Effect of pronounced weight loss on visceral fat, liver steatosis and adiponectin isoforms

New predictive models and indices for screening MAFLD in school-aged overweight/obese children

Currently, most predictions of metabolic-associated fatty liver disease (MAFLD) in school-aged children utilize indicators that usually predict nonalcoholic fatty liver disease (NAFLD). The present study aimed to develop new predictive models and predictors for children with MAFLD, which could enhance the feasibility of MAFLD screening programs in the future. A total of 331 school-aged overweight/obese children were recruited from six primary schools in Ningbo city, China. Hepatic steatosis and fibrosis were detected with controlled attenuation parameter (CAP) and liver stiffness measurement (LSM), respectively. Machine learning methods were adapted to build a set of variables to predict MAFLD in children. Then, the area under the curve (AUC) of multiple models and indices was compared to predict pediatric MAFLD. Compared with non-MAFLD children, children with MAFLD had more obvious metabolic disturbances, as they had higher anthropometric indicators, alanine aminotransferase, fasting plasma glucose, and inflammation indicators (white blood cell count, hemoglobin, neutrophil count) (all P < 0.05). The optimal variables for all subjects selected by random forest (RF) were alanine aminotransferase, uric acid, insulin, and BMI. The logistic regression (LR) model performed best, with AUC values of 0.758 for males and 0.642 for females in predicting MAFLD. LnAI-BMI, LnAI, and LnAL-WHtR were approving indices for predicting pediatric MAFLD in all participants, boys and girls individually.

CONCLUSIONS

This study developed LR models and sex-specific indices for predicting MAFLD in overweight/obese children that may be useful for widespread screening and identification of children at high risk of MAFLD for early treatment.

WHAT IS KNOWN

• Most of the indicators predicting pediatric MAFLD are derived from the predictive indicators for NAFLD, but the diagnostic criteria for MAFLD and NAFLD are not exactly the same. • The accuracy of predictors based on routine physical examination and blood biochemical indicators to diagnose MAFLD is limited.

WHAT IS NEW

• This study developed indicators based on routine examination parameters that have approving performance for MAFLD, with AUC values exceeding 0.70.

Analysis of the adiponectin paradox in healthy older people

BACKGROUND

It remains unknown why adiponectin levels are associated with poor physical functioning, skeletal muscle mass and increased mortality in older populations.

METHODS

In 190 healthy adults (59-86 years, BMI 17-37 kg/m² , 56.8% female), whole body skeletal muscle mass (normalized by height, SMI, kg/m² ), muscle and liver fat were determined by magnetic resonance imaging. Bone mineral content (BMC) and density (BMD) were assessed by dual X-ray absorptiometry (n = 135). Levels of insulin-like growth factor 1 (IGF-1), insulin, inflammation markers, leptin and fibroblast growth factor 21 were measured as potential determinants of the relationship between adiponectin and body composition.

RESULTS

Higher adiponectin levels were associated with a lower SMI (r = -0.23, P < 0.01), BMC (r = -0.17, P < 0.05) and liver fat (r = -0.20, P < 0.05) in the total population and with higher muscle fat in women (r = 0.27, P < 0.01). By contrast, IGF-1 showed positive correlations with SMI (r = 0.33), BMD (r = 0.37) and BMC (r = 0.33) (all P < 0.01) and a negative correlation with muscle fat (r = -0.17, P < 0.05). IGF-1 was negatively associated with age (r = -0.21, P < 0.01) and with adiponectin (r = -0.15, P < 0.05). Stepwise regression analyses revealed that IGF-1, insulin and leptin explained 18% of the variance in SMI, and IGF-1, leptin and age explained 16% of the variance in BMC, whereas adiponectin did not contribute to these models.

CONCLUSIONS

Associations between higher adiponectin levels and lower muscle or bone mass in healthy older adults may be explained by a decrease in IGF-1 with increasing adiponectin levels.

