AIM： To determine the clinical outcome and predictors of survival after transjugular intrahepatic portosystemic stent shunt （TIPS） implantation in cirrhotic patients. METHODS： Eighty-one patients with liver cirrho...AIM： To determine the clinical outcome and predictors of survival after transjugular intrahepatic portosystemic stent shunt （TIPS） implantation in cirrhotic patients. METHODS： Eighty-one patients with liver cirrhosis and consequential portal hypertension had TIPS implanta- tion （bare metal） for either refractory ascites （RA） （n = 27） or variceal bleeding （VB） （n = 54）. Endpoints for the study were： technical success, stent occlusion and stent stenosis, rebleeding, RA and mortality. Clini- cal records of patients were collected and analysed. Baseline characteristics [e.g., age, sex, CHILD score and the model for end-stage liver disease score （MELD score）, underlying disease] were retrieved. The Kaplan- Meier method was employed to calculate survival from the time of TIPS implantation and comparisons were made by log rank test. A multivariate analysis of factors influencing survival was carried out using the Cox pro- portional hazards regression model. Results were ex- pressed as medians and ranges. Comparisons between groups were performed by using the Mann-Whitney U-test and the4,2 test as appropriate. RESULTS： No difference could be seen in terms of age, sex, underlying disease or degree of portal pressure gradient （PPG） reduction between the ascites and the bleeding group. The PPG significantly decreased from 23.4 ± 5.3 mmHg （VB） vs 22.1± 5.5 mmHg （RA） be- fore TIPS to 11.8 ±4.0 vs 11.7 ± 4.2 after TIPS im- plantation （P = 0.001 within each group）. There was a tendency towards more patients with stage CHILD A in the bleeding group compared to the ascites group （24 vs 6, P = 0.052）. The median survival for the ascites group was 29 mo compared to 〉 60 mo for the bleed- ing group （P = 0.009）. The number of radiological con- trols for stent patency was 6.3 for bleeders and 3.8 for ascites patients （P = 0.029）. Kaplan-Meier calculation indicated that stent occlusion at first control （P = 0.027）, ascites prior to TIPS implantation （P = 0.009）, CHILD stage （P = 0.013）, MELD score （P = 0.001） and those patients not having undergone liver transplantation （P = 0.024） were significant predictors of survival. In the Cox regression model, stent occlusion （P = 0.022）, RA （P = 0.043）, CHILD stage （P = 0.015） and MELD score （P = 0.004） turned out to be independent prognostic factors of survival. The anticoagulation management （P = 0.097）, the porto-systemic pressure gradient （P= 0.460） and rebleeding episodes （P = 0.765） had no significant effect on the overall survival. CONCLUSION： RA, stent occlusion, initial CHILD stage and MELD score are independent predictors of survival in patients with TIPS, speaking for a close follow-up in these circumstances.展开更多
Portal hypertension is the main complication of cirrhosis and is defined as an hepatic venous pressure gradient （HVPG） of more than 5 mmHg. Clinically significant portal hypertension is defined as HVPG of 10 mmHg or...Portal hypertension is the main complication of cirrhosis and is defined as an hepatic venous pressure gradient （HVPG） of more than 5 mmHg. Clinically significant portal hypertension is defined as HVPG of 10 mmHg or more. Development of gastroesophageal varices and variceal hemorrhage are the most direct consequence of portal hypertension. Over the last decades significant advancements in the field have led to standard treatment options. These clinical recommendations have evolved mostly as a result of rando.mized controlled trials and consensus conferences among experts where existing evidence has been reviewed and future goals for research and practice guidelines have been pro- posed. Management of varices/variceal hemorrhage is based on the clinical stage of portal hypertension. No specific treatment has shown to prevent the formation of varices. Prevention of first variceal hemorrhage depends on the size/characteristics of varices. In patients with small varices and high risk of bleeding, nonselective β-blockers are recommended, while patients with medium/large varices can be treated with either β-blockers or esophageal band ligation. Standard ofcare for acute variceal hemorrhage consists of vasoacrive drugs, endoscopic band ligation and antibiotics prophylaxis. Transjugular intrahepatic portosystemic shunt （TIPS） is reserved for those who fail standard of care or for patients who are likely to fail （＂early TIPS＂）. Prevention of recurrent variceal hemorrhage consists of the combination of β-blockers and endoscopic band ligation.展开更多
