Associates of change in liver fat content in the morbidly obese after laparoscopic gastric banding surgery

Bariatric Surgery and Liver Disease: General Considerations and Role of the Gut-Liver Axis

Weight loss is a therapeutic solution for many metabolic disorders, such as obesity and its complications. Bariatric surgery aims to achieve lasting weight loss in all patients who have failed after multiple dietary attempts. Among its many benefits, it has been associated with the regression of non-alcoholic fatty liver disease (NAFLD), which is often associated with obesity, with evidence of substantial improvement in tissue inflammation and fibrosis. These benefits are mediated not only by weight loss, but also by favorable changes in systemic inflammation and in the composition of the gut microbiota. Changes in microbial metabolites such as short-chain fatty acids (SCFAs), capable of acting as endocrine mediators, and bile acids (BAs) as well as modifications of the gut-brain axis, are among the involved mechanisms. However, not all bariatric surgeries show beneficial effects on the liver; those leading to malabsorption can cause liver failure or a marked worsening of fibrosis and the development of cirrhosis. Nevertheless, there are still many unclear aspects, including the extent of the benefits and the magnitude of the risks of bariatric surgery in cirrhotic patients. In addition, the usefulness and the safety of these procedures in patients who are candidates to or who have undergone liver transplant need solid supporting evidence. This paper aims to review literature data on the use of bariatric surgery in the setting of chronic liver disease.

Liver Fat Reduction After Gastric Banding and Associations with Changes in Insulin Sensitivity and β-Cell Function

OBJECTIVE

The aim of this study was to examine the relationship between changes in liver fat and changes in insulin sensitivity and β-cell function 2 years after gastric banding surgery.

METHODS

Data included 23 adults with the surgery who had prediabetes or type 2 diabetes for less than 1 year and BMI 30 to 40 kg/m² at baseline. Body adiposity measures including liver fat content (LFC), insulin sensitivity (M/I), and β-cell responses (acute, steady-state, and arginine-stimulated maximum C-peptide) were assessed at baseline and 2 years after surgery. Regression models were used to assess associations adjusted for age and sex.

RESULTS

Two years after surgery, all measures of body adiposity, LFC, fasting and 2-hour glucose, and hemoglobin A1c significantly decreased; M/I significantly increased; and β-cell responses adjusted for M/I did not change significantly. Among adiposity measures, reduction in LFC had the strongest association with M/I increase (r = -0.61, P = 0.003). Among β-cell measures, change in LFC was associated with change in acute C-peptide response to arginine at maximal glycemic potentiation adjusted for M/I (r = 0.66, P = 0.007). Significant reductions in glycemic measures and increase in M/I were observed in individuals with LFC loss >2.5%.

CONCLUSIONS

Reduction in LFC after gastric banding surgery appears to be an important factor associated with long-term improvements in insulin sensitivity and glycemic profiles in adults with obesity and prediabetes or early type 2 diabetes.

Increasing Liver Fat Is Associated With Incident Cardiovascular Risk Factors

Nonalcoholic fatty liver disease (NAFLD) is associated with increased liver- and cardiovascular disease (CVD)-related morbidity and mortality. In cross-sectional analyses, NAFLD clusters with several cardiometabolic traits including obesity,^1,2 hypertension,³ diabetes,¹ and dyslipidemia.³ However, liver fat is dynamic and changes over time. Aside from limited prior studies evaluating diet or exercise interventions, little is known about the association between changes in liver fat and the incidence of CVD risk factors. Additionally, previous studies often have limited follow-up; evaluate only select populations, such as individuals with obesity^4,5 or diabetes^6-8; and may not account for changes in weight or body mass index (BMI). The aim of the present study was to examine, in a longitudinal cohort, the natural history of liver fat change and the association with the incidence of multiple CVD risk factors.

Gamma-glutamyl transferase and cardiovascular risk in nonalcoholic fatty liver disease: The Gut and Obesity Asia initiative

BACKGROUND

Gamma-glutamyl transferase (GGT) is associated with the risk of cardiovascular disease (CVD) in the general population.

AIM

To identify the association of baseline GGT level and QRISK2 score among patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD).

METHODS

This was a retrospective study involving 1535 biopsy-proven NAFLD patients from 10 Asian centers in 8 countries using data collected by the Gut and Obesity in Asia (referred to as "GO ASIA") workgroup. All patients with available baseline GGT levels and all 16 variables for the QRISK2 calculation (QRISK2-2017; developed by researchers at the United Kingdom National Health Service; https://qrisk.org/2017/; 10-year cardiovascular risk estimation) were included and compared to healthy controls with the same age, sex, and ethnicity. Relative risk was reported. QRISK2 score > 10% was defined as the high-CVD-risk group. Fibrosis stages 3 and 4 (F3 and F4) were considered advanced fibrosis.

