1. From the Centre for Vision and Vascular Sciences, Institute of Clinical Science, and the 2School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, Northern Ireland;
2. From the Centre for Vision and Vascular Sciences, Institute of Clinical Science, and
3. the Leeds Institute of Molecular Medicine, St. James's University Hospital, Leeds, United Kingdom; and
4. The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom.