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Biomedical subjects

S V Girman

Publications and source records attributed to S V Girman.

At least 37 records · Page 2Linked to original sources
PubMed1986

Normalization of dystrophic brain cortex neurons after hypoxia and transplantation of embryonic nervous tissue in rats.

It was established by us previously that mass reversible and irreversible dystrophy and death of neurons occur in the cortex and hippocampus of adult rats after acute hypoxic hypoxia. Transplantation of embryonic nervous tissue into the brain of rats exposed to hypoxia leads to partial normalization of the nervous tissue and brain cortex and to the reduction in the number of irreversibly degenerative neurons. The objective of the present work is to find out how this visually detected normalization of brain cortex is achieved: by means of elimination of dead neurons and preservation of normal ones or by means of compensatory-restorative processes on the cellular and intracellular levels. To elucidate this question, adult Wistar rats were subjected to acute hypoxic hypoxia and cortex tissue pieces of 19-day-old rat embryos were transplanted into their brain and the brain of intact rats. Intact and hypoxia-subjected rats served as a control. Parts of their brain were injured by puncturing with a syringe needle and injecting 0.01 ml of physiological solution. The rats were killed 4 and 100 days after the operation, their brains were examined histologically and the number of normal nerve cells and those with signs of irreversible and reversible dystrophy or compensatory restoration per 1,000 neurons was determined: uninucleolate, binucleolate, binuclear and paired morphologically similar nerve cells. It has been established that normalization of brain cortex in rats after hypoxia and transplantation occurs not only due to elimination of dead neurons and preservation of normal ones but mainly due to transition of reversibly degenerative neurons into the normal state and, probably, partly due to compensatory-restorative processes on the cell level. Transplantation has a stronger influence than a single injury of the brain.

Animals↗
PubMed1985

Morphological, biochemical and physiological changes in brain nervous tissue of adult intact and hypoxia-subjected rats after transplantation of embryonic nervous tissue.

Data of morphological, biochemical and physiological investigations of brain nervous tissue in adult intact and hypoxia-subjected rats after transplantation of rat embryonic nervous tissue are presented. It has been established that transplants survive and develop successfully in the brain of both intact and hypoxia-subjected rats. The Golgi technique reveals that transplanted neurons form dendrites and axons. They also establish afferent and efferent connections with neurons in different brain regions of the recipient, as has been demonstrated by the horseradish peroxidase (HRP) tract tracing technique. Hypoxia induces reversible as well as irreversible dystrophy of host brain neurons, and transplantation of embryonic brain tissue leads to considerable normalization of the state of reversibly dystrophic neurons. Biochemical investigations have revealed that the spectrum of cytoplasmic proteins of neurons and proteins of the whole brain cortex tissue changed after hypoxia are significantly normalized after subsequent transplantation. It should be also pointed out that there is a considerable increase in the number of proteins in certain fractions which is correlated with regeneration of reversibly dystrophic neurons and other cortical cells. Electrophysiological experiments revealed distinct but short-term EEG changes induced by hypoxia. 1-2 days after hypoxia all EEG parameters were back to normal and displayed no changes during the 2-3-month registration period.

Animals↗
PubMed1977

[Effect of binocular interaction of rat visual cortex neurons].

In anesthetized rats, out of 135 neurons recorded in binocular area within the striate cortex, 92 (74%) were binocular. 53 of these had well defined, mainly identical receptive fields on the two retinae. The range of relative horizontal and vertical disparity was found to be 5 degrees and 4 degrees respectively. These findings suggest that the visual system of the rat is capable to discover the spatial relationship using mechanisms of binocular fusion, in contrast to data obtained in rabbits.

Animals↗
PubMedDate not supplied

Unilateral photoreceptor rescue can improve the ability of the opposite, untreated, eye to drive cortical cells in a retinal degeneration model.

In the Royal College of Surgeons, rat photoreceptor degeneration occurs over the first several months of life, causing deterioration of visual cortical responsiveness seen as greater numbers of cells being nonresponsive to visual stimulation, poor tuning of those cells that do respond, and an overall tendency for domination by the contralateral visual input. If the progress of degeneration in one eye is slowed by intraretinal cell transplantation, cortical responses to stimulation of the remaining, untreated, eye are much stronger, better tuned and histograms of ocular dominance resemble more those in normal rats. This suggests that the rescued eye is able to enhance performance in the untreated eye by some form of postsynaptic mechanism.

Animals↗
PubMedDate not supplied

[The long-term effect of acute hypoxic hypoxia on shuttlebox avoidance learning in rats].

Long-term influence was studied of the acute hypoxic hypoxia seance on rats behaviour in situation of elaboration of the conditioned reaction of active avoidance of electric shocks in shuttle chamber. It was found that in 2.5-3 months after the hypoxia seance, the experimental animals significantly differed from the intact controls by dynamics of CR elaboration (rats which had hypoxia were ahead of the control ones) and by distribution of the conditioned reactions latencies (for experimental animals this distribution was shifted to minor values). The character of these behavioural shifts coincided with that observed in the group of rats with local unilateral hippocampus lesion. The obtained results and numerous data presented in literature on the influence of the hippocampus lesion on animals shuttle avoidance learning, allow to conclude that the seance of hypoxic hypoxia leads to the disturbance of the hippocampus function. This conclusion conforms to the data on diffusive death of the hippocampal and neocortical neurones as a result of hypoxia action.

Acute Disease↗
PubMedDate not supplied

[Responses of neurons of the primary visual cortex to visual stimuli in the awake unrestrained rat].

In an experiment on alert unrestrained rats trained for instrumental reaction of retaining immobility, a study was made of the structure of receptive fields (RF) and the properties of responses to controlled visual stimuli of cortical neurones in the field 17. Most of the neurones by their characteristics did not differ from those of immobilized rats. The RF structure and the neuronal responses did not depend on the animals' behaviour, the level of their attention, excitation or motivation. Part of the neurones which did not respond to a wide set of light-dark stimuli presented on the screen, gave responses to natural objects or items of the surroundings. The results are discussed in connection with up to date concepts on information processing in the primary visual cortex of mammals.

Animals↗