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The rate of implant removal and the factors influencing its indication in patients with distal radius fracture (DRF) in Japan are unclear. We retrospectively evaluated the incidence rate of implant removal in a large cohort of DRF patients obtained from the Diagnosis Procedure Combination database in Japan between April 2014 and March 2019. Patient- and hospital-related factors possibly affecting removal rate, including age, sex, annual number of open reduction and internal fixation (ORIF) for DRF procedures per hospital, number of hospital beds, advanced or general care hospital, and hospital location were analyzed as well. Hospital location was classified into three types based on population and population density as 1) large city, 2) local city, and 3) sparse area. Implant removal was performed in 3242 (26.3%) of 12,328 DRF patients receiving ORIF. According to multivariate analysis, the significant factors related to a decreased probability of removal were older patients, male, large annual number of ORIF for DRF procedures per hospital, large number of hospital beds, advanced care hospital, and hospital in large city. This study clarified the current implant removal rate and trends following ORIF for DRF in Japan. Both patient- and hospital-related factors significantly impacted the decision for implant removal. [ABSTRACT FROM AUTHOR]

Mutations in the OTOF gene are a common cause of hereditary hearing loss and the main cause of auditory neuropathy spectrum disorder (ANSD). Although it is reported that most of the patients with OTOF mutations have stable, congenital or prelingual onset severe-to-profound hearing loss, some patients show atypical clinical phenotypes, and the genotype–phenotype correlation in patients with OTOF mutations is not yet fully understood. In this study, we aimed to reveal detailed clinical characteristics of OTOF-related hearing loss patients and the genotype–phenotype correlation. Detailed clinical information was available for 64 patients in our database who were diagnosed with OTOF-related hearing loss. As reported previously, most of the patients (90.6%) showed a "typical" phenotype; prelingual and severe-to-profound hearing loss. Forty-seven patients (73.4%) underwent cochlear implantation surgery and showed successful outcomes; approximately 85–90% of the patients showed a hearing level of 20–39 dB with cochlear implant and a Categories of Auditory Performance (CAP) scale level 6 or better. Although truncating mutations and p.Arg1939Gln were clearly related to severe phenotype, almost half of the patients with one or more non-truncating mutations showed mild-to-moderate hearing loss. Notably, patients with p.His513Arg, p.Ile1573Thr and p.Glu1910Lys showed "true" auditory neuropathy-like clinical characteristics. In this study, we have clarified genotype–phenotype correlation and efficacy of cochlear implantation for OTOF-related hearing loss patients in the biggest cohort studied to date. We believe that the clinical characteristics and genotype–phenotype correlation found in this study will support preoperative counseling and appropriate intervention for OTOF-related hearing loss patients. [ABSTRACT FROM AUTHOR]

Recently, a new rapid assay for the detection of tcdB gene of Clostridioides difficile was developed using the GENECUBE. The assay can directly detect the tcdB gene from stool samples without a purification in approximately 35 minutes with a few minutes of preparation process. We performed a prospective comparative study of the performance of the assay at eight institutions in Japan. Fresh residual stool samples (Bristol stool scale ≥5) were used and comparisons were performed with the BD MAX Cdiff assay and toxigenic cultures. For the evaluation of 383 stool samples compared with the BD MAX Cdiff assay, the sensitivity, and specificity of the two assays was 99.0% (379/383), 98.1% (52/53), 99.1% (327/330), respectively. In the comparison with toxigenic culture, the total, sensitivity, and specificity were 96.6% (370/383), 85.0% (51/60), and 98.8% (319/323), respectively. The current investigation indicated the GENECUBE Clostridioides difficile assay has equivalent performance with the BD MAX Cdiff assay for the detection of tcdB gene of C. difficile. [ABSTRACT FROM AUTHOR]

Conclusion: Rapidly progressive bilateral sensorineural hearing loss (SNHL) often develops as a symptom of intracranial diseases or systemic vasculitis. For early diagnosis and treatment of these potentially fatal diseases, a history of hearing deterioration within 2 months and associated symptoms may be important. Objectives: To reveal clinical features and causative diseases for rapidly progressive bilateral SNHL. Methods: The inclusion criterion was patients with bilateral progressive SNHL, who had experienced difficulty in daily conversation within 4 days to 1 year after the onset of hearing loss awareness. This study was a retrospective evaluation of 12 patients with rapidly progressive bilateral SNHL who visited our hospital between 2007 and 2011. Results: The causative disease for hearing loss was identified in 11 of 12 patients; intracranial lesions including nonbacterial meningitis, meningeal metastasis of lymphoma, and superficial siderosis in 4 patients, systemic vasculitis in 2, auditory neuropathy spectrum disorder in 1, and an isolated inner ear disorder in 4. Relatively rapid hearing deterioration within 2 months showed a significant association in six patients with an intracranial lesion or systemic vasculitis. Moreover, all these six patients complained of dizziness and/or non-cochleovestibular symptoms such as fever, headache, and/or altered mental state in addition to hearing loss. [ABSTRACT FROM AUTHOR]

