A population-based urinary and plasma metabolomics study of environmental exposure to cadmium.

BACKGROUND: The application of metabolomics-based profiles in environmental epidemiological studies is a promising approach to refine the process of health risk assessment. We aimed to identify potential metabolomics-based profiles in urine and plasma for the detection of relatively low-level cadmium (Cd) exposure in large population-based studies. METHOD: We analyzed 123 urinary metabolites and 94 plasma metabolites detected in fasting urine and plasma samples collected from 1,412 men and 2,022 women involved in the Tsuruoka Metabolomics Cohort Study. Regression analysis was performed for urinary N-acetyl-beta-D-glucosaminidase (NAG), plasma, and urinary metabolites as dependent variables, and urinary Cd (U-Cd, quartile) as an independent variable. The multivariable regression model included age, gender, systolic blood pressure, smoking, rice intake, BMI, glycated hemoglobin, low-density lipoprotein cholesterol, alcohol consumption, physical activity, educational history, dietary energy intake, urinary Na/K ratio, and uric acid. Pathway-network analysis was carried out to visualize the metabolite networks linked to Cd exposure. RESULT: Urinary NAG was positively associated with U-Cd, but not at lower concentrations (Q2). Among urinary metabolites in the total population, 45 metabolites showed associations with U-Cd in the unadjusted and adjusted models after adjusting for the multiplicity of comparison with FDR. There were 12 urinary metabolites which showed consistent associations between Cd exposure from Q2 to Q4. Among plasma metabolites, six cations and one anion were positively associated with U-Cd, whereas alanine, creatinine, and isoleucine were negatively associated with U-Cd. Our results were robust by statistical adjustment of various confounders. Pathway-network analysis revealed metabolites and upstream regulator changes associated with mitochondria (ACACB, UCP2, and metabolites related to the TCA cycle). CONCLUSION: These results suggested that U-Cd was associated with metabolites related to upstream mitochondrial dysfunction in a dose-dependent manner. Our data will help develop environmental Cd exposure profiles for human populations.

Association of Nonalcoholic Fatty Liver Disease with Arterial Stiffness and its Metabolomic Profiling in Japanese Community-Dwellers.

AIMS: Nonalcoholic fatty liver disease (NAFLD) is known to be associated with atherosclerosis. This study focused on upstream changes in the process by which NAFLD leads to atherosclerosis. The study aimed to confirm the association between NAFLD and the cardio-ankle vascular index (CAVI), an indicator of subclinical atherosclerosis, and explore metabolites involved in both by assessing 94 plasma polar metabolites. METHODS: A total of 928 Japanese community-dwellers (306 men and 622 women) were included in this study. The association between NAFLD and CAVI was examined using a multivariable regression model adjusted for confounders. Metabolites commonly associated with NAFLD and CAVI were investigated using linear mixed-effects models in which batch numbers of metabolite measurements were used as a random-effects variable, and false discovery rate-adjusted p-values were calculated. To determine the extent to which these metabolites mediated the association between NAFLD and CAVI, mediation analysis was conducted. RESULTS: NAFLD was positively associated with CAVI (coefficients [95% Confidence intervals (CI)]=0.23 [0.09-0.37]; p=0.001). A total of 10 metabolites were involved in NAFLD and CAVI, namely, branched-chain amino acids (BCAAs; valine, leucine, and isoleucine), aromatic amino acids (AAAs; tyrosine and tryptophan), alanine, proline, glutamic acid, glycerophosphorylcholine, and 4-methyl-2-oxopentanoate. Mediation analysis showed that BCAAs mediated more than 20% of the total effect in the association between NAFLD and CAVI. CONCLUSIONS: NAFLD was associated with a marker of atherosclerosis, and several metabolites related to insulin resistance, including BCAAs and AAAs, could be involved in the process by which NAFLD leads to atherosclerosis.

Study Profile of the Tsuruoka Metabolomics Cohort Study (TMCS).

