[Lipids of neocortex after X-ray irradiation of the rat head at a dose of 200 Gy].

X-ray irradiation at a dose of 200 Gy with local exposure of the rat head induced the change of the lipid content in the neocortex tissue. The amount of phosphatidylinositol was decreased, the amount of free fatty acids, diglycerols, sphingomyelin was increased, and the amount of cholesterol had a growth trend in 2 h after X-ray exposition. The results testify in favor of participation of phosphatidylinositol- and sphingomyelin-relating signal systems and cholesterol in early stages of the cerebral radiation syndrome.

[The nonmonotonicity changes of ornithine decarboxylase activity in spleen following exposure to gamma-irradiation on rats].

Exposure of rats to ionizing radiation caused in spleen nonmonotonous (as a function of time and of dose) changes in the activity of ornithine decarboxylase [ODC EC 4.1.1.

[The methodological aspects of the nonmonotonous dose-response dependence].

The methodological foundations of two radiobiological conceptions, the target-theory and the structural-metabolic theory in radiobiology, are discussed. According to the target theory the biologically significant structure (target size) exists in cell, and the dose-response dependence is monotonic. In the structural-metabolic theory, the target appears as the unity of the structure and metabolism.

[The effect of X-rays and artificial hypotermia on lipids in rat neocortex].

Lipid content of tissue and of fraction of microsomes in neocortex of Wistar rats was studies under artificial hypothermia, after X-ray irradiation in dose 8 Gy under conditions of normothermia and artificial hypothermia in 48 h. The condition of artificial hypothermia get by cooling of rats to 15-18 degrees C. It was shown, that in fraction of microsomes of hypothermia rats the content of phosphatidylinositol was decreased, and in 48 h after cooling of rats the amount of protein, total and individual phospholipids was increased.

[The effect of hypothermia on the rat radioresistance].

The cooling of Wistar rats up to 15-19 degrees C under a condition hypoxia-hypercapnia increased the radioresistance with a dose reduction factor (DRF) of 1.4. To elucidate the mechanisms of hypothermia radioprotective effect was evaluated the functional state of rat neocortex using a electroencephalogram (EEG) as well as was studied the lipid composition of neocortex under the conditions of both normothermia and hypothermia.

[Non-monotonous dose-response relationship in the region of low doses of ionizing radiation].

The statement about nonmonotony of dose-effect curves as a result of nonmonotony of the time-effect relationship including the field of low doses is discussed. The living cells possess a fundamental property to response to action of different stress agents by oscillatory--nonmonotonous--hanges of metabolism. The systems keeping up homeostasis by direct and feed-back regulation return metabolism to norm.

[Nonmonotonous metabolic response of mammalian cells and tissues to ionizing radiation].

Changes in the activity of ornithindecarboxylase in various tissues and in the amount of catecholamine in rat hypothalamus by the action of acute and chronic ionizing radiation were studied. A nonmonotonous relationship between the metabolic parameters of animal tissues and cells and the radiation dose was revealed. It was assumed that the nonmonotonous character of the dose-response dependence results from the nonmonotonous time course of the metabolic response to irradiation.

Effect of picrotoxin-induced seizures on lipid composition of cortical tissue homogenate and its nuclear fraction in rats.

The content of lipids in rat cortical tissue homogenate and fraction of neuronal nuclei was determined under normal conditions and after picrotoxin-induced seizures. Changes in lipid composition of homogenate and nuclear fraction differed considerably. In homogenate, the content of sphingomyelin, lysophosphatidylcholine, and total phospholipids increased, while the content of free fatty acid remained unchanged; in the nuclear fraction the total phospholipid content decreased, while the concentration of free fatty acids increased.

Effect of chronic gamma-irradiation and beta-carotene on lipid metabolism in presynaptic membranes in rat brain.

Lysophosphatidylcholine is involved in radiation-induced modulation of presynaptic membranes in rat brain. High sensitivity of the cortical integrative functions to chronic low-dose gamma-irradiation is demonstrated. beta-Carotene produced a protective effect during chronic irradiation.

[Behavior reactions and lipids of brain synaptic membranes of rats under chronic exposure to gamma irradiation].

The effects of low level chronic ionising irradiation (12.9 cGy/day on the sensory attention to the stimuli of different modalities (somatosensory, visual, odor) of Wistar rats were studied. Analysis of animals behaviour was made after they had received the different doses of irradiation: 4, 6, 8, 10, 15 and 20 Gy.

[Ornithine decarboxylase in the organs of rats under chronic exposure to gamma radiation at a low dosage rate].

Chronic exposure of rats to gamma-irradiation at the dose rates of 1.1, 2.1, and 12.

[The catecholaminergic system in the hypothalamus in the chronic gamma irradiation of rats].

Drastic changes in the level of catecholamines (dophamine and noradrenaline) in the central regulatory area of the sympathetic-adrenal system-hypothalamus--caused by continuous gamma irradiation of rats were observed. The irradiation was performed with the doses of 9 to 165 cGy at a rate of 1.1 cGy/day and with the doses of 17 to 315 cGy at a rate of 2.