Conclusion: Cochlear implantation was effective for deaf children with congenital cytomegalovirus (CMV) infection, but their cochlear implant (CI) outcomes were often impaired, depending on the types of CMV-associated psycho-neurological disorders. Evaluation of cognitive development and autistic tendency of implantees might be useful to predict their CI outcomes. Objectives: To reveal the influence of CMV-associated psycho-neurological disorders on CI outcomes. Methods: This was a retrospective evaluation of 11 implantees with congenital CMV infection (CMV-CIs) and 14 implantees with autosomal recessive hearing loss (genetic-CIs). Results: Nine of 11 CMV-CIs suffered from psycho-neurological disorders; one from attention deficit hyperactivity disorder, two from pervasive developmental disorder, and six from mental retardation. Aided hearing thresholds with CIs in the two groups did not differ, but two autistic and two mentally retarded CMV-CIs showed significantly low scores in speech discrimination tests. Language-Social (L-S) developmental quotients (DQs) evaluated by the Kyoto Scale of Psychological development were improved after the implantation in both groups, but the postoperative increase of L-S DQs was significantly smaller in the CMV-CIs than that of genetic-CIs. Interestingly, the postoperative L-S and Cognitive-Adaptive (C-A) DQs showed statistically significant correlation in all cases except for two autistic CMV-CIs whose L-S DQs were much lower than those expected from their C-A DQs. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to describe kinetically and kinematically the control patterns of wheelchair wheelies, to clarify the relation between motion of the wheelchair and floor reaction force, to reveal movement strategies of the task, and to find useful parameters to understand the control and learning process of the skill. 10 healthy female Japanese students who were able to perform a 2-min. stationary wheelie participated in the experiments. Analysis of the 20-sec. wheelie performances suggested that (1) Center of Pressure is not a fundamental parameter for wheelie balance control, but may be the result of the control, (2) the anteroposterior component of the floor reaction force is a fundamental parameter for analyzing the control of a wheelchair wheelie, and (3) angular velocity is used in the control of wheelie balance as a cue. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • A novel CYP2C19 gene variant, CYP2C19* 17, is associated with increased metabolic activity. • Ethnic differences in the frequency of the variant allele have been reported. However, the frequency of the CYP2C19* 17 allele has not been studied in the Japanese population. WHAT THIS STUDY ADDS • In a population of 265 healthy Japanese subjects, a low frequency (1.3%) of the CYP2C19* 17 allele was observed. • The limited frequency of the * 17 allele and the absence of a subject homozygous for * 17 indicated that CYP2C19* 17 would play a minor role in a Japanese population. AIMS We investigated the CYP2C19* 17 allelic frequency in Japanese subjects, and evaluated whether CYP2C19* 17 is an important determinant of interindividual variability of CYP2C19 activity. METHODS We enrolled 265 subjects to determine their CYP2C19 genotype and plasma metabolic ratio following a single dose of 40 mg omeprazole. RESULTS Seven subjects heterozygous for CYP2C19* 17 and no * 17/* 17 subjects resulted in the CYP2C19* 17 frequency being 1.3%. These heterozygotes had moderate metabolic activities when compared with the metabolic ratio of the other subjects. CONCLUSIONS The low frequency of CYP2C19* 17 and the absence of * 17/* 17 indicates that CYP2C19* 17 plays a minor role in the Japanese population. [ABSTRACT FROM AUTHOR]

Genetic variants of human flavin-containing monooxygenase 3 (FMO3) were investigated using an updated Japanese population panel containing 54,000 subjects (the previous panel contained 38,000 subjects). One stop codon mutation and six amino acid-substituted FMO3 variants were newly identified in the updated databank. Of these, two substituted variants (p.Thr329Ala and p.Arg492Trp) were previously identified in compound haplotypes with p.[(Glu158Lys; Glu308Gly)] and were associated with the metabolic disorder trimethylaminuria. Three recombinant FMO3 protein variants (p.Ser137Leu, p.Ala334Val, and p.Ile426Val) expressed in bacterial membranes had similar activities toward trimethylamine N-oxygenation (∼75-125 %) as wild-type FMO3 (117 min -1 ); however, the recombinant novel FMO3 variant Phe313Ile showed moderately decreased FMO3 catalytic activity (∼20 % of wild-type). Because of the known deleterious effects of FMO3 C-terminal stop codons, the novel truncated FMO3 Gly184Ter variant was suspected to be inactive. To easily identify the four impaired FMO3 variants (one stop codon mutation and three amino-acid substitutions) in the clinical setting, simple confirmation methods for these FMO3 variants are proposed using polymerase chain reaction/restriction fragment length polymorphism or allele-specific PCR methods. The updated whole-genome sequence data and kinetic analyses revealed that four of the seven single-nucleotide nonsense or missense FMO3 variants had moderately or severely impaired activity toward trimethylamine N-oxygenation., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (© 2023 Published by Elsevier Ltd on behalf of The Japanese Society for the Study of Xenobiotics.)

Fluvastatin is a 3-hydroxy-3-methylglutaryl CoA reductase inhibitor that competitively inhibits human cytochrome P450 (P450) 2C9 in vitro. Drug interactions between a variety of P450 2C9 substrates/inhibitors and fluvastatin can increase the incidence of fluvastatin-related hepatic or skeletal muscle toxicity in vivo. In this survey, the prescribed dosage of fluvastatin was reduced or discontinued in 133 of 164 patients receiving fluvastatin alone, as recorded in the Japanese Adverse Drug Event Report database of spontaneously reported events. The median days to onset of fluvastatin-related disorders were in the range 30-35 d in the 87 patients. Therefore, we aimed to focus on fluvastatin and, using the pharmacokinetic modeling technique, estimated the virtual plasma and hepatic exposures in subjects harboring the impaired CYP2C9*3 allele. The plasma concentrations of fluvastatin modeled after a virtual oral 20-mg dose increased in homozygotes with CYP2C9*3; the area under the plasma concentration curve was 4.9-fold higher than that in Japanese homozygotes for wild-type CYP2C9*1. The modeled hepatic concentrations of fluvastatin in patients with CYP2C9*3/*3 after virtual daily 20-mg doses for 7 d were 31-fold higher than those in subjects with CYP2C9*1/*1. However, heterozygous Chinese patients with CYP2C9*1/*3 reportedly have a limited elevation (1.2-fold) in plasma maximum concentrations. Virtual hepatic/plasma exposures in subjects harboring the impaired CYP2C9*3 allele estimated using pharmacokinetic modeling indicate that such exposure could be a causal factor for hepatic disorders induced by fluvastatin prescribed alone in a manner similar to that for interactions with a variety of co-administered drugs.

Omeprazole, a gastric acid pump inhibitor, is repeatedly administered and is oxidatively metabolized mainly by polymorphic cytochrome P450 2C19. The prescribed dosage of omeprazole was discontinued or reduced in 47 of the 135 patients who received omeprazole alone in this survey, as recorded in the Japanese Adverse Drug Event Report database. The days to onset of omeprazole-related disorders were 3-4 d (median) and 16 d for intravenous 20-40 mg and oral 20 mg daily doses, respectively, in 34 patients for whom relevant data were available. The maximum plasma concentration of omeprazole was pharmacokinetically modeled after a single oral 40-mg dose in P450 2C19-defective poor metabolizers and was 2.4-fold higher than that in extensive metabolizers. The modeled area under the hepatic concentration curves of omeprazole in P450 2C19 poor metabolizers after virtual daily 40-mg doses for 7 d was 5.2-fold higher than that in the extensive metabolizers. Omeprazole-induced P450 2C19 (approx. 2-fold), resulting in increased hepatic intrinsic clearance in repeated doses, was considered after the second day. Virtual plasma/hepatic exposure estimated using pharmacokinetic modeling in subjects with P450 2C19 poor metabolizers indicated that these exposure levels virtually estimated could be one of causal factors for unexpected hepatic disorders induced by prescribed omeprazole, such as those resulting from drug interactions with repeatedly co-administered medicines.

