The Experts below are selected from a list of 477 Experts worldwide ranked by ideXlab platform
Masakuni Degawa - One of the best experts on this subject based on the ideXlab platform.
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ionic lead but not other ionic metals ni2 co2 and cd2 suppresses 2 methoxy 4 Aminoazobenzene mediated cytochrome p450ia2 cyp1a2 induction in rat liver
Biological & Pharmaceutical Bulletin, 1995Co-Authors: Masakuni Degawa, Hiroshi Arai, Masako Kubota, Yoshiyuki HashimotoAbstract:Male F344 rats were pretreated with lead nitrate, nickel chloride, cobalt chloride or cadmium chloride, and their effects on the induction of cytochrome P450 (CYP) enzymes, mainly CYP1A2 enzyme, with 2-methoxy-4-Aminoazobenzene (2-MeO-AAB) in the livers were comparatively examined by enzymatical, immunochemical, and molecular biological methods. When rats were pretreated with each ionic metal, the total CYP amount in the liver microsomes decreased, as compared with that of rats treated with 2-MeO-AAB alone. However, among the ionic metals used only lead reduced the levels of the mRNA and protein of CYP1A2 induced with 2-MeO-AAB in the rat liver, and decreased the microsomal activity (per CYP) for CYP1A2-mediated mutagenesis. Furthermore, ionic lead, but not other ionic metals, showed an ability to induce a placental form of glutathione S-transferase (GST-P). The level of CYP1A2 induced with 2-MeO-AAB was decreased along with increase in that of the induced GST-P.
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mutagenic activation of 3 methoxy 4 Aminoazobenzene by mouse renal cytochrome p450 cyp4b1 cloning and characterization of mouse cyp4b1
Archives of Biochemistry and Biophysics, 1995Co-Authors: Susumu Imaoka, Masakuni Degawa, Toyoko Hiroi, Y Tamura, Hiroshi Yamazaki, Tsutomu Shimada, Masayuki Komori, Yoshihiko FunaeAbstract:A new P450 responsible for mutagenic activation of 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) which is a potent procarcinogen was purified from renal microsomes of male mice using an index of umu gene expression. The purified P450 had high bioactivation toward 3-MeO-AAB and also 2-aminofluorene and 2-aminoanthracene. The antibody against this P450 completely inhibited mutagenic activation of 3-MeO-AAB of mouse renal microsomes. With immunoblotting, this form was present abundantly in renal microsomes of male mice but not in those of female mice. This P450 was also present in pulmonary microsomes of male and female mice but not in hepatic microsomes. The NH2-terminal amino acid sequence analysis indicated that this form belonged to the CYP4B subfamily. Thus, mouse kidney cDNA library was screened with rat CYP4B1 probe. The cDNA-deduced amino acid sequence of isolated cDNA consisted of 511 amino acids and bore 90, 86, and 84% similarities to rat, rabbit, and human CYP4B1, respectively. The NH2-terminal amino acid sequence of the purified renal P450 and amino acid sequence of BrCN-digested peptides from the purified P450 agreed with the cDNA-deduced amino acid sequence. These results suggest that CYP4B1 is a major form in renal microsomes of male mice and plays a major role in mutagenic activation of 3-MeO-AAB. In extrahepatic tissue, CYP4B1 may contribute to chemical carcinogenesis.
