Correlation between fatty liver and coronary risk factors: a population study of elderly men and women in Nagasaki, Japan

Steatosis and hepatitis C virus: mechanisms and significance for hepatic and extrahepatic disease

Nonalcoholic fatty liver disease (NAFLD) and hepatitis C virus (HCV)-related liver disease are common in the general population, but their concurrence is 2- to 3-fold higher than would be expected by chance alone. In patients with chronic HCV infection, steatosis is attributable to a variable combination of the mechanisms considered to play a role in the pathogenesis of NAFLD--insulin resistance in the obese and in the lean subject--along with a direct effect of HCV on hepatic lipid metabolism that leads to triglyceride accumulation through inhibition of export proteins that are required for very low density lipoprotein (VLDL) assembly and secretion. Accumulating evidence suggests that steatosis contributes to the progression of fibrosis in HCV-related disease in a pattern similar to that observed in NAFLD. Potential mechanisms of this effect include the increased sensitivity of steatotic livers to oxidative stress and cytokine-mediated injury. Steatosis-related hepatic insulin resistance may also play a role through the profibrogenic effects of the compensatory hyperinsulinemia and provides a potential explanation for the association between HCV and type 2 diabetes mellitus. Indeed, an appreciation of the importance of fat in HCV has recently led to trials of adjuvant therapy for HCV directed at steatosis-associated disease mechanisms, with encouraging results reported for various modalities, including weight loss and antioxidants. Future therapy should be aimed at exploiting the interactions of HCV with host insulin and lipid metabolism, particularly in nonresponders to standard antiviral schedules.

Non-alcoholic steatohepatitis: what is it, and why is it important in the Asia-Pacific region?

Non-alcoholic steatohepatitis (NASH), is a critical link in the chain of metabolic fatty liver disorders that spans steatosis to cryptogenic cirrhosis. It is the hepatic manifestation of the insulin resistance (or metabolic) syndrome, and provides a clue to understanding fibrotic progression of other chronic liver diseases, particularly hepatitis C. Non-alcoholic steatohepatitis is often the first clinical indication of insulin resistance, with its complications of high blood pressure, coronary heart disease and type 2 diabetes. Among those with risk factors, NASH is common: present in at least 20% of obese adults or children with or without type 2 diabetes, and at least 5% of those overweight. With emerging urbanization, increasing affluence and behavioral changes of physical inactivity and high fat/energy-excessive diet, type 2 diabetes has become common in Asia and the western Pacific rim. The rates range from 7-40%, which in countries like Japan represents a 3-20-fold increase (depending on age) over the last 20 years. The increase is associated with central adiposity, insulin resistance, hepatic steatosis and NASH. After cancer, cirrhosis from NASH is now the second most common age-related cause of death in type 2 diabetes. Reversing these trends must become a public health priority; the first awakenings were evident in Taiwan at the time of this meeting. In order to stimulate clinicians to think more about the importance of metabolic liver disease for development of cirrhosis, this review will cover clinical and laboratory features, natural history and an approach to diagnosis and management of NASH. Some emerging concepts on pathogenesis will be mentioned briefly, but the emphasis will be on the potency of lifestyle adjustments (physical activity and diet) to prevent or reverse fatty liver disorders.

Effects of Radiation on Fatty Liver and Metabolic Coronary Risk Factors among Atomic Bomb Survivors in Nagasaki

In order to clarify the basic mechanism(s) linking radiation exposure and coronary heart disease (CHD), we here collected ultrasonographic data on fatty liver and measured levels of metabolic CHD risk factors from November 1990 through October 1992 in 1,517 Nagasaki atomic bomb survivors (575 men and 942 women). Using a cross-sectional study design, we examined the effects of radiation dose on fatty liver and CHD risk factors by means of a multiple logistic regression model. Fatty liver was related to the metabolic CHD risk factors associated with insulin resistance syndrome: obesity, hypertension, hypercholesterolemia, low high density lipoprotein (HDL)-cholesterol, hypertriglyceridemia, and abnormal glucose metabolism. Radiation dose was positively related to fatty liver, low HDL-cholesterol, and hypertriglyceridemia, whereas it had no effects on obesity, hypertension, hypercholesterolemia, or abnormal glucose metabolism. The present results suggested that radiation dose was related to 1) fatty liver, which clustered the metabolic CHD risk factors associated with insulin resistance syndrome and 2) atherogenic lipid profiles. It is suggested that these associations are involved in the basic mechanism(s) linking radiation exposure and CHD.

Fatty liver in non-alcoholic non-overweight Japanese adults: incidence and clinical characteristics

BACKGROUND AND AIMS

Fatty liver is not uncommon in many countries, including Japan, and is mainly caused by alcohol usage and obesity. The aim of this study was to determine the incidence and causative factors of fatty liver in Japanese adults.

METHODS

The clinical characteristics of 3432 Japanese adults who visited our hospital between January and December 2000 for thorough medical examinations were recorded including sex, age, body mass index (BMI), percentage body fat measurement using a bipedal bioimpedance instrument, history of alcohol intake, blood pressure, serum levels of aspartate aminotransferase, alanine aminotransferase (ALT), gamma-glutamyl transpeptidase, total cholesterol, triglyceride, uric acid, fasting blood glucose (FBG), and liver status by ultrasonography (USG).

RESULTS

Of 3432 participants, 747 (21.8%) were diagnosed as having fatty liver by USG, 1873 (54.6%) were 'daily alcohol drinkers', and 698 (20.3%) were overweight (BMI >or= 25 kg/m2). Fatty liver was more frequent in men and overweight subjects (P < 0.01), whereas there was no significant difference in the proportion of the 'daily alcohol drinker' between fatty liver and non-fatty liver participants. The logistic regression analysis showed that BMI, ALT, and triglyceride were independent predictors of fatty liver in both sexes, and FBG, uric acid, percentage body fat, and total cholesterol were independent predictors of fatty liver only in men. It was noted that 319 (9.3%) were non-alcoholic individuals with fatty liver, and 141 (4.1%) were non-alcoholic and non-overweight individuals with fatty liver. The logistic regression analysis showed that percentage body fat was an independent predictor of fatty liver in non-alcoholic and non-overweight participants in both sexes, although non-significant in women in the whole group.

CONCLUSIONS

In our study population, 21.8% had fatty liver diagnosed by USG, 9.3% were non-alcoholic with fatty liver, and 4.1% were non-alcoholic and non-overweight with fatty liver. Our results suggest that central body fat distribution can correlate with the development of fatty liver, and that measurement of percentage body fat is useful to assess the etiology of fatty liver in non-alcoholic and non-overweight participants, particularly women.