The impacts of polymorphic cytochrome P450 (P450 or CYP) 2C9 on drug interactions and the pharmacokinetics of cyclooxygenase inhibitors have attracted considerable attention. In this survey, the prescribed dosage was reduced or discontinued in 150 and 56 patients, respectively, receiving celecoxib and diclofenac prescribed alone, as recorded in a Japanese database of adverse drug events. Among the factors underlying adverse events, intrinsic drug clearance rates may be a contributing factor. The pharmacokinetically modeled plasma concentrations of celecoxib after an oral 200-mg dose increased in CYP2C9*3 homozygotes: the area under the plasma concentration curve was 4.7-fold higher than that in CYP2C9*1 homozygotes. In patients with CYP2C9*3/*3, the virtual hepatic concentrations of diclofenac after three daily 25-mg doses for a week were 11-fold higher than the plasma concentrations in subjects with CYP2C9*1/*1. The in vivo and in vitro fractions of the victim drug metabolized by a specific polymorphic P450 form is an important determining factor for estimating drug-drug interactions. Virtual hepatic and plasma exposures estimated by pharmacokinetic modeling in patients harboring the impaired CYP2C9*3 allele could represent a causal factor for adverse events induced by celecoxib or diclofenac in a manner similar to that for drug interactions.

The number of single-nucleotide substitutions of human flavin-containing monooxygenase 3 (FMO3) recorded in mega-databases is increasing. Moreover, phenotype-gene analyses have revealed impaired FMO3 variants associated with the metabolic disorder trimethylaminuria. In this study, four novel amino-acid substituted FMO3 variants, namely p.(Gly191Asp), p.(Glu414Gln), p.(Phe510Ser), and p.(Val530CysfsTer1), were identified in the whole-genome sequences in the Japanese population reference panel (8.3K JPN) of the Tohoku Medical Megabank Organization. Additionally, four variants, namely p.(Ile369Thr), p.(Phe463Val), p.(Arg500Gln), and p.(Ala526Thr) FMO3, were found in the 8.3K JPN database but were already recorded in the National Center for Biotechnology Information database. Novel FMO3 variants p.[(Met1Leu)] and p.[(Trp231Ter)] were also identified in phenotype-gene analyses of 290 unrelated subjects with self-reported malodor. Among the eight recombinant FMO3 variants tested (except for p.[(Met1Leu)] and p.[(Trp231Ter)]), Arg500Gln and Gly191Asp FMO3, respectively, had lower and much lower capacities for trimethylamine and/or benzydamine N-oxygenation activities than wild-type FMO3. Because another FMO3 mutation p.[(Gly191Cys)] with diminished recombinant protein activity was previously detected in two independent probands, Gly191 would appear to be important for FMO3 catalytic function. Analysis of whole-genome sequence data and trimethylaminuria phenotypes revealed missense FMO3 variants that severely impaired FMO3-mediated N-oxygenations in Japanese subjects that could be susceptible to low drug clearances., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2022 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Background: Little is known of whether Internet use is associated with physical activity among socially isolated older adults during the coronavirus disease 2019 (COVID-19) pandemic. This study investigated the association between Internet use and physical activity, and whether this association differs depending on social isolation among community-dwelling Japanese older adults., Methods: A cross-sectional study was conducted with 1048 community-dwelling residents aged 65-90 years. Data were obtained using a self-reported questionnaire in August 2020. Physical activity was assessed using the International Physical Activity Questionnaire-Short Form. Multivariable logistic regression analyses were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between Internet use and moderate-to-vigorous physical activity (MVPA)., Results: Internet use showed a significant association with MVPA (OR = 1.42, 95% CI: 1.06-1.90) after adjusting for age, sex, self-reported socioeconomic status, and other health-related characteristics. When the results were stratified by social participation and living status, Internet use was associated with a significantly higher likelihood of MVPA among participants with no social participation (OR = 1.81, 95% CI: 1.03-3.17) and living with family (OR = 1.40, 95% CI: 1.02-1.93)., Conclusion: Internet use was associated with sufficient physical activity, and this association may differ depending on the social isolation among community-dwelling older adults in Japan., (© 2022. The Author(s).)

The aim of this study was to determine the proportion of near-miss dispensing errors in hospital pharmacies in Japan. A prospective multi-center observational study was conducted between December 2018 and March 2019. The primary objective was to determine the proportion of near-miss dispensing errors in hospital pharmacy departments. The secondary objective was to determine the predictive factors for near-miss dispensing errors using multiple logistic regression analysis. The study was approved by the ethical committee at The Institute of Medical Sciences, University of Tokyo, Japan. A multi-center prospective observational study was conducted in 20 hospitals comprising 8862 beds. Across the 20 hospitals, we assessed data from 553 pharmacists and 53039 prescriptions. A near-miss dispensing error proportion of 0.87% (n = 461) was observed in the study. We found predictive factors for dispensing errors in day-time shifts: a higher number of drugs in a prescription, higher number of quantified drugs, such as liquid or powder formula, in a prescription, and higher number of topical agents in a prescription; but we did not observe for career experience level for clinical pharmacists. For night-time and weekend shifts, we observed a negative correlation of near-miss dispensing errors with clinical pharmacist experience level. We found an overall incidence of near-miss dispensing errors of 0.87%. Predictive factors for errors in night-time and weekend shifts was inexperienced pharmacists. We recommended that pharmacy managers should consider education or improved work flow to avoid near-miss dispensing errors by younger pharmacists, especially those working night or weekend shifts.