Potential Applications of Thyroid Hormone Derivatives in Obesity and Type 2 Diabetes: Focus on 3,5-Diiodothyronine (3,5-T2) in Psammomys obesus (Fat Sand Rat) Model

3,5-Diiodothyronine (3,5-T2) has been shown to exert pleiotropic beneficial effects. In this study we investigated whether 3,5-T2 prevent several energy metabolism disorders related to type 2 diabetes mellitus (T2DM) in gerbils diabetes-prone P. obesus. 157 male gerbils were randomly to Natural Diet (ND-controlled) or a HED (High-Energy Diet) divided in: HED- controlled, HED-3,5-T2 and HED- Placebo groups. 3,5-T2 has been tested at 25 µg dose and was administered under subcutaneous pellet implant during 10 weeks. Isolated hepatocytes were shortly incubated with 3,5-T2 at 10⁻⁶ M and 10⁻⁹ M dose in the presence energetic substrates. 3,5-T2 treatment reduce visceral adipose tissue, prevent the insulin resistance, attenuated hyperglycemia, dyslipidemia, and reversed liver steatosis in diabetes P. obesus. 3,5-T2 decreased gluconeogenesis, increased ketogenesis and enhanced respiration capacity. 3,5-T2 potentiates redox and phosphate potential both in cytosol and mitochondrial compartment. The use of 3,5-T2 as a natural therapeutic means to regulate cellular energy metabolism. We suggest that 3,5-T2 may help improve the deleterious course of obesity and T2DM, but cannot replace medical treatment.

Insights Into the Controversial Aspects of Adiponectin in Cardiometabolic Disorders

In 2016, the World Health Organization estimated that more than 1.9 billion adults were overweight or obese. This impressive number shows that weight excess is pandemic. Overweight and obesity are closely associated with a high risk of comorbidities, such as insulin resistance and its most important outcomes, including metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. Adiponectin has emerged as a salutary adipocytokine, with insulin-sensitizing, anti-inflammatory, and cardiovascular protective properties. However, under metabolically unfavorable conditions, visceral adipose tissue-derived inflammatory cytokines might reduce the transcription of the adiponectin gene and consequently its circulating levels. Low circulating levels of adiponectin are negatively associated with various conditions, such as insulin resistance, type 2 diabetes mellitus, metabolic syndrome, and cardiovascular disease. In contrast, several recent clinical trials and meta-analyses have reported high circulating adiponectin levels positively associated with cardiovascular mortality and all-cause mortality. These results are biologically intriguing and counterintuitive, and came to be termed "the adiponectin paradox". Adiponectin paradox is frequently associated with adiponectin resistance, a concept related with the downregulation of adiponectin receptors in insulin-resistant states. We review this contradiction between the apparent role of adiponectin as a health promoter and the recent evidence from Mendelian randomization studies indicating that circulating adiponectin levels are an unexpected predictor of increased morbidity and mortality rates in several clinical conditions. We also critically review the therapeutic perspective of synthetic peptide adiponectin receptors agonist that has been postulated as a promising alternative for the treatment of metabolic syndrome and type 2 diabetes mellitus.

Beneficial Effects of a Low-dose of Conjugated Linoleic Acid on Body Weight Gain and other Cardiometabolic Risk Factors in Cafeteria Diet-fed Rats

Conjugated linoleic acid (CLA) is a dietary supplement that has been shown to improve obesity. However, some authors have associated high doses of CLA supplementation with liver impairment and insulin resistance. The aim of this study was to assess whether the consumption of low doses of CLA maintained the beneficial effects on the main metabolic disturbances associated with metabolic syndrome (MetS) but prevented the occurrence of non-desirable outcomes associated with its consumption. Male Wistar rats, fed standard or cafeteria (CAF) diet for 12 weeks, were supplemented with three different low doses of CLA in the last three weeks. Both biochemical and H¹ NMR-based metabolomics profiles were analysed in serum and liver. The consumption of 100 mg/kg CLA, but not doses of 200 and 300 mg/kg, ameliorated the increase in body weight gain as well as the serum concentrations of glucose, insulin, cholesterol, triglyceride, diglyceride, and total phospholipid induced by a CAF diet. In turn, CLA reverted the increase in lactate, alanine, and glucose concentrations in the liver of these animals, but enhanced hepatic cholesterol accumulation without any detrimental effect on liver function. In conclusion, a low dose of CLA corrected the adverse effects associated with MetS without compromising other metabolic parameters.

