Medicine and Health Sciences Commons^™

Impact Of Accelerometer Data Processing Decisions On The Sample Size, Wear Time And Physical Activity Level Of A Large Cohort Study, Sarah Kozey Keadle, Eric Shiroma, Patty Freedson, I-Min Lee

Patty S. Freedson

Background Accelerometers objectively assess physical activity (PA) and are currently used in several large-scale epidemiological studies, but there is no consensus for processing the data. This study compared the impact of wear-time assessment methods and using either vertical (V)-axis or vector magnitude (VM) cut-points on accelerometer output. Methods Participants (7,650 women, mean age 71.4 y) were mailed an accelerometer (ActiGraph GT3X+), instructed to wear it for 7 days, record dates and times the monitor was worn on a log, and return the monitor and log via mail. Data were processed using three wear-time methods (logs, Troiano or Choi algorithms) and …

Do Black-White Racial Disparities In Breastfeeding Persist In The Military Community?, Jennifer H. Lundquist, Zhun Xu, Wanda Barfield, Irma Elo

Dr. Jennifer H. Lundquist

Objective: We conduct a comparative analysis of breastfeeding behavior between military and civilian-affiliated mothers. Our focus is on African American mothers among whom breastfeeding rates are lowest. The military context may mitigate conditions associated with low breastfeeding prevalence by a) providing stable employment and educational opportunities to populations who face an otherwise poor labor market and b) providing universal healthcare that includes breastfeeding consultation. Methods: Using Pregnancy Risk Assessment Monitoring System (PRAMS) data for which we received special permission from each state to flag military affiliation, we analyze civilians and military affiliate in breastfeeding initiation using logistic regression and breastfeeding …

Racial Disparities In Us Infant Birth Outcomes: A Protective Effect Of Military Affiliation?, Jennifer H. Lundquist

Dr. Jennifer H. Lundquist

Research has been unable to determine why African Americans have higher infant mortality and preterm birth prevalence than whites, even taking into account measurable social and economic differences. This is, in part, due to the difficulty of adequately measuring the impacts of racial inequality and residential segregation. As an alternative approach, this paper comparatively examines infant outcomes among military-affiliated and civilian black and white women. The military setting provides higher-than-average economic equality and universal healthcare access. Although military-affiliated populations are usually left out of most major datasets, we construct a new variable that allows us to identify military affiliation using …

The Effects Of Aerobic Training And Age On Plasma Sicam-1, G. Many, N. Jenkins, Sarah Witkowski, J. Damsker, J. Hagberg

Sarah Witkowski

Chronic low-grade systemic infl ammation plays a role in the development of cardiovascular (CV) disease. Habitual endurance exercise training reduces the risk of CV disease in part through anti-infl ammatory mechanisms. The purpose of this study was to investigate the eff ects of age, endurance training status, and their interaction on pro-infl ammatory plasma cytokines involved in the pathogenesis of CV disease. Subjects were BMI-matched young (25 ± 3 years; endurance trained: n = 9, sedentary: n = 11) and older (62 ± 5 years; endurance-trained: n = 12, sedentary: n = 11) men. Plasma cytokine concentrations were determined by …

Identifying Important Breast Cancer Control Strategies In Asia, Latin America And The Middle East/North Africa, John Fp. Bridges, Benjamin O. Anderson, Antonio C. Buzaid, Abdul R. Jazieh, Louis W. Niessen, Barri M. Blauvelt, David R. Buchanan

David R Buchanan

Background: Breast cancer is the most frequent cause of cancer death in women worldwide, but global disparities in breast cancer control persist, due to a lack of a comprehensive breast cancer control strategy in many countries. Objectives: To identify and compare the need for breast cancer control strategies in Asia, Latin America and the Middle East/North Africa and to develop a common framework to guide the development of national breast cancer control strategies. Methods: Data were derived from open-ended, semi-structured interviews conducted in 2007 with 221 clinicians, policy makers, and patient advocates; stratified across Asia (n = 97), Latin America …

