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N Ariyoshi

Publications and source records attributed to N Ariyoshi.

At least 37 records · Page 2Linked to original sources
PubMed1997

Metabolism of 2,4,5,2',4',5'-hexachlorobiphenyl (PCB153) in guinea pig.

1. The in vitro and in vivo metabolism of 2,4,5,2',4',5'-hexachlorobiphenyl (PCB153) in guinea pig has been studied. 2. Seven metabolites were detected in the faeces of PCB153-treated animals and three were identical to those produced by dog liver microsomes. The detection of a metabolite where a chlorine atom was shifted from the 2- to 3-position strongly suggested the involvement of 2,3-arene oxide intermediate, and evidence for the concomitant formation of a 3,4-arene oxide intermediate was provided by identifying other two minor metabolites which were dechlorinated at the 4-position. 3. In vitro studies using liver microsomes from guinea pigs revealed that the 2,3-arene oxide and 3-hydroxylation pathways are the predominant metabolic routes compared with the 3,4-arene oxide pathway. Although the guinea pig is an another species that can metabolize PCB153 mainly to the 2,3-arene oxide intermediate, the rate of formation was only about one-tenth of the dog. 4. These results indicate that the ability to form this unusual 2,3-arene oxide intermediate may not be responsible for high excretion rate of this congener. Our data also suggest that the cytochrome P450-catalysed metabolism of PCB153 in the guinea pig and dog are similar, whereas for post-cytochrome P450 metabolism, the guinea pig resembles the rabbit.

Animals↗
PubMed1997

[Production of antibody against cytosolic 54 kDa protein in rat liver--evidence of the significant induction by a highly toxic coplanar polychlorinated biphenyl].

We have reported that a 54 kDa protein in rat liver cytosol is highly inducible by treatment with 3,3',4,4',5-pentachlorobiphenyl (PenCB) or 3-methylcholanthrene (MC) using SDS-polyacrylamide gel electrophoresis. Internal amino acid sequences of this protein in the rat liver were highly homologous to those of selenium binding protein (SeBP) or acetaminophen binding protein (APBP) in mouse liver cytosol. In this paper, the purification and characterization of this protein were demonstrated. MC was given at a dose of 20 mg/kg for 3 consecutive days. The liver cytosolic 54 kDa protein was purified twice from the MC-treated male Wistar rats by Rotofore Cell procedure to apparent single on SDS-polyacrylamide gel electrophoresis, and the rabbit antiserum against this protein was obtained. Male Wistar rats were given PenCB in corn oil at a single dose of 25 mg/kg i.p. The liver cytosol was prepared on the 5th day after the treatment and subjected to immunoblot analysis. The 54 kDa protein was markedly induced in the liver cytosol of PenCB-treated rats. Immunoblot analysis after two-dimensional gel electrophoresis suggested that there could be isoforms of 54 kDa protein. The induction of the 54 kDa protein with PenCB was assumed to be mediated through Ah-receptor. The physiological role of the 54 kDa protein was discussed together with SeBP and APBP, the role of which has not yet been elucidated.

Animals↗
PubMed1997

[Effect of co-planar polychlorinated biphenyl on the hepatic glutathione peroxidase redox system in rats and guinea pigs].

The effect of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on hepatic glutathione peroxidase (GPx) redox system was studied in vivo in rats and guinea pigs. PCB 126 treatment caused significant reduction of Se-dependent and -non-dependent GPx activity in rats. In agreement with this, the content of glutathione (GSH) and the activities of GSH reductase (GR) and gamma-glutamyl transpeptidase (gamma-GTP) were also decreased in this species. On the contrary, guinea pig liver Se-non-dependent GPx activity was significantly enhanced by PCB 126 treatment, while no effect on Se-dependent activity was observed. Neither the content of GSH nor the enzyme activities responsible for GSH supply in guinea pig liver was affected by PCB 126. These result suggested that the damage on GPx redox system is, at least, one of mechanisms by which co-planar PCB induces the toxicity in rats. However, in guinea pigs, this is not the case, and different mechanism from the damage on active oxygen quenching system is likely to be involved.

