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1.  Vascular Responses to Long- and Short-Term Exposure to Fine Particulate Matter 
Objectives
This study evaluated the association of long- and short-term air pollutant exposures with flow-mediated dilation (FMD) and baseline arterial diameter (BAD) of the brachial artery using ultrasound in a large multicity cohort.
Background
Exposures to ambient air pollution, especially long-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM2.5), are linked with cardiovascular mortality. Short-term exposure to PM2.5 has been associated with decreased FMD and vasoconstriction, suggesting that adverse effects of PM2.5 may involve endothelial dysfunction. However, long-term effects of PM2.5 on endothelial dysfunction have not been investigated.
Methods
FMD and BAD were measured by brachial artery ultrasound at the initial examination of the Multi-Ethnic Study of Atherosclerosis. Long-term PM2.5 concentrations were estimated for the year 2000 at each participant’s residence (n = 3,040) using a spatio-temporal model informed by cohort-specific monitoring. Short-term PM2.5 concentrations were based on daily central-site monitoring in each of the 6 cities.
Results
An interquartile increase in long-term PM2.5 concentration (3 μg/m3) was associated with a 0.3% decrease in FMD (95% confidence interval [CI] of difference: −0.6 to −0.03; p = 0.03), adjusting for demographic characteristics, traditional risk factors, sonographers, and 1/BAD. Women, nonsmokers, younger participants, and those with hypertension seemed to show a greater association of PM2.5 with FMD. FMD was not significantly associated with short-term variation in PM2.5 (−0.1% per 12 μg/m3 daily increase [95% CI: −0.2 to 0.04] on the day before examination).
Conclusions
Long-term PM2.5 exposure was significantly associated with decreased endothelial function according to brachial ultrasound results. These findings may elucidate an important pathway linking air pollution and cardiovascular mortality.
doi:10.1016/j.jacc.2012.08.973
PMCID: PMC3665082  PMID: 23103035
air pollution; atherosclerosis; cardiovascular mortality; endothelial function; flow-mediated dilation; traffic
2.  Long-Term Exposure to Airborne Particles and Arterial Stiffness: The Multi-Ethnic Study of Atherosclerosis (MESA) 
Environmental Health Perspectives  2011;119(6):844-851.
Background
Increased arterial stiffness could represent an intermediate subclinical outcome in the mechanistic pathway underlying associations between average long-term pollution exposure and cardiovascular events.
Objective
We hypothesized that 20 years of exposure to particulate matter (PM) ≤ 2.5 and 10 μm in aerodynamic diameter (PM2.5 and PM10, respectively) would be positively associated with arterial stiffness in 3,996 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) who were seen at six U.S. study sites.
Methods
We assigned pollution exposure during two decades preceding a clinical exam (2000–2002) using observed PM10 from monitors nearest participants’ residences and PM10 and PM2.5 imputed from a space-time model. We examined three log-transformed arterial stiffness outcome measures: Young’s modulus (YM) from carotid artery ultrasound and large (C1) and small (C2) artery vessel compliance from the radial artery pulse wave. All associations are expressed per 10 μg/m3 increment in PM and were adjusted for weather, age, sex, race, glucose, triglycerides, diabetes, waist:hip ratio, seated mean arterial pressure, smoking status, pack-years, cigarettes per day, environmental tobacco smoke, and physical activity. C1 and C2 models were further adjusted for heart rate, weight, and height.
Results
Long-term average particle exposure was not associated with greater arterial stiffness measured by YM, C1, or C2, and the few associations observed were not robust across metrics and adjustment schemes.
Conclusions
Long-term particle mass exposure did not appear to be associated with greater arterial stiffness in this study sample.
doi:10.1289/ehp.0901524
PMCID: PMC3114821  PMID: 21245016
air pollution; arterial stiffness; environmental air pollutants; epidemiology
3.  ENDOTHELIAL DYSFUNCTION AND THE RISK OF HYPERTENSION: THE MULTI-ETHNIC STUDY OF ATHEROSCLEROSIS 
Hypertension  2010;55(5):1210-1216.
Hypertension is associated with impaired endothelial function in cross-sectional studies. However, few longitudinal data exist on whether endothelial dysfunction precedes the development of hypertension. We examined the cross-sectional and longitudinal relationships between endothelial-dependent brachial artery flow-mediated dilation (FMD) and hypertension prevalence and incidence in 3,500 participants from the Multi-Ethnic Study of Atherosclerosis (MESA), an ethnically diverse, community-based cohort study. At baseline, the prevalence ratios (95% CI) of hypertension from the highest to the lowest quartile of FMD were 1.00 (referent), 1.26 (1.12 – 1.40), 1.35 (1.21 – 1.52), and 1.68 (1.50 – 1.87) (linear trend P < 0.001). This association remained (P = 0.017) after adjustment for demographics (age, gender, ethnicity), MESA site, and other risk factors. Of the 1,869 participants without hypertension at baseline, 584 (31.3%) developed hypertension over a median follow-up of 4.8 years. The unadjusted relative risks (95% CI) of incident hypertension from the highest to the lowest quartile of FMD were 1.00 (referent), 1.38 (1.14 – 1.67), 1.44 (1.19 – 1.74), and 1.64 (1.36 – 1.97) (linear trend P < 0.001). However, after adjustment for demographics and MESA site, the relationship between FMD and incident hypertension was attenuated and not statistically significant: 1.00 (referent), 1.26 (1.04 – 1.52), 1.19 (0.98 – 1.44), and 1.18 (0.97 – 1.44). The longitudinal results also did not appreciably change after adjustment for additional risk factors and baseline blood pressure levels. In this sample, reduced FMD was not an independent predictor of hypertension incidence, suggesting that impaired endothelial function does not play a major role in the development of hypertension.
doi:10.1161/HYPERTENSIONAHA.109.143123
PMCID: PMC2896877  PMID: 20308612
hypertension; blood pressure; endothelium; atherosclerosis; epidemiology
4.  Individual pathogens, pathogen burden, and markers of subclinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis 
We examined the cross-sectional relationships of subclinical atherosclerosis – expressed by carotid intimal–medial thickness and coronary calcification – with antibodies to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, herpes simplex virus, hepatitis A virus, and pathogen burden (number of positive pathogens). A random sample of 1056 individuals chosen from 5030 Multi-Ethnic Study of Atherosclerosis cohort participants were included. After multiple adjustment, no associations were found between atherosclerosis measures and either individual pathogens or pathogen burden. Interactions with inflammatory and endothelial function markers, demographic factors, BMI, high-density lipoprotein, diabetes, and smoking were also explored. The only interaction that was large, qualitative, statistically significant (P < 0.05) and in the expected direction was that between hepatitis A virus and soluble intercellular adhesion molecule-1 with regard to Agatston calcium score: the difference between hepatitis A virus-positive and hepatitis A virus-negative participants was −86 units in participants with soluble intercellular adhesion molecule-1 below the median, and +162 units in those with soluble intercellular adhesion molecule-1 equal or above the median. However, given the number of interactions that were explored, these results must be interpreted cautiously.
Findings from the present analyses do not provide support for an infectious etiology for subclinical atherosclerosis. However, the study’s limitations, which include its cross-sectional design and insufficient statistical power, suggest that inferences from its findings should be made cautiously.
doi:10.2459/JCM.0b013e32832cacab
PMCID: PMC2732746  PMID: 19444130
atherosclerosis; infections; pathogens

Results 1-4 (4)