Calibrating A Novel Multi-Sensor Physical Activity Measurement System, D. John, S. Liu, J. Saski, C. Howe, J. Staudenmayer, R. Gao, Patty Freedson

Patty S. Freedson

Advancing the field of physical activity (PA) monitoring requires the development of innovative multi-sensor measurement systems that are feasible in the free-living environment. The use of novel analytical techniques to combine and process these multiple sensor signals is equally important. This paper, describes a novel multi-sensor ‘Integrated PA Measurement System’ (IMS), the lab-based methodology used to calibrate the IMS, techniques used to predict multiple variables from the sensor signals, and proposes design changes to improve the feasibility of deploying the IMS in the free-living environment. The IMS consists of hip and wrist acceleration sensors, two piezoelectric respiration sensors on the …

Metabolic And Anthropometric Parameters Contribute To Art-Mediated Cd4+ T Cell Recovery In Hiv-1-Infected Individuals: An Observational Study, Andrea S. Foulkes, Livio Azzoni, Cynthia Firnhaber, Xiangfan Yin, Nigel J. Crowther, Deborah Glencross, Denise Lawrie, Wendy Stevens, Emmanouil Papasavvas, Ian Sanne, Luis J. Montaner

Andrea S Foulkes

Background The degree of immune reconstitution achieved in response to suppressive ART is associated with baseline individual characteristics, such as pre-treatment CD4 count, levels of viral replication, cellular activation, choice of treatment regimen and gender. However, the combined effect of these variables on long-term CD4 recovery remains elusive, and no single variable predicts treatment response. We sought to determine if adiposity and molecules associated with lipid metabolism may affect the response to ART and the degree of subsequent immune reconstitution, and to assess their ability to predict CD4 recovery. Methods We studied a cohort of 69 (48 females and 21 …

Association Between Hiv Replication And Serum Leptin Levels: An Observational Study Of A Cohort Of Hiv-1-Infected South African Women, Livio Azzoni, Nigel J. Crowther, Cynthia Firnhaber, Andrea S. Foulkes

Andrea S Foulkes

Background - Advanced HIV infection can result in lipoatrophy and wasting, even in the absence of ongoing opportunistic infections, suggesting that HIV may directly affect adipose tissue amount and distribution. Methods - We assessed the relationship of fat (measured using anthropometry, DEXA, MRI scans) or markers related to glucose and lipid metabolism with viral load in a cross-sectional sample of 83 antiretroviral-naïve HIV-1-infected South African women. A multivariable linear model was fitted to log10VL to assess the combined effect of these variables. Results - In addition to higher T cell activation, women with viral load greater than the population median …

Elevated Atmospheric Carbon Dioxide Concentrations Amplify Alternaria Alternata Sporulation And Total Antigen Production, Julie Wolf, Nichole R. O’Neill, Christine A. Rogers, Michael L. Muilenberg, Lewis H. Ziska

Christine A. Rogers

Background

Although the effect of elevated carbon dioxide (CO2) concentration on pollen production has been established in some plant species, impacts on fungal sporulation and antigen production have not been elucidated.

Objective

Our purpose was to examine the effects of rising atmospheric CO2 concentrations on the quantity and quality of fungal spores produced on timothy (Phleum pratense) leaves.

Methods

Timothy plants were grown at four CO2 concentrations (300, 400, 500, and 600 μmol/mol). Leaves were used as growth substrate for Alternaria alternata and Cladosporium phlei. The spore abundance produced by both fungi, as well as the size (microscopy) and antigenic …

Seasonal And Sex Variation Of High-Sensitivity C-Reactive Protein In Healthy Adults: A Longitudinal Study, David E. Chiriboga, Yunsheng Ma, Wenjun Li, Edward J. Stanek, James R. Hébert, Philip A. Merriam, Eric S. Rawson, Ira S. Ockene

Edward J. Stanek

BACKGROUND

Cross-sectional studies have reported seasonal variation in high-sensitivity C-reactive protein (hsCRP). However, longitudinal data are lacking. METHODS

