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Biomedical subjects

T Akao

Publications and source records attributed to T Akao.

At least 109 records · Page 6Linked to original sources
PubMed1986

A novel type of aryl sulfotransferase obtained from an anaerobic bacterium of human intestine.

A novel type of aryl sulfotransferase is produced by an anaerobic bacterium of human intestine, Eubacterium A-44. Aryl sulfotransferase separated from this bacterium differs from the sulfotransferase which uses 3'-phosphoadenosine 5'-phosphosulfate as a donor. The enzyme catalyzes stoichiometric transfer of a sulfate group from a phenol sulfate ester to other phenolic compounds, with strict specificity. The optimal pH and molecular weight were 8-9 and 315,000, respectively.

Arylsulfotransferase↗
PubMed1986

3 beta-Hydroxysteroid dehydrogenase of Ruminococcus sp. from human intestinal bacteria.

Ruminococcus sp. PO1-3 obtained from human intestinal flora is able to reduce dehydrocholate as well as 3-ketoglycyrrhetinate. From this bacterium dehydrocholate- and 3-ketoglycyrrhetinate-reducing activities were purified one thousand-fold together with 3-ketocholanate-reducing and 3-beta-hydroxyglycyrrhetinate (glycyrrhetic acid) oxidizing activities by means of Matrex Red A, Sephadex G-200 and Octyl-Sepharose column chromatography. The purified enzyme catalyzed the reduction of dehydrocholic acid to 3 beta-hydroxy-7,12-diketocholanic acid and of 3-ketocholanic acid to 3 beta-hydroxycholanic acid. Studies on substrate specificity revealed that the enzyme had absolute specificity for the beta-configuration of a hydroxyl group at the 3 position of bile acid and steroids having no double bond in the A/B ring. This enzyme was neither beta-hydroxysteroid dehydrogenase [EC 1.1.1.51] nor 3 beta-hydroxy-delta 5-steroid dehydrogenase [EC 1.1.1.145], but a novel type of enzyme, defined as 3 beta-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗
PubMed1985

Cystinosis with marked atrophy of the kidneys and thyroid. Histological and ultrastructural studies in an autopsy case.

The eldest autopsied case (a 23-year-old man) of infantile form of cystinosis with uremia and myxoedema was reported. The cystine content per gram wet tissue of various organs was arranged as follows: the thyroid (4.61 mg), kidney (1.71 mg), eye (0.75 mg), spleen (0.65 mg), liver (0.49 mg), and brain (0.016 mg). In polarized light microscopy, cystine crystals were detected in the epithelial cells and epithelial lumina of both kidneys by Wollaston test, and foam cells with cystine crystals were histologically found in the reticuloendothelial and other organs, especially in the bone marrows. Moreover, electron microscopic findings revealed square, rectangular or lozenge-shaped small cystine crystal profiles in osmophilic dense bodies of the histiocytic cells and in the cytoplasm of the foam cells. In some of them, positive reaction for acid phosphatase activity was specifically localized at the periphery of the cystine crystal profiles.

Adult↗
PubMed1985

Enzymatic reduction of sennidin and sennoside in Peptostreptococcus intermedius.

Peptostreptococcus intermedius, one of the dominant bacteria of human intestine, reduced sennidin and sennoside to rheinanthrone and 8-glucosyl-rheinanthrone, respectively, and these reduction rates were stimulated by the addition of nicotinamide adenine dinucleotide (reduced form) (NADH), flavin adenine dinucleotide (FAD) and glucose. The reduction was accelerated by removing oxygen from the incubation tubes, which indicates the inhibition of the reduction by O2. Thus, for the maximal activity, the reaction system required an anaerobic condition and cofactors, NADH and FAD. This bacterium also reduced methyl orange, whose mode of reduction resembled that of sennidin reduction. More than 80% of these activities were recovered in the supernatant fraction after sonication of the bacterial suspension, and these activities were purified together by means of Sephadex G-200 gel-filtration and diethylaminoethyl-cellulose column chromatography. The purified enzyme reduced FAD and benzyl viologen in the presence of NADH under an anaerobic condition.

