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Biomedical subjects

M Taniguchi

Publications and source records attributed to M Taniguchi.

At least 739 records · Page 41Linked to original sources
PubMed1984

Transaminative metabolism of L-cysteine in guinea pig liver and kidney.

Transaminative metabolism of L-cysteine was investigated using homogenates of guinea pig liver and kidney. L-Cysteine was transaminated in the presence of 2-oxoglutarate and the homogenate of either liver or kidney. S-(2-Hydroxy-2-carboxyethylthio)cysteine (HCETC) (3-mercaptolactate-cysteine disulfide) was formed by liver homogenate, but the amount was very small. On the other hand, a relatively large amount of HCETC was formed in the presence of kidney homogenate. Transamination between 3-mercaptopyruvate and certain amino acids was catalyzed actively by both liver and kidney homogenates in the presence of L-glutamate. However, more half-cysteine was formed by liver than kidney, and more HCETC was produced by kidney than liver. L-Glutamate was the most potent amino donor, and L-aspartate strongly inhibited the reaction. Results indicate that L-cysteine can be transaminated both in liver and kidney of the guinea pig, and that kidney is more active than liver. 2-Oxoglutarate is the most active 2-oxo acid for cysteine transamination. Oxaloacetate (and aspartate in the reverse reaction) is inhibitory to the reaction. These results are in agreement with the previous conclusion that cysteine aminotransferase is identical with aspartate aminotransferase.

Amino Acids↗
PubMed1984

[Depression of protective mechanisms against ectromelia virus infection in tumor-bearing mice and its prevention by PSK].

Effector mechanisms responsible for protection against ectromelia virus (EMV) including antiviral activity of non-immune macrophages, cytotoxic T cells, antiviral antibody, delayed footpad reaction to viral antigen and interferon induction after viral infection were depressed in BALB/c mice bearing syngeneic Meth A tumors. The degree of viral growth correlated well with the depression of delayed footpad reaction, antibody production and interferon induction. But a control level of these elements could be obtained by pretreatment of tumor-bearing mice, with PSK Cytotoxic activity may not be the principal effector, since cytotoxicity was induced in both normal and tumor-bearing mice to almost the same extent but an explosive viral growth was observed only in the latter. These results suggest that PSK was responsible for restoring the depressed antiviral protective immunity to normal levels in tumor-bearing animals.

Adjuvants, Immunologic↗
PubMed1984

Shared antigenic determinant expressed on various mammalian melanoma cells.

The interspecies cross-reactive melanoma antigen recognized by a syngeneic monoclonal anti-B16 melanoma antibody (M2590) was characterized. The melanoma antigen with cross-species determinants was detected in culture supernates or NP-40 extracts of all melanoma cell lines of mouse, hamster and human origins tested, but not in those of other tumors or normal tissues. Physicochemical analyses using gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the melanoma antigen was a macromolecular complex composed of acidic sialoglycoproteins with a molecular weight of 31,000 daltons. Moreover, the antigens from mouse and human melanoma were shown to have the same molecular weights. The carbohydrate nature of the cross-species determinant was also investigated by treatment with exoglycosidases or pronase; the results suggested that the epitope is composed of carbohydrate side chains with terminal sialic acid.

Animals↗
PubMed1984

Sandwich radioimmunoassay using single monoclonal antibody that detects minute amounts of melanoma antigens from various mammalian species.

A sensitive sandwich radioimmunoassay for the detection of minute amounts of melanoma antigens from various mammalian melanomas was established by using a syngeneic mouse monoclonal anti-melanoma antibody (M2590). The assay system detected the soluble mouse and human melanoma antigens equally at a concentration of 10(3)-10(4) cells/ml because the M2590 antibody was found to react specifically with cross-species melanoma antigenic determinants composed of the carbohydrate side chains of the 31,000-dalton glycoprotein uniquely expressed on various mammalian melanoma cells. Furthermore, human melanomas of various types, such as melanotic, amelanotic, primary, metastatic etc., were successfully detected in an antigen-specific manner. Therefore, the present sandwich assay system using a single monoclonal antibody should be quite useful in clinical applications, especially in the diagnosis of human melanomas.

Animals↗
PubMed1984

Activation of acceptor-suppressor hybridoma with antigen-specific suppressor T cell factor of two-chain type: requirement of the antigen- and the I-J-restricting specificity.

