[1] Univ Pittsburgh, Vasc Med Inst, Pittsburgh, PA USA
[2] NHLBI, Sickle Cell Vasc Dis Sect, NIH, Bethesda, MD 20892 USA
[3] Univ Pittsburgh, Dept Med, Div Hematol Oncol, Pittsburgh, PA USA
[4] Hemophilia Ctr Western Penn, Pittsburgh, PA USA
[5] NIH, Dept Crit Care Med, Ctr Clin, Bethesda, MD 20892 USA
[6] ITXM Diagnost, Pittsburgh, PA USA