The Tsuruoka Metabolomics Cohort Study (TMCS) is an ongoing population-based cohort study being conducted in the rural area of Yamagata Prefecture, Japan. This study aimed to enhance the precision prevention of multi-factorial, complex diseases, including non-communicable and aging-associated diseases, by improving risk stratification and prediction measures. At baseline, 11,002 participants aged 35-74 years were recruited in Tsuruoka City, Yamagata Prefecture, Japan, between 2012 and 2015, with an ongoing follow-up survey. Participants underwent various measurements, examinations, tests, and questionnaires on their health, lifestyle, and social factors. This study used an integrative approach with deep molecular profiling to identify potential biomarkers linked to phenotypes that underpin disease pathophysiology and provide better mechanistic insights into social health determinants. The TMCS incorporates multi-omics data, including genetic and metabolomic analyses of 10,933 participants and comprehensive data collection ranging from physical, psychological, behavioral, and social to biological data. The metabolome is used as a phenotypic probe because it is sensitive to changes in physiological and external conditions. The TMCS focuses on collecting outcomes for cardiovascular disease, cancer incidence and mortality, disability, functional decline due to aging and disease sequelae, and the variation in health status within the body represented by omics analysis that lies between exposure and disease. It contains several sub-studies on aging, heated tobacco products, and women's health. This study is notable for its robust design, high participation rate (89%), and long-term repeated surveys. Moreover, it contributes to precision prevention in Japan and East Asia as a well-established multi-omics platform.

Metabolomics profiles alterations in cigarette smokers and heated tobacco product users.

BACKGROUND: Heated tobacco products (HTPs) have gained global popularity, but their health risks remain unclear. Therefore, the current study aimed to identify plasma metabolites associated with smoking and HTP use in a large Japanese population to improve health risk assessment. METHODS: Metabolomics data from 9,922 baseline participants of the Tsuruoka Metabolomics Cohort Study (TMCS) were analyzed to determine the association between smoking habits and plasma metabolites. Moreover, alterations in smoking-related metabolites among HTP users were examined based on data obtained from 3,334 participants involved from April 2018 to June 2019 in a follow-up survey. RESULTS: Our study revealed that cigarette smokers had metabolomics profiles distinct from never smokers, with 22 polar metabolites identified as candidate biomarkers for smoking. These biomarker profiles of HTP users were closer to those of cigarette smokers than those of never smokers. The concentration of glutamate was higher in cigarette smokers, and biomarkers involved in glutamate metabolism were also associated with cigarette smoking and HTP use. Network pathway analysis showed that smoking was associated with the glutamate pathway, which could lead to endothelial dysfunction and atherosclerosis of the vessels. CONCLUSIONS: Our study showed that the glutamate pathway is affected by habitual smoking. These changes in the glutamate pathway may partly explain the mechanism by which cigarette smoking causes cardiovascular disease. HTP use was also associated with glutamate metabolism, indicating that HTP use may contribute to the development of cardiovascular disease through mechanisms similar to those in cigarette use.

The association between sleep parameters and sarcopenia in Japanese community-dwelling older adults.

PURPOSE: This study aimed to examine the association between sleep duration and quality and sarcopenia, assessed by factors such as low muscle mass (LMM), low muscle strength (LMS), and low physical performance (LPP) among older community-dwellers in Japan. METHODS: In this cross-sectional study, a total of 2,069 (men, 902; women, 1,167) participants aged 65 to 80 years were included. Sarcopenia and each low physical function were defined using the definitions of the Asian Working Groups of Sarcopenia 2019. Sleep duration was stratified into three categories: short sleep (<6 h), normal sleep (6-8 h), and long sleep (>8 h). Sleep quality was classified into two groups based on 8-item Athens Insomnia Scale score: insomnia (≥6), and non-insomnia (<6). We analyzed the association between sleep parameters and sarcopenia, including low physical functions, by logistic regression analysis. RESULTS: Compared to normal sleepers, long sleepers had a positive association with sarcopenia (odds ratio [OR] 2.11, 95% confidence interval [CI] 1.25-3.58). In particular, long sleep was strongly associated with LMS (OR 1.77, 95%CI 1.07-2.94) and LPP (OR 1.90, 95%CI 1.25-2.88). On the other hand, poor sleep quality was not associated with sarcopenia in long sleepers, but in normal sleepers. CONCLUSIONS: Long sleep was associated with sarcopenia, including LMS and LPP. However, in long sleepers, insomnia was not associated with sarcopenia or any of its components.

