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1.  Cardiorespiratory fitness, body mass index, and cancer mortality: a cohort study of Japanese men 
BMC Public Health  2014;14(1):1012.
The aim of this study is to investigate the independent and joint effects of cardiorespiratory fitness (CRF) and body mass index (BMI) on cancer mortality in a low body mass index population.
We evaluated CRF and BMI in relation to cancer mortality in 8760 Japanese men. The median BMI was 22.6 kg/m2 (IQR: 21.0-24.3). The mean follow-up period was more than 20 years. Hazard ratios and 95% CI were obtained using a Cox proportional hazards model while adjusting for several confounding factors.
Using the 2nd tertile of BMI (21.6-23.6 kg/m2) as reference, hazard ratios and 95% CI for the lowest tertile of BMI (18.5-21.5) were 1.26 (0.87–1.81), and 0.92 (0.64–1.34) for the highest tertile (23.7-37.4). Using the lowest tertile of CRF as reference, hazard ratios and 95% CIs for 2nd and highest tertiles of CRF were 0.78 (0.55–1.10) and 0.59 (0.40–0.88). We further calculated hazard ratios according to groups of men cross-tabulated by tertiles of CRF and BMI. Among men in the second tertile of BMI, those belonging to the lowest CRF tertile had a 53% lower risk of cancer mortality compared to those in the lowest CRF tertile (hazard ratio: 0.47, 95% CI: 0.23-0.97). Among those in the highest BMI tertile, the corresponding hazard ratio was 0.54 (0.25-1.17).
These results suggest that high CRF is associated with lower cancer mortality in a Japanese population of men with low average BMI.
PMCID: PMC4190338  PMID: 25261876
Epidemiology; Maximal oxygen uptake; Physical activity; Exercise; Smoking
2.  Workers' load and job-related stress after a reform and work system change in a hospital kitchen in Japan 
Many kitchen work environments are considered to be severe; however, when kitchens are reformed or work systems are changed, the question of how this influences kitchen workers and environments arises. The purpose of this study is to examine whether there was a change in workload and job-related stress for workers after a workplace environment and work system change in a hospital kitchen.
The study design is a pre–post comparison of a case, performed in 2006 and 2008. The air temperature and humidity in the workplace were measured. Regarding workload, work hours, fluid loss, heart rate, and amount of activity [metabolic equivalents of task (METs)] of 7 and 8 male subjects pre- and post-reform, respectively, were measured. Job-related stress was assessed using a self-reporting anonymous questionnaire for 53 and 45 workers pre- and post-system change, respectively.
After the reform and work system change, the kitchen space had increased and air-conditioners had been installed. The workplace environment changes included the introduction of temperature-controlled wagons whose operators were limited to male workers. The kitchen air temperature decreased, so fluid loss in the subjects decreased significantly. However, heart rate and METs in the subjects increased significantly. As for job-related stress, although workplace environment scores improved, male workers’ total job stress score increased.
These results suggest that not only the workplace environment but also the work system influenced the workload and job stress on workers.
PMCID: PMC3590319  PMID: 22791208
Workplace environment; Work load; Job-related stress; Work system; Kitchen
3.  Burn and Cut Injuries Related to Job Stress among Kitchen Workers in Japan 
Industrial Health  2014;52(2):113-120.
To clarify the correlation between kitchen work-related burns and cuts and job stress, a self-administered questionnaire survey was conducted involving 991 kitchen workers among 126 kitchen facilities. The demographics, condition of burns and cuts, job stress with the Brief Job Stress Questionnaire (BJSQ), health condition, and work-related and environmental factors were surveyed. Multiple logistic regression models and trend tests were used according to quartiles (Q1, Q2, Q3, and Q4) of each sub-scale BJSQ. After adjustment for potential confounding variables, burns/cuts were associated with a higher score category (Q4) of job demands (OR: 2.56, 95% CI: 1.10–6.02/OR: 2.72, 95% CI: 1.30–5.69), psychological stress (OR: 4.49, 95% CI: 2.05–9.81/OR: 3.52, 95% CI: 1.84–6.72), and physical stress (OR: 2.41, 95% CI: 1.20–4.98/OR 2.16, 95% CI: 1.16–4.01). The ORs of the burn/cut injures increased from Q1 to Q4 with job demands (p for trend = 0.045/0.003), psychological stress (p for trend<0.001/0.001), and physical stress (p for trend = 0.006/0.005), respectively. These findings suggest that kitchen work-related burns and cuts are more likely to be correlated with job stress, and the higher the job stress score, the higher the frequency of burns and cuts among kitchen workers.
PMCID: PMC4202755  PMID: 24429518
Burns; Cuts; Occupational injuries; Job stress; Kitchen worker
4.  Presence of an interaction between smoking and being overweight increases risks of hypertension, diabetes, and cardiovascular disease in outpatients with mood disorders 
We aimed to evaluate the hypothesis that the presence of an interaction between smoking and being overweight increases the risks of lifestyle-related diseases (hypertension, diabetes mellitus, dyslipidemia, and cardiovascular disease) in outpatients with mood disorders.
In this cross-sectional survey, using data from 213 outpatients with mood disorders (95 men, 118 women), we calculated the adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for each of hypertension, diabetes, dyslipedemia, and cardiovascular disease, using a binary logistic regression model; we then calculated the adjusted OR values for smokers and non-smokers with body mass indexes (BMIs) of <25 or ≥25 kg/m2. Next, we examined the data for the presence of an interaction between smoking and being overweight, using three measures of additive interaction: relative excess risk due to the interaction (RERI), attributable proportion due to the interaction (AP), and the synergy index (S).
Smokers with BMI <25 kg/m2 had a significantly lower risk of hypertension (OR 0.27, 95% CI 0.09–0.81) than non-smokers with BMI <25 kg/m2 (reference group). Compared with the reference group, overweight non-smokers had a significantly higher risk (2.82, 1.34–6.19) of hypertension, and overweight smokers had a higher risk (4.43, 1.28–15.26) of hypertension and very high risks of diabetes (8.24, 2.47–27.42) and cardiovascular disease (13.12, 1.95–88.41). The highest RERI was derived from the relation with cardiovascular disease. The highest AP and S were derived from the relation with type 2 diabetes. There was no interaction of smoking and being overweight with dyslipidemia.
The presence of an interaction between smoking and being overweight exacerbates the risks of hypertension, diabetes, and cardiovascular disease in outpatients with mood disorders.
PMCID: PMC3390563  PMID: 22065307
Mood disorders; Lifestyle-related diseases; Interaction; Smoking; Body mass index
5.  Evaluation of a community intervention program in Japan using Framingham risk score and estimated 10-year coronary heart disease risk as outcome variables: a non-randomized controlled trial 
BMC Public Health  2013;13:219.
Community-based programs are being widely adopted in the struggle to prevent cardiovascular diseases. No study has been conducted in Japan to evaluate the effects of a community-based health promotion program by using the Framingham risk score and 10-year CHD risk as outcome variables. The aim of the present study was to assess the effects of a program involving 6-month intervention and 18-month follow-up using such outcomes.
Participants (n = 1,983, 39.5% women, mean age 63.4 years) were selected for the study in 2008. Of these 1,983, 347 (42.4% women) subjects received the 6-month intervention. The intervention included individual counseling and group sessions, among others. After 18 months, 1,278 participants (intervention group: 238, control group: 1,040) were followed up. Changes in the Framingham risk score and 10-year coronary heart disease (CHD) risk were evaluated. ANCOVA and multiple logistic models adjusted for baseline value, age, sex and intervention times were used.
