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Biomedical subjects

E S Gevorkian

Publications and source records attributed to E S Gevorkian.

At least 19 recordsLinked to original sources
PubMed2000

[The role of the thalamic ventrolateral nucleus in the cortical effect on the activity of vestibular neurons].

Electrocoagulation of lateral vestibular nucleus (NVL) reduces inhibitory effect of the motor and somatosensory areas and enhances the inhibitory effect of limbic, vestibular, and orbital cortical areas. Facilitating effect was enhanced by electrostimulation of the motor area and reduced by the stimulation of other cortical areas. Following the coagulation of the NVL, the ascending afferent flow to the cortex seems to be reduced. This results in diminishing of the cortical neurones tone and readjusts the descending influences upon the NVL neurones activity.

Animals↗
PubMed1997

[Limbic mechanisms regulating vestibular neuron reactions in vibration].

Acute experiment on rabbits (extracellular registration) studied influence of limbic cortex on neuron activity of Deuters nucleus before and after exposure to low-frequency vibration (5 Hz, 30 minutes). The authors discuss mechanisms underlying changes in activity and response of vestibular neutrons to electric simulation (5 and 60 Hz) of limbic cortex before and after vibration.

Animals↗
PubMed1990

[The effect of estradiol on the initiation of phosphoinositide catabolism in rat brain synaptic membranes].

The in vivo effect of estradiol on phosphoinositide catabolism initiation provoked by K(+)-depolarization of rat brain synaptosomal membranes was studied. The decreased yield of diacylglyceride was revealed on the 5th sec of initiation. It was found that estradiol markedly increases the phospholipid content, particularly that of phosphatidylinositol, in synaptosomal membranes but causes a simultaneous decrease of the neutral lipid content. The activity of phosphatidylinositol-specific phospholipase C is significantly decreased thereby. It was concluded that the effect of the steroid hormone on the genome provides for a functional status of membrane structures which slightly impedes the processes mediated by phosphoinositides.

Animals↗
PubMed1988

[Action of hydrocortisone on the lipid composition of active and inactive chromatin fractions in the rat liver].

A composition of phospholipids and neutral lipids of rat liver chromatin and its active and inactive fractions has been investigated. It is shown that the hydrocortisone action results in marked increase in phospholipid/neutral lipid ratio of both chromatin and its active fraction. The changes in lipid content is clearly expressed in active chromatin fraction, the lipid content of inactive fraction is not changed. It is concluded that the increase of content in certain phospholipids and simultaneous decrease of neutral lipids in chromatin promotes the hormonal activation of genome.

Animals↗
PubMed1987

[Relation between hormonal induction of enzymes regulating glycolysis and convulsive activity in the brain].

The authors have demonstrated the estradiol induction of the key glycolytic enzymes of the brain (hexokinase, phosphofructokinase and pyruvate kinase) which is "switched off" by injection of actinomycin-D--an inhibitor of protein biosynthesis. Another steroid hormone, progesterone, has an inhibitory action on the above enzymes. Administration of estradiol to rats significantly elevates the amplitude and frequency of contractility induced in them, while the same doses of progesterone decrease them. Thus, there is a definite correlation between the induction of glycolytic enzymes and sensitivity toward contractility on the one hand and the estradiol/progesterone ratio on the other. It is possible that activation of glycolysis may reduce the threshold of epileptic attacks providing an additional energy for epileptic manifestations.

Animals↗
PubMed1987

[Lipid composition of the rat liver nuclear matrix as affected by hydrocortisone].

It has been found that the rat liver nuclear matrix contains a small amount of phospholipids (2%) and neutral lipids (1.6%). The injection of hydrocortisone increased the nuclear matrix phospholipid content and reduced its neutral lipid levels. A marked increase in sphingomyelin content observed was accompanied by the reduction in phosphatidylcholine level. The decrease in neutral lipid content took place mainly at the expense of a sharp lowering of triglyceride and cholesterol ether levels. The latter may turn into free cholesterol, thus increasing its content. The data obtained testify to steroid hormone influence on lipid metabolism in intranuclear structures. The observed changes in lipid composition may be related to specific hydrocortisone-induced activation of genome.