Increasing numbers of single-nucleotide substitutions of the human flavin-containing monooxygenase 3 (FMO3) gene are being recorded in mega-databases. Phenotype-gene analyses revealed impaired FMO3 variants associated with the metabolic disorder trimethylaminuria. Here, a series of reliable FMO3 genotyping confirmation methods was assembled and developed for 45 impaired FMO3 variants, mainly found in Japanese populations, using singleplex or duplex polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods and singleplex, duplex, or tetraplex allele-specific PCR methods. Nine PCR-RFLP procedures with single restriction enzymes and fourteen duplex PCR-RFLP procedures (for p.Trp41Ter and p.Thr329Ala, p.Met66Val and p.Leu163Pro, p.Pro70Leu and p.Glu308Gly, p.Asn114Ser and p.Ser195Leu, p.Glu158Lys and p.Ile441Thr, p.Cys197Ter and p.Trp388Ter, p.Arg205Cys and p.Val257Met, p.Arg205His and p.Cys397Ser, p.Met211ArgfsTer10 and p.Arg492Trp, p.Arg223Gln and p.Leu473Pro, p.Met260Val and p.Thr488Ala, p.Tyr269His and p.Ala311Pro, p.Ser310Leu and p.Gly376Glu, and p.Gln470Ter and p.Arg500Ter) were newly established along with eight singleplex (for p.Pro153GlnfsTer14, p.Gly191Cys, p.Pro248Thr, p.Ile486Met, and p.Pro496Ser, among others), one duplex (p.Ile199Ser and p.Asp286Tyr), and one tetraplex (p.Ile7Thr, p.Val58Ile, p.Thr201Lys, and p.Gly421Val) allele-specific PCR systems. This series of systems should facilitate the easy detection in a clinical setting of FMO3 variants in Japanese subjects susceptible to low drug clearances or drug reactions possibly caused by impaired FMO3 function., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2021 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Physical activity (PA) is a key determinant of health in older adults. However, little is known about the effect of social factors on PA among older adults during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, we aimed to clarify the association between socioeconomic status, social participation, and PA during the pandemic. A cross-sectional study was conducted on 999 community-dwelling residents aged 65-90 years. A self-administered questionnaire was used to collect socioeconomic status, social participation, and PA data in August 2020. Multivariable logistic regression analyses were used to calculate the odds ratios (ORs) for the associations between socioeconomic status, social participation, and maintaining PA. For both sexes, PA was reduced by approximately 5%-10% after the onset of COVID-19-related distancing restrictions. Men with a low socioeconomic status were less physically active (OR = 0.49, 95% CI: 0.30-0.82). Women who reported social participation had higher odds of maintaining PA (OR = 1.67, 95% CI: 1.13-2.45) during the restrictions. Higher socioeconomic status and social participation levels before the COVID-19 pandemic may have helped older adults to maintain PA during the COVID-19 pandemic. Further research is needed to clarify the potential effects of these factors on the health of older adults.

Background: The relationships between lifestyle-related diseases and polymorphic drug-metabolizing enzyme activities in the general population in Japan remain unclear., Objective: In this study, the relationships between an index of arteriosclerosis and the phenotypic activities of flavin-containing monooxygenase 3 (FMO3) and cytochrome P450 (P450) 2A6 were analysed., Methods: Subjects in a general population in Japan (age range 35-97 years, 640 men and 795 women, 12% were current smokers) who took part in a health check program were recruited., Results: Subjects were divided into two groups using the median ankle-brachial pressure index (ABI) score. Subjects harbouring P450 2A6 wild-type allele had a significant age-adjusted odds ratio of 1.3 (95% CI, 1.0-1.6) of having a lower than median ABI score compared with subjects for mutant P450 2A6. For subjects with wild-type FMO3, the odds ratio of 0.89 was not significant. The proportions of P450 2A6 extensive metabolizers varied significantly across the inter-quartile ranges of the ABI scores (p = 0.008). Furthermore, the proportion of subjects with low ABI scores was also dependent on the phenotypic P450 2A6 activity (p = 0.025) as estimated from the P450 2A6 genotype. These results suggest that in a general population in Japan, the ABI score, as a risk index for arteriosclerosis, is associated with the predicted P450 2A6 phenotype but is not associated with FMO3 function., Conclusion: The P450 2A6 wild-type allele may be a possible candidate biomarker for arteriosclerosis in a general population in Japan with a variety of dietary habits., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: The aim of this study was to identify the risk factors for median nerve dysfunctions after volar locking plate (VLP) fixation for distal radius fracture (DRF). Methods: We prospectively assessed the incidence of median nerve symptoms (MNS) such as numbness, pain, paresthesia, or hypesthesia in the area innervated by the median nerve and evaluated post-operative nerve conduction (NC) in 91 hands of 121 patients after VLP fixation for DRF. Multivariate logistic regression analysis was conducted to identify factors independently associated with MNS and abnormal NC in the injured wrist. Results: There were 18 cases (20%) of MNS on the injured side, 9 hands (10%) of both MNS and abnormal NC, 11 hands (12%) with only abnormal NC, and 9 hands with only MNS. Sensitivity, specificity, and diagnostic accuracy of abnormal NC for diagnosing MNS were 50%, 86%, and 78%, respectively. Four cases did not respond to conservative treatment and received carpal tunnel release concomitantly with plate removal. Logistic regression examination revealed that volar placement of the plate and short stature were significant independent predictors of MNS, while patient age was the sole independent predictor of abnormal NC. Conclusions: Our study demonstrated that plate prominence, short stature, and age were significant independent risk factors for median nerve dysfunctions after VLP fixation for DRF.

1. Flavin-containing monooxygenase 3 (FMO3) in humans is polymorphic in several ethnic groups, including Caucasians, Africans and Asians. Some FMO3 variants are associated with a disorder trimethylaminuria. 2. In the current study, we used the results from urinary phenotyping assays to identify 63 subjects with <85% FMO3 metabolic capacity with respect to trimethylamine N -oxidation among 787 Japanese volunteers with self-reported trimethylaminuria. The 63 subjects with reduced FMO3 activity were screened and investigated in detail to identify novel FMO3 variants. 3. Homozygous or heterozygous individuals for new single nucleotide substitution variants/haplotypes p.(Pro282Leu), p.[(Glu158Lys; Glu308Gly; Thr329Ala)], p.[(Glu158Lys; Glu308Gly; Asp429Gly)], p.[(Val257Met; Leu473Pro)], p.[(Glu158Lys; Glu308Gly; Ile441Thr)], and p.[(Arg205Cys; Gly503Arg)] were identified in six proband subjects and their family members after pedigree analyses. 4. These variant FMO3 proteins recombinantly expressed in Escherichia coli membranes exhibited decreased N -oxygenation activities toward trimethylamine ( V max / K m < 40% that of the wild-type). 5. Although the allele frequencies of the six new variants and/or haplotypes were low, the present results indicated that individuals homozygous or heterozygous for any of these novel missense FMO3 variants or known nonsense mutations such as p.(Cys197Ter) or p.(Arg205Cys) highly found in this self-reported Japanese trimethylaminuria cohort may have reduced FMO3 activity with respect to the N- oxygenation of trimethylamine.

