Air Pollution Exposure Assessment for Epidemiologic Studies of Pregnant Women and Children: Lessons Learned from the Centers for Children’s Environmental Health and Disease Prevention Research

The National Children’s Study is considering a wide spectrum of airborne pollutants that are hypothesized to potentially influence pregnancy outcomes, neurodevelopment, asthma, atopy, immune development, obesity, and pubertal development. In this article we summarize six applicable exposure assessment lessons learned from the Centers for Children’s Environmental Health and Disease Prevention Research that may enhance the National Children’s Study: a) Selecting individual study subjects with a wide range of pollution exposure profiles maximizes spatial-scale exposure contrasts for key pollutants of study interest. b) In studies with large sample sizes, long duration, and diverse outcomes and exposures, exposure assessment efforts should rely on modeling to provide estimates for the entire cohort, supported by subject-derived questionnaire data. c) Assessment of some exposures of interest requires individual measurements of exposures using snapshots of personal and microenvironmental exposures over short periods and/or in selected microenvironments. d) Understanding issues of spatial–temporal correlations of air pollutants, the surrogacy of specific pollutants for components of the complex mixture, and the exposure misclassification inherent in exposure estimates is critical in analysis and interpretation. e) “Usual” temporal, spatial, and physical patterns of activity can be used as modifiers of the exposure/outcome relationships. f) Biomarkers of exposure are useful for evaluation of specific exposures that have multiple routes of exposure. If these lessons are applied, the National Children’s Study offers a unique opportunity to assess the adverse effects of air pollution on interrelated health outcomes during the critical early life period

Community Woodstove Changeout and Impact on Ambient Concentrations of Polycyclic Aromatic Hydrocarbons and Phenolics

A large woodstove changeout program was carried out in Libby, Montana, with the goal of reducing ambient levels of PM2.5. This provided researchers the opportunity to measure ambient concentrations of phenolic and polycyclic aromatic hydrocarbons (PAHs) before, during, and after the changeout of nearly 1200 stoves to evaluate the effectiveness of the intervention. Starting in the heating season of 2004/2005 and ending in the heating season of 2007/2008, 19 compounds were measured every three days using a high-volume polyurethane foam (PUF) sampler followed by gas chromatography and mass spectrometry analysis. Some of the organic species with the highest measured concentrations were also signature chemical markers for wood combustion. When comparing the measurements conducted during the heating season of 2004/2005 (prechangeout) to those of the heating season of 2007/2008 (postchangeout), there was a 64% average reduction in the measured concentrations of phenolics and PAHs, while the PM2.5 mass dropped by only 20% over the same time period. The results of this four year sampling program suggest that the Libby woodstove changeout program was successful in reducing overall concentrations of the measured phenolic and PAH compounds

Residential Indoor PM\u3csub\u3e2.5\u3c/sub\u3e in Wood Stove Homes: Follow-up of the Libby Changeout Program

In 2005 through 2008 a small rural mountain valley community engaged in a wood stove changeout program to address concerns of poor ambient air quality. During this program we assessed changes to indoor air quality before and after the introduction of a new, lower emission wood stove. We previously reported a greater than 70% reduction in indoor PM2.5 concentrations in homes following the installation of a new EPA-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM2.5 concentrations (mean (sd) = 45.0 (33.0) μg/m3) to multiple post-changeout measures of PM2.5 concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was −18.5 μg/m3 (−31.9, −5.2), adjusting for ambient PM2.5, ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM2.5 following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new wood stove

Evolution of Esophagectomy for Cancer Over 30 Years:Changes in Presentation, Management and Outcomes

Background: Esophageal cancer has seen a considerable change in management and outcomes over the last 30 years. Historically, the overall prognosis has been regarded as poor; however, the use of multimodal treatment and the integration of enhanced recovery pathways have improved short- and long-term outcomes. Objective: The aim of this study was to evaluate the changing trends in presentation, management, and outcomes for patients undergoing surgical treatment for esophageal cancer over 30 years from a single-center, high-volume unit in the UK. Patients and Methods: Data from consecutive patients undergoing esophagectomy for cancer (adenocarcinoma or squamous cell carcinoma) between 1989 and 2018 from a single-center, high-volume unit were reviewed. Presentation method, management strategies, and outcomes were evaluated. Patients were grouped into successive 5-year cohorts for comparison and evaluation of changing trends. Results: Between 1989 and 2018, 1486 patients underwent esophagectomy for cancer. Median age was 65 years (interquartile range [IQR] 59–71) and 1105 (75%) patients were male. Adenocarcinoma constituted 1105 (75%) patients, and overall median survival was 29 months (IQR 15–68). Patient presentation changed, with epigastric discomfort now the most common presentation (70%). An improvement in mortality from 5 to 2% (p &lt; 0.001) was seen over the time period, and overall survival improved from 22 to 56 months (p &lt; 0.001); however, morbidity increased from 54 to 68% (p = 0.004). Conclusions: Long-term outcomes have significantly improved over the 30-year study period. In addition, mortality and length of stay have improved despite an increase in complications. The reasons for this are multifactorial and include the use of perioperative chemo(radio)therapy, the introduction of an enhanced recovery pathway, and improved patient selection.</p

Impact of Smoking Status on Perioperative Morbidity, Mortality, and Long-Term Survival Following Transthoracic Esophagectomy for Esophageal Cancer

