[Distribution Characteristics and Pollution Risk of Heavy Metals in River Sediment of Suzhou Water Network Area, China].

The average contents of the heavy metals Cd, Cu, Cr, As, Ni, Pb, and Zn in the sediment of sampling points in the Suzhou water network area were 1.4, 127.4, 83.2, 18.2, 51.7, 145.1, and 350.7 mg·kg-1, respectively, which were 13.7, 5.7, 1.1, 1.7, 1.9, 5.5, and 5.6 times the background values, respectively. The proportions of points exceeding the risk screening values of the GB 15618-2018 standard were 100.0%, 97.3%, 38.4%, 83.6%, 97.3%, 90.4%, and 100.0%, respectively. The pollution degree of single heavy metal elements was evaluated using the improved ground accumulation index method. The pollution degree of the seven heavy metal elements in the sediment of the Suzhou water network area was in the order of Cd>Cu>Pb>Zn>As>Cr>Ni. Among them, Cd showed extremely strong pollution, Cu and Pb showed intense to extremely strong pollution, Zn showed strong pollution, As showed moderate to intense pollution, and Cr and Ni showed moderate pollution. Cd, Pb, Cu, and Zn in the sediment samples of the ancient city area, northwest area, southwest area, and east area were the heavy metal elements with high pollution contributions. The potential ecological risk degree of heavy metals was ranked as northwest>southwest>ancient city area>east. Correlation analysis and principal component analysis showed that Cd, Cu, Cr, As, Ni, Pb, and Zn may have come from anthropogenic factors such as tail gas emissions, the use of chemical fertilizers and pesticides, and the pollutant emissions of the electronic manufacturing industry.

[Increased expression of placenta growth factor in lung tissue of paraquat-induced rat pulmonary fibrosis model].

OBJECTIVE: To investigate the dynamic expression of placenta growth factor (PLGF) in the lungs with paraquat (PQ)-induced pulmonary fibrosis. METHODS: Forty-two adult healthy female Sprague-Dawley (SD) rats were randomly divided into two groups: the control group and the PQ group. Each group was divided into three subgroups, seven animals each. The rats in PQ group were treated intragastrically (ig) with PQ (40 mg/kg) and the rats in control group were treated with the same volume of saline at the beginning of the experiment. The animals of model and control group were sacrificed and lungs were harvested on the 7(th), 14(th) and 28th days respectively. A semiquantitative assay of histological examination and hydroxyproline in lung tissues were used to determine the severity of alveolitis and fibrosis. RT-PCR and immunohistochemistry were used to detect the mRNA and protein expression of PLGF. RESULTS: Hydroxyproline contents in lung tissue were significantly increased after PQ administration. Inflammatory cell infiltration and fibrotic scores were more prominent in the model group compared to the control group. Further study showed that PLGF mRNA on day 7, 14 and 28 (1.28 +/- 0.29, 0.80 +/- 0.07, 0.65 +/- 0.13) and positive index of protein expression (2.27 +/- 0.34, 1.78 +/- 0.41, 1.25 +/- 0.69) in the PQ group were all upregulated as compared with those of the control group. CONCLUSION: The PLGF expression in the lung tissue in rats with paraquat-induced pulmonary fibrosis is upregulated.