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Biomedical subjects

M Taniguchi

Publications and source records attributed to M Taniguchi.

At least 775 records · Page 43Linked to original sources
PubMed1981

Monoclonal antibodies that recognize the product controlled by a gene in the I-J subregion of the mouse H-2 complex.

The B cell hybridomas producing monoclonal antibodies (E10, D7, F4, H6, and D4) were established by the fusion of P3U1 or NS-1 murine myeloma cell lines and spleen cells of B10.A(5R) mice hyperimmunized with mitomycin C-treated B10.A(3R) spleen and thymus cells. Two types of monoclonal antibodies specific for the products controlled by a gene in the I-Jb subregion of the H-2 complex were characterized: one specific for the private type of I-Jb determinant, the other recognizing the cross-reactive determinant between the I-Jb and I-Jd products. By using these monoclonal reagents, the I-J-encoded product on the antigen-specific suppressor T cells was found to be expressed on their soluble suppressor factors. Furthermore, the I-Jb products were successfully detected not only on the T cell hybridoma with suppressor activity specific for keyhole limpet hemocyanin (KLH), but also on KLH-primed suppressor T cells enriched by antigen-coated petri dishes and concanavalin A-induced thymocyte blasts of C57BL/6 mice by complement-dependent cytotoxic assays and membrane fluorescence techniques.

Animals↗
PubMed1981

Presence of interchain disulfide bonds between two gene products that compose the secreted form of an antigen-specific suppressor factor.

The secreted form of the suppressor T cell factor specific for keyhole limpet hemocyanin derived from the hybridoma 34S-704 was found to consist of the two distinct polypeptide chains, i.e., the antigen-binding and the I-J-encoded chains. They were linked in covalent association with disulfide bonds. The two chains were cleaved by the reduction with dithiothreitol and were easy to reconstitute the active form of TsF. The association of the two distinct chains was suggested to be essential for the expression of the TsF activity.

Animals↗
PubMed1981

Blood compatibility of hydrophilic polymers.

Blood compatibility has been studied for hydrophilic polymers such as poly(vinyl alcohol) (PVA), its derivative, and polyethylene grafted with water-soluble monomers. The surfaces in contact with electrolyte solutions have been characterized by measuring the zeta potentials. The study of plasma protein adsorption on these polymers has revealed that bovine serum albumin as well as bovine serum fibrinogen adsorbs to a lesser extent as the hydrophilicity of the polymers increases. Platelet deposition and fibrin formation, examined using platelet-rich plasma, have been found to take place less significantly on PVA as well as sodium acrylate- and acrylamide-grafted polyethylene than on nongrafted and acrylic acid-grafted polyethylene. Ex vivo experiments with canine whole blood have shown that formation of thrombus on PVA is less than on siliconized glass but increases upon heat treatment which reduces the hydrophilicity. When PVA tubes of about 1 mm diameter are anastomosed to the carotid artery of rat, the patency rate is found to depend strongly on the anastomotic technique. From the results on the zeta potential and the experiments in vitro and ex vivo it can be concluded that the material having a surface from which solvated, neutral chains are extended into the outer aqueous phase may exhibit excellent resistance to thrombus formation.

Adsorption↗
PubMed1981

A simple and effective method for hemolysis with a hypoxanthine-xanthine oxidase system and alteration of erythrocyte phospholipid composition during the hemolysis.

A very rapid hemolysis was found to be caused by active oxygen species produced by a hypoxanthine-xanthine oxidase system with very low concentrations of hypoxanthine. The addition of superoxide dismutase or catalase inhibited the hemolysis, indicating that O2- and H2O2 participate in this system. The extent of erythrocyte hemolysis was found to depend on the sex of the human donor. The change in phospholipid composition before and after hemolysis in human erythrocytes from donors of each sex was compared by thin layer chromatography. A significant decrease in phosphatidylethanolamine content and a concomitant increase in altered phospholipid fraction were observed in erythrocytes from male donors, suggesting that these erythrocytes were easily attacked by active oxygen species to produce modified phosphatidylethanolamine.

Adult↗
PubMed1981

Effect of bumetanide on p-aminohippurate transport in renal cortical slices.

The inhibitory effect of bumetanide on the accumulation of p-aminohippurate (PAH) in rat kidney slices was investigated. Bumetanide increased the Km value for PAH while the Vmax remained to be constant, indicating a competitive inhibition of PAH uptake by bumetanide in the slices. Addition of bumetanide to the medium increased the efflux of PAH with which the slices were preloaded. These data suggest that the inhibitory effect of bumetanide on PAH accumulation is due to an decrease in the PAH transport to the slices from the medium as well as an increase in the efflux of PAH. The present study suggests that the effect of bumetanide was not mediated by the changes of the intracellular contents of electrolytes, Na+, K+, Ca2+ and Mg2+.