Accumulated unhealthy behaviours and insomnia in Japanese dwellers with and without cardiovascular risk factors: a cross-sectional study.

OBJECTIVES: To date, the association between accumulated unhealthy behaviours and insomnia in individuals stratified according to the presence or absence of major cardiovascular risk factors is unclear. This study aimed to examine the effect of accumulated unhealthy behaviours on insomnia in Japanese dwellers. DESIGN: Cross-sectional study. SETTING: Baseline data between April 2012 and March 2015. PARTICIPANTS: Our study used cross-sectional data among Japanese aged 35-74 years in a rural community (N=9565), the attendees of annual municipal or work site health check-up programmes. MAIN OUTCOME MEASURES: Insomnia was assessed by Athens Insomnia Scale, which was set at 6 points and greater; other scales were given. Participants were categorised into three groups by their number of unhealthy behaviours (no exercise habit, smoking, alcohol drinking, skipping breakfast and obesity): 0-1, 2-3, 4 or more. The association between accumulated unhealthy behaviours and insomnia was estimated by logistic regression analysis. Further analysis was done after stratification of cardiovascular risk factors assessed by anthropometrics and clinical biochemistry measurements. RESULTS: The overall prevalence of insomnia was 13.3% for men and 19.3% for women. Men with unhealthy behaviour factors were more likely to have insomnia after adjusting for potential confounders, compared with the least unhealthy group (trend p=0.013). Women with four or more unhealthy behaviour factors were more likely to have insomnia, compared with the lowest groups (OR 1.175, 95% CI 1.077 to 1.282). Insomnia has an association with the unhealthy behaviours among men without cardiovascular risk factors (lowest groups: OR 1.133, 95% CI 1.037 to 1.238, trend p=0.026). Women without hypertension were more likely to have suspected insomnia, compared with the lowest group (OR 1.215, 95% CI 1.101 to 1.341). CONCLUSION: The results showed accumulated unhealthy behaviours were associated with increased risk of insomnia in Japanese dwellers. For healthy population without cardiovascular risk factors, unhealthy behaviours should be considered as background conditions for insomnia.

Changes in Smoking Habits and Behaviors Following the Introduction and Spread of Heated Tobacco Products in Japan and Its Effect on FEV1 Decline: A Longitudinal Cohort Study.

BACKGROUND: Heated tobacco product (HTP) use in Japan has rapidly increased. Despite this rapid spread, little is known about the health effects of HTP use. We conducted a longitudinal cohort study to investigate the change in smoking habits following the spread of HTP use and its effect on forced expiratory volume in 1 second (FEV1) decline. METHODS: Participants consisted of a resident population (n = 2,612; mean age, 67.7 years) with FEV1 measurement in 2012-2014 and 2018-2019, and a worksite population (n = 722; mean age 49.3 years) without FEV1 data. Participants were categorized as combustible cigarette-only smokers, HTP-only users, dual users, past smokers, and never smokers. The association between smoking group and the change in smoking consumption over a mean 5.6 years was examined. Differences in annual FEV1 change between smoking groups were examined in the resident population. RESULTS: Prevalence of HTP-only and dual users in 2018-2019 was 0.8% and 0.6% in the resident population, and 5.0% and 1.9% in the worksite population, respectively. The overall number of tobacco products smoked/used increased in dual users compared to baseline, but not in others. Annual FEV1 decline in dual users tended to be greater than that in cigarette-only smokers (16; 95% confidence interval, -34 to 2 mL/year after full adjustment). Participants switching to HTP-only use 1.7 years before had a similar FEV1 decline as cigarette-only smokers. CONCLUSIONS: HTP use, including dual use, is prevalent even in a rural region of Japan. Dual users appear to smoke/use tobacco products more and have a greater FEV1 decline. Tobacco policy should consider dual use as high-risk.

Metabolic profiling of charged metabolites in association with menopausal status in Japanese community-dwelling midlife women: Tsuruoka Metabolomic Cohort Study.

