Protective mechanism of L-arginine against liver ischemic-reperfusion injury in rats

OBJECTIVE: To investigate the protective effect of L-arginine (L-arg) against liver ischemic-reperfusion (I/R) injury in rat model and its possible mechanism. METHODS: Male Sprague-Dawley rats were randomized into sham group: hepatoduodenal ligament mobilized, but not clamped; control group: hepatic ischemia only; Arg group: 5 minutes before hepatic ischemia, L-arg (200 mg/kg) injected via the dorsal penis vein; Arg+L group: 10 and 5 minutes before hepatic ischemia, L-NAME (30 mg/kg) and L-arg (200 mg/kg) injected via the dorsal penis vein, respectively; and Fink group: 5 minutes before, hepatic ischemia, ZVAD-fmk (15 mg/kg) injected via the dorsal penis vein. The liver was subjected to ischemia for 40 minutes by Pringle's maneuver, and reperfusion was initiated hy removing clamp. The 7-day survival rate, alanine transaminase (ALT) level, caspase-3 activity and apoptotic hepatocyte count were compared among these groups. RESULTS: After 40 minutes of ischemia and 6 hours of reperfusion, the 7-day survival rate of the Arg group was significantly higher than that of the control and Arg+L groups (P<0.05). The ALT Level, caspase-3 activity and apoptotic hepatocyte count in the Arg group were decreased significantly than those in the control and Arg+L groups (P<0. 01). The caspase-3 activity and apoptotic hepatocyte count in the Arg group were slightly higher than those in the sham and Fmk groups, but there was no statistical significance. CONCLUSIONS: L-arg could ameliorate liver I/R injury and the possible protective mechanism is inhibition of hepatocyte apoptosis via inhibition of caspase-3 activity by nitric oxide synthesis.

近α型Ti−6Al−2Zr−1Mo−1V钛合金帽形试样在高应变速率下的剪切局部化行为

采用Hopkinson冲击实验装置(SHPB)研究近α型Ti−6Al−2Zr−1Mo−1V钛合金帽形试样剪切局部化的组织特征,通过背散射电子衍射技术(EBSD)揭示帽形试样的组织演变及剪切变形机制。结果表明,绝热剪切带的形核与扩展受几何因素及组织因素的影响。变形影响区中的位错增值、组织细化和温升提供基本的组织条件。除位错滑移外,在剪切区中还发现了大量的拉伸孪生,孪晶界大大加速了组织细化过程。三明治结构对绝热剪切带最终形态有很大影响,在动态变形过程中,这种结构会形成更宽、更稳定的绝热剪切带。但是,很宽的三明治结构也可能成为利于裂纹形核的位置。

Combined vascular resection and analysis of prognostic factors for hilar cholangiocarcinoma

BACKGROUND： Hilar cholangiocarcinoma （HCCA） is a devastating malignancy arising from the bifurcation of the hepatic duct, whether combined vascular resection benefits HCCA patients is controversial. This study was undertaken to assess the effect of combined vascular resection in HCCA patients and to analyze the prognostic factors.

Hepatocyte apoptosis induced by hepatic ischemia-reperfusion injury in cirrhotic rats

OBJECTIVE: To investigate whether hepatocyte apoptosis in hepatic ischemia-reperfusion (I/R) injury is mediated by Fas pathway. METHODS: Fas-mRNA expression detected by in situ hybridization assay, caspase-3 activity measured by fluorescence spectrophotometer, and hepatocyte apoptosis detected by TUNEL assay were compared in different L/R conditions between cirrhotic and normal rats. The relationship was analyzed between hepatocyte apoptosis, Fas-mRNA expression, and caspase-3 activity. RESULTS: In cirrhotic rats, Fas-mRNA expression and caspase-3 activity were significantly increased when the ischemic time prolonged, and subsequently, hepatocyte apoptosis was increased (P<0.O1). Under the same I/R condition, the Fas-mRNA expression, caspase-3 activity and hepatocyte apoptosis in cirrhotic liver were significantly higher than those in normal liver (P<0.O1). CONCLUSIONS: Hepatocyte apoptosis in hepatic I/R injury might be mediated by Fas pathway. The possible underlying mechanism that cirrhotic liver is more sensitive to ischemic injury than normal liver is alteration of Fas expression level.

Latent Heat of TB18 Titanium Alloy during β to α Phase Transition by DSC and First-Principles Methods

The phase transition of titanium alloys is sensitive to the heat-treatment procedure,accompanied with the latent heat induced by phase transition.However,the latent heat during phase transition of titanium alloy has not been systematically studied,which may result in the gap between designed and actual temperature of the sample and affect the final mechanical properties.In this work,DSC(differential scanning calorimetry)and first-principles simulate methods were used to study theβ→αphase transition process of TB18(Ti–Al-Mo-V-Cr-Nb-Fe system)metastableβtitanium alloy,especially to reveal the influence of the heating rate on latent heat.The ratio of latent heat to endothermic heat of the sample during temperature rising was introduced to interpret the effect of latent heat to actual temperature.The ratio of latent heat to endothermic heat at 1℃/min is about 15 to 20 times higher than that at 10℃/min.The higher ratio indicates that the latent heat of phase transition has a more significant effect on the temperature,which is related to the temperature range of phase transition and theαvolume fraction.Compared with the heating rate of 1℃/min,theβ→αphase transition takes place at higher temperature and the volume fraction ofαis smaller at 10℃/min.Meanwhile,there is a precipitation free zone between grain boundaryαand intragranularαand the distribution ofαlamellae is heterogeneous when the heating rate is 10℃/min.Both of the experimental and theoretical results suggest that the latent heat of phase transition is the main cause of the temperature fluctuation during heat-treatment process.This work has guiding significance for microstructure optimization affected by temperature,to achieve the desired mechanical properties.