Publications by authors named "Maciej S Buchowski"

79 Publications

A standard calculation methodology for human doubly labeled water studies.

Cell Rep Med 2021 Feb 16;2(2):100203. Epub 2021 Feb 16.

Maastricht University, Maastricht, the Netherlands.

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (<10 kg). Using data for 1,021 babies and infants, we show that the DSR varies non-linearly with body mass between 0 and 10 kg. Using this relationship to predict DSR from weight provides an equation for rCO over this size range that agrees well with indirect calorimetry (average difference 0.64%; SD = 12.2%). We propose adoption of these equations in future studies.
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http://dx.doi.org/10.1016/j.xcrm.2021.100203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7897799PMC
February 2021

Identifying bedrest using waist-worn triaxial accelerometers in preschool children.

PLoS One 2021 28;16(1):e0246055. Epub 2021 Jan 28.

Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Energy Balance Laboratory, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.

Purpose: To adapt and validate a previously developed decision tree for youth to identify bedrest for use in preschool children.

Methods: Parents of healthy preschool (3-6-year-old) children (n = 610; 294 males) were asked to help them to wear an accelerometer for 7 to 10 days and 24 hours/day on their waist. Children with ≥3 nights of valid recordings were randomly allocated to the development (n = 200) and validation (n = 200) groups. Wear periods from accelerometer recordings were identified minute-by-minute as bedrest or wake using visual identification by two independent raters. To automate visual identification, chosen decision tree (DT) parameters (block length, threshold, bedrest-start trigger, and bedrest-end trigger) were optimized in the development group using a Nelder-Mead simplex optimization method, which maximized the accuracy of DT-identified bedrest in 1-min epochs against synchronized visually identified bedrest (n = 4,730,734). DT's performance with optimized parameters was compared with the visual identification, commonly used Sadeh's sleep detection algorithm, DT for youth (10-18-years-old), and parental survey of sleep duration in the validation group.

Results: On average, children wore an accelerometer for 8.3 days and 20.8 hours/day. Comparing the DT-identified bedrest with visual identification in the validation group yielded sensitivity = 0.941, specificity = 0.974, and accuracy = 0.956. The optimal block length was 36 min, the threshold 230 counts/min, the bedrest-start trigger 305 counts/min, and the bedrest-end trigger 1,129 counts/min. In the validation group, DT identified bedrest with greater accuracy than Sadeh's algorithm (0.956 and 0.902) and DT for youth (0.956 and 0.861) (both P<0.001). Both DT (564±77 min/day) and Sadeh's algorithm (604±80 min/day) identified significantly less bedrest/sleep than parental survey (650±81 min/day) (both P<0.001).

Conclusions: The DT-based algorithm initially developed for youth was adapted for preschool children to identify time spent in bedrest with high accuracy. The DT is available as a package for the R open-source software environment ("PhysActBedRest").
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246055PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7842939PMC
June 2021

Early postoperative physical activity and function: a descriptive case series study of 53 patients after lumbar spine surgery.

BMC Musculoskelet Disord 2020 Nov 27;21(1):783. Epub 2020 Nov 27.

Department of Orthopaedic Surgery, Center for Musculoskeletal Research, Vanderbilt University Medical Center, 1215 21st Avenue South, Medical Center East - South Tower, Suite 4200, Nashville, TN, 37232, USA.

Background: The purpose of this prospective case series study was to compare changes in early postoperative physical activity and physical function between 6 weeks and 3 and 6 months after lumbar spine surgery.

Methods: Fifty-three patients (mean [95% confidence interval; CI] age = 59.2 [56.2, 62.3] years, 64% female) who underwent spine surgery for a degenerative lumbar condition were assessed at 6 weeks and 3- and 6-months after surgery. The outcomes were objectively-measured physical activity (accelerometry) and patient-reported and objective physical function. Physical activity was assessed using mean steps/day and time spent in moderate to vigorous physical activity (MVPA) over a week. Physical function measures included Oswestry Disability Index (ODI), 12-item Short Form Health Survey (SF-12), Timed Up and Go (TUG), and 10-Meter Walk (10 MW). We compared changes over time in physical activity and function using generalized estimating equations with robust estimator and first-order autoregressive covariance structure. Proportion of patients who engaged in meaningful physical activity (e.g., walked at least 4400 and 6000 steps/day or engaged in at least 150 min/week in MVPA) and achieved clinically meaningful changes in physical function were compared at 3 and 6 months.

Results: After surgery, 72% of patients initiated physical therapy (mean [95%CI] sessions =8.5 [6.6, 10.4]) between 6 weeks and 3 months. Compared to 6 weeks post-surgery, no change in steps/day or time in MVPA/week was observed at 3 or 6 months. From 21 to 23% and 9 to 11% of participants walked at least 4400 and 6000 steps/day at 3 and 6 months, respectively, while none of the participants spent at least 150 min/week in MVPA at these same time points. Significant improvements were observed on ODI, SF-12, TUG and 10 MW (p <  0.05), with over 43 to 68% and 62 to 87% achieving clinically meaningful improvements on these measures at 3 and 6 months, respectively.

Conclusion: Limited improvement was observed in objectively-measured physical activity from 6 weeks to 6 months after spine surgery, despite moderate to large function gains. Early postoperative physical therapy interventions targeting physical activity may be needed.
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http://dx.doi.org/10.1186/s12891-020-03816-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7697379PMC
November 2020

Patterns and correlates of sleep duration in the Southern cohort community study.

Sleep Med 2020 11 10;75:459-467. Epub 2020 Sep 10.

Division of Gastroenterology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA. Electronic address:

Objective: To investigate whether race (African American (AA) and white) is associated with sleep duration among adults from low socioeconomic (SES) strata and whether SES status, lifestyle behaviors, or health conditions are associated with sleep duration within race-sex groups.

Methods: This cross-sectional study includes 78,549 participants from the Southern Community Cohort Study (SCCS). Averaged daily sleep duration was assessed by weighted averages of self-reported sleep duration on weekdays and weekends. Adjusted odds ratios (ORs) of very short (<5 h/day), short (5-6 h/day), and long sleep (≥9 h/day) associated with pre-selected risk factors in each race-sex group were determined by multinomial logistic models.

Results: The prevalence of very short and short sleep was similar among AAs (6.2% and 29.1%) and whites (6.5% and 29.1%). Long sleep was considerably more prevalent among AAs (19.3%) than whites (13.0%). Very short sleep was associated with lower education and family income, with stronger associations among whites. Higher physical activity levels significantly decreased odds for both very short (OR = 0.80) and long sleep (OR = 0.78). Smoking, alcohol use, and dietary intake were not associated with sleep duration. Regardless of race or sex, very short, short, and long sleep were significantly associated with self-reported health conditions, especially depression (ORs were 2.06, 1.33, and 1.38, respectively).