Low levels of total and high-molecular-weight adiponectin may predict non-alcoholic fatty liver in Korean adults

OBJECTIVES

While weight gain is known as a predictor of non-alcoholic fatty liver disease (NAFLD) incidence, it remains controversial whether adipokine levels predict the development of NAFLD. We aimed to investigate the relationship of total adiponectin, high-molecular-weight (HMW) adiponectin, and leptin with the development and improvement of non-alcoholic fatty liver (NAFL) independent of sex and weight change over a maximum of 8.5 years.

METHODS

This prospective study enrolled 2735 participants in a hospital health check-up setting. Adipokine levels were measured at baseline. NAFL was assessed with liver ultrasonography, and the development or improvement of NAFL was determined by repeated ultrasonography at follow-ups.

RESULTS

Cross-sectional analyses revealed that total and HMW adiponectin levels were inversely associated with NAFL prevalence. In longitudinal analyses, the incidence of NAFL was 5.6 per 100-person-years during the observation period. The hazard ratios (HRs) per 1 μg/mL increase in the levels of total and HMW adiponectin were 0.900 (0.836-0.969) and 0.846 (0.754-0.948), respectively. Sex-stratified analyses showed that total and HMW adiponectin levels were significantly related to NAFL incidence only in women. In the subgroup of minimal weight change, only HMW adiponectin was a significant predictor for NAFL. Leptin predicted NAFL in the subgroup with weight gain. The improvement of NAFL was influenced by weight change, but not by adipokine levels.

CONCLUSIONS

Low levels of total and HMW adiponectin may predict the development of NAFL independent of pathophysiological factors including obesity and insulin resistance. This predictability was evident in women. Leptin was a significant predictor for NAFL in the subjects with weight gain.

Monitoring Fatty Liver Disease with MRI Following Bariatric Surgery: A Prospective, Dual-Center Study

Purpose To longitudinally monitor liver fat before and after bariatric surgery by using quantitative chemical shift-encoded (CSE) MRI and to compare with changes in body mass index (BMI), weight, and waist circumference (WC). Materials and Methods For this prospective study, which was approved by the internal review board, a total of 126 participants with obesity who were undergoing evaluation for bariatric surgery with preoperative very low calorie diet (VLCD) were recruited from June 27, 2010, through May 5, 2015. Written informed consent was obtained from all participants. Participants underwent CSE MRI measuring liver proton density fat fraction (PDFF) before VLCD (2-3 weeks before surgery), after VLCD (1-3 days before surgery), and 1, 3, and 6-10 months following surgery. Linear regression was used to estimate rates of change of PDFF (ΔPDFF) and body anthropometrics. Initial PDFF (PDFF₀), initial anthropometrics, and anthropometric rates of change were evaluated as predictors of ΔPDFF. Mixed-effects regression was used to estimate time to normalization of PDFF. Results Fifty participants (mean age, 51.0 years; age range, 27-70 years), including 43 women (mean age, 50.8 years; age range, 27-70 years) and seven men (mean age, 51.7 years; age range, 36-62 years), with mean PDFF₀ ± standard deviation of 18.1% ± 8.6 and mean BMI₀ of 44.9 kg/m² ± 6.5 completed the study. By 6-10 months following surgery, mean PDFF decreased to 4.9% ± 3.4 and mean BMI decreased to 34.5 kg/m² ± 5.4. Mean estimated time to PDFF normalization was 22.5 weeks ± 11.5. PDFF₀ was the only strong predictor for both ΔPDFF and time to PDFF normalization. No body anthropometric correlated with either outcome. Conclusion Average liver proton density fat fraction (PDFF) decreased to normal (< 5%) by 6-10 months following surgery, with mean time to normalization of approximately 5 months. Initial PDFF was a strong predictor of both rate of change of PDFF and time to normalization. Body anthropometrics did not predict either outcome. Online supplemental material is available for this article. © RSNA, 2018.

Changes in body composition and metabolic disease risk

As individuals gain weight, they increase the amount of fat that they accrue on their body. This causes adipocytes to enlarge and increases not only subcutaneous fat but also deposits fat in other vulnerable areas of the body. This ectopic fat is deposited in the intra-abdominal visceral fat depot, in muscle, in the liver and in the beta cells. Fat in these locations initiates a dysfunctional state in these insulin-sensitive tissues leading to insulin resistance, the appearance of the Metabolic Syndrome, and an increased risk of developing both type 2 diabetes and cardiovascular disease. A loss of weight and with it a loss of fat decreases this risk.

