[1] John Radcliffe Hosp, Oxford OX3 9DU, England
[2] MRC, Clin Trials Unit, London, England
[3] Univ Nottingham, Nottingham NG7 2RD, England
[4] Royal Victoria Infirm, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, England
[5] Western Gen Infirm, Edinburgh, Midlothian, Scotland
[6] NHS Blood & Transplant, Oxford, England