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Biomedical subjects

M Kamei

Publications and source records attributed to M Kamei.

105 records · Page 6Linked to original sources
PubMed1984

Effect of sodium butyrate on induction of ornithine decarboxylase activity in phytohemagglutinin-stimulated lymphocytes.

Effect of sodium butyrate on DNA synthesis and the induction of ornithine decarboxylase (EC 4.1.1.17), a rate-limiting enzyme of polyamine biosynthesis, was studied in phytohemagglutinin (PHA)-stimulated bovine lymphocytes. Millimolar concentrations of butyrate completely inhibited the incorporation of [3H]thymidine into the acid-insoluble fraction and reversibly suppressed the induction of ornithine decarboxylase. Other short-chain fatty acids were much less active than butyrate. These results suggest that the suppression of ornithine decarboxylase activity may be one of the reasons for the inhibition of DNA synthesis with butyrate in bovine lymphocytes, because our previous experimental results have shown that the induction of ornithine decarboxylase closely correlates with the DNA synthesis in growth-stimulated cells.

Animals↗
PubMed1982

Thymidine triphosphate dephosphorylating activity in regenerating rat liver.

The enzyme activity of dephosphorylation of thymidine triphosphate was found in microsomal fraction of rat liver. The enzyme activity decreased at the time when [3H]thymidine incorporation into DNA of regenerating liver increased. When the [3H]thymidine incorporation was suppressed by 1,3-diaminopropane, the enzyme activity remained elevated. These results suggest that the enzyme activity appears to be closely linked to DNA synthesis.

Animals↗
PubMed1982

Inactivation of spermidine N1-acetyltransferase with alkaline phosphatase.

Spermidine N1-acetyltransferase in an extract from phytohemagglutinin-stimulated bovine lymphocytes was inactivated by preincubation with alkaline phosphatase. Inactivation of the acetylase with the phosphatase was totally inhibited by addition of pyrophosphate. These results suggest that spermidine N1-acetyltransferase, the rate-limiting enzyme in the biodegradative pathway of polyamines, is inactivated by dephosphorylation. A similar effect of alkaline phosphatase on the acetylase in an extract from Escherichia coli was also observed. The acetylase has a rapid rate of turnover and the rapid loss of the enzyme activity may be to some extent regulated by the covalent modification.

Acetyltransferases↗
PubMed1981

Purification and properties of guanylate kinase from baker's yeast.

Guanylate kinase (ATP:(d)GMP phosphotransferase, EC 2.7.4.8) was purified about 200-fold with 4% yield from baker's yeast. The enzyme preparation showed a single band on polyacrylamide gel electrophoresis and the molecular weight of the enzyme was calculated to be 25 000 by gel filtration. With ATP as a phosphate donor, the kinase used only GMP as a phosphate acceptor. Km values for ATP and GMP were 0.5 and 0.048 mM, respectively. The enzyme reacted optimally at pH 7.5. The enzyme was labile during storage at 4 degrees C and inactivation was prevented by 20% glycerol.

Adenosine Triphosphate↗
PubMedDate not supplied

Erythrina cristagalli lectin-reactive alpha-fetoprotein-E2: a marker of hepatocellular carcinoma and other malignancies.

A newly isolated lectin Erythrina cristagalli (ECL) was tested for separation of human alpha-fetoprotein (AFP) glycoforms by affinity electrophoresis at 0.5 mg/ml and separated AFP bands were detected by antibody-affinity blotting. Three AFP bands, AFP-E1, AFP-E2 and AFP-E3 in order of increasing affinity, were obtained. Sera from control patients with chronic hepatitis and cirrhosis gave a major band of AFP-E1 and a minor or trace band of AFP-E2 (3.4 +/- 2.3%), while those from patients with mostly advanced hepatocellular carcinomas had increased proportions of AFP-E2 band (16.6 +/- 10.2%). With a cutoff level of 8% (mean + 2SD of AFP-E2 for controls), the sensitivity for hepatocellular carcinoma was 72% at a specificity of 100%. Gastrointestinal tumors had much higher percentages of AFP-E2 and occasionally positive AFP-E3. Most of the yolk sac tumors examined showed AFP-E3 in addition to AFP-E2, although AFP-E3 was a minor band. Thus, AFP-E2 is potentially a clinically useful marker for differentiation of increased AFP in hepatocellular carcinoma and other malignancies from that in precancerous chronic hepatitis or cirrhosis.

Biomarkers, Tumor↗