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Biomedical subjects

I Matsui

Publications and source records attributed to I Matsui.

At least 73 records · Page 4Linked 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↗
PubMed1984

Induction of ornithine decarboxylase in guinea-pig lymphocytes and its relation to phospholipid metabolism.

Treatment of lymphocytes with exogenous phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3.) derived from Clostridium perfringens at concentrations similar to those which induced ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) activity produced diacylglycerol and phosphatidate. A divalent cation ionophore, A23187, and phytohemagglutinin induced not only diacylglycerol formation, but also ornithine decarboxylase activity. Dibutyryl cAMP inhibited both diacylglycerol formation and ornithine decarboxylase induction to a similar extent in phytohemagglutinin-stimulated lymphocytes, but stimulated them somewhat in ionophore A23187-activated lymphocytes. This suggests that the activation of intracellular phospholipase C and the formation of diacylglycerol is involved in ornithine decarboxylase induction in lymphocytes.

Animals↗
PubMed1983

Induction of ornithine decarboxylase by treatment of guinea pig lymphocytes with phospholipase C.

Treatment of guinea pig lymphocytes with Clostridium perfringens phospholipase C but not with Naja naja snake venom phospholipase A2 increased ornithine decarboxylase activity. The increase in ornithine decarboxylase activity was suppressed by actinomycin D or cycloheximide, suggesting that de novo syntheses of RNA and protein are necessary for the increase in the enzyme activity. These results suggest that the activation of phospholipase C rather than that of phospholipase A2 is responsible for induction of ornithine decarboxylase during lymphocyte transformation.

Animals↗
PubMed1983

Induction of spermidine N1-acetyltransferase by sodium n-butyrate and phytohemagglutinin in bovine lymphocytes.

An increased activity of spermidine N1-acetyltransferase was induced in bovine lymphocytes by stimulation with either sodium n-butyrate or phytohemagglutinin (PHA). The acetylase activity was elevated by 2- to 3-fold 24 h after the addition of butyrate, whereas a similar increase of the enzyme activity was found 48 h after stimulation with PHA. When butyrate and PHA were added to the lymphocyte suspensions simultaneously, the peak of enzyme induction was observed at 24 h after the addition and the increase (9-fold) was found to be more than additive. Since the increases in acetylase activity by both butyrate and PHA were markedly inhibited by actinomycin D or cycloheximide, they appear to have resulted from the synthesis of new protein rather than the release of the enzyme from a cryptic inactive form. The enzyme induced by the two agents was most active with spermidine as a substrate, but spermine was also acetylated to a smaller extent (25% of spermidine). Virtually no acetylation was observed with putrescine. Also, the product formed from spermidine and acetyl CoA was more than 90% N1-acetylspermidine. These results indicate that the acetylases induced by the two agents are similar. Although the addition of indomethacin or 8-bromocyclic AMP to PHA-stimulated lymphocytes caused an inhibition of the enzyme induction, no such inhibitory effect was found in the case of enzyme induction by butyrate. These results indicate that both sodium n-butyrate and PHA induce spermidine N1-acetyltransferase in bovine lymphocytes, but the induction mechanisms are different from each other.

Acetyltransferases↗
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↗
PubMed1982

Conversion of exogenous spermidine into putrescine after administration to rats.

Administration of large, but non-toxic doses of spermidine (0.4-1.25 mmol/kg) led to a substantial increase in putrescine in liver, kidney and a number of other tissues including muscle. The increase in putrescine peaked at 6 h after treatment and was completely prevented by administration of cycloheximide 3 h after the spermidine suggesting that the induction of a new protein was required. This protein is likely to be spermidine N1-acetyltransferase which was induced by the treatment with spermidine and increased 3-4-fold in liver and kidney within 6 h. N1-Acetylspermidine was detected in tissues at this time after spermidine treatment and experiments in which labeled spermidine was given indicated that a substantial fraction of the administered spermidine was converted into N1-acetylspermidine and into putrescine. These results suggest that the rise in putrescine after spermidine treatment is brought about by the production of N1-acetylspermidine which is converted into putrescine by the action of polyamine oxidase. The limiting step in this conversion is the activity of the acetylase which is induced in response to the rise in spermidine content. The acetylase/oxidase pathway, therefore, provides a means by which polyamine levels can be regulated and excess polyamine disposed of.

Animals↗
PubMed1982

Induction of ornithine decarboxylase in guinea pig lymphocytes by the divalent cation ionophore A 23187. Effect of dibutyryladenosine 3',5'-monophosphate.

