The study area is among Changsha, Zhuzhou, and Xiangtan cities, which was under agricultural use and natural conditions about 10 years ago and now is becoming part of the metropolis because of the urban expansion. This study aims to investigate the mechanisms and capabilities of the local alluvial soil layer for protecting the local shallow groundwater from arsenic pollution by field surveys and batch experiments. The field surveys showed that there was an acidic tendency of the groundwater, and phosphate, nitrate, and arsenic in the groundwater significantly increased comparing to their reference values. It indicates that the disturbance of the former agricultural land due to the change of land use may be responsible for these changes. From the experimental results, the maximum adsorption capacity of the soil for As(V) was as low as 0.334 mg/g, and lower As(V) adsorption capacities were obtained at higher As(V) concentration, higher pH, and lower temperature. The presence of HPO and SiO posed negative, while HCO slight positive, and SO, NO and Cl negligible influences on the As(V) adsorption. The surface-derived organic matter played a negative role in the adsorption process, and low specific surface area influenced adsorption capacity of the soil. The study reveals that the local soil layer shows poor potential for protection of the local shallow groundwater from As(V) pollution, and the change trends of the groundwater environments due to more intensive anthropogenic activities will further weaken this potential and increase the risk of the groundwater contamination.

Background We aimed to investigate the role of PDCD4-mediated Akt signaling pathway in vascular endothelial cell injury caused by ischemia-reperfusion in the lower extremities. Material/Methods Ten rats were used as control, while 50 rats were used for creating disease models and were assigned to 5 groups: model group (no injection), NC group (injected with vectors containing PDCD negative control sequence), sh-PDCD4 group (injected with vectors containing sh-PDCD4 sequence), IGF-1 group (injected with IGF-1), and sh-PDCD4+IGF-1 group (injected with IGF-1 and vectors containing sh-PDCD4 sequence). Results Compared with the control group, the expression levels of PDCD4 mRNA and protein, as well as levels of circulating endothelial cells, von Willebrand factor, thrombomodulin, and malondialdehyde, increased in the other 5 groups, while the mRNA and protein expression levels of Akt and eNOS, the protein expression levels of p-Akt and p-eNOS, and superoxide dismutase content decreased in these groups (all P<0.05). Compared with the model group, the sh-PDCD4 and sh-PDCD4+1GF-1 groups had lower mRNA and protein expressions of PDCD4 (all P<0.05), whereas the IGF-1 group had similar levels (all P>0.05). These 3 groups had lower levels of circulating endothelial cells, von Willebrand factor, thrombomodulin, and malondialdehyde, and higher mRNA and protein expressions of Akt and eNOS, protein expressions of p-Akt and p-eNOS, and superoxide dismutase content (all P<0.05). The NC group did not differ from the model group (all P>0.05). Conclusions PDCD4 gene silencing can activate the Akt signaling pathway and attenuate vascular endothelial cell injury caused by ischemia-reperfusion in the lower extremities in rats.

Background: Matrix metalloproteinases (MMPs) are supposed to be potential drug targets to prevent leakage after colonic anastomosis. A method of colonic anastomosis by using a stent coated with doxycycline, a MMP inhibitor, was developed and its safety and feasibility, as well as the effect of locally regulating MMPs, were evaluated by comparing with the conventional method or the method with a doxycycline-free stent. Methods: 48 pigs were assigned randomly to doxycycline-coated stent anastomosis group (DSA), doxycycline-free stent anastomosis group (SA), or conventional anastomosis group (CA). In each group, pigs were subdivided into four subgroups according to postoperative observation time (3, 7, 14, and 30 days). Healing of anastomosis and expressions of MMP-2/9 were evaluated. Results: No anastomotic leakage, stricture or necrosis was observed in the DSA group. No significant difference of bursting pressure was found between the DSA group and SA group. Relative expression of MMP-2 in the DSA group was significantly lower than in the SA group on postoperative days 3 and 7. No significant differences of hydroxyproline content, microvessel density and TGF-β₁ level were found in these groups. Conclusion: These results suggested this method was feasible and safe for colonic anastomosis with the advantage of locally inhibiting MMPs.

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