Medicine and Health Sciences Commons^™

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 …

Aging, Spacial Cues, And Single-Versus Dual-Task Performance In Competing Speech Perception, Karen S. Helfer, Jamie Chevalier, Richard L. Freyman

Karen S Helfer

Older individuals often report difficulty coping in situations with multiple conversations in which they at times need to "tune out" the background speech and at other times seek to monitor competing messages. The present study was designed to simulate this type of interaction by examining the cost of requiring listeners to perform a secondary task in conjunction with understanding a target talker in the presence of competing speech. The ability of younger and older adults to understand a target utterance was measured with and without requiring the listener to also determine how many masking voices were presented time-reversed. Also of …

A Cross-Sectional Comparison Of The Effects Of Phonotactic Probability And Neighborhood Density On Word Learning By Preschool Children, Jill R. Hoover, Holly L. Storkel, Tiffany Hogan

Jill R. Hoover

Two experiments examined the effects of phonotactic probability and neighborhood density on word learning by 3-, 4-, and 5-year-old children. Nonwords orthogonally varying in probability and density were taught with learning and retention measured via picture naming. Experiment 1 used a within-story probability/across-story density exposure context. Experiment 2 used an across-story probability/within-story density exposure context. Results showed that probability and density interacted to create optimal learning conditions. Specifically, rare/sparse sound sequences appeared to facilitate triggering of word learning. In contrast, the optimal convergence for lexical configuration and engagement was dependent on exposure context. In particular, common sound sequences and dense …

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 …

An Online Calculator To Compute Phonotactic Probability And Neighborhood Density Based On Child Corpora Of Spoken American English, Holly L. Storkel, Jill R. Hoover

Jill R. Hoover

An online calculator was developed (www.bncdnet.ku.edu/cml/info_ccc.vi) to compute phonotactic probability--the likelihood of occurrence of a sound sequence--and neighborhood density--the number of phonologically similar words--on the basis of child corpora of American English (Kolson, 1960; Moe, Hopkins, & Rush, 1982) and to compare its results to those of an adult calculator. Phonotactic probability and neighborhood density were computed for a set of 380 nouns (Fenson et al., 1993) using both the child and adult corpora. The child and adult raw values were significantly correlated. However, significant differences were detected. Specifically, child phonotactic probability was higher than adult phonotactic probability, especially for …

Differentiating The Effects Of Phonotactic Probability And Neighborhood Density On Vocabulary Comprehension And Production: A Comparison Of Preschool Children With Versus Without Phonological Delays, Holly L. Storkel, Junko Maekawa, Jill R. Hoover

Jill R. Hoover

The purpose of this study was to differentiate the effect of phonotactic probability from that of neighborhood density on a vocabulary probe administered to preschool children with or without a phonological delay.

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 …