Introduction: Esophagectomy is a key component in the curative treatment of esophageal cancer. Little is understood about the impact of smoking status on perioperative morbidity and mortality and the long-term outcome of patients following esophagectomy. Objective: This study aimed to evaluate morbidity and mortality according to smoking status in patients undergoing esophagectomy for esophageal cancer. Methods: Consecutive patients undergoing two-stage transthoracic esophagectomy (TTE) for esophageal cancers (adenocarcinoma or squamous cell carcinoma) between January 1997 and December 2016 at the Northern Oesophagogastric Unit were included from a prospectively maintained database. The main explanatory variable was smoking status, defined as current smoker, ex-smoker, and non-smoker. The primary outcome was overall survival (OS), while secondary outcomes included perioperative complications (overall, anastomotic leaks, and pulmonary complications) and survival (cancer-specific survival [CSS], recurrence-free survival [RFS]). Results: During the study period, 1168 patients underwent esophagectomy for cancer. Of these, 24% (n = 282) were current smokers and only 30% (n = 356) had never smoked. The median OS of current smokers was significantly shorter than ex-smokers and non-smokers (median 36 vs. 42 vs. 48 months; p = 0.015). However, on adjusted analysis, there was no significant difference in long-term OS between smoking status in the entire cohort. The overall complication rates were significantly higher with current smokers compared with ex-smokers or non-smokers (73% vs. 66% vs. 62%; p = 0.018), and there were no significant differences in anastomotic leaks and pulmonary complications between the groups. On subgroup analysis by receipt of neoadjuvant therapy and tumor histology, smoking status did not impact long-term survival in adjusted multivariable analyses. Conclusion: Although smoking is associated with higher rates of short-term perioperative morbidity, it does not affect long-term OS, CSS, and RFS following esophagectomy for esophageal cancer. Therefore, implementation of perioperative pathways to optimize patients may help reduce the risk of complications.</p

Case-Crossover Analysis of Air Pollution Health Effects: A Systematic Review of Methodology and Application

10 pages, 2 figures, 5 tables.-- PMID: 20356818 [PubMed].--PMCID: PMC2920078.-- Printed version published Aug 2010.BACKGROUND: Case-crossover is one of the most used designs for analyzing the health-related effects of air pollution. Nevertheless, no one has reviewed its application and methodology in this context.OBJECTIVE: We conducted a systematic review of case-crossover (CCO) designs used to study the relationship between air pollution and morbidity and mortality, from the standpoint of methodology and application.DATA SOURCES AND EXTRACTION: A search was made of the MEDLINE and EMBASE databases.Reports were classified as methodologic or applied. From the latter, the following information was extracted: author, study location, year, type of population (general or patients), dependent variable(s), independent variable(s), type of CCO design, and whether effect modification was analyzed for variables at the individual level.DATA SYNTHESIS: The review covered 105 reports that fulfilled the inclusion criteria. Of these, 24 addressed methodological aspects, and the remainder involved the design's application. In the methodological reports, the designs that yielded the best results in simulation were symmetric bidirectional CCO and time-stratified CCO. Furthermore, we observed an increase across time in the use of certain CCO designs, mainly symmetric bidirectional and time-stratified CCO. The dependent variables most frequently analyzed were those relating to hospital morbidity; the pollutants most often studied were those linked to particulate matter. Among the CCO-application reports, 13.6% studied effect modification for variables at the individual level.CONCLUSIONS: The use of CCO designs has undergone considerable growth; the most widely used designs were those that yielded better results in simulation studies: symmetric bidirectional and time-stratified CCO. However, the advantages of CCO as a method of analysis of variables at the individual level are put to little use.This study was supported by grant CIBERESP-MET-007 from the Consortium for Biomedical Research in Epidemiology and Public Health [CIBER en Epidemiología y Salud Pública (CIBERESP)], Spain. A.T. was funded by project PI080354 [Fondo de Investigaciones Sanitarias (FIS)] of the Subdirectorate-General for Research Evaluation and Development and by project 200930I008 [Consejo Superior de Investigaciones Científicas (CSIC)].This study was supported by grant CIBERESP-MET-007 from the Consortium for Biomedical Research in Epidemiology and Public Health [CIBER en Epidemiología y Salud Pública (CIBERESP)], Spain. A.T. was funded by project PI080354 [Fondo de Investigaciones Sanitarias (FIS)] of the Subdirectorate-General for Research Evaluation and Development and by project 200930I008 [Consejo Superior de Investigaciones Científicas (CSIC)].Peer reviewe

Effects of epitaxial strain on the growth mechanism of YBa2Cu3O7-x thin films in [YBa2Cu3O7-x / PrBa2Cu3O7-x] superlattices

We report on the growth mechanism of YBa2Cu3O7-x (YBCO). Our study is based on the analysis of ultrathin, YBa2Cu3O7-x layers in c-axis oriented YBa2Cu3O7-x / PrBa2Cu3O7-x superlattices. We have found that the release of epitaxial strain in very thin YBCO layers triggers a change in the dimensionality of the growth mode. Ultrathin, epitaxially strained, YBCO layers with thickness below 3 unit cells grow in a block by block two dimensional mode coherent over large lateral distances. Meanwhile, when thickness increases, and the strain relaxes, layer growth turns into three dimensional, resulting in rougher layers and interfaces.Comment: 10 pages + 9 figures, accepted in Phys. Rev.