1. Internal Medicine Iowa City Veterans Administration Health Center Iowa City IA USA
2. Department of Internal Medicine University of Iowa Carver College of Medicine Iowa City IA USA
3. U.S. Department of Agriculture Agricultural Research Service Beltsville Human Nutrition Research Center Diet, Genomics and Immunology Laboratory Beltsville MD USA
4. Department of Pediatrics H.B. Wells Center for Pediatric Research and Department of Microbiology and Immunology Indiana University School of Medicine Indianapolis IN USA