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Query: UMLS:C0042373 (vascular disease)
 17,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The abnormal neurites that surround beta-amyloid in senile plaques (SP) in Alzheimer disease contain beta-amyloid precursor protein (beta APP) or abnormal filaments which react with antibodies to tau. Occasionally, beta APP and abnormal filaments are present in the same neurite. Whether both types of abnormal neurites are reactive to the presence of beta-amyloid or they are instead independent from each other is unknown. To begin to clarify this issue, we comparatively studied beta APP and tau-epitopes in SP from cases of classical Alzheimer disease and cases of cerebral amyloid angiopathy, with SP but without neurofibrillary pathology. In subjects with cerebral amyloid angiopathy, about one-third of SP, the same percentage as in Alzheimer disease, were beta APP reactive in the absence of tau-reactivity. beta APP epitopes were ultrastructurally localized in dense bodies of probable lysosomal origin, adjacent to the core of SP. These results demonstrate that beta APP and tau-reactive cytoskeletal alterations occur independently in the neurites of SP. The presence of beta APP in dystrophic neurites of SP and the localization of beta APP in lysosomes suggest that beta APP containing dystrophic neurites may play a role in the extracellular deposition of amyloid.
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PMID:Senile plaques in cerebral amyloid angiopathy show accumulation of amyloid precursor protein without cytoskeletal abnormalities. 128 May 24

Several families with an early-onset form of familial Alzheimer's disease have been found to harbour mutations at a specific codon (717) of the gene for the beta-amyloid precursor protein (APP) on chromosome 21. We now report, a novel base mutation in the same exon of the APP gene which co-segregates in one family with presenile dementia and cerebral haemorrhage due to cerebral amyloid angiopathy. The mutation results in the substitution of alanine into glycine at codon 692. These results suggest that the clinically distinct entities, presenile dementia and cerebral amyloid angiopathy, can be caused by the same mutation in the APP gene.
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PMID:Presenile dementia and cerebral haemorrhage linked to a mutation at codon 692 of the beta-amyloid precursor protein gene. 130 39

The brains of individuals with Down's syndrome in their 40's and 50's begin to develop changes that are otherwise seen only in patients with Alzheimer disease. Neurons develop neurofibrillary tangles, flame-shaped alterations composed mainly of condensed cytoskeletal proteins. Another protein, beta/A4 amyloid, is deposited in large amounts in the form of senile plaques and, around blood vessels, amyloid angiopathy. With increasing age, Down syndrome individuals accumulate more and more of these changes. Different parts of the brain are affected to varying degrees by these two alterations. Surprisingly, the pattern of accumulation of neurofibrillary tangles and senile plaques is characteristic, and follows a predictable pattern. We have characterized this pattern in the hippocampal formation in a group of Down individuals, ages 13-71. Certain specific neurons such as those in layer II of entorhinal cortex and the CA1/subiculum field of the hippocampus are exquisitely vulnerable to tangle formation, and are the first neurons to be affected. Perhaps 20-30 years pass as the disease process evolves from mild to severe pathological changes. One hypothesis for why Down individuals would be predisposed to developing Alzheimer pathology is the observation that the gene that encodes the precursor of the amyloid protein is located on chromosome 21. An extra copy of this gene, such as occurs in Down syndrome, may lead to "overproduction" of amyloid, and ultimately to its accumulation as senile plaques. Experiments to test this hypothesis are now underway.
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PMID:Down syndrome and Alzheimer disease. 140 40

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D) (or familial cerebral amyloid angiopathy) and familial Alzheimer's disease (FAD) share several properties. Both are autosomal dominant forms of cerebral amyloidosis characterized by beta-amyloid (A beta) deposition. In HCHWA-D the A beta is predominantly found in blood vessels and in early parenchymal plaques, whereas in AD parenchymal A beta deposits in the form of senile plaques and neurofibrillary tangles are a more prominent finding. Point mutations in the amyloid precursor protein (APP) have recently been described, in both conditions. A G to C transversion at codon 618 (extracellular portion of APP695), producing a single amino acid substitution of glutamine instead of glutamine acid, occurs in HCHWA-D; whereas mutations at codon 642 in the intramembrane region of APP695 (phenylalanine, isoleucine, or glycine instead of valine) are associated with early onset FAD. This suggests that the site of particular mutations in the APP gene and the type of amino acid substitution in the APP holoprotein are more important in determining clinicopathological phenotype and age at which A beta is deposited. Thus FAD and HCHWA-D can be regarded as two sides of the same coin.
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PMID:Molecular biology of Alzheimer's amyloid--Dutch variant. 146 89

We present prospective clinical and neuropathologic details of a pedigree segregating familial Alzheimer's disease (FAD) associated with a mutation (G----A substitution) at nucleotide 2149 in exon 17 of the amyloid precursor protein (APP) gene. This mutation, which is predicted to cause the missense substitution of isoleucine for valine at codon 717 of APP, cosegregated perfectly with the FAD trait (lod score = 3.49 at theta = 0.00). The earliest clinical manifestations of the disease relate to deficits in memory function, cognitive processing speed, and attention to complex cognitive sets. These changes occurred in the absence of changes in nonmemory language and visuospatial functions. The neuropathologic features of FAD associated with the APP717 mutation in this family include severe neuronal loss, abundant neurofibrillary tangles, amyloid plaques, and amyloid angiopathy. These results provide independent confirmation that mutations in the APP gene are linked to the FAD trait in some families.
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PMID:Molecular and prospective phenotypic characterization of a pedigree with familial Alzheimer's disease and a missense mutation in codon 717 of the beta-amyloid precursor protein gene. 152 Mar 98

The cytoskeletal pathology of a patient with familial Alzheimer's disease (AD) associated with the probably causal amyloid precursor protein (APP) codon 717 Val----Ile mutation is described. In addition to moderately extensive beta A4 protein deposition within the substance of the brain and in blood vessel walls (congophilic angiopathy), there was abundant cytoskeletal pathology in the form of neurofibrillary tangles, plaque neurites and neuropil threads. Interestingly, plentiful cortical and subcortical Lewy bodies were also seen. In order to compare the cytoskeletal pathology in this case with that seen in sporadic cases of AD we (1) studied the immunohistochemical profile of the amyloid and cytoskeletal pathology with antibodies to beta A4 protein, tau, phosphorylated neurofilament epitopes and ubiquitin and (2) performed a biochemical fractionation and Western blot analysis for the abnormally phosphorylated form of tau (A68) characteristically seen in AD. No substantial difference between the familial case and sporadic cases could be found. We conclude that it is now reasonable to hypothesise that an abnormality in APP metabolism is responsible not only for the deposition of beta A4 protein, but also for the range of cytoskeletal pathology, typical of AD.
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PMID:Familial Alzheimer's disease with the amyloid precursor protein position 717 mutation and sporadic Alzheimer's disease have the same cytoskeletal pathology. 158 63

The fine structure of cerebral amyloid angiopathy, especially in small and presumably early deposits, was examined by immunolabeling of the beta/A4 protein in semithin and ultrathin sections from brains with Alzheimer's disease. The following findings emerged: 1) in large leptomeningeal arteries, small, focal amyloid deposits appear to consist of clusters of delicate (approximately 8 nm diameter) amyloid fibrils, not previously described, in the outermost part of the basement membrane (BM) at the media-adventitia junction; 2) in small leptomeningeal arteries and perforating cortical arterioles, small foci of delicate amyloid fibrils were observed within the BM. They appeared mostly in the outer portion of the BM, around intact smooth muscle cells, rather than in the subendothelial region. In larger and presumably more advanced deposits, coarse amyloid fibrils (approximately 10 nm) occupied the abluminal BM, and adjacent smooth muscle cells showed degeneration; and 3) in capillaries, small amounts of delicate (approximately 8 nm) amyloid fibrils, not previously described, were seen within the BM in the smallest discernible deposits. The BM at these sites was abnormally folded and layered. In larger deposits, amyloid fibrils appeared to extravasate from the outer BM of the capillary into the neuropil and were surrounded by astrocytic foot processes and/or microglia. Our results suggest that vascular amyloid fibrils may first be formed within the abluminal vascular BM, that is, outside of cells. The BM may trap degradative intermediates of the amyloid precursor protein that contain the beta/A4 region, and local proteases may then cleave them further to yield amyloidogenic fragments.
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PMID:Beta amyloid is focally deposited within the outer basement membrane in the amyloid angiopathy of Alzheimer's disease. An immunoelectron microscopic study. 163 66

