AIM: To investigate the relationship between gallstone disease and nonalcoholic fatty liver disease(NAFLD) in a large Asian population. METHODS: A cross-sectional study including 17612 subjects recruited from general ...AIM: To investigate the relationship between gallstone disease and nonalcoholic fatty liver disease(NAFLD) in a large Asian population. METHODS: A cross-sectional study including 17612 subjects recruited from general health check-ups at the Seoul National University Hospital, Healthcare System Gangnam Center between January 2010 and December 2010 was conducted. NAFLD and gallstone disease were diagnosed based on typical ultrasonographic findings. Subjects who were positive for hepatitis B or C, or who had a history of heavy alcohol consumption(> 30 g/d for men and > 20 g/d for women) or another type of hepatitis were excluded. Gallstone disease was defined as either the presence of gallstones or previous cholecystectomy, and these two entities(gallstones and cholecystectomy) were analyzed separately. Clinical parameters including body mass index, waist circumference, hypertension, diabetes, smoking status, and regular physical activity were reviewed. Laboratory parameters, including serum levels of gamma-glutamyl transpeptidase, alanine aminotransferase, aspartate aminotransferase, fasting glucose, fasting insulin, total cholesterol, triglycerides, and high-density lipoprotein, were also reviewed.RESULTS: The mean age of the subjects was 48.5± 11.3 years, and 49.3% were male. Approximately 30.3% and 6.1% of the subjects had NAFLD and gallstone disease, respectively. The prevalence of gallstone disease(8.3% vs 5.1%, P < 0.001), including both the presence of gallstones(5.5% vs 3.4%, P < 0.001) and a history of cholecystectomy(2.8% vs 1.7%, P < 0.001), was significantly increased in the NAFLD group. In the same manner, the prevalence of NAFLD increased with the presence of gallstone disease(41.3% vs 29.6%, P < 0.001). Multivariate regression analysis showed that cholecystectomy was associated with NAFLD(OR = 1.35, 95%CI: 1.03-1.77, P = 0.028). However, gallstones were not associated with NAFLD(OR = 1.15, 95%CI: 0.95-1.39, P = 0.153). The independent association between cholecystectomy and NAFLD was still significant after additional adjustment for insulin resistance(OR = 1.45, 95%CI: 1.01-2.08, P = 0.045). CONCLUSION: This study shows that cholecystectomy, but not gallstones, is independently associated with NAFLD after adjustment for metabolic risk factors. These data suggest that cholecystectomy may be an independent risk factor for NAFLD.展开更多
Alcoholic hepatitis(AH) is an acute hepatic manifesta-tion occurring from heavy alcohol ingestion. Alcoholic steatohepatitis(ASH) is histologically characterized by steatosis, inflammation, and fibrosis in the liver. ...Alcoholic hepatitis(AH) is an acute hepatic manifesta-tion occurring from heavy alcohol ingestion. Alcoholic steatohepatitis(ASH) is histologically characterized by steatosis, inflammation, and fibrosis in the liver. Despite the wide range of severity at presentation, those with severe ASH(Maddrey's discriminant function ≥ 32) typically present with fever, jaundice, and abdominal tenderness. Alcohol abstinence is the cornerstone of therapy for AH and, in the milder forms, is sufficient for clinical recovery. Severe ASH may progress to multi-or-gan failure including acute kidney injury and infection. Thus, infection and renal failure have a major impact on survival and should be closely monitored in patients with severe ASH. Patients with severe ASH have a re-ported short-term mortality of up to 40%-50%. Severe ASH at risk of early death should be identified by one of the available prognostic scoring systems before consid-ering specific therapies. Corticosteroids are the main-stay of treatment for severe ASH. When corticosteroids are contraindicated, pentoxifylline may be alternatively used. Responsiveness to steroids should be assessed at day 7 and stopping rules based on Lille score should come into action. Strategically, future studies for pa-tients with severe ASH should focus on suppressing inflammation based on cytokine profiles, balancing he-patocellular death and regeneration, limiting activation of the innate immune response, and maintaining gut mucosal integrity.展开更多
