Papers - Tamura, Hiroomi

Analysis of formaldehyde, acetaldehyde and oligomers in recycled polyethylene terephthalate

Ohkado Y., Kawamura Y., Mutsuga M., Tamura H., Tanamoto K.

Journal of the Food Hygienic Society of Japan (Journal of the Food Hygienic Society of Japan)  46 ( 5 ) 218 - 223 2005.10

Research paper (scientific journal),  ISSN  00156426

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Formaldehyde (FA), acetaldehyde (AA) and oligomers in recycled polyethylene terephthalate (PET) were analyzed by HPLC. All of the physically recycled PET contained detectable levels of FA, AA and oligomers, and the levels were almost the same as in used bottles. Most superclean-like and chemically recycled PET contained lower levels than new pellets. These compounds showed no decrease upon physical recycling, but showed a marked decrease upon superclean-like recycling. In PET sheets made using physically recycled PET, FA was decreased, though AA was increased by the sheeting process as same as new one. FA, AA and oligomers originated from PET resin and their levels in recycled products were almost equivalent to those in new products. It was concluded that there is no particular safety concern about their presence in recycled PET.

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ポリエチレンテレフタレート再生材中の残存金属と再生材使用の判別法.

大門由佳, 河村葉子, 六鹿元雄, 田村悦臣, 棚元憲一*.

食品衛生学雑誌 46   46 2005.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

Metals in recycled polyethylene terephthalate and discrimination method for its use

Ohkado Y., Kawamura Y., Mutsuga M., Tamura H., Tanamoto K.

Journal of the Food Hygienic Society of Japan (Journal of the Food Hygienic Society of Japan)  46 ( 3 ) 109 - 115 2005.06

Research paper (scientific journal),  ISSN  00156426

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Metals in recycled polyethylene terephthalate (PET) were analyzed by ICP-MS following microwave digestion with nitric acid. Physically and superclean-like recycled PET contained both Ge and Sb, and sometimes contained Co, P or Si. In contrast, the chemically recycled PET contained only Ge or Sb, and some samples contained Co. The recycled PETs did not contain Pb or Cd. Ge and Sb were catalysts of the polymerization, and the other metals also originated from the PET resin as additives. It was concluded that there is no safety concern about metals in recycled PET. It became clear that the presence of both Ge and Sb could identify products formed using physically or superclean-like recycled PET. According to this discrimination method, about half of the sheet molding products used recycled PET.

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ポリエチレンテレフタレート再生材中の残存揮発性物質の分析.

大門 由佳, 河村 葉子, 六鹿 元雄, 田村 悦臣, 棚元 憲一*.

食品衛生学雑誌 46   46 2005.02

Research paper (conference, symposium, etc.), Joint Work, Accepted

The effects of coffee on conjugation reactions in human colon carcinoma cells.

Okamura S, Suzuki K, Yanase M, Koizumi M, Tamura H*.

Biol Pharm Bull (Biological and Pharmaceutical Bulletin)  28 ( 2 ) 271-274 - 274 2005.02

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  09186158

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We examined the effect of coffee on conjugation reactions in the human colon carcinoma cell line, Caco-2. After supplementing Caco-2 cultures with both 1-naphthol (200 μM) and various concentrations of coffee, the accumulation of 1-naphthyl sulfate and glucuronide in the growth medium was determined by analytical HPLC over a 24-h period. A strong reduction in sulfo-conjugation (<50% of the control value) was observed in cells treated with coffee (IC50=4.3%), but no effect on glucuronic acid conjugation (glucuronidation) was observed. Coffee was also found to inhibit sulfotransferase (SULT) activity towards 1-naphthol in vitro to a similar extent (IC50=5.1%) as in intact Caco-2 cells, but exhibited no effect upon UDP-glucuronosyl transferase (UGT) activity in vitro. PCR analyses showed no significant changes in the expression of either SULT genes (SULT1A1 and SULT1A3) or UGT genes (UGT1A1 and UGT1A6) following treatment with coffee solutions of up to 5% in concentration. These results suggest that the consumption of coffee can modify sulfo-conjugation reactions within intestinal epithelial cells, which may possibly affect the bioavailability of therapeutic drugs and the toxicity of environmental chemicals. © 2005 Pharmaceutical Society of Japan.

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Analysis of residual volatiles in recycled polyethylene terephthalate

Ohkado Y., Kawamura Y., Mutsuga M., Tamura H., Tanamoto K.

