1. Charles Salt Centre for Human Metabolism, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry SY10 7AG, UK
2. Institute of Medicine, University of Chester, Bache Hall, Chester CH1 4BJ, UK
3. Institute of Medicine, University Centre Shrewsbury, University of Chester, The Guildhall, Frankwell Quay, Shrewsbury, Shropshire SY3 8HQ, UK