Conclusions: Sleep duration patterns differed between AAs and whites from the underrepresented SCCS population with low SES. Sleep duration was associated with several socioeconomic, health behaviors, and health conditions depending on race and sex.
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http://dx.doi.org/10.1016/j.sleep.2020.09.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7669688PMC
November 2020

Functional Properties and Antioxidant Activity of L. Leaves var. Zolwinska Wielkolistna (WML-P)-The Effect of Controlled Conditioning Process.

Antioxidants (Basel) 2020 Jul 26;9(8). Epub 2020 Jul 26.

Institute of Natural Fibres and Medicinal Plants, Wojska Polskiego 71 B, 60-630 Poznan, Poland.

This study evaluated the effect of adding a new step, termed conditioning, to the traditional processing of leaves from var. zolwinska wielkolistna grown in Poland (WML-P). This step, modeled on tea leaves processing, was conducted in a controlled environment on a semi-technical scale. The primary goal was to evaluate the effect of the WML-P conditioning for 1-4 h at 32-35 °C on the content of bioactive compounds (total phenolics, phenolic acids, flavonols, 1-deoxynojirimycin) and antioxidant activity (radical scavenging against DPPH, antioxidant capacity, chelating activity and ferric reducing antioxidant potential) of the lyophilized extracts. For the first time WML-P extracts content was comprehensively characterized by assessing dietary fiber fractions, fatty acids, amino acids, macro- and microelements and chlorophyll content. Compared to the traditional process, adding the conditioning step to WML-P processing resulted in an increased total phenolics content, radical scavenging capacity, ability to quench 2,2-diphenyl-1-picrylhydrazyl (DPPH) and iron-chelating ability in the lyophilized extracts. The beneficial effect depended on conditioning time. The highest flavonols and phenolic acids content were found after 2-h conditioning. We concluded that adding a 2-h conditioning step to traditional WML-P processing results in getting WML-P lyophilized extract with increased bioactive compounds content and high antioxidant activity.
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http://dx.doi.org/10.3390/antiox9080668DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463858PMC
July 2020

Assessing Physical Activity Using Accelerometers in Youth with Duchenne Muscular Dystrophy.

J Neuromuscul Dis 2020 ;7(3):331-342

Energy Balance Laboratory, Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.

Background: Physical activity, assessed by accelerometers, has been proposed as a quantitative outcome measure for patients with DMD, but research is limitedObjective:To assess the total amount and patterns of physical activity in patients with DMD using accelerometers.

Methods: Physical activity was assessed in patients with DMD (n = 49, 13.6±4.0-year-old) and age- and sex-matched healthy controls (n = 15, 14.0±2.3-year-old) using wrist- and ankle-worn accelerometers. To assess the amount of activity, accelerometer recordings were converted into acceleration estimates (counts/min). Patterns of activity were assessed as the time that participants spent in sedentary, low-intensity, and moderate-to-vigorous physical activity categories. The sedentary category was divided into three (sedentary -1, -2, and -3) and the low-intensity into two (low-intensity-1, and -2) subcategories.

Results: Physical activity across intensity categories differed between study groups (p < 0.001). Patients with DMD spent on average 98.8% of their daytime in the sedentary and low-intensity categories. Compared to non-ambulatory, ambulatory patients spent more time in sedentary-3 and low-intensity-2 subcategories (p < 0.001). Amount of activity was lower in all patients than controls (p < 0.05) and in non-ambulatory than ambulatory patients and controls (p < 0.001), but similar between ambulatory patients and controls. Activity measures in patients were significantly affected by age and ambulation status (p < 0.05) but not corticosteroid use.

Conclusion: Patients with DMD spent most of their daytime in sedentary and low-intensity activities. Dividing these intensities into three and two subcategories, respectively, allows better characterization of activity patterns in DMD. Ambulation status and age but not corticosteroid use affected activity measures in patients with DMD.
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http://dx.doi.org/10.3233/JND-200478DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7369107PMC
March 2021

Beyond ambulation: Measuring physical activity in youth with Duchenne muscular dystrophy.

Neuromuscul Disord 2020 04 20;30(4):277-282. Epub 2020 Feb 20.

Thomas P Graham Division of Pediatric Cardiology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States.

Patients with Duchenne muscular dystrophy (DMD) develop skeletal muscle weakness and cardiomyopathy. Validated skeletal muscle outcome measures are limited to ambulatory patients, but most DMD patients in cardiac trials are non-ambulatory. New objective functional assessments are needed. This study's objective was to assess the correlation and longitudinal change of two measures: quantitative muscle testing (QMT) and accelerometry. Patients with DMD were prospectively enrolled and underwent QMT and wore wrist and ankle accelerometers for seven days at baseline, 1-, and 2-years. QMT measures were indexed to age. Accelerometer recordings were total vector magnitudes and awake vector magnitude. Correlations were assessed using a Spearman correlation, and longitudinal change was evaluated using a paired t-test or a Wilcoxon signed rank test. Forty-eight participants were included. QMT and accelerometry measures had a moderate or strong correlation, particularly indexed arm QMT with total wrist vector magnitude (rho=0.85, p<0.001), total indexed QMT with total wrist vector magnitude (rho=0.8, p<0.001) and indexed leg QMT with total ankle vector magnitude (rho=0.69, p<0.001). QMT and accelerometry measures declined significantly over time. Accelerometry correlates with QMT and indexed QMT in boys with DMD. A combination of QMT and accelerometry may provide a complementary assessment of skeletal muscle function in non-ambulatory boys with DMD.
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http://dx.doi.org/10.1016/j.nmd.2020.02.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7234926PMC
April 2020

Effects of fibre-rich rye milling fraction on the functional properties and nutritional quality of wholemeal rye bread.

J Food Sci Technol 2020 Jan 26;57(1):222-232. Epub 2019 Aug 26.

1Institute of Food Technology of Plant Origin, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznan, Poland.

The goal was to assess the effects of partial replacement of wholemeal rye flour with 30%, 40% and 50% of the high-fibre rye flour (HFRF) on nutritional quality and sensory and physicochemical characteristics of breads. The HFRF supplemented breads (SB30, SB40, SB50) were compared in their nutrients and energy contents, physicochemical and sensory properties, and in vitro digestibility to the control bread (CB). There were no significant differences in shape and volume of loaves, crusts and crumbs appearance, taste and smell of two supplemented breads (SB30 and SB40) and the CB. Compared to the CB, all supplemented breads contained significantly more soluble and insoluble fibre, arabinoxylan and β-glucan, but less available saccharides, including rapidly available glucose. Bread with 40% HFRF (SB40) yielded both, improved nutritional quality and acceptable sensory characteristics comparable to the CB. An in vitro overall digestibility of the SB40 was lower than that of the CB but the losses of dietary fibre and its components after enzymatic digestion were comparable between both breads. In conclusion, rye bread supplemented with 40% of the HFRF had improved nutritional quality and acceptable sensory and physicochemical characteristics and could be considered as an option to commonly consumed wholemeal rye bread.
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http://dx.doi.org/10.1007/s13197-019-04050-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6952513PMC
January 2020

Food intake of folate, folic acid and other B vitamins with lung cancer risk in a low-income population in the Southeastern United States.

