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Biomedical subjects

T Nitta

Publications and source records attributed to T Nitta.

At least 199 records · Page 11Linked to original sources
PubMed1982

Biochemical signals transmitted by Fc gamma receptors: triggering mechanisms of the increased synthesis of adenosine-3',5'-cyclic monophosphate mediated by Fc gamma 2a- and Fc gamma 2b- -receptors of a murine macrophage-like cell line (P388D1).

The specific binding of IgG2a or IgG2b subclass monoclonal anti-sheep erythrocyte antibodies to P388D1 cell surface Fc gamma 2aR3 or Fc gamma 2bR, respectively, triggered the synthesis of adenosine-3'5'-monophosphate (cAMP) to an approximately same extent by the mechanisms that are apparently unique for each type of Fc gamma Rs. Fc gamma 2aR appeared to trigger directly, upon binding of IgG2a antibodies, the adenylate cyclase system without requiring the participation of guanine nucleotide-binding (G/F) regulatory protein, because the Fc gamma 2aR-triggered cAMP synthesis, which reached maximum within 30 min, was not significantly affected by an uncoupler, Mn++ or by addition of guanosine triphosphate (GTP) analog, 5'-guanylylimidodiphosphate (Gpp(NH)p). In contrast, Fc gamma 2bR appeared to stimulate indirectly the G/F regulatory requiring-adenylate cyclase system by generating prostaglandins, since the cAMP synthesis, which required 90 min to reach plateau after binding of IgG2b to Fc gamma 2bR, was totally suppressed by phospholipase A2 inhibitor (p-bromophenacylbromide) or cyclo-oxygenase inhibitor (indomethacin), partially suppressed by Mn++, and slightly increased by Gpp(NH)p. Furthermore, the inhibition of phagocytic process by cytochalasin D increased cAMP synthesis mediated by Fc gamma 2aR (about 70% at 2 micrograms/ml), but did not affect Fc gamma 2bR-mediated cAMP synthesis. In addition, our data suggested that both Fc gamma 2aR- and Fc gamma 2bR-mediated cAMP synthesis are independent from beta-adrenergic receptor-mediated stimulation of the adenylate cyclase system, since either beta-agonist (isoproterenol) or beta-antagonist (propranolol) did not affect significantly the levels of cAMP produced in response to EA-stimulation.

Acetophenones↗
PubMed1982

Mitogenic activity of a water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii. IV. Synergistic effects of Bu-WSA on Concanavalin A-induced proliferative response of human peripheral blood lymphocytes.

Butanol-extracted water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii was cultured with peripheral blood mononuclear cells (PBM) in the presence of sub- and/or supra-optimal mitogenic concentrations of concanavalin A (Con A). The addition of Bu-WSA resulted in increased tritiated thymidine incorporation above that produced by Con A alone. Bu-WSA by itself is not mitogenic for PBM and in fact produced a decrease in thymidine uptake compared to the control. We investigated the response of subpopulation(s) of PBM to Bu-WSA, Con A and a mixture of Bu-WSA and Con A. Separation of PBM into purified T cells, B cells and macrophages showed that cell-cell cooperation of T cells with B cells or macrophages is necessary for the observed synergistic effect of Bu-WSA with Con A. A marked increase in thymidine incorporation by the mixture of T and B cell populations occurred, while only a small amount of thymidine was incorporated when the B cell population was absent. Mitomycin treatment revealed that the response could be ascribed to the T-cell response with a B-cell helper effect. Moreover, Con A and Bu-WSA appeared to act on the same T cell population. This model may provide unique information about the activation of human peripheral blood T cells compared with the activation of these cells by other mitogens.

Actinomycetaceae↗
PubMed1981

In vitro proliferative response and polyclonal antibody production in spleen cells of immunologically defective CBA/N and C3H/HeJ mice by water-soluble adjuvant (Bu-WSA) extracted from Bacterionema matruchotii.

Mitogenicity and the polyclonal plaque forming cell (PFC)-inducing property of a water soluble-adjuvant extracted from Bacterionema matruchotii by butanol (Bu-WSA) were examined in vitro in the spleen cells of hybrid (CBA/N female X BALB/c male)F1 mice and C3H strain of mice. The hybrid F1 male cells which expressed a CBA/N-defect were unable to respond to Bu-WSA, when assessed by the incorporation of [3H]thymidine into the cells and the generation of anti-trinitrophenyl (TNP)-PFC or autoantibody PFC defined by the anti-bromelain-treated mouse erythrocyte PFC assay. However, hybrid F1 female cells with normal traits responded to Bu-WSA. Cultured spleen cells of bacterial lipopolysaccharide (LPS)-nonresponsive (C3H/HeJ mice responded to Bu-WSA as in the case of cells of LPS-responsive C3H/He mice, and the [3H]thymidine-uptakes and the numbers of PFC in these culture cells increased. Re-extraction of Bu-WSA by phenol did not affect its activities, while the activity of butanol-extracted LPS and C3H/HeJ cells decreased after re-extraction by the same procedure with phenol.

