Abstract
Alzheimer neurofibrillary tangles (NFT) and senile plaque core amyloid (SPCA) isolated from the brain of patients with Alzheimer's disease were freeze-dried and replicated with a new platinum-carbon (Pt-C) vertical deposition method for high-resolution transmission electron microscopy (TEM). The resolution of this vertical Pt-C replication method is superior to either of the more conventional 20° rotary replication or 45° unidirectional replication methods and is dependent on the Pt-C film thickness coating the specimen. The paired helical filaments (PHF) observed within the tangles were right-handed helices with a fairly regular twist period averaging 79.3 ± 5.9 nm and a fairly regular maximum width averaging 14.9 ± 1.0 nm. The PHF regions of minimum width were not regular and fell into three size categories: 2.4 ± 0.3 nm, 4.9 ± 0.6 nm and 9.6 ± 1.4 nm. In addition to the PHF found in the tangles, a new filament was found within all the tangles. These 2.1 ± 0.2 nm diameter filaments were triple-stranded left helices with 1.0 ± 0.2 nm diameter strands with a structure identical to bovine τ. Like bovine τ polymer a number of filaments (1.30 nm to 2.38 nm) were longer than a fully strectched τ monomer of 96 nm. Images of neuritic senile plaque core amyloid (SPCA) showed that amyloid had a more solid appearance than the NFT and its branched filament structures were unlike the ∼2.1 nm diameter filaments or the PHF found in NFT.
Published Version
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