Flavin-containing monooxygenase 3 (FMO3) is a polymorphic xenobiotic- and dietary compound-metabolizing enzyme associated with the genetic disorder trimethylaminuria. We phenotyped 428 Japanese subjects using traditional urinary phenotyping assays and identified two subjects with <20% FMO3 metabolic capacity. Both subjects had novel frameshift mutations. Proband 1 harbored a novel CC deletion resulting in p.[(Pro153Gln fs; Phe166Ter)] FMO3, which was in trans configuration with p.(Cys197Ter). Proband 2 harbored a novel T deletion resulting in p.[(Met211Arg fs; Val220Ter)] FMO3, which was in trans configuration with p.[(Val257Met; Met260Val)]. We also analyzed a new large Japanese database for novel single nucleotide substitutions of FMO3 and identified the following variants with very low frequencies (<∼0.1%): p.(Lys56Glu), p.(Ser112Asn), p.(Asn164Lys), p.(Gly191Cys), p.(Ile199Ser), p.(Pro248Thr), p.(Pro248Leu), p.(Asp286Tyr), and p.(Ala311Pro). Recombinant FMO3 proteins of the above and unanalyzed variants underwent kinetic analysis of their trimethylamine/benzydamine N-oxygenation activities. Gly191Cys, Ile199Ser, Asp286Tyr, and Ala311Pro variant FMO3 proteins exhibited severely decreased activities (V max /K m <5% of wild-type). Although these new variants were rare alleles in Japanese self-reported trimethylaminuria sufferers and in the large genomic database, we found that most Japanese individuals compound heterozygous or homozygous for any of these missense FMO3 variants or known severe mutations [e.g., p.(Cys197Ter)] had impaired FMO3-dependent N-oxygenation of malodorous trimethylamine., (Copyright © 2019 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

The Japanese Society for the Study of Xenobiotics has focused on drug development and clinical pharmacotherapy by applying cutting-edge technology and reviewing drugs. One specific area of focus has been the reverse-translational approach. This approach uses data from the investigation of clinical problems and from the detailed revisiting of preclinical studies to discover new pharmacotherapies and new methods to prevent drug-induced side effects. In 2017, the U.S. Food and Drug Administration restricted the use of prescription codeine cough-and-cold medicines in children. This decision was based on concerns about the effects of the extensive metabolite morphine in cytochrome P450 2D6 ultra-rapid metabolizers. However, there are few reports on the side effects of dihydrocodeine in Japanese children. Our laboratory measured serum concentrations of dihydrocodeine in a 1-month-old infant with respiratory depression who was given dihydrocodeine phosphate in a suspected case of overdosing. Levels of dihydrocodeine and its primary metabolite, dihydromorphine, were high in this infant. However, the molar ratios of glucuronide conjugates of dihydrocodeine and dihydromorphine were lower than those found in a 3-year-old and a 6-year-old child used as references. To support and facilitate reverse-translational research, the elimination of regional differences in the methodologies used for liquid chromatography to measure drug concentrations and for the genotyping of drug-metabolizing enzymes should become the focus in hospitals, laboratories, and doctoral programs.

The Japanese government actively urges pharmacists to support efforts to reduce surplus medicines. However, these activities currently serve only to dispose of surplus medicines; no measures are being taken to fundamentally prevent the accumulation of surplus medicines from the outset. A deep understanding of patients' views about storing medicines at home and how they might be accumulating surplus medicines would contribute to the prevention of surplus accumulation. This study aimed to characterize the process by which elderly chronic disease patients in Japan accumulate surplus medicines. Semi-structured interviews were conducted with 18 elderly patients, and the interview data were analyzed using a modified grounded theory approach (M-GTA) to present the process by which surplus medicines were accumulated at patients' homes. The results suggest that elderly patients with chronic diseases often wish to avoid unnecessary medications because of anxiety about medicines, and that these patients seek to maximize medicine suppression. In this context, patients use their own judgment to decide whether to use medicines as needed. Additionally, when patients accumulate surplus medicines, they hesitate to throw them away because they feel that to do so is mottainai (wasteful), or because they accumulate surplus medicines as emergency household medicines. These findings reveal when and how surplus medicine accumulation occurs and the points at which pharmacists can easily intervene to promote a close relationship with patients.

