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Burlington, MA, United States

Richmond T.K.,Boston Childrens Hospital | Thurston I.,University of Memphis | Sonneville K.,Boston Childrens Hospital | Milliren C.E.,Clinical Research Center | And 3 more authors.
International Journal of Obesity

Surveillance data describing the weight status of the US population often rely on self-reported height and weight, despite likely differences in reporting accuracy by demographics. Our objective was to determine if there were racial/ethnic differences in accuracy of self-reported body mass index (BMI) in a diverse nationally representative sample of young people. Using data from Wave III (data collected in 2001-2002) of the National Longitudinal Study of Adolescent Health when respondents were aged 18-26, we used gender-stratified multivariable linear regression models to examine the association of race/ethnicity and self-reported BMI controlling for measured BMI while also adjusting for factors known to be associated with weight self-perception. Black males and females (b Female =0.45, confidence interval (CI): 0.19, 0.71; b Male =0.34, CI: 0.17, 0.51) and Hispanic females (b Female =0.30, CI: 0.08, 0.52) and Native American males (b Native American =0.87, CI: 0.15, 1.58) reported higher BMIs than their similarly weighted White peers, leading to more accurate BMI reporting in these groups at higher BMIs. Caution should be taken in interpreting results from studies relying on self-reported BMI, as they may exaggerate racial/ethnic differences in weight status. © 2015 Macmillan Publishers Limited. Source

Blagovic K.,Massachusetts Institute of Technology | Kim L.Y.,Massachusetts Institute of Technology | Kim L.Y.,Decision Resources Inc. | Voldman J.,Massachusetts Institute of Technology

Background: Autocrine & paracrine signaling are widespread both in vivo and in vitro, and are particularly important in embryonic stem cell (ESC) pluripotency and lineage commitment. Although autocrine signaling via fibroblast growth factor-4 (FGF4) is known to be required in mouse ESC (mESC) neuroectodermal specification, the question of whether FGF4 autocrine signaling is sufficient, or whether other soluble ligands are also involved in fate specification, is unknown. The spatially confined and closed-loop nature of diffusible signaling makes its experimental control challenging; current experimental approaches typically require prior knowledge of the factor/receptor in order to modulate the loop. A new approach explored in this work is to leverage transport phenomena at cellular resolution to downregulate overall diffusible signaling through the physical removal of cell-secreted ligands. Methodology/Principal Findings: We develop a multiplex microfluidic platform to continuously remove cell-secreted (autocrine\paracrine) factors to downregulate diffusible signaling. By comparing cell growth and differentiation in side-by-side chambers with or without added cell-secreted factors, we isolate the effects of diffusible signaling from artifacts such as shear, nutrient depletion, and microsystem effects, and find that cell-secreted growth factor(s) are required during neuroectodermal specification. Then we induce FGF4 signaling in minimal chemically defined medium (N2B27) and inhibit FGF signaling in fully supplemented differentiation medium with cell-secreted factors to determine that the non-FGF cell-secreted factors are required to promote growth of differentiating mESCs. Conclusions/Significance: Our results demonstrate for the first time that flow can downregulate autocrine\paracrine signaling and examine sufficiency of extracellular factors. We show that autocrine\paracrine signaling drives neuroectodermal commitment of mESCs through both FGF4-dependent and -independent pathways. Overall, by uncovering autocrine\paracrine processes previously hidden in conventional culture systems, our results establish microfluidic perfusion as a technique to study and manipulate diffusible signaling in cell systems. © 2011 Blagovic et al. Source

Bickham D.S.,Center on Media and Child Health | Bickham D.S.,Harvard University | Blood E.A.,Boston Childrens Hospital | Blood E.A.,Harvard University | And 7 more authors.

