Faculty Bibliography

BACKGROUND: Obesity has become a worldwide epidemic, and many methods are currently used to reduce obesity. This systematic review shows the effectiveness of the intragastric balloon (IGB) method compared to the sham/diet (s/d) method. OBJECTIVE: To demonstrate the effectiveness of the IGB method compared to the s/d method. SETTING: Hospital das Clinicas da Universidade de Sao Paulo, Brazil, Public Hospital. METHODS: After searching MEDLINE, Embase, Cochrane, Lilacs, Scopus, and CINAHL, only enrolled randomized control trials comparing IGB/diet with s/d were analyzed. For qualitative analysis, 12 studies were selected, and 9 of these were acceptable for quantitative analysis. RESULTS: The IGB/diet is more effective than s/d when comparing body mass index (BMI) loss with a mean difference of 1.1 kg/m(2) by the Student's t test and 1.41 kg/m(2) by the meta-analysis, with significant differences in both. It is also more effective in weight loss (WL), with a mean difference of 2 kg by the Student's t test and 3.55 kg by the meta-analysis. In the qualitative analysis of % excess WL (%EWL), the mean %EWL is 14.0% in favor of the IGB group compared to the s/d group by the Student's t test; however, no significant difference was found between these groups by quantitative analysis. CONCLUSION: Based on randomized control trial data alone, IGB>400 mL is more effective than sham/diet in achieving BMI loss, WL, and %EWL.

Nonalcoholic fatty liver disease (NAFLD) represents a rapidly growing cause of chronic liver disease in the United States and is associated with significant morbidity and mortality, including progression to liver cirrhosis and hepatocellular carcinoma. NAFLD comprises a spectrum of liver conditions, ranging from simple steatosis to steatosis with inflammation (steatohepatitis) and progressive fibrosis. Weight loss represents a first line therapeutic modality for the management of NAFLD. Herein, we review the evidence base for medical, surgical, and endoscopic approaches to weight loss and their potential impact on the natural history of NAFLD.

Nonalcoholic fatty liver disease (NAFLD) affects one in three Americans and is a major predisposing condition for the metabolic syndrome and type 2 diabetes (T2D). We examined whether a functionally liver-targeted derivative of 2,4-dinitrophenol (DNP), DNP-methyl ether (DNPME), could safely decrease hypertriglyceridemia, NAFLD, and insulin resistance without systemic toxicities. Treatment with DNPME reversed hypertriglyceridemia, fatty liver, and whole-body insulin resistance in high-fat-fed rats and decreased hyperglycemia in a rat model of T2D with a wide therapeutic index. The reversal of liver and muscle insulin resistance was associated with reductions in tissue diacylglycerol content and reductions in protein kinase C epsilon (PKCepsilon) and PKCtheta activity in liver and muscle, respectively. These results demonstrate that the beneficial effects of DNP on hypertriglyceridemia, fatty liver, and insulin resistance can be dissociated from systemic toxicities and suggest the potential utility of liver-targeted mitochondrial uncoupling agents for the treatment of hypertriglyceridemia, NAFLD, metabolic syndrome, and T2D.

By 2030, nearly half of Americans will have nonalcoholic fatty liver disease. In part, this epidemic is fueled by the increasing consumption of caloric sweeteners coupled with an innate capacity to convert sugar into fat via hepatic de novo lipogenesis. In addition to serving as substrates, monosaccharides also increase the expression of key enzymes involved in de novo lipogenesis via the carbohydrate response element-binding protein (ChREBP). To determine whether ChREBP is a potential therapeutic target, we decreased hepatic expression of ChREBP with a specific antisense oligonucleotide (ASO) in male Sprague-Dawley rats fed either a high-fructose or high-fat diet. ChREBP ASO treatment decreased plasma triglyceride concentrations compared with control ASO treatment in both diet groups. The reduction was more pronounced in the fructose-fed group and attributed to decreased hepatic expression of ACC2, FAS, SCD1, and MTTP and a decrease in the rate of hepatic triglyceride secretion. This was associated with an increase in insulin-stimulated peripheral glucose uptake, as assessed by the hyperinsulinemic-euglycemic clamp. In contrast, ChREBP ASO did not alter hepatic lipid content or hepatic insulin sensitivity. Interestingly, fructose-fed rats treated with ChREBP ASO had increased plasma uric acid, alanine transaminase, and aspartate aminotransferase concentrations. This was associated with decreased expression of fructose aldolase and fructokinase, reminiscent of inherited disorders of fructose metabolism. In summary, these studies suggest that targeting ChREBP may prevent fructose-induced hypertriglyceridemia but without the improvements in hepatic steatosis and hepatic insulin responsiveness.

Nonalcoholic fatty liver disease (NAFLD) and insulin resistance have recently been found to be associated with increased plasma concentrations of apolipoprotein CIII (APOC3) in humans carrying single nucleotide polymorphisms within the insulin response element of the APOC3 gene. To examine whether increased expression of APOC3 would predispose mice to NAFLD and hepatic insulin resistance, human APOC3 overexpressing (ApoC3Tg) mice were metabolically phenotyped following either a regular chow or high-fat diet (HFD). After HFD feeding, ApoC3Tg mice had increased hepatic triglyceride accumulation, which was associated with cellular ballooning and inflammatory changes. ApoC3Tg mice also manifested severe hepatic insulin resistance assessed by a hyperinsulinemic-euglycemic clamp, which could mostly be attributed to increased hepatic diacylglycerol content, protein kinase C- activation, and decreased insulin-stimulated Akt2 activity. Increased hepatic triglyceride content in the HFD-fed ApoC3Tg mice could be attributed to a approximately 70% increase in hepatic triglyceride uptake and approximately 50% reduction hepatic triglyceride secretion. CONCLUSION: These data demonstrate that increase plasma APOC3 concentrations predispose mice to diet-induced NAFLD and hepatic insulin resistance.