Background & Aims: Esophageal squamous cell carcinoma (ESCC) is the predominant form of esophageal cancer in Japan. Smoking and drinking alcohol are environmental risk factors for ESCC, whereas single nucleotide polymorphisms in ADH1B and ALDH2, which increase harmful intermediates produced by drinking alcohol, are genetic risk factors. We conducted a large-scale genomic analysis of ESCCs from patients in Japan to determine the mutational landscape of this cancer., Methods: We performed whole-exome sequence analysis of tumor and nontumor esophageal tissues collected from 144 patients with ESCC who underwent surgery at 5 hospitals in Japan. We also performed single-nucleotide polymorphism array-based copy number profile and germline genotype analyses of polymorphisms in ADH1B and ALDH2. Polymorphisms in CYP2A6, which increase harmful effects of smoking, were analyzed. Functions of TET2 mutants were evaluated in KYSE410 and HEK293FT cells., Results: A high proportion of mutations in the 144 tumor samples were C to T substitution in CpG dinucleotides (called the CpG signature) and C to G/T substitutions with a flanking 5' thymine (called the APOBEC signature). Based on mutational signatures, patients were assigned to 3 groups, which associated with environmental (drinking and smoking) and genetic (polymorphisms in ALDH2 and CYP2A6) factors. Many tumors contained mutations in genes that regulate the cell cycle (TP53, CCND1, CDKN2A, FBXW7); epigenetic processes (MLL2, EP300, CREBBP, TET2); and the NOTCH (NOTCH1, NOTCH3), WNT (FAT1, YAP1, AJUBA) and receptor-tyrosine kinase-phosphoinositide 3-kinase signaling pathways (PIK3CA, EGFR, ERBB2). Mutations in EP300 and TET2 correlated with shorter survival times, and mutations in ZNF750 associated with an increased number of mutations of the APOBEC signature. Expression of mutant forms of TET2 did not increase cellular levels of 5-hydroxymethylcytosine in HEK293FT cells, whereas knockdown of TET2 increased the invasive activity of KYSE410 ESCC cells. Computational analyses associated the mutations in NFE2L2 we identified with transcriptional activation of its target genes., Conclusions: We associated environmental and genetic factors with base substitution patterns of somatic mutations and provide a registry of genes and pathways that are disrupted in ESCCs. These findings might be used to design specific treatments for patients with esophageal squamous cancers., (Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objective: There are conflicting reports regarding the effects of cytochrome P450 (P450, CYP) genotypes on the plasma concentrations of risperidone and its pharmacologically active metabolite, 9-hydroxyrisperidone (paliperidone), in clinical patients. The aim of this study was to investigate individual differences in the metabolic clearance of risperidone in vitro and in vivo., Methods: In vitro liver microsomal risperidone 9-hydroxylation activities and in vivo plasma concentrations of risperidone and paliperidone were investigated in 15 male and 12 female Japanese subjects (mean age 52 years, range: 24-75 years) genotyped for CYP2D6 and CYP3A5., Results: CYP2D6 intermediate and poor metabolizers showed significantly lower liver microsomal risperidone 9-hydroxylation activities than extensive metabolizers did at 5 μM of risperidone; this difference was not evident at 50 μM of risperidone. The recombinant CYP3A5 Vmax/Km value for risperidone 9-hydroxylation was 30% that of CYP3A4, and liver microsomes from CYP3A5 expressers had similar risperidone 9-hydroxylation activities to those of CYP3A5 poor expressers. The plasma concentration/dose ratios for risperidone and paliperidone in 27 Japanese patients were not significantly influenced by the CYP2D6 or CYP3A5 genotypes., Conclusions: Individual differences in metabolic clearance of risperidone under the present conditions were not significantly influenced by the genotypes of CYP2D6 or CYP3A5., (Copyright © 2016 John Wiley & Sons, Ltd.)

Objective: The antipsychotic olanzapine is reportedly metabolized by inducible human cytochrome P450 (CYP) 1A2 and variable copy-number CYP2D6 and polymorphic flavin-containing monooxygenase 3 (FMO3) in different pathways. We investigated individual differences in the metabolite formation and clearance of olanzapine in vitro and in vivo., Methods: Human liver microsomal olanzapine oxidation activities were evaluated, and plasma concentrations of olanzapine were determined in 21 Japanese patients (mean age: 50 years, range: 32-69 years, 14 male and 7 female, including 6 smokers) genotyped for CYP2D6 (*1, *5, and *10) and FMO3 (E158K, C197fsX, R205C, V257M, E308G, and R500X)., Results: Furafylline (a CYP1A2 inhibitor), quinidine (a CYP2D6 inhibitor), and heat treatment (inactivates FMO3) suppressed liver microsomal metabolic clearance of olanzapine by approximately 30%. Olanzapine N-demethylation and N-oxygenation were found to be catalyzed by CYP1A2 and CYP2D6 and by CYP2D6 and FMO3, respectively, in experiments using liver microsomes and recombinant enzymes. Plasma concentrations and clearance of olanzapine were not affected by CYP2D6 or FMO3 genotypes or smoking behavior., Conclusions: Olanzapine clearance was not affected by CYP2D6 or FMO3 genotypes or smoking behavior as a single factor under the present conditions because olanzapine clearance is mediated by multiple enzymes involved in two major and one minor pathways., (Copyright © 2016 John Wiley & Sons, Ltd.)

Loss-of-function mutations of flavin-containing monooxygenase 3 (FMO3), the enzyme responsible for trimethylamine N-oxygenation, cause the inherited disorder trimethylaminuria, or fish odor syndrome. The aim of this study was to further investigate the inter-individual variations of FMO3 activity in a Japanese cohort that we had studied previously. The subjects were 640 Japanese volunteers with self-reported trimethylaminuria; genomic DNA was sequenced in those that had 10-70% FMO3 metabolic capacity in urine tests. A heterozygote for the novel single nucleotide substitution p.Ile441Thr (proband 1) and a heterozygote for the novel single nucleotide substitution p.Ser195Leu (proband 2) were identified. The biological parents of probands 1 and 2 were heterozygous and had >90% trimethylamine N-oxygenation metabolic capacity. In addition, single nucleotide substitutions p.Val58Ile, p.Pro70Leu, and p.Gly421Val in FMO3 were found in probands 3-7. In the course of DNA sequencing, another FMO3 variant, p.Thr488Ala, was found in two unrelated heterozygous subjects. Variant FMO3 proteins recombinantly expressed in Escherichia coli membranes exhibited decreased activity toward typical FMO3 substrates. Although the allele frequencies of these six novel variants were low (<1%), the present results suggest that individuals homozygous or heterozygous for any of the six novel missense FMO3 variants or known nonsense mutations such as p.Cys197stop or p.Arg500stop may possess abnormal trimethylamine N-oxygenation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Purpose: although CYP2D6*36 was thought to be one of the alleles causing the poor metabolizer phenotype, several in vitro studies clarified that the enzyme produced by CYP2D6*36 showed enzymatic activities. However, the effects of CYP2D6*36 in tandem with CYP2D6*10 on the in vivo CYP2D6 activity have been unclear. In this study, we investigated in vivo metabolic capacities of CYP2D6 among the subjects carrying different numbers of CYP2D6*36 in tandem with CYP2D6*10., Methods: we measured the metabolic ratio (MR) of dextromethorphan in 98 subjects. We determined the CYP2D6 genotype of these subjects, including allelic copy number of CYP2D6*10 and CYP2D6*36 by direct sequencing, TaqMan assay, and real-time Invader assay., Results: single copies of CYP2D6*10 and tandem duplication of CYP2D6*36-*10 alleles were found at frequencies of 8.7 and 32.7%, respectively. Median dextromethorphan MRs of the subjects carrying CYP2D6*10 and CYP2D6*36-*10 were not significantly different (P = 0.24)., Conclusions: CYP2D6*36 in tandem with CYP2D6*10 plays a minor role in interindividual variation of dextromethorphan metabolism in vivo.