Carbon nanotube(CNT)/polymer nanocomposites have vast application in industry because of their light mass and high strength. In this work, a cylindrical tube which is made up of functionally graded(FG) PmP V/CNT nanoc...Carbon nanotube(CNT)/polymer nanocomposites have vast application in industry because of their light mass and high strength. In this work, a cylindrical tube which is made up of functionally graded(FG) PmP V/CNT nanocomposite, is optimally designed for the purpose of torque transmission. The main confining parameters of a rotating shaft in torque transmission process are mass of the shaft, critical speed of rotation and critical buckling torque. It is required to solve a multi-objective optimization problem(MOP) to consider these three targets simultaneously in the process of design. The three-objective optimization problem for this case is defined and solved using a hybrid method of FEM and modified non-dominated sorting genetic algorithm(NSGA-II), by coupling two softwares, MATLAB and ABAQUS. Optimization process provides a set of non-dominated optimal design vectors. Then, two methods, nearest to ideal point(NIP) and technique for ordering preferences by similarity to ideal solution(TOPSIS), are employed to choose trade-off optimum design vectors. Optimum parameters that are obtained from this work are compared with the results of previous studies for similar cylindrical tubes made from composite or a hybrid of aluminum and composite that more than 20% improvement is observed in all of the objective functions.展开更多
The vibration and instability of functionally graded material(FGM)sandwich cylindrical shells conveying fluid are investigated.The Navier-Stokes relation is used to describe the fluid pressure acting on the FGM sandwi...The vibration and instability of functionally graded material(FGM)sandwich cylindrical shells conveying fluid are investigated.The Navier-Stokes relation is used to describe the fluid pressure acting on the FGM sandwich shells.Based on the third-order shear deformation shell theory,the governing equations of the system are derived by using the Hamilton’s principle.To check the validity of the present analysis,the results are compared with those in previous studies for the special cases.Results manifest that the natural frequency of the fluid-conveying FGM sandwich shells increases with the rise of the core-to-thickness ratio and power-law exponent,while decreases with the rise of fluid density,radius-to-thickness ratio and length-to-radius ratio.The fluid-conveying FGM sandwich shells lose stability when the non-dimensional flow velocity falls in 2.1-2.5,which should be avoided in engineering application.展开更多
基金Supported by A research fellowship from the Faculty of Medicine, Westflische Wilhelms-Universitt Münster
文摘AIM： To determine the clinical outcome and predictors of survival after transjugular intrahepatic portosystemic stent shunt （TIPS） implantation in cirrhotic patients. METHODS： Eighty-one patients with liver cirrhosis and consequential portal hypertension had TIPS implanta- tion （bare metal） for either refractory ascites （RA） （n = 27） or variceal bleeding （VB） （n = 54）. Endpoints for the study were： technical success, stent occlusion and stent stenosis, rebleeding, RA and mortality. Clini- cal records of patients were collected and analysed. Baseline characteristics [e.g., age, sex, CHILD score and the model for end-stage liver disease score （MELD score）, underlying disease] were retrieved. The Kaplan- Meier method was employed to calculate survival from the time of TIPS implantation and comparisons were made by log rank test. A multivariate analysis of factors influencing survival was carried out using the Cox pro- portional hazards regression model. Results were ex- pressed as medians and ranges. Comparisons between groups were performed by using the Mann-Whitney U-test and the4,2 test as appropriate. RESULTS： No difference could be seen in terms of age, sex, underlying disease or degree of portal pressure gradient （PPG） reduction between the ascites and the bleeding group. The PPG significantly decreased from 23.4 ± 5.3 mmHg （VB） vs 22.1± 5.5 mmHg （RA） be- fore TIPS to 11.8 ±4.0 vs 11.7 ± 4.2 after TIPS im- plantation （P = 0.001 within each group）. There was a tendency towards more patients with stage CHILD A in the bleeding group compared to the ascites group （24 vs 6, P = 0.052）. The median survival for the ascites group was 29 mo compared to 〉 60 mo for the bleed- ing group （P = 0.009）. The number of radiological con- trols for stent patency was 6.3 for bleeders and 3.8 for ascites patients （P = 0.029）. Kaplan-Meier calculation indicated that stent occlusion at first control （P = 0.027）, ascites prior to TIPS implantation （P = 0.009）, CHILD stage （P = 0.013）, MELD score （P = 0.001） and those patients not having undergone liver transplantation （P = 0.024） were significant predictors of survival. In the Cox regression model, stent occlusion （P = 0.022）, RA （P = 0.043）, CHILD stage （P = 0.015） and MELD score （P = 0.004） turned out to be independent prognostic factors of survival. The anticoagulation management （P = 0.097）, the porto-systemic pressure gradient （P= 0.460） and rebleeding episodes （P = 0.765） had no significant effect on the overall survival. CONCLUSION： RA, stent occlusion, initial CHILD stage and MELD score are independent predictors of survival in patients with TIPS, speaking for a close follow-up in these circumstances.