Actinomycetaceae↗
PubMed1980

Mitogenic activity of water-soluble adjuvant obtained from Bacterionema matruchotii.

A butanol-extracted water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii, a gram-positive oral bacterium, is a potent B-cell mitogen for murine lymphocytes in vitro. [(3)H]thymidine uptake of cultured spleen cells of BALB/c mice and nude athymic mice was greatly enhanced by the presence of Bu-WSA. Spleen cells which had been treated previously with rabbit anti-mouse thymocyte serum and guinea pig complement responded to Bu-WSA, whereas thymocytes and nylon wool column-filtered spleen cells were unresponsive to it. It was necessary for the adjuvant to be in the culture for at least 24 h in order to obtain significant lymphocyte activation. As macrophage-depleted spleen cells still responded to Bu-WSA, the proliferative response of lymphocytes seems to be independent of the presence of macrophages. The degree of response of spleen cells stimulated by a mixture of Bu-WSA and lipopolysaccharide (LPS) was very close to the sum of the responses stimulated by Bu-WSA and LPS individually. Spleen cells of LPS-injected mice, which were refractory to LPS, responded to Bu-WSA. On the other hand, the spleen cells of Bu-WSA-injected mice responded to LPS but not to Bu-WSA. Furthermore, the cells obtained from the spleens of mice which had been heavily cobalt 60 irradiated and bone marrow reconstituted 3 weeks in advance responded to LPS but not to Bu-WSA. Therefore, it appears that the cells responding to Bu-WSA were not identical to those responding to LPS.

Actinomycetaceae↗
PubMed1978

Water-soluble adjuvant obtained from Bacterionema matruchotii.

The adjuvant effect of a butanol-extracted water-soluble adjuvant (bu-WSA) obtained from Bacterionemia matruchotii, a gram-positive oral bacteria, was studied on the antibody response at the plaque-forming cell (PFC) level in murine spleens. Intraperitoneal injection of Bu-WSA caused significant increase in direct PFC numbers in spleens 1 to 3 days after the antigenic stimulation with sheep erythrocytes (SRBC). Injection of 100 to 800 microgram of Bu-WSA was effective, and 400 microgram of Bu-WSA seemed to be the optimum for induction of the adjuvant effect. The adjuvant effect was strongest when Bu-WSA was injected at the same time as the SRBC, but some effect was still observed when Bu-WSA was injected 7 days before or 1 day after the immunization. The adjuvant effect of Bu-WSA was greatest at high dose of antigen. The mice injected with Bu-WSA at the time of priming SRBC and then immunized with trinitrophenylated SRBC showed greater anti-trinitrophenyl PFC response than controls without the injection of Bu-WSA. These findings suggest that a part of the adjuvant effect of Bu-WSA depends on thymic cell function and another part does not.

Actinomycetaceae↗
PubMed1976

Isolation of native DNA fragments containing structural genes at the beginning, in the middle or at the end of the coding strand.

A method for the isolation of the DNA fragments containing structural genes at the beginning, in the middle and at the end of the coding strand is described. It involves mechanical or enzymatic shearing, exonuclease treatment, hybridization with mRNA and subsequent retention of DNA-mRNA complex on poly(U)-Sepharose. Hybridization of the DNA fragments with mRNA takes place with high specificity and isolated material is enriched in structural genes. Applications of this method for gene isolation are discussed.

Animals↗
PubMed1973

Production of a new type of acid carboxypeptidase of molds of the Aspergillus niger group.

The ability of 88 fungi, which had been obtained as high-potency strains for acid proteinase production, to produce a new type of acid carboxypeptidase (having on optimal pH of about 3 for hydrolysis of benzyloxycarbonyl-glutamyltyrosine) in surface koji culture was determined. Among the aspergilli, substantial amounts of this new acid carboxypeptidase were produced by Aspergillus saitoi, A. usamii, A. awamori, A. inuii, and A. niger. Maximum yields of acid carboxypeptidase per gram of substrate were obtained by submerged culture in a medium containing 0.9% defatted soybean and 0.6% wheat bran. However, the maximum enzyme concentration per milliliter was obtained with a medium containing 3% defatted soybean and 2% wheat bran. The terminal pH could be controlled by varying the concentrations of soybean oil meal and wheat bran. The maximum enzyme production was reached after 4 days or more at 30 C.

Aspergillus↗