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Biomedical subjects

N Watanabe

Publications and source records attributed to N Watanabe.

At least 1,171 records · Page 65Linked to original sources
PubMed1984

Enhancement of clonal proliferation of mouse mast cells by a tumor-promoting phorbol ester.

Mast cell colonies grew in methylcellulose when mouse spleen cells were cultured for 14 days in the presence of medium conditioned by concanavalin A-stimulated spleen cells. Tumor-promoting phorbol esters, 12-O-tetradecanoylphorbol-13-acetate (TPA) and phorbol-12,13-didecanoate, enhanced the concanavalin A-stimulated spleen cell-conditioned medium-induced colony growth of mast cell progenitors. The effect of TPA on this colony growth was blocked by the addition of two antipromoters of experimental skin carcinogenesis, i.e., retinoic acid and dexamethasone. These results show that TPA has the ability to enhance the clonal proliferation of mouse mast cells and that this effect of TPA is closely related to tumor-promoting activity.

Animals↗
PubMed1983

A new potentiator of insulin action. Post-receptor activation in vitro.

A new potentiator of insulin action, 5-[4-(1-methylcyclohexylmethoxy)-benzyl]thiazolidine-2,4-dione, was tested for activation of insulin action in vitro. The agent (50 mg X kg-1 X day-1) was orally administered to rats for 14 days and adipocytes from treated rats were used to assess insulin-binding, glucose uptake and glucose oxidation. In obese rats, the agent increased glucose uptake and oxidation without any change in insulin binding, whereas in lean or streptozotocin-treated rats it failed to increase glucose metabolism. Fat tissues were cultured with the agent for 24 h and were tested for insulin action. In the presence of insulin (10 ng/ml) in the culture media, the agent increased glucose oxidation in these cells without any change in insulin binding. However, without insulin in the culture media the agent did not increase glucose oxidation. Thus, the agent appeared to potentiate insulin action at the post receptor process.

Adipose Tissue↗
PubMed1983

Inhibition by hemin of in vitro translocation of chicken liver delta-aminolevulinate synthase into mitochondria.

The precursor form of chicken liver delta-aminolevulinate synthase was synthesized in a reticulocyte lysate cell-free translation system and then incubated with the homologous liver mitochondria. The precursor enzyme was incorporated into the mitochondria with an attendant processing to the mature enzyme. In this in vitro experimental system, both the transport and processing of the enzyme were significantly inhibited by the addition of hemin as low as about 3 microM. This provides further support to the view, which had been derived from the studies in vivo, that inhibition by hemin of the translocation of delta-aminolevulinate synthase into mitochondria could be one of the regulatory mechanisms for heme biosynthesis in the liver cells.

5-Aminolevulinate Synthetase↗
PubMed1983

Ligand exchange reactions of diol dehydrase-bound cobalamins and the effect of the nucleoside binding.

The inactive complex of diol dehydrase with hydroxocobalamin was resolved by treatment with SO2-3, followed by dialysis to remove SO2-3, giving the apoenzyme which was reconstitutable into catalytically active holoenzyme upon addition of adenosylcobalamin ("re-activation"). Spectral evidence showed that the enzyme-bound hydroxocobalamin undergoes a Co beta-ligand exchange reaction forming sulfitocobalamin. Sulfitocobalamin was bound to diol dehydrase only loosely, and therefore dissociated from the enzyme. In contrast, neither the enzyme-hydroxocobalamin-5'-deoxyadenosine nor the enzyme-hydroxocobalamin-adenosine complex was resolved and thus re-activated by this procedure. It was shown spectroscopically that the hydroxocobalamin in these complexes does not react with SO2-3, or even with CN-, indicating that the OH group in the Co beta-position was blocked spatially by these enzyme-bound nucleosides. Neither O2-inactivated holoenzyme nor the holoenzyme inactivated suicidally by glycerol or 1,2-ethanediol during dehydration reaction was also re-activated by the same procedure. The complex of the enzyme with cyanocobalamin or methylcobalamin was not resolvable by the SO2-3 treatment. This was because these cobalamins bound to the enzyme were not subject to a ligand exchange reaction with SO2-3.

