Biomedical subjects
Publications and source records attributed to V I Kobrin.
17-beta-estradiolsulfate (17-ES) was shown to exert a distinct vasoconstrictory effect on coronary vessels resulting in a decrease of the force contraction as well indexes of contractility. The distinct antiarrhythmic effect suggests that 17-ES possesses some properties of calcium antagonist.
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Maintenance of vertical posture is a complex coordination act dependent on a multi-level system of regulation. Functional state of the visual system may contribute significantly to the implementation of the mechanisms of vertical posture maintenance. Stabilographic examination of healthy teenagers and patients afflicted with the main CCP forms with the method of dynamic proprioceptive correction revealed dependence of posture stability and involvement of the visual analyzer on sex.
The paper presents the study concerning influence of somatosensory stimulation (single wearing of either space loading costume "PENGUIN" or its modification--"ADELY" costume) on the individual profile of interhemispheral cerebral assymmetry (IPIHCA) in patients with spastic form of infantile cerebral paralysis (ICP). The computer stabilograph analyzed motor arms' asymmetry, sensory asymmetry of visual hemiareas, asymmetry of the position of centre of gravity. It is shown that peculiarities of the realization of the standing position either with visual control or without it both in healthy individuals and in patients depended on initial IPIHCA. Initial stability was higher in healthy individuals than in patients, besides in healthy persons it was higher in right-handers while in patients--in left-handers. There was possibility of changes of both IPIHCA and stability during keeping up vertical position even during single somatosensory stimulation. For elaboration of new criteria of the estimation of the efficiency of treatment in patients with CNS damages, including ICP, it is necessary to take into consideration different influence of somatosensory stimulation on IPIHC in right-handers and left-handers.
Presented are results of the investigations of individual profiles of the brain interhemispheric asymmetry (IPIHA) in healthy grown-ups and children prior to, during, and immediately after somatosensory stimulation. The somatosensory stimulation was performed by one-time wearing of space g-loading suit PENGUIN and its modification ADELIE. IPIHA was studied by the main functional asymmetries including motor hand asymmetry, sensory asymmetry of the visual hemispheres, body mass center asymmetry (BMA) using a computerized stabilimeter indirectly measuring the muscle tone of contralateral extensor. Results demonstrate differences in IPIHA of grown-ups and children, persons with right- and left-hand motor asymmetry. It was shown that peculiar features of standing posture acquisition with and without visual control are original IPIHA and age dependent. Initial stability was higher in grown-ups than children and right-handed grown-ups and left-handed children. IPIHA and stability of the vertical posture can be modified even during single somatosensory stimulation. Unequal effects of the somatosensory stimulation on IPIHA in right- and left-handed subjects of varying age dictate the necessity to allow for these differences when assessing effects of the somatosensory stimulation in grown-ups and developing criteria of effective therapy of patients with CNS pathology, specifically, infantile cerebral paralysis.
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The paper discussed the results of stabilographic examination of the children suffered from the spastic form of child cerebral paralysis (CCP) treated by means of graded wearing of "Adel" suit which is a modification of the "Penguin" spacesuit. There has been studied the state of 30 children before treatment with the use of "Adel" suit and after the treatment as well as following the several courses of wearing the suit. Besides the patients, eleven healthy volunteer subjects (control group) were examined. There have been obtained the results pointing to the fact that in the healthy persons when they try to achieve the standing posture the leading role pertains to visual analyzer, at the same time, in the patients with spastic form of CCP the realization of standing posture depends upon the severity of the motor function disorders. When in the process of control stabilographic examination the patients suffered from spastic form of CCP demonstrate the significant role of the visual analyzer in achieving the standing posture, the use of the "Adel" suit is most desirable. The use of the "Adel" suit in the CCP patients with a decreased role of visual analyzer in achieving the standing pose as it was found under control examination enhances its significance in controlling the position of the center of gravity of the body.
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The paper presents the findings of stabiligraphic investigations of children afflicted with the hyperkinetic child's cerebral paralysis treated with the method of graduated wearing suit ADELI. This suit is a modification of space-designated PINGUIN used to counteract the adverse effect of long-term microgravity on the skeletal muscles and the skeleton. 30 children were investigated prior to, immediately after, and in a delayed period after this treatment. A group of 11 healthy volunteers were also investigated as their control. The program of investigation included routine stabilimetry, the station test, and head rolling tests. The results demonstrate that in healthy subjects the standing pose is primarily acquired and sustained by means of the visual analyzer, whereas the CCP patients pose could attain this pose with a significantly weakened control by the visual analyzer. Application of ADELI increases the role of visual analyzer in the control of standing pose. Following the treatment, the stabilimetric indices of patients changed for the better and approached those in healthy subjects.
The parameters of transmembrane potentials of cardiomyocytes and dynamics of fibrillation process have been investigated when altering the level of sympathetic action on the heart by injection of rausedile, katecholamines and by stimulation of the nucleus of hypothalamus. It was shown that the injection of rausedile decreases rest potential and potential activity, meanwhile electrical irritation significantly increases the period of spontaneously reversible fibrillation.
The microelectrode technique has shown that bonnecor given in a dose of as many as 2 mg/kg increases the action potential amplitude, but when its dose is increased up to 3 mg/kg, the agent decreases the action potential amplitude of ventricular cardiomyocytes in the guinea-pig, the resting potential remaining steady. Administration of bonnecor prevents ventricular fibrillation after aconitine application and provokes ventricular fibrillation and flutter when the focus of ectopic automatism is formed.
The duration of periods of the spontaneous reversible fibrillation of heart ventricles of different masses of guinea pigs, rabbits, pigeons and chickens was investigated. It was demonstrated, that a heart mass doesn't play an important role in the process of spontaneous heart ventricles defibrillation. Only the number of strong contacts and the level of the parasympathetic control are determined.
'Floating' microelectrodes were used to examine the transmembrane potentials of left and right ventricular cardiomyocytes in the guinea pig exposed to deep cooling. In the wide range of temperatures (37 to 20 degrees C), the transmembrane potentials did not substantially change, no fibrillation occurred. There may be a spontaneous reversible ventricular fibrillation in hypothermia where asynchronous excitation of myocardial cells occurs during cell membrane depolarization, which is essentially less than at normal body temperature.
The processes of spontaneous reversible fibrillation were compared in mature-born (guinea pigs, hens and cocks) and in immature-born animals (cats, dogs and rats). An increase in duration of the fibrillation in immature-born animals was most significant in the period of recovery of sight which is associated with an increasing parasympathetic influences.
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The enhancement of parasympathetic control in newborn and mature guinea pigs, achieved through vagal stimulation and acetylcholine administration, was shown to increase the duration of spontaneously reversible fibrillation of the heart ventricles. Acetylcholine administration could prevent spontaneously irreversible fibrillation of the heart ventricles in old animals. The preservation of sympathetic control was shown to be important for the mechanisms of spontaneous restoration of normal cardiac rhythm.
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The transmembrane potentials of the cells of the ventricle contractile myocardium of the rat and frog isolated hearts were studied as well as the strength of the ventricle contraction under the effect of a decrease (to 30 mM) or increase (up to 200 mM) in the sodium chloride concentration in the perfusate. The decrease led to a fibrillation of ventricles, 80-85% of contractile cells generating a high-frequency activity, 12-15% preserving the same AP and 3-5% having completely lost the excitability. The increase only affects the transmembrane potentials of ischemized myocardium. The decrease in the sodium concentration led to an augmentation of the contraction strength through the sodium-calcium exchange mechanism.