Isolation of periportal and centrolobular hepatocytes by isopycnic centrifugation

Suspensions of rat hepatocytes were separated by Ficoll discontinuous density gradient into four fractions. About 85% of the total quantity of cells sedimented within the range from 1.044 to 1.126 g/ml. The activity of key enzymes of glycolysis and gluconeogenesis were measured to determine the acinar origin of hepatocyte subpopulations. The activity of the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase, in hepatocytes with the density of 1.044 g/ml was twice as high as in hepatocytes with the density of 1.073 g/ml. In contrast, glycolytic enzyme, hexokinase, was 3 times more active in heavy than in light cells. The results indicate that light and heavy cells correspond to periportal and centrilobular hepatocytes, respectively.     

Determination of the fraction composition of blood lipoproteins by the small-angle X-ray scattering technique.

A new method for analyzing the fraction composition of blood lipoproteins (LP) was developed based on the small-angle X-ray scattering (SAXS) technique. The method allows quantitative determination of the contents of basic LP fractions (high-density LP, low-density LP, very low-density LP and their subfractions) in the blood plasma or serum. The results of LP analysis by the new method were compared with electron microscopy, ultracentrifugation and gel electrophoresis data. The results obtained by SAXS correlated with those obtained by traditional methods. The new method for the determination of the LP fraction composition in the blood is rapid (1-1.5 h), uses only one reagent (e.g., sucrose) and features a high accuracy and resolution up to LP subfractions. A total of 0.05 ml of the blood plasma or serum is required for an assay. The assays can be carried out in purified preparations or in the blood plasma or serum. The method developed can be used in clinical practice for diagnostics and in scientific research.     

Change in the activity of the key gluconeogenesis enzymes in the rat liver and kidneys during the action of subextreme and extreme factors on the body]

The activity of glucogenesis key enzymes (phosphoenolpyruvate carboxinase, fructoso-1,6-siphosphatase, glucoso-6-phosphatase) of the rat liver and kidneys was studied simultaneously under the effect of extreme and subextreme factors on the organism. The low initial phosphoenolpyruvate carboxikinase activity in the liver and its high inductivity under extreme conditions suggest a role of this enzyme as limiting link in glyconeogenesis. The activity of phosphoenolpyruvate carboxinase in the kidneys is comparable to that of fructoso-1,6-diphosphatase; it is considerably higher than the activity of glucoso-6-phosphatase. The phosphoenolpyruvate carboxinase activity in the kidneys is 5--6 times higher than in the liver. The activity of phosphoenolpyruvate carboxinase and glucoso-6-phosphatase is increased under the effect of extreme factors, and that of fructoso-1,6-diphosphatase remains unchanged. The lack of clear synchronous changes in the activity of glucogenesis key enzymes in the liver and kidneys indicates that the cells of these organs do not provide the united operon for phosphoenolpyruvate carboxinase, fructoso-1,6-diphosphatase and glucoso-6-phosphatase with common regulation mechanism.     

Characteristics of binding and transport of benzo(a)pyrene by blood serum lipoproteins

Binding and distribution of 3H-benzo[a]pyrene in lipoprotein fraction of rat blood serum were studied. The binding was enhanced in the row: LDL, VLDL, HDL, Kd lipoprotein-benzo[a]pyrene complexes had been calculated by means of tryptophan fluorescence quenching. It was found, that Kd value benzo[a]pyrene complexes with VLD was 1.5 x 10(-6) M, with LDL -6.6 x 10(-7) M and with HDL -4.2 x 10(-6) M. Radiolabeled benzo[a]pyrene uptake by rat organs and tissues was investigated after i.v. injection of benzo[a]pyrene-complexes with LP of different classes. High uptake activity was revealed for liver, adrenals and kidneys, whereas heart, spleen, thymus were characterized by low 3H-benzo[a]pyrene accumulation. Radioactivity distribution pattern was depended on the class of LP used for complexation. Ours data permit to evaluate the participation of lipoproteins in transport and metabolic pathways of xenobiotics in organism.     

ICI 182,780 has agonistic effects and synergizes with estradiol-17 beta in fish liver, but not in testis

Background  

ICI 182,780 (ICI) belongs to a new class of antiestrogens developed to be pure estrogen antagonists and, in addition to its therapeutic use, it has been used to knock-out estrogen and estrogen receptor (ER) actions in several mammalian species. In the present study, the effects and mechanism of action of ICI were investigated in the teleost fish, sea bream (Sparus auratus).     

Mechanisms of interaction of tetrahydrocortisol and its ApoA-I complex with a model DNA regulatory element CC(GCC)5/GG(CGG)5

Interaction of tetrahydrocortisol (THF) and its apolipoprotein A-I (ApoA-I) complex with a CC(GCC)₅/GG(CGG)₅ duplex were studied by IR spectroscopy, which revealed formation of hydrogen bonds between the OH group of the THF A-ring and the C=O groups of cytosine and guanine. In addition, THF formed hydrogen bonds with the PO₂ group of the duplex and with a sugar OH group. THF and ApoA-I interacted with the duplex in the same active site involving the base C=O groups. THF increased the conformational order in the duplex, while the THF-ApoA-I complex induced an order → disorder transition.     

Zinc compounds in multiple- and zinc-polluted soils of the irtysh region near semipalatinsk

Study was given to zinc compounds in multiple- and zinc-polluted light and dark chestnut soils. It is established that the initial relations between the element forms change under any kind of pollution. As the load of both kinds of pollution on the soil increases, zinc accumulates in the most mobile forms. In the case of multiple pollution, the mobility of zinc is much higher than in the case of monoelement pollution. The soils under study differ in their zinc-binding capacity. It was revealed that the basic mechanism of zinc binding in polluted soil is ion-exchange absorption.     

Study of the relationship between the glucocorticoid function of the adrenal cortex and blood lipoproteins]

Single administration of hydrocortisone to rats led to elevation in the blood serum of lipoproteins of very low density; and repeated administration - of lipoproteins of very low density, low density and of high density. Lipoproteins with d less than 1.063 g/ml produced an inhibitory action on the production of steroid hormones by the adrenal glands of rats in vitro.