Cobamides↗
PubMed1983

Suppression of IgE antibody production in SJL mice. V. Effect of irradiation and adult thymectomy on the suppression of IgE antibody production in SJL mice.

Anti-DNP IgE antibody production was low and transient in SJL mice which were immunized with 1 microgram DNP-Nb and 1 mg A1(OH)3. The immunized SJL mice were irradiated (60-540 R) 1 day after challenge. A dose higher than 180 R induced enhancement of anti-DNP IgE antibody production as compared to nonirradiated control mice, suggesting the existence of irradiation-sensitive suppressor cells. Anti-DNP IgE antibody production was suppressed when immunized and irradiated SJL mice were injected with spleen cells from adult-thymectomized SJL mice. The donors of the spleen cells were thymectomized 2 or 4 months previously, and this suggests that the suppressor cells from unprimed mice are long-living T cells.

Animals↗
PubMed1983

delta-Aminolevulinate synthase isozymes in the liver and erythroid cells of chicken.

Antibodies raised against the purified chicken liver delta-aminolevulinate synthase showed a partial cross-reactivity with the chicken erythroid delta-aminolevulinate synthase. delta-Aminolevulinate synthase synthesized in vitro using polysomes from erythroid cells showed a subunit molecular weight of 55,000, whereas the enzyme synthesized in vitro using liver polysomes had a subunit molecular weight of 73,000. delta-Aminolevulinate synthase isolated from mitochondria of erythroid cells showed a molecular weight of 53,000, while the enzyme in liver mitochondria had a value of 65,000. These observations imply that the erythroid delta-aminolevulinate synthase differs from the hepatic enzyme.

5-Aminolevulinate Synthetase↗
PubMed1983

Studies on heterogeneity in ferritin subunits.

Subunits prepared by dissociating rat and human ferritins by acid/urea or SDS can be resolved by isoelectric focusing in urea/Triton gels into many discrete forms. Most of these are not true isosubunits but aggregation artefacts formed during electrofocusing. The distribution of H and L subunit classes in these aggregates indicates that HeLa and heart ferritins contain similar classes of H and L subunits but that one or both of these classes is different in liver and kidney ferritins. To avoid aggregation artefacts, we examined subunits synthesised in vitro from exogenous mRNA. Our results indicate that HeLa and rat liver cells synthesise only one class of L subunit but two classes of H subunit.

Animals↗
PubMed1983

Studies on IgE production in mice. I. Spontaneous suppression of IgE production in SJA/9 mice.

IgE levels after Nippostrongylus brasiliensis infestation were high in all strains of mice examined except in the SJA/9 strain. However, surface IgE levels on B cells were not different from those observed in the SJL strain. Most surface IgE-bearing cells also had surface IgM molecules. We suggest that the surface IgE-bearing cells are precursors of IgE-producing cells. In adoptive transfer, hapten-specific IgE antibody was produced when hapten-primed cells from SJA/9 mice were transferred together with cells from SJL donors infested with N. brasiliensis but not when the cells were from SJA/9 donors. It is suggested that the lack of collaboration between hapten-primed B cells and cells from infested mice is a genetic trait of the SJA/9 strain.

Animals↗
PubMed1983

Effects of emetine on initiation of DNA synthesis in embryonic cells of sea urchin.

The effects of the inhibition of protein synthesis by emetine on the initiation of DNA synthesis and mitosis in the fertilized eggs of the sea urchin, Anthocidaris crassispina, were studied. The initiation of DNA synthesis was completely prevented, and no delayed initiation was observed in eggs in which protein synthesis was completely inhibited by emetine, while delayed initiation of DNA synthesis occurred after prolonged culture in eggs in which protein synthesis was incompletely inhibited by emetine. In both cases, neither mitosis nor cleavage was observed. Synthesis of some protein factor seems to be necessary for the initiation of DNA synthesis.

Animals↗
PubMed1983

Purification and properties of adenosine 5'-triphosphate-dependent deoxyribonuclease from Thermus thermophilus HB8.

