1. Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
2. Division of Nuclear Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
3. Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
4. Division of Molecular Medicine, Department of Anesthesiology, The Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California