[Influence of anxiogenic stress upon severity of alloxan-induced pancreatic and hepatic damage].

4 episodes of immobilization stress caused anxious and depressive behavioral disorder in rats, accompanied by decreased sensitivity of pancreatic tissue to alloxan-induced damage, and simultaneously increased sensitivity of hepatic tissue to alloxanogenic inflammatory effect. The latter shifts were accompanied by a more pronounced hyperglycemia. The paper discusses a probable role of hepatitis in hyperglycemic response to alloxan challenge associated with stressogenic anxiety.

Activation of apoptosis as a mechanism of thymus involution during repeated immobilization.

Lymphopenia preceded involution of the thymus during daily immobilization for 1 h. Hypoplasia of the thymus was associated with induction of apoptosis.

[Effect of rarely repeated immobilization episodes on hypoxia-tolerance and anxiogenic stress severity].

4 episodes of immobilization stress (60 minutes, once 72 hours) led to diminution of hypoxia tolerance and anxiety-depressive disorders of behavior. The later shifts were associated with decrease of IL-4 concentration and simultaneous increase of IL-6 level in blood serum. The stress-induced behavioral shifts appeared to correlate with IL-4 concentration in blood of stress-sustained rats.

[Effects of triamcinolone acetonide on leukocyte distribution in blood system, mononuclear liver infiltration, and immune response under conditions of stress-induced hypoxia in rats].

The effect of triamcinolone acetonide (2 mg/kg) on the distribution of morphologically mature leukocytes in the blood system, the mononuclear liver infiltration, and the immune response was studied in rats under conditions of stress-induced hypoxia. Administered under these conditions, the drug produces a less pronounced effect on the content of circulating lymphocytes, the lymphoid cell number in the bone marrow, and the number of hepatocytes and monocytes/macrophages in the liver. However, the post-stressor immunodepressant effect of triamcinolone acetonide was increased and accompanied by the development of hepatic damage.

The effects of anxiogenic stress on glucocorticoid sensitivity, glucose tolerance, and alloxan resistance in rats.

Four sessions of immobilization stress induced anxiogenic behavioral disorders in rats, which were accompanied by decreases in glucocorticoid sensitivity, increases in MAO-B activity in brain tissue, increases in tolerance to glucose loading, and decreases in resistance to acute hypoxia. Alloxan diabetes was accompanied by a decrease in behavioral activity of rats in the open field test, with an increase in cerebral MAO-B activity. Preceding anxiogenic stress increased the extent of the alloxan-induced increase in cerebral MAO-B activity and the accompanying abnormalities in the rats' behavior, and also potentiated the hyperglycemic effect of alloxan.

[DNAses of the cell nuclei: Mn2+-dependent endonuclease]. / DNKazy kletochnykh iader: Mn2+-zavisimaia éndonukleaza.

Comparison of catalytic properties of a Mn2(+)-dependent and a Ca2+, Mg2+ dependent endonucleases of rat liver cell nuclei was carried out. The Mn2(+)-dependent endonuclease has Mr 31 kDa by SDS-PAAG-electrophoresis; pH optimum 5.5; calcium-magnesium synergism less than 3 in rat liver DNA, RF M13 DNA and phage M13 DNA. The rate of hydrolysis of single strand and double strand circular DNA was the same. The Mn2(+)-dependent endonuclease split DNA by double hit manner, and didn't change the manner in the presence of different divalent cations. Ca2+, Mg2(+)-dependent endonuclease has pH optimum 6.5; calcium-magnesium synergism up to 40 in rat liver DNA and 175 in RF M13 DNA. The rate of hydrolysis of single strand DNA was higher than double-strand DNA.

[Cell nuclear DNases: multiplicity and heterogeneity]. / DNKazy kletochnykh iader: mnozhestvennost' i geterogennost'.

In order to determine the ratio of activities of major endonucleases of rat liver chromatin, a stepwise fractionation of cell nuclear extracts by chromatography on phosphocellulose and gel filtration through Toyopearl HW60 was carried out. This procedure resulted in partially purified preparations of Ca2+,Mg2+-dependent endonuclease (55 +/- 10 kD), Ca2+,Mg2+-dependent endonuclease (30 +/- 10 kD), Mn2+-dependent endonuclease (30 +/- 5 kD) and acid cation-independent endonuclease. The Ca2+,Mg2+-dependent endonuclease with Mr of 55 +/- 10 kD made up to 57% of the nuclear extract activity in the presence of Ca2+ + Mg2+ and revealed a high calcium-magnesium synergism. Under the same experimental conditions, the 30 +/- 10 kD enzyme made up to 33% of the nuclear extract activity and revealed a low synergism. The activity of Mn2+-dependent endonuclease made up to 26% of the total nuclear extract activity in the presence of Mn2+, that of acid endonuclease--11% of the extract activity in 1 mM EDTA at pH 5.0. It was assumed that the low molecular weight Ca2+,Mg2+-dependent endonuclease represents a product of limited proteolysis of high molecular weight Ca2+,Mg2+-dependent endonuclease.

