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M Kiuchi

Publications and source records attributed to M Kiuchi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prediction of drug-drug interactions of zonisamide metabolism in humans from in vitro data.

OBJECTIVE: The purposes of this study were to identify the P450 enzyme (CYP) responsible for zonisamide metabolism in humans by using expressed human CYPs and to predict drug interaction of zonisamide in vivo from in vitro data. METHODS: Ten expressed human CYPs and human liver microsomes were used in the experiments for the identification of enzymes responsible for zonisamide metabolism and for the prediction of drug-drug interactions of zonisamide metabolism in humans from in vitro data, respectively. Two-sulfamoylacetyl phenol, a reductive metabolite of zonisamide, was measured by the HPLC method. RESULTS: From the experiments using ten expressed human CYPs, CYP2C19, CYP3A4 and CYP3A5 were shown to be capable of catalyzing zonisamide reduction. However, an intrinsic clearance, Vmax/kM, of CYP3A4 was much higher than those of CYP2C19 and CYP3A5. From the point of view of enzyme amount in human liver CYPs isoform and their intrinsic clearance, it was suggested that CYP3A4 is mainly responsible for zonisamide metabolism in human CYPs. Zonisamide metabolism in human liver microsomes was markedly inhibited by cyclosporin A, dihydroergotamine, ketoconazole, itraconazole, miconazole and triazolam. We estimated the possibility and degree of change of zonisamide clearance in vivo in clinical dose range from in vitro inhibition constant of other drugs against zonisamide metabolism (Ki) and unbound inhibitor concentration in blood (Iu) in clinical usage. Clearance of zonisamide was maximally estimated to decrease by 31%, 23% and 17% of the clearance without inhibitors i.e. ketoconazole, cyclospolin A and miconazole, respectively. Fluconazole and carbamazepine are estimated to decrease by 5-6% of the clearance of zonisamide. On the other hand, there may be lack of interaction of zonisamide metabolism by dihydroergotamine, itraconazole and triazolam in clinical dose range. CONCLUSION: We demonstrated that: (1) zonisamide is metabolized by recombinant CYP3A4, CYP2C19 and CYP3A5, (2) the metabolism is inhibited to a variable extent by known CYP3A4/5 substrates and/or inhibitors in human liver microsomes, and (3) in vitro-in vivo predictive calculations suggest that several compounds demonstrating CYP3A4-affinity might cause in vivo drug-drug interactions with zonisamide.

Anticonvulsants↗
PubMed1997

Tissue-specific and stage-specific expression of two silkworm ecdysone receptor isoforms -- ecdysteroid-dependent transcription in cultured anterior silk glands.

Previously, we isolated a cDNA clone for the ecdysone receptor B1 isoform of the silkworm, Bombyx mori (BmEcR-B1). Here we report the cloning of a cDNA that encodes the Bombyx ecdysone receptor A isoform (BmEcR-A) and mRNA expression of the two BmEcR isoforms during molting and metamorphosis. At larval-pupal transformation, mRNA expression of BmEcR-B1 was predominant in most tissues examined, including three larval tissues (midgut, epidermis, and fat body) and the wing imaginal disc. The anterior silk gland was the only tissue where BmEcR-A was predominant. These expression patterns were different from observations demonstrated in Drosophila. In the anterior silk gland, both EcR isoforms were expressed synchronously during the fifth larval instar, while expression of the A isoform preceded that of the B1 isoform by two days in the fourth instar. Precedence of BmEcR-A during the fourth instar and synchronization of both isoforms during the fifth instar were also observed in the middle and posterior silk glands, suggesting that transcription of BmEcR in the silk gland is regulated differently in these two instars. In the cultured anterior silk glands of day 0 of the fifth instar, transcription of BmEcR-A and BmEcR-B1 was induced dose dependently by more than 5 ng/ml 20-hydroxyecdysone. BmEcR-A and BmEcR-B1 mRNAs were induced within 2 h and 1 h, respectively, of the addition of 20-hydroxyecdysone. These results suggest that the increase of BmEcR mRNAs during the fifth instar is induced in vivo by a small increase in ecdysteroids.

Amino Acid Sequence↗
PubMed1997

Substitutions of alanine for cysteine at a reactive thiol site and for lysine at a pyridoxal phosphate binding site of 1-aminocyclopropane-1-carboxylate deaminase.

