[Dynamics of structural changes in rat liver after single dose of gamma-irradiation]. / Dinamika strukturnykh izmenenii v pecheni krys posle odnokratnogo vozdeistviia gamma-izlucheniia.

Histological changes and alterations in biophysical and biochemical parameters in liver of gamma-irradiate rats have been investigated. The gamma-irradiation of the whole body of rats with a single dose of 1 Gy did not cause any impairments of beam structure of rat liver, but resulted in the lymphocytic infiltrations of portal tracts which were not accompanied by formation of spotty areas of necrosis in adjacent areas of lever parenchyma. gamma-Irradiation stimulated proliferation of the hepatocytes and induced time-dependent mitochondrial structure lesions. Post-irradiation changes in cell cytoplasm appeared as disordering in reticulum-endothelial system, among them enlarging and fragmentation of its cisterns, cytoplasmic vacuolization, enhancement of the number of lysosomes and of the lipid inclusion contents. These facts revealed the mobilization of the additional energy resources for recovery of metabolic processes in rat liver. Post-irradiation increase of the level of the hepatocyte membrane lipid peroxidation products preceded liver morphological alterations. The membrane lipid microviscosity decreased in 1 and 3 days after irradiation. As a result of damages of hepatocyte membrane, the activity of the alanin- and asparagin-aminotransferases in blood serum increased 6 hours after. We can conclude that the whole body single gamma-irradiation with a dose of 1 Gy leads to the reversible but significant damages to the rat liver cell membrane structures. These damages might be the reason of radiation-induced liver morphological alterations.

Generation of NO during oxidation of hemoglobin ferroforms by nitrite.

The oxidation of hemoglobin solutions or erythrocyte suspensions containing a mixture of deoxyHb and oxyHb by NaNO2 (under decreased partial pressure of dissolved O2) resulted in the generation of metHb and nitrosoHb. The maximum amount of nitrosoHb was generated during the oxidation of deoxyHb. An increase in oxygen content was accompanied with increased generation of metHb, which was the only hemoglobin form under aerobic conditions. In the presence of oxygen, GSH was oxidized by NaNO2 to GSSG either in solution of oxyHb or in the structure of erythrocytes. GSH decelerated the oxidation of Hb to metHb due to prolongation of the slow phase and suppression of the autocatalytic phase of the reaction. The oxidation of GSH to GSSG was induced by NO2 radicals and not by NO. The incubation of deoxyHb with S-nitrosoglutathione resulted in its complete conversion to nitrosoHb, and this indicated that NO was released during the spontaneous decomposition of GSNO. The addition of S-nitrosoglutathione to oxyHb resulted in the generation of metHb in the solution.

Interaction of ethanol with blood proteins.

At concentrations arising in alcohol intoxication ethanol was reversibly bound to human serum albumin and hemoglobin. Alcohol altered the conformation and stability of the proteins, reduced the domain-domain interactions in the molecule of albumin and changed the binding of such hydrophobic ligands as ANS and bilirubin.

[Complexes of Cu2+ with pyridoxal-5'-phosphate and human and bovine serum albumin]. / Kompleksy Cu2+ s piridoksal'-5'-fosfatom i syvorotochnymi al'buminami cheloveka i byka.

The copper ion Cu2+ bound to serum albumin in the most strong center stabilizes aldimine bonds formed by PLP with epsilon-NH2 group of 4-Lys and alpha-NH2 1-Asp. The stoichometric ratio of the ternary albumin-PLP-Cu2+ complex is 1:2:1. The imidazole rings of histidine residues are involved in binding of copper ions in the first, second, third centers of the albumin molecule. In this case copper ions increase the binding of PLP with the protein stabilizing Schiff bases produced by epsilon-NH2 group of lysine and PLP. The cooper ion bound to serum albumin in the most strong center forms two types of complexes: with rhombic environment in neutral and alkaline media and axial one at pH less than 5,0. On formation of the ternary complex with PLP the rhombic environment is changed to axial.

[Changes in serum albumin conformation following exposure to ultraviolet radiation]. / Izmenenie konformatsii syvorotochnykh al'buminov pod deistviem ul'trafioletovogo izlucheniiu.

Rapid photolysis of one (the most labile) disulfide bridge in bovine and human serum albumines resulted from the sensitizing action of 212 and 214 tryptophane residues, correspondingly, decomposing practically simultaneously with the disulfide bond. This effect was not observed in 6-8 M guanidine. Conformational rearrangement of the protein globule accompanied by a decrease of the exposed arginine residues was observed after the break of the albumine disulfide bond on NaBH4 by ultraviolet, the exposed lisine residues being unaltered. The intensity of 1,8-anilinonaphtalenosulfonate (ANS) fluorescence decreased by 60-70% after the reduction of the disulfide bond due to the arginine residues being unexposed for the chromophore.