作者单位:Columbia Univ, Vagelos Coll Phys & Surg, New York, NY 10027 USA[1]USC, Keck Sch Med, Los Angeles, CA USA[2]Univ Vermont, Larner Coll Med, Burlington, VT USA[3]Univ Toronto, St Michaels Hosp, Toronto, ON, Canada[4]Brown Univ, Warren Alpert Med Sch, Providence, RI 02912 USA[5]