Exploring new biological functions of amyloids: bacteria cell agglutination mediated by host protein aggregation.

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Marc Torrent

Full Text Available Antimicrobial proteins and peptides (AMPs are important effectors of the innate immune system that play a vital role in the prevention of infections. Recent advances have highlighted the similarity between AMPs and amyloid proteins. Using the Eosinophil Cationic Protein as a model, we have rationalized the structure-activity relationships between amyloid aggregation and antimicrobial activity. Our results show how protein aggregation can induce bacteria agglutination and cell death. Using confocal and total internal reflection fluorescence microscopy we have tracked the formation in situ of protein amyloid-like aggregates at the bacteria surface and on membrane models. In both cases, fibrillar aggregates able to bind to amyloid diagnostic dyes were detected. Additionally, a single point mutation (Ile13 to Ala can suppress the protein amyloid behavior, abolishing the agglutinating activity and impairing the antimicrobial action. The mutant is also defective in triggering both leakage and lipid vesicle aggregation. We conclude that ECP aggregation at the bacterial surface is essential for its cytotoxicity. Hence, we propose here a new prospective biological function for amyloid-like aggregates with potential biological relevance.

Rab11-family of interacting protein 2 associates with chlamydial inclusions through its Rab-binding domain and promotes bacterial multiplication.

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Leiva, Natalia; Capmany, Anahí; Damiani, María Teresa

2013-01-01

Chlamydia trachomatis, an obligate intracellular pathogen, survives within host cells in a special compartment named 'inclusion' and takes advantage of host vesicular transport pathways for its growth and replication. Rab GTPases are key regulatory proteins of intracellular trafficking. Several Rabs, among them Rab11 and Rab14, are implicated in chlamydial development. FIP2, a member of the Rab11-Family of Interacting Proteins, presents at the C-terminus a Rab-binding domain that interacts with both Rab11 and Rab14. In this study, we determined and characterized the recruitment of endogenous and GFP-tagged FIP2 to the chlamydial inclusions. The recruitment of FIP2 is specific since other members of the Rab11-Family of Interacting Proteins do not associate with the chlamydial inclusions. The Rab-binding domain of FIP2 is essential for its association. Our results indicate that FIP2 binds to Rab11 at the chlamydial inclusion membrane through its Rab-binding domain. The presence of FIP2 at the chlamydial inclusion favours the recruitment of Rab14. Furthermore, our results show that FIP2 promotes inclusion development and bacterial replication. In agreement, the silencing of FIP2 decreases the bacterial progeny. C. trachomatis likely recruits FIP2 to hijack host intracellular trafficking to redirect vesicles full of nutrients towards the inclusion. © 2012 Blackwell Publishing Ltd.

Cross-interactions between the Alzheimer Disease Amyloid-β Peptide and Other Amyloid Proteins: A Further Aspect of the Amyloid Cascade Hypothesis.

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Luo, Jinghui; Wärmländer, Sebastian K T S; Gräslund, Astrid; Abrahams, Jan Pieter

2016-08-05

Many protein folding diseases are intimately associated with accumulation of amyloid aggregates. The amyloid materials formed by different proteins/peptides share many structural similarities, despite sometimes large amino acid sequence differences. Some amyloid diseases constitute risk factors for others, and the progression of one amyloid disease may affect the progression of another. These connections are arguably related to amyloid aggregates of one protein being able to directly nucleate amyloid formation of another, different protein: the amyloid cross-interaction. Here, we discuss such cross-interactions between the Alzheimer disease amyloid-β (Aβ) peptide and other amyloid proteins in the context of what is known from in vitro and in vivo experiments, and of what might be learned from clinical studies. The aim is to clarify potential molecular associations between different amyloid diseases. We argue that the amyloid cascade hypothesis in Alzheimer disease should be expanded to include cross-interactions between Aβ and other amyloid proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Loss of metal ions, disulfide reduction and mutations related to familial ALS promote formation of amyloid-like aggregates from superoxide dismutase.

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Zeynep A Oztug Durer

Full Text Available Mutations in the gene encoding Cu-Zn superoxide dismutase (SOD1 are one of the causes of familial amyotrophic lateral sclerosis (FALS. Fibrillar inclusions containing SOD1 and SOD1 inclusions that bind the amyloid-specific dye thioflavin S have been found in neurons of transgenic mice expressing mutant SOD1. Therefore, the formation of amyloid fibrils from human SOD1 was investigated. When agitated at acidic pH in the presence of low concentrations of guanidine or acetonitrile, metalated SOD1 formed fibrillar material which bound both thioflavin T and Congo red and had circular dichroism and infrared spectra characteristic of amyloid. While metalated SOD1 did not form amyloid-like aggregates at neutral pH, either removing metals from SOD1 with its intramolecular disulfide bond intact or reducing the intramolecular disulfide bond of metalated SOD1 was sufficient to promote formation of these aggregates. SOD1 formed amyloid-like aggregates both with and without intermolecular disulfide bonds, depending on the incubation conditions, and a mutant SOD1 lacking free sulfhydryl groups (AS-SOD1 formed amyloid-like aggregates at neutral pH under reducing conditions. ALS mutations enhanced the ability of disulfide-reduced SOD1 to form amyloid-like aggregates, and apo-AS-SOD1 formed amyloid-like aggregates at pH 7 only when an ALS mutation was also present. These results indicate that some mutations related to ALS promote formation of amyloid-like aggregates by facilitating the loss of metals and/or by making the intramolecular disulfide bond more susceptible to reduction, thus allowing the conversion of SOD1 to a form that aggregates to form resembling amyloid. Furthermore, the occurrence of amyloid-like aggregates per se does not depend on forming intermolecular disulfide bonds, and multiple forms of such aggregates can be produced from SOD1.

Isolation, characterization, and aggregation of a structured bacterial matrix precursor.

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Chai, Liraz; Romero, Diego; Kayatekin, Can; Akabayov, Barak; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

2013-06-14

Biofilms are surface-associated groups of microbial cells that are embedded in an extracellular matrix (ECM). The ECM is a network of biopolymers, mainly polysaccharides, proteins, and nucleic acids. ECM proteins serve a variety of structural roles and often form amyloid-like fibers. Despite the extensive study of the formation of amyloid fibers from their constituent subunits in humans, much less is known about the assembly of bacterial functional amyloid-like precursors into fibers. Using dynamic light scattering, atomic force microscopy, circular dichroism, and infrared spectroscopy, we show that our unique purification method of a Bacillus subtilis major matrix protein component results in stable oligomers that retain their native α-helical structure. The stability of these oligomers enabled us to control the external conditions that triggered their aggregation. In particular, we show that stretched fibers are formed on a hydrophobic surface, whereas plaque-like aggregates are formed in solution under acidic pH conditions. TasA is also shown to change conformation upon aggregation and gain some β-sheet structure. Our studies of the aggregation of a bacterial matrix protein from its subunits shed new light on assembly processes of the ECM within bacterial biofilms.

Lipopolysaccharide Associates with Amyloid Plaques, Neurons and Oligodendrocytes in Alzheimer’s Disease Brain: A Review

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Xinhua Zhan

2018-02-01

Full Text Available This review proposes that lipopolysaccharide (LPS, found in the wall of all Gram-negative bacteria could play a role in causing sporadic Alzheimer’s disease (AD. This is based in part upon recent studies showing that: Gram-negative E. coli bacteria can form extracellular amyloid; bacterial-encoded 16S rRNA is present in all human brains with over 70% being Gram-negative bacteria; ultrastructural analyses have shown microbes in erythrocytes of AD patients; blood LPS levels in AD patients are 3-fold the levels in control; LPS combined with focal cerebral ischemia and hypoxia produced amyloid-like plaques and myelin injury in adult rat cortex. Moreover, Gram-negative bacterial LPS was found in aging control and AD brains, though LPS levels were much higher in AD brains. In addition, LPS co-localized with amyloid plaques, peri-vascular amyloid, neurons, and oligodendrocytes in AD brains. Based upon the postulate LPS caused oligodendrocyte injury, degraded Myelin Basic Protein (dMBP levels were found to be much higher in AD compared to control brains. Immunofluorescence showed that the dMBP co-localized with β amyloid (Aβ and LPS in amyloid plaques in AD brain, and dMBP and other myelin molecules were found in the walls of vesicles in periventricular White Matter (WM. These data led to the hypothesis that LPS acts on leukocyte and microglial TLR4-CD14/TLR2 receptors to produce NFkB mediated increases of cytokines which increase Aβ levels, damage oligodendrocytes and produce myelin injury found in AD brain. Since Aβ1–42 is also an agonist for TLR4 receptors, this could produce a vicious cycle that accounts for the relentless progression of AD. Thus, LPS, the TLR4 receptor complex, and Gram-negative bacteria might be treatment or prevention targets for sporadic AD.

Amyloid and immune homeostasis.

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Wang, Ying-Hui; Zhang, Yu-Gen

2018-03-01

Extracellular amyloid deposition defines a range of amyloidosis and amyloid-related disease. Addition to primary and secondary amyloidosis, amyloid-related disease can be observed in different tissue/organ that sharing the common pathogenesis based on the formation of amyloid deposition. Currently, both Alzheimer's disease and type 2 diabetes can be diagnosed with certainly only based on the autopsy results, by which amyloidosis of the associative tissue/organ is observed. Intriguingly, since it demonstrated that amyloid deposits trigger inflammatory reaction through the activation of cascaded immune response, wherein several lines of evidence implies a protective role of amyloid in preventing autoimmunity. Furthermore, attempts for preventing amyloid formation and/or removing amyloid deposits from the brain have caused meningoencephalitis and consequent deaths among the subjects. Hence, it is important to note that amyloid positively participates in maintaining immune homeostasis and contributes to irreversible inflammatory response. In this review, we will focus on the interactive relationship between amyloid and the immune system, discussing the potential functional roles of amyloid in immune tolerance and homeostasis. Copyright © 2017 Elsevier GmbH. All rights reserved.

The nuclear inclusion a (NIa protease of turnip mosaic virus (TuMV cleaves amyloid-β.

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Hye-Eun Han

Full Text Available BACKGROUND: The nuclear inclusion a (NIa protease of turnip mosaic virus (TuMV is responsible for the processing of the viral polyprotein into functional proteins. NIa was previously shown to possess a relatively strict substrate specificity with a preference for Val-Xaa-His-Gln↓, with the scissile bond located after Gln. The presence of the same consensus sequence, Val(12-His-His-Gln(15, near the presumptive α-secretase cleavage site of the amyloid-β (Aβ peptide led us to hypothesize that NIa could possess activity against Aβ. METHODOLOGY/PRINCIPAL FINDINGS: Western blotting results showed that oligomeric as well as monomeric forms of Aβ can be degraded by NIa in vitro. The specific cleavage of Aβ was further confirmed by mass spectrometry analysis. NIa was shown to exist predominantly in the cytoplasm as observed by immunofluorescence microscopy. The overexpression of NIa in B103 neuroblastoma cells resulted in a significant reduction in cell death caused by both intracellularly generated and exogenously added Aβ. Moreover, lentiviral-mediated expression of NIa in APP(sw/PS1 transgenic mice significantly reduced the levels of Aβ and plaques in the brain. CONCLUSIONS/SIGNIFICANCE: These results indicate that the degradation of Aβ in the cytoplasm could be a novel strategy to control the levels of Aβ, plaque formation, and the associated cell death.

Amyloid β-sheet mimics that antagonize protein aggregation and reduce amyloid toxicity

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Cheng, Pin-Nan; Liu, Cong; Zhao, Minglei; Eisenberg, David; Nowick, James S.

2012-11-01

The amyloid protein aggregation associated with diseases such as Alzheimer's, Parkinson's and type II diabetes (among many others) features a bewildering variety of β-sheet-rich structures in transition from native proteins to ordered oligomers and fibres. The variation in the amino-acid sequences of the β-structures presents a challenge to developing a model system of β-sheets for the study of various amyloid aggregates. Here, we introduce a family of robust β-sheet macrocycles that can serve as a platform to display a variety of heptapeptide sequences from different amyloid proteins. We have tailored these amyloid β-sheet mimics (ABSMs) to antagonize the aggregation of various amyloid proteins, thereby reducing the toxicity of amyloid aggregates. We describe the structures and inhibitory properties of ABSMs containing amyloidogenic peptides from the amyloid-β peptide associated with Alzheimer's disease, β2-microglobulin associated with dialysis-related amyloidosis, α-synuclein associated with Parkinson's disease, islet amyloid polypeptide associated with type II diabetes, human and yeast prion proteins, and Tau, which forms neurofibrillary tangles.

Functional Amyloids in Reproduction.

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Hewetson, Aveline; Do, Hoa Quynh; Myers, Caitlyn; Muthusubramanian, Archana; Sutton, Roger Bryan; Wylie, Benjamin J; Cornwall, Gail A

2017-06-29

Amyloids are traditionally considered pathological protein aggregates that play causative roles in neurodegenerative disease, diabetes and prionopathies. However, increasing evidence indicates that in many biological systems nonpathological amyloids are formed for functional purposes. In this review, we will specifically describe amyloids that carry out biological roles in sexual reproduction including the processes of gametogenesis, germline specification, sperm maturation and fertilization. Several of these functional amyloids are evolutionarily conserved across several taxa, including human, emphasizing the critical role amyloids perform in reproduction. Evidence will also be presented suggesting that, if altered, some functional amyloids may become pathological.

Amyloid Imaging in Aging and Dementia: Testing the Amyloid Hypothesis In Vivo

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G. D. Rabinovici

2009-01-01

Full Text Available Amyloid imaging represents a major advance in neuroscience, enabling the detection and quantification of pathologic protein aggregations in the brain. In this review we survey current amyloid imaging techniques, focusing on positron emission tomography (PET with ^{11}carbon-labelled Pittsburgh Compound-B (11C-PIB, the most extensively studied and best validated tracer. PIB binds specifically to fibrillar beta-amyloid (Aβ deposits, and is a sensitive marker for Aβ pathology in cognitively normal older individuals and patients with mild cognitive impairment (MCI and Alzheimer’s disease (AD. PIB-PET provides us with a powerful tool to examine in vivo the relationship between amyloid deposition, clinical symptoms, and structural and functional brain changes in the continuum between normal aging and AD. Amyloid imaging studies support a model in which amyloid deposition is an early event on the path to dementia, beginning insidiously in cognitively normal individuals, and accompanied by subtle cognitive decline and functional and structural brain changes suggestive of incipient AD. As patients progress to dementia, clinical decline and neurodegeneration accelerate and proceed independently of amyloid accumulation. In the future, amyloid imaging is likely to supplement clinical evaluation in selecting patients for anti-amyloid therapies, while MRI and FDG-PET may be more appropriate markers of clinical progression.

Functional amyloids in bacteria.

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Romero, Diego; Kolter, Roberto

2014-06-01

The term amyloidosis is used to refer to a family of pathologies altering the homeostasis of human organs. Despite having a name that alludes to starch content, the amyloid accumulations are made up of proteins that polymerize as long and rigid fibers. Amyloid proteins vary widely with respect to their amino acid sequences but they share similarities in their quaternary structure; the amyloid fibers are enriched in β-sheets arranged perpendicular to the axis of the fiber. This structural feature provides great robustness, remarkable stability, and insolubility. In addition, amyloid proteins specifically stain with certain dyes such as Congo red and thioflavin-T. The aggregation into amyloid fibers, however, it is not restricted to pathogenic processes, rather it seems to be widely distributed among proteins and polypeptides. Amyloid fibers are present in insects, fungi and bacteria, and they are important in maintaining the homeostasis of the organism. Such findings have motivated the use of the term "functional amyloid" to differentiate these amyloid proteins from their toxic siblings. This review focuses on systems that have evolved in bacteria that control the expression and assembly of amyloid proteins on cell surfaces, such that the robustness of amyloid proteins are used towards a beneficial end. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Organotypic vibrosections from whole brain adult Alzheimer mice (overexpressing amyloid-precursor-protein with the Swedish-Dutch-Iowa mutations as a model to study clearance of beta-amyloid plaques

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Christian eHumpel

2015-04-01

Full Text Available Alzheimer´s disease is a severe neurodegenerative disorder of the brain, pathologically characterized by extracellular beta-amyloid plaques, intraneuronal Tau inclusions, inflammation, reactive glial cells, vascular pathology and neuronal cell death. The degradation and clearance of beta-amyloid plaques is an interesting therapeutic approach, and the proteases neprilysin (NEP, insulysin and matrix metalloproteinases (MMP are of particular interest. The aim of this project was to establish and characterize a simple in vitro model to study the degrading effects of these proteases. Organoytpic brain vibrosections (120 µm thick were sectioned from adult (9 month old wildtype and transgenic mice (expressing amyloid precursor protein (APP harboring the Swedish K670N/M671L, Dutch E693Q, and Iowa D694N mutations; APP_SDI and cultured for 2 weeks. Plaques were stained by immunohistochemistry for beta-amyloid and Thioflavin S. Our data show that plaques were evident in 2 week old cultures from 9 month old transgenic mice. These plaques were surrounded by reactive GFAP+ astroglia and Iba1+ microglia. Incubation of fresh slices for 2 weeks with 1-0.1-0.01 µg/ml of NEP, insulysin, MMP-2 or MMP-9 showed that NEP, insulysin and MMP-9 markedly degradeded beta-amyloid plaques but only at the highest concentration. Our data provide for the first time a potent and powerful living brain vibrosection model containing a high number of plaques, which allows to rapidly and simply study the degradation and clearance of beta-amyloid plaques in vitro.

Cerebral amyloid angiopathy, blood-brain barrier disruption and amyloid accumulation in SAMP8 mice.

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del Valle, Jaume; Duran-Vilaregut, Joaquim; Manich, Gemma; Pallàs, Mercè; Camins, Antoni; Vilaplana, Jordi; Pelegrí, Carme

2011-01-01

Cerebrovascular dysfunction and β-amyloid peptide deposition on the walls of cerebral blood vessels might be an early event in the development of Alzheimer's disease. Here we studied the time course of amyloid deposition in blood vessels and blood-brain barrier (BBB) disruption in the CA1 subzone of the hippocampus of SAMP8 mice and the association between these two variables. We also studied the association between the amyloid deposition in blood vessels and the recently described amyloid clusters in the parenchyma, as well as the association of these clusters with vessels in which the BBB is disrupted. SAMP8 mice showed greater amyloid deposition in blood vessels than age-matched ICR-CD1 control mice. Moreover, at 12 months of age the number of vessels with a disrupted BBB had increased in both strains, especially SAMP8 animals. At this age, all the vessels with amyloid deposition showed BBB disruption, but several capillaries with an altered BBB showed no amyloid on their walls. Moreover, amyloid clusters showed no spatial association with vessels with amyloid deposition, nor with vessels in which the BBB had been disrupted. Finally, we can conclude that vascular amyloid deposition seems to induce BBB alterations, but BBB disruption may also be due to other factors. Copyright © 2011 S. Karger AG, Basel.

Tetrahydroxystilbene glucoside modulates amyloid precursor protein processing via activation of AKT-GSK3β pathway in cells and in APP/PS1 transgenic mice.

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Yin, Xiaomin; Chen, Chen; Xu, Ting; Li, Lin; Zhang, Lan

2018-01-01

Alternative splicing of amyloid precursor protein (APP) exon 7 generates the isoforms containing a Kunitz protease inhibitor (KPI) domain. APP-KPI levels in the brain are correlated with amyloid beta (Aβ) production. Here, we determined the effect of Tetrahydroxystilbene glucoside (TSG) on the AKT-GSK3β pathway. We found GSK3β increased APP-KPI inclusion level and interacted with the splicing factor ASF. TSG was intragastrically administered to 5-month-old APP/PS1 transgenic mice for 12 months. We found that the activated the AKT-GSK3β signaling pathway suppressed APP-KPI inclusion. Moreover, TSG treatment attenuated amyloid deposition in APP/PS1 mice. This study demonstrates the neuroprotective effect of TSG on APP expression, suggesting that TSG may be beneficial for AD prevention and treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Diagnostic radionuclide imaging of amyloid: biological targeting by circulating human serum amyloid P component

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Hawkins, P.N.; Lavender, J.P.; Myers, M.J.; Pepys, M.B.

1988-06-25

The specific molecular affinity of the normal plasma protein, serum amyloid P component (SAP), for all known types of amyloid fibrils was used to develop a new general diagnostic method for in-vivo radionuclide imaging of amyloid deposits. After intravenous injection of /sup 123/I-labelled purified human SAP there was specific uptake into amyloid deposits in all affected patients, 7 with systematic AL amyloid, 5 with AA amyloid, and 2 with ..beta../sub 2/M amyloid, in contrast to the complete absence of any tissue localisation in 5 control subjects. Distinctive high-resolution scintigraphic images, even of minor deposits in the carpal regions, bone marrow, or adrenals, were obtained. This procedure should yield much information on the natural history and the management of amyloidosis, the presence of which has hitherto been confirmed only by biopsy. Clearance and metabolic studies indicated that, in the presence of extensive amyloidosis, the rate of synthesis of SAP was greatly increased despite maintenance of normal plasma levels. Futhermore, once localised to amyloid deposits the /sup 123/I-SAP persisted for long periods and was apparently protected from its normal rapid degradation. These findings shed new light on the pathophysiology of amyloid and may have implications for therapeutic strategies based upon specific molecular targeting with SAP.

Formation of soluble amyloid oligomers and amyloid fibrils by the multifunctional protein vitronectin

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Langen Ralf

2008-10-01

Full Text Available Abstract Background The multifunctional protein vitronectin is present within the deposits associated with Alzheimer disease (AD, age-related macular degeneration (AMD, atherosclerosis, systemic amyloidoses, and glomerulonephritis. The extent to which vitronectin contributes to amyloid formation within these plaques, which contain misfolded, amyloidogenic proteins, and the role of vitronectin in the pathophysiology of the aforementioned diseases is currently unknown. The investigation of vitronectin aggregation is significant since the formation of oligomeric and fibrillar structures are common features of amyloid proteins. Results We observed vitronectin immunoreactivity in senile plaques of AD brain, which exhibited overlap with the amyloid fibril-specific OC antibody, suggesting that vitronectin is deposited at sites of amyloid formation. Of particular interest is the growing body of evidence indicating that soluble nonfibrillar oligomers may be responsible for the development and progression of amyloid diseases. In this study we demonstrate that both plasma-purified and recombinant human vitronectin readily form spherical oligomers and typical amyloid fibrils. Vitronectin oligomers are toxic to cultured neuroblastoma and retinal pigment epithelium (RPE cells, possibly via a membrane-dependent mechanism, as they cause leakage of synthetic vesicles. Oligomer toxicity was attenuated in RPE cells by the anti-oligomer A11 antibody. Vitronectin fibrils contain a C-terminal protease-resistant fragment, which may approximate the core region of residues essential to amyloid formation. Conclusion These data reveal the propensity of vitronectin to behave as an amyloid protein and put forth the possibilities that accumulation of misfolded vitronectin may contribute to aggregate formation seen in age-related amyloid diseases.

Hyperforin prevents beta-amyloid neurotoxicity and spatial memory impairments by disaggregation of Alzheimer's amyloid-beta-deposits.

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Dinamarca, M C; Cerpa, W; Garrido, J; Hancke, J L; Inestrosa, N C

2006-11-01

The major protein constituent of amyloid deposits in Alzheimer's disease (AD) is the amyloid beta-peptide (Abeta). In the present work, we have determined the effect of hyperforin an acylphloroglucinol compound isolated from Hypericum perforatum (St John's Wort), on Abeta-induced spatial memory impairments and on Abeta neurotoxicity. We report here that hyperforin: (1) decreases amyloid deposit formation in rats injected with amyloid fibrils in the hippocampus; (2) decreases the neuropathological changes and behavioral impairments in a rat model of amyloidosis; (3) prevents Abeta-induced neurotoxicity in hippocampal neurons both from amyloid fibrils and Abeta oligomers, avoiding the increase in reactive oxidative species associated with amyloid toxicity. Both effects could be explained by the capacity of hyperforin to disaggregate amyloid deposits in a dose and time-dependent manner and to decrease Abeta aggregation and amyloid formation. Altogether these evidences suggest that hyperforin may be useful to decrease amyloid burden and toxicity in AD patients, and may be a putative therapeutic agent to fight the disease.

Amyloid positron emission tomography in sporadic cerebral amyloid angiopathy: A systematic critical update

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Karim Farid

2017-01-01

Full Text Available Sporadic cerebral amyloid angiopathy (CAA is a very common small vessel disease of the brain, showing preferential and progressive amyloid-βdeposition in the wall of small arterioles and capillaries of the leptomeninges and cerebral cortex. CAA now encompasses not only a specific cerebrovascular pathological trait, but also different clinical syndromes - including spontaneous lobar intracerebral haemorrhage (ICH, dementia and ‘amyloid spells’ - an expanding spectrum of brain parenchymal MRI lesions and a set of diagnostic criteria – the Boston criteria, which have resulted in increasingly detecting CAA during life. Although currently available validated diagnostic criteria perform well in multiple lobar ICH, a formal diagnosis is currently lacking unless a brain biopsy is performed. This is partly because in practice CAA MRI biomarkers provide only indirect evidence for the disease. An accurate diagnosis of CAA in different clinical settings would have substantial impact for ICH risk stratification and antithrombotic drug use in elderly people, but also for sample homogeneity in drug trials. It has recently been demonstrated that vascular (in addition to parenchymal amyloid-βdeposition can be detected and quantified in vivo by positron emission tomography (PET amyloid tracers. This non-invasive approach has the potential to provide a molecular signature of CAA, and could in turn have major clinical impact. However, several issues around amyloid-PET in CAA remain unsettled and hence its diagnostic utility is limited. In this article we systematically review and critically appraise the published literature on amyloid-PET (PiB and other tracers in sporadic CAA. We focus on two key areas: (a the diagnostic utility of amyloid-PET in CAA and (b the use of amyloid-PET as a window to understand pathophysiological mechanism of the disease. Key issues around amyloid-PET imaging in CAA, including relevant technical aspects are also covered in depth

IL-1β-Induced Accumulation of Amyloid: Macroautophagy in Skeletal Muscle Depends on ERK

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Karsten Schmidt

2017-01-01

Full Text Available The pathology of inclusion body myositis (IBM involves an inflammatory response and β-amyloid deposits in muscle fibres. It is believed that MAP kinases such as the ERK signalling pathway mediate the inflammatory signalling in cells. Further, there is evidence that autophagic activity plays a crucial role in the pathogenesis of IBM. Using a well established in vitro model of IBM, the autophagic pathway, MAP kinases, and accumulation of β-amyloid were examined. We demonstrate that stimulation of muscle cells with IL-1β and IFN-γ led to an increased phosphorylation of ERK. The ERK inhibitor PD98059 diminished the expression of proinflammatory markers as well as the accumulation of β-amyloid. In addition, IL-1β and IFN-γ led to an increase of autophagic activity, upregulation of APP, and subsequent accumulation of β-sheet aggregates. Taken together, the data demonstrate that the ERK pathway contributes to formation of β-amyloid and regulation of autophagic activity in muscle cells exposed to proinflammatory cell stress. This suggests that ERK serves as an important mediator between inflammatory mechanisms and protein deposition in skeletal muscle and is a crucial element of the pathology of IBM.

{beta} - amyloid imaging probes

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Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2007-04-15

Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

β - amyloid imaging probes

International Nuclear Information System (INIS)

Jeong, Jae Min

2007-01-01

Imaging distribution of β - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the β -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral β - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging β - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for β - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for β - amyloid imaging agent

General amyloid inhibitors? A critical examination of the inhibition of IAPP amyloid formation by inositol stereoisomers.

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Hui Wang

Full Text Available Islet amyloid polypeptide (IAPP or amylin forms amyloid deposits in the islets of Langerhans; a process that is believed to contribute to the progression of type 2 diabetes and to the failure of islet transplants. An emerging theme in amyloid research is the hypothesis that the toxic species produced during amyloid formation by different polypeptides share common features and exert their effects by common mechanisms. If correct, this suggests that inhibitors of amyloid formation by one polypeptide might be effective against other amyloidogenic sequences. IAPP and Aβ, the peptide responsible for amyloid formation in Alzheimer's disease, are particularly interesting in this regard as they are both natively unfolded in their monomeric states and share some common characteristics. Comparatively little effort has been expended on the design of IAPP amyloid inhibitors, thus it is natural to inquire if Aβ inhibitors are effective against IAPP, especially since no IAPP inhibitors have been clinically approved. A range of compounds inhibit Aβ amyloid formation, including various stereoisomers of inositol. Myo-, scyllo-, and epi-inositol have been shown to induce conformational changes in Aβ and prevent Aβ amyloid fibril formation by stabilizing non-fibrillar β-sheet structures. We investigate the ability of inositol stereoisomers to inhibit amyloid formation by IAPP. The compounds do not induce a conformational change in IAPP and are ineffective inhibitors of IAPP amyloid formation, although some do lead to modest apparent changes in IAPP amyloid fibril morphology. Thus not all classes of Aβ inhibitors are effective against IAPP. This work provides a basis of comparison to work on polyphenol based inhibitors of IAPP amyloid formation and helps provide clues as to the features which render them effective. The study also helps provide information for further efforts in rational inhibitor design.

Endocytic vesicle rupture is a conserved mechanism of cellular invasion by amyloid proteins.

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Flavin, William P; Bousset, Luc; Green, Zachary C; Chu, Yaping; Skarpathiotis, Stratos; Chaney, Michael J; Kordower, Jeffrey H; Melki, Ronald; Campbell, Edward M

2017-10-01

Numerous pathological amyloid proteins spread from cell to cell during neurodegenerative disease, facilitating the propagation of cellular pathology and disease progression. Understanding the mechanism by which disease-associated amyloid protein assemblies enter target cells and induce cellular dysfunction is, therefore, key to understanding the progressive nature of such neurodegenerative diseases. In this study, we utilized an imaging-based assay to monitor the ability of disease-associated amyloid assemblies to rupture intracellular vesicles following endocytosis. We observe that the ability to induce vesicle rupture is a common feature of α-synuclein (α-syn) assemblies, as assemblies derived from WT or familial disease-associated mutant α-syn all exhibited the ability to induce vesicle rupture. Similarly, different conformational strains of WT α-syn assemblies, but not monomeric or oligomeric forms, efficiently induced vesicle rupture following endocytosis. The ability to induce vesicle rupture was not specific to α-syn, as amyloid assemblies of tau and huntingtin Exon1 with pathologic polyglutamine repeats also exhibited the ability to induce vesicle rupture. We also observe that vesicles ruptured by α-syn are positive for the autophagic marker LC3 and can accumulate and fuse into large, intracellular structures resembling Lewy bodies in vitro. Finally, we show that the same markers of vesicle rupture surround Lewy bodies in brain sections from PD patients. These data underscore the importance of this conserved endocytic vesicle rupture event as a damaging mechanism of cellular invasion by amyloid assemblies of multiple neurodegenerative disease-associated proteins, and suggest that proteinaceous inclusions such as Lewy bodies form as a consequence of continued fusion of autophagic vesicles in cells unable to degrade ruptured vesicles and their amyloid contents.

Widespread abundance of functional bacterial amyloid in Mycolata and other Gram-positive bacteria

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Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul

2009-01-01

extracellular fibrils were also produced. In three cases, FuBA was only revealed after extensive removal of extracellular material by saponification, indicating an integrated attachment within the cellular envelope. Spores from species within the genera Streptomyces, Bacillus and Nocardia were all coated...... analysis. We conclude that amyloid is widespread among Gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spores and the cellular envelope....

Nanomechanical properties of single amyloid fibrils

International Nuclear Information System (INIS)

Sweers, K K M; Bennink, M L; Subramaniam, V

2012-01-01

Amyloid fibrils are traditionally associated with neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease or Creutzfeldt-Jakob disease. However, the ability to form amyloid fibrils appears to be a more generic property of proteins. While disease-related, or pathological, amyloid fibrils are relevant for understanding the pathology and course of the disease, functional amyloids are involved, for example, in the exceptionally strong adhesive properties of natural adhesives. Amyloid fibrils are thus becoming increasingly interesting as versatile nanobiomaterials for applications in biotechnology. In the last decade a number of studies have reported on the intriguing mechanical characteristics of amyloid fibrils. In most of these studies atomic force microscopy (AFM) and atomic force spectroscopy play a central role. AFM techniques make it possible to probe, at nanometer length scales, and with exquisite control over the applied forces, biological samples in different environmental conditions. In this review we describe the different AFM techniques used for probing mechanical properties of single amyloid fibrils on the nanoscale. An overview is given of the existing mechanical studies on amyloid. We discuss the difficulties encountered with respect to the small fibril sizes and polymorphic behavior of amyloid fibrils. In particular, the different conformational packing of monomers within the fibrils leads to a heterogeneity in mechanical properties. We conclude with a brief outlook on how our knowledge of these mechanical properties of the amyloid fibrils can be exploited in the construction of nanomaterials from amyloid fibrils. (topical review)

Functional Amyloid Formation within Mammalian Tissue.

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2005-11-01

Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

Functional amyloid formation within mammalian tissue.

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Douglas M Fowler

2006-01-01

Full Text Available Amyloid is a generally insoluble, fibrous cross-beta sheet protein aggregate. The process of amyloidogenesis is associated with a variety of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington disease. We report the discovery of an unprecedented functional mammalian amyloid structure generated by the protein Pmel17. This discovery demonstrates that amyloid is a fundamental nonpathological protein fold utilized by organisms from bacteria to humans. We have found that Pmel17 amyloid templates and accelerates the covalent polymerization of reactive small molecules into melanin-a critically important biopolymer that protects against a broad range of cytotoxic insults including UV and oxidative damage. Pmel17 amyloid also appears to play a role in mitigating the toxicity associated with melanin formation by sequestering and minimizing diffusion of highly reactive, toxic melanin precursors out of the melanosome. Intracellular Pmel17 amyloidogenesis is carefully orchestrated by the secretory pathway, utilizing membrane sequestration and proteolytic steps to protect the cell from amyloid and amyloidogenic intermediates that can be toxic. While functional and pathological amyloid share similar structural features, critical differences in packaging and kinetics of assembly enable the usage of Pmel17 amyloid for normal function. The discovery of native Pmel17 amyloid in mammals provides key insight into the molecular basis of both melanin formation and amyloid pathology, and demonstrates that native amyloid (amyloidin may be an ancient, evolutionarily conserved protein quaternary structure underpinning diverse pathways contributing to normal cell and tissue physiology.

Anti-amyloid treatments in Alzheimer's disease.

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Sapra, Mamta; Kim, Kye Y

2009-06-01

Alzheimer's disease is one of the most challenging threats to the healthcare system in society. One of the main characteristic of Alzheimer's disease (AD) pathology is formation of amyloid plaques from accumulation of amyloid beta peptide. The therapeutic agents that are currently available for AD including acetylcholinesterase inhibitors (AchEIs) and the N-methyl-D-aspartate (NMDA) antagonist are focused on improving the symptoms and do not revert the progression of the disease. This limitation coupled with the burgeoning increase in the prevalence of AD and resultant impact on healthcare economics calls for more substantial treatments for AD. According to the leading amyloid hypothesis, cleavage of amyloid precursor protein to release amyloid beta peptide is the critical event in pathogenesis of Alzheimer's disease. Recently treatment strategies have been focused on modifying the formation, clearance and accumulation of neurotoxic amyloid beta peptide. This article reviews different therapeutic approaches that have been investigated to target amyloid beta ranging from secretase modulators, antiaggregation agents to amyloid immunotherapy. Authors review the different novel drugs which are in clinical trials.

Extracellular vesicles from human pancreatic islets suppress human islet amyloid polypeptide amyloid formation

OpenAIRE

Ribeiro, Diana; Horvath, Istvan; Heath, Nikki; Hicks, Ryan; Forslöw, Anna; Wittung-Stafshede, Pernilla

2017-01-01

Protein assembly into amyloid fibers underlies such neurodegenerative disorders as Alzheimer’s disease and Parkinson’s disease. Type 2 diabetes (T2D) also involves amyloid formation, although in the pancreas. Because there are no cures for amyloid diseases and T2D is on the rise due to an increasing prevalence of obesity, identifying involved mechanisms and control processes is of utmost importance. Extracellular vesicles (EVs) can mediate physiological and pathological communication both loc...

Towards a Pharmacophore for Amyloid

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Landau, Meytal; Sawaya, Michael R.; Faull, Kym F.; Laganowsky, Arthur; Jiang, Lin; Sievers, Stuart A.; Liu, Jie; Barrio, Jorge R.; Eisenberg, David (UCLA)

2011-09-16

Diagnosing and treating Alzheimer's and other diseases associated with amyloid fibers remains a great challenge despite intensive research. To aid in this effort, we present atomic structures of fiber-forming segments of proteins involved in Alzheimer's disease in complex with small molecule binders, determined by X-ray microcrystallography. The fiber-like complexes consist of pairs of {beta}-sheets, with small molecules binding between the sheets, roughly parallel to the fiber axis. The structures suggest that apolar molecules drift along the fiber, consistent with the observation of nonspecific binding to a variety of amyloid proteins. In contrast, negatively charged orange-G binds specifically to lysine side chains of adjacent sheets. These structures provide molecular frameworks for the design of diagnostics and drugs for protein aggregation diseases. The devastating and incurable dementia known as Alzheimer's disease affects the thinking, memory, and behavior of dozens of millions of people worldwide. Although amyloid fibers and oligomers of two proteins, tau and amyloid-{beta}, have been identified in association with this disease, the development of diagnostics and therapeutics has proceeded to date in a near vacuum of information about their structures. Here we report the first atomic structures of small molecules bound to amyloid. These are of the dye orange-G, the natural compound curcumin, and the Alzheimer's diagnostic compound DDNP bound to amyloid-like segments of tau and amyloid-{beta}. The structures reveal the molecular framework of small-molecule binding, within cylindrical cavities running along the {beta}-spines of the fibers. Negatively charged orange-G wedges into a specific binding site between two sheets of the fiber, combining apolar binding with electrostatic interactions, whereas uncharged compounds slide along the cavity. We observed that different amyloid polymorphs bind different small molecules, revealing that a

Why are Functional Amyloids Non-Toxic in Humans?

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Matthew P. Jackson

2017-09-01

Full Text Available Amyloids were first identified in association with amyloidoses, human diseases in which proteins and peptides misfold into amyloid fibrils. Subsequent studies have identified an array of functional amyloid fibrils that perform physiological roles in humans. Given the potential for the production of toxic species in amyloid assembly reactions, it is remarkable that cells can produce these functional amyloids without suffering any obvious ill effect. Although the precise mechanisms are unclear, there are a number of ways in which amyloid toxicity may be prevented. These include regulating the level of the amyloidogenic peptides and proteins, minimising the production of prefibrillar oligomers in amyloid assembly reactions, sequestrating amyloids within membrane bound organelles, controlling amyloid assembly by other molecules, and disassembling the fibrils under physiological conditions. Crucially, a better understanding of how toxicity is avoided in the production of functional amyloids may provide insights into the prevention of amyloid toxicity in amyloidoses.

Packaging protein drugs as bacterial inclusion bodies for therapeutic applications

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Villaverde Antonio

2012-06-01

Full Text Available Abstract A growing number of insights on the biology of bacterial inclusion bodies (IBs have revealed intriguing utilities of these protein particles. Since they combine mechanical stability and protein functionality, IBs have been already exploited in biocatalysis and explored for bottom-up topographical modification in tissue engineering. Being fully biocompatible and with tuneable bio-physical properties, IBs are currently emerging as agents for protein delivery into mammalian cells in protein-replacement cell therapies. So far, IBs formed by chaperones (heat shock protein 70, Hsp70, enzymes (catalase and dihydrofolate reductase, grow factors (leukemia inhibitory factor, LIF and structural proteins (the cytoskeleton keratin 14 have been shown to rescue exposed cells from a spectrum of stresses and restore cell functions in absence of cytotoxicity. The natural penetrability of IBs into mammalian cells (reaching both cytoplasm and nucleus empowers them as an unexpected platform for the controlled delivery of essentially any therapeutic polypeptide. Production of protein drugs by biopharma has been traditionally challenged by IB formation. However, a time might have arrived in which recombinant bacteria are to be engineered for the controlled packaging of therapeutic proteins as nanoparticulate materials (nanopills, for their extra- or intra-cellular release in medicine and cosmetics.

Experimental induction of chicken amyloid A amyloidosis in white layer chickens by inoculation with inactivated vaccines.

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Habibi, Wazir Ahmad; Hirai, Takuya; Niazmand, Mohammad Hakim; Okumura, Naoko; Yamaguchi, Ryoji

2017-10-01

We investigated the amyloidogenic potential of inactivated vaccines and the localized production of serum amyloid A (SAA) at the injection site in white layer chickens. Hens in the treated group were injected intramuscularly three times with high doses of inactivated oil-emulsion Salmonella Enteritidis vaccine and multivalent viral and bacterial inactivated oil-emulsion vaccines at two-week intervals. Chickens in the control group did not receive any inoculum. In the treated group, emaciation and granulomas were present, while several chickens died between 4 and 6 weeks after the first injection. Hepatomegaly was seen at necropsy, and the liver parenchyma showed inconsistent discolouration with patchy green to yellowish-brown areas, or sometimes red-brown areas with haemorrhage. Amyloid deposition in the liver, spleen, duodenum, and at injection sites was demonstrated using haematoxylin and eosin staining, Congo red, and immunohistochemistry. The incidence of chicken amyloid A (AA) amyloidosis was 47% (28 of 60) in the treated group. In addition, RT-PCR was used to identify chicken SAA mRNA expression in the liver and at the injection sites. Furthermore, SAA mRNA was detected by in situ hybridization in fibroblasts at the injection sites, and also in hepatocytes. We believe that this is the first report of the experimental induction of systemic AA amyloidosis in white layer chickens following repeated inoculation with inactivated vaccines without the administration of amyloid fibrils or other amyloid-enhancing factors.

A subcutaneous cellular implant for passive immunization against amyloid-β reduces brain amyloid and tau pathologies.