Hepatitis B reactivation is a potentially serious complication of anticancer chemotherapy,which occurs during and after therapy.This condition affects primarily hepatitis B surface antigen(HBsAg)-positive patients,but...Hepatitis B reactivation is a potentially serious complication of anticancer chemotherapy,which occurs during and after therapy.This condition affects primarily hepatitis B surface antigen(HBsAg)-positive patients,but sometimes HBsAg-negative patients can be at risk,based only on evidence of past infection or occult infection with a low titer of detectable hepatitis B virus(HBV)DNA.The clinical outcomes vary with the different degrees of virologic and biochemical rebound,ranging from asymptomatic elevations in liver enzymes to hepatic failure and even death.Despite the remarkable advancement in the treatment of chronic hepatitis B over the past decade,proper strategies for the prevention and management of HBV reactivation remain elusive.Moreover,with the increasing use of rituximab in patients with lymphoma,HBV reactivation in occult or past infections has become increasingly problematic,especially in HBV-endemic regions.This review addresses the current knowledge on the clinical aspects and management of chemotherapy-related HBV reactivation,updates from recent reports,several unresolvedissues and future perspectives.展开更多
Manning＇s roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coeffici...Manning＇s roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.展开更多
A bstract The venerid clam(M actra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean a...A bstract The venerid clam(M actra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidifi cation on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO_2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fi ssures. Specimens were incubated in seawater equilibrated with bubbled CO_2-enriched air at(400±25)×10^(-6)(ambient control),(800±25)×10^(-6)(high pCO_2), or(1 200±28)×10^(-6)(extremely high pCO_2), the atmospheric CO_2 concentrations predicted for the years 2014, 2084, and 2154(70-year intervals; two human generations), respectively, in the Representative Concentration Pathway(RCP) 8.5 scenario. The mean shell lengths of larvae were signifi cantly decreased in the high and extremely high pCO_2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO_2 conditions, the cultures exhibited signifi cantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fi ssures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO_2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.展开更多
YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure...YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.展开更多
While log law is an equation theoretically derived for near-bed region, in most cases, power law has been researched by experimental methods. Thus, many consider it as an empirical equation and fixed power law exponen...While log law is an equation theoretically derived for near-bed region, in most cases, power law has been researched by experimental methods. Thus, many consider it as an empirical equation and fixed power law exponents such as 1/6 and 1/7 are generally applied. However, exponent of power law is an index representing bed resistance related with relative roughness and furthermore influences the shapes of vertical velocity distribution. The purpose of this study is to investigate characteristics of vertical velocity distribution of the natural rivers by testing and optimizing previous methods used for determination of power law exponent with vertical velocity distribution data collected with ADCPs during the years of 2005 to 2009 from rivers in South Korea. Roughness coefficient has been calculated from the equation of Limerinos. And using theoretical and empirical formulae, and representing relationships between bed resistance and power law exponent, it has been evaluated whether the exponents suggested by these equations appropriately reproduce vertical velocity distribution of actual rivers. As a result, it has been confirmed that there is an increasing trend of power law exponent as bed resistance increases. Therefore, in order to correctly predict vertical velocity distribution in the natural rivers, it is necessary to use an exponent that reflects flow conditions at the field.展开更多
