Initial studies with high resolution TEM and electron energy loss spectroscopy studies of ferritin cores extracted from brains of patients with progressive supranuclear palsy and Alzheimer disease

Studies of crystallographic structure and composition of core nanocrystals of ferritin bound to aberrant tau filaments extracted from progressive supr anuclear Palsy (PSP) and Alzheimer disease (AD) brain tissues were performe d using high resolution transmission electron microscopy (HRTEM) and electr on energy loss spectroscopy (EELS). The results were compared with those ob tained from synthetic Fe3O4 crystal (magnetite) and horse spleen ferritin c ores. Core dimensions of ferritin molecules from PSP and AD were similar to those found in normal brain. Ferritin cores nanocrystals in AD seems to ha ve less ordered structure than in PSP. Some nanocrystals did not have the h exagonal ferrihydrite structure generally found in healthy ferritin but rat her a cubic structure similar to magnetite, a crystalline form in which bot h Fe2+ and Fe3+ are present. The presence of ferrous ion, Fe2+, may indicat e some dysfunction in these pathological ferritins that might contribute to production of free radicals via the Fenton reaction involved in neurodegen eration.