1. From the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, 733 N Broadway, Baltimore, MD 21205 (O.H.O., A.D.O., S.M.I.U., O.D., M.J.B.); American Heart Association Tobacco Regulation and Addiction Center, Dallas, Tex (O.H.O., A.D.O., S.M.I.U., M.J.B.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (O.D.).