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Lathuilière, Aurélien; Laversenne, Vanessa; Astolfo, Alberto; Kopetzki, Erhard; Jacobsen, Helmut; Stampanoni, Marco; Bohrmann, Bernd; Schneider, Bernard L; Aebischer, Patrick

2016-05-01

Passive immunization against misfolded toxic proteins is a promising approach to treat neurodegenerative disorders. For effective immunotherapy against Alzheimer's disease, recent clinical data indicate that monoclonal antibodies directed against the amyloid-β peptide should be administered before the onset of symptoms associated with irreversible brain damage. It is therefore critical to develop technologies for continuous antibody delivery applicable to disease prevention. Here, we addressed this question using a bioactive cellular implant to deliver recombinant anti-amyloid-β antibodies in the subcutaneous tissue. An encapsulating device permeable to macromolecules supports the long-term survival of myogenic cells over more than 10 months in immunocompetent allogeneic recipients. The encapsulated cells are genetically engineered to secrete high levels of anti-amyloid-β antibodies. Peripheral implantation leads to continuous antibody delivery to reach plasma levels that exceed 50 µg/ml. In a proof-of-concept study, we show that the recombinant antibodies produced by this system penetrate the brain and bind amyloid plaques in two mouse models of the Alzheimer's pathology. When encapsulated cells are implanted before the onset of amyloid plaque deposition in TauPS2APP mice, chronic exposure to anti-amyloid-β antibodies dramatically reduces amyloid-β40 and amyloid-β42 levels in the brain, decreases amyloid plaque burden, and most notably, prevents phospho-tau pathology in the hippocampus. These results support the use of encapsulated cell implants for passive immunotherapy against the misfolded proteins, which accumulate in Alzheimer's disease and other neurodegenerative disorders. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Amyloid Goiter Secondary to Ulcerative Colitis

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Bunyamin Aydin

2016-01-01

Full Text Available Diffuse amyloid goiter (AG is an entity characterized by the deposition of amyloid in the thyroid gland. AG may be associated with either primary or secondary amyloidosis. Secondary amyloidosis is rarely caused by inflammatory bowel diseases. Secondary amyloidosis is relatively more common in the patients with Crohn’s disease, whereas it is highly rare in patients with ulcerative colitis. Diffuse amyloid goiter caused by ulcerative colitis is also a rare condition. In the presence of amyloid in the thyroid gland, medullary thyroid cancer should be kept in mind in the differential diagnosis. Imaging techniques and biochemical tests are not very helpful in the diagnosis of secondary amyloid goiter and the definitive diagnosis is established based on the histopathologic analysis and histochemical staining techniques. In this report, we present a 35-year-old male patient with diffuse amyloid goiter caused by secondary amyloidosis associated with ulcerative colitis.

Chiral recognition in amyloid fiber growth.

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Torbeev, Vladimir; Grogg, Marcel; Ruiz, Jérémy; Boehringer, Régis; Schirer, Alicia; Hellwig, Petra; Jeschke, Gunnar; Hilvert, Donald

2016-05-01

Insoluble amyloid fibers represent a pathological signature of many human diseases. To treat such diseases, inhibition of amyloid formation has been proposed as a possible therapeutic strategy. d-Peptides, which possess high proteolytic stability and lessened immunogenicity, are attractive candidates in this context. However, a molecular understanding of chiral recognition phenomena for d-peptides and l-amyloids is currently incomplete. Here we report experiments on amyloid growth of individual enantiomers and their mixtures for two distinct polypeptide systems of different length and structural organization: a 44-residue covalently-linked dimer derived from a peptide corresponding to the [20-41]-fragment of human β2-microglobulin (β2m) and the 99-residue full-length protein. For the dimeric [20-41]β2m construct, a combination of electron paramagnetic resonance of nitroxide-labeled constructs and (13) C-isotope edited FT-IR spectroscopy of (13) C-labeled preparations was used to show that racemic mixtures precipitate as intact homochiral fibers, i.e. undergo spontaneous Pasteur-like resolution into a mixture of left- and right-handed amyloids. In the case of full-length β2m, the presence of the mirror-image d-protein affords morphologically distinct amyloids that are composed largely of enantiopure domains. Removal of the l-component from hybrid amyloids by proteolytic digestion results in their rapid transformation into characteristic long straight d-β2m amyloids. Furthermore, the full-length d-enantiomer of β2m was found to be an efficient inhibitor of l-β2m amyloid growth. This observation highlights the potential of longer d-polypeptides for future development into inhibitors of amyloid propagation. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Augmenting Amyloid PET Interpretations With Quantitative Information Improves Consistency of Early Amyloid Detection.

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Harn, Nicholas R; Hunt, Suzanne L; Hill, Jacqueline; Vidoni, Eric; Perry, Mark; Burns, Jeffrey M

2017-08-01

Establishing reliable methods for interpreting elevated cerebral amyloid-β plaque on PET scans is increasingly important for radiologists, as availability of PET imaging in clinical practice increases. We examined a 3-step method to detect plaque in cognitively normal older adults, focusing on the additive value of quantitative information during the PET scan interpretation process. Fifty-five F-florbetapir PET scans were evaluated by 3 experienced raters. Scans were first visually interpreted as having "elevated" or "nonelevated" plaque burden ("Visual Read"). Images were then processed using a standardized quantitative analysis software (MIMneuro) to generate whole brain and region of interest SUV ratios. This "Quantitative Read" was considered elevated if at least 2 of 6 regions of interest had an SUV ratio of more than 1.1. The final interpretation combined both visual and quantitative data together ("VisQ Read"). Cohen kappa values were assessed as a measure of interpretation agreement. Plaque was elevated in 25.5% to 29.1% of the 165 total Visual Reads. Interrater agreement was strong (kappa = 0.73-0.82) and consistent with reported values. Quantitative Reads were elevated in 45.5% of participants. Final VisQ Reads changed from initial Visual Reads in 16 interpretations (9.7%), with most changing from "nonelevated" Visual Reads to "elevated." These changed interpretations demonstrated lower plaque quantification than those initially read as "elevated" that remained unchanged. Interrater variability improved for VisQ Reads with the addition of quantitative information (kappa = 0.88-0.96). Inclusion of quantitative information increases consistency of PET scan interpretations for early detection of cerebral amyloid-β plaque accumulation.

Proteomic screening for amyloid proteins.

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Anton A Nizhnikov

Full Text Available Despite extensive study, progress in elucidation of biological functions of amyloids and their role in pathology is largely restrained due to the lack of universal and reliable biochemical methods for their discovery. All biochemical methods developed so far allowed only identification of glutamine/asparagine-rich amyloid-forming proteins or proteins comprising amyloids that form large deposits. In this article we present a proteomic approach which may enable identification of a broad range of amyloid-forming proteins independently of specific features of their sequences or levels of expression. This approach is based on the isolation of protein fractions enriched with amyloid aggregates via sedimentation by ultracentrifugation in the presence of strong ionic detergents, such as sarkosyl or SDS. Sedimented proteins are then separated either by 2D difference gel electrophoresis or by SDS-PAGE, if they are insoluble in the buffer used for 2D difference gel electrophoresis, after which they are identified by mass-spectrometry. We validated this approach by detection of known yeast prions and mammalian proteins with established capacity for amyloid formation and also revealed yeast proteins forming detergent-insoluble aggregates in the presence of human huntingtin with expanded polyglutamine domain. Notably, with one exception, all these proteins contained glutamine/asparagine-rich stretches suggesting that their aggregates arose due to polymerization cross-seeding by human huntingtin. Importantly, though the approach was developed in a yeast model, it can easily be applied to any organism thus representing an efficient and universal tool for screening for amyloid proteins.

Interaction of magnetic nanoparticles with lysozyme amyloid fibrils

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Gdovinová, Veronika [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Tomašovičová, Natália, E-mail: nhudak@saske.sk [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Batko, Ivan; Batková, Marianna; Balejčíková, Lucia [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia); Garamus, Vasyl M. [Helmholtz-Zentrum Geesthacht: Zentrum fr Material, und Kstenforschung GmbH, Max-Plank-Strae 1, Geesthacht 216502 (Germany); Petrenko, Viktor I. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Physics Department, Taras Shevchenko Kyiv National University, Volodymyrska Street 64, 01601 Kyiv (Ukraine); Avdeev, Mikhail V. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Kopčanský, Peter [Institute of Experimental Physics SAS, Watsonova 47, 040 01 Košice (Slovakia)

2017-06-01

This work is devoted to the structural study of complex solutions of magnetic nanoparticles with lysozyme amyloid fibrils due to possible ordering of such system by applying the external magnetic field. The interaction of magnetic nanoparticles with amyloid fibrils has been followed by atomic force microscopy and small-angle X-ray scattering. It has been observed that magnetic nanoparticles (MNPs) adsorb to lysozyme amyloid fibrils. It was found that MNPs alter amyloids structures, namely the diameter of lysozyme amyloid fibrils is increased whereas the length of fibrils is decreased. In the same time MNPs do not change the helical pitch significantly. - Highlights: • Solution of MNPs with lysozyme amyloid fibrils was characterized by AFM and SAXS. • MNPs adsorb to lysozyme amyloid fibrils. • Diameter and size of lysozyme amyloid fibrils change due to doping with MNPs.

Key aromatic/hydrophobic amino acids controlling a cross-amyloid peptide interaction versus amyloid self-assembly.

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Bakou, Maria; Hille, Kathleen; Kracklauer, Michael; Spanopoulou, Anna; Frost, Christina V; Malideli, Eleni; Yan, Li-Mei; Caporale, Andrea; Zacharias, Martin; Kapurniotu, Aphrodite

2017-09-01

The interaction of the intrinsically disordered polypeptide islet amyloid polypeptide (IAPP), which is associated with type 2 diabetes (T2D), with the Alzheimer's disease amyloid-β (Aβ) peptide modulates their self-assembly into amyloid fibrils and may link the pathogeneses of these two cell-degenerative diseases. However, the molecular determinants of this interaction remain elusive. Using a systematic alanine scan approach, fluorescence spectroscopy, and other biophysical methods, including heterocomplex pulldown assays, far-UV CD spectroscopy, the thioflavin T binding assay, transmission EM, and molecular dynamics simulations, here we identified single aromatic/hydrophobic residues within the amyloid core IAPP region as hot spots or key residues of its cross-interaction with Aβ40(42) peptide. Importantly, we also find that none of these residues in isolation plays a key role in IAPP self-assembly, whereas simultaneous substitution of four aromatic/hydrophobic residues with Ala dramatically impairs both IAPP self-assembly and hetero-assembly with Aβ40(42). Furthermore, our experiments yielded several novel IAPP analogs, whose sequences are highly similar to that of IAPP but have distinct amyloid self- or cross-interaction potentials. The identified similarities and major differences controlling IAPP cross-peptide interaction with Aβ40(42) versus its amyloid self-assembly offer a molecular basis for understanding the underlying mechanisms. We propose that these insights will aid in designing intervention strategies and novel IAPP analogs for the management of type 2 diabetes, Alzheimer's disease, or other diseases related to IAPP dysfunction or cross-amyloid interactions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

AL amyloid imaging and therapy with a monoclonal antibody to a cryptic epitope on amyloid fibrils.

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Jonathan S Wall

Full Text Available The monoclonal antibody 2A4 binds an epitope derived from a cleavage site of serum amyloid protein A (sAA containing a -Glu-Asp- amino acid pairing. In addition to its reactivity with sAA amyloid deposits, the antibody was also found to bind amyloid fibrils composed of immunoglobulin light chains. The antibody binds to synthetic fibrils and human light chain (AL amyloid extracts with high affinity even in the presence of soluble light chain proteins. Immunohistochemistry with biotinylated 2A4 demonstrated positive reaction with ALκ and ALλ human amyloid deposits in various organs. Surface plasmon resonance analyses using synthetic AL fibrils as a substrate revealed that 2A4 bound with a K(D of ∼10 nM. Binding was inhibited in the presence of the -Glu-Asp- containing immunogen peptide. Radiolabeled 2A4 specifically localized with human AL amyloid extracts implanted in mice (amyloidomas as evidenced by single photon emission (SPECT imaging. Furthermore, co-localization of the radiolabeled mAb with amyloid was shown in biodistribution and micro-autoradiography studies. Treatment with 2A4 expedited regression of ALκ amyloidomas in mice, likely mediated by the action of macrophages and neutrophils, relative to animals that received a control antibody. These data indicate that the 2A4 mAb might be of interest for potential imaging and immunotherapy in patients with AL amyloidosis.

Amyloid-β Peptide Induces Prion Protein Amyloid Formation: Evidence for Its Widespread Amyloidogenic Effect.

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Honda, Ryo

2018-04-12

Transmissible spongiform encephalopathy is associated with misfolding of prion protein (PrP) into an amyloid β-rich aggregate. Previous studies have indicated that PrP interacts with Alzheimer's disease amyloid-β peptide (Aβ), but it remains elusive how this interaction impacts on the misfolding of PrP. This study presents the first in vitro evidence that Aβ induces PrP-amyloid formation at submicromolar concentrations. Interestingly, systematic mutagenesis of PrP revealed that Aβ requires no specific amino acid sequences in PrP, and induces the misfolding of other unrelated proteins (insulin and lysozyme) into amyloid fibrils in a manner analogous to PrP. This unanticipated nonspecific amyloidogenic effect of Aβ indicates that this peptide might be involved in widespread protein aggregation, regardless of the amino acid sequences of target proteins, and exacerbate the pathology of many neurodegenerative diseases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amyloid-degrading ability of nattokinase from Bacillus subtilis natto.

Science.gov (United States)

Hsu, Ruei-Lin; Lee, Kung-Ta; Wang, Jung-Hao; Lee, Lily Y-L; Chen, Rita P-Y

2009-01-28

More than 20 unrelated proteins can form amyloid fibrils in vivo which are related to various diseases, such as Alzheimer's disease, prion disease, and systematic amyloidosis. Amyloid fibrils are an ordered protein aggregate with a lamellar cross-beta structure. Enhancing amyloid clearance is one of the targets of the therapy of these amyloid-related diseases. Although there is debate on whether the toxicity is due to amyloids or their precursors, research on the degradation of amyloids may help prevent or alleviate these diseases. In this study, we explored the amyloid-degrading ability of nattokinase, a fibrinolytic subtilisin-like serine protease, and determined the optimal conditions for amyloid hydrolysis. This ability is shared by proteinase K and subtilisin Carlsberg, but not by trypsin or plasmin.

Amyloid beta peptide immunotherapy in Alzheimer disease.

Science.gov (United States)

Delrieu, J; Ousset, P J; Voisin, T; Vellas, B

2014-12-01

Recent advances in the understanding of Alzheimer's disease pathogenesis have led to the development of numerous compounds that might modify the disease process. Amyloid β peptide represents an important molecular target for intervention in Alzheimer's disease. The main purpose of this work is to review immunotherapy studies in relation to the Alzheimer's disease. Several types of amyloid β peptide immunotherapy for Alzheimer's disease are under investigation, active immunization and passive administration with monoclonal antibodies directed against amyloid β peptide. Although immunotherapy approaches resulted in clearance of amyloid plaques in patients with Alzheimer's disease, this clearance did not show significant cognitive effect for the moment. Currently, several amyloid β peptide immunotherapy approaches are under investigation but also against tau pathology. Results from amyloid-based immunotherapy studies in clinical trials indicate that intervention appears to be more effective in early stages of amyloid accumulation in particular solanezumab with a potential impact at mild Alzheimer's disease, highlighting the importance of diagnosing Alzheimer's disease as early as possible and undertaking clinical trials at this stage. In both phase III solanezumab and bapineuzumab trials, PET imaging revealed that about a quarter of patients lacked fibrillar amyloid pathology at baseline, suggesting that they did not have Alzheimer's disease in the first place. So a new third phase 3 clinical trial for solanezumab, called Expedition 3, in patients with mild Alzheimer's disease and evidence of amyloid burden has been started. Thus, currently, amyloid intervention is realized at early stage of the Alzheimer's disease in clinical trials, at prodromal Alzheimer's disease, or at asymptomatic subjects or at risk to develop Alzheimer's disease and or at asymptomatic subjects with autosomal dominant mutation. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Chemical Methods to Knock Down the Amyloid Proteins

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Na Gao

2017-06-01

Full Text Available Amyloid proteins are closely related with amyloid diseases and do tremendous harm to human health. However, there is still a lack of effective strategies to treat these amyloid diseases, so it is important to develop novel methods. Accelerating the clearance of amyloid proteins is a favorable method for amyloid disease treatment. Recently, chemical methods for protein reduction have been developed and have attracted much attention. In this review, we focus on the latest progress of chemical methods that knock down amyloid proteins, including the proteolysis-targeting chimera (PROTAC strategy, the “recognition-cleavage” strategy, the chaperone-mediated autophagy (CMA strategy, the selectively light-activatable organic and inorganic molecules strategy and other chemical strategies.

Nuclear imaging of amyloid deposits based upon thioflavins

International Nuclear Information System (INIS)

Wang Yanming; Wu Chunying; Wei Jinjun

2005-01-01

Alzheimer's Disease (AD) is a chronic neurodegenerative disorders characterized by the presence of amyloid deposits and neurofibrillar tangles in the brain. Direct assessment of local changes of amyloid deposits in vivo would greatly facilitate the diagnosis and therapeutic treatments of AD. The goal of this study is to develop small-molecule probes that can be used to follow amyloid deposition in vivo in patients with neurodegenerative diseases. Over the past years, we set out to develop a series of small molecules based on thioflavins as radiotracers for use in nuclear imaging modalities such as positron emission tomography and single photon emission computed tomography. The potential of these amyloid-imaging agents for in vivo studies of amyloid deposition has been evaluated based on the following methods: 1) spectrophotometric binding. assays with synthetic amyloid-β (Aβ) fibrils and AD brain homogenates; 2) fluorescent staining of brain tissue sections to evaluate specificity of binding to amyloid deposits; 3) fluorescent microscopy in mouse models to determine the brain permeability and characterize the binding specificity in vivo, and 4) PET studies in human subjects diagnosed with AD and age-matched control subjects. To date, we have identified some lead compounds as molecular probes with specificity towards amyloid deposits. The in vitro and in vivo binding properties of these compounds have been demonstrated in the following ways: 1) they selectively binds to Aβ fibrils; 2) they selectively stains amyloid deposits in AD brain tissue sections; 3) they readily penetrates the blood-brain barrier, selectively detects amyloid deposits in vivo iri living mice; and 4) One of these compounds, termed PIB, has been successfully used in PET studies in human subjects. In conclusion, amyloid-imaging probes have been developed that could be used to monitor amyloid load in vivo. Applications of the probes are under investigation for potential pathophysiology studies

Specific localization and imaging of amyloid deposits in vivo using 123I-labeled serum amyloid P component

International Nuclear Information System (INIS)

Hawkins, P.N.; Myers, M.J.; Epenetos, A.A.; Caspi, D.; Pepys, M.B.

1988-01-01

Highly specific, high-resolution scintigraphic images of amyloid-laden organs in mice with experimentally induced amyloid A protein (AA) amyloidosis were obtained after intravenous injection of 123 I-labeled serum amyloid P component (SAP). Interestingly, a much higher proportion (up to 40%) of the injected dose of heterologous human SAP localized to amyloid and was retained there than was the case with isologous mouse SAP, indicating that human SAP binds more avidly to mouse AA fibrils than does mouse SAP. Specificity of SAP localization was established by the failure of the related proteins, human C-reactive protein and Limulus C-reactive protein, to deposit significantly in amyloid and by the absence of human SAP deposition in nonamyloidotic organs. However, only partial correlations were observed between the quantity of SAP localized and two independent estimates, histology and RIA for AA of the amount of amyloid in particular organs. It is not clear which of the three methods used reflects better the extent or clinical significance of the amyloid deposits but in vivo localization of radiolabeled SAP, detectable and quantifiable by gamma camera imaging, is apparently extremely sensitive. These findings establish the use of labeled SAP as a noninvasive in vivo diagnostic probe in experimental amyloidosis, potentially capable of revealing the natural history of the condition, and suggest that it may also be applicable generally as a specific targeting agent for diagnostic and even therapeutic purposes in clinical amyloidosis

Towards Alzheimer's beta-amyloid vaccination.

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Frenkel, D; Solomon, B

2001-01-01

Beta-amyloid pathology, the main hallmark of Alzheimer's disease (AD), has been linked to its conformational status and aggregation. We recently showed that site-directed monoclonal antibodies (mAbs) towards the N-terminal region of the human beta-amyloid peptide bind to preformed beta-amyloid fibrils (Abeta), leading to disaggregation and inhibition of their neurotoxic effect. Here we report the development of a novel immunization procedure to raise effective anti-aggregating amyloid beta-protein (AbetaP) antibodies, using as antigen filamentous phages displaying the only EFRH peptide found to be the epitope of these antibodies. Due to the high antigenicity of the phage no adjuvant is required to obtain high affinity anti-aggregating IgG antibodies in animals model, that exhibit identity to human AbetaP. Such antibodies are able to sequester peripheral AbetaP, thus avoiding passage through the blood brain barrier (BBB) and, as recently shown in a transgenic mouse model, to cross the BBB and dissolve already formed beta-amyloid plaques. To our knowledge, this is the first attempt to use as a vaccine a self-anti-aggregating epitope displayed on a phage, and this may pave the way to treat abnormal accumulation-peptide diseases, such as Alzheimer's disease or other amyloidogenic diseases. Copyright 2001 The International Association for Biologicals.

Human Islet Amyloid Polypeptide

DEFF Research Database (Denmark)

Kosicka, Iga

2014-01-01

Diabetes mellitus type II is a metabolic disease affecting millions of people worldwide. The disease is associated with occurence of insoluble, fibrillar, protein aggregates in islets of Langerhans in the pancreas - islet amyloid. The main constituent of these protein fibers is the human islet...... of diabetes type II, while revealing the structure(s) of islet amyloid fibrils is necessary for potential design of therapeutic agents....

Strong transthyretin immunostaining: potential pitfall in cardiac amyloid typing.

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Satoskar, Anjali A; Efebera, Yvonne; Hasan, Ayesha; Brodsky, Sergey; Nadasdy, Gyongyi; Dogan, Ahmet; Nadasdy, Tibor

2011-11-01

Although systemic amyloidosis commonly presents with renal disease, cardiac involvement usually determines the patient's prognosis. Cardiac involvement is seen in light chain amyloid and transthyretin amyloidosis. Distinguishing between these two is critical because prognosis and treatment differ. Our study demonstrates the unreliability of transthyretin immunostaining in subtyping cardiac amyloid. Between January 2003 and August 2010, we retrieved 229 native endomyocardial biopsies, of which 24 had amyloid. Immunohistochemistry for κ, λ, transthyretin, and serum amyloid A protein was performed on formalin-fixed, paraffin-embedded sections. Staining was graded as weak (trace to 1+) or strong (2 to 3+). Mass spectrometry (MS)-based proteomic typing of microdissected amyloid material was performed on selected cases. Fifteen patients had monoclonal gammopathy/plasma cell dyscrasia with cardiac amyloid. Eight of them (53%) showed strong transthyretin staining in the cardiac amyloid deposits. MS was performed in 5 of these 8 biopsies, and all 5 biopsies revealed light chain amyloid-type amyloid. Two of these 5 light chain amyloid biopsies did not even have concomitant strong staining for the appropriate light chain. Among the 15 cases with plasma cell dyscrasia, only 7 biopsies showed strong staining for the corresponding monoclonal light chain. Strong, false-positive immunostaining for transthyretin in cardiac amyloid is a potential pitfall, augmented by the frequent lack of staining for immunoglobulin light chains. Therefore, the presence of amyloid in the cardiac biopsy should prompt a search for plasma cell dyscrasia irrespective of transthyretin staining. Confirmation with MS should be sought, particularly if there is any discrepancy between κ/λ staining and serum immunofixation results.

Bilateral metachronous periosteal tibial amyloid tumors

International Nuclear Information System (INIS)

Murata, H.; Kusuzaki, Katsuyuki; Hashiguchi, S.; Ueda, Hidetaka; Hirasawa, Yasusuke

2000-01-01

Localized primary periosteal amyloid tumors are extremely rare. A case of bilateral tibial amyloid tumor is presented. A 62-year-old woman initially presented with a painful mass in the anterior aspect of the right leg. There was no evidence of underlying systemic disease, including chronic infection or malignancy. Based on the results of resistance with Congo red staining to treatment with potassium permanganate and positivity for kappa light chain, we classified this particular case as AL-type amyloidosis. The patient noticed a swelling in the opposite leg 2 years later. The second tumor was also an AL-type amyloidoma. Amyloid tumors are generally solitary. This is the first case of bilateral periosteal amyloid tumors of the AL-type occurring in the tibiae. (orig.)

Imaging β-amyloid fibrils in Alzheimer's disease: a critical analysis through simulation of amyloid fibril polymerization

International Nuclear Information System (INIS)

Shoghi-Jadid, Kooresh; Barrio, Jorge R.; Kepe, Vladimir; Wu, H.-M.; Small, Gary W.; Phelps, Michael E.; Huang, S.-C.

2005-01-01

The polymerization of β-amyloid (Aβ) peptides into fibrillary plaques is implicated, in part, in the pathogenesis of Alzheimer's disease. Aβ molecular imaging probes (Aβ-MIPs) have been introduced in an effort to quantify amyloid burden or load, in subjects afflicted with AD by invoking the classic PET receptor model for the quantitation of neuronal receptor density. In this communication, we explore conceptual differences between imaging the density of amyloid fibril polymers and neuronal receptors. We formulate a mathematical model for the polymerization of Aβ with parameters that are mapped to biological modulators of fibrillogenesis and introduce a universal measure for amyloid load to accommodate various interactions of Aβ-MIPs with fibrils. Subsequently, we hypothesize four Aβ-MIPs and utilize the fibrillogenesis model to simulate PET tissue time activity curves (TACs). Given the unique nature of polymer growth and resulting PET TAC, the four probes report differing amyloid burdens for a given brain pathology, thus complicating the interpretation of PET images. In addition, we introduce the notion of an MIP's resolution, apparent maximal binding site concentration, optimal kinetic topology and its resolving power in characterizing the pathological progression of AD and the effectiveness of drug therapy. The concepts introduced in this work call for a new paradigm that goes beyond the classic parameters B max and K D to include binding characteristics to polymeric peptide aggregates such as amyloid fibrils, neurofibrillary tangles and prions

Adherence to the Mediterranean Diet Is not Related to Beta-Amyloid Deposition: Data from the Women's Healthy Ageing Project.

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Hill, E; Szoeke, C; Dennerstein, L; Campbell, S; Clifton, P

2018-01-01

Research has indicated the neuroprotective potential of the Mediterranean diet. Adherence to the Mediterranean diet has shown preventative potential for Alzheimer's disease incidence and prevalence, yet few studies have investigated the impact of Mediterranean diet adherence on the hallmark protein; beta-amyloid. To investigate the association between Mediterranean diet adherence and beta-amyloid deposition in a cohort of healthy older Australian women. This study was a cross-sectional investigation of participants from the longitudinal, epidemiologically sourced Women's Healthy Ageing Project which is a follow-up of the Melbourne Women's Midlife Health Project. Assessments were conducted at the Centre for Medical Research, Royal Melbourne Hospital in Melbourne, Australia. F-18 Florbetaben positron emission tomography scanning was conducted at the Austin Centre for PET in Victoria, Australia. One hundred and eleven Women's Healthy Ageing Project participants were included in the study. Mediterranean diet adherence scores for all participants were calculated from the administration of a validated food frequency questionnaire constructed by the Cancer Council of Victoria. Beta-amyloid deposition was measured using positron emission tomography standardised uptake value ratios. Gamma regression analysis displayed no association between Mediterranean diet adherence and beta-amyloid deposition. This result was consistent across APOE-ε4 +/- cohorts and with the inclusion of covariates such as age, education, body mass index and cognition. This study found no association between adherence to the Mediterranean diet and beta-amyloid deposition in a cohort of healthy Australian women.

Halogenation dictates the architecture of amyloid peptide nanostructures.

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Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

2017-07-20

Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

Amyloid PET in neurodegenerative diseases with dementia.

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Camacho, V; Gómez-Grande, A; Sopena, P; García-Solís, D; Gómez Río, M; Lorenzo, C; Rubí, S; Arbizu, J

2018-05-15

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary tangles are a neuropathological hallmark of AD that produces synaptic dysfunction and culminates later in neuronal loss. Amyloid PET is a useful, available and non-invasive technique that provides in vivo information about the cortical amyloid burden. In the latest revised criteria for the diagnosis of AD biomarkers were defined and integrated: pathological and diagnostic biomarkers (increased retention on fibrillar amyloid PET or decreased Aβ 1-42 and increased T-Tau or P-Tau in CSF) and neurodegeneration or topographical biomarkers (temporoparietal hypometabolism on 18 F-FDG PET and temporal atrophy on MRI). Recently specific recommendations have been created as a consensus statement on the appropriate use of the imaging biomarkers, including amyloid PET: early-onset cognitive impairment/dementia, atypical forms of AD, mild cognitive impairment with early age of onset, and to differentiate between AD and other neurodegenerative diseases that occur with dementia. Amyloid PET is also contributing to the development of new therapies for AD, as well as in research studies for the study of other neurodegenerative diseases that occur with dementia where the deposition of Aβ amyloid is involved in its pathogenesis. In this paper, we review some general concepts and study the use of amyloid PET in depth and its relationship with neurodegenerative diseases and other diagnostic techniques. Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.

A Peptide-Fc Opsonin with Pan-Amyloid Reactivity

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James S. Foster

2017-09-01

Full Text Available There is a continuing need for therapeutic interventions for patients with the protein misfolding disorders that result in systemic amyloidosis. Recently, specific antibodies have been employed to treat AL amyloidosis by opsonizing tissue amyloid deposits thereby inducing cell-mediated dissolution and organ improvement. To develop a pan-amyloid therapeutic agent, we have produced an Fc-fusion product incorporating a peptide, p5, which binds many if not all forms of amyloid. This protein, designated Fcp5, expressed in mammalian cells, forms the desired bivalent dimer structure and retains pan-amyloid reactivity similar to the p5 peptide as measured by immunosorbent assays, immunohistochemistry, surface plasmon resonance, and pulldown assays using radioiodinated Fcp5. Additionally, Fcp5 was capable of opsonizing amyloid fibrils in vitro using a pH-sensitive fluorescence assay of phagocytosis. In mice,125 I-labeled Fcp5 exhibited an extended serum circulation time, relative to the p5 peptide. It specifically bound AA amyloid deposits in diseased mice, as evidenced by biodistribution and microautoradiographic methods, which coincided with an increase in active, Iba-1-positive macrophages in the liver at 48 h postinjection of Fcp5. In healthy mice, no specific tissue accumulation was observed. The data indicate that polybasic, pan-amyloid-targeting peptides, in the context of an Fc fusion, can yield amyloid reactive, opsonizing reagents that may serve as next-generation immunotherapeutics.

Rates of Amyloid Imaging Positivity in Patients With Primary Progressive Aphasia

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Santos-Santos, Miguel A.; Rabinovici, Gil D.; Iaccarino, Leonardo; Ayakta, Nagehan; Tammewar, Gautam; Lobach, Iryna; Henry, Maya L.; Hubbard, Isabel; Mandelli, Maria Luisa; Spinelli, Edoardo; Miller, Zachary A.; Pressman, Peter S.; O’Neil, James P.; Ghosh, Pia; Lazaris, Andreas; Meyer, Marita; Watson, Christa; Yoon, Soo Jin; Rosen, Howard J.; Grinberg, Lea; Seeley, William W.; Miller, Bruce L.; Jagust, William J.; Gorno-Tempini, Maria Luisa

2018-01-01

IMPORTANCE The ability to predict the pathology underlying different neurodegenerative syndromes is of critical importance owing to the advent of molecule-specific therapies. OBJECTIVE To determine the rates of positron emission tomography (PET) amyloid positivity in the main clinical variants of primary progressive aphasia (PPA). DESIGN, SETTING, AND PARTICIPANTS This prospective clinical-pathologic case series was conducted at a tertiary research clinic specialized in cognitive disorders. Patients were evaluated as part of a prospective, longitudinal research study between January 2002 and December 2015. Inclusion criteria included clinical diagnosis of PPA; availability of complete speech, language, and cognitive testing; magnetic resonance imaging performed within 6 months of the cognitive evaluation; and PET carbon 11–labeled Pittsburgh Compound-B or florbetapir F 18 brain scan results. Of 109 patients referred for evaluation of language symptoms who underwent amyloid brain imaging, 3 were excluded because of incomplete language evaluations, 5 for absence of significant aphasia, and 12 for presenting with significant initial symptoms outside of the language domain, leaving a cohort of 89 patients with PPA. MAIN OUTCOMES AND MEASURES Clinical, cognitive, neuroimaging, and pathology results. RESULTS Twenty-eight cases were classified as imaging-supported semantic variant PPA (11 women [39.3%]; mean [SD] age, 64 [7] years), 31 nonfluent/agrammatic variant PPA (22 women [71.0%]; mean [SD] age, 68 [7] years), 26 logopenic variant PPA (17 women [65.4%]; mean [SD] age, 63 [8] years), and 4 mixed PPA cases. Twenty-four of 28 patients with semantic variant PPA (86%) and 28 of 31 patients with nonfluent/agrammatic variant PPA (90%) had negative amyloid PET scan results, while 25 of 26 patients with logopenic variant PPA (96%) and 3 of 4 mixed PPA cases (75%) had positive scan results. The amyloid positive semantic variant PPA and nonfluent/agrammatic variant PPA cases

Stable, metastable, and kinetically trapped amyloid aggregate phases.

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Miti, Tatiana; Mulaj, Mentor; Schmit, Jeremy D; Muschol, Martin

2015-01-12

Self-assembly of proteins into amyloid fibrils plays a key role in a multitude of human disorders that range from Alzheimer's disease to type II diabetes. Compact oligomeric species, observed early during amyloid formation, are reported as the molecular entities responsible for the toxic effects of amyloid self-assembly. However, the relation between early-stage oligomeric aggregates and late-stage rigid fibrils, which are the hallmark structure of amyloid plaques, has remained unclear. We show that these different structures occupy well-defined regions in a peculiar phase diagram. Lysozyme amyloid oligomers and their curvilinear fibrils only form after they cross a salt and protein concentration-dependent threshold. We also determine a boundary for the onset of amyloid oligomer precipitation. The oligomeric aggregates are structurally distinct from rigid fibrils and are metastable against nucleation and growth of rigid fibrils. These experimentally determined boundaries match well with colloidal model predictions that account for salt-modulated charge repulsion. The model also incorporates the metastable and kinetic character of oligomer phases. Similarities and differences of amyloid oligomer assembly to metastable liquid-liquid phase separation of proteins and to surfactant aggregation are discussed.

A method for probing the mutational landscape of amyloid structure.

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O'Donnell, Charles W; Waldispühl, Jérôme; Lis, Mieszko; Halfmann, Randal; Devadas, Srinivas; Lindquist, Susan; Berger, Bonnie

2011-07-01

Proteins of all kinds can self-assemble into highly ordered β-sheet aggregates known as amyloid fibrils, important both biologically and clinically. However, the specific molecular structure of a fibril can vary dramatically depending on sequence and environmental conditions, and mutations can drastically alter amyloid function and pathogenicity. Experimental structure determination has proven extremely difficult with only a handful of NMR-based models proposed, suggesting a need for computational methods. We present AmyloidMutants, a statistical mechanics approach for de novo prediction and analysis of wild-type and mutant amyloid structures. Based on the premise of protein mutational landscapes, AmyloidMutants energetically quantifies the effects of sequence mutation on fibril conformation and stability. Tested on non-mutant, full-length amyloid structures with known chemical shift data, AmyloidMutants offers roughly 2-fold improvement in prediction accuracy over existing tools. Moreover, AmyloidMutants is the only method to predict complete super-secondary structures, enabling accurate discrimination of topologically dissimilar amyloid conformations that correspond to the same sequence locations. Applied to mutant prediction, AmyloidMutants identifies a global conformational switch between Aβ and its highly-toxic 'Iowa' mutant in agreement with a recent experimental model based on partial chemical shift data. Predictions on mutant, yeast-toxic strains of HET-s suggest similar alternate folds. When applied to HET-s and a HET-s mutant with core asparagines replaced by glutamines (both highly amyloidogenic chemically similar residues abundant in many amyloids), AmyloidMutants surprisingly predicts a greatly reduced capacity of the glutamine mutant to form amyloid. We confirm this finding by conducting mutagenesis experiments. Our tool is publically available on the web at http://amyloid.csail.mit.edu/. lindquist_admin@wi.mit.edu; bab@csail.mit.edu.

Amyloid-PET burden and regional distribution in cerebral amyloid angiopathy: a systematic review and meta-analysis of biomarker performance.

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Charidimou, Andreas; Farid, Karim; Tsai, Hsin-Hsi; Tsai, Li-Kai; Yen, Rouh-Fang; Baron, Jean-Claude

2018-04-01

We performed a meta-analysis to synthesise current evidence on amyloid-positron emission tomography (PET) burden and presumed preferential occipital distribution in sporadic cerebral amyloid angiopathy (CAA). In a PubMed systematic search, we identified case-control studies with extractable data on global and occipital-to-global amyloid-PET uptake in symptomatic patients with CAA (per Boston criteria) versus control groups (healthy participants or patients with non-CAA deep intracerebral haemorrhage) and patients with Alzheimer's disease. To circumvent PET studies' methodological variation, we generated and used 'fold change', that is, ratio of mean amyloid uptake (global and occipital-to-global) of CAA relative to comparison groups. Amyloid-PET uptake biomarker performance was then quantified by random-effects meta-analysis on the ratios of the means. A ratio >1 indicates that amyloid-PET uptake (global or occipital/global) is higher in CAA than comparison groups, and a ratio 90% with probable CAA) and 138 controls (96 healthy elderly, 42 deep intracerebral haemorrhage controls) and 72 patients with Alzheimer's disease, were included. Global amyloid-PET ratio between patients with CAA and controls was above 1, with an average effect size of 1.18 (95% CI 1.08 to 1.28; pPET uptake ratio did not differ between patients with CAA versus patients with deep intracerebral haemorrhage or healthy controls. By contrast, occipital-to-global amyloid-PET uptake ratio was above 1 in patients with CAA versus those with Alzheimer's disease, with an average ratio of 1.10 (95% CI 1.03 to 1.19; p=0.009) and high statistical heterogeneity. Our analysis provides exploratory actionable data on the overall effect sizes and strength of amyloid-PET burden and distribution in patients with CAA, useful for future larger studies. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless

Amyloid in basal cell carcinoma and seborrheic keratosis

DEFF Research Database (Denmark)

Olsen, K E; Westermark, Per

1994-01-01

The frequency of amyloid substance was studied in two different types of skin tumours: basal cell carcinoma and seborrheic keratosis. In 9 out of 49 cases of seborrheic keratosis amyloid substance was found. In the basal cell carcinomas, 194 out of 260 cases showed amyloid deposits, a rate...

Amyloid-β and Astrocytes Interplay in Amyloid-β Related Disorders

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Yazan S. Batarseh

2016-03-01

Full Text Available Amyloid-β (Aβ pathology is known to promote chronic inflammatory responses in the brain. It was thought previously that Aβ is only associated with Alzheimer’s disease and Down syndrome. However, studies have shown its involvement in many other neurological disorders. The role of astrocytes in handling the excess levels of Aβ has been highlighted in the literature. Astrocytes have a distinctive function in both neuronal support and protection, thus its involvement in Aβ pathological process may tip the balance toward chronic inflammation and neuronal death. In this review we describe the involvement of astrocytes in Aβ related disorders including Alzheimer’s disease, Down syndrome, cerebral amyloid angiopathy, and frontotemporal dementia.

Apolipoprotein E Regulates Amyloid Formation within Endosomes of Pigment Cells

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Guillaume van Niel

2015-10-01

Full Text Available Accumulation of toxic amyloid oligomers is a key feature in the pathogenesis of amyloid-related diseases. Formation of mature amyloid fibrils is one defense mechanism to neutralize toxic prefibrillar oligomers. This mechanism is notably influenced by apolipoprotein E variants. Cells that produce mature amyloid fibrils to serve physiological functions must exploit specific mechanisms to avoid potential accumulation of toxic species. Pigment cells have tuned their endosomes to maximize the formation of functional amyloid from the protein PMEL. Here, we show that ApoE is associated with intraluminal vesicles (ILV within endosomes and remain associated with ILVs when they are secreted as exosomes. ApoE functions in the ESCRT-independent sorting mechanism of PMEL onto ILVs and regulates the endosomal formation of PMEL amyloid fibrils in vitro and in vivo. This process secures the physiological formation of amyloid fibrils by exploiting ILVs as amyloid nucleating platforms.

Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology

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Rehana Akter

2016-01-01

Full Text Available The hormone islet amyloid polypeptide (IAPP, or amylin plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to β-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced β-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of β-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.

Establishing and validating the fluorescent amyloid ligand h-FTAA (heptamer formyl thiophene acetic acid) to identify transthyretin amyloid deposits in carpal tunnel syndrome.

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Hahn, Katharina; Nilsson, K Peter R; Hammarström, Per; Urban, Peter; Meliss, Rolf Rüdiger; Behrens, Hans-Michael; Krüger, Sandra; Röcken, Christoph

2017-06-01

Transthyretin-derived (ATTR) amyloidosis is a frequent finding in carpal tunnel syndrome. We tested the following hypotheses: the novel fluorescent amyloid ligand heptameric formic thiophene acetic acid (h-FTAA) has a superior sensitivity for the detection of amyloid compared with Congo red-staining; Amyloid load correlates with patient gender and/or patient age. We retrieved 208 resection specimens obtained from 184 patients with ATTR amyloid in the carpal tunnel. Serial sections were stained with Congo red, h-FTAA and an antibody directed against transthyretin (TTR). Stained sections were digitalized and forwarded to computational analyses. The amount of amyloid was correlated with patient demographics. Amyloid stained intensely with h-FTAA and an anti-TTR-antibody. Congo red-staining combined with fluorescence microscopy was significantly less sensitive than h-FTAA-fluorescence and TTR-immunostaining: the highest percentage area was found in TTR-immunostained sections, followed by h-FTAA and Congo red. The Pearson correlation coefficient was .8 (Congo red vs. h-FTAA) and .9 (TTR vs. h-FTAA). Amyloid load correlated with patient gender, anatomical site and patient age. h-FTAA is a highly sensitive method to detect even small amounts of ATTR amyloid in the carpal tunnel. The staining protocol is easy and h-FTAA may be a much more sensitive procedure to detect amyloid at an earlier stage.

Formation of amyloid fibers by monomeric light chain variable domains.

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Brumshtein, Boris; Esswein, Shannon R; Landau, Meytal; Ryan, Christopher M; Whitelegge, Julian P; Phillips, Martin L; Cascio, Duilio; Sawaya, Michael R; Eisenberg, David S

2014-10-03

Systemic light chain amyloidosis is a lethal disease characterized by excess immunoglobulin light chains and light chain fragments composed of variable domains, which aggregate into amyloid fibers. These fibers accumulate and damage organs. Some light chains induce formation of amyloid fibers, whereas others do not, making it unclear what distinguishes amyloid formers from non-formers. One mechanism by which sequence variation may reduce propensity to form amyloid fibers is by shifting the equilibrium toward an amyloid-resistant quaternary structure. Here we identify the monomeric form of the Mcg immunoglobulin light chain variable domain as the quaternary unit required for amyloid fiber assembly. Dimers of Mcg variable domains remain stable and soluble, yet become prone to assemble into amyloid fibers upon disassociation into monomers. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Amyloid Imaging: Poised for Integration into Medical Practice.

