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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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Inhibition of Amyloid beta Protein Fibrillation by Polymeric Nanoparticles
- 2008
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 130:46, s. 15437-15443
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Tidskriftsartikel (refereegranskat)abstract
- Copolymeric NiPAM:BAM nanoparticles of varying hydrophobicity were found to retard fibrillation of the Alzheimer's disease-associated amyloid beta protein (A beta). We found that these nanoparticles affect mainly the nucleation step of A beta fibrillation. The elongation step is largely unaffected by the particles, and once the M is nucleated, the fibrillation process occurs with the same rate as in the absence of nanoparticles. The extension of the lag phase for fibrillation of A beta is strongly dependent on both the amount and surface character of the nanoparticles. Surface plasmon resonance studies show that A beta binds to the nanoparticles and provide rate and equilibrium constants for the interaction. Numerical analysis of the kinetic data for fibrillation suggests that binding of monomeric A beta and prefibrillar oligomers to the nanoparticles prevents fibrillation. Moreover, we find that fibrillation of A beta initiated in the absence of nanoparticles can be reversed by addition of nanoparticles up to a particular time point before mature fibrils appear.
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| 4. |
- Hampel, Harald, et al.
(författare)
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Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.
- 2010
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Ingår i: Experimental neurology. - : Elsevier BV. - 1090-2430 .- 0014-4886. ; 223:2, s. 334-46
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Forskningsöversikt (refereegranskat)abstract
- Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer's disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.
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- O'Dowd, Seán T, et al.
(författare)
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The ELISA-Measured Increase in Cerebrospinal Fluid Tau that Discriminates Alzheimer's Disease from other Neurodegenerative Disorders is not Attributable to Differential Recognition of Tau Assembly Forms.
- 2013
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908. ; 33:4, s. 923-928
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Tidskriftsartikel (refereegranskat)abstract
- Elevated cerebrospinal fluid concentrations of tau discriminate Alzheimer's disease from other neurodegenerative conditions. The reasons for this are unclear. While commercial assay kits are widely used to determine total-tau concentrations, little is known about their ability to detect different aggregation states of tau. We demonstrate that the leading commercial enzyme-linked immunosorbent assay reliably detects aggregated and monomeric tau and evinces good recovery of both species when added into cerebrospinal fluid. Hence, the disparity between total-tau levels encountered in Alzheimer's disease and other neurodegenerative conditions is not due to differential recognition of tau assembly forms or the extent of degeneration.
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| 6. |
- O'Malley, Tiernan T., et al.
(författare)
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The Aggregation Paths and Products of Aβ42 Dimers Are Distinct from Those of the Aβ42 Monomer
- 2016
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 55:44, s. 6150-6161
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Tidskriftsartikel (refereegranskat)abstract
- Extracts of Alzheimer's disease (AD) brain that contain what appear to be sodium dodecyl sulfate-stable amyloid β-protein (Aβ) dimers potently block LTP and impair memory consolidation. Brain-derived dimers can be physically separated the Aβ monomer, consist primarily of Aβ42, and resist denaturation by chaotropic agents. In nature, covalently cross-linked Aβ dimers could be generated in two ways: by the formation of a dityrosine (DiY) or an isopeptide ϵ-(γ-glutamyl)-lysine (Q-K) bond. We enzymatically cross-linked recombinant Aβ42 monomer to produce DiY and Q-K dimers and then used a range of biophysical methods to study their aggregation. Both Q-K and DiY dimers aggregate to form soluble assemblies distinct from the fibrillar aggregates formed by the Aβ monomer. The results suggest that the cross-links disfavor fibril formation from Aβ dimers, thereby enhancing the concentration of soluble aggregates akin to those in aqueous extracts of AD brain. Thus, it seems that Aβ dimers may play an important role in determining the formation of soluble rather than insoluble aggregates.
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| 7. |
- Walsh, Dominic M., et al.
(författare)
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A facile method for expression and purification of the Alzheimer's disease-associated amyloid beta-peptide
- 2009
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X. ; 276:5, s. 1266-1281
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Tidskriftsartikel (refereegranskat)abstract
- We report the development of a high-level bacterial expression system for the Alzheimer's disease-associated amyloid beta-peptide (A beta), together with a scaleable and inexpensive purification procedure. A beta(1-40) and A beta(1-42) coding sequences together with added ATG codons were cloned directly into a Pet vector to facilitate production of Met-A beta(1-40) and Met-A beta(1-42), referred to as A beta(M1-40) and A beta(M1-42), respectively. The expression sequences were designed using codons preferred by Escherichia coli, and the two peptides were expressed in this host in inclusion bodies. Peptides were purified from inclusion bodies using a combination of anion-exchange chromatography and centrifugal filtration. The method described requires little specialized equipment and provides a facile and inexpensive procedure for production of large amounts of very pure A beta peptides. Recombinant peptides generated using this protocol produced amyloid fibrils that were indistinguishable from those formed by chemically synthesized A beta 1-40 and A beta 1-42. Formation of fibrils by all peptides was concentration-dependent, and exhibited kinetics typical of a nucleation-dependent polymerization reaction. Recombinant and synthetic peptides exhibited a similar toxic effect on hippocampal neurons, with acute treatment causing inhibition of MTT reduction, and chronic treatment resulting in neuritic degeneration and cell loss.