RESULTS

A total of 1122 patients (73%) had complete data and were included in the final analysis; 314 (28%) had advanced fibrosis. The median age (interquartile range [IQR]) of the study population was 53 (44-60) years, 532 (47.4%) were females, and 492 (43.9%) were of Chinese ethnicity. The median 10-year CVD risk (IQR) was 5.9% (2.6-10.9), and the median relative risk of CVD over 10 years (IQR) was 1.65 (1.13-2.2) compared to healthy individuals with the same age, sex, and ethnicity. The high-CVD-risk group was significantly older than the low-risk group (median [IQR]: 63 [59-67] vs 49 [41-55] years; P < 0.001). Higher fibrosis stages in biopsy-proven NAFLD patients brought a significantly higher CVD risk (P < 0.001). Median GGT level was not different between the two groups (GGT [U/L]: Median [IQR], high risk 60 [37-113] vs low risk 66 [38-103], P = 0.56). There was no correlation between baseline GGT level and 10-year CVD risk based on the QRISK2 score (r = 0.02).

CONCLUSION

The CVD risk of NAFLD patients is higher than that of healthy individuals. Baseline GGT level cannot predict CVD risk in NAFLD patients. However, advanced fibrosis is a predictor of a high CVD risk.

Niacin Ameliorates Hepatic Steatosis by Inhibiting De Novo Lipogenesis Via a GPR109A-Mediated PKC-ERK1/2-AMPK Signaling Pathway in C57BL/6 Mice Fed a High-Fat Diet

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. Hepatic de novo lipogenesis (DNL) has been suggested to contribute to the pathogenesis of NAFLD. Recent studies have demonstrated that niacin (NA) modulates hepatic DNL through GPR109A. However, the underlying mechanism remains largely unknown.

OBJECTIVES

This study aims to elucidate the potential molecular mechanism by which GPR109A inhibits hepatic DNL.

METHODS

C57BL/6 wild-type (WT) and Gpr109a knockout (KO) mice (male, 5 wk old) were fed a high-fat diet (60% energy from fat) firstly for 6 wk to generate a diet-induced obese model. Subsequently, they were randomly divided into 4 groups for the next 8-9 wk: WT mice with oral water [WT + vehile (VE)], WT mice with oral NA (50 mM, dissolved in water) (WT + NA), KO mice with oral water (KO + VE), and KO mice with oral NA (50 mM) (KO + NA). Mechanisms were examined in HepG2 cells. Body composition, liver histology, biomarkers of hepatic function, lipid accumulation, and lipid synthesis signals in HepG2 cells were measured.

RESULTS

Upon activation, GPR109A apparently protected against obesity and hepatic steatosis (P < 0.05). The concentrations of hepatic Tnf-α in the WT + NA group were about 50% of those in the WT + VE group (P < 0.05). The activities of serum alanine transaminase and aspartate transaminase were 26.7% and 53.5% lower in the WT + NA group than in the WT + VE group, respectively (P < 0.05). In HepG2 cells, activation of GPR109A resulted in remarkable inhibition of oleic acid-induced lipid accumulation via a protein kinase C-extracellular signal-regulated kinase-1/2-AMP-activated protein kinase signaling pathway.

CONCLUSIONS

NA inhibits hepatic lipogenesis in C57BL/6 mice through a GPR109A-mediated signaling pathway, consistent with the mechanistic studies in HepG2 cells, suggesting its potential for treatment of NAFLD and other fatty liver diseases.

Pilot study on longitudinal change in pancreatic proton density fat fraction during a weight-loss surgery program in adults with obesity

BACKGROUND

Quantitative-chemical-shift-encoded (CSE)-MRI methods have been applied to the liver. The feasibility and potential utility CSE-MRI in monitoring changes in pancreatic proton density fat fraction (PDFF) have not yet been demonstrated.

PURPOSE

To use quantitative CSE-MRI to estimate pancreatic fat changes during a weight-loss program in adults with severe obesity and nonalcoholic fatty liver disease (NAFLD). To explore the relationship of reduction in pancreatic PDFF with reductions in anthropometric indices.

STUDY TYPE

Prospective/longitudinal.

POPULATION

Nine adults with severe obesity and NAFLD enrolled in a weight-loss program.

FIELD STRENGTH/SEQUENCE

CSE-MRI fat quantification techniques and multistation-volumetric fat/water separation techniques were performed at 3 T.

