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Biomedical subjects

S Otani

Publications and source records attributed to S Otani.

At least 325 records · Page 18Linked to original sources
PubMed1984

Phorbol esters stimulate spermidine/spermine N1-acetyltransferase activity in mitogen-stimulated bovine lymphocytes.

Phorbol 12-myristate-13-acetate (PMA) is shown to induce spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme of polyamine biodegradation, in bovine lymphocytes. When PMA and phytohemagglutinin (PHA) were added simultaneously, the enzyme activity was stimulated synergistically. The ability of phorbol esters to stimulate the enzyme activity was consistent with their tumor-promoting ability. Phorbol, which is not a tumor promotor, was incapable of stimulating the enzyme activity. Phorbol diacetate weakly stimulated the activity of the acetylase. Phorbol dibutyrate had a similar stimulatory effect to PMA. These results suggest that the spermidine/spermine N1-acetyltransferase may play an important role in changes in polyamine levels in phorbol ester-treated cells and that the increase in the enzyme activity may have some relationship to the control of cell growth and differentiation by phorbol esters.

Acetyltransferases↗
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↗
PubMed1984

Reduction of left ventricular size following oxygen inhalation in patients with coronary artery disease as measured by biplane coronary cineangiograms.

Left ventricular size is one of the major determinants of myocardial oxygen consumption, therefore if oxygen inhalation reduces myocardial oxygen demand, such might be beneficial in the treatment of acute myocardial infarction. Routine diagnostic biplane left coronary cineangiograms were obtained during air or oxygen breathing in 11 patients with old myocardial infarction or angina pectoris. Coordinates of the points on the left coronary artery were measured and throughout one cardiac cycle frame by frame. The spatial distance (segment length: L) between any two of these points was calculated. Segment length at R wave on the electrocardiogram (LECG R) and minimum value (Lmin) for each segment were calculated. Arterial pO2 was elevated by oxygen breathing from 91 +/- 4 (+/- SE) to 427 +/- 18 mmHg. Left ventricular segment length was significantly reduced by oxygen breathing: LECG R being reduced following oxygen breathing from 62.3 +/- 3.0 to 60.6 +/- 3.0 mm (a decrease of 3.3 +/- 0.8%) and Lmin also being reduced from 55.9 +/- 2.8 to 54.4 +/- 2.8 mm (a decrease of 3.1 +/- 1.0%). These figures indicate that left ventricular size was reduced. Reduction in left ventricular size through oxygen inhalation, by reducing myocardial oxygen demand, should therefore be beneficial in coronary artery disease.

Adult↗
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

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

Regulation of ornithine decarboxylase activity by cyclic AMP in guinea pig lymphocytes: transcriptional and post-transcriptional control.

Induction of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in phytohemagglutinin-stimulated lymphocytes was suppressed by the administration of dibutyryl cyclic AMP and 3-isobutyl-1-methylxanthine. This inhibition of ornithine decarboxylase induction was overcome by removing the chemicals from the lymphocyte culture. However, the recovery of ornithine decarboxylase induction by washout of the chemicals did not occur when actinomycin D, cordycepin or alpha-amanitin was added to the cultures, suggesting that the synthesis of mRNA directed to ornithine decarboxylase was reduced in dibutyryl cyclic AMP- and 3-isobutyl-1-methylxanthine-treated cells. Moreover, the decay of ornithine decarboxylase activity in the cells treated with phytohemagglutinin plus dibutyryl cyclic AMP and 3-isobutyl-1-methylxanthine was significantly slower than that of control cells stimulated with phytohemagglutinin alone. The difference of the decrease in ornithine decarboxylase activity between dibutyryl cyclic AMP- and 3-isobutyl-1-methylxanthine-treated and control cells was observed when actinomycin D was added to the culture, but not when cycloheximide was added. Therefore, prevention of ornithine decarboxylase decay by cyclic AMP may be post-transcriptional events, but not post-translational events.

Animals↗
PubMed1982

Studies on the cell-mediated immune response of tonsillar lymphocytes with regard to the clinical course and patient's age.

There was no statistically significant difference in the intensity of the cell-mediated immune response of tonsillar T cells among different pathological conditions of the tonsils nor among different age groups. The tonsillar cell population of the adult was smaller than that of the child. Tonsillar cells were separated into 3 fractions with different specific gravities. In tonsillar cells from adults, fraction III consisting mainly of small lymphocytes with a high specific gravity occupied a larger portion than in those from children. Fraction I consisting of cells with a low specific gravity had a greater number of cells in the swollen tonsils of children than in the tonsils of adults. However, the absolute numbers of the cells in fraction III in adults and in children were nearly the same. The proportion of T cells in fraction III was higher than in fraction I. Hence, the proportion of T cells in adults' tonsils is higher than in children's tonsils. The cells composing fraction I include some cells that have undergone blastoid transformation in response to various stimuli and some lymphoid cells that are ontogenetically immature T cells, besides mature T cells. The cells composing fraction III include fully mature T cells and the total cell population of fraction III does not differ significantly with age. It seems likely that the child's tonsil contains a larger number of cells under antigenic stimulation or in preparation for immune response than does the adult's tonsil.

Adult↗
PubMed1981

Myocardial contractile force at high coronary arterial oxygen tension in dogs.

In 34 mongrel dogs, the left anterior descending coronary artery was perfused with the dog's own femoral arterial blood at a constant flow rate and the myocardial contractile force was measured using a myocardial strain gauge arch. When the femoral arterial blood was oxygenated (pO2 61.7 kPa (463 mmHg)) using an artificial lung, so that the perfused myocardium became hyperoxic, the myocardial contractile force was increased by 11.1 +/- 2.3%. When the perfusion rate was reduced by approximately 20%, there was a smaller increase in myocardial contractile force, 8.0 +/- 2.3%. If, in addition, oxygen inhalation was performed the myocardial contractile force decreased by 4.1 +/- 2.1%. In 10 mongrel dogs, the carotid arteries were perfused at a constant flow rate with femoral arterial blood from a donor dog. Oxygen inhalation by the donor dog caused a reduction in the myocardial contractile force of the experimental dog of 5.9 +/- 1.6%. It is suggested that oxygen has a direct effect in increasing myocardial contractile force. This increase is counteracted by oxygen-induced coronary vasoconstriction in some part and by a neurohumoral effect or suppression of chemoreceptor activity.

Animals↗