Heavy metal exposure, oxidative stress and semen quality: Exploring associations and mediation effects in reproductive-aged men.

BACKGROUND: Heavy metal exposure induces oxidative stress, which is critical for adverse male reproductive health. OBJECTIVE: To explore the mediating effect of oxidative stress on the relationship of heavy metal exposure with semen quality. METHODS: Urinary levels of three oxidative stress markers, semen quality, and urinary arsenic, cadmium and lead were examined among 1020 men. Multivariate linear regression was applied to explore cross-sectional associations, and the role of oxidative stress as mediators was investigated. RESULTS: Quartiles of metals showed significant dose-dependent relationships with increasing levels of 8-hydroxy-2deoxyguanosine (8-OHdG), 8-iso-prostaglandin F2α (8-isoPGF2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA). Significant or suggestive associations were also found between urinary 8-OHdG levels and the percentage of normal sperm morphology (ptrend < 0.001), between urinary 8-isoPGF2α levels and total motility (ptrend = 0.052), progressive motility (ptrend = 0.050) respectively. The mediation analysis showed that about 14.59%, 18.06%, 15.35% or 16.49% of the association between arsenic/cadmium exposure and the decreased total motility/progressive motility was mediated by 8-isoPGF2α, respectively. In addition, about 16.47% of the relationship between lead exposure and the decreased percentage of normal sperm morphology was mediated by 8-OHdG. CONCLUSIONS: Our findings suggest that higher urinary arsenic, cadmium and lead levels were associated with increased oxidative stress markers, which also related with altered semen quality. 8-isoPGF2α and 8-OHdG might be the possible mediators of the associations between urinary heavy metals and total motility, progressive motility or the proportion of normal sperm morphology.

Expressions of Tumor Necrosis Factor alpha-induced Protein 3 and Mammary Serine Protease Inhibitor in Radiotherapy of Nasopharyngeal Carcinoma.

OBJECTIVE: To study the expressions of tumor necrosis factor alpha-induced protein 3(TNFAIP3) and mammary serine protease inhibitor (Maspin) in the radiotherapy of nasopharyngeal carcinoma and explore the differences in radiosensitivity and radioresistance,the relation with the occurrence and development of radioresistance. METHODS: The TNFAIP3 and Maspin mRNA expressions were detected by using TNFAIP3 and Maspin multi-point labeled DIG probes in situ hybridization. RESULTS: In radiosensitivity and radioresistance of nasopharyngeal carcinoma,the moderately and strongly positive TNFAIP3 mRNA expression rates were 27.50% and 48.33% (P=0.037), and the moderately and strongly positive Maspin mRNA expression rates were 67.50% and 46.67% (P=0.040). In the radioresistance of nasopharyngeal carcinoma,TNFAIP3 mRNA moderately and strongly positive expressions were positively correlated with TNM stage (P=0.005). In distant metastasis and no distant metastasis (70.00% and 37.50%, P=0.018), the expression rates had statistical significance. The Maspin mRNA moderately and strongly positive expressions were positively correlated with TNM stage (P=0.039) and T stage (P=0.021). In distant metastasis and no distant metastasis (65.00% and 37.50%, P=0.044), the expression rates had statistical significance. CONCLUSION: TNFAIP3 may be involved in the development of radioresistant nasopharyngeal carcinoma,and Maspin may be related with the invasion and metastasis of radioresistant nasopharyngeal carcinoma.