Biomedical subjects

A A Shandra

Publications and source records attributed to A A Shandra.

At least 73 records · Page 4Linked to original sources

PubMed1981

[Use of nicotinamide and pyridoxal-5-phosphate to treat experimental epilepsy].

In experiments on cats it was shown that nicotinamide injected intravenously in a dose of 300 to 500 mg per kg body weight depressed singular epileptic foci and groups of foci with synchronized activity induced in the animals' brain cortex by application of strychnine (0.1 ml of 3% solution). The vitamin was also effective, though to a lesser degree, in depressing foci induced by application of penicillin (2% solution). Pyridoxal-5-phosphate (Pyr-5-Ph) injected intravenously in a dose of 10 mg/kg depressed singular foci and groups of foci with synchronized activity induced by application of 2% solution of penicillin, but was less effective in depressing strychnine-induced foci. Combined application of both drugs even in lower doses (nicotinamide, 200 mg/kg; Pyr-5-Ph, 5 mg/kg) resulted in depression of groups of epileptic foci induced by combined application of strychnine and penicillin. Mechanisms of the effects discovered are discussed. A question on possible use of combined nicotinamide and pyridoxal-5-phosphate in the treatment of epilepsy is raised.

Animals↗

PubMed1981

[Effect of cerebellectomy on strychnine foci in the cerebral cortex].

Acute experiments on cats demonstrated that cerebellectomy resulted in the shortened latency period of the appearance of seizure discharges produced in the neocortex by strychnine application. The time during which the amplitude of spikes was increasing up to the maximal size declined as well. Meanwhile the period of the existence of the spikes of maximal amplitude and the total time of potential generation were greater. A conclusion is made that the cerebellum is an important component of the brain antiepileptic system.

Animals↗

PubMed1980

[Effect of nicotinamide on epileptic activity in the cerebral cortex].

The experiments on cats showed that intravenous administration of nicotinamide suppresses the epileptic activity in a solitary epileptic focus as well as in the complex of epileptic foci produced by strychnine application to various cortical zones under the influence of the most powerful focus that plays the role of a determinant. After the intravenous injection of nicotinamide (50-70 mg/kg) the complex was destabilized and broken down. The epileptic activity in the dependent foci of the complex disappeared first in the more remote from the determinant focus and then in the nearer one. The determinant focus was the last to disappear. The inhibitory effect of nicotinamide is associated with antiepileptic activity. Nicotinamide is suggested to be one of the endogenous drugs which may suppress brain hyperactivity and activate the antiepileptogenic system.

Animals↗

PubMed1980

[Effect of electric stimulation of the caudal reticular nucleus of the pons on foci of epileptic activity in the cerebral cortex].

It was shown in experiments on cats that electrostimulation (ES) of the nucleus caudalis reticularis pontis under the destruction of the central grey matter suppressed discharges in a single epileptic focus, created with application of strychnine to the brain cortex and did not suppress the epileptic activity in the complex of foci, formed under the influence of a determinant focus after local application of strychnine to different zones of the neocortex. After increasing the number of foci in the complex the resistance of the latter to suppressive effects of ES of the nucleus caudalis increases too. The complex reduction owing to liquidation of its foci (local application of nembutal) facilitates the suppressive effects of ES of the nucleus caudalis. Under prolonged inhibition of the epileptic activity in the focus, the coagulation of the nucleus caudalis leads after its long-term ES to the recovery of the epileptic activity. The evidence obtained is discussed from the standpoint of the properties of the pathological system (epileptic complex) and the role of the "antisystem" in suppression of its activity.

Animals↗

PubMed1980

[Formation of determinant structures and functional complexes in the neocortex when the brain is transected at different levels].

A strychnine focus created in the cat neocortex preparations with mediopontine section and encephale isolé, increased activity in other weaker foci, synchronized discharges in them, united them into a functional complex and determined the character of the whole complex activity. Such an hyperactive focus plays an active role of the determinant structure. In cortex isolé and preparations with mesencephalic section of the stem, a more rapid formation of functional complexes occurred under the effect of determinant focus. Complete elimination of the afferent and thalamo-cortical interactions seems to hinder neither the hypersynchronization of cortex neuronal elements, nor the formation of functional complexes, nor the generalization of seizure activity over the cortex.

Animals↗

PubMed1980

[Formation of an epileptic complex in the cerebral cortex and effect of diazepam on it with different levels of cerebral transection].

Effect of diazepam on the activity of the epileptic complex consisting of a number of foci created with strychnine applications to the brain cortex under conditions of intact brain and at different levels of it neuronal isolation was studied in acute and chronic experiments on cats. It was shown that in the preparations of cerveau isolé and cortex isolé a more rapid formation of the epileptic complex under the influence of the determinant focus, and marked generalizaiton of convulsant activity could be observed. Diazepam induced a decrease in the amplitude and frequency of convulsive discharges. There was a break in the synchronization of their appearance first in the dependent foci and then in the determinant one. The diazepam effects were seen both in the intact brain and in the preparations of cerveau isolé and cortex isolé. These findings indicate that diazepam may exert an indirect action on the brain cortex that does not exclude the participation of other brain structures in the realization of the diazepam effect under conditions of intact brain.

Acute Disease↗

PubMed1979

[Modeling of determinant and dependent foci of epileptic activity in the rat cerebral cortex].

Foci of increased excitability were created in acute experiments on rats by means of weak strychnine solutions working at independent regimens. The hyperactive excitability focus induced by means of concentrated strychnine solutions played the role of a determinant structure. The importance of the latter is in the fact that it determines the activity character of other epileptogenic foci, enhances their convulsive activity, unites them into a single functional complex and determines the behaviour of the complex as a whole. This complex can be destroyed by depression of the determinant focus activity. Switching off any dependent foci included into this complex fails to destroy that latter. Results of the investigations confirmed on the new model the general concept of the role played by the determinant structures in the brain activity.

Acute Disease↗

PubMed1979

[Formation of epileptic activity complexes under the effect of the determinant focus in the cortex isolé].

In experiments on cats foci of enhanced excitation working in independent regimes were created in the neuronal-isolated cortex using weak strychnine solutions. Creation of a hyperactive focus by means of application of strychnine concentrated solutions or crystals leads to an increase in the amplitude and discharge frequency in other foci, synchronism in discharges of these foci and their unification into a single functional complex, working in the hyperactive focus regime. The latter, in such a way, presented the determinant structure. Under the influence of the determinaant focus there was also a marked generalization of the convulsive activity manifested by an embrace with epileptical discharges of the cortex area intact from strychnine. The results obtained indicate that the established relations between the foci of hyperactivity in the cortx as well as the effects of the determinant structure may be realized by the cortex mechanisms proper.

Action Potentials↗

PubMed1979

[Formation of epileptic activity complexes in the cerebral cortex as a result of a determinant focus induced by acetylcholine].

Foci of increased excitability were created by means of weak strychnine and penicillin dilutions in experiments on cats. These foci worked at individual regimens. Creation with acetylcholine and proserine of a hyperactive focus led to increase of the amplitude and frequency of convulsive discharges at first in the nearest activity foci, and then in the ones remote from the hyperactive focus. The next stage was attended by qualitative changes in the activity pattern of strychnine and penicillin foci (the appearance of acetylcholine activity in them) and by the formation of a single functional focal complex working in the regimen of acetylcholine focus. Thus, the latter played the role of a determinant structure. Suppression of the determinant focus activity led to disappearance of the acetylcholine activity in all the other foci, restoration of the initial (penicillin and strychnine) activity, and to the epileptic complex decay.

Acetylcholine↗

PubMed1979

[Afferent cortico-cortical connections of the orbito-frontal cortex].

Relations of frontal and orbital sections of the prefrontal cortex with different sections of neocortex were studied in cats by means of acute strychnine neurography. Afferent cortical connections of orbital and frontal sections did not differ much in their organization. Both sections had direct efferent cortical connections with motor, somatosensory and the rostral sections of the secondary auditory zone. Primary auditory field, visual and parietal associative cortex of suprasylvian gyrus had no direct afferent connections with orbito--frontal cortex. The cortico--cortical connections of orbito--frontal cortex with motor, somatosensory, and rostral sections of insular zone of neocortex appeared to be bilateral.

Animals↗

PubMed1978

[Principle of the determinant and formation of complexes of epileptic activity].

Experiments on cats under nembutal anesthesia demonstrated that the focus in cerebral cortex with a high level of convulsive activity increases the activity in foci with a low level of convulsive activity, unites them into a functional complex of epileptic activity and determines the behaviour of this complex. Such a focus has been named a determinant. An abolishment of the determinant focus entails a breakage of this complex. The abolishment of any dependent foci fails to produce such effect. The dependent foci are suppressed first of all under ether or halothane anesthesia. Bemegrid injected intravenously revealed first of all the latent determinant foci. The results of such studies as well as some problems of the pathogenesis, diagnosis, therapy and terminology of focal epilepsia are discussed from the point of view of a general conception of the role of the determinant structures in the CNS activity and the theories of generator mechanisms of neuropathologic syndromes characterized by hyperactivity of the systems.

Animals↗

PubMed1978

[Mechanism of formation of epileptic activity complexes in the cerebral cortex under the influence of a determinant focus].