BACKGROUND: Emerging evidence has shown that charged metabolites, such as amino acids, may play an important role in the pathogenesis of various metabolic disorders, many of which women in the postmenopausal period are at high risk of developing. This study examined the metabolic profile of middle-aged Japanese women to investigate alterations in charged metabolites induced by menopausal transition. METHODS: The participants were 1193 female residents aged 40-60 at the baseline survey of the Tsuruoka Metabolomics Cohort Study. We investigated the cross-sectional association of menopausal status with 94 metabolomic biomarkers assayed in fasting plasma samples via capillary electrophoresis time-of-flight mass spectrometry using linear regression analysis. RESULTS: Among the participants, 529 were premenopausal, 132 were in menopausal transition (MT), and 532 were postmenopausal. Significant differences were found in age, blood pressure, glucose and lipid levels, and smoking and drinking habits among the three groups. The concentrations of 5 metabolites in the MT group and 15 metabolites in the postmenopausal group were significantly higher than those in the premenopausal group after adjusting for confounding factors. When classified into pathways, these metabolites were related to the tricarboxylic cycle, urea cycle, and homocysteine metabolism, some of which are linked to arteriosclerosis. CONCLUSION: Multiple charged metabolites were associated with women's menopausal status, showing a gradual increase as women shifted from pre-, to peri-, to postmenopause. These findings might reflect the early changes behind the increased risk of dyslipidemia, diabetes, cardiovascular disease, and osteoporosis in later life.

SARS-CoV-2 Infection among Medical Institution Faculty and Healthcare Workers in Tokyo, Japan.

Objective To consider effective measures against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in medical institutions, this study estimated the SARS-CoV-2 infection rate among healthcare workers (HCWs) in Tokyo, Japan, and determined the specific findings for mild coronavirus disease 2019 (COVID-19) cases. Methods This study analyzed the results of serologic tests to detect immunoglobulin G antibodies against SARS-CoV-2 and evaluated the demographic and clinical characteristics of the faculty and HCWs at a Tokyo medical institution in August 2020. The demographic and clinical characteristics of participants with antibody-positive results were compared to those of participants with antibody-negative results. Materials This study recruited 2,341 faculty and HCWs at a Tokyo medical institution, 21 of whom had a COVID-19 history. Results Of the 2,320 participants without a COVID-19 history, 20 (0.862%) had positive serologic test results. A fever and dysgeusia or dysosmia occurred with greater frequency among the participants with positive test results than in those with negative results [odds ratio (OR), 5.475; 95% confidence interval (CI), 1.960-15.293 and OR, 24.158; 95% CI, 2.693-216.720, respectively]. No significant difference was observed in the positivity rate between HCWs providing medical care for COVID-19 patients using adequate protection and other HCWs (OR, 2.514; 95% CI, 0.959-6.588). Conclusion To reduce the risk of COVID-19 spread in medical institutions, faculty and HCWs should follow standard and necessary transmission-based precautions, and those with a fever and dysgeusia or dysosmia should excuse themselves from work as soon as possible.

Correction: Charged metabolite biomarkers of food intake assessed via plasma metabolomics in a population-based observational study in Japan.

[This corrects the article DOI: 10.1371/journal.pone.0246456.].

Reliability of urinary charged metabolite concentrations in a large-scale cohort study using capillary electrophoresis-mass spectrometry.

Currently, large-scale cohort studies for metabolome analysis have been launched globally. However, only a few studies have evaluated the reliability of urinary metabolome analysis. This study aimed to establish the reliability of urinary metabolomic profiling in cohort studies. In the Tsuruoka Metabolomics Cohort Study, 123 charged metabolites were identified and routinely quantified using capillary electrophoresis-mass spectrometry (CE-MS). We evaluated approximately 750 quality control (QC) samples and 6,720 participants' spot urine samples. We calculated inter- and intra-batch coefficients of variation in the QC and participant samples and technical intraclass correlation coefficients (ICC). A correlation of metabolite concentrations between spot and 24-h urine samples obtained from 32 sub-cohort participants was also evaluated. The coefficient of variation (CV) was less than 20% for 87 metabolites (70.7%) and 20-30% for 19 metabolites (15.4%) in the QC samples. There was less than 20% inter-batch CV for 106 metabolites (86.2%). Most urinary metabolites would have reliability for measurement. The 96 metabolites (78.0%) was above 0.75 for the estimated ICC, and those might be useful for epidemiological analysis. Among individuals, the Pearson correlation coefficient of 24-h and spot urine was more than 70% for 59 of the 99 metabolites. These results show that the profiling of charged metabolites using CE-MS in morning spot human urine is suitable for epidemiological metabolomics studies.