Eur J Nutr 2020 Mar 5;59(2):671-683. Epub 2019 Mar 5.

Division of Epidemiology, Department of Medicine, Vanderbilt Epidemiology Center and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN, 37232, USA.

Purpose: We prospectively examined associations of lung cancer risk with food intake of B vitamins involved in one-carbon metabolism and the use of folic acid-containing supplements among a low-income population of black and white adults in the Southeastern US.

Methods: Within the Southern Community Cohort Study, we included 1064 incident lung cancer cases among 68,236 participants aged 40-79 years at study enrollment. Food intake and the use of folic acid-containing supplements were assessed using a validated food frequency questionnaire at study enrollment. Multivariate Cox regression was used to estimate hazards ratios (HRs) and the 95% confidence intervals (CIs).

Results: Folate and/or folic acid intake from food were not associated with lung cancer risk; HRs (95% CI) for highest compared with lowest quartile were 1.08 (0.91-1.29) for total dietary folate, 1.00 (0.84-1.19) for food folate, and 1.09 (0.91-1.30) for food folic acid, respectively. Similarly, no associations were observed after stratifying by sex, race and smoking status, except for a positive association with total dietary folate intake among black women (HR 1.46, 95% CI 1.04-2.05 for the highest quartile compared with the lowest quartile, P trend = 0.02). Neither the use of folic acid-containing supplements nor food intake of vitamin B, vitamin B and riboflavin were associated with lung cancer risk.

Conclusions: Our findings do not support a protective effect of folate or folic acid for lung cancer prevention in a low-income population of black and white adults in the Southeastern US. Our finding of a positive association with total dietary folate intake among black women needs to be interpreted with caution and replicated in other studies.
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http://dx.doi.org/10.1007/s00394-019-01934-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6728240PMC
March 2020

Physical Activity Levels and Cardiometabolic Risks in Obese African American Adults: A Pilot Intervention Study.

J Health Care Poor Underserved 2018 ;29(3):1027-1045

Limited information is available regarding the effects of physical activity on risks of cardiometabolic diseases among obese African American adults. We conducted a church-based 12-week weight control and cardiometabolic risk reduction intervention (n=30, 22 females, 56.7±11.4 years old, BMI 37.4±6.7 kg/m2), after which body weight was slightly reduced (98.3±18.4 and 97.3±19 kg, p=.052); body fat percentage was significantly decreased among males (34.7±8.9 to 28.5±8.4 %; p=.049); and walking steps were increased, but not significantly. Among measured cardiometabolic risk biomarkers, hemoglobin A1c (HbA1c) was decreased significantly (6.8±1.1 to 6.1±1.1%; p=.0004) while time spent in sedentary behaviors was associated with less favorable change in total cholesterol (β=11.49, SE=3.55, p=.003) and tumor necrosis factor (TNF-α, β=0.3, SE=0.13, p=.038). Our study shows that adiposity reduction was feasible through a short-term healthy lifestyle program for obese African American adults, and suggests that reducing sedentary behaviors through light physical activity might lead to a decrease in cardiovascular risks.
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http://dx.doi.org/10.1353/hpu.2018.0077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7927573PMC
April 2019

Effect of a Behavioral Intervention for Underserved Preschool-Age Children on Change in Body Mass Index: A Randomized Clinical Trial.

JAMA 2018 08;320(5):450-460

Department of Nutrition and Epidemiology, The University of North Carolina at Chapel Hill Gillings School of Global Public Health.

Importance: Prevention of obesity during childhood is critical for children in underserved populations, for whom obesity prevalence and risk of chronic disease are highest.

Objective: To test the effect of a multicomponent behavioral intervention on child body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) growth trajectories over 36 months among preschool-age children at risk for obesity.

Design, Setting, And Participants: A randomized clinical trial assigned 610 parent-child pairs from underserved communities in Nashville, Tennessee, to a 36-month intervention targeting health behaviors or a school-readiness control. Eligible children were between ages 3 and 5 years and at risk for obesity but not yet obese. Enrollment occurred from August 2012 to May 2014; 36-month follow-up occurred from October 2015 to June 2017.

Interventions: The intervention (n = 304 pairs) was a 36-month family-based, community-centered program, consisting of 12 weekly skills-building sessions, followed by monthly coaching telephone calls for 9 months, and a 24-month sustainability phase providing cues to action. The control (n = 306 pairs) consisted of 6 school-readiness sessions delivered over the 36-month study, conducted by the Nashville Public Library.

Main Outcomes And Measures: The primary outcome was child BMI trajectory over 36 months. Seven prespecified secondary outcomes included parent-reported child dietary intake and community center use. The Benjamini-Hochberg procedure corrected for multiple comparisons.

Results: Participants were predominantly Latino (91.4%). At baseline, the mean (SD) child age was 4.3 (0.9) years; 51.9% were female. Household income was below $25 000 for 56.7% of families. Retention was 90.2%. At 36 months, the mean (SD) child BMI was 17.8 (2.2) in the intervention group and 17.8 (2.1) in the control group. No significant difference existed in the primary outcome of BMI trajectory over 36 months (P = .39). The intervention group children had a lower mean caloric intake (1227 kcal/d) compared with control group children (1323 kcal/d) (adjusted difference, -99.4 kcal [95% CI, -160.7 to -38.0]; corrected P = .003). Intervention group parents used community centers with their children more than control group parents (56.8% in intervention; 44.4% in control) (risk ratio, 1.29 [95% CI, 1.08 to 1.53]; corrected P = .006).

Conclusions And Relevance: A 36-month multicomponent behavioral intervention did not change BMI trajectory among underserved preschool-age children in Nashville, Tennessee, compared with a control program. Whether there would be effectiveness for other types of behavioral interventions or implementation in other cities would require further research.

Trial Registration: ClinicalTrials.gov Identifier: NCT01316653.
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http://dx.doi.org/10.1001/jama.2018.9128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6583104PMC
August 2018

Identifying bedrest using 24-h waist or wrist accelerometry in adults.

PLoS One 2018 23;13(3):e0194461. Epub 2018 Mar 23.

Energy Balance Laboratory, Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.

Objectives: To adapt and refine a previously-developed youth-specific algorithm to identify bedrest for use in adults. The algorithm is based on using an automated decision tree (DT) analysis of accelerometry data.

