The innervation of the bone marrow in laboratory animals.
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Patients with Down syndrome (DS) over 40 years of age, prematurely and consistently develop neurofibrillary tangles (NFT), intracytoplasmic inclusions of highly insoluble straight or paired helical 12-16 nm filaments, and senile plaques (SP) composed of abnormal neurites surrounding a core of beta amyloid. These two lesions occur in distributions similar to those seen in Alzheimer disease (AD). SP and NFT are detected also in some younger individuals with DS (10-30+ years) when immunocytochemical and/or silver staining techniques are used. Retrospective and prospective attempts to relate neuropathological lesions and clinical dementia in DS have produced conflicting results. Clinical evidence of dementia and large numbers of SP and NFT were not always concordant. The predictable and consistent appearance of the AD-like neuropathologic changes in DS provides an unusual opportunity to examine the sequential development of SP and NFT. By combining morphological, immunocytochemical, and morphometric techniques with molecular biological approaches, the evolution of the structural and chemical changes in DS and AD can be examined and their relationship to clinical deficits can be evaluated.
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A sural nerve biopsy was performed on an 8-year-old boy with a chronic, slowly progressive polyneuropathy. Light and electron microscopy as well as teased nerve-fiber preparations demonstrated numerous giant axons filled with closely packed neurofilaments. Both myelinated and unmyelinated fibers were involved. Segmental demyelination, remyelination, and onion-bulb formation by multiple Schwann cell processes were observed, suggesting recurrent Schwann cell dysfunction. Abundant aggregates of cytoplasmic microfilaments occurred in Schwann cells, endothelial cells, perineurial cells, endoneurial fibroblasts, and endomysial fibroblasts. These findings support the proposal that giant axonal neuropathy is a generalized disorder of cytoplasmic microfilaments and that segmental demyelination occurs concomitantly with axonal and Schwann cell disease. The pathogenesis of this rare disorder is discussed with reference to experimental toxic neuropathies.
Paired helical filaments, the ultrastructural substrate of Alzheimer neurofibrillary change, were found in great number in a 29-year-old patient with neurovisceral lipidosis. The abnormal filaments were frequently present in the distended neurons and axons. The clinical, pathological, and ultrastructural findings were consistent with juvenile dystonic lipidosis, which is considered to be a variant of type C Niemann-Pick disease. The association of Alzheimer neurofibrillary change and central nervous system lipidosis is reviewed.
A brief description is given of neurofibrillary changes of the paired helical filament type in a variety of chronic neurological diseases. These include subacute sclerosing panencephalitis, lead encephalopathy, tuberous sclerosis, Down syndrome, Hallervorden-Spatz disease, and lipofuscinosis. In these conditions, with the exception of Hallervorden-Spatz disease neurofibrillary changes were previously recognized but paired helical filaments were identified only in some cases. Moreover, in the present series, the age of patients at death was often younger than in previously recorded cases.
A 50,000-dalton polypeptide has been purified from fractions enriched with neurofibrillary tangles of paired helical filaments from human autopsy specimens of Alzheimer disease and senile dementia of the Alzheimer type. An antiserum to this polypeptide was raised in a rabbit. This antiserum formed an immunoprecipitation line with the purified antigen and with human neurotubules in ouchterlony double-diffusion plates. The reactivity of the anti-paired helical filament protein serum with neurofibrillary tangles was studied by immunofluorescence on cryostat sections of hippocampus from Alzheimer autopsy tissue and by the peroxidase-antiperoxidase technique on paraffin sections of an Alzheimer brain biopsy. The tangles were stained with the antiserum in both systems. Preimmune rabbit serum and unrelated hyperimmune sera, used as controls, did not stain the tangles. These results show that the 50,000-dalton polypeptide purified from the neurofibrillary tangle-enriched fractions is a constituent of Alzheimer neurofibrillary tangles and, perhaps, of the paired helical filaments of which the tangles are composed.
A preliminary observation from another laboratory recently suggested that a systemic microtubular defect may exist in Alzheimer disease. To investigate this hypothesis, we obtained skin biopsies from 4 patients with Alzheimer disease and 2 age-matched controls. Fibroblast cultures were established and the tubulin networks examined using immunoadsorbent purified antitubulin antibody and the indirect immunoperoxidase technique as well as electron microscopy. The cells were also examined after treatment with vinblastine and at senescence. The microtubular network appeared as delicate fibers radiating from the perinuclear region toward the cytoplasmic margins. No differences were recognized between the controls and the fibroblast cultures from patients with Alzheimer disease. Microtubules were not visualized following incubation with vinblastine, but positively staining intracytoplasmic paracrystalline inclusions were noted. No abnormalities of microtubules were recognized in the electron microscopic examinations. These findings suggest that the neurofibrillary neuronal degeneration of Alzheimer disease is not a manifestation of a systemic disorder of the microtubular network.
