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Biomedical subjects

H Otsuka

Publications and source records attributed to H Otsuka.

At least 343 records · Page 19Linked to original sources
PubMed1981

Bladder carcinogenesis in mice induced by N-butyl-N-(4-hydroxybutyl) nitrosamine and N-ethyl-N-(4-hydroxybutyl)-nitrosamine with reference to the effect of cyclophosphamide.

The carcinogenicities of N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) and N-ethyl-N-(4-hydroxybutyl) nitrosamine (EHBN) on the urinary bladder were compared in male BALB/c mice. The effect of cyclophosphamide (CPA) on the carcinogenicities was also investigated. The carcinogenic activity on the bladder mucosa of EHBN was similar to that of BBN, and there was no difference in the growth patterns, histological types or invasive characters of carcinomas induced by BBN and EHBN. Benign or malignant tumors of vascular origin developed in the urinary bladders of 15 mice treated with these carcinogens. The incidence of vascular tumors induced by EHBN was significantly higher than that of tumors induced by BBN. Intraperitoneal injections of CPA seemed to have no effect in the incidence of bladder carcinomas induced by these carcinogens, or on the development of vascular tumors in the bladder wall induced by EHBN.

Animals↗
PubMed1981

Tumors of the anal region induced in mice painted with methylazoxymethanol acetate.

The carcinogenicity of methylazoxymethanol acetate (MAM acetate) was examined in 91 BALB/c mice by painting it on the anal region. Carcinomas and adenomas of the perianal sebaceous gland were induced in 23 of 24 male (96%) and 16 of 30 female (53%) mice and keratoacanthoma developed in one of 24 male mice within 30 weeks after treatment with MAM acetate. Vascular tumors of the liver and fat issue of the abdominal cavity also developed in 16 of 24 male (67%) and 3 of 30 female (10%) mice treated with this drug. Microscopic adenocarcinomas were found in the rectal mucosa of 3 of 24 male mice adjacent to the anorectal junction. The sex difference in the incidence of tumors is briefly discussed.

Adenoma↗
PubMed1981

Effect of tryptophan metabolites and metal ions on the purified kynureninase from rat liver.

Kynureninase purified from rat liver was inhibited by 3-hydroxyanthranilate, or anthranilate, and slightly by 5-hydroxyanthranilate. However, tryptophan metabolites other than anthranilate and its derivatives, and also alpha-keto acids and alanine did not affect the activity of this enzyme. Kynureninase was also inhibited and inactivated by metal ions, especially Hg2+ and Zn2+. On the other hand Mg2+, Ca2+ and monovalent cations had no effect on the activity of the enzyme. The reductants, such as dithiothreitol, reduced glutathione and mercaptoethanol, prevented this inactivation. p-Chloromercurybenzoate (CMB) and N-ethylmaleimide inhibited the enzyme action. Kynureninase which had been completely inactivated by Hg2+ or CMB could be reactivated with excess dithiothreitol, indicating that enzyme inactivation can be attributed to the blocking of sulfhydryl groups. Five sulfhydryl groups per subunit of the enzyme molecule were detected using CMB and mercury orange.

Animals↗
PubMed1980

Stereochemistry of the myo-inositol-1-phosphate synthase reaction.

Experiments with D-glucose-6-P stereospecifically tritiated at C-6 showed that the myo-inositol-1 P synthase reaction catalyzed by both the enzyme from beef testis and from pollen of Lilium longiflorum proceeds with stereospecific loss of the pro-6R and incorporation of the pro-6S hydrogen into the product. The ring closure thus occurs in a retention mode at C-6 of the substrate, a finding at variance with an earlier report, but in agreement with the stereochemistry recently determined for the reaction in Streptomyces flavopersicus and with the general stereochemical mode of operation of aldolases.

Animals↗
PubMed1980

Biochemical transformation of thymidine kinase (TK)-deficient mouse cells by herpes simplex virus type 1 DNA fragments purified from hybrid plasmids.

The thymidine kinase (TK) gene of HSV-1 has been cloned in Escherichia coli K12 plasmids, pMH1, pMH1A, and pMH4. These plasmids contain a 1,92Obp HSV-1 TK DNA sequence, which replaces a 2,067 bp EcoR I to Pvu II sequence of plasmid pBR322 DNA. Superhelical DNAs of plasmids pMH1, pMH1A, and pMH4 as well as plasmid DNAs cleaved by EcoR I, Hinc II, Bg1 II, Sma I, and Pvu II transformed TK-deficient LM(TK-) cells to the TK+ phenotype. A 1,230bp EcoR I-Sma I fragment purified from pMH1 DNA (and from plasmid pAGO, DNA, the parent of pMH1) also transformed LM(TK-) cells. Serological and disc PAGE studies demonstrated that the TK activity expressed in biochemically transformed cells were HSV-1-specific. The experiments suggest that the HSV-1 TK coding region may be contained within a l.1kbp DNA sequence extending from about the Hinc II (or Bgl II) cleavage site to the Sma I site. 35S-methionine labeling experiments carried out on cell lines transformed by Hinc II-cleaved pMH1 DNA and by the EcoR I-Sma I fragment showed that the TKs purified from the transformed cells consisted of about 39-40,000 dalton polypeptides.