ASSESSMENT

PDFF values were recorded from parametric maps colocalized across timepoints.

STATISTICAL TESTS

Rates of change of log-transformed variables across time were determined (linear-regression), and their significance assessed compared with no change (Wilcoxon test). Rates of change were correlated pairwise (Spearman's correlation).

RESULTS

Mean pancreatic PDFF decreased by 5.7% (range 0.7-17.7%) from 14.3 to 8.6%, hepatic PDFF by 11.4% (2.6-22.0%) from 14.8 to 3.4%, weight by 30.9 kg (17.3-64.2 kg) from 119.0 to 88.1 kg, body mass index by 11.0 kg/m2 (6.3-19.1 kg/m2 ) from 44.1 to 32.9 kg/m2 , waist circumference (WC) by 25.2 cm (4.0-41.0 cm) from 133.1 to 107.9 cm, HC by 23.5 cm (4.5-47.0 cm) from 135.8 to 112.3 cm, visceral adipose tissue (VAT) by 2.9 L (1.7-5.7 L) from 7.1 to 4.2 L, subcutaneous adipose tissue (SCAT) by 4.0 L (2.9-7.4 L) from 15.0 to 11.0 L. Log-transformed rate of change for pancreatic PDFF was moderately correlated with log-transformed rates for hepatic PDFF, VAT, SCAT, and WC (ρ = 0.5, 0.47, 0.45, and 0.48, respectively), although not statistically significant.

DATA CONCLUSION

Changes in pancreatic PDFF can be estimated by quantitative CSE-MRI in adults undergoing a weight-loss surgery program. Pancreatic and hepatic PDFF and anthropometric indices decreased significantly.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1092-1102.

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.

Clinical and Laboratory Associations with Persistent Hyperferritinemia in 373 Black Hemochromatosis and Iron Overload Screening Study Participants

BACKGROUND

373 black participants had elevated screening and post-screening serum ferritin (SF) (> 300 μg/L men; > 200 μg/L women).

MATERIAL AND METHODS

We retrospectively studied SF and post-screening age; sex; body mass index; transferrin saturation (TS); ALT; AST; GGT; elevated C-reactive protein; ß-thalassemia; neutrophils; lymphocytes; monocytes; platelets; metacarpophalangeal joint hypertrophy; hepatomegaly; splenomegaly; diabetes; HFE H63D positivity; iron/alcohol intakes; and blood/erythrocyte transfusion units. Liver disease was defined as elevated ALT or AST. We computed correlations of SF and TS with: age; body mass index; ALT; AST; GGT; C-reactive protein; blood cell counts; and iron/alcohol. We compared participants with SF > 1,000 and ≤ 1,000 μg/L and performed regressions on SF.

RESULTS

There were 237 men (63.5%). Mean age was 55 ± 13 (SD) y. 143 participants had liver disease (62 hepatitis B or C). There were significant correlations of SF: TS, ALT, AST, GGT, and monocytes (positive); and SF and TS with platelets (negative). 22 participants with SF > 1,000 μg/L had significantly higher median TS, ALT, and AST, and prevalences of anemia and transfusion > 10 units; and lower median platelets. Regression on SF revealed significant associations: TS; male sex; age; GGT; transfusion units (positive); and splenomegaly (negative) (p < 0.0001, 0.0016, 0.0281, 0.0025, 0.0001, and 0.0096, respectively). Five men with SF > 1,000 μg/L and elevated TS had presumed primary iron overload (hemochromatosis). Four participants had transfusion iron overload.

CONCLUSION

Persistent hyperferritinemia in 373 black adults was associated with male sex, age, TS, GGT, and transfusion. 2.4% had primary iron overload (hemochromatosis) or transfusion iron overload.

Epigenome-Wide Association Study Identifies Methylation Sites Associated With Liver Enzymes and Hepatic Steatosis

BACKGROUND & AIMS

Epigenetic mechanisms might be involved in the regulation of liver enzyme level. We aimed to identify CpG sites at which DNA methylation levels are associated with blood levels of liver enzymes and hepatic steatosis.

METHODS

We conducted an epigenome-wide association study in whole blood for liver enzyme levels, including gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), among a discovery set of 731 participants of the Rotterdam Study and sought replication in a non-overlapping sample of 719 individuals. Significant DNA methylation changes were further analyzed to evaluate their relation with hepatic steatosis. Expression levels of the top identified gene were measured in 9 human liver cell lines and compared with expression profiles of its potential targets associated with lipid traits. The candidate gene was subsequently knocked down in human hepatoma cells using lentiviral vectors expressing small hairpin RNAs.

