[Regurgitation and motor reactions in infants]. / Srygivanie i dvigatel'nye reaktsii u detei rannego vozrasta.

An interrelationship of regurgitation and a motor reaction (MR) of the type of a shudder was revealed in infants. A jerking motor activity occurred in lower rate of respiration and decrease of its amplitude. The muscles of respiration are also involved in the activity in this case, which leads at first to expiration and regurgitation and then to inspiration only. Expiration is attended by a specific component of a vomiting reaction--jerky contraction of the abdominal muscles directed at evacuation of the food from the gastrointestinal tract. It is shown that regurgitation occurs most frequently in babies born in a state of asphyxia in whom a shudder-type MR occurs very often.

[Motor reactions in rats during critical growth periods in the early postnatal age]. / Osobennosti dvigatel'nykh reaktsii u krys vo vremia kriticheskikh periodov rosta v rannem postnatal'nom vozraste.

Within the first days after birth, the sleeping rats demonstrate the high rate of motor reactions (RMR) of the jerk type. With advancing age the RMR diminishes. However during a sudden change in the growth, the 25-day-old rats show an increase in the RMR of the jerk type. This is manifested by the return of the functions to the state marking the first days of life. The catecholaminergic mechanisms of the growth and development of rats are discussed.

[Various characteristics of the activity of skeletal muscles in humans and dogs during postnatal ontogenesis]. / Nekotorye osobennosti aktivnosti skeletnoi muskulatury u cheloveka i sobaki v rannem postnatal'nom ontogeneze.

At normal ambient temperatures, in absence of stress, in babies during first months of life (in contrast to less maturely born mammals), the respiratory activity of skeletal muscles is not realized, being observed only under stress conditions. In 1-1 1/2 months old puppies, after deafferentation of the hindlimb, the frequency of movements of a jerk type increases approximating the level observed in newborn animals. At normal ambient temperatures, these puppies exhibit respiratory activity of skeletal muscles which is not observed at this age in control animals.

[Adrenergic mechanisms regulating the motor reactions of rats in the early postnatal period]. / Adrenergicheskie mekhanizmy reguliatsii dvigatel'nykh reaktsii u krys v rannem postnatal'nom vozraste.

In 12-day-old rats, L-DOPA, a precursor of catecholamine synthesis, provokes an increase in the rate of the motor reactions (MR) of the shudder type. Reserpine which promotes catecholamine release from the tissues, leads to the diminution of the rate of the MR of the shudder type in rats of the same age. Aminazine, an alpha-adrenoblocker and antagonist of dopamine receptors, decreases the rate of the MR of the shudder type. Administration of aminazine in a dose of 10 mg/kg at different age periods produces inconclusive changes in the diminution of the rate of the MR of the shudder type. During sudden changes in the growth, the rate of the above-described modulations substantially decreases. The high rate of the MR of the shudder type seen in rats in the early postnatal period is a consequence of the marked activity of the catecholaminergic (dopaminergic) systems during that period. Reduction in the effect of the decreased MR rate produced by the same dose of aminazine during the critical periods of the growth also attests to the high activity of the catecholaminergic (dopaminergic) system in rats at that period.

[Effect of immersion in water on the rudimentary reflexes of infants in the 1st months of life]. / Vliianie pogruzheniia v vodu na rudimentarnye refleksy u detei pervykh mesiatsev zhizni.

Seizing and myotatic reflexes differ in their intensities in the right and left hands already from the first month of life in babies. It was shown that disappearing seizing and myotatic reflexes together with Moro's and Babinsky's reflexes in 3 1/2-4 months old babies can be elicited again during bathing. In the course of adaptation of babies to the water these reflexes disappear.

[Cholinergic and GABA-ergic mechanisms of motor reaction regulation in rats during the early postnatal period]. / Kholinergicheskie i GAMK-ergicheskie mekhanizmy reguliatsii dvigatel'nykh reaktsii u krys v rannem postnatal'nom periode.

Examination of rats during early postnatal period has demonstrated the high rate of motor reactions (MR) of the shudder type during sleep, which amounts to 832 +/- 59 per hour at an age of 9 days. As the animals grow, the rate of MR drops to 623 +/- 38 per hour at an age of 12 days. Administration into 12-day-old rats of aminalon (a GABA analog), phenibut (a GABA derivative), and diazepam that raises receptor sensitivity to GABA and increases GABA-ergic inhibition on the whole, brings about a decrease in the rate of MR of the shudder type. The drugs that increase the content of acetylcholine, e.g. proserine and galanthamine, make the rate of MR higher. On the contrary, the m-cholinolytic atropine reduces this indicator. The high rate of MR of the shudder type in the early postnatal period is a consequence of the correlations between the cholinergic and GABA-ergic regulation mechanisms which, at the developmental stage in question, determine higher activity of the cholinergic and lower activity of the GABA-ergic systems.

[Transformation of the structuro-functional organization of the motor neuron pool of the spinal cord during the postnatal ontogeny of dogs]. / Preobrazovanie strukturno-funktsional'noi organizatsii motoneironnogo pula spinnogo mozga v postnatal'nom ontogeneze sobaki.

Data are presented concerning input-output characteristics of motoneuronal pool in puppies at various age periods (beginning from the first days of life) and distribution histograms of thresholds in motoneuronal populations. It was established that in early postnatal life, before realization of anti-gravitational reactions, low amplitude action potentials in the ventral root are recorded; threshold variation is rather insignificant accounting for the immediate maximum reflex reaction of motoneuronal pool. This is manifested in a rapid (relay) onset of plateau of input-output parameters. At this period, motoneurones of the pool are homogenous with respect to both the size and functional properties. During further postnatal life, relative amount of low amplitude elements of the pool decreases, modal value of threshold distribution being shifted to higher thresholds, indicating differentiation of motoneurones in the pool. After realization of antigravitational reactions, two plateaus in input-output parameters of the system are established together with corresponding two modal values in threshold distribution, indicating the onset of two main groups of motoneurones which differ in the size and functional properties.

[Thyroid gland hypofunction and features of musculoskeletal system growth and growth of the body as a whole at an early age]. / Gipofunktsiia shchitovidoi zhelezy i osobennosti rosta skeletno-myshechnoi sistemy i organizma v tselom v rannie vozrastnye periody.

Chronic injection of mercazolyl to rats aged from 5--7 days to 4 months induces a decrease in motor activity, in the relative and total weight of bones and muscles, in oxygen consumption and cardiac activity. It also leads to hypercholesterolemia associated with a decreased cholesterol level in the skeletal muscle tissue. Abnormal growth and development of the muscles and bones along with a diminished oxygen consumption in rats under one month of age produce a reduction in the body weight as compared to that in control animals. In rats aged from 1 to 4 months the same factors lead to the weight increase accounted for by abnormal oxygent consumption and lipid metabolism. The goitrogenic effec was revealed in young rats chronically administered mercazolyl, this effect was not manifested in 4-month-old rats.

Motor reactions during the antenatal period correlated with the periodic change in the activity of the cardiovascular system.

A connection between the periodic appearance of vagal bradycardia and of intrauterine large-amplitude respiratory movements, as well as the appearance of generalized jerky-type and more sustained extensor motor reactions, has been established in experiments on dog fetuses connected with the mother through the umbilical cord. Brief vagal bradycardia also arises immediately after completion of these reactions and is an analogue of the vagal phase in adults after motor activity. These correlated phenomena are caused by periodic reversible mild hypoxemia which through the chemoreceptors of the sinocarotid zone stimulates the centers of vagal innervation of the heart and the centers of innervation of skeletal muscles. These phenomena disappear when the mother inhales a gas mixture containing less than 14-15% oxygen or greater than 50-60% oxygen, as well as when the mother is under deep anesthesia.

[Motor reactions and cardiac activity of the fetus at the end of full-term pregnancy and during labor]. / Osobennosti dvigatel'nykh reaktsii i deiatel'nosti serdtsa ploda v kontse donoshennoi beremennosti i v rodakh

There are two forms of motor activity of the skeletal muscles at the last stages of internatal ontogenesis, i. e. jerky (jMA) and prolonged (PMA). Vagal regulation of the cardiac activity of the fetus associated with development of temporary hypoxemia took place before and after the JMA and the PMA. JMA and PMA occurred during labour pains when the circulation in the uterus decreased and development of JMA and PMA resulted in the compensation of temporary fetal hypoxemia.