[1] Univ Penn, Dept Physiol, Philadelphia, PA 19104 USA
[2] Univ Penn, Inst Med & Engn, Philadelphia, PA 19104 USA
[3] Univ Penn, Dept Pathol & Med, Philadelphia, PA 19104 USA
[4] Univ Penn, Dept Lab Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Dept Pharmacol, Philadelphia, PA 19104 USA
[6] Univ Toronto, Fac Dent, Matrix Dynam Grp, Toronto, ON M5S 3E2, Canada