The mechanism(s) determining the progression from fatty liver to steatohepatitis is currently unknown. Our goal was to define the relative impact of iron overload, genetic mutations of HFE, and insulin resistance on the severity of liver fibrosis in a population of subjects with nonalcoholic fatty liver disease (NAFLD) who had low prevalence of obesity and no overt symptoms of diabetes. In a cohort of 263 prospectively enrolled patients with NAFLD, 7.4% of patients had signs of peripheral iron overload and 9% had signs of hepatic iron overload, but 21.1% had hyperferritinemia. The prevalence of C282Y and H63D HFE mutations was similar to the general population and mutations were not associated with iron overload. Although subjects were on average only moderately overweight, insulin sensitivity, measured both in the fasting state and in response to oral glucose, was lower. Univariate analysis demonstrated that the presence of severe fibrosis was independently associated with older age, female sex, overweight, aspartate/alanine aminotransferase ratio, serum ferritin level, fasting glucose and insulin levels, decreased insulin sensitivity, and with histologic features (degree of necroinflammation and steatosis). After adjustment for body mass index (BMI), age, sex, and degree of steatosis, ferritin levels (odds ratio [OR] ؍ 1.77; 95% CI ؍ 1.21-2.58; P ؍ .0032) and the oral glucose insulin sensitivity (OR ؍ 0.53; CI ؍ 0.33-0.87; P ؍ .0113) were independent predictors of severe fibrosis. In conclusion, the current study indicates that insulin resistance is a major, independent risk factor for advanced fibrosis in patients with NAFLD. Increased ferritin levels are markers of severe histologic damage, but not of iron overload. Iron burden and HFE mutations do not contribute significantly to hepatic fibrosis in the majority of patients with NAFLD. (HEPATOLOGY 2004;39:179 -187.) N onalcoholic fatty liver disease (NAFLD) is growing in importance, causing in a wide spectrum of hepatic injury, ranging from fatty liver to steatohepatitis and cirrhosis. 1 Whereas pure fatty liver has a benign clinical course, nonalcoholic steatohepatitis (NASH) is a recognized cause of progressive liver fibrosis that eventually leads to cirrhosis, liver failure, and hepatocellular carcinoma. 2-4 NAFLD and NASH are the two most common chronic liver diseases in Western countries, with an estimated prevalence in the general population of 10% to 20% and 2% to 3%, respectively. 2,5-7 A two-hit theory 8 has been proposed to explain the progression from simple steatosis to NASH, fibrosis, or cirrhosis. The first hit is represented by excessive hepatic fat accumulation primarily owing to insulin resistance and is supported by the close relation observed between NAFLD and several features of the metabolic syndrome (visceral obesity, type II diabetes mellitus, and dyslipidemia). 9 -11 The second hit is related mainly to increased intrahepatic oxidative stress, which promotes hepatic fibrosis through the production of reactive oxygen sp...
OBJECTIVE -Reactive oxygen and nitric oxide (NO) have recently been considered to be involved in the cardiovascular complications of patients with type 2 diabetes, as NO is thought to lose its beneficial physiological effects in the presence of oxygen radicals. For this reason, we tested the effects of L-arginine (ARG) and N-acetylcysteine (NAC) administration in increasing NO bioavailability by reducing free radical formation. RESEARCH DESIGN AND METHODS-A double-blind study was performed on 24 male patients with type 2 diabetes and hypertension divided into two groups of 12 patients that randomly received either an oral supplementation of placebo or NAC ϩ ARG for 6 months.RESULTS -The NAC ϩ ARG treatment caused a reduction of both systolic (P Ͻ 0.05) and diastolic (P Ͻ 0.05) mean arterial blood pressure, total cholesterol (P Ͻ 0.01), LDL cholesterol (P Ͻ 0.005), oxidized LDL (P Ͻ 0.05), high-sensitive C-reactive protein (P Ͻ 0.05), intracellular adhesion molecule (P Ͻ 0.05), vascular cell adhesion molecule (P Ͻ 0.01), nitrotyrosine (P Ͻ 0.01), fibrinogen (P Ͻ 0.01), and plasminogen activator inhibitor-1 (P Ͻ 0.05), and an improvement of the intima-media thickness during endothelial postischemic vasodilation (P Ͻ 0.02). HDL cholesterol increased (P Ͻ 0.05). No changes in other parameters studied were observed.CONCLUSIONS -NAC ϩ ARG administration seems to be a potential well-tolerated antiatherogenic therapy because it improves endothelial function in hypertensive patients with type 2 diabetes by improving NO bioavailability via reduction of oxidative stress and increase of NO production. Our study's results give prominence to its potential use in primary and secondary cardiovascular prevention in these patients. Diabetes Care 31:940-944, 2008
The study showed activation of TNF-α axis and oxidative stress in AN patients, as well as correlation between the two systems. Due to the correlation between TNF receptors and both BMI and disease duration, a possible role of pro-inflammatory cytokines in the evolution of the eating disorder is suggested.
Objectives:Few in vitro studies have examined the participation of resistin, a recently discovered adipokine, in oxidative processes. We investigated whether in vivo treatment with the antioxidant vitamin C might affect resistin serum levels.Design:Randomized prospective open trial.Setting:San Giovanni Battista Hospital, Turin, Italy.Participants:Eighty healthy individuals.Intervention:Administration of 2 g of ascorbic acid orally for 2 wk (n = 40; experimental group) or no supplementation (n = 40; control group).Outcome measures:The primary end point was the between-group difference in the before–after change in resistin serum level after vitamin C supplementation. Secondary endpoints were the within- and between-group changes in glucose, insulin, lipid parameters, C-reactive protein fasting values, and markers of oxidative stress.Results:In the experimental group, vitamin C supplementation was significantly associated with both resistin concentration reduction (from 4.3 ± 1.5 to 2.9 ± 0.8 ng/ml; 95% confidence interval [CI] −1.87, −1.03) and ascorbic acid level increase (from 9.4 ± 2.9 to 19.0 ± 5.2 mg/l; 95% CI 7.9, 11.2). In the control group, resistin levels did not change significantly (from 4.2 ± 1.0 to 4.3 ± 0.9 ng/ml; 95% CI −0.07, 0.37). The between-group differences were highly significant (p < 0.001). Vitamin C supplementation was also associated with a statistically significant reduction in nitrotyrosine level and incremental increase in reduced glutathione. In a linear regression model, within-individual changes in vitamin C concentrations were inversely correlated with changes in resistin levels in both groups (each unit increase of vitamin C corresponded to a decrease of about 0.10 units of resistin levels (95% CI 0.13, 0.08; p < 0.001).Conclusion:This is to our knowledge the first randomized trial in humans that has demonstrated that short-term vitamin C supplementation could significantly reduce resistin levels, independent of changes in inflammatory or metabolic variables. Future investigations of resistin participation in oxidative processes are warranted.
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