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T Hama

Publications and source records attributed to T Hama.

At least 73 records · Page 4Linked to original sources
PubMed1986

Nerve growth factor and gangliosides stimulate the release of glycoproteins from PC12 pheochromocytoma cells.

PC12 pheochromocytoma cells in monolayer cultures secrete increased amounts of glycoproteins into the medium following the addition of nerve growth factor (NGF) or of brain gangliosides. After a 48-h incubation with 50 ng/ml NGF there is approximately a twofold increase in the total [14C]glucosamine-labeled, ethanol-precipitable cellular material released into the medium. Between 30 and 50% of the radioactivity is associated with a glycoprotein (Gpl) of molecular weight of 52,000; the remaining radioactivity is distributed between five and six major bands. Only a small amount (10%) is associated with a glycoprotein of Mr greater than 200,000 which might correspond to the NGF-induced large external glycoprotein. A substantial increase in the release of the glycoproteins is also seen on the addition of a variety of gangliosides including asialo GMl. This increase is independent of the presence of NGF. GMl and GDlb/GTlb but not GDla stimulate release above the levels seen in the presence of NGF. Addition of GDla (2 micrograms/ml) enhances selectively the release of various glycoproteins between 2.6- and 8-fold. The pattern of glycoprotein secretion is similar to that seen with NGF, although Gp2 (Mr 78,000) is more abundant. Stimulation of release by GDla is not accompanied by neurite outgrowth, suggesting that the glycoproteins are not directly associated with neuritogenesis. The release of these glycoproteins following the addition of NGF or gangliosides may relate to the neurotrophic properties that these two entirely different ligands exert on PC12 cells.

Adrenal Gland Neoplasms↗
PubMed1985

Distribution of Nsp100 and Nsp100 kinase, a nerve growth factor-sensitive phosphorylation system, in rat tissues.

Previous work from this laboratory has shown that in PC12 cells the phosphorylation of a specific soluble protein is decreased by nerve growth factor treatment. The protein, designated Nsp100, and its kinase have been separated and partially purified from PC12 cells. In the present work, the tissue distribution of Nsp100 phosphorylation in 5-day-old and adult rats was studied. In adult rats, phosphorylation of an Nsp100-like protein was observed in brain, adrenal gland, testis, and muscle, but not in liver or kidney. In 5-day-old rats, a similar phosphorylation was observed in brain, adrenal gland, superior cervical ganglia, liver, spleen, kidney, and muscle. In PC12 cells, Nsp100 phosphorylation is completely inhibited by 5 X 10(-5) M Zn2+ and is completely inactivated by treatment at 50 degrees C for 2 min. The phosphorylation of the Nsp100-like protein in both adult and 5-day-old rats showed the same characteristics. Partial purification of Nsp100 and Nsp100 kinase from the brains of 5-day-old rats was carried out using the procedures developed for PC12 cells. Nsp100 and Nsp100 kinase were separated on diethylaminoethyl-Sephacel, and the kinase was eluted with 0.3 M NaCl; the same results have previously been obtained with PC12 cells. Phosphorylated Nsp100 from brain and from PC12 cells was compared by proteolysis on sodium dodecyl sulfate gels; similar peptide patterns were generated from the two samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1985

Suppressor T lymphocyte induction by a factor released from cultured blastocysts.

For the analysis of immunologic escape mechanisms of embryos during the implantation period in mice, the effects of culture supernatant of blastocysts on in vitro responsiveness to alloantigen of mice was investigated. Blastocyst-cultured conditioned medium was prepared by culturing late blastocysts of outbred ICR mice for 5 days. The addition of culture supernatant containing four or eight blastocysts to allogeneic mixed lymphocyte culture inhibited both the MLR responses and the generation of cytotoxic T lymphocytes (CTL). Preincubation of the culture supernatant with lymphocytes syngeneic to the responder cells of MLR induced potent suppressor cell activity in the MLR. The supernatant did not inhibit the activity of CTL at the effector phase, but preinduced suppressor cells obtained by incubation of splenocytes with the supernatant showed almost complete suppression of CTL activity at the effector phase. Both of the suppressor cells, active on MLR and at the generation phase of CTL as well as active at the effector phase, had a surface phenotype of Thy-1+ and Ig-. The suppressive material could be extracted from the eight-cell stage of fertilized ova or blastocysts but not from unfertilized ova, indicating that the production of the factor(s) is dependent on the stages of early embryogenesis. These results suggest that the active induction of suppressor T lymphocytes by the factor(s) released from implanted embryos is one of the protective mechanisms from maternal immunologic attack.

Animals↗
PubMed1984

The utilization of carnosine in rats fed on a histidine-free diet and its effect on the levels of tissue histidine and carnosine.

