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S Yoshihara

Publications and source records attributed to S Yoshihara.

At least 127 records · Page 7Linked to original sources
PubMed1987

Comparison of DT-diaphorases purified from the liver cytosol of untreated, and 3,4,5,3',4'-pentachlorobiphenyl- and 3-methylcholanthrene-treated rats.

DT-Diaphorase purified from the liver cytosol of rats treated with a highly toxic PCB congener, 3,4,5,3',4'-pentachlorobiphenyl (PenCB), was compared to those from 3-methylcholanthrene (MC)-treated and untreated rats. Treatments with PenCB and MC resulted in about 8- and 7-fold increases of cytosolic DT-diaphorase activity, respectively. Purification of the enzyme preparations from untreated, and PenCB- and MC-treated rats were conducted by using DE-52, DEAE-Sephadex A-50, hydroxylapatite, and Bio-Gel P-150 column chromatographies. Both Sephadex G-100 gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that all of the final preparations from the three origins were homogeneous and had the same molecular weight of 59,000, consisting of two subunits with molecular weights of 30,000. Further studies on amino acid composition, Km value, optimum pH, and catalytic activities for various substrates also indicated that both PenCB- and MC-inducible DT-diaphorases were identical with that from the untreated rats. All three DT-diaphorases contained about 2 mol of FAD per mol of enzyme. Partial digestion of the enzymes by trypsin and subsequent analysis by HPLC revealed that the three preparations were indistinguishable. The identity among the three purified DT-diaphorases was finally confirmed by Ouchterlony immunodiffusion employing anti-serum raised against each enzyme preparation.

Amino Acids↗
PubMed1986

Kinetic and inhibition studies on reduction of diphenyl sulfoxide by guinea pig liver aldehyde oxidase.

To characterize the properties of diphenyl sulfoxide (DPSO) as a new type of electron acceptor for guinea pig liver aldehyde oxidase (AO), we compared the kinetics of the reductions of DPSO and other classical electron acceptors such as O2 and ferricyanide. The double-reciprocal plot of the 2-hydroxypyrimidine (2-OH PM)-linked DPSO reduction with the highly purified enzyme was biphasic. Similar biphasic plots were obtained with the reductions of other electron acceptors. Only the lower Km value, which was obtained by extrapolation of the plot at lower concentrations of 2-OH PM, was identical with that shown by the freshly prepared crude enzyme. DPSO as well as menadione progressively inhibited the reductions of O2 and ferricyanide with time. Menadione inhibited the DPSO reduction noncompetitively with respect to 2-OH PM and competitively with respect to DPSO, while its mode of inhibition of ferricyanide reduction was uncompetitive for either the electron donor or the acceptor. On the other hand, DPSO showed an uncompetitive and a noncompetitive inhibition of ferricyanide reduction with respect to 2-OH PM and ferricyanide, respectively. These results may indicate that DPSO interacts with the enzyme at the same site as menadione, and thereby when other electron acceptors are present it serves as an actual inhibitor rather than as an electron acceptor for AO.

Aldehyde Oxidase↗
PubMed1986

A method for the identification of sulfated glycopeptide by two-dimensional electrophoresis on cellulose acetate membrane.

Two-dimensional electrophoresis on cellulose acetate membrane permits the clean separation of sulfated glycopeptide in a mixture of acidic glycans (glycosaminoglycans and acidic glycopeptides). Two systems were used. In system 1, 0.1 M pyridine-0.47 M formic acid buffer (pH 3.0) was used in the first and 0.1 M barium acetate (pH 8.0) in the second dimension. In system 2, 0.1 M pyridine-0.47 M formic acid buffer (pH 3.0) was used in the first and 0.1 M HCl in the second dimension. All of the acidic glycans on electrophoretogram were stained with alcian blue in 70% ethanol. On the other hand, sulfated glycans alone were made visible with alcian blue in 0.1 M HCl. Alcian blue in 70% ethanol or 0.1 M HCl, when combined with periodic acid-Schiff's reagent identified sulfated glycopeptides on cellulose acetate membrane.

Electrophoresis↗
PubMed1986

Changing pattern of age-specific prevalence of hepatitis B surface antigen and corresponding antibody in Japan.

