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Biomedical subjects

V N Kazakov

Publications and source records attributed to V N Kazakov.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Assessment of the erythropoietin-producing function of the kidney and liver under controlled perfusion].

The balance of erythropoietin production by the dog kidney and liver was studied during controlled normoxic perfusion. The hormone production was stimulated by acute posthemorrhagic anemia (bloodletting of 25% total blood volume) combined with subcutaneous injection of cobaltous chloride (250 microM/kg body weight). The increase in erythropoietin level was revealed in posthypoxic animal perfusate after 6 hours of perfusion. The amount of hepatic erythropoietin was shown to be 2.5 times higher than that excreted by kidneys.

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PubMed1981

[Associative connections of the parietal cortex in cats].

Cortico-cortical connections of sensory (visual, auditory and somatosensory) areas of cortex with parietal associative cortex were investigated in cat by means of retrograde axonal transport of horse-radish peroxidase and Fink-Haimer technique. The shape, size and localization of cells which make monosynaptic connections between the primary sensory areas and parietal cortex and the distribution of fiber terminals of such cells in the associative parietal cortex were determined. Maximum number of cells connected with field 7 of the parietal associative cortex was found in field V1 of the visual cortex, and with field 5 in field S1 of the somatosensory cortex. Besides HRP-positive pyramidal neurons, mainly localized in layers II-IV, labelled stellate and spindle-shaped cells were found in a small amount. The connections of parietal associative cortex are discussed on the basis of the data obtained.

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PubMed1980

[Corticofugal influences on pontine neuronal activity].

Reactions of neurons of pons varolii reticular and proprial nuclei to stimulation of the frontobasal regions of the cortex (proreal, orbital and basal temporal regions) and dorsal hippocampus were studied in cat. The stimulation of various cortical structures caused phasic and rarely tonic reactions of these neurons. Primary excitation was the dominant type of reactions in the reticular nuclei and primary inhibition--in the proprial nuclei. The greatest number of responding neurons was observed during stimulation of the proreal gyrus. In the cerebro-cerebellar system the most responsible neurons were those of nucleus reticularis tegmenti pontis and ventromedial part of the pontine grey matter. The regions of dominant influence from the cortical structures were in the same zones of the pontine reticular formation, where neurons with rostral projection are localized.

Animals↗
PubMed1980

[Convergence of corticofugal impulses on pontine neurons].

The convergence of corticofugal impulses in reticular and grisea pontis nuclei evoked by stimulation of the neocortex frontobasal regions (proreal, posterior orbital, basal temporal) as well as of the dorsal hippocampus was studied in cats narcotized by a mixture of nembutale and chloralose. Three foci of corticofugal impulse convergence were determined in the structures of pons varolii: one in the reticular formation and two in grisea pontis nuclei -- in their medial and lateral regions. Neurons with excitatory reactions are shown to dominate in the pons varolii reticular formation and those with inhibitory and mixed reactions -- in the grisea pontis. The integrative function of pons varolii nuclei in the functional connection of frontobasal zones of neocortex and hippocampus is discussed.

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PubMed1978

[Interaction of heterosensory afferent impulses in the neurons of the thalamic associative nuclei].

The interaction of visual, auditory and cutaneous afferent signals on neurons of pulvinar (Pulv), posterior lateral (LP) and mediodorsal (MD) thalamic nuclei was studied in acute experiments on cats anaesthetized with a mixture of nembutal and chloralorse. The first (more frequent) type of the interaction was characterized by inhibition or inhibition followed by facilitation of the response; the second--by facilitation or facilitation followed by inhibition of neuronal activity. The capacity for interaction in MD neurons was less expressed than in cells of the Pulv-LP complex (P less than 0.05). The interaction could be better seen in three-sensory elements. Certain peculiarities were found in the interaction of afferent signals coming from different peripheral receptive areas in neurons of both structures.

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PubMed1978

[Responses of neurons of hypothalamic nuclei to stimulation of the frontobasal regions of the neocortex].

Neuronal responses of different hypothalamic nuclei to frontobasal cerebral cortex (proreal, posterior orbital, basal and temporal regions) were studied in acute experiments on cats narcotized by membutal mixed with chloraloze. Neurons which could be activated antidromically during stimulation of another region were recorded. On the basis of their response a number of neuronal chains (circles) functioning in forebrain was distinguished. The first chain is orbital gyrus--preoptical zone--proreal gyrus. The second chain has the same cortical components as the first one, but switching over in the hypothalamus takes place in the region of mamillary bodies. The third chain is basal temporal cortex--lateral hypothalamus--prefrontal cortex.