1-Aminocyclopropane-1-carboxylate (ACC) deaminase catalyzes the cyclopropane ring fragmentation and deamination of ACC. Replacement of cysteine with alanine at a reactive thiol site, Cys-162, of ACC deaminase did not affect the enzyme activity, in spite of the previous result that modification of Cys-162 caused complete loss of the enzyme activity. Substitution of glycine or valine for the cysteine residue gave a higher Km for ACC without a significant change of the K0, indicating that changes of the amino acid side chain had structural effects on substrate binding. Replacement of lysine with alanine at the pyridoxal phosphate (PLP) binding site of the ACC deaminase caused a lower content of PLP and loss of detectable activity of ACC deamination. This mutant enzyme, K51A, showed absorption peaks at 330 nm and 405 nm. The peak at 405 nm was shifted to about 425 nm by the addition of ACC, D-, L-alanine, and D-, L-serine. The formation of aldimine complexes indicated by the spectral shift was reversible. It is suggested that lysine 51 affects the formation of holoenzyme and is important in catalysis.

Absorption↗
PubMed1997

Combined polymorphism associated with a 3-bp deletion in the 5'-flanking region of a tetrameric short tandem repeat at the CYP19 locus.

Allele frequencies for a tetrameric short tandem repeat locus, CYP19, were determined in 220 unrelated Japanese individuals. The frequency distribution was similar to that of a previous report. However, PCR amplification using two sets of primers suggested that one allele consisting of 7 TTTA repeats (the allele 7) was divided into two separate ones, 7P (standard) and 7(-3), which differed in length for 3 bp. Sequence analysis of the two alleles revealed that the smaller 7(-3) had a 3-bp deletion in the 5'-flanking region of the tetrameric repeat. The deletion was also observed as the allele 7(-3) in non-Japanese such as Caucasians and Africans; it was only found in a part of the allele 7 [7(-3)], but not in the other alleles, in all examined populations. In the Japanese population, the deletion was observed in 39.6% of the allele 7, or 24.8% of all of the alleles. When the STR polymorphism at the CYP19 locus was combined with the polymorphic deletion adjacent to the repeat region, the numerical indices of genetic polymorphisms (heterozygosity, polymorphism information content and the power of discrimination) in Japanese rose from 0.541, 0.46 and 0.723 to 0.723, 0.66 and 0.864, respectively. Accordingly, the combined polymorphism at the CYP19 locus can be considered appropriate for hereditary analysis in the field of forensic science.

Alleles↗
PubMed1996

Potent immunosuppressants, 2-alkyl-2-aminopropane-1,3-diols.

Several immunosuppressants, ISP-I [(2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-(hydroxymethyl)-14-oxoeicos++ +-6-enoic acid, myriocin = thermozymocidin] and mycestericins A-G, were isolated from culture broths of Isaria sinclairii and Mycelia sterilia, respectively. In order to investigate structure-activity relationships, extensive modifications of ISP-I were conducted, and it was established that the fundamental structure possessing the immunosuppressive activity is a symmetrical 2-alkyl-2-aminopropane-1,3-diol. The tetradecyl, pentadecyl, and hexadecyl derivatives prolonged rat skin allograft survival in the combination of LEW donor and F344 recipient and were more effective than cyclosporin A. Among them, 2-amino-2-tetradecylpropane-1,3-diol hydrochloride, ISP-I-55, showed the lowest toxicity. ISP-I-55 is a promising lead compound for the development of effective immunosuppressants for organ transplantations and for the treatment of autoimmune diseases.

Acyltransferases↗
PubMed1996

Determination of absolute configuration and biological activity of new immunosuppressants, mycestericins D, E, F and G.

Mycestericins D, E, F and G were isolated from the culture broth of Mycelia sterilia ATCC 20349 as potent immunosuppressants. Mycestericins F and G were identical with dihydromycestericins D and E, respectively. Their absolute configurations were determined by use of the modified MOSHER'S method and by comparison of the CD spectra of their benzoate derivatives with those of synthetic analogs. Mycestericins D, E, F and G suppressed the proliferation of lymphocytes in the mouse allogeneic mixed lymphocyte reaction.