Journal of the Food Hygienic Society of Japan (Journal of the Food Hygienic Society of Japan)  46 ( 1 ) 13 - 20 2005.02

Research paper (scientific journal),  ISSN  00156426

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The residual volatiles in recycled polyethylene terephthalate (PET) were analyzed using headspace/GC/MS. Recycled PET samples were made from PET bottles used for beverages, alcohol and soy sauce, and they were recycled in physical recycling plants, chemical recycling plants and superclean-like recycling trials. The physically recycled PET flakes contained small amounts of volatiles such as ethanol, limonene, 2-methyl-1,3-dioxolane, acetone, octanal and nonanal. Most of them originated from foods packed in bottles, and only 2-methyl-1,3-dioxolane was derived from polymer impurities. In contrast, the superclean-like or chemically recycled PET contained no detectable volatiles, like new PET pellets. The PET sheets shaped from physically recycled PET had no detectable volatiles. Not only the chemically and superclean-like recycled PET, but also the physically recycled PET contained no hazardous volatiles. It was concluded that there is no safety concern about volatiles in recycled PET, for the present use.

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Region- and isoform-specific expression of hydroxysteroid sulfotransferase in rat brain.

Shimizu M, Nakano Y, Yamazaki T, Kimoto T, Kawato S, Tamura H*.

J Health Sci 50   689-692 2004.12

Research paper (conference, symposium, etc.), Joint Work, Accepted

Region- and isoform-specific expression of hydroxysteroid sulfotransferases in rat brain

Shimizu M., Nakano Y., Yamasaki T., Kimoto T., Kawato S., Tamura H.

Journal of Health Science (Journal of Health Science)  50 ( 6 ) 689 - 692 2004.12

Research paper (scientific journal),  ISSN  13449702

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Hydroxysteroid sulfotransferase (HS-ST) is thought to be a key enzyme in the synthesis of neurosteroid sulfates, which are known to act as potent regulators of neuronal activity within the brain. In rat liver, three isoforms of HS-ST (ST2A1, ST2A2 and ST2A5) have now been identified and to further elucidate the precise contribution of each of these variants in neurosteroid sulfation in rat brain, we analyzed the expression of their transcripts in different brain regions using isoform-specific RT-PCR. The expression of ST2A1 was found exclusively in the olfactory bulb and ST2A2 expression levels were most abundant in the hippocampus, but no ST2A5 expression was detectable in any brain region. We then measured the HS-ST activity in these same regions and detected low but significant activity levels in the olfactory bulb and hippocampus, but less activity in the cortex. These activity levels were found to correlate with the mRNA levels of the HS-ST isoforms. Our findings will further our understanding of the physiological role of HS-ST enzymes within the brain, particularly how they affect neurosteroid metabolism and modulate neuronal activity.

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Effect of herbal teas on conjugation reaction in a human colon carcinoma cell line, Caco-2.

Okamura S, Tamura H*.

J Health Sci 50   189-192 2004.04

Research paper (conference, symposium, etc.), Joint Work, Accepted

Oxidative stress induces GSTP1 and CYP3A4 expression in the human erythroleukemia cell line, K562.

Nagai F, Kato E, Tamura H*.

Biol Pharm Bull (Biological and Pharmaceutical Bulletin)  27 ( 4 ) 492-495 - 495 2004.04

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  09186158

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To explore the effects of oxidative stress on metabolizing enzymes in blood cells, we examined the effect of hydrogen peroxide (H2O2) on glutathione S-transferase (GST) and cytochrome P450 (CYP) expression in a human erythroleukemic cell line, K562. After adding H2O2 (up to 100 μM) to the culture medium of K562 cells, the expression levels of GST and CYP enzymes were monitored by RT-PCR. The expression of GSTP1 and CYP3A4 was induced by oxidative stress. Quantitative PCR and immunoblot analysis revealed a 3- to 4-fold increase in GSTP1 and CYP3A4 mRNA, and a 2- to 3-fold increase in GSTP1 and CYP3A4 protein levels, 3 d after the addition of 100 μM H2O2. Induction was H2O2 dose-dependent and also depended on the length of culture. Our results suggest that oxidative stress may affect GST and/or CYP expression in human blood cells, which may alter the metabolism of drugs and xenobiotics and thus, the toxicity of these compounds to the blood cells. © 2004 Pharmaceutical Society of Japan.

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Effect of herbal teas on conjugation reactions in a human colon carcinoma cell line, Caco-2

Okamura S., Tamura H.

