Yoko Wakayama

Effect of phytoncide from trees on human natural killer cell function.

We previously reported that the forest environment enhanced human natural killer (NK) cell activity, the number of NK cells, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after trips to forests both in male and female subjects. To explore the factors in the forest environment that activated human NK cells, in the present study we investigate the effect of essential oils from trees on human immune function in twelve healthy male subjects, age 37–60 years, who stayed at an urban hotel for 3 nights from 7.00p.m. to 8.00a.m. Aromatic volatile substances (phytoncides) were produced by vaporizing Chamaecyparis obtusa (hinoki cypress) stem oil with a humidifier in the hotel room during the night stay. Blood samples were taken on the last day and urine samples were analysed every day during the stay. NK activity, the percentages of NK and T cells, and granulysin, perforin, granzyme A/B-expressing lymphocytes in blood, and the concentrations of adrenaline and noradrenaline in urine were measured. Similar control measurements were made before the stay on a normal working day. The concentrations of phytoncides in the hotel room air were measured. Phytoncide exposure significantly increased NK activity and the percentages of NK, perforin, granulysin, and granzyme A/B-expressing cells, and significantly decreased the percentage of T cells, and the concentrations of adrenaline and noradrenaline in urine. Phytoncides, such as α-pinene and β-pinene, were detected in the hotel room air. These findings indicate that phytoncide exposure and decreased stress hormone levels may partially contribute to increased NK activity.

Association of smoking status, insulin resistance, body mass index, and metabolic syndrome in workers: A 1-year follow-up study

SUMMARY OBJECTIVE We performed a 1-year follow-up study to determine the effects of smoking status and insulin resistance on the prevalence of metabolic syndrome. METHODS This study included 2136 workers without metabolic syndrome at baseline who were followed for 1 year. The subjects were divided into four categories of smoking and work history, respectively. Insulin resistance was evaluated using the homeostasis model assessment for insulin resistance (HOMA-R). RESULTS The prevalence of metabolic syndrome after 1 year was 6.3%. A multiple logistic regression analysis showed that the current smokers category versus the non-smokers category, a 0.1-point increase in the HOMA-R score, a 1-point increase in the uric acid level, age, and body mass index were significantly correlated with increased odds for metabolic syndrome, yielding odds ratios (95% confidence intervals) of 1.61 (1.09-2.39), 1.14 (1.04-1.25), 1.31 (1.12-1.54), and 1.06 (1.03-1.09), and 1.23 (1.15-1.31), respectively. CONCLUSIONS Current smoking, insulin resistance, uric acid level, and age contributed positively to the prevalence of metabolic syndrome. In contrast, smoking cessation within 1 year and work history did not contribute to metabolic syndrome.

Relationship among lifestyles, aging and psychological wellbeing using the General Health Questionnaire 12-items in Japanese working men

Introduction. The relationship among lifestyle, aging and psychological wellbeing was evaluated in Japanese working men. Methods. Self-administered questionnaire on six lifestyle factors and the General Health Questionnaire 12-item version (GHQ12) were administered to 3306 male workers. Health practice index (HPI) was calculated as a desirable lifestyle score by summing up each binary lifestyle score (0, 1), ranging from 0 to 6. To check validity of the study outcome, the authors repeated twice with 1 year interval. HPI was categorised into three groups by the score of 0–2, 3–4 and 5–6. Results. The number of subjects categorised by HPI was 532, 1967 and 807, respectively. The mean value of GHQ12 significantly decreased as the HPI increased by adjusting age. Multiple regression analysis was conducted to predict GHQ12 by six lifestyle scores, and age, sleep, night snacking and exercise were significantly related to GHQ12. Multiple logistic regression analysis was conducted and age in 50s, two-shift work, sleep, night snacking and exercise were significantly associated with GHQ12. Conclusion. Although cause–effect relationship cannot make clear, some of desirable health practices and aging were closely related to psychological wellbeing judged by GHQ12.

A cross-sectional study on the shift work and metabolic syndrome in Japanese male workers

Introduction. Shift work has been reported to be associated with an increase in the metabolic syndrome (MetS). To clarify the association between the type of shift work and the risk of MetS, a cross-sectional field survey was conducted after adjusting for age and lifestyle factors. Methods. The subjects were 3007 Japanese males, aged 34–64 years old, who were employees (1700 day and 1307 shift workers) of a car-manufacturing company. The standard Japanese criteria for the diagnosis of MetS was used. Age, smoking habit, drinking habit, sleeping habit and exercise habit were used as the independent variables. Results. The prevalence of MetS in the day workers, two-shift workers, and three-shift workers were 13.8% (234/1700), 10.7% (120/1125) and 17.6% (32/182), respectively. There was a significant difference in the prevalence between the two-shift workers and the day workers. Estimation of the odds ratios (95% confidence intervals) of age, two-shift work and habitual exercise for MetS were 1.03 (1.01–1.04), 0.77 (0.61–0.98) and 0.64 (0.51–0.81), respectively. Conclusion. Two-shift work was associated with lower risk of MetS, which is not in accordance with past reports. This finding should therefore be re-analysed, including investigation of the job content in each group.

Biological markers, lifestyles and metabolic syndrome in workers.

