Metabolic, hormonal, oxidative, and inflammatory factors in pediatric obesity-related liver disease

Practical approach to quantitative liver and pancreas MRI in children

Quantitative abdominal magnetic resonance imaging (MRI) offers non-invasive, objective assessment of diseases in the liver, pancreas, and other organs and is increasingly being used in the pediatric population. Certain quantitative MRI techniques, such as liver proton density fat fraction (PDFF), R2* mapping, and MR elastography, are already in wide clinical use. Other techniques, such as liver T1 mapping and pancreas quantitative imaging methods, are emerging and show promise for enhancing diagnostic sensitivity and treatment monitoring. Quantitative imaging techniques have historically required a breath-hold, making them more difficult to implement in the pediatric population. However, technological advances, including free-breathing techniques and compressed sensing imaging, are making these techniques easier to implement. The purpose of this article is to review current liver and pancreas quantitative techniques and to provide a practical guide for implementing these techniques in pediatric practice. Future directions of liver and pancreas quantitative imaging will be briefly discussed.

Non-invasive diagnosis of papillary thyroid microcarcinoma using a novel metabolomics analysis of urine

BACKGROUND

The severity of thyroid cancer is judged on the basis of histologic and clinical features. A limited number of studies have considered urinary metabolite signatures for its diagnosis, and no reliable urinary metabolite biomarkers have been proposed. This diagnostic method would be particularly valuable because of its non-invasive nature.

METHOD

A nuclear magnetic resonance (NMR)-based metabolomics approach was used as the analytical platform to study the urine samples of patients with PTMC. Urine samples collected from 41 PTMC patients, 52 healthy subjects, and 13 patients with benign tumors were analyzed using 1H-NMR spectroscopy to identify metabolic changes. PLS-DA, or partial least squares discriminant analysis, was used to analyze the NMR spectra. A double cross-validation method and randomization tests were used to validate PLS-DA models.

RESULTS

Clear discriminations between PTMC patients and healthy controls, as well as between PTMC patients and patients with benign tumors were obtained. Collectively, pi-methyhistidine, trimethylamine, myo-inositol, acetate, suberate, azelate, mannitol, tau-methylhistine, ascorbate, 3-aminoisobutyric acid, 2-oxoglutarate, and methanol contributed to the discrimination. Apart from myo-inositol and methanol, all of these metabolites exhibited increased levels in the urine samples of PTMC patients as compared to that of patients with benign tumors.

CONCLUSIONS

The application of this NMR-based metabolomics approach allowed the detection of anomalous metabolic traits directly connected PTMC, potentially yielding a more sensitive and comprehensive diagnostic results for PTMC.

Pro- and anti-inflammatory cytokines are the game-changers in childhood obesity-associated metabolic disorders (diabetes and non-alcoholic fatty liver diseases)

Childhood obesity is a chronic inflammatory epidemic that affects children worldwide. Obesity affects approximately 1 in 5 children worldwide. Obesity in children can worsen weight gain and raise the risk of obesity-related comorbidities like diabetes and non-alcoholic fatty liver disease (NAFLD). It can also negatively impact the quality of life for these children. Obesity disrupts immune system function, influencing cytokine (interleukins) balance and expression levels, adipokines, and innate and adaptive immune cells. The altered expression of immune system mediators, including interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-17 (IL-17), interleukin-18 (IL-18), transforming growth factor (TGF), tumor necrosis factor (TNF), and others, caused inflammation, progression, and the development of pediatric obesity and linked illnesses such as diabetes and NAFLD. Furthermore, anti-inflammatory cytokines, including interleukin-2 (IL-2), have been shown to have anti-diabetes and IL-1 receptor antagonist (IL-1Ra) anti-diabetic and pro-NAFLFD properties, and interleukin-10 (IL-10) has been shown to have a dual role in managing diabetes and anti-NAFLD. In light of the substantial increase in childhood obesity-associated disorders such as diabetes and NAFLD and the absence of an effective pharmaceutical intervention to inhibit immune modulation factors, it is critical to consider the alteration of immune system components as a preventive and therapeutic approach. Thus, the current review focuses on the most recent information regarding the influence of pro- and anti-inflammatory cytokines (interleukins) and their molecular mechanisms on pediatric obesity-associated disorders (diabetes and NAFLD). Furthermore, we discussed the current therapeutic clinical trials in childhood obesity-associated diseases, diabetes, and NAFLD.

Glycerol as a precursor for hepatic de novo glutathione synthesis in human liver

BACKGROUND

Glycerol is a substrate for gluconeogenesis and fatty acid esterification in the liver, processes which are upregulated in obesity and may contribute to excess fat accumulation. Glycine and glutamate, in addition to cysteine, are components of glutathione, the major antioxidant in the liver. In principle, glycerol could be incorporated into glutathione via the TCA cycle or 3-phosphoglycerate, but it is unknown whether glycerol contributes to hepatic de novo glutathione biosynthesis.

METHODS

Glycerol metabolism to hepatic metabolic products including glutathione was examined in the liver from adolescents undergoing bariatric surgery. Participants received oral [U-13C3]glycerol (50 mg/kg) prior to surgery and liver tissue (0.2-0.7g) was obtained during surgery. Glutathione, amino acids, and other water-soluble metabolites were extracted from the liver tissue and isotopomers were quantified with nuclear magnetic resonance spectroscopy.

RESULTS

Data were collected from 8 participants (2 male, 6 female; age 17.1 years [range 14-19]; BMI 47.4 kg/m2 [range 41.3-63.3]). The concentrations of free glutamate, cysteine, and glycine were similar among participants, and so were the fractions of 13C-labeled glutamate and glycine derived from [U-13C3]glycerol. The signals from all component amino acids of glutathione - glutamate, cysteine and glycine - were strong and analyzed to obtain the relative concentrations of the antioxidant in the liver. The signals from glutathione containing [13C2]glycine or [13C2]glutamate derived from the [U-13C3]glycerol drink were readily detected, and 13C-labelling patterns in the moieties were consistent with the patterns in corresponding free amino acids from the de novo glutathione synthesis pathway. The newly synthesized glutathione with [U-13C3]glycerol trended to be lower in obese adolescents with liver pathology.

CONCLUSIONS

This is the first report of glycerol incorporation into glutathione through glycine or glutamate metabolism in human liver. This could represent a compensatory mechanism to increase glutathione in the setting of excess glycerol delivery to the liver.

Effects of Probiotic Supplementation during Pregnancy on the Future Maternal Risk of Metabolic Syndrome

Probiotics are live microorganisms that induce health benefits in the host. Taking probiotics is generally safe and well tolerated by pregnant women and their children. Consumption of probiotics can result in both prophylactic and therapeutic effects. In healthy adult humans, the gut microbiome is stable at the level of the dominant taxa: Bacteroidetes, Firmicutes and Actinobacteria, and has a higher presence of Verrucomicrobia. During pregnancy, an increase in the number of Proteobacteria and Actinobacteria phyla and a decrease in the beneficial species Roseburia intestinalis and Faecalibacterium prausnitzii are observed. Pregnancy is a "window" to the mother's future health. The aim of this paper is to review studies assessing the potentially beneficial effects of probiotics in preventing the development of diseases that appear during pregnancy, which are currently considered as risk factors for the development of metabolic syndrome, and consequently, reducing the risk of developing maternal metabolic syndrome in the future. The use of probiotics in gestational diabetes mellitus, preeclampsia and excessive gestational weight gain is reviewed. Probiotics are a relatively new intervention that can prevent the development of these disorders during pregnancy, and thus, would reduce the risk of metabolic syndrome resulting from these disorders in the mother's future.