Journal of Health Science (Journal of Health Science)  50 ( 2 ) 189 - 192 2004.04

Research paper (scientific journal),  ISSN  13449702

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We examined the effect of herbal teas (including black and green teas) on conjugation reactions within a human colon carcinoma cell line, Caco-2. After adding herbal tea to the culture medium of Caco-2 cells, accumulation of 1-naphthyl sulfate and glucuronide was determined within the medium by analytical HPLC prior to 24 hr. A reduction in sulfoconjugation (< 50% of the control value) was observed in cells treated with 5% solutions of green tea, jasmine tea or black tea. Mild induction of sulfoconjugation (20-30%) was detected in cells exposed to 5% solutions of hibiscus or lemongrass tea. In addition, a slight reduction (20-30%) in glucuronic acid conjugation (glucuronidation) was observed in cells treated with rose red, peppermint, lavender or St. John's wort. At low concentrations, ranging from 0.1-1.0%, several herbal teas resulted in weak but significant induction (10-20%) of both types of conjugation reactions. These results suggest that herbal teas modify conjugation reactions within intestinal epithelial cells, thereby potentially affecting the bioavailability and toxicity of therapeutic drugs and environmental chemicals.

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Identification and purification of sulfotransferases for 20-hydroxysteroid from the larval fat body of a freshfly, Sarcophaga peregrina.

Matsumoto E, Matsui M, Tamura H*.

Biosci Biotechnol Biochem 67   1780-1785 2003.08

Research paper (conference, symposium, etc.), Joint Work, Accepted

Sulfoconjugation of bisphenol A in a human neuroblastoma cell line, NB-1.

Ishii Y, Tamura H*.

J Health Sci (Journal of Health Science)  49 ( 4 ) 319-323 - 323 2003.04

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  13449702

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Bisphenol A (BPA) is a common environmental endocrine disruptor and BPA sulfate has been demonstrated as one of metabolites of BPA. Since it has been observed to have effects on the central nervous system (CNS), we examined the effects of sulfoconjugation on the toxicity of BPA in a human neuroblastoma cell line, NB-1. NB-1 cells showed limited but significant sulfotransferase activity toward BPA in vitro (Km = 74 μM, Vmax = 7.8 pmol/min/mg). Accumulation of BPA sulfate was observed for 12 hr to 4 days after 10 μM BPA was added to a culture of NB-1 cells. These results suggest that BPA is partly detoxified by the sulfoconjugation reaction in human neuronal cells.

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Identification and purification of sulfotransferases for 20-hydroxysteroid from the larval fat body of a fleshfly, sarcophag peregrina

Matsumoto E., Matsui M., Tamura H.

Bioscience, Biotechnology and Biochemistry (Bioscience, Biotechnology and Biochemistry)  67 ( 8 ) 1780 - 1785 2003.01

Research paper (scientific journal),  ISSN  09168451

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Sulfotransferase (ST) activity for 20-hydroxyecdysone (20E) was identified in a larval fat body lysate of the fleshfly, Sarcophaga peregrina, but not in the hemolymph. The activity was highly sensitive to 2,6-dichloro-4-nitrophenol (DCNP) (IC50=0.61 μM), a specific inhibitor of phenol ST (P-ST), but insensitive to triethylamine, a hydroxysteroid ST inhibitor. These results suggest that 20E-specific ST enzymes belong to the P-ST family, despite the fact that 20E is a hydroxysteroid. In addition to 20E ST activity, a relatively high level of 2-naphthol ST activity was detected in the fat body lysate. The ST activity for both substrates transiently decreased to the 50% of maximal levels, 6 hrs after induction of pupation. The ST enzymes were separated on a DEAE-cellulose column. The 20E-ST enzymes were eluted around 50 mM KCl as two separate peaks of close proximity and the P-ST was eluted at 0.1 M KCl. The 20E ST enzymes were further purified using 3′-phosphoadenosine 5′-phosphate (PAP)-agarose affinity column chromatography. Both of the eluted active fractions demonstrated 43-kDa proteins on SDS-polyacrylamide gel. Photoaffinity labeling with [35S]-3′-phosphoadenosine 5′-phosphosulfate (PAPS) showed 43-kDa bands in the fat body lysate, as well as in the purified fractions. These results suggest that the 43-kDa proteins catalyze 20E sulfation within the fat body of S. peregrina. © 2003 by Japan Society for Bioscience, Biotechnology, and Agrochemistry.

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Cytochrome P450-dependent neurosteroid synthesis in the rat brain hippocampal neurons

Kimoto T., Tsurugizawa T., Ohta Y., Makino J., Tamura H., Hojo Y., Enami T., Kawato S.