We collected data on diet, physical activity, psychosocial factors, physiology, and anthropometric measurements from 534 healthy adults (mean age 48 years, 48.5% women, 87% white) at quarterly intervals over a 1-year period between 1994 and 1998. Using sinusoidal regression models, we estimated peak-to-trough amplitude and phase of the peaks. RESULTS

At baseline, average hsCRP was 1.72 mg/L (men, 1.75 mg/L; women, 1.68 mg/L). Overall seasonal variation amplitude was 0.16 mg/L (95% CI 0.02 to 0.30) and was lower in men (0.10 mg/L, …

Predicting Low Dose Effects For Chemicals In High Through-Put Studies, Edward J. Stanek, E. J. Calabrese

Edward J. Stanek

High through-put studies commonly use automated systems with 96-well plates in which multiple chemicals are tested at multiple doses using log-2 dose increments after a suitable incubation period. There are typically multiple (ranging from five to eleven) doses on each chemical, and occasionally plate replications of the dose-response studies. The target endpoint for such studies is typically the LC50, but for some chemicals, there may be multiple doses below a benchmark dose where there is no apparent adverse response relative to control response. We show how an estimation approach can lead to clearly interpretable results about response in the low …

Defining Accelerometer Thresholds For Physical Activity In Girls Using Roc Analysis, Sofiya Alhassan, Thomas Robinson

Sofiya Alhassan

Background Receiver operating characteristic (ROC) analysis is a common method used in diagnostic and screening tests to define thresholds levels of a factor that discriminates between 2 levels of another factor. The purpose of this analysis was to use ROC analysis to determine the optimal accelerometer-measured physical activity (PA) thresholds for predicting selective cardiovascular disease (CVD) risk factors. Methods ROC was performed using data from Stanford Girls Health Enrichment Multisite Studies trial. PA was assessed for multiple days using accelerometers. CVD variables were overweight, elevated triglyceride, reduced HDL-C, hypertension, impaired fasting glucose, fasting insulin, and clustering of multiple CVD risk …

Smoking During Pregnancy And Risk Of Abnormal Glucose Tolerance: A Prospective Cohort Study, Penelope Susan Pekow, Amy E. Haskins, Elizabeth R. Bertone-Johnson, Elena Carbone, Renee T. Fortner, Lisa Chasen-Tabe

Penelope Susan Pekow

Background: Disturbances in glucose metabolism during pregnancy are associated with negative sequalae for both mother and infant. The association between smoking and abnormal glucose tolerance (AGT) remains controversial. Therefore, the aim of this study was to examine the relationship between smoking prior to and during pregnancy and risk of AGT. Methods: We utilized data from a prospective cohort of 1,006 Hispanic (predominantly Puerto Rican) prenatal care patients in Western Massachusetts. Women reported pre- and early pregnancy smoking at recruitment (mean = 15 weeks) and mid pregnancy smoking at a second interview (mean = 28 weeks). AGT was defined as > 135 …

Prediction-Based Classification For Longitudinal Biomarkers, Andrea S. Foulkes, Livio Azzoni, Xiaohong Li, Margaret A. Johnson, Colette Smith, Karam Mounzer, Luis J. Montaner

Andrea S Foulkes

Assessment of circulating CD4 count change over time in HIV-infected subjects on antiretroviral therapy (ART) is a central component of disease monitoring. The increasing number of HIV-infected subjects starting therapy and the limited capacity to support CD4 count testing within resource-limited settings have fueled interest in identifying correlates of CD4 count change such as total lymphocyte count, among others. The application of modeling techniques will be essential to this endeavor due to the typically nonlinear CD4 trajectory over time and the multiple input variables necessary for capturing CD4 variability. We propose a prediction-based classification approach that involves first stage modeling …

Quantification Of Hormesis In Anticancer-Agent Dose-Responses, Marc A. Nascarella, Edward J. Stanek, George R. Hoffmann, Edward J. Calabrese

