[1] Univ Penn, Sch Med, Inst Med & Engn, Vagelos Res Labs 1010, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Philadelphia, PA 19104 USA
[3] Kyushu Univ, Grad Sch Med Sci, Fukuoka 812, Japan
[4] Univ Penn, Dept Pathol & Lab Med, Philadelphia, PA 19104 USA
[5] Univ Colorado, Hlth Sci Ctr, Dept Pediat, Denver, CO 80262 USA
[6] Med Univ S Carolina, Dept Anat, Charleston, SC 29425 USA
[7] Hosp Sick Children, Toronto, ON M5G 1X8, Canada
[8] Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA