[1] Purdue Univ, W Lafayette, IN 47907 USA
[2] Oregon Hlth & Sci Univ, Portland, OR 97201 USA
[3] Case Western Reserve Univ, Cleveland, OH 44106 USA
[4] Loyola Univ, Med Ctr, Maywood, IL 60153 USA
[5] Georgia Inst Technol, Atlanta, GA 30332 USA
[6] Duke Univ, Med Ctr, Durham, NC 27706 USA