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Biomedical subjects

T Saeki

Publications and source records attributed to T Saeki.

At least 217 records · Page 12Linked to original sources
PubMed1983

Proline iminopeptidase from Bacillus megaterium: purification and characterization.

Proline iminopeptidase [EC 3.4.11.5] was purified about 1,700-fold from cell free extract of Bacillus megaterium by a series of column chromatographies on DEAE-Toyopearl, PCMB-T-Sepharose and hydroxyapatite, and gel filtration on Toyopearl FW-55. The purified enzyme still contained a minor contaminant as judged by disc gel electrophoresis. The enzyme was most active at pH 7.0 with Pro-beta-naphthylamide (Pro-2-NNap) as the substrate, and hydrolyzed Pro-X (X = amino acid, peptide, amide, and arylamide) bonds when the proline residue was at the amino terminal. The enzyme was completely inactivated by p-chloromercuribenzoate (PCMB), but was not inhibited by metal chelators, diisopropylphosphorofluoridate (DFP) and phenylmethanesulfonyl fluoride (PMSF). The enzyme inactivated with PCMB was reactivated by adding 2-mercaptoethanol. From this result and the chromatographic profile on PCMB-T-Sepharose, the enzyme seems to be a sulfhydryl enzyme. The isoelectric point of the enzyme was 4.0. The molecular weight of the enzyme was estimated to be 58,000 by gel filtration on Toyopearl and 60,000 by sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme is a monomer.

Aminopeptidases↗
PubMed1982

Antihypertensive actions of isoprenoids.

Specific features of antihypertensive action of two new isoprenoid compounds, i.e. 5-nicotinooxymethyl -gamma - tocopherylnicotinate (NNT) and decaprenoic ethylester (EDP) were studied in rats. NNT and EDP were very similar to each other in their pharmacological features as far as we studied. Both NNT and EDP did not affect blood pressure in normotensive animals but significantly reduced blood pressure in SHR and DOCA/salt hypertensive animals in the acute studies with single dosing of 1 to 10 mg/kg (p.o.). Their antihypertensive action was mild but long-lasting and cumulated by the repeated administration. The chronic administration of NNT and EDP at oral doses of 0.2 and 2 mg/kg once a day completely suppressed the development of hypertension in rats unilaterally nephrectomized and treated with DOCA/salt and in SHR which were unilaterally ureter-ligated to accelerate the progress of their genetic hypertension. The mechanism of their antihypertensive action remains to be solved.

Animals↗
PubMed1981

Microsomal reductase for aromatic aldehydes and ketones in guinea pig liver. Purification, characterization, and functional relationship to hexose-6-phosphate dehydrogenase.

An NADPH-specific aromatic aldehyde-ketone reductase located in guinea pig liver microsomes can be effectively solubilized with nonionic detergents, but not with bile salts and hydrolytic enzymes. Destruction of microsomal membranes by nonionic detergents or acetone treatment leads to significant activation of the reductase, indicating that the enzyme is partly latent in intact microsomes. After solubilization with Triton X-100, the reductase has been highly purified. The purified enzyme catalyzes the NADPH-linked reduction of xenobiotic aromatic aldehydes and ketones as well as 3-ketosteroids, notably 5 alpha- and 5 beta-dihydrotestosterones. The reductase activities for xenobiotic carbonyl compounds and for 3-ketosteroids are each inhibited by addition of the other type of substrate and show the same pH optimum, cofactor requirement, and heat stability, indicating the same enzyme is responsible for the reduction of the two types of substrates. Hexose-6-phosphate dehydrogenase, purified from guinea pig liver microsomes, acts as a more effective NADPH generator for the reductase than yeast and guinea pig liver cytosolic glucose-6-phosphate dehydrogenase. Evidence has been obtained that hexose-6-phosphate dehydrogenase undergoes a functional interaction with the reductase, facilitating the provision of NADPH to the reductase activity both in the reconstituted system and in microsomes.

Alcohol Oxidoreductases↗
PubMed1981

Progressing alteration of parathyroid function in cattle from experimental high and low calcium feeding.

Changes in function of the parathyroid gland was studied periodically for 36 days in two groups of calves fed high and low calcium diets. After changes to the experimental diets, parathyroid function was altered in some calves at 9 days of high or low calcium feeding. Parathyroid function was reduced in high calcium feeding and increased in low calcium feeding. These changes increased progressively in intensity with the lapse of time during experimental feeding periods.