International Congress Series (International Congress Series)  1233 ( C ) 127 - 137 2002.11

Research paper (scientific journal),  ISSN  05315131

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We have demonstrated the neuronal localization of neurosteroidogenic systems as well as the regulation of neurosteroidogenic activity in an adult rat hippocampus. The expressions of steroidogenic enzymes (cytochrome P450scc, adrenodoxin (ADX), NADPH-adrenodoxin reductase (ADR), hydroxysteroid sulfotransferase and steroidogenic acute regulatory protein (StAR)) were observed principally in pyramidal neurons and granule neurons by means of immunohistochemical staining. The expression of P450scc, redox partners, sulfotransferase and StAR was also confirmed by Western blot analysis.Exposing the neurons to N-methyl-D-aspartate (NMDA) stimulated the process of active neurosteroidogenesis. Upon stimulation with NMDA, the significant net production of pregnenolone (PREG) and pregnenolone sulfate (PREGS) was observed in the hippocampus. This neurosteroid production was considerably suppressed by the addition of antagonists of NMDA receptors, by Ca2+ depletion or by the addition of an inhibitor of P450scc. Upon stimulation with NMDA, the processing of full-length StAR (37-kDa) to the truncated 30-kDa StAR was observed. Taken together, these observations imply that hippocampal neurons synthesize neurosteroids. This synthesis may be stimulated and regulated by glutamate-mediated synaptic communication. We also discuss the possibility that PREGS may act as a paracrine modulator of NMDA receptors. © 2002 Elsevier Science B.V.

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Identification and localization of two hydroxysteroid sulfotransferase in the human brain.

Shimizu M, Tamura H*.

J Health Sci 48   467-472 2002.10

Research paper (conference, symposium, etc.), Joint Work, Accepted

Identification and localization of two hydroxysteroid sulfotransferases in the human brain

Shimizu M., Tamura H.

Journal of Health Science (Journal of Health Science)  48 ( 5 ) 467 - 472 2002.10

Research paper (scientific journal),  ISSN  13449702

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Hydroxysteroid sulfotransferase (SULT2) is thought to be a key enzyme in the synthesis of neurosteroid sulfates, which are known to act as potent regulators of neuronal activity within the brain. We detected two SULT2 mRNAs (SULT2A1 and SULT2B1b) in the human brain. We isolated their cDNAs, and determined the location of their expression in the brain by Northern blot hybridization. Exclusive SULT2A1 expression was detected in the thalamus and hypothalamus, whereas SULT2B1b expression was detected throughout the brain in varying amounts, reaching levels two to three times greater in some regions than in others. These findings further our understanding of the physiological role of SULT2 enzymes within the human brain, particularly how they affect neurosteroid metabolism, and thus, modulate neuronal activity within the brain.

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Cytochrome P450 Expression in Rat Ocular Tissues and Its Induction by Phenobarbital.

Tanaka H, Hirayama I, Takehana M,Kobayashi S, Tamura H*.

J Health Sci (Journal of Health Science)  48 ( 4 ) 346-349 - 349 2002.09

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  13449702

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Composition and inducibility of cytochrome P450 (CYP) in ocular tissues were investigated using reverse transcription-polymerase chain reaction (RT-PCR) and immunoblot techniques. Composition of ocular CYPs is more restricted than that of hepatic forms. High levels of CYP2B1/2 and reduced levels of CYP2C11 expression were detected in rat ocular tissues. Phenobarbital induced CYP2B1/2 expression in the lens but not in the rest of the eye, whereas CYP2C11 induction was observed in both regions. In addition, CYP2B1/2 proteins were found to be prominent in the retina. Our data indicate eye-specific regulation of CYP expression.

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Cytochrome P450 (CYP) expression in human myeloblastic and lymphoid cell lines.

Nagai F, Hiyoshi Y, Sugimachi K, Tamura H*.

Biol Pharm Bull (Biological and Pharmaceutical Bulletin)  25 ( 3 ) 383・385 - 385 2002.03

Research paper (conference, symposium, etc.), Joint Work, Accepted,  ISSN  09186158

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To explore the physiological roles of cytochrome P450 (CYP) in peripheral blood cells, we examined which isoforms of CYP families were expressed in human myeloid leukemia cell lines (U937, HL-60 and K562) and lymphoid cell lines (BALL-1, MOLT-4 and Jurkat) by RT-PCR. We observed relatively high expression of CYP1A1, CYP1B1, CYP2A6, CYP2A7, CYP2D6, and CYP2E1 in all cell types, but CYP2A13 and CYP2C9 expression was not detected. Expressions of aryl hydrocarbon (Ah) receptor and Ah receptor nuclear translocator (ARNT), which mediate induction of the CYP1 family, were also detected in all cell types. Cell-type specific expression of CYP3A4 and CYP3A5 was observed in MOLT-4 and K562 cells. Weak, but significant, expression of CYP3A7 was detected in K562 cells. The profile of CYP expression in the culture cells reported here provides information that furthers our understanding of the physiological roles of CYP enzymes in human blood cells.

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Expression profiling of drug metabolizing enzymes in human myeloblastic cell lines.

Tamura H*, Nagai F.

Drug Metabol Rev 33   158 2001.11

Research paper (conference, symposium, etc.), Joint Work, Accepted