[The mechanism of anti-insulin effect of apoprotein B]. / K mekhanizmu kontrinsuliarnogo éffekta apoproteina B.

The existence of common epitope in insulin molecule and apolipoprotein B one was shown by means of enzyme immunoassay. Similar epitopes were revealed in apoB-containing lipoproteins (VLDL and LDL) by dot-immunobinding and immunoelectroblotting. Epitopes locate on the surface of lipoproteins and are not screened by lipids. The existence of common epitopes is the reason of competition between insulin and LDL. The experiments with isolated perfused rat hindquarter demonstrate that insulin increased the glucose uptake by muscle and LDL decreased it. Simultaneous perfusion with LDL and insulin leads to reduced insulin action due to completion for insulin receptors. After the recovery of S-S bounds apoB forms some proteins, containing common epitopes with insulin. The presence of such proteins was shown in lipoprotein-free serum. Apoprotein B and its derivates seem to be insulin antagonists with marked antiinsulin action.

[Lipid contents in blood of healthy subjects and patients with peptic ulcer during regular motor activity of the gastrointestinal tract]. / Soderzhanie lipidov v krovi zdorovykh i bol'nykh iazvennoi bolezn'iu v protsesse periodicheskoi dvigatel'noi aktivnosti pishchevaritel'nogo trakta.

The concentrations of total cholesterol, beta-lipoproteins, and triglycerides were measured three times in 20 to 65 min in venous blood of 45 men (8 normal and 37 patients with peptic ulcer). Lipid concentration in the blood was shown to vary within a wide range in just few minutes, particularly so in normal subjects. In some cases the maximal values surpassed the minimal ones twofold and even more. The chi 2 test helped detect a correlation between the content of cholesterol and triglycerides in the blood and the phase of regular motor activity of the gastrointestinal tract, which was registered by tensotransmitters located in the stomach and small intestine. Soon after the beginning of a new cycle of this motor activity cholesterol concentration in the blood increased and triglyceride level reduced. The phase of the motor activity of the gastrointestinal tract should be taken into consideration when measuring the concentrations of lipids in human blood serum.

[The role of hepatocytes, Kupffer, and endothelial cells of the liver in blood lipoprotein metabolism]. / Rol' gepatotsitov, kupferovskikh i éndotelial'nykh kletok pecheni v obmene lipoproteidov krovi.

The rates of blood lipoprotein adsorption by hepatocytes and nonparenchymal cells (NPC) of rat liver have been quantitatively characterized. It was found that the lipoprotein-adsorbing capacity of NPC is higher than that of hepatocytes: 5.6 times for very low density lipoproteins (VLDL), 4.3 times for low density lipoproteins (LDL) and 14.4 times for high density lipoproteins. Stimulation of the mononuclear phagocyte system by a lipopolysaccharide from Serratia marcescens resulted in a significant reduction of blood serum levels of HDL3, LDL and glucocorticoids. Under these conditions the binding of [125I]HDL to hepatocytes increased, while that to Kupffer's cells decreased considerably. In response to stimulation of liver resident macrophages (Kupffer's cells) the rate of protein biosynthesis in hepatocytes increased together with an increase in the rate of [14C]leucine incorporation into the protein component of the blood serum lipoproteins. Enhanced gene expression in the hepatocytes seems to be associated with the cooperative action of HDL and glucocorticoids. Adsorption of lipoproteins by activated Kupffer's cells is due to the receptor-mediated endocytosis, resulting in a decrease of the binding capacity of these cells for HDL and LDL.

[Changes in blood lipids in humans during long-term ski crossing in the Extreme North]. / Izmenenie lipidov syvorotki krovi u liudei v dinamike dlitel'nogo lyzhnogo perekhoda v usloviiakh krainego severa.

Serum lipids were measured in the men who made two ski crosses in the Far North during polar night. The first trip, which was to train the athletes, took 17 days and the second took 38 days. In both studies, lipid mobilization and utilization increased, which led to changes in the lipid spectrum: decrease of the concentration of LDL and, in the second trip, of VLDL and HDL3, and increase of the concentration of HDL2 and cholesterol HDL. In the second trip, lipids were most intensively utilized: lipolysis enhanced and free fatty acids declined. This was also indicated by an increase of the capillary-venous difference in terms of the total fraction of LDL and VLDL as well as free fatty acids. At the end of the second trip, the positive capillary-venous difference in terms of LDL and VLDL and, accordingly, the negative capillary-venous difference in terms of HDL2 and HDL3 increased. At the end of both trips the synthesis of transport lipids grew; in the most strenuous second trip, their active utilization in the working organs was stronger.