Biomedical subjects
Publications and source records attributed to B N Nikitin.
The authors review the results of estimating platelet spontaneous aggregation by Wu and Hoak's method and by its modifications. They describe a modification of the procedure that essentially improves the accuracy of investigation, is sufficiently sensitive, simple, and rapid. Its informative value was confirmed in experiments with spontaneous platelet aggregation in rabbits with cholesterolemia.
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Active participation of lymphatic system in the reconstruction of cholesterol pool during its passage from the intestinal lymph to the thoracic duct lymph was revealed. This phenomenon depends both on the directional dilution of intestinal lipids in the thoracic duct lymph and enzyme mechanisms of the maintenance of lipid balance occurring with the aid of lecithin-cholesterol-acyltransferase and lipoprotein lipase. The rate of transformation of the cholesterol pool correlates with the volume speed of thoracic duct flow. Walls of the intestine, lymphatic and circulatory systems seem to function within the framework of a single mechanism controlling the adequate status of circulatory lipids.
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The blood plasma cholesterol (CS) level increased by 170% due CS of atherogenic lipoproteins (LP) in dogs that received atherogenic rations including lamb fat (LF) (group 1) during 2 months. In dogs of group 2 that received atherogenic rations including sunflower oil (SFO), the total content of CS in the blood plasma rose only by 50%, the portion of high density LP (HDLP) decreased from 73 to 25% in both groups of animals. LF and SFO produced no effect on the plasma CS level, when the dogs did not receive excessive CS in the ration (groups 3 and 4). SFO induced reduction in the rate of the lecitin-cholesterolacyltransferase (LCAT) reaction, both in normal and excessive CS consumption. Nevertheless, the ratio free CS/CS esters was lowered that denoted the appearance in the blood of CS esters, the nature of which was not associated with the LCAT reaction. In the animals of groups 1, 2 and 3 the share of oleic acid in phosphatidylcholine of HDLP increased (in group 3 this increase was most manifest), while the portion of stearic acid significantly diminished.
Experimental alimentary hypercholesterolemia in conditions of thyroid blocking was attended by accumulation of esterified fatty acids (EFA) in the atherogenic lipoproteins of the blood plasma and lymph in the intestine. Rearrangement of EFA pool depended to a great measure on the reduction of linoleate share in cholesterol phospholipids and ethers. The concentration of free linoleate decreased. Arteriovenous difference in the content of free linoleate was detected only in intact animals. It is supposed that changed parameters of penetration of free linoleate into enterocytes are related to enhanced endocytosis of the blood plasma lipoproteins and to intracellular accumulation of fatty acids, that may be responsible for similarity of EFA composition in hypercholesterolemia. As a result, a part of free linoleate pool, normally engaged in lipid synthesis, is spent for energy purposes. This may predetermine a relative depletion of blood plasma lipoprotein linoleate in hypercholesterolemia.
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Fatty acid composition of various lipids was studied in dog blood plasma from femoral and portal veins as well as in dog lymph from thoracic duct and intestinal tract under conditions of acute experiments. Reverse dynamics of the saturation patterns i.e. the ratio of total saturated and unsaturated fatty acid radicals, was found for cholesterol esters and phospholipids from the lymph of intestinal tract and thoracic duct. More than 3-fold reduction of cholesterol esters saturation in the lymph of thoracic duct depended on an increase in linoleates and oleinates. The data obtained suggest that the active transformation of lipids in the lymphatic system is a results of lecithin-cholesterol-acyltransferase effect.