Departments of Medicine and Physiology, Division of Endocrinology and Metabolism, University of Toronto, Toronto, Ontario, Canada Correspondence to Gary F. Lewis, MD, FRCPC, Toronto General Hospital, 200 Elizabeth Street, EN12-218, Toronto, Ontario, Canada M5G2C4 Tel: +1 416 340 4270; fax: +1 416 340 3314; e-mail: [email protected]