The degree of neurofibrillary tangle formation, granulovascuolar degeneration, and nerve cell loss was quantified in serial sections of the hippocampal formation from the brains of 5 adults dying with Down syndrome (monogolism). These morphometric results were compared with values obtained from a series of mentally normal elderly patients reported previously. Granulovacuolar change appeared to be related as much to patient age as to the existence of monogolism. By contrast, the number of Alzheimer neurofibrillary tangles and loss of pyramidal neurons from the hippocampus exceeded levels found in considerably older subjects and fell into the same range of severity as was noted in 8 patients with Alzheimer dementia. The neuron population in the hippocampus of Down syndrome patients may be only half the expected normal number for their decade. These quantitative similarities stimulate the search for a common pathogenetic mechanism underlying cerebral changes in monogolism and senile dementia of the Alzheimer type.
Choline acetyltransferase (CAT) and acetylcholinesterase (AChE) activities were measured in spinal cord homogenates from rabbits with aluminum-induced neurofibrillary degeneration and a group of saline-treated, age-matched controls. All aluminum-treated animals showed neurofibrillary changes in the spinal cord, but CAT and AChE activities were not significantly different from levels in control animals. These results are at variance with the greatly reduced activity of these enzymes observed in Alzheimer disease and senile dementia of the Alzheimer type.
Aluminum chloride injected into the brains of developing rabbits produced profound neurofibrillary changes to neurons of spinal cord and cerebrum similar to those produced in adult rabbits, along with a variety of clinical symptoms with the exception of seizures. Approximately half of the rabbits survived for more than three weeks, and many survived for several months. Many rabbits with large numbers of neurofibrillary changes had no clinical signs and symptoms. The dynamics and topography of the neurofibrillary changes induced by aluminum chloride are described over a period of several months. Many neurofibrillary tangles were seen in neurons of spinal cord and cerebrum up to 60 days after injection of aluminum chloride. There was no obvious correlation between the degree of neurofibrillary changes and the severity of the clinical signs and symptoms. Animals examined at 85 and 100 days after injection of aluminum chloride had fewer neurofibrillary tangles of none at all, and apparently they had recovered from the neurofibrillary changes. This chronic animal model will allow better investigations of the biochemistry and pathology of neurofibrillary changes, and it will enable behavioral studies to be performed in animals with neurofibrillary changes.
Instrumental neutron activation analysis procedures were used to determine the aluminum content of various brain regions in histologically verified Alzheimer disease (AD) and in controls. The grand mean aluminum level for 74 AD specimens was 0.372 +/- 0.058 microgram/gm and for 137 adult controls, 0.467 +/- 0.033 microgram/gm, both on a wet weight basis. No difference was found at the bulk sample level between AD and adult controls, corrected for age and sex, or when frontal, temporal, and hippocampal specimens were compared. Control specimens (infancy to 85 years) showed an increase in brain aluminum concentration with age. Comparison of freeze-dried to wet weight ratios of AD and controls revealed a small increase in water content in AD brains.
Mice inoculated intracerebrally with mouse brain homogenate infected with a particular strain of scrapie agent developed amyloid and neuritic plaques and amyloid tubercles along the injection track, solid wall-like infiltrations at the injection site, or both. Our observations implicate an infections agent in the localized formation of the amyloid and the neuritic plaque--the leading pathological change found in normal elderly people and animals and in patients with senile dementia of the Alzheimer type. Further, these studies indicate that microglia appear to play a central role in the pathogenesis of amyloid formation and could be involved in the processing, production, and assembly of the fibers.
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Antiserum raised against a two-cycle-purified human brain microtubule fraction that binds specifically to tangles of senile dementia of the Alzheimer type was tested on the subthalamus, basis pontis, and midbrain sections of two patients with progressive supranuclear palsy. Tangles composed of 15 nm straight fibers in these areas showed positive immunolabeling with the antiserum. The labeling tangles appeared as a fibrous meshwork in neuronal cell bodies and occasionally in short segments of axons. Corresponding sections of brains obtained from patients with idiopathic parkinsonism, striatonigral degeneration, and olivopontocerebellar atrophy treated with the same antiserum did not display peroxidase products. Only in the elderly subjects and patients with postencephalitic parkinsonism did the periaqueductal gray and median raphe show occasional cells that reacted positively with the antiserum. Tangles in the substantia nigra of patients with postencephalitic parkinsonism were also recognized by the antiserum. The results suggest that the two morphologically distinct neurofibrillary tangles share their immunological properties with components present in microtubule fractions of normal brain.
A review of over 2,000 cases of Creutzfeldt-Jakob disease and related disorders in the literature and our own files yielded 231 cases of dementia with early lower motor neuron signs. The clinical-pathological profiles of the 231 cases were distinctly different from those of cases of transmissible Creutzfeldt-Jakob disease: the patients had a longer illness, and their brains lacked the typical spongiform change. Brain tissue from 33 of these patients has been inoculated intracerebrally into nonhuman primates, but only 2 atypical cases transmitted a spongiform encephalopathy; 23 have been incubating from three to twelve years and can be considered negative transmission experiments. The findings suggest that most cases of dementia associated with early amyotrophy are more closely related to classic amyotrophic lateral sclerosis than to transmissible Creutzfeldt-Jakob disease and do not deserve the label of "amyotrophic Creutzfeldt-Jakob disease." When lower motor neuron involvement occurs in transmissible Creutzfeldt-Jakob disease, it is usually late and accompanied by signs of a more fulminant cerebral and cerebellar involvement.