Edward J. Stanek

Quantitative features of dose responses were analyzed for 2,189 candidate anticancer agents in 13 strains of yeast (Saccharomyces cerevisiae). The agents represent a diverse class of chemical compounds including mustards, other alkylating agents, and antimetabolites, inter alia. Previous analyses have shown that the responses below the toxic threshold were stimulatory and poorly predicted by a threshold dose-response model, while better explained by a hormetic dose-response model. We determined the quantitative features of the hormetic concentration-responses (n = 4,548) using previously published entry and evaluative criteria. The quantitative features that are described are: (1) the width of the concentration range showing …

Feasibility And Acceptability Of Continuous Glucose Monitoring And Accelerometer Technology In Exercising Individuals With Type 2 Diabetes, Nancy Allen, Cynthia Jacelon, Stuart Chipkin

Stuart R. Chipkin

Aims and Objectives—The aim of this study was to develop role model data for an intervention to motivate non-exercising individuals with type 2 diabetes mellitus to engage in regular physical activity. Toward that end, the study 1) described Continuous Glucose Monitoring System data and obtained role model CGMS graphs, 2) described a monitor to measure exercise amount and intensity and 3) explored participants’ experiences of the monitors and perceptions of the glucose monitoring data. Background—Physical activity is a cornerstone of diabetes treatment yet the majority of individuals with diabetes are inactive. Thus, increasing physical activity in these individuals demands innovative …

A Photovoice Participatory Evaluation Of A School Gardening Program Through The Eyes Of Fifth Graders, Catherine Sands, Krista Harper, Lee Ellen Reed, Maggie Shar

Krista M. Harper

In the springtime, fifth grade students at the Williamsburg Elementary School in rural Western Massachusetts ask to snack on sorrel and chives from the school garden, between planting potatoes and building a shade structure for their outdoor classroom. They are members of the first cohort of the curriculum-integrated program initiated by Fertile Ground, a grassroots organization in western Massachusetts. The children’s delight in the fresh greens they have grown marks a national phenomenon: the farm-to-school movement. With limited resources, parents, teachers, students, administrators, and community activists are developing inroads to better school food and food education, by constructing school teaching …

Tree-Based Methods For Discovery Of Association Between Flow Cytometry Data And Clinical Endpoints, M. Eliot, L. Azzoni, C. Firnhaber, W. Stevens, D. K. Glencross, I. Sanne, L. J. Montaner, Andrea S. Foulkes

Andrea S Foulkes

We demonstrate the application and comparative interpretations of three tree-based algorithms for the analysis of data arising from flow cytometry: classification and regression trees (CARTs), random forests (RFs), and logic regression (LR). Specifically, we consider the question of what best predicts CD4 T-cell recovery in HIV-1 infected persons starting antiretroviral therapy with CD4 count between 200 and 350 cell/μL. A comparison to a more standard contingency table analysis is provided. While contingency table analysis and RFs provide information on the importance of each potential predictor variable, CART and LR offer additional insight into the combinations of variables that together are …

Application Of Two Machine Learning Algorithms To Genetic Association Studies In The Presence Of Covariates, Bareng As Nonyane, Andrea S. Foulkes

Andrea S Foulkes

Background - Population-based investigations aimed at uncovering genotype-trait associations often involve high-dimensional genetic polymorphism data as well as information on multiple environmental and clinical parameters. Machine learning (ML) algorithms offer a straightforward analytic approach for selecting subsets of these inputs that are most predictive of a pre-defined trait. The performance of these algorithms, however, in the presence of covariates is not well characterized. Methods and Results - In this manuscript, we investigate two approaches: Random Forests (RFs) and Multivariate Adaptive Regression Splines (MARS). Through multiple simulation studies, the performance under several underlying models is evaluated. An application to a cohort …

Association Between Dietary Glycemic Index, Glycemic Load, And High-Sensitivity C-Reactive Protein, Jennifer A. Griffith, Yusheng Ma, Lisa Chasan-Taber, Barbara C. Olendzki, David E. Chiriboga, Edward J. Stanek, Philip A. Merriam, Ira S. Ockene

Edward J. Stanek

OBJECTIVE:

