[Phospholipids and glycosphingolipids in cultured skin fibroblasts from healthy donors and patients with systemic scleroderma]. / Fosfolipidy i glikosfingolipidy kul'tiviruemykh fibroblastov kozhi zdorovykh donorov i bol'nykh sistemnoi sklerodermiei.

A comparative study of phospho- and glycosphingolipids of cultured skin fibroblast from healthy donors and from patients with systemic sclerodermia (SSD) was carried out. It was shown that the total phospholipid content in SSD fibroblasts is elevated. No significant changes in the concentration of neutral glycosphingolipids were observed. The ganglioside composition of SSD cell cultures differs significantly from that of healthy donor cells. The concentration of the gangliosides, GM3 and GM1, is decreased; no ganglioside GD1a was found in SSD fibroblasts. The data obtained are suggestive of changes in the properties of fibroblast surface which can be manifested both in the impaired reception of matrix proteins and in the impairment of basic properties of the membrane. These changes are well correlated with the results of previous studies on the AMP cyclase system.

[Glycosylation of glycoconjugates on thymocyte surfaces]. / Glikozilirovanie glikokon''iugatov poverkhnosti timotsitov.

The ectosialation and ectogalactosylation of mouse thymocyte surface were studied. The incorporation of labeled monosaccharides (N-acetylneuraminic acid and galactose) into cell surface glycoproteins and glycolipids were demonstrated. Identification of glycolipids was carried out. The effect of glycosylation on the immune properties of thymocytes was established.

[Monospecific antibodies against synthetic T-antigen. Characteristics of their specificity and use in the identification of T-antigenic determinants on the cell surface]. / Monospetsificheskie antitela k iskusstvennomu T-antigenu. Kharakteristika ikh spetsifichnosti i primenenie dlia identifikatsii T-antigennykh determinant na poverkhnosti kletok.

Monospecific antibodies directed to a Thomsen-Friedenreich antigen (T-antigen) were obtained using artificial antigen. T-antigen immunodominant alpha-disaccharide Galbeta (1----3) GalNAc alpha 1-(T alpha) and its beta-anomer Gal beta (1----3) GalNAc beta 1-(T beta) were bound to bovine serum albumin (BSA) and cytochrome C (CCC) through a spacer (sp = -O(CH2)3NHCO (CH2)4CO-) by the azide method to give neoglycoproteins T alpha-sp-BSA, T alpha-sp-CCC and T beta-sp-BSA. Anti-T alpha antiserum was obtained by immunization of rabbits with T alpha-sp-BSA and then purified by sequential affinity chromatography on BSA-Sepharose and T alpha-sp-BSA-Sepharose to yield monospecific anti-T IgG antibodies. As elucidated by ELISA method, binding T alpha-sp-BSA to the antibodies was inhibited by T alpha-sp-CCC, T alpha-sp-OEt, asialofetuin, T alpha-OBzl, the activity of the inhibitors decreasing in the above order. Methyl beta-galactopyranoside, benzyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside, disaccharide Gal beta (1----3) GalNAc and H-sp-BSA were inactive. The inhibitory analysis suggests that both disaccharide moiety T alpha- and a definite part of the spacer are important for the binding and that T alpha-OCH2 seems to be the minimal recognized structure. In immunoprecipitation tests the antibodies react with T alpha-sp-BSA but not with T beta-sp-BSA, whereas peanut (Arachis hypogaea) lectin (PNL) precipitated both T alpha- and T beta-sp-BSA. These data suggest the significance of the alpha-galactosaminide bond for the antibody recognition. Desialylated human erithrocites (natural T-antigen) were effectively agglutinated with the antibodies. Murine cortical thymocytes (obtained by agglutination-sedimentation method using PNL) were agglutinated with the antibodies only partially (67%), while these cells as well as the cells unaffected by the antibodies were completely agglutinated with PNL. These results indicate to different contents of glycoproteins (T alpha) and glycolipids (T beta) oligosaccharide determinants on the surface of cortical thymocytes species.

[Comparative study of sialyltransferases in cultured cells of the rat embryo, transformed by DNA bovine adenovirus type 3]. / Sravnitel'noe izuchenie sialiltransferaz v kul'turakh kletok émbrionov krys, transformirovannykh DNK bych'ego adenovirusa tipa 3.