Association of Adipokines with Development and Progression of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease affecting 30% of the general population and 40% to 70% of obese individuals. Adipose tissue plays a crucial role in its pathogenesis, as it produces and secretes pro- and anti-inflammatory cytokines called adipokines. Adiponectin and leptin have well-determined actions in terms of NAFLD pathophysiology. Adiponectin deficiency is associated with a pro-inflammatory condition, as it is observed in obesity and other metabolic disorders. On the other hand, increased leptin levels, above the normal levels, act as a pro-inflammatory stimulus. Regarding other adipokines (resistin, visfatin, chemerin, retinol-binding protein 4, irisin), data about their contribution to NAFLD pathogenesis and progression are inconclusive. In addition, pharmacological agents like thiazolidinediones (pioglitazone and rosiglitazone), that are used in the management of NAFLD exert favourable effects on adipokine levels, which in turn may contribute to the improvement of liver function. This review summarizes the current knowledge and developments in the association between adipokines and NAFLD and discusses possible therapeutic implications targeting the modulation of adipokine levels as a potential tool for the treatment of NAFLD.

Adipokines and Non-Alcoholic Fatty Liver Disease: Multiple Interactions

Accumulating evidence links obesity with low-grade inflammation which may originate from adipose tissue that secretes a plethora of pro- and anti-inflammatory cytokines termed adipokines. Adiponectin and leptin have evolved as crucial signals in many obesity-related pathologies including non-alcoholic fatty liver disease (NAFLD). Whereas adiponectin deficiency might be critically involved in the pro-inflammatory state associated with obesity and related disorders, overproduction of leptin, a rather pro-inflammatory mediator, is considered of equal relevance. An imbalanced adipokine profile in obesity consecutively contributes to metabolic inflammation in NAFLD, which is associated with a substantial risk for developing hepatocellular carcinoma (HCC) also in the non-cirrhotic stage of disease. Both adiponectin and leptin have been related to liver tumorigenesis especially in preclinical models. This review covers recent advances in our understanding of some adipokines in NAFLD and associated HCC.

Effects of weight loss on adipose visceral and subcutaneous tissue in overweight adults

BACKGROUND & AIMS

Weight loss is an important strategy for mitigating the complications of obesity. However, weight reduction does not provide detailed information on relative changes in bodily behaviors and in abdominal fat deposits (adipose visceral tissue (AVT) and adipose subcutaneous tissue (AST)). The aim of this study was to evaluate the effect of weight loss based on calorie restriction on AVT and AST in overweight individuals (1); to verify the metabolic benefits resulting from AVT reduction (2); and to the analyze the influence of covariates in AVT and AST reduction (3).

METHODS

Clinical intervention study involving overweight adult patients, seen at a public hospital in the Northeast of Brazil, who underwent three months of calorie restriction. AVT and AST were quantified using computed tomography at the baseline and at the end of a follow up.

RESULTS

51 patients were evaluated (50.2 ± 11.3 years old), for whom it was verified that a 5.8(±6.2)% weight reduction in the men resulted in a 11.2(±7.9)% reduction in AVT and 6.8(±11.2)% in AST. Among the women, a 4.1(±2.5)% reduction in initial weight resulted in a 11.1(±8.8)% decrease in AVT and 5.6(±7.4)% in AST. Simple linear regression showed that a reduction in AVT caused a 54.9% reduction in triglyceride concentrations in the men and a 12.2% reduction in cholesterol and 31.4% in triglyceride levels in women. Multiple regression identified different factors that influenced the reduction in visceral and subcutaneous fat. The predictive models explained 42.9% and 54.8% of the AVT reduction in the females and males, respectively; and 39.9% and 86.7% of the AST reduction in the females and males, respectively.

CONCLUSIONS

A modest 5% weight loss caused substantial AVT and AST mobilization, with potential benefits to cardiometabolic profile.