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the carcinogenicity of methoxyl derivatives of 4 Aminoazobenzene correlation between dna adducts and genotoxicity
Environmental Health Perspectives, 1994Co-Authors: Misaki Kojima, Yoshiyuki Hashimoto, Masakuni Degawa, Mariko TadaAbstract:To elucidate the cause of the difference in genotoxic activity between carcinogenic 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) and noncarcinogenic 2-methoxy-4-Aminoazobenzene (2-MeO-AAB), we analyzed DNA adducts in the livers of rats exposed to either of these chemicals and studied the resulting biologic potential with the aid of in vitro modified M13 phage DNA. 32P-Postalbeling analysis revealed that the carcinogen 3-MeO-AAB produced 20-fold higher amounts of adducts than did 2-MeO-AAB. Five adducts were formed in the 3-MeO-AAB case whereas only one adduct was apparent in 2-MeO-AAB-treated rat. Studies of in vitro DNA replication using N-hydroxy (N-OH)-aminoazo dye-modified M13 phage DNA as a template demonstrated inhibition by 3-MeO-AAB adducts to be substantially greater than in the 2-MeO-AAB-adducts. The specificity of mutagenesis induced in M13mp9 phage DNA by these chemicals also was analyzed after transfection into SOS-induced Escherichia coli JM103, mutation frequencies being higher with N-OH-3-MeO-AAB- than N-OH-2-MeO-AAB-modified DNA. The mutation spectra differed in each case. Our data suggest that the difference in hepatocarcinogenic activity between the two chemicals depends not only on qualitative and quantitative variation in adduct formation but also on conformation changes in modified DNA.
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differences in dna damage induced by mutagenic and nonmutagenic 4 Aminoazobenzene derivatives in escherichia coli
Mutation Research-dna Repair, 1992Co-Authors: Misaki Kojima, Yoshiyuki Hashimoto, Masakuni Degawa, Toshiteru Morita, Mariko TadaAbstract:Abstract DNA lesions produced in Escherichia coli AB2500 ( uvrA ) exposed to the carcinogen N -hydroxy-3-methoxy-4-Aminoazobenzene (N-OH-3-MeO-AAB) or the noncarcinogen N -hydroxy-2-methoxy-4-Aminoazobenzene (N-OH-2-MeO-AAB) were investigated by alkaline sucrose gradient sedimentation and 32 P-postlabeling analysis. Alkali-labile sites appeared to be formed equally in cells treated with both Aminoazobenzene derivatives. 32 P-Postlabeling analysis revealed that the 3-MeO-AAB-DNA adduct level was 25-fold higher than that for 2-MeO-AAB-DNA adducts. In addition to major adducts, 4 minor spots were detected in N-OH-3-MeO-AAB-treated cells, while only one major adduct was found in N-OH-2-MeO-AAB-treated cells. The mutagenecities and cytotoxicities were also determined with E. coli with different repair capacities; we found that repair of 3-MeO-AAB damages is strongly dependent on the UVR repair system. Moreover, N-OH-3-MeO-AAB, but not N-OH-2-MeO-AAB, could induce recA and umuC gene expression, which was higher in uvrA strains than in the wild type.
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immunological detection and quantitation of dna adducts formed by 4 Aminoazobenzene species in vivo
Japanese Journal of Cancer Research, 1992Co-Authors: Misaki Kojima, Masakuni Degawa, Toshiteru Morita, Tomoyuki Shirai, Mariko TadaAbstract:Antibodies to 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) and 2-methoxy-4-Aminoazobenzene (2-MeO-AAB) DNA adducts were raised in rabbits against in vitro-adducted DNA samples. The enzyme-linked immunosorbent assay (ELISA) was used to determine the sensitivity and specificity of these antibodies. They proved highly specific for the modified DNA used as the immunogen, but cross-reacted with each other. Moreover, they showed cross reactivity with DNA modified by 4-(o-tolylazo)-o-toluidine, but not by other carcinogens, such as 4-aminobiphenyl or 4-nitroquinoline 1-oxide. The 50% inhibition level of antibody binding in the competitive ELISA was at 10–20 fmol of modified base per assay (equivalent to 1–2 adducts per 106 bases). Immunohistochemical staining indicated that these antibodies bind specifically to nuclear components of the liver in rats given either 3-MeO-AAB or 2-MeO-AAB at the dose of 50 mg/kg body weight.
Zhong Lin Wang - One of the best experts on this subject based on the ideXlab platform.
