NIH PubMed latest 20 articles on Alzheimer's amyloid

The Nun Study. Clinically silent AD, neuronal hypertrophy, and linguistic skills in early life.

Iacono D, Markesbery WR, Gross M, Pletnikova O, Rudow G, Zandi P, Troncoso JC

The Nun Study. Clinically silent AD, neuronal hypertrophy, and linguistic skills in early life.

Neurology. 2009 Jul 8;

Authors: Iacono D, Markesbery WR, Gross M, Pletnikova O, Rudow G, Zandi P, Troncoso JC

BACKGROUND: It is common to find substantial Alzheimer disease (AD) lesions, i.e., neuritic beta-amyloid plaques and neurofibrillary tangles, in the autopsied brains of elderly subjects with normal cognition assessed shortly before death. We have termed this status asymptomatic AD (ASYMAD). We assessed the morphologic substrate of ASYMAD compared to mild cognitive impairment (MCI) in subjects from the Nun Study. In addition, possible correlations between linguistic abilities in early life and the presence of AD pathology with and without clinical manifestations in late life were considered. METHODS: Design-based stereology was used to measure the volumes of neuronal cell bodies, nuclei, and nucleoli in the CA1 region of hippocampus (CA1). Four groups of subjects were compared: ASYMAD (n = 10), MCI (n = 5), AD (n = 10), and age-matched controls (n = 13). Linguistic ability assessed in early life was compared among all groups. RESULTS: A significant hypertrophy of the cell bodies (+44.9%), nuclei (+59.7%), and nucleoli (+80.2%) in the CA1 neurons was found in ASYMAD compared with MCI. Similar differences were observed with controls. Furthermore, significant higher idea density scores in early life were observed in controls and ASYMAD group compared to MCI and AD groups. CONCLUSIONS: 1) Neuronal hypertrophy may constitute an early cellular response to Alzheimer disease (AD) pathology or reflect compensatory mechanisms that prevent cognitive impairment despite substantial AD lesions; 2) higher idea density scores in early life are associated with intact cognition in late life despite the presence of AD lesions.

PMID: 19587326 [PubMed - as supplied by publisher]

Conversion of amyloid positive and negative MCI to AD over 3 years. An 11C-PIB PET study.

Conversion of amyloid positive and negative MCI to AD over 3 years. An 11C-PIB PET study.

Neurology. 2009 Jul 8;

Authors: Okello A, Koivunen J, Edison P, Archer HA, Turkheimer FE, Någren K, Bullock R, Walker Z, Kennedy A, Fox NC, Rossor MN, Rinne JO, Brooks DJ

BACKGROUND: Patients with amnestic mild cognitive impairment (MCI) represent an important clinical group as they are at increased risk of developing Alzheimer disease (AD). (11)C-PIB PET is an in vivo marker of brain amyloid load. OBJECTIVE: To assess the rates of conversion of MCI to AD during a 3-year follow-up period and to compare levels of amyloid deposition between MCI converters and nonconverters. METHODS: Thirty-one subjects with MCI with baseline (11)C-PIB PET, MRI, and neuropsychometry have been clinically followed up for 1 to 3 years (2.68 +/- 0.6 years). Raised cortical (11)C-PIB binding in subjects with MCI was detected with region of interest analysis and statistical parametric mapping. RESULTS: Seventeen of 31 (55%) subjects with MCI had increased (11)C-PIB retention at baseline and 14 of these 17 (82%) clinically converted to AD during follow-up. Only one of the 14 PIB-negative MCI cases converted to AD. Of the PIB-positive subjects with MCI, half (47%) converted to AD within 1 year of baseline PIB PET, these faster converters having higher tracer-retention values than slower converters in the anterior cingulate (p = 0.027) and frontal cortex (p = 0.031). Seven of 17 (41%) subjects with MCI with known APOE status were epsilon4 allele carriers, this genotype being associated with faster conversion rates in PIB-positive subjects with MCI (p = 0.035). CONCLUSIONS: PIB-positive subjects with mild cognitive impairment (MCI) are significantly more likely to convert to AD than PIB-negative patients, faster converters having higher PIB retention levels at baseline than slower converters. In vivo detection of amyloid deposition in MCI with PIB PET provides useful prognostic information.

PMID: 19587325 [PubMed - as supplied by publisher]

Matrix metalloprotease-9 inhibition improves amyloid {beta}-mediated cognitive impairment and neurotoxicity in mice.

Matrix metalloprotease-9 inhibition improves amyloid {beta}-mediated cognitive impairment and neurotoxicity in mice.

