β-Amyloid 22-35 (Amyloid β-Protein 22-35) TFA, the residues 22-35 fragment ofβ-amyloid protein, has a cytotoxic effect on cultured neurons from the rat hippocampus in serum-free medium. β-Amyloid 22-35 TFA forms aggregates and typical amyloid fibrils resembling those of the β-amyloid protein in neutral buffer solution).