Carnosine can support the growth of rats fed on a histidine-free diet. Rats fed on the histidine-free diet lost weight rapidly for a few days, then remained at a relatively constant weight for 2 weeks at least. However, rats fed on a 0.90% carnosine diet, which contains histidine equimolar to that in a 20% casein diet, increased their weight at the same rate as rats fed on a 20% amino acid diet simulated with casein. On the other hand, the growth of rats fed on a 5% carnosine diet was about 70% compared with that of control rats fed on the 20% amino acid diet for a 2-week experimental period. Carnosinase activity was not significantly affected in the kidney of rats fed on the histidine-free or the 5% carnosine diet. On the other hand, carnosinase activity in the small intestine of rats fed on the histidine-free diet was significantly increased. Histidine content of serum of rats fed on the histidine-free diet decreased to 1/3 of that of control rats, while that of rats fed on the 5% carnosine diet increased to about 14 times. Carnosine content of rat gastrocnemius muscle increased with carnosine content of diets, followed by an increase of histidine in the muscle. However, carnosinase activity of gastrocnemius muscle was not affected by carnosine in diets.

Animals↗
PubMed1983

Purification and properties of rat brain dipeptidyl aminopeptidase.

Dipeptidyl aminopeptidase, which hydrolyzes the 7-(Gly-Pro)-4-methylcoumarinamide, has been purified from the brains of 3 week-old rats. It was purified about 2,600-fold by column chromatography on CM-cellulose, hydroxyapatite and Gly-Pro AH-Sepharose. This enzyme hydrolyzed Lys-Ala-beta-naphthylamide well with an optimum pH of 5.5. It was inhibited by diisopropyl fluorophosphate, phenyl-methanesulfonyl fluoride, some cations, and puromycin, but was not inhibited by p-chloromercuribenzoate, N-ethylmaleimide, dithiothreitol, EDTA, iodoacetic acid, and bacitracin, indicating that rat brain dipeptidyl aminopeptidase is a serine protease. This enzyme showed a molecular weight of 220,000 by gel filtration and of 51,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The properties of purified rat brain dipeptidyl aminopeptidase were similar to those of bovine pituitary dipeptidyl peptidase II, but the molecular weight and substrate specificity of these enzymes were different.

Animals↗
PubMed1982

Purification of dipeptidyl-aminopeptidase IV from human kidney by anti dipeptidyl-aminopeptidase IV affinity chromatography.

Dipeptidyl-aminopeptidase IV (DAP-IV) was purified 850 fold with a yield of 16.5% from human kidney cortex. Only two chromatographic procedures of DEAE-cellulose and anti DAP-IV Sepharose were used. The purified enzyme was shown to be homogeneous by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. Among various substrates with the structure of X-Y-p-nitroanilide, Lys-Pro-Gly-Pro- and Arg-Pro-p-nitroanilides were hydrolyzed very fast by DAP-IV. Optimum pH of DAP-IV in human kidney was pH 8.7, Km value for Gly-Pro-pNA was 2.51 +/- 0.01 x 10(-4) M and V max was 66.6 +/- 0.7 mumol/min/mg protein. Diisopropylfluorophosphate completely inhibited DAP-IV at 0.1 mM. However, the enzyme was almost unaffected by N-ethylmaleimide, p-chloromercuribenzoate, iodoacetate, phenylmethylsulfonylfluoride, and several metals. The amino acid composition of DAP-IV purified from human kidney was similar to that of DAP-IV purified from pig kidney, liver and intestine. These results indicate that the properties of DAP-IV purified from human kidney are almost same as those from pig kidney.

Antibodies↗
PubMed1982

Purification and properties of beta-alanine aminotransferase from rabbit liver.

beta-Alanine aminotransferase from rabbit liver has been purified 1,700-fold over the initial liver extract. The purified enzyme was shown to be homogeneous by disc electrophoresis and SDS polyacrylamide electrophoresis. The molecular weight of the purified enzyme determined by gel filtration was 95,000 +/- 5,700 and the subunit molecular weight was 48,000 +/- 2,100. The enzyme showed absorption maxima at 282, 330, and 414 nm and contained only 1 mol of pyridoxal 5'-phosphate/mol of dimer. The pH optimum for enzyme activity was 8.8 and the Km values for beta-alanine and 2-oxoglutaric acid were calculated to be 3.9 and 1.4 mM, respectively. The enzyme catalyzed transamination of various omega-amino acids with 2-oxoglutaric acid, which was a favourable amino acceptor. beta-Alanine, gamma-aminobutyric acid, and beta-aminoisobutyric acid, which are naturally occurring substrates, were preferred amino donors, but taurine, alanine, ornithine, spermine, and spermidine were not. 6-Azauracil inhibited the enzyme activity with a Ki of approximately 1.5 mM. From the above properties, beta-alanine aminotransferase from rabbit liver was seen to closely resemble with 4-aminobutyrate aminotransferase from liver and brain.

4-Aminobutyrate Transaminase↗