Rotating night shift work, sleep duration and elevated gamma-glutamyl transpeptidase among steelworkers: cross-sectional analyses from a Chinese occupational cohort

OBJECTIVES

This study aimed to evaluate the separate and combined effects of rotating night shift work and lifestyle factors with elevated gamma-glutamyl transpeptidase (GGT) among steelworkers.

DESIGN, SETTING AND PARTICIPANTS

This cross-sectional study used the baseline information from a Chinese occupational cohort. The in-service workers of the production department of Tangsteel Company who participated in the occupational health examination in Tangshan from February to June 2017 were selected as the research objects.

MAIN OUTCOME MEASURES

The separate and combined effects of rotating night shift work and lifestyle factors with elevated GGT among steelworkers.

RESULTS

The information of 7031 subjects from the production department of Tangsteel Company was analysed. Results showed that the current shift workers and the workers with the duration of night shifts>19 years, the cumulative number of night shifts>1774 nights, the average frequency of night shifts≤7 nights/month and the average frequency of night shifts>7 nights/month had elevated odds of elevated GGT, compared with those who never worked night shifts, and ORs, (95% CIs) were 1.39, (1.10 to 1.75), 1.46, (1.15 to 1.86), 1.46, (1.15 to 1.85), 1.34, (1.04 to 1.73) and 1.37, (1.09 to 1.74) after adjustment for potential confounders. The independent effect of shorter sleep duration (<7 hours/day) on elevated GGT was not statistically significant. Among workers who had shorter sleep duration, the association between rotating night shift work and elevated GGT was statistically significant, but no associations were found among workers with the sleep duration of ≥7 hours/day. In addition, other lifestyle factors affected the association between rotating night shift work and elevated GGT.

CONCLUSIONS

Rotating night shift work is associated with elevated GGT among steelworkers. In particular, the effect of rotating night shift work on elevated GGT was affected by sleep duration and other lifestyle factors.

Non-Alcoholic Fatty Liver Disease in Obese Youth With Insulin Resistance and Type 2 Diabetes

Currently, Non-Alcoholic Fatty Liver Disease (NAFLD) is the most prevalent form of chronic liver disease in children and adolescents worldwide. Simultaneously to the epidemic spreading of childhood obesity, the rate of affected young has dramatically increased in the last decades with an estimated prevalence of NAFLD of 3%-10% in pediatric subjects in the world. The continuous improvement in NAFLD knowledge has significantly defined several risk factors associated to the natural history of this complex liver alteration. Among them, Insulin Resistance (IR) is certainly one of the main features. As well, not surprisingly, abnormal glucose tolerance (prediabetes and diabetes) is highly prevalent among children/adolescents with biopsy-proven NAFLD. In addition, other factors such as genetic, ethnicity, gender, age, puberty and lifestyle might affect the development and progression of hepatic alterations. However, available data are still lacking to confirm whether IR is a risk factor or a consequence of hepatic steatosis. There is also evidence that NAFLD is the hepatic manifestation of Metabolic Syndrome (MetS). In fact, NAFLD often coexist with central obesity, impaired glucose tolerance, dyslipidemia, and hypertension, which represent the main features of MetS. In this Review, main aspects of the natural history and risk factors of the disease are summarized in children and adolescents. In addition, the most relevant scientific evidence about the association between NAFLD and metabolic dysregulation, focusing on clinical, pathogenetic, and histological implication will be provided with some focuses on the main treatment options.

Oxidative Stress in Non-alcoholic Fatty Liver Disease. An Updated Mini Review

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it remains still orphan of an adequate therapeutic strategy. Herein we focus on the interplay between oxidative stress (OS) and the other causal pathogenetic factors. Different reactive oxygen species (ROS) generators contribute to NAFLD inflammatory and fibrotic progression, which is quite strictly linked to the lipotoxic liver injury from fatty acids and/or a wide variety of their biologically active metabolites in the context of either a two-hit or a (more recent) multiple parallel hits theory. An antioxidant defense system is usually able to protect hepatic cells from damaging effects caused by ROS, including those produced into the gastrointestinal tract, i.e., by-products generated by usual cellular metabolic processes, normal or dysbiotic microbiota, and/or diet through an enhanced gut–liver axis. Oxidative stress originating from the imbalance between ROS generation and antioxidant defenses is under the influence of individual genetic and epigenetic factors as well. Healthy diet and physical activity have been shown to be effective on NAFLD also with antioxidant mechanisms, but compliance to these lifestyles is very low. Among several considered antioxidants, vitamin E has been particularly studied; however, data are still contradictory. Some studies with natural polyphenols proposed for NAFLD prevention and treatment are encouraging. Probiotics, prebiotics, diet, or fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors will likely assist in further selecting the treatment that could work best for a specific patient.

Urinary Metabolomics in Pediatric Obesity and NAFLD Identifies Metabolic Pathways/Metabolites Related to Dietary Habits and Gut-Liver Axis Perturbations

To get insight into still elusive pathomechanisms of pediatric obesity and non-alcoholic fatty liver disease (NAFLD) we explored the interplay among GC-MS studied urinary metabolomic signature, gut liver axis (GLA) abnormalities, and food preferences (Kid-Med). Intestinal permeability (IP), small intestinal bacterial overgrowth (SIBO), and homeostatic model assessment-insulin resistance were investigated in forty children (mean age 9.8 years) categorized as normal weight (NW) or obese (body mass index <85th or >95th percentile, respectively) ± ultrasonographic bright liver and hypertransaminasemia (NAFLD). SIBO was increased in all obese children (p = 0.0022), IP preferentially in those with NAFLD (p = 0.0002). The partial least-square discriminant analysis of urinary metabolome correctly allocated children based on their obesity, NAFLD, visceral fat, pathological IP and SIBO. Compared to NW, obese children had (1) higher levels of glucose/1-methylhistidine, the latter more markedly in NAFLD patients; and (2) lower levels of xylitol, phenyl acetic acid and hydroquinone, the latter especially in children without NAFLD. The metabolic pathways of BCAA and/or their metabolites correlated with excess of visceral fat centimeters (leucine/oxo-valerate), and more deranged IP and SIBO (valine metabolites). Urinary metabolome analysis contributes to define a metabolic fingerprint of pediatric obesity and related NAFLD, by identifying metabolic pathways/metabolites reflecting typical obesity dietary habits and GLA perturbations.

NEED OF IRON SUPPLEMENTATION IN GESTATIONAL DIABETES MELLITUS

Objective

Gestational diabetes mellitus (GDM) increases the foetal morbidity and mortality and there is also risk of development of type II diabetes for the mother. In pregnancy iron supplementations are given to all the females in India. Data are not available on the relationship between serum ferritin and GDM in Indian populations.

Material & Methods

Case control study was done on 90 women (30 GDM patients approx 28 weeks of gestation and 60 control subjects without GDM) referred to the tertiary care hospital at New Delhi. Ferritin was analysed by ELISA kit. They were analyzed for the correlation of ferritin with blood glucose in GDM patients.

Results

On comparison with blood glucose the levels of ferritin were statistically significantly high in GDM cases as compared to controls (p value 0.008). There was a negative correlation of ferritin with blood glucose level (r value -0.039, p value 0.794).

Discussion

Pregnancy is an equivalent of an inflammatory state and the high levels of ferritin can help in determining the need of iron supplementation given in pregnant females. Women who had high serum ferritin had the greatest risk of GDM.

Conclusion

This study suggests a possible link between elevated serum ferritin and low-grade inflammation. Further studies in larger populations are required to establish this study.

A review of iron studies in overweight and obese children and adolescents: a double burden in the young?

INTRODUCTION

The connection between iron and excessive adiposity has received much research interest. Although children and adolescents have unique developmental phases and nutritional demands, to date, reviews of iron in the overweight (OW) and obese (OB) have combined studies of children and adults or have focussed on adults.

PURPOSE

The aim of this review was to critically evaluate studies of the relationship between iron and OW and obesity in children and adolescents, with emphasis on iron status, oral iron response, dietary intake and systemic inflammatory markers.

METHODS

A PubMed search was conducted to identify relevant articles published up to December 2015. Combinations of the following keywords were used: iron, OW, OB, children, adolescents, diet, hepcidin, inflammation, fortification, supplementation, weight loss, trace elements, obesity, iron deficiency (ID), minerals.

RESULTS AND CONCLUSION

A higher prevalence of ID, or risk of ID, among OW and OB children and adolescents has been consistently observed. Chronic inflammation caused by excessive adiposity offers a plausible explanation for this finding, rather than dietary factors. However, future studies must employ screening for the presence of both acute and chronic infections and inflammatory conditions and report other factors such as pubertal status. Intervention studies, although few, indicate that OW and OB children and adolescents have reduced response to oral iron. Further trials are needed to explore the connection between body fat mass, inflammatory proteins and iron absorption, together with the effect of weight loss on iron status in iron-deficient OW and OB children and adolescents.

Review article: the management of paediatric nonalcoholic fatty liver disease

BACKGROUND

Paediatric nonalcoholic fatty liver disease (NAFLD) is a major public health concern given the recent increase in its prevalence and link to obesity and other metabolic comorbidities. Current treatment strategies involve lifestyle changes. Other surgical and pharmacologic interventions have been proposed; however, limited randomised controlled trials (RCTs) in the paediatric population restrict their use.

AIM

To review the current management of paediatric NAFLD, including lifestyle and pharmacologic interventions, and to formulate recommendations for study design for future studies.

METHODS

A MEDLINE, Pubmed and Cochrane Review database search used a combination of keywords, including NAFLD, nonalcoholic steatohepatitis (NASH), paediatric, treatments, lifestyle changes, bariatric surgery, orlistat, metformin, thiazolidinediones, vitamin E, cysteamine bitartrate, ursodeoxycholic acid (UDCA), probiotics, omega-3 fatty acids, pentoxyfylline, farnesoid X receptor agonist and toll-like receptor modifiers. The articles were selected based on their relevance to the review.

RESULTS

Lifestyle interventions involving diet and exercise remain first-line treatment for paediatric NAFLD. Bariatric surgery, orlistat, insulin sensitisers and UDCA have been evaluated but are not recommended as first or second-line therapy. Medications such as cysteamine bitartrate, probiotics, polyunsaturated fats and pentoxyfilline share beneficial effects in trials, however, there is a paucity of adequately powered RCTs in which liver histology is evaluated. Vitamin E has been shown to be effective and safe in improving NASH histology in children.

CONCLUSIONS

Lifestyle intervention should be first-line treatment for paediatric NAFLD. Vitamin E should be considered for those with biopsy-proven NASH or borderline NASH failing first-line therapy. Other therapeutics show promising results but require larger RCTs with convincing endpoints. Improved screening techniques, objective validated inclusion criteria and outcome measures as well as rigour in study design are necessary for propelling therapeutic discovery.

Noninvasive biomarkers in non-alcoholic fatty liver disease: Current status and a glimpse of the future

The development of non invasive biomarkers of disease has become a major focus of interest in nonalcoholic fatty liver disease (NAFLD). The large prevalence of the disease and the invasive nature of the investigation means that screening with liver biopsy is impractical. In addition to screening, the differentiation of those with simple steatosis vs steatohepatitis and fibrosis is clinically important as the prognosis of each differs. Serum biomarkers may be a combination of simple markers derived from large data sets or direct markers of disease activity. Serum markers of inflammation, apoptosis and oxidative stress in addition to fibrosis have been extensively studied in patients with NAFLD. Other techniques such as transient elastography, magnetic resonance elastography and acoustic radiation force imaging are becoming more established as noninvasive methods of detecting fibrosis in a variety of chronic liver conditions in addition to NAFLD. Newer high throughput methods such as proteomics and glycomics allow the nonhypothesis-driven identification of novel markers and may also potentially contribute to our understanding of the pathogenesis of the condition. This review addresses some of the methodological issues which need to be considered in the search for the ideal biomarker. It is likely that a combination of serum biomarkers and techniques such as transient elastography may provide the optimal diagnostic discrimination however this remains to be proven in large studies.

Serum adiponectin, leptin, resistin and RBP4 levels in obese and metabolic syndrome children with nonalcoholic fatty liver disease

AIM

To investigate the relationship of adiponectin, leptin, resistin and RBP4 levels in obese and metabolic syndrome children with nonalcoholic fatty liver disease (NAFLD).

PATIENTS & METHODS

Group I consisted of 63 obese children with liver steatosis, group II consisted of 12 obese children with elevated serum ALT activity from group I, and group III included 85 obese children without liver steatosis.

RESULTS

Leptin levels were higher in the NAFLD children than in the control group. Serum RBP4 levels in obese children with NAFLD were higher than those in obese children without NAFLD and controls. Adiponectin and resistin levels were negatively correlated and RBP4 levels positively correlated with ALT activity and ultrasonographic grading.

CONCLUSION

These data suggest that adiponectin, resistin and RBP4 may have a role in the pathogenesis of NAFLD in obese children. Adiponectin, leptin, resistin and RBP4 may be suitable markers for predicting metabolic syndrome and NAFLD.

Long-term day-and-night rotating shift work poses a barrier to the normalization of alanine transaminase

To evaluate the impact of day-and-night rotating shift work (RSW) on liver health, we performed a retrospective analysis of the association between long-term RSW exposure and the normalization of plasma alanine transaminase (ALT) levels over a five-year period. The data from physical examinations, blood tests, abdominal sonographic examinations, personal histories, and occupational records were collected from a cohort of workers in a semiconductor manufacturing company. The sample population was divided into three subgroups for analysis, according to self-reported shift work status over the five-year interval: persistent daytime workers, workers exposed intermittently to RSW (i-RSW), and workers exposed persistently to RSW (p-RSW). Records were analyzed for 1196 male workers with an initial mean age of 32.5 years (SD 6.0 years), of whom 821 (68.7%) were identified as rotating shift workers, including 374 i-RSW (31.3%) and 447 p-RSW workers (37.4%). At the beginning of the follow-up, 275 were found to have elevated ALT (e-ALT): 25.1% daytime workers, 23.0% i-RSW workers, and 21.3% p-RSW workers (p = 0.098). Of those with e-ALT at the beginning, 101 workers showed normalized serum ALT levels at the end of five-year follow-up: 40 (10.7%) of 375 daytime workers, 32 (8.6%) of 374 i-RSW workers, and 29 (6.5%) of 447 p-RSW workers (p = 0.016). Compared with the workers having persistent e-ALT at the end of follow-up, the workers normalized serum ALT levels had significantly lesser exposures to RSW during follow-up. By performing multivariate logistic regression analyses, and comparing with the persistent daytime co-workers, after controlling for confounding variables (age, occupational factors, educational levels, lifestyle factors, metabolic syndrome, hepatovirus infection, and fatty liver), analysis indicated that the workers exposed to p-RSW were 46% less likely (OR, 0.54; 95% CI, 0.30-0.95; p = 0.03) to attain normal ALT levels within a five-year interval. These observations demonstrate that persistent day-and-night RSW pose a vigorous obstacle to the normalization of e-ALT among workers with preexisting abnormal liver function. We suggest that workers and managers approach with caution the consideration of assigning or accepting long-term day-and-night RSW when an employee health screening shows evidence of abnormal liver function.

MRI-diagnosed nonalcoholic fatty liver disease is correlated to insulin resistance in adolescents

RATIONALE AND OBJECTIVES

To evaluate the presence of nonalcoholic fatty liver disease (NAFLD) in eutrophic and obese adolescents with magnetic resonance imaging (MRI) and its relationship to insulin resistance and other potential biomarkers.

MATERIALS AND METHODS

A total of 50 adolescents (aged 11-17 years), including 24 obese and 26 eutrophic adolescents, were evaluated using MRI exams for NAFLD diagnosis. Blood analysis was performed to measure glucose, insulin, total cholesterol, high-density lipoprotein cholesterol, triglycerides, fibrinogen, aminotransferases, alkaline phosphatase, gamma-gt, and C-reactive protein. The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) index was also calculated. Laboratory test results and anthropometric assessment were statistically analyzed to determine potential correlation with NAFLD prevalence.

RESULTS

The prevalence of NAFLD among the obese was significantly higher (83.3%; CI 95: 64.5-94.5%) than that of the eutrophic group (19.2%; CI 95: 7.4-37.6%). In multivariate analysis, only HOMA-IR was an independent risk factor for diagnosis NAFLD using MRI. Compared to eutrophic adolescents, the obese adolescents had significantly higher levels for all parameters measured except for total and high-density lipoprotein cholesterol, which were significantly lower.

CONCLUSION

The prevalence of NAFLD was 19.2% among eutrophic patients and 83.3% among obese patients. Only HOMA-IR was determined to be an independent risk factor for NAFLD.

Ethnic differences in the link between insulin resistance and elevated ALT

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) exhibits tight links with insulin resistance (IR) and the metabolic syndrome (MetS), a cluster of cardiovascular risk factors. Compared with non-Hispanic whites, non-Hispanic black adolescents have more IR but a lower prevalence of NAFLD and MetS. Our hypothesis was that IR would be a better predictor of alanine aminotransferase (ALT) elevations than is MetS among non-Hispanic blacks.

METHODS

We analyzed data from 4124 adolescents aged 12 to 19 years in the 1999 to 2010 NHANES, using unexplained elevations in ALT (>30 U/L) to characterize presumed NAFLD and using a pediatric adaptation of the Adult Treatment Panel III definition of MetS.

RESULTS

Prevalence of elevated ALT varied by race/ethnicity (Hispanics 13.7%, non-Hispanic white 8.6%, non-Hispanic blacks 5.4%, P < .0001). Among non-Hispanic whites and Hispanics, a classification of MetS performed well in identifying adolescents with elevated ALT (odds ratios [ORs] 9.53 and 5.56, respectively), as did MetS-related indices. However, among non-Hispanic blacks, the association between MetS and ALT elevations was smaller in magnitude and technically nonsignificant (OR = 3.24, P = .051). Furthermore, among non-Hispanic blacks, the presence of IR and elevated waist circumference performed more poorly at identifying ALT elevations (ORs 3.93 and 2.28, respectively: significantly smaller than ORs for non-Hispanic whites, P < .05), with triglyceride elevations being a better predictor (OR = 4.44).

CONCLUSIONS

Non-Hispanic black adolescents exhibit a lower relationship between IR and elevated ALT, supporting racial/ethnic differences in the link between MetS and NAFLD. These data may have implications regarding triggers for screening for NAFLD among non-Hispanic black adolescents, focusing particularly on those with triglyceride elevations.

Iron in child obesity. Relationships with inflammation and metabolic risk factors

Iron (Fe) sequestration is described in overweight and in its associated metabolic complications, i.e., metabolic syndrome (MetS) and non-alcoholic liver fatty disease (NAFLD); however, the interactions between Fe, obesity and inflammation make it difficult to recognize the specific role of each of them in the risk of obesity-induced metabolic diseases. Even the usual surrogate marker of Fe stores, ferritin, is influenced by inflammation; therefore, in obese subjects inflammation parameters must be measured together with those of Fe metabolism. This cross-sectional study in obese youth (502 patients; 57% girls): 11.4 ± 3.0 years old (x ± SD); BMI z score 5.5 ± 2.3), multivariate regression analysis showed associations between Fe storage assessed by serum ferritin with risk factors for MetS and NAFLD, assessed by transaminase levels, which were independent of overweight and the acute phase protein fibrinogen. Further studies incorporating the measurement of complementary parameters of Fe metabolism could improve the comprehension of mechanisms involved.

Persistent rotating shift work exposure is a tough second hit contributing to abnormal liver function among on-site workers having sonographic fatty liver

To investigate the relationship between elevated serum alanine-transaminase (e-ALT) and persistent rotating shift work (p-RSW) among employees with sonographic fatty liver (SFL), the authors performed a retrospective analysis on a cohort of electronics manufacturing workers. The records of 758 workers (507 men, 251 women) with initially normal ALT and a mean age of 32.9 years were analyzed. A total of 109 workers (14.4%) developed e-ALT after 5 years. Compared with those having neither initial SFL nor p-RSW exposure, multivariate analysis indicated that employees who had initial SFL but without p-RSW finally had a higher risk (odds ratio = 2.9; 95% confidence interval [CI] = 1.7-5.1) for developing e-ALT; workers with baseline SFL plus p-RSW had a 3.7-fold increased risk (95% CI = 1.8-7.5). SFL poses a conspicuous risk for the development of e-ALT, and persistent p-RSW exposure significantly aggravates the development of e-ALT among on-site workers with preexisting SFL.