During the course of sequencing for the CYP2D6 gene, we found a novel single nucleotide polymorphism of g.3318G>A (E383K) associated with CYP2D6*10, termed as CYP2D6*72. We also found a g.1611T>A (F120I) in the CYP2D6*49, which was previously identified as a CYP2D6*10-associated allele in an independent Japanese population. To clarify the effects of these novel CYP2D6*10 haplotypes on the functions of CYP2D6, kinetic analysis for dextromethorphan O-demethylation was performed using the Escherichia coli expression system and human liver microsomes. The V(max)/K(m) values for dextromethorphan O-demethylation catalyzed by recombinant CYP2D6 forms encoded by CYP2D6*10, CYP2D6*49, and CYP2D6*72 were 3.0, 0.5, and 1.3%, respectively, compared with that catalyzed by CYP2D6.1. Liver microsomes from a human subject genotyped as CYP2D6*10/*49 also showed a reduced dextromethorphan O-demethylase activity. CYP2D6.49 formed a 7-hydroxydextromethorphan, with a roughly similar V(max)/K(m) value to that of O-demethylation. These results suggest that these two CYP2D6*10 haplotypes are possible causes of interindividual variation in the activities and the substrate specificity of CYP2D6.

Trimethylaminuria (fish odor syndrome) is a metabolic disorder characterized by the inability to convert malodorous dietary-derived trimethylamine (TMA) to odorless TMA N-oxide by the flavin-containing monooxygenase 3 (FMO3). Mutations of the FMO3 gene were investigated in Japanese trimethylaminuria that showed low FMO3 metabolic capacity. Novel polymorphisms in the FMO3 gene causing stop codons at Cys197, Trp388, Gln470 or Arg500 of FMO3 were discovered in self-reported trimethylaminuria Japanese volunteers. Different metabolic capacities of FMO3 were observed for Asn114Ser, Thr201Lys, Arg205Cys or Met260Val FMO3 variants in addition to common Glu158Lys, Val257Met, and Glu308Gly FMO3. Estimated allelic frequencies for these novel mutated FMO3 genes for the Japanese population examined was approximately 1-4 % in this Japanese cohort. Recombinant Arg500stop (94% of the whole FMO3 structure) and several missense FMO3 variants showed no detectable activity and different effects on N- and S-oxygenation activities, respectively. The family members of Japanese probands who were heterozygous for these nonsense mutants generally showed moderate TMA N-oxygenation metabolic capacity, suggesting that heterozygotes for the nonsense mutations will exhibit trimethylaminuria symptoms only if they have, on the other chromosome, a mutation that substantially impairs enzyme activity. In addition, other causal factors for decreased FMO3 metabolic capacity such as liver damage or menstruation and treatment with copper chlorophyllin are also included in this minireview. The present article provides fundamental information for the importance of future investigations of the human FMO3 gene associated with trimethylaminuria (fish odor syndrome).

In the present study, we identified three novel single nucleotide polymorphisms (SNPs), 147C>T in exon 2 (silent), 602G>C in exon 3 (Arg201Pro), and 1134C>T in exon 4 (silent), in the gene of bile acid CoA: amino acid N-acyltransferase (BAAT) by resequencing the entire coding region and the exon-intron junctions of 100 Japanese individuals. The allelic frequencies were 0.005 for 147C>T, 0.095 for 602G>C, and 0.015 for 1134C>T. The two known SNPs, 59G>A (Arg20Gln, rs1572983) and UTR1513G>A (rs2229594), were detected at a frequency of 0.500 and 0.425, respectively. In the haplotype analysis for the 59G>A and 602G>C polymorphisms, the allelic frequency of 59G-602G, 59G-602C, 59A-602G and 59A-602C was 0.405, 0.095, 0.500 and 0.000, respectively. On the other hand, the allelic frequency of the nonsynonymous SNP 602G>C was 0.194 in a Caucasian population.

We sequenced all exons and exon-intron junctions of the flavin-containing monooxygenase 3 (FMO3) gene from 3 Japanese individuals and their family members, who were case subjects that showed low FMO3 metabolic capacity among a population of self-reported trimethylaminuria Japanese volunteers (n=50). We found three novel single nucleotide polymorphisms (SNPs) (g. 20752 A>G, g. 27400 G>A, and g. 30308 C>T) causing an amino acid substitution and stop codons, Asn114Ser in exon 4, Trp388Stop in exon 7, and Gln470Stop in exon 9, respectively. The Trp388Stop and Gln470Stop also presented together with known SNPs, Val257Met and Glu158Lys, respectively, in the same alleles of the FMO3 gene to form novel haplotypes. These sequences are as follows: 1) SNP, 060825Shimizu004; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-TATCCAGTGTAAA/GTAAACATCCTGA-3'. 2) SNP, 060825Shimizu005; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-CCAGTCCCGCTGG/AGCAGCACAAGTA-3'. 3) SNP, 060825Shimizu006; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-TGTAGTCCCTACC/TAGTTTAGGCTGG-3'.

The reduced capacity of flavin-containing monooxygenase 3 (FMO3) to N-oxidize trimethylamine (TMA) is believed to cause a metabolic disorder. The aim of this study was to investigate the inter-individual variations of FMO3. Genomic DNA of case subjects that showed only 10-20% of FMO3 metabolic capacity among self-reported trimethylaminuria Japanese volunteers was sequenced. Functional analysis of recombinant FMO3 proteins was also performed. One homozygote for a novel single nucleotide substitution causing a stop codon at Arg500 was observed. The biological parents of this Proband A were heterozygous and showed >90% TMA N-oxygenation metabolic capacity. Another Proband B had the Arg500Stop and Cys197Stop codons. The TMA N-oxygenation metabolic capacities of the father and brother of this Proband B were apparently observed by possessing Arg205Cys mutant that coded for decreased TMA N-oxygenase. Recombinant Arg500Stop FMO3 cDNA expressed in Escherichia coli membranes and a series of highly purified truncation mutants at different positions of the C-terminus of FMO3 showed no detectable functional activity toward typical FMO3 substrates. The results suggest that individuals homozygous for either of the nonsense mutations, Arg500Stop and/or Cys197Stop alleles, in the FMO3 gene can possess abnormal TMA N-oxygenation.