The molecular mechanisms of activation of immunoregulatory T cells were characterized by using two complementary suppressor T cell hybridoma systems: the KLH-specific monoclonal suppressor factor (KLH-TsF), and the inducible acceptor-suppressor hybridoma line with anti-idiotypic receptor for KLH-TsF. It was demonstrated that the identity of the KLH specificity and genetic specificity was required for the TsF-acceptor interaction. These specificities were found to be mediated by the two polypeptide chains of TsF: KLH-binding, Ct-bearing heavy chain and I-J+ light chain. These two chains were essential for stimulation of the acceptor hybridoma. The results were also confirmed by the findings that the mixture of the 11S and 13S mRNA translation products reconstituted the active TsF to stimulate the acceptor hybridoma. Furthermore, the genetic restriction observed was found to be mediated by the I-J+ light chain and to be governed by the gene linked to the H-2 complex but not to the Igh genes. The gene controlling the restriction specificity was strongly suggested to be in the intra-H-2 complex, but not outside of the H-2 complex.

Animals↗
PubMed1984

[Effect of PSK on the recovery of macrophage function and T cell-mediated immunity in tumor-bearing mice].

The effect of PSK on the depressed bactericidal activity of macrophages and delayed-type hypersensitivity (DTH) to Listeria monocytogenes in BALB/c mice bearing transplantable Meth A fibrosarcoma was studied. In tumor-bearing mice pretreated with PSK, L. monocytogenes was cleared rapidly from the circulating blood and bacterial growth in the liver was inhibited effectively in the early phase of infection. This resistance to the infection could be transferred with peritoneal exudate cells (PEC) but not with non-adherent PE cells of PSK-treated mice. In the early phase of infection, tumor-bearing mice developed a lower level of DTH to L. monocytogenes than did nongrafted control mice. However, the control levels of DTH could be obtained by pretreatment of tumor-bearing mice with PSK. These results suggest that the restoration of resistance to L. monocytogenes in tumor-bearing mice by PSK may be ascribed to both prevention of depression or activation of macrophage function and prevention of depression of T cell-mediated immunity.

Animals↗
PubMed1984

Chemical features of an antigen-specific suppressor T cell factor composed of two polypeptide chains.

A [35S]methionine-labelled antigen-specific suppressor factor (TsF) was extracted from a T cell hybridoma by freezing and thawing. It was purified by use of immunoadsorbent columns or plates conjugated with antigens or antibodies, and was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The TsF was found to be composed of two distinct and non-covalently associated polypeptide chains with molecular weights of 45 and 27 kilodaltons (kd). The heavy chain possesses both antigen-binding capacity and constant-region determinants (Ct) detected by monoclonal BALB/c anti-CB-20 antibodies (anti-Ct). The light chain was defined by conventional or monoclonal anti-I-J antibodies [B10.A(5R) anti-B10.A(3R)]. Functional analyses have also shown that the keyhole-limpet-hemocyanin-specific TsF composed of 45-kd and 27-kd molecules purified on plates coated with monoclonal anti-Ct or anti-I-J antibodies suppresses antibody response in an antigen-specific fashion.

Animals↗
PubMed1984

Anti-tumor effects of radiolabeled syngeneic monoclonal anti-melanoma antibodies.

The effect of 131I-labeled syngeneic mouse monoclonal anti-melanoma antibodies on tumor growth in vivo were investigated. The injection of unlabeled antibody had little effect on tumor growth, whereas the anti-tumor activity was considerably increased when the antibody was conjugated with 131I and also when a mixture of two different radiolabeled monoclonal antibodies with distinct specificities was used. The anti-tumor effects of the radiolabeled antibody were transient but significant under the present experimental conditions: melanoma growth was completely inhibited for about 10 days or more after the antibody treatment, but resumed thereafter. Possible mechanisms of escape of the tumor from the therapy with radiolabeled monoclonal anti-tumor antibody are discussed.

Animals↗
PubMed1983

Acceptor-suppressor T cell hybridoma with a receptor recognizing antigen-specific suppressor factor.

An acceptor hybridoma with a receptor that recognizes the keyhole limpet hemocyanin (KLH)-specific suppressor T cell factor (KLH-TsF) was established after the fusion of C57BL/6 splenic T cells enriched with KLH-coated petri dishes. The cloned hybridoma (34S-281) could be specifically activated by stimulation with the conventional KLH-TsF or monoclonal KLH-TsF from three different hybridomas in the absence of the relevant antigen (KLH) and it started to produce another factor that suppresses the antibody response against DNP-KLH in a KLH-specific fashion. The KLH specificity of the TsF was required for activation. The new factor was found not to bind the KLH but to be absorbed with the KLH-TsF-producing hybridoma. It is thus strongly suggested that the acceptor site has a complementary structure (antiidiotype) for the KLH-TsF. Moreover, the idiotypic determinant on KLH-TsF was found to have a structure similar to that on some of the anti-KLH antibodies, since the acceptor hybridoma was specifically killed by the conventional anti-KLH antibodies and complement. Drawing on the above results, the idiotype-antiidiotype network in the conventional antigen system is discussed.

