Accounting for Biases in Survey-Based Estimates of Population Attributable Fractions

Background: This paper discusses best practices for estimating fractions of mortality attributable to health exposures in survey data that are biased by observed confounders and unobserved endogenous selection. Extant research has shown that estimates of population attributable fractions (PAF) from the formula using the proportion of deceased that is exposed (PAFpd) can attend to confounders, whereas the formula using the proportion of the entire sample exposed (PAFpe) is biased by confounders. Research has not explored how PAFpd and PAFpe equations perform when both confounding and selection bias are present. Methods: We review equations for calculating PAF based on either the proportion of deceased (pd) or the proportion of the entire sample (pe) that receives the exposure. We explore how estimates from each equation are affected by confounding bias and selection bias using hypothetical data and real-world survey data from the National Health Interview Survey–Linked Mortality Files, 1987–2011. We examine the association between cigarette smoking and all-cause mortality risk in the US adult population as an example. Results: We show that both PAFpd and PAFpe calculate the true PAF in the presence of confounding bias if one uses the “weighted-sum” approach. We further show that both the PAFpd and PAFpe calculate biased PAFs in the presence of collider bias, but that the bias is more severe in the PAFpd formula. Conclusion: We recommend that researchers use the PAFpe formula with the weighted-sum approach when estimates of the exposure-outcome relationship are biased by endogenous selection

A cross-sectional comparison of quality of life between physically active and underactive older men with prostate cancer

Men with prostate cancer experience many side effects and symptoms that may be improved by a physically active lifestyle. It was hypothesized that older men with prostate cancer who were physically active would report significantly higher levels of quality of life (QOL) as assessed by the WHOQOL-BREF and the WHOQOL-OLD. Of the 348 prostate cancer survivors who were invited to participate in the present postal survey, 137 men returned the questionnaires. Those who were physically active had significantly lower prostate specific antigen (PSA) scores and higher social participation than those insufficiently active. These findings offer some support for the benefits of physical activity (PA) within the prostate cancer population in managing the adverse side effects of their treatments on aspects of their QOL. Future research should more closely examine what types of PA best promote improvements in varying aspects of QOL and psychological well-being for prostate cancer survivors

The anti-cancer effect of retinoic acid signaling in CRC occurs via decreased growth of ALDH+ colon cancer stem cells and increased differentiation of stem cells

Background: Tumorigenesis is driven by stem cell (SC) overpopulation. BecauseALDH is both a marker for SCs in many tissues and a key enzyme in retinoid acid (RA)signaling, we studied RA signaling in normal and malignant colonic SCs.Hypothesis: RA signaling regulates growth and differentiation of ALDH+ colonicSCs dysregulation of RA signaling contributes to SC overpopulation and colorectalcancer (CRC) development.Methods: We analyzed normal and malignant colonic tissues and CRC cell linesto see if retinoid receptors (RXR &RAR) are exclusively expressed in ALDH+ SCs,and if RA signaling changes during CRC development. We determined whether RAsignaling regulates cancer SC (CSC) proliferation, differentiation, sphere formation,and population size.Results: RXR &RAR were expressed in ALDH+ colonic SCs, but not in MCM2+proliferative cells. Western blotting/immunostaining of CRCs revealed that RAsignaling components become overexpressed in parallel with ALDH overexpression,which coincides with the known overpopulation of ALDH+ SCs that occurs during,and drives, CRC development. Treatment of SCs with all-trans retinoic acid (ATRA)decreased proliferation, sphere formation and ALDH+ SC population size, and induceddifferentiation along the neuroendocrine cell (NEC) lineage.Conclusions: Retinoid signaling, by regulating ALDH+ colonic CSCs, decreases SCproliferation, sphere formation, and population size, and increases SC differentiation toNECs. Dysregulation of RA signaling in colonic SCs likely contributes to overpopulationof ALDH+ SCs and CRC growth.Implications: That retinoid receptors RXR and RAR are selectively expressed inALDH+ SCs indicates RA signaling mainly occurs via ALDH+ SCs, which provides amechanism to selectively target CSCs. © 2018 Impact Journals LLC. All rights reserved

Fitting Age-Period-Cohort Models Using the Intrinsic Estimator: Assumptions and Misapplications

We thank Demography’s editorial office for the opportunity to respond to te Grotenhuis et al.’s commentary regarding the methods used and the results presented in our earlier paper (Masters et al. 2014). In this response, we briefly reply to three general themes raised in the commentary: (1) the presentation and discussion of APC results, (2) the fitting of full APC models to data for which a simpler model holds, and (3) the variation in the estimated age, period, and cohort coefficients produced by the intrinsic estimator (IE) (i.e., the “non-uniqueness property” of the IE, as referred to by Pelzer et al. (2015))