We sequenced all exons and exon-intron junctions of the flavin-containing monooxygenase 3 (FMO3) gene from 2 Japanese individuals and their family members, who were case subjects that showed low FMO3 metabolic capacity among a population of self-reported trimethylaminuria Japanese volunteers. We found two novel single nucleotide polymorphisms (SNPs) (21,254 C>A and 24,006 A>G) causing amino acid substitutions, Thr(201)Lys in exon 5 and Met(260)Val in exon 6, respectively. The Thr(201)Lys and Met(260)Val also presented together with known SNPs (Glu(158)Lys-Glu(308)Gly and Val(257)Met, respectively) in the same alleles of the FMO3 gene to form novel haplotypes. A SNP (30,398 C>T) in the FMO3 gene causing a stop codon at Arg(500) in exon 9 was also discovered. These sequences are as follows: 1) SNP, 060116Shimizu001; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-GTGATATTGCCAC/AAGAACTCAGCCG-3'. 2) SNP, 060116Shimizu002; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-TAC(G/A)TGAAGCAGA/GTGAATGCAAGAT-3'. 3) SNP, 060116Shimizu003; GENE NAME, FMO3; ACCESSION NUMBER, AL021026; LENGTH, 25 base; 5'-CCCATGCAGACAC/TGAGTGGTCGGGA-3'.

The purpose of this study was to evaluate a contribution of polymorphic cytochrome P450 (CYP) 3A5 to the oxidation of diltiazem, midazolam and testosterone by liver microsomes from Japanese subjects. Twenty-seven liver samples were classified into three groups according to the CYP3A5 genotypes; CYP3A5(*)1/(*)1 (n=3), (*)1/(*)3 (n=12) and (*)3/(*)3 (n=12). The results of genotyping and immunochemical quantitation of CYP3A5 protein showed a good accordance between the CYP3A5 genotype and CYP3A5 content but not CYP3A4 content in liver microsomes. The expression levels of hepatic CYP3A5 protein ranged from 20 to 60% of the sum of CYP3A4 and CYP3A5 contents in subjects with at least one wild type allele ((*)1). The CYP3A5 contents correlated well with liver microsomal activities of diltiazem N-demethylation, midazolam 1'- and 4-hydroxylations and testosterone 6beta-hydroxylation among subjects carrying at least one (*)1 allele. In addition, the correlation coefficients of CYP3A5 contents with the rates of diltiazem N-demethylation, midazolam 1'-hydroxylation and testosterone 6beta- hydroxylation were higher than those of CYP3A4, although the value of CYP3A5 with the midazolam 4-hydroxylation rate was similar to that of CYP3A4. Kinetic analyses revealed a biphasic diltiazem N-demethylation in liver microsomes from subjects carrying the (*)1 allele. The apparent V(max)/K(m) values for recombinant CYP3A5 indicated the greater contributions to diltiazem N-demethylation and midazolam 1'-hydroxylation as compared with CYP3A4. These results suggest that polymorphic CYP3A5 contributes markedly to the drug oxidations, particularly diltiazem N-demethylation, midazolam 1'- hydroxylation and testosterone 6beta-hydroxylation by liver microsomes from Japanese subjects.

The expression level of mRNAs for cytochrome P450 (CYP) 1A1 and 1B1 in freshly prepared white cells from 72 subjects exposed to dioxins at waste incinerators was investigated. The amounts of CYP1B1 mRNA ranged from 0.16 to 671 molecules/10(7) molecules of 18S rRNA, whereas the amounts of CYP1A1 mRNA were <6 molecules/10 ng total RNA, indicating that CYP1A1 was not induced to a detectable level by environmentally exposed dioxins. The inducibility of CYP1B1 mRNA in leukocytes, defined as the ratio of CYP1B1 mRNA to the plasma concentration of dioxins, varied among the subjects. It was found that the subjects showed trimodal distribution according to inducibility: 39 (54.2%), 25 (34.7%), and 8 (11.1%) of 72 subjects were judged as poor, intermediate, and high responders to environmental dioxins, respectively. The amounts of CYP1B1 mRNA in leukocytes of the intermediate and high responders were highly correlated with the plasma concentrations of dioxins (P < 0.05 and <0.01). These results suggest that CYP1B1 with polymorphic inducibility by dioxins is involved in aromatic hydrocarbon hydroxylase activities in human lymphocytes.

Objective: We assessed in vivo activities of cytochrome P450 1A2 (CYP1A2), N-acetyltransferase 2, and xanthine oxidase in Japanese residents of Kyushu, the southern island of Japan., Methods: One hundred eighty-two healthy volunteers (108 men and 74 women) received a 150-mg oral dose of caffeine before they went to sleep. The concentrations of caffeine, caffeine metabolites, and uric acid in their overnight urine samples were analyzed. The CYP2A6 genotypes were determined in 66 of the 182 volunteers to assess whether they affected a metabolic ratio for CYP1A2 activity index., Results: The metabolic ratio for CYP1A2 was not polymorphic, but its mean ratio was greater in smokers than in nonsmokers (P <.05). Twenty subjects (11.0%) were found to be slow acetylators. Twenty subjects were determined to be putative poor metabolizers of xanthine oxidase, and the mean urinary uric acid concentration of those subjects was 53% lower than that of the other subjects (P <.0001). The mean ratio for CYP1A2 obtained from 3 subjects with the CYP2A6(*)4C/CYP2A6(*)4C genotype was greater than the mean ratio from subjects with other genotypes (P <.01) or that from subjects with a wild-type CYP2A6(*)1A allele (P <.05)., Conclusions: Our results suggest that putative poor metabolizers of xanthine oxidase activities exist in a Japanese population and that a decreased 1,7-dimethyluric acid formation from caffeine in poor metabolizers of CYP2A6 appears to affect the metabolic ratio used for the assessment of CYP1A2 activity.