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Query: UMLS:C0233794 (memory impairment)
 7,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transgenic mice for the human amyloid precursor protein 695 (APP695) isoform may provide an animal model of Alzheimer's disease (AD). To evaluate this, the spatial learning abilities of transgenic and wild strain mice were compared in the Morris water maze task. The transgenic mice were significantly retarded in initial learning and in learning a new escape location, although in each case they eventually reached control levels. The transgenic mice also showed slower swimming speed and reduced nocturnal activity, which may contribute to their deficit in spatial learning. Preliminary neuropathological investigations failed to reveal amyloid depositions. Thus, a gene dosage effect of APP695 may account for the memory impairment but not the plaque formation associated with AD.
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PMID:Transgenic mice for the amyloid precursor protein 695 isoform have impaired spatial memory. 168 63

Alzheimer disease is a common neurodegenerative disorder consisting of memory impairment and intellectual function that produces not only profound disabilities in the patient, but a significant cost to society as well. The biochemical basis for Alzheimer disease is not completely understood, but both positron-emission tomography and single-photon-emission computed tomography provide insights into the in vivo biochemistry associated with this disease. Both techniques show characteristic brain abnormalities, which consist of reductions in temporal-parietal metabolism that progress in severity and extent as the disease itself shows clinical progression. Such noninvasive biochemical assays may ultimately prove to be of assistance in clinical management, and are clearly helpful in understanding the pathophysiologic mechanisms associated with the production of this disease.
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PMID:Functional brain imaging and Alzheimer-type dementia. 178 64

Amyloid beta-protein (A beta), the major protein of cerebrovascular and plaque amyloid in Alzheimer disease, is considered a primary factor in the pathology of this disease. The effect of synthetic A beta (1-40) on the activity of protein kinase C (PKC) was studied with histones for a substrate in a mixed micellar assay, and with calmodulin-depleted soluble brain proteins in a liposomal system. We report here that A beta affects PKC activity in a biphasic manner. An initial stimulation of PKC was noted at low concentrations of A beta (less than 2.5 microM); while PKC-inhibition was observed in a concentration-dependent manner at higher concentrations of A beta. The in vitro phosphorylation of 20, 47, and 87 kDa brain proteins (known PKC substrates) was significantly reduced by 60 microM A beta. The role of 20 kDa in memory storage, of 87 kDa in neurotransmission and neurosecretory processes, and of 47 kDa in long-term potentiation or memory is well recognized, and A beta is known to have both neurotrophic and neurotoxic effects. Since PKC plays an important role in neuronal function, it is suggested that dual modulation of PKC by A beta may be linked to its neurotrophic and neurotoxic effects. We propose that at low concentrations A beta, by stimulating PKC, may contribute to neurites generation; and at higher concentrations A beta, by inhibiting PKC activity, might lead first to memory impairment, and then to neuronal loss.
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PMID:Action of amyloid beta-protein on protein kinase C activity. 194 60

In the primate brain, there are strong connections among the entorhinal cortex, the hippocampal formation, and the amygdala, 3 structures of the ventromedial temporal lobe that are related to memory function. Because memory impairment is a central feature of Alzheimer's disease, we examined the probable cells of origin and terminal zones of these connections in the brains of humans affected by the disease, using thioflavine S, Alz-50, and anti-A4 amyloid protein immunocytochemistry. Specific cytoarchitectural areas and lamina that give rise to projections from the entorhinal cortex, the hippocampal formation, and the amygdala consistently contained neurofibrillary tangles. The terminal zones of many of these projections contained neuritic plaques, Alz-50-positive neuritic alterations, and A4 deposition. Other cytoarchitectural areas and lamina, sometimes immediately adjacent, were consistently spared from these Alzheimer changes. This pattern of Alzheimer-related alterations would disrupt projections among the entorhinal cortex, hippocampal formation, and amygdala at multiple sites, and also disrupt projections between these structures and cortical and subcortical targets. In functional terms, this pattern of structural damage is likely to be as devastating as bilateral destruction of the ventromedial temporal lobe, and thus contribute substantially to the memory disorder seen in this condition.
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PMID:Memory-related neural systems in Alzheimer's disease: an anatomic study. 223 28

The memory dysfunction of Alzheimer disease has been associated with a cortical cholinergic deficiency and loss of cholinergic neurons of the nucleus basalis of Meynert. This cholinergic component of Alzheimer disease can be modeled in the rat by ibotenic acid lesions of the cholinergic nucleus basalis magnocellularis. The memory impairment caused by such unilateral lesions, as reflected in passive avoidance behavior, is reversed by grafts into the deafferented neocortex of embryonic neurons of the cholinergic ventral forebrain, but not by grafts of noncholinergic hippocampal cells.
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PMID:Cholinergic ventral forebrain grafts into the neocortex improve passive avoidance memory in a rat model of Alzheimer disease. 386 Aug 57

Alzheimer's disease (AD) is characterized by the presence of senile plaques. The core of the plaque consists of beta-amyloid protein. In AD patients, learning and memory are impaired with a concomitant loss of the cholinergic marker enzyme, choline acetyltransferase (ChAT). However, direct evidence that beta-amyloid protein is related to the impairment of learning and memory has not been demonstrated. In this study, we investigated whether memory impairment and neuronal dysfunction were produced after 2 weeks continuous infusion of beta-amyloid protein (3, 30 and 300 pmol/day) into the cerebral ventricles in adult rats. To investigate the ability of learning and memory in beta-amyloid protein-treated rats, water maze and passive avoidance tasks were carried out. The performance of both tasks in beta-amyloid protein-treated rats was impaired. ChAT activity in the frontal cortex (3 and 30 pmol/day) and hippocampus (300 pmol/day) significantly decreased. These results suggest that beta-amyloid protein is related to the impairment of learning and memory, and neurodegeneration, and that beta-amyloid protein-treated rats could be used as an animal model for AD.
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PMID:Memory impairment and neuronal dysfunction induced by beta-amyloid protein in rats. 776 89

