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Associations of endothelial function and air temperature in diabetic subjects
Citation:
Herbst, M., A. Schneider, A. Hinderliter, W. CASCIO, L. M. NEAS, M. W. CASE, AND R. B. DEVLIN. Associations of endothelial function and air temperature in diabetic subjects. Presented at International Society of Environmental Epidemiology, Dublin, Northern Ireland, IRELAND, August 25 - 29, 2009.
Impact/Purpose:
These data suggest that endothelial function is associated with short-term air temperature changes. Endothelial dysfunction might contribute to the increase in cardiovascular morbidity and mortality associated with cold weather.
Description:
Background and Objective: Epidemiological studies consistently show that air temperature is associated with changes in cardiovascular morbidity and mortality. However, the biological mechanisms underlying the association remain largely unknown. As one index of endothelial function, flow-mediated dilatation can be viewed as a "barometer" of vascular health. Therefore, the purpose ofthis study was to analyze the short-term effects air temperature on markers ofendothelial function in diabetic patients. Methods: A prospective panel study was conducted on 22 people with diabetes in Chapel Hill, NC, from Nov 2004-Dec 2005. Each subject was studied for 4 consecutive days. Daily measurements ofmeteorological data were acquired from the rooftop ofthe patient exam site. Brachial artery FMD measured by brachial artery ultrasound as well as blood markers on endothelial function were assessed during each patient visit. Data were analyzed using random effects models adjusting for relative humidity, barometric pressure, particles with an aerodynamic diameter <2.511m and day ofthe week. Results: FMD decreased in association with a IOOC decrease in temperature on the same day (percent-change in mean level:-41.6% with 95%-confidence interval (CI) [-69.3%; -13.9%]) as well as with a delay of one day (-33.0%; 95%-CI:[-64.8%; -1.2%]), four days (-34.2%; 95%-CI: [-63.3%; -5.1%]) and with the 5-day-average (-43.4%; 95%-CI: [-2.6%; -84.3%]). In soluble intercellular adhesion molecules an increase in association with the 5-day-average of temperature was found (78.7%; 95%-CI: [19.5%; 137.8%]). A similar trend was seen for soluble vascular cell adhesion molecules. Other blood markers representing endothelial function such as von Willebrand factor and E-selectin did not show any temperature effect. Conclusion: These data suggest that endothelial function is associated with short-term air temperature changes. Endothelial dysfunction might contribute to the increase in cardiovascular morbidity and mortality associated with cold weather. This abstract of a proposed presentation does not necessarily represent EPA policy.