[1] Univ Oxford, Oxford, England
[2] John Radcliffe Hosp, Oxford OX3 9DU, England
[3] Univ Leeds, Leeds, W Yorkshire, England
[4] Royal Brompton Hosp, London SW3 6LY, England
[5] Natl Heart & Lung Inst, London, England
[6] N Shore Hosp, Auckland, New Zealand