An ATP-dependent DNase has been purified from Thermus thermophilus HB8 by a procedure involving streptomycin precipitation, DEAE-cellulose chromatography, Sephadex G-200 gel filtration and heparin-agarose affinity chromatography. ATP-dependent DNase activity was separated into two distinct peaks, Peak A and Peak B, by heparin-agarose affinity chromatography. Each peak fraction was further purified by ATP-agarose affinity chromatography. Peak A and Peak B were eluted from an ATP-agarose column at 0.14 M and 0.28 M KCl, respectively, each as a single peak. Both enzyme activities require ATP and Mg2+ for the degradation of double- and single-stranded DNAs, and degrade denatured DNA about 1.5 times faster than native DNA. The two peaks are optimally active at 69 degrees C and have similar optimal pH ranges from 8.2 to 9.2. The two purified peaks were unstable on storage at -20 degrees C, but were remarkably stabilized by addition of 0.4 mg/ml bovine serum albumin. Ammonium sulfate strongly inhibits the activities of both peaks. The molecular weights of Peak A and Peak B are about 170,000 as estimated by glycerol gradient sedimentation. The average chain lengths of denatured DNA produced by Peak A and Peak B were 4.2 and 3.6, respectively, and the products were terminated by 5'-phosphoryl and 3'-hydroxyl groups. The limit-digested products of denatured DNA produced by Peak B consist of mono-, di-, tri-, tetra-, and pentanucleotides along with some larger fragments. The mode of action of both activities is processive and Peak A does not attack double-stranded circular DNA.

Adenosine Triphosphate↗
PubMed1983

Enhancement of IgE antibody production by ovalbumin aerosol in mice.

The effect of aerosolized ovalbumin (OA) on the induction of IgE antibody production was investigated in BALB/c mice. Enhancement of anti-OA IgE antibody production was obtained after the administration of 10 micrograms OA in mice preexposed to 1% aerosolized OA for 6 or 30 min, and after the administration of 1 microgram OA in mice preexposed to aerosolized OA for 30 min. IgE antibody production could also be induced by preexposure to aerosolized OA at a concentration as low as 0.1%. A carrier effect was observed by preexposure to aerosolized OA using a hapten-carrier system. In the latter system, whole body irradiation (200 R) could not enhance IgE response, suggesting that irradiation-sensitive suppressor T cells might be generated in insufficient amount or not at all by aerosolized OA. Preexposure to aerosolized dinitrophenol-OA could not enhance anti-dinitrophenol IgE response. These results suggest that the exposure to aerosolized antigen primed preferentially T helper cells.

Aerosols↗
PubMed1983

Evidence of the lack of receptor-mediated insulin degradation in human cultured lymphocytes (RPMI-1788 line).

We studied insulin degradation in human cultured lymphocytes (RPMI-1788 line) with a small but significant number of lysosomes under the electron microscope. Insulin degradation determined by the TCA solubility method was 64.6 +/- 1.2% (mean +/- SEM) at a trace concentration after the incubation with 2.0 x 10(7) cells (4.0 x 10(7) cells/ml) for 60 min at 37 degrees C. Because insulin degradation was 54.6 +/- 7.0% in the cell-free buffer in which 2.0 x 10(7) cells were previously incubated, most of the insulin was degraded outside of the cells. Gel filtration of the radioactive materials also revealed that most of the labeled insulin in the medium was degraded, and the main peak of the cell-associated radioactivities was intact labeled insulin. Chloroquine, a lysosomotropic agent, failed not only to increase insulin binding but also to decrease the insulin degradation. Other lysosomal protease inhibitors, antipain and leupeptin had also no effect on insulin degradation. In contrast, bacitracin (500 micrograms/ml) significantly decreased the insulin degradation analyzed by TCA solubility, receptor-rebinding, and the gel filtration method. These results suggest that insulin molecules are degraded by the enzymes leaked from the cells. The non-receptor mediated process, which is the bacitracin sensitive pathway, might be a general mechanism of insulin degradation in human cultured lymphocytes in vitro.

Bacitracin↗