Methods for analysis of amyloid-beta aggregates.

Item does not contain fulltextAmyloid-beta protein (Abeta) accumulation is one of the major hallmarks of Alzheimer's disease and plays a crucial role in its pathogenesis. Abeta aggregates into fibrils, but rather than these end-products of the aggregation process, intermediate species, referred to as oligomers, have been identified as the most neurotoxic Abeta aggregates. To characterize the different Abeta species and to study the aggregation process, a wide range of techniques has been applied over the past years. These techniques aim to visualize the different Abeta species and study their structure, to separate them, and to quantify the aggregated Abeta forms by immunology-based methods. In this review, we provide an overview and discussion of the most important techniques used for these aims. Often a combination of techniques will be appropriate to obtain the most optimal information

Methods for analysis of amyloid-beta aggregates.

Item does not contain fulltextAmyloid-beta protein (Abeta) accumulation is one of the major hallmarks of Alzheimer's disease and plays a crucial role in its pathogenesis. Abeta aggregates into fibrils, but rather than these end-products of the aggregation process, intermediate species, referred to as oligomers, have been identified as the most neurotoxic Abeta aggregates. To characterize the different Abeta species and to study the aggregation process, a wide range of techniques has been applied over the past years. These techniques aim to visualize the different Abeta species and study their structure, to separate them, and to quantify the aggregated Abeta forms by immunology-based methods. In this review, we provide an overview and discussion of the most important techniques used for these aims. Often a combination of techniques will be appropriate to obtain the most optimal information

The Diagnostic Value of CSF Amyloid-beta43 in Differentiation of Dementia Syndromes

Item does not contain fulltextAmyloid-beta (Abeta) is known as the most prominent core protein in Alzheimer's Disease (AD) senile plaques. Although research has focused mainly on Abeta40 and Abeta42 as potential cerebrospinal fluid (CSF) biomarkers, a range of Abeta peptides with variable lengths has been demonstrated in the brains and CSF of AD patients. Recently, it has been found that the Abeta43 peptide may be more abundant than previously assumed, could therefore play an important role in AD pathophysiology, and hence also function as putative biomarker. In this study the value of CSF Abeta43 in AD diagnosis was investigated. Abeta43 levels in CSF were highly correlated with Abeta42 levels. Furthermore, in differentiation of AD from nondemented controls and from patients with Lewy body dementia and frontotemporal dementia, Abeta43 had an equal diagnostic value as Abeta42, both as a single biomarker and in combination with total and phosphorylated tau. In conclusion, quantification of Abeta43 in CSF does not add novel diagnostic information to the differential diagnosis of AD compared to existing biomarkers

Detection of elevated levels of alpha-synuclein oligomers in CSF from patients with Parkinson disease

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Amyloid-beta oligomer detection by ELISA in cerebrospinal fluid and brain tissue

Item does not contain fulltextAmyloid-beta (Abeta) deposits are important pathological hallmarks of Alzheimer's disease (AD). Abeta aggregates into fibrils; however, the intermediate oligomers are believed to be the most neurotoxic species and, therefore, are of great interest as potential biomarkers. Here, we have developed an enzyme-linked immunosorbent assay (ELISA) specific for Abeta oligomers by using the same capture and (labeled) detection antibody. The ELISA predominantly recognizes relatively small oligomers (10-25 kDa) and not monomers. In brain tissue of APP/PS1 transgenic mice, we found that Abeta oligomer levels increase with age. However, for measurements in human samples, pretreatment to remove human anti-mouse antibodies (HAMAs) was required. In HAMA-depleted human hippocampal extracts, the Abeta oligomer concentration was significantly increased in AD compared with nondemented controls. Abeta oligomer levels could also be quantified in pretreated cerebrospinal fluid (CSF) samples; however, no difference was detected between AD and control groups. Our data suggest that levels of small oligomers might not be suitable as biomarkers for AD. In addition, we demonstrate the importance of avoiding HAMA interference in assays to quantify Abeta oligomers in human body fluids

Football et relations internationales - 2002 FIFA World Cup. Korea / Japan : que la fête recommence !

Amyloid-beta (Abeta) is the most prominent protein in Alzheimer's disease (AD) senile plaques. In addition, Abeta interacts with a variety of Abeta-associated proteins (AAPs), some of which can form complexes with Abeta and influence its clearance, aggregation or toxicity. Identification of novel AAPs may shed new light on the pathophysiology of AD and the metabolic fate of Abeta. In this study, we aimed to identify new AAPs by searching for proteins that may form soluble complexes with Abeta in CSF, using a proteomics approach. We identified the secreted Wnt pathway protein Dickkopf-related protein 3 (Dkk-3) as a potential Abeta-associated protein. Using immunohistochemistry on human AD brain tissue, we observed that (i) Dkk-3 co-localizes with Abeta in the brain, both in diffuse and classic plaques. (ii) Dkk-3 is expressed in neurons and in blood vessel walls in the brain and (iii) is secreted by leptomeningeal smooth muscle cells in vitro. Finally, measurements using ELISA revealed that (iv) Dkk-3 protein is abundantly present in both cerebrospinal fluid and serum, but its levels are similar in non-demented controls and patients with AD, Lewy body dementia, and frontotemporal dementia. Our study demonstrates that Dkk-3 is a hitherto unidentified Abeta-associated protein which, given its relatively high cerebral concentrations and co-localization with Abeta, is potentially involved in AD pathology. In this study, we propose that Dickkopf-related protein-3 (Dkk-3) might be a novel Amyloid-beta (Abeta) associated protein. We demonstrate that Dkk-3 is expressed in the brain, especially in vessel walls, and co-localizes with Abeta in senile plaques. Furthermore, Dkk-3 levels in cerebrospinal fluid strongly correlate with Abeta40 levels, but were not suitable to discriminate non-demented controls and patients with dementia

