Jiro Takaki

Oxidative stress biomarkers and lifestyles in Japanese healthy people

The urinary concentrations of 8-isoprostane and 8-hydroxy-2’-deoxyguanosine (8-OHdG), which are biomarkers of oxidative stress, were measured in 677 Japanese people without any diseases, and their correlations with lifestyle facotrs, lifestyle-related blood biochemical parameters, and dietary intake of antioxidative vitamins were investigated. The mean urinary concentration of 8-isoprostane and 8-OHdG was 0.58 ng/mg creatinine and 8.43 ng/mg creatinine, respectively. Mean urinary 8-isoprostane was significantly different in terms of age, gender, smoking and alcohol consumption but not different in terms of body mass index (BMI) and exercise. By multiple regression analysis, urinary 8-isoprostane was significantly influenced by smoking and age. On the other hand, mean urinary 8-OHdG showed differences only by age group. Multiple regression analysis revealed that urinary 8-OHdG was significantly influenced by age, smoking, body weight, levels of high-sensitivity C-reactive protein (Hs-CRP) and low density lipoprotein-cholesterol in females, although it was significantly influenced by body weight in males. The present study shows that urinary 8-isoprostane is associated with lipid peroxidation related-lifestyles such as smoking, and urinary 8-OHdG is associated with arteriosclerosis related-factors such as Hs-CRP. Our findings suggest that 8-isoprostane and 8-OHdG appear to be prospective biomarkers for early prediction of lifestyle related-disease risk at the population level.

Workplace Bullying could Play Important Roles in the Relationships between Job Strain and Symptoms of Depression and Sleep Disturbance

Workplace Bullying could Play Important Roles in the Relationships between Job Strain and Symptoms of Depression and Sleep Disturbance: Jiro Takaki, et al. Department of Public Health, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences

Effect of sports activity on bone mineral density in wheelchair athletes

The present study carried out a measurement of body composition and a nutrition survey, targeting 28 male wheelchair athletes and comparing them with 25 male physically able healthy athletes as the controls. The DXA method was used to measure bone mineral density (BMD), percentage of body fat (% body fat), and lean body mass (LBM). Possible factors affecting the BMD of the wheelchair athletes with spinal injuries were analyzed including age, body part, type of sport, area of injury, length of injury, and the length of time it took before restarting sports activity after injury. BMD in the arms, body trunk, legs, and entire body was measured. There were no significant differences in the BMD of the wheelchair athletes by age group (from 20 to 29, from 30 to 39, and 40 years and older), by sports (basketball, track and field, and tennis), and by area of injury (high and low paraplegia). BMD in the legs (r = −0.549, P < 0.01), body trunk (r = −0.414, P < 0.05), and entire body (r = −0.452, P < 0.05) of the wheelchair athletes was negatively correlated with the period since injury; however, no such a relationship was observed in the arms. In addition, the multiple regression analysis for BMD of each body region showed that the earlier the wheelchair athletes restarted sports after injury, the higher values the BMD of legs (r = −0.467, P < 0.05), body trunk (r = −0.469, P < 0.05), and entire body (r = −0.488, P < 0.05), independent of age and sports. The leg BMD of the wheelchair athletes was lower than that of the physically able athletes, with a BMD 76.5% of the controls. The present study suggests that restarting sports activity in a timely manner after treatment and rehabilitation for the injury is useful in preventing loss of BMD in wheelchair athletes and ultimately improving their quality of life.

Health impact of disaster‐related stress on pregnant women living in the affected area of the Noto Peninsula earthquake in Japan

Aims:  The present study assessed the health impact of stress on women who were pregnant during, or immediately after, a major earthquake and were living in the disaster area. Inherent resistance against the stress induced by the earthquake was also assessed.

Plasma 3-nitrotyrosine, urinary 8-isoprostane and 8-OHdG among healthy Japanese people

To examine the relation between lifestyle factors and oxidative stress biomarkers, this study analysed plasma 3-nitrotyrosine (3-NT), urinary 8-isoprostane and 8-hydroxy-2’- deoxyguanosine (8-OHdG) of 323 healthy Japanese without any disease. Plasma 3-NT was significantly increased by excessive exercise (p=0.010), but it was not significantly different in terms of sex, age (< 40, ≧40), BMI (<18.5, 18.5–24.9, ≧25.0), smoking (non-smokers, smokers) and alcohol drinking per week (non-drinkers, <10 units, ≧10 units). Urinary 8-isoprostane was significantly associated with alcohol drinking (p <0.01) and sex (p <0.01), although it had no significant relevance to age and exercise. Moreover, urinary 8-OHdG was positively associated with age (p <0.05) and negatively associated with BMI (p <0.05) and fasting insulin (p <0.001). However, it was not related with sex, smoking, alcohol drinking and exercise. In conclusion, the present results suggest that 3-NT, 8-isoprostane and 8-OHdG seem to be useful biomarkers for early prediction of lifestyle-related disease risk at the population level.