[The activity of nuclear endonucleases and topoisomerases in the liver of rats and in diethylnitrosamine-induced tumors]. / Aktivnost' iadernykh éndonukleaz i topoizomeraz v pecheni krys i opukholiakh, indutsirovannykh diétilnitrozaminom.

The DNA endonuclease (Aendo) and DNA topoisomerase (Atopo) activities in liver nucleus extracts of normal rats, in DENA-induced hepatomas and in liver tissues around tumours were investigated. The profile of nuclear endonucleases measured in the presence of 2 mM CaCl2 + 5 mM MgCl2, or 5 mM MnCl2, or 5 mM MgCl2, or 2 mM CaCl2 (pH 7.4), or I mM EDTA (pH 5.0) was different in normal and tumour tissues. Mn2+-dependent endonuclease was the main endonuclease in the tumour tissue, whereas Ca2+, Mg2+-dependent endonuclease was the main one in the normal liver and in the tissue around the tumour. An increase in the Mn2+-dependent endonuclease activity correlated with a decrease in the hepatoma differentiation level. Atopo of types I and II increased in the tissue around the tumour. Aendo and Atopo of cellular nuclei decreased in animals given DENA without the liver tumour.

Bivalent cation and ATP requirements of endonucleases from rat liver nuclei.

The distribution of different types of DNase in rat liver nuclei was determined after a purification procedure involving ion exchange chromatography and gel filtration. As major enzymes Ca2+, Mg2+-dependent endonuclease, Mn2+-dependent endonuclease and an acid endonuclease were identified, sharing 60, 20 and 10% of the total activity, respectively. Mn2+-dependent endonuclease is a novel enzyme with a molecular mass of 30 +/- 5 kilodaltons. The synergistic effect of Ca2+ and Mg2+ ions for the Mn2+-dependent enzyme was lower by an order of magnitude than that of the Ca2+ and Mg2+-dependent endonuclease. The Ca2+ and Mg2+-dependent nuclease activity represents a heterogeneous population of enzymes. One of the cation dependent enzymes (Mr 25 +/- 5 kD) is stimulated by ATP the ATP optimum being 0.1 mM and the Mg2+ requirement 1 mM. The ATP-dependent endonuclease belongs to the minor endonucleases separable from the major ones.

[Mn2+-dependent endonuclease activity of chromatin]. / Mn2+-zavisimaia éndonukleaznaia aktivnost' khromatina.

The endogenous endonuclease activity of chromatin in isolated rat liver nuclei in the presence of Mn2+, Mg2+ and Ca2+ + Mg2+ was studied. The existence of a Mn2+-dependent endonuclease activity not coupled with the Ca2+, Mg2+-dependent endonuclease was demonstrated, which was weaker than the former one in isolated cell nuclei but higher than in the preparation of Ca2+, Mg2+-dependent nuclease obtained by gel filtration through Toyopearl HW 60F. The Mn2+-dependent splitting of chromatin predominantly occurs at linker DNA of distal parts of chromatin loops. A split-off of purified DNA was more universal than in the presence of Ca2+, Mg2+-dependent endonuclease; the hydrolysis rate of native and denaturated DNA appeared to be the same.

[Dinucleosome as a product of initial chromatin cleavage by endogenous nucleases]. / Dinukleosoma kak produkt nachal'nogo rasshchepleniia khromatina éndogennymi nukleazami.

The ability of nucleic endonucleases to recognize dinucleosomal level of chromatin structure was studied. Rat liver chromatin endonucleases were shown to be capable of DNA cleavage at dinucleosome linkers. The cleavage was observed mainly at initial stages of chromatin autohydrolysis, i.e. up to 10-20th min of incubation in the medium containing 5 mmol of magnesium chloride and 2 mmol of calcium chloride. Thus, mononucleosomal DNA in dinucleosomes and other even chromatin subunits was larger and more homogeneous than in odd subunits. The cleavage of autodigested chromatin by bovine spleen and snake venom exonucleases and by nuclease S1 has shown that dinucleosomal structure is independent of differences in the length of internal and external dinucleosome linkers. The initial endonucleolysis appears to be characterized by different accessibility of the linkers for chromatin nucleases.

[Conditions for initial chromatin endonucleolysis and the characteristics of its products]. / Usloviia nachal'nogo éndonukleoliza khromatina i kharakteristika go produktov.

The restricted initial autohydrolysis of chromatin is used for obtaining its matrix-active fractions. Application of the method for isolating cell nuclei in the presence of 10 mM CaCl2 makes it possible to appreciably inhibit the cleavage of chromatin DNA in the course of isolation, namely to 0.9% according to the acid-soluble fraction. It is shown that at the initial stages of autohydrolysis the method of solubilization is by one order of magnitude more sensitive as compared to the measurement according to the acid-soluble fraction. Initial autohydrolysis is characterized by rapid increment of the amount of the solubilized fraction, delayed formation of mononucleosomes and by the capacity to a 20% activation in the presence of 10(-5) M histamine.