Murine models provide insight to the development of non-alcoholic fatty liver disease

Associated with the obesity epidemic, non-alcoholic fatty liver disease (NAFLD) has become the leading liver disease in North America. Approximately 30 % of patients with NAFLD may develop non-alcoholic steatohepatitis (NASH) that can lead to cirrhosis and hepatocellular carcinoma (HCC). Frequently animal models are used to help identify underlying factors contributing to NAFLD including insulin resistance, dysregulated lipid metabolism and mitochondrial stress. However, studying the inflammatory, progressive nature of NASH in the context of obesity has proven to be a challenge in mice. Although the development of effective treatment strategies for NAFLD and NASH is gaining momentum, the field is hindered by a lack of a concise animal model that reflects the development of liver disease during obesity and the metabolic syndrome. Therefore, selecting an animal model to study NAFLD or NASH must be done carefully to ensure the optimal application. The most widely used animal models have been reviewed highlighting their advantages and disadvantages to studying NAFLD and NASH specifically in the context of obesity.

Chronic stress induces steatohepatitis while decreases visceral fat mass in mice

Background

Prolonged stress leads over time to allostatic load on the body and is likely to exacerbate a disease process. Long-term of stress exposure is one of a risk factor for metabolism-related diseases such as obesity and type 2 diabetes. However, the relationship between chronic stress and non-alcoholic fatty liver disease (NAFLD) remain unknown.

Methods

To address the hypothesis that chronic stress associate to NAFLD development, we subjected C57bl/6 mice to electric foot shock and restraint stress for 12 weeks to set up chronic stress model. Then the serum and hepatic triglyceride (TG), total cholesterol (TC) were measured. Hepatic HE and Oil red O staining were used to specify the state of the NAFLD. To investigate whether inflammation takes part in the stress-induced NAFLD process, related visceral fat, serum and hepatic inflammatory factors were measured.

Results

We observed that chronic stress led to an overall increase of hepatic triglyceride and cholesterol while decreasing body weight and visceral fat mass. Microvesicular steatosis, lobular inflammation and ballooning degeneration were seen in stress liver section. This effect was correlated with elevated hepatic and serum inflammatory factors. Although the amount of visceral fat was decreased in stress group, various adipocytokines were elevated.

Conclusions

We showed that chronic stress is associated to NAFLD and chronic inflammation in visceral fat, though food intake and visceral fat mass were decreased. These results may contribute to better understanding of the mechanism from steatosis to steatohepatitis, and propose a novel insight into the prevention and treatment of NAFLD.

Adiponectin isoforms differentially affect gene expression and the lipidome of primary human hepatocytes

Adiponectin (APN) exerts multiple beneficial effects in obesity and protects from liver injury. Different APN isoforms circulate in serum, and here, the effect of low molecular weight (LMW) and higher molecular weight (HMW) APN on primary human hepatocytes (PHH) has been analyzed. APN is not detected in hepatocyte lysates; levels are strongly increased by HMW-APN, but not by LMW-APN, suggesting the distinct uptake/degradation of APN isoforms by PHH. Several genes with a role in fibrosis, glucose and lipid metabolism known to be regulated by HMW-APN are not affected by the LMW-isoform. Follistatin is reduced by HMW-APN and induced by LMW-APN in supernatants of PHH. Fibroblast growth factor 21 is repressed by both isoforms. Cellular triglycerides and cholesterol levels are not reduced by APN. Total phospholipids, including plasmalogens and sphingomyelins, are not changed upon APN incubation, while distinct species are either induced or repressed. Unexpectedly, total ceramide is increased by LMW-APN. Current data show that APN isoforms differentially affect hepatocyte gene expression, but do not grossly alter the hepatocyte lipidome.

c9,t11-Conjugated linoleic acid ameliorates steatosis by modulating mitochondrial uncoupling and Nrf2 pathway