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self powered electrochemical oxidation of 4 Aminoazobenzene driven by a triboelectric nanogenerator
ACS Nano, 2017Co-Authors: Shuyan Gao, Xianjun Wei, Miao Wang, Miao Tian, Tao Jiang, Zhong Lin WangAbstract:A rotary disc-structured triboelectric nanogenerator (rd-TENG) on the basis of free-standing electrification has been designed, where the aluminum composite panel has not been tailored to the stator becauseit is commercially available and cost-effective, has good electronic conductivity, and is easily processed. With the rotating speed increasing from 200 to 1000 rpm, the short-circuit current (Isc) is sharply enhanced from 50 μA to 200 μA, while the measured open-circuit voltage (Voc) and transferred charge (Qtr) almost keep constant, 600 V and 0.4 μC, respectively. The matched load for the rd-TENG at a rotating speed of 600 rpm is 2.7 MΩ, generating a maximum power of 19.75 mW, which corresponds to a maximum power density of 2.28 W m–2. Using the electric power generated by such a rd-TENG, highly toxic and carcinogenic 4-Aminoazobenzene can be selectively treated to produce CO2 or an oligomer via reasonably controlling electrochemical oxidation potentials. The underlying mechanism is tentatively propose...
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Self-Powered Electrochemical Oxidation of 4‑Aminoazobenzene Driven by a Triboelectric Nanogenerator
2017Co-Authors: Shuyan Gao, Xianjun Wei, Miao Wang, Miao Tian, Tao Jiang, Zhong Lin WangAbstract:A rotary disc-structured triboelectric nanogenerator (rd-TENG) on the basis of free-standing electrification has been designed, where the aluminum composite panel has not been tailored to the stator becauseit is commercially available and cost-effective, has good electronic conductivity, and is easily processed. With the rotating speed increasing from 200 to 1000 rpm, the short-circuit current (Isc) is sharply enhanced from 50 μA to 200 μA, while the measured open-circuit voltage (Voc) and transferred charge (Qtr) almost keep constant, 600 V and 0.4 μC, respectively. The matched load for the rd-TENG at a rotating speed of 600 rpm is 2.7 MΩ, generating a maximum power of 19.75 mW, which corresponds to a maximum power density of 2.28 W m–2. Using the electric power generated by such a rd-TENG, highly toxic and carcinogenic 4-Aminoazobenzene can be selectively treated to produce CO2 or an oligomer via reasonably controlling electrochemical oxidation potentials. The underlying mechanism is tentatively proposed based on the cyclic voltammogram, gas chromatograph-mass spectrometer, electrochemical impedance spectroscopy, and UV–vis spectra. Here the electrochemical degradation in a single-compartment cell is more valid, preferable, and feasible. The output Voc and rectified current of rd-TENG guarantee its extensive application to self-power electrochemical degradation of other azo compounds, i.e., 2-(4-dimethylaminophenylazo) benzoic acid, to CO2. This work suggests that rd-TENG, sustainable energy, can be feasibly designed to self-power a practical electrochemical treatment of dyeing wastewater by harvesting vibration energy
Tsutomu Shimada - One of the best experts on this subject based on the ideXlab platform.
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mutagenic activation of 3 methoxy 4 Aminoazobenzene by mouse renal cytochrome p450 cyp4b1 cloning and characterization of mouse cyp4b1
Archives of Biochemistry and Biophysics, 1995Co-Authors: Susumu Imaoka, Masakuni Degawa, Toyoko Hiroi, Y Tamura, Hiroshi Yamazaki, Tsutomu Shimada, Masayuki Komori, Yoshihiko FunaeAbstract:A new P450 responsible for mutagenic activation of 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) which is a potent procarcinogen was purified from renal microsomes of male mice using an index of umu gene expression. The purified P450 had high bioactivation toward 3-MeO-AAB and also 2-aminofluorene and 2-aminoanthracene. The antibody against this P450 completely inhibited mutagenic activation of 3-MeO-AAB of mouse renal microsomes. With immunoblotting, this form was present abundantly in renal microsomes of male mice but not in those of female mice. This P450 was also present in pulmonary microsomes of male and female mice but not in hepatic microsomes. The NH2-terminal amino acid sequence analysis indicated that this form belonged to the CYP4B subfamily. Thus, mouse kidney cDNA library was screened with rat CYP4B1 probe. The cDNA-deduced amino acid sequence of isolated cDNA consisted of 511 amino acids and bore 90, 86, and 84% similarities to rat, rabbit, and human CYP4B1, respectively. The NH2-terminal amino acid sequence of the purified renal P450 and amino acid sequence of BrCN-digested peptides from the purified P450 agreed with the cDNA-deduced amino acid sequence. These results suggest that CYP4B1 is a major form in renal microsomes of male mice and plays a major role in mutagenic activation of 3-MeO-AAB. In extrahepatic tissue, CYP4B1 may contribute to chemical carcinogenesis.