Amyloid-beta Oligomers Relate to Cognitive Decline in Alzheimer's Disease

Item does not contain fulltextBACKGROUND: Amyloid-beta (Abeta)-oligomers are neurotoxic isoforms of Abeta and are a potential diagnostic biomarker for Alzheimer's disease (AD). OBJECTIVES: 1) Analyze the potential of Abeta-oligomer concentrations in cerebrospinal fluid (CSF) to diagnose and predict progression to AD in a large clinical study sample. 2) Monitor Abeta-oligomer concentrations over-time, both in early and advanced stages of AD. 3) Examine the relation between Abeta-oligomer levels in CSF and cognitive functioning. METHODS: 24 non-demented, 61 mild cognitive impairment (MCI), and 64 AD patients who underwent lumbar puncture and cognitive testing at baseline and follow-up were selected from the memory clinic based Amsterdam Dementia Cohort. CSF samples were analyzed for standard AD-biomarkers and Abeta-oligomer levels using a validated in-house Abeta-oligomer specific enzyme-linked immunosorbent assay. Abeta-oligomer levels were analyzed as indicators of disease progression (follow-up AD diagnosis) and cognitive decline, respectively. RESULTS: Patient groups did not differ in Abeta-oligomer concentrations at baseline or follow-up. Baseline CSF Abeta-oligomer levels were similar in MCI patients that develop AD as in stable MCI patients. MCI and AD patients showed an annual decrease in Abeta-oligomer levels of 9.4% and 6.8%, respectively. A decrease in Abeta-oligomer levels over time was strongly associated with more severe cognitive decline in AD patients. CONCLUSION: Despite the limited diagnostic potential of Abeta-oligomer levels in CSF to differentiate between patient groups, and between MCI-AD and MCI-stable patients, changes in CSF Abeta-oligomer levels were related to cognitive decline. Therefore, CSF Abeta-oligomers may aid in the selection of patients with a more aggressive disease course

A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee

Many clinical trials have evaluated the benefit of long-term use of antiplatelet drugs in reducing the risk of clinical thrombotic events. Aspirin and ticlopidine have been shown to be effective, but both have potentially serious adverse effects. Clopidogrel, a new thienopyridine derivative similar to ticlopidine, is an inhibitor of platelet aggregation induced by adenosine diphosphate. METHODS: CAPRIE was a randomised, blinded, international trial designed to assess the relative efficacy of clopidogrel (75 mg once daily) and aspirin (325 mg once daily) in reducing the risk of a composite outcome cluster of ischaemic stroke, myocardial infarction, or vascular death; their relative safety was also assessed. The population studied comprised subgroups of patients with atherosclerotic vascular disease manifested as either recent ischaemic stroke, recent myocardial infarction, or symptomatic peripheral arterial disease. Patients were followed for 1 to 3 years. FINDINGS: 19,185 patients, with more than 6300 in each of the clinical subgroups, were recruited over 3 years, with a mean follow-up of 1.91 years. There were 1960 first events included in the outcome cluster on which an intention-to-treat analysis showed that patients treated with clopidogrel had an annual 5.32% risk of ischaemic stroke, myocardial infarction, or vascular death compared with 5.83% with aspirin. These rates reflect a statistically significant (p = 0.043) relative-risk reduction of 8.7% in favour of clopidogrel (95% Cl 0.3-16.5). Corresponding on-treatment analysis yielded a relative-risk reduction of 9.4%. There were no major differences in terms of safety. Reported adverse experiences in the clopidogrel and aspirin groups judged to be severe included rash (0.26% vs 0.10%), diarrhoea (0.23% vs 0.11%), upper gastrointestinal discomfort (0.97% vs 1.22%), intracranial haemorrhage (0.33% vs 0.47%), and gastrointestinal haemorrhage (0.52% vs 0.72%), respectively. There were ten (0.10%) patients in the clopidogrel group with significant reductions in neutrophils (< 1.2 x 10(9)/L) and 16 (0.17%) in the aspirin group. INTERPRETATION: Long-term administration of clopidogrel to patients with atherosclerotic vascular disease is more effective than aspirin in reducing the combined risk of ischaemic stroke, myocardial infarction, or vascular death. The overall safety profile of clopidogrel is at least as good as that of medium-dose aspirin