During the period 1978-1984 in Japan, the prevalence of hepatitis B surface antigen (HBsAg) in age groups below age 15 years was 18/2,550 (0.7%), and it was particularly low in the group below age 5 years (2/706 (0.3%)). The low prevalence of HBsAg in children under 15 years of age contrasted sharply with the much higher prevalence in persons age 15 years and older (36/2,050 (1.8%)). In accord with this, the prevalence of antibody to hepatitis B surface antigen (anti-HBs) was much lower in children below age 15 years than that in persons 15 years of age and older (29/2,550 (1.1%) vs. 242/2,050 (11.8%)). Furthermore, the prevalence of hepatitis B viral markers in 1978-1984 was lower than that during the period from 1972-1977 in every age group. A total of 13 (81%) of 16 mothers of carrier children, identified in 1978-1984, were positive both for HBsAg and hepatitis B e antigen in their sera. Now that mother-to-baby transmission appears to be the main route for establishing the persistent carrier state, its interruption should reduce the reservoir of hepatitis B virus, toward its eventual eradication, in Japan.

Adolescent↗
PubMed1985

Guinea pig liver aldehyde oxidase as a sulfoxide reductase: its purification and characterization.

Guinea pig aldehyde oxidase was purified about 120-fold at a yield of 26% from liver cytosol by sequential column chromatography using DEAE-cellulose, FMN-Sepharose 4B, and Sephacryl S-300. The purified enzyme showed many similarities with the rabbit liver aldehyde oxidase reported by other workers with respect to its absolute spectra, molecular weight, and cofactor compositions of molybdenum, FAD, and nonheme iron. This enzyme efficiently utilized 2-hydroxypyrimidine and benzaldehyde as electron donors while N1-methylnicotinamide was 40 times less effective than 2-hydroxypyrimidine. Diphenyl sulfoxide was reduced anaerobically to diphenyl sulfide in the presence of electron donors. This activity was highly susceptible to SKF 525-A as well as the known inhibitors for aldehyde oxidase such as menadione, estradiol, and potassium cyanide. This enzyme also reduced dibenzyl sulfoxide, phenothiazine sulfoxide, D-biotin methyl ester d-sulfoxide, and quinoline N-oxide, but not L-methionine sulfoxide, dimethyl sulfoxide, D-biotin methyl ester l-sulfoxide, and D-biotin d- and l-sulfoxides, as well as diphenyl sulfone. These results indicate that aldehyde oxidase in guinea pig liver functions as a sulfoxide reductase with selective substrate specificity under anaerobic conditions.

Aldehyde Oxidase↗
PubMed1985

Purification and characterization of seven distinct forms of liver microsomal cytochrome P-450 from untreated and inducer-treated male Wistar rats.

A total of nine forms of cytochrome P-450 were purified to homogeneity from liver microsomes of male Wistar rats. They were P-451 I and P-451 II from untreated rats, P-450 II and P-450 III from phenobarbital-treated rats, MC-P-448 L and MC-P-448 H from 3-methylcholanthrene-treated rats, and P-452, P-448 L, and P-448 H from 3,4,5,3',4'-pentachlorobiphenyl-treated rats. Among them, MC-P-448 L and MC-P-448 H were indistinguishable from P-448 L and P-448 H, respectively, with regard to electrophoretic, spectral, catalytic and immunochemical properties, and thus seven forms were distinct hemoproteins. The minimal molecular weight of each form was as follows: P-451 I (49,000), P-451 II (52,000), P-450 II (52,000), P-450 III (53,500), P-452 (48,000), P-448 L (56,000), P-448 H (54,000). Judging from the oxidized absolute spectra, P-448 H was a high-spin form and the others were of low-spin type. In a reconstituted system, N-demethylations of benzphetamine and aminopyrine were catalyzed by most of the forms at comparable rates. On the other hand, the activities for the oxidations of benzo[a]pyrene, 7-ethoxycoumarin, biphenyl, and estradiol-17 beta varied greatly among the forms of cytochrome P-450. The most efficient catalysts were as follows: P-448 L and P-451 II for benzo[a]pyrene 3-hydroxylation; P-448 L for 7-ethoxycoumarin O-deethylation; P-448 L, P-451 II, and P-448 H for biphenyl 4-hydroxylation; P-448 L and P-448 H for biphenyl 2-hydroxylation; and P-451 II and P-448 H for estradiol 2-hydroxylation. P-451 I, P-450 II, and P-450 III were somewhat poorer catalysts in metabolizing all the substrates except for benzphetamine and aminopyrine, but their substrate specificities were still distinguishable from one another. Of all the purified cytochrome P-450's, P-452 showed the least ability to metabolize all the substrates. Judging from the properties, it appears that six forms in male Wistar rats correspond to the distinct forms of cytochrome P-450 in Long-Evans and/or Sprague-Dawley rats reported by other workers, but P-451 I is a new constitutive isozyme in Wistar rats.