Animals↗
PubMed1978

[Reactions of neurons in the associative thalamic nuclei to peripheral stimulation of different modality].

Reactions of 252 neurons of the mediodorsal nucleus (MD) and 329 cells of the pulvinar-posterior-lateral complex (Pulv-LP) of the thalamus to separate the complex peripheral stimulations (visual, auditory and somatosensory) were studied in acute experiments on cats anaesthetized with a mixture of chloralose and nembutal. According to the character of the neuronal responses to peripheral stimuli three types of reactions were found: acceleration of the background activity (32.0% neurons in Pulv-LP and 20.6% in MD), inhibition (21.0% neurons in Pulv-LP and 24.2% in MD) and mixed (8.8% neurons in Pulv-LP and 4.0% in MD). No responses were observed in 37.4% neurons of Pulv-LP and in 51.2% of MD. Along with certain similarity, some specific features in the organization of Pulv-LP and MD were found. According to the response latency, the neuronal reactions to stimulation were divided into three groups: with short (less than 20 ms), medium (21--40 ms) and long (over 41 ms) latent period. The second group was the most numerous.

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PubMed1977

[Responses of neurons of the medial group of thalamic nuclei to stimulation of the fronto-basal portions of the neocortex].

Neuronal and focal responses of medial thalamic nuclei (mediodorsal, central lateral, parecentral, centrum medianum, parafascicular) to stimulation of frontobasal cerebral cortex (proreal, posterior orbital, basal temporal regions) were studied in acute experiments on cats narcotized by nembutal mixed with chloralose. Proceeding from the data on the number of neurons responding to cortical stimulation and on the duration of the response latent period, three functionally heterogeneous sections of medial nuclei were distinguished: the microcellular and magnocellular regions of the mediodorsal nucleus, and the intralaminar nuclei with the parafascicular complex. Neurons were recorded which could be activated antidromically during stimulation of another region. On this basis a suggestion is made on the integrating function of medial nuclei providing unification of the frontobasal regions of the neocortex.

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PubMed1977

[Electrophysiologic analysis of cortico-pontine relationships].

Projections of different regions of orbitofrontal and basotemporal cortex as well as of the hippocampus in the pons varolii area were studied by means of focal recording in acute experiments on cats anesthetized with nembutal and chloralose. It is shown that different formations of the frontobasal regions of the neocortex have local projections into the rostral zones of pons varolii and relatively diffuse projections into its caudal regions. The representation of the hippocampus is weaker as compared with the representation of the frontobasal region, and the focal responses are more diffuse. All the studied structures are represented in the nuclei of the pons varolii. The region of the orbitofrontal cortex is not represented in the caudal part of the reticular formation, the basotemporal cortex has no projections into brachium pontis.

Animals↗
PubMed1976

[The interaction of impulses evoked by stimuli of different modality in neurons of the parietal association cortex].

Interaction of visual, auditory and electro-dermal signals in neurons of the parietal associative cortex was investigated in acute experiments on cats anesthetized by chloralose and nembutal. Two types of the interaction were found, one of which was characterized by inhibition or inhibition followed by facilitation of the response to testing stimuli, and the other by facilitation or facilitation followed by inhibition of background impulses. The interaction between signals of different modality is shown to depend on the properties of the neuron. Interaction ability in polysensory neurons was evidently higher than in bi- and monosensory ones.

Animals↗
PubMed1976

[Electrophysiologic study of cortico-hypothalamic interrelationships in cats].

In acute experiments on cats anesthetized with nembutal and chloralose the projections of different parts of orbito-frontal cortex, basal temporal cortex and hippocampus to hypothalamic nuclei were studied by focal potential recording. It was found that the proreal gyrus has local projections into the latero-dorsal parts of the preoptical region, rostral parts of the forebrain medial bundle, lateral and posterior hypothalamus with mammilary bodies. The orbital gyrus is projected mainly into latero-dorsal parts of the forebrain medial bundle, latero-ventral part of the preoptical region, and the region of lateral and latero-dorsal hypothalamic nuclei. Projections from the orbital gyrus are of a relatively diffuse character. The basal temporal cortex has diffuse projections into the central part of the preoptical region, latero-ventral part of the forebrain medial bundle and lateral mammilary body. No pronounced foci were observed in the hypothalamic structures during stimulation of the hyppocampus, but diffuse projections were found into ventral parts of the preoptical region and ventral regions of the forebrain medial bundle as well as into lateral hypothalamus and lateral mammilary nucleus.

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