Association of the Estimated Coronary Artery Incidence Risk According to the Japan Atherosclerosis Society Guidelines 2017 with Cardio-Ankle Vascular Index.

AIMS: The categories in the comprehensive lipid and risk management guidelines were proposed by the Japan Atherosclerosis Society (JAS Guidelines 2017), which adopted the estimated 10 year absolute risk of coronary artery disease (CAD) incidence in the Suita score. We examined whether those categories were concordant with the degree of arterial stiffness. METHODS: In 2014, the cardio-ankle vascular index (CAVI), an arterial stiffness parameter, was measured in 1,972 Japanese participants aged 35-74 years in Tsuruoka City, Yamagata Prefecture, Japan. We examined the mean CAVI and the proportion and odds ratios (ORs) of CAVI ≥ 9.0 on the basis of the following three management classifications using the analysis of variance and logistic regression: "Category I (Low risk)," "Category II (Middle risk)," and "Category III (High risk)." RESULTS: The mean CAVI and proportion of CAVI ≥ 9.0 were 8.6 and 34.8% among males and 8.1 and 18.3% among females, respectively. The mean CAVI and proportion of CAVI ≥ 9.0 were associated with an estimated 10 year absolute risk for CAD among males and females, excluding High risk for females. These results were similar to the management classification by the guideline: the multivariable-adjusted ORs (95% confidence intervals) of CAVI ≥ 9.0 among Category II and Category III compared with those among Category I were 2.96 (1.61-5.43) and 7.33 (4.03-13.3) for males and 3.99 (2.55-6.24) and 3.34 (2.16-5.16) for females, respectively. CONCLUSIONS: The risk stratification, which was proposed in the JAS Guidelines 2017, is concordant with the arterial stiffness parameter.

Charged metabolite biomarkers of food intake assessed via plasma metabolomics in a population-based observational study in Japan.

Food intake biomarkers can be critical tools that can be used to objectively assess dietary exposure for both epidemiological and clinical nutrition studies. While an accurate estimation of food intake is essential to unravel associations between the intake and specific health conditions, random and systematic errors affect self-reported assessments. This study aimed to clarify how habitual food intake influences the circulating plasma metabolome in a free-living Japanese regional population and to identify potential food intake biomarkers. To achieve this aim, we conducted a cross-sectional analysis as part of a large cohort study. From a baseline survey of the Tsuruoka Metabolome Cohort Study, 7,012 eligible male and female participants aged 40-69 years were chosen for this study. All data on patients' health status and dietary intake were assessed via a food frequency questionnaire, and plasma samples were obtained during an annual physical examination. Ninety-four charged plasma metabolites were measured using capillary electrophoresis mass spectrometry, by a non-targeted approach. Statistical analysis was performed using partial-least-square regression. A total of 21 plasma metabolites were likely to be associated with long-term food intake of nine food groups. In particular, the influential compounds in each food group were hydroxyproline for meat, trimethylamine-N-oxide for fish, choline for eggs, galactarate for dairy, cystine and betaine for soy products, threonate and galactarate for carotenoid-rich vegetables, proline betaine for fruits, quinate and trigonelline for coffee, and pipecolate for alcohol, and these were considered as prominent food intake markers in Japanese eating habits. A set of circulating plasma metabolites was identified as potential food intake biomarkers in the Japanese community-dwelling population. These results will open the way for the application of new reliable dietary assessment tools not by self-reported measurements but through objective quantification of biofluids.

Validity Assessment of Self-reported Medication Use for Hypertension, Diabetes, and Dyslipidemia in a Pharmacoepidemiologic Study by Comparison With Health Insurance Claims.

