1 Division of Endocrinology, Diabetes & Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, M13 9WL, Manchester, UK. frederick.wu@manchester.ac.uk.
2 Professor Emeritus of Reproductive Endocrinology Institute of Reproductive and Developmental Biology, Department of Digestion, Metabolism and Reproduction, Hammersmith Campus Imperial College London, W12 0NN, London, UK.