[1] S Dakota State Univ, EA Martin Program Human Nutr, Brookings, SD 57007 USA
[2] Univ S Dakota, Sch Med, Childrens Care Hosp & Sch, Sioux Falls, SD USA
[3] Univ N Carolina, Dept Orthopaed, Chapel Hill, NC USA
[4] AI du Pont Hosp Children, Dept Res, Wilmington, DE USA