Scanning electron microscopy with energy-dispersive x-ray spectrometry was used to analyze the elemental content of neurofibrillary tangle (NFT)-bearing and NFT-free neurons within the Sommer's sector (H1 region) of the hippocampus in Guamanian Chamorros with amyotrophic lateral sclerosis and parkinsonism-dementia and in neurologically normal controls. Preliminary data indicate prominent accumulation of aluminum within the nuclear region and perikaryal cytoplasm of NFT-bearing hippocampal neurons, regardless of the underlying neurological diagnosis. These findings further extend the association between intraneuronal aluminum and NFT formation and support the hypothesis that environmental factors are related to the neurodegenerative changes seen in the Chamorro population.

Perikaryal collections of intermediate filaments have been described in the anterior horn motoneurons of patients with amyotrophic lateral sclerosis (ALS), but these inclusions have generally been considered rare and mainly associated with the familial form of ALS. Using the monoclonal antibody NF2F11, which recognizes phosphorylated neurofilament epitopes, we showed that focal collections of neurofilaments in anterior horn motoneurons were a characteristic finding in sporadic as well as in familial ALS; they were present in seven of nine ALS patients, but in none of nine control spinal cords. These neurofilamentous collections are not cross-reactive with antibodies directed against paired helical filaments and the microtubule associated protein tau. In addition, diffuse staining for phosphorylated neurofilament epitopes in chromatolytic anterior horn perikarya was significantly more frequent in ALS patients than in controls.

Three adults with progressive cognitive decline and extrapyramidal dysfunction were studied. They were all mentally retarded women without known chromosomal abnormalities, ranging in age at the time of onset from 31 to 42 yrs with an average duration of illness of 6 yrs. Neurological signs were stereotyped and consisted of a unilateral equinovarus foot posture followed by progressive dementia, rigidity and quadriparesis. Identical pathological findings were noted in all cases. There was marked deposition of iron-containing pigments in the globus pallidus and reticulate zone of the substantia nigra. Numerous axonal spheroids were noted in these areas and in the gracile and cuneate nuclei. In addition to these typical changes of Hallervorden-Spatz disease (HSD), abundant neurofibrillary tangles (NFTs) were found within the hippocampus, neocortex, nuclei of basal forebrain, subthalamic nucleus and brainstem reticular formation. Rare Hirano bodies and granulovacuolar degeneration were noted within the hippocampus; neuritic plaques and amyloid deposits were absent. Ultrastructurally the NFTs were mostly paired helical filaments (PHFs) with a diameter of 20 to 25 nm and a half-periodicity of 80 nm. Straight filaments and incompletely twisted forms were also seen. Immunocytochemistry with polyclonal antibodies to PHFs was positive in a distribution identical to that of Bodian-positive NFTs. Biochemical analysis of frozen frontal cortex from 1 case revealed a 94% depletion of the cholinergic marker enzyme choline acetyltransferase. Somatostatin-like immunoreactivity was within normal range. Study of 1 case with laser microprobe mass analysis revealed evidence of aluminium accumulation in tangle-bearing hippocampal neurons. Adjacent tangle-free neurons failed to show comparable accumulations. These findings indicate that adult onset HSD occurring in mentally retarded individuals may represent a distinct clinicopathological entity associated with neurofibrillary pathology without amyloid deposition.

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