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Immunocytochemical characterization of neurofibrillary tangles in amyotrophic lateral sclerosis and parkinsonism-dementia of Guam.

Cryostat-cut sections of formalin-fixed and unfixed hippocampus from 23 Guamanian Chamorros with clinically and neuropathologically verified amyotrophic lateral sclerosis (ALS) (8 cases) and parkinsonism-dementia (PD) (15 cases) and from 12 neurologically normal Guamanians (5 with and 7 without neurofibrillary degeneration) were evaluated by the immunoperoxidase technique, using monoclonal antibodies against phosphorylated neurofilament, human fetal microtubule-associated protein tau, and paired helical filaments. On immunostaining, all three antibodies showed intracellular tangles in the hippocampal neurons of patients with ALS, patients with PD, and in neurologically normal Guamanians with neurofibrillary pathology, but the correlation of immunostaining between these antibodies was not absolute. Extracellular or ghost tangles were immunostained only with the antibody against paired helical filaments. Our immunocytochemical data indicate that the antigenic composition of neurofibrillary tangles in Guamanian ALS and PD is similar to that of Alzheimer's disease, suggesting a common pathogenetic pathway for neurofibrillary tangle formation in these neurodegenerative disorders.

Adult↗

Neurofibrillary tangles and neuropil threads as a cause of dementia in Parkinson's disease.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common age-related degenerative disorders of the human brain. Both diseases involve multiple neuronal systems and are the consequences of cytoskeletal abnormalities. In AD susceptible neurons produce neurofibrillary changes, while in Parkinson's disease, they develop Lewy bodies. In AD six developmental stages can be distinguished on account of the predictable manner in which the neurofibrillary changes spread across the cerebral cortex. During the course of PD numerous limbic determined parts of the brain undergo specific lesions regulating endocrine and autonomic functions. In general, the extranigral destructions are in themselves not sufficient to produce overt intellectual deterioration. Fully developed Parkinson's disease with concurring incipient Alzheimer's disease is likely to cause impaired cognition.

Dementia↗

Neurofibrillary tangles have no obligatory predilection for acetylcholinesterase-rich neurons.

Parts of the brain that are prone to NFT formation normally contain many neurons that are intensely acetylcholinesterase (AChE)-positive. In this study, we used thioflavin-S immunofluorescence, AChE histochemistry, and AChE immunocytochemistry to investigate the possibility that intense AChE positivity may act as a perikaryal marker for the vulnerability to NFT formation. Our observations in entorhinal and motor cortices and in the subthalamic nucleus demonstrate major mismatches between the distribution of AChE-rich neurons in normal brains and the distribution of NFT in AD. There is therefore no obligatory relationship between intense AChE positivity in the premorbid period and subsequent vulnerability to tangle formation.

Acetylcholinesterase↗

Abnormally phosphorylated tau protein related to the formation of neurofibrillary tangles and neuropil threads in the cerebral cortex of sheep and goat.

Frontal sections including temporal isocortex, entorhinal region and hippocampus from aged domestic animals (dog, cat, horse, sheep and goat) were studied for Alzheimer-related changes using immunostaining with the AT8 antibody for abnormally phosphorylated tau protein and selective silver techniques for A4 amyloid and neurofibrillary changes of the Alzheimer type. The material available to us did not show A4 amyloid deposits or argyrophilic neurofibrillary changes. Only the brains of aged sheep and goat exhibited the presence of AT8-immunoreactive pyramidal cells in the entorhinal region and hippocampal formation. Two groups of AT8-positive neurons could be observed: The first group contained evenly distributed immunoreactive material in all parts of the soma, the dendrites and the axon. The neuronal processes appeared quite normal. The second group, however, showed conspicuous changes in the cellular processes consisting of a loss of immunoreactivity within the axon and the proximal dendrites and the appearance of intensely stained swellings within the curved distal dendrites. These changes were closely reminiscent to alterations of the cytoskeleton known to occur at the same location in the aging human brain and in Alzheimer's disease. The findings justify a closer look at sheep and goat when searching for suitable animal models for experimental studies of the conditions responsible for the development of Alzheimer-related neurofibrillary changes.

Animals↗

Dementia in hereditary cerebral hemorrhage with amyloidosis-Dutch type is associated with cerebral amyloid angiopathy but is independent of plaques and neurofibrillary tangles.

Cerebral amyloid angiopathy is frequently found in demented and nondemented elderly persons, but its contribution to the causation of dementia is unknown. Therefore, we investigated the relation between the amount of cerebral amyloid angiopathy and the presence of dementia in 19 patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type. The advantage of studying hereditary cerebral hemorrhage in amyloidosis-Dutch type is that patients with this disease consistently have severe cerebral amyloid angiopathy with minimal neurofibrillary pathology. The amount of cerebral amyloid angiopathy, as quantified by computerized morphometry, was strongly associated with the presence of dementia independent of neurofibrillary pathology, plaque density, or age. The number of cortical amyloid beta-laden severely stenotic vessels, vessel-within-vessel configurations, and cerebral amyloid angiopathy-associated microvasculopathies was associated with the amount of cerebral amyloid angiopathy and dementia. A semiquantitative score, based on the number of amyloid beta-laden severely stenotic vessels, completely separated demented from nondemented patients. These results suggest that extensive (more than 15 amyloid beta-laden severely stenotic vessels in five frontal cortical sections) cerebral amyloid angiopathy alone is sufficient to cause dementia in hereditary cerebral hemorrhage with amyloidosis-Dutch type. This may have implications for clinicopathological correlations in Alzheimer's disease and other dementias with cerebral amyloid angiopathy.

Aged↗

Decrease in adenylate cyclase activity antecedes neurofibrillary tangle formation.

In previous studies, the formation of cAMP was seen to be significantly reduced in various brain regions in Alzheimer patients. Recently, a staging system was introduced in which Alzheimer-related. histopathological changes were classified according to the pattern of alterations rather than their density. In this study, we examined the degree of correlation between these stages and the postmortem activity of the CAMP-generating enzyme adenylate cyclase. Our findings suggest that forskolin-stimulated adenylate cyclase activity is significantly decreased before major neurofibrillary changes develop. Early impairment of postreceptor signalling could have potentially important consequences for drug treatment and/or for the development of neurofibrillary changes.

Adenylyl Cyclases↗