C-reactive protein is associated with cigarette smoking-induced hyperfiltration and proteinuria in an apparently healthy population

Although cigarette smoking is known to be an important risk factor for renal disease, the mechanism by which smoking induces progressive renal disease in a healthy population has not been established. We hypothesized that oxidative stress (measured as 8-iso-prostaglandin F2α, 8-iso-PGF2a), inflammation (highly sensitive C-reactive protein (CRP), hs-CRP) and nitric oxide may be associated with an alteration in the estimated glomerular filtration rate (eGFR) and proteinuria in otherwise healthy smokers. A total of 649 eligible subjects were classified according to their smoking status. Plasma NOx was measured using ozone-based chemiluminescence, urinary 8-iso-PGF2a was measured using enzyme immunoassay and serum hs-CRP was measured using a latex aggregation nephelometry method. The levels of 8-iso-PGF2a and hs-CRP increased in current smokers (P=0.001 and P=0.029, respectively), although there was not an increase in the NOx level. The prevalence of a high eGFR increased in light smokers (odds ratio (OR) 1.15 (95% confidence interval (CI), 0.61–2.17)) and heavy smokers (OR 2.33 (95% CI, 1.06–5.10)) when compared with non- and past smokers (P for trend=0.024). The multivariable-adjusted mean values of the eGFR in current smokers, reported from the lowest to the highest quintiles of hs-CRP levels, were 82.1, 85.1, 86.4 and 88.5 ml per min per 1.73 m2 (P for trend=0.027). The mean values of proteinuria were 28.6, 34.6, 37.2 and 39.5 mg g−1 creatinine (P for trend=0.003). The correlation coefficient between hs-CRP and eGFR was increased significantly (P=0.03) across non- (r=0.03), past (r=−0.17), light (r=0.13) and heavy smokers (r=0.31). In conclusion, cigarette smoking is a risk factor for renal function alteration in healthy smokers and is characterized by a high eGFR and a high urinary protein associated with an increase in the hs-CRP. This finding suggests that hs-CRP may help mediate the alteration of renal function in smokers.

Assessment of workplace bullying and harassment: Reliability and validity of a Japanese version of the negative acts questionnaire

Assessment of Workplace Bullying and Harassment: Reliability and Validity of a Japanese Version of the Negative Acts Questionnaire: Jiro Takaki, et al. Department of Public Health, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences

Associations of workplace bullying and harassment with pain

The aim of this study was to investigate associations of workplace bullying and harassment with headache, stiffness of the neck or shoulders, lumbago, and pain of two or more joints. The subjects in this cross-sectional study were recruited from workers (n = 1,913) at 35 healthcare or welfare facilities in Japan. Because of non-participation or missing data, the number of subjects included in the analysis varied (response rate ≥ 77.1%). Workplace bullying and harassment were assessed using the Negative Acts Questionnaire. Depression was assessed using the Brief Job Stress Questionnaire. The frequency of pain experienced by workers in the previous month was evaluated using a four-point scale. Many of the associations of person-related bullying, work-related bullying, and sexual harassment with headache, stiffness of the neck or shoulders, lumbago, and pain of two or more joints were positive and significant (p < 0.05). Even after adjustment for depression, some of the associations remained significant (p < 0.05). For example, changes in the prevalence ratio for headache associated with a 1-point increase in the work-related bullying score were 1.05 (95% confidence interval (CI) 1.01 to 1.09) in men and 1.03 (95% CI 1.01 to 1.05) in women after adjustment for age, marital status, employment status, work shift, and depression.

Interactive Effects of Job Stress and Body Mass Index on Over-eating

Interactive Effects of Job Stress and Body Mass Index on Over‐eating: Jiro Takaki, et al. Department of Public Health, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences

Possible Health-protecting Effects of Feeling Useful to Others on Symptoms of Depression and Sleep Disturbance in the Workplace

Possible Health‐protecting Effects of Feeling Useful to Others on Symptoms of Depression and Sleep Disturbance in the Workplace: Jiro Takaki, et al. Department of Public Health, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences