0.05).Conclusion:Helicid had no effects on the early development of central nervous system in rat offspring.

Objective To explore the maternal toxicity in Wistar rats induced by exposure to methylmercury in rats during pregnancy Methods The parameters of physiological development,reproductive process and brain histomorphology were observed and monoamine neurotransmitters(noradrenaline,dopamine and 5 HT) were determined during pregnancy and lactation periods,continuous oral perfusion with methylmercury with different concentrations of 0 00,0 01,0 05 and 2 00 mg/(kg?d) was performed during the 6th~9th day after conception to terminal pregnancy Results The levels of monoamine neurotransmitters in brain tissue of maternal rats in exposure groups increased significantly compared with those in control group(P

0.05).Conclusion The administration of helicid to pregnant rats did not affect the early development of nervous system, neurobehavioral function and brain histology of offspring.

Objective: To observe the effect of hypoxia on changes of proliferation ability of cultured human periodontal ligament fibroblasts (HPLFS) in vitro. Methods: HPLFS were randomly divided into two groups (experimental group and control group) by different oxygen concentrations. The oxygen concentration of control group was 21%. The oxygen concentrations of experiment group were 10%, 5% and 2%. The proliferation ability of HPLFS was detected by MTT colorimetric assay. The cell ultrastructure was observed by transmission electron microscope (TEM). Results: MTT assay results showed that compared with the control group, at the 12 h and 24 h, cell proliferation was enhanced with the hypoxia degree. At 24 h, cell proliferation showed significant differences. At 48 h and 72 h, proliferation of the cultured HPLFS in severe hypoxia group reduced significantly. Observed by TEM, at 24 h, not only the number of mitochondria, rough endoplasmic reticulum but also cell process increased in the cultured HPLFS in severe hypoxia group. At 72 h, the number of lysosome increased and the cell structure degenerated. Conclusion: Long-time severe hypoxia may lower the repair and remodeling abilities of periodontium, which might be one of the important etiological factors of periodontal disease under condition of high altitude.