Person: Li, Wenyuan
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Li
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Wenyuan
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Li, Wenyuan
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Publication Residential proximity to major roads, exposure to fine particulate matter and aortic calcium: the Framingham Heart Study, a cohort study(BMJ Publishing Group, 2017) Dorans, Kirsten; Wilker, Elissa; Li, Wenyuan; Berlik, Mary; Ljungman, Petter L; Schwartz, Joel; Coull, Brent; Kloog, Itai; Koutrakis, Petros; D'Agostino, Ralph B; Massaro, Joseph M; Hoffmann, Udo; O'Donnell, Christopher; Mittleman, MurrayObjectives: Traffic and ambient air pollution exposure are positively associated with cardiovascular disease, potentially through atherosclerosis promotion. Few studies have assessed associations of these exposures with thoracic aortic calcium Agatston score (TAC) or abdominal aortic calcium Agatston score (AAC), systemic atherosclerosis correlates. We assessed whether living close to a major road and residential fine particulate matter (PM2.5) exposure were associated with TAC and AAC in a Northeastern US cohort. Design: Cohort study. Setting: Framingham Offspring and Third Generation participants residing in the Northeastern USA. Participants and outcome measures Among 3506 participants, mean age was 55.8 years; 50% female. TAC was measured from 2002 to 2005 and AAC up to two times (2002–2005; 2008–2011) among participants from the Framingham Offspring or Third Generation cohorts. We first assessed associations with detectable TAC (logistic regression) and AAC (generalised estimating equation regression, logit link). As aortic calcium scores were right skewed, we used linear regression models and mixed-effects models to assess associations with natural log-transformed TAC and AAC, respectively, among participants with detectable aortic calcium. We also assessed associations with AAC progression. Models were adjusted for demographic variables, socioeconomic position indicators and time. Results: There were no consistent associations of major roadway proximity or PM2.5 with the presence or extent of TAC or AAC, or with AAC progression. Some estimates were in the opposite direction than expected. Conclusions: In this cohort from a region with relatively low levels of and variation in PM2.5, there were no strong associations of proximity to a major road or PM2.5 with the presence or extent of aortic calcification, or with AAC progression.Publication Short‐Term Exposure to Air Pollution and Biomarkers of Oxidative Stress: The Framingham Heart Study(John Wiley and Sons Inc., 2016) Li, Wenyuan; Wilker, Elissa; Dorans, Kirsten; Berlik, Mary; Schwartz, Joel; Coull, Brent; Koutrakis, Petros; Gold, Diane; Keaney, John F.; Lin, Honghuang; Vasan, Ramachandran S.; Benjamin, Emelia J.; Mittleman, MurrayBackground: Short‐term exposure to elevated air pollution has been associated with higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution hypothesized as an important underlying mechanism. However, few community‐based studies have assessed this association. Methods and Results: Two thousand thirty‐five Framingham Offspring Cohort participants living within 50 km of the Harvard Boston Supersite who were not current smokers were included. We assessed circulating biomarkers of oxidative stress including blood myeloperoxidase at the seventh examination (1998–2001) and urinary creatinine‐indexed 8‐epi‐prostaglandin F2α (8‐epi‐PGF 2α) at the seventh and eighth (2005–2008) examinations. We measured fine particulate matter (PM 2.5), black carbon, sulfate, nitrogen oxides, and ozone at the Supersite and calculated 1‐, 2‐, 3‐, 5‐, and 7‐day moving averages of each pollutant. Measured myeloperoxidase and 8‐epi‐PGF 2α were loge transformed. We used linear regression models and linear mixed‐effects models with random intercepts for myeloperoxidase and indexed 8‐epi‐PGF 2α, respectively. Models were adjusted for demographic variables, individual‐ and area‐level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of PM 2.5 and black carbon with myeloperoxidase across multiple moving averages. Additionally, 2‐ to 7‐day moving averages of PM 2.5 and sulfate were consistently positively associated with 8‐epi‐PGF 2α. Stronger positive associations of black carbon and sulfate with myeloperoxidase were observed among participants with diabetes than in those without. Conclusions: Our community‐based investigation supports an association of select markers of ambient air pollution with circulating biomarkers of oxidative stress.Publication Ambient Air Pollution, Adiposity, and Hepatic Steatosis: The Framingham Heart Study(2016-05-03) Li, Wenyuan; Mittleman, Murray A.; Schwartz, Joel; Coull, Brent A.; Fox, Caroline S.Air pollution-induced systemic inflammation and oxidative stress are among potential underlying mechanisms that mediate the associations between air pollution and metabolic risk factors such as obesity and insulin resistance. Furthermore, both obesity and insulin resistance are two important risk factors for non-alcoholic liver disease, one of the most common liver diseases in the United States. Although in controlled animal studies, exposure to elevated fine particulate matter (PM2.5) has been associated with increased abdominal adiposity and liver fat accumulation, few epidemiologic studies examined these associations among adults. In this work, we first examined the associations of short-term exposure to air pollution, measured at the central and local air pollution monitors, with biomarkers of oxidative stress, including myeloperoxidase and 8-epi-prostaglandin F2α (8-epi-PGF2α) among participants from the community-based Framingham Heart Study Offspring cohort. We used linear regression models and linear mixed-effects models with random intercepts, and adjusted for demographic variables, individual- and area-level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of black carbon, a correlate of local traffic pollution, with myeloperoxidase, and of PM2.5 and sulfate with 8-epi-PGF2α across multiple moving averages. Participants with diabetes appeared to be more susceptible. In the next project, we examined the associations of residential proximity to the nearest major roadway and annual average PM2.5 with body mass index (BMI) and abdominal adiposity among participants from the multidetector computed tomography (MDCT) study, a substudy that recruited participants from the Framingham Offspring and Third Generation cohorts. We estimated residential-based annual average PM2.5 concentrations using a spatial-temporal model, and estimated subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes by the MDCT scan. In this study, we found that living closer to a major roadway was associated with higher overall and abdominal adiposity. Finally, we examined the associations of residential proximity to the nearest major roadway and annual average PM2.5 with liver fat attenuation among participants from the MDCT study. In this study, liver CT attenuation in Hounsfield units was measured by abdominal MDCT scan and we defined hepatic steatosis as having a liver-to-phantom ratio ≤ 0.33. We found more liver fat (lower liver-to-phantom ratio) and higher odds of hepatic steatosis among participants who lived closer to a major roadway than those who lived further away. However, residential-based PM2.5 estimations were not associated with liver fat. Overall, we showed positive associations between short-term exposure to ambient air pollution and biomarkers of oxidative stress. We also showed that participants who lived closer to a major roadway had higher BMI, higher abdominal adiposity, and more liver fat than those who lived further away. Our observations were consistent with previous findings in animal studies and we extended these associations to adults from large community-based cohorts. Future studies are necessary to identify traffic-related factors that are associated with adipose tissue deposition other than particulate matter and to extend these findings by examining changes in abdominal adiposity or liver fat accumulation in relation to traffic-related components.