Functionally Active Gap Junctions between Connexin 43-Positive Mesenchymal Stem Cells and Glioma Cells.

The formation of functional gap junctions between mesenchymal stem cells and cells of low-grade rat glioma C6 cells was studied in in vitro experiments. Immunocytochemical analysis with antibodies to connexin 43 extracellular loop 2 showed that mesenchymal stem cells as well as C6 glioma cells express the main astroglial gap junction protein connexin 43. Analysis of migration activity showed that mesenchymal stem cells actively migrate towards C6 glioma cells. During co-culturing, mesenchymal stem cells and glioma C6 form functionally active gap junctions mediating the transport of cytoplasmic dye from glioma cells to mesenchymal stem cells in the opposite direction. Fluorometry showed that the intensity of transport of low-molecular substances through heterologous gap junctions between mesenchymal stem cells and glioma cells is similar to that through homologous gap junctions between glioma cells. This phenomenon can be used for the development of new methods of cell therapy of high-grade gliomas.

[Mono- and polyspecific glycoconjugates based on synthetic O-antigen determinants of Salmonella and their serological characteristics]. / Mono- i polispetsificheskie glikokon''iugaty na osnove sinteticheskikh O-antigennykh determinant sal'monell i ikh serologicheskaia kharakteristika.

Mono- and polydeterminant synthetic antigens have been prepared via copolymerisation of acrylamide with allyl-, 2-acrylamidoethyl, and p-acrylamidophenyl glycosides of di- and trisaccharides representative of the group-specific Salmonella O-antigenic determinants (0:2, 0:3, 0:4, and 0:9). Serological specificity of the glycoconjugates obtained has been studied in enzyme immunoassay (EIA) using monoreceptor antisera.

Enzyme immunoassay (EIA) test systems for the detection of Salmonella O-antigen.

Four EIA (enzyme immunoassay) test systems for the detection of salmonella O-antigens in various biological tissues were studied. To find the optimum test system two types of affinity purified antibodies were used to coat the microtitre plates: (i) monospecific antibodies isolated on immunoadsorbent bearing synthetic O-antigen factor 4 (O:4; salmonella serogroup B) as ligand, (ii) antibodies specific for lipopolysaccharide (LPS) B isolated from the IgG fraction of hyperimmune sera. The use of affinity purified antibodies led to an increase in the sensitivity of 'sandwich' EIA by an order of magnitude and to improved specificity. Competitive EIA was ten to twenty times less sensitive. It is demonstrated for the first time that salmonella O-antigens can be detected in the sera of animals within a day after challenge. For patients with salmonellosis, O-antigen could be detected after the fifth day of illness, but in the urine and faeces only (not in the blood serum), in 30%-70% of cases. This substantially improves the identification of salmonellosis from among other enteric infections. In competitive EIA, inhibition of standard antibodies by the sera under study was caused not by the presence of O-antigen but by antibodies homologous to the coating antigen. This resulted in "blocking' of the latter and led to false-positive results. The results obtained enable the optimum EIA technique to be selected to improve the serological diagnosis of salmonellosis with both synthetic salmonella O-antigens and LPS.

[Synthesis of determinant disaccharides of O-antigens of Salmonella of serological groups A, B and D1 in the form of glycosides suitable for conversion into artificial antigens via copolymerization]. / Sintez determinantnykh disakharidov O-antigenov Salmonella serologicheskikh grupp A, B i D1 v vide glikozidov, udobnykh dlia prevrashcheniia v iskusstvennye antigeny metodom sopolimerizatsii.

The synthesis of 3-O-(alpha-paratosyl)-, 3-O-(alpha-abequosyl)-, and 3-O-(alpha-tyvelosyl)-alpha-D-mannopyranoses, group-specific disaccharides fragments of the Salmonella O-specific polysaccharides (serological groups A, B, and D1) is described. Disaccharides were prepared in the form of allyl and 2-acrylamidoethyl glycosides suitable for conversion into artificial antigens via copolymerisation.

[Immunochemical characteristics of artificial antigens with Salmonella O-determinants 4 and 9]. / Immunokhimicheskaia kharakteristika iskusstvennykh antigenov s O-determinantami 4 i 9 Salmonella.

Two new synthetic high-molecular protein-free O-antigens have been obtained. These O-antigens are copolymers of synthetic disaccharides with acrylamide. The copolymers of alpha-allylglycosides, abequosyl-(alpha 1----3]-mannopyranose and tyvelosyl-(alpha 1----3)-mannopyranose, with acrylamide have been shown to possess, respectively, the specificity of immunodominant O-factors 4 and 9 characteristic of Salmonella serogroups B and D1. The synthetic O-antigens have proved to possess higher capacity for binding antibodies in the precipitation test and the hemagglutination inhibition test than the corresponding lipopolysaccharides.