Therapeutic options in pediatric non alcoholic fatty liver disease: current status and future directions

The epidemics of overweight and obesity has resulted in a significant increase of non alcoholic fatty liver disease (NAFLD), a potentially progressive condition. Currently, obesity related hepatopathy represents therefore the main cause of pediatric chronic liver disease. The first choice treatment at all ages is weight loss and/or lifestyle changes, however compliance is very poor and a pharmacological approach has become necessary. In the present article we present a systematic literature review focusing on established pediatric NALFD drugs (ursodeoxycholic acid, insulin sensitizers, and antioxidants) and on innovative therapeutic options as well.

Regarding the former ones, a pediatric pilot study highlighted that ursodeoxycholic acid is not efficient on transaminases levels and bright liver. Similarly, a recent large scale, multicenter randomized clinical trial (TONIC study) showed that also insulin sensitizers and antioxidant vitamin E have scarce effects on serum transaminase levels. Among a large series of novel therapeutic approaches acting on recently proposed different pathomechanisms, probiotics seem hitherto the most interesting and reasonable option for their safety and tolerability. Toll-like receptors modifiers, Pentoxifylline, and Farnesoid X receptors agonists have been still poorly investigated, and will need further studies before becoming possible promising innovative therapeutic strategies.

Diagnosis of nonalcoholic fatty liver disease in children and adolescents: position paper of the ESPGHAN Hepatology Committee

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children and adolescents in the United States, and most probably also in the rest of the industrialized world.As the prevalence of NAFLD in childhood increases with the worldwide obesity epidemic, there is an urgent need for diagnostic standards that can be commonly used by pediatricians and hepatologists. To this end, we performed a PubMed search of the adult and pediatric literature on NAFLD diagnosis through May 2011 using Topics and/or relevant Authors as search words. According to the present literature, NAFLD is suspected based on the association of fatty liver combined with risk factors (mainly obesity), after the exclusion of other causes of liver disease. The reference but imperfect standard for confirming NAFLD is liver histology. The following surrogate markers are presently used to estimate degree of steatosis and liver fibrosis and risk of progression to end-stage liver disease: imaging by ultrasonography or magnetic resonance imaging, liver function tests, and serum markers of liver fibrosis.NAFLD should be suspected in all of the overweight or obese children and adolescents older than 3 years with increased waist circumference especially if there is a NAFLD history in relatives. The typical presentation, however, is in children ages 10 years and older. The first diagnostic step in these children should be abdominal ultrasound and liver function tests, followed by exclusion of other liver diseases. Overweight/obese children with normal ultrasonographic imaging and normal liver function tests should still be monitored due to the poor sensitivity of these tests at a single assessment.Indications for liver biopsy include the following: to rule out other treatable diseases, in cases of clinically suspected advanced liver disease, before pharmacological/surgical treatment, and as part of a structured intervention protocol or clinical research trial.

Influence of elevated liver fat on circulating adipocytokines and insulin resistance in obese Hispanic adolescents

OBJECTIVE

We performed this study to examine the metabolic differences arising from higher liver fat accumulation in obese Hispanic adolescents, with a particular focus on circulating levels of adipocytokines and insulin resistance.

METHODS

Forty-one obese Hispanic adolescents (15.3 ± 1.0 years, body mass index percentile: 97.0 ± 3.9) were assessed for: visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and hepatic fat fraction (HFF) by magnetic resonance imaging; fasting measures of serum glucose, insulin and adipocytokines; homeostasis model assessment of insulin resistance (HOMA-IR); and insulin sensitivity (SI) and the acute insulin response to glucose (AIR) by intravenous glucose tolerance test. Subjects with normal levels of HFF (below 5%; n = 25) were compared to those with HFF > 5% (n = 16).

RESULTS

The two groups differing in HFF were similar for total body fat, VAT and SAT. The group with HFF > 5% had significantly (P < 0.05) higher interleukin-8 (IL-8) (6.1 ± 1.6 vs. 3.2 ± 0.4 pg mL(-1) ), NGF (30.2 ± 9.9 vs. 13.9 ± 1.6 pg mL(-1) ), HOMA-IR (8.8 ± 1.1 vs. 5.5 ± 0.5), AIR (1869 ± 206 vs. 1092 ± 165) and a tendency for lower SI (1.2 ± 0.4 vs. 2.1 ± 0.3; P = 0.06), with no significant differences in any of other factors measured.

CONCLUSIONS

These data suggest that elevated liver fat is most closely associated with elevated serum IL-8 and NGF levels as well as increased AIR and HOMA-IR. These elevated factors may play significant roles in the metabolic abnormalities associated with elevated liver fat in obese Hispanics.

Unbalanced oxidant-antioxidant status and its effects in pediatric diseases

Oxidative stress results from a disparity between the generation of reactive oxygen species and the antioxidant ability of the organism. The alteration of the oxidant-antioxidant system brings in adults an effective state of imbalance, which may influence the pathogenesis of many diseases. Oxidative stress also plays a pivotal role in the progression of various pathologies in childhood, through a manipulation of regulatory proteins. In fact, several studies have demonstrated that an unbalanced oxidant-antioxidant status is able to determine toxic effects even during infancy. Therefore, the aim of this review was to summarize current knowledge about the dynamic relationship between oxidative stress and systemic diseases during childhood. In order to better understand these complex mechanisms, a comprehensive review of the literature was done, focusing mainly on pre-pubertal children. In fact, this age-group offers a unique opportunity to exclude confounding factors, especially those related to the metabolic effects induced by puberty. Early identification of these very young patients should be aimed at minimizing the degree of oxidative damage. Only by achieving early diagnosis, will it be possible to identify those children who could benefit from specific therapeutic approaches targeting oxidative stress.

Metabolic syndrome in pediatrics: old concepts revised, new concepts discussed

The worldwide epidemic of childhood obesity in the last decades is responsible for the occurrence in pediatrics of disorders once mainly found in adults, such as the metabolic syndrome. A key factor in the pathogenesis of metabolic syndrome is insulin resistance, a phenomenon occurring mainly in obese subjects with a general resistance to the insulin effect only on carbohydrates metabolism. Given that the metabolic syndrome is driven by obesity, the prevalence of the latter will strongly influence the prevalence of metabolic syndrome. This article addresses the causes of metabolic syndrome and the relevance of obesity in the pediatric population.

The Relationship between Serum Gamma-glutamyltransferase Level and Overweight in Korean Urban Children

BACKGROUND

Recently, it has been reported that gamma-glumyltransferase (GGT) is associated with various cardiovascular risk factors including overweight in adults. However, there are few studies on the relationship between GGT and cardiovascular risk factors in children. The aim of this study was to assess the relationship between serum GGT level and overweight in Korean urban children.

METHODS

This study was a cross-sectional study using data on 390 4th grade students of elementary schools in Gunpo, Korea. Children were divided into 4 groups according to gender-specific quartiles of serum GGT level. Body mass index, waist circumference and body fat percentage were quantified as adiposity indices.

RESULTS

All adiposity indices in children of the highest GGT level quartile were higher than those in children of the lowest quartile. Adjusted odd ratios on overweight of the highest quartile of GGT level compared to the lowest quartile were 14.40 (95% confidence interval [CI], 4.43 to 46.83) in boys and 2.94 (95% CI, 1.06 to 8.16) in girls.