Animals↗
PubMed1996

Hamster liver cytochrome P450 (CYP2A8) as a 4-hydroxylase for 2,5,2',5'-tetrachlorobiphenyl.

Metabolism of 2,5,2',5'-tetrachlorobiphenyl (TCB) was studied using liver microsomes of hamsters and two hamster P450 isoforms, CYP1A2 and 2A8. CYP2A8 catalyzed selectively 4-hydroxylation of 2,5,2',5-TCB at a rate of 21.7 pmol/min/nmol P450. In contrast, CYP1A2 showed no activity for hydroxylation of 2,5,2',5'-TCB. Immunological study revealed that rabbit antiserum against CYP2A8 almost completely inhibited the microsomal 4-hydroxylation but that against CYP1A2 did not. It was also shown that the induction pattern of CYP2A8 protein by P450 inducer was similar to that of the 4-hydroxylase activity in hamster liver microsomes. These results suggest that CYP2A8 plays a major role in the 4-hydroxylation of 2,5,2',5'-TCB in hamster liver.

Animals↗
PubMed1996

A coplanar PCB induces a selenium binding protein as a major cytosolic protein in rat liver.

We obtained evidence that a toxic coplanar polychlorinated biphenyl (PCB) induces a counterpart of murine 56kDa selenium binding protein in rat liver cytosol. A 54kDa protein in the liver cytosol was significantly induced by 3,3',4,4',5-pentachlorobiphenyl and proved to be a major cytosolic protein in the rat liver. The protein exhibited pI of 6.8 on two-dimensional gel electrophoresis. The amino acid sequence of peptide fragments from the protein digested in situ, was highly similar to a 56kDa selenium binding protein and similar to an acetaminophen binding protein in mice.

Amino Acid Sequence↗
PubMed1996

Involvement of cytochrome b5 in the metabolism of tetrachlorobiphenyls catalyzed by CYP2B1 and CYP1A1.

The role of cytochrome b5 in the cytochrome P450 (CYP)-dependent hydroxylation of tetrachlorobiphenyl (TCB) isomers was examined using a reconstituted mixed function oxygenase (MFO) system containing purified CYP2B1 or 1A1, and rat liver microsomes. Hydroxylations of 2,2',5,5'- and 3,3',4,4'-TCBs were catalyzed mainly by CYP2B1 and 1A1, respectively, in the reconstituted MFO system and those of 2,3',4',5- and 2,3',4,4'-TCBs were mediated by both cytochrome P450 systems. The activity toward 2,2',5,5'- and 2,3',4',5-TCB was significantly increased 6.5- and 5.5-fold, respectively, by addition of cytochrome b5 in the reconstituted MFO system containing of CYP2B1. Either hydroxylation activity toward 2,3',4,4'-TCB with the CYP2B1 system was very low or decreased by addition of cytochrome b5. These results suggest that the involvement of cytochrome b5 to the hydroxylation of TCBs is dependent on the TCB congener being metabolized, and the cytochrome P450 isoform involved in its metabolism.

Animals↗
PubMed1996

Significant induction of a 54-kDa protein in rat liver with homologous alignment to mouse selenium binding protein by a coplanar polychlorinated biphenyl, 3,4,5,3',4'-pentachlorobiphenyl and 3-methylcholanthrene.

A 54-kDa protein in rat liver cytosol was significantly induced by treatment with 3,4,5,3',4'-pentachlorobiphenyl (25 mg/kg, single i.p.) and 3-methylcholanthrene (20 mg/kg, once a day for 3 days, i.p.). The protein exhibited pI of 6.8 on two-dimensional gel electrophoresis. The amino acid sequences of peptide fragments from the protein digested in situ were highly similar to a selenium binding protein in mice and to the isoform acetaminophen binding protein in mice. The present result clearly demonstrates that a coplanar polychlorinated biphenyl and 3-methylcholanthrene are responsible for induction of selenium binding protein homologues. The physiological role of the mouse proteins, however, is not yet elucidated.

Amino Acid Sequence↗
PubMed1996

Role of cytochrome b5 in the oxidative metabolism of polychlorinated biphenyls catalyzed by cytochrome P450.