The results showed that the differences in the Framingham risk score and mean 10-year CHD risk were significant in the intervention group compared with the control group after 6-month follow-up (-0.46 and -1.12, respectively) and were also significant after 18-month follow-up (-0.39 and -0.85, respectively). The proportion of those with intermediate 10-year CHD risk (> = 10%) was significantly lower at 6 months (OR 0.30, 95% CI 0.12-0.74) and at 18 months (OR 0.41, 95% CI 0.19-0.92).
The six-month intervention program effectively decreased estimated 10-year CHD risk and the effects were still present at 18-month follow-up.
Trial registration
UMIN-CTR: UMIN000008163
PMCID: PMC3605303  PMID: 23497156
Coronary disease; Lifestyle; Prevention; Risk factors
6.  Relationship between the Onset of Depression and Stress Response Measured by the Brief Job Stress Questionnaire among Japanese Employees: A Cohort Study 
PLoS ONE  2013;8(2):e56319.
The proportion of Japanese workers experiencing intense worry or stress during working life is in excess of 60%, and the incidence of psychiatric disorders and suicide due to psychological burden from work duties is increasing. To confirm whether the stress response measured by the Brief Job Stress Questionnaire (BJSQ) can identify risk for depression, a cohort study was conducted to evaluate whether the stress response measured by BJSQ was associated with the onset of depression.
A total of 1,810 participants aged 20–70 years in 2005 completed the stress response of the BJSQ and were followed-up until August, 2007 by examining sick pay records. Depression was defined by a description in sick pay records that included “depression” or “depressive symptoms” as a reason for sick leave according to a physician's medical certificate. The participants were divided into quartiles (Ql, Q2, Q3, and Q4) according to the total stress response score of BJSQ at baseline. Furthermore, the participants were divided into a higher score category (Q4) and a lower score category (Q1–Q3). Risk ratios of the stress response of the BJSQ for onset of depression were calculated using a multivariable Cox proportional hazard model.
Among 1,810 participants, 14 developed depression during a mean of 1.8 years of follow-up. The risk ratio was 2.96 (95% confidence interval [CI], 1.04–8.42, p for trend = 0.002) when the higher stress response score category of BJSQ was compared with the low stress response score category for sick leave due to depression. After adjusting for gender, age, marital status, and having children, the risk ratios were similar to no adjustment.
These findings suggest that the stress response measured by the BJSQ can demonstrate risk for the onset of depression.
PMCID: PMC3570457  PMID: 23424656
7.  Long-Term Trends in Cardiorespiratory Fitness and the Incidence of Type 2 Diabetes 
Diabetes Care  2010;33(6):1353-1357.
Whereas single assessments of cardiorespiratory fitness have been shown to predict lower incidence of type 2 diabetes, there are no data on long-term trends in fitness and risk. We investigated the relationship between long-term trends in fitness and the incidence of type 2 diabetes.
A cohort of 4,187 Japanese men free of diabetes completed annual health checkups and fitness tests for estimated maximal oxygen uptake at least four times over 7 years (1979–1985). We modeled the trend in fitness over 7 years for each man using simple linear regression. Men were then divided into quartiles based on the regression coefficient (slope) from the model. During the follow-up period (1985–1999), 274 men developed diabetes. Hazard ratios (HRs) and 95% CIs for the incidence of diabetes were obtained using the Cox proportional hazards model.
Men in the lowest quartile of the distribution decreased in fitness over the 7 years (median slope −1.25 ml/kg/min), whereas men in the highest quartile increased in fitness (median slope 1.33 ml/kg/min). With adjustment for age, initial fitness level, BMI, systolic blood pressure, cigarette smoking, alcohol intake, and a family history of diabetes and use of the lowest quartile, the HRs (95% CI) for the second through fourth quartiles were 0.64 (0.46–0.89), 0.40 (0.27–0.58), and 0.33 (0.21–0.50), respectively (Ptrend < 0.001).
These results indicate that the long-term trend in fitness is a strong predictor of the incidence of type 2 diabetes in Japanese men.
