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Biomedical subjects

L I Ivanova

Publications and source records attributed to L I Ivanova.

At least 37 records · Page 2Linked to original sources
PubMed1984

[Change in the properties of plasma membranes of normal and neoplastic cells after incorporation of cholesterol].

It is shown that cholesterol incorporation into the membranes of lymphocytes, lymphoblast leikose cells L1210 and into those of ovary tumor causes an increase in the membrane phospholipid bilayer microviscosity measured by pyrene as a fluorescent probe. An increase in the membrane lipid microviscosity resulted in a decrease in the activity of Na+, K+-ATPase and 51-nucleotidase of the normal and tumor cells. After the injection of the tumor cells with an elevated cholesterol/phospholipid ratio an increase of the life span in the experimental animals as compared with the control group was observed.

5'-Nucleotidase↗
PubMed1983

[Limbico-reticular relations during formation of various motivation responses in rabbits subjected to ethanol administration].

Chronic experiments on rabbits with electrodes implanted into different limbic-midbrain structures were made to study the effects of a single intravenous injection of ethanol (0.5 g/kg) on the background EEG during formation of food motivation and avoidance behavior from the criterion of the power of the main EEG rhythms. Intravenous injection of ethanol resulted in an increase in the power of beta-, alpha- and theta-rhythms in the frontal cortex, and in that of alpha- and theta-rhythms in the occipital area of the neocortex. New patterns of the powers of the main EEG rhythms recorded in animals exposed to ethanol during electric stimulation of the lateral and ventromedial hypothalamus, evoking food motivation and avoidance behavior, as well as during electrical stimulation of the dorsal hippocamp and mesencephalic reticular formation that correlate with changes in the functions of the study limbic-mesencephalic structures attest to profound ethanol-induced abnormalities of the central mechanisms of food motivation and avoidance behavior.

Alcoholic Intoxication↗
PubMedDate not supplied

[Characteristics of the lipid transport system in psoriasis].

Cholesterol of high density lipoprotein (HDL) subfractions (HDL2 and HDL3), activity of cholesterol ester transport protein (CETP), and standard lipoprotein parameters (cholesterol, triglycerides, HDL cholesterol) were measured in plasma of 192 patients with various psoriasis forms, which included simple "distributed psoriasis", erythrodermic and arthropathic psoriasis. Among psoriatic patients unusually high percent of persons with both hypo- and hyper-cholesterolemia was observed. The same situation was observed with frequency of cases with both low and high plasma HDL cholesterol levels, the distribution being depending from disease severity. In contrast to norm, psoriasis patients had big range not only in HDL2 cholesterol level, but also in HDL3 cholesterol. They also had decreased CETP activity. Data obtained suggest the existence of changes in reverse cholesterol transport system in psoriasis, which may influence skin cell proliferation (via control of cell supply with cholesterol).

Arteriosclerosis↗
PubMedDate not supplied

[Alcohol dehydrogenase inhibitors and their effect on major enzymatic systems involved in oxidation of aliphatic alcohols].

Effects of four main inhibitors of rat liver tissue alcohol dehydrogenase (4-methyl pyrasol, dimethyl sulfoxide, amide isovaleric acid and dioxime benzoylacetic aldehyde) were studied. Constants and type of inhibition of these substances were evaluate. Effects of these inhibitors on alternative pathways of aliphatic alcohols oxidation were studied: on microsomal ethanol oxidizing system, catalase, xanthine oxidase and on aldehyde dehydrogenases.

Acetaldehyde↗
PubMedDate not supplied

[Role of substance P in regulating the feeding behavior and the avoidance reaction in the rabbit].