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roles of different cytochrome p450 enzymes in bioactivation of the potent hepatocarcinogen 3 methoxy 4 Aminoazobenzene by rat and human liver microsomes
Carcinogenesis, 1991Co-Authors: Hiroshi Yamazaki, Masakuni Degawa, Susumu Imaoka, Yoshihiko Funae, Yukiharu Inui, Peter F Guengerich, Tsutomu ShimadaAbstract:The potent hepatocarcinogen 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) has been reported to be bioactivated to mutagenic intermediates by rat liver microsomal cytochrome P450 (P450) and to be a selective inducer of rat P450IA2. In this study we have further investigated the roles of individual rat and human P450 enzymes in the bioactivation of this hepatocarcinogen in a Salmonella typhimurium TA1535/pSK1002 system where umu response is indicative of DNA damage. 3-MeO-AAB was found to be bioactivated by liver microsomal enzymes from rats and humans in this assay system. The liver microsomal activities are increased by pretreatment of rats with various P450 inducers such as phenobarbital (PB), beta-naphthoflavone (BNF), dexamethasone (DEX), acetone, ethanol, isoniazid (INH), diphenylhydantoin and valproic acid, and can be inhibited considerably by SKF-525A and metyrapone. alpha-Naphthoflavone (ANF) is also an inhibitor for the reaction catalyzed in BNF-treated rats, but stimulated the microsomal activity in DEX-treated rats. Evidence has also been obtained that specific antibodies raised against P450IIB1, P450IA1 or IA2, P450IIE1, and P450IIIA2 inhibited the activation in liver microsomes from rats pretreated with PB, BNF, INH and DEX respectively, suggesting the possible roles of several P450 enzymes in the bioactivation of 3-MeO-AAB. The results obtained with reconstituted monooxygenase systems containing various rat P450 enzymes are highly supportive of this conclusion. Human liver microsomal activation of 3-MeO-AAB was also inhibited to various extents by antibodies raised against P450IA2, P450MP, P450IIE1 and P450IIIA4. In a reconstituted system containing purified forms of human P450, P450IA2 was the most active in catalyzing 3-MeO-AAB, followed by P450IIIA4 and P450MP. ANF, a known activator of P450IIIA-catalyzed reactions, caused an increase in activation of 3-MeO-AAB in human liver microsomal and P450IIIA4- and P450MP-containing reconstituted systems. From these results it is concluded that multiple P450 enzymes in rat and human liver microsomes are involved in the bioactivation of 3-MeO-AAB, regardless of its selective induction of the rat P450IA2 gene.
Yoshihiko Funae - One of the best experts on this subject based on the ideXlab platform.