The beta-amyloid precursor protein (beta-APP), from which the beta-A4 peptide is derived, is considered to be central to the pathogenesis of Alzheimer disease (AD). Transgenic mice expressing the 751-amino acid isoform of human beta-APP (beta-APP751) have been shown to develop early AD-like histopathology with diffuse deposits of beta-A4 and aberrant tau protein expression in the brain, particularly in the hippocampus, cortex, and amygdala. We now report that beta-APP751 transgenic mice exhibit age-dependent deficits in spatial learning in a water-maze task and in spontaneous alternation in a Y maze. These deficits were mild or absent in 6-month-old transgenic mice but were severe in 12-month-old transgenic mice compared to age-matched wild-type control mice. No other behavioral abnormalities were observed. These mice therefore model the progressive learning and memory impairment that is a cardinal feature of AD. These results provide evidence for a relationship between abnormal expression of beta-APP and cognitive impairments.
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PMID:Age-related learning deficits in transgenic mice expressing the 751-amino acid isoform of human beta-amyloid precursor protein. 777 9

Early onset Familial Alzheimer's Disease (FAD) is an autosomal dominant disease with apparent complete penetrance. It is genetically heterogeneous with some families carrying mutations in the amyloid precursor protein (APP) gene which segregate with the disease. In addition, there is allelic heterogeneity with four mutations associated with FAD. Three mutations have been reported at APP 717, just distal to the C-terminus of the beta-amyloid domain, APP 717 val-ile, APP 717 val-phe, and APP 717 val-gly, which are associated with autopsy-proven Alzheimer's disease (AD). APP 670/671 lies at the N terminus of the beta-amyloid domain and is associated with clinically diagnosed FAD in two Swedish families. FAD tends to have prominent myoclonus and this is shared by the cases with APP mutations. In two unrelated UK families with APP 717 val-ile mutations there was early prominent memory impairment with dyscalculia proceeding to generalized cognitive impairment with a lack of insight. There was a late development of a gait disturbance with extrapyramidal features in some members. Positron emission tomography (PET) with fluorodeoxyglucose demonstrated posterior bitemporal biparietal hypometabolism in one case. Magnetic resonance imaging (MRI) showed generalized cerebral atrophy particularly affecting the temporal lobes and hippocampus. At autopsy, a single case showed extensive beta-amyloid deposition with congophilic angiopathy and widespread senile plaques and neurofibrillary tangles. The cytoskeletal pathology associated with abnormally phosphorylated tau was similar to cases of sporadic AD. In addition, there were widespread cortical and subcortical Lewy bodies. A single family with the APP 717 val-gly mutation also showed prominent myoclonus, lack of insight, and seizures, PET, in a single case, showed classical biparietal bitemporal hypometabolism. Autopsy, in a single case, showed diffuse deposits of beta-amyloid throughout the cortex with frequent neuritic plaques and neurofibrillary tangles. No other inclusion bodies were seen. There was severe congophilic angiopathy. The age at onset of APP mutations is around 50 years of age by contrast to other early onset FAD pedigrees.
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PMID:Alzheimer's disease families with amyloid precursor protein mutations. 823 83

Blood from patients diagnosed as having Alzheimer disease and from subjects without memory impairment or dementia was collected in citrate. The erythrocytes were washed and electrophoresed in phosphate-buffered saline as well as in a number of polymer solutions in phosphate-buffered saline. The electrophoretic mobilities of red cells from Alzheimer patients and from normals were indistinguishable when measured in phosphate-buffered saline. In the dextran-rich bottom phase obtained from a dextran-poly(ethylene glycol) aqueous phase system, but not in a dextran solution alone, the electrophoretic mobilities differ (P < 0.001). In a poly(ethylene glycol) solution the mobilities also differ although, on a percentage basis, less so than in the bottom phase. It would appear that a differential adsorption of appropriately selected polymer(s) on the Alzheimer and normal red blood cells renders surface differences electrophoretically detectable.
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PMID:Red blood cells from Alzheimer patients and from normal subjects discerned by cell electrophoresis in an aqueous polymer solution. 833 37

Alzheimer's disease is histopathologically characterized by neurofibrillary tangles, formed by the abnormally high phosphorylated tau protein, and senile plaques which largely consist of the beta/A4-amyloid peptide. Metabolism of the amyloid precursor protein and its processing into beta/A4-amyloid is regulated by protein phosphorylation. Thus, an imbalance between protein phosphorylation and dephosphorylation might be crucial for the development of the molecular hallmarks of Alzheimer's disease. We report here that chronic infusion into rat brain ventricles of okadaic acid, a specific inhibitor of the serine/threonine protein phosphatases 1 and 2A, results in a severe memory impairment, accompanied by a paired helical filament-like phosphorylation of tau protein and the formation of beta/A4-amyloid containing plaque-like structures in gray and white matter areas.
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PMID:Paired helical filament-like phosphorylation of tau, deposition of beta/A4-amyloid and memory impairment in rat induced by chronic inhibition of phosphatase 1 and 2A. 859 39


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