PMCID: PMC2875453  PMID: 20215460
8.  Glycated albumin suppresses glucose-induced insulin secretion by impairing glucose metabolism in rat pancreatic β-cells 
Glycated albumin (GA) is an Amadori product used as a marker of hyperglycemia. In this study, we investigated the effect of GA on insulin secretion from pancreatic β cells.
Islets were collected from male Wistar rats by collagenase digestion. Insulin secretion in the presence of non-glycated human albumin (HA) and GA was measured under three different glucose concentrations, 3 mM (G3), 7 mM (G7), and 15 mM (G15), with various stimulators. Insulin secretion was measured with antagonists of inducible nitric oxide synthetase (iNOS), and the expression of iNOS-mRNA was investigated by real-time PCR.
Insulin secretion in the presence of HA and GA was 20.9 ± 3.9 and 21.6 ± 5.5 μU/3 islets/h for G3 (P = 0.920), and 154 ± 9.3 and 126.1 ± 7.3 μU/3 islets/h (P = 0.046), for G15, respectively. High extracellular potassium and 10 mM tolbutamide abrogated the inhibition of insulin secretion by GA. Glyceraldehyde, dihydroxyacetone, methylpyruvate, GLP-1, and forskolin, an activator of adenylate cyclase, did not abrogate the inhibition. Real-time PCR showed that GA did not induce iNOS-mRNA expression. Furthermore, an inhibitor of nitric oxide synthetase, aminoguanidine, and NG-nitro-L-arginine methyl ester did not abrogate the inhibition of insulin secretion.
GA suppresses glucose-induced insulin secretion from rat pancreatic β-cells through impairment of intracellular glucose metabolism.
PMCID: PMC3079599  PMID: 21470398
9.  Sense of coherence as a predictor of onset of depression among Japanese workers: a cohort study 
BMC Public Health  2011;11:205.
The ability to predict future onset of depression is required for primary prevention of depression. Many cross-sectional studies have reported a correlation between sense of coherence (SOC) and the presence of depressive symptoms. However, it is unclear whether SOC can predict future onset of depression. Therefore, whether measures to prevent onset of depression are needed in for persons with low SOC is uncertain. Thus, the aim of this cohort study was to determine whether SOC could predict onset of depression and to assess the need for measures to prevent onset of depression for persons with low SOC.
A total of 1854 Japanese workers aged 20-70 years in 2005 who completed a sense of coherence (SOC) questionnaire were followed-up until August 2007 using their sick-pay records with medical certificates. Depression was defined as a description of "depression" or "depressive" as a reason for sick leave on the medical certificates. The day of incidence of depression was defined as the first day of the sick leave. Risk ratios of SOC for onset of depression were calculated using a multivariate Cox proportional hazards model.
Of the 1854 participants, 14 developed depression during a mean of 1.8 years of follow-up. After adjustment for gender and age, the risk ratio of high SOC compared with low SOC for sick leave from depression was 0.18 (95% confidence interval [CI], 0.04 to 0.79). The area under the receiver operating characteristic curve of SOC was 0.70 (95% CI, 0.58 to 0.82).
The SOC may be able to predict onset of depression in Japanese workers. Measures to prevent onset of depression for persons with low SOC might be required in Japanese workplaces. Thus, SOC could be useful for identifying persons at high risk for future depression.
PMCID: PMC3078884  PMID: 21453548
10.  Relationship Between Obesity and Incident Diabetes in Middle-Aged and Older Japanese Adults: The Ibaraki Prefectural Health Study 
Mayo Clinic Proceedings  2010;85(1):36-40.
OBJECTIVE: To investigate the age-specific relationship between body mass index (BMI) and risk of diabetes in a Japanese general population.
PARTICIPANTS AND METHODS: A cohort of Japanese men (N=19,926) and women (N=41,489) (aged 40-79 years) who under went community-based health checkups in 1993 and were free of diabetes was followed up by annual examinations with measurement of blood glucose concentrations until the end of 2006. Incident diabetes mellitus was defined as a blood glucose concentration of 126 mg/dL or greater under fasting conditions, 200 mg/dL or greater under nonfasting conditions, or diabetic medication use at baseline. Hazard ratios (HRs) for diabetes according to BMI were estimated using a Cox proportional hazard model. The model was adjusted for possible confounding variables.
RESULTS: A total of 4429 participants (7.2%) developed diabetes (2065 men and 2364 women) during a mean follow-up of 5.5 years. Compared with those with a BMI of less than 25.0, the multivariate HRs for diabetes among participants with a BMI of 30.0 or greater were 1.40 (95% confidence interval [CI], 0.89-2.20) for men aged 40 to 59 years and 1.26 (95% CI, 0.81-1.96) for men aged 60 to 79 years (P=.002 for interaction). The HRs were 2.50 (95% CI, 2.01-3.11) for women aged 40 to 59 years and 1.80 (95% CI, 1.41-2.30) for women aged 60 to 79 years (P=.04 for interaction).
CONCLUSION: The effect of obesity on the risk of diabetes is greater for middle-aged than for older adults.
In this investigation of the age-specific relationship between body mass index and risk of diabetes in 61,415 adults, 4429 individuals developed diabetes during a mean follow-up of 5.5 years. The effect of obesity on the risk of diabetes is greater for middle-aged adults than for older adults.
PMCID: PMC2800296  PMID: 20042559
11.  Age-Stratified Analysis of the Impact of Hypertension on National Health Insurance Medical Expenditures in Ibaraki, Japan 
Journal of Epidemiology  2010;20(3):192-196.
This retrospective cohort study examined the sex- and age-specific impact of hypertension on medical expenditures.
In 2006, we analyzed the medical expenditure records of 42 426 Japanese National Health Insurance beneficiaries (16 169 men, 26 257 women) who lived in Ibaraki, Japan, were aged 40 to 69 years, and underwent health checkups in 2002. Blood pressure was classified into 4 categories according to the criteria outlined in the seventh report of the Joint National Committee.
The difference in median total expenditure between the hypertension categories and the normotension category was 119 585 yen (140 360 yen vs 20 775 yen) for men aged 40 to 54 years, 126 160 yen (204 070 yen vs 77 910 yen) for men aged 55 to 69 years, 125 495 yen (158 025 yen vs 32 530 yen) for women aged 40 to 54 years, and 122 370 yen (208 700 yen vs 86 330 yen) for women aged 55 to 69 years. The median total and outpatient medical expenditures markedly differed between patients with stage 1 hypertension and stage 2 hypertension (which included people on antihypertensive medication) in both sexes and all age subgroups. The median total and outpatient medical expenditures were higher among women than among men in all blood pressure categories.
The impact of hypertension on medical expenditures was similar in all age groups. Therefore, from the perspective of medical economics, prevention of the onset of hypertension seems equally important for all age subgroups.
PMCID: PMC3900840  PMID: 20208401
hypertension; medical expenditure; health expenditure; age groups
12.  Activities of occupational physicians for occupational health services in small-scale enterprises in Japan and in the Netherlands 
Occupational health service (OHS) for small-scale enterprises (SSEs) is still limited in many countries. Both Japan and the Netherlands have universal OHS systems for all employees. The objective of this survey was to examine the activities of occupational physicians (OPs) in the two countries for SSEs and to investigate their proposals for the improvement of service.
Questionnaires on types and sizes of the industries they serve, allocation of service hours (current and desired), sources of information for occupational health activities etc. were mailed in 2006 to 461 and 335 Japanese and Dutch OPs, respectively, who have served in small- and medium-scale enterprises. In practice, 107 Japanese (23%) and 106 Dutch physicians (32%) replied, respectively.