RESULTS

Eight probes annotated to SLC7A11, SLC1A5, SLC43A1, PHGDH, PSORS1C1, SREBF1, ANKS3 were associated with GGT and 1 probe annotated to SLC7A11 was associated with ALT after Bonferroni correction (1.0 × 10^-7). No probe was identified for AST levels. Four probes for GGT levels including cg06690548 (SLC7A11), cg11376147 (SLC43A1), cg22304262 (SLC1A5), and cg14476101 (PHGDH), and 1 for ALT cg06690548 (SLC7A11) were replicated. DNA methylation at SLC7A11 was associated with reduced risk of hepatic steatosis in participants (odds ratio, 0.69; 95% CI= 0.55-0.93; P value: 2.7 × 10^-3). In functional experiments, SLC7A11 was highly expressed in human liver cells; its expression is positively correlated with expression of a panel of lipid-associated genes, indicating a role of SLC7A11 in lipid metabolism.

CONCLUSIONS

Our results provide new insights into epigenetic mechanisms associated with markers of liver function and hepatic steatosis, laying the groundwork for future diagnostic and therapeutic applications.

Nonalcoholic fatty liver disease and bariatric surgery: a comprehensive review

CONTEXT AND OBJECTIVE:

Nonalcoholic fatty liver disease (NAFLD) has been increasingly diagnosed worldwide and is now recognized as a source of public health concern. It comprises a wide spectrum of histological features that range from simple steatosis to severe forms of fibrosis, steatohepatitis and even cirrhosis. The impact of bariatric surgery on the course of NAFLD in individuals with obesity has been extensively studied.

DESIGN AND SETTING:

Narrative review; public university hospital.

METHODS:

A comprehensive review was conducted based on an online search on the electronic databases MEDLINE and LILACS using the MeSH terms "fatty liver" and "bariatric surgery".

RESULTS:

The exact mechanisms that lead to improvement in NAFLD following bariatric surgery are not completely understood. Since Roux-en-Y gastric bypass (RYGB) is the bariatric surgical procedure most performed worldwide, it is also the one from which the effects on NAFLD have been most studied, although there is also consistent evidence regarding the effects from gastric banding, sleeve gastrectomy and biliopancreatic diversions.

CONCLUSION:

According to the currently available evidence, bariatric surgery leads to significant improvement in NAFLD. Further research, especially by means of randomized controlled trials enrolling larger cohorts of individuals, is needed to determine the optimal procedure for this group of subjects.

Bariatric Surgery and Non-Alcoholic Fatty Liver Disease: a Systematic Review of Liver Biochemistry and Histology

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is becoming a leading cause of global liver disease that is associated with the rising prevalence of obesity worldwide. There is now increasing clinical and mechanistic evidence reporting on the metabolic and weight loss effects of bariatric surgery on improving NAFLD in obese patients.

OBJECTIVES

The aim of this paper was to quantify the effects of bariatric surgery on NAFLD by appraising the modulation between pre- and post-operative liver enzyme levels (as markers of liver injury) and liver histology.

METHODS

A systematic review of studies reporting pre-operative and post-operative liver enzymes or liver histology was done in obese patients with NAFLD undergoing bariatric surgery. Data were meta-analysed using random-effects modelling. Subgroup analysis, quality scoring and risk of bias were assessed.

RESULTS

Bariatric surgery is associated with a significant reduction in the weighted incidence of a number of histological features of NAFLD including steatosis (50.2 and 95 %CI of 35.5-65.0), fibrosis (11.9 and 95 %CI of 7.4-16.3 %), hepatocyte ballooning (67.7 and 95 %CI 56.9-78.5) and lobular inflammation (50.7 and 95 %CI 26.6-74.8 %). Surgery is also associated with a reduction in liver enzyme levels, with statistically significant reductions in ALT (11.36 u/l, 95 %CI 8.36-14.39), AST (3.91 u/l, 95 %CI 2.23-5.59), ALP (10.55 u/l, 95 %CI 4.40-16.70) and gamma-GT (18.39 u/l, 95 %CI 12.62-24.16). Heterogeneity in results was high.

CONCLUSIONS

Bariatric surgery is associated with a significant improvement in both histological and biochemical markers of NAFLD. Future studies must focus on higher levels of evidence to better identify the benefits of bariatric surgery on liver disease in order to enhance future treatment strategies in the management of NAFLD.

A Randomized Controlled Trial of the Effects of an Almond-enriched, Hypocaloric Diet on Liver Function Tests in Overweight/Obese Women

Background:

Gradual weight reduction has been shown to be associated with improvements in liver enzymes. However, some evidence demonstrated that liver enzymes may transiently increase immediately after a diet-induced weight loss.