Animals↗
PubMed1983

Experimental biliary obstruction of rat. Initial changes in the structure and lipid content of erythrocytes.

The bile duct was ligated and the resulting changes in the plasma and erythrocyte lipid composition and in the shape of erythrocytes were observed. Electron microscopy at 8th hour after ligation revealed the appearance of spur cells, and on the 7th day target cells began to be observed. The appearance of spur cells was considered to be a reflection of abrupt increases in bile acid and bilirubin levels in the plasma. The conversion of spur cells to target cells which was observed was accompanied by increased levels of cholesterol and phosphatidylcholine in the erythrocytes. Plasma phosphatidylcholine and cholesterol levels were increased immediately after the commencement of ligation. On the other hand, erythrocyte phosphatidylcholine and cholesterol levels only gradually increased when compared to those in plasma, and the maximum value was observed from the 5th to the 7th day. The fatty acid composition of the increased plasma phosphatidylcholine after ligation resembled that of phosphatidylcholine in bile. On the other hand, the fatty acid composition of erythrocyte phosphatidylcholine changed remarkably between the 1st and 3rd days after bile duct ligation. These changes were also reflected by those of phosphatidylcholine in bile. These results led to the conclusion that the appearance of target cells observed in the present study was due to the accumulation of erythrocyte lipids which derived from bile. This is the first report on experimentally induced target cells and the mechanism for their appearance that seems applicable for humans.

Animals↗
PubMed1983

Physiological activity of warburganal and its reactivity with sulfhydryl groups.

Warburganal, a unique dialdehyde sesquiterpene isolated from East African Warburgia plants, showed a strong antifungal activity. However, this growth inhibition in Saccharomyces cerevisiae was reversed with L-cysteine. In addition, warburganal inhibited the alcoholic fermentation of S. cerevisiae while L-cysteine reversed this inhibition. When alcohol dehydrogenase, a sulfhydryl enzyme, was incubated with warburganal, the enzyme activity decreased with time. The decrease was more rapid at alkaline pH. L-Cysteine prevented this enzyme inhibition by warburganal but could not restore the enzyme activity lost already due to warburganal. Warburganal lost its characteristic ultraviolet absorption spectrum in the presence of L-cysteine. The change in absorbance was favored at alkaline pH, indicating Michael reaction type addition of L-cysteine to warburganal. Based on these observations, a variety of physiological activities due to warburganal appear to result from its irreversible reactivity with sulfhydryl groups.

Alcohol Oxidoreductases↗
PubMed1983

The ability of interspecies crossreactive anti-Ia murine alloantibodies to eliminate a subpopulation of human adherent cells responsible for induction of alloimmunity.

Certain anti-Ia murine alloantibodies react with the Ia-positive B cells of almost all mammalian species. In this report, the effect of such murine alloantibodies on the function of accessory cells in induction of human immune responses was studied by using human peripheral blood lymphocytes pretreated with anti-Iak murine alloantibodies and complement. The induction of allogeneic mixed lymphocyte reactions and allogeneic cytotonic T cells was drastically reduced by means of pretreatment of the stimulator population with anti-Ia and complement. When both responder and stimulator were pretreated with these reagents, inductions of the residual responses were completely eliminated. Cells with quite similar characteristics (i.e., adherence to the petri dish and crossreaction with the anti-Ia murine alloantibodies) were also found to be essential in the induction of in vitro T cell proliferative responses to purified protein derivate and concanavalin A. These results seem to indicate that the interspecies crossreactive anti-Ia murine alloantibodies react with the human homologue of murine Ia-positive macrophagelike cells that are recognized as antigen-presenting cells. It is also concluded that, in induction of alloimmunity, Ia-positive adherent cells of the stimulator population are the major source of the stimulation.

Animals↗
PubMed1983

Monoclonal anti-Ia murine alloantibodies crossreactive with the Ia-homologues of other mammalian species including humans.

Two murine monoclonal anti-Ia alloantibodies (ISCR2 and ISCR3) crossreactive with lymphocytes of other mammalian species including humans have been established. These hybridomas were derived from A.TH mice immunized with A.TL lymphocytes, and they reacted with murine Ia antigens, as judged by complement-dependent cytotoxicity assays and chemical analysis. Genetic mapping analysis suggested that ISCR2 recognizes the allotypic determinants shared between the I-A and the I-E molecules. On the other hand, the specificity of ISCR3 was shown to correspond to the serological specificity Ia.7 and directed to the I-E subregion gene product (E alpha). The genetic specificity of ISCR3 was also confirmed by sequential precipitation analysis performed on the internally labeled B10.BR spleen cell antigen. These antibodies showed interspecies crossreactions with non-murine lymphocytes. ISCR2 showed reactivity on human and dog lymphocytes, but not with rat lymphocytes. ISCR3 reacted with human, dog, and rat lymphocytes but not with chicken or frog lymphocytes. Furthermore, ISCR3 was shown to be capable of eliminating a population of cells necessary for induction of human allogeneic killer cells in vitro. Treatment of stimulator cells with ISCR3 and complement drastically reduced the induction of the killer activity.

