1. From the Department of Medical Physiology (P.N., L.P.), Faculty of Health Sciences, University of Copenhagen, Denmark; Medical Department B (M.D., M.G., B.P., A.G.), Division of Aviation Medicine, The Heart Centre, Copenhagen University Hospital (Rigshospitalet), Denmark; and Department of Internal Medicine and Endocrinology (N.J.C.), Herlev University Hospital, Denmark.