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mutagenic activation of 3 methoxy 4 Aminoazobenzene by mouse renal cytochrome p450 cyp4b1 cloning and characterization of mouse cyp4b1
Archives of Biochemistry and Biophysics, 1995Co-Authors: Susumu Imaoka, Masakuni Degawa, Toyoko Hiroi, Y Tamura, Hiroshi Yamazaki, Tsutomu Shimada, Masayuki Komori, Yoshihiko FunaeAbstract:A new P450 responsible for mutagenic activation of 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) which is a potent procarcinogen was purified from renal microsomes of male mice using an index of umu gene expression. The purified P450 had high bioactivation toward 3-MeO-AAB and also 2-aminofluorene and 2-aminoanthracene. The antibody against this P450 completely inhibited mutagenic activation of 3-MeO-AAB of mouse renal microsomes. With immunoblotting, this form was present abundantly in renal microsomes of male mice but not in those of female mice. This P450 was also present in pulmonary microsomes of male and female mice but not in hepatic microsomes. The NH2-terminal amino acid sequence analysis indicated that this form belonged to the CYP4B subfamily. Thus, mouse kidney cDNA library was screened with rat CYP4B1 probe. The cDNA-deduced amino acid sequence of isolated cDNA consisted of 511 amino acids and bore 90, 86, and 84% similarities to rat, rabbit, and human CYP4B1, respectively. The NH2-terminal amino acid sequence of the purified renal P450 and amino acid sequence of BrCN-digested peptides from the purified P450 agreed with the cDNA-deduced amino acid sequence. These results suggest that CYP4B1 is a major form in renal microsomes of male mice and plays a major role in mutagenic activation of 3-MeO-AAB. In extrahepatic tissue, CYP4B1 may contribute to chemical carcinogenesis.
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roles of different cytochrome p450 enzymes in bioactivation of the potent hepatocarcinogen 3 methoxy 4 Aminoazobenzene by rat and human liver microsomes
Carcinogenesis, 1991Co-Authors: Hiroshi Yamazaki, Masakuni Degawa, Susumu Imaoka, Yoshihiko Funae, Yukiharu Inui, Peter F Guengerich, Tsutomu ShimadaAbstract:The potent hepatocarcinogen 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) has been reported to be bioactivated to mutagenic intermediates by rat liver microsomal cytochrome P450 (P450) and to be a selective inducer of rat P450IA2. In this study we have further investigated the roles of individual rat and human P450 enzymes in the bioactivation of this hepatocarcinogen in a Salmonella typhimurium TA1535/pSK1002 system where umu response is indicative of DNA damage. 3-MeO-AAB was found to be bioactivated by liver microsomal enzymes from rats and humans in this assay system. The liver microsomal activities are increased by pretreatment of rats with various P450 inducers such as phenobarbital (PB), beta-naphthoflavone (BNF), dexamethasone (DEX), acetone, ethanol, isoniazid (INH), diphenylhydantoin and valproic acid, and can be inhibited considerably by SKF-525A and metyrapone. alpha-Naphthoflavone (ANF) is also an inhibitor for the reaction catalyzed in BNF-treated rats, but stimulated the microsomal activity in DEX-treated rats. Evidence has also been obtained that specific antibodies raised against P450IIB1, P450IA1 or IA2, P450IIE1, and P450IIIA2 inhibited the activation in liver microsomes from rats pretreated with PB, BNF, INH and DEX respectively, suggesting the possible roles of several P450 enzymes in the bioactivation of 3-MeO-AAB. The results obtained with reconstituted monooxygenase systems containing various rat P450 enzymes are highly supportive of this conclusion. Human liver microsomal activation of 3-MeO-AAB was also inhibited to various extents by antibodies raised against P450IA2, P450MP, P450IIE1 and P450IIIA4. In a reconstituted system containing purified forms of human P450, P450IA2 was the most active in catalyzing 3-MeO-AAB, followed by P450IIIA4 and P450MP. ANF, a known activator of P450IIIA-catalyzed reactions, caused an increase in activation of 3-MeO-AAB in human liver microsomal and P450IIIA4- and P450MP-containing reconstituted systems. From these results it is concluded that multiple P450 enzymes in rat and human liver microsomes are involved in the bioactivation of 3-MeO-AAB, regardless of its selective induction of the rat P450IA2 gene.