Animals↗
PubMed1980

Biosynthesis of biopterin in Ascaris lumbricoides suum.

In in vivo experiments, radioactivity from [U-14C]GTP was incorporated into biopterin, and, in fact, all carbon atoms of biopterin synthesized in Ascaris lumbricoides suum originated from GTP. Biopterin was also biosynthesized in homogenates of tissue fluid and muscles of Ascaris lumbricoides suum. The enzyme which catalyzes sepiapterin synthesis from D-erythro-7,8-dihydroneopterin-3'-phosphate was found in A. lumbricoides suum extracts and extracted in the 0--30% (NH4)2SO4 fraction from a 40 000 x g supernatant. The enzyme was purified by Sephadex G-200 column and DEAE-cellulose column chromatography. It is suggested that sepiapterin could be an intermediate compound in biopterin biosynthesis.

Alcohol Oxidoreductases↗
PubMed1980

Purification and properties of kynureninase from rat liver.

Kynureninase [L-kynurenine hydrolase EC 3.7.1.3] has been purified 614-fold from rat liver cytosol. The purification procedure involved pH treatment, ammonium sulfate fractionation, Sephadex G-100 gel filtration, DEAE-Sepharose CL-6B chromatography, extraction with 40% saturated solution of ammonium sulfate and hydroxyapatite chromatography. The enzyme was found to be homogeneous by the criteria of disc gel electrophoresis. SDS-gel electrophoresis and sucrose gradient centrifugation. The enzyme was obtained as a holo-enzyme which showed an absorption maximum at 420 nm. In the absence of pyridoxal 5-phosphate (PLP) the enzyme was dissociated into an apoenzyme. The isoelectric points of holoenzyme and apoenzyme are 5.7 and 6.1. Sucrose gradient centrifugation and SDS-gel electrophoresis gave molecular weight estimates of 95,000 and 55,000, respectively. The optimum pH shifted to higher pH with increase in the concentration of PLP. The Michaelis constants were determined as follows: kynurenine, 240 microM; 3-hydroxykynurenine, 13 microM; PLP, 0.1-1.7 microM. The maximum velocity for 3-hydroxykynurenine was 11 times higher than that for kynurenine at pH 7.7. This enzyme can be regarded as a 3-hydroxykynureninase type enzyme.

Animals↗
PubMed1980

Biochemical transformation of mouse cells by a purified fragment of marmoset herpesvirus DNA.

Although the size of marmoset herpesvirus (MarHV) DNA, estimated by velocity sedimentation in sucrose gradients, was similar to that of herpes simplex virus type 1 (HSV-1) DNA, the restriction endonuclease sites of MarHV and HSV-1 DNAs were quite different. A specific BamHI restriction fragment (6.2 x 10(6) daltons) of MarHV DNA biochemically transformed LM(TK-) mouse fibroblasts to the thymidine kinase(TK)-positive phenotype. Rabbit antisera, prepared against MarHV TK, inhibited MarHV-induced TK, but not HSV-1, HSV-2, or cellular TKs. Disc PAGE analyses and enzyme neutralization experiments with the anti-MarHV TK sera demonstrated that the TK expressed in MarHV transformants was MarHV-specific.

Animals↗
PubMed1980

Growth stimulation of BHK cells in culture by free biotin in serum.

A dialysate of fetal bovine serum stimulated the growth of BHK cells in a medium containing 1% dialyzed serum. The growth-stimulating activity of the dialysate was separated in a single peak with Biogel P-2 chromatography, and a single active component was further fractionated with paper and thin-layer chromatography. The component was identified as biotin. Pure biotin behaved the same as the active component in the dialysate and had the same growth-stimulating activity. The dialysate contained only the free biotin that was present in serum. Free biotin was found in relatively large amounts in fetal (bovine and human) sera, and only a very small percentage of dialysates of adult (bovine, horse, swine, and human) sera had traces of growth-stimulating activity. The possible role of free biotin in the body is discussed.

Animals↗