[1] Univ Calif Davis, Ctr Med, Dept Internal Med, Sacramento, CA USA
[2] Blood Ctr Pacific, San Francisco, CA USA
[3] Blood Syst Inc, Scottsdale, AZ USA
[4] New England Res Inst, Watertown, MA USA
[5] Univ N Carolina, Sch Med, Dept Med, Chapel Hill, NC 27514 USA