Design: Healthy adults (n = 141, 85 females, 19-69 years-old) wore accelerometers on the waist, with a subset also wearing accelerometers on the dominant wrist (n = 45). Participants spent ≈24-h in a whole-room indirect calorimeter equipped with a force-platform floor to detect movement.

Methods: Minute-by-minute data from recordings of waist-worn or wrist-worn accelerometers were used to identify bedrest and wake periods. Participants were randomly allocated to development (n = 69 and 23) and validation (n = 72 and 22) groups for waist-worn and wrist-worn accelerometers, respectively. The optimized DT algorithm parameters were block length, threshold, bedrest-start trigger, and bedrest-end trigger. Differences between DT classification and synchronized objective classification by the room calorimeter to bedrest or wake were assessed for sensitivity, specificity, and accuracy using a Receiver Operating Characteristic (ROC) procedure applied to 1-min epochs (n = 92,543 waist; n = 30,653 wrist).

Results: The optimal algorithm parameter values for block length were 60 and 45 min, thresholds 12.5 and 400 counts/min, bedrest-start trigger 120 and 400 counts/min, and bedrest-end trigger 1,200 and 1,500 counts/min, for the waist and wrist-worn accelerometers, respectively. Bedrest was identified correctly in the validation group with sensitivities of 0.819 and 0.912, specificities of 0.966 and 0.923, and accuracies of 0.755 and 0.859 by the waist and wrist-worn accelerometer, respectively. The DT algorithm identified bedrest/sleep with greater accuracy than a commonly used automated algorithm (Cole-Kripke) for wrist-worn accelerometers (p<0.001).

Conclusions: The adapted DT accurately identifies bedrest in data from accelerometers worn by adults on either the wrist or waist. The automated bedrest/sleep detection DT algorithm for both youth and adults is openly accessible as a package "PhysActBedRest" for the R-computer language.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194461PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5865746PMC
July 2018

Effects of Low Versus Moderate Glycemic Index Diets on Aerobic Capacity in Endurance Runners: Three-Week Randomized Controlled Crossover Trial.

Nutrients 2018 Mar 17;10(3). Epub 2018 Mar 17.

Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences, 60-624 Poznań, Poland.

The glycemic index (GI) of ingested carbohydrates may influence substrate oxidation during exercise and athletic performance. Therefore, the aim of this study was to assess the effect of low- and moderate-GI three-week diets on aerobic capacity and endurance performance in runners. We conducted a randomized crossover feeding study of matched diets differing only in GI (low vs. moderate) in 21 endurance-trained runners. Each participant consumed both, low- (LGI) and moderate-GI (MGI) high-carbohydrate (~60%) and nutrient-balanced diets for three weeks each. At the beginning and end of each diet, participants had their aerobic capacity and body composition measured and performed a 12-min running test. After LGI, time to exhaustion during incremental cycling test (ICT) and distance covered in the 12-min run were significantly increased. The MGI diet led to an increase in maximal oxygen uptake ( V ˙ O₂max), but no performance benefits were found after the MGI diet. The LGI and MGI diets improved time and workload at gas exchange threshold (GET) during ICT. The results indicate that a three-week high-carbohydrate LGI diet resulted in a small but significant improvement in athletic performance in endurance runners. Observed increase in V ˙ O₂max on MGI diet did not affect performance.
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http://dx.doi.org/10.3390/nu10030370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872788PMC
March 2018

Novel patterns of physical activity in a large sample of preschool-aged children.

BMC Public Health 2018 02 13;18(1):242. Epub 2018 Feb 13.

Department of Pediatrics, Vanderbilt University School of Medicine, 2200 Children's Way, Doctor's Office Tower 8232, Nashville, TN, 37232-9225, USA.

Background: Moderate-to-vigorous physical activity (MVPA), shown to be associated with health benefits, is not well-characterized in preschool-aged children. MVPA is commonly described as a threshold amount to achieve. We examined a novel way to characterize MVPA patterns in preschool-aged children by gender and age.

Methods: Preschool-aged children from Nashville, TN and Minneapolis, MN wore triaxial accelerometers. Four distinct MVPA patterns were identified: isolated spurt (IS), isolated sustained activity (ISA), clustered spurt (CS), and clustered sustained activity (CSA). Multivariable linear regression models were used to test associations of gender and age with each pattern.

Results: One thousand one hundred thirty-one children (3.9 years old, 51% girls, 30% overweight, 11% obese, and 76% Hispanic) wore accelerometers for 12.9 (SD = 1.4) hours/day for 6.7 (SD = 0.7) days. Children spent 53% of wear time in sedentary behavior and 13% in MVPA. On average, boys and girls achieved > 90 min/day of MVPA (98.2 min, SD = 32.3). Most MVPA (80%) was obtained in spurt-like (IS and CS) MVPA; however, girls spent a higher proportion of MVPA in IS and CS, and lower proportion of time in CSA (all p < 0.001). Controlling for gender, an increase of 1-year in age corresponded to a 1.5% increase in CSA (p < 0.05).

Conclusions: How MVPA was obtained varied depending on the gender and age of the child. On average, boys spent more time in sustained MVPA than girls and MVPA was more sustained in older children. Utilizing these patterns could inform PA practice and policy guidelines.

Trial Registration: NCT01316653 , date of registration: March 3, 2011; NCT01606891, date of registration: May 23, 2012.
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http://dx.doi.org/10.1186/s12889-018-5135-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812042PMC
February 2018

Refining a Church-Based Lifestyle Intervention Targeting African-American Adults at Risk for Cardiometabolic Diseases: A Pilot Study.

Open J Epidemiol 2017 May 21;7(2):96-114. Epub 2017 Apr 21.

Department of Internal Medicine, Meharry Medical College, Nashville, TN, USA.

Objective: The pilot study was intended to test the feasibility of a multiple-component lifestyle intervention targeting African American adults in a weight control and cardiometabolic risk reduction program on diet, activity, and stress, using community-engagement principles.

Methods: Applying mixed qualitative and quantitative measures, the intervention had a two-part sequential study design consisting of 12 weekly small group sessions that provided individual and group counseling in nutrition, exercise, and mindfulness, while incorporating focus group and interactive techniques to learn about barriers and acceptable practices for this population. The program was implemented at an African-American church in Nashville, Tennessee.