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Anand, Keshav; Sabbagh, Marwan

2017-01-01

Amyloid imaging represents a significant advance as an adjunct in the diagnosis of Alzheimer's disease (AD) because it is the first imaging modality that identifies in vivo changes known to be associated with the pathogenesis. Initially, 11 C-PIB was developed, which was the prototype for many 18 F compounds, including florbetapir, florbetaben, and flutemetamol, among others. Despite the high sensitivity and specificity of amyloid imaging, it is not commonly used in clinical practice, mainly because it is not reimbursed under current Center for Medicare and Medicaid Services guidelines in the USA. To guide the field in who would be most appropriate for the utility of amyloid positron emission tomography, current studies are underway [Imaging Dementia Evidence for Amyloid Scanning (IDEAS) Study] that will inform the field on the utilization of amyloid positron emission tomography in clinical practice. With the advent of monoclonal antibodies that specifically target amyloid antibody, there is an interest, possibly a mandate, to screen potential treatment recipients to ensure that they are suitable for treatment. In this review, we summarize progress in the field to date.

Lack of evidence for protein AA reactivity in amyloid deposits of lattice corneal dystrophy and amyloid corneal degeneration.

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Gorevic, P D; Rodrigues, M M; Krachmer, J H; Green, C; Fujihara, S; Glenner, G G

1984-08-15

Amyloid fibrils occurring in primary and myeloma-associated (AL), secondary (AA), and certain neuropathic hereditary forms of systemic amyloidosis can be distinguished biochemically or immunohistologically as being composed of immunoglobulin light chain, protein AA, or prealbumin respectively. All types of systemic and several localized forms of amyloidosis contain amyloid P component (protein AP). We studied formalin-fixed tissue from eight cases of lattice corneal dystrophy by the immunoperoxidase method using antisera to proteins AA and AP, to normal serum prealbumin and prealbumin isolated from a case of hereditary amyloidosis, and to light-chain determinants; additional cases were examined by indirect immunofluorescence of fresh-frozen material. We found weak (1:10 dilution) staining with anti-AP, but no reactivity with other antisera. Congo red staining was resistant to pretreatment of sections with potassium permanganate, a characteristic of non-AA amyloid. Two-dimensional gels of solubilized proteins from frozen tissue from two cases of lattice corneal dystrophy resembled those obtained from normal human cornea. Western blots of two cases of polymorphous amyloid degeneration and solubilized protein from normal cornea did not react with radioactive iodine-labeled anti-AA or anti-AP with purified protein AP and unfixed protein AA amyloid tissue as controls. We were unable to corroborate the presence of protein AA in the amyloid deposits of lattice corneal dystrophy. Although staining with antiserum to protein AP was demonstrable, the molecular configuration of this protein in stromal deposits remains to be defined.

Melanosomal formation of PMEL core amyloid is driven by aromatic residues.

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Hee, Jia Shee; Mitchell, Susan M; Liu, Xinran; Leonhardt, Ralf M

2017-03-08

PMEL is a pigment cell protein that forms physiological amyloid in melanosomes. Many amyloids and/or their oligomeric precursors are toxic, causing or contributing to severe, incurable diseases including Alzheimer's and prion diseases. Striking similarities in intracellular formation pathways between PMEL and various pathological amyloids including Aβ and PrP Sc suggest PMEL is an excellent model system to study endocytic amyloid. Learning how PMEL fibrils assemble without apparent toxicity may help developing novel therapies for amyloid diseases. Here we identify the critical PMEL domain that forms the melanosomal amyloid core (CAF). An unbiased alanine-scanning screen covering the entire region combined with quantitative electron microscopy analysis of the full set of mutants uncovers numerous essential residues. Many of these rely on aromaticity for function suggesting a role for π-stacking in melanosomal amyloid assembly. Various mutants are defective in amyloid nucleation. This extensive data set informs the first structural model of the CAF and provides insights into how the melanosomal amyloid core forms.

Molecular mechanism of pore creation in bacterial membranes by amyloid proteins

International Nuclear Information System (INIS)

Tsigelny, I F; Sharikov, Y; Miller, M A; Masliah, E

2009-01-01

This study explores the mechanism of pore creation in cellular membranes by MccE92 bacterial proteins. The results of this study are then compared with the mechanism of alpha-synuclein (aS)-based pore formation in mammalian cells, and its role in Parkinson's disease.

Conformational dynamics of amyloid proteins at the aqueous interface

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Armbruster, Matthew; Horst, Nathan; Aoki, Brendy; Malik, Saad; Soto, Patricia

2013-03-01

Amyloid proteins is a class of proteins that exhibit distinct monomeric and oligomeric conformational states hallmark of deleterious neurological diseases for which there are not yet cures. Our goal is to examine the extent of which the aqueous/membrane interface modulates the folding energy landscape of amyloid proteins. To this end, we probe the dynamic conformational ensemble of amyloids (monomer prion protein and Alzheimer's Ab protofilaments) interacting with model bilayers. We will present the results of our coarse grain molecular modeling study in terms of the existence of preferential binding spots of the amyloid to the bilayer and the response of the bilayer to the interaction with the amyloid. NSF Nebraska EPSCoR First Award

Intracellular amyloid formation in muscle cells of Aβ-transgenic Caenorhabditis elegans: determinants and physiological role in copper detoxification

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Bush Ashley I

2009-01-01

Full Text Available Abstract Background The amyloid β-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Aβ aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Aβ is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Aβ is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly. Results In the present work, we found that intracellular Aβ aggregation in muscle cells of Caenorhabditis elegans overexpressing Aβ peptide is affected by two single amino acid substitutions, E22G (Arctic and V18A (NIC. Both variations show decrease intracellular amyloidogenesis compared to wild type Aβ. We show that intracellular amyloid aggregation of wild type Aβ is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Aβ-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates. Conclusion Our data show that intracellular Aβ amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Aβ aggregation may be part of a cell protective mechanism.

Multiple Myeloma Presenting as Massive Amyloid Deposition in a Parathyroid Gland Associated with Amyloid Goiter: A Medullary Thyroid Carcinoma Mimic on Intra-operative Frozen Section.

Science.gov (United States)

Hill, Kirk; Diaz, Jason; Hagemann, Ian S; Chernock, Rebecca D

2018-06-01

Clinical examples of amyloid deposition in parathyroid glands are exceedingly rare and usually present as an incidental finding in a patient with amyloid goiter. Here, we present the first histologically documented case of parathyroid amyloid deposition that presented as a mass. The patient did not have hyperparathyroidism. The parathyroid gland was submitted for intra-operative frozen section and concern for medullary thyroid carcinoma was raised. An important histologic clue arguing against medullary thyroid carcinoma was the evenly dispersed nature of the amyloid. Histologic perinuclear clearing and parathyroid hormone immunohistochemistry confirmed parathyroid origin on permanent sections. The patient was also found to have associated amyloid goiter. Mass spectrometry of the amyloid showed it to be composed of kappa light chains. On further work-up, the patient was diagnosed with multiple myeloma. Awareness of parathyroid amyloid deposition is important as it is a histologic mimic of medullary thyroid carcinoma, especially on frozen section. Amyloid typing with evaluation for multiple myeloma in any patient with kappa or lambda light chain restriction is also important.

The prion protein as a receptor for amyloid-beta

NARCIS (Netherlands)

Kessels, Helmut W.; Nguyen, Louis N.; Nabavi, Sadegh; Malinow, Roberto

2010-01-01

Increased levels of brain amyloid-beta, a secreted peptide cleavage product of amyloid precursor protein (APP), is believed to be critical in the aetiology of Alzheimer's disease. Increased amyloid-beta can cause synaptic depression, reduce the number of spine protrusions (that is, sites of synaptic

Stabilization of a β-hairpin in monomeric Alzheimer's amyloid-β peptide inhibits amyloid formation

OpenAIRE

Hoyer, Wolfgang; Grönwall, Caroline; Jonsson, Andreas; Ståhl, Stefan; Härd, Torleif

2008-01-01

According to the amyloid hypothesis, the pathogenesis of Alzheimer's disease is triggered by the oligomerization and aggregation of the amyloid-β (Aβ) peptide into protein plaques. Formation of the potentially toxic oligomeric and fibrillar Aβ assemblies is accompanied by a conformational change toward a high content of β-structure. Here, we report the solution structure of Aβ(1–40) in complex with the phage-display selected affibody protein ZAβ3, a binding protein of nanomolar affinity. Boun...

Recent progress on understanding the mechanisms of amyloid nucleation.

Science.gov (United States)

Chatani, Eri; Yamamoto, Naoki

2018-04-01

Amyloid fibrils are supramolecular protein assemblies with a fibrous morphology and cross-β structure. The formation of amyloid fibrils typically follows a nucleation-dependent polymerization mechanism, in which a one-step nucleation scheme has widely been accepted. However, a variety of oligomers have been identified in early stages of fibrillation, and a nucleated conformational conversion (NCC) mechanism, in which oligomers serve as a precursor of amyloid nucleation and convert to amyloid nuclei, has been proposed. This development has raised the need to consider more complicated multi-step nucleation processes in addition to the simplest one-step process, and evidence for the direct involvement of oligomers as nucleation precursors has been obtained both experimentally and theoretically. Interestingly, the NCC mechanism has some analogy with the two-step nucleation mechanism proposed for inorganic and organic crystals and protein crystals, although a more dramatic conformational conversion of proteins should be considered in amyloid nucleation. Clarifying the properties of the nucleation precursors of amyloid fibrils in detail, in comparison with those of crystals, will allow a better understanding of the nucleation of amyloid fibrils and pave the way to develop techniques to regulate it.

In vivo detection of amyloid plaques by gadolinium-stained MRI can be used to demonstrate the efficacy of an anti-amyloid immunotherapy

Directory of Open Access Journals (Sweden)

Mathieu D. Santin

2016-03-01

Full Text Available Extracellular deposition of β amyloid plaques is an early event associated to Alzheimer's disease. Here we have used in vivo gadolinium-stained high resolution (29*29*117µm3 MRI to follow-up in a longitudinal way individual amyloid plaques in APP/PS1 mice and evaluate the efficacy of a new immunotherapy (SAR255952 directed against protofibrillar and fibrillary forms of Aβ. APP/PS1 mice were treated for 5 months between the age of 3.5 and 8.5 months. SAR255952 reduced amyloid load in 8.5-month-old animals, but not in 5.5-month animals compared to mice treated with a control antibody (DM4. Histological evaluation confirmed the reduction of amyloid load and revealed a lower density of amyloid plaques in 8.5-month SAR255952-treated animals. The longitudinal follow-up of individual amyloid plaques by MRI revealed that plaques that were visible at 5.5 months were still visible at 8.5 months in both SAR255952 and DM4-treated mice. This suggests that the amyloid load reduction induced by SAR255952 is related to a slowing down in the formation of new plaques rather than to the clearance of already formed plaques.

Star Polymers Reduce Islet Amyloid Polypeptide Toxicity via Accelerated Amyloid Aggregation.

Science.gov (United States)

Pilkington, Emily H; Lai, May; Ge, Xinwei; Stanley, William J; Wang, Bo; Wang, Miaoyi; Kakinen, Aleksandr; Sani, Marc-Antonie; Whittaker, Michael R; Gurzov, Esteban N; Ding, Feng; Quinn, John F; Davis, Thomas P; Ke, Pu Chun

2017-12-11

Protein aggregation into amyloid fibrils is a ubiquitous phenomenon across the spectrum of neurodegenerative disorders and type 2 diabetes. A common strategy against amyloidogenesis is to minimize the populations of toxic oligomers and protofibrils by inhibiting protein aggregation with small molecules or nanoparticles. However, melanin synthesis in nature is realized by accelerated protein fibrillation to circumvent accumulation of toxic intermediates. Accordingly, we designed and demonstrated the use of star-shaped poly(2-hydroxyethyl acrylate) (PHEA) nanostructures for promoting aggregation while ameliorating the toxicity of human islet amyloid polypeptide (IAPP), the peptide involved in glycemic control and the pathology of type 2 diabetes. The binding of PHEA elevated the β-sheet content in IAPP aggregates while rendering a new morphology of "stelliform" amyloids originating from the polymers. Atomistic molecular dynamics simulations revealed that the PHEA arms served as rodlike scaffolds for IAPP binding and subsequently accelerated IAPP aggregation by increased local peptide concentration. The tertiary structure of the star nanoparticles was found to be essential for driving the specific interactions required to impel the accelerated IAPP aggregation. This study sheds new light on the structure-toxicity relationship of IAPP and points to the potential of exploiting star polymers as a new class of therapeutic agents against amyloidogenesis.

Amyloid plaque imaging in vivo: current achievement and future prospects

International Nuclear Information System (INIS)

Nordberg, Agneta

2008-01-01

Alzheimer's disease (AD) is a very complex neurodegenerative disorder, the exact cause of which is still not known. The major histopathological features, amyloid plaques and neurofibrillary tangles, already described by Alois Alzheimer, have been the focus in research for decades. Despite a probable whole cascade of events in the brain leading to impairment of cognition, amyloid is still the target for diagnosis and treatment. The rapid development of molecular imaging techniques now allows imaging of amyloid plaques in vivo in Alzheimer patients by PET amyloid ligands such as Pittsburgh compound B (PIB). Studies so far have revealed high 11 C-PIB retention in brain at prodromal stages of AD and a possibility to discriminate AD from other dementia disorders by 11 C-PIB. Ongoing studies are focussing to understand the relationship between brain and CSF amyloid processes and cognitive processes. In vivo imaging of amyloid will be important for early diagnosis and evaluation of new anti-amyloid therapies in AD. (orig.)

Cooperative structural transitions in amyloid-like aggregation

Science.gov (United States)

Steckmann, Timothy; Bhandari, Yuba R.; Chapagain, Prem P.; Gerstman, Bernard S.

2017-04-01

Amyloid fibril aggregation is associated with several horrific diseases such as Alzheimer's, Creutzfeld-Jacob, diabetes, Parkinson's, and others. Although proteins that undergo aggregation vary widely in their primary structure, they all produce a cross-β motif with the proteins in β-strand conformations perpendicular to the fibril axis. The process of amyloid aggregation involves forming myriad different metastable intermediate aggregates. To better understand the molecular basis of the protein structural transitions and aggregation, we report on molecular dynamics (MD) computational studies on the formation of amyloid protofibrillar structures in the small model protein ccβ, which undergoes many of the structural transitions of the larger, naturally occurring amyloid forming proteins. Two different structural transition processes involving hydrogen bonds are observed for aggregation into fibrils: the breaking of intrachain hydrogen bonds to allow β-hairpin proteins to straighten, and the subsequent formation of interchain H-bonds during aggregation into amyloid fibrils. For our MD simulations, we found that the temperature dependence of these two different structural transition processes results in the existence of a temperature window that the ccβ protein experiences during the process of forming protofibrillar structures. This temperature dependence allows us to investigate the dynamics on a molecular level. We report on the thermodynamics and cooperativity of the transformations. The structural transitions that occurred in a specific temperature window for ccβ in our investigations may also occur in other amyloid forming proteins but with biochemical parameters controlling the dynamics rather than temperature.

Chirality and chiroptical properties of amyloid fibrils.

Science.gov (United States)

Dzwolak, Wojciech

2014-09-01

Chirality of amyloid fibrils-linear beta-sheet-rich aggregates of misfolded protein chains-often manifests in morphological traits such as helical twist visible in atomic force microscopy and in chiroptical properties accessible to vibrational circular dichroism (VCD). According to recent studies the relationship between molecular chirality of polypeptide building blocks and superstructural chirality of amyloid fibrils may be more intricate and less deterministic than previously assumed. Several puzzling experimental findings have put into question earlier intuitive ideas on: 1) the bottom-up chirality transfer upon amyloidogenic self-assembly, and 2) the structural origins of chiroptical properties of protein aggregates. For example, removal of a single amino acid residue from an amyloidogenic all-L peptide was shown to reverse handedness of fibrils. On the other hand, certain types of amyloid aggregates revealed surprisingly strong VCD spectra with the sign and shape dependent on the conditions of fibrillation. Hence, microscopic and chiroptical studies have highlighted chirality as one more aspect of polymorphism of amyloid fibrils. This brief review is intended to outline the current state of research on amyloid-like fibrils from the perspective of their structural and superstructural chirality and chiroptical properties. © 2014 Wiley Periodicals, Inc.

Yeast and Fungal Prions: Amyloid-Handling Systems, Amyloid Structure, and Prion Biology.

Science.gov (United States)

Wickner, R B; Edskes, H K; Gorkovskiy, A; Bezsonov, E E; Stroobant, E E

2016-01-01

Yeast prions (infectious proteins) were discovered by their outré genetic properties and have become important models for an array of human prion and amyloid diseases. A single prion protein can become any of many distinct amyloid forms (called prion variants or strains), each of which is self-propagating, but with different biological properties (eg, lethal vs mild). The folded in-register parallel β sheet architecture of the yeast prion amyloids naturally suggests a mechanism by which prion variant information can be faithfully transmitted for many generations. The yeast prions rely on cellular chaperones for their propagation, but can be cured by various chaperone imbalances. The Btn2/Cur1 system normally cures most variants of the [URE3] prion that arise. Although most variants of the [PSI+] and [URE3] prions are toxic or lethal, some are mild in their effects. Even the most mild forms of these prions are rare in the wild, indicating that they too are detrimental to yeast. The beneficial [Het-s] prion of Podospora anserina poses an important contrast in its structure, biology, and evolution to the yeast prions characterized thus far. Copyright © 2016 Elsevier Inc. All rights reserved.

[Amyloid goiter].

Science.gov (United States)

Hrívó, A; Péter, I; Bánkúti, B; Péley, G; Baska, F; Besznyák, I

1999-03-21

Amyloid goitre is at an extremely rare occurrence. Authors review the origin of disease and its symptoms, diagnostic and therapeutic tools. The disease may be due to either primary or secondary systemic or local amyloidosis. Diagnosis may be made even before surgery on anamnestic data, on very rapid growth of thyroid glands, on diffuse appearance, on other symptoms of systemic amyloidosis, on findings of iconographic procedures and on detection of amyloid in aspirates. Final diagnosis is based on histology. Surgical therapy is aiming at avoidance of the existing and the threatening consequences of expanding mass. The outcome is independent from thyroid surgery, it is related to other manifestations of amyloidosis. Concerning with the present case the chronic superior vena cava syndrome and chylous pleural effusion as first described symptoms and asymptomatic hyperthyroxinaemia is emphasised. Neither other organ involvement, nor primary amyloidogenous molecula was found during the 18 months follow up, so patient has secondary and localised amyloidosis.

Associations Between β-Amyloid Kinetics and the β-Amyloid Diurnal Pattern in the Central Nervous System.

Science.gov (United States)

Lucey, Brendan P; Mawuenyega, Kwasi G; Patterson, Bruce W; Elbert, Donald L; Ovod, Vitaliy; Kasten, Tom; Morris, John C; Bateman, Randall J

2017-02-01

Recent studies found that the concentration of amyloid-β (Aβ) fluctuates with the sleep-wake cycle. Although the amplitude of this day/night pattern attenuates with age and amyloid deposition, to our knowledge, the association of Aβ kinetics (ie, production, turnover, and clearance) with this oscillation has not been studied. To determine the association between Aβ kinetics, age, amyloid levels, and the Aβ day/night pattern in humans. We measured Aβ concentrations and kinetics in 77 adults aged 60 to 87 years with and without amyloid deposition by a novel precise mass spectrometry method at the Washington University School of Medicine in St Louis, Missouri. We compared findings of 2 orthogonal methods, enzyme-linked immunosorbent assay and mass spectrometry, to validate the day/night patterns and determine more precise estimates of the cosinor parameters. In vivo labeling of central nervous system proteins with stable isotopically labeled leucine was performed, and kinetics of Aβ40 and Aβ42 were measured. Serial cerebrospinal fluid collection via indwelling lumbar catheter over 36 to 48 hours before, during, and after in vivo labeling, with a 9-hour primed constant infusion of 13C6-leucine. The amplitude, linear increase, and other cosinor measures of each participant's serial cerebrospinal fluid Aβ concentrations and Aβ turnover rates. Of the 77 participants studied, 46 (59.7%) were men, and the mean (range) age was 72.6 (60.4-87.7) years. Day/night patterns in Aβ concentrations were more sharply defined by the precise mass spectrometry method than by enzyme-linked immunosorbent assay (mean difference of SD of residuals: Aβ40, -7.42 pM; P effects of age and amyloid on Aβ42 amplitude at least partially affect each other. Production and turnover rates suggest that day/night Aβ patterns are modulated by both production and clearance mechanisms active in sleep-wake cycles and that amyloid deposition may impair normal circadian patterns. These findings

beta. -Amyloid gene dosage in Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Murdoch, G H; Manuelidis, L; Kim, J H; Manuelidis, E E

1988-01-11

The 4-5 kd amyloid ..beta..-peptide is a major constituent of the characteristic amyloid plaque of Alzheimer's disease. It has been reported that some cases of sporatic Alzheimer's disease are associated with at least a partial duplication of chromosome 21 containing the gene corresponding to the 695 residue precursor of this peptide. To contribute to an understanding of the frequency to such a duplication event in the overall Alzheimer's population, the authors have determined the gene dosage of the ..beta..-amyloid gene in this collection of cases. All cases had a clinical diagnosis of Alzheimer's confirmed neuropathologically. Each Alzheimer's case had an apparent normal diploid ..beta..-amyloid gene dosage, while control Down's cases had the expected triploid dosage. Thus partial duplication of chromosome 21 may be a rare finding in Alzheimer's disease. Similar conclusions were just reported in several studies of the Harvard Alzheimer collection.

Collapsed state of polyglutamic acid results in amyloid spherulite formation.

Science.gov (United States)

Stehli, Daniel; Mulaj, Mentor; Miti, Tatiana; Traina, Joshua; Foley, Joseph; Muschol, Martin

2015-01-01

Self-assembly of proteins and peptides into amyloid fibrils involves multiple distinct intermediates and late-stage fibrillar polymorphs. Understanding the conditions and mechanisms that promote the formation of one type of intermediate and polymorph over the other represents a fundamental challenge. Answers to this question are also of immediate biomedical relevance since different amyloid aggregate species have been shown to have distinct pathogenic potencies. One amyloid polymorph that has received comparatively little attention are amyloid spherulites. Here we report that self-assembly of the intrinsically disordered polymer poly(L-glutamic) acid (PLE) can generate amyloid spherulites. We characterize spherulite growth kinetics, as well as the morphological, optical and tinctorial features of this amyloid polymorph previously unreported for PLE. We find that PLE spherulites share both tinctorial and structural characteristics with their amyloid fibril counterparts. Differences in PLE's molecular weight, polydispersity or chemistry could not explain the selective propensity toward either fibril or spherulite formation. Instead, we provide evidence that PLE polymers can exist in either a collapsed globule or an extended random coil conformation. The collapsed globule consistently produces spherulites while the extended coil assembles into disordered fibril bundles. This results suggests that these 2 PLE conformers directly affect the morphology of the resulting macroscopic amyloid assembly.

Collapsed state of polyglutamic acid results in amyloid spherulite formation

Science.gov (United States)

Stehli, Daniel; Mulaj, Mentor; Miti, Tatiana; Traina, Joshua; Foley, Joseph; Muschol, Martin

2015-01-01

Self-assembly of proteins and peptides into amyloid fibrils involves multiple distinct intermediates and late-stage fibrillar polymorphs. Understanding the conditions and mechanisms that promote the formation of one type of intermediate and polymorph over the other represents a fundamental challenge. Answers to this question are also of immediate biomedical relevance since different amyloid aggregate species have been shown to have distinct pathogenic potencies. One amyloid polymorph that has received comparatively little attention are amyloid spherulites. Here we report that self-assembly of the intrinsically disordered polymer poly(L-glutamic) acid (PLE) can generate amyloid spherulites. We characterize spherulite growth kinetics, as well as the morphological, optical and tinctorial features of this amyloid polymorph previously unreported for PLE. We find that PLE spherulites share both tinctorial and structural characteristics with their amyloid fibril counterparts. Differences in PLE's molecular weight, polydispersity or chemistry could not explain the selective propensity toward either fibril or spherulite formation. Instead, we provide evidence that PLE polymers can exist in either a collapsed globule or an extended random coil conformation. The collapsed globule consistently produces spherulites while the extended coil assembles into disordered fibril bundles. This results suggests that these 2 PLE conformers directly affect the morphology of the resulting macroscopic amyloid assembly. PMID:28232889

The Tubular Sheaths Encasing Methanosaeta thermophila Filaments Are Functional Amyloids.

Science.gov (United States)

Dueholm, Morten S; Larsen, Poul; Finster, Kai; Stenvang, Marcel R; Christiansen, Gunna; Vad, Brian S; Bøggild, Andreas; Otzen, Daniel E; Nielsen, Per Halkjær

2015-08-14

Archaea are renowned for their ability to thrive in extreme environments, although they can be found in virtually all habitats. Their adaptive success is linked to their unique cell envelopes that are extremely resistant to chemical and thermal denaturation and that resist proteolysis by common proteases. Here we employ amyloid-specific conformation antibodies and biophysical techniques to show that the extracellular cell wall sheaths encasing the methanogenic archaea Methanosaeta thermophila PT are functional amyloids. Depolymerization of sheaths and subsequent MS/MS analyses revealed that the sheaths are composed of a single major sheath protein (MspA). The amyloidogenic nature of MspA was confirmed by in vitro amyloid formation of recombinant MspA under a wide range of environmental conditions. This is the first report of a functional amyloid from the archaeal domain of life. The amyloid nature explains the extreme resistance of the sheath, the elastic properties that allow diffusible substrates to penetrate through expandable hoop boundaries, and how the sheaths are able to split and elongate outside the cell. The archaeal sheath amyloids do not share homology with any of the currently known functional amyloids and clearly represent a new function of the amyloid protein fold. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Bone marrow amyloid spherulites in a case of AL amyloidosis.

Science.gov (United States)

Bommannan B K, Karthik; Sonai, Mukinkumar; Sachdeva, Man Updesh Singh

2016-05-01

Parallel arrangement of β-pleated sheets by amyloidogenic proteins is a well known phenomenon. Rarely, amyloid fibrils undergo radial orientation to form globular structures called spherulites. These amyloid spherulites show Maltese cross pattern under polarized microscopy. The clinical significance of amyloid spherulites is undetermined. Amyloidogenic proteins like insulin and β-lactoglobulin form spherulites in vitro. The senile plaques of Alzheimer's disease rarely form in vivo spherulites. Amyloid spherulites have been described in the liver and small intestine. For the first time, we document amyloid spherulite formation in the bone marrow biopsy of an AL amyloidosis patient. Copyright © 2016 Elsevier Inc. All rights reserved.

Preparation of Amyloid Fibrils Seeded from Brain and Meninges.

Science.gov (United States)

Scherpelz, Kathryn P; Lu, Jun-Xia; Tycko, Robert; Meredith, Stephen C

2016-01-01

Seeding of amyloid fibrils into fresh solutions of the same peptide or protein in disaggregated form leads to the formation of replicate fibrils, with close structural similarity or identity to the original fibrillar seeds. Here we describe procedures for isolating fibrils composed mainly of β-amyloid (Aβ) from human brain and from leptomeninges, a source of cerebral blood vessels, for investigating Alzheimer's disease and cerebral amyloid angiopathy. We also describe methods for seeding isotopically labeled, disaggregated Aβ peptide solutions for study using solid-state NMR and other techniques. These methods should be applicable to other types of amyloid fibrils, to Aβ fibrils from mice or other species, tissues other than brain, and to some non-fibrillar aggregates. These procedures allow for the examination of authentic amyloid fibrils and other protein aggregates from biological tissues without the need for labeling the tissue.

secHsp70 as a tool to approach amyloid-β42 and other extracellular amyloids.

Science.gov (United States)

De Mena, Lorena; Chhangani, Deepak; Fernandez-Funez, Pedro; Rincon-Limas, Diego E

2017-07-03

Self-association of amyloidogenic proteins is the main pathological trigger in a wide variety of neurodegenerative disorders. These aggregates are deposited inside or outside the cell due to hereditary mutations, environmental exposures or even normal aging. Cumulative evidence indicates that the heat shock chaperone Hsp70 possesses robust neuroprotection against various intracellular amyloids in Drosophila and mouse models. However, its protective role against extracellular amyloids was largely unknown as its presence outside the cells is very limited. Our recent manuscript in PNAS revealed that an engineered form of secreted Hsp70 (secHsp70) is highly protective against toxicity induced by extracellular deposition of the amyloid-β42 (Aβ42) peptide. In this Extra View article, we extend our analysis to other members of the heat shock protein family. We created PhiC31-based transgenic lines for human Hsp27, Hsp40, Hsp60 and Hsp70 and compared their activities in parallel against extracellular Aβ42. Strikingly, only secreted Hsp70 exhibits robust protection against Aβ42-triggered toxicity in the extracellular milieu. These observations indicate that the ability of secHsp70 to suppress Aβ42 insults is quite unique and suggest that targeted secretion of Hsp70 may represent a new therapeutic approach against Aβ42 and other extracellular amyloids. The potential applications of this engineered chaperone are discussed.

Modeling the Aggregation Propensity and Toxicity of Amyloid-β Variants

DEFF Research Database (Denmark)

Tiwari, Manish Kumar; Kepp, Kasper Planeta

2015-01-01

Protein aggregation is a hallmark of many neurodegenerative disorders. Alzheimer’s disease (AD) is directly linked to deposits of amyloid-β (Aβ) derived from the amyloid-β protein precursor (AβPP), and multiple experimental studies have investigated the aggregation behavior of these amyloids...

Fish β-parvalbumin acquires allergenic properties by amyloid assembly.

Science.gov (United States)

Martínez, Javier; Sánchez, Rosa; Castellanos, Milagros; Fernández-Escamilla, Ana M; Vázquez-Cortés, Sonia; Fernández-Rivas, Montserrat; Gasset, María

2015-01-01

Amyloids are highly cross-β-sheet-rich aggregated states that confer protease resistance, membrane activity and multivalence properties to proteins, all essential features for the undesired preservation of food proteins transiting the gastrointestinal tract and causing type I allergy. Amyloid propensity of β-parvalbumin, the major fish allergen, was theoretically analysed and assayed under gastrointestinal-relevant conditions using the binding of thioflavin T, the formation of sodium dodecyl sulphate- (SDS-) resistant aggregates, circular dichroism spectroscopy and atomic force microscopy fibril imaging. Impact of amyloid aggregates on allergenicity was assessed with dot blot. Sequences of β-parvalbumin from species with commercial value contain several adhesive hexapeptides capable of driving amyloid formation. Using Atlantic cod β-parvalbumin (rGad m 1) displaying high IgE cross-reactivity, we found that formation of amyloid fibres under simulated gastrointestinal conditions accounts for the resistance to acid and neutral proteases, for the presence of membrane active species under gastrointestinal relevant conditions and for the IgE-recognition in the sera of allergic patients. Incorporation of the anti-amyloid compound epigallocatechin gallate prevents rGad m 1 fibrillation, facilitates its protease digestion and impairs its recognition by IgE. the formation of amyloid by rGad m 1 explains its degradation resistance, its facilitated passage across the intestinal epithelial barrier and its epitope architecture as allergen.

Towards Prebiotic Catalytic Amyloids Using High Throughput Screening.

Directory of Open Access Journals (Sweden)

Michael P Friedmann

Full Text Available Enzymes are capable of directing complex stereospecific transformations and of accelerating reaction rates many orders of magnitude. As even the simplest known enzymes comprise thousands of atoms, the question arises as to how such exquisite catalysts evolved. A logical predecessor would be shorter peptides, but they lack the defined structure and size that are apparently necessary for enzyme functions. However, some very short peptides are able to assemble into amyloids, thereby forming a well-defined tertiary structure called the cross-β-sheet, which bestows unique properties upon the peptides. We have hypothesized that amyloids could have been the catalytically active precursor to modern enzymes. To test this hypothesis, we designed an amyloid peptide library that could be screened for catalytic activity. Our approach, amenable to high-throughput methodologies, allowed us to find several peptides and peptide mixtures that form amyloids with esterase activity. These results indicate that amyloids, with their stability in a wide range of conditions and their potential as catalysts with low sequence specificity, would indeed be fitting precursors to modern enzymes. Furthermore, our approach can be efficiently expanded upon in library size, screening conditions, and target activity to yield novel amyloid catalysts with potential applications in aqueous-organic mixtures, at high temperature and in other extreme conditions that could be advantageous for industrial applications.

Amyloid PET in European and North American cohorts; and exploring age as a limit to clinical use of amyloid imaging

Energy Technology Data Exchange (ETDEWEB)

Chiotis, Konstantinos [Karolinska Institutet, Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Stockholm (Sweden); Carter, Stephen F. [Karolinska Institutet, Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Stockholm (Sweden); University of Manchester, Wolfson Molecular Imaging Centre, Institute of Brain, Behaviour and Mental Health, Manchester (United Kingdom); Farid, Karim [Karolinska Institutet, Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Stockholm (Sweden); APHP, Hotel-Dieu Hospital, Department of Nuclear Medicine, Paris (France); Savitcheva, Irina [Karolinska University Hospital Huddinge, Department of Radiology, Stockholm (Sweden); Nordberg, Agneta [Karolinska Institutet, Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Stockholm (Sweden); Karolinska University Hospital Huddinge, Department of Geriatric Medicine, Stockholm (Sweden); Collaboration: for the Diagnostic Molecular Imaging (DiMI) network and the Alzheimer' s Disease Neuroimaging Initiative

2015-09-15

Several radiotracers that bind to fibrillar amyloid-beta in the brain have been developed and used in various patient cohorts. This study aimed to investigate the comparability of two amyloid positron emission tomography (PET) tracers as well as examine how age affects the discriminative properties of amyloid PET imaging. Fifty-one healthy controls (HCs), 72 patients with mild cognitive impairment (MCI) and 90 patients with Alzheimer's disease (AD) from a European cohort were scanned with [11C]Pittsburgh compound-B (PIB) and compared with an age-, sex- and disease severity-matched population of 51 HC, 72 MCI and 84 AD patients from a North American cohort who were scanned with [18F]Florbetapir. An additional North American population of 246 HC, 342 MCI and 138 AD patients with a Florbetapir scan was split by age (55-75 vs 76-93 y) into groups matched for gender and disease severity. PET template-based analyses were used to quantify regional tracer uptake. The mean regional uptake patterns were similar and strong correlations were found between the two tracers across the regions of interest in HC (ρ = 0.671, p = 0.02), amyloid-positive MCI (ρ = 0.902, p < 0.001) and AD patients (ρ = 0.853, p < 0.001). The application of the Florbetapir cut-off point resulted in a higher proportion of amyloid-positive HC and a lower proportion of amyloid-positive AD patients in the older group (28 and 30 %, respectively) than in the younger group (19 and 20 %, respectively). These results illustrate the comparability of Florbetapir and PIB in unrelated but matched patient populations. The role of amyloid PET imaging becomes increasingly important with increasing age in the diagnostic assessment of clinically impaired patients. (orig.)

Amyloid PET in European and North American cohorts; and exploring age as a limit to clinical use of amyloid imaging

International Nuclear Information System (INIS)

Chiotis, Konstantinos; Carter, Stephen F.; Farid, Karim; Savitcheva, Irina; Nordberg, Agneta

2015-01-01

Several radiotracers that bind to fibrillar amyloid-beta in the brain have been developed and used in various patient cohorts. This study aimed to investigate the comparability of two amyloid positron emission tomography (PET) tracers as well as examine how age affects the discriminative properties of amyloid PET imaging. Fifty-one healthy controls (HCs), 72 patients with mild cognitive impairment (MCI) and 90 patients with Alzheimer's disease (AD) from a European cohort were scanned with [11C]Pittsburgh compound-B (PIB) and compared with an age-, sex- and disease severity-matched population of 51 HC, 72 MCI and 84 AD patients from a North American cohort who were scanned with [18F]Florbetapir. An additional North American population of 246 HC, 342 MCI and 138 AD patients with a Florbetapir scan was split by age (55-75 vs 76-93 y) into groups matched for gender and disease severity. PET template-based analyses were used to quantify regional tracer uptake. The mean regional uptake patterns were similar and strong correlations were found between the two tracers across the regions of interest in HC (ρ = 0.671, p = 0.02), amyloid-positive MCI (ρ = 0.902, p < 0.001) and AD patients (ρ = 0.853, p < 0.001). The application of the Florbetapir cut-off point resulted in a higher proportion of amyloid-positive HC and a lower proportion of amyloid-positive AD patients in the older group (28 and 30 %, respectively) than in the younger group (19 and 20 %, respectively). These results illustrate the comparability of Florbetapir and PIB in unrelated but matched patient populations. The role of amyloid PET imaging becomes increasingly important with increasing age in the diagnostic assessment of clinically impaired patients. (orig.)

Key points concerning amyloid infectivity and prion-like neuronal invasion

Directory of Open Access Journals (Sweden)

Alba eEspargaró

2016-04-01

Full Text Available Amyloid aggregation has been related to an increasing number of human illnesses, from Alzheimer and Parkinson’s diseases to Creutzfeldt-Jakob disease. Traditionally only prions have been considered as infectious agents with a high capacity of propagation. Although recent publications have showed that many amyloid proteins, including amyloid β-peptide, α-synuclein and tau protein, also propagate in a prion-like manner, the link between propagation of pathological proteins and neurotoxicity has not been evidenced. The extremely low infectivity in natural conditions of the most of non-prion amyloids is far from the spreading capacity displayed by the prions. However, it is important to elucidate the key factors that cause non-prion amyloids become infectious agents. In recent years, important advances in the understanding of the amyloid processes of amyloid-like proteins and unrelated prions (i.e., yeast and fungal prions have yielded essential information that can be applied to shed light on the prion phenomenon in mammals and humans. As shown in this review, recent evidences suggest that there are key factors that could dramatically modulate the prion capacity of proteins in the amyloid conformation. The concentration of nuclei, the presence of oligomers, and the toxicity, resistance and localization of these aggregates could be key factors affecting their spreading. In short, those factors that favor the high concentration of extracellular nuclei or oligomers, characterized by a small size, with a low toxicity could dramatically increase prion propensity; whereas low concentrations of highly toxic intracellular amyloids, with a large size, would prevent infectivity.

Curcumin Decreases Amyloid-β Peptide Levels by Attenuating the Maturation of Amyloid-β Precursor Protein*

Science.gov (United States)

Zhang, Can; Browne, Andrew; Child, Daniel; Tanzi, Rudolph E.

2010-01-01

Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-β (Aβ), the principal component of senile plaques. Aβ is an ∼4-kDa peptide generated via cleavage of the amyloid-β precursor protein (APP). Curcumin is a compound in the widely used culinary spice, turmeric, which possesses potent and broad biological activities, including anti-inflammatory and antioxidant activities, chemopreventative effects, and effects on protein trafficking. Recent in vivo studies indicate that curcumin is able to reduce Aβ-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Aβ levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Aβ levels by attenuating the maturation of APP in the secretory pathway. These data provide a mechanism of action for the ability of curcumin to attenuate amyloid-β pathology. PMID:20622013

Curcumin decreases amyloid-beta peptide levels by attenuating the maturation of amyloid-beta precursor protein.

Science.gov (United States)

Zhang, Can; Browne, Andrew; Child, Daniel; Tanzi, Rudolph E

2010-09-10

Alzheimer disease (AD) is a devastating neurodegenerative disease with no cure. The pathogenesis of AD is believed to be driven primarily by amyloid-beta (Abeta), the principal component of senile plaques. Abeta is an approximately 4-kDa peptide generated via cleavage of the amyloid-beta precursor protein (APP). Curcumin is a compound in the widely used culinary spice, turmeric, which possesses potent and broad biological activities, including anti-inflammatory and antioxidant activities, chemopreventative effects, and effects on protein trafficking. Recent in vivo studies indicate that curcumin is able to reduce Abeta-related pathology in transgenic AD mouse models via unknown molecular mechanisms. Here, we investigated the effects of curcumin on Abeta levels and APP processing in various cell lines and mouse primary cortical neurons. We show for the first time that curcumin potently lowers Abeta levels by attenuating the maturation of APP in the secretory pathway. These data provide a mechanism of action for the ability of curcumin to attenuate amyloid-beta pathology.

Stabilization of a β-hairpin in monomeric Alzheimer's amyloid-β peptide inhibits amyloid formation

Science.gov (United States)

Hoyer, Wolfgang; Grönwall, Caroline; Jonsson, Andreas; Ståhl, Stefan; Härd, Torleif

2008-01-01

According to the amyloid hypothesis, the pathogenesis of Alzheimer's disease is triggered by the oligomerization and aggregation of the amyloid-β (Aβ) peptide into protein plaques. Formation of the potentially toxic oligomeric and fibrillar Aβ assemblies is accompanied by a conformational change toward a high content of β-structure. Here, we report the solution structure of Aβ(1–40) in complex with the phage-display selected affibody protein ZAβ3, a binding protein of nanomolar affinity. Bound Aβ(1–40) features a β-hairpin comprising residues 17–36, providing the first high-resolution structure of Aβ in β conformation. The positions of the secondary structure elements strongly resemble those observed for fibrillar Aβ. ZAβ3 stabilizes the β-sheet by extending it intermolecularly and by burying both of the mostly nonpolar faces of the Aβ hairpin within a large hydrophobic tunnel-like cavity. Consequently, ZAβ3 acts as a stoichiometric inhibitor of Aβ fibrillation. The selected Aβ conformation allows us to suggest a structural mechanism for amyloid formation based on soluble oligomeric hairpin intermediates. PMID:18375754

Metastable Amyloid Phases and their Conversion to Mature Fibrils

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Muschol, Martin; Miti, Tatiana; Mulaj, Mentor; Schmit, Jeremy

Self-assembly of proteins into amyloid fibrils plays a key role in both functional biological responses and pathogenic disorders which include Alzheimer's disease and type II diabetes. Amyloid fibril assembly frequently generates compact oligomeric and curvilinear polymeric intermediates which are implicated to be toxic to cells. Yet, the relation between these early-stage oligomeric aggregates and late-stage rigid fibrils, which are the hallmark structure of amyloid plaques, has remained unclear. Our measurements indicate that lysozyme amyloid oligomers and their curvilinear fibrils only form after crossing a salt and protein concentration dependent threshold. These oligomeric aggregates are structurally distinct from rigid fibrils and are metastable against nucleation and growth of rigid fibrils. Our experimental transition boundaries match well with colloidal model predictions accounting for salt-modulated charge repulsion. We also report our preliminary findings on the mechanism by which these metastable oligomeric phases are converted into stable amyloid fibrils.