Objectives:

This study was designed to assess the effects of a hypocaloric, almond-enriched diet (AED) compared with a hypocaloric nut-free diet (NFD) on liver function tests in the context of a three-month weight reduction program in overweight/obese women.

Patients and Methods:

This randomized controlled clinical trial was registered at Iranian Registry of Clinical Trials with ID number of IRCT2013062313751N1. Overweight and obese Iranian women [n = 108; age = 42.7 y, body mass index = 29.6 kg/m²] were randomly assigned to consume an AED or NFD. The carefully planned hypocaloric diets were identical for both groups except for the AED group who consumed 50 grams of almonds daily for three months. Anthropometric measurements and laboratory measurements including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and γ-glutamyltransferase (GGT) were assessed before and immediately after the intervention.

Results:

Of 108 participants, 50 women in AED group and 50 women in NFD group completed the protocol of the study (response rate: 92.6 %). The AED led to a median weight loss of 3.79 kg (interquartile range: 4.4 kg). Significant decreases within AED and NFD were observed in ALT (-16.6 ± 16.3 and -11.7 ± 16.8, P < 0.001, respectively). Similar significant decreases were observed in AST (-13.6 ± 15.7 and -7.7 ± 16.1; P < 0.001, respectively). The decrease in GGT was also significant in both groups (-11.4 ± 21.6 and -6.2 ± 19.8; P < 0.001 respectively). ALT, AST and GGT decreased significantly in the AED group compared to the NFD group (P < 0.001).

Conclusions:

AED improved liver enzymes in obese women. However, mild, transient increases in ALT and AST values can be observed immediately after an NFD in women.

Low- and high-density lipoprotein subclasses in subjects with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with increased cardiometabolic risk. Although dyslipidemia represents a key factor in this disease, its impact on serum levels of distinct lipoprotein subfractions is largely unknown.

OBJECTIVE

To assess the full low-density lipoprotein (LDL) and high-density lipoprotein (HDL) profiles in patients with NAFLD.

METHODS

Seven LDL and 10 HDL subfractions were assessed by gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA) in men with biopsy proven NAFLD (simple steatosis [n = 17, age, 34 ± 7 years] and nonalcoholic steatohepatitis [NASH; n = 24, age, 32 ± 6 years]). Exclusion criteria included robust alcohol consumption, infection with hepatitis B or C virus, body mass index ≥ 40 kg/m(2), diabetes mellitus, and hypertension.

RESULTS

Compared with simple steatosis, NASH patients had similar body mass index, homeostasis model assessment of insulin resistance index and plasma lipids, with increased levels of both aspartate aminotransferase and alanine transaminase. NASH subjects had lower levels of larger LDL1 (10 ± 4 vs 13 ± 4%, P = .010) and increased smaller LDL3 and LDL4 particles (9 ± 5 vs 5 ± 5%, P = .017 and 3 ± 3 vs 1 ± 2%, P = .012, respectively). No changes were found in the HDL subclass profile. By multiple regression analysis, we found that NASH was associated only with increased levels of LDL3 (P = .0470).

CONCLUSIONS

The increased levels of small, dense LDL3 and LDL4 in NASH may help to at least partly explain the increased risk for atherosclerosis and cardiovascular diseases in these patients.

Ultrasonic integrated backscatter in assessing liver steatosis before and after liver transplantation

BACKGROUND

Liver steatosis affects 20%-30% of adults. Because of the increasing gap between graft supplies and demands, livers with steatosis are frequently used in liver transplantation. But severely steatotic liver grafts are associated with a high risk of intraoperative and postoperative complications. Accurate assessment of fat content of donor livers and monitoring of the extent of steatosis in recipients are required for liver transplantation. The present study aimed to determine the correlation between liver echogenicity and fat content, and to evaluate the use of an ultrasonic integrated backscatter system (IBS) in the assessment of changes in fat content after liver transplantation.

METHODS

Seventy-nine consecutive patients receiving liver grafts from living donors were evaluated in our center. Of these recipients, 67 survived for more than two years and were included in this study. Each liver graft was evaluated with IBS and ultrasound before operation and the fat content was estimated. The fat content of the grafts in the recipients was again assessed with ultrasound at 18 months after surgery.

RESULTS

A correlation was detected between each graft's IBS value and its fat content (P=0.001). The IBS value in fatty grafts with various degrees of steatosis was significantly decreased in 3 (P=0.02), 12, 15 and 18 (P=0.001) months after orthotopic liver transplantation. The IBS value returned to normal in all patients in 18 months after liver transplantation.