Results and Conclusions
Total service time per month was longer for OPs in the Netherlands than OPs in Japan. Japanese OPs spent more hours for health and safety meetings, worksite rounds, and prevention of overwork-induced ill health (14–16% each). Dutch OPs used much more hours for the guidance of absent workers (48%). Thus, service conditions were not the same for OPs in the two countries. Nevertheless, both groups of OPs unanimously considered that employers are the key persons for the improvement of OHS especially in SSEs and their education is important for better OHS. The conclusions should be taken as preliminary, however, due to study limitations including low response rates in both groups of physicians.
PMCID: PMC2836247  PMID: 20130904
Education; Employer; Occupational physician; Occupational health services; Small-scale enterprises
13.  The relationship between the frequency of the common cold and the activities of natural killer cells 
We investigated the relationship between the frequency of the common cold and the conditions of the body’s immune system among members of a generally healthy population. Self-reporting questionnaires on the frequency of the common cold and on fatigue and stress conditions were administered to a total of 67 healthy individuals aged 22 to 50. The activities of natural killer (NK) cells, which were determined by Eu3+-DTPA release assay, and of NK cell members in the peripheral blood of the subjects were phenotypically (CD3 CD16+ CD56+) analyzed with three-color flow cytometry. The results showed that the frequency of the common cold was significantly correlated with NK activity and NK subset (CD3-CD16+ CD56+) frequency (r=—0.34 and—0.47 respectively, P<0.01). After adjusting for age, the mean NK subset (CD3-CD16+CD56) significandy differed (F=3.384, P<0.05) among the four frequency groups for the common cold, and the frequencies of the common cold were significandy different among the four stress/fatigue groups (F=8.016, P<0.001) for the males, as evaluated by ANCOVA. These results indicate that conditions of high stress and fatigue may increase the chance of catching the common cold due to a decrease in activities of NK cells.
PMCID: PMC2723598  PMID: 21432487
NK activity; NK subset; frequency of the common cold; fatigue; stress
14.  Evaluation of a diabetes patient education program consisting of a three-day hospitalization and a six-month follow-up by telephone counseling for mild type 2 diabetes and IGT 
The purpose of this study was to evaluate the efficacy and feasibility of a newly developed diabetes patient education program consisting of a three-day hospitalization and a six-month follow-up by telephone counseling for patients with mild type 2 diabetes or impaired glucose tolerance (IGT) by a randomized controlled trial (RCT) method. Fifty-two patients with mild type 2 diabetes or IGT (HbAlc<8) were randomly assigned to either an intervention group or a control group. The current care was continued for the control group and the new education program was provided in addition to the current care for the intervention group. Changes in weight, blood glucose in a 75g-oral glucose tolerance test (75g-OGTT), and HbAlc were measured in June 1997 as baseline data and again in Dec. 1997. Scores for knowledge of diabetes, dietary habits, physical activity, health practice index, diabetes quality of life (DQOL), and self-efficacy were also obtained. After six months, the intervention group showed a statistically significant weight loss and blood glucose reduction in the 75g-OGTT test, but the control group did not. A significant improvement in lifestyle was observed in the intervention group, especially in terms of dietary habits and physical activity. The knowledge test scores increased in both groups. There were no significant differences in HbAlc, DQOL, or self-efficacy between the two groups. The results of this study show that the combination of a three-day hospitalization and a six-month follow-up by telephone counseling is effective in metabolic control and improvement of lifestyle for patients with mild type 2 diabetes or IGT. The reasons for the effectiveness were considered to be that l)changes in lifestyle were based on autonomous decision-making; 2)regular, consistent counseling was provided by the nurse in charge of each patient; 3)extended follow-up is more effective than initial education in preventing a rebound of weight or metabolic control.
PMCID: PMC2723521  PMID: 21432184
randomized controlled trial; type 2 diabetes; IGT; patient education; telephone counseling

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