It was shown in the experiments on cats anesthetized by nembutal that by forming a hyperactive focus with a high level of excitation in the temporal cortex and a number of foci with a less higher level of the excitation in other parts of neocortex, it is possible to create a functional complex, working in a single routine, determined by the activity of hyperactive focus. The latter plays a role of a determinant structure. The inhibition of the determinant focus results in the disturbance of the epileptic complex. Focus nature has no sufficient importance in the realization of the following interrelations: both the determinant focus and dependent foci may be created by means of strychnin and penicillin, disturbing different forms of the inhibition. The results of our investigations evidence a common conception on the role of determinant structures in the activity of the nervous system.

Animals↗

PubMed1978

[Functional interaction between the determinant and other foci of epileptiform activity created in the cortex of both cerebral hemispheres].

It was shown in experiments on cats under nembutal anesthesia that creation of a hyperactive focus with a high excitation level in the orbital or coronary cortex of one hemisphere and of a number of foci in the neocortex of the contralateral hemisphere led to formation of a functional complex working in a unified regimen determined by the hyperactive focus activity. The latter plays the role of a determinant structure. Suppression of the determinant focus with nembutal was followed by a decay of the epileptic complex. Section of the corpus callossum (its rostral part) led to derangement in synch ronization of the work between the determinant and other epileptic activity foci. The results of investigation confirmed the conception on the role of the determinant structure in the nervous system activity.

Animals↗

PubMed1977

[Effect of aminazin on changes in the electrical activity of the cerebral cortex under the influence of the toxin C1. perfringens type A].

Experiments on cats revealed that injection of chlorpromazine (3 mg/kg of body weight, intramuscular) one hour prior to the Cl. perfingens toxin type A injection prevented the appearance of desynchronization of the electrical activity of the cerebral cortex usually observed during the first phase of intoxication. Chlorpromazine injection postpones the appearance of the electrical activity depression phase during the second phase and prolonged the animals' life span from 1.5 to 2 times. The effect of chlorpromazine was apparently connected with the block of the adrenergic structures of the brain stem reticular formation.

Animals↗

PubMed1977

[Role of hyperactive determinant structures in the creation of functional complexes of seizure activity in the cerebral cortex].

Experiments were conducted on cats; foci of increased excitability working in the individual activity regimens were created by the subconvulsive strychminization. A focus of more powerful excitation induced also by means of strychine played the role of a determinant dispatch station (DDS). Its importance consists in determining the character of the other excitation foci activity in enhancing the excitation in them, in uniting them into a functional complex, and in determining the character of the whole complex activity. This complex can be destroyed by nembutal suppression of DDS. Exclusion of any other destination stations included into the complex failed to effect this complex.

Animals↗

PubMed1976

[Mechanisms of transmission of excitation grnerated in the orbito-frontal cortex].

Experiments carried out on cats showed that interhemispheric generalization of strychnine spasmodic potentials from the orbito-frontal cortex were mainly brought about by the callosal pathway. In contrast to other projection and association zones of the cortex only the frontal portion of the corpus callosum (the rostrum) and not the whole corpus took part in transmitting strychnine commissures. The results of investigations carried out were consistent with the general conception of the principle of the determining dispatch station (DDS) in the nervous system integration activity. These results reveal that the appearance of the DDS induces secondary excitation foci which fully reproduce tha work regimen of the DDS. Switching of such "mirror" foci representing "the destination stations" from the DDS influence led to the elimination of the activity induced in them.

Animals↗

PubMed1975

[Cortico-cortical connections of the orbito-frontal cortex].

Using strychnine neuronography, the connections of proreal and orbital convolutions with different sections of the neocortex were studied, in cats. The proreal cortex was found to have direct efferent connections with premotor, motor, and associative sections of the sigmoid gyrus and with the anterior lateral convolution. Besides, the orbital convolution has connections with the auditory, visual, and associative sections of the neocortex. The orbital cortex was concluded to be the basic efferent system of the orbito--frontal cortex providing the latter's conncetions with different sections of the neocortex; the proreal cortex projects efferents only to adjacent sections of the frontal cortex.

Animals↗

PubMedDate not supplied

The influence of activation of the superior colliculi on convulsive activity during picrotoxin kindling.

It has been demonstrated in experiments in rats in which kindling was induced by repeated subconvulsive doses of picrotoxin (1.0 mg/kg) that the bilateral microinjection of picrotoxin, bicuculline, and penicillin into the deep layers of the superior colliculi of the corpora quadrigemina leads to the appearance of a generator of pathologically intensified excitation. An increase in the latent period of the initial convulsive manifestations, the suppression of clonic-tonic convulsive attacks, as well as the prevention of generalized epileptic activity induced by the systemic utilization of picrotoxin were observed under the conditions of the appearance of a generator of pathologically intensified excitation. An inference was drawn regarding the role of the superior colliculi in the mechanisms of the suppression of convulsive activity and regarding their inclusion in the antiepileptic system.

Animals↗