Clinical usefulness of AGEs as a biomarker for the attenuation of NASH

Department of Internal Medicine, Gulhane School of Medicine, Ankara, Turkey, .
Journal of Gastroenterology (Impact Factor: 4.52). 03/2010; 45(7):779-80; author reply 781. DOI: 10.1007/s00535-010-0229-1
Source: PubMed
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    ABSTRACT: Although it has been reported that angiotensin II receptor blockers inhibited the formation and accumulation of advanced glycation endproducts (AGEs) in vitro and in vivo, whether they can do so clinically is not clear. We investigated the effects of 12-month valsartan therapy on various markers of inflammation, glycation, and oxidation in type 2 diabetic subjects with hypertension. We started 40 mg/day valsartan treatment in 15 type 2 diabetic patients with hypertension. In 6 patients, the dose of valsartan was increased to 80 mg/day after 6 months and maintained until 12 months. Metabolic parameters including BMI and serum high molecular weight (HMW)-adiponectin, high-sensitivity C-reactive protein (hs-CRP) as an inflammation marker, AGEs, paraoxonase activity, platelet-activating factor (PAF)- acetylhydrolase activity, and urine 8-isoprostane levels were measured at baseline and after 6 and 12 months of treatment. Urine microalbumin level and carotid artery intima-media thickness (IMT) were also measured. Even after valsartan therapy, the blood pressure levels of the patients were not decreased significantly. Serum AGEs and urine 8-isoprostane levels decreased at both 6 and 12 months (P < 0.05 for both), although other metabolic and oxidative markers were unchanged. Though urine microalbumin levels tended to be decreased after 6 and 12 months of valsartan treatment, the changes were not significant. Mean IMT at 12 months was not changed from the baseline value. In conclusion, the findings suggest that treatment with valsartan, even at a low dose, may ameliorate some glycation and oxidative stress markers independently of an effect on blood pressure in hypertensive type 2 diabetic subjects.
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    ABSTRACT: Methylglyoxal (MG) is a reactive alpha-dicarbonyl that is thought to contribute to diabetic complications either as a direct toxin or as a precursor for advanced glycation end products. It is produced primarily from triose phosphates and is detoxified to D-lactate (DL) by the glyoxalase pathway. Because guanidino compounds can block dicarbonyl groups, we have investigated the effects of the diamino biguanide compound metformin and of hyperglycemia on MG and its detoxification products in type 2 diabetes. MG and DL were measured by high-performance liquid chromatography in plasma from 57 subjects with type 2 diabetes. Of these subjects, 27 were treated with diet, sulfonylureas, or insulin (nonmetformin), and 30 were treated with metformin; 28 normal control subjects were also studied. Glycemic control was determined by HbA1c. MG was significantly elevated in diabetic subjects versus the normal control subjects (189.3 +/- 38.7 vs. 123.0 +/- 37 nmol/l, P = 0.0001). MG levels were significantly reduced by high-dosage (1,500-2,500 mg/day) metformin (158.4 +/- 44.2 nmol/l) compared with nonmetformin (189.3 +/- 38.7 nmol/l, P = 0.03) or low-dosage (< or = 1,000 mg/day) metformin (210.98 +/- 51.0 nmol/l, P = 0.001), even though the groups had similar glycemic control. Conversely, DL levels were significantly elevated in both the low- and high-dosage metformin groups relative to the nonmetformin group (13.8 +/- 7.7 and 13.4 +/- 4.6 vs. 10.4 +/- 3.9 micromol/l, P = 0.03 and 0.06, respectively). MG correlated with rising HbA1c levels (R = 0.4, P = 0.03, slope = 13.2) in the nonmetformin subjects but showed no increase with worsening glycemic control in the high-dosage metformin group (R = 0.0004, P = 0.99, slope = 0.02). In conclusion, MG is elevated in diabetes and relates to glycemic control. Metformin reduces MG in a dose-dependent fashion and minimizes the effect of worsening glycemic control on MG levels. To the extent that elevated MG levels lead to their development, metformin treatment may protect against diabetic complications by mechanisms independent of its antihyperglycemic effect.
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    ABSTRACT: This study was designed to assess the utility of statin therapy in patients with biopsy proven nonalcoholic steatohepatitis (NASH) and hyperlipidemia. Nonalcoholic fatty liver disease, as the hepatic manifestation of the metabolic syndrome, has become a growing public health concern. Nonalcoholic steatohepatitis (NASH) represents a subset of nonalcoholic fatty liver disease manifested by hepatic fatty infiltration and inflammation which may progress to cirrhosis and its subsequent complications, to include hepatocellular carcinoma. As the metabolic syndrome is thought to be central in the pathogenesis of NASH, it has been speculated that medications that improve metabolic profiles may be beneficial in treatment. In fact, recent studies have demonstrated potential benefit of 3-hydroxy-3-methyglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins), which are used in clinical practice to improve lipid panels. This double-blinded randomized placebo-controlled trial compared the HMG-CoA reductase inhibitor, simvastatin, with placebo in the treatment of NASH over a 12-month period using serum aminotransferases and repeat liver biopsy to assess for improvement. Sixteen patients with biopsy proven NASH were enrolled: 14 completed the study and 10 underwent 1-year repeat liver biopsy. Mean age: 53 years (+/-10.1), mean body mass index: 32.4 (+/-6.1) with 11 male and 5 female patients. Although a 26% reduction in low-density lipoprotein was seen in the simvastatin group compared with placebo, there was no statistically significant improvement in serum aminotransferases, hepatic steatosis, necroinflammatory activity or stage of fibrosis within or between groups. In this pilot trial, monotherapy with simvastatin does not seem to be an effective treatment for NASH.
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