Change in body composition during a weight loss trial in obese adolescents.

UNLABELLED: What is already known about this subject Adolescence is an important period of physiological growth. Loss of central adiposity with preservation of lean mass during weight loss is optimal. There are discrepancies in the literature concerning changes in lean mass during weight loss in adolescents. What this study adds This study provides information of regional and total body composition change in adolescents during weight loss. This study controls for important factors that impact body composition in growing adolescents such as age, sex, height, baseline weight and race. This study provides correlations of changes in waist circumference and body mass index (BMI) with total and trunk fat mass during weight loss in adolescents. SUMMARY: Background Changes in body composition during weight loss among obese adolescents are poorly understood. This study characterized the composition of weight loss and its association with changes in waist circumference (WC) in obese adolescents. Methods Total (Tot), trunk (Tr) and appendicular (Ap) fat mass (FM) and lean mass (LM) were measured by dual-energy X-ray absorptiometry in 61 obese adolescents (40 girls) who participated in a randomized controlled weight loss trial. Changes in body composition were assessed at 0, 6 and 12 months using mixed-effects regression models. Correlation analysis of change in WC and total and regional compartments of FM and LM were assessed. Results Weight loss for adolescents was 90.3% FM and 15.9% LM at 0-6 months, and 98.2% FM and 7% LM at 0-12 months. At 12 months, girls lost 2.67 kg more TotFM than boys in models adjusted for height, age, race and baseline weight. Boys gained LM in all compartments in all models. At 12 months, girls lost TotLM (2.23 ± 0.74, P < 0.004) and ApLM (0.69 ± 0.31, P = 0.03) and gained TrLM (0.37 ± 0.35, P = 0.29). The percentage LM, increased for boys and girls in all models. TotFM was correlated with body mass index (BMI) change with TotFM (R = 0.70-0.91, P = 0.001) and WC change (R = 0.53-0.55, P < 0.001). Conclusions Weight loss in obese adolescents during a weight loss trial using lifestyle management and sibutramine was primarily from trunk FM. Although absolute LM increased in boys and decreased in girls, the percentage of weight that is LM increased for both boys and girls. Changes in BMI were more reflective of changes in FM than changes in WC.

Resting energy expenditure and adiposity accretion among children with Down syndrome: a 3-year prospective study.

BACKGROUND: Children with Down syndrome (DS) have a higher prevalence of obesity than other children. Whether this increased risk for obesity is due to a lower resting energy expenditure (REE) is controversial. Our study assessed whether (1) the REE of children with DS adjusted for fat-free mass (FFM) was lower than that of sibling controls, and (2) the changes in fat mass (FM) over 3 years were associated with FFM-adjusted baseline REE. METHODS: This study used cross-sectional and prospective cohort designs. Four annual measurement visits were conducted with 28 children with DS and 35 sibling controls aged 3-10 years. REE and serum thyroxine (T4) were measured at baseline. Anthropometry, skinfold thickness measures, and, in a subsample, dual-energy x-ray absorptiometry (DXA) were used at each visit to calculate FM. RESULTS: Children with DS had significantly lower REE adjusted for FFM (-78 kcal/day, 95% CI: -133 to -27, P=0.003). The difference remained significant after adjustment for FM, sex and African ancestry (-49 kcal/day, 95% CI: -94 to -4, P=0.03). In the longitudinal analysis, the baseline REE adjusted for baseline FFM was not predictive of FM accretion over time (P=0.8). CONCLUSION: Children with DS have lower REE than sibling controls, but REE was not associated with changes in FM over time. The results suggest that the lower REE of children with DS does not explain their increased risk for obesity.

A rat glioma model, CNS-1, with invasive characteristics similar to those of human gliomas: a comparison to 9L gliosarcoma.

A glioma cell line, CNS-1, was developed in the inbred Lewis rat to obtain a histocompatible astrocytoma cell line with infiltrative and growth patterns that more closely simulate those observed in human gliomas. Rats were given weekly intravenous injections for a six month period with N-nitroso-N-methylurea to produce neoplasm in the central nervous system. Intracranial tumor was isolated, enzymatically and mechanically digested, and placed into culture. The tumor cell line injected subcutaneously on the flanks of Lewis rats grew extensively in situ as cohesive tumor masses but did not metastasize. Intracranially, CNS-1 demonstrated single cell infiltration of paranchyma and leptomeningeal, perivascular, and periventricular spread with expansion of the tumor within choroid plexus stroma. CNS-1 cells titrated in right frontal brain of Lewis rats at 10(5), 5 x 10(5), 10(5), 5 x 10(4) cells per group had mean survival times ranging from 20.5 to 30.2 days. CNS-1 was immunoreactive for glial fibrillary acidic protein, S100 protein, vimentin, neural cell adhesion molecule, retinoic acid receptor alpha, intercellular adhesion molecule, and neuron specific enolase. The CNS-1 cells commonly had one or more trisomies of chromosomes 11, 13 or 18; losses, possibly random, of chromosomes (3, 5, 19, 30, X or Y) were noticed, and a marker chromosome made up of approximately 3 chromosomes was usual. Comparisons of CNS-1 to 9L gliosarcoma tumor were made. The glial CNS-1 tumor model provides an excellent system in which to investigate a variety of immunological therapeutic modalities. It spreads within brain in a less cohesive mass than 9L and is accepted without rejection in non-central nervous system sites by Lewis rats.