BACKGROUND: Although self-reported questionnaires are widely employed in epidemiologic studies, their validity has not been sufficiently assessed. The aim of this study was to evaluate the validity of a self-reported questionnaire on medication use by comparison with health insurance claims and to identify individual determinants of discordance in the Tsuruoka Metabolomics Cohort Study. METHODS: Participants were 2,472 community-dwellers aged 37 to 78 years from the Tsuruoka Metabolomics Cohort Study. Information on lifestyle and medications was collected through a questionnaire. Sensitivity and specificity were determined using health insurance claims from November 2014 to March 2016, which were used as a standard. Potential determinants of discordance were assessed using multivariable logistic regression. RESULTS: The self-reported questionnaire on medication use showed high validity. Sensitivity and specificity were 0.95 (95% CI, 0.93-0.96) and 0.97 (95% CI, 0.96-0.98) for antihypertensive medications, 0.94 (95% CI, 0.91-0.97) and 0.98 (95% CI, 0.98-0.99) for diabetes medications, and 0.84 (95% CI, 0.82-0.87) and 0.98 (95% CI, 0.97-0.99) for dyslipidemia medications, respectively. Males without high education and those who currently smoke cigarettes were found to be associated with discordant reporting which affected sensitivity, especially those with medication use for dyslipidemia. CONCLUSIONS: In this population-based cohort study, we found that the self-reported questionnaire on medication use was a valid measure to capture regular medication users. Sensitivity for dyslipidemia medications was lower than those for the other medications. Type of medication, sex, education years, and smoking status influenced discordance, which affected sensitivity in self-reporting.

Association between dyslipidemia and plasma levels of branched-chain amino acids in the Japanese population without diabetes mellitus.

BACKGROUND: Branched-chain amino acids (BCAAs) play a key role in energy homeostasis. OBJECTIVE: We aimed to investigate the association between plasma BCAA levels and dyslipidemia in the Japanese population without diabetes mellitus. METHODS: This cross-sectional study included 4952 participants without diabetes mellitus, enrolled in the Tsuruoka Metabolomic Cohort Study. Plasma BCAA levels were measured by capillary electrophoresis-mass spectrometry. Correlations between lipid and BCAA profiles were evaluated by sex-stratified multiple linear regression analyses, after adjusting for confounders. Logistic regression was used to identify associations between BCAAs and metabolic dyslipidemia (MD) defined as triglyceride levels ≥150 mg/dL, high-density lipoprotein cholesterol levels ≤40 mg/dL for men and ≤50 mg/dL for women, or low-density lipoprotein cholesterol (LDL-C) levels ≥140 mg/dL. RESULTS: In both sexes, the levels of individual BCAAs and the total BCAA levels correlated positively with triglyceride levels and negatively with high-density lipoprotein cholesterol levels. Valine, leucine, and total BCAA levels were weakly and positively correlated with LDL-C levels. Increased BCAA levels showed positive associations with MD. However, associations between BCAAs and elevated LDL-C levels were unclear. Furthermore, the associations between BCAA levels and MD regardless of fasting blood sugar (FBS) levels (high or low). Although valine, leucine, and total BCAA levels were weakly associated with elevated LDL-C levels in the high-FBS group, no such association was observed in the low-FBS group. CONCLUSIONS: BCAAs might be associated with MD independently of the FBS level and might play an important role in lipid metabolism and dyslipidemia.

Spreading Awareness of Stroke through School-Based Education: A Pooled Analysis of Three Community-Based Studies.

BACKGROUND: Advancing school-based education is a promising means to spread knowledge pertaining to stroke. The aim of the current study was to clarify whether stroke lessons provided by schoolteachers could deliver stroke knowledge to children (aged 9-11 years) and their parents, at a similar level to when taught by medical staff. METHODS: Schoolteachers conducted lessons on stroke for school children using the educational materials we prepared (i.e., the teacher group; 1051 children and 719 parents). This was compared with our previous data from Akashi city and Tochigi prefecture, in which the stroke lessons were conducted by medical staff (i.e., the medical group; 1031 children and 756 parents). Three campaigns were conducted between September 2014 and May 2016. Each child was given education materials to take home to discuss stroke with their parents. The children and their parents answered questionnaires on stroke knowledge, at baseline, immediately after the lesson, and at 3 months after the lesson. RESULTS: Compared with the time point before the lesson, both children and parents instructed by the teacher group showed significant increases in the scores about stroke symptoms and risk factors, immediately and at 3 months after the lesson (P < .001). The combined analysis for the group instructed by medical personnel showed no significant differences in the stroke knowledge scores between the 2 groups at 3 months. CONCLUSIONS: Teacher-led lessons, using our educational material, adequately delivered knowledge of stroke to children and parents, in a manner that was similar to when medical staff delivered this information.