Spontaneous intracerebral hemorrhages can occur in patients with severe amyloid angiopathy and other morphological signs of Alzheimer's disease (AD). We observed 15 patients in whom histological examination of brain tissue specimens obtained at surgery revealed characteristic congophilic amyloid deposits in subcortical arteries and/or nerve cells. Clinical follow-up examinations were carried out up to 9 years after diagnosis. In addition, three survivors from the operated group were investigated by neuropsychological testing and single photon emission computer tomography (SPECT) using Tc-99m-HMPAO for determination of regional cerebral blood flow (rCBF). SPECT could not differentiate between the "typical Alzheimer disease pattern" of bilateral temporo-parietal rCBF reduction and flow deficits resulting from previous hemorrhage. Intellectual functioning was found to be impaired to various degrees ranging from normal function to severe dementia (MMS test scores varied between 15 and 26 points); again, it was difficult to differentiate clinically between the nosologic entities mentioned above. On the basis of our present experience we cannot distinguish between brain dysfunction due to Alzheimer's disease and intracranial hemorrhage from amyloid angiopathy. This supports the idea that intracranial hemorrhage may only be one clinical manifestation of amyloid deposits, another one being "Alzheimer's disease" with varying preponderance.
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PMID:Clinical and cerebral blood flow studies in patients with intracranial hemorrhage and amyloid angiopathy typical of Alzheimer's disease. 163 24

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D) is an autosomal dominant form of severe cerebrovascular amyloid angiopathy causing recurrent strokes during the fifth and sixth decades of life. The major constituent of the amyloid deposits in HCHWA-D is the amyloid beta-protein (A beta), also found in Alzheimer's disease. A point mutation in the DNA sequence encoding A beta has been found in 2 unrelated patients with HCHWA-D, and an assay detecting the single base change was developed for diagnostic purposes. We describe the detection of the point mutation in a patient living in the United States, suffering from recurring cerebral hemorrhages, who only recently was diagnosed with HCHWA-D. In addition, we tested a number of family members, and found the mutation in 2 additional individuals, one of them too young to exhibit clinical manifestations. This study combined with the study of two other families in Holland indicates that the codon 618 variant in the amyloid precursor protein gene segregates with HCHWA-D.
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PMID:Codon 618 variant of Alzheimer amyloid gene associated with inherited cerebral hemorrhage. 176 98

At the cellular level, Alzheimer's disease (AD) must be the result of neuronal dysfunction and degeneration leading to a reduction in synaptic density. Filamentous deposits of amyloid, which define the disease at the molecular level, occur within perikarya, axons, dendrites, and terminals of neurons as neurofibrillary tangles (NFT), in the extracellular neuropil as amyloid plaques (APC), and around blood vessels as amyloid congophilic angiopathy (ACA). These fibrillar amyloid protein aggregates are also found in the brain of all individuals with Down's syndrome after the age of 30 years. The amyloid deposits apparently occur in the terminal zones of neurons that develop NFT. It is suggested that amyloid deposition is of fundamental significance in AD and that a thorough understanding of amyloid formation will eventually lead to successful therapeutic intervention in AD. As elucidation of the reasons behind amyloid deposition must shed some light on the pathogenesis of AD, we review the current state of knowledge on the nature of the AD amyloid protein, its origin, and its formation. Although there is yet no agreement about the chemical nature of the amyloid protein of NFT, the major constituent of both APC and ACA has been shown to be a 4.5-kD amyloid protein originally termed "beta-protein" or "amyloid A4" which we now denote as "beta A4." Amyloid beta A4 protein is proteolytically derived from a transmembrane protein termed amyloid precursor protein (APP) which is encoded by a widely expressed gene on chromosome 21. Our present results are consistent with the possibility that amyloid formation requires membrane damage or APP molecules that are not or are incorrectly integrated into membranes. To allow the generation of the C-terminus of beta A4, one proteolytic cleavage step has to occur in the sequence that normally forms the transmembrane domain of the APP proteins. This cleavage is crucial for amyloid formation because we could show that the ability of synthetic beta A4 to form amyloid depositions is mainly based on hydrophobic parts of the sequence that have to interact with each other and build up large aggregates under physiologic conditions. Membrane association of APP is expected to interfere with this cleavage and the process of aggregation.
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PMID:Mechanisms of amyloid deposition in Alzheimer's disease. 177 29


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