Results: Thirty-four participants (aged 56.1 ± 11 years, body mass index (BMI) 36.7 ± 6.6 kg/m) completed the intervention. Lifestyle changes after the 12 weekly sessions showed some positive trends including reduced sodium intake (from 2725.3 ± 326.5 to 2132 ± 330, mg/day, P = 0.008), increased walking steps (from 4392.1 ± 497.2 to 4895.3 ± 497.9, steps/day, not significant), and slightly decreased Perceived Stress Scale (PSS) scores (from 13.7 ± 1.4 to 12.4 ± 1.5, not significant). Body fat % among male participants decreased significantly (from 33.8 ± 2.6 to 28 ± 2.6, %, P = 0.043). Among cardiometabolic risk biomarkers, hemoglobin A1c (HbA1c) decreased significantly (from 6.6 ± 0.2 to 6.1 ± 0.2, %, P < 0.001). The baseline PSS score was positively associated with baseline adiposity levels (e.g., weight, = 2.4, P = 0.006). Twenty-one participants took part in focus groups during the program to identify barriers to healthy lifestyle changes. Primary barriers reported were price, time for preparing healthy meals, unfamiliarity with mindfulness activities, their health condition, and daily schedule available for physical activities.

Conclusions: This church-based pilot intervention was proven feasible by showing modest progress in reducing adiposity and decreasing HbA1c levels. The focus group and interactive methods facilitated program direction. Future full-scale studies are warranted to identify key strategies that provide more personalized approaches and supportive environments to sustain a healthy lifestyle among these at risk minorities with limited resources.
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http://dx.doi.org/10.4236/ojepi.2017.72009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808719PMC
May 2017

Association of gene coding variation and resting metabolic rate in a multi-ethnic sample of children and adults.

BMC Obes 2017 5;4:12. Epub 2017 Apr 5.

Division of Epidemiology, Department of Medicine, Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37203 USA.

Background: Resting metabolic rates (RMR) vary across individuals. Understanding the determinants of RMR could provide biological insight into obesity and its metabolic consequences such as type 2 diabetes and cardiovascular diseases.

Methods: The present study measured RMR using reference standard indirect calorimetry and evaluated genetic variations from an exome array in a sample of children and adults ( = 262) predominantly of African and European ancestry with a wide range of ages (10 - 67 years old) and body mass indices (BMI; 16.9 - 56.3 kg/m for adults, 15.1 - 40.6 kg/m2 for children).

Results: Single variant analysis for RMR identified suggestive loci on chromosomes 15 (rs74010762, , -value = 2.7 × 10-6), 1 (rs2358728 and rs2358729, , -values < 5.8x10-5), 17 (AX-82990792, , 5.5 × 10-5) and 5 (rs115795863 and rs35433829, and , -values < 8.2 × 10-5). To evaluate the effect of low frequency variations with RMR, we performed gene-based association tests. Our most significant locus was (-value 2.01 × 10-4), which also contained suggestive results from single-variant analyses. A further investigation of all variants within the reported genes for all obesity-related loci from the GWAS catalog found nominal evidence for association of body mass index (BMI- kg/m)-associated loci with RMR, with the most significant -value at rs35433754 (, -value = 0.0017).

Conclusions: These nominal associations were robust to adjustment for BMI. The most significant variants were also evaluated using phenome-wide association to evaluate pleiotropy, and genetically predicted gene expression using the summary statistics implicated loci related to in obesity and body composition. These results merit further examination in larger cohorts of children and adults.
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http://dx.doi.org/10.1186/s40608-017-0145-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381071PMC
April 2017

Physical Activity: A Viable Way to Reduce the Risks of Mild Cognitive Impairment, Alzheimer's Disease, and Vascular Dementia in Older Adults.

Brain Sci 2017 Feb 20;7(2). Epub 2017 Feb 20.

Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721-0038, USA.

A recent alarming rise of neurodegenerative diseases in the developed world is one of the major medical issues affecting older adults. In this review, we provide information about the associations of physical activity (PA) with major age-related neurodegenerative diseases and syndromes, including Alzheimer's disease, vascular dementia, and mild cognitive impairment. We also provide evidence of PA's role in reducing the risks of these diseases and helping to improve cognitive outcomes in older adults. Finally, we describe some potential mechanisms by which this protective effect occurs, providing guidelines for future research.
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http://dx.doi.org/10.3390/brainsci7020022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5332965PMC
February 2017

Parent's Physical Activity Associated With Preschooler Activity in Underserved Populations.

Am J Prev Med 2017 Apr 9;52(4):424-432. Epub 2017 Jan 9.

Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Introduction: In the U.S., children from low-income families are more likely to be obese. The impact of parent modeling of physical activity (PA) and sedentary behaviors in low-income American ethnic minorities is unclear, and studies examining objective measures of preschooler and parent PA are sparse.

Methods: This cross-sectional study examined 1,003 parent-child pairs who were of low income, largely Latino and African American, and living in one of two geographically disparate metropolitan areas in the U.S. Parents and children wore GT3X/GT3X+ accelerometers for an average of >12 hours/day (7:00am-9:00pm) for 1 week (September 2012 to May 2014). Analysis occurred in 2015-2016.

Results: About 75% of children were Latino and >10% were African American. Mean child age was 3.9 years. The majority of children (60%) were normal weight (BMI ≥50th and <85th percentiles), and more than a third were overweight/obese. Children's total PA was 6.03 hours/day, with 1.5 hours spent in moderate to vigorous PA (MVPA). Covariate-adjusted models showed a monotonic, positive association between parent and child minutes of sedentary behavior (β=0.10, 95% CI=0.06, 0.15) and light PA (β=0.06; 95% CI=0.03, 0.09). Child and parent MVPA were positively associated up to 40 minutes/day of parent MVPA, but an inverse association was observed when parental MVPA was beyond 40 minutes/day (p=0.002).

Conclusions: Increasing parental PA and reducing sedentary behavior correlate with increased PA-related behaviors in children. However, more work is needed to understand the impact of high levels of parental MVPA on the MVPA levels of their children.
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http://dx.doi.org/10.1016/j.amepre.2016.11.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5363267PMC
April 2017

Parental perception of built environment characteristics and built environment use among Latino families: a cross-sectional study.

BMC Public Health 2016 11 22;16(1):1180. Epub 2016 Nov 22.

Department of Pediatrics, Vanderbilt University Medical Center, 2146 Belcourt Ave, 2nd Floor, Nashville, TN, 37209, USA.

Background: Perception of undesirable features may inhibit built environment use for physical activity among underserved families with children at risk for obesity.

Methods: To examine the association of perceived availability, condition, and safety of the built environment with its self-reported use for physical activity, we conducted a cross-sectional analysis on baseline data from a randomized controlled trial. Adjusted Poisson regression was used to test the association between the primary independent variables (perceived availability, physical condition, and safety) with the primary outcome of self-reported use of built environment structures.

Results: Among 610 parents (90% Latino) of preschool-age children, 158 (26%) reported that there were no available built environment structures for physical activity in the neighborhood. The use of built environment structures was associated with the perceived number of available structures (B = 0.34, 95% CI 0.31, 0.37, p < 0.001) and their perceived condition (B = 0.19, 95% CI 0.12, 0.27, p = 0.001), but not with perceived safety (B = 0.00, 95% CI -0.01, 0.01, p = 0.7).

