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目的探讨环境镉暴露时胎盘组织金属硫蛋白表达的意义。方法于2002年11月~2003年1月选择湖北省某市的待产孕妇,进行问卷调查和体格检查,同时检测全血镉水平;采集新生儿脐血和部分胎盘组织用于测定镉含量。对部分胎盘组织做了免疫组织化学检查,观察胎盘组织MT表达情况;分析胎盘组织MT表达与孕妇镉暴露水平、胎盘镉蓄积及胎盘镉转运关系。结果母血镉波动在0.27~13.00μg/L,其中60.71%超过血镉正常范围的上限(1.2μg/L)。胎盘镉水平波动在0.0325~1.69μg/g干重。所有新生儿脐血镉水平均低于孕母血镉,波动在0.02~2.69μg/L,与母血镉比值的中位数为0.274。Spearman相关分析表明,胎盘镉、脐血镉均与母血镉呈显著正相关(rs=0.450,P<0.01;rs=0.343,P<0.01)。全部研究对象胎盘组织MT表达的阳性率为60%(84/140),多因素logistic逐步回归分析,母血镉与MT表达高度相关(OR=13.822,95%可信区间为2.591~73.719);正常血镉孕妇胎盘组织MT的阳性表达率为47.27%(26/55),高血镉孕妇胎盘组织MT的阳性表达率为68.24%(58/85),层间MT阳性表达率差异有统计学意义(χ2=6.1141,P<0.05)。全部研究对象中进行协方差分析,不同MT表达组间脐血镉/母血镉差异有统计学意义(F=4.13,P<0.05)。结论胎盘对镉具有明显的屏障作用,环境镉暴露能诱导胎盘组织MT的表达。
Objective To investigate the significance of metallothionein in placental tissue under cadmium exposure. Methods From November 2002 to January 2003, pregnant women in a city in Hubei province were selected for questionnaire and physical examination. Cadmium level in whole blood was also measured. Neonatal cord blood and some placental tissues were collected for the determination of cadmium content. Immunohistochemistry was performed on some of the placenta tissues to observe the expression of MT in placenta tissue. The expression of MT in placenta tissue was analyzed in relation to cadmium exposure in pregnant women, the accumulation of placental cadmium and the relationship between placental cadmium transport. Results The fluctuation of maternal blood cadmium was 0.27 ~ 13.00μg / L, of which 60.71% exceeded the upper limit of the normal range of blood cadmium (1.2μg / L). Placental cadmium levels fluctuated between 0.0325 and 1.69 μg / g dry weight. All newborn umbilical cord blood cadmium levels were lower than the maternal serum cadmium, fluctuations in the 0.02 ~ 2.69μg / L, with the ratio of mother’s blood to cadmium was 0.274. Spearman correlation analysis showed that placental cadmium and umbilical cord blood cadmium were positively correlated with maternal blood cadmium (rs = 0.450, P <0.01; rs = 0.343, P <0.01). The positive rate of MT expression in placenta of all subjects was 60% (84/140). Multivariate logistic regression analysis showed that the expression of cadmium was highly correlated with MT (OR = 13.822, 95% CI: 2.591 ~ 73.719). The positive expression rate of placental MT in normal blood cadmium group was 47.27% (26/55). The positive expression rate of placental MT in high blood cadmium group was 68.24% (58/85) Significance (χ2 = 6.1141, P <0.05). Covariance analysis was performed in all subjects. There were significant differences in the levels of cadmium and serum maternal serum cadmium between different MT expression groups (F = 4.13, P <0.05). Conclusion The placenta has obvious barrier function to cadmium. Environmental cadmium exposure can induce the expression of MT in placenta.