[Activity of selenium-dependent enzymes in erythroid cells of animals in the postnatal period]. / Aktyvnist' selezalezhnykh fermentiv erytroïdnykh klityn tvaryn u neonatal'nomu periodi rozvytku.

The age dynamics of selenium-dependent enzymes glutathione peroxidase and thyroxine-5'-deiodinases type I and II (D1 and D2 respectively) in bone marrow erythroblasts of new-born, 1-, 3-, 5- and 10-day old piglets as well as influences of hormones (thyroxine, cortisol) selenium and iron on enzyme activities were investigated. The enzyme activities in the pig erythroid cells were established to increase after birth. D1 activity increased in erythroblasts of 3-day old piglets, while augmentation of D2 activity was significant in the cells of 10-day old animals. Glutathione peroxidase and thyroxine-5'deiodinase activities in pig erythroblasts decreased under the influence of thyroxine and hydrocortisone in vivo, and increased after injections of sodium selenite. For comparison, activities of 5'-deiodinases in the cells of some other tissues were also investigated.

[Effect of thyroxine on the activity of some enzymes of energy metabolism in bone marrow myeloid cells and blood neutrophils from piglets]. / Vliianie tiroksina na aktivnost' nekotorykh fermentov énergeticheskogoobmena v mieloidnykh kletkakh kostnogo mozga i neitrofilakh krovi porosiat.

The influence of thyroxine on the activities of enzymes of energy metabolism (hexokinase, 6-phosphofructokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase, cytochrome c oxidase) was investigated in bone marrow myeloid cells and blood neutrophils of 3-10-day old neonatal piglets. Data obtained suggest different responsiveness of energy metabolism enzymes to thyroxine action. Repeated hormone injections resulted in the preferential stimulation of enzymes involved in oxidative stages of carbohydrate catabolism in animal myelocaryocytes, while the activities of anaerobic enzymes in these cells were less affected. At the same time glycolytic enzymes in neutrophil granulocytes showed higher sensitivity to thyroxine action than enzymes catalyzing oxidative stages of energy metabolism.

[Structure and function of thyroid hormone receptors]. / Struktura i funktsii retseptorov tireoidn'ikh gormonov.

The new data concerning the structure of nuclear receptor of thyroid hormone and peculiarities of its functioning as a ligand-dependent transcriptional factor are reviewed. Considerable attention is concentrated on the analysis of mechanisms of receptor interactions with specifical DNA regions which mediate iodothyronine influence on the gene expression and factors that participate in regulation of these mechanisms.

[The effect of thyroxine and insulin on the hemopoiesis in animals during neonatal development]. / Vliianie tiroksina i insulina na protsess krovetvoreniia u zhivotnykh v neonatal'nom periode razvitiia.

The influence of thyroxine and insulin on the share of cell populations, involved in erythro- and myelopoiesis in bone marrow and blood of 1-10-day old pigs, was investigated. After durable injections of thyroxine (4mg per kg body weight every 12 h from the 2nd day of life) a relative share of erythroid cells in haemopoetic tissue of animal bone marrow was seen to increase, while the proliferative activity of myeloid precursors decreased. Under the influence of insulin (after injections 0.15 U insulin per kg body weight every 12 h for 3 days) a relative share of proliferating erythroid cells increased, while that of myeloid cell did not change significantly.

[Insulin binding by erythroid cells of swines]. / Zv'iazuvannia insulinu erytroïdnymy klitynamy svinei.

Insulin binding by erythroid cells of newborn and 1-, 10-, 30-days pigs was investigated. The process intensity in piglets was found to decline in the period from birth to 30 days of life. The obtained changes were determined by the reduced receptors number in high affinity site in early postnatal ontogenesis as well as by decrease of receptor affinity constants in 30-days animals. During investigated period the level of insulin binding by erythrocytes was conditioned by hormone binding ability of "young" erythroid cells, which was found to be high in newborn and decreased considerably in 10-30 days pigs. It was established that postnatal decrease of insulin binding by erythrocytes occurred simultaneously with sharp increase of insulin concentration in animal during the 10-days period after birth. So, it is supposed that insulin may be involved in regulation of its own receptor number in erythrocytes.