文摘Portal hypertension is the main complication of cirrhosis and is defined as an hepatic venous pressure gradient （HVPG） of more than 5 mmHg. Clinically significant portal hypertension is defined as HVPG of 10 mmHg or more. Development of gastroesophageal varices and variceal hemorrhage are the most direct consequence of portal hypertension. Over the last decades significant advancements in the field have led to standard treatment options. These clinical recommendations have evolved mostly as a result of rando.mized controlled trials and consensus conferences among experts where existing evidence has been reviewed and future goals for research and practice guidelines have been pro- posed. Management of varices/variceal hemorrhage is based on the clinical stage of portal hypertension. No specific treatment has shown to prevent the formation of varices. Prevention of first variceal hemorrhage depends on the size/characteristics of varices. In patients with small varices and high risk of bleeding, nonselective β-blockers are recommended, while patients with medium/large varices can be treated with either β-blockers or esophageal band ligation. Standard ofcare for acute variceal hemorrhage consists of vasoacrive drugs, endoscopic band ligation and antibiotics prophylaxis. Transjugular intrahepatic portosystemic shunt （TIPS） is reserved for those who fail standard of care or for patients who are likely to fail （＂early TIPS＂）. Prevention of recurrent variceal hemorrhage consists of the combination of β-blockers and endoscopic band ligation.
文摘Carbon nanotube(CNT)/polymer nanocomposites have vast application in industry because of their light mass and high strength. In this work, a cylindrical tube which is made up of functionally graded(FG) PmP V/CNT nanocomposite, is optimally designed for the purpose of torque transmission. The main confining parameters of a rotating shaft in torque transmission process are mass of the shaft, critical speed of rotation and critical buckling torque. It is required to solve a multi-objective optimization problem(MOP) to consider these three targets simultaneously in the process of design. The three-objective optimization problem for this case is defined and solved using a hybrid method of FEM and modified non-dominated sorting genetic algorithm(NSGA-II), by coupling two softwares, MATLAB and ABAQUS. Optimization process provides a set of non-dominated optimal design vectors. Then, two methods, nearest to ideal point(NIP) and technique for ordering preferences by similarity to ideal solution(TOPSIS), are employed to choose trade-off optimum design vectors. Optimum parameters that are obtained from this work are compared with the results of previous studies for similar cylindrical tubes made from composite or a hybrid of aluminum and composite that more than 20% improvement is observed in all of the objective functions.
基金supported by the National Natural Science Foundation of China(Nos.11922205,12072201)the Fundamental Research Fund for the Central Universities(No.N2005019)。
文摘The vibration and instability of functionally graded material(FGM)sandwich cylindrical shells conveying fluid are investigated.The Navier-Stokes relation is used to describe the fluid pressure acting on the FGM sandwich shells.Based on the third-order shear deformation shell theory,the governing equations of the system are derived by using the Hamilton’s principle.To check the validity of the present analysis,the results are compared with those in previous studies for the special cases.Results manifest that the natural frequency of the fluid-conveying FGM sandwich shells increases with the rise of the core-to-thickness ratio and power-law exponent,while decreases with the rise of fluid density,radius-to-thickness ratio and length-to-radius ratio.The fluid-conveying FGM sandwich shells lose stability when the non-dimensional flow velocity falls in 2.1-2.5,which should be avoided in engineering application.
