1. Department of Cardiology (T.A., T.S., Y.Y., R.F., Y.A., K.N., S.H., S.S., M.I.), Institute of Medicine, University of Tsukuba, Ibaraki, Japan.
2. Department of Respiratory Medicine (T.A., N.H.), Institute of Medicine, University of Tsukuba, Ibaraki, Japan.
3. Division of Regenerative Medicine, Transborder Medical Research Center (R.F.), Institute of Medicine, University of Tsukuba, Ibaraki, Japan.
4. Departments of Anatomy (Y.K.), Keio University School of Medicine, Tokyo, Japan.
5. Faculty of Health Science, Tsukuba University of Technology, Japan (S.S.).
6. Cardiology (M.I.), Keio University School of Medicine, Tokyo, Japan.