Similar changes in feeding and avoidance reaction in spite of the way of substance P administration (30 mgk/kg intravenously or 14,8 nmol intraventricular) were found in rabbits with electrodes implanted in various limbic-midbrain structures. Feeding was found to be more sensitive to substance P administration, as it was shown by the decrease of excitability of the hypothalamic "feeding center" and abolishing of the inhibitory and facilitatory effects on this center from the dorsal hippocampus and the midbrain reticular formation, correspondingly. New cortical-subcortical integration under substance P was presented in new characteristics of EEG activity in neocortical areas, both background and in response to stimulation of various limbic-midbrain structures. Biochemical data let to suggest that at the neural level substance P led to destabilization of membrane structures in endoplasmatic reticulum and to redistribution of membrane-connected N-acetylneuramine acid which was directly involved in neurotransmission.

Animals↗
PubMedDate not supplied

[Substance P and the ethanol-evoked changes in the independent motivated behavioral reactions of rabbits].

Ethanol (0.5 g/kg) administered intravenously led to alterations in central mechanisms of feeding and escape, elicited by threshold electrical stimulation either of lateral or of ventromedial hypothalamic centers of the rabbit. Subsequent intravenous injection of substance P (30 mcg/kg) restored the excitability of the ventromedial hypothalamus and facilitatory effects on this motivational center of the midbrain reticular formation. The restoration of both inhibitory influences of the dorsal hippocampus and facilitatory ones of the midbrain reticular formation on the excitability of the lateral hypothalamus was also observed after SP administration. Data obtained suggest that oligopeptides could be used to increase the tolerance to ethanol or to cure the negative acute effects of alcohol in motivated behaviours.

Animals↗
PubMedDate not supplied

[Functional characteristics of the adrenals in the ontogeny of male water voles Arvicola terrestris with various fur colorings].

Studies have been made of the effect of colour mutations on the adrenal function in growing male voles. In postnatal life, the level of 11-oxycorticosteroids in the blood exhibited similar changes in brown (wild phenotype) and black (mutant) voles. The highest level was found in 1-2-month animals; a decrease took place to the 6th month which was followed by a secondary increase at the age of 8 months. Corticosteron production in vitro is the highest in brown males 5-month. In black voles, after 2 months the production remains unchanged, being rather high. In 5-, 6- and 8-month voles, corticosteron production in vitro increased, but not decreased after prior incubation. In mutant voles, the adrenals are more sensitive to stimulating effect of ACTH (5 units per 1 g of the adrenals) and inhibitory effect of estradiol (40 ng/100 mg) in vitro.

11-Hydroxycorticosteroids↗
PubMedDate not supplied

[Effect of cholesterol on the physical state and function of lymphocyte membranes].

Effect of gradual increase of cholesterol content in T-lymphocyte membranes on the structure and physical state of plasmic membrane lipids and activities of the membrane-bound enzymes was investigated. The increase in cholesterol content was shown to result in a two-phase change of luminescence parameters of the fluorescent probes dimethylaminochalcone and pyrene, which indicates heterogeneity of cholesterol in the membranes. With the growth of steroid content in the cell membranes, at first, we observed a sharp decrease in the lipid bilayer fluidity and inhibition of Na+, K+-ATPase activity, which at the molar ratio cholesterol/phospholipids 0.6 in thymocyte membranes, remains at the same level. With higher cholesterol concentrations ATPase activity did not change. The effect of cholesterol on ATPase activity was in a good agreement with the effect of membrane lipids on fluidity. It is suggested that two pools of cholesterol molecules exist in the membranes, differing in their effects of bilayer fluidity and functional activity of the membranes.

Ca(2+) Mg(2+)-ATPase↗
PubMedDate not supplied

[Incorporation and release of cholesterol from plasma membranes of hepatocytes and Zajdela hepatoma cells].

Molar ratio of cholesterol/phospholipids was decreased in Zajdela hepatoma cell membranes as compared with rat normal hepatocytes. Microviscosity of lipid bilayer was increased in membranes of normal and malignant cells, while the activity of Na+, K+-ATPase and 5'-nucleotidase was decreased during introduction of cholesterol into the cell membranes. As compared with control groups the duration of life was increased in the group of animals implanted with Zajdela hepatoma cells modified by cholesterol. The data obtained suggest that an increase in microviscosity of membranes in tumoral cells, enriched with cholesterol, might inhibit their mitotic divisions.

5'-Nucleotidase↗