Lipoxin A 4 (LXA 4 ), as an endogenously produced lipid mediator, promotes the resolution of inflammation. Previously, we demonstrated that LXA 4 stimulated alveolar fluid clearance through alveolar epithelial sodium channel gamma (ENaC-γ). In this study, we sought to investigate the mechanisms of LXA 4 in modulation of ENaC-γ in lipopolysaccharide (LPS)-induced inflammatory lung injury. miR-21 was upregulated during an LPS challenge and downregulated by LXA 4 administration in vivo and in vitro. Serum miR-21 concentration was also elevated in acute respiratory distress syndrome patients as compared with healthy volunteers. LPS increased miR-21 expression by activation of activator protein 1 (AP-1). In A549 cells, miR-21 upregulated phosphorylation of AKT activation via inhibition of phosphatase and tensin homolog (PTEN), and therefore reduced the expression of ENaC-γ. In contrast, LXA 4 reversed LPS-inhibited ENaC-γ expression through inhibition of AP-1 and activation of PTEN. In addition, an miR-21 inhibitor mimicked the effects of LXA 4 ; overexpression of miR-21 abolished the protective effects of LXA 4 . Finally, both AKT and ERK inhibitors (LY294002 and UO126) blocked effects of LPS on the depression of ENaC-γ. However, LXA 4 only inhibited LPS-induced phosphorylation of AKT. In summary, LXA 4 activates ENaC-γ in part via the miR-21/PTEN/AKT signaling pathway.

SUMMARYBased on the physical properties of rolled compacted concrete (RCC) arch dam, three-dimensional ÿnite element relocating mesh method is used to simulate the temperature distribution for di erent pipe cooling scheme in the RCC arch dam during construction and operation period. Many factors have also been considered, such as thermal adiabatic rise of temperature with age, the process of placement by layer, work suspension in summer, the change of air temperature, the method of superÿcial thermal insulation and water storage in temperature ÿeld. The calculated results show that the cooling e ect was notable and the maximum temperature decreased greatly at the centre of the dam when the layout range of pipe cooling changed from El.2299-2327 m to El.2275-2293 m.

No abstract

No abstract

No abstract