CONCLUSIONS

Decreased fat content in steatotic grafts can be observed in all recipients. Ultrasonic IBS is useful in determining the steatotic degree of grafts in donors as well as in monitoring the grafts after liver transplantation.

Liver steatosis (LS) evaluated through chemical-shift magnetic resonance imaging liver enzymes in morbid obesity; effect of weight loss obtained with intragastric balloon gastric banding

The aim of this study was to evaluate in morbid obesity clinical and metabolic effects related to weight loss on liver steatosis (LS), measured through chemical-shift magnetic resonance imaging (MRI) and liver enzymes. Forty obese subjects (8 M/32 W; BMI 42.8 ± 7.12 kg/m(2), mean ± SD) were evaluated for LS through ultrasound (US-LS), chemical-shift MRI (MRI-LS), liver enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (GGT), alkaline phosphatase (ALP)], anthropometric parameters [weight, BMI, waist circumference (WC)], lipids, insulin, insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), oral glucose tolerance test, and body composition [fat mass (FM) and fat-free mass (FFM) at bio-impedance analysis (BIA)]. Anthropometric measures, MRI-LS, BIA, and biochemical parameters were reevaluated 6 months later in 18 subjects undergoing restrictive bariatric approach, i.e., intragastric balloon (BIB, n = 13) or gastric banding (LAGB, n = 5), and in 13 subjects receiving hypocaloric diet. At baseline, US-LS correlates only with MRI-LS, and the latter correlates with ALT, AST, and GGT. After 6 months, subjects undergoing BIB or LAGB had significant changes of BMI, weight, WC, ALT, AST, GGT, ALP, HbA1c, insulin, HOMA-IR, FM, FFM, and MRI-LS. Diet-treated obese subjects had no significant change of any parameter under study; change of BMI, fat mass, and fat-free mass was significantly greater in LAGB/BIB subjects than in diet-treated subjects. Change of MRI-LS showed a significant correlation with changes in weight, BMI, WC, GGT, ALP, and basal MRI-LS. Significant weight loss after BIB or LAGB is associated with decrease in chemical-shift MRI-LS and with reduction in liver enzymes; chemical-shift MRI and liver enzymes allow monitoring of LS in follow-up studies.

Whole body fat: content and distribution

Obesity and its co-morbidities, including type II diabetes, insulin resistance and cardiovascular diseases, have become one of the biggest health issues of present times. The impact of obesity goes well beyond the individual and is so far-reaching that, if it continues unabated, it will cause havoc with the economies of most countries. In order to be able to fully understand the relationship between increased adiposity (obesity) and its co-morbidity, it has been necessary to develop proper methodology to accurately and reproducibly determine both body fat content and distribution, including ectopic fat depots. Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) have recently emerged as the gold-standard for accomplishing this task. Here, we will review the use of different MRI techniques currently being used to determine body fat content and distribution. We also discuss the pros and cons of MRS to determine ectopic fat depots in liver, muscle, pancreas and heart and compare these to emerging MRI techniques currently being put forward to create ectopic fat maps. Finally, we will discuss how MRI/MRS techniques are helping in changing the perception of what is healthy and what is normal and desirable body-fat content and distribution.

Evaluation of the Swedish adjustable gastric band VC (SAGB-VC) in an Australian population: early results

BACKGROUND

The Swedish adjustable gastric band VC (SAGB-VC) has been in use in Australia since 2007. We evaluated its efficacy and safety.

METHODS

We retrospectively analyzed the prospective clinical data of patients who received the implant between November 2007 and June 2009 at 3 Australian bariatric centres.

RESULTS

In all, 1176 patients (mean age 45.9 [standard deviation (SD) 12.3] yr, mean body mass index 43.4 [SD 7.6]) received the SAGB-VC. At a mean follow-up of 11 (SD 3) months, weight reduced by a mean of 18.4 (SD 11.1) kg with an excess weight loss of 37.8% (SD 19.9%). Body mass index decreased (from mean 43.4 [SD 7.7] to mean 36.7 [SD 6.5], p < 0.001). Type 2 diabetes (T2DM) was reported in 167 patients and hypertension in 373. Improvement occurred in 73.5% of patients with T2DM and 31% with hypertension, with patient-reported reduction or cessation of medication. Metabolic syndrome indices improved during follow-up: high-density lipoprotein cholesterol (mean 1.3 [SD 0.3] v. mean 1.4 [SD 0.3] mmol/L, p < 0.001), triglycerides (mean 1.6 [SD 0.8] v. mean 1.3 [SD 0.7] mmol/L, p < 0.001), waist circumference (men 141 [SD 103] to 121 [SD 15] cm, women 117 [SD 14] to 105 [SD 14] cm, both p < 0.001), C-reactive protein (90.5 [SD 75.2] v. 53.3 [SD 61.9] nmol/L, p < 0.001). The complication rate was 4.2%.