Oxidative stress, hepatic steatosis, and mitochondrial dysfunction are key pathophysiological features of nonalcoholic fatty liver disease. A conjugated linoleic acid (CLA) mixture of cis9,trans11 (9,11-CLA) and trans10,cis12 (10,12-CLA) isomers enhanced the antioxidant/detoxifying mechanism via the activation of nuclear factor E2-related factor-2 (Nrf2) and improved mitochondrial function, but less is known about the actions of specific isomers. The differential ability of individual CLA isomers to modulate these pathways was explored in Wistar rats fed for 4 weeks with a lard-based high-fat diet (L) or with control diet (CD), and, within each dietary treatment, two subgroups were daily administered with 9,11-CLA or 10,12-CLA (30 mg/day). The 9,11-CLA, but not 10,12-CLA, supplementation to CD rats improves the GSH/GSSG ratio in the liver, mitochondrial functions, and Nrf2 activity. Histological examination reveals a reduction of steatosis in L-fed rats supplemented with both CLA isomers, but 9,11-CLA downregulated plasma concentrations of proinflammatory markers, mitochondrial dysfunction, and oxidative stress markers in liver more efficiently than in 10,12-CLA treatment. The present study demonstrates the higher protective effect of 9,11-CLA against diet-induced pro-oxidant and proinflammatory signs and suggests that these effects are determined, at least in part, by its ability to activate the Nrf2 pathway and to improve the mitochondrial functioning and biogenesis.

Upregulation of plasma insulin-like growth factor binding protein 2 levels after biliopancreatic diversion in humans

The biliopancreatic diversion surgery with duodenal switch (BPD-DS) is a surgical procedure that not only induces significant weight loss, but also promotes remission of diabetes. However, the mechanism responsible for this insulin-potentiating effect (both on sensitivity and production) is not yet clearly understood. The insulin-like growth factor (IGF) binding protein 2 (IGFBP-2) is a 36 kDa circulating protein that has been recently suggested to modulate insulin sensitization and fat accumulation. In humans, a low-circulating concentration of IGFBP-2 has been associated with obesity and insulin resistance. We thus tested the hypothesis that BPD-DS would trigger an increase in IGFBP-2 levels. Plasma IGFBP-2 was quantified by enzyme-linked immunosorbent assay in 77 severely obese men and women before and up to 1 year after BPD-DS surgery. Baseline IGFBP-2 levels were 159 ± 17 ng/ml. Plasma IGFBP-2 levels increased significantly as soon as 24 h after BPD-DS surgery and were further augmented at both 6 months and 1 year after the surgery, reaching 748 ± 65 ng/ml. Changes in IGFBP-2 concentrations were significantly and negatively associated with blood glucose, insulin, triglycerides, and total cholesterol levels. The present findings suggest that the rise in IGFBP-2 levels is associated with the improvements in glucose and lipid metabolism in the short- and long-term after BPD-DS. The mechanisms for the augmentation in IGFBP-2 after BPD-DS and its contribution to insulin sensitization remain to be elucidated.

Serum total adiponectin in nonalcoholic fatty liver disease: a systematic review and meta-analysis

Hypoadiponectinemia might represent a risk factor for nonalcoholic fatty liver disease (NAFLD). We performed a systematic review and meta-analysis to evaluate the serum total adiponectin levels in patients with simple nonalcoholic fatty liver (NAFL), those with nonalcoholic steatohepatitis (NASH), and controls. Data were extracted from PubMed, EMBASE, and Cochrane Central Register of Controlled Trials electronic databases (up to December 2009). The main outcome was the weighted mean differences (WMDs) in adiponectin between comparison groups. Twenty-eight studies were included in the systematic review. A meta-analysis of 27 studies that reported data on 2243 subjects (698 controls and 1545 patients with NAFLD) was performed. Controls had higher serum adiponectin compared with NAFL patients (12 studies, random-effects WMD [95% confidence interval {CI}] = 3.00 [1.57-4.43], I² = 80.4%) or NASH patients (19 studies, random-effects WMD [95% CI] = 4.75 [3.71-5.78], I² = 84.1%). The NASH patients demonstrated lower adiponectin compared with NAFL patients (19 studies, random-effects WMD [95% CI] = 1.81 [1.09-2.53], I² = 71.7%). By performing a meta-regression analysis, body mass index, age, sex, and type 2 diabetes mellitus failed to account for heterogeneity. However, the performance of liver biopsy on controls had significant effect on the outcome and accounted for 76.7%, 85.5%, and 22.8% of the between-study variance for comparisons between controls vs NAFLD, NAFL, and NASH patients, respectively. Based on liver histology, serum adiponectin levels are similar in NAFL patients and controls, but hypoadiponectinemia may play an important pathophysiological role in the progression from NAFL to NASH.