CONCLUSION

This study shows that high serum GGT level is related with overweight in Korean urban children and this relationship is stronger in boys compared to girls.

Limited Weight Loss or Simply No Weight Gain following Lifestyle-Only Intervention Tends to Redistribute Body Fat, to Decrease Lipid Concentrations, and to Improve Parameters of Insulin Sensitivity in Obese Children

Objectives. To investigate whether lifestyle-only intervention in obese children who maintain or lose a modest amount of weight redistributes parameters of body composition and reverses metabolic abnormalities. Study Design. Clinical, anthropometric, and metabolic parameters were assessed in 111 overweight or obese children (CA of 11.3 ± 2.8 years; 63 females and 48 males), during 8 months of lifestyle intervention. Patients maintained or lost weight (1-5%) (group A; n: 72) or gained weight (group B). Results. Group A patients presented with a decrease in systolic blood pressure (SBP) and diastolic blood pressure (DBP) (P < .005 and P < .05, resp.), BMI (P < .0001), z-score BMI (P < .0001), waist circumference (P < .0001), fat mass (P < .005), LDL-C (P < .05), Tg/HDL-C ratio (P < .05), fasting and postprandial insulin (P < .005), and HOMA (P < .005), while HDL-C (P < .05) and QUICKI increased (P < .005). Conversely, group B patients had an increase in BMI (P < .0001), waist circumference (P < .005), SBP (P < .005), and in QUICKI (P < .005), while fat mass (P < .05), fasting insulin (P < .05), and HOMA (P < .05) decreased. Lean mass, DBP, lipid concentrations, fasting and postprandial glucose, postprandial insulin, and ultrasensitive C-reactive protein (CRP) remained stable. Conclusions. Obese children who maintain or lose a modest amount of weight following lifestyle-only intervention tend to redistribute their body fat, decrease blood pressure and lipid levels, and to improve parameters of insulin sensitivity.

Breastfeeding in infancy is not associated with inflammatory status in healthy adolescents

It has been suggested that breast-feeding (BF) may be associated with a decreased risk of cardiovascular disease in adulthood. A low-grade inflammation is associated with an increased risk of cardiovascular disease, even in apparently healthy children. The objective of this study was to assess the potential modulating effect of BF on the inflammatory status of healthy adolescents. Information on BF (duration) was obtained from parental records in 484 of 1040 healthy European urban adolescents (56.4% females) that had a blood sample obtained as part of the Healthy Lifestyle in Europe by Nutrition and Adolescence study. Blood serum inflammatory markers were measured, including high sensitivity C-reactive protein, complement factors 3 and 4, ceruloplasmin, adhesion molecules (L-selectin and soluble endothelial selectin, soluble vascular cell adhesion molecule 1, and intercellular adhesion molecule 1), cytokines, TGFβ1, and white blood cells. After univariate analysis, a propensity score, including the potential confounding factors, was computed and used to assess the association between BF and selected inflammatory markers. BF was not significantly associated with any of the selected inflammatory markers after adjustment for gender and propensity score. In our study, BF was not associated with low-grade inflammatory status in healthy adolescents, suggesting that the potential cardiovascular benefits of BF are related to other mechanisms than modulation of inflammation or might become relevant at a later age. Groups at high risk for cardiovascular disease should be a target for further research concerning the effects of BF.

Tumor necrosis factor alpha and its soluble receptors in obese children with NAFLD

PURPOSE

To evaluate the serum levels of tumor necrosis factor (TNF) alpha and its soluble receptors in obese children with non-alcoholic fatty liver disease (NAFLD).

MATERIAL/METHODS

Fasting serum levels of TNFalpha and its receptors were determined in 45 consecutive obese children with suspected liver disease and 20 lean controls. The degree of liver steatosis was graded in ultrasound according to Saverymuttu. 1H-MR spectroscopy was performed with 1.5T scanner with PRESS sequence.

RESULTS

A fatty liver was confrmed in 32 children by ultrasonography (group I); 16 of them also had increased ALT activity (group Ia - NAFLD). Serum concentrations of TNFalpha and its receptors were significantly higher in obese children with NAFLD compared to controls. Significant correlation was found between ultrasonographic grade of liver steatosis and TNFalpha level but serum level of this adipokine was not significantly different in children with advanced liver steatosis (grade 2-3, n=13) compared to patients with mild steatosis (grade 1, n=19). The ability of TNFalpha and its receptors (R1, R2) to differentiate children with advanced liver steatosis from those with mild steatosis was insignificant. However, the ability of serum TNFalpha to differentiate obese children with liver steatosis from those without steatosis was significant (AUC=0.7448, p=0.0291).

CONCLUSION

Although TNFalpha does not predict advanced liver steatosis, it may be suitable serum marker in predicting liver steatosis in obese children.

Serum levels of CK18 M30 and leptin are useful predictors of steatohepatitis and fibrosis in paediatric NAFLD

BACKGROUND

With the alarming growth in prevalence of paediatric nonalcoholic fatty liver disease (NAFLD), there is a need for noninvasive methods of stratifying disease severity. Our aim was to evaluate a combination of serum biomarkers as a measure of disease activity in paediatric NAFLD.

PATIENTS AND METHODS

Forty-five children with biopsy-proven NAFLD were enrolled. Caspase-cleaved CK18 fragments (CK18 M30), hyaluronic acid, leptin, and adiponectin were measured in serum using enzyme-linked immunosorbent assays and high-sensitivity C-reactive protein using a colorimetric assay.

RESULTS

Median age was 12.7 years (55% boys). Median body mass index z score was 1.7. CK18 M30 levels were significantly higher in patients with NAFLD versus controls, median 288 IU/L versus 172 IU/L (P < 0.001), and in those with steatohepatitis, median 347 IU/L versus simple steatosis (NAFLD activity score < 3), median 191 IU/L (P = 0.006). Significant fibrosis (≥F2) could be differentiated from no/minimal fibrosis (<F2), median 393 IU/L versus 243 IU/L (P = 0.03). Leptin could distinguish <F2 from ≥F2; 28.9 ng/mL versus 70.1 ng/mL (P = 0.037). Adiponectin, hyaluronic acid, and high-sensitivity C-reactive protein did not achieve significance in predicting steatohepatitis nor significant fibrosis.

CONCLUSIONS

The present study combines use of markers for different processes in the development of steatohepatitis. Serum biomarkers, especially CK18 M30, are useful in stratifying disease severity in paediatric NAFLD.

Diagnostic and Therapeutic Significance of the Oxidative Stress Parameters in Children

Pharmacotherapy of pediatric diseases represents a major challenge considering that the majority of medicines in everyday practice have not been pediatrically evaluated. The efficacy of therapy depends to a large extent on the knowledge of pathophysiological processes in the children organism at different ages. Therefore, research in that direction is of the utmost importance. An imbalance in the production of free oxygen/nitrogen species and parameters of antioxidative protection is a significant factor in many diseases (e.g. heart failure, pulmonary hypertension, asthma, neonatal sepsis, cancer etc.) in children of different age groups. Reactive oxygen/nitrogen species serve as cell signaling molecules for normal biologic processes. An increase in their generation can cause damages which can disrupt normal physiological cellular processes and eventually cause cell death. This review outlines the previous assessments of oxidative stress parameters in children of different ages for some diseases. Also, the potential diagnostic and therapeutic possibilities for the oxydative stress parameters in children have been considered.

Serum concentration of adiponectin, leptin and resistin in obese children with non-alcoholic fatty liver disease

PURPOSE

Obesity, insulin resistance and dyslipidemia are the most significant risk factors of non-alcoholic fatty liver disease (NAFLD) but the role of adipokines in patomechanism of this disease is not clear. The aim of the study was to evaluate the serum levels of leptin, adiponectin and resistin in obese children with NAFLD.

MATERIAL/METHODS

The fasting serum levels of adipokines were determined in 44 consecutive obese children with suspected liver disease and in 24 lean controls. The degree of the ultrasound liver steatosis was graded according to Saverymuttu.

RESULTS

The fatty liver was confirmed in 33 children by ultrasonography (16 of them also showed an increased ALT activity). The serum leptin level was significantly higher and adiponectin level was lower in the obese children with NAFLD when compared to controls. Only adiponectin correlated with homeostasis model assessment of insulin resistance (HOMA-IR). Significant negative correlations were found between the ultrasonographic grades of liver steatosis and adiponectin and resistin levels. Serum adiponectin and resistin levels were lower in children with an advanced liver steatosis (grade 3, n=10) compared to patients with a mild steatosis (grade 1-2, n=23). The ability of serum adiponectin and resistin to differentiate children with an advanced liver steatosis from those with mild steatosis was significant.

CONCLUSIONS

These data suggest a role of both adiponectin and resistin in the pathogenesis of NAFLD in obese children and confirm the association between adiponectin and insulin resistance. Adiponectin and resistin may be suitable serum markers in predicting an advanced liver steatosis in children with NAFLD.

Metabolic syndrome in pediatrics: old concepts revised, new concepts discussed

The worldwide epidemic of childhood obesity in the last decades is responsible for the occurrence in pediatrics of disorders once mainly found in adults, such as the metabolic syndrome. A key factor in the pathogenesis of metabolic syndrome is insulin resistance, a phenomenon occurring mainly in obese subjects with a general resistance to the insulin effect only on carbohydrates metabolism. Given that the metabolic syndrome is driven by obesity, the prevalence of the latter will strongly influence the prevalence of metabolic syndrome. This article addresses the causes of metabolic syndrome and the relevance of obesity in the pediatric population.

Evaluation of a urinary multi-parameter biomarker set for oxidative stress in children, adolescents and young adults

The involvement of reactive oxygen species (ROS) and oxidative stress in pediatric diseases is an important concern, but oxidative stress status in healthy young subjects and appropriate methods for its measurement remain unclear. This study evaluated a comprehensive set of urinary biomarkers for oxidative stress in healthy children, adolescents and young adults. Results show that urinary excretion of acrolein-lysine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), nitrite/nitrate and pentosidine were highest in the youngest subjects and decreased to constant levels by early adolescence. Urinary acrolein-lysine, 8-OHdG, nitrite/nitrate and pentosidine showed significant inverse correlations with age, but pyrraline did not change significantly with age. No significant differences in biomarkers were apparent between males and females. Younger subjects grow rapidly and sustain immune activation, and are probably exposed to high concentrations of ROS and nitric oxide. Consequently, they are more vulnerable to oxidation of lipids, proteins, DNA and carbohydrates. Normal reported values in this study are a basis for future studies of disease mechanisms involving oxidative stress and for future trials using antioxidant therapies for oxidative stress-related diseases in the pediatric field.

Treatment of non-alcoholic fatty liver disease with metformin versus lifestyle intervention in insulin-resistant adolescents

The presence of fatty liver per ultrasound and liver-associated enzymes were measured in a select cohort of youth with both obesity and insulin resistance, and the effect of metformin on these parameters evaluated. Fifty obese, multiethnic, insulin-resistant adolescents (mean age 15.1 yr, mean body mass index 39.8 kg/m2) were randomized to receive lifestyle recommendations plus either twice per day doses of 850 mg of metformin or placebo. Fasting and post-glucose challenge biochemistries and liver ultrasounds were compared at baseline and 6 months. The prevalence of fatty liver was 74%, elevated alanine aminotransferase (ALT) 14%, aspartate aminotransferase (AST) 14%, and gamma-glutamyl transferase (GGT) 17%. Fatty liver was mild in 23%, moderate in 31%, and severe in 46%. Fatty liver was more common in male and Hispanic subjects and elevated ALT more common in Hispanic subjects. Subjects with fatty liver appeared more insulin resistant (higher fasting insulin and triglycerides, lower high-density lipoprotein cholesterol) and had higher ALT and AST. At 6 months, mean ALT, GGT, and fasting insulin improved significantly in all subjects. Fatty liver prevalence (p < 0.04), severity (p < 0.04), and fasting insulin (p < 0.025) improved significantly with metformin compared to placebo. Non-alcoholic fatty liver disease (NAFLD) occurs with a high prevalence and severity in obese, insulin-resistant adolescents. While metformin plus lifestyle intervention appears promising, defining NAFLD therapies capable of preventing fibrosis and cirrhosis requires further study.

Beta-aminoisobutyric acid prevents diet-induced obesity in mice with partial leptin deficiency

Beta-Aminoisobutyric acid (BAIBA), a thymine catabolite, increases fatty acid oxidation (FAO) in liver and reduces the gain of body fat mass in Swiss (lean) mice fed a standard chow. We determined whether BAIBA could prevent obesity and related metabolic disorders in different murine models. To this end, BAIBA (100 or 500 mg/kg/day) was administered for 4 months in mice totally deficient in leptin (ob/ob). BAIBA (100 mg/kg/day) was also given for 4 months in wild-type (+/+) mice and mice partially deficient in leptin (ob/+) fed a high-calorie (HC) diet. BAIBA did not limit obesity and hepatic steatosis in ob/ob mice, but reduced liver cytolysis and inflammation. In ob/+ mice fed the HC diet, BAIBA fully prevented, or limited, the gain of body fat, steatosis and necroinflammation, glucose intolerance, and hypertriglyceridemia. Plasma beta-hydroxybutyrate was increased, whereas expression of carnitine palmitoyltransferase-1 was augmented in liver and white adipose tissue. Acetyl-CoA carboxylase was more phosphorylated, and de novo lipogenesis was less induced in liver. These favorable effects of BAIBA in ob/+ mice were associated with a restoration of plasma leptin levels. The reduction of body adiposity afforded by BAIBA was less marked in +/+ mice. Finally, BAIBA significantly stimulated the secretion of leptin in isolated ob/+ adipose cells, but not in +/+ cells. Thus, BAIBA could limit triglyceride accretion in tissues through a leptin-dependent stimulation of FAO. As partial leptin deficiency is not uncommon in the general population, supplementation with BAIBA may help to prevent diet-induced obesity and related metabolic disorders in low leptin secretors.