Animals↗
PubMed1996

Sequence variation found in the flanking region of a trimeric short tandem repeat at the PLA2 locus: its considerable effect on estimating alleles.

Amplified alleles at the PLA2 short tandem repeat locus were sequenced and analyzed using different combinations of the PCR primer. When changing one side of the primers from the previous design to our original one, additional alleles, which had been previously hidden, could be newly detected in two out of 60 DNA samples of unrelated Japanese individuals. The sequence data revealed both 'hidden alleles' to be accompanied by a 3-bp deletion in the 5'-flanking region of the trimeric short tandem repeat. The position of the deletion corresponded to the exact 3' end of the primer, which had been formerly used. In the present case, both of the base numbers, which constituted the core repeat unit and which were deleted in the 'hidden alleles', were equal. Therefore, it was impossible to distinguish an allele from that with not only an additional trimeric repeat but a 3-bp deletion without the sequence analysis. This result indicates that the estimated allele size does not always reflect the difference in the repeat number even if the alleles regularly differ in size by one repeat unit. Moreover, this study suggests the presence of apparent homozygotes, of which the fellow of the heterozygous alleles is hidden by an unsuccessful amplification due to the sequence variation.

Alleles↗
PubMed1994

Immunochemical evidence for the occurrence of Mu class glutathione S-transferase in human fetal livers.

Immunoblot analysis showed that alpha-class glutathione S-transferase (GST), which is one of the major forms in adult human liver, was expressed in human fetal liver. Mu-class GST was also expressed in fetal liver. The majority of mu-class GST expressed in adult liver consisted of a subunit with a molecular weight of 27 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), whereas two subunits of 27 and 26 kDa were detected in fetal liver as proteins immunochemically related to mu-class GST. On reverse-phase HPLC, these two subunits cross-reactive with antibodies to rat GST 3-3 in fetal liver were indistinguishable from each other in their retention time; though, they could be separated by chromatofocusing analysis. The molecular weights of GSTs immunochemically related to rat GST 3-3, eluted at pH 7.1, 6.4, and 5.7, were 27, 27 and 26, and 26 kDa, respectively. In addition, the N-terminal amino acid sequence of these subunits suggested that GSTs related to rat GST 3-3 expressed in fetal liver may be homodimeric and heterodimeric proteins. As expected, pi-class GST was found to be a major form of GST in fetal liver but not in adult liver. In contrast, the GST immunochemically related to rat GST Yrs-Yrs, which is classified as theta-class GST, was detected in adult liver but not in fetal liver. These results indicate that several isoenzymes of GST are expressed in human fetal liver, but they are not the same as those in adult liver.

Amino Acid Sequence↗
PubMed1994

Fungal metabolites. Part 14. Novel potent immunosuppressants, mycestericins, produced by Mycelia sterilia.

Mycestericins A, B, C, D and E were isolated from the culture broth of Mycelia sterilia ATCC 20349 along with thermozymocidin (= myriocin). Their structures were elucidated on the basis of spectroscopic studies and chemical evidence. The acetate of mycestericin C was identical with the acetate of 6,7-dihydromyriocin. Mycestericins suppressed the proliferation of lymphocytes in the mouse allogeneic mixed lymphocyte reaction, with a potency similar to that of myriocin.

Animals↗
PubMed1993

Purification and characterization of two forms of hepatic microsomal cytochrome P450 from untreated cynomolgus monkeys.

Two forms of cytochrome P450, referred to as P450 CMLb and P450 CMLc, were purified and characterized from hepatic microsomes of untreated cynomolgus monkeys (Macaca irus). The final preparations were apparently homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The minimum molecular weights of P450 CMLb and P450 CMLc estimated from the mobilities on the gel were 48 and 50 kDa, respectively. The N-terminal amino acid sequences of P450 CMLb and P450 CMLc (first 13 residues) were identical, respectively, with those of P450 FI isolated from baboons and P450 MK-2, which has been characterized as a P450 3A enzyme in cynomolgus monkeys. P450 CMLb showed coumarin 7-hydroxylation and 7-ethoxycoumarin O-deethylation activities. This P450 enzyme reacted with anti-P450 2A6 antibody and acts as a coumarin 7-hydroxylase in hepatic microsomes. On the basis of these results P450 CMLb was classified into the 2A subfamily. P450 CMLb is expressed constitutively as one of the minor forms of P450 in liver microsomes of untreated cynomolgus monkeys and is inducible by phenobarbital. P450 CMLc reacted with anti-P450 3A4 antibody and hydroxylated testosterone at the 6 beta-position. The testosterone 6 beta-hydroxylation activities in hepatic microsomes of cynomolgus monkeys, common squirrel monkeys, and humans were strongly inhibited by the anti-P450 CMLc antibody. These results demonstrate that this P450 enzyme is in the P450 3A subfamily.