Accumulation of murine amyloid-β mimics early Alzheimer's disease.

Science.gov (United States)

Krohn, Markus; Bracke, Alexander; Avchalumov, Yosef; Schumacher, Toni; Hofrichter, Jacqueline; Paarmann, Kristin; Fröhlich, Christina; Lange, Cathleen; Brüning, Thomas; von Bohlen Und Halbach, Oliver; Pahnke, Jens

2015-08-01

Amyloidosis mouse models of Alzheimer's disease are generally established by transgenic approaches leading to an overexpression of mutated human genes that are known to be involved in the generation of amyloid-β in Alzheimer's families. Although these models made substantial contributions to the current knowledge about the 'amyloid hypothesis' of Alzheimer's disease, the overproduction of amyloid-β peptides mimics only inherited (familiar) Alzheimer's disease, which accounts for patients with Alzheimer's disease. The inherited form is even regarded a 'rare' disease according to the regulations for funding of the European Union (www.erare.eu). Here, we show that mice that are double-deficient for neprilysin (encoded by Mme), one major amyloid-β-degrading enzyme, and the ABC transporter ABCC1, a major contributor to amyloid-β clearance from the brain, develop various aspects of sporadic Alzheimer's disease mimicking the clinical stage of mild cognitive impairment. Using behavioural tests, electrophysiology and morphological analyses, we compared different ABC transporter-deficient animals and found that alterations are most prominent in neprilysin × ABCC1 double-deficient mice. We show that these mice have a reduced probability to survive, show increased anxiety in new environments, and have a reduced working memory performance. Furthermore, we detected morphological changes in the hippocampus and amygdala, e.g. astrogliosis and reduced numbers of synapses, leading to defective long-term potentiation in functional measurements. Compared to human, murine amyloid-β is poorly aggregating, due to changes in three amino acids at N-terminal positions 5, 10, and 13. Interestingly, our findings account for the action of early occurring amyloid-β species/aggregates, i.e. monomers and small amyloid-β oligomers. Thus, neprilysin × ABCC1 double-deficient mice present a new model for early effects of amyloid-β-related mild cognitive impairment that allows investigations

Whole body amyloid deposition imaging by 123I-SAP scintigraphy

NARCIS (Netherlands)

van Rheenen, Ronald; Glaudemans, Andor; Hazenberg, Bouke

2011-01-01

Amyloidosis is the name of a group of diseases characterized by extracellular deposition of amyloid fibrils. Deposition of amyloid can be localized or systemic. The 123I-SAP-scan can be used to image extent and distribution of amyloid deposition in patients with systemic AA, AL and ATTR amyloidosis.

Development of (F-18)-Labeled Amyloid Imaging Agents for PET

International Nuclear Information System (INIS)

Mathis, C.A.

2007-01-01

The applicant proposes to design and synthesize a series of fluorine-18-labeled radiopharmaceuticals to be used as amyloid imaging agents for positron emission tomography (PET). The investigators will conduct comprehensive iterative in vitro and in vivo studies based upon well defined acceptance criteria in order to identify lead agents suitable for human studies. The long term goals are to apply the selected radiotracers as potential diagnostic agents of Alzheimer's disease (AD), as surrogate markers of amyloid in the brain to determine the efficacy of anti-amyloid therapeutic drugs, and as tools to help address basic scientific questions regarding the progression of the neuropathology of AD, such as testing the 'amyloid cascade hypothesis' which holds that amyloid accumulation is the primary cause of AD.

Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

International Nuclear Information System (INIS)

Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee

2008-01-01

Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an important role in

Small heat shock protein HspB8: its distribution in Alzheimer's disease brains and its inhibition of amyloid-beta protein aggregation and cerebrovascular amyloid-beta toxicity.

NARCIS (Netherlands)

Wilhelmus, M.M.M.; Boelens, W.C.; Otte-Holler, I.; Kamps, B.; Kusters, B.; Maat-Schieman, M.L.; Waal, R.M.W. de; Verbeek, M.M.

2006-01-01

Alzheimer's disease (AD) is characterized by pathological lesions, such as senile plaques (SPs) and cerebral amyloid angiopathy (CAA), both predominantly consisting of a proteolytic cleavage product of the amyloid-beta precursor protein (APP), the amyloid-beta peptide (Abeta). CAA is also the major

Kinetically controlled thermal response of beta2-microglobulin amyloid fibrils.

Science.gov (United States)

Sasahara, Kenji; Naiki, Hironobu; Goto, Yuji

2005-09-23

Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta2-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern.

The influence of pathological mutations and proline substitutions in TDP-43 glycine-rich peptides on its amyloid properties and cellular toxicity.

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Chia-Sui Sun

Full Text Available TAR DNA-binding protein (TDP-43 was identified as the major ubiquitinated component deposited in the inclusion bodies in amyotrophic lateral sclerosis (ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U in 2006. Later on, numerous ALS-related mutations were found in either the glycine or glutamine/asparagine-rich region on the TDP-43 C-terminus, which hinted on the importance of mutations on the disease pathogenesis. However, how the structural conversion was influenced by the mutations and the biological significance of these peptides remains unclear. In this work, various peptides bearing pathogenic or de novo designed mutations were synthesized and displayed their ability to form twisted amyloid fibers, cause liposome leakage, and mediate cellular toxicity as confirmed by transmission electron microscopy (TEM, circular dichroism (CD, Thioflavin T (ThT assay, Raman spectroscopy, calcein leakage assay, and cell viability assay. We have also shown that replacing glycines with prolines, known to obstruct β-sheet formation, at the different positions in these peptides may influence the amyloidogenesis process and neurotoxicity. In these cases, GGG308PPP mutant was not able to form beta-amyloid, cause liposome leakage, nor jeopardized cell survival, which hinted on the importance of the glycines (308-310 during amyloidogenesis.

Mouse senile amyloid fibrils deposited in skeletal muscle exhibit amyloidosis-enhancing activity.

Directory of Open Access Journals (Sweden)

Jinze Qian

2010-05-01

Full Text Available Amyloidosis describes a group of protein folding diseases in which amyloid proteins are abnormally deposited in organs and/or tissues as fine fibrils. Mouse senile amyloidosis is a disorder in which apolipoprotein A-II (apoA-II deposits as amyloid fibrils (AApoAII and can be transmitted from one animal to another both by the feces and milk excreted by mice with amyloidosis. Thus, mouse AApoAII amyloidosis has been demonstrated to be a "transmissible disease". In this study, to further characterize the transmissibility of amyloidosis, AApoAII amyloid fibrils were injected into transgenic Apoa2(cTg(+/- and normal R1.P1-Apoa2(c mice to induce AApoAII systemic amyloidosis. Two months later, AApoAII amyloid deposits were found in the skeletal muscles of amyloid-affected mice, primarily in the blood vessels and in the interstitial tissues surrounding muscle fibers. When amyloid fibrils extracted from the skeletal muscles were subjected to Western blot analysis, apoA-II was detected. Amyloid fibril fractions isolated from the muscles not only demonstrated the structure of amyloid fibrils but could also induce amyloidosis in young mice depending on its fibril conformation. These findings present a possible pathogenesis of amyloidosis: transmission of amyloid fibril conformation through muscle, and shed new light on the etiology involved in amyloid disorders.

Novel β-amyloid aggregation inhibitors possessing a turn mimic.

Science.gov (United States)

Hamada, Yoshio; Miyamoto, Naoko; Kiso, Yoshiaki

2015-04-01

Amyloid β peptide, the main component of senile plaques found in the brain of Alzheimer disease (AD) patients, is a molecular target for AD therapeutic intervention. A number of potential AD therapeutics have been reported, including inhibitors of β-secretase, γ-secretase, and Aβ aggregation, and anti-amyloid agents, such as neprilysin, insulin degrading enzyme (IDE), and Aβ antibodies. Recently, we reported potent small-sized β-secretase (BACE1) inhibitors, which could serve as anti-AD drugs. However AD is a progressive disorder, where dementia symptoms gradually worsen over several decades, and therefore may require many years to get cured. One possible way to achieve a greater therapeutic effect is through simultaneous administration of multiple drugs, similar to those used in Highly Active Anti-Retroviral Therapy (HAART) used to treat AIDS. In order to overcome AD, we took a drug discovery approach to evaluate, novel β-amyloid aggregation inhibitors. Previously, we reported that a tong-type compound possessing a turn mimic as the inhibitor of HIV-1 protease dimerization. Oligomerized amyloid β peptides contain a turn structure within the molecule. Here, we designed and synthesized novel β-amyloid aggregation inhibitors with a turn-mimic template, based on the turn conformer of the oligomerized amyloid β peptides. Copyright © 2015 Elsevier Ltd. All rights reserved.

Depressive symptoms accelerate cognitive decline in amyloid-positive MCI patients

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Brendel, Matthias; Xiong, Guoming; Delker, Andreas [University of Munich, Department of Nuclear Medicine, Munich (Germany); Pogarell, Oliver [University of Munich, Department of Psychiatry, Munich (Germany); Bartenstein, Peter; Rominger, Axel [University of Munich, Department of Nuclear Medicine, Munich (Germany); Munich Cluster for Systems Neurology (SyNergy), Munich (Germany); Collaboration: for the Alzheimer' s Disease Neuroimaging Initiative

2015-04-01

Late-life depression even in subsyndromal stages is strongly associated with Alzheimer's disease (AD). Furthermore, brain amyloidosis is an early biomarker in subjects who subsequently suffer from AD and can be sensitively detected by amyloid PET. Therefore, we aimed to compare amyloid load and glucose metabolism in subsyndromally depressed subjects with mild cognitive impairment (MCI). [{sup 18}F]AV45 PET, [{sup 18}F]FDG PET and MRI were performed in 371 MCI subjects from the Alzheimer's Disease Neuroimaging Initiative Subjects were judged β-amyloid-positive (Aβ+; 206 patients) or β-amyloid-negative (Aβ-; 165 patients) according to [{sup 18}F]AV45 PET. Depressive symptoms were assessed by the Neuropsychiatric Inventory Questionnaire depression item 4. Subjects with depressive symptoms (65 Aβ+, 41 Aβ-) were compared with their nondepressed counterparts. Conversion rates to AD were analysed (mean follow-up time 21.5 ± 9.1 months) with regard to coexisting depressive symptoms and brain amyloid load. Aβ+ depressed subjects showed large clusters with a higher amyloid load in the frontotemporal and insular cortices (p < 0.001) with coincident hypermetabolism (p < 0.001) in the frontal cortices than nondepressed subjects. Faster progression to AD was observed in subjects with depressive symptoms (p < 0.005) and in Aβ+ subjects (p < 0.001). Coincident depressive symptoms additionally shortened the conversion time in all Aβ+ subjects (p < 0.005) and to a greater extent in those with a high amyloid load (p < 0.001). Our results clearly indicate that Aβ+ MCI subjects with depressive symptoms have an elevated amyloid load together with relative hypermetabolism of connected brain areas compared with cognitively matched nondepressed individuals. MCI subjects with high amyloid load and coexistent depressive symptoms are at high risk of faster conversion to AD. (orig.)

Depressive symptoms accelerate cognitive decline in amyloid-positive MCI patients

International Nuclear Information System (INIS)

Brendel, Matthias; Xiong, Guoming; Delker, Andreas; Pogarell, Oliver; Bartenstein, Peter; Rominger, Axel

2015-01-01

Late-life depression even in subsyndromal stages is strongly associated with Alzheimer's disease (AD). Furthermore, brain amyloidosis is an early biomarker in subjects who subsequently suffer from AD and can be sensitively detected by amyloid PET. Therefore, we aimed to compare amyloid load and glucose metabolism in subsyndromally depressed subjects with mild cognitive impairment (MCI). [ 18 F]AV45 PET, [ 18 F]FDG PET and MRI were performed in 371 MCI subjects from the Alzheimer's Disease Neuroimaging Initiative Subjects were judged β-amyloid-positive (Aβ+; 206 patients) or β-amyloid-negative (Aβ-; 165 patients) according to [ 18 F]AV45 PET. Depressive symptoms were assessed by the Neuropsychiatric Inventory Questionnaire depression item 4. Subjects with depressive symptoms (65 Aβ+, 41 Aβ-) were compared with their nondepressed counterparts. Conversion rates to AD were analysed (mean follow-up time 21.5 ± 9.1 months) with regard to coexisting depressive symptoms and brain amyloid load. Aβ+ depressed subjects showed large clusters with a higher amyloid load in the frontotemporal and insular cortices (p < 0.001) with coincident hypermetabolism (p < 0.001) in the frontal cortices than nondepressed subjects. Faster progression to AD was observed in subjects with depressive symptoms (p < 0.005) and in Aβ+ subjects (p < 0.001). Coincident depressive symptoms additionally shortened the conversion time in all Aβ+ subjects (p < 0.005) and to a greater extent in those with a high amyloid load (p < 0.001). Our results clearly indicate that Aβ+ MCI subjects with depressive symptoms have an elevated amyloid load together with relative hypermetabolism of connected brain areas compared with cognitively matched nondepressed individuals. MCI subjects with high amyloid load and coexistent depressive symptoms are at high risk of faster conversion to AD. (orig.)

Light Chain Amyloid Fibrils Cause Metabolic Dysfunction in Human Cardiomyocytes.

Directory of Open Access Journals (Sweden)

Helen P McWilliams-Koeppen

Full Text Available Light chain (AL amyloidosis is the most common form of systemic amyloid disease, and cardiomyopathy is a dire consequence, resulting in an extremely poor prognosis. AL is characterized by the production of monoclonal free light chains that deposit as amyloid fibrils principally in the heart, liver, and kidneys causing organ dysfunction. We have studied the effects of amyloid fibrils, produced from recombinant λ6 light chain variable domains, on metabolic activity of human cardiomyocytes. The data indicate that fibrils at 0.1 μM, but not monomer, significantly decrease the enzymatic activity of cellular NAD(PH-dependent oxidoreductase, without causing significant cell death. The presence of amyloid fibrils did not affect ATP levels; however, oxygen consumption was increased and reactive oxygen species were detected. Confocal fluorescence microscopy showed that fibrils bound to and remained at the cell surface with little fibril internalization. These data indicate that AL amyloid fibrils severely impair cardiomyocyte metabolism in a dose dependent manner. These data suggest that effective therapeutic intervention for these patients should include methods for removing potentially toxic amyloid fibrils.

Prevalence of amyloid PET positivity in dementia syndromes

DEFF Research Database (Denmark)

Ossenkoppele, Rik; Jansen, Willemijn J; Rabinovici, Gil D

2015-01-01

IMPORTANCE: Amyloid-β positron emission tomography (PET) imaging allows in vivo detection of fibrillar plaques, a core neuropathological feature of Alzheimer disease (AD). Its diagnostic utility is still unclear because amyloid plaques also occur in patients with non-AD dementia. OBJECTIVE: To use...

Amyloid structure exhibits polymorphism on multiple length scales in human brain tissue

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiliang; Costantino, Isabel; Venugopalan, Nagarajan; Fischetti, Robert F.; Hyman, Bradley; Frosch, Matthew; Gomez-Isla, Teresa; Makowski, Lee

2016-09-15

Although aggregation of Aβ amyloid fibrils into plaques in the brain is a hallmark of Alzheimer's Disease (AD), the correlation between amyloid burden and severity of symptoms is weak. One possible reason is that amyloid fibrils are structurally polymorphic and different polymorphs may contribute differentially to disease. However, the occurrence and distribution of amyloid polymorphisms in human brain is poorly documented. Here we seek to fill this knowledge gap by using X-ray microdiffraction of histological sections of human tissue to map the abundance, orientation and structural heterogeneities of amyloid within individual plaques; among proximal plaques and in subjects with distinct clinical histories. A 5 µ x-ray beam was used to generate diffraction data with each pattern arising from a scattering volume of only ~ 450 µ3 , making possible collection of dozens to hundreds of diffraction patterns from a single amyloid plaque. X-ray scattering from these samples exhibited all the properties expected for scattering from amyloid. Amyloid distribution was mapped using the intensity of its signature 4.7 Å reflection which also provided information on the orientation of amyloid fibrils across plaques. Margins of plaques exhibited a greater degree of orientation than cores and orientation around blood vessels frequently appeared tangential. Variation in the structure of Aβ fibrils is reflected in the shape of the 4.7 Å peak which usually appears as a doublet. Variations in this peak correspond to differences between the structure of amyloid within cores of plaques and at their periphery. Examination of tissue from a mismatch case - an individual with high plaque burden but no overt signs of dementia at time of death - revealed a diversity of structure and spatial distribution of amyloid that is distinct from typical AD cases. We demonstrate the existence of structural polymorphisms among amyloid within and among plaques of a single individual and suggest

High prevalence of biofilm synergy among bacterial soil isolates in cocultures indicates bacterial interspecific cooperation

DEFF Research Database (Denmark)

Ren, Dawei; Madsen, Jonas Stenløkke; Sørensen, Søren Johannes

2015-01-01

of single-species biofilms, indicating that all the individual strains benefit from inclusion in the multispecies community. Our results show a high prevalence of synergy in biofilm formation in multispecies consortia isolated from a natural bacterial habitat and suggest that interspecific cooperation...

In situ analysis of Bacillus licheniformis biofilms: amyloid-like polymers and eDNA are involved in the adherence and aggregation of the extracellular matrix.

Science.gov (United States)

Randrianjatovo-Gbalou, I; Rouquette, P; Lefebvre, D; Girbal-Neuhauser, E; Marcato-Romain, C-E

2017-05-01

This study attempts to determine which of the exopolymeric substances are involved in the adherence and aggregation of a Bacillus licheniformis biofilm. The involvement of extracellular proteins and eDNA were particularly investigated using DNase and proteinase K treatment. The permeability of the biofilms increased fivefold after DNase I treatment. The quantification of the matrix components showed that, irrespective to the enzyme tested, eDNA and amyloid-like polymers were removed simultaneously. Size-exclusion chromatography analyses supported these observations and revealed the presence of associated nucleic acid and protein complexes in the biofilm lysates. These data suggest that some extracellular DNA and amyloid-like proteins were closely interlaced within the matrix. Finally, confocal laser scanning microscopy imaging gave supplementary clues about the 3D organization of the biofilms, confirming that eDNA and exoproteins were essentially layered under and around the bacterial cells, whereas the amyloid-like fractions were homogeneously distributed within the matrix. These results confirm that some DNA-amyloid complexes play a key role in the modulation of the mechanical resistance of B. licheniformis biofilms. The study highlights the need to consider the whole structure of biofilms and to target the interactions between matrix components. A better understanding of B. licheniformis biofilm physiology and the structural organization of the matrix will strengthen strategies of biofilm control. © 2017 The Society for Applied Microbiology.

Resveratrol and Amyloid-Beta: Mechanistic Insights

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Yongming Jia

2017-10-01

Full Text Available The amyloid-beta (Aβ hypothesis that dyshomeostasis between Aβ production and clearance is a very early, key molecular factor in the etiology of Alzheimer’s disease (AD has been proposed and examined in the AD research field. Scientists have focused on seeking natural products or drugs to influence the dynamic equilibrium of Aβ, targeting production and clearance of Aβ. There is emerging evidence that resveratrol (Res, a naturally occurring polyphenol mainly found in grapes and red wine, acts on AD in numerous in vivo and in vitro models. Res decreases the amyloidogenic cleavage of the amyloid precursor protein (APP, enhances clearance of amyloid beta-peptides, and reduces Aβ aggregation. Moreover, Res also protects neuronal functions through its antioxidant properties. This review discusses the action of Res on Aβ production, clearance and aggregation and multiple potential mechanisms, providing evidence of the useful of Res for AD treatment.

Reduced vascular amyloid burden at microhemorrhage sites in cerebral amyloid angiopathy

NARCIS (Netherlands)

van Veluw, Susanne J.; Kuijf, Hugo J.; Charidimou, Andreas; Viswanathan, Anand; Biessels, Geert Jan; Rozemuller, Annemieke J M; Frosch, Matthew P.; Greenberg, Steven M.

Microhemorrhages are strongly associated with advanced cerebral amyloid angiopathy (CAA). Although it has been frequently proposed that the deposition of Aβ in the walls of cortical vessels directly causes microhemorrhages, this has not been studied in great detail, mainly because the ruptured

Trifluoroethanol modulates α-synuclein amyloid-like aggregate formation, stability and dissolution

DEFF Research Database (Denmark)

Di Carlo, Maria Giovanna; Vetri, Valeria; Buscarino, Gianpiero

2016-01-01

The conversion of proteins into amyloid fibrils and other amyloid-like aggregates is closely connected to the onset of a series of age-related pathologies. Upon changes in environmental conditions, amyloid-like aggregates may also undergo disassembly into oligomeric aggregates, the latter being r...

The late endocytic Rab39a GTPase regulates the interaction between multivesicular bodies and chlamydial inclusions.

Science.gov (United States)

Gambarte Tudela, Julian; Capmany, Anahi; Romao, Maryse; Quintero, Cristian; Miserey-Lenkei, Stephanie; Raposo, Graca; Goud, Bruno; Damiani, Maria Teresa

2015-08-15

Given their obligate intracellular lifestyle, Chlamydia trachomatis ensure that they have access to multiple host sources of essential lipids by interfering with vesicular transport. These bacteria hijack Rab6-, Rab11- and Rab14-controlled trafficking pathways to acquire sphingomyelin from the Golgi complex. Another important source of sphingolipids, phospholipids and cholesterol are multivesicular bodies (MVBs). Despite their participation in chlamydial inclusion development and bacterial replication, the molecular mechanisms mediating the interaction between MVBs and chlamydial inclusions remain unknown. In the present study, we demonstrate that Rab39a labels a subset of late endocytic vesicles - mainly MVBs - that move along microtubules. Moreover, Rab39a is actively recruited to chlamydial inclusions throughout the pathogen life cycle by a bacterial-driven process that depends on the Rab39a GTP- or GDP-binding state. Interestingly, Rab39a participates in the delivery of MVBs and host sphingolipids to maturing chlamydial inclusions, thereby promoting inclusion growth and bacterial development. Taken together, our findings indicate that Rab39a favours chlamydial replication and infectivity. This is the first report showing that a late endocytic Rab GTPase is involved in chlamydial infection development. © 2015. Published by The Company of Biologists Ltd.

Elasticity in Physically Cross-Linked Amyloid Fibril Networks

Science.gov (United States)

Cao, Yiping; Bolisetty, Sreenath; Adamcik, Jozef; Mezzenga, Raffaele

2018-04-01

We provide a constitutive model of semiflexible and rigid amyloid fibril networks by combining the affine thermal model of network elasticity with the Derjaguin-Landau-Vervey-Overbeek (DLVO) theory of electrostatically charged colloids. When compared to rheological experiments on β -lactoglobulin and lysozyme amyloid networks, this approach provides the correct scaling of elasticity versus both concentration (G ˜c2.2 and G ˜c2.5 for semiflexible and rigid fibrils, respectively) and ionic strength (G ˜I4.4 and G ˜I3.8 for β -lactoglobulin and lysozyme, independent from fibril flexibility). The pivotal role played by the screening salt is to reduce the electrostatic barrier among amyloid fibrils, converting labile physical entanglements into long-lived cross-links. This gives a power-law behavior of G with I having exponents significantly larger than in other semiflexible polymer networks (e.g., actin) and carrying DLVO traits specific to the individual amyloid fibrils.

Inhibition of Alzheimer amyloid {beta} aggregation by polyvalent trehalose

Energy Technology Data Exchange (ETDEWEB)

Miura, Yoshiko; You, Chouga [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Ohnishi, Reiko [Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)], E-mail: miuray@jaist.ac.jp

2008-04-15

A glycopolymer carrying trehalose was found to suppress the formation of amyloid fibrils from the amyloid {beta} peptide (1-42) (A{beta}), as evaluated by thioflavin T assay and atomic force microscopy. Glycopolymers carrying sugar alcohols also changed the aggregation properties of A{beta}, and the inhibitory effect depended on the type of sugar and alkyl side chain. Neutralization activity was confirmed by in vitro assay using HeLa cells. The glycopolymer carrying trehalose strongly inhibited amyloid formation and neutralized cytotoxicity.

Thermal Stability Threshold for Amyloid Formation in Light Chain Amyloidosis

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Tanya L. Poshusta

2013-11-01

Full Text Available Light chain (AL amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.

Nanoparticles and amyloid systems: A fatal encounter?

Energy Technology Data Exchange (ETDEWEB)

Abel, Bernd [Leibniz Institute of Surface Modification, Chemical Department, Permoserstr. 15, D-04318 Leipzig, Germany and Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Linnéstr. 3, D-04103 Leipzig (Germany)

2014-10-06

Nanoparticles (NPs) are used in many products of our daily life, however, there has been concern that they may also be harmful to human health. Recently NPs have been found to accelerate the fibrillation kinetics of amyloid systems. In the past this has been preliminarily attributed to a nucleation effect. Nanoparticle surfaces and interfaces appear to limit the degrees of freedom of amyloid systems (i.e., peptides and proteins) due to a phase space constraint such that rapid cross-beta structures are formed faster than without interface interactions and in turn fibril formation is enhanced significantly. Here we explore if lipid bilayers in the form of liposomes (140nm) also accelerate fibril formation for amyloid systems. We have investigated a fragment NNFGAIL of the Human islet amyloid polypeptide (hIAPP) in contact with 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) liposomes in aqueous solution. We found that the lipid bilayer vesicles do accelerate fibril formation in time-resolved off-line detected atomic force microscopy experiments. Characteristic Thioflavine-T fluorescence on the same structures verify that the structures consist of aggregated peptides in a typical cross-β-structure arrangement.

Direct identification of amyloids by label-free quantitative LC-MS

DEFF Research Database (Denmark)

Dueholm, Morten Simonsen; Danielsen, Heidi Nolsøe; Hansen, Susan Hove

adhesive and therefore bind to pipette tips and other consumables. Pure cultures, large sample volumes and high productivity of amyloids are therefore required for successful purification. We here present a quantitative proteomics technique that allow direct identification of functional amyloid candidates......Direct identification of amyloids by label-free quantitative LC-MS H. N. Danielsen, S. H. Hansen, F.-A. Herbst, P. H. Nielsen, M. S. Dueholm Amyloids are highly ordered fibrillar protein polymers used by organisms from all domains of life due to their exceptional properties. We have previously...... in complex samples based on their structural stability in the presence of increasing concentrations of formic acid....

Clinical and imaging correlates of amyloid deposition in dementia with Lewy bodies.

Science.gov (United States)

Donaghy, Paul C; Firbank, Michael J; Thomas, Alan J; Lloyd, Jim; Petrides, George; Barnett, Nicola; Olsen, Kirsty; O'Brien, John T

2018-04-19

Amyloid deposition is common in dementia with Lewy bodies, but its pathophysiological significance is unclear. The objective of this study was to investigate the relationship between amyloid deposition and clinical profile, gray matter volume, and brain perfusion in dementia with Lewy bodies. Dementia with Lewy bodies (n = 37), Alzheimer's disease (n = 20), and controls (n = 20) underwent a thorough clinical assessment, 3T MRI, and early- and late-phase 18 F-Florbetapir PET-CT to assess cortical perfusion and amyloid deposition, respectively. Amyloid scans were visually categorized as positive or negative. Image analysis was carried out using statistical parametric mapping (SPM) 8. There were no significant differences between amyloid-positive and amyloid-negative dementia with Lewy bodies cases in age (P = .78), overall cognitive impairment (P = .83), level of functional impairment (P = .80), or any other clinical or cognitive scale. There were also no significant differences in hippocampal or gray matter volumes. However, amyloid-positive dementia with Lewy bodies cases had lower medial temporal lobe perfusion (P = .03) than amyloid-negative cases, although a combination of medial temporal lobe perfusion, hippocampal volume, and cognitive measures was unable to accurately predict amyloid status in dementia with Lewy bodies. Amyloid deposition was not associated with differences in clinical or neuropsychological profiles in dementia with Lewy bodies, but was associated with imaging evidence of medial temporal lobe dysfunction. The presence of amyloid in dementia with Lewy bodies cannot be identified on the basis of clinical and other imaging features and will require direct assessment via PET imaging or CSF. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf

Amyloid goitre following chronic osteomyelitis: case report and ...

African Journals Online (AJOL)

Amyloid goitre following chronic osteomyelitis: case report and review of literature. AZ Mohammed, ST Edino, O Ochicha. Abstract. Amyloid Goitre is a rare clinical entity associated with systemic amyloidosis. It poses a significant diagnostic and therapeutic challenge and may be confused with a neoplastic goiter. We present ...

A new integrated dual time-point amyloid PET/MRI data analysis method

International Nuclear Information System (INIS)

Cecchin, Diego; Zucchetta, Pietro; Turco, Paolo; Bui, Franco; Barthel, Henryk; Tiepolt, Solveig; Sabri, Osama; Poggiali, Davide; Cagnin, Annachiara; Gallo, Paolo; Frigo, Anna Chiara

2017-01-01

In the initial evaluation of patients with suspected dementia and Alzheimer's disease, there is no consensus on how to perform semiquantification of amyloid in such a way that it: (1) facilitates visual qualitative interpretation, (2) takes the kinetic behaviour of the tracer into consideration particularly with regard to at least partially correcting for blood flow dependence, (3) analyses the amyloid load based on accurate parcellation of cortical and subcortical areas, (4) includes partial volume effect correction (PVEC), (5) includes MRI-derived topographical indexes, (6) enables application to PET/MRI images and PET/CT images with separately acquired MR images, and (7) allows automation. A method with all of these characteristics was retrospectively tested in 86 subjects who underwent amyloid ( 18 F-florbetaben) PET/MRI in a clinical setting (using images acquired 90-110 min after injection, 53 were classified visually as amyloid-negative and 33 as amyloid-positive). Early images after tracer administration were acquired between 0 and 10 min after injection, and later images were acquired between 90 and 110 min after injection. PVEC of the PET data was carried out using the geometric transfer matrix method. Parametric images and some regional output parameters, including two innovative ''dual time-point'' indexes, were obtained. Subjects classified visually as amyloid-positive showed a sparse tracer uptake in the primary sensory, motor and visual areas in accordance with the isocortical stage of the topographic distribution of the amyloid plaque (Braak stages V/VI). In patients classified visually as amyloid-negative, the method revealed detectable levels of tracer uptake in the basal portions of the frontal and temporal lobes, areas that are known to be sites of early deposition of amyloid plaques that probably represented early accumulation (Braak stage A) that is typical of normal ageing. There was a strong correlation between age

A new integrated dual time-point amyloid PET/MRI data analysis method

Energy Technology Data Exchange (ETDEWEB)

Cecchin, Diego; Zucchetta, Pietro; Turco, Paolo; Bui, Franco [University Hospital of Padua, Nuclear Medicine Unit, Department of Medicine - DIMED, Padua (Italy); Barthel, Henryk; Tiepolt, Solveig; Sabri, Osama [Leipzig University, Department of Nuclear Medicine, Leipzig (Germany); Poggiali, Davide; Cagnin, Annachiara; Gallo, Paolo [University Hospital of Padua, Neurology, Department of Neurosciences (DNS), Padua (Italy); Frigo, Anna Chiara [University Hospital of Padua, Biostatistics, Epidemiology and Public Health Unit, Department of Cardiac, Thoracic and Vascular Sciences, Padua (Italy)

2017-11-15

In the initial evaluation of patients with suspected dementia and Alzheimer's disease, there is no consensus on how to perform semiquantification of amyloid in such a way that it: (1) facilitates visual qualitative interpretation, (2) takes the kinetic behaviour of the tracer into consideration particularly with regard to at least partially correcting for blood flow dependence, (3) analyses the amyloid load based on accurate parcellation of cortical and subcortical areas, (4) includes partial volume effect correction (PVEC), (5) includes MRI-derived topographical indexes, (6) enables application to PET/MRI images and PET/CT images with separately acquired MR images, and (7) allows automation. A method with all of these characteristics was retrospectively tested in 86 subjects who underwent amyloid ({sup 18}F-florbetaben) PET/MRI in a clinical setting (using images acquired 90-110 min after injection, 53 were classified visually as amyloid-negative and 33 as amyloid-positive). Early images after tracer administration were acquired between 0 and 10 min after injection, and later images were acquired between 90 and 110 min after injection. PVEC of the PET data was carried out using the geometric transfer matrix method. Parametric images and some regional output parameters, including two innovative ''dual time-point'' indexes, were obtained. Subjects classified visually as amyloid-positive showed a sparse tracer uptake in the primary sensory, motor and visual areas in accordance with the isocortical stage of the topographic distribution of the amyloid plaque (Braak stages V/VI). In patients classified visually as amyloid-negative, the method revealed detectable levels of tracer uptake in the basal portions of the frontal and temporal lobes, areas that are known to be sites of early deposition of amyloid plaques that probably represented early accumulation (Braak stage A) that is typical of normal ageing. There was a strong correlation between

Direct visualization of HIV-enhancing endogenous amyloid fibrils in human semen

Science.gov (United States)

Usmani, Shariq M.; Zirafi, Onofrio; Müller, Janis; Sandi-Monroy, Nathallie; Yadav, Jay K.; Meier, Christoph; Weil, Tanja; Roan, Nadia R.; Greene, Warner C.; Walther, Paul; Nilsson, K. Peter R.; Hammarström, Per; Wetzel, Ronald; Pilcher, Christopher D.; Gagsteiger, Friedrich; Fändrich, Marcus; Kirchhoff, Frank; Münch, Jan

2014-01-01

Naturally occurring fragments of the abundant semen proteins prostatic acid phosphatase (PAP) and semenogelins form amyloid fibrils in vitro. These fibrils boost HIV infection and may play a key role in the spread of the AIDS pandemic. However, the presence of amyloid fibrils in semen remained to be demonstrated. Here, we use state of the art confocal and electron microscopy techniques for direct imaging of amyloid fibrils in human ejaculates. We detect amyloid aggregates in all semen samples and find that they partially consist of PAP fragments, interact with HIV particles and increase viral infectivity. Our results establish semen as a body fluid that naturally contains amyloid fibrils that are exploited by HIV to promote its sexual transmission. PMID:24691351

Cerebral hemorrhage caused by amyloid angiopathy

International Nuclear Information System (INIS)

Hanyu, Haruo; Tomonaga, Masanori; Yoshimura, Masahiro; Yamanouchi, Hiroshi; Shimada, Hiroyuki.

1985-01-01

Cerebral hemorrhage caused by amyloid angiopathy was studied clinicopathologically, with special attention given to the CT images. Cerebral hemorrhage caused by amyloid angiopathy is characterized, by a lobar-type hemorrhage involving the cortex, with direct extension into the subarachnoid space. Multiple hemorrhages are frequent, and cortical infarctions are present as complications in elderly patients without risk factors. CT scans taken in 5 cases demonstrated lobar hemorrhages in superficial locations, frequently in multiple sites or recurrently, with surrounding edema and mass effect. A subarachnoid extension of the hemorrhage through the superficial cortex, proven pathologically in all cases, was noted by CT in 4 of the 5 cases. However, cortical infarction was not detected by CT in any case. Therefore, CT is of value in the diagnosis of cerebral hemorrhage due to amyloid angiopathy based on distinctive findings such as a lobar hemorrhage in superficial regions, with extension into the subarachnoid space, frequently in multiple sites or recurrently. (author)

Detection of AA-type amyloid protein in labial salivary glands.

Science.gov (United States)

Sacsaquispe, Sonia-Julia; Antúnez-de Mayolo, Eleazar-Antonio; Vicetti, Rodolfo; Delgado, Wilson-Alejandro

2011-03-01

Among the diverse forms of amyloidosis, secondary type is the most frequent one. Diagnosis of amyloid deposition is based on the identification of the fibrillary protein amyloid by means of Congo Red (CR) or crystal violet (CV) stains, but these techniques do not differentiate between the different types of amyloid fibrils. The aim of this study was to identify by immunofluorescence (IF) AA amyloid a pathological fibrillar low-molecular-weight protein formed by cleavage of serum amyloid A (SAA) protein in labial salivary gland (LSG) biopsies from patients with secondary amyloidosis. 98 LSG were studied, 65 were from patients with secondary amyloidosis and 33 from subjects with chronic inflammatory diseases without evidence of this anomaly. All sections were stained with hematoxylin and eosin (H &E), CV, CR and IF using anti-AA antibodies. Positive and negative controls were used for all techniques. CV and CR demonstrated that the amyloid substance was found mainly distributed periductally (93.8%), followed by periacinar and perivascular locations (p <0.001); however, the IF demonstrated that amyloid AA substance predominates in the periacinar area (73.8%), followed by periductal and perivascular locations (p <0.001). IF has a sensitivity of 83%, 100% of specificity, 100% of predictive positive value and 75% of predictive negative value. The results of this study confirm the efficacy of the LSG biopsy as a highly reliable method for diagnosis of secondary amyloidosis.

Proteomics with Mass Spectrometry Imaging: Beyond Amyloid Typing.

Science.gov (United States)

Lavatelli, Francesca; Merlini, Giampaolo

2018-04-01

Detection and typing of amyloid deposits in tissues are two crucial steps in the management of systemic amyloidoses. The presence of amyloid deposits is routinely evaluated through Congo red staining, whereas proteomics is now a mainstay in the identification of the deposited proteins. In article number 1700236, Winter et al. [Proteomics 2017, 17, Issue 22] describe a novel method based on MALDI-MS imaging coupled to ion mobility separation and peptide filtering, to detect the presence of amyloid in histology samples and to identify its composition, while preserving the spatial distribution of proteins in tissues. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of amyloid-PET to determine cutpoints for CSF markers

DEFF Research Database (Denmark)

Zwan, Marissa D; Rinne, Juha O; Hasselbalch, Steen G

2016-01-01

OBJECTIVES: To define CSF β-amyloid 1-42 (Aβ42) cutpoints to detect cortical amyloid deposition as assessed by 11C-Pittsburgh compound B ([11C]PiB)-PET and to compare these calculated cutpoints with cutpoints currently used in clinical practice. METHODS: We included 433 participants (57 controls......, 99 with mild cognitive impairment, 195 with Alzheimer disease [AD] dementia, and 82 with non-AD dementia) from 5 European centers. We calculated for each center and for the pooled cohort CSF Aβ42 and Aβ42/tau ratio cutpoints for cortical amyloid deposition based on visual interpretation of [11C......]PiB-PET images. RESULTS: Amyloid-PET-based calculated CSF Aβ42 cutpoints ranged from 521 to 616 pg/mL, whereas existing clinical-based cutpoints ranged from 400 to 550 pg/mL. Using the calculated cutpoint from the pooled sample (557 pg/mL), concordance between CSF Aβ42 and amyloid-PET was 84%. Similar...

MR Microimaging of amyloid plaques in Alzheimer's disease transgenic mice

International Nuclear Information System (INIS)

Wengenack, Thomas M.; Poduslo, Joseph F.; Jack, Clifford R.; Garwood, Michael

2008-01-01

Alzheimer's disease (AD) is the most prevalent neurological condition affecting industrialized nations and will rapidly become a healthcare crisis as the population ages. Currently, the post-mortem histological observation of amyloid plaques and neurofibrillary tangles is the only definitive diagnosis available for AD. A pre-mortem biological or physiological marker specific for AD used in conjunction with current neurological and memory testing could add a great deal of confidence to the diagnosis of AD and potentially allow therapeutic intervention much earlier in the disease process. Our group has developed MRI techniques to detect individual amyloid plaques in AD transgenic mouse brain in vivo. We are also developing contrast-enhancing agents to increase the specificity of detection of amyloid plaques. Such in vivo imaging of amyloid plaques will also allow the evaluation of anti-amyloid therapies being developed by the pharmaceutical industry in pre-clinical trials of AD transgenic mice. This short review briefly discusses our progress in these areas. (orig.)

A Novel Small Molecule Modulator of Amyloid Pathology.

Science.gov (United States)

Lovell, Mark A; Lynn, Bert C; Fister, Shuling; Bradley-Whitman, Melissa; Murphy, M Paul; Beckett, Tina L; Norris, Christopher M

2016-05-04

Because traditional approaches to drug development for Alzheimer's disease are becoming increasingly expensive and in many cases disappointingly unsuccessful, alternative approaches are required to shift the paradigm. Following leads from investigations of dihydropyridine calcium channel blockers, we observed unique properties from a class of functionalized naphthyridines and sought to develop these as novel therapeutics that minimize amyloid pathology without the adverse effects associated with current therapeutics. Our data show methyl 2,4-dimethyl-5-oxo-5,6-dihydrobenzo[c][2,7]naphthyridine-1-carboxylate (BNC-1) significantly decreases amyloid burden in a well-established mouse model of amyloid pathology through a unique mechanism mediated by Elk-1, a transcriptional repressor of presenilin-1. Additionally, BNC-1 treatment leads to increased levels of synaptophysin and synapsin, markers of synaptic integrity, but does not adversely impact presenilin-2 or processing of Notch-1, thus avoiding negative off target effects associated with pan-gamma secretase inhibition. Overall, our data show BNC-1 significantly decreases amyloid burden and improves markers of synaptic integrity in a well-established mouse model of amyloid deposition by promoting phosphorylation and activation of Elk-1, a transcriptional repressor of presenilin-1 but not presenilin-2. These data suggest BNC-1 might be a novel, disease-modifying therapeutic that will alter the pathogenesis of Alzheimer's disease.

Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds

Directory of Open Access Journals (Sweden)

Massimo Stefani

2013-06-01

Full Text Available Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i to stabilize toxic amyloid precursors; (ii to prevent the growth of toxic oligomers or speed that of fibrils; (iii to inhibit fibril growth and deposition; (iv to disassemble preformed fibrils; and (v to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols.

Interaction of amyloid inhibitor proteins with amyloid beta peptides: insight from molecular dynamics simulations.

Directory of Open Access Journals (Sweden)

Payel Das

Full Text Available Knowledge of the detailed mechanism by which proteins such as human αB- crystallin and human lysozyme inhibit amyloid beta (Aβ peptide aggregation is crucial for designing treatment for Alzheimer's disease. Thus, unconstrained, atomistic molecular dynamics simulations in explicit solvent have been performed to characterize the Aβ17-42 assembly in presence of the αB-crystallin core domain and of lysozyme. Simulations reveal that both inhibitor proteins compete with inter-peptide interaction by binding to the peptides during the early stage of aggregation, which is consistent with their inhibitory action reported in experiments. However, the Aβ binding dynamics appear different for each inhibitor. The binding between crystallin and the peptide monomer, dominated by electrostatics, is relatively weak and transient due to the heterogeneous amino acid distribution of the inhibitor surface. The crystallin-bound Aβ oligomers are relatively long-lived, as they form more extensive contact surface with the inhibitor protein. In contrast, a high local density of arginines from lysozyme allows strong binding with Aβ peptide monomers, resulting in stable complexes. Our findings not only illustrate, in atomic detail, how the amyloid inhibitory mechanism of human αB-crystallin, a natural chaperone, is different from that of human lysozyme, but also may aid de novo design of amyloid inhibitors.