The specific activities of membrane-bound sialyl transferases from six cultures of cells transformed by bovine adenovirus DNA type 3 (BA-3) before and after passage through host animal organism were compared. The sialyl transferase activity was increased with respect to the high molecular weight acceptor, asialylofetuin in the majority of transformed and tumour cultures. Identification of sialylation products by paper chromatography revealed that all cell cultures contain sialyltransferases synthesizing neuraminosyl-alpha (2----6)N-acetyllactosamine. The pH dependence of activities of the membrane-bound enzymes were studied. An additional pH optimum (5.5-6.0) of endogenous activity was revealed in most of transformed cultures. Using isoelectrofocusing of detergent extracts in sucrose density gradient, the presence of multiple forms of the enzyme was revealed in all cultures under study. In most virulent strains, Op2a/4 and OAB2a, the forms possessing a high exogenous activity at pH gradient 6.0-6.5 were activated. The multiple forms of line Op2a/4 were investigated at pH 5.8-6.3 and 7.6-8.0. It was shown that the forms with different pI have different pH optima. A correlation between the changes in the activities of sialyl transferases and the increase of oncogenicity of transformed cells after their passage through host organism was detected only in one group of transformed cells.

[Multiple forms of glycosyltransferases in Golgi complex membrane fractions]. / Mnozhestvennye formy glikoziltransferaz v membrannykh fraktsiiakh kompleksa Gol'dzhi.

The distribution of multiple forms of galactosyltransferase (EC 2.4.1.22) and sialyltransferase (EC 2.4.99.1) from the microsomes and Golgi complex membrane fractions of rat liver was investigated. Three fractions of Golgi membranes, namely GF1, GF2, and GF3, differing in their morphology and marker enzyme activity, were obtained. A simultaneous increase of glycosyltransferases under study was observed in fractions GF3 less than GF2 less than GF1. Using isoelectrofocusing, the presence of at least 6-8 forms of galactosyl- and sialyltransferases in the microsomes and Golgi fraction was revealed. The distribution patterns of multiple forms along the pH gradient for each membrane fraction were found to be identical. However, the ratios of highly active and low active forms were specific for each fraction. The similarity of multiple form spectra for galactosyl-and sialyltransferase suggest their tight functional interaction and a possible "en block" packing of membrane glycosyltransferases.

[Properties of membrane-bound sialyltransferase from rana temporaria liver]. / Izuchenie svoistv membranosviazannykh form sialiltransferaz iz pecheni liagushki Rana temproaria.

It was demonstrated that microsomal membranes from frog liver contain at least two different sialyltransferases involved in the synthesis of alpha 2 leads to 3 and alpha 2 leads to 6 oligosaccharide isomers. Studies on acceptor specificity of the sialyltransferase system with respect to low molecular acceptors revealed its similarity to the mammalian sialyltransferase system. However, sharp distinctions were observed in sialylation of mammalian glycoproteins. It was assumed that that the disaccharide unit of the acceptor oligosaccharide chain is a structural element, which in necessary but not sufficient for glycoprotein recognition by sialyltransferases.

[Lysosomal neuraminidase, beta-galactosidase and beta-N-acetylglucosaminidase of regenerating liver tissue]. / Izuchenie neiraminidazy, beta-galaktozidazy i beta-N-atsetilgliukozaminidazy lizosom regeneriruiushchei tkani pecheni

Neuraminidase (EC 3.2.1.18) beta-galactosidase (EC 3.2.1.23) and beta-N-acetylglucosaminidase (EC 3.2.1.30) were studied in normal and regenerating rat liver. All these glycosidases were shown to be predominantly localized in lysosome rich fraction. The activity of lysosomal neuraminidase in regenerating rat liver increased 24 hours after partial hepatectomy, whereas those of beta-galactosidase and beta-N-acetylglucosaminidase decreased. The presence of inhibitor of neurominidase in regenerating liver homogenate was shown. Actinomycin D and cycloheximide were shown to have no significant effect on lysosomal neuraminidase in regenerating rat liver.

[Soluble and membrane-bound neuraminidase in regenerating rat liver]. / Izuchenie rastvorimoi i sviazannoi s membrami neiraminidaszy v regeneriruiushchei pecheni krys

Two forms of neuraminidase (soluble and membrane-bound) are found in regenerating rat liver. Specific activity of the soluble form was found to be maximal in 18 hours after partial hepatectomy, and that of the membrane-bound form-in 24 hours after the operation. Maximal specific activities of both neurominidase forms from regenerating rat liver considerably exceeded that from intact rat liver, shem-operated liver and also from embryonic and lactating rat liver.