1. National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA
2. Constella Group, Research Triangle Park, North Carolina, USA
3. Pathology Associates—A Charles River Company, Durham, North Carolina, USA
4. Experimental Pathology Laboratories, Research Triangle Park, North Carolina, USA
5. Battelle Columbus Laboratories, Columbus, Ohio, USA