Aminohippuric Acids↗
PubMed1981

Mouse alloantibodies capable of blocking cytotoxic T cell function. III. Studies of the mechanism of blocking of CML by anti-Lyt-2 antibodies.

Attempts were made to analyze the mechanism of action of anti-Lyt-2 antibody in blocking of CML in the absence of complement. Preincubation of killer cells with anti-Lyt-2 antibody followed by washing was found to abrogate the inhibitory effect of the antibody on target cell lysis, whereas an equivalent amount of the antibody present throughout the culture period caused marked inhibition. The failure of pretreatment with anti-Lyt-2 antibody to cause inhibition of CML might be due to rapid turnover of Lyt-2 molecules. Delayed addition of the anti-Lyt-2 antibody to CML cultures decreased the inhibition observed, which indicated that the antibody must be present during early stages of killing in order to exert significant inhibitory effects. The partitioning of CML according to requirements for divalent cations showed that anti-Lyt-2 antibody acts on killer cells during the Mg++-dependent stage of killing. In addition, the antibody was shown to be capable of reversing certain events occurring during this stage. These data are consistent with a role for Lyt-2 molecules during the antigen recognition stage of cell-mediated lysis. However, the exact function of the Lyt-2 molecule remains unknown.

Animals↗
PubMed1980

Cellular consequences in the suppression of antibody response by the antigen-specific T-cell factor.

Cellular events mediated by antigen-specific soluble factor extracted from carrier-primed suppressor T cells (TsF) in the suppressive interaction was studied. Keyhole limpet hemocyanin (KLH)-specific TsF directly acts on KLH-primed, I-J positive, nylon-wool-adherent T cells that have an acceptor site for TsF. The nylon-wool-adherent T cells, after accepting TsF in the presence of specific antigen, generate new suppressor T cells acting as an actual effector cell type. Antigen-specificity and syngeneity at I-J between TsF and acceptor T cells are both required for the induction of new suppressor T cells. Newly induced suppressor T cells, however, suppress both syngeneic and allogeneic responses in an antigen-nonspecific fashion.

Animals↗
PubMed1980

Functional and molecular organisation of an antigen-specific suppressor factor from a T-cell hybridoma.

Thymus-dependent (T) lymphocytes have been shown to have antigen specificity. The antigen receptor on T lymphocytes, in contrast to that on B lymphocytes, does not appear to be of the conventional immunoglobulin (Ig) type. Studies on the antigen-specific factors derived from helper and suppressor T cells (Ts) demonstrated that they possess determinants with antigen binding affinity and products of genes in the H-2 complex (MHC). Furthermore, antibodies against the variable region of Ig heavy chains or idiotypes have been shown to react with T-cell antigen receptors as well as antigen-specific helper and suppressor T-cell factors (TsF). It is, therefore, conceivable that at least two gene products are involved in the structural entity of these receptors: one each coded for by genes in either. To establish the molecular nature of the recognition component of T cells we have used homogeneous TsF from a T-cell hybridoma with a specific function. We report here that the antigen binding and I-J coded molecules on TsF are independently synthesised in the cytoplasm, and are secreted as an associated form of the two molecules; this association is required for antigen-specific suppression of antibody response.

Animals↗
PubMed1980

Effects of riboflavin deficiency on lipid peroxidation of rat liver microsomes.

Increases in cytochrome P-450 and cytochrome b5 and a decrease in NADPH-cytochrome c (P-450) reductase were generally brought about by feeding the riboflavin-deficient diet to young rats (50-120 g body weight) for 5 weeks, whereas no significant changes in these enzymes were observed with rats of 220 g body weight by feeding for 2 weeks. Amounts of lipid peroxides in the serum or the liver tissue and microsomes increased significantly after feeding the deficient diet for 5 weeks, in comparison with the respective control rats. On the other hand, NADPH-dependent lipid peroxidation in the presence of ferric ion and pyrophosphate, assayed as malondialdehyde, was decreased drastically in the liver microsomes of all groups of riboflavin-deficient rats irrespective of the period or body weight of animals. Lipid peroxidation could be detected by addition of EDTA-ferric ion or ferricyanide to the incubation medium, though the formation of malondialdehyde was less than that expected by the activity of NADPH-cytochrome c reductase. NADPH-reduction of nitroblue tetrazolium with liver microsomes was decreased in riboflavin deficiency, and was almost able to be correlated with the activity of NADPH-cytochrome c reductase. Following intraperitoneal injection of riboflavin into the deficient rats, NADPH-dependent lipid peroxidation in the presence of ferric ion and pyrophosphate recovered only to 10% of the control rates at 40 hr after the injection, when cytochrome P-450, cytochrome b5 and NADPH-cytochrome c reductase levels were restored to those of their respective controls. Activities of drug-metabolizing enzymes, aminopyrine demethylase and aniline hydroxylase were decreased by initiation of feeding from the weanling stage, but the activities changed only slightly by feeding from the 120 g of body weight stage.

Animals↗