[1] Univ N Carolina, Chapel Hill, NC 27599 USA
[2] Scripps Res Inst, La Jolla, CA 92037 USA
[3] Univ Milan, Milan, Italy
[4] UCSD, Dept Phys, La Jolla, CA 92093 USA
[5] Univ Bern, Theodor Kocher Inst, Bern, Switzerland
[6] Univ Penn, Dept Med, Philadelphia, PA 19104 USA
[7] Univ Virginia, Cardiovasc Res Ctr, Charlottesville, VA 22908 USA