The proton-pump inhibitor lansoprazole enhances amyloid beta production.

Science.gov (United States)

Badiola, Nahuai; Alcalde, Victor; Pujol, Albert; Münter, Lisa-Marie; Multhaup, Gerd; Lleó, Alberto; Coma, Mireia; Soler-López, Montserrat; Aloy, Patrick

2013-01-01

A key event in the pathogenesis of Alzheimer's disease (AD) is the accumulation of amyloid-β (Aβ) species in the brain, derived from the sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. Based on a systems biology study to repurpose drugs for AD, we explore the effect of lansoprazole, and other proton-pump inhibitors (PPIs), on Aβ production in AD cellular and animal models. We found that lansoprazole enhances Aβ37, Aβ40 and Aβ42 production and lowers Aβ38 levels on amyloid cell models. Interestingly, acute lansoprazole treatment in wild type and AD transgenic mice promoted higher Aβ40 levels in brain, indicating that lansoprazole may also exacerbate Aβ production in vivo. Overall, our data presents for the first time that PPIs can affect amyloid metabolism, both in vitro and in vivo.

Variation of amino acid sequences of serum amyloid a (SAA) and immunohistochemical analysis of amyloid a (AA) in Japanese domestic cats.

Science.gov (United States)

Tei, Meina; Uchida, Kazuyuki; Chambers, James K; Watanabe, Ken-Ichi; Tamamoto, Takashi; Ohno, Koichi; Nakayama, Hiroyuki

2018-02-02

Amyloid A (AA) amyloidosis, a fatal systemic amyloid disease, occurs secondary to chronic inflammatory conditions in humans. Although persistently elevated serum amyloid A (SAA) levels are required for its pathogenesis, not all individuals with chronic inflammation necessarily develop AA amyloidosis. Furthermore, many diseases in cats are associated with the elevated production of SAA, whereas only a small number actually develop AA amyloidosis. We hypothesized that a genetic mutation in the SAA gene may strongly contribute to the pathogenesis of feline AA amyloidosis. In the present study, genomic DNA from four Japanese domestic cats (JDCs) with AA amyloidosis and from five without amyloidosis was analyzed using polymerase chain reaction (PCR) amplification and direct sequencing. We identified the novel variation combination of 45R-51A in the deduced amino acid sequences of four JDCs with amyloidosis and five without. However, there was no relationship between amino acid variations and the distribution of AA amyloid deposits, indicating that differences in SAA sequences do not contribute to the pathogenesis of AA amyloidosis. Immunohistochemical analysis using antisera against the three different parts of the feline SAA protein-i.e., the N-terminal, central, and C-terminal regions-revealed that feline AA contained the C-terminus, unlike human AA. These results indicate that the cleavage and degradation of the C-terminus are not essential for amyloid fibril formation in JDCs.

Two-Step Amyloid Aggregation: Sequential Lag Phase Intermediates

Science.gov (United States)

Castello, Fabio; Paredes, Jose M.; Ruedas-Rama, Maria J.; Martin, Miguel; Roldan, Mar; Casares, Salvador; Orte, Angel

2017-01-01

The self-assembly of proteins into fibrillar structures called amyloid fibrils underlies the onset and symptoms of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. However, the molecular basis and mechanism of amyloid aggregation are not completely understood. For many amyloidogenic proteins, certain oligomeric intermediates that form in the early aggregation phase appear to be the principal cause of cellular toxicity. Recent computational studies have suggested the importance of nonspecific interactions for the initiation of the oligomerization process prior to the structural conversion steps and template seeding, particularly at low protein concentrations. Here, using advanced single-molecule fluorescence spectroscopy and imaging of a model SH3 domain, we obtained direct evidence that nonspecific aggregates are required in a two-step nucleation mechanism of amyloid aggregation. We identified three different oligomeric types according to their sizes and compactness and performed a full mechanistic study that revealed a mandatory rate-limiting conformational conversion step. We also identified the most cytotoxic species, which may be possible targets for inhibiting and preventing amyloid aggregation.

Prevalence of cerebral amyloid pathology in persons without dementia

DEFF Research Database (Denmark)

Jansen, Willemijn J; Ossenkoppele, Rik; Knol, Dirk L

2015-01-01

IMPORTANCE: Cerebral amyloid-β aggregation is an early pathological event in Alzheimer disease (AD), starting decades before dementia onset. Estimates of the prevalence of amyloid pathology in persons without dementia are needed to understand the development of AD and to design prevention studies...

Nonequilibrium and generalized-ensemble molecular dynamics simulations for amyloid fibril

Energy Technology Data Exchange (ETDEWEB)

Okumura, Hisashi [Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan); Department of Structural Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585 (Japan)

2015-12-31

Amyloids are insoluble and misfolded fibrous protein aggregates and associated with more than 20 serious human diseases. We perform all-atom molecular dynamics simulations of amyloid fibril assembly and disassembly.

Calumenin interacts with serum amyloid P component

DEFF Research Database (Denmark)

Vorum, H; Jacobsen, Christian; Honoré, Bent

2000-01-01

with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate...... in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues. Udgivelsesdato: 2000-Jan-14...

Nasal administration of amyloid-beta peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease

DEFF Research Database (Denmark)

Weiner, H L; Lemere, C A; Maron, R

2000-01-01

Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease-implicated ......Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease...... cerebral Abeta deposition, suggesting a novel mucosal immunological approach for the treatment and prevention of AD....

Safety of disclosing amyloid status in cognitively normal older adults.

Science.gov (United States)

Burns, Jeffrey M; Johnson, David K; Liebmann, Edward P; Bothwell, Rebecca J; Morris, Jill K; Vidoni, Eric D

2017-09-01

Disclosing amyloid status to cognitively normal individuals remains controversial given our lack of understanding the test's clinical significance and unknown psychological risk. We assessed the effect of amyloid status disclosure on anxiety and depression before disclosure, at disclosure, and 6 weeks and 6 months postdisclosure and test-related distress after disclosure. Clinicians disclosed amyloid status to 97 cognitively normal older adults (27 had elevated cerebral amyloid). There was no difference in depressive symptoms across groups over time. There was a significant group by time interaction in anxiety, although post hoc analyses revealed no group differences at any time point, suggesting a minimal nonsustained increase in anxiety symptoms immediately postdisclosure in the elevated group. Slight but measureable increases in test-related distress were present after disclosure and were related to greater baseline levels of anxiety and depression. Disclosing amyloid imaging results to cognitively normal adults in the clinical research setting with pre- and postdisclosure counseling has a low risk of psychological harm. Copyright © 2017 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Powerful beneficial effects of benfotiamine on cognitive impairment and beta-amyloid deposition in amyloid precursor protein/presenilin-1 transgenic mice.

Science.gov (United States)

Pan, Xiaoli; Gong, Neng; Zhao, Jing; Yu, Zhe; Gu, Fenghua; Chen, Jia; Sun, Xiaojing; Zhao, Lei; Yu, Meijing; Xu, Zhiru; Dong, Wenxin; Qin, Yan; Fei, Guoqiang; Zhong, Chunjiu; Xu, Tian-Le

2010-05-01

Reduction of glucose metabolism in brain is one of the main features of Alzheimer's disease. Thiamine (vitamin B1)-dependent processes are critical in glucose metabolism and have been found to be impaired in brains from patients with Alzheimer's disease. However, thiamine treatment exerts little beneficial effect in these patients. Here, we tested the effect of benfotiamine, a thiamine derivative with better bioavailability than thiamine, on cognitive impairment and pathology alterations in a mouse model of Alzheimer's disease, the amyloid precursor protein/presenilin-1 transgenic mouse. We show that after a chronic 8 week treatment, benfotiamine dose-dependently enhanced the spatial memory of amyloid precursor protein/presenilin-1 mice in the Morris water maze test. Furthermore, benfotiamine effectively reduced both amyloid plaque numbers and phosphorylated tau levels in cortical areas of the transgenic mice brains. Unexpectedly, these effects were not mimicked by another lipophilic thiamine derivative, fursultiamine, although both benfotiamine and fursultiamine were effective in increasing the levels of free thiamine in the brain. Most notably, benfotiamine, but not fursultiamine, significantly elevated the phosphorylation level of glycogen synthase kinase-3alpha and -3beta, and reduced their enzymatic activities in the amyloid precursor protein/presenilin-1 transgenic brain. Therefore, in the animal Alzheimer's disease model, benfotiamine appears to improve the cognitive function and reduce amyloid deposition via thiamine-independent mechanisms, which are likely to include the suppression of glycogen synthase kinase-3 activities. These results suggest that, unlike many other thiamine-related drugs, benfotiamine may be beneficial for clinical Alzheimer's disease treatment.

New Insights in the Amyloid-Beta Interaction with Mitochondria

Directory of Open Access Journals (Sweden)

Carlos Spuch

2012-01-01

Full Text Available Biochemical and morphological alterations of mitochondria may play an important role in the pathogenesis of Alzheimer’s disease (AD. Particularly, mitochondrial dysfunction is a hallmark of amyloid-beta-induced neuronal toxicity in Alzheimer’s disease. The recent emphasis on the intracellular biology of amyloid-beta and its precursor protein (APP has led researchers to consider the possibility that mitochondria-associated and mitochondrial amyloid-beta may directly cause neurotoxicity. Both proteins are known to localize to mitochondrial membranes, block the transport of nuclear-encoded mitochondrial proteins to mitochondria, interact with mitochondrial proteins, disrupt the electron transport chain, increase reactive oxygen species production, cause mitochondrial damage, and prevent neurons from functioning normally. In this paper, we will outline current knowledge of the intracellular localization of amyloid-beta. Moreover, we summarize evidence from AD postmortem brain as well as animal AD models showing that amyloid-beta triggers mitochondrial dysfunction through a number of pathways such as impairment of oxidative phosphorylation, elevation of reactive oxygen species production, alteration of mitochondrial dynamics, and interaction with mitochondrial proteins. Thus, this paper supports the Alzheimer cascade mitochondrial hypothesis such as the most important early events in this disease, and probably one of the future strategies on the therapy of this neurodegenerative disease.

Glycation induces formation of amyloid cross-beta structure in albumin.

Science.gov (United States)

Bouma, Barend; Kroon-Batenburg, Loes M J; Wu, Ya-Ping; Brünjes, Bettina; Posthuma, George; Kranenburg, Onno; de Groot, Philip G; Voest, Emile E; Gebbink, Martijn F B G

2003-10-24

Amyloid fibrils are components of proteinaceous plaques that are associated with conformational diseases such as Alzheimer's disease, transmissible spongiform encephalopathies, and familial amyloidosis. Amyloid polypeptides share a specific quarternary structure element known as cross-beta structure. Commonly, fibrillar aggregates are modified by advanced glycation end products (AGE). In addition, AGE formation itself induces protein aggregation. Both amyloid proteins and protein-AGE adducts bind multiligand receptors, such as receptor for AGE, CD36, and scavenger receptors A and B type I, and the serine protease tissue-type plasminogen activator (tPA). Based on these observations, we hypothesized that glycation induces refolding of globular proteins, accompanied by formation of cross-beta structure. Using transmission electron microscopy, we demonstrate here that glycated albumin condensates into fibrous or amorphous aggregates. These aggregates bind to amyloid-specific dyes Congo red and thioflavin T and to tPA. In contrast to globular albumin, glycated albumin contains amino acid residues in beta-sheet conformation, as measured with circular dichroism spectropolarimetry. Moreover, it displays cross-beta structure, as determined with x-ray fiber diffraction. We conclude that glycation induces refolding of initially globular albumin into amyloid fibrils comprising cross-beta structure. This would explain how glycated ligands and amyloid ligands can bind to the same multiligand "cross-beta structure" receptors and to tPA.

Spectroscopic study of Alzheimer's amyloid fibrils using terahertz time domain spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Jung, Euna; Kim, Jeonghoi; Han, Younho; Moon, Kiwon; Lim, Meehyun; Han, Haewook; Park, Joonhyuck; Kim, Sungjee [POSTECH, Pohang (Korea, Republic of)

2008-11-15

Alzheimer's disease, one of the most common neurodegenerative diseases, is characterized by extensive amyloid deposition. Amyloid deposits contain the abundant fibrils formed by amyloid β protein (Aβ). Because amyloid fibrils are associated with amyloid diseases, including Alzheimer's disease, type 2 diabetes, prion disease, Parkinson's disease, senile systemic amyloidosis and Huntington's disease, there has been considerable interest within the biomedical and biochemical research communities. In transmission electron microscopic (TEM)images, amyloid firils are 0.1∼10μm long and approximately 10nm wide. Amyloid fibrils commonly exhibit self assembled filaments, often described as twisted or parallel assemblies of finer protofilaments. They are formed by the spontaneous aggregation of a wide variety of peptides and proteins. Structural studies of amyloid fibrils have revealed that the common structural motif of virtually all amyloid fibrils consists of cross β sheets in which the peptide strands are arranged perpendicular to the long axis of the fiber. But little was known until recently about the molecular level structures of amyloid fibils. Therefore, spectroscopic investigation of both amyloid fibrils and Aβ at the molecular level can provide the significant evidence for the molecular understanding of amyloidogenesis and for the development of innovative therapeutic and diagnostic approaches. We used terahertz time domain spectroscopy (THz TDS)to investigate both Aβ and amyloid fibril. THz TDS, developed over the last two decades, is a powerful tool to extract the properties of biomaterials and provides unique spectral signatures of biomolecules within 0.1∼10THz, which exists between microwave and infrared frequency range. Current interest in THz radiation arises from its capability of probing the delocalized collective vibrational modes in proteins. Studying the collective modes of proteins in THz frequency range can play an

Repurposing Hsp104 to Antagonize Seminal Amyloid and Counter HIV Infection.

Science.gov (United States)

Castellano, Laura M; Bart, Stephen M; Holmes, Veronica M; Weissman, Drew; Shorter, James

2015-08-20

Naturally occurring proteolytic fragments of prostatic acid phosphatase (PAP248-286 and PAP85-120) and semenogelins (SEM1 and SEM2) form amyloid fibrils in seminal fluid, which capture HIV virions and promote infection. For example, PAP248-286 fibrils, termed SEVI (semen-derived enhancer of viral infection), can potentiate HIV infection by several orders of magnitude. Here, we design three disruptive technologies to rapidly antagonize seminal amyloid by repurposing Hsp104, an amyloid-remodeling nanomachine from yeast. First, Hsp104 and an enhanced engineered variant, Hsp104(A503V), directly remodel SEVI and PAP85-120 fibrils into non-amyloid forms. Second, we elucidate catalytically inactive Hsp104 scaffolds that do not remodel amyloid structure, but cluster SEVI, PAP85-120, and SEM1(45-107) fibrils into larger assemblies. Third, we modify Hsp104 to interact with the chambered protease ClpP, which enables coupled remodeling and degradation to irreversibly clear SEVI and PAP85-120 fibrils. Each strategy diminished the ability of seminal amyloid to promote HIV infection, and could have therapeutic utility. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stop-and-go kinetics in amyloid fibrillation

DEFF Research Database (Denmark)

Ferkinghoff-Borg, Jesper; Fonslet, Jesper; Andersen, Christian Beyschau

2010-01-01

Many human diseases are associated with protein aggregation and fibrillation. We present experiments on in vitro glucagon fibrillation using total internal reflection fluorescence microscopy, providing real-time measurements of single-fibril growth. We find that amyloid fibrils grow in an intermi......Many human diseases are associated with protein aggregation and fibrillation. We present experiments on in vitro glucagon fibrillation using total internal reflection fluorescence microscopy, providing real-time measurements of single-fibril growth. We find that amyloid fibrils grow...

Interaction between amyloid beta peptide and an aggregation blocker peptide mimicking islet amyloid polypeptide.

Directory of Open Access Journals (Sweden)

Nasrollah Rezaei-Ghaleh

Full Text Available Assembly of amyloid-beta peptide (Aβ into cytotoxic oligomeric and fibrillar aggregates is believed to be a major pathologic event in Alzheimer's disease (AD and interfering with Aβ aggregation is an important strategy in the development of novel therapeutic approaches. Prior studies have shown that the double N-methylated analogue of islet amyloid polypeptide (IAPP IAPP-GI, which is a conformationally constrained IAPP analogue mimicking a non-amyloidogenic IAPP conformation, is capable of blocking cytotoxic self-assembly of Aβ. Here we investigate the interaction of IAPP-GI with Aβ40 and Aβ42 using NMR spectroscopy. The most pronounced NMR chemical shift changes were observed for residues 13-20, while residues 7-9, 15-16 as well as the C-terminal half of Aβ--that is both regions of the Aβ sequence that are converted into β-strands in amyloid fibrils--were less accessible to solvent in the presence of IAPP-GI. At the same time, interaction of IAPP-GI with Aβ resulted in a concentration-dependent co-aggregation of Aβ and IAPP-GI that was enhanced for the more aggregation prone Aβ42 peptide. On the basis of the reduced toxicity of the Aβ peptide in the presence of IAPP-GI, our data are consistent with the suggestion that IAPP-GI redirects Aβ into nontoxic "off-pathway" aggregates.

Amyloid PET in pseudotumoral multiple sclerosis.

Science.gov (United States)

Matías-Guiu, Jordi A; Cabrera-Martín, María Nieves; Cortés-Martínez, Ana; Pytel, Vanesa; Moreno-Ramos, Teresa; Oreja-Guevara, Celia; Carreras, José Luis; Matías-Guiu, Jorge

2017-07-01

Pseudotumoral multiple sclerosis is a rare form of demyelinating disease of the central nervous system. Positron emission tomography (PET) using amyloid-tracers has also been suggested as a marker of damage in white matter lesions in multiple sclerosis due to the nonspecific uptake of these tracers in white matter. We present the case of a 59 year-old woman with a pathological-confirmed pseudotumoral multiple sclerosis, who was studied with the amyloid tracer 18 F-florbetaben. The patient had developed word-finding difficulties and right hemianopia twelve years ago. In that time, MRI showed a lesion on the left hemisphere with an infiltrating aspect in frontotemporal lobes. Brain biopsy showed demyelinating areas and inflammation. During the following years, two new clinical relapses occurred. 18 F-florbetaben PET showed lower uptake in the white matter lesion visualized in the CT and MRI images. Decreased tracer uptake was also observed in a larger area of the left hemisphere beyond the lesions observed on MRI or CT. White matter lesion volume on FLAIR was 44.2mL, and tracer uptake change between damaged white matter and normal appearing white matter was - 40.5%. Standardized uptake value was inferior in the pseudotumoral lesion than in the other white matter lesions. We report the findings of amyloid PET in a patient with pseudotumoral multiple sclerosis. This case provides further evidence on the role of amyloid PET in the assessment of white matter and demyelinating diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrafast Hydrogen-Bonding Dynamics in Amyloid Fibrils.

Science.gov (United States)

Pazos, Ileana M; Ma, Jianqiang; Mukherjee, Debopreeti; Gai, Feng

2018-06-08

While there are many studies on the subject of hydrogen bonding dynamics in biological systems, few, if any, have investigated this fundamental process in amyloid fibrils. Herein, we seek to add insight into this topic by assessing the dynamics of a hydrogen bond buried in the dry interface of amyloid fibrils. To prepare a suitable model peptide system for this purpose, we introduce two mutations into the amyloid-forming Aβ(16-22) peptide. The first one is a lysine analog at position 19, which is used to help form structurally homogeneous fibrils, and the second one is an aspartic acid derivative (DM) at position 17, which is intended (1) to be used as a site-specific infrared probe and (2) to serve as a hydrogen-bond acceptor to lysine so that an inter-β-sheet hydrogen bond can be formed in the fibrils. Using both infrared spectroscopy and atomic force microscopy, we show that (1) this mutant peptide indeed forms well defined fibrils, (2) when bulk solvent is removed, there is no detectable water present in the fibrils, (3) infrared results obtained with the DM probe are consistent with a protofibril structure that is composed of two antiparallel β-sheets stacked in a parallel fashion, leading to formation of the expected hydrogen bond. Using two-dimensional infrared spectroscopy, we further show that the dynamics of this hydrogen bond occur on a timescale of ~2.3 ps, which is attributed to the rapid rotation of the -NH3+ group of lysine around its Cε-Nζ bond. Taken together, these results suggest that (1) DM is a useful infrared marker in facilitating structure determination of amyloid fibrils and (2) even in the tightly packed core of amyloid fibrils certain amino acid sidechains can undergo ultrafast motions, hence contributing to the thermodynamic stability of the system.

Surface Mediated Self-Assembly of Amyloid Peptides

Science.gov (United States)

Fakhraai, Zahra

2015-03-01

Amyloid fibrils have been considered as causative agents in many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, type II diabetes and amyloidosis. Amyloid fibrils form when proteins or peptides misfold into one dimensional crystals of stacked beta-sheets. In solution, amyloid fibrils form through a nucleation and growth mechanism. The rate limiting nucleation step requires a critical concentration much larger than those measured in physiological conditions. As such the exact origins of the seeds or oligomers that result in the formation of fully mature fibrils in the body remain topic intense studies. It has been suggested that surfaces and interfaces can enhance the fibrillization rate. However, studies of the mechanism and kinetics of the surface-mediated fibrillization are technologically challenging due to the small size of the oligomer and protofibril species. Using smart sample preparation technique to dry the samples after various incubation times we are able to study the kinetics of fibril formation both in solution and in the vicinity of various surfaces using high-resolution atomic force microscopy. These studies elucidate the role of surfaces in catalyzing amyloid peptide formation through a nucleation-free process. The nucleation free self-assembly is rapid and requires much smaller concentrations of peptides or proteins. We show that this process resembles diffusion limited aggregation and is governed by the peptide adhesion rate, two -dimensional diffusion of the peptides on the surface, and preferential interactions between the peptides. These studies suggest an alternative pathway for amyloid formation may exist, which could lead to new criteria for disease prevention and alternative therapies. Research was partially supported by a seed grant from the National Institute of Aging of the National Institutes of Health (NIH) under Award Number P30AG010124 (PI: John Trojanowski) and the University of Pennsylvania.

The molecular mass of dextran used to modify magnetite nanoparticles affects insulin amyloid aggregation

International Nuclear Information System (INIS)

Siposova, Katarina; Pospiskova, Kristyna; Bednarikova, Zuzana; Safarik, Ivo; Safarikova, Mirka; Kubovcikova, Martina; Kopcansky, Peter; Gazova, Zuzana

2017-01-01

Protein transformation from its soluble state into amyloid aggregates is associated with amyloid-related diseases. Amyloid deposits of insulin fibrils have been found in the sites of subcutaneous insulin application in patients with prolonged diabetes. Using atomic force microscopy and ThT fluorescence assay we have investigated the interference of insulin amyloid aggregation with superparamagnetic Fe 3 O 4 -based nanoparticles (SPIONs) coated with dextran (DEX); molecular mass of dextran was equal to 15–20, 40 or 70 kDa. The obtained data indicate that all three types of dextran coated nanoparticles (NP-FeDEXs) are able to inhibit insulin fibrillization and to destroy amyloid fibrils. The extent of anti-amyloid activities depends on the properties of NP-FeDEXs, mainly on the size of nanoparticles which is determined by molecular mass of dextran molecules. The most effective inhibiting activity was observed for the smallest nanoparticles coated with 15–20 kDa dextran. Contrary, the highest destroying activity was observed for the largest NP-FeDEX (70 kDa dextran). - Highlights: • Interference of dextran- magnetite nanoparticles with insulin amyloid aggregation. • Nanoparticles inhibited insulin fibrillization and depolymerized insulin amyloid fibrils. • Size of nanoparticles significantly influences their anti-amyloid activities. • The most effective inhibition of insulin amyloid fibrillization was detected for the smallest nanoparticles. • Contrary, DC 50 values decreased with increasing size of nanoparticles.

Case report 480: Periosteal amyloid tumor

International Nuclear Information System (INIS)

Yoshida, S.O.; Karjoo, R.; Johnstone, M.R.

1988-01-01

In summary, a 66-year-old woman presented with an asymptomatic left pretibial tumor of 7 years duration. Serial radiographs over this period demonstrated a slowly enlarging periosteal tumor with focal and increasing calcifications/ossifications. No involvement of the underlying medullary bone, as demonstrated by computed tomography was noted. Following the diagnosis by biopsy of an amyloid tumor, serum and urine electrophoreses, complete blood count, SMAC panel, erythrocyte sedimentation rate, and serum rheumatoid factor level were found to be within reference ranges. A needle biopsy of the abdominal wall failed to reveal amyloid in the fat by Congo-red staining. (orig.)

Concordance Between Different Amyloid Immunoassays and Visual Amyloid Positron Emission Tomographic Assessment.

Science.gov (United States)

Janelidze, Shorena; Pannee, Josef; Mikulskis, Alvydas; Chiao, Ping; Zetterberg, Henrik; Blennow, Kaj; Hansson, Oskar

2017-12-01

Visual assessment of amyloid positron emission tomographic (PET) images has been approved by regulatory authorities for clinical use. Several immunoassays have been developed to measure β-amyloid (Aβ) 42 in cerebrospinal fluid (CSF). The agreement between CSF Aβ42 measures from different immunoassays and visual PET readings may influence the use of CSF biomarkers and/or amyloid PET assessment in clinical practice and trials. To determine the concordance between CSF Aβ42 levels measured using 5 different immunoassays and visual amyloid PET analysis. The study included 262 patients with mild cognitive impairment or subjective cognitive decline from the Swedish BioFINDER (Biomarkers for Identifying Neurodegenerative Disorders Early and Reliably) cohort (recruited from September 1, 2010, through December 31, 2014) who had undergone flutemetamol F 18 ([18F]flutemetamol)-labeled PET. Levels of CSF Aβ42 were analyzed using the classic INNOTEST and the newer modified INNOTEST, fully automated Lumipulse (FL), EUROIMMUN (EI), and Meso Scale Discovery (MSD) assays. Concentrations of CSF Aβ were assessed using an antibody-independent mass spectrometry-based reference measurement procedure. The concordance of CSF Aβ42 levels and Aβ42:Aβ40 and Aβ42:tau ratios with visual [18F]flutemetamol PET status. Of 262 participants (mean [SD] age, 70.9 [5.5] years), 108 were women (41.2%) and 154 were men (58.8%). The mass spectrometry-derived Aβ42 values showed higher correlations with the modified Aβ42-INNOTEST (r = 0.97), Aβ42-FL (r = 0.93), Aβ42-EI (r = 0.93), and Aβ42-MSD (r = 0.95) assays compared with the classic Aβ42-INNOTEST assay (r = 0.88; P ≤ .01). The signal in the classic Aβ42-INNOTEST assay was partly quenched by recombinant Aβ1-40 peptide. However, the classic Aβ42-INNOTEST assay showed better concordance with visual [18F]flutemetamol PET status (area under the receiver operating characteristic curve [AUC], 0.92) compared with the

FKBP12 regulates the localization and processing of amyloid ...

Indian Academy of Sciences (India)

2014-01-27

Jan 27, 2014 ... One of the pathological hallmarks of Alzheimer's disease is the presence of insoluble extracellular amyloid plaques. These plaques ... The proteolytic cleavage of amyloid precursor protein (APP) ..... lower sAPPα/sAPPs ratio, which may lead to an increase in ..... spine density in healthy adult mouse brain.

Ligand-binding sites in human serum amyloid P component

DEFF Research Database (Denmark)

Heegaard, N.H.H.; Heegaard, Peter M. H.; Roepstorff, P.

1996-01-01

Amyloid P component (AP) is a naturally occurring glycoprotein that is found in serum and basement membranes, AP is also a component of all types of amyloid, including that found in individuals who suffer from Alzheimer's disease and Down's syndrome. Because AP has been found to bind strongly...

Amyloid Fibrils as Building Blocks for Natural and Artificial Functional Materials.

Science.gov (United States)

Knowles, Tuomas P J; Mezzenga, Raffaele

2016-08-01

Proteinaceous materials based on the amyloid core structure have recently been discovered at the origin of biological functionality in a remarkably diverse set of roles, and attention is increasingly turning towards such structures as the basis of artificial self-assembling materials. These roles contrast markedly with the original picture of amyloid fibrils as inherently pathological structures. Here we outline the salient features of this class of functional materials, both in the context of the functional roles that have been revealed for amyloid fibrils in nature, as well as in relation to their potential as artificial materials. We discuss how amyloid materials exemplify the emergence of function from protein self-assembly at multiple length scales. We focus on the connections between mesoscale structure and material function, and demonstrate how the natural examples of functional amyloids illuminate the potential applications for future artificial protein based materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Technical considerations on scanning and image analysis for amyloid PET in dementia

International Nuclear Information System (INIS)

Akamatsu, Go; Ohnishi, Akihito; Aita, Kazuki; Ikari, Yasuhiko; Senda, Michio; Yamamoto, Yasuji

2017-01-01

Brain imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET), can provide essential and objective information for the early and differential diagnosis of dementia. Amyloid PET is especially useful to evaluate the amyloid-β pathological process as a biomarker of Alzheimer's disease. This article reviews critical points about technical considerations on the scanning and image analysis methods for amyloid PET. Each amyloid PET agent has its own proper administration instructions and recommended uptake time, scan duration, and the method of image display and interpretation. In addition, we have introduced general scanning information, including subject positioning, reconstruction parameters, and quantitative and statistical image analysis. We believe that this article could make amyloid PET a more reliable tool in clinical study and practice. (author)

Technical Considerations on Scanning and Image Analysis for Amyloid PET in Dementia.

Science.gov (United States)

Akamatsu, Go; Ohnishi, Akihito; Aita, Kazuki; Ikari, Yasuhiko; Yamamoto, Yasuji; Senda, Michio

2017-01-01

Brain imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET), can provide essential and objective information for the early and differential diagnosis of dementia. Amyloid PET is especially useful to evaluate the amyloid-β pathological process as a biomarker of Alzheimer's disease. This article reviews critical points about technical considerations on the scanning and image analysis methods for amyloid PET. Each amyloid PET agent has its own proper administration instructions and recommended uptake time, scan duration, and the method of image display and interpretation. In addition, we have introduced general scanning information, including subject positioning, reconstruction parameters, and quantitative and statistical image analysis. We believe that this article could make amyloid PET a more reliable tool in clinical study and practice.

Differential regulation of amyloid precursor protein sorting with pathological mutations results in a distinct effect on amyloid-β production.

Science.gov (United States)

Lin, Yen-Chen; Wang, Jia-Yi; Wang, Kai-Chen; Liao, Jhih-Ying; Cheng, Irene H

2014-11-01

The deposition of amyloid-β (Aβ) peptide, which is generated from amyloid precursor protein (APP), is the pathological hallmark of Alzheimer's disease (AD). Three APP familial AD mutations (D678H, D678N, and H677R) located at the sixth and seventh amino acid of Aβ have distinct effect on Aβ aggregation, but their influence on the physiological and pathological roles of APP remain unclear. We found that the D678H mutation strongly enhances amyloidogenic cleavage of APP, thus increasing the production of Aβ. This enhancement of amyloidogenic cleavage is likely because of the acceleration of APPD678H sorting into the endosomal-lysosomal pathway. In contrast, the APPD678N and APPH677R mutants do not cause the same effects. Therefore, this study indicates a regulatory role of D678H in APP sorting and processing, and provides genetic evidence for the importance of APP sorting in AD pathogenesis. The internalization of amyloid precursor protein (APP) increases its opportunity to be processed by β-secretase and to produce Amyloid-β (Aβ) that causes Alzheimer's disease (AD). We report a pathogenic APPD678H mutant that enhances APP internalization into the endosomal-lysosomal pathway and thus promotes the β-secretase cleavage and Aβ production. This study provides genetic evidence for the importance of APP sorting in AD pathogenesis. © 2014 International Society for Neurochemistry.

The molecular mass of dextran used to modify magnetite nanoparticles affects insulin amyloid aggregation

Energy Technology Data Exchange (ETDEWEB)

Siposova, Katarina [Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Pospiskova, Kristyna [Regional Centre of Advanced Technologies and Materials, Palacky University, Olomouc (Czech Republic); Bednarikova, Zuzana [Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Department of Biochemistry, Faculty of Science, Safarik University, Kosice (Slovakia); Safarik, Ivo [Regional Centre of Advanced Technologies and Materials, Palacky University, Olomouc (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Ceske Budejovice (Czech Republic); Safarikova, Mirka [Department of Nanobiotechnology, Biology Centre, ISB, CAS, Ceske Budejovice (Czech Republic); Kubovcikova, Martina; Kopcansky, Peter [Department of Magnetism, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Gazova, Zuzana, E-mail: gazova@saske.sk [Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia)

2017-04-01

Protein transformation from its soluble state into amyloid aggregates is associated with amyloid-related diseases. Amyloid deposits of insulin fibrils have been found in the sites of subcutaneous insulin application in patients with prolonged diabetes. Using atomic force microscopy and ThT fluorescence assay we have investigated the interference of insulin amyloid aggregation with superparamagnetic Fe{sub 3}O{sub 4}-based nanoparticles (SPIONs) coated with dextran (DEX); molecular mass of dextran was equal to 15–20, 40 or 70 kDa. The obtained data indicate that all three types of dextran coated nanoparticles (NP-FeDEXs) are able to inhibit insulin fibrillization and to destroy amyloid fibrils. The extent of anti-amyloid activities depends on the properties of NP-FeDEXs, mainly on the size of nanoparticles which is determined by molecular mass of dextran molecules. The most effective inhibiting activity was observed for the smallest nanoparticles coated with 15–20 kDa dextran. Contrary, the highest destroying activity was observed for the largest NP-FeDEX (70 kDa dextran). - Highlights: • Interference of dextran- magnetite nanoparticles with insulin amyloid aggregation. • Nanoparticles inhibited insulin fibrillization and depolymerized insulin amyloid fibrils. • Size of nanoparticles significantly influences their anti-amyloid activities. • The most effective inhibition of insulin amyloid fibrillization was detected for the smallest nanoparticles. • Contrary, DC{sub 50} values decreased with increasing size of nanoparticles.

Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy

Energy Technology Data Exchange (ETDEWEB)

Goldsbury, C.; Wall, J.; Baxa, U.; Simon, M. N.; Steven, A. C.; Engel, A.; Aebi, U.; Muller, S. A.

2011-01-01

Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

Fibrillar dimer formation of islet amyloid polypeptides

Energy Technology Data Exchange (ETDEWEB)

Chiu, Chi-cheng [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States); de Pablo, Juan J. [Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)

2015-05-08

Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

Fibrillar dimer formation of islet amyloid polypeptides

Directory of Open Access Journals (Sweden)

Chi-cheng Chiu

2015-09-01

Full Text Available Amyloid deposits of human islet amyloid polypeptide (hIAPP, a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

Ginkgolide B inhibits the neurotoxicity of prions or amyloid-β1-42

Directory of Open Access Journals (Sweden)

Williams Alun

2004-05-01

Full Text Available Abstract Background Neuronal loss in Alzheimer's or prion diseases is preceded by the accumulation of fibrillar aggregates of toxic proteins (amyloid-β1-42 or the prion protein. Since some epidemiological studies have demonstrated that the EGb 761 extract, from the leaves of the Ginkgo biloba tree, has a beneficial effect on Alzheimer's disease, the effect of some of the major components of the EGb 761 extract on neuronal responses to amyloid-β1-42, or to a synthetic miniprion (sPrP106, were investigated. Methods Components of the EGb 761 extract were tested in 2 models of neurodegeneration. SH-SY5Y neuroblastoma cells were pre-treated with ginkgolides A or B, quercetin or myricetin, and incubated with amyloid-β1-42, sPrP106, or other neurotoxins. After 24 hours neuronal survival and the production of prostaglandin E2 that is closely associated with neuronal death was measured. In primary cortical neurons apoptosis (caspase-3 in response to amyloid-β1-42 or sPrP106 was measured, and in co-cultures the effects of the ginkgolides on the killing of amyloid-β1-42 or sPrP106 damaged neurons by microglia was tested. Results Neurons treated with ginkgolides A or B were resistant to amyloid-β1-42 or sPrP106. Ginkgolide-treated cells were also resistant to platelet activating factor or arachidonic acid, but remained susceptible to hydrogen peroxide or staurosporine. The ginkgolides reduced the production of prostaglandin E2 in response to amyloid-β1-42 or sPrP106. In primary cortical neurons, the ginkgolides reduced caspase-3 responses to amyloid-β1-42 or sPrP106, and in co-culture studies the ginkgolides reduced the killing of amyloid-β1-42 or sPrP106 damaged neurons by microglia. Conclusion Nanomolar concentrations of the ginkgolides protect neurons against the otherwise toxic effects of amyloid-β1-42 or sPrP106. The ginkgolides also prevented the neurotoxicity of platelet activating factor and reduced the production of prostaglandin E2 in

BETASCAN: probable beta-amyloids identified by pairwise probabilistic analysis.

Directory of Open Access Journals (Sweden)

Allen W Bryan

2009-03-01

Full Text Available Amyloids and prion proteins are clinically and biologically important beta-structures, whose supersecondary structures are difficult to determine by standard experimental or computational means. In addition, significant conformational heterogeneity is known or suspected to exist in many amyloid fibrils. Recent work has indicated the utility of pairwise probabilistic statistics in beta-structure prediction. We develop here a new strategy for beta-structure prediction, emphasizing the determination of beta-strands and pairs of beta-strands as fundamental units of beta-structure. Our program, BETASCAN, calculates likelihood scores for potential beta-strands and strand-pairs based on correlations observed in parallel beta-sheets. The program then determines the strands and pairs with the greatest local likelihood for all of the sequence's potential beta-structures. BETASCAN suggests multiple alternate folding patterns and assigns relative a priori probabilities based solely on amino acid sequence, probability tables, and pre-chosen parameters. The algorithm compares favorably with the results of previous algorithms (BETAPRO, PASTA, SALSA, TANGO, and Zyggregator in beta-structure prediction and amyloid propensity prediction. Accurate prediction is demonstrated for experimentally determined amyloid beta-structures, for a set of known beta-aggregates, and for the parallel beta-strands of beta-helices, amyloid-like globular proteins. BETASCAN is able both to detect beta-strands with higher sensitivity and to detect the edges of beta-strands in a richly beta-like sequence. For two proteins (Abeta and Het-s, there exist multiple sets of experimental data implying contradictory structures; BETASCAN is able to detect each competing structure as a potential structure variant. The ability to correlate multiple alternate beta-structures to experiment opens the possibility of computational investigation of prion strains and structural heterogeneity of amyloid

Increased KPI containing amyloid precursor protein in experimental autoimmune encephalomyelitis brains.

Science.gov (United States)

Beilin, Orit; Karussis, Dimitrios M; Korczyn, Amos D; Gurwitz, David; Aronovich, Ramona; Mizrachi-Kol, Rachel; Chapman, Joab

2007-04-16

Amyloid precursor protein can be translated from three alternatively spliced mRNAs. We measured levels of amyloid precursor protein isoforms containing the Kunitz protease inhibitor domain (KPIAPP), and amyloid precursor protein without the Kunitz protease inhibitor domain (KPIAPP) in brain homogenates of acute experimental autoimmune encephalomyelitis mice. At the preclinical phase of the disease, both KPIAPP and KPIAPP levels were significantly higher in homogenates from brains of autoimmune encephalomyelitis mice, whereas at the acute phase of the disease only KPIAPP remained significantly elevated compared with controls. At the recovery phase, no differences were observed between the groups. The early and isoform-specific elevation of KPIAPP in autoimmune encephalomyelitis mice suggests a possible role for amyloid precursor protein in the immune response mediating the disease.

Bacterial inclusion bodies as potential synthetic devices for pathogen recognition and a therapeutic substance release.

Science.gov (United States)

Talafová, Klaudia; Hrabárová, Eva; Chorvát, Dušan; Nahálka, Jozef

2013-02-07

Adhesins of pathogens recognise the glycans on the host cell and mediate adherence. They are also crucial for determining the tissue preferences of pathogens. Currently, glyco-nanomaterials provide potential tool for antimicrobial therapy. We demonstrate that properly glyco-tailored inclusion bodies can specifically bind pathogen adhesins and release therapeutic substances. In this paper, we describe the preparation of tailored inclusion bodies via the conjugation of indicator protein aggregated to form inclusion bodies with soluble proteins. Whereas the indicator protein represents a remedy, the soluble proteins play a role in pathogen recognition. For conjugation, glutaraldehyde was used as linker. The treatment of conjugates with polar lysine, which was used to inactivate the residual glutaraldehyde, inhibited unwanted hydrophobic interactions between inclusion bodies. The tailored inclusion bodies specifically interacted with the SabA adhesin from Helicobacter pylori aggregated to form inclusion bodies that were bound to the sialic acids decorating the surface of human erythrocytes. We also tested the release of indicator proteins from the inclusion bodies using sortase A and Ssp DNAB intein self-cleaving modules, respectively. Sortase A released proteins in a relatively short period of time, whereas the intein cleavage took several weeks. The tailored inclusion bodies are promising "nanopills" for biomedical applications. They are able to specifically target the pathogen, while a self-cleaving module releases a soluble remedy. Various self-cleaving modules can be enabled to achieve the diverse pace of remedy release.

Kinetics of inclusion body formation and its correlation with the characteristics of protein aggregates in Escherichia coli.

Directory of Open Access Journals (Sweden)

Arun K Upadhyay

Full Text Available The objective of the research was to understand the structural determinants governing protein aggregation into inclusion bodies during expression of recombinant proteins in Escherichia coli. Recombinant human growth hormone (hGH and asparaginase were expressed as inclusion bodies in E.coli and the kinetics of aggregate formation was analyzed in details. Asparaginase inclusion bodies were of smaller size (200 nm and the size of the aggregates did not increase with induction time. In contrast, the seeding and growth behavior of hGH inclusion bodies were found to be sequential, kinetically stable and the aggregate size increased from 200 to 800 nm with induction time. Human growth hormone inclusion bodies showed higher resistance to denaturants and proteinase K degradation in comparison to those of asparaginase inclusion bodies. Asparaginase inclusion bodies were completely solubilized at 2-3 M urea concentration and could be refolded into active protein, whereas 7 M urea was required for complete solubilization of hGH inclusion bodies. Both hGH and asparaginase inclusion bodies showed binding with amyloid specific dyes. In spite of its low β-sheet content, binding with dyes was more prominent in case of hGH inclusion bodies than that of asparaginase. Arrangements of protein molecules present in the surface as well as in the core of inclusion bodies were similar. Hydrophobic interactions between partially folded amphiphillic and hydrophobic alpha-helices were found to be one of the main determinants of hGH inclusion body formation. Aggregation behavior of the protein molecules decides the nature and properties of inclusion bodies.

