Yuanfen Zhou

Changes of serum sex hormone levels and MT mRNA expression in rats orally exposed to cadmium

It has been demonstrated that cadmium (Cd) is carcinogenic to rodent prostate. However, the mechanism of its toxicity is far from fully understood. In the present study, the effects of oral Cd exposure (0, 50, 100, 200 ppm in drinking water) on serum sex hormone levels, the expression of MT-I and MT-II mRNA, and the zinc content of rat prostate were assessed. With Cd administration, serum testosterone (T) levels significantly increased in all Cd groups after 3 months and in the 200 ppm Cd group after 6 months. A significant depression in the serum luteinizing hormone (LH) level was seen in the Cd group (200 ppm) after 6 months. It was noted that Cd administration resulted in a significant down-regulation in the expression of MT-I and MT-II mRNA in the rat ventral prostate. However, no Cd-induced changes in the mRNA expression of Metallothioneins (MTs) were detected in the dorsolateral prostate. After Cd administration, the content of Cd in both the ventral and dorsolateral lobes of the prostate significantly increased with increasing dose and duration of Cd administration. In contrast, the Zn content decreased with Cd administration in both the ventral and dorsolateral lobes of the rat prostate. Taken together, these results suggest that oral Cd exposure may disrupt endocrine homeostasis, changing the distribution of Zn and the mRNA expression of MTs in rat prostate, and that such Cd-induced changes may contribute to the susceptibility of prostate to the carcinogenicity of this heavy metal.

Increased risk of chronic obstructive pulmonary diseases in coke oven workers : interaction between occupational exposure and smoking

Background: Coke oven workers are regularly exposed to coke oven emissions (COE) and may be at risk of developing lung diseases. There is limited evidence for the link between exposure to COE and chronic obstructive pulmonary diseases (COPD). The aim of this study was to explore the dose-response relationship between COE exposure and COPD and to assess the interaction with cigarette smoking. Methods: Seven hundred and twelve coke oven workers and 211 controls were investigated in southern China. Benzene soluble fraction (BSF) concentrations as a surrogate of COE were measured in representative personal samples and the individual cumulative COE exposure level was quantitatively estimated. Detailed information on smoking habits and respiratory symptoms was collected and spirometric tests were performed. Results: The mean BSF levels at the top of two coking plants were 743.8 and 190.5 μg/m3, respectively, which exceed the OSHA standard (150 μg/m3). After adjusting for cigarette smoking and other risk factors, there was a significant dose-dependent reduction in lung function and increased risks of chronic cough/phlegm and COPD in coke oven workers. The odds ratio for COPD was 5.80 (95% confidence interval 3.13 to 10.76) for high level cumulative COE exposure (⩾1714.0 μg/m3-years) compared with controls. The interaction between COE exposure and smoking in COPD was significant. The risk of COPD in those with the highest cumulative exposure to COE and cigarette smoking was 58-fold compared with non-smokers not exposed to COE. Conclusion: Long term exposure to COE increases the risk of an interaction between COPD and cigarette smoking.