THE CHANGES OF EPILEPTOGENIC THRESHOLD IN HIPPOCAMPUS DURING NORMAL SLEEP - WAKING CYCLE.

Our work aimed to investigate the changes of focal epileptogenic threshold at different stages of sleep-waking cycle (SWC). Experiments were carried out in adult Wistar rats. Under ketalar anesthesia electrodes were implanted stereotaxically into the brain structures, according to Paxinos and Watson atlas coordinates. Epiletiform Discharges (ED) were induced by electrical stimulation of dorsal hippocampus. In addition, reduction of neocortical activity via spreading depression (SD) was induced in the neocortex by bilateral application of 12% KCL solution. It was found that EDs were more durable at the stage of slow sleep than in wakefulness. Consequently, during slow sleep, the hippocampal epileptogenic threshold was lowered. Prolongation of EDs of hippocampal origin during SD was also observed in neocortex. According to the data obtained one of important factors increasing susceptibility of hippocampus to EDs, at the stage of slow sleep, should be the weakening of tonic inhibitory influence of the cortex upon hippocampus, resulting in decreased epileptogenic threshold in the latter.

THE STUDY OF LIVER AND KIDNEY FUNCTION WITHIN COVID-19 PATIENTS.

Goal -the existing data on the coronavirus disease 2019 (COVID-19) revealed the impact of the disease on different organs such as the liver, the heart, the kidneys, etc. In our study, we evaluated the clinical characteristics of COVID-19 in patients with abnormal liver and kidney test results in recovered and dead patients. The number of the covid-19 patients was - 289. The gold standard method of polymerase chain reaction (PCR) was used to detect the infection of Covid-19. Blood plasma was used as research material. For The Determination of ALT, AST, and Creatinine, the Analyzer was the Prestige 24i - optimized, modified method according to the International Federation of Clinical Chemistry (IFCC), without pyridoxal phosphate; For the statistical analysis were used the Graphed Prism (Version 8.0). Studies have revealed an increase in AST and ALT compared with the reference value. A small difference was also found between those who died and those who recovered; A change in creatinine levels was also found. Men have a high level of Creatinine (~4.28 times) compared to the reference level, and in women, the level of Creatinine is ~2.18 times higher than the reference level. We have thought that according to our results, the high creatinine levels may have some risk impact for the severity of COVID-19 disease.

TONIC INFLUENCE OF NEOCORTEX ON HIPPOCAMPAL SEIZURES.

The interaction between different brain structures could be crucial to predicting seizure occurrence, threshold and spread. Moreover, the sleep-wake cycle and electrical activity of brain structures in different phases of sleep could significantly affect the pattern and extent of seizure spread, and therefore the characteristics of epileptic activity. In this animal model using 15 Wistar rats, we show that the duration of hippocampal seizures, induced by electrical stimulation of the hippocampus, is significantly increased during slow sleep. Moreover, decreasing the electrical activity of the neocortex by cooling of the cortical surface or induction of cortical spreading depression also caused an increase in hippocampal seizure duration. Conversely, warming the cortical surface triggered a remission in spreading depression, in turn restoring the duration of epileptic episodes. Our data suggest that the neocortex probably exerts a tonic inhibitory influence on hippocampal seizures. Thus, cortico-hippocampal interaction could be an important component in the manifestation and generalization of limbic seizures.