Significance of endogenous glutathione in realizing the oxygen effect in bone marrow cells

It has been established using hemopoietic bone marrow cells or EHrlich ascites carcinoma cells that endogenous glutathione affects the realization of only those lesions which appear in response to an increase in radioresistance, for example during anoxia. The involvement of glutathione in the realization of the oxygen effect is not limited to the time of irradiation. The effect of glutathione extends to the postirradiation period i. e., it is not determined only by the competition with oxygen for target radicals.     

The arsenolysis reaction in the biotechnological synthesis of ribavirin. The in vitro and in vivo inhibition of influenza A virus replication with a combination of ribavirin and ozeltamivir

The biotechnological method of synthesis of the antiviral drug ribavirin based on the transglycosylation reaction was improved due to the addition of catalytic amounts of sodium arsenate. This approach allows us to hydrolyze the excess natural nucleoside guanosine, a ribose donor, and, hence, made the composition of the reaction mixture less complicated, thus facilitating the process of ribavirin isolation. It was shown that in cell cultures the combination of ribavirin and oseltamivir carboxylate inhibited the replication of the influenza A virus more effectively than each of them alone. Similar results were obtained in experiments on laboratory animals (mouse Balb/c) infected with the influenza A virus H3N2/Aichi/68 strain.     

The strengthening role of <Emphasis Type="Italic">D</Emphasis>:<Emphasis Type="Italic">D</Emphasis> interactions in fibrin self-assembly under oxidation

The effect on ozone-induced oxidation on the self-assembly of fibrin in the presence of fibrin-stabilizing factor FXIIIa of soluble cross-linked fibrin oligomers was studied in a medium containing moderate urea concentrations. It is established that fibrin oligomers were formed by the protofibrils cross-linked through γ-γ dimers and the fibrils additionally cross-linked by through α-polymers. The oxidation promoted both the accumulation of greater amounts of γ-γ dimers and the formation of protofibrils, fibrils, and their dissociation products emerging with increasing urea concentrations, which have a high molecular weight. It is concluded that the oxidation enhances the axial interactions between D-regions of fibrin molecules.     

Formation of protodioscin and deltoside isomers in suspension cultures of Nepal yam (<Emphasis Type="Italic">Dioscorea deltoidea</Emphasis> Wall.) cells

Changes in the content of the furostanol glycosides protodioscin and deltoside, particularly that of the (25S)-isomers of the glycosides, during suspension cultivation of different lines of Nepal yam (Dioscorea deltoidea Wall.) cells of the strain IFR-DM-0.5 has been investigated. The composition of furostanol glycosides has been characterized, and the dynamics of the accumulation of individual glycosides during lengthy subcultivation of cells maintained in flasks or in a barbotage bioreactor has been analyzed. A positive correlation between the growth and accumulation of substances that belonged to the class of furostanol glycosides has been demonstrated for cultured dioscorea cells, whereas the content of some of the individual glycosides varied considerably between the lines of the strain, cultures maintained under different conditions, and even between cells in different phases of the growth cycle. The increased content of (25R)-forms of the glycosides (protodioscin and deltoside) was correlated with a decrease in the cellular growth rate, whereas an increase in culture growth intensity occurred concomitantly to an increase of the amount of (25S)-isomers. This may be indicative of the specific stimulatory effect of (25S)-glycosides, but not the (25R)-forms, on cell proliferation in vitro. Thus, the concentration of (25S)-forms may increase due to the autoselection of cells capable of intensive division during prolonged cultivation.     

Synthesis of [26-2H(3)]brassinosteroids

A number of [26-2H(3)]brassinosteroids were prepared for biochemical studies. The parent, nondeuterated compounds were considered to be biosynthetic intermediates in brassinosteroid biosynthesis. Claisen rearrangement was used to construct the steroidal side chain. Deuterium was introduced by reducing the corresponding intermediates with lithium aluminium deuteride.     

EGF receptor degrades via the proteasome-dependent pathway in A-431 cells

It is known that a lot of cell receptors degrade by ubiquitine-proteasome pathway. Here we show that degradation of the epidermal growth factor (EGF) receptor is proteasome-dependent. Treatment of A-431 cells with lactacystine, an inhibitor of proteolytic activities of 26S proteasomes, induces accumulation of the receptor in cells. Incubation of cell lysates with isolated 26S proteasomes leads to diminishing EGF receptor in these cells. Active (tyrosine phosphorylated) EGF receptor is a target of proteolysis by proteasomes.     

The synthesis of cationic glycerolipid acetals containing aliphatic and heterocyclic bases

1,3-Dioxolane series cationic lipids containing residues of aliphatic or heterocyclic nitrogenous bases were synthesized. The bases were attached to the glycerol backbone either directly (piperazine) or via a spacer group through a thioether bond.