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Biomedical subjects

D A Sibarov

Publications and source records attributed to D A Sibarov.

6 recordsLinked to original sources
PubMed2006

[Reflection of cortical activation pattern in the human EEG phase structure].

Investigation was fulfilled on healthy subjects (22) and on outpatients (62). The EEG by the standard scheme as recorded at resting with open and closed eyes and under different functional loads. These records were processed in accordance with the EEC phase structure with the aid of computer animation technology. The main idea of the phase structure technology consists in rejection of one supporting lead. Time shifts were measured only between two neighbouring electrodes, so that the oscillations under comparison were always highly coherent. Time errors were evaluated according to crosscorrelation function maximum shift. The differences between high- and low-frequency EEG rhythms were shown to be only quantitative from the phase structure viewpoint. Qualitatively, the rhythm properties were equal and came to slow (second) phase structure oscillations. Low frequency activity compared to high frequency one was characterized by greater phase shifts from electrode to electrode. Phase shifts of potentials are forming the structure which, as a whole, is very similar in different people and is reproduced in different states. Initial EEG waves appearance is statistical linked with main sensory projections: visual (occiput), auditory (temples) and somatic (parietal region) with addition of frontal region. Redistribution of phase leadership in favor of occipital pole and to both temporal regions when eyes are open is described. It is apparently dependent on the sensory surge level from thalamus to a given cortex region. Phase gradient direction seems to reflect the cortex current density gradient which is parallel to surface. It can be used for localization of compact sources lying near to cortex.

Adolescent↗
PubMed2006

[Intranasal epitalon infusion modulates neuronal activity in the rat neocortex].

Properties of tetrapeptide epitalon (Ala-Glu-Asp-Gly) constructed on the basis of pineal peptide extract, have been studied. The intranasal infusions: a noninvasive way to deliver this peptide to CNS hypassing the blood-brain barrier, was used. The aim of the study is to estimate epitalon action on rat motor cortex spontaneous activity. Wistar male rats were anesthetized with urethane (1 g/kg). Extracellular unit recording was made using glass microelectrodes (1-2 MOhm). After recording of spontaneous activity (10-15 min), epitalon intranasal infusion (2 ng) was followed by 30-minute recording. Within a few minutes after the infusion, significant activation of neural activity was observed (2-2.5-fold higher frequency of neuronal spikes). Complex response consisting of several phases was identified in some recordings. The spikes frequency growth during 5 to 7 min (first phase) after the infusion was followed by the second (11-12 min) and the third (17-18 min) phases. An increase of neuronal spontaneous activity was conditioned by the higher frequency of already active units and by the involvement of previously silent cells. At least the first phase of epitalon action can be explained by direct action of the peptide on the cells of the motor cortex.

Action Potentials↗
PubMed2005

Fluorescent microscopic study of epithalon binding in maternal and fetal rabbit tissues in health and under conditions of placental insufficiency.

Epithalon (regulatory tetrapeptide) labeled with dansil (fluorescent stain) easily penetrates into all tissues and organs of pregnant rabbit females and through the placenta into fetal organs. Incorporation of labeled epithalon in placental tissues is more often observed in fetuses developing under conditions of placental insufficiency than in normal fetuses.

Animals↗
PubMed2000

[Pinealocyte functioning in stress during daytime in rats].

Several types of unit activity were detected in the rat pineal gland during a 48-hour water and food deprivation. The unit activity rate in stress was higher by 4-6 times than in intact rats (due to an increase in the "fast" cells number and switching of some cells from regular to a burst type of activity). Electrical stimulation of olfactory epithelium decreased the unit activity rate in the most active pinealocytes. The daytime increase in the pineal electrical activity reflects an intensification of secretion of the protein/peptide substances and, probably, serotonin but not the melatonin. Blocking exocytosis with colchicin revealed a close relation of the pinealocytes secretion with their electrical activity. Existence of central (olfactory in particular) mechanisms limiting the pineal activation, was shown.

Animals↗