1. The role of cytochrome b5 in the cytochrome P450-dependent hydroxylation of tetrachlorobiphenyl (TCB) isomers was examined using a reconstituted system consisting of CYP2B1 and CYP1A1 and rat liver microsomes. 2. By addition of cytochrome b5 to the reconstituted system containing CYP2B1, the 3-hydroxylation of 2,5,2,'5'- and 2,5,3',4'-TCB was increased about six-fold, but the 3- and 5-hydroxylation of 2,4,3',4'-TCB was decreased by about 50% 3. All hydroxylations of 3 ,4,3',4'-,2,5, 3,4'- and 2,4,3',4'-TCBs were decreased by addition of cytochrome b5 to the reconstituted system containing CYPlA1. 4. In stoichiometry measurements, changes in NADPH oxidation and coupling efficiency by addition of cytochrome b5 was observed and these differed according to the position of chlorine atoms of TCBs and cytochrome P450 isoforms used in the systems.

Animals↗
PubMed1995

Structure of genes for sperm-specific nuclear basic protein (SP4) in Xenopus laevis.

Nuclear basic proteins in sperm of Xenopus laevis consist of 6 sperm-specific proteins (SPs1-6) in addition to somatic core histones. Using a cDNA for SP4 as a probe, we cloned genomic DNA containing SP4 genes from a genomic library constructed from recombinant lambda bacteriophage containing 12.0 kbp-EcoRI digests of J-strain X. laevis liver DNA. Construction of restriction maps based on Southern blot analysis revealed the existence of a total of five SP4 genes which are arranged in a tandemly repeated array forming a cluster of simple multigenes per haploid genome, over a range of 18 kbp. Among these genes, the one located at the most upstream position differed from others in possessing a single base substitution which gave rise to a replacement of one out of 78 amino acid residues. The DNA containing the second to the fourth SP4 genes, arranged at about 3 kbp intervals each, was totally sequenced for 10,165 bp. Each gene was found to contain one intron, typical TATA and CCAAT boxes in the 5'-flanking region, and a polyadenylation signal in the 3'-flanking region. Comparative sequence analyses revealed three regions of extensive homology within the upstream non-coding region among three genes, suggesting a possible relevance to their expression at a particular phase of spermatogenesis and/or in testis.

Amino Acid Sequence↗
PubMed1995

Metabolism of highly persistent PCB congener, 2,4,5,2',4',5'-hexachlorobiphenyl, by human CYP2B6.

Metabolism of 2,4,5,2',4',5'-hexachlorobiphenyl was studied with cDNA-expressed human P450 2B isoform, CYP2B6. 3-Hydroxy-2,4,5,2',4',5'-hexachlorobiphenyl was identified as a major metabolite, and the formation activity was compared with that of dog CYP2B11 and guinea pig P450GP-1. The activity of 3-hydroxylation was comparable with that of P450GP-1, but one-tenth of CYP2B11. These results indicate that P450 2B in humans as well as other animal species can metabolize 2,4,5,2',4',5'-hexachlorobiphenyl, and the reason why this PCB congener remained most abundantly in human bodies is discussed.

Animals↗
PubMed1995

[Effect of a coplanar PCB on lipid metabolism: the remarkable difference between rats and guinea pigs].

We studied the effect of 3, 4, 5, 3', 4'-pentachlorobiphenyl (PenCB) on lipid metabolism by determining the level of triacylglycerol and total cholesterol in rats and guinea pigs. Male Wistar rats and male Hartley guinea pigs received PenCB in corn oil one at a dose of 25 mg/kg i.p. and 0.5 mg/kg i.p., respectively. Pair-fed control group of both species were treated with the vehicle and given the amount of chow matched with that taken by the PenCB-treated animals. Free-fed control group was treated with vehicle and was given the chow ad libitum. The plasma was collected on the day 5 after the treatment and the liver was removed. The plasma triacylglycerol level in guinea pigs treated with PenCB was significantly higher than those in free- and pair-fed controls, whereas no significant difference was observed in PenCB-treated rats from both control groups. The plasma cholesterol level was also higher in PenCB-treated guinea pigs than in the two control groups, though the level in rats was significantly lower than the corresponding control values. The hepatic triacylglycerol and cholesterol levels were increased significantly in both species by the PenCB treatment. Although lipid metabolism was disordered in both animals by treatment with PenCB, the responsiveness was remarkably different between guinea pigs and rats. These differences could be associated with species difference in susceptibility toward toxic chlorinated aromatic hydrocarbons.

