[1] Vanderbilt Univ, Med Ctr, Nashville, TN USA
[2] Indiana Univ Sch Med, Indianapolis, IN 46202 USA
[3] Northwestern Univ, Feinberg Sch Med, Chicago, IL 60611 USA
[4] Johns Hopkins Univ, Baltimore, MD USA
[5] Univ Calgary, Calgary, AB, Canada
[6] NCI, Bethesda, MD 20892 USA
[7] Kaiser Permanente Midatlantic States, Midatlantic Permanente Res Inst, Rockville, MD USA
[8] Ctr Dis Control & Prevent, Atlanta, GA USA
[9] Univ Alabama Birmingham, Birmingham, AL USA
[10] Univ British Columbia, Vancouver, BC, Canada
[11] Univ Washington, Seattle, WA 98195 USA
[12] Kaiser Permanente Northern Calif, Kaiser Permanente Div Res, Oakland, CA USA
[13] Univ Calif San Diego, San Diego, CA 92103 USA
[14] Univ Texas Hlth Sci Ctr Houston, Houston, TX 77030 USA
[15] Vet Affairs Tennessee Valley Healthcare Syst, Nashville, TN USA