Liver steatosis in obese prepubertal children: a possible role of insulin resistance

OBJECTIVE

To determine whether in obese prepubertal children insulin resistance (IR) is associated with the development of liver steatosis.

METHODS AND PROCEDURES

Cross-sectional study evaluating the prevalence of liver steatosis in 100 severely obese prepubertal children and comparing IR indexes between children with (group 1) and without steatosis (group 2). Furthermore, IR indexes were compared to values of 50 normal weight children. Fasting blood samples were collected for the evaluation of liver function tests, lipid profile, plasma glucose, and insulin levels. All children underwent an oral glucose tolerance test and anthropometric measurements. Hepatic ultrasound was performed according to international criteria and by one single operator. Analysis was performed by Mann-Whitney U-test, Pearson correlation, and logistic regression.

RESULTS

Liver steatosis was found in 52% obese children and was equally distributed between the two sexes. Obese children were more insulin resistant when compared to controls (homeostasis model assessment of IR (HOMA-IR): P = 0.0001; whole body insulin sensitivity index (WBISI): P = 0.0005; fasting glucose/fasting insulin ratio (G/I): P = 0.0001), and group 1 presented an even higher degree of IR when compared to group 2 (HOMA-IR P = 0.0001; WBISI P = 0.0004; G/I P = 0.0001). The area under the curve (AUC) for insulin was significantly higher in group 1 when compared to group 2, while no difference was found in the AUC for glucose. There was no association between IR and adiposity indexes (P >0.05). The role of IR as a predictor for the development of steatosis was analyzed by multiple logistic regression, which documented that IR indexes were significantly related to steatosis independently of BMI-SDS.

DISCUSSION

Liver steatosis is an emerging problem in prepubertal severely obese children, and it appears to be an association between liver steatosis and IR in these subjects.

The obesity epidemic and nonalcoholic fatty liver disease in children

Childhood obesity is a worldwide health problem associated with an increase in the prevalence and severity of nonalcoholic fatty liver disease (NAFLD). This review covers the progress made between 2005 and 2007 in understanding the epidemiology, histology, and treatment of pediatric NAFLD. The number of children with NAFLD presents a major public health crisis. Noninvasive diagnostic tools offer future promise, but currently are unable to grade and stage disease. Therefore, pediatric NAFLD remains a clinico-pathological diagnosis requiring direct demonstration of liver steatosis and the exclusion of other causes of fatty liver and/or hepatitis. There are currently no proven therapies for NAFLD in children; however, TONIC (Treatment of Nonalcoholic Fatty Liver Disease in Children), the first multicenter clinical trial of pediatric NAFLD, is currently in progress. Such studies are imperative to address fundamental questions regarding cause and cure.

Application of metabolic flux analysis to identify the mechanisms of free fatty acid toxicity to human hepatoma cell line

Chronic exposure to elevated levels of free fatty acids (FFAs) has been shown to cause cell death (lipotoxicity), but the underlying mechanisms of lipotoxicity in hepatocytes remain unclear. We have previously shown that the saturated FFAs cause much greater toxicity to human hepatoma cells (HepG2) than the unsaturated ones (Srivastava and Chan, 2007). In this study, metabolic flux analysis (MFA) was applied to identify the metabolic changes associated with the cytotoxicity of saturated FFA. Measurements of the fluxes revealed that the saturated FFA, palmitate, was oxidized to a greater extent than the non-toxic oleate and had comparatively less triglyceride synthesis and reduced cystine uptake. Although fatty acid oxidation had a high positive correlation to the cytotoxicity, inhibitor experiments indicated that the cytotoxicity was not due to the higher fatty acid oxidation. Application of MFA revealed that cells exposed to palmitate also had a consistently reduced flux of glutathione (GSH) synthesis but greater de novo ceramide synthesis. These predictions were experimentally confirmed. In silico sensitivity analyses identified that the GSH synthesis was limited by the uptake of cysteine. Western blot analyses revealed that the levels of the cystine transporter xCT, but not that of the GSH-synthesis enzyme glutamyl-cysteine synthase (GCS), were reduced in the palmitate cultures, suggesting the limitation of cysteine import as the cause of the reduced GSH synthesis. Finally, supplementing with N-acetyl L-cysteine (NAC), a cysteine-provider whose uptake does not depend on xCT levels, reduced the FFA-toxicity significantly. Thus, the metabolic alterations that contributed to the toxicity and suggested treatments to reduce the toxicity were identified, which were experimentally validated.

Prevalence of elevated alanine aminotransferase among US adolescents and associated factors: NHANES 1999-2004

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is a common cause of liver disease in children and adolescents. The majority of studies of NAFLD in children have been in select populations of the clinically obese. Study aims were to estimate the prevalence of elevated alanine aminotransferase (ALT, as a marker of NAFLD) in a general contemporary adolescent population and to identify leading risk factors for ALT elevation (>30 U/L).

METHODS

We analyzed data of adolescent participants (aged 12-19 years; N = 5586) in the National Health and Nutrition Examination Survey 1999-2004, a representative sample of the civilian noninstitutionalized US population.

RESULTS

The prevalence of elevated ALT levels (>30 U/L) was 7.4% among white adolescents, 11.5% among Mexican American adolescents, and 6.0% among black adolescents. Elevated ALT levels were prevalent in 12.4% of male subjects compared with 3.5% of female subjects. Multivariable associations with elevated ALT levels were found for sex (odds ratio [OR] male vs female, 7.7; 95% confidence interval [CI], 3.9-15.1), ethnicity (OR black vs white, 0.6; 95% CI, 0.3-1.3; OR Mexican American vs white, 1.6; 95% CI, 1.0-2.6), waist circumference (OR per 1 SD, 1.4; 95% CI, 1.0-2.0), and fasting insulin level (OR per 1 SD, 1.6; 95% CI, 1.2-2.1). Age, C-reactive protein levels, and triglyceride levels were also positively and socioeconomic position inversely associated with elevated ALT levels. The magnitude of associations were similar across ethnic groups.

CONCLUSIONS

ALT level is associated with waist circumference and insulin resistance even in a young population. These characteristics could be utilized to identify adolescents who may benefit from screening for NAFLD, offering an opportunity to prevent disease progression at an early age.

Pediatric nonalcoholic fatty liver disease (NAFLD): a "growing" problem?

Nonalcoholic fatty liver disease (NAFLD) can affect both adults and children. With the current worldwide epidemic of pediatric obesity, pediatric NAFLD is increasingly being diagnosed. It is not exactly identical to NAFLD in adults, and these differences may be due in part to the occurrence of hepatic metabolic derangements typical of NAFLD during periods of active growth (infancy, mid-childhood and puberty). The natural history of pediatric NAFLD is not yet known; however, children with pediatric NAFLD can develop cirrhosis. Although details of disease mechanism in pediatric NAFLD remain unclear, hyperinsulinemia with insulin resistance appears to be critical. Determining the pathogenesis of pediatric NAFLD is likely to enhance our understanding of NAFLD in all age groups and may identify new treatment opportunities. Finding effective ways to prevent pediatric NAFLD is an important issue for children's health.