Chromium compounds are carcinogenic to the human lung, although the detailed biochemical mechanism is still unclear. To understand the carcinogenic mechanism in cells exposed to low level hexavalent chromium, we measured the generation of reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine (8-OH-dG), the transcription of hogg1, which encodes an 8-OH-dG repair protein, and NF-κB activation levels in the A549 human lung epithelial cell line after exposure to Cr (VI) at concentrations of 12.5 to 800 M. In A549 cells, ROS levels and DNA binding by NF-κB increased in proportion to the concentration of Cr (VI). These increases were diminished by pretreatment with catalase, superoxide dismutase, or D-mannitol, but the levels of 8-OH-dG and expression of hogg1 did not change significantly with Cr (VI) exposure. These results suggest that the induction of ROS and the activation of NF-κB are important in the carcinogenic mechanism of Cr (VI), but it is unlikely that Cr (VI) concentrations below 800 M increase 8-OH-dG levels or the expression of hogg1.

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We have previously demonstrated that a sense of coherence (SOC), a candidate for a mediating stress factor, is involved in natural killer cell activity (NKCA) reduced in smokers, whereas the relationship among exercise, NKCA and SOC is unclear. To clarify the effects of exercise on SOC and NKCA, we examined the changes in SOC and NKCA before and after health education to encourage exercise. Of one-hundred and one male office workers who received the health education for one year, 27 improved, 65 were unchanged and 9 had deteriorated exercise habits. The repeated measures analysis of variance showed that SOC in workers with improvement in the exercise habit were increased more significantly by the health education than those in workers without improvement (p<0.05). Although the change in NKCA produced by health education was recognized to be significantly different in those who had never smoked from that in current smokers (p<0.05), multiple regression analysis demonstrated that improvement in health practice significantly contributed to increases in both SOC (p<0.01) and NKCA (p<0.05) in never smokers, independently of other psychological factors. These results suggest that subjects with improvement in exercise enhance NKCA through increased SOC in never smokers.

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Self-perceived health and fitness are epidemiological predictors of subsequent mortality and/or functional limitation. The present study was designed to analyze which lifestyle factors contribute to good status of self-perceived health and fitness in middle-aged male employees. Participants (n=401) aged 50-59 were assessed as to the status of self-perceived health and fitness, and various lifestyle factors including nutrition, smoking, drinking, physical activity, psychological stress, sleeping and relaxation. Logistic regression analysis revealed that among the lifestyle factors surveyed in the present study, doing exercise/sports at a medium level (either ≥4.5METs/1-2 times per week or <4.5METs/≥3-4 times per week) of physical activity index (PAI) was the only predictor of good self-perceived health. Similarly, doing exercise/sports at or above the medium level of PAI was identified as the only independent predictor of good self-perceived fitness. In addition, maintaining the habit of doing exercise/sports at or above the medium level of PAI throughout the year, and having this habit through the 4 th and 5th decades of life or starting to have it from the age of 50 through 59 were important to obtain a good status of self-perceived health and fitness. These findings suggest that leisure time physical activity level is a determinant of good health and fitness in the middle-aged male employees in the present study.

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The relationships between alcohol consumption, serum gamma-glutamyltransferase (GGT) levels, and the prevalence of major coronary risk factors were analyzed crosssectionally in 2,399 male and 1,402 female middle-aged workers, to clarify the effects of moderate alcohol consumption on the development of the metabolic syndrome. Male moderate drinkers, consuming less than 60 ml of alcohol per day, had a lower prevalence of upper body obesity and low serum HDL-cholesterolemia (LHDLC) in comparison with nondrinkers, but not of hypertension, impaired glucose tolerance or hypertriglyceridemia (HTG). In women, alcohol consumption did not show any significant associations with the coronary risk factors. Men with an elevated serum GGT (EGGT) of 40 U/l or above had a significantly higher odds ratio for all the coronary risk factors as compared with those with normal GGT, even after adjusting for alcohol consumption, together with age, body mass index, cigarette consumption and physical activity. Women with an EGGT of 25 U/l or above had similar findings, although significance was found only in HTG. Nearly 80% and 55% of the appearance of EGGT in men and women were attributable to alcohol consumption, and 20% and 10% of the male and female moderate drinkers had EGGT. These results suggest that even moderate alcohol consumption will increase coronary risk factors characteristic of the metabolic syndrome in drinkers who have an increase in serum GGT. Further studies are required to confirm the causal association between alcohol consumption, increase in serum GGT and development of the metabolic syndrome.