Animals↗
PubMed1995

[Alteration of peroxisomal enzyme activities in the liver of guinea pigs caused by coplanar PCB].

The hyperlipidemia is a well-known typical symptom in Yusho patients and experimental animals treated with PCBs. We have found a significant induction of CYP4A1, which catalyzes omega-hydroxylation of fatty acids, in guinea pigs by the treatment with a coplanar PCB, 3, 4, 5, 3',4-pentachlorobiphenyl (PenCB), though the P450 is reduced in the treated rats. Peroxisome has beta-oxidation enzymes distinct from mitochondrial enzymes, and also play an important role in lipid metabolism. Peroxisome proliferators have been shown to regulate the expression of CYP4A1 and peroxisomal enzymes by the same mechanism in the rat. In the present study, we examine the effect of PenCB treatment on peroxisomal enzymes in the liver of guinea pigs. As a result, the enzyme activities of hepatic peroxisome, e.g. fatty acid oxidizing system, catalase and urate oxidase, had a rising tendency by the treatment with PenCB in the animal. The results suggest that the regulation of peroxisomal enzymes and CYP4A1 is also associated in guinea pigs, and PenCB provides a similar effect of peroxisomal proliferators to the animal. The possible toxicity through the peroxisomal alteration was discussed.

Animals↗
PubMed1995

[Studies on PCB toxicity involving 2C subfamily cytochrome P450].

It has been demonstrated that PCB metabolism is mainly catalyzed by 1A and 2B subfamily cytochrome P450s, CYP1A1/2 and CYP2B1/2. These studies were conducted mostly with hepatic enzymes in rodents. The 1A and 2B subfamily P450 s are constitutively expressed little, but markedly induced by xenobiotics such as 3-methylcholanthrene and phenobarbital in rodents. On the other hand, the recent studies showed that cytochrome P450s in human liver are remarkably different from isoform of rodents in constitution and enzyme activities. In the present study, we first tried to metabolize some PCBs with 2C subfamily cytochrome P450 (CYP2C) purified from dog liver microsomes. The data suggested that CYP2C may not be involved in PCB metabolism. Since CYP2C is the same most abundant enzyme as 3A subfamily P450 in human liver and plays a major role for metabolism of many drugs used clinically, and may also play an important role for metabolism of some steroid hormones, we further studied the inhibition of CYP2C-catalyzed steroid metabolism by typical PCB congeners. CYP2C-mediated steroid metabolism is greatly inhibited by 2, 4, 5, 2', 4', 5'-hexachlorbiphenyl, but not by 3, 4, 5, 3', 4'-pentachlorobiphenyl. On the contrary, 3, 4, 5, 3', 4'-pentachlorobiphenyl markedly suppressed CYP2C expression in the dog liver. These results suggest that residual PCBs may affect the current situation of steroid hormones in Yusho patients, and may cause PCB drug interactions.

Amino Acid Sequence↗
PubMed1995

[Hand-mirror cells acute lymphoblastic leukemia (L3)].

To our knowledge, this report represents the first confirmed case in Japan of a 15-year-old boy with acute lymphoblastic leukemia (ALL).L3 with hand-mirror cells (HMC) in the bone marrow. HMC lymphoid leukemia is an unusual variant of ALL in which the bone marrow lymphoblasts manifest distinctive hand-mirror morphologic features. HMC lymphoblast is characterized by an asymmetric foot-like cytoplasmic process that extends from the portion of the cell, thus giving it the light-microscopic appearance responsible for its name. Besides ALL, HMC has been reported in acute myeloblastic leukemia (AML), blastic crisis of chronic myelogenous leukemia, non-Hodgkin's lymphoma, and infectious mononucleosis. HMC has been reported to be prevalent in ALL.L1 and L2 as compared with L3.

Adolescent↗
PubMed1994

cDNA cloning and expression of Xenopus sperm-specific basic nuclear protein 5 (SP5) gene.

As part of our continuing program to understand the molecular mechanisms controlling the synthesis of sperm-specific nuclear proteins (SPs1-6) during spermatogenesis in Xenopus, we report here on the isolation of a cDNA clone for SP5, the partial sequencing of the amino acids in the SPs, and the expression of the mRNA for SP5. A cDNA clone (pXSP633) was isolated from a cDNA library, previously prepared from poly (A)+ mRNA obtained from Xenopus round spermatids. Determination of the amino acid sequence of the N-terminal regions of all the SPs(1-6) suggested that pXSP633 encodes SP5, whereas SPs3, 4, and 6 are derived from a second mRNA species, and SPs1 and 2 from a third mRNA species. Thus it seems likely that the six SPs are derived from three different mRNA species. Northern blot analyses of RNA, extracted from primary spermatocytes and round spermatids, was performed with oligonucleotide probes specific for SPs4 and 5 mRNAs. The results showed that whereas both SPs4 and 5 mRNAs are expressed in primary spermatocytes, the amount of SP5 mRNA is only about one-fifth of that of SP4 mRNA. However, both mRNA species undergo a similar size change in the length of their poly (A) tracts during spermatogenesis: the size of the mRNA in cultured round spermatids on day 0 was longer than that in primary spermatocytes, but the size of the mRNA in round spermatids on day 6 was shorter than that in round spermatids on day 0.

Amino Acid Sequence↗
PubMed1994

Purification and characterization of dog liver microsomal epoxide hydrolase.

An epoxide hydrolase (mEH) in liver microsomes was purified to apparent homogeneity from a dog treated with phenobarbital. The purified enzyme had a minimum molecular weight of 47,000 as determined by SDS-PAGE. The dog mEH activity was characterized by use of a substrate, 7-glycidoxycoumarin (GOC), and some effectors of this enzyme. In vitro activators, metyrapone, and isoquinoline, stimulated the microsomal activity, but the former had no such effect on the purified enzyme in case of this substrate. All mEH inhibitors, 1,1,1-trichloropropene 2,3-oxide (TCPO), cyclohexene oxide, and 2-bromo-4'-nitroacetophenone (BrNAP), suppressed hydrolase activity. The NH2-terminal amino acid sequence of the purified enzyme was highly homologous (90%) to the sequences deduced from a cDNA clone of rat enzyme. Antiserum to the purified enzyme raised in rabbits cross-reacted with rat and guinea pig epoxide hydrolases. No gender-difference in this enzyme in liver microsomes was observed in dogs.

Amino Acid Sequence↗
PubMed1994

Assessment of testicular biopsy after cessation of maintenance chemotherapy in childhood acute lymphoblastic leukemia: a report from the Children's Cancer and Leukemia Study Group.

Among 484 male patients with acute lymphoblastic leukemia (ALL) registered into the protocols CCLSG 811, 841 and 874, from 1981 through 1990, 246 patients completed their protocols and were in continuous complete remission (CCR) for more than 3 years. One hundred and seven patients received bilateral testicular biopsies at the time of cessation of maintenance chemotherapy. Eight patients (7.5%) were found to have occult testicular leukemia (TL). Three of them did not receive any additional therapy and all suffered subsequent relapses; one bone marrow relapse and two testicular relapses. The other 3 patients received testicular radiation combined with an additional 2 years of chemotherapy, resulting in CCR for more than 6 years 10 months, 7 years 6 months, and 8 years 6 months. One with chemotherapy alone and another with radiation alone showed subsequent relapse. Overt TL after negative initial biopsy was developed in 3 (3.0%) of the 99 patients. All of them received testicular radiation with chemotherapy, resulting again in CCR for more than 1 year 0 months and 5 years 3 months; one patient showed relapse in testes and bone marrow after 3 years 8 months of CCR. These studies suggested that occult TL has an adverse prognostic significance unless retrieval chemotherapy is given and that performance of testicular biopsy at completion of maintenance chemotherapy is not contributory to prolongation of disease-free survival for males with ALL because the treatment employing testicular radiation plus retrieval chemotherapy for both occult TL and isolated overt TL after off-therapy is similarly very effective.

Antineoplastic Combined Chemotherapy Protocols↗