Animals↗
PubMed1981

Analgesic effect of fentiazac after tooth extraction or minor oral surgery.

A new nonsteroidal anti-inflammatory agent, fentiazac, was used for analgesia after tooth extractions and minor oral surgery in two Japanese dental hospitals. The drug was administered as a single oral dose of either 50 mg or 100 mg. The 50-mg dose provided rapid analgesic effect, but its effect lasted only two to three hours in a number of patients. At a dose of 100 mg, fentiazac proved effective for 85% of 53 patients, usually providing marked reduction of disappearance of pain within one hour or less. Among patients in whom pain reappeared, the mean time for recurrence was four hours, indicating a satisfactory duration of analgesic effect. One side effect--loss of appetite--was reported by one patient in the entire series of 71 subjects. It is concluded that fentiazac is a highly effective analgesic agent with a wide margin of safety for use after dental procedures that produce pain.

Acetates↗
PubMed1980

Genetic control of diploid recovery after gamma-irradiation in the yeast Saccharomyces cerevisiae.

Genetic mechanisms(s) of gamma-ray resistance of the diploid and budding haploid cells of S. cerevisiae were investigated, with special reference to mitotic recombination, by examining 11 rad mutant strains. The radiosensitivity of the diploid was markedly enhanced in certain gamma-ray-sensitive rad mutants, whereas the sensitivity of the haploid was not so enhanced in these rad mutants. These enhanced sensitivities of diploids were irrespective of their own haploid sensitivities. From these results, the existence of a mechanism of diploid-specific recovery was postulated. The magnitude of diploid radioresistance in rad mutants was positively correlated with the ability for the induction of mitotic recombinational events which were controlled by RAD genes belonging to the RAD-51 genetic pathway. The genetic mechanism(s) of the diploid recovery after gamma-irradiation are probably related to recombinational processes between the homologous chromosomes leading to reciprocal recombination or non-reciprocal gene conversion. Furthermore, the higher radioresistance of budding cells in comparison with the non-budding cells was also correlated to the diploid radioresistance with a few exceptions. Consequently, the mechanism(s) of budding radioresistance similar to the diploid recovery seems to be related to mitotic recombinational processes.

Diploidy↗
PubMed1980

Effects of estrogen administration on parathyroid function in cattle.

Experiment was performed with 6 castrated Holstein bullocks. The animals were divided into two groups of three each, one for experiment and the other for control. The experimental group was given intramuscularly with 120 mg of estrone and 24 mg of estradiol-17 beta daily for 7 days, and the control group with the same dose of solvent without estrogens. The decreasing effect of estrogens on appetite was clearly observed after starting estrogen treatment. The secretory function of the parathyroid gland was improved and the recovery rate of plasma-titratable calcium enhanced in the experimental group after ethylenediaminetetra-acetic acid 2Na infusion as a functional test of the parathyroid gland. Plasma estrogen concentration was kept at the same level as than in healthy dairy cows of the late stage of pregnancy. It was suggested that those changes in calcium metabolism might be mainly due to the acceleration of bone resorption caused by the estrogen injection via the increased secretion of parathyroid hormone.

Animals↗
PubMed1975

Effect of desdanine on nucleoside diphosphate kinase and pyruvate kinase of Escherichia coli.

Kinetic analysis demonstrated that the irreversible inhibition of nucleoside diphosphate kinase of Escherichia coli by desdanine proceeds via a reversible Enzyme-Inhibitor complex. It is known that pyruvate kinase of E. coli becomes inactive upon prolonged dialysis in the absence of a reducing reagent, such as dithiothreitol and that the inactive enzyme is reactivated if dithiothretiol is added. Desdanine inhibits this reactivation process. The effect is discussed in relation to inhibition in relation to the inhibition of growth of E. coli by desdanine under anaerobic conditions. Pyruvate kinase of E. coli changes not only in intracellular quantity but in its kinetic characteristics depending on growth conditions, aerobic or anaerobic. The enzyme shows a broad specificity for nucleside diphosphates, especially in the presence of AMP, and thus resembles closely nucleoside diphosphate kinase. The in vivo role of pyruvate kinase in supplying nucleoside triphosphates under anaerobic conditions is discussed.

Acrylamides↗