Kinetics of Inclusion Body Formation and Its Correlation with the Characteristics of Protein Aggregates in Escherichia coli

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Upadhyay, Arun K.; Murmu, Aruna; Singh, Anupam; Panda, Amulya K.

2012-01-01

The objective of the research was to understand the structural determinants governing protein aggregation into inclusion bodies during expression of recombinant proteins in Escherichia coli. Recombinant human growth hormone (hGH) and asparaginase were expressed as inclusion bodies in E.coli and the kinetics of aggregate formation was analyzed in details. Asparaginase inclusion bodies were of smaller size (200 nm) and the size of the aggregates did not increase with induction time. In contrast, the seeding and growth behavior of hGH inclusion bodies were found to be sequential, kinetically stable and the aggregate size increased from 200 to 800 nm with induction time. Human growth hormone inclusion bodies showed higher resistance to denaturants and proteinase K degradation in comparison to those of asparaginase inclusion bodies. Asparaginase inclusion bodies were completely solubilized at 2–3 M urea concentration and could be refolded into active protein, whereas 7 M urea was required for complete solubilization of hGH inclusion bodies. Both hGH and asparaginase inclusion bodies showed binding with amyloid specific dyes. In spite of its low β-sheet content, binding with dyes was more prominent in case of hGH inclusion bodies than that of asparaginase. Arrangements of protein molecules present in the surface as well as in the core of inclusion bodies were similar. Hydrophobic interactions between partially folded amphiphillic and hydrophobic alpha-helices were found to be one of the main determinants of hGH inclusion body formation. Aggregation behavior of the protein molecules decides the nature and properties of inclusion bodies. PMID:22479486

Rational heterodoxy: cholesterol reformation of the amyloid doctrine.

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Castello, Michael A; Soriano, Salvador

2013-01-01

According to the amyloid cascade hypothesis, accumulation of the amyloid peptide Aβ, derived by proteolytic processing from the amyloid precursor protein (APP), is the key pathogenic trigger in Alzheimer's disease (AD). This view has led researchers for more than two decades and continues to be the most influential model of neurodegeneration. Nevertheless, close scrutiny of the current evidence does not support a central pathogenic role for Aβ in late-onset AD. Furthermore, the amyloid cascade hypothesis lacks a theoretical foundation from which the physiological generation of Aβ can be understood, and therapeutic approaches based on its premises have failed. We present an alternative model of neurodegeneration, in which sustained cholesterol-associated neuronal distress is the most likely pathogenic trigger in late-onset AD, directly causing oxidative stress, inflammation and tau hyperphosphorylation. In this scenario, Aβ generation is part of an APP-driven adaptive response to the initial cholesterol distress, and its accumulation is neither central to, nor a requirement for, the initiation of the disease. Our model provides a theoretical framework that places APP as a regulator of cholesterol homeostasis, accounts for the generation of Aβ in both healthy and demented brains, and provides suitable targets for therapeutic intervention. Copyright © 2012 Elsevier B.V. All rights reserved.

Association of Higher Cortical Amyloid Burden With Loneliness in Cognitively Normal Older Adults.

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Donovan, Nancy J; Okereke, Olivia I; Vannini, Patrizia; Amariglio, Rebecca E; Rentz, Dorene M; Marshall, Gad A; Johnson, Keith A; Sperling, Reisa A

2016-12-01

Emotional and behavioral symptoms in cognitively normal older people may be direct manifestations of Alzheimer disease (AD) pathophysiology at the preclinical stage, prior to the onset of mild cognitive impairment. Loneliness is a perceived state of social and emotional isolation that has been associated with cognitive and functional decline and an increased risk of incident AD dementia. We hypothesized that loneliness might occur in association with elevated cortical amyloid burden, an in vivo research biomarker of AD. To determine whether cortical amyloid burden is associated with greater loneliness in cognitively normal older adults. Cross-sectional analyses using data from the Harvard Aging Brain Study of 79 cognitively normal, community-dwelling participants. A continuous, aggregate measure of cortical amyloid burden, determined by Pittsburgh Compound B-positron emission tomography (PiB-PET), was examined in association with loneliness in linear regression models adjusting for age, sex, apolipoprotein E ε4 (APOEε4), socioeconomic status, depression, anxiety, and social network (without and with the interaction of amyloid and APOEε4). We also quantified the association of high amyloid burden (amyloid-positive group) to loneliness (lonely group) using logistic regression, controlling for the same covariates, with the amyloid-positive group and the lonely group, each composing 32% of the sample (n = 25). Loneliness, as determined by the 3-item UCLA Loneliness Scale (possible range, 3-12, with higher score indicating greater loneliness). The 79 participants included 43 women and 36 men with a mean (SD) age of 76.4 (6.2) years. Mean (SD) cortical amyloid burden via PiB-PET was 1.230 (0.209), and the mean (SD) UCLA-3 loneliness score was 5.3 (1.8). Twenty-two (28%) had positive APOEε4 carrier status, and 25 (32%) were in the amyloid-positive group with cortical PiB distribution volume ratio greater than 1.2. Controlling for age, sex, APOEε4, socioeconomic

Peptide p5 binds both heparinase-sensitive glycosaminoglycans and fibrils in patient-derived AL amyloid extracts

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Martin, Emily B.; Williams, Angela [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Heidel, Eric [Department of Surgery, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Macy, Sallie [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Kennel, Stephen J. [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Wall, Jonathan S., E-mail: jwall@utmck.edu [Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States); Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37922 (United States)

2013-06-21

Highlights: •Polybasic peptide p5 binds human light chain amyloid extracts. •The binding of p5 with amyloid involves both glycosaminoglycans and fibrils. •Heparinase treatment led to a correlation between p5 binding and fibril content. •p5 binding to AL amyloid requires electrostatic interactions. -- Abstract: In previously published work, we have described heparin-binding synthetic peptides that preferentially recognize amyloid deposits in a mouse model of reactive systemic (AA) amyloidosis and can be imaged by using positron and single photon emission tomographic imaging. We wanted to extend these findings to the most common form of visceral amyloidosis, namely light chain (AL); however, there are no robust experimental animal models of AL amyloidosis. To further define the binding of the lead peptide, p5, to AL amyloid, we characterized the reactivity in vitro of p5 with in situ and patient-derived AL amyloid extracts which contain both hypersulfated heparan sulfate proteoglycans as well as amyloid fibrils. Histochemical staining demonstrated that the peptide specifically localized with tissue-associated AL amyloid deposits. Although we anticipated that p5 would undergo electrostatic interactions with the amyloid-associated glycosaminoglycans expressing heparin-like side chains, no significant correlation between peptide binding and glycosaminoglycan content within amyloid extracts was observed. In contrast, following heparinase I treatment, although overall binding was reduced, a positive correlation between peptide binding and amyloid fibril content became evident. This interaction was further confirmed using synthetic light chain fibrils that contain no carbohydrates. These data suggest that p5 can bind to both the sulfated glycosaminoglycans and protein fibril components of AL amyloid. Understanding these complex electrostatic interactions will aid in the optimization of synthetic peptides for use as amyloid imaging agents and potentially as

Imaging and quantification of amyloid fibrillation in the cell nucleus.

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Arnhold, Florian; Scharf, Andrea; von Mikecz, Anna

2015-01-01

Xenobiotics, as well as intrinsic processes such as cellular aging, contribute to an environment that constantly challenges nuclear organization and function. While it becomes increasingly clear that proteasome-dependent proteolysis is a major player, the topology and molecular mechanisms of nuclear protein homeostasis remain largely unknown. We have shown previously that (1) proteasome-dependent protein degradation is organized in focal microenvironments throughout the nucleoplasm and (2) heavy metals as well as nanoparticles induce nuclear protein fibrillation with amyloid characteristics. Here, we describe methods to characterize the landscape of intranuclear amyloid on the global and local level in different systems such as cultures of mammalian cells and the soil nematode Caenorhabditis elegans. Application of discrete mathematics to imaging data is introduced as a tool to develop pattern recognition of intracellular protein fibrillation. Since stepwise fibrillation of otherwise soluble proteins to insoluble amyloid-like protein aggregates is a hallmark of neurodegenerative protein-misfolding disorders including Alzheimer's disease, CAG repeat diseases, and the prion encephalopathies, investigation of intracellular amyloid may likewise aid to a better understanding of the pathomechanisms involved. We consider aggregate profiling as an important experimental approach to determine if nuclear amyloid has toxic or protective roles in various disease processes.

Cerebral Amyloid Angiopathy

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Mahmut Edip Gürol

2009-03-01

Full Text Available Cerebral amyloid angiopathy (CAA is characterized by the accumulation of amyloid beta-peptides (Ab in the walls of leptomeningeal arteries, arterioles, and veins. Despite the fact that these pathological changes were first described in 1909, major advancement in our understanding of the clinicoradiological manifestations, neurobiology, and course of CAA has occurred only during the last 30 years. No significant associations have been shown between CAA and other systemic/visceral amyloidoses or vascular risk factors, including hypertension. CAA is well known as the most common cause of spontaneous and anticoagulant-related lobar parenchymal ICH in the elderly. It also causes lobar cerebral microbleeds (CMBs, small dot-like dark susceptibility artifacts visible with gradient recalled echo (GRE-magnetic resonance imaging (MRI. CMBs are important markers of disease severity and predictors of CAA progression. Amyloid angiopathy is also a common cause of ischemic microvascular white matter disease (WMD and deep cerebral infarctions. Such WMD is defined as subcortical and periventricular white matter changes without obvious infarction, as well as a dark appearance on computerized tomography (CT and a bright appearance on fluid attenuated inversion recovery (FLAIR-MRI. CAA-related vascular dysfunction, with its hemorrhagic and ischemic complications, is a recognized contributor to vascular cognitive impairment in the elderly, an independent effect that is synergistically increased by Alzheimer pathologies, such as plaques and tangles. A set of clinicoradiological criteria was established for the accurate diagnosis of CAA. According to the Boston Criteria, patients aged 55 years and older with multiple hemorrhages (on CT or GRE-MRI restricted to the lobar, cortical, or corticosubcortical regions (cerebellar hemorrhage allowed are diagnosed as probable CAA when no other etiology is found; a single hemorrhage in the same region is classified as possible

Comparison of the amyloid pore forming properties of rat and human Alzheimer’s beta-amyloid peptide 1-42: Calcium imaging data

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Coralie Di Scala

2016-03-01

Full Text Available The data here consists of calcium imaging of human neuroblastoma SH-SY5Y cells treated with the calcium-sensitive dye Fluo-4AM and then incubated with nanomolar concentrations of either human or rat Alzheimer’s β-amyloid peptide Aβ1-42. These data are both of a qualitative (fluorescence micrographs and semi-quantitative nature (estimation of intracellular calcium concentrations of cells probed by Aβ1-42 peptides vs. control untreated cells. Since rat Aβ1-42 differs from its human counterpart at only three amino acid positions, this comparative study is a good assessment of the specificity of the amyloid pore forming assay. The interpretation of this dataset is presented in the accompanying study “Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides” [1].

Significant association between renal function and amyloid-positive area in renal biopsy specimens in AL amyloidosis

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Kuroda Takeshi

2012-09-01

Full Text Available Abstract Background The kidney is a major target organ for systemic amyloidosis that often affects the kidney including proteinura, and elevated serum creatinine (Cr. The correlation between amount of amyloid deposits and clinical parameters is not known. The aim of this study was to clarify correlation the amyloid area in all renal biopsy specimen and clinical parameters. Methods Fifty-eight patients with an established diagnosis of AL amyloidosis participated in the study. All patients showed amyloid deposits in renal biopsies. We retrospectively investigated the correlation between clinical data and amyloid occupied area in whole renal biopsy specimens. Results The area occupied by amyloid was less than 10% in 57 of the 58 patients, and was under 2% in 40. For statistical analyses, %amyloid-positive areas were transformed to common logarithmic values (Log10%amyloid. Cr showed significant correlation with Log10%amyloid and estimated glomerular filtration rate (eGFR showed the significant negative correlation. Patient age, cleatinine clearance (Ccr, blood urea nitorogen, and urinary protein was not significantly correlated with Log10%amyloid. The correlation with other clinical factors such as sex, and serum concentrations of total protein, albumin, immunoglobulins, compliments was evaluated. None of these factors significantly correlated with Log10%amyloid. According to sex- and age- adjusted multiple linear regression analysis, Log10%amyloid had significant positive association with Cr and significant negative association with eGFR. Conclusion There is significant association between amyloid-positive area in renal tissue and renal function, especially Cr and eGFR. The level of Cr and eGFR may be a marker of amount of amyloid in renal tissue.

Structure activity relationship study of curcumin analogues toward the amyloid-beta aggregation inhibitor.

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Endo, Hitoshi; Nikaido, Yuri; Nakadate, Mamiko; Ise, Satomi; Konno, Hiroyuki

2014-12-15

Inhibition of the amyloid β aggregation process could possibly prevent the onset of Alzheimer's disease. In this article, we report a structure-activity relationship study of curcumin analogues for anti amyloid β aggregation activity. Compound 7, the ideal amyloid β aggregation inhibitor in vitro among synthesized curcumin analogues, has not only potent anti amyloid β aggregation effects, but also water solubility more than 160 times that of curcumin. In addition, new approaches to improve water solubility of curcumin-type compounds are proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Amyloid fibril formation from sequences of a natural beta-structured fibrous protein, the adenovirus fiber.

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Papanikolopoulou, Katerina; Schoehn, Guy; Forge, Vincent; Forsyth, V Trevor; Riekel, Christian; Hernandez, Jean-François; Ruigrok, Rob W H; Mitraki, Anna

2005-01-28

Amyloid fibrils are fibrous beta-structures that derive from abnormal folding and assembly of peptides and proteins. Despite a wealth of structural studies on amyloids, the nature of the amyloid structure remains elusive; possible connections to natural, beta-structured fibrous motifs have been suggested. In this work we focus on understanding amyloid structure and formation from sequences of a natural, beta-structured fibrous protein. We show that short peptides (25 to 6 amino acids) corresponding to repetitive sequences from the adenovirus fiber shaft have an intrinsic capacity to form amyloid fibrils as judged by electron microscopy, Congo Red binding, infrared spectroscopy, and x-ray fiber diffraction. In the presence of the globular C-terminal domain of the protein that acts as a trimerization motif, the shaft sequences adopt a triple-stranded, beta-fibrous motif. We discuss the possible structure and arrangement of these sequences within the amyloid fibril, as compared with the one adopted within the native structure. A 6-amino acid peptide, corresponding to the last beta-strand of the shaft, was found to be sufficient to form amyloid fibrils. Structural analysis of these amyloid fibrils suggests that perpendicular stacking of beta-strand repeat units is an underlying common feature of amyloid formation.

Cardiac resynchronization therapy in a patient with amyloid cardiomyopathy.

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Zizek, David; Cvijić, Marta; Zupan, Igor

2013-06-01

Cardiac involvement in systemic light chain amyloidosis carries poor prognosis. Amyloid deposition in the myocardium can alter regional left ventricular contraction and cause dyssynchrony. Cardiac resynchronization therapy (CRT) is an effective treatment strategy for patients with advanced heart failure and echocardiographic dyssynchrony. We report a clinical and echocardiographic response of a patient with amyloid cardiomyopathy, treated with a combination of chemotherapy and CRT.

Extracellular DNA facilitates the formation of functional amyloids in Staphylococcus aureus biofilms.

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Schwartz, Kelly; Ganesan, Mahesh; Payne, David E; Solomon, Michael J; Boles, Blaise R

2016-01-01

Persistent staphylococcal infections often involve surface-associated communities called biofilms. Staphylococcus aureus biofilm development is mediated by the co-ordinated production of the biofilm matrix, which can be composed of polysaccharides, extracellular DNA (eDNA) and proteins including amyloid fibers. The nature of the interactions between matrix components, and how these interactions contribute to the formation of matrix, remain unclear. Here we show that the presence of eDNA in S. aureus biofilms promotes the formation of amyloid fibers. Conditions or mutants that do not generate eDNA result in lack of amyloids during biofilm growth despite the amyloidogeneic subunits, phenol soluble modulin peptides, being produced. In vitro studies revealed that the presence of DNA promotes amyloid formation by PSM peptides. Thus, this work exposes a previously unacknowledged interaction between biofilm matrix components that furthers our understanding of functional amyloid formation and S. aureus biofilm biology. © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

MR Microimaging of amyloid plaques in Alzheimer's disease transgenic mice

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Wengenack, Thomas M.; Poduslo, Joseph F. [Mayo Clinic, Molecular Neurobiology Laboratory, Departments of Neurology, Neuroscience, and Biochemistry/Molecular Biology, Rochester, MN (United States); Jack, Clifford R. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Garwood, Michael [University of Minnesota Medical School, Center for Magnetic Resonance Research, Minneapolis, MN (United States); University of Minnesota Medical School, Department of Radiology, Minneapolis, MN (United States)

2008-03-15

Alzheimer's disease (AD) is the most prevalent neurological condition affecting industrialized nations and will rapidly become a healthcare crisis as the population ages. Currently, the post-mortem histological observation of amyloid plaques and neurofibrillary tangles is the only definitive diagnosis available for AD. A pre-mortem biological or physiological marker specific for AD used in conjunction with current neurological and memory testing could add a great deal of confidence to the diagnosis of AD and potentially allow therapeutic intervention much earlier in the disease process. Our group has developed MRI techniques to detect individual amyloid plaques in AD transgenic mouse brain in vivo. We are also developing contrast-enhancing agents to increase the specificity of detection of amyloid plaques. Such in vivo imaging of amyloid plaques will also allow the evaluation of anti-amyloid therapies being developed by the pharmaceutical industry in pre-clinical trials of AD transgenic mice. This short review briefly discusses our progress in these areas. (orig.)

Computational Modelling of the Human Islet Amyloid Polypeptide

DEFF Research Database (Denmark)

Skeby, Katrine Kirkeby

2014-01-01

to interpret results correctly. Computational studies and molecular dynamics (MD) simulations in particular have become important tools in the effort to understand biological mechanisms. The strength of these methods is the high resolution in time and space, and the ability to specifically design the system....... Using MD simulations we have investigated the binding of 13 different imaging agents to a fibril segment. Using clustering analysis and binding energy calculations we have identified a common binding mode for the 13 agents in the surface grooves of the fibril, which are present on all amyloid fibrils....... This information combined with specific knowledge about the AD amyloid fibril is the building block for the design of highly specific amyloid imaging agents. We have also used MD simulations to study the interaction between hIAPP and a phospholipid membrane. At neutral pH, we find that the attraction is mainly...

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species.

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Needham, Lisa-Maria; Weber, Judith; Fyfe, James W B; Kabia, Omaru M; Do, Dung T; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M; Ghandi, Sonia; Bohndiek, Sarah E; Snaddon, Thomas N; Lee, Steven F

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H 2 O 2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H 2 O 2 . We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H 2 O 2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species

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Needham, Lisa-Maria; Weber, Judith; Fyfe, James W. B.; Kabia, Omaru M.; Do, Dung T.; Klimont, Ewa; Zhang, Yu; Rodrigues, Margarida; Dobson, Christopher M.; Ghandi, Sonia; Bohndiek, Sarah E.; Snaddon, Thomas N.; Lee, Steven F.

2018-02-01

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

Transbronchial biopsies safely diagnose amyloid lung disease

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Govender, Praveen; Keyes, Colleen M.; Hankinson, Elizabeth A.; O’Hara, Carl J.; Sanchorawala, Vaishali; Berk, John L.

2018-01-01

Background Autopsy identifies lung involvement in 58–92% of patients with the most prevalent forms of systemic amyloidoses. In the absence of lung biopsies, amyloid lung disease often goes unrecognized. Report of a death following transbronchial biopsies in a patient with systemic amyloidosis cautioned against the procedure in this patient cohort. We reviewed our experience with transbronchial biopsies in patients with amyloidosis to determine the safety and utility of bronchoscopic lung biopsies. Methods We identified patients referred to the Amyloidosis Center at Boston Medical Center with lung amyloidosis diagnosed by transbronchial lung biopsies (TBBX). Amyloid typing was determined by immunohistochemistry or mass spectrometry. Standard end organ assessments, including pulmonary function test (PFT) and chest tomography (CT) imaging, and extra-thoracic biopsies established the extent of disease. Results Twenty-five (21.7%) of 115 patients with lung amyloidosis were diagnosed by TBBX. PFT classified 33.3% with restrictive physiology, 28.6% with obstructive disease, and 9.5% mixed physiology; 9.5% exhibited isolated diffusion defects while 19% had normal pulmonary testing. Two view chest or CT imaging identified focal opacities in 52% of cases and diffuse interstitial disease in 48%. Amyloid type and disease extent included 68% systemic AL disease, 16% localized (lung limited) AL disease, 12% ATTR disease, and 4% AA amyloidosis. Fluoroscopy was not used during biopsy. No procedure complications were reported. Conclusions Our case series of 25 patients supports the use of bronchoscopic transbronchial biopsies for diagnosis of parenchymal lung amyloidosis. Normal PFTs do not rule out the histologic presence of amyloid lung disease. PMID:28393574

Morphology and mechanical properties of multi-stranded amyloid fibrils probed by atomistic and coarse-grained simulations

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Yoon, Gwonchan; Lee, Myeongsang; Kim, Kyungwoo; In Kim, Jae; Joon Chang, Hyun; Baek, Inchul; Na, Sungsoo; Eom, Kilho

2015-01-01

Amyloid fibrils are responsible for pathogenesis of various diseases and exhibit the structural feature of an ordered, hierarchical structure such as multi-stranded helical structure. As the multi-strandedness of amyloid fibrils has recently been found to be highly correlated with their toxicity and infectivity, it is necessary to study how the hierarchical (i.e. multi-stranded) structure of amyloid fibril is formed. Moreover, although it has recently been reported that the nanomechanics of amyloid proteins plays a key role on the amyloid-induced pathogenesis, a critical role that the multi-stranded helical structure of the fibrils plays in their nanomechanical properties has not fully characterized. In this work, we characterize the morphology and mechanical properties of multi-stranded amyloid fibrils by using equilibrium molecular dynamics simulation and elastic network model. It is shown that the helical pitch of multi-stranded amyloid fibril is linearly proportional to the number of filaments comprising the amyloid fibril, and that multi-strandedness gives rise to improving the bending rigidity of the fibril. Moreover, we have also studied the morphology and mechanical properties of a single protofilament (filament) in order to understand the effect of cross-β structure and mutation on the structures and mechanical properties of amyloid fibrils. Our study sheds light on the underlying design principles showing how the multi-stranded amyloid fibril is formed and how the structure of amyloid fibrils governs their nanomechanical properties. (paper)

Amyloid oligomers and protofibrils, but not filaments, self-replicate from native lysozyme.

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Mulaj, Mentor; Foley, Joseph; Muschol, Martin

2014-06-25

Self-assembly of amyloid fibrils is the molecular mechanism best known for its connection with debilitating human disorders such as Alzheimer's disease but is also associated with various functional cellular responses. There is increasing evidence that amyloid formation proceeds along two distinct assembly pathways involving either globular oligomers and protofibrils or rigid monomeric filaments. Oligomers, in particular, have been implicated as the dominant molecular species responsible for pathogenesis. Yet the molecular mechanisms regulating their self-assembly have remained elusive. Here we show that oligomers/protofibrils and monomeric filaments, formed along distinct assembly pathways, display critical differences in their ability to template amyloid growth at physiological vs denaturing temperatures. At physiological temperatures, amyloid filaments remained stable but could not seed growth of native monomers. In contrast, oligomers and protofibrils not only remained intact but were capable of self-replication using native monomers as the substrate. Kinetic data further suggested that this prion-like growth mode of oligomers/protofibrils involved two distinct activities operating orthogonal from each other: autocatalytic self-replication of oligomers from native monomers and nucleated polymerization of oligomers into protofibrils. The environmental changes to stability and templating competence of these different amyloid species in different environments are likely to be important for understanding the molecular mechanisms underlying both pathogenic and functional amyloid self-assembly.

Calcium-dependent and -independent binding of the pentraxin serum amyloid P component to glycosaminoglycans and amyloid proteins

DEFF Research Database (Denmark)

Danielsen, B; Sørensen, I J; Nybo, Mads

1997-01-01

precursor protein beta2M was observed. This binding was also enhanced at slightly acid pH, most pronounced at pH 5.0. The results of this study indicate that SAP can exhibit both Ca2(+)-dependent and -independent binding to ligands involved in amyloid fibril formation and that the binding is enhanced under...... and beta2M) by ELISA. An increase in the dose-dependent binding of SAP to heparan sulfate, AA-protein and beta2M was observed as the pH decreased from 8.0 to 5.0. Furthermore, a lower, but significant Ca2(+)-independent binding of SAP to heparan sulfate, dermatan sulfate, AA protein and the amyloid...

Chemical Assistance in Refolding of Bacterial Inclusion Bodies

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Mona Alibolandi

2011-01-01

Full Text Available Escherichia coli is one of the most widely used hosts for the production of recombinant proteins but insoluble expression of heterologous proteins is a major bottleneck in production of recombinant proteins in E. coli. In vitro refolding of inclusion body into proteins with native conformations is a solution for this problem but there is a need for optimization of condition for each protein specifically. Several approaches have been described for in vitro refolding; most of them involve the use of additives for assisting correct folding. Cosolutes play a major role in refolding process and can be classified according to their function as aggregation suppressors and folding enhancers. This paper presents a review of additives that are used in refolding process of insoluble recombinant proteins in small scale and industrial processes.

Amyloid-β production via cleavage of amyloid-β protein precursor is modulated by cell density.

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Zhang, Can; Browne, Andrew; Divito, Jason R; Stevenson, Jesse A; Romano, Donna; Dong, Yuanlin; Xie, Zhongcong; Tanzi, Rudolph E

2010-01-01

Mounting evidence suggests that Alzheimer's disease (AD) is caused by the accumulation of the small peptide, amyloid-β (Aβ), a proteolytic cleavage product of amyloid-β protein precursor (AβPP). Aβ is generated through a serial cleavage of AβPP by β- and γ-secretase. Aβ40 and Aβ42 are the two main components of amyloid plaques in AD brains, with Aβ42 being more prone to aggregation. AβPP can also be processed by α-secretase, which cleaves AβPP within the Aβ sequence, thereby preventing the generation of Aβ. Little is currently known regarding the effects of cell density on AβPP processing and Aβ generation. Here we assessed the effects of cell density on AβPP processing in neuronal and non-neuronal cell lines, as well as mouse primary cortical neurons. We found that decreased cell density significantly increases levels of Aβ40, Aβ42, total Aβ, and the ratio of Aβ42: Aβ40. These results also indicate that cell density is a significant modulator of AβPP processing. Overall, these findings carry profound implications for both previous and forthcoming studies aiming to assess the effects of various conditions and genetic/chemical factors, e.g., novel drugs on AβPP processing and Aβ generation in cell-based systems. Moreover, it is interesting to speculate whether cell density changes in vivo may also affect AβPP processing and Aβ levels in the AD brain.

The Tubular Sheaths Encasing Methanosaeta and Methanospirillum Filaments are Functional Amyloids

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Dueholm, Morten Simonsen; Larsen, Poul; Nielsen, Per Halkjær

Archaea are well-recognized for their ability to thrive in extreme environments, although they can be found in virtually all habitats. Their adaptive success is linked to their unique cell envelopes, which often display extremely resistant to chemical and thermal denaturation and resist proteolysis...... techniques to show that the extracellular cell wall sheaths of the methanogenic archaea Methanosaeta and Methanospirillum are functional amyloid structures. Depolymerization of sheaths with formic acid and reducing agents and subsequent MS/MS analysis revealed that the sheaths are composed of a single major...... sheath protein (MspA). The amyloidogenic nature of MspA was confirmed by in vitro amyloid formation of recombinant MspA under a wide range of environmental conditions. This is the first report of a functional amyloid from the archaeal domain of life. The amyloid properties explain the extreme resistance...

[Clinical Laboratory Test Using Proteomics: The Usefulness of Proteomic Techniques for Amyloid Typing].

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Tasaki, Masayoshi; Obayashi, Konen; Ando, Yukio

2015-08-01

Amyloidosis is a heterogeneous group of disorders characterized by the deposition of amyloid fibrils. To diagnose amyloidosis, it is important to detect amyloid deposits and identify the amyloid precursor protein in specimens, such as tissues and serum. Mass spectrometry is a powerful tool to measure the molecular weight and identify the protein. Recently, mass spectrometries such as liquid chromatography/tandem mass spectrometry and surface-enhanced laser desorption/ionization time of flight mass spectrometry, have made a contribution to amyloid typing. In the paper, we describe the usefulness of mass spectrometric analyses for the typing of amyloidosis.

Does aluminium bind to histidine? An NMR investigation of amyloid β12 and amyloid β16 fragments.

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Narayan, Priya; Krishnarjuna, Bankala; Vishwanathan, Vinaya; Jagadeesh Kumar, Dasappa; Babu, Sudhir; Ramanathan, Krishna Venkatachala; Easwaran, Kalpathy Ramaier Katchap; Nagendra, Holenarasipur Gundurao; Raghothama, Srinivasarao

2013-07-01

Aluminium and zinc are known to be the major triggering agents for aggregation of amyloid peptides leading to plaque formation in Alzheimer's disease. While zinc binding to histidine in Aβ (amyloid β) fragments has been implicated as responsible for aggregation, not much information is available on the interaction of aluminium with histidine. In the NMR study of the N-terminal Aβ fragments, DAEFRHDSGYEV (Aβ12) and DAEFRHDSGYEVHHQK (Aβ16) presented here, the interactions of the fragments with aluminium have been investigated. Significant chemical shifts were observed for few residues near the C-terminus when aluminium chloride was titrated with Aβ12 and Aβ16 peptides. Surprisingly, it is nonhistidine residues which seem to be involved in aluminium binding. Based on NMR constrained structure obtained by molecular modelling, aluminium-binding pockets in Aβ12 were around charged residues such as Asp, Glu. The results are discussed in terms of native structure propagation, and the relevance of histidine residues in the sequences for metal-binding interactions. We expect that the study of such short amyloid peptide fragments will not only provide clues for plaque formation in aggregated conditions but also facilitate design of potential drugs for these targets. © 2013 John Wiley & Sons A/S.

α-Iso-cubebene exerts neuroprotective effects in amyloid beta stimulated microglia activation.

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Park, Sun Young; Park, Se Jin; Park, Nan Jeong; Joo, Woo Hong; Lee, Sang-Joon; Choi, Young-Whan

2013-10-25

Schisandra chinensis is commonly used for food and as a traditional remedy for the treatment of neuronal disorders. However, it is unclear which component of S. chinensis is responsible for its neuropharmacological effects. To answer this question, we isolated α-iso-cubebene, a dibenzocyclooctadiene lignin, from S. chinensis and determined if it has any anti-neuroinflammatory and neuroprotective properties against amyloid β-induced neuroinflammation in microglia. Microglia that are stimulated by amyloid β increased their production of pro-inflammatory cytokines and chemokines, prostaglandin E2 (PGE2), nitric oxide (NO) and reactive oxygen species (ROS) and the enzymatic activity of matrix metalloproteinase 9 (MMP-9). We found this was all inhibited by α-iso-cubebene. Consistent with these results, α-iso-cubebene inhibited the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2) and MMP-9 in amyloid β-stimulated microglia. Subsequent mechanistic studies revealed that α-iso-cubebene inhibited the phosphorylation and degradation of IκB-α, the phosphorylation and transactivity of NF-κB, and the phosphorylation of MAPK in amyloid β-stimulated microglia. These results suggest that α-iso-cubebene impairs the amyloid β-induced neuroinflammatory response of microglia by inhibiting the NF-κB and MAPK signaling pathways. Importantly, α-iso-cubebene can provide critical neuroprotection for primary cortical neurons against amyloid β-stimulated microglia-mediated neurotoxicity. To the best of our knowledge, this is the first report showing that α-iso-cubebene can provide neuroprotection against, and influence neuroinflammation triggered by, amyloid β activation of microglia. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

In situ hybridization of nucleus basalis neurons shows increased β-amyloid mRNA in Alzheimer disease

International Nuclear Information System (INIS)

Cohen, M.L.; Golde, T.E.; Usiak, M.F.; Younkin, L.H.; Younkin, S.G.

1988-01-01

To determine which cells within the brain produce β-amyloid mRNA and to assess expression of the β-amyloid gene in Alzheimer disease, the authors analyzed brain tissue from Alzheimer and control patients by in situ hybridization. The results demonstrate that β-amyloid mRNA is produced by neurons in the nucleus basalis of Meynert and cerebral cortex and that nuclues basalis perikarya from Alzheimer patients consistently hybridize more β-amyloid probe than those from controls. These observations support the hypothesis that increased expression of the β-amyloid gene plays an important role in the deposition of amyloid in the brains of patients with Alzheimer disease

Proteomic analysis of highly prevalent amyloid A amyloidosis endemic to endangered island foxes.

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Patricia M Gaffney

Full Text Available Amyloid A (AA amyloidosis is a debilitating, often fatal, systemic amyloid disease associated with chronic inflammation and persistently elevated serum amyloid A (SAA. Elevated SAA is necessary but not sufficient to cause disease and the risk factors for AA amyloidosis remain poorly understood. Here we identify an extraordinarily high prevalence of AA amyloidosis (34% in a genetically isolated population of island foxes (Urocyon littoralis with concurrent chronic inflammatory diseases. Amyloid deposits were most common in kidney (76%, spleen (58%, oral cavity (45%, and vasculature (44% and were composed of unbranching, 10 nm in diameter fibrils. Peptide sequencing by mass spectrometry revealed that SAA peptides were dominant in amyloid-laden kidney, together with high levels of apolipoprotein E, apolipoprotein A-IV, fibrinogen-α chain, and complement C3 and C4 (false discovery rate ≤ 0.05. Reassembled peptide sequences showed island fox SAA as an 111 amino acid protein, most similar to dog and artic fox, with 5 unique amino acid variants among carnivores. SAA peptides extended to the last two C-terminal amino acids in 5 of 9 samples, indicating that near full length SAA was often present in amyloid aggregates. These studies define a remarkably prevalent AA amyloidosis in island foxes with widespread systemic amyloid deposition, a unique SAA sequence, and the co-occurrence of AA with apolipoproteins.

Terapeutika amyloidóz

Czech Academy of Sciences Publication Activity Database

Holubová, Monika; Hrubý, Martin

2016-01-01

Roč. 110, č. 12 (2016), s. 851-859 ISSN 0009-2770 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : amyloidosis * amyloid * Alzheimer's disease Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.387, year: 2016 http://www.chemicke-listy.cz/common/article-vol_110-issue_12-page_851.html

Unwinding fibril formation of medin, the peptide of the most common form of human amyloid

International Nuclear Information System (INIS)

Larsson, Annika; Soederberg, Linda; Westermark, Gunilla T.; Sletten, Knut; Engstroem, Ulla; Tjernberg, Lars O.; Naeslund, Jan; Westermark, Per

2007-01-01

Medin amyloid affects the medial layer of the thoracic aorta of most people above 50 years of age. The consequences of this amyloid are not completely known but the deposits may contribute to diseases such as thoracic aortic aneurysm and dissection or to the general diminished elasticity of blood vessels seen in elderly people. We show that the 50-amino acid residue peptide medin forms amyloid-like fibrils in vitro. With the use of Congo red staining, Thioflavin T fluorescence, electron microscopy, and a solid-phase binding assay on different synthetic peptides, we identified the last 18-19 amino acid residues to constitute the amyloid-promoting region of medin. We also demonstrate that the two C-terminal phenylalanines, previously suggested to be of importance for amyloid formation, are not required for medin amyloid formation

The effects of white matter hyperintensities and amyloid deposition on Alzheimer dementia

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Brian A. Gordon

2015-01-01

Conclusions: The amount of amyloid deposition and white matter damage independently predicts cognitive impairment. This suggests a diagnostic utility of qualitative white matter scales in addition to measuring amyloid levels.

Mechanical properties of amyloid-like fibrils defined by secondary structures

Science.gov (United States)

Bortolini, C.; Jones, N. C.; Hoffmann, S. V.; Wang, C.; Besenbacher, F.; Dong, M.

2015-04-01

Amyloid and amyloid-like fibrils represent a generic class of highly ordered nanostructures that are implicated in some of the most fatal neurodegenerative diseases. On the other hand, amyloids, by possessing outstanding mechanical robustness, have also been successfully employed as functional biomaterials. For these reasons, physical and chemical factors driving fibril self-assembly and morphology are extensively studied - among these parameters, the secondary structures and the pH have been revealed to be crucial, since a variation in pH changes the fibril morphology and net chirality during protein aggregation. It is important to quantify the mechanical properties of these fibrils in order to help the design of effective strategies for treating diseases related to the presence of amyloid fibrils. In this work, we show that by changing pH the mechanical properties of amyloid-like fibrils vary as well. In particular, we reveal that these mechanical properties are strongly related to the content of secondary structures. We analysed and estimated the Young's modulus (E) by comparing the persistence length (Lp) - measured from the observation of TEM images by using statistical mechanics arguments - with the mechanical information provided by peak force quantitative nanomechanical property mapping (PF-QNM). The secondary structure content and the chirality are investigated by means of synchrotron radiation circular dichroism (SR-CD). Results arising from this study could be fruitfully used as a protocol to investigate other medical or engineering relevant peptide fibrils.Amyloid and amyloid-like fibrils represent a generic class of highly ordered nanostructures that are implicated in some of the most fatal neurodegenerative diseases. On the other hand, amyloids, by possessing outstanding mechanical robustness, have also been successfully employed as functional biomaterials. For these reasons, physical and chemical factors driving fibril self-assembly and morphology

Lowering beta-amyloid levels rescues learning and memory in a Down syndrome mouse model.

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William J Netzer

Full Text Available beta-amyloid levels are elevated in Down syndrome (DS patients throughout life and are believed to cause Alzheimer's disease (AD in adult members of this population. However, it is not known if beta-amyloid contributes to intellectual disability in younger individuals. We used a gamma-secretase inhibitor to lower beta-amyloid levels in young mice that model DS. This treatment corrected learning deficits characteristic of these mice, suggesting that beta-amyloid-lowering therapies might improve cognitive function in young DS patients.

Minocycline does not affect amyloid beta phagocytosis by human microglial cells

NARCIS (Netherlands)

Familian, Atoosa; Eikelenboom, Piet; Veerhuis, Robert

2007-01-01

Activated microglia accumulate in amyloid beta (Abeta) plaques containing amyloid associated factors SAP and C1q in Alzheimer's disease (AD) brain. Microglia are involved in AD pathogenesis by promoting Abeta plaque formation and production of pro-inflammatory cytokines. On the other hand,

Neuroprotective and nootropic drug noopept rescues α-synuclein amyloid cytotoxicity.

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Jia, Xueen; Gharibyan, Anna L; Öhman, Anders; Liu, Yonggang; Olofsson, Anders; Morozova-Roche, Ludmilla A

2011-12-16

Parkinson's disease is a common neurodegenerative disorder characterized by α-synuclein (α-Syn)-containing Lewy body formation and selective loss of dopaminergic neurons in the substantia nigra. We have demonstrated the modulating effect of noopept, a novel proline-containing dipeptide drug with nootropic and neuroprotective properties, on α-Syn oligomerization and fibrillation by using thioflavin T fluorescence, far-UV CD, and atomic force microscopy techniques. Noopept does not bind to a sterically specific site in the α-Syn molecule as revealed by heteronuclear two-dimensional NMR analysis, but due to hydrophobic interactions with toxic amyloid oligomers, it prompts their rapid sequestration into larger fibrillar amyloid aggregates. Consequently, this process rescues the cytotoxic effect of amyloid oligomers on neuroblastoma SH-SY5Y cells as demonstrated by using cell viability assays and fluorescent staining of apoptotic and necrotic cells and by assessing the level of intracellular oxidative stress. The mitigating effect of noopept against amyloid oligomeric cytotoxicity may offer additional benefits to the already well-established therapeutic functions of this new pharmaceutical. Copyright © 2011 Elsevier Ltd. All rights reserved.

Impact of amyloid imaging on drug development in Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Mathis, Chester A. [Department of Radiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States)], E-mail: mathisca@upmc.edu; Lopresti, Brian J. [Department of Radiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States); Klunk, William E. [Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States)

2007-10-15

Imaging agents capable of assessing amyloid-beta (A{beta}) content in vivo in the brains of Alzheimer's disease (AD) subjects likely will be important as diagnostic agents to detect A{beta} plaques in the brain as well as to help test the amyloid cascade hypothesis of AD and as an aid to assess the efficacy of anti-amyloid therapeutics currently under development and in clinical trials. Positron emission tomography (PET) imaging studies of amyloid deposition in human subjects with several A{beta} imaging agents are currently underway. We reported the first PET studies of the carbon 11-labeled thioflavin-T derivative Pittsburgh Compound B in 2004, and this work has subsequently been extended to include a variety of subject groups, including AD patients, mild cognitive impairment patients and healthy controls. The ability to quantify regional A{beta} plaque load in the brains of living human subjects has provided a means to begin to apply this technology as a diagnostic agent to detect regional concentrations of A{beta} plaques and as a surrogate marker of therapeutic efficacy in anti-amyloid drug trials.

Investigation of the phase morphology of bacterial PHA inclusion bodies by contrast variation SANS

International Nuclear Information System (INIS)

Russell, R.A.; Holden, P.J.; Garvey, C.J.; Wilde, K.L.; Hammerton, K.M.; Foster, L.J.

2006-01-01

Under growth-limiting conditions, many bacteria are able to metabolise excess organic acids into polyhydroxyalkanoates (PHA) and store these polymers as intracellular inclusions until the return of favourable conditions. Various models have been proposed for the macromolecular organisation of the boundary layer surrounding the polymer, and contrast-variation small-angle neutron scattering (SANS) was used to study its organisation. Inclusions formed by Pseudomonas oleovorans under hydrogenating conditions showed lowest scattering intensity at ca. 20% D 2 O. The inclusions consist of protein and membrane lipids in the boundary layer and polyhydroxyoctanoate (lipid) in the inclusion body. At 20% D 2 O the contributions of lipids were contrast matched with the solvent, indicating that lipids contributed the bulk of the scattering intensity observed at other D 2 O/H 2 O ratios. These results are inconsistent with a model of the boundary layer which proposed outer and inner layers of crystalline protein lattice sandwiching a membrane lipid membrane layer [E.S. Stuart, R.W. Lenz, R.C. Fuller, Can J Microbiol 41(Suppl 1) (1995) 84-93], and is more consistent with a model consisting of a lipid monolayer containing embedded proteins [U. Pieper-furst, M.H. Madkour, F. Mayer, A. Steinbuchel, J. Bacteriol. 176 (1994) 4328-4337.] By altering the H/D content of the precursors, we were able to collect SANS data from preparations of both deuterated and H/D copolymer inclusions, where initial PHA produced was hydrogenated followed by deuteration. Deuterated inclusions showed minimum intensity above 90% D 2 O/H 2 O whereas the sequentially produced copolymer (assumed to be in a core/shell arrangement) displayed minimum scattering some 20% lower, which is consistent with the increased hydrogenation of the boundary layer expected from its synthesis during supply of hydrogenated followed by deuterated precursors

Neuronal Cx3cr1 Deficiency Protects against Amyloid β-Induced Neurotoxicity

Science.gov (United States)

Dworzak, Jenny; Renvoisé, Benoît; Habchi, Johnny; Yates, Emma V.; Combadière, Christophe; Knowles, Tuomas P.; Dobson, Christopher M.; Blackstone, Craig; Paulsen, Ole; Murphy, Philip M.