This study examined the relation between quality of dietary carbohydrate intake, as measured by glycemic index (GI) and glycemic load (GL), and serum high-sensitivity C-reactive protein (hs-CRP) levels. METHODS:

During a 1-y observational study, data were collected at baseline and at each quarter thereafter. GI and GL were calculated from multiple 24-h dietary recalls (24HRs), 3 randomly selected 24HRs at every quarter, with up to 15 24HRs per participant. The hs-CRP was measured in blood samples collected at baseline and each of the four quarterly measurement points. Multivariable linear mixed models were used to examine the cross-sectional and longitudinal …

Effect Of Diet And Exercise On Body Composition, Energy Intake And Leptin Levels In Overweight Women And Men, Stella L. Volpe, Hati Kobusingye, Smita Bailfur, Edward J. Stanek

Edward J. Stanek

OBJECTIVE: To investigate the effect of diet alone (D), exercise alone (E), and a combination of diet and exercise (DE) on body weight, body composition, energy intake, blood pressure, serum lipid and leptin levels, and fitness levels in mildly obese sedentary women and men. DESIGN: The three interventions were compared in a randomized longitudinal study design. The exercise programs were supervised for six months, after which participants in E and DE were provided with exercise equipment to take home. SUBJECTS: 90 adult overweight women and men (age: 44.2 +/- 7.2 years; BMI = 30.5 +/- 2.7 kg/m(2)). MEASUREMENTS: Body weight, …

Should Adjustment For Covariates Be Used In Prevalence Estimations?, Wenjun Li, Edward J. Stanek, Elizabeth R. Bertone-Johnson

Edward J. Stanek

Background

Adjustment for covariates (also called auxiliary variables in survey sampling literature) is commonly applied in health surveys to reduce the variances of the prevalence estimators. In theory, adjusted prevalence estimators are more accurate when variance components are known. In practice, variance components needed to achieve the adjustment are unknown and their sample estimators are used instead. The uncertainty introduced by estimating variance components may overshadow the reduction in the variance of the prevalence estimators due to adjustment. We present empirical guidelines indicating when adjusted prevalence estimators should be considered, using gender adjusted and unadjusted smoking prevalence as an illustration. …

Changes In Muscle And Joint Coordination In Learning To Direct Forces, Christopher Hasson, Graham Caldwell, Richard Van Emmerik

Richard E.A. van Emmerik

While it has been suggested that biarticular muscles have a specialized role in directing external reaction forces, it is unclear how humans learn to coordinate mono- and bi-articular muscles to perform force-directing tasks. Subjects were asked to direct pedal forces in a specified target direction during one-legged cycling. We expected that with practice, performance improvement would be associated with specific changes in joint torque patterns and mono- and bi-articular muscular coordination. Nine male subjects practiced pedaling an ergometer with only their left leg, and were instructed to always direct their applied pedal force perpendicular to the crank arm (target direction) …

Monitoring Microbial Populations On Wide-Body Commercial Passenger Aircraft, Taylor L. Mckernan, K M. Wallingford, M J. Hein, H A. Burge, Christine A. Rogers, R Herrick

Christine A. Rogers

Although exposure to bacteria has been assessed in cabin air previously, minimal numbers of samples have been collected in-flight. The purpose of this research was to comprehensively characterize bacterial concentrations in the aircraft cabin. Twelve randomly selected flights were sampled on Boeing-767 aircraft, each with a flight duration between 4.5 and 6.5 h. N-6 impactors were used to collect sequential, triplicate air samples in the front and rear of coach class during six sampling intervals throughout each flight: boarding, mid-climb, early cruise, mid-cruise, late cruise and deplaning. Comparison air samples were also collected inside and outside the airport terminals at …

A Likelihood-Based Approach To Mixed Modeling With Ambiguity In Cluster Identifiers, Andrea S. Foulkes, Recai Yucel, Xiaohong Li

