[1] Univ Puerto Rico, Dept Biol, Coll Nat Sci, San Juan, PR 00931 USA
[2] Univ Puerto Rico, Dept Chem, Coll Nat Sci, San Juan, PR 00931 USA
[3] Univ Puerto Rico, Prot Mass Spectrometry Core Facil, Coll Nat Sci, San Juan, PR 00931 USA
[4] Emory Univ, Sch Med, Alzheimers Dis Res Ctr, Neuropathol Core Facil, Atlanta, GA USA
[5] Univ Penn, Cellular & Mol Neuropathol Program, Philadelphia, PA 19104 USA
[6] Univ Penn, Mahoney Inst Neurol Sci, Geriatr Psychiat Program, Philadelphia, PA 19104 USA