Animals↗
PubMed1983

Mouse alloantibodies capable of blocking cytotoxic T cell function. IV. Comparative analysis of the blocking effects of anti-Lyt-2 and anti-H-2 antibodies on allogeneic and PHA-mediated killing.

Blocking of cell-mediated lympholysis (CML) by anti-Lyt-2 antibodies was compared with that by anti-H-2 antibodies which most likely inhibit CML by blocking antigen recognition by cytotoxic T lymphocytes (CTLs). Both antibodies were shown to inhibit the early Mg2+-dependent process of killing. Moreover, the anti-H-2-sensitive event was found to be reversible by the antibody as was the case with the anti-Lyt-2-sensitive event, suggesting that the two antibodies block the same event taking place during the Mg2+-dependent stage. Both types of antibody were also shown to be capable of inhibiting the phytohemagglutinin (PHA)-mediated non-specific killing activity of CTLs. However, in the case of anti-Lyt-2 antibodies, available monoclonal antibodies failed to inhibit PHA-mediated killing whereas conventional antisera did. The results thus suggest multiplicity and heterogeneity of Lyt-2 determinants or the existence of multiple products of Lyt-2-linked genes. In addition, an anti-H-2 antiserum also exerted a specific inhibitory effect on PHA-mediated killing. Thus there appears to be a general requirement for involvement of the Lyt-2 molecules on CTLs and major histocompatibility complex (MHC) products on the target cells. The implications of these observations are discussed.

Animals↗
PubMed1983

Effects of riboflavin and selenium deficiencies on glutathione and its relating enzyme activities with respect to lipid peroxide content of rat livers.

Weanling male rats were fed a riboflavin- or selenium-deficient diet for 5 weeks, and the glutathione content and its relating enzyme activities in the livers were examined. The glutathione content and glutathione reductase activity were decreased by deficiency of riboflavin, but not by that of selenium. Glutathione peroxidase activity was increased by addition of selenium to the diet, but without its addition, the activity was higher in the riboflavin-deficient rats than in the riboflavin-sufficient rats, in spite of the increase of lipid peroxides in the former rats. Glucose 6-phosphate dehydrogenase activity was decreased significantly by riboflavin deficiency. In another experiment, riboflavin was intraperitoneally injected into rats fed the diet to which neither riboflavin nor selenium had been added. The glutathione content and activities of glutathione reductase and glucose 6-phosphate dehydrogenase returned to the control level of riboflavin-sufficient rats in 24 h, the lipid peroxide level in 48 h, and the glutathione peroxidase activity, being higher than that in the control rats, in 72 h after the injection, respectively. These findings indicate that the increase of lipid peroxides in the livers of riboflavin-deficient rats is caused by the decrease in the glutathione content as well as glutathione reductase activity rather than by that in the selenium-dependent glutathione peroxidase activity.

Animals↗
PubMed1983

Cell cycle-dependent expression of antigen-binding and I-J-bearing molecules on suppressor T cell hybridomas.

The I-J and antigen-binding chains with constant region determinant (Ct) that compose an antigen-specific suppressor T cell factor were found on the surface of suppressor T cell hybridomas, serologically and morphologically demonstrated by a fluorescence-activated cell sorter (FACS) and immunoelectron microscopic analyses. Moreover, the surface expression of the I-J and Ct-bearing chains fluctuating with the same kinetics depended entirely upon the cell cycle. The maximum expression of these two chains was observed in the early stage of the M phase, and the minimum in the S phase. Similarly, the magnitude of the suppressor activity was maximal in the late stage of the M phase, and was minimal in the S phase. The results therefore demonstrated that there exists good correlation between the cell surface expression of the I-J and Ct-bearing chains and the magnitude of the suppressor activity produced. The antigen recognition units on suppressor T cell hybridomas have serologically and morphologically been characterized by using radiolabeled antigens or monoclonal antibodies against the I-J or Ct on the antigen-binding molecule. Cell-binding assay and radioautographic analysis demonstrated that the suppressor T cell hybridoma possesses the capacity to bind native antigen in an antigen-specific fashion as does the hybridoma-derived, antigen-specific suppressor factor composed of the I-J and the Ct-bearing chains, indicating that the recognition unit on the cell surface is composed of a structure similar to the factor.

Animals↗