To clarify the incidence of Raynaud's phenomenon among workers exposed to low level hand-arm vibration for a long time, a sample cohort of workers mainly operating a bush cleaner (the vibration level was 2-4 m/s2rms) were followed up for a period of 20 yr. The sample cohort consisted of 331 male workers mainly working at maintaining public roads or afforesting and gardening on a farm. The examination was based on questionnaires used in special medical examinations for vibration syndrome from 1977 to 1996. Raynaud's phenomenon was observed in 11 subjects. The accumulative occurrence rate increased linearly in the case of more than 11 operating years. The mean number of operating years at the occurrence of Raynaud's phenomenon was 11.7 ± 7.1 yr. The mean total operating time at the occurrence of Raynaud's phenomenon was 3,756 h on the geometric average. Stockholm Workshop scale classified 1 subject as Stage 1 (mild), 4 subjects Stage 2 (moderate) and 6 subjects Stage 3 (severe). By the person-year method, the incidence of Raynaud's phenomenon was 4.48 per 1000 person-year. These findings show that the number of operating years for a bush cleaner should be considered to prevent Raynaud's phenomenon, even though the hand-arm vibration level is low.
Objectives: The purposes of this paper were to evaluate the serum leptin levels in healthy adolescents and to establish standard age variation curves.Methods: Nine hundred six (414 boys and 492 girls) healthy adolescents were investigated. The maximum increment age in height (MIA) was identified in 124 boys and 130 girls. The menarcheal age (MA) was obtained for 130 girls. Fasting leptin levels were measured by enzyme immunoassay. The MIA was calculated by proportional allotment of yearly height increments.Results: Serum leptin levels did not change in boys and girls from the ages of 9 to 11. They decreased after the age of 11 in boys, while they increased in girls. Stepwise multiple regression analysis revealed that serum leptin levels were closely related to pubertal stage. The levels decreased remarkably after MIA in boys and increased remarkably after MA in girls. We drew standard age variation curves of serum leptin levels by calculating the 25th, 50th and 75th percentiles for each age in both boys and girls. The percentile curves for boys were divided into pre-MIA and post-MIA curves. Those for girls were divided into pre-MA and post-MA curves.Conclusion: We have devised a potentially useful method for evaluating serum leptin levels in adolescents considering the effects of gender and growth.
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