Comparison of DXA and water measurements of body fat following gastric bypass surgery and a physiological model of body water, fat, and muscle composition

Measurement of body composition changes following bariatric surgery is complicated because of the difficulty of measuring body fat in highly obese individuals that have increased photon absorption and are too large for the standard dual-energy X-ray absorptiometry (DXA) table. We reproducibly measured body composition from half-body DXA scans and compared the values of total body fat estimated from total body water (TBW) and DXA measurements before and after Roux-en-Y gastric bypass surgery (RYGB). DXA, TBW (deuterium dilution), extracellular water (ECW; bromide dilution), and intracellular water (ICW) measurement (by subtraction) were made before surgery and at 2 wk, 6 wk, 6 mo, and 12 mo after surgery. Twenty individuals completed baseline and at least four follow-up visits. DXA appeared to underestimate the fat and bone mass in extreme obesity (before surgery), whereas at 6 and 12 mo after surgery, the DXA and TBW fat measurements were similar. The ECW-to-ICW ratio was increased in obese individuals and increased slightly more after surgery. We describe a new model that explains this abnormal water composition in terms of the normal physiological changes that occur in body composition in obesity and weight loss. This model is also used to predict the muscle mass loss following RYGB.

Pharmacological and non-pharmacological treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) comprises a disease spectrum ranging from simple steatosis and steatohepatitis to cirrhosis. Based on its strongest risk factors namely visceral obesity and insulin resistance, NAFLD is thought to be the hepatic manifestation of the metabolic syndrome and is considered to be the most common liver disorder in Western countries. Pathophysiological mechanisms include an enlarged pool of fatty acids, subclinical inflammation, oxidative stress and imbalances of various adipocytokines such as adiponectin. Accordingly, targets for therapeutic interventions are miscellaneous: amelioration of obesity by pharmacological, surgical or lifestyle intervention has been evaluated with success in numerous, but not all studies. Some efficacy was reported for metformin and short-term glitazone treatment. In a large recently reported trial, vitamin E supplementation improved biochemical and histological markers in subjects with non-alcoholic steatohepatitis. Blockade of the endocannabinoid system has been proposed to be a promising target in NAFLD; however, very recently the cannabinoid receptor blocker rimonabant has been withdrawn because of central nervous system toxicity. Cytoprotective therapies and statins have been mainly ineffective in NAFLD. New but so far insufficiently studied therapeutic approaches include inhibitors of the renin-angiotensin system as well as incretin mimetics respectively.

A review of weight loss following Roux-en-Y gastric bypass vs restrictive bariatric surgery: impact on adiponectin and insulin

BACKGROUND

Bariatric surgery is a common procedure often used to ameliorate comorbidities associated with obesity, including type 2 diabetes. Substantial weight loss leads to alterations in inflammation and insulin sensitivity as well as numerous metabolic and physiologic pathways. Several inflammatory markers have been evaluated, yet adiponectin, an anti-inflammatory adipokine, has not been fully investigated. Adiponectin may play a key role as a mediator between obesity and inflammation, as lower blood levels are more commonly associated with obesity and type 2 diabetes and because adiponectin lessens insulin resistance. This review evaluates outcome variables from patients who underwent Roux-en-Y gastric bypass (RYGB) or restrictive bariatric surgery to compare and contrast any differential surgical impacts on weight loss, adiponectin, and insulin.

METHODS

A systematic literature review was conducted using a PubMed search. Published studies from 1999 to 2009 that measured blood levels of adiponectin and insulin in bariatric surgery patients prior to and at least 6 months after surgery were included.

RESULTS

Eighteen studies met inclusion criteria for evaluation. RYGB surgery compared to restrictive surgery led to significantly greater weight loss and improvements in adiponectin and insulin sensitivity. Despite significant weight loss, many patients did not achieve "healthy" body mass index or normalization of inflammatory markers.

CONCLUSIONS

While RYGB surgery appears to more favorably influence body weight and inflammatory markers, data are insufficient to fully understand the impact of bariatric surgery on changes in adiponectin and insulin and related health implications. Long-term research is needed to more thoroughly evaluate inflammatory outcomes following these two bariatric surgery procedures.