Animals↗
PubMed1985

Tay-Sachs disease associated with precocious puberty.

A girl with Tay-Sachs disease developed enlargement of the mammary glands at the age of 4 years and menstruation at the age of 6 years. It was demonstrated that the precocious puberty in this patient was due to the hypersecretion of gonadotropins.

Child↗
PubMed1985

Unique induction of cytochrome P-450 isozymes in rat liver microsomes by treatment with 3,4,5,3',4'-pentachlorobiphenyl and its effect on testosterone metabolism.

Pretreatment of male Wistar rats with 3,4,5,3',4'-pentachlorobiphenyl (PenCB), a potent 3-methylcholanthrene-type inducer, increased selectively 7 alpha-but strongly repressed 2 alpha-, 6 beta- and 16 alpha-hydroxylations of testosterone in the liver microsomes. To understand this unique phenomenon, the testosterone metabolism by three isozymes (P-452, P-448 L and P-448 H) of cytochrome P-450 purified from Wistar rats treated with PenCB was studied in a reconstituted system. For comparison 4 other isozymes (P-451 I, P-451 II, P-450 II and P-450 III) of cytochrome P-450 from untreated and phenobarbital-treated rats were also studied. In addition, the contribution of cytochrome P-450's to testosterone hydroxylation was examined by an immune complex inhibition of the activity and by a determination of the individual cytochrome P-450 in microsomes using antibodies. In the reconstituted system, 7 alpha-hydroxylation of testosterone was catalyzed almost exclusively by P-452, with the exception of P-451 I. On the other hand, the 6 beta-hydroxylation was catalyzed by most of the cytochrome P-450's tested at considerably lower rates. Among the seven forms, P-451 II was the most effective catalyst for 2 alpha- and 16 alpha-hydroxylations, with equally high turnover numbers, while other forms showed only low or no activity for either or both hydroxylations. The microsomal activity of 7 alpha-hydroxylation in PenCB-treated rats was inhibited almost completely by anti-P-452. A partial inhibition of the 16 alpha-hydroxylation was achieved by anti-P-451 II and anti-P-452 while the 6 beta-hydroxylation was insensitive to anti-P-451 II but slightly sensitive to anti-P-452. The activity of 2 alpha-hydroxylation was not detected in the liver microsomes from PenCB-treated rats. Immunochemical quantitation showed that in the microsomes from PenCB-treated rats, P-451 II, P-452, P-448 L and P-448 H accounted for 4.1, 3.6, 31.6 and 62.8%, respectively, of the total cytochrome P-450 (2.69 nmol/mg protein). On the other hand, the microsomal cytochrome P-450 in untreated rat livers (0.83 nmol/mg protein) consisted of 62.7% as P-451 II, less than 1% as P-452 and the remainder as P-451 I and other unknown forms.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Sulfoxide reduction catalyzed by guinea pig liver aldehyde oxidase in combination with one-electron reducing flavoenzymes.

The mechanism of the enhancing effect of methyl viologen (MV) and flavin-adenine dinucleotide (FAD) on sulfoxide reduction which is mediated by a combination of aldehyde oxidase (AO) from guinea pig liver and one-electron reducing flavoenzymes, such as milk xanthine oxidase (XO), was examined. The activity of anaerobic reduction of diphenyl sulfoxide (DPSO) to diphenyl sulfide (DPS) was less than 1 nmol/min/mg protein of AO preparation in a system consisting of hypoxanthine, XO and AO. However, the sulfoxide reduction by this system was enhanced about 6- and 100-fold by the additions of FAD and MV, respectively. In the system containing MV or FAD, other one-electron reducing flavoenzymes such as nicotinamide adenine dinucleotide (reduced form) (NADH) dehydrogenase, lipoamide dehydrogenase and glutathione reductase with an appropriate electron donor, could replace XO. The ability of supplemented flavoenzymes to facilitate DPSO reduction correlated with their abilities to reduce MV and FAD. When AO was omitted from the combined system, no sulfoxide reduction was observed. Stoichiometric study revealed that MV semiquinone and FADH2 were oxidized at ratios of 2 and 1 mol, respectively, per mol of DPS formed. These results indicate that either MV or FAD serves as an electron carrier from the supplemented flavoenzymes to AO, a terminal reductase of sulfoxide.