Conclusions: In this sample of underserved families, perceived availability and condition of built environment structures were associated with use rather than perceived safety. To encourage physical activity among underserved families, communities need to invest in the condition and availability of built environment structures.

Trial Registration: Registered at ClinicalTrials.gov ( NCT01316653 ) on March 11, 2011.
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http://dx.doi.org/10.1186/s12889-016-3854-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5120513PMC
November 2016

Plasma Lycopene Is Associated with Pizza and Pasta Consumption in Middle-Aged and Older African American and White Adults in the Southeastern USA in a Cross-Sectional Study.

PLoS One 2016 1;11(9):e0161918. Epub 2016 Sep 1.

Department of Internal Medicine, Meharry Medical College, Nashville, TN, 37208, United States of America.

Background: The role of dietary lycopene in chronic disease prevention is not well known.

Methods: This study examined intake of lycopene and other antioxidants from lycopene-rich foods (e.g., pizza and pasta) simultaneously with plasma levels of lycopene and other antioxidants in a representative cross-sectional sample (187 Blacks, 182 Whites, 40-79 years old) from the Southern Community Cohort Study (SCCS). The SCCS is an ongoing study conducted in populations at high risk for chronic diseases living in Southeastern United States. Dietary intake was assessed using a validated food frequency questionnaire (FFQ), and plasma levels of lycopene and other antioxidants were measured at baseline (2002-2005). The participants were classified into tertiles according to consumption of pizza and pasta food groups.

Results: Lycopene dietary intake and plasma lycopene concentrations were significantly higher in the highest (tertile 3) compared to tertiles 1 and 2 (both P < 0.01). Total energy intake ranged from 1964.3 ± 117.1 kcal/day (tertile 1) to 3277.7 ± 115.8 kcal/day (tertile 3) (P<0.0001). After adjusting for age and energy intake, total dietary fat, saturated fatty acids, trans-fatty acids, and sodium intakes were significantly higher in tertile 3 than tertiles 2 and 1 (all P <0.01). Vitamin C intake was significantly lower in tertile 3 than tertiles 1 and 2 (P = 0.003). Except for γ-tocopherol being higher in tertile 3 than tertiles 1 and 2 (P = 0.015), the plasma concentrations of antioxidants were lower in tertile 3 than tertiles 1 and 2 (β-carotene, α-carotene, lutein and zeaxanthin, all P<0.05).

Conclusions: In the SCCS population, pizza and pasta were the main sources of dietary lycopene and their intake was associated with plasma lycopene concentration. Diets with frequent pizza and pasta consumption were high in energy, saturated fatty acids, trans-fatty acids, sodium and low in other antioxidants. Future studies of lycopene as a protective dietary factor against chronic disease should consider the overall nutritional quality of lycopene-containing foods.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161918PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008825PMC
August 2017

Energy Expenditure of Common Sedentary Activities in Youth.

J Phys Act Health 2016 06;13(6 Suppl 1):S17-20

Albert Einstein School of Medicine, Bronx, New York.

Background: Standardized measures of energy expenditure (EE) for sedentary activities in youth are needed. The goal was to determine EE of common contemporary and computer-related sedentary activities in youth.

Methods: We measured EE for sedentary tasks in 10- to 17-year-old youths (n = 24) during ~24 hours in a whole-room indirect calorimeter. Directly monitored tasks were performed for ~10-min. EE was calculated from oxygen consumed and carbon dioxide produced, converted to metabolic equivalents (MET) by normalization to an individual's measured resting EE, and compared with the Compendium of Energy Expenditures for Youth.

Results: Compared with the youth compendium, measured METs were lower for internet surfing (1.3), computer keyboard typing (1.3), and sorting beads/crafts (1.5) (all P < .002), and similar for handwriting (1.4), playing cards (1.6), video-gaming (1.6), and telephoning (1.5).

Conclusions: Current youth compendium MET estimates should be used with caution when predicting EE of common contemporary and computer-related sedentary activities in youth.
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http://dx.doi.org/10.1123/jpah.2015-0727DOI Listing
June 2016

A 52-week pilot study of the effects of exenatide on body weight in patients with hypothalamic obesity.

Obesity (Silver Spring) 2016 06 2;24(6):1222-5. Epub 2016 May 2.

Division of Pediatric Endocrinology, Vanderbilt University, Nashville, Tennessee, USA.

Objective: Hypothalamic obesity (HO) is a common complication of hypothalamic tumors, and effective therapies are lacking. The objective of this pilot study was to investigate changes in body weight before and during treatment with exenatide.

Methods: This was a prospective, open-label, 52-week pilot study of exenatide (10 mcg b.i.d.) in adults with HO. Ten patients enrolled, and eight completed the study. Study measures included indirect calorimetry, body composition, buffet meals, diet recall, actigraphy, and hormone assays.

Results: Participants had obesity with a baseline weight of 137.2 ± 37.6 kg. Exenatide therapy was well tolerated. Change in weight with exenatide therapy was not significant (-1.4 ± 4.3 kg [95% CI -4.9 to 2.2], P = 0.40), but six out of eight completers lost weight (-6.2 to -0.2 kg). Participants reported significantly lower intake on food recall during treatment compared with baseline (7837.8 ± 2796.6 vs. 6258.4 ± 1970.7 kJ [95% CI -2915.8 to -242.6], P = 0.027), but there was no change in intake during buffet meals.

Conclusions: Significant weight loss was not observed in patients with HO treated with exenatide, but 75% of completers had stable or decreasing weight. Further studies are needed to evaluate weight loss efficacy in patients with HO.
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http://dx.doi.org/10.1002/oby.21493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882247PMC
June 2016

Physical activity, sedentary behavior and all-cause mortality among blacks and whites with diabetes.

Ann Epidemiol 2015 Sep 9;25(9):649-55. Epub 2015 Jun 9.

Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN.

Purpose: The study objective was to examine the role of physical activity (PA) and sedentary time (ST) on mortality risk among a population of low-income adults with diabetes.

Methods: Black (n = 11,137) and white (n = 4508) men and women with diabetes from the Southern Community Cohort Study self-reported total PA levels and total ST. Participants were categorized into quartiles of total PA and total ST. Hazard ratios (HRs) and 95% confidence intervals (CIs) for subsequent mortality risk were estimated from Cox proportional hazards analysis with adjustment for potential confounders.

Results: During follow-up, 2370 participants died. The multivariable risk of mortality was lower among participants in the highest quartile of PA compared with those in the lowest quartile (HR, 0.64; 95% CI: 0.57-0.73). Mortality risk was significantly increased among participants in the highest compared with the lowest quartile of ST after adjusting for PA (HR, 1.21; 95% CI: 1.08-1.37). Across sex and race groups, similar trends of decreasing mortality with rising PA and increasing mortality with rising ST were observed.

