1. Oxford Centre for Diabetes, Endocrinology, and Metabolism (C.P., C.A.M., F.K., L.H.), Oxford OX3 7LE, United Kingdom
2. Oxford Centre for Clinical Magnetic Resonance Research (M.P., R.B., S.N.), University of Oxford, Churchill Hospital, Oxford OX3 7LE, United Kingdom
3. Translational Gastroenterology Unit (M.P.), Oxford OX3 9DU, United Kingdom
4. John Radcliffe Hospital and National Institute for Health Research Oxford Biomedical Research Centre (F.K.), Oxford University Hospital Trusts, Oxford OX3 9DU, United Kingdom