OBJECTIVE The association between metabolic syndrome (MetS) and biological inflammatory or anti-coagulant markers were clarified in combination with lifestyle factors. PATIENTS AND METHODS The target subjects were 5102 working men without metabolic diseases, aged 30-60 years old. The authors measured the serum levels of high-sensitivity C-reactive protein (CRP), uric acid and plasma fibrinogen as potential key biomarkers of MetS. RESULTS Mean values of uric acid, log-transformed serum CRP and plasma fibrinogen increased significantly as the number of components of MetS increased after adjustment for age. Multivariate analysis revealed significant associations between the presence of MetS and age, habitual exercise, not current smoking, the log-transformed value of serum CRP and serum uric acid, with odds ratios (ORs) of 1.03 (95% confidence interval (CI): 1.02-1.04; p<0.001), 0.77 (95% CI: 0.65-0.90; p<0.01), 0.82 (95% CI: 0.70-0.96; p<0.05), 3.2 (95% CI: 2.6-3.9; p<0.001) and 1.5 (95% CI: 1.4-1.6; p<0.001), respectively for the presence of MetS. CONCLUSION Elevated serum level of CRP, uric acid, not habitual exercise and current smoking were associated with MetS in this cross-sectional study.

Optimal cut-off levels of body mass index and waist circumference in relation to each component of metabolic syndrome (MetS) and the number of MetS component

AIMS There is an ethnic difference of obesity index to diagnose metabolic syndrome. The authors explored the optimal cut-off levels for body mass index (BMI) and waist circumference (WC) in relation to each component of metabolic syndrome. MATERIALS AND METHODS Receiver operating characteristics (ROC) analysis was used to determine the optimal cut-off levels for each component of metabolic syndrome. This study included 4572 workers aged 42.5±9.9 years. RESULTS The optimal BMI cut-off values for diabetes mellitus, hypertension or dyslipidemia varied from 23.0 to 24.3 kg/m(2). As for WC, the optimal cut-off values varied from 83.0 to 83.7 cm. The optimal BMI cut-off values relating with one to three components of metabolic syndrome varied from 23.2 to 25.3 kg/m(2). As for WC, the optimal cut-off values varied from 83.0 to 85.0 cm. Pair-wise comparison of ROC curves showed that WC has an advantage in relation to metabolic syndrome and its components compared with BMI. By logistic regression analysis, odds ratios of obesity indices for hypertension, dyslipidemia or the number of metabolic component were all significantly increased. As for diabetes mellitus, odds ratios of BMI ≥25 and WC ≥85 significantly increased, respectively. CONCLUSIONS Japanese criteria of obesity in metabolic syndrome in man may be appropriate for diabetes mellitus. Ethnic difference in criteria of obesity in Asian metabolic syndrome exists, and mutual comparisons in the prevalence of metabolic syndrome have a difficulty to conduct.

Depressive state and subsequent weight gain in workers: A 4-year follow-up study

OBJECTIVE It has been suggested that the presence of a depressive state is a predictor of increase of the body weight. However, to precisely understand the nature of this relationship, the data should be controlled for other factors that can also be associated with weight gain. METHODS AND PARTICIPANTS To test the hypothesis that the presence of a depressive state is associated with future weight gain, a 4-year prospective occupation-based cohort study was conducted in male adult workers (N=1730) at a railway company. Following the initial screening, follow-up information was obtained via a legally required annual health examination. The presence of a depressive state was identified using the Zung Self-Rating Depression Scale (SDS). The weight of each participant was measured to the nearest kilogram. Multiple logistic regression analysis was used to test the association between the depressive state and a weight gain of 4 kg or more over the 4-year study period after controlling for potentially confounding variables such as the age, smoking status, alcohol intake status, and physical activity. RESULTS A weight gain of 4 kg or more over the 4-year study period was significantly associated with the depressive state, even after controlling for confounding variables (p< 0.05). Short-term longitudinal analysis also revealed an association between the depressive state and subsequent increase of the body weight. CONCLUSION Since the depressive state was demonstrated to be an important risk factor for increase of the body weight, further research on depression should be conducted with a view to providing effective health education.

Serum insulin is significantly related to components of the metabolic syndrome in Japanese working men.

J Clin Hypertens (Greenwich).

Increase in the prevalence of metabolic syndrome among workers according to age

Introduction. Statistical information regarding the prevalence of metabolic syndrome among a wide age range of workers is insufficient. Methods. A total of 4278 men between the ages of 20 and 59 years participated in the study. Metabolic syndrome was diagnosed according to the International Diabetes Federation (IDF) and the National Cholesterol Education Program (NCEP) III criteria. Results. Overall, the prevalences of metabolic syndrome according to the IDF and NCEPIII criteria were 13.6% and 14.8%, respectively. The prevalence of metabolic syndrome according to the IDF (NCEPIII) criteria among workers in their 20s, 30s, 40s, and 50s were 4.8% (6.1%), 9.9% (12.2%), 18.4% (21.6%) and 25.8% (34.0%), respectively. A plot of the prevalence of metabolic syndrome according to the NCEPIII criteria versus age had a steep gradient and increased sharply for men in their 50s. In contrast, a plot of the prevalence of metabolic syndrome according to the IDF criteria versus age increased in a linear manner. Conclusion. The prevalence of metabolic syndrome increased among workers according to age, but the increasing trend and the absolute prevalence of metabolic syndrome differed according to the two sets of diagnostic criteria used in this study.

Serum insulin is significantly related to components of the metabolic syndrome in Japanese working women

BACKGROUND The aim of this study was to examine the association between serum insulin levels and components of the metabolic syndrome (MetS) in working women. METHODS The target subjects were 141 working women. Serum triglyceride, HDL cholesterol, uric acid, plasma insulin and plasma glucose were measured in addition to waist circumference and blood pressure. RESULTS MetS was diagnosed based on the modified criteria of the International Diabetes Federation, and was present in 7.1% (10/141) of the study subjects. Stepwise multiple regression analysis showed that some components of MetS were significantly associated with log-transformed values of the serum insulin. The standardized regression coefficient for the waist circumference, high density lipoprotein cholesterol, systolic blood pressure and age were 0.238, -0.333, 0.309 and -0.156, respectively. CONCLUSIONS A statistically significant relationship existed between the components of MetS and the serum insulin levels in working women.