[1] Michigan State Univ, Dept Radiol, E Lansing, MI 48824 USA
[2] Michigan State Univ, Precis Hlth Program, E Lansing, MI 48824 USA
[3] Karolinska Inst, Dept Med Biochem & Biophys, Div Physiol Chem 1, SE-17177 Stockholm, Sweden
[4] Univ Massachusetts, Dept Neurol, Worcester, MA 01003 USA
[5] Beth Israel Deaconess Med Ctr, Dept Neurol, Boston, MA 02215 USA
[6] Harvard Univ, Dept Chem & Chem Biol, Cambridge, MA 02138 USA