Reliability of plasma polar metabolite concentrations in a large-scale cohort study using capillary electrophoresis-mass spectrometry.

BACKGROUND: Cohort studies with metabolomics data are becoming more widespread, however, large-scale studies involving 10,000s of participants are still limited, especially in Asian populations. Therefore, we started the Tsuruoka Metabolomics Cohort Study enrolling 11,002 community-dwelling adults in Japan, and using capillary electrophoresis-mass spectrometry (CE-MS) and liquid chromatography-mass spectrometry. The CE-MS method is highly amenable to absolute quantification of polar metabolites, however, its reliability for large-scale measurement is unclear. The aim of this study is to examine reproducibility and validity of large-scale CE-MS measurements. In addition, the study presents absolute concentrations of polar metabolites in human plasma, which can be used in future as reference ranges in a Japanese population. METHODS: Metabolomic profiling of 8,413 fasting plasma samples were completed using CE-MS, and 94 polar metabolites were structurally identified and quantified. Quality control (QC) samples were injected every ten samples and assessed throughout the analysis. Inter- and intra-batch coefficients of variation of QC and participant samples, and technical intraclass correlation coefficients were estimated. Passing-Bablok regression of plasma concentrations by CE-MS on serum concentrations by standard clinical chemistry assays was conducted for creatinine and uric acid. RESULTS AND CONCLUSIONS: In QC samples, coefficient of variation was less than 20% for 64 metabolites, and less than 30% for 80 metabolites out of the 94 metabolites. Inter-batch coefficient of variation was less than 20% for 81 metabolites. Estimated technical intraclass correlation coefficient was above 0.75 for 67 metabolites. The slope of Passing-Bablok regression was estimated as 0.97 (95% confidence interval: 0.95, 0.98) for creatinine and 0.95 (0.92, 0.96) for uric acid. Compared to published data from other large cohort measurement platforms, reproducibility of metabolites common to the platforms was similar to or better than in the other studies. These results show that our CE-MS platform is suitable for conducting large-scale epidemiological studies.

Effects of a school-based stroke education program on stroke-related knowledge and behaviour modification-school class based intervention study for elementary school students and parental guardians in a Japanese rural area.

OBJECTIVES: This study aimed to determine the effect of a stroke education programme on elementary school students and their parental guardians in a rural area in Japan that has high stroke mortality. DESIGN: School class based intervention study. SETTING: Eleven public elementary schools in Tochigi Prefecture, Japan. PARTICIPANTS: 268 students aged 11-12 years and 267 parental guardians. INTERVENTIONS: Students received lessons about stroke featuring animated cartoons and were instructed to communicate their knowledge about stroke to their parental guardians using material (comic books) distributed in the lessons. Stroke knowledge (symptoms, risk factors and attitude towards stroke) and behavioural change for risk factors were assessed at baseline, immediately after the programme and at 3 months. We also evaluated behavioural change for risk factors among parental guardians. RESULTS: The percentage of students with all correct answers for stroke symptoms, risk factors and the recommended response to stroke was significantly increased at 3 months P<0.001). We observed a significant increase in the percentage of guardians who chose all correct symptoms (P<0.001: 61.0% vs 85.4%) and risk factors (P<0.001: 41.2% vs 59.9%) at 3 months compared with baseline. The percentage of parental guardians with a high behavioural response to improving risk factors was significantly increased at 3 months compared with baseline (P<0.001). CONCLUSIONS: In a rural population with high stroke mortality, stroke education can improve knowledge about stroke in elementary school students and their parental guardians. ETHICS AND DISSEMINATION: We conducted the intervention as a part of compulsory education; this study was not a clinical trial. This study was approved by the Ethics Committee of the National Cerebral and Cardiovascular Center (M27-026).