CONCLUSION

The SAGB-VC is safe and effective for treating obesity and its comorbidities. The results are reproducible in separate Australian centres and consistent with published literature.

Insulin resistance and bariatric surgery

The objective of this article is to systematically review the changes in insulin resistance after various types of bariatric surgical procedures. A Pubmed and EMBASE search for studies measuring insulin resistance before and after bariatric surgery was done and all original research articles from 1980 to present (2011) were included. Only the currently widely performed bariatric procedures were included. A meta-analysis of change in HOMA-IR was conducted, grouping studies with similar duration of follow-up. The percentage decrease in HOMA-IR at <=2 weeks, 1 month, 3 months, 6 months, 12 months and >16-18 months was found to be (mean ± standard error) -33.48 ± 5.78, -46.43 ± 6.99, -38.79 ± 9.64, -58.62 ± 7.38, -44.91 ± 7.98 and -67.04 ± 10.78%, respectively. RYGB (gastric bypass) and BPD (biliopancreatic diversion) produced a significant decrease in insulin resistance at 2 weeks after surgery, while LSG (sleeve gastrectomy) was strongly trending. LSG produced an earlier decrease in insulin resistance when compared to LAGB (gastric banding). RYGB, BPD and LSG produce an early decrease in insulin resistance through yet unknown mechanisms.

Type 2 diabetes, bariatric surgery and the risk of subsequent gestational diabetes

Women with pre-existing abnormal glucose regulation are certain to develop gestational diabetes in pregnancy and pre-gestational type 2 diabetes will become more difficult to control. However, an increasing number of women with type 2 diabetes have had bariatric surgery. In this group, the effect of pregnancy on glucose metabolism is unknown. We report two women with type 2 diabetes who underwent laparoscopic gastric bypass surgery with normalization of plasma glucose levels. During subsequent pregnancy, maternal blood glucose levels remained completely normal throughout. This is remarkable given the predisposition to abnormal glucose tolerance and the ongoing obesity, in the face of the insulin resistance of pregnancy. Women with prior type 2 diabetes reversed by gastric bypass surgery are not at high risk for gestational diabetes.

Hepatic steatosis in morbidly obese patients undergoing gastric bypass surgery: assessment with open-system 1H-MR spectroscopy

OBJECTIVE

The purpose of this study was to assess, with histopathologic control, the use of open-system 1-T (1)H MR spectroscopy for the evaluation of hepatic steatosis in morbidly obese patients undergoing gastric bypass surgery.

SUBJECTS AND METHODS

Patients underwent (1)H MR spectroscopy (MRS) for the assessment of steatosis before and 3 months after surgery. Liver biopsy was performed during surgery. Hepatic steatosis was expressed as the ratio of fat peak area to cumulative water and fat peak areas. Histopathologic percentage of steatosis was graded as none (0-5%), mild (5-33%), moderate (33-66%), or severe (> 66%). The accuracy of (1)H-MRS and Spearman correlation coefficient were calculated. Differences between groups were assessed with the Wilcoxon signed rank and Mann-Whitney tests.

RESULTS

The study included 38 patients (median age, 45.5 years; median body mass index, 47.7). Before surgery, median steatosis measured with (1)H-MRS was 5.8%. The accuracy of (1)H-MRS was 89% (32/36), and the (1)H-MRS findings correlated with the histopathologic assessment of steatosis (r = 0.85, p < 0.001). With (1)H-MRS, no steatosis was discriminated from mild steatosis (p = 0.011), mild was discriminated from moderate steatosis (p < 0.001), and moderate was discriminated from severe steatosis (p = 0.021). Three months after surgery, steatosis had decreased to 3.1% (p < 0.001). The prevalence of hepatic steatosis measured with (1)H-MRS decreased from 53% to 32%.

CONCLUSION

In the care of morbidly obese patients undergoing assessment of hepatic steatosis and changes in steatosis after gastric bypass surgery, (1)H-MRS with an open 1-T MRI system is feasible. Measurements of hepatic fat with (1)H-MRS are accurate and correlate with clinical and histopathologic results.