Aldehyde Oxidoreductases↗
PubMed1985

Inductive effect on hepatic enzymes and toxicity of congeners of PCBs and PCDFs.

The present paper describes a marked induction of liver microsomal cytochrome P-450 and cytosolic DT-diaphorase to cause possible disorder of steroid homeostasis and promotion of carcinogenicity of 4-nitroquinoline N-oxide (4-NQO) in rats by pretreatment with 3,4,5,3',4'-pentachlorobiphenyl (PenCB) or 2,3,4,7,8-pentachlorodibenzofuran (PenCDF). The animals were sacrificed 5 days after the pretreatment. These induction experiments showed that 7 alpha-hydroxylation of both progesterone and testosterone in liver microsomes was selectively increased to a great extent, but hydroxylations at the 2 alpha-, 6 beta- and 16 alpha-positions were depressed, together with 5 alpha-reduction. From the same microsomes, three of the strongly induced P-450 isozymes, i.e., high- and low-spin P-448s and P-452, were purified. The last isozyme was most responsible for 7 alpha-hydroxylation of testosterone. The pretreatment, also increased activity of DT-diaphorase and reduction of 4-NQO about 10-fold in liver 9000g supernatants. This reduction of 4-NQO was solely catalyzed by DT-diaphorase and the only product was 4-hydroxylaminoquinoline N-oxide, a proximate carcinogen, indicating that the pretreatment strongly increased production of a proximate carcinogen from 4-NQO. Such an enhancement of the metabolic activation of 4-NQO by the pretreatment was also observed to some extent in the lung and the skin. Persistency of PenCB and PenCDF in the liver of rats was also discussed.

4-Nitroquinoline-1-oxide↗
PubMed1985

Protection against Fasciola gigantica infection in rats administered metacercarial antigens.

Immature worms were recovered from the liver parenchyma of rats which received extracts of metacercariae or adult worms of Fasciola gigantica, after challenge infection. When resistance was assessed by counting the number of immature worms, exposure of the animals to extracts of these two stages of the flukes conferred a significant degree of protection against challenge with F gigantica metacercariae. Rats given the extract of metacercariae were more resistant to infection than rats immunised with the extract of adult worms.

Animals↗
PubMed1983

Different responsiveness of hepatic and pulmonary microsomal mixed function oxidases to phenobarbital-type and 3-methylcholanthrene-type polychlorinated biphenyls in rats.

Inductive effects of pretreatments with a phenobarbital(PB)-type 2, 4, 5, 2', 4', 5'-hexachlorobiphenyl(HCB), a 3-methylcholantrene(MC)-type 3, 4, 5, 3', 4'-pentachlorbiphenyl(PenCB) and a mixed type polychlorinated biphenyl(PCB) mixture, Kanechlor(KC-)400 as well as PB and MC on the hepatic and pulmonary microsomal mixed function oxidases(MFOs) were examined and compared using male Wistar rats. Hepatic cytochrome P-450(448) content was increased 2- to 4-fold by pretreatment with all inducers tested, whereas the pulmonary content was slightly elevated only by the MC-type(MC and PenCB) and mixed type inducers. Benzphetamine(BZ) N-demethylase activity in the liver was strongly enhanced by the PB-type(PB and HCB) and mixed type inducers, but not affected by MC and suppressed by PenCB. Pulmonary BZ N-demethylation was not affected by pretreatments with the MC-type and mixed type inducers while both PB-type inducers decreased the activity. The PB-type inducers, showing a weak inducibility for aryl hydrocarbon hydroxylase(AHH) in the liver, also diminished the activity in the lung. In contrast, a marked enhancement of AHH activity in both organs was caused by pretreatment with the MC-type and mixed type inducers. AHH activity in both organs from PenCB-treated rats was highly sensitive to alpha-naphthoflavone but almost insensitive to SKF 525-A. These results strongly suggest that the pulmonary MFO in rats in inducible only with MC-type but not with PB-type PCB unlike the hepatic MFO.

Animals↗