[The lipid composition of the membrane of the brush border in the rat small intestine in the late period after gamma irradiation].

The lipid composition of membrane of the small intestine brush border was studied 1, 2, 3 and 6 months after the whole-body fractionated gamma irradiation of the one-month-old rats of 80 g weight with a dose of 6 Gy (2 Gy x 3 at a week intervals). Three months after exposure the amount of cholesterol, total phospholipids, phosphatidylcholine, phosphatidyl-ethanolamine in brush border membrane was the same as in control. The role of phospholipids and cholesterol catabolism suppression in membrane regulatory function disturbances after irradiation is discussed.

[Lipids from liver microsomes and mitochondria upon acute and chronic gamma-irradiation of rats].

It has been shown that acute gamma-irradiation of rats with 100 Gy and 270 Gy doses when the lipid synthesis in the liver is activated, produces changes in the lipid content in liver cell organelles. The amount of cholesterol and its esters in the microsomal fraction increases after 100 Gy but decreases after 270 Gy irradiation, the phospholipid content being unchanged. In the mitochondrial fraction the lipid content decreases 1 hour after 270 Gy irradiation but is expressed in a lower degree after 48 hours.

[Difference in metabolic pools of cholesterol and free fatty acids of rat thymocyte chromatin and nuclear membranes].

Incorporation of [2-14C]acetate into cholesterol and free fatty acids of nuclear membrane, chromatin, and nuclei of rat thymocytes have been studied in 7 and 45 min of cell incubation. Specific radioactivity of the lipids from the nuclear membrane was lower than that from chromatin. Basing on the results obtained, it should be concluded that the pools of lipids from the nuclear membrane and the chromatin are different.

[The effect of beta-carotene on the cytoplasmic membrane lipids of cells in rats under chronic gamma irradiation].

Chronic gamma irradiation of rats at a dose rate of 12.9 rad/day for 155 days (total dose 20 Gy) did not change the cholesterol level in the brush border membrane of the small intestine. Maintenance of rats on a beta-carotene-enriched diet (daily throughout the irradiation period, at a diurnal dose of 3 mg/kg body weight produced an increase in cholesterol levels in the small intestinal brush border membranes.

[Metabolism of nuclear neutral lipids and rat thymocyte chromatin under normal conditions and after gamma-irradiation].

The levels and specific radioactivities of cholesterol and free fatty acids in nuclei and chromatin of thymocytes from normal and gamma-irradiated (10 Gy) rats have been studied. The radioactivity of the total lipid fraction of gamma-irradiated cells was decreased significantly in the absence of inhibition of [2-14C]acetate incorporation into the total protein and lipid reactions and the [3H]uracil incorporation into the acid-insoluble RNA. The concentration of free fatty acids in the nuclei increased significantly after irradiation.

[The effect of gamma irradiation at sub- and supralethal doses on the lipid composition of the mucosa and of the brush border membrane of the small intestine in rats].

A study was made of the amount of cholesterol and its ethers (phosphatidyl choline, phosphatidyl ethanolamine, sphingomyelin, phosphatidyl serine, and phosphatidyl inositol) in mucosa and membrane of the small intestine brush border 24 h after 4 Gy and 2 h after 20 Gy irradiation. No changes in the lipid content of mucosa and membrane of the brush border were noted after 4 Gy irradiation. Exposure to 20 Gy radiation doubled the number of cholesterol ethers and made the number of individual phospholipids and cholesterol increase by nearly 1.

[Effects of ubiquinone-9 on lipids of nuclei and chromatin of the rat liver under continuous irradiation].

The influence of continuous gamma irradiation on the lipids of nuclei and chromatin of rat liver at a dose-rate of 0,129 Gy/day for 155 days (a total dose of 20 Gy) and by feeding of ubiquinone-9 has been studied. The amount of phosphatidylcholine with phosphatidylserine and phosphatidyl-ethanolamine in liver nuclei of irradiated rats was found to increase. Ubiquinone-9 had a normalizing effect.

[Radioprotective properties of ubiquinones during acute and chronic irradiation of rats].

Protective and therapeutic effect of ubiquinone-8 was demonstrated on rats exposed to 8 Gy radiation. There was a 16-20% increase in the survival rate of the irradiated rats as compared with the controls. The per os administration of ubiquinone-8 during a five-month period in conditions of chronic exposure arrested the radiation-induced accumulation of lipids in rat liver and somewhat improved the dynamics of the body mass growth in the exposed rats.

[Role of rat thymus chromatin lipids in response to the harmful effect of gamma-radiation].

In vitro incubation of thymocytes with [2-14C]acetate results in a more intensive label incorporation into chromatin lipids as compared to nuclear lipids. The deleterious effect of gamma-irradiation leads to specific changes in [2-14C]acetate incorporation into the total fraction of phosphatidylcholine-phosphatidylserine and chromatin sphingomyelin. This is paralleled with an increase in the ratio of specific radioactivities of chromatin cardiolipin and nuclear cardiolipin.