Cardiorespiratory responses induced by upright tilt before and after intermittent hypoxia during head-down tilt, were investigated in rabbits. Arterial blood pressure, heart rate, central venous pressure, transmural filling pressure of the heart (calculated as the product of esophageal and central venous pressure), breathing frequency, esophageal pressure were measured in supine (baseline), head-down and upright posture. Our results indicate a reduction in orthostatic responses in cardiovascular system after intermittent hypoxia.

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In ground-based model of the hemodynamics effects of weightlessness, the intersystem relation of breathing and circulation was investigated during inspiration and expiration separately in anesthetized catz. It's shown that the dynamics of central venous pressure, esophageal pressure and filling pressure of the heart during inspiration in supine and head-down tilt position has obvious similarity to those which hypothetically can be present in microgravity. The results suggest that intrathoracic hemodynamics during inspiration in supine and head-down position may be an adequate ground model for investigation of weightlessness influences on intrathoracic circulation.

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The aim of this study was the search of association with diabetic polyneuropathy of the polymorphic markers epsilon2/epsilon3/epsilon4 of apolipoprotein E (APOE) and I/D of apolipoprotein B (APOB) genes in groups of type 1 diabetes patients with diabetic polyneuropathy (n = 86) and without its clinical signs (n = 94). We have not found significant association with diabetic polyneuropathy (DPN) of epsilon2/epsilon3/epsilon4 marker of APOE gene. However the comparison of allele and genotype frequencies of I/D marker of APOB gene showed that the carriers of I allele and II genotype had higher risk (OR = 1.66 and 2.01, relatively; p < 0.027), whereas the carriers of D allele had lower risk of DPN (OR = 0.60; p < 0.018). Our findings show that APOB gene, encoding one of the main components of lipid metabolism system, is involved into the diabetic polyneuropathy development in type 1 diabetes mellitus.

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Essential differences in the intensity of collective immunity to poliomyelitis in the donors of Moscow and Kaluga were established. To find out the nature of high characteristics of collective immunity to poliovirus, types 1 and 2, in the donors of Kaluga, strain-specific antibodies to wild and vaccine polioviruses were studied. In a considerable number of donors strain-specific antibodies to poliovirus, types 1 and 2, were detected. This made it possible to presume a sufficiently wide circulation of these viruses among the population of the city in the middle of the 20th century and, as a consequence, high level of collective immunity appeared. Strain-specific antibodies to poliovirus of type 3 were rarely detected. This made it possible to suggest that the circulation of viruses of this type among the population was limited. Immunity to viruses of this type was due only to immunization. For this reason the characteristics of collective immunity in the donors of Moscow and Kaluga coincided. The detection of strain-specific antibodies to poliomyelitis virus allowed to retrospectively form the opinion of the spread and time of the circulation of wild poliomyelitis viruses in the population.

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The focus was placed on the physiological mechanisms of correction of the blood redistribution during the head-down tilt (HDT) with a discrete or complex use of the methods of negative pressure respiration (NPR) and lower body negative pressure (LBNP). It was evidenced that rise in the intracranial hydrostatic pressure in HDT (-6 degrees) can be compensated by NPR within a range of -10 to -15 cm of water column causing decrease in the intrasternal pressure from -5.04 to -7.74 cm w.c. Bioimpedance and ultrasonic investigations led to the conclusion that the decreased transpulmonary pressure is responsible for blood outflow from the intracranial venous system till the level adequate to the horizontal position of the body. The results were verified in experiments with unconscious cats: pressure in the exterior jugular vein and v. cava superior during HDT (-30 degrees) with NRP at -5 cm w.c. decreased by 3.2. and 4.3. w.c., respectively. Experiments with human subjects also demonstrated that the complex use of NPR and LBNP produces an additive hemodynamic effect and can be considered a new method for correcting the adverse consequences of redistribution of the local blood volumes toward the head end.

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Changes in the ratio between intrathoracic and central venous pressure were studied in narcotized cats under conditions of constant positive or negative pressure ventilation. Transformation of elastic characteristics in the respiratory system caused by changes in intrathoracic pressure led to inversion of the ratio between transpulmonary intrathoracic and central venous pressure determining right atrial filling pressure.

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Immunity induced by immunization with oral poliomyelitis vaccine has long been considered to last for life, similarly to immunity developing after infection with wild poliomyelitis virus. Vaccine virus cannot circulate among the immune population for a long time. The vaccination of children against poliomyelitis, carried out in the course of many years, has made it possible to suggest that a considerable number of immune persons were present among the adult population. The examination of 1,030 Moscow donors has revealed that antibodies to poliomyelitis virus of types 1, 2 and 3 were detected in 47.3%, 45.5% and 76.4% of the examinees respectively, the values of the average geometric titers being low. It is known that passages of poliomyelitis vaccine virus through nonimmune persons may result in emergence of revertant viruses with increased neurovirulence. The nonimmune adult population, especially the mothers of vaccinated and revaccinated children, may serve as favorable environment for the circulation of vaccine viruses and the appearance of revertant viruses.

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To improve methods of offsetting the hemodynamic shifts in microgravity, applicability of breathing at negative pressure (BNP, pressure relief by -5.0 cm of water column) during inspiration and expiration was assessed in acute experiments with unconscious cats tilted head-down (-30 degrees). Direct measurement of pressure in v. cava superior and v. jugularis externa using a catheter revealed a concurrent significant (p < 0.05) growth of the parameter which should be considered a sign of impeded venous outflow from the craniocervical vessels. BNP added to the sucking effect of the thoracic cavity (the siphoning effect) and led to more massive venous outflow from cephalic vessels as evidenced by pressure drop in the jugular vein and v. cava superior to the values determined in the basic horizontal position. However, BNP did not significantly alter arterial hemodynamics, respiration pattern or gas exchange. Data of the investigation attest effectiveness of this method of moderating blood flow to the cat's head during HDT and possibility to apply it in the zero-g environment.

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In anaesthetised cats, antiorthostatic posture of the body with an inclination angle of 30 degrees increased pressure in the vena cava superior and in jugular vein. The rest of the cardio-respiratory parameters were changed insignificantly. Physical and physiological mechanisms of the blood regional redistribution in alteration of the body gravitation orientation, are discussed.

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In response to vaccination or infection with wild poliovirus, some children can finely differentiate the virus structure and respond by forming strain-specific antibodies. The analysis of strain-specific antibodies indicates that in epidemically unfavorable regions strain-specific antibodies to wild poliovirus strains may prevail over those to vaccine poliovirus strains in children or occur with equal frequency. In epidemically favourable regions strain-specific antibodies to vaccine poliovirus strain significantly prevail in children or may be absent at all. The analysis of strain-specific antibodies makes it possible to retrospectively judge on the circulation of wild viruses in the surveyed region.

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Eleven neonatal cotton rats were infected with Coxsackie B3 viruses, 9 animals served as controls. The course of the disease was followed for 44 to 154 days. Electro- and phonocardiography, two-dimensional Doppler echocardiography, morphological and histological studies were performed in the experiment. All the histologically examined infected rats were found to develop myocarditis, whereas 75% of the animals had valvulitis. The total number of the afflicted values was 10, out of them the mitral, tricuspid, and pulmonary trunk valves accounted for 40, 40, and 20%, respectively. Doppler echocardiography revealed organic mitral and tricuspid insufficiencies in the outcome of valvulitis induced by Coxsackie B3 viruses due to the impairment of valvular cusp.

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