[1] Univ Sheffield, Sheffield, S Yorkshire, England
[2] Univ Hosp Heidelberg, Thoraxclin, Heidelberg, Germany
[3] Univ Calif San Francisco, Fresno, CA USA
[4] Hosp Clin Barcelona, Barcelona, Spain
[5] Sapienza Univ Rome, Rome, Italy
[6] Univ Cincinnati, Med Ctr, Cincinnati, OH 45267 USA
[7] Univ Calif Davis, Davis Hlth, Davis, CA 95616 USA
[8] United Therapeut Corp, Res Triangle Pk, NC USA
[9] Univ Rochester, Med Ctr, Rochester, NY 14627 USA