New data from the United States lluminates research in obesity
(Science Letter Via Thomson Dialog NewsEdge)
Data on obesity are outlined in reports from the United States.
Study 1: Nonalcoholic fatty liver disease was very prevalent in morbidly obese adolescents, but severe nonalcoholic steato-hepatitis was uncommon.
In a recent report, researchers in the United States conducted a study "to characterize the spectrum of nonalcoholic fatty liver disease (NAFLD) in morbidly obese adolescents, we correlated liver histology with clinical features and compared findings with reported adult data. We hypothesized that NAFLD would be less severe as a result of younger age and shorter duration of obesity, but portal inflammation and fibrosis would be more prevalent."
Cross-sectional study was made of 41 adolescent subjects, 13-19 years old (Mean, 16 years), 61% female, 83% non-Hispanic white, mean body mass index 59 kg/m2, undergoing gastric bypass with liver biopsy. Liver biopsies were graded and staged as proposed by the NASH Clinical Research Network. Data were analyzed by using descriptive statistics, analysis of variance, and Fisher exact tests," recounted S. Xanthakos and colleagues, Children's Hospital.
They determined, "Eighty-three percent had NAFLD: 24% steatosis alone, 7% isolated fibrosis with steatosis, 32% nonspecific inflammation and steatosis, and 20% nonalcoholic steato-hepatitis (NASH). Twenty-nine percent had fibrosis; none had cirrhosis. Abnormal ALT (p=0.05) and AST (p=0.01) were more prevalent in NASH. Mean fasting glucose was significantly higher in NASH (p=0.05), but prevalence of the metabolic syndrome was not significantly different."
The authors concluded, "NAFLD was very prevalent in morbidly obese adolescents, but severe NASH was uncommon. In contrast to morbidly obese adults, lobular inflammation, significant ballooning, and perisinusoidal fibrosis were rare, whereas portal inflammation and portal fibrosis were more prevalent, even in those who did not meet criteria for NASH. These findings might support use of a modified scoring system for pediatric NASH. Presence of the metabolic syndrome in morbidly obese adolescents did not distinguish NASH from steatosis alone."
Xanthakos and colleagues published their study in Clinical Gastroenterology and Hepatology (Histologic spectrum of nonalcoholic fatty liver disease in morbidly obese adolescents. Clin Gastroenterol Hepatol, 2006;4(2):226-232).
For additional information, contact S. Xanthakos, Children's Hospital, Medical Center, Division Gastroenterology Hepatology & Nutrition, MLC 2010, Cincinnati, OH 45229, USA.
Study 2: Microarray technology is advancing the study of obesity and nonalcoholic fatty liver disease.
According to a recent review from the United States, "The recent development of high-throughput gene expression technology permits simultaneous investigation of thousands of genes, providing a snapshot of the transcription state of diseased tissue. Microarray-based expression profiling is well suited to investigate the molecular basis of complex diseases such as obesity and chronic liver disease."
A. Baranova and colleagues at Inova Fairfax Hospital summarized, "With the help of microarray technology, functional genomics will surely advance our understanding of these diseases, and lead to more effective, targeted interventions that lack the toxicity of many conventional treatments.
"Despite their tremendous potential, microarray studies are subject to potential flaws in experimental design, experimental techniques, data analysis, and data interpretation. Besides the technical issues, the most important challenge is to develop integrative databases that combine gene expression data with the clinical data."
"Over the next few years," predicted the reviewers, "advances in technology and refinements in study design and data analysis will make clinically relevant translational research even more engaging and productive."
Baranova and colleagues published the results of their research in Liver International (Microarray technology in the study of obesity and nonalcoholic fatty liver disease. Liver Int, 2005;25(6):1091-1096).
For additional information, contact Z.M. Younossi, Inova Fairfax Hospital, Center Liver Diseases, 3300 Gallows Rd., Falls Church, VA 22042, USA.
Study 3: A short-term lifestyle intervention can reverse obesity-related hypoadiponectinemia in adolescents.
According to a study from the United States, "Hypoadiponectinemia and chronic subclinical inflammation in adults are associated with the development of diabetes and cardiovascular disease. The potential relationship between adiponectin and inflammation and its modulation by lifestyle intervention in the pediatric obese population remain unclear."
P. Balagopal and colleagues working with the Nemours Children's Clinic in Jacksonville proposed "to investigate in adolescents 1) the relationship between adiponectin and obesity-related inflammatory factors, C-reactive protein, and IL-6; and 2) the effect of a lifestyle intervention on adiponectin and whether these effects are related to changes in inflammatory factors."
They described, "Twenty-one obese and age-matched lean adolescents (age, 14-18 yr; Tanner stage, greater than or equal toIV) were studied cross-sectionally. Fifteen obese adolescents also underwent a randomized, controlled physical activity-behavior-diet-based lifestyle intervention for 3 months. Associations among adiponectin, fat mass, insulin resistance, and inflammatory factors at baseline as well as after the intervention were assessed."
The scientists determined, "Plasma adiponectin concentration was lower (p<0.001) in the obese vs. age-matched lean adolescents. Significant inverse relationships were observed between adiponectin and inflammatory factors, insulinemia, insulin resistance, and fat mass. Intervention produced a 34% increase in adiponectin concentration (p=0.0004) despite negligible weight loss but with reductions in fat mass, hyperinsulinemia, insulin resistance, and inflammatory factors (all p<0.01)."
"The data suggest," concluded the authors, "that in adolescents, obesity-related hypoadiponectinemia is associated with subclinical inflammation, and a short-term lifestyle intervention augments adiponectin concentrations. These effects appear to be related to reductions in fat mass and inflammatory factors. Based on our current understanding of adiponectin physiology, reversal of hypoadiponectinemia in obese adolescents may protect against risks for cardiovascular disease and diabetes."
Balagopal and colleagues published their study in the Journal of Clinical Endocrinology and Metabolism (Reversal of obesity-related hypoadiponectinemia by lifestyle intervention: A controlled, randomized study in obese adolescents. J Clin Endocrinol Metab, 2005;90(11):6192-6197).
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