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| 8. |
- Englund, Hillevi, 1980-
(författare)
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Soluble amyloid-β aggregates in Alzheimer’s disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soluble oligomeric aggregates of the amyloid-β (Aβ) peptide are suggested to initiate Alzheimer's disease (AD), leading to impaired synapse signalling, widespread neuronal death and loss of cognitive functions. These aggregates seem tightly linked to disease progression, and have therefore gained much attention as potential novel disease markers. In this thesis soluble oligomeric Aβ aggregates in general, and the Aβ protofibril species in particular, have been investigated with the aim to quantify and determine their role in AD pathogenesis. Sandwich-ELISAs specifically measuring Aβ42 peptides are widely used both in AD research and as complements for clinical diagnosis. Here it was demonstrated that presence of soluble Aβ aggregates disturbs such analyses, making it difficult to interpret the results. This discovery was made through analyses of samples from cell- and mouse models carrying the AD causing 'Arctic' APP mutation. When analyzed by ELISA, Aβ42 levels were reduced in Arctic samples, in contrast to levels measured by denaturing SDS-PAGE Western blot. The same divergence in Aβ42-levels between analyses was observed in CSF samples from Down syndrome infants. The discrepancy between methods was hypothesized to be due to presence of soluble Aβ aggregates leading to impaired ELISA detection caused by epitope masking. This was confirmed by developing a protofibril specific ELISA, by which samples from Arctic cell- and mouse models were demonstrated to have enhanced Aβ protofibril levels. AD patients have reduced ELISA-measured Aβ42-levels in CSF compared to healthy controls. To test if this reduction was due to oligomeric Aβ species present in AD CSF, Aβ42-levels were analyzed under both denaturing and non-denaturing conditions. These two measures were combined and an Aβ42 oligomer ratio established. Higher ratios were found in AD patients than healthy controls, implying that Aβ oligomers are present in CSF during Alzheimer pathogenesis. The observations from AD patients and young Down syndrome individuals suggest that Aβ42 oligomer formation is an early mechanism of AD pathogenesis, which potentially could be used as a biomarker to monitor disease development.
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| 9. |
- Hellstrand, Erik, et al.
(författare)
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Amyloid beta-Protein Aggregation Produces Highly Reproducible Kinetic Data and Occurs by a Two-Phase Process
- 2010
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Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 1:1, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- Protein aggregation can lead to major disturbances of cellular processes and is associated with several diseases. We report kinetic and equilibrium data by ThT fluorescence and enzyme-linked immunosorbent assay of sufficient quality and reproducibility to form a basis for mechanistic understanding of amyloid beta-peptide (A beta) fibril formation. Starting from monomeric peptide in a pure buffer system without cosolvents, we find that the kinetics of A beta aggregation vary strongly with peptide concentration in a highly predictable manner. The free A beta concentration in equilibrium with fibrils was found to vary with total peptide concentration in a manner expected for a two-phase system. The free versus total A beta concentration was linear up to ca. 0.2,mu M, after which free A beta decreased with total A beta toward an asymptotic value. Our results imply that A beta fibril formation arises from a sequence of events in a highly predictable manner.
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| 10. |
- Klyubin, Igor, et al.
(författare)
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Amyloid beta protein dimer-containing human CSF disrupts synaptic plasticity: prevention by systemic passive immunization.
- 2008
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Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 28:16, s. 4231-7
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Tidskriftsartikel (refereegranskat)abstract
- The current development of immunotherapy for Alzheimer's disease is based on the assumption that human-derived amyloid beta protein (Abeta) can be targeted in a similar manner to animal cell-derived or synthetic Abeta. Because the structure of Abeta depends on its source and the presence of cofactors, it is of great interest to determine whether human-derived oligomeric Abeta species impair brain function and, if so, whether or not their disruptive effects can be prevented using antibodies. We report that untreated ex vivo human CSF that contains Abeta dimers rapidly inhibits hippocampal long-term potentiation in vivo and that acute systemic infusion of an anti-Abeta monoclonal antibody can prevent this disruption of synaptic plasticity. Abeta monomer isolated from human CSF did not affect long-term potentiation. These results strongly support a strategy of passive immunization against soluble Abeta oligomers in early Alzheimer's disease.
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