1. Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, USA
2. Department of Transfusion Medicine, National Institutes of Health, Bethesda, Maryland, USA
3. Hospital Epidemiology Service, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
4. Clinical Monitoring Research Program Directorate, Frederick National Laboratory for Cancer Research, Rockville, Maryland, USA
5. MedStar Washington Hospital Center, Washington, DC, USA