2015-01-01

Cx3cr1, the receptor for the chemokine Cx3cl1 (fractalkine), has been implicated in the progression and severity of Alzheimer’s disease-like pathology in mice, but the underlying mechanisms remain unclear. A complicating factor is that Cx3cr1 has been demonstrated in both neurons and microglia. Here, we have dissected the differences between neuronal and microglial Cx3cr1, specifically by comparing direct amyloid-β-induced toxicity in cultured, mature, microglia-depleted hippocampal neurons from wild-type and Cx3cr1-/- mice. Wild-type neurons expressed both Cx3cl1 and Cx3cr1 and released Cx3cl1 in response to amyloid-β. Knockout of neuronal Cx3cr1 abated amyloid-β-induced lactate dehydrogenase release. Furthermore, amyloid-β differentially induced depression of pre- and postsynaptic components of miniature excitatory postsynaptic currents, in a peptide conformation-dependent manner. Knockout of neuronal Cx3cr1 abated effects of both amyloid-β conformational states, which were differentiable by aggregation kinetics and peptide morphology. We obtained similar results after both acute and chronic treatment of cultured neurons with the Cx3cr1 antagonist F1. Thus, neuronal Cx3cr1 may impact Alzheimer’s disease-like pathology by modulating conformational state-dependent amyloid-β-induced synaptotoxicity. PMID:26038823

Neuronal Cx3cr1 Deficiency Protects against Amyloid β-Induced Neurotoxicity.

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Jenny Dworzak

Full Text Available Cx3cr1, the receptor for the chemokine Cx3cl1 (fractalkine, has been implicated in the progression and severity of Alzheimer's disease-like pathology in mice, but the underlying mechanisms remain unclear. A complicating factor is that Cx3cr1 has been demonstrated in both neurons and microglia. Here, we have dissected the differences between neuronal and microglial Cx3cr1, specifically by comparing direct amyloid-β-induced toxicity in cultured, mature, microglia-depleted hippocampal neurons from wild-type and Cx3cr1-/- mice. Wild-type neurons expressed both Cx3cl1 and Cx3cr1 and released Cx3cl1 in response to amyloid-β. Knockout of neuronal Cx3cr1 abated amyloid-β-induced lactate dehydrogenase release. Furthermore, amyloid-β differentially induced depression of pre- and postsynaptic components of miniature excitatory postsynaptic currents, in a peptide conformation-dependent manner. Knockout of neuronal Cx3cr1 abated effects of both amyloid-β conformational states, which were differentiable by aggregation kinetics and peptide morphology. We obtained similar results after both acute and chronic treatment of cultured neurons with the Cx3cr1 antagonist F1. Thus, neuronal Cx3cr1 may impact Alzheimer's disease-like pathology by modulating conformational state-dependent amyloid-β-induced synaptotoxicity.

Plasma based markers of [11C] PiB-PET brain amyloid burden.

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Steven John Kiddle

Full Text Available Changes in brain amyloid burden have been shown to relate to Alzheimer's disease pathology, and are believed to precede the development of cognitive decline. There is thus a need for inexpensive and non-invasive screening methods that are able to accurately estimate brain amyloid burden as a marker of Alzheimer's disease. One potential method would involve using demographic information and measurements on plasma samples to establish biomarkers of brain amyloid burden; in this study data from the Alzheimer's Disease Neuroimaging Initiative was used to explore this possibility. Sixteen of the analytes on the Rules Based Medicine Human Discovery Multi-Analyte Profile 1.0 panel were found to associate with [(11C]-PiB PET measurements. Some of these markers of brain amyloid burden were also found to associate with other AD related phenotypes. Thirteen of these markers of brain amyloid burden--c-peptide, fibrinogen, alpha-1-antitrypsin, pancreatic polypeptide, complement C3, vitronectin, cortisol, AXL receptor kinase, interleukin-3, interleukin-13, matrix metalloproteinase-9 total, apolipoprotein E and immunoglobulin E--were used along with co-variates in multiple linear regression, and were shown by cross-validation to explain >30% of the variance of brain amyloid burden. When a threshold was used to classify subjects as PiB positive, the regression model was found to predict actual PiB positive individuals with a sensitivity of 0.918 and a specificity of 0.545. The number of APOE [Symbol: see text] 4 alleles and plasma apolipoprotein E level were found to contribute most to this model, and the relationship between these variables and brain amyloid burden was explored.

Globular hepatic amyloid is highly sensitive and specific for LECT2 amyloidosis.

Science.gov (United States)

Chandan, Vishal S; Shah, Sejal S; Lam-Himlin, Dora M; Petris, Giovanni De; Mereuta, Oana M; Dogan, Ahmet; Torbenson, Michael S; Wu, Tsung-Teh

2015-04-01

Globular hepatic amyloid (GHA) is rare, and its clinical significance remains unclear. Recently, leukocyte chemotactic factor-associated amyloidosis (ALECT2) has been reported to involve the liver, showing a globular pattern. We reviewed 70 consecutive cases of hepatic amyloidosis to determine the prevalence and morphology of hepatic amyloid subtypes, especially ALECT2 and its association with GHA. Each case was reviewed for amyloid subtype (immunohistochemistry and/or mass spectrometry), its pattern (linear or globular), and distribution (vascular, perisinusoidal, or stromal). In addition, 24 cases of confirmed hepatic ALECT2 on mass spectrometry from our consultation files were also reviewed. LECT2 immunostaining was performed in 49 cases. Of the 70 cases, immunoglobulin light chain (AL) type was most common with 41 cases (59%), followed by transthyretin (ATTR) 15 cases (22%), 3 cases each of fibrinogen A (AFib) (4%), serum amyloid A (AA) (4%), and ALECT2 (4%), 2 cases of apolipoproteins (AApoA1) (3%), and 3 cases (4%) were unclassified. Three of our 70 cases (4%), with ALECT2, and all 24 cases (100%) of mass spectrometry-confirmed hepatic ALECT2 showed only GHA deposits in the hepatic sinusoids and portal tracts. Three (4%) other cases of AL type showed a focal globular pattern admixed with prominent linear amyloid. None of the other amyloid subtypes showed GHA. LECT2 immunostain was positive in all 27 cases (100%) of ALECT2 and negative in the other 22 non-ALECT2 cases (100%) (14 AL, 5 ATTR, 1 AA, 1 AFib, 1 AApoA1). Pure GHA is uncommon (4%) but is highly specific for ALECT2, and LECT2 immunostain is helpful in confirming this amyloid type.

Core cerebrospinal fluid biomarker profile in cerebral amyloid angiopathy: A meta-analysis.

Science.gov (United States)

Charidimou, Andreas; Friedrich, Jan O; Greenberg, Steven M; Viswanathan, Anand

2018-02-27

To perform a meta-analysis of 4 core CSF biomarkers (β-amyloid [Aβ]42, Aβ40, total tau [t-tau], and phosphorylated tau [p-tau]) to assess which of these are most altered in sporadic cerebral amyloid angiopathy (CAA). We systematically searched PubMed for eligible studies reporting data on CSF biomarkers reflecting amyloid precursor protein metabolism (Aβ42, Aβ40), neurodegeneration (t-tau), and tangle pathology (p-tau) in symptomatic sporadic CAA cohorts vs controls and patients with Alzheimer disease (AD). Biomarker performance was assessed in random-effects meta-analysis based on ratio of mean (RoM) biomarker concentrations: (1) in patients with CAA vs healthy controls and (2) in patients with CAA vs patients with AD. RoM >1 indicates higher biomarker concentration in patients with CAA vs comparison population and RoM <1 indicates higher concentration in comparison groups. Three studies met inclusion criteria. These comprised 5 CAA patient cohorts (n = 59 patients) vs healthy controls (n = 94 cases) and AD cohorts (n = 158). Three core biomarkers differentiated CAA from controls: CSF Aβ42 (RoM 0.49, 95% confidence interval [CI] 0.38-0.64, p < 0.003), Aβ40 (RoM 0.70, 95% CI 0.63-0.78, p < 0.0001), and t-tau (RoM 1.54, 95% CI 1.15-2.07, p = 0.004); p-tau was marginal (RoM 1.24, 95% CI 0.99-1.54, p = 0.062). Differentiation between CAA and AD was strong for CSF Aβ40 (RoM 0.76, 95% CI 0.69-0.83, p < 0.0001), but not Aβ42 (RoM 1.00; 95% CI 0.81-1.23, p = 0.970). For t-tau and p-tau, average CSF ratios in patients with CAA vs patients with AD were 0.63 (95% CI 0.54-0.74, p < 0.0001) and 0.60 (95% CI 0.50-0.71, p < 0.0001), respectively. Specific CSF patterns of Aβ42, Aβ40, t-tau, and p-tau might serve as molecular biomarkers of CAA, but analyses in larger CAA cohorts are needed. © 2018 American Academy of Neurology.

Cerebral amyloid angiopathy: diagnosis and potential therapies.

Science.gov (United States)

Weber, Stewart A; Patel, Ranish K; Lutsep, Helmi L

2018-06-01

Cerebral amyloid angiopathy (CAA) is characterized by the pathologic deposition of amyloid-beta within cortical and leptomeningeal arteries, arterioles, capillaries and, in rare cases, the venules of the brain. It is often associated with the development of lobar intracerebral hemorrhages (ICHs) but may cause other neurologic symptoms or be asymptomatic. Magnetic resonance imaging characteristics, such as lobar microbleeds, support a diagnosis of CAA and assist with hemorrhage risk assessments. Immunosuppressants are used to treat rarer inflammatory forms of CAA. For the more common forms of CAA, the use of antihypertensive medications can prevent ICH recurrence while the use of antithrombotics may increase hemorrhage risk. Anti-amyloid approaches to treatment have not yet been investigated in phase 3 trials. Areas covered: A literature search was conducted using MEDLINE on the topics of imaging, biomarkers, ICH prevention and treatment trials in CAA, focusing on its current diagnosis and management and opportunities for future therapeutic approaches. Expert commentary: There is likely a significant unrecognized burden of CAA in the elderly population. Continued research efforts to discover biomarkers that allow the early diagnosis of CAA will enhance the opportunity to develop treatment interventions.

Analysis of amyloid fibrils in the cheetah (Acinonyx jubatus).

Science.gov (United States)

Bergström, Joakim; Ueda, Mitsuharu; Une, Yumi; Sun, Xuguo; Misumi, Shogo; Shoji, Shozo; Ando, Yukio

2006-06-01

Recently, a high prevalence of amyloid A (AA) amyloidosis has been documented among captive cheetahs worldwide. Biochemical analysis of amyloid fibrils extracted from the liver of a Japanese captive cheetah unequivocally showed that protein AA was the main fibril constituent. Further characterization of the AA fibril components by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis revealed three main protein AA bands with approximate molecular weights of 8, 10 and 12 kDa. Mass spectrometry analysis of the 12-kDa component observed in SDS-PAGE and Western blotting confirmed the molecular weight of a 12,381-Da peak. Our finding of a 12-kDa protein AA component provides evidence that the cheetah SAA sequence is longer than the previously reported 90 amino acid residues (approximately 10 kDa), and hence SAA is part of the amyloid fibril.

Are Amyloid Fibrils RNA-Traps? A Molecular Dynamics Perspective

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Massimiliano Meli

2018-06-01

Full Text Available The self-assembly of proteins and peptides into amyloids is a key feature of an increasing number of diseases. Amyloid fibrils display a unique surface reactivity endowing the sequestration of molecules such as MicroRNAs, which can be the active moiety of the toxic action. To test this hypothesis we studied the recognition between a model RNA and two different steric zipper spines using molecular dynamics simulations. We found that the interaction occurs and displays peptide-sequence dependence. Interestingly, interactions with polar zipper surfaces such as the formed by SNQNNF are more stable and favor the formation of β-barrel like complexes resembling the structures of toxic oligomers. These sequence-structure-recognition relationships of the two different assemblies may be exploited for the design of compounds targeting the fibers or competing with RNA-amyloid attachment

Co-deposition of basement membrane components during the induction of murine splenic AA amyloid

DEFF Research Database (Denmark)

Lyon, A W; Narindrasorasak, S; Young, I D

1991-01-01

Past studies have demonstrated that during murine AA amyloid induction there is co-deposition of the AA amyloid peptide and the basement membrane form of heparan sulfate proteoglycan. The synthesis and accumulation of heparan sulfate proteoglycan does not usually occur in the absence of other...... basement membrane components, such as type IV collagen, laminin, and fibronectin. Using immunohistochemical techniques, the present experiments have demonstrated that in addition to the heparan sulfate proteoglycan, there are other basement membrane components present in splenic AA amyloid deposits...... and these are present as soon as AA amyloid deposits are detectable. The results indicate that within the time constraints imposed by the experiments, the basement membrane components, fibronectin, laminin, type IV collagen, and heparan sulfate proteoglycan are co-deposited 36 to 48 hours after the AgNO3 and amyloid...

The molecular mass of dextran used to modify magnetite nanoparticles affects insulin amyloid aggregation

Science.gov (United States)

Siposova, Katarina; Pospiskova, Kristyna; Bednarikova, Zuzana; Safarik, Ivo; Safarikova, Mirka; Kubovcikova, Martina; Kopcansky, Peter; Gazova, Zuzana

2017-04-01

Protein transformation from its soluble state into amyloid aggregates is associated with amyloid-related diseases. Amyloid deposits of insulin fibrils have been found in the sites of subcutaneous insulin application in patients with prolonged diabetes. Using atomic force microscopy and ThT fluorescence assay we have investigated the interference of insulin amyloid aggregation with superparamagnetic Fe3O4-based nanoparticles (SPIONs) coated with dextran (DEX); molecular mass of dextran was equal to 15-20, 40 or 70 kDa. The obtained data indicate that all three types of dextran coated nanoparticles (NP-FeDEXs) are able to inhibit insulin fibrillization and to destroy amyloid fibrils. The extent of anti-amyloid activities depends on the properties of NP-FeDEXs, mainly on the size of nanoparticles which is determined by molecular mass of dextran molecules. The most effective inhibiting activity was observed for the smallest nanoparticles coated with 15-20 kDa dextran. Contrary, the highest destroying activity was observed for the largest NP-FeDEX (70 kDa dextran).

Role of sequence and structural polymorphism on the mechanical properties of amyloid fibrils.

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Gwonchan Yoon

Full Text Available Amyloid fibrils playing a critical role in disease expression, have recently been found to exhibit the excellent mechanical properties such as elastic modulus in the order of 10 GPa, which is comparable to that of other mechanical proteins such as microtubule, actin filament, and spider silk. These remarkable mechanical properties of amyloid fibrils are correlated with their functional role in disease expression. This suggests the importance in understanding how these excellent mechanical properties are originated through self-assembly process that may depend on the amino acid sequence. However, the sequence-structure-property relationship of amyloid fibrils has not been fully understood yet. In this work, we characterize the mechanical properties of human islet amyloid polypeptide (hIAPP fibrils with respect to their molecular structures as well as their amino acid sequence by using all-atom explicit water molecular dynamics (MD simulation. The simulation result suggests that the remarkable bending rigidity of amyloid fibrils can be achieved through a specific self-aggregation pattern such as antiparallel stacking of β strands (peptide chain. Moreover, we have shown that a single point mutation of hIAPP chain constituting a hIAPP fibril significantly affects the thermodynamic stability of hIAPP fibril formed by parallel stacking of peptide chain, and that a single point mutation results in a significant change in the bending rigidity of hIAPP fibrils formed by antiparallel stacking of β strands. This clearly elucidates the role of amino acid sequence on not only the equilibrium conformations of amyloid fibrils but also their mechanical properties. Our study sheds light on sequence-structure-property relationships of amyloid fibrils, which suggests that the mechanical properties of amyloid fibrils are encoded in their sequence-dependent molecular architecture.

Investigation of Amyloid Structures at Nanoscale via AFM based Dynamic Nanomechncial Microscopy

DEFF Research Database (Denmark)

Zhang, Shuai

2014-01-01

Amyloid structures are one important kind of protein aggregations. They are a group of stable misfolded species, other than native states, which have been found to accumulate as plaques on neuron cells. This behavior is considered to associate with tens of human neurodegenerative diseases...... summarized the main methodologies of DNM. I also utilized DNM to explore the path way of amyloid self-assembly, and the substrate effect to the conformation of amyloid structures. Furthermore, 2D peptide based material has also been characterized by DNM....

No association of cortical amyloid load and EEG connectivity in older people with subjective memory complaints

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Stefan Teipel

2018-01-01

Full Text Available Changes in functional connectivity of cortical networks have been observed in resting-state EEG studies in healthy aging as well as preclinical and clinical stages of AD. Little information, however, exists on associations between EEG connectivity and cortical amyloid load in people with subjective memory complaints. Here, we determined the association of global cortical amyloid load, as measured by florbetapir-PET, with functional connectivity based on the phase-lag index of resting state EEG data for alpha and beta frequency bands in 318 cognitively normal individuals aged 70–85 years with subjective memory complaints from the INSIGHT-preAD cohort. Within the entire group we did not find any significant associations between global amyloid load and phase-lag index in any frequency band. Assessing exclusively the subgroup of amyloid-positive participants, we found enhancement of functional connectivity with higher global amyloid load in the alpha and a reduction in the beta frequency bands. In the amyloid-negative participants, higher amyloid load was associated with lower connectivity in the low alpha band. However, these correlations failed to reach significance after controlling for multiple comparisons. The absence of a strong amyloid effect on functional connectivity may represent a selection effect, where individuals remain in the cognitively normal group only if amyloid accumulation does not impair cortical functional connectivity.

Neuroinflammation and common mechanism in Alzheimer's disease and prion amyloidosis: amyloid-associated proteins, neuroinflammation and neurofibrillary degeneration

NARCIS (Netherlands)

Rozemuller, A.J.M.; Jansen, C.; Carrano, A.; van Haastert, E.S.; Hondius, D.; van der Vies, S.M.; Hoozemans, J.J.M.

2012-01-01

Background: In cases with a long (>1 year) clinical duration of prion disease, the prion protein can form amyloid deposits. These cases do not show accumulation of 4-kDa β-amyloid, which is observed in amyloid deposits in Alzheimer's disease (AD). In AD, amyloid is associated with inflammation and

Inhibitory Effect of Lycopene on Amyloid-β-Induced Apoptosis in Neuronal Cells.

Science.gov (United States)

Hwang, Sinwoo; Lim, Joo Weon; Kim, Hyeyoung

2017-08-16

Alzheimer's disease (AD) is a fatal neurodegenerative disease. Brain amyloid-β deposition is a crucial feature of AD, causing neuronal cell death by inducing oxidative damage. Reactive oxygen species (ROS) activate NF-κB, which induces expression of Nucling. Nucling is a pro-apoptotic factor recruiting the apoptosome complex. Lycopene is an antioxidant protecting from oxidative stress-induced cell damage. We investigated whether lycopene inhibits amyloid-β-stimulated apoptosis through reducing ROS and inhibiting mitochondrial dysfunction and NF-κB-mediated Nucling expression in neuronal SH-SY5Y cells. We prepared cells transfected with siRNA for Nucling or nontargeting control siRNA to determine the role of Nucling in amyloid-β-induced apoptosis. The amyloid-β increased intracellular and mitochondrial ROS levels, apoptotic indices (p53, Bax/Bcl-2 ratio, caspase-3 cleavage), NF-kB activation and Nucling expression, while cell viability, mitochondrial membrane potential, and oxygen consumption rate decreased in SH-SY5Y cells. Lycopene inhibited these amyloid-β-induced alterations. However, amyloid-β did not induce apoptosis, determined by cell viability and apoptotic indices (p53, Bax/Bcl-2 ratio, caspase-3 cleavage), in the cells transfected with siRNA for Nucling. Lycopene inhibited apoptosis by reducing ROS, and by inhibiting mitochondrial dysfunction and NF-κB-target gene Nucling expression in neuronal cells. Lycopene may be beneficial for preventing oxidative stress-mediated neuronal death in patients with neurodegeneration.

Uptake of raft components into amyloid β-peptide aggregates and membrane damage.

Science.gov (United States)

Sasahara, Kenji; Morigaki, Kenichi; Mori, Yasuko

2015-07-15

Amyloid aggregation and deposition of amyloid β-peptide (Aβ) are pathologic characteristics of Alzheimer's disease (AD). Recent reports have shown that the association of Aβ with membranes containing ganglioside GM1 (GM1) plays a pivotal role in amyloid deposition and the pathogenesis of AD. However, the molecular interactions responsible for membrane damage associated with Aβ deposition are not fully understood. In this study, we microscopically observed amyloid aggregation of Aβ in the presence of lipid vesicles and on a substrate-supported planar membrane containing raft components and GM1. The experimental system enabled us to observe lipid-associated aggregation of Aβ, uptake of the raft components into Aβ aggregates, and relevant membrane damage. The results indicate that uptake of raft components from the membrane into Aβ deposits induces macroscopic heterogeneity of the membrane structure. Copyright © 2015 Elsevier Inc. All rights reserved.

Massive accumulation of luminal protease-deficient axonal lysosomes at Alzheimer's disease amyloid plaques.

Science.gov (United States)

Gowrishankar, Swetha; Yuan, Peng; Wu, Yumei; Schrag, Matthew; Paradise, Summer; Grutzendler, Jaime; De Camilli, Pietro; Ferguson, Shawn M

2015-07-14

Through a comprehensive analysis of organellar markers in mouse models of Alzheimer's disease, we document a massive accumulation of lysosome-like organelles at amyloid plaques and establish that the majority of these organelles reside within swollen axons that contact the amyloid deposits. This close spatial relationship between axonal lysosome accumulation and extracellular amyloid aggregates was observed from the earliest stages of β-amyloid deposition. Notably, we discovered that lysosomes that accumulate in such axons are lacking in multiple soluble luminal proteases and thus are predicted to be unable to efficiently degrade proteinaceous cargos. Of relevance to Alzheimer's disease, β-secretase (BACE1), the protein that initiates amyloidogenic processing of the amyloid precursor protein and which is a substrate for these proteases, builds up at these sites. Furthermore, through a comparison between the axonal lysosome accumulations at amyloid plaques and neuronal lysosomes of the wild-type brain, we identified a similar, naturally occurring population of lysosome-like organelles in neuronal processes that is also defined by its low luminal protease content. In conjunction with emerging evidence that the lysosomal maturation of endosomes and autophagosomes is coupled to their retrograde transport, our results suggest that extracellular β-amyloid deposits cause a local impairment in the retrograde axonal transport of lysosome precursors, leading to their accumulation and a blockade in their further maturation. This study both advances understanding of Alzheimer's disease brain pathology and provides new insights into the subcellular organization of neuronal lysosomes that may have broader relevance to other neurodegenerative diseases with a lysosomal component to their pathology.

Cerebral amyloid angiopathy severity is linked to dilation of juxtacortical perivascular spaces

NARCIS (Netherlands)

van Veluw, Susanne J; Biessels, Geert Jan; Bouvy, Willem H; Spliet, Wim Gm; Zwanenburg, Jaco Jm; Luijten, Peter R; Macklin, Eric A; Rozemuller, Annemieke Jm; Gurol, M Edip; Greenberg, Steven M; Viswanathan, Anand; Martinez-Ramirez, Sergi

2016-01-01

Perivascular spaces are an emerging marker of small vessel disease. Perivascular spaces in the centrum semiovale have been associated with cerebral amyloid angiopathy. However, a direct topographical relationship between dilated perivascular spaces and cerebral amyloid angiopathy severity has not

Regulation of presynaptic Ca2+, synaptic plasticity and contextual fear conditioning by a N-terminal β-amyloid fragment.

Science.gov (United States)

Lawrence, James L M; Tong, Mei; Alfulaij, Naghum; Sherrin, Tessi; Contarino, Mark; White, Michael M; Bellinger, Frederick P; Todorovic, Cedomir; Nichols, Robert A

2014-10-22

Soluble β-amyloid has been shown to regulate presynaptic Ca(2+) and synaptic plasticity. In particular, picomolar β-amyloid was found to have an agonist-like action on presynaptic nicotinic receptors and to augment long-term potentiation (LTP) in a manner dependent upon nicotinic receptors. Here, we report that a functional N-terminal domain exists within β-amyloid for its agonist-like activity. This sequence corresponds to a N-terminal fragment generated by the combined action of α- and β-secretases, and resident carboxypeptidase. The N-terminal β-amyloid fragment is present in the brains and CSF of healthy adults as well as in Alzheimer's patients. Unlike full-length β-amyloid, the N-terminal β-amyloid fragment is monomeric and nontoxic. In Ca(2+) imaging studies using a model reconstituted rodent neuroblastoma cell line and isolated mouse nerve terminals, the N-terminal β-amyloid fragment proved to be highly potent and more effective than full-length β-amyloid in its agonist-like action on nicotinic receptors. In addition, the N-terminal β-amyloid fragment augmented theta burst-induced post-tetanic potentiation and LTP in mouse hippocampal slices. The N-terminal fragment also rescued LTP inhibited by elevated levels of full-length β-amyloid. Contextual fear conditioning was also strongly augmented following bilateral injection of N-terminal β-amyloid fragment into the dorsal hippocampi of intact mice. The fragment-induced augmentation of fear conditioning was attenuated by coadministration of nicotinic antagonist. The activity of the N-terminal β-amyloid fragment appears to reside largely in a sequence surrounding a putative metal binding site, YEVHHQ. These findings suggest that the N-terminal β-amyloid fragment may serve as a potent and effective endogenous neuromodulator. Copyright © 2014 the authors 0270-6474/14/3414210-09$15.00/0.

Prevalence of Cerebral Amyloid Pathology in Persons Without Dementia A Meta-analysis

NARCIS (Netherlands)

Jansen, W.J.; Ossenkoppele, R.; Knol, D.L.; Tijms, B.M.; Scheltens, P.; Verhey, F.R.J.; Visser, P.J.

2015-01-01

IMPORTANCE: Cerebral amyloid-β aggregation is an early pathological event in Alzheimer disease (AD), starting decades before dementia onset. Estimates of the prevalence of amyloid pathology in persons without dementia are needed to understand the development of AD and to design prevention studies.

Prevalence of cerebral amyloid pathology in persons without dementia: a meta-analysis

NARCIS (Netherlands)

Jansen, W.J.; Ossenkoppele, R.; Knol, D.L.; Tijms, B.M.; Scheltens, P.J.; Verhey, F.R.J.; Visser, P.J.; Aalten, P.; Aarsland, D.; Alcolea, D.; Alexander, M.; Almdahl, I.S.; Arnold, S.E.; Baldeiras, I.; Barthel, H.; Berckel, B.N. van; Bibeau, K.; Blennow, K.; Brooks, D.J.; Buchem, M.A. van; Camus, V.; Cavedo, E.; Chen, K.; Chetelat, G.; Cohen, A.D.; Drzezga, A.; Engelborghs, S.; Fagan, A.M.; Fladby, T.; Fleisher, A.S.; Flier, W.M. van der; Ford, L.; Forster, S.; Fortea, J.; Foskett, N.; Frederiksen, K.S.; Freund-Levi, Y.; Frisoni, G.B.; Froelich, L.; Gabryelewicz, T.; Gill, K.D.; Gkatzima, O.; Gomez-Tortosa, E.; Gordon, M.F.; Grimmer, T.; Hampel, H.; Hausner, L.; Hellwig, S.; Herukka, S.K.; Hildebrandt, H.; Ishihara, L.; Ivanoiu, A.; Jagust, W.J.; Johannsen, P.; Kandimalla, R.; Kapaki, E.; Klimkowicz-Mrowiec, A.; Klunk, W.E.; Kohler, S.; Koglin, N.; Kornhuber, J.; Kramberger, M.G.; Laere, K. Van; Landau, S.M.; Lee, D.Y.; Leon, M.; Lisetti, V.; Lleo, A.; Madsen, K.; Maier, W.; Marcusson, J.; Mattsson, N.; Mendonca, A. de; Meulenbroek, O.V.; Meyer, P.T.; Mintun, M.A.; Mok, V.; Molinuevo, J.L.; Mollergard, H.M.; Morris, J.C.; Mroczko, B.; Mussele, S. Van der; Na, D.L.; Newberg, A.; Nordberg, A.; Nordlund, A.; Novak, G.P.; Paraskevas, G.P.; Parnetti, L.; Perera, G.; Peters, O.; Popp, J.; Prabhakar, S.; Rabinovici, G.D.; Ramakers, I.H.; Rami, L.; Oliveira, C.R.; Rinne, J.O.; Rodrigue, K.M.; Rodriguez-Rodriguez, E.; Verbeek, M.M.; et al.,

2015-01-01

IMPORTANCE: Cerebral amyloid-beta aggregation is an early pathological event in Alzheimer disease (AD), starting decades before dementia onset. Estimates of the prevalence of amyloid pathology in persons without dementia are needed to understand the development of AD and to design prevention

Feasibility and acceptance of simultaneous amyloid PET/MRI

International Nuclear Information System (INIS)

Schuetz, Lisa; Tiepolt, Solveig; Werner, Peter; Jochimsen, Thies; Rullmann, Michael; Sattler, Bernhard; Patt, Marianne; Barthel, Henryk; Lobsien, Donald; Fritzsch, Dominik; Hoffmann, Karl-Titus; Schroeter, Matthias L.; Villringer, Arno; Berrouschot, Joerg; Saur, Dorothee; Classen, Joseph; Hesse, Swen; Sabri, Osama; Gertz, Hermann-Josef

2016-01-01

Established Alzheimer's disease (AD) biomarker concepts classify into amyloid pathology and neuronal injury biomarkers, while recent alternative concepts classify into diagnostic and progression AD biomarkers. However, combined amyloid positron emission tomography/magnetic resonance imaging (PET/MRI) offers the chance to obtain both biomarker category read-outs within one imaging session, with increased patient as well as referrer convenience. The aim of this pilot study was to investigate this matter for the first time. 100 subjects (age 70 ± 10 yrs, 46 female), n = 51 with clinically defined mild cognitive impairment (MCI), n = 44 with possible/probable AD dementia, and n = 5 with frontotemporal lobe degeneration, underwent simultaneous [ 18 F]florbetaben or [ 11 C]PIB PET/MRI (3 Tesla Siemens mMR). Brain amyloid load, mesial temporal lobe atrophy (MTLA) by means of the Scheltens scale, and other morphological brain pathologies were scored by respective experts. The patients/caregivers as well as the referrers were asked to assess on a five-point scale the convenience related to the one-stop-shop PET and MRI approach. In three subjects, MRI revealed temporal lobe abnormalities other than MTLA. According to the National Institute on Aging-Alzheimer's Association classification, the combined amyloid-beta PET/MRI evaluation resulted in 31 %, 45 %, and 24 % of the MCI subjects being categorized as ''MCI-unlikely due to AD'', ''MCI due to AD-intermediate likelihood'', and ''MCI due to AD-high likelihood'', respectively. 50 % of the probable AD dementia patients were categorized as ''High level of evidence of AD pathophysiological process'', and 56 % of the possible AD dementia patients as ''Possible AD dementia - with evidence of AD pathophysiological process''. With regard to the International Working Group 2 classification, 36 subjects had both positive

Feasibility and acceptance of simultaneous amyloid PET/MRI

Energy Technology Data Exchange (ETDEWEB)

Schuetz, Lisa; Tiepolt, Solveig; Werner, Peter; Jochimsen, Thies; Rullmann, Michael; Sattler, Bernhard; Patt, Marianne; Barthel, Henryk [Leipzig University Hospital, Department of Nuclear Medicine, Leipzig (Germany); Lobsien, Donald; Fritzsch, Dominik; Hoffmann, Karl-Titus [Leipzig University Hospital, Department of Neuroradiology, Leipzig (Germany); Schroeter, Matthias L.; Villringer, Arno [Leipzig University Hospital and Max Planck Institute for Human Cognitive and Brain Sciences, Day Clinic for Cognitive Neurology, Leipzig (Germany); Leipzig University Hospital, IFB Adiposity Diseases, Leipzig (Germany); Berrouschot, Joerg [Clinical Centre Altenburger Land, Altenburg (Germany); Saur, Dorothee; Classen, Joseph [Leipzig University Hospital, Department of Neurology, Leipzig (Germany); Hesse, Swen; Sabri, Osama [Leipzig University Hospital, Department of Nuclear Medicine, Leipzig (Germany); Leipzig University Hospital, IFB Adiposity Diseases, Leipzig (Germany); Gertz, Hermann-Josef [Leipzig University Hospital, Department of Psychiatry, Leipzig (Germany)

2016-11-15

Established Alzheimer's disease (AD) biomarker concepts classify into amyloid pathology and neuronal injury biomarkers, while recent alternative concepts classify into diagnostic and progression AD biomarkers. However, combined amyloid positron emission tomography/magnetic resonance imaging (PET/MRI) offers the chance to obtain both biomarker category read-outs within one imaging session, with increased patient as well as referrer convenience. The aim of this pilot study was to investigate this matter for the first time. 100 subjects (age 70 ± 10 yrs, 46 female), n = 51 with clinically defined mild cognitive impairment (MCI), n = 44 with possible/probable AD dementia, and n = 5 with frontotemporal lobe degeneration, underwent simultaneous [{sup 18}F]florbetaben or [{sup 11}C]PIB PET/MRI (3 Tesla Siemens mMR). Brain amyloid load, mesial temporal lobe atrophy (MTLA) by means of the Scheltens scale, and other morphological brain pathologies were scored by respective experts. The patients/caregivers as well as the referrers were asked to assess on a five-point scale the convenience related to the one-stop-shop PET and MRI approach. In three subjects, MRI revealed temporal lobe abnormalities other than MTLA. According to the National Institute on Aging-Alzheimer's Association classification, the combined amyloid-beta PET/MRI evaluation resulted in 31 %, 45 %, and 24 % of the MCI subjects being categorized as ''MCI-unlikely due to AD'', ''MCI due to AD-intermediate likelihood'', and ''MCI due to AD-high likelihood'', respectively. 50 % of the probable AD dementia patients were categorized as ''High level of evidence of AD pathophysiological process'', and 56 % of the possible AD dementia patients as ''Possible AD dementia - with evidence of AD pathophysiological process''. With regard to the International Working Group 2 classification, 36 subjects had both

Hsp40 function in yeast prion propagation: Amyloid diversity necessitates chaperone functional complexity.

Science.gov (United States)

Sporn, Zachary A; Hines, Justin K

2015-01-01

Yeast prions are heritable protein-based elements, most of which are formed of amyloid aggregates that rely on the action of molecular chaperones for transmission to progeny. Prions can form distinct amyloid structures, known as 'strains' in mammalian systems, that dictate both pathological progression and cross-species infection barriers. In yeast these same amyloid structural polymorphisms, called 'variants', dictate the intensity of prion-associated phenotypes and stability in mitosis. We recently reported that [PSI(+)] prion variants differ in the fundamental domain requirements for one chaperone, the Hsp40/J-protein Sis1, which are mutually exclusive between 2 different yeast prions, demonstrating a functional plurality for Sis1. Here we extend that analysis to incorporate additional data that collectively support the hypothesis that Sis1 has multiple functional roles that can be accomplished by distinct sets of domains. These functions are differentially required by distinct prions and prion variants. We also present new data regarding Hsp104-mediated prion elimination and show that some Sis1 functions, but not all, are conserved in the human homolog Hdj1/DNAJB1. Importantly, of the 10 amyloid-based prions indentified to date in Saccharomyces cerevisiae, the chaperone requirements of only 4 are known, leaving a great diversity of amyloid structures, and likely modes of amyloid-chaperone interaction, largely unexplored.

Synovial deposition of wild-type transthyretin-derived amyloid in knee joint osteoarthritis patients.

Science.gov (United States)

Takanashi, Tetsuo; Matsuda, Masayuki; Yazaki, Masahide; Yamazaki, Hideshi; Nawata, Masashi; Katagiri, Yoshiki; Ikeda, Shu-Ichi

2013-09-01

To investigate histological features of deposited amyloid in the synovial tissue and its clinical significance in knee joint osteoarthritis (OA) patients. We prospectively enrolled 232 consecutive patients who underwent arthroplasty or total replacement of the knee joint for treatment of OA. Congo red staining and immunohistochemistry were performed in the synovial tissue obtained at surgery. When transthyretin (TTR)-derived amyloid was positive, we analyzed all 4 exons of the TTR gene using the direct DNA sequencing method in order to detect mutations. We analyzed 322 specimens in this study. Twenty-six specimens (8.1%) obtained from 21 patients (5 men and 16 women; mean, 79.0 ± 4.6 years) showed deposition of amyloid, which was positively stained with the anti-TTR antibody. Eighteen patients showed inhomogeneous accumulations of amyloid in the loose connective tissue under the synovial epithelia sometimes with nodule formation, while in the remaining three, small vessels in the adipose tissue were involved. Medical records of these patients revealed nothing remarkable in the clinical course, laboratory data or macroscopic intraarticular findings at surgery. No mutations were detectable in the TTR gene analysis. Wild-type TTR-derived amyloid may affect the synovial tissue as a result of long-term mechanical stress or as a part of senile systemic amyloidosis in approximately 8% of knee joint OA patients. No obvious clinical significance was found in synovial deposition of amyloid.

Identification of a Common Binding Mode for Imaging Agents to Amyloid Fibrils from Molecular Dynamics Simulations

DEFF Research Database (Denmark)

Skeby, Katrine Kirkeby; Sørensen, Jesper; Schiøtt, Birgit

2013-01-01

experimentally due to the insoluble nature of amyloid fibrils. This study uses molecular dynamics simulations to investigate the interactions between 13 aromatic amyloid imaging agents, entailing 4 different organic scaffolds, and a model of an amyloid fibril. Clustering analysis combined with free energy...

Influence of hydrophobic Teflon particles on the structure of amyloid beta-peptide

NARCIS (Netherlands)

Giacomelli, C.E.; Norde, W.

2003-01-01

The amyloid beta-protein (Abeta) constitutes the major peptide component of the amyloid plaque deposits of Alzheimer's disease in humans. The Abeta changes from a nonpathogenic to a pathogenic conformation resulting in self-aggregation and deposition of the peptide. It has been established that

A high-glycemic diet is associated with cerebral amyloid burden in cognitively normal older adults.

Science.gov (United States)

Taylor, Matthew K; Sullivan, Debra K; Swerdlow, Russell H; Vidoni, Eric D; Morris, Jill K; Mahnken, Jonathan D; Burns, Jeffrey M

2017-12-01

Background: Little is known about the relation between dietary intake and cerebral amyloid accumulation in aging. Objective: We assessed the association of dietary glycemic measures with cerebral amyloid burden and cognitive performance in cognitively normal older adults. Design: We performed cross-sectional analyses relating dietary glycemic measures [adherence to a high-glycemic-load diet (HGLDiet) pattern, intakes of sugar and carbohydrates, and glycemic load] with cerebral amyloid burden (measured by florbetapir F-18 positron emission tomography) and cognitive performance in 128 cognitively normal older adults who provided eligibility screening data for the University of Kansas's Alzheimer's Prevention through Exercise (APEX) Study. The study began in November 2013 and is currently ongoing. Results: Amyloid was elevated in 26% ( n = 33) of participants. HGLDiet pattern adherence ( P = 0.01), sugar intake ( P = 0.03), and carbohydrate intake ( P = 0.05) were significantly higher in participants with elevated amyloid burden. The HGLDiet pattern was positively associated with amyloid burden both globally and in all regions of interest independently of age, sex, and education (all P ≤ 0.001). Individual dietary glycemic measures (sugar intake, carbohydrate intake, and glycemic load) were also positively associated with global amyloid load and nearly all regions of interest independently of age, sex, and educational level ( P ≤ 0.05). Cognitive performance was associated only with daily sugar intake, with higher sugar consumption associated with poorer global cognitive performance (global composite measure and Mini-Mental State Examination) and performance on subtests of Digit Symbol, Trail Making Test B, and Block Design, controlling for age, sex, and education. Conclusion: A high-glycemic diet was associated with greater cerebral amyloid burden, which suggests diet as a potential modifiable behavior for cerebral amyloid accumulation and subsequent Alzheimer

Specific chlamydial inclusion membrane proteins associate with active Src family kinases in microdomains that interact with the host microtubule network.

Science.gov (United States)

Mital, Jeffrey; Miller, Natalie J; Fischer, Elizabeth R; Hackstadt, Ted

2010-09-01

Chlamydiae are Gram-negative obligate intracellular bacteria that cause diseases with significant medical and economic impact. Chlamydia trachomatis replicates within a vacuole termed an inclusion, which is extensively modified by the insertion of a number of bacterial effector proteins known as inclusion membrane proteins (Incs). Once modified, the inclusion is trafficked in a dynein-dependent manner to the microtubule-organizing centre (MTOC), where it associates with host centrosomes. Here we describe a novel structure on the inclusion membrane comprised of both host and bacterial proteins. Members of the Src family of kinases are recruited to the chlamydial inclusion in an active form. These kinases display a distinct, localized punctate microdomain-like staining pattern on the inclusion membrane that colocalizes with four chlamydial inclusion membrane proteins (Incs) and is enriched in cholesterol. Biochemical studies show that at least two of these Incs stably interact with one another. Furthermore, host centrosomes associate with these microdomain proteins in C. trachomatis-infected cells and in uninfected cells exogenously expressing one of the chlamydial effectors. Together, the data suggest that a specific structure on the C. trachomatis inclusion membrane may be responsible for the known interactions of chlamydiae with the microtubule network and resultant effects on centrosome stability.

Brain inflammation accompanies amyloid in the majority of mild cognitive impairment cases due to Alzheimer's disease.