Anthracenes↗
PubMed1983

The role of protease in streptolysin S formation.

Production of streptolysin S by streptococci was found to be inhibited by treatment with protease inhibitors, tosylphenylalanine chloromethyl ketone (TPCK), tosyllysine chloromethyl ketone (TLCK), or phenylmethylsulfonyl fluoride (PMSF), even in the presence of the inducer oligonucleotides. Other protease inhibitors, antipain, leupeptin, or pepstatin were found to have little or no effect. Trypsin reversed the effect of TPCK or TLCK. The reversal was dependent upon the amount of added trypsin and the incubation time at 37 degrees C, suggesting that a protease activity was involved in the hemolysin formation. The effect of trypsin was not observed if chloramphenicol was also added, suggesting that a precursor of streptolysin S was processed as it was synthesized and released into medium as the active hemolysin, by the concerted action of a protease and inducer oligonucleotides. Experiments with the subcellular fractions of streptococci indicated that the streptolysin precursor was localized in the insoluble fraction and the "processing" protease in the supernatant fraction.

Cell-Free System↗
PubMed1981

Two esterases released from Mycobacterium smegmatis from the hydrolysis of long chain acyl-CoAs and Tween.

An esterase activity hydrolyzing palmitoyl-CoA was released into the culture medium from Mycobacterium smegmatis. Although another esterase activity hydrolyzing Tween 20 (polyoxyethylene sorbitan monolaurate) was also found in the culture medium, the bulk of the esterase activity was retained in the cells. However, treatment of early-log phase cells with lysozyme to prepare ghosts released 80% of the Tween 20 hydrolyzing activity, indicating the localization of the esterase in the periplasmic space or the cell envelope fraction. The presence of two different esterases hydrolyzing palmitoyl-CoA and Tween 20, suggested by the above results, was confirmed by the separation of these esterases on phenyl-Sepharose column chromatography. Palmitoyl-CoA hydrolase (thioesterase) was purified 630-fold from lysozyme-treated supernatant fluid to homogeneity, by means of Sephadex G-100 gel filtration, and DEAE-cellulose, phenyl-Sepharose and Blue-Agarose column chromatographies. Its molecular weight was approximately 42,000. Tween hydrolase was partially purified 150-fold by the same purification procedure up to the step of phenyl-Sepharose chromatography and its molecular weight was found to be about 51,000. These activities were stable against heating at 60 degrees C and treatment with non-ionic detergents. Thioesterase hydrolyzed long chain acyl-CoAs (C12-C20), but not Tween 20-80 or beta-naphthyl acetate. On the other hand, Tween hydrolase hydrolyzed Tween 20-80 and beta-naphthyl acetate. On the other hand, Tween hydrolase hydrolyzed Tween 20-80 and beta-naphthyl acetate, but not acyl-CoAs. Both esterases hydrolyzed monoolein, but not diolein, triolein, or phosphatidylcholine.

Acyl Coenzyme A↗
PubMed1979

In vitro sensitivity test of stomach cancer tissues by the use of metal grid method.

Ninety-nine specimens obtained from 53 patients with stomach cancer were cultured for about 3 days by means of the stainless steel grid method. In vitro effects of antitumor drugs on the cancer cells were evaluated autoradiographically or biochemically using a liquid scintillation counter to measure the uptake of 3H-thymidine. The radioactivity of the labeled tumor cells of both control fragments and fragments affected by drugs varied greatly among individual tumors. Therefore, the in vitro efficacy of antitumor drugs was represented as a comparison with that of control fragments. Positive correlation between in vitro tests and the clinical effects of antitumor drugs was observed in the specimens of 18 cases.

Antineoplastic Agents↗
PubMed1977

Protracted oral chemotherapy with fluorinated pyrimidines as an adjuvant to surgical treatment for stomach cancer.