Amino Acid Sequence↗
PubMed1993

Studies on cytochrome P450 responsible for oxidative metabolism of imipramine in human liver microsomes.

The activity of imipramine 2-hydroxylase highly correlated with that of desipramine 2-hydroxylase but not with that of desipramine N-demethylase. The correlation was also found between N-demethylation and 2-hydroxylation when imipramine was used as a substrate, whereas no correlation was observed between them when desipramine was used in place of imipramine. Both activities of desipramine and imipramine 2-hydroxylase were markedly inhibited by quinidine but not by quinine. Although the activity of imipramine N-demethylase was slightly inhibited by both quinidine and quinine, the activity of desipramine N-demethylase was unaffected under the same conditions. The activity of imipramine N-demethylase was roughly correlated with the amounts of P450 3A4 immunochemically determined and the activities of testosterone 6 beta-hydroxylase in human liver microsomes. The P450 3A4 catalyzed imipramine N-demethylation much more efficiently than 2-hydroxylation in a reconstituted system, whereas neither N-demethylation nor 2-hydroxylation of desipramine was catalyzed by P450 3A4. The activity of imipramine N-demethylase was inhibited, to various extents, by anti-P450 3A4 antibodies in human liver microsomes. Taking together these and other results, it is suggested that P450 3A4, other than P450 2Cmp, also partly contributes to N-demethylation of imipramine, depending on human liver microsomes.

Cytochrome P-450 Enzyme Inhibitors↗
PubMed1993

A murine model of experimental autoimmune lens-induced uveitis using Klebsiella O3 lipopolysaccharide as a potent immunological adjuvant.

Experimental autoimmune uveitis and finally panophthalmitis could be produced in mice by repeated immunization of syngeneic eyeball extract mixed with Klebsiella O3 lipopolysaccharide (KO3 LPS) as a powerful immunological adjuvant. No ocular lesions were produced in mice given eyeball extract emulsified in complete Freund's adjuvant (CFA), KO3 LPS alone or eyeball extract alone. Histopathological changes in the ocular lesions at the early stage after the second or tertiary immunization were characterized by infiltration with inflammatory cells in the ciliary body and iris. The iridocyclitis was followed by extensive infiltration of polymorphonuclear leucocytes (PMN) into the cornea, lens and the surrounding tissues after repeated immunization. Finally, these areas were replaced by granulomatous tissues infiltrated with mononuclear cells. On the other hand, the structure of the retina and sclera was partially preserved. Those mice exhibited production of autoantibodies and development of the delayed-type hypersensitivity (DTH) to syngeneic eyeball extract. Moreover, ocular lesions could be produced in normal recipient mice by transfer of sensitized lymphocytes from hyperimmunized mice. Therefore, it was suggested that the ocular lesions produced by repeated immunization with the mixture of eyeball extract and KO3 LPS were due to the autoimmune mechanism. This might be useful to model immunological phenomena in the pathogenesis of human phacoantigenic uveitis.

Adjuvants, Immunologic↗
PubMed1993

Characterization of human liver microsomal cytochrome P450 involved in the reductive metabolism of zonisamide.