J Pharmacol Exp Ther. 2009 Jul 8;

Authors: Mizoguchi H, Takuma K, Fukuzaki E, Ibi D, Someya E, Akazawa KH, Alkam T, Tsunekawa H, Mouri A, Noda Y, Nabeshima T, Yamada K

In Alzheimer's disease (AD), the expression of matrix metalloproteases (MMPs), which are capable of degrading extracellular matrix proteins, is increased in the brain. Previous studies with cultured glial cells have demonstrated that amyloid beta (Abeta) protein can induce the expression of MMPs, which could be involved in the degradation of Abeta. In the present study, we investigated the role of MMP-2 and MMP-9 in cognitive impairment induced by the injection of Abeta in mice. The i.c.v. injection of Abeta25-35, Abeta1-40 and Abeta1-42, but not Abeta40-1, transiently increased MMP-9, but not MMP-2, activity and protein expression in the hippocampus. Immunohistochemistry revealed the expression of MMP-9 to be increased in both neurons and glial cells in the hippocampus after Abeta treatment. The Abeta-induced cognitive impairment in vivo as well as neurotoxicity in vitro was significantly alleviated in MMP-9 homozygous knockout mice and by treatment with MMP inhibitors. These results suggest the increase in MMP-9 expression in the hippocampus to be involved in the development of cognitive impairment induced by Abeta1-40. Thus, specific inhibitors of MMP-9 may have therapeutic potential for the treatment of AD. Our findings suggest that, as opposed to expectations based on previous findings, MMP-9 plays a causal role in Abeta-induced cognitive impairment and neurotoxicity.

PMID: 19587312 [PubMed - as supplied by publisher]

Tetraspanin12 regulates ADAM10-dependent cleavage of amyloid precursor protein.

Xu D, Sharma C, Hemler ME

Tetraspanin12 regulates ADAM10-dependent cleavage of amyloid precursor protein.

FASEB J. 2009 Jul 8;

Authors: Xu D, Sharma C, Hemler ME

Using mass spectrometry, we identified ADAM10 (a membrane-associated metalloproteinase) as a partner for TSPAN12, a tetraspanin protein. TSPAN12-ADAM10 interaction was confirmed by reciprocal coimmunoprecipitation in multiple tumor cell lines. TSPAN12, to a greater extent than other tetraspanins (CD81, CD151, CD9, and CD82), associated with ADAM10 but not with ADAM17. Overexpression of TSPAN12 enhanced ADAM10-dependent shedding of amyloid precursor protein (APP) in MCF7 (breast cancer) and SH-SY5Y (neuroblastoma) cell lines. Conversely, siRNA ablation of endogenous TSPAN12 markedly diminished APP proteolysis in both cell lines. Furthermore, TSPAN12 overexpression enhanced ADAM10 prodomain maturation, whereas TSPAN12 ablation diminished ADAM10 maturation. A palmitoylation-deficient TSPAN12 mutant failed to associate with ADAM10, inhibited ADAM10-dependent proteolysis of APP, and inhibited ADAM10 maturation, most likely by interfering with endogenous wild-type TSPAN12. In conclusion, TSPAN12 serves as a novel and robust partner for ADAM10 and promotes ADAM10 maturation, thereby facilitating ADAM10-dependent proteolysis of APP. This novel mode of regulating APP cleavage is of relevance to Alzheimer's disease therapy.-Xu, D., Sharma, C., Hemler, M. E. Tetraspanin12 regulates ADAM10-dependent cleavage of amyloid precursor protein.

PMID: 19587294 [PubMed - as supplied by publisher]

Deletion of the alpha7 nicotinic acetylcholine receptor gene improves cognitive deficits and synaptic pathology in a mouse model of Alzheimer's disease.

Dziewczapolski G, Glogowski CM, Masliah E, Heinemann SF

Deletion of the alpha7 nicotinic acetylcholine receptor gene improves cognitive deficits and synaptic pathology in a mouse model of Alzheimer's disease.

J Neurosci. 2009 Jul 8;29(27):8805-15

Authors: Dziewczapolski G, Glogowski CM, Masliah E, Heinemann SF

It has been recently shown that the Alzheimer's disease (AD) pathogenic peptide amyloid beta(1-42) (Abeta(1-42)) binds to the alpha7 nicotinic acetylcholine receptor (alpha7nAChR) with high affinity and the alpha7nAChR and Abeta(1-42) are both found colocalized in neuritic plaques of human brains with AD. Moreover, the intraneuronal accumulation of Abeta(1-42) was shown to be facilitated by its high-affinity binding to the alpha7nAChR, and alpha7nAChR activation mediates Abeta-induced tau protein phosphorylation. To test the hypothesis that alpha7nAChRs are involved in AD pathogenesis, we used a transgenic mouse model of AD overexpressing a mutated form of the human amyloid precursor protein (APP) and lacking the alpha7nAChR gene (APPalpha7KO). We have shown that, despite the presence of high amounts of APP and amyloid deposits, deleting the alpha7nAChR subunit in the mouse model of AD leads to a protection from the dysfunction in synaptic integrity (pathology and plasticity) and learning and memory behavior. Specifically, APPalpha7KO mice express APP and Abeta at levels similar to APP mice, and yet they were able to solve a cognitive challenge such as the Morris water maze test significantly better than APP, with performances comparable to control groups. Moreover, deleting the alpha7nAChR subunit protected the brain from loss of the synaptic markers synaptophysin and MAP2, reduced the gliosis, and preserved the capacity to elicit long-term potentiation otherwise deficient in APP mice. These results are consistent with the hypothesis that the alpha7nAChR plays a role in AD and suggest that interrupting alpha7nAChR function could be beneficial in the treatment of AD.