The divalent cation ionophore, A23187, at a concentration of 0.25 microgram/ml, enhanced influx of Ca2+, activity of ornithine decarboxylase and incorporation of [3H]thymidine into DNA of guinea pig lymphocytes. Combined treatment of cells with A23187 and dibutyryladenosine 3',5'-monophosphate (Bt2cAMP) augmented these three events. A23187 at a concentration of 0.06 microgram/ml was insufficient for induction of ornithine decarboxylase stimulated neither Ca2+ influx nor [3H]thymidine incorporation, but stimulated Ca2+ efflux. A23187 (0.06 microgram/ml) in combination with Bt2cAMP caused a marked induction of ornithine decarboxylase and stimulation of [3H]thymidine incorporation into DNA. When the time of Bt2cAMP addition was delayed after A23187, the stimulation of ornithine decarboxylase activity decreased. Washout of Bt2cAMP from cell culture earlier than 4 h of incubation caused a reduction in the stimulatory effect of Bt2cAMP. These results suggest that raising concentrations of cytoplasmic Ca2+ and cellular cAMP are important to some initial events leading to induction of ornithine decarboxylase and these biochemical changes are obligatory sequential steps for stimulation of DNA synthesis.

Animals↗
PubMed1982

Ring 18 mosaicism in identical twins.

Male identical twins with r(18)/normal mosaicism are reported. Twin 1 has the characteristic manifestations of the r(18) syndrome, but twin 2 shows a normal phenotype. Cytogenetic study of cultured lymphocytes revealed that the proportions of r(18) are 19.7% and 19.2%, respectively. However in the fibroblast cultures, the ring is observed in 51% of cells in twin 1 and in 0% in twin 2. The mechanism of the occurrence of the discrepant phenotypes in the twins is discussed.

Child, Preschool↗
PubMed1982

Induction of spermidine N1-acetyltransferase by dialkylnitrosamines.

Treatment of rats with dimethylnitrosamine (30 mg/kg) or diethylnitrosamine (200 mg/kg) produced a rapid increase in the activity of spermidine N1-acetyltransferase which peaked at values 7-fold greater than did control at 48 hr after exposure. This increase led to a small accumulation of N1-acetylspermidine in the liver but produced a more striking effect on putrescine which increased 30- to 40-fold after 2 days. Most of this increase appeared to be due to the conversion of N1-acetylspermidine into putrescine which is catalyzed by polyamine oxidase. Treatment with the nitrosamines also increased the conversion of spermine into spermidine which replaced the spermidine converted into putrescine. Spermine levels were therefore significantly depressed by treatment with these carcinogens. These results indicate that these hepatocarcinogens bring about an increase in putrescine and in the spermidine/spermine ratio in the liver not only by enhancement of ornithine decarboxylase but also by induction of the spermidine N1-acetyltransferase activity which is the rate-limiting step in the acetylase-oxidase pathway for interconversion of the polyamines.

Acetyltransferases↗
PubMed1981

Effect of inhibitors of protein synthesis on rat liver spermidine N-acetyltransferase.

The increase in spermidine N-acetyltransferase activity in rat liver produced by carbon tetrachloride was completely prevented by simultaneous treatment with inhibitors of protein and nucleic acid synthesis suggesting that the increase results from the synthesis of new protein rather than the release of the enzyme from a cryptic inactive form. Treatment with cycloheximide 2 h after carbon tetrachloride also completely blocked the rise in spermidine N-acetyltransferase seen 4 h later. Such treatment completely prevented the fall in spermidine and rise in putrescine in the liver 6 h after carbon tetrachloride confirming the importance of the induction of spermidine N-acetyltransferase in the conversion of spermidine into putrescine. When cycloheximide was administered to rats in which spermidine N-acetyltransferase activity had been stimulated by prior treatment with carbon tetrachloride or thioacetamide, the activity was lost rapidly showing that the enzyme protein has a rapid rate of turnover. The half-life for the enzyme in thioacetamide-treated rats was 40 min, whereas the half-life for ornithine decarboxylase (which is well known to turn over very rapidly) was 27 min. In carbon tetrachloride-treated rats the rate or protein degradation was reduced and the half-life of spermidine N-acetyltransferase was 155 min and that for ornithine decarboxylase was 65 min. It appears that three of the enzymes involved in the synthesis and interconversion of putrescine and spermidine namely, ornithine decarboxylase, S-adenosylmethionine decarboxylase and spermidine N-acetyltransferase have rapid rates of turnover and that polyamine levels are regulated by changes in the amount of these enzymes.

Acetyltransferases↗
PubMed1981

Trisomy 18q. A case report and review of karyotype-phenotype correlations.

A 2-month-old male infant with partial trisomy 18, 46,XY,der(4),t(q35;q21.1)mat, was presented. Except for atypical facies, he had many of the significant signs of full trisomy 18. Phenotype-karyotype correlations based on the data of our case and those from the literature were discussed. Major features of trisomy 18, such as congenital heart disease, early death, and external malformations, appear to be consistently related to the trisomic state of 18q21. Characteristic congenital heart diseases in trisomy 18 were polyvalvular disease in 100%, membranous ventricular septal defect, patent ductus arteriosus, and high take-off of the right coronary ostium. Pathology of the heart did not differ between full and partial 18-trisomy cases.

Abnormalities, Multiple↗