Conclusions: Although causality cannot be established from these observational data, the current findings suggest that increasing PA and decreasing ST may help extend survival among individuals with diabetes irrespective of race and sex.
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http://dx.doi.org/10.1016/j.annepidem.2015.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4602000PMC
September 2015

Healthy Eating and Risks of Total and Cause-Specific Death among Low-Income Populations of African-Americans and Other Adults in the Southeastern United States: A Prospective Cohort Study.

PLoS Med 2015 May 26;12(5):e1001830; discussion e1001830. Epub 2015 May 26.

Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, Tennessee, United States of America.

Background: A healthy diet, as defined by the US Dietary Guidelines for Americans (DGA), has been associated with lower morbidity and mortality from major chronic diseases in studies conducted in predominantly non-Hispanic white individuals. It is unknown whether this association can be extrapolated to African-Americans and low-income populations.

Methods And Findings: We examined the associations of adherence to the DGA with total and cause-specific mortality in the Southern Community Cohort Study, a prospective study that recruited 84,735 American adults, aged 40-79 y, from 12 southeastern US states during 2002-2009, mostly through community health centers that serve low-income populations. The present analysis included 50,434 African-Americans, 24,054 white individuals, and 3,084 individuals of other racial/ethnic groups, among whom 42,759 participants had an annual household income less than US$15,000. Usual dietary intakes were assessed using a validated food frequency questionnaire at baseline. Adherence to the DGA was measured by the Healthy Eating Index (HEI), 2010 and 2005 editions (HEI-2010 and HEI-2005, respectively). During a mean follow-up of 6.2 y, 6,906 deaths were identified, including 2,244 from cardiovascular disease, 1,794 from cancer, and 2,550 from other diseases. A higher HEI-2010 score was associated with lower risks of disease death, with adjusted hazard ratios (HRs) of 0.80 (95% CI, 0.73-0.86) for all-disease mortality, 0.81 (95% CI, 0.70-0.94) for cardiovascular disease mortality, 0.81 (95% CI, 0.69-0.95) for cancer mortality, and 0.77 (95% CI, 0.67-0.88) for other disease mortality, when comparing the highest quintile with the lowest (all p-values for trend < 0.05). Similar inverse associations between HEI-2010 score and mortality were observed regardless of sex, race, and income (all p-values for interaction > 0.50). Several component scores in the HEI-2010, including whole grains, dairy, seafood and plant proteins, and ratio of unsaturated to saturated fatty acids, showed significant inverse associations with total mortality. HEI-2005 score was also associated with lower disease mortality, with a HR of 0.86 (95% CI, 0.79-0.93) when comparing extreme quintiles. Given the observational study design, however, residual confounding cannot be completely ruled out. In addition, future studies are needed to evaluate the generalizability of these findings to African-Americans of other socioeconomic status.

Conclusions: Our results showed, to our knowledge for the first time, that adherence to the DGA was associated with lower total and cause-specific mortality in a low-income population, including a large proportion of African-Americans, living in the southeastern US.
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http://dx.doi.org/10.1371/journal.pmed.1001830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4444091PMC
May 2015

Physical activity, sedentary behavior, and cause-specific mortality in black and white adults in the Southern Community Cohort Study.

Am J Epidemiol 2014 Aug 1;180(4):394-405. Epub 2014 Aug 1.

There is limited evidence demonstrating the benefits of physical activity with regard to mortality risk or the harms associated with sedentary behavior in black adults, so we examined the relationships between these health behaviors and cause-specific mortality in a prospective study that had a large proportion of black adults. Participants (40-79 years of age) enrolled in the Southern Community Cohort Study between 2002 and 2009 (n = 63,308) were prospectively followed over 6.4 years, and 3,613 and 1,394 deaths occurred in blacks and whites, respectively. Black adults who reported the highest overall physical activity level (≥32.3 metabolic equivalent-hours/day vs. <9.7 metabolic equivalent-hours/day) had lower risks of death from all causes (hazard ratio (HR) = 0.76. 95% confidence interval (CI): 0.69, 0.85), cardiovascular disease (HR = 0.81, 95% CI: 0.67, 0.98), and cancer (HR = 0.76, 95% CI: 0.62, 0.94). In whites, a higher physical activity level was associated with a lower risk of death from all causes (HR = 0.76, 95% CI: 0.64, 0.90) and cardiovascular disease (HR = 0.69, 95% CI: 0.49, 0.99) but not cancer (HR = 0.95, 95% CI: 0.67, 1.34). Spending more time being sedentary (>12 hours/day vs. <5.76 hours/day) was associated with a 20%-25% increased risk of all-cause mortality in blacks and whites. Blacks who reported the most time spent being sedentary (≥10.5 hours/day) and lowest level of physical activity (<12.6 metabolic equivalent-hours/day) had a greater risk of death (HR = 1.47, 95% CI: 1.25, 1.71). Our study provides evidence that suggests that health promotion efforts to increase physical activity level and decrease sedentary time could help reduce mortality risk in black adults.
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http://dx.doi.org/10.1093/aje/kwu142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4128770PMC
August 2014

Insulin resistance is not associated with thermogenic effect of a high-fat meal in obese children.

Nutr Res 2014 Jun 11;34(6):486-90. Epub 2014 Jun 11.

Division of Pediatric Endocrinology, Vanderbilt University, Nashville, TN, USA. Electronic address:

In adults, insulin resistance may decrease the thermogenic effect of food, contributing to weight gain. We aimed to determine the effect of insulin resistance on energy expenditure in children with long-standing obesity. We hypothesized that thermogenic effect of food would decrease with increasing insulin resistance. Energy expenditure was measured using whole room indirect calorimetry in obese children 7 to 18 years old. Participants were fed a high-fat meal with energy content equal to 35% of measured resting energy expenditure. Thermogenic effect of food was measured for 180 minutes posttest meal and expressed as a percent of calories consumed. Body composition was assessed using whole-body dual-energy x-ray absorptiometry. Fasting glucose, insulin, and hemoglobin A1C were measured. Complete data were available for 25 children (median age, 12.1 years; 52% male). As expected, a significant decrease in resting energy expenditure was observed with increasing Tanner stage (P = .02 by Kruskal-Wallis test). Insulin sensitivity, as determined by homeostasis model assessment index equation, did not significantly affect resting energy expenditure (P = .3) or thermogenic effect of food (P = .7) after adjustment for Tanner stage. In conclusion, our study did not find an association between insulin resistance and energy expenditure in obese children.
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http://dx.doi.org/10.1016/j.nutres.2014.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4115362PMC
June 2014

Pigmented rice bran and plant sterol combination reduces serum lipids in overweight and obese adults.

