[1] Washington Univ, Med Scientist Training Program, Sch Med, St. Louis, MO USA
[2] Washington Univ, Dept Neurol Surg, Sch Med, St. Louis, MO 63130 USA
[3] Univ Iowa, Dept Neurosurg, Carver Coll Med, Iowa, IA USA
[4] Washington Univ, Bernard Becker Med Lib, Sch Med, St. Louis, MO USA
[5] Washington Univ, Brain Tumor Ctr, Siteman Canc Ctr, Sch Med, St. Louis, MO 63130 USA