Galaxy Zoo: Bar Lengths in Nearby Disk Galaxies

We present an analysis of bar length measurements of 3150 local galaxies in a volume limited sample of low redshift (z < 0.06) disk galaxies. Barred galaxies were initially selected from the Galaxy Zoo 2 project, and the lengths and widths of the bars were manually drawn by members of the Galaxy Zoo community using a Google Maps interface. Bars were measured independently by different observers, multiple times per galaxy (>=3), and we find that observers were able to reproduce their own bar lengths to 3% and each others' to better than 20%. We find a "color bimodality" in our disk galaxy population with bar length, i.e., longer bars inhabit redder disk galaxies and the bars themselves are redder, and that the bluest galaxies host the smallest galactic bars (< 5 kpc/h). We also find that bar and disk colors are clearly correlated, and for galaxies with small bars, the disk is, on average, redder than the bar colors, while for longer bars the bar then itself is redder, on average, than the disk. We further find that galaxies with a prominent bulge are more likely to host longer bars than those without bulges. We categorise our galaxy populations by how the bar and/or ring are connected to the spiral arms. We find that galaxies whose bars are directly connected to the spiral arms are preferentially bluer and that these galaxies host typically shorter bars. Within the scatter, we find that stronger bars are found in galaxies which host a ring (and only a ring). The bar length and width measurements used herein are made publicly available for others to use (http://data.galaxyzoo.org).Comment: 15 pages, 16 figures, accepted in MNRA

Profiling the iron, copper and zinc content in primary neuron and astrocyte cultures by rapid online quantitative size exclusion chromatography-inductively coupled plasma-mass spectrometry

Metals often determine the chemical reactivity of the proteins to which they are bound. Each cell in the body tightly maintains a unique metalloproteomic profile, mostly dependent on function. This paper describes an analytical online flow injection quantitative size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) method, which was applied to profiling the metal-binding proteins found in primary cultures of neurons and astrocytes. This method can be conducted using similar amounts of sample to those used for Western blotting (20-150 μg protein), and has a turnaround time of <15 minutes. Metalloprotein standards for Fe (as ferritin), Cu and Zn (as superoxide dismutase-1) were used to construct multi-point calibration curves for online quantification of metalloproteins by SEC-ICP-MS. Homogenates of primary neuron and astrocyte cultures were analysed by SEC-ICP-MS. Online quantification by external calibration with metalloprotein standards determined the mass of metal eluting from the column relative to time (as pg s-1). Total on-column Fe, Cu and Zn detection limits ranged from 0.825 ± 0.005 ng to 13.6 ± 0.7 pg. Neurons and astrocytes exhibited distinct metalloprotein profiles, featuring both ubiquitous and unique metalloprotein species. Separation and detection by SEC-ICP-MS allows appraisal of these metalloproteins in their native state, and online quantification was achieved using this relatively simple external calibration process. © 2013 The Royal Society of Chemistry

The contribution of coping related variables and cardiac vagal activity on the performance of a dart throwing task under pressure.

The aims of this study were 1) to assess the predictive role of coping related variables (CRV) on cardiac vagal activity (derived from heart rate variability), and 2) to investigate the influence of CRV (including cardiac vagal activity) on a dart throwing task under low pressure (LP) and high pressure (HP) conditions. Participants (n=51) completed trait CRV questionnaires: Decision Specific Reinvestment Scale, Movement Specific Reinvestment Scale and Trait Emotional Intelligence Questionnaire. They competed in a dart throwing task under LP and HP conditions. Cardiac vagal activity measurements were taken at resting, task and during recovery for 5min. Self-reported ratings of stress were recorded at three time points via a visual analogue scale. Upon completion of the task, self-report measures of motivation, stress appraisal, attention, perceived pressure and dart throwing experience were completed. Results indicated that resting cardiac vagal activity had no predictors. Task cardiac vagal activity was predicted by resting cardiac vagal activity in both pressure conditions with the addition of a trait CRV in HP. Post task cardiac vagal activity was predicted by resting cardiac vagal activity in both conditions with the addition of a trait CRV in HP. Cardiac vagal reactivity (difference from resting to task) was predicted by a trait CRV in HP conditions. Cardiac vagal recovery (difference from task to post task) was predicted by a state CRV only in LP. Dart throwing task performance was predicted by a combination of both CRV and cardiac vagal activity. The current research suggests that coping related variables and cardiac vagal activity influence dart throwing task performance differently dependent on pressure condition

Creating Livable Neighborhoods in Old Hill and Six Corners, Springfield, Massachusetts

This report documents the work of the Graduate Urban Design Studio in Springfield’s Old Hill and Six Corners neighborhoods with 12,000 inhabitants. Both neighborhoods are challenged by a very low average household income, housing foreclosures, lot vacancies, lack of substantial home ownership, high traffic volumes and poor quality of open space. The primary goal of the project was to develop a vision to renew Old Hill and Six Corners to improve livability for their residents and create new opportunities for housing, recreation, working and commercial activities. Crucial keys to attaining this goal will be creating a stronger sense of place throughout the neighborhood and improved connectivity to the existing public open spaces like the Watershops Pond and the proposed recreational trail “Arc of Recreation”. Four physical design objectives were explored: Creating a vision for livable streets - a more livable streetscape improves walkability, urban ecology, commercial activities and provides an enriching sensual experience. Creating a better physical environment for commercial and business activities – attractive streets create a new identity and support existing businesses. Creating and improving a pedestrian and bicycle oriented circulation and coherent public open space system. Exploring new housing opportunities - new sites for housing integrate the student population in the neighborhoods. We are proud that our proposals were recognized after a tornado hit Springfield in June 2011. REBUILDSPRINGFIELD targeted the tornado-impacted neighborhoods in a collaborative effort with engaged citizens and community groups. Our plans created a valuable planning and design framework to rebuild the City