Failure mechanism and control technology of water-immersed roadway in high-stress and soft rock in a deep mine

Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.

Pretreatment with intestinal trefoil factor alleviates stress-induced gastric mucosal damage via Akt signaling

BACKGROUND Stress-related gastric mucosal damage or ulcer remains an unsolved issue for critically ill patients.Stress ulcer prophylaxis has been part of routine intensive care,but uncertainty and controversy still exist.Co-secreted with mucins,intestinal trefoil factor(ITF)is reported to promote restitution and regeneration of intestinal mucosal epithelium,although the mechanism remains unknown.AIM To elucidate the protective effects of ITF on gastric mucosa and explore the possible mechanisms.METHODS We used a rat model of gastric mucosal damage induced by water immersion restraint stress and lipopolysaccharide-treated human gastric epithelial cell line to investigate the potential effects of ITF on damaged gastric mucosa both in vivo and in vitro.RESULTS ITF promoted the proliferation and migration and inhibited necrosis of gastric mucosal epithelia in vitro.It also preserved the integrity of gastric mucosa by upregulating expressions of occludin and zonula occludens-1.In the rat model,pretreatment with ITF ameliorated the gastric mucosal epithelial damage and facilitated mucosal repair.The protective effects of ITF were confirmed to be exerted via activation of Akt signaling,and the specific inhibitor of Akt signaling LY249002 reversed the protective effects.CONCLUSION ITF might be a promising candidate for prevention and treatment of stressinduced gastric mucosal damage,and further studies should be undertaken to verify its clinical feasibility.

Protective role of fruits of Rosa odorata var. gigantea against WIRSinduced gastric mucosal injury in rats by modulating pathway related to inflammation, oxidative stress and apoptosis

Objective: Rosa odorata var. gigantea is a popular medicinal plant. Some studies have demonstrated that ethanolic extract of the fruits of R. odorata var. gigantea(FOE) has gastroprotective properties. The aim of this study was to investigate the gastroprotective activity of FOE on water immersion restrained stress(WIRS)-induced gastric mucosal injury in a rat model and elucidate the possible molecular mechanisms involved.Methods: A rat stress ulcer model was established in this study using WIRS. After rats were treated with FOE orally for 7 d, the effect of FOE treatment was analyzed by hematoxylin and eosin(H&E) staining, and the changes of inflammatory factors, oxidative stress factors, and gastric-specific regulatory factors and pepsin in the blood and gastric tissues of rats were examined by ELISA assay. Molecular mechanism of FOE was investigated by immunohistochemical assay and Western blot.Results: Compared with the WIRS group, FOE could diminish both the macroscopic and microscopic pathological morphology of gastric mucosa. FOE significantly preserved the antioxidants glutathione peroxidase(GSH-PX), superoxide dismutase(SOD) and catalase(CAT) contents;anti-inflammatory cytokines interleukin-10(IL-10) and prostaglandin E2(PGE2) levels as well as regulatory factors tumor necrosis factor-a(TGF-a) and somatostatin(SS) contents, while decreasing malondialdehyde(MDA), nitric oxide synthase(i NOS), tumor necrosis factor(TNF-a), interleukin-1β(IL-1β), interleukin-6(IL-6), gastrin(GAS)and endothelin(ET) levels. Moreover, FOE distinctly upregulated the expression of Nrf2, HO-1, Bcl2 and proliferating cell nuclear antigen(PCNA). In addition, FOE activated the expression of p-EGFR and downregulated the expression of NF-ΚB, Bax, Cleaved-caspase-3, Cyto-C and Cleaved-PARP1, thus promoting gastric mucosal cell survival.Conclusion: The current work demonstrated that FOE exerted a gastroprotective activity against gastric mucosal injury induced by WIRS. The underlying mechanism might be associated with the improvement of anti-inflammatory, anti-oxidation and anti-apoptosis systems.