Quantification of liver fat with magnetic resonance imaging

Intracellular fat accumulation is common feature of liver disease. Intracellular fat (steatosis) is the histologic hallmark of nonalcoholic fatty liver disease but also may occur with alcohol abuse, viral hepatitis, HIV and genetic lipodystrophies, and chemotherapy. This article reviews emerging MR imaging techniques that attempt to quantify liver fat. The content provides an overview of fatty liver disease and diseases where fat is an important disease feature. Also discussed is the current use and limitation of nontargeted biopsy in diffuse liver disease and why quantitative noninvasive biomarkers of liver fat would be beneficial.

Liver enzymes, nonalcoholic fatty liver disease, and incident cardiovascular disease: a narrative review and clinical perspective of prospective data

In recent years, a strong link has been established between nonalcoholic fatty liver disease (NAFLD) and the pathogenesis of type 2 diabetes mellitus. The potential role of NAFLD in cardiovascular disease (CVD) has also attracted interest. Published studies have tended to use biochemical and imaging surrogate markers of NAFLD, such as elevated gamma glutamyl transpeptidase (GGT) and alanine aminotransferase (ALT) and fatty liver on ultrasound, when investigating associations with incident CVD events. Positive associations between both baseline GGT and temporal change in GGT, as well as cardiovascular events and cardiovascular mortality independent of alcohol intake, have been reported in several prospective studies. However, adjustment for confounders is often incomplete, and there is scant evidence of improvement in cardiovascular risk prediction beyond established risk scores when incorporating such data. There also appears to be a strong and underrecognized age interaction, with associations between GGT and incident coronary heart disease (CHD) being strong in young individuals but relatively weak in the elderly. By contrast, ALT appears to be only weakly associated with incident CHD and may exhibit a U-shaped association with total mortality. Finally, although some studies have linked imaging-defined and biopsy-confirmed NAFLD with CVD risk, the evidence is inconsistent, with few incident events and/or insufficient potential confounders.

CONCLUSION

A diagnosis of NAFLD is insufficient to consider patients as being at high risk for CVD. The presence of NAFLD should be a clear indication for diabetes screening, but cardiovascular risk screening should be performed with the use of existing risk calculators and should be guided by established cardiovascular risk factors.

Liver fat content determined by magnetic resonance imaging and spectroscopy

Hepatic steatosis as the most prevalent liver disorder can either be related to alcoholic liver disease (ALD) or non-alcoholic fatty liver disease (NAFLD). In both conditions, hepatocytes excessively accumulate fat-containing vacuoles within their cytoplasm, which is the key histological feature. In contrast to ALD, NAFLD is commonly associated with metabolic syndrome, obesity and insulin resistance. To determine increased liver fat content, liver biopsy is currently considered the gold standard. Besides the invasive technique, various other non-invasive techniques have been developed, such as ultrasound, computed tomography (CT), magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) based methods. Among these techniques, ultrasound and CT provide only qualitative information about hepatic steatosis, whereas MRS- or MRI-based methods are able to determine even small amounts of fat accurately. These non-invasive magnetic resonance techniques have already proven their great potential, especially in longitudinal and cross-sectional studies regarding various metabolic conditions and medical treatment regimens. In this review, the most common, non-invasive MRS/MRI techniques for assessment of intrahepatic lipid content are described with their inherent advantages and limitations.

Influence of visceral obesity and liver fat on vascular structure and function in obese subjects

Endothelial dysfunction and increased intima-media thickness (IMT) have been found in obese patients. Both regional fat distribution and liver steatosis may influence these markers of subclinical atherosclerosis. We sought to determine the interrelationships of endothelial function, carotid IMT, visceral and subcutaneous adipose tissue accumulation, and liver steatosis in severely obese subjects. In 64 severely obese patients (BMI 42.3 +/- 4.3 kg/m(2)), we determined (i) endothelial function as flow-mediated dilation (FMD) of the brachial artery, (ii) carotid IMT, (iii) visceral fat diameter, and (iv) degree of liver steatosis using ultrasound. FMD was associated inversely with visceral fat diameter and degree of steatosis (r = -0.577, P < 0.0001 and r = -0.523, P < 0.0001, respectively). Carotid IMT correlated with visceral fat mass (r = 0.343, P = 0.007) but not with liver steatosis. After adjustment for conventional cardiovascular risk factors, FMD was predicted independently by the visceral fat diameter, age, and sex (r(2) = 0.48, P < 0.0001), but not by the degree of liver steatosis or plasma adiponectin levels. In contrast, age and sex were the only predictors of IMT (r(2) = 0.33, P < 0.001). In obese patients, visceral fat diameter is a major determinant of endothelial dysfunction, independent of traditional risk factors or the degree of liver steatosis and plasma adiponectin. Measurement of visceral fat diameter by ultrasound is a novel and simple method to identify subjects with an increased risk for atherosclerosis within an obese population.