PMID: 19587288 [PubMed - in process]

Tricyclic pyrone compounds prevent aggregation and reverse cellular phenotypes caused by expression of mutant huntingtin protein in striatal neurons.

Trushina E, Rana S, McMurray CT, Hua DH

Tricyclic pyrone compounds prevent aggregation and reverse cellular phenotypes caused by expression of mutant huntingtin protein in striatal neurons.

BMC Neurosci. 2009 Jul 8;10(1):73

Authors: Trushina E, Rana S, McMurray CT, Hua DH

ABSTRACT: BACKGROUND: Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion mutation in the coding region of a novel gene. The mechanism of HD is unknown. Most data suggest that polyglutamine-mediated aggregation associated with expression of mutant huntingtin protein (mhtt) contributes to the pathology. However, recent studies have identified early cellular dysfunctions that preclude aggregate formation. Suppression of aggregation is accepted as one of the markers of successful therapeutic approaches. Previously, we demonstrated that tricyclic pyrone (TP) compounds efficiently inhibited formation of amyloid-beta (Abeta) aggregates in cell and mouse models representing Alzheimer's Disease (AD). In the present study, we aimed to determine whether TP compounds could prevent aggregation and restore early cellular defects in primary embryonic striatal neurons from animal model representing HD. RESULTS: TP compounds effectively inhibit aggregation caused by mhtt in neurons and glial cells. Treatment with TP compounds also alleviated cholesterol accumulation and restored clathrin-independent endocytosis in HD neurons. CONCLUSIONS: We have found that TP compounds not only blocked mhtt-induced aggregation, but also alleviated early cellular dysfunctions that preclude aggregate formation. Our data suggest TP molecules may be used as lead compounds for prevention or treatment of multiple neurodegenerative diseases including HD and AD.

PMID: 19586540 [PubMed - as supplied by publisher]

Structural neuroimaging in Altheimer's disease: do white matter hyperintensities matter?

Brickman AM, Muraskin J, Zimmerman ME

Structural neuroimaging in Altheimer's disease: do white matter hyperintensities matter?

Dialogues Clin Neurosci. 2009;11(2):181-90

Authors: Brickman AM, Muraskin J, Zimmerman ME

The targeted brain dysfunction that accompanies aging can have a devastating effect on cognitive and intellectual abilities. A significant proportion of older adults experience precipitous cognitive decline that negatively impacts functional activities. Such individuals meet clinical diagnostic criteria for dementia, which is commonly attributed to Alzheimer's disease (AD). Structural neuroimaging, including magnetic resonance imaging (MRI), has contributed significantly to our understanding of the morphological and pathology-related changes that may underlie normal and disease-associated cognitive change in aging. White matter hyperintensities (WMH), which are distributed patches of increased hyperintense signal on T2-weighted MRI, are among the most common structural neuroimaging findings in older adults. In recent years, WMH have emerged as robust radiological correlates of cognitive decline. Studies suggest that WMH distributed in anterior brain regions are related to decline in executive abilities that is typical of normal aging, whereas WMH distributed in more posterior brain regions are common in AD. Although epidemiological, observational, and pathological studies suggest that WMH may be ischemic in origin and caused by consistent or variable hypoperfusion, there is emerging evidence that they may also reflect vascular deposition of beta-amyloid, particularly when they are distributed in posterior areas and are present in patients with AD. Findings from the literature highlight the potential contribution of small-vessel cerebrovascular disease to the pathogenesis of AD, and suggest a mechanistic interaction, but future longitudinal studies using multiple imaging modalities are required to fully understand the complex role of WMH in AD.

PMID: 19585953 [PubMed - in process]

Mechanism-based treatments for Alzheimer's disease.

Davies P, Koppel J

Mechanism-based treatments for Alzheimer's disease.

Dialogues Clin Neurosci. 2009;11(2):159-69

Authors: Davies P, Koppel J

Treatment for Alzheimer's disease is entering a new and exciting phase, with several new drugs beginning clinical trials. Many of these new therapies are based on our best current understanding of the pathogenesis of Alzheimer's disease, and are designed to try to either slow or halt the progression of the disease. There are several different theories underlying the current efforts, and these are briefly reviewed. Therapies directed against some aspect of beta-amyloid formation, against neurofibrillary tangle formation and against the inflammatory response are all considered, as are the problems associated with each area. It is as yet unclear which, if any, of these approaches will be successful, but the high level of activity in each of these three fields provides some hope that an effective treatment for Alzheimer's disease is on the horizon.

PMID: 19585951 [PubMed - in process]

Amyloid imaging with PET: methodological issues and correlative studies.

Lucignani G

Amyloid imaging with PET: methodological issues and correlative studies.

Eur J Nucl Med Mol Imaging. 2009 Jun;36(6):1009-14

Authors: Lucignani G

PMID: 19319525 [PubMed - indexed for MEDLINE]