Hiroshi Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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mutagenic activation of 3 methoxy 4 Aminoazobenzene by mouse renal cytochrome p450 cyp4b1 cloning and characterization of mouse cyp4b1
Archives of Biochemistry and Biophysics, 1995Co-Authors: Susumu Imaoka, Masakuni Degawa, Toyoko Hiroi, Y Tamura, Hiroshi Yamazaki, Tsutomu Shimada, Masayuki Komori, Yoshihiko FunaeAbstract:A new P450 responsible for mutagenic activation of 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) which is a potent procarcinogen was purified from renal microsomes of male mice using an index of umu gene expression. The purified P450 had high bioactivation toward 3-MeO-AAB and also 2-aminofluorene and 2-aminoanthracene. The antibody against this P450 completely inhibited mutagenic activation of 3-MeO-AAB of mouse renal microsomes. With immunoblotting, this form was present abundantly in renal microsomes of male mice but not in those of female mice. This P450 was also present in pulmonary microsomes of male and female mice but not in hepatic microsomes. The NH2-terminal amino acid sequence analysis indicated that this form belonged to the CYP4B subfamily. Thus, mouse kidney cDNA library was screened with rat CYP4B1 probe. The cDNA-deduced amino acid sequence of isolated cDNA consisted of 511 amino acids and bore 90, 86, and 84% similarities to rat, rabbit, and human CYP4B1, respectively. The NH2-terminal amino acid sequence of the purified renal P450 and amino acid sequence of BrCN-digested peptides from the purified P450 agreed with the cDNA-deduced amino acid sequence. These results suggest that CYP4B1 is a major form in renal microsomes of male mice and plays a major role in mutagenic activation of 3-MeO-AAB. In extrahepatic tissue, CYP4B1 may contribute to chemical carcinogenesis.
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roles of different cytochrome p450 enzymes in bioactivation of the potent hepatocarcinogen 3 methoxy 4 Aminoazobenzene by rat and human liver microsomes
Carcinogenesis, 1991Co-Authors: Hiroshi Yamazaki, Masakuni Degawa, Susumu Imaoka, Yoshihiko Funae, Yukiharu Inui, Peter F Guengerich, Tsutomu ShimadaAbstract:The potent hepatocarcinogen 3-methoxy-4-Aminoazobenzene (3-MeO-AAB) has been reported to be bioactivated to mutagenic intermediates by rat liver microsomal cytochrome P450 (P450) and to be a selective inducer of rat P450IA2. In this study we have further investigated the roles of individual rat and human P450 enzymes in the bioactivation of this hepatocarcinogen in a Salmonella typhimurium TA1535/pSK1002 system where umu response is indicative of DNA damage. 3-MeO-AAB was found to be bioactivated by liver microsomal enzymes from rats and humans in this assay system. The liver microsomal activities are increased by pretreatment of rats with various P450 inducers such as phenobarbital (PB), beta-naphthoflavone (BNF), dexamethasone (DEX), acetone, ethanol, isoniazid (INH), diphenylhydantoin and valproic acid, and can be inhibited considerably by SKF-525A and metyrapone. alpha-Naphthoflavone (ANF) is also an inhibitor for the reaction catalyzed in BNF-treated rats, but stimulated the microsomal activity in DEX-treated rats. Evidence has also been obtained that specific antibodies raised against P450IIB1, P450IA1 or IA2, P450IIE1, and P450IIIA2 inhibited the activation in liver microsomes from rats pretreated with PB, BNF, INH and DEX respectively, suggesting the possible roles of several P450 enzymes in the bioactivation of 3-MeO-AAB. The results obtained with reconstituted monooxygenase systems containing various rat P450 enzymes are highly supportive of this conclusion. Human liver microsomal activation of 3-MeO-AAB was also inhibited to various extents by antibodies raised against P450IA2, P450MP, P450IIE1 and P450IIIA4. In a reconstituted system containing purified forms of human P450, P450IA2 was the most active in catalyzing 3-MeO-AAB, followed by P450IIIA4 and P450MP. ANF, a known activator of P450IIIA-catalyzed reactions, caused an increase in activation of 3-MeO-AAB in human liver microsomal and P450IIIA4- and P450MP-containing reconstituted systems. From these results it is concluded that multiple P450 enzymes in rat and human liver microsomes are involved in the bioactivation of 3-MeO-AAB, regardless of its selective induction of the rat P450IA2 gene.