Advanced fibrosis determines the prognosis of nonalcoholic fatty liver disease(NAFLD);therefore,accurate risk-prediction for advanced fibrosis is fundamental in the management of NAFLD(1).Targeted screening for advanc...Advanced fibrosis determines the prognosis of nonalcoholic fatty liver disease(NAFLD);therefore,accurate risk-prediction for advanced fibrosis is fundamental in the management of NAFLD(1).Targeted screening for advanced fibrosis in high-risk populations,such as those with type 2 diabetes,obesity with metabolic complications,a family history of cirrhosis,or significant alcohol use is recommended for implementing early intervention to prevent future adverse hepatic outcomes of NAFLD(2,3).Non-invasive tests including fibrosis-4 index(FIB-4)and liver stiffness measurement(LSM)are recommended to identify individuals at a higher risk of liver-related events(1,2).In addition to clinical classifications,such as FIB-4;genetic information provides further stratification for liver-related outcomes(4).展开更多
基金Supported by Seoul National University Hospital Research Fund,No.04-2014-0660
文摘AIM: To investigate the relationship between gallstone disease and nonalcoholic fatty liver disease(NAFLD) in a large Asian population. METHODS: A cross-sectional study including 17612 subjects recruited from general health check-ups at the Seoul National University Hospital, Healthcare System Gangnam Center between January 2010 and December 2010 was conducted. NAFLD and gallstone disease were diagnosed based on typical ultrasonographic findings. Subjects who were positive for hepatitis B or C, or who had a history of heavy alcohol consumption(> 30 g/d for men and > 20 g/d for women) or another type of hepatitis were excluded. Gallstone disease was defined as either the presence of gallstones or previous cholecystectomy, and these two entities(gallstones and cholecystectomy) were analyzed separately. Clinical parameters including body mass index, waist circumference, hypertension, diabetes, smoking status, and regular physical activity were reviewed. Laboratory parameters, including serum levels of gamma-glutamyl transpeptidase, alanine aminotransferase, aspartate aminotransferase, fasting glucose, fasting insulin, total cholesterol, triglycerides, and high-density lipoprotein, were also reviewed.RESULTS: The mean age of the subjects was 48.5± 11.3 years, and 49.3% were male. Approximately 30.3% and 6.1% of the subjects had NAFLD and gallstone disease, respectively. The prevalence of gallstone disease(8.3% vs 5.1%, P < 0.001), including both the presence of gallstones(5.5% vs 3.4%, P < 0.001) and a history of cholecystectomy(2.8% vs 1.7%, P < 0.001), was significantly increased in the NAFLD group. In the same manner, the prevalence of NAFLD increased with the presence of gallstone disease(41.3% vs 29.6%, P < 0.001). Multivariate regression analysis showed that cholecystectomy was associated with NAFLD(OR = 1.35, 95%CI: 1.03-1.77, P = 0.028). However, gallstones were not associated with NAFLD(OR = 1.15, 95%CI: 0.95-1.39, P = 0.153). The independent association between cholecystectomy and NAFLD was still significant after additional adjustment for insulin resistance(OR = 1.45, 95%CI: 1.01-2.08, P = 0.045). CONCLUSION: This study shows that cholecystectomy, but not gallstones, is independently associated with NAFLD after adjustment for metabolic risk factors. These data suggest that cholecystectomy may be an independent risk factor for NAFLD.
文摘Alcoholic hepatitis(AH) is an acute hepatic manifesta-tion occurring from heavy alcohol ingestion. Alcoholic steatohepatitis(ASH) is histologically characterized by steatosis, inflammation, and fibrosis in the liver. Despite the wide range of severity at presentation, those with severe ASH(Maddrey's discriminant function ≥ 32) typically present with fever, jaundice, and abdominal tenderness. Alcohol abstinence is the cornerstone of therapy for AH and, in the milder forms, is sufficient for clinical recovery. Severe ASH may progress to multi-or-gan failure including acute kidney injury and infection. Thus, infection and renal failure have a major impact on survival and should be closely monitored in patients with severe ASH. Patients with severe ASH have a re-ported short-term mortality of up to 40%-50%. Severe ASH at risk of early death should be identified by one of the available prognostic scoring systems before consid-ering specific therapies. Corticosteroids are the main-stay of treatment for severe ASH. When corticosteroids are contraindicated, pentoxifylline may be alternatively used. Responsiveness to steroids should be assessed at day 7 and stopping rules based on Lille score should come into action. Strategically, future studies for pa-tients with severe ASH should focus on suppressing inflammation based on cytokine profiles, balancing he-patocellular death and regeneration, limiting activation of the innate immune response, and maintaining gut mucosal integrity.