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This study was performed to determine whether there was any relationship between cold exposure and hypertension, and to evaluate risk factors affecting hypertension in cold-exposed workers. In 11 refrigeration industries, 68 male workers working in cold areas more than once per day were selected as the cold-exposed group, and 68 workers not exposed to cold were selected as the control group. The questionnaire survey, clinical and laboratory tests were performed. Systolic and diastolic blood pressures were significantly higher in the cold-exposed group, and body core temperature was significantly lower in the cold-exposed group (p<0.05). In logistic regression analysis, age, cold exposure severity and milk intake were significant variables affecting hypertension in cold-exposed workers, whose odd ratios were 5.204 (95% CI 1.440-18.812), 2.674 (95% CI 1.080-6.618), and 0.364 (95% CI 0.141-0.942), respectively. Cold exposure was a risk factor for hypertension, and risk factors affecting hypertension in cold exposed workers were age, cold exposure severity, and milk intake. Therefore, cold exposed workers should minimize cold exposure time as much as possible, and ingest foods containing calcium such as milk. In particular, old workers working in cold areas should check their blood pressure and electrocardiogram periodically.

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Intratracheal instillation studies have shown that exposure to silicon carbide whisker (SiCW), an asbestos substitute, produces pulmonary fibrotic changes, suggesting that SICW might have a fibrogenic potential. It is thought that surfactant protein is a good biomarker of lung injury and pulmonary fibrotic activity. In order to explore whether or not surfactant protein is associated with lung disorder through exposure to SiCW, we examined the expression of SP-A, SP-C and thyroid transcription factor-1 (TTF-1), a common transcription factor of SP-A and SP-C mRNA in lungs exposed to SiCW. Male Wistar rats were administered 2 mg or 10 mg of SiCW suspended in saline by a single intratracheal instillation, and were sacrificed at 3 d, 1 wk, 1 month, 3 months and 6 months after the intratracheal instillation. RNA was subsequently extracted from the lungs, and expression of SP-A, SP-C and TTF-1 mRNA from the lungs was observed by reverse transcription-polymerase chain reaction (RT-PCR). Exposure to 2 mg of SiCW showed a decrease in mRNA of SP-A and TTF-1 at 6 months, but exposure to 10 mg of SiCW showed decreased levels of SP-A and TTF-1 mRNA at 3 d and 6 months. On the other hand, 2 mg of SiCW increased the level of SP-C mRNA from 3 d to 3 months, and 10 mg of SiCW decreased the levels of SP-C mRNA in the rat lungs at 3 d, 1 month and 6 months. No clear tendency to the expression of SP-C was observed, but the patterns of expression of TTF-1 and SP-A were similar. These data suggest that SP-A and TTF-1 are associated with not only the acute phase but also the chronic phase in lungs exposed to SiCW.

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To examine associations between interpersonal relationships in work settings and burnout, a cross-sectional survey was conducted on home care workers in Sapporo, Japan, by using the Maslach Burnout Inventory (MBI) and scales of interpersonal conflict and social support developed by the authors. Questionnaires were distributed among 303 subjects and returned by 243 subjects (80%). Complete answers were obtained from 106 subjects and were used for analysis. In multiple regression analyses, conflict with clients and their families significantly related to emotional exhaustion and depersonalization of the MBI (p<.05). Supervisory conflict significantly related to emotional exhaustion (p<.05), whereas coworker conflict significantly associated with depersonalization (p<.01). It is suggested that conflicts with clients' families, as well as clients, are important indicators for emotional exhaustion and depersonalization of home care workers.

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Aim-The aim of our study was to assess the prevalence of chronic work related respiratory symptoms and to determine lung function abnormalities in animal feed industry workers. Method-108 workers with a mean age of ± SD: 32 ± 7.11 yr employed in the animal feed industry and 108 unexposed subjects as a control group were enrolled in the study. All subjects filled out a questionnaire on their respiratory symptoms. Pulmonary function tests (PFTs) were conducted. Airborne dust (respirable fraction) was sampled during an 8-h work shift. Dust sampling was performed with a Casella AFC 123 machine. Results-A significantly higher prevalence of work related upper and lower respiratory tract symptoms such as cough (12%), dyspnea (5.6%) and sinusitis (8.3%) were found among the workers than in the control group (p=0.001, p=0.04 and p=0.008 respectively). Irritation symptoms such as pruritis of the eyes (11.1%), skin lesions (7.4%) and nose symptoms (8.3%) were also significantly higher among workers that in the control group (p=0.001, p=0.014 and p=0.005 respectively). The mean PFTs (predicted %) of the workers; forced vital capacity (FVC)% ± SD (85.23 ± 12.06), 1-s forced expiratory volume (FEV1)% ± SD (88.73 ± 13.09), peak expiratory flow (PEF)% ± SD (70.64 ± 18.76) and forced expiratory flow rate at 25-75% of the FVC (FEF25-75)% ± SD (88.42 ± 25.94) were found significantly lower than in the control group (p<0.0001, p<0.0001, p<0.0001, p<0.0001 respectively). Our data indicate that exposure to animal feed dust is an important factor in the occurrence of respiratory symptoms and decline in lung functions.

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