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Biomedical subjects

A I Belich

Publications and source records attributed to A I Belich.

At least 19 recordsLinked to original sources
PubMed1996

[Morphophysiological analysis of the formation of mechanisms of the activity-rest cycle in human ontogenesis].

The natural behavior of normal and anencephalic fetuses at 20 to 41 weeks of the development was studied by ultrasound monitoring and continuous recording of heart rate (HR) and motor activity (MA), followed by processing and presentation on [symbol: see text]CM computer. The statistical characteristics of HR and MA changes in the anencephalic fetuses were corrected by the degree of CNS deficiency. The comparative study of 20 normal and 34 anencephalic fetuses showed: 1) when the spinal cord was present, stable HR (about 150 bpm) seems to be due to cardiac automatism and sharp decelerations unaccompanied by MA were recorded; 2) in fetuses with the medulla oblongata present showed a decrease in baseline HR up to 140 bpm, repeated pronounced decelerations and spontaneous single motor acts dissociated with the latter; 3) when a rudiment of the midbrain was present, some reductions in the amplitude of decelerations and manifestation of weak accelerations, cluster motor acts, brief episodes of the active state were revealed; 4) the quiet state was observed in fetuses with the cerebral cortex; 5) the rest-activity cycle formed with further differentiation of the cerebral cortex.

Anencephaly↗
PubMed1993

[The development of interrelationships between the activity-rest cycle and thermoregulation in rabbit fetuses].

The gradient of temperatures of the foetus and mother was found to increase along with an increase of the gestation age which coincides with an increase in the mass of grey fat tissue. In artificial placenta insufficiency, the activity-rest cycle of the foetuses is delayed by 1 or 2 days in their development. The mechanisms of thermoregulation were shown to start forming by 4 or 5 days earlier than the activity-rest cycle, the character of their functioning being comparable to that in poikilothermic animals.

Adipose Tissue, Brown↗
PubMed1989

[Development of the activity-rest cycle in the human fetus].

Some features of natural fetal behavior (general motor activity, including respiratory activity, heart rate and the motor-cardiac reflex as their correlated function) were studied by means of ultrasound scanning, monitoring and dynamic cardiography in 96 women at 20 to 36 weeks of pregnancy under continuous recording of physiological parameters for 2-3 hours. Computer analysis of heart rate variation in correlation with body movements has revealed that there is only one functional state in the fetal behavior, called "nondifferentiated state" (NDS), by the 20th week of pregnancy. Against this background, there appear transitory episodes of active state beginning from the 21st week, and those of quiet state, from the 23rd week; duration of the episodes increases with the progress of pregnancy. In the intervals between the episodes of active and quiet states, NDS gradually transforms into an intermediate state by the 28th week, which shortens in the course of ontogenesis; the alternation of active and quiet states assumes distinct cyclicity by the 32nd week that indicates the establishment of the rest-activity cycle, becoming apparent in all fetuses in the 36th week of gestation when it reaches 50-70 min in duration. On the basis of the comparison of somato-vegetative patterns of quiet state in human fetuses with the ones, seen earlier in rabbit fetuses, the homology of these states is postulated.

Female↗
PubMedDate not supplied

[Interaction of the cholinergic and adrenergic systems during generation of 2 forms of sleep in Rana temporaria frogs and Emys orbicularis turtles].

Universal role of cholinergic mechanisms has been revealed in triggering of activation during two forms of sleep in cold-blooded animals--the primary sleep (fish, amphibians) and intermediate sleep (reptiles). The intensity of activation phenomenon in the brain during these forms of the sleep is controlled by functional interaction between cholinergic and adrenergic systems of the brain. It is suggested that the vegetative nervous system is the most ancient regulatory system of the cycle awakefulness-sleep in vertebrates. The observed activation phenomenon, developing during sleep in the cold-blooded animals, with respect to its biological role plays presumably the same function as paradoxical stage during slow--wave sleep in warm-blooded animals.

Adrenergic Fibers↗
PubMedDate not supplied

[The development of the activity-rest cycle in the rabbit fetus].

On 25-30-day rabbit foetuses, in chronic experiments using constant synchronous recording of the motor activity and heart rate, studies have been made of temporal organization of the activity-rest cycle. Already in 25-day foetus, three functional conditions may be distinguished: active, intermediate and resting ones, the duration of the latter increasing to the end of gestation up to 8-10 min, whereas the duration of the intermediate phase decreases, reaching its minimum to the 30th day if not being completely reduced. Cyclic pattern of active and resting phases is observed in 28-day foetuses; to the 29th-30th day, these phases from a unique activity-rest cycle, its duration reaching 20-30 min to the end of intrauterine period. It is suggested that the resting phase in foetal rabbits serves as a basis for the development of polyphasic sleep in adult animals.

Activity Cycles↗
PubMedDate not supplied

[Effect of the epiphysis and hypophysis on the circadian organization of the wakefulness-primary sleep cycle in the frog Rana temporaria].

Using continuous non-contact registration of the heart rate and motor activity in unrestrained frogs, studies have been made of the effects of hypophysectomy and epiphysectomy on functional state of the organism. It was shown that removal of the epiphysis alleviates the circadian physiological rhythm of natural changes of functional states in wakefulness-primary sleep cycle, whereas removal of the hypophysis results in additional cyclic rhythm of two functional states in the diurnal periodicity of the behaviour. The latter effect is considered to be the ultradian rhythm, which in the intact animals is masked by the circadian one modulated by natural diurnal illumination. It is suggested that removal of the epiphysis reveals endogenous rhythm of the activity typical of periodic regimes of the spontaneous excitation at early stages of ontogenesis.

Animals↗
PubMedDate not supplied

[Effect of the hypothalamus on the diurnal rhythm of heart rate in the Rana temporaria].

Computer treatment of the continuous row of R-R intervals of the ECG revealed the general pattern and masked periodicity of the diurnal dynamics of the heart rate in the frog Rana temporaria. It was found that in day time intact frogs exhibit tonic decrease of the heart rate with a maximum at about 12 a.m. At night, there is a tendency to tachycardia with a maximum at about 4 a.m. This periodicity of the heart rate is monitored mainly by the anterior and posterior hypothalamus.

Animals↗
PubMedDate not supplied

[Role of the hypothalamus in organizing the wakefulness-primary sleep cycle in the frog Rana temporaria].

New data are presented on the role of the hypothalamus in re-arrangement of tonus of the vegetative nervous system during three forms of rest of the primary sleep in the frog. Temporal organization of the cycle " awakefulness -primary sleep" depends on interaction of the anterior and posterior hypothalamus. The anterior hypothalamus is responsible for manifestation of two forms of rest of the primary sleep, i.e. diurnal resting form (P-1) which is associated with the increase in plastic tone of skeletal muscles, and the other resting form (P-3) which is associated with the decrease in muscle tonus. These forms of rest are accompanied by the predominance of parasympathetic tonus of the vegetative nervous system. The posterior hypothalamus is associated with manifestation of the resting form which includes the increase in the rigidity of muscle tonus (P-2) and transient phasic increase in the heart rate, the latter being observed at all forms of the primary sleep. Statistical treatment of the ECG revealed specific pattern of two-dimensional density of distribution of probabilities of R-R intervals for the resting forms of the primary sleep which is important for identification of different phases in the " awakefulness -primary sleep" cycle in vertebrates.

Animals↗
PubMedDate not supplied

[Dynamics of cardiac rhythm in hypobiosis in the frog Rana temporaria].

Employing distant recording technique of the heart rate and motor activity in hypobiotic frogs, studies have been made of temporal characteristic of the diurnal dependence of the heart rate on natural diurnal behavioural periodicity. It was shown that during natural reversible hypobiosis, the circadian rhythm of the heart rate is preserved, being destroyed during irreversible hypobiosis. Typical patterns are presented of the circadian dynamics of the heart rate with a specific variation in R-R intervals of the ECG during reversible and irreversible hypobiosis. A discussion is made of the importance of preservation of self-regulating mechanisms during hypobiosis, these mechanisms accounting for maintenance of a certain level of the activity in hypobiotic organism.

Animals↗
PubMedDate not supplied

[Sleep--wakefulness cycle of cold-blooded vertebrates according to the results of continuous contact-free recording of the heart rate and motor activity].

Using continuous non-contact registration of the heart rate and motor activity, separate states were revealed in awakefulness--sleep cycle of various poikilotherms (the catfish Ictalurus nebulosus, frog Rana temporaria, tortoise Emys orbicularis). The method employed allowed also to classify motor automatic activity which was observed in earlier experiments at the background of sleep-like forms of the resting state. Two basic types of these automaticities were distinguished. Comparison of the data obtained on poikilothermic animals with those obtained on homoiothermic ones (the ground squirrel Citellus parryi) indicates the validity of using the heart rate and motor activity for detection of the awakefulness-sleep cycle.

Activity Cycles↗