Animals↗
PubMed1986

[Effect of hydrocortisone on the phospholipid composition and activity of various enzymes of phospholipid metabolism in the nuclear membranes of the rat liver].

It was shown that hydrocortisone injections markedly increase the total content of liver nuclear membrane phospholipids, the greatest increase being observed in the phosphatidyl choline level. It was found also that nuclear membranes contain phospholipid metabolism enzymes. The hormone-induced increase in the phospholipid content is accompanied by a marked decrease of the activity of phospholipase A2 (5.3 times against control), phospholipase C (9.3 times) and acyl-CoA: lysophosphatidylcholine transferase (2.5 times). The results obtained are suggestive of appreciable metabolic changes in nuclear membrane phospholipids caused by hydrocortisone which, in turn, may be due to hormonal activation of the genome.

Acetyl-CoA C-Acyltransferase↗
PubMedDate not supplied

[Change in electrokinetic potential in rat brain synaptosomes exposed to estradiol].

The effect of different estradiol concentrations on electrokinetic potential of rat brain synaptosomes has been investigated. Changes in synaptosome electrokinetic potential at early stages of estradiol action are shown. The data obtained show that synaptosomes may be used as a model system to study the correlation between electrokinetic potential of cells and their physiological and biochemical status.

Animals↗
PubMedDate not supplied

[Effect of hydrocortisone on composition of polyphosphoinositides in liver cell nuclear membrane and rat brain].

The action of hydrocortisone in vivo was shown to cause changes both in the total amount of phospholipids and polyphosphoinositides of rat liver and brain nuclear membranes. The hormone increased the content of five from seven phospholipid fractions including the fraction of monophosphoinositide when acting in concentration and exposition leading to activation of biosynthetic processes. The increasing of monophosphoinositides amount was accompanied by the decreasing of triphosphoinositides content which indicated the redistribution among the phosphoinositides fractions under the steroid hormone action in both cell types.

Animals↗
PubMedDate not supplied

[Effects of hydrocortisone and insulin on the electrokinetic potential of hepatocyte nuclei].

The electrokinetic potential of liver cell nuclei of rats after the in vivo separate and joint injection of hydrocortisone and insulin was determined. It was shown that the steroid induces a significant elevation of the value of electrokinetic potential while insulin does not change this parameter. An insignificant elevation of the potential by the joint action of the hormones was found, which apparently is indicative of the antagonism between hydrocortisone and insulin.

Animals↗
PubMedDate not supplied

[Shifts in phospholipid composition of the nuclear matrix in rat liver cells exposed to insulin].

It was shown that the total content of phospholipids of rat liver nuclear matrix increased after in vivo action of insulin (2 units per 100 g of animal weight). At the same time the sphyngomyelin content was increased and the content of phosphatydilcholine and phoshpatydilinositol was decreased significantly under the hormone action. The decreasing of monophosphoinositides amount was accompanied by the increasing of triphosphoinositides content which indicates the redistribution among the phosphoinositides fractions under the hormone action and may be the result of insulin initiation of phosphoinositide pathway in nuclear membrances.

Animals↗
PubMedDate not supplied

[Effect of insulin on the composition of chromatin phospholipid in rat liver cells].

In vivo the action of insulin on rat liver chromatin phospholipid composition was investigated. It was shown that the hormone led to reliable increase (nearly 20%) of total phospholipid content. The same phenomenon was shown also in the fraction of active chromatin while the phospholipids content of non-active chromatin didn't changed. It was also shown that the content of three from six phospholipid fractions altered under the insulin action. The content of sphingomyelin and phosphatidilethanolamine increased and the quantity of phosphatidylinositol decreased under the hormone action. The decrease of monophosphoinositides content was accompanied by the reliable increase of triphosphoinositides amount. It was suggested that the fractions of chromatin polyphosphoinositides were redistributed under the action of insulin.

Animals↗
PubMedDate not supplied

[Changes in psychophysiological variables in students during examinations].

Current psychological tests and classic methods for recording and calculating autonomic correlates were used to study changes in students' psychophysiological indices during examinations. During this period, the students were found to develop emotional stress characterized by a complex of psychophysiological and autonomic changes. The nature and direction of the latter were determined by the individual and typological properties the examinees, by the significance of the emotional and stress situation of the autonomic nervous system and its responsiveness.

Adolescent↗