[The effect of hypoxic hypoxia on the activity of glycolysis enzymes in rat erythrocytes]. / Vliianie gipoksicheskoi gipoksii na aktivnost' fermentov glikoliza v éritrotsitakh krys.

The oxygen-binding properties of hemoglobin, concentration of 2,3-diphosphoglycerate, activity of carbohydrate metabolism enzymes and kinetics of rat erythrocyte hemolysis have been studied at high altitudes. The hemoglobin affinity to oxygen, glycolysis enzyme activity and erythrocyte membrane resistance are established to increase at the initial period of adaptation. The activation of the pentose-phosphate pathway of the glucose, transformation and inhibition of the glycolytic process in these cells are observed on the 10th day.

[Insulin-degrading neutral protease from plasma membranes of rat liver cells and erythrocytes]. / Insulinrasshchepliaiushchaia neitral'naia proteinaza plazmaticheskikh membran kletok pecheni i éritrotsitov krys.

Insulin-degrading neutral proteinase with molecular weight of 70 kDa was partly purified from the rat liver and erythrocyte plasma membranes. Incubation of membranes with [gamma-32P]ATP resulted in the enzyme phosphorylation. Intensity of this process greatly increased in the presence of insulin (100 microU/ml), and correlated with the elevation of the insulin-degrading activity in proteinase. Ca2+, Mn2+, dithiothreitol, cysteine were shown to have a stimulatory effect on insulin degradation; p-chloromercuribenzoate significantly repressed this process. Phenylmethylsulphonyl fluoride and soybean trypsin inhibitor did not affect the activity of the proteinase. It was concluded that the investigated enzyme was a calpain and may participate in the mechanism of insulin action.

[Oxygen-transport function and carbohydrate metabolism in rat erythrocytes during hypoxic hypoxia and treatment with insulin]. / Kislorodtransportnaia funktsiia i uglevodnyi obmen v éritrotsitakh krys v usloviiakh gipoksicheskoi gipoksii pod vozdeistviem insulina.

Hemoglobin affinity to oxygen, enzyme activity and metabolite concentration of carbohydrate metabolism were determined in erythrocytes of rats which were administered insulin solution. A valid decrease of the hemoglobin value P50 (pressure of hemoglobin half-saturation with oxygen), as well as a decrease of the enzyme activity of 2,3-diphosphoglycerate shunt and increase of the activity of regulatory glycolysis enzymes--hexokinase and pyruvate kinase in erythrocytes with multiple introduction of hormones to animals have been established. Such changes in rat erythrocytes were registered with the simultaneous effect of insulin and hypoxic hypoxia evoked by the "lift" of rats in the altitude chamber to the conditional altitude of 9000 m. It is found out that preliminary injection of insulin considerably increases survivability of rats under hypoxic hypoxia at great altitudes.

[Effect of thyroxine on the hemoglobin affinity to oxygen and 2,3-diphosphoglycerate level in rat erythrocytes]. / Vliianie tiroksina na srodstvo gemoglobina k kislorodu i kontsentratsiiu 2,3-difosfoglitserata v éritrotsitakh krys.

Affinity of hemoglobin to oxygen was studied in rat erythrocytes under conditions of intraperitoneal administration of thyroxin in a dose of 0.4 mg per 100 g of animal weight each 24 h for five days. A significant right shift of the oxyhemoglobin dissociation curve is observed only on the 6th day simultaneously with the increase of the 2,3-diphosphoglycerate level in erythrocytes in the period under study. The results obtained from the study of the thyroxin effect on the respiratory function of hemoglobin permit recommending it as an antihypoxant.