Serum aminotransferase changes with significant weight loss: sex and age effects

In obese subjects, the liver may be differentially affected by significant weight loss depending on as yet unknown factors. We explored clinical factors associated with serum alanine aminotransferase (ALT) changes during significant weight loss in a residential weight loss program. Clinical data from 362 adults who received a comprehensive weight loss intervention (ie, diets, physical fitness, and behavioral modification) in the program were analyzed. Serum ALT was used as a surrogate marker of liver injury. The ALT changes during the program were calculated to create study outcome categories (improvement, no change, or deterioration of ALT during significant weight loss). Variables of demography, lifestyle, and comorbidities at baseline, and total/rate of weight change during the program were explored for associations with the ALT change categories using multiple logistic regression models. Variation by sex was apparent among predictors of ALT deterioration; men with rapid weight loss and women with higher initial body mass index were more likely to experience ALT deterioration, whereas men with prior alcohol consumption were less likely to experience ALT deterioration even after adjusting for baseline ALT (Ps < .03). Variation by age was apparent among predictors of ALT improvement; younger patients with current smoking and older patients with rapid weight loss, diabetes or impaired fasting glucose, or sleep apnea or who followed a reduced-carbohydrate diet were less likely to experience ALT improvement (Ps < .05). A number of clinical factors influence ALT changes during weight loss in sex- and age-specific manners. The patterns that we detected may have pathophysiologic significance beyond the practical implications of our findings in clinical practice related to underlying changes in fat metabolism.

3,5-diiodo-l-thyronine, by modulating mitochondrial functions, reverses hepatic fat accumulation in rats fed a high-fat diet

BACKGROUND/AIMS

Mitochondrial dysfunction is central to the physiopathology of steatosis and/or non-alcoholic fatty liver disease. In this study on rats we investigated whether 3,5-diiodo-l-thyronine (T2), a biologically active iodothyronine, acting at mitochondrial level is able to reverse hepatic steatosis after its induction through a high-fat diet.

METHODS

Hepatic steatosis was induced by long-term high-fat feeding of rats for six weeks which were then fed the same high-fat diet for the next 4 weeks and were simultaneously treated or not treated with T2. Histological analyses were performed on liver sections (by staining with Sudan black B). In liver mitochondria fatty acid oxidation rate, mitochondrial efficiency (by measuring proton conductance) and mitochondrial oxidative stress (by measuring H(2)O(2) release, aconitase and SOD activity) were detected.

RESULTS

Stained sections showed that T2 treatment reduced hepatic fatty accumulation induced by a high-fat diet. At the mitochondrial level, the fatty acid oxidation rate and carnitine palmitoyl transferase activity were enhanced by T2 treatment. Moreover, by stimulating mitochondrial uncoupling, T2 caused less efficient utilization of fatty acid substrates and ameliorated mitochondrial oxidative stress.

CONCLUSION

These data demonstrate that T2, by activating mitochondrial processes, markedly reverses hepatic steatosis in vivo.

Ghrelin secretion is not reduced by increased fat mass during diet-induced obesity

Ghrelin is a stomach hormone that stimulates growth hormone (GH) secretion, adiposity, and food intake. Gastric ghrelin production and secretion are regulated by caloric intake; ghrelin secretion increases during fasting, decreases with refeeding, and is reduced by diet-induced obesity. The aim of the present study was to test the hypotheses that 1) an increase in body adiposity will play an inhibitory role in the reduction of gastric ghrelin synthesis and secretion during chronic ingestion of a high-fat (HF) diet and 2) chronic ingestion of an HF diet will suppress the rise in circulating ghrelin levels in response to acute fasting. Adult male Sprague-Dawley rats were fed a standard AIN-76A (approximately 5-12% of calories from fat) or an HF (approximately 45% of calories from fat) diet. The effect of increased adiposity on gastric ghrelin homeostasis was assessed by comparison of stomach ghrelin production and plasma ghrelin levels in obese and nonobese rats fed the HF diet. HF diet-fed, nonobese rats were generated by administration of triiodothyronine to lower body fat accumulation. Our findings indicate that an increased fat mass per se does not exert an inhibitory effect on ghrelin homeostasis during ingestion of the HF diet. Additionally, the magnitude of change in plasma ghrelin in response to fasting was not blunted, indicating that a presumed, endogenous signal for activation of ingestive behavior remains intact, despite excess stored calories in HF-fed rats.