Andrea S Foulkes

This manuscript describes a novel, linear mixed-effects model–fitting technique for the setting in which correlated data indicators are not completely observed. Mixed modeling is a useful analytical tool for characterizing genotype–phenotype associations among multiple potentially informative genetic loci. This approach involves grouping individuals into genetic clusters, where individuals in the same cluster have similar or identical multilocus genotypes. In haplotype-based investigations of unrelated individuals, corresponding cluster assignments are unobservable since the alignment of alleles within chromosomal copies is not generally observed. We derive an expectation conditional maximization approach to estimation in the mixed modeling setting, where cluster assignments are ambiguous. …

Outcomes Of Care By Hospitalists, General Internists, And Family Physicians, Peter K. Lindenauer, Michael B. Rothberg, Penelope Susan Pekow, Christopher Kenwood, Evan M. Benjamin, Andrew D. Auerbach

Penelope Susan Pekow

Background: The hospitalist model is rapidly altering the landscape for inpatient care in the United States, yet evidence about the clinical and economic outcomes of care by hospitalists is derived from a small number of single-hospital studies examining the practices of a few physicians.

Methods: We conducted a retrospective cohort study of 76,926 patients 18 years of age or older who were hospitalized between September 2002 and June 2005 for pneumonia, heart failure, chest pain, ischemic stroke, urinary tract infection, acute exacerbation of chronic obstructive pulmonary disease, or acute myocardial infarction at 45 hospitals throughout the United States. We used …

Changes In Physical Activity From Walking To School, John Sirard, Sofiya Alhassan, Tirzah Spencer, Thomas Robinson

Sofiya Alhassan

No abstract provided.

Interaction Of The Onset Of Spring And Elevated Atmospheric Co2 On Ragweed (Ambrosia Artemisiifolia L.) Pollen Production, Christine A. Rogers, P Wayne, E Macklin, M L. Muilenberg, C W. Wagner, P R. Epstein, F A. Bazzaz

Christine A. Rogers

Increasing atmospheric carbon dioxide is responsible for climate changes that are having widespread effects on biological systems. One of the clearest changes is earlier onset of spring and lengthening of the growing season. We designed the present study to examine the interactive effects of timing of dormancy release of seeds with low and high atmospheric CO2 on biomass, reproduction, and phenology in ragweed plants (Ambrosia artemisiifolia L.), which produce highly allergenic pollen. We released ragweed seeds from dormancy at three 15-day intervals and grew plants in climate-controlled glasshouses at either ambient or 700-ppm CO2 concentrations, placing open-top bags over inflorescences …

How Exposure To Environmental Tobacco Smoke, Outdoor Air Pollutants, And Increased Pollen Burdens Influence The Incidence Of Asthma, M I. Gilmour, M S. Jaakola, S J. London, A Nel, Christine A. Rogers

Christine A. Rogers

Asthma is a multifactorial airway disease that arises from a relatively common genetic background interphased with exposures to allergens and airborne irritants. The rapid rise in asthma over the past three decades in Western societies has been attributed to numerous diverse factors, including increased awareness of the disease, altered lifestyle and activity patterns, and ill-defined changes in environmental exposures. It is well accepted that persons with asthma are more sensitive than persons without asthma to air pollutants such as cigarette smoke, traffic emissions, and photochemical smog components. It has also been demonstrated that exposure to a mix of allergens and …

Perioperative Beta-Blocker Therapy And Mortality After Major Noncardiac Surgery, Peter K. Lindenauer, Penelope Susan Pekow, Kaijun Wang, Dheeresh K. Mamidi, Benjamin Gutierrez, Evan M. Benjamin

Penelope Susan Pekow

Background: Despite limited evidence from randomized trials, perioperative treatment with beta-blockers is now widely advocated. We assessed the use of perioperative beta-blockers and their association with in-hospital mortality in routine clinical practice.

Methods: We conducted a retrospective cohort study of patients 18 years of age or older who underwent major noncardiac surgery in 2000 and 2001 at 329 hospitals throughout the United States. We used propensity-score matching to adjust for differences between patients who received perioperative beta-blockers and those who did not receive such therapy and compared in-hospital mortality using multivariable logistic modeling.

Results: Of 782,969 patients, 663,635 (85 percent) …