title: Characterization of paired helical filaments by scanning transmission electron microscopy.
abstract: Paired helical filaments (PHFs) are abnormal twisted filaments composed of hyperphosphorylated tau protein. They are found in Alzheimer's disease and other neurodegenerative disorders designated as tauopathies. They are a major component of intracellular inclusions known as neurofibrillary tangles (NFTs). The objective of this review is to summarize various structural studies of PHFs in which using scanning transmission electron microscopy (STEM) has been particularly informative. STEM provides shape and mass per unit length measurements important for studying ultrastructural aspects of filaments. These include quantitative comparisons between dispersed and aggregated populations of PHFs as well as comparative studies of PHFs in Alzheimer's disease and other neurodegenerative disorders. Other approaches are also discussed if relevant or complementary to studies using STEM, e.g., application of a novel staining reagent, Nanovan. Our understanding of the PHF structure and the development of PHFs into NFTs is presented from a historical perspective. Others goals are to describe the biochemical and ultrastructural complexity of authentic PHFs, to assess similarities between authentic and synthetic PHFs, and to discuss recent advances in PHF modeling.
authors.affiliation: Neuroinflammation Research Laboratories, Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029, USA. Hanna.Reding@mssm.edu
authors.forename: Hanna
authors.initials: H
authors.lastname: Ksiezak-Reding
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Wall
mesh_terms: D000544:Alzheimer Disease / Q000473:pathology; D016718:Arachidonic Acid / Q000378:metabolism; D006801:Humans; D017348:Microscopy, Electron, Scanning Transmission; D016253:Microscopy, Immunoelectron; D016874:Neurofibrillary Tangles / Q000378:metabolism / Q000648:ultrastructure*; D010766:Phosphorylation; D020774:Pick Disease of the Brain / Q000473:pathology; D016875:tau Proteins / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D016875:tau Proteins; D016718:Arachidonic Acid