Search PubMed⌕ Search

Biomedical subjects

A Ivanova

Publications and source records attributed to A Ivanova.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Morphological changes in the nervous system in lead poisoning. I. Experimentally induced lead neuropathy].

A morphological study on experimental model of lead (Pb) neuropathy (by the method of Pentschev, A., 1966) was described. Dense inclusions in Schwann's cells and satellite cells of the sensory ganglia were found by an electron microscope in the examined peripheral nerves (n. ischiadicus) and sensory ganglia (g. lumbale and g. trigeminale--Gasseri). These finding supported direct toxic action of Pb on these structures and proved their participation in the pathogenesis of developing neuropathy.

Animals↗
PubMed1987

Kainic acid microinjected into the cat raphe dorsal nucleus modulates the somatosensory evoked potentials and their cycles of excitability.

Studies were made on the effect of the neuroexcitatory agent kainic acid, microinjected into raphe dorsal nucleus by glass micropipette and an air pressure system in doses ranging from 0.2 to 24.0 nmol (in volumes from 0.05 microliter to 0.47 microliter), on the somatosensory evoked potentials and their cycles of recovery (excitability) obtained from cortex (primary somatosensory and parietal associative), thalamus (ventral posterolateral nucleus and centre median nucleus), mesencephalic reticular formation and raphe dorsal nucleus. Kainic acid in doses higher than 3 nmol exerted an activating effect on the evoked potentials and their recovery cycles especially in thalamus and mesencephalic reticular formation. The analysis of these electrophysiological parameters revealed that the non-specific structures were involved to a larger extent in the activating effect of kainic acid than the specific ones. The morphological changes were not severe and were limited to a part of the raphe dorsal nucleus neurons. Our data indicate that kainic acid injected into raphe dorsal nucleus modulates (in direction of facilitation) the somatosensory evoked potentials and their cycles of excitability obtained in some brain structures. The results suggest that this nucleus is involved in the somatosensory information processing in a non-specific manner.

Afferent Pathways↗
PubMed1986

Intraraphedorsal kainic acid induces paroxysmal electroencephalographic changes in some brain structures of cats.

In acute experiments on cats the effect of kainic acid microinjected into the raphe dorsal nucleus on the EEG activity recorded from various brain structures was investigated. Kainic acid in doses of 0.2 to 32.0 nmol was injected by glass micropipets and an air-pressure system. The analysis of the EEG and the EEG power analysis in the usual frequency bands (delta, theta, alpha, and beta) revealed an activating to hyperexcitatory effect of kainic acid. This hyperexcitatory effect was manifested by the appearance of paroxysmal EEG patterns of different types which developed in some cases into seizure episodes or an epileptic state. Abnormal EEG changes occurred first in the thalamus and mesencephalic reticular formation. A dose-response relationship existed: the duration of the EEG with pathological patterns increased whereas the latency of their appearance decreased with increase of the dose of kainic acid. Five to seven hours after the injection there were no severe histopathologic changes in the region of the raphe dorsal nucleus. The hyperexcitatory effect of kainic acid on brain excitability might be a result of the excitatory action of kainic acid and of triggering of circuits of neuronal hyperactivity in structures connected with the raphe dorsal nucleus.

Animals↗
PubMed1977

Ultrastructural changes in rat striatum after chronic amphetamine treatment.

Rat striatum is examined electronmicroscopically after chronic (90-day) treatment with 5 mg/kg dl-amphetamine injected intraperitoneally. Disorganization of the cytoplasmic organelles is observed in part of the nerve cells as well as disappearance of the dense core vesicles. Axonal terminals have reduced electron density, mitochondria with different degree of disorganization and synaptic vesicles and accumulated in groups. Single smooth and concentrically arranged membranes may be found in some of the boutons. Electron-dense bodies and lipid vacuoles are observed in the cytoplasm of the pericytes. The alterations are considered to be the result of chronic amphetamine treatment.

Amphetamine↗