Abnormal glial cytoskeleton in progressive supranuclear palsy

Tau-positive glial inclusions in progressive supranuclear palsy, corticobasal degeneration and Pick's disease

The presence of tau-positive glial inclusions has been recently found a consistent feature in the brains of patients with progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and Pick's disease (PiD). These inclusions are classified based on cellular origin as tau-positive astrocytes, presumably either fibrillary or protoplasmic, coiled bodies and glial threads. Immunohistochemically, their major structural component is abnormal tau proteins, similar to those found in Alzheimer's disease. Nevertheless, their morphology, including ultrastructural profile, has been suggested to be distinctive for each disease. The profile and extent of particular glial inclusions correlate well with disease phenotype. Highly characteristic correlations include tufts of abnormal fibers in PSP, astrocytic plaques and dense glial threads in CBD and ramified astrocytes and small Pick body-like inclusions in PiD. The significance of the inclusions in disease pathogenesis and their biochemical characteristics remain to be clarified. Nevertheless, these distinctive glial lesions most likely reflect fundamental alterations in isoform composition of tau as well as its specific cellular and regional expression in sporadic tauopathies.

Autopsy case of pure akinesia showing pallidonigro-luysian atrophy

A 60-year-old man developed levodopa-resistant pure akinesia. The patient gradually became more akinetic without accompanying gaze palsies, nuchal dystonia, or other parkinsonian features such as rigidity or tremor. At the age of 71, he died of bronchopneumonia. Neuropathologically, bilateral marked neuronal loss and gliosis were restrictedly observed in the globus pallidus, substantia nigra and corpus luysii, whereas mild gliosis without neuronal loss was found in the brain stem. With Gallyas-Braak silver stain, numerous argyrophilic fibrous structures partly surrounding glial nuclei were observed in the three major affected regions. With Bodian stain, however, they were rarely recognized. The structures were partly positive for tau protein. Rare neurofibrillary tangles were found in the three areas and brain stem. They were relatively more numerous but still sparse in the hippocampus and the parahippocampus. The present case was diagnosed as having pallidonigro-luysian atrophy based on two characteristic findings: (i) the distribution of lesions showing neuronal loss with gliosis; and (ii) significant presence of tau-positive argyrophilic fibrous structures related to glia but with the absence of neurofibrillary tangles in the major affected regions and the brain stem. As our present case uniquely showed pure akinesia for the whole clinical course, it is noteworthy to report it here with a full neuropathological evaluation. In addition, a moderate number of diffuse plaques positive for beta-amyloid were distributed in the thalamus.

Recent advances in dementia research in Japan: non-Alzheimer-type degenerative dementias

In this article, we review recent reports by Japanese researchers on non-Alzheimer-type degenerative dementias. These dementias can be classified into the following subtypes: dementias with Lewy bodies, including diffuse Lewy body disease, dementias with neurofibrillary tangles, dementias with glial tangles, including progressive supranuclear palsy and corticobasal degeneration, argyrophilic grain dementia, frontotemporal dementias including Pick's disease; dementias with degeneration of subcortical nuclei, including Huntington's disease and, last, unclassified dementias. Recently, these various forms of dementia have received much attention in Japan, as elsewhere.