J Am Coll Nutr 2014 ;33(3):231-8

a Nutritional Sciences (N.H.), and College of Public Health, Epidemiology and Biostatics (B.T.P.), University of Arizona , Tucson , Arizona ; Department of Food Nutrition and Health , University of British Columbia , Vancouver , British Columbia , CANADA (D.D.K., J.Z.); Department of Medicine, Clinical Research Center , Vanderbilt University , Nashville , Tennessee (C.M.D., M.S.B.); Department of Human Nutrition, Faculty of Food Technology , Agricultural University of Krakow , Krakow , POLAND (A.K.).

Objective: This study investigated the dietary effect of including pigmented rice bran with or without plant sterols on lipid profiles during energy restriction-induced weight loss in overweight and obese adults not taking cholesterol-lowering medication. In addition, the study examined the effect of intervention on biomarkers of oxidative stress and inflammation.

Methods: A group of 24 overweight and obese adults (age: 43 ± 6 years, body mass index 32 ± 1 kg/m(2), 18 females) were randomized to a 25% calorie-restricted diet containing either pigmented rice bran (RB) or the RB with addition of plant sterols (RB+PS) snack bars for 8 weeks. The individualized nutrient-balanced diet contained ∼70% of daily energy needs assessed from indirect calorimetry measured resting energy expenditure (EE) and physical activity-related EE assessed using accelerometry. Anthropometrics, blood pressure, blood lipids, glucose, urinary F2-isoprostanes, C-reactive protein, insulin, and leptin were measured at baseline and after 8 weeks of intervention.

Results: Participants lost approximately 4.7 ± 2.2 kg (p < 0.001). Weight loss was not significant between the RB+PS and RB group (p = 0.056). Changes in body fat corresponded to changes in body weight. Average decrease in total cholesterol was significantly higher in the RB+PS group than in the RB group (difference 36 ± 25 g/dL vs 7 ± 16 g/dL; p = 0.044). A similar pattern was observed for the decrease in low-density lipoprotein (LDL) cholesterol (difference 22.3 ± 25.2 g/dL vs 4.4 ± 18.9 g/dL; p = 0.062). Changes in systolic blood pressure, serum levels of leptin, and F2-isoprostanes were significant between baseline values and after 8 weeks on the diet in both groups (p < 0.05) but did not differ between the 2 groups.

Conclusions: A nutrient-balanced and energy-restricted diet supplemented with rice bran and plant sterols resulted in a significant decrease in total and LDL cholesterol in overweight and obese adults.
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http://dx.doi.org/10.1080/07315724.2013.869772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4465497PMC
February 2015

Separating bedtime rest from activity using waist or wrist-worn accelerometers in youth.

PLoS One 2014 11;9(4):e92512. Epub 2014 Apr 11.

Energy Balance Laboratory, Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America.

Recent interest in sedentary behavior and technological advances expanded use of watch-size accelerometers for continuous monitoring of physical activity (PA) over extended periods (e.g., 24 h/day for 1 week) in studies conducted in natural living environment. This approach necessitates the development of new methods separating bedtime rest and activity periods from the accelerometer recordings. The goal of this study was to develop a decision tree with acceptable accuracy for separating bedtime rest from activity in youth using accelerometer placed on waist or wrist. Minute-by-minute accelerometry data were collected from 81 youth (10-18 years old, 47 females) during a monitored 24-h stay in a whole-room indirect calorimeter equipped with a force platform covering the floor to detect movement. Receiver Operating Characteristic (ROC) curve analysis was used to determine the accelerometer cut points for rest and activity. To examine the classification differences, the accelerometer bedtime rest and activity classified by the algorithm in the development group (n = 41) were compared with actual bedtime rest and activity classification obtained from the room calorimeter-measured metabolic rate and movement data. The selected optimal bedtime rest cut points were 20 and 250 counts/min for the waist- and the wrist-worn accelerometer, respectively. The selected optimal activity cut points were 500 and 3,000 counts/min for waist and wrist-worn accelerometers, respectively. Bedtime rest and activity were correctly classified by the algorithm in the validation group (n = 40) by both waist- (sensitivity: 0.983, specificity: 0.946, area under ROC curve: 0. 872) and wrist-worn (0.999, 0.980 and 0.943) accelerometers. The decision tree classified bedtime rest correctly with higher accuracy than commonly used automated algorithm for both waist- and wrist-warn accelerometer (all p<0.001). We concluded that cut points developed and validated for waist- and wrist-worn uniaxial accelerometer have a good power for accurate separation of time spent in bedtime rest from activity in youth.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092512PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3984076PMC
December 2014

Doubly labeled water is a validated and verified reference standard in nutrition research.

J Nutr 2014 May 26;144(5):573-4. Epub 2014 Feb 26.

Energy Balance Laboratory, Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University, Nashville, TN.

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http://dx.doi.org/10.3945/jn.114.191361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3985818PMC
May 2014

Plasma selenium biomarkers in low income black and white americans from the southeastern United States.

PLoS One 2014 20;9(1):e84972. Epub 2014 Jan 20.

Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.

Biomarkers of selenium are necessary for assessing selenium status in humans, since soil variation hinders estimation of selenium intake from foods. In this study, we measured the concentration of plasma selenium, selenoprotein P (SEPP1), and glutathione peroxidase (GPX3) activity and their interindividual differences in 383 low-income blacks and whites selected from a stratified random sample of adults aged 40-79 years, who were participating in a long-term cohort study in the southeastern United States (US). We assessed the utility of these biomarkers to determine differences in selenium status and their association with demographic, socio-economic, dietary, and other indicators. Dietary selenium intake was assessed using a validated food frequency questionnaire designed for the cohort, matched with region-specific food selenium content, and compared with the US Recommended Dietary Allowances (RDA) set at 55 µg/day. We found that SEPP1, a sensitive biomarker of selenium nutritional status, was significantly lower among blacks than whites (mean 4.4 ± 1.1 vs. 4.7 ± 1.0 mg/L, p = 0.006), with blacks less than half as likely to have highest vs. lowest quartile SEPP1 concentration (Odds Ratio (OR) 0.4, 95% Confidence Interval (CI) 0.2-0.8). The trend in a similar direction was observed for plasma selenium among blacks and whites, (mean 115 ± 15.1 vs. 118 ± 17.7 µg/L, p = 0.08), while GPX3 activity did not differ between blacks and whites (136 ± 33.3 vs. 132 ± 33.5 U/L, p = 0.320). Levels of the three biomarkers were not correlated with estimated dietary selenium intake, except for SEPP1 among 10% of participants with the lowest selenium intake (≤ 57 µg/day). The findings suggest that SEPP1 may be an effective biomarker of selenium status and disease risk in adults and that low selenium status may disproportionately affect black and white cohort participants.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084972PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896351PMC
December 2014
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