Affiliation: | Center for Skeletal Aging and Osteoporosis, Veterans Affairs Medical Center and Medical College of Pennsylvania-Hahnemann School of Medicine, Allegheny University of the Health Sciences and University of Pennsylvania, Philadelphia, PA 19104;Morehouse School of Medicine, Department of Microbiology and Immunology, Atlanta, GA 30310, USA;The Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, UK |