OBJECTIVES: This study investigates how characteristics of young adolescents' screen media use are associated with their BMI. By examining relationships between BMI and both time spent using each of 3 screen media and level of attention allocated to use, we sought to contribute to the understanding of mechanisms linking media use and obesity. METHODS: We measured heights and weights of 91 13- to 15-year-olds and calculated their BMIs. Over 1 week, participants completed a weekday and a Saturday 24-hour time-use diary in which they reported the amount of time they spent using TV, computers, and video games. Participants carried handheld computers and responded to 4 to 7 random signals per day by completing onscreen questionnaires reporting activities to which they were paying primary, secondary, and tertiary attention. RESULTS: Higher proportions of primary attention to TV were positively associated with higher BMI. The difference between 25th and 75th percentiles of attention to TV corresponded to an estimated +2.4 BMI points. Time spent watching television was unrelated to BMI. Neither duration of use nor extent of attention paid to video games or computers was associated with BMI. CONCLUSIONS: These findings support the notion that attention to TV is a key element of the increased obesity risk associated with TV viewing. Mechanisms may include the influence of TV commercials on preferences for energy-dense, nutritionally questionable foods and/or eating while distracted by TV. Interventions that interrupt these processes may be effective in decreasing obesity among screen media users. Copyright © 2013 by the American Academy of Pediatrics. Source

Richmond T.K.,Boston Childrens Hospital | Spadano-Gasbarro J.L.,Harvard University | Walls C.E.,Decision Resources Inc. | Austin S.B.,Boston Childrens Hospital | And 5 more authors.
Preventive Medicine

Background: Prior studies have demonstrated disproportionate clustering of fast food outlets around schools. Purpose: The purpose of this study is to determine if racial/ethnic differences in middle school student self-reported sugar-sweetened beverage (SSB) consumption is explained by differential distributions of food outlets surrounding their schools. Methods: Baseline (2005) data were analyzed from 18,281 middle school students in 47 Massachusetts schools participating in Healthy Choices, an obesity prevention program. Linear mixed effects models were used to examine the association of individual race/ethnicity and daily SSB consumption and the potential mediating effect of the density of food outlets (the number of fast food outlets and convenience stores in a 1500. m buffer area surrounding the school) on this association adjusting for individual and school demographics. Results: More SSB consumption was reported by students of all racial/ethnic minority groups compared to their White peers except Asians. The density of fast food restaurants and convenience stores was not associated with individual SSB consumption (β = 0.001, p = 0.875) nor did it mediate the association of race/ethnicity and SSB consumption. Conclusions: Racial and ethnic differences in SSB consumption among MA middle school students cannot be fully explained by the location of fast food restaurants and convenience stores. © 2013. Source

Baer T.E.,Boston Childrens Hospital | Milliren C.E.,Boston Childrens Hospital | Milliren C.E.,Clinical Research Center | Walls C.,Decision Resources Inc. | DiVasta A.D.,Boston Childrens Hospital
Journal of Pediatric and Adolescent Gynecology

Study Objectives: To review the clinical presentation, evaluation, and management of normal-weight (NW), overweight (OW), and obese (OB) adolescent and young adult women with polycystic ovary syndrome (PCOS) during a 2-year follow-up. Design: Retrospective chart review. Participants: One hundred seventy-three adolescent and young adult women, aged 12-22 years, diagnosed with PCOS. Interventions: Demographic, health data, and laboratory measures were abstracted from 3 clinic visits: baseline and 1- and 2-year follow-up. Subjects were classified as NW, OW, or OB. Longitudinal data were analyzed using repeated-measures analysis of variance. Main Outcome Measures: Body mass index, self-reported concerns, and lifestyle changes. Results: Most patients (73%) were OW or OB. Family history of type 2 diabetes was greater in OW (38%) and OB (53%) patients compared with NW (22%) patients ( P = .002). Acanthosis nigricans was identified in OW (62%) and OB (21%) patients but not in NW patients (0%; P < .001). OW and OB patients had higher fasting insulin ( P < .001) and lower high-density lipoprotein cholesterol ( P = .005) levels than NW patients, although screening rates were low. Body mass index Z-scores decreased in both OW and OB patients over time (0.07 unit/yr, P < .001). Conclusions: Most patients with PCOS were OW or OB. Substantial clinical variability existed in cardiovascular disease (CVD) screening; among those screened, OW and OB patients had greater CVD risk factors. Despite self-reported concerns about weight and diabetes risk among OW and OB patients, no clinically significant change in body mass index percentile occurred. Evidence-based interventions and recommendations for screening tests are needed to address CVD risk in adolescents and young adults with PCOS. © 2015 North American Society for Pediatric and Adolescent Gynecology. Source

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