Studies of oral chemotherapy of 5-fluroruracil (5-FU) combined with FT-207, a furanyl analog of 5-FU, as an adjuvant to surgical treatment of stomach cancer have been performed since 1970 in the first department of surgery of Chiba University, Japan. These studies were performed on 107 patients with curative stomach cancer and 22 patients with non-curative stomach cancer. These patients received consecutively 3.5mg/kg/day of 5-FU and 8mg/kg/day of FT-207 for 24 to 36 months and were compared with control patients who had undergone only surgical treatment. A significant higher survival was observed in the curatively resected patients receiving oral 5-FU and FT-207, as compared to the control group. Studies on non-curative stomach cancer patients treated with the same dose schedule gave encouraging results. Because of the limited number of patients treated in this study, the drawing of reliable conclusions must wait the results of further studies.

Administration, Oral↗
PubMed1976

A study of survival in patients with stomach cancer treated by a combination of preoperative intra-arterial infusion therapy and surgery.

Since 1968, there have been 62 patients with stomach cancer seen in the First Department of Surgery of Chiba University. Treatment consisted of preoperative intra-arterial chemotherapy and surgery. The chemotherapy entailed continuous infusion for 15 to 20 hours. The survival rates were analyzed with particular emphasis on the degree of serosal invasion of the stomach. The overall survivals at the end of 3 years were 54.2% for the treated patients, and 37.1% for the controls: and at the end of 5 years, 33.3% of the treated patients were living as compared to 29.7% of the control patients. In patients without serosal invasion, the survival rates were higher for those treated than for the controls for the first 2 years. At the end of 3 years, the 39 patients treated for serosal invasion had a survival rate of 46.8% vs. 29% in the controls: and at 5 years, 32.2% of the treated patients vs. 23.7% in the controls. The survival rates for the treated patients with cancerous infiltration of other organs were about the same as those for the corresponding control patients.

Adult↗
PubMed1976

Solubilization of diglyceride acyltransferase from the membrane of Mycobacterium smegmatis.

Diglyceride acyltransferase [acyl-CoA : 1,2-diacylglycerol O-acyltransferase, EC 2.3.1.20] was found to be localized in the membrane of Mycobacterium smegmatis, and this enzyme could be solubilized from the membrane by treatment with aqueous acetone. The solubilized enzyme required either 1,2-diolein or 1, 3-diolein as an acceptor for palmitoyl-CoA. The apparent Km value for 1,2- or 1,3-diolein and that for palmitoyl-CoA were about 1.4 X 10(-5) M and 6 X 10(-6) M, respectively. Several sulfhydryl reagents were inhibitory to the enzyme activity, suggesting the existence of a thiol group(s) in its active site. The solubilized enzyme, which was more labile than that membrane-bound one, could be stabilized to some extent with antichaotropic salts such as phosphate, pyrophosphate, and sulfate.

Acyltransferases↗
PubMed1976

Effect of N1-(2'-tetrahydrofuryl)-5-fluorouracil and 5-fluorouracil on nucleic acid and protein biosyntheses in Ehrlich ascites cells.

N1-(2'-Tetrahydrofuryl)-5-fluorouracil (FT-207) is a derivative of 5-fluorouracil (5-FU) and has been accepted as a new chemotherapeutic drug. The inhibitory effects of FT-207 and 5-FU on nucleic acid and protein biosyntheses in Ehrlich ascites cells were compared. Both drugs markedly inhibited the incorporation in vivo of the labeled precursors into nucleic acid and protein. The inhibitory effect of FT-207 on DNA and RNA synthesis lasted for a long period of time. Two hr after administration of 5-FU (250 mug/g body weight), the absolute size of uracil pool of liver increased by at least 50%. However, in an in vitro study, FT-207 at a concentration of 60 mug/ml produced no effect on the incorporation of precursors into DNA and RNA of Ehrlich ascites cells 3 hr incubation. If 5-FU was added to Ehrlich ascites cell suspension simultaneously with [5-3H]uridine, the incorporation of the labeled precursor into RNA increased by 30 to 50%.

Animals↗