文摘Hepatitis B reactivation is a potentially serious complication of anticancer chemotherapy,which occurs during and after therapy.This condition affects primarily hepatitis B surface antigen(HBsAg)-positive patients,but sometimes HBsAg-negative patients can be at risk,based only on evidence of past infection or occult infection with a low titer of detectable hepatitis B virus(HBV)DNA.The clinical outcomes vary with the different degrees of virologic and biochemical rebound,ranging from asymptomatic elevations in liver enzymes to hepatic failure and even death.Despite the remarkable advancement in the treatment of chronic hepatitis B over the past decade,proper strategies for the prevention and management of HBV reactivation remain elusive.Moreover,with the increasing use of rituximab in patients with lymphoma,HBV reactivation in occult or past infections has become increasingly problematic,especially in HBV-endemic regions.This review addresses the current knowledge on the clinical aspects and management of chemotherapy-related HBV reactivation,updates from recent reports,several unresolvedissues and future perspectives.
基金supported by the 2006 Core Construction Technology Development Project(Grant No.06KSHS-B01) through the ECORIVER21 Research Center in KICTTEP of MOCT KOREA
文摘Manning＇s roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.
基金Supported by the Korea Polar Research Institute(Nos.PE14150,PM15040)
文摘A bstract The venerid clam(M actra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidifi cation on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO_2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fi ssures. Specimens were incubated in seawater equilibrated with bubbled CO_2-enriched air at(400±25)×10^(-6)(ambient control),(800±25)×10^(-6)(high pCO_2), or(1 200±28)×10^(-6)(extremely high pCO_2), the atmospheric CO_2 concentrations predicted for the years 2014, 2084, and 2154(70-year intervals; two human generations), respectively, in the Representative Concentration Pathway(RCP) 8.5 scenario. The mean shell lengths of larvae were signifi cantly decreased in the high and extremely high pCO_2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO_2 conditions, the cultures exhibited signifi cantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fi ssures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO_2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.
基金supported by Samsung Research Fund,Sungkyunkwan University,2006
文摘YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.
文摘While log law is an equation theoretically derived for near-bed region, in most cases, power law has been researched by experimental methods. Thus, many consider it as an empirical equation and fixed power law exponents such as 1/6 and 1/7 are generally applied. However, exponent of power law is an index representing bed resistance related with relative roughness and furthermore influences the shapes of vertical velocity distribution. The purpose of this study is to investigate characteristics of vertical velocity distribution of the natural rivers by testing and optimizing previous methods used for determination of power law exponent with vertical velocity distribution data collected with ADCPs during the years of 2005 to 2009 from rivers in South Korea. Roughness coefficient has been calculated from the equation of Limerinos. And using theoretical and empirical formulae, and representing relationships between bed resistance and power law exponent, it has been evaluated whether the exponents suggested by these equations appropriately reproduce vertical velocity distribution of actual rivers. As a result, it has been confirmed that there is an increasing trend of power law exponent as bed resistance increases. Therefore, in order to correctly predict vertical velocity distribution in the natural rivers, it is necessary to use an exponent that reflects flow conditions at the field.
基金supported by Korea National Institute of Health(KNIH)research project(2022ER090700).
文摘Advanced fibrosis determines the prognosis of nonalcoholic fatty liver disease(NAFLD);therefore,accurate risk-prediction for advanced fibrosis is fundamental in the management of NAFLD(1).Targeted screening for advanced fibrosis in high-risk populations,such as those with type 2 diabetes,obesity with metabolic complications,a family history of cirrhosis,or significant alcohol use is recommended for implementing early intervention to prevent future adverse hepatic outcomes of NAFLD(2,3).Non-invasive tests including fibrosis-4 index(FIB-4)and liver stiffness measurement(LSM)are recommended to identify individuals at a higher risk of liver-related events(1,2).In addition to clinical classifications,such as FIB-4;genetic information provides further stratification for liver-related outcomes(4).