Zonisamide (1,2-benzisoxazole-3-methanesulfonamide) was metabolized to 2-sulfamoylacetylphenol (SMAP) in human liver microsomes under anaerobic conditions. The formation of SMAP was remarkably inhibited by cimetidine, n-octylamine, ketoconazole, and carbon monoxide, indicating that a cytochrome P450 is involved in the metabolism of zonisamide to SMAP in human liver microsomes. The SMAP-producing activity did not correlate with the spectrally determined amount of cytochrome P450. In contrast, the SMAP-producing activity from zonisamide correlated closely with the activity of testosterone 6 beta-hydroxylase (r2 = 0.96) and correlated slightly but significantly with the activity of imipramine 2-hydroxylase (r2 = 0.28), but not with those of aniline hydroxylase (r2 = 0.09) or benzphetamine N-demethylase (r2 = 0.20). In addition, immunoquantitation of cytochrome P450 enzymes in 21 human liver microsomal samples revealed that SMAP formation correlated closely with the amount of P450 3A enzyme and correlated moderately well with that of P450 2D6 but not with that of P450 2C enzyme in human liver microsomes. P450 3A4 exhibited SMAP-producing activity in a reconstituted monooxygenase system. The metabolism of zonisamide to SMAP was almost completely inhibited by anti-P450 3A4 antibody but not by anti-P450 2C9 or anti-P450 2D6 antibodies, suggesting that the amount of P450 3A enzyme may be a major factor influencing the level of metabolism of zonisamide to SMAP in human liver microsomes.

Anticonvulsants↗
PubMed1992

Unusual intravascular hemolysis in a case of fatal hypothermia.

A 55-year-old man was discovered dead inside a deep freezer maintained at -40 degrees C. After consuming a large quantity of alcohol, the man had become trapped in the freezer approximately 11 h before his body was found. The body was still frozen at the time of autopsy, but subcutaneous dendriform vessel repletion phenomenon was observed on the upper and lower extremities. Although this intravascular hemolysis resembled that which develops during putrefaction, in this case it was thought to be due to pooling and freezing of blood in subcutaneous vessels. Contributory factors included alcohol ingestion, vasodilation following vasoconstriction, vasomotor paralysis, and red cell sludging. Hemolysis followed freezing of the blood. When such phenomena are observed in a corpse, exposure to extreme cold should be suspected.

Hemolysis↗
PubMed1991

Quality of life: a possible health index for the elderly.

To assess whether quality of life (QOL) could be employed as an outcome measure of health programs for elderly populations, we evaluated the relationship between subjective assessment of QOL ("morale scale") and objective constituents of active life such as activities of daily living (ADL), instrumental ADL (IADL) and work status along with determination of active life expectancy (ALE) in a rural district in Japan (n = 13,529). The QOL scale was positively correlated with ADL, IADL and work status but not with age. Validity and test-retest reliability were satisfactory as regards the small subsamples of respondents. ALE of the elderly aged 60 to 64 was 15.2 years, while their life expectancy was 27.1 years. Factors associated with lower ADL included age, lower IADL and joblessness. The QOL measurement and the objective variables can be incorporated into an assessment of the health status of the elderly in addition to conventional indices based on mortality.

Activities of Daily Living↗
PubMed1990

[Basic studies on abdominal injuries. Part 1: Degree of depression of abdominal wall by compression].

The degree of depression of the abdominal surface by compression was measured in 121 healthy adult male having an average age of 20.4 years. Three disks of different sizes (10, 25, and 45 mm in diameter) were attached to the edge of the baresthesiometer, and pressures of 1, 3 and 5 kg were applied to the 10 mm disk, and 1, 3, 5, and 7 kg to the other disks. The regions tested were the medial abdomen approximately 2 cm above the umbilicus and the left and right flanks at the level of umbilicus. The higher the pressure administered, the greater the depression formed on each disk. Severe pain occurred in the nonanesthetized person, and it was difficult to increase the pressure to a higher level than 7 kg. At each pressure, the smallest disk produced larger depression than did the other two. The degree of depression was related to the total pressure administered rather than to the amount of pressure per unit area. The distribution of measured value was shown to be normal. After the largest depression for each region had been determined, a pressure of 7 kg was imposed on the 25-mm disk. On the medial abdomen, the anatomical position generated a mean depression of 6.3 cm, and the spine position a depression of 5.04 cm. On the flank, mean value of the depression was approximately 5.7 cm, and did not differ between the anatomical and supine positions and between the right and left flanks.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1988

Sudden infant death due to asplenia syndrome.

An apparently healthy 80-day-old boy died suddenly for no apparent reason. The autopsy revealed that the patient had had congenital asplenia, extensive cardiovascular anomalies, and other organ malformations, including trisegmented lungs, hypoplasia of the corpus callosum and cranial bones, a symmetrical liver, accessory hepatic tissue in the adrenal glands, malrotation of the intestine, and hypoplasia of the greater omentum.

Abnormalities, Multiple↗