Objective： Diabetic nephropathy （DN） is one of the most common causes of end-stage renal failure. The pathogenesis of progressive renal injury is multifactorial and the mechanism by which hyperglycemia causes micro...Objective： Diabetic nephropathy （DN） is one of the most common causes of end-stage renal failure. The pathogenesis of progressive renal injury is multifactorial and the mechanism by which hyperglycemia causes microangiopathy is still poorly understood. The WNT pathway is activated in DN and regulating β-catenin protein levels is referred to as the canonical Wntβ-catenin pathway. Because the renin angiotensin system has been reported to be an important contributory factor in the pathophysiology of DN, exogenous administration of angiotensin Ⅱ receptor antagonist may be beneficial in counteracting some biochemical or functional changes of DN. The aim of the study was to determine the β-catenin expression and the possible protective effects of irbesartan, an angiotensin Ⅱ type 1 receptor blocker （ARB） in a rat model of streptozotocin（STZ）-induced diabetic nephropathy. Methods： STZ-induced DN in rats was assessed biochemically by measuring urine volume, protein and creatinine clearance as well as Kidney weight/body weight （KW/BW） and the index of mesangial expansion. Three groups of male Sprague-dawley rats were used. The first group consisted of non-diabetic control rats （control）. The second group was the untreated diabetic rats（STZ＋vehicle）. The third group consisted of diabeti rats treated with irbesartan, 50 mg/kg for 12 weeks （STZ＋irbesartan）. Immunohistochemical stainings and real time PCR for β-catenin were performed in renal cortex of rat modals. Results： Marked hyperglycemia, polyuria, proteinuria, renal hypertrophy, mesangial matrix expansion and glomerular hyperfiltration were observed in STZ diabetic rats. The levels of microalbuminuria and KW/BW in the STZ＋irbesartan group were lower than those in the STZ＋vehicle group （P〈0.05）. The up-regulated immunostaining and mRNA expression of β-catenin were decreased in renal cortic of the Irbesartan-treated diabetic group, but there was no significant difference compared to the untreated diabetic group. Conclusion： The data suggest that irbesartan ameliorates proteinuria and renal hypertrophy, charactered damages of STZ-induced early-stage DN in rats, but its effective drug target is not to inhibit the up-regulated expressions of β-catenin.展开更多
The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational flu...The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,validated with published data,was used to solve the gas-solid multiphase flow of a sandstorm around a train.The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated.Results showed that in sandstorm weather,the drag,lift,side forces and overturning moment increase by variable degrees.Based on a numerical analysis of aerodynamic characteristics,an equation of train stability was also derived using the theory of moment balance from the view of dynamics.A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.展开更多
文摘Objective： Diabetic nephropathy （DN） is one of the most common causes of end-stage renal failure. The pathogenesis of progressive renal injury is multifactorial and the mechanism by which hyperglycemia causes microangiopathy is still poorly understood. The WNT pathway is activated in DN and regulating β-catenin protein levels is referred to as the canonical Wntβ-catenin pathway. Because the renin angiotensin system has been reported to be an important contributory factor in the pathophysiology of DN, exogenous administration of angiotensin Ⅱ receptor antagonist may be beneficial in counteracting some biochemical or functional changes of DN. The aim of the study was to determine the β-catenin expression and the possible protective effects of irbesartan, an angiotensin Ⅱ type 1 receptor blocker （ARB） in a rat model of streptozotocin（STZ）-induced diabetic nephropathy. Methods： STZ-induced DN in rats was assessed biochemically by measuring urine volume, protein and creatinine clearance as well as Kidney weight/body weight （KW/BW） and the index of mesangial expansion. Three groups of male Sprague-dawley rats were used. The first group consisted of non-diabetic control rats （control）. The second group was the untreated diabetic rats（STZ＋vehicle）. The third group consisted of diabeti rats treated with irbesartan, 50 mg/kg for 12 weeks （STZ＋irbesartan）. Immunohistochemical stainings and real time PCR for β-catenin were performed in renal cortex of rat modals. Results： Marked hyperglycemia, polyuria, proteinuria, renal hypertrophy, mesangial matrix expansion and glomerular hyperfiltration were observed in STZ diabetic rats. The levels of microalbuminuria and KW/BW in the STZ＋irbesartan group were lower than those in the STZ＋vehicle group （P〈0.05）. The up-regulated immunostaining and mRNA expression of β-catenin were decreased in renal cortic of the Irbesartan-treated diabetic group, but there was no significant difference compared to the untreated diabetic group. Conclusion： The data suggest that irbesartan ameliorates proteinuria and renal hypertrophy, charactered damages of STZ-induced early-stage DN in rats, but its effective drug target is not to inhibit the up-regulated expressions of β-catenin.
基金Project(No.2009BAG12A01-C03) supported by the National Key Technology R&D Program of China
文摘The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,validated with published data,was used to solve the gas-solid multiphase flow of a sandstorm around a train.The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated.Results showed that in sandstorm weather,the drag,lift,side forces and overturning moment increase by variable degrees.Based on a numerical analysis of aerodynamic characteristics,an equation of train stability was also derived using the theory of moment balance from the view of dynamics.A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.
