[1] Univ Alberta, Dept Med, Edmonton, AB T6G 2E1, Canada
[2] Univ Texas, Ctr Hlth, Transplant Ctr, San Francisco, CA USA
[3] New England Med Ctr Transplant Surg, Boston, MA USA
[4] Mayo Clin, Coll Med, Rochester, MN USA
[5] F Hoffmann La Roche & Co Ltd, CH-4002 Basel, Switzerland
[6] Roche Prod Ltd, Welwyn Garden City AL7 3AY, Herts, England