Science.gov (United States)

Parbo, Peter; Ismail, Rola; Hansen, Kim V; Amidi, Ali; Mårup, Frederik H; Gottrup, Hanne; Brændgaard, Hans; Eriksson, Bengt O; Eskildsen, Simon F; Lund, Torben E; Tietze, Anna; Edison, Paul; Pavese, Nicola; Stokholm, Morten G; Borghammer, Per; Hinz, Rainer; Aanerud, Joel; Brooks, David J

2017-07-01

See Kreisl (doi:10.1093/awx151) for a scientific commentary on this article.Subjects with mild cognitive impairment associated with cortical amyloid-β have a greatly increased risk of progressing to Alzheimer's disease. We hypothesized that neuroinflammation occurs early in Alzheimer's disease and would be present in most amyloid-positive mild cognitive impairment cases. 11C-Pittsburgh compound B and 11C-(R)-PK11195 positron emission tomography was used to determine the amyloid load and detect the extent of neuroinflammation (microglial activation) in 42 mild cognitive impairment cases. Twelve age-matched healthy control subjects had 11C-Pittsburgh compound B and 10 healthy control subjects had 11C-(R)-PK11195 positron emission tomography for comparison. Amyloid-positivity was defined as 11C-Pittsburgh compound B target-to-cerebellar ratio above 1.5 within a composite cortical volume of interest. Supervised cluster analysis was used to generate parametric maps of 11C-(R)-PK11195 binding potential. Levels of 11C-(R)-PK11195 binding potential were measured in a selection of cortical volumes of interest and at a voxel level. Twenty-six (62%) of 42 mild cognitive impairment cases showed a raised cortical amyloid load compared to healthy controls. Twenty-two (85%) of the 26 amyloid-positive mild cognitive impairment cases showed clusters of increased cortical microglial activation accompanying the amyloid. There was a positive correlation between levels of amyloid load and 11C-(R)-PK11195 binding potentials at a voxel level within subregions of frontal, parietal and temporal cortices. 11C-(R)-PK11195 positron emission tomography reveals increased inflammation in a majority of amyloid positive mild cognitive impairment cases, its cortical distribution overlapping that of amyloid deposition. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Influence of retinoic acid on mesenchymal stem cell differentiation in amyloid hydrogels

Directory of Open Access Journals (Sweden)

Reeba Susan Jacob

2015-12-01

Full Text Available This paper presents data related to the research article “Self healing hydrogels composed of amyloid nano fibrils for cell culture and stem cell differentiation” [1]. Here we probed the collective influence of all-trans retinoic acid (RA and substrate properties (amyloid hydrogel on human mesenchymal stem cell (hMSC differentiation. Stem cells were cultured on soft amyloid hydrogels [1,2] in the presence and absence of matrix encapsulated RA. The cell morphology was imaged and assessed via quantification of circularity. Further immunostaining and quantitative real time PCR was used to quantify various markers of differentiation in the neuronal lineage.

A binding-site barrier affects imaging efficiency of high affinity amyloid-reactive peptide radiotracers in vivo.

Science.gov (United States)

Wall, Jonathan S; Williams, Angela; Richey, Tina; Stuckey, Alan; Huang, Ying; Wooliver, Craig; Macy, Sallie; Heidel, Eric; Gupta, Neil; Lee, Angela; Rader, Brianna; Martin, Emily B; Kennel, Stephen J

2013-01-01

Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selectively imaging systemic visceral AA amyloidosis in a murine model of the disease. The p5 peptide was posited to bind effectively to amyloid deposits, relative to similarly charged polybasic heparin-reactive peptides, because it adopted a polar α helix secondary structure. We have now synthesized a variant, p5R, in which the 8 lysine amino acids of p5 have been replaced with arginine residues predisposing the peptide toward the α helical conformation in an effort to enhance the reactivity of the peptide with the amyloid substrate. The p5R peptide had higher affinity for amyloid and visualized AA amyloid in mice by using SPECT/CT imaging; however, the microdistribution, as evidenced in micro-autoradiographs, was dramatically altered relative to the p5 peptide due to its increased affinity and a resultant "binding site barrier" effect. These data suggest that radioiodinated peptide p5R may be optimal for the in vivo detection of discreet, perivascular amyloid, as found in the brain and pancreatic vasculature, by using molecular imaging techniques; however, peptide p5, due to its increased penetration, may yield more quantitative imaging of expansive tissue amyloid deposits.

Genetic variation in Aquaporin-4 moderates the relationship between sleep and brain Aβ-amyloid burden.

Science.gov (United States)

Rainey-Smith, Stephanie R; Mazzucchelli, Gavin N; Villemagne, Victor L; Brown, Belinda M; Porter, Tenielle; Weinborn, Michael; Bucks, Romola S; Milicic, Lidija; Sohrabi, Hamid R; Taddei, Kevin; Ames, David; Maruff, Paul; Masters, Colin L; Rowe, Christopher C; Salvado, Olivier; Martins, Ralph N; Laws, Simon M

2018-02-26

The glymphatic system is postulated to be a mechanism of brain Aβ-amyloid clearance and to be most effective during sleep. Ablation of the astrocytic end-feet expressed water-channel protein, Aquaporin-4, in mice, results in impairment of this clearance mechanism and increased brain Aβ-amyloid deposition, suggesting that Aquaporin-4 plays a pivotal role in glymphatic function. Currently there is a paucity of literature regarding the impact of AQP4 genetic variation on sleep, brain Aβ-amyloid burden and their relationship to each other in humans. To address this a cross-sectional observational study was undertaken in cognitively normal older adults from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study. Genetic variants in AQP4 were investigated with respect to self-reported Pittsburgh Sleep Quality Index sleep parameters, positron emission tomography derived brain Aβ-amyloid burden and whether these genetic variants moderated the sleep-Aβ-amyloid burden relationship. One AQP4 variant, rs72878776, was associated with poorer overall sleep quality, while several SNPs moderated the effect of sleep latency (rs491148, rs9951307, rs7135406, rs3875089, rs151246) and duration (rs72878776, rs491148 and rs2339214) on brain Aβ-amyloid burden. This study suggests that AQP4 genetic variation moderates the relationship between sleep and brain Aβ-amyloid burden, which adds weight to the proposed glymphatic system being a potential Aβ-amyloid clearance mechanism and suggests that AQP4 genetic variation may impair this function. Further, AQP4 genetic variation should be considered when interpreting sleep-Aβ relationships.

Insulin amyloid fibrillation studied by terahertz spectroscopy and other biophysical methods

Energy Technology Data Exchange (ETDEWEB)

Liu, Rui [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); He, Mingxia [College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Su, Rongxin, E-mail: surx@tju.edu.cn [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China); Yu, Yanjun [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Qi, Wei; He, Zhimin [State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China)

2010-01-01

Assembly and fibrillation of amyloid proteins are believed to play a key role in the etiology of various human diseases, including Alzheimer's, Parkinson's, Huntington's and type II diabetes. Insights into conformational changes and formation processes during amyloid fibrillation are essential for the clinical diagnosis and drug discovery. To study the changes in secondary, tertiary, quaternary structures, and the alteration in the collective vibrational mode density of states during the amyloid fibrillation, bovine insulin in 20% acetic acid was incubated at 60 {sup o}C, and its multi-level structures were followed by various biophysical techniques, including circular dichroism (CD), thioflavin T fluorescence (ThT), dynamic light scattering (DLS), electron microscopy, and terahertz (THz) absorption spectroscopy. The experimental data demonstrated a transformation of {alpha}-helix into {beta}-sheet starting at 26 h. This was followed by the aggregation of insulin, as shown by ThT binding, with a transition midpoint at 41 h, and by the bulk formation of mature aggregates after about 71 h. THz is a quick and non-invasive technique, which has the advantage of allowing the study of the conformational state of biomolecules and tissues. We first applied THz spectroscopy to study the amyloid fibrillation. At the terahertz frequency range of 0.2-2.0 THz, there was an apparent increase in both the absorbance and refractive index in THz spectra. Thus, THz is expected to provide a new way of looking into amyloid fibrillation.

A comparative analysis of the aggregation behavior of amyloid-β peptide variants

NARCIS (Netherlands)

Vandersteen, Annelies; Hubin, Ellen; Sarroukh, Rabia; De Baets, Greet; Schymkowitz, Joost; Rousseau, Frederic; Subramaniam, Vinod; Raussens, Vincent; Wenschuh, Holger; Wildemann, Dirk; Broersen, Kerensa

2012-01-01

Aggregated forms of the amyloid-β peptide are hypothesized to act as the prime toxic agents in Alzheimer disease (AD). The in vivo amyloid-β peptide pool consists of both C- and N-terminally truncated or mutated peptides, and the composition thereof significantly determines AD risk. Other

The Alzheimer's Amyloid-Degrading Peptidase, Neprilysin: Can We Control It?

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N. N. Nalivaeva

2012-01-01

Full Text Available The amyloid cascade hypothesis of Alzheimer's disease (AD postulates that accumulation in the brain of amyloid β-peptide (Aβ is the primary trigger for neuronal loss specific to this pathology. In healthy brain, Aβ levels are regulated by a dynamic equilibrium between Aβ release from the amyloid precursor protein (APP and its removal by perivascular drainage or by amyloid-degrading enzymes (ADEs. During the last decade, the ADE family was fast growing, and currently it embraces more than 20 members. There are solid data supporting involvement of each of them in Aβ clearance but a zinc metallopeptidase neprilysin (NEP is considered as a major ADE. NEP plays an important role in brain function due to its role in terminating neuropeptide signalling and its decrease during ageing or after such pathologies as hypoxia or ischemia contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP by the APP intracellular domain (AICD opens new avenues for its therapeutic manipulation and raises hope for developing preventive strategies in AD. However, consideration needs to be given to the diverse physiological roles of NEP. This paper critically evaluates general biochemical and physiological functions of NEP and their therapeutic relevance.

Cerebral Amyloid Angiopathy: Diagnosis, Clinical Implications, and Management Strategies in Atrial Fibrillation.

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DeSimone, Christopher V; Graff-Radford, Jonathan; El-Harasis, Majd A; Rabinstein, Alejandro A; Asirvatham, Samuel J; Holmes, David R

2017-08-29

With an aging population, clinicians are more frequently encountering patients with atrial fibrillation who are also at risk of intracerebral hemorrhage due to cerebral amyloid angiopathy, the result of β-amyloid deposition in cerebral vessels. Cerebral amyloid angiopathy is common among elderly patients, and is associated with an increased risk of intracerebral bleeding, especially with the use of anticoagulation. Despite this association, this entity is absent in current risk-benefit analysis models, which may result in underestimation of the chance of bleeding in the subset of patients with this disease. Determining the presence and burden of cerebral amyloid angiopathy is particularly important when planning to start or restart anticoagulation after an intracerebral hemorrhage. Given the lack of randomized trial data to guide management strategies, we discuss a heart-brain team approach that includes clinician-patient shared decision making for the use of pharmacologic and nonpharmacologic approaches to diminish stroke risk. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Calumenin interacts with serum amyloid P component

DEFF Research Database (Denmark)

Vorum, H; Jacobsen, Christian; Honoré, Bent

2000-01-01

We recently reported the identification of human calumenin, a novel Ca(2+) binding, transformation-sensitive and secreted protein [Vorum et al. (1998) Biochim. Biophys. Acta 1386, 121-131; Vorum et al. (1999) Exp. Cell Res. 248, 473-481] belonging to the family of multiple EF-hand proteins...... with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate...... in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues. Udgivelsesdato: 2000-Jan-14...

Novel squarylium dyes for detection of amyloid fibrils in vitro

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K. O. Vus

2015-04-01

Full Text Available A series of novel symmetrical and asymmetrical squarylium dyes with the different substituents in the donor moieties have been tested for their ability to detect and characterize insulin and lysozyme amyloid fibrils prepared in acidic buffer at elevated temperature. The dye-protein binding parameters were estimated in terms of the one-site Langmuir adsorption model using the data of direct and reverse fluorimetric titrations. By comparing the dye quantum yields, binding affinities, and extents of the fluorescence enhancement in the protein-bound state, G6 and G7 were selected as the most prospective amyloid tracers. Furthermore, these probes provided evidence for the lower polarity of the lysozyme fibrillar grooves compared to insulin aggregates. The novel dyes G6 and G7 were recommended for amyloid fibril detection and characterization in the near-infrared region.

Beta-amyloid and cholinergic neurons

Czech Academy of Sciences Publication Activity Database

Doležal, Vladimír; Kašparová, Jana

2003-01-01

Roč. 28, 3-4 (2003), s. 499-506 ISSN 0364-3190 R&D Projects: GA ČR GA305/01/0283; GA AV ČR IAA5011206 Institutional research plan: CEZ:AV0Z5011922 Keywords : cholinergic neurons * AlzheimerŽs disease * beta-amyloid Subject RIV: FH - Neurology Impact factor: 1.511, year: 2003

Evaluation of systemic amyloidosis by scintigraphy with 123I-labeled serum amyloid P component

International Nuclear Information System (INIS)

Hawkins, P.N.; Lavender, J.P.; Pepys, M.B.

1990-01-01

In systemic amyloidosis the distribution and progression of disease have been difficult to monitor, because they can be demonstrated only by biopsy. Serum amyloid P component (SAP) is a normal circulating plasma protein that is deposited on amyloid fibrils because of its specific binding affinity for them. We investigated whether labeled SAP could be used to locate amyloid deposits. Purified human SAP labeled with iodine-123 was given intravenously to 50 patients with biopsy-proved systemic amyloidosis--25 with the AL (primary) type and 25 with the AA (secondary) type--and to 26 control patients with disease and 10 healthy subjects. Whole-body images and regional views were obtained after 24 hours and read in a blinded fashion. In the patients with amyloidosis the 123I-SAP was localized rapidly and specifically in amyloid deposits. The scintigraphic images obtained were characteristic and appeared to identify the extent of amyloid deposition in all 50 patients. There was no uptake of the 123I-SAP by the control patients and the healthy subjects. In all patients with AA amyloidosis the spleen was affected, whereas the scans showed uptake in the heart, skin, carpal region, and bone marrow only in patients with the AL type. Positive images were seen in six patients in whom biopsies had been negative or unsuccessful; in all six, amyloid was subsequently found on biopsy or at autopsy. Progressive amyloid deposition was observed in 9 of 11 patients studied serially. Scintigraphy after the injection of 123I-SAP can be used for diagnosing, locating, and monitoring the extent of systemic amyloidosis

Massive accumulation of luminal protease-deficient axonal lysosomes at Alzheimer’s disease amyloid plaques

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Gowrishankar, Swetha; Yuan, Peng; Wu, Yumei; Schrag, Matthew; Paradise, Summer; Grutzendler, Jaime; De Camilli, Pietro; Ferguson, Shawn M.

2015-01-01

Through a comprehensive analysis of organellar markers in mouse models of Alzheimer’s disease, we document a massive accumulation of lysosome-like organelles at amyloid plaques and establish that the majority of these organelles reside within swollen axons that contact the amyloid deposits. This close spatial relationship between axonal lysosome accumulation and extracellular amyloid aggregates was observed from the earliest stages of β-amyloid deposition. Notably, we discovered that lysosomes that accumulate in such axons are lacking in multiple soluble luminal proteases and thus are predicted to be unable to efficiently degrade proteinaceous cargos. Of relevance to Alzheimer’s disease, β-secretase (BACE1), the protein that initiates amyloidogenic processing of the amyloid precursor protein and which is a substrate for these proteases, builds up at these sites. Furthermore, through a comparison between the axonal lysosome accumulations at amyloid plaques and neuronal lysosomes of the wild-type brain, we identified a similar, naturally occurring population of lysosome-like organelles in neuronal processes that is also defined by its low luminal protease content. In conjunction with emerging evidence that the lysosomal maturation of endosomes and autophagosomes is coupled to their retrograde transport, our results suggest that extracellular β-amyloid deposits cause a local impairment in the retrograde axonal transport of lysosome precursors, leading to their accumulation and a blockade in their further maturation. This study both advances understanding of Alzheimer’s disease brain pathology and provides new insights into the subcellular organization of neuronal lysosomes that may have broader relevance to other neurodegenerative diseases with a lysosomal component to their pathology. PMID:26124111

Optical properties of amyloid stained by Congo red: history and mechanisms.

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Howie, Alexander J; Brewer, Douglas B

2009-04-01

Amyloid stained by Congo red has striking optical properties that generally have been poorly described and inadequately explained, although they can be understood from principles of physical optics. Molecules of Congo red are orientated on amyloid fibrils, and so the dye becomes dichroic and birefringent. The birefringence varies with wavelength in accordance with a fundamental property of all light-transmitting materials called anomalous dispersion of the refractive index around an absorption peak. The combination of this and absorption of light, with modification by any additional birefringence in the optical system, explains the various colours that can be seen in Congo red-stained amyloid between crossed polariser and analyser, and also when the polariser and analyser are progressively uncrossed. These are called anomalous colours.

A binding-site barrier affects imaging efficiency of high affinity amyloid-reactive peptide radiotracers in vivo.

Directory of Open Access Journals (Sweden)

Jonathan S Wall

Full Text Available Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selectively imaging systemic visceral AA amyloidosis in a murine model of the disease. The p5 peptide was posited to bind effectively to amyloid deposits, relative to similarly charged polybasic heparin-reactive peptides, because it adopted a polar α helix secondary structure. We have now synthesized a variant, p5R, in which the 8 lysine amino acids of p5 have been replaced with arginine residues predisposing the peptide toward the α helical conformation in an effort to enhance the reactivity of the peptide with the amyloid substrate. The p5R peptide had higher affinity for amyloid and visualized AA amyloid in mice by using SPECT/CT imaging; however, the microdistribution, as evidenced in micro-autoradiographs, was dramatically altered relative to the p5 peptide due to its increased affinity and a resultant "binding site barrier" effect. These data suggest that radioiodinated peptide p5R may be optimal for the in vivo detection of discreet, perivascular amyloid, as found in the brain and pancreatic vasculature, by using molecular imaging techniques; however, peptide p5, due to its increased penetration, may yield more quantitative imaging of expansive tissue amyloid deposits.

Amyloid and tau cerebrospinal fluid biomarkers in HIV infection

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Rosengren Lars

2009-12-01

Full Text Available Abstract Background Because of the emerging intersections of HIV infection and Alzheimer's disease, we examined cerebrospinal fluid (CSF biomarkers related of amyloid and tau metabolism in HIV-infected patients. Methods In this cross-sectional study we measured soluble amyloid precursor proteins alpha and beta (sAPPα and sAPPβ, amyloid beta fragment 1-42 (Aβ1-42, and total and hyperphosphorylated tau (t-tau and p-tau in CSF of 86 HIV-infected (HIV+ subjects, including 21 with AIDS dementia complex (ADC, 25 with central nervous system (CNS opportunistic infections and 40 without neurological symptoms and signs. We also measured these CSF biomarkers in 64 uninfected (HIV- subjects, including 21 with Alzheimer's disease, and both younger and older controls without neurological disease. Results CSF sAPPα and sAPPβ concentrations were highly correlated and reduced in patients with ADC and opportunistic infections compared to the other groups. The opportunistic infection group but not the ADC patients had lower CSF Aβ1-42 in comparison to the other HIV+ subjects. CSF t-tau levels were high in some ADC patients, but did not differ significantly from the HIV+ neuroasymptomatic group, while CSF p-tau was not increased in any of the HIV+ groups. Together, CSF amyloid and tau markers segregated the ADC patients from both HIV+ and HIV- neuroasymptomatics and from Alzheimer's disease patients, but not from those with opportunistic infections. Conclusions Parallel reductions of CSF sAPPα and sAPPβ in ADC and CNS opportunistic infections suggest an effect of CNS immune activation or inflammation on neuronal amyloid synthesis or processing. Elevation of CSF t-tau in some ADC and CNS infection patients without concomitant increase in p-tau indicates neural injury without preferential accumulation of hyperphosphorylated tau as found in Alzheimer's disease. These biomarker changes define pathogenetic pathways to brain injury in ADC that differ from those

Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

International Nuclear Information System (INIS)

Bayliss, D L; Walsh, J L; Iza, F; Kong, M G; Shama, G

2009-01-01

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

Brain amyloid β protein and memory disruption in Alzheimer’s disease

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Weiming Xia

2010-09-01

Full Text Available Weiming XiaCenter for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USAAbstract: The development of amyloid-containing neuritic plaques is an invariable characteristic of Alzheimer’s diseases (AD. The conversion from monomeric amyloid β protein (Aβ to oligomeric Aβ and finally neuritic plaques is highly dynamic. The specific Aß species that is correlated with disease severity remains to be discovered. Oligomeric Aβ has been detected in cultured cells, rodent and human brains, as well as human cerebrospinal fluid. Synthetic, cell, and brain derived Aβ oligomers have been found to inhibit hippocampal long-term potentiation (LTP and this effect can be suppressed by the blockage of Aβ oligomer formation. A large body of evidence suggests that Aβ oligomers inhibit N-methyl-D-aspartate receptor dependent LTP; additional receptors have also been found to elicit downstream pathways upon binding to Aβ oligomers. Amyloid antibodies and small molecular compounds that reduce brain Aβ levels and block Aβ oligomer formation are capable of reversing synaptic dysfunction and these approaches hold a promising therapeutic potential to rescue memory disruption.Keywords: Alzheimer, amyloid, oligomer, long-term potentiation, NMDA

Characterization of amyloid beta peptides from brain extracts of transgenic mice overexpressing the London mutant of human amyloid precursor protein.

Science.gov (United States)

Pype, Stefan; Moechars, Dieder; Dillen, Lieve; Mercken, Marc

2003-02-01

Alzheimer's disease (AD) is marked by the presence of neurofibrillary tangles and amyloid plaques in the brain of patients. To study plaque formation, we report on further quantitative and qualitative analysis of human and mouse amyloid beta peptides (Abeta) from brain extracts of transgenic mice overexpressing the London mutant of human amyloid precursor protein (APP). Using enzyme-linked immunosorbant assays (ELISAs) specific for either human or rodent Abeta, we found that the peptides from both species aggregated to form plaques. The ratios of deposited Abeta1-42/1-40 were in the order of 2-3 for human and 8-9 for mouse peptides, indicating preferential deposition of Abeta42. We also determined the identity and relative levels of other Abeta variants present in protein extracts from soluble and insoluble brain fractions. This was done by combined immunoprecipitation and mass spectrometry (IP/MS). The most prominent peptides truncated either at the carboxyl- or the amino-terminus were Abeta1-38 and Abeta11-42, respectively, and the latter was strongly enriched in the extracts of deposited peptides. Taken together, our data indicate that plaques of APP-London transgenic mice consist of aggregates of multiple human and mouse Abeta variants, and the human variants that we identified were previously detected in brain extracts of AD patients.

Imaging of Cerebral Amyloid Angiopathy with Bivalent (99m)Tc-Hydroxamamide Complexes.

Science.gov (United States)

Iikuni, Shimpei; Ono, Masahiro; Watanabe, Hiroyuki; Matsumura, Kenji; Yoshimura, Masashi; Kimura, Hiroyuki; Ishibashi-Ueda, Hatsue; Okamoto, Yoko; Ihara, Masafumi; Saji, Hideo

2016-05-16

Cerebral amyloid angiopathy (CAA), characterized by the deposition of amyloid aggregates in the walls of cerebral vasculature, is a major factor in intracerebral hemorrhage and vascular cognitive impairment and is also associated closely with Alzheimer's disease (AD). We previously reported (99m)Tc-hydroxamamide ((99m)Tc-Ham) complexes with a bivalent amyloid ligand showing high binding affinity for β-amyloid peptide (Aβ(1-42)) aggregates present frequently in the form in AD. In this article, we applied them to CAA-specific imaging probes, and evaluated their utility for CAA-specific imaging. In vitro inhibition assay using Aβ(1-40) aggregates deposited mainly in CAA and a brain uptake study were performed for (99m)Tc-Ham complexes, and all (99m)Tc-Ham complexes with an amyloid ligand showed binding affinity for Aβ(1-40) aggregates and very low brain uptake. In vitro autoradiography of human CAA brain sections and ex vivo autoradiography of Tg2576 mice were carried out for bivalent (99m)Tc-Ham complexes ([(99m)Tc]SB2A and [(99m)Tc]BT2B), and they displayed excellent labeling of Aβ depositions in human CAA brain sections and high affinity and selectivity to CAA in transgenic mice. These results may offer new possibilities for the development of clinically useful CAA-specific imaging probes based on the (99m)Tc-Ham complex.

Chlamydia trachomatis intercepts Golgi-derived sphingolipids through a Rab14-mediated transport required for bacterial development and replication.

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Anahí Capmany

2010-11-01

Full Text Available Chlamydia trachomatis are obligate intracellular bacteria that survive and replicate in a bacterial-modified phagosome called inclusion. As other intracellular parasites, these bacteria subvert the phagocytic pathway to avoid degradation in phagolysosomes and exploit trafficking pathways to acquire both energy and nutrients essential for their survival. Rabs are host proteins that control intracellular vesicular trafficking. Rab14, a Golgi-related Rab, controls Golgi to endosomes transport. Since Chlamydia establish a close relationship with the Golgi apparatus, the recruitment and participation of Rab14 on inclusion development and bacteria growth were analyzed. Time course analysis revealed that Rab14 associated with inclusions by 10 h post infection and was maintained throughout the entire developmental cycle. The recruitment was bacterial protein synthesis-dependent but independent of microtubules and Golgi integrity. Overexpression of Rab14 dominant negative mutants delayed inclusion enlargement, and impaired bacteria replication as determined by IFU. Silencing of Rab14 by siRNA also decreased bacteria multiplication and infectivity. By electron microscopy, aberrant bacteria were observed in cells overexpressing the cytosolic negative Rab14 mutant. Our results showed that Rab14 facilitates the delivery of sphingolipids required for bacterial development and replication from the Golgi to chlamydial inclusions. Novel anti-chlamydial therapies could be developed based on the knowledge of how bacteria subvert host vesicular transport events through Rabs manipulation.

Chlamydia trachomatis intercepts Golgi-derived sphingolipids through a Rab14-mediated transport required for bacterial development and replication.

Science.gov (United States)

Capmany, Anahí; Damiani, María Teresa

2010-11-22

Chlamydia trachomatis are obligate intracellular bacteria that survive and replicate in a bacterial-modified phagosome called inclusion. As other intracellular parasites, these bacteria subvert the phagocytic pathway to avoid degradation in phagolysosomes and exploit trafficking pathways to acquire both energy and nutrients essential for their survival. Rabs are host proteins that control intracellular vesicular trafficking. Rab14, a Golgi-related Rab, controls Golgi to endosomes transport. Since Chlamydia establish a close relationship with the Golgi apparatus, the recruitment and participation of Rab14 on inclusion development and bacteria growth were analyzed. Time course analysis revealed that Rab14 associated with inclusions by 10 h post infection and was maintained throughout the entire developmental cycle. The recruitment was bacterial protein synthesis-dependent but independent of microtubules and Golgi integrity. Overexpression of Rab14 dominant negative mutants delayed inclusion enlargement, and impaired bacteria replication as determined by IFU. Silencing of Rab14 by siRNA also decreased bacteria multiplication and infectivity. By electron microscopy, aberrant bacteria were observed in cells overexpressing the cytosolic negative Rab14 mutant. Our results showed that Rab14 facilitates the delivery of sphingolipids required for bacterial development and replication from the Golgi to chlamydial inclusions. Novel anti-chlamydial therapies could be developed based on the knowledge of how bacteria subvert host vesicular transport events through Rabs manipulation.

Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect

KAUST Repository

Demetrius, Lloyd A.; Magistretti, Pierre J.; Pellerin, Luc

2015-01-01

Epidemiological and biochemical studies show that the sporadic forms of Alzheimer's disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events—mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model.

Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect

KAUST Repository

Demetrius, Lloyd A.

2015-01-14

Epidemiological and biochemical studies show that the sporadic forms of Alzheimer\\'s disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events—mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model.

Protein recovery from inclusion bodies of Escherichia coli using mild solubilization process.

Science.gov (United States)

Singh, Anupam; Upadhyay, Vaibhav; Upadhyay, Arun Kumar; Singh, Surinder Mohan; Panda, Amulya Kumar

2015-03-25

Formation of inclusion bodies in bacterial hosts poses a major challenge for large scale recovery of bioactive proteins. The process of obtaining bioactive protein from inclusion bodies is labor intensive and the yields of recombinant protein are often low. Here we review the developments in the field that are targeted at improving the yield, as well as quality of the recombinant protein by optimizing the individual steps of the process, especially solubilization of the inclusion bodies and refolding of the solubilized protein. Mild solubilization methods have been discussed which are based on the understanding of the fact that protein molecules in inclusion body aggregates have native-like structure. These methods solubilize the inclusion body aggregates while preserving the native-like protein structure. Subsequent protein refolding and purification results in high recovery of bioactive protein. Other parameters which influence the overall recovery of bioactive protein from inclusion bodies have also been discussed. A schematic model describing the utility of mild solubilization methods for high throughput recovery of bioactive protein has also been presented.

Adaptive template generation for amyloid PET using a deep learning approach.

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Kang, Seung Kwan; Seo, Seongho; Shin, Seong A; Byun, Min Soo; Lee, Dong Young; Kim, Yu Kyeong; Lee, Dong Soo; Lee, Jae Sung

2018-05-11

Accurate spatial normalization (SN) of amyloid positron emission tomography (PET) images for Alzheimer's disease assessment without coregistered anatomical magnetic resonance imaging (MRI) of the same individual is technically challenging. In this study, we applied deep neural networks to generate individually adaptive PET templates for robust and accurate SN of amyloid PET without using matched 3D MR images. Using 681 pairs of simultaneously acquired 11 C-PIB PET and T1-weighted 3D MRI scans of AD, MCI, and cognitively normal subjects, we trained and tested two deep neural networks [convolutional auto-encoder (CAE) and generative adversarial network (GAN)] that produce adaptive best PET templates. More specifically, the networks were trained using 685,100 pieces of augmented data generated by rotating 527 randomly selected datasets and validated using 154 datasets. The input to the supervised neural networks was the 3D PET volume in native space and the label was the spatially normalized 3D PET image using the transformation parameters obtained from MRI-based SN. The proposed deep learning approach significantly enhanced the quantitative accuracy of MRI-less amyloid PET assessment by reducing the SN error observed when an average amyloid PET template is used. Given an input image, the trained deep neural networks rapidly provide individually adaptive 3D PET templates without any discontinuity between the slices (in 0.02 s). As the proposed method does not require 3D MRI for the SN of PET images, it has great potential for use in routine analysis of amyloid PET images in clinical practice and research. © 2018 Wiley Periodicals, Inc.

Amyloid Load in Fat Tissue Reflects Disease Severity and Predicts Survival in Amyloidosis

NARCIS (Netherlands)

Van Gameren, Ingrid I.; Hazenberg, Bouke P. C.; Bijzet, Johan; Haagsma, Elizabeth B.; Vellenga, Edo; Posthumus, Marcel D.; Jager, Pieter L.; Van Rijswijk, Martin H.

Objective. The severity of systemic amyloidosis is thought to be related to the extent of amyloid deposition. We studied whether amyloid load in fat tissue reflects disease severity and predicts survival. Methods. We studied all consecutive patients with systemic amyloidosis seen between January

Quantitative Amyloid Imaging in Autosomal Dominant Alzheimer's Disease: Results from the DIAN Study Group.

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Yi Su

Full Text Available Amyloid imaging plays an important role in the research and diagnosis of dementing disorders. Substantial variation in quantitative methods to measure brain amyloid burden exists in the field. The aim of this work is to investigate the impact of methodological variations to the quantification of amyloid burden using data from the Dominantly Inherited Alzheimer's Network (DIAN, an autosomal dominant Alzheimer's disease population. Cross-sectional and longitudinal [11C]-Pittsburgh Compound B (PiB PET imaging data from the DIAN study were analyzed. Four candidate reference regions were investigated for estimation of brain amyloid burden. A regional spread function based technique was also investigated for the correction of partial volume effects. Cerebellar cortex, brain-stem, and white matter regions all had stable tracer retention during the course of disease. Partial volume correction consistently improves sensitivity to group differences and longitudinal changes over time. White matter referencing improved statistical power in the detecting longitudinal changes in relative tracer retention; however, the reason for this improvement is unclear and requires further investigation. Full dynamic acquisition and kinetic modeling improved statistical power although it may add cost and time. Several technical variations to amyloid burden quantification were examined in this study. Partial volume correction emerged as the strategy that most consistently improved statistical power for the detection of both longitudinal changes and across-group differences. For the autosomal dominant Alzheimer's disease population with PiB imaging, utilizing brainstem as a reference region with partial volume correction may be optimal for current interventional trials. Further investigation of technical issues in quantitative amyloid imaging in different study populations using different amyloid imaging tracers is warranted.

Absence of beta-amyloid in cortical cataracts of donors with and without Alzheimer's disease.

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Michael, Ralph; Rosandić, Jurja; Montenegro, Gustavo A; Lobato, Elvira; Tresserra, Francisco; Barraquer, Rafael I; Vrensen, Gijs F J M

2013-01-01

Eye lenses from human donors with and without Alzheimer's disease (AD) were studied to evaluate the presence of amyloid in cortical cataract. We obtained 39 lenses from 21 postmortem donors with AD and 15 lenses from age-matched controls provided by the Banco de Ojos para Tratamientos de la Ceguera (Barcelona, Spain). For 17 donors, AD was clinically diagnosed by general physicians and for 4 donors the AD diagnosis was neuropathologically confirmed. Of the 21 donors with AD, 6 had pronounced bilateral cortical lens opacities and 15 only minor or no cortical opacities. As controls, 7 donors with pronounced cortical opacities and 8 donors with almost transparent lenses were selected. All lenses were photographed in a dark field stereomicroscope. Histological sections were analyzed using a standard and a more sensitive Congo red protocol, thioflavin staining and beta-amyloid immunohistochemistry. Brain tissue from two donors, one with cerebral amyloid angiopathy and another with advanced AD-related changes and one cornea with lattice dystrophy were used as positive controls for the staining techniques. Thioflavin, standard and modified Congo red staining were positive in the control brain tissues and in the dystrophic cornea. Beta-amyloid immunohistochemistry was positive in the brain tissues but not in the cornea sample. Lenses from control and AD donors were, without exception, negative after Congo red, thioflavin, and beta-amyloid immunohistochemical staining. The results of the positive control tissues correspond well with known observations in AD, amyloid angiopathy and corneas with lattice dystrophy. The absence of staining in AD and control lenses with the techniques employed lead us to conclude that there is no beta-amyloid in lenses from donors with AD or in control cortical cataracts. The inconsistency with previous studies of Goldstein et al. (2003) and Moncaster et al. (2010), both of which demonstrated positive Congo red, thioflavin, and beta-amyloid

Amyloid-β secretion, generation, and lysosomal sequestration in response to proteasome inhibition

DEFF Research Database (Denmark)

Agholme, Lotta; Hallbeck, Martin; Benedikz, Eirikur

2012-01-01

, as the autophagosome has been suggested as a site of amyloid-β (Aβ) generation. In this study, we investigated the effect of proteasome inhibition on Aβ accumulation and secretion, as well as the processing of amyloid-β protein precursor (AβPP) in AβPP(Swe) transfected SH-SY5Y neuroblastoma cells. We show...

The Pattern of Brain Amyloid Load in Posterior Cortical Atrophy Using 18F-AV45: Is Amyloid the Principal Actor in the Disease

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Emilie Beaufils

2014-11-01

Full Text Available Background: Posterior cortical atrophy (PCA is characterized by progressive higher-order visuoperceptual dysfunction and praxis declines. This syndrome is related to a number of underlying diseases, including, in most cases, Alzheimer's disease (AD. The aim of this study was to compare the amyloid load with 18F-AV45 positron emission tomography (PET between PCA and AD subjects. Methods: We performed 18F-AV45 PET, cerebrospinal fluid (CSF biomarker analysis and a neuropsychological assessment in 11 PCA patients and 12 AD patients. Results: The global and regional 18F-AV45 uptake was similar in the PCA and AD groups. No significant correlation was observed between global 18F-AV45 uptake and CSF biomarkers or between regional 18F-AV45 uptake and cognitive and affective symptoms. Conclusion: This 18F-AV45 PET amyloid imaging study showed no specific regional pattern of cortical 18F-AV45 binding in PCA patients. These results confirm that a distinct clinical phenotype in amnestic AD and PCA is not related to amyloid distribution.

The Pattern of Brain Amyloid Load in Posterior Cortical Atrophy Using 18F-AV45: Is Amyloid the Principal Actor in the Disease?

Science.gov (United States)

Beaufils, Emilie; Ribeiro, Maria Joao; Vierron, Emilie; Vercouillie, Johnny; Dufour-Rainfray, Diane; Cottier, Jean-Philippe; Camus, Vincent; Mondon, Karl; Guilloteau, Denis; Hommet, Caroline

2014-01-01

Background Posterior cortical atrophy (PCA) is characterized by progressive higher-order visuoperceptual dysfunction and praxis declines. This syndrome is related to a number of underlying diseases, including, in most cases, Alzheimer's disease (AD). The aim of this study was to compare the amyloid load with 18F-AV45 positron emission tomography (PET) between PCA and AD subjects. Methods We performed 18F-AV45 PET, cerebrospinal fluid (CSF) biomarker analysis and a neuropsychological assessment in 11 PCA patients and 12 AD patients. Results The global and regional 18F-AV45 uptake was similar in the PCA and AD groups. No significant correlation was observed between global 18F-AV45 uptake and CSF biomarkers or between regional 18F-AV45 uptake and cognitive and affective symptoms. Conclusion This 18F-AV45 PET amyloid imaging study showed no specific regional pattern of cortical 18F-AV45 binding in PCA patients. These results confirm that a distinct clinical phenotype in amnestic AD and PCA is not related to amyloid distribution. PMID:25538727

Sporadic inclusion-body myositis: conformational multifactorial ageing-related degenerative muscle disease associated with proteasomal and lysosomal inhibition, endoplasmic reticulum stress, and accumulation of amyloid-β42 oligomers and phosphorylated tau.

Science.gov (United States)

Askanas, Valerie; Engel, W King

2011-04-01

The pathogenesis of sporadic inclusion-body myositis (s-IBM), the most common muscle disease of older persons, is complex and multifactorial. Both the muscle fiber degeneration and the mononuclear-cell inflammation are components of the s-IBM pathology, but how each relates to the pathogenesis remains unsettled. We consider that the intramuscle fiber degenerative component plays the primary and the major pathogenic role leading to muscle fiber destruction and clinical weakness. In this article we review the newest research advances that provide a better understanding of the s-IBM pathogenesis. Cellular abnormalities occurring in s-IBM muscle fibers are discussed, including: several proteins that are accumulated in the form of aggregates within muscle fibers, including amyloid-β42 and its oligomers, and phosphorylated tau in the form of paired helical filaments, and we consider their putative detrimental influence; cellular mechanisms leading to protein misfolding and aggregation, including evidence of their inadequate disposal; pathogenic importance of endoplasmic reticulum stress and the unfolded protein response demonstrated in s-IBM muscle fibers; and decreased deacetylase activity of SIRT1. All these factors are combined with, and perhaps provoked by, an ageing intracellular milieu. Also discussed are the intriguing phenotypic similarities between s-IBM muscle fibers and the brains of Alzheimer and Parkinson's disease patients, the two most common neurodegenerative diseases associated with ageing. Muscle biopsy diagnostic criteria are also described and illustrated. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Association of Cerebral Amyloid-β Aggregation With Cognitive Functioning in Persons Without Dementia

DEFF Research Database (Denmark)

Jansen, Willemijn J; Ossenkoppele, Rik; Tijms, Betty M

2018-01-01

Importance: Cerebral amyloid-β aggregation is an early event in Alzheimer disease (AD). Understanding the association between amyloid aggregation and cognitive manifestation in persons without dementia is important for a better understanding of the course of AD and for the design of prevention tr...

Structural evaluation of an amyloid fibril model using small-angle x-ray scattering

Science.gov (United States)

Dahal, Eshan; Choi, Mina; Alam, Nadia; Bhirde, Ashwinkumar A.; Beaucage, Serge L.; Badano, Aldo

2017-08-01

Amyloid fibrils are highly structured protein aggregates associated with a wide range of diseases including Alzheimer’s and Parkinson’s. We report a structural investigation of an amyloid fibril model prepared from a commonly used plasma protein (bovine serum albumin (BSA)) using small-angle x-ray scattering (SAXS) technique. As a reference, the size estimates from SAXS are compared to dynamic light scattering (DLS) data and the presence of amyloid-like fibrils is confirmed using Congo red absorbance assay. Our SAXS results consistently show the structural transformation of BSA from spheroid to rod-like elongated structures during the fibril formation process. We observe the elongation of fibrils over two months with fibril length growing from 35.9  ±  3.0 nm to 51.5  ±  2.1 nm. Structurally metastable fibrils with distinct SAXS profiles have been identified. As proof of concept, we demonstrate the use of such distinct SAXS profiles to detect fibrils in the mixture solutions of two species by estimating their volume fractions. This easily detectable and well-characterized amyloid fibril model from BSA can be readily used as a control or standard reference to further investigate SAXS applications in the detection of structurally diverse amyloid fibrils associated with protein aggregation diseases.

Organization and Biology of the Porcine Serum Amyloid A (SAA) Gene Cluster: Isoform Specific Responses to Bacterial Infection

DEFF Research Database (Denmark)

Olsen, Helle G; Skovgaard, Kerstin; Nielsen, Ole L

2013-01-01

Serum amyloid A (SAA) is a prominent acute phase protein. Although its biological functions are debated, the wide species distribution of highly homologous SAA proteins and their uniform behavior in response to injury or inflammation in itself suggests a significant role for this protein. The pig...... is increasingly being used as a model for the study of inflammatory reactions, yet only little is known about how specific SAA genes are regulated in the pig during acute phase responses and other responses induced by pro-inflammatory host mediators. We designed SAA gene specific primers and quantified the gene...... expression of porcine SAA1, SAA2, SAA3, and SAA4 by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) in liver, spleen, and lung tissue from pigs experimentally infected with the Gram-negative swine specific bacterium Actinobacillus pleuropneumoniae, as well as from pigs experimentally...

The acute phase response of haptoglobin and serum amyloid A (SAA) in cattle undergoing experimental infection with bovine respiratory syncytial virus

DEFF Research Database (Denmark)

Heegaard, Peter M. H.; Godson, D.L.; Toussaint, M.J.M.

2000-01-01

respiratory syncytial virus (BRSV), analysing the induction of the two most dominant bovine acute phase proteins haptoglobin and serum amyloid A (SAA). Strong and reproducible acute phase responses were detected for both proteins, peaking at around 7-8 days after inoculation of BRSV, while no response...... was seen in mock-inoculated control animals. The serum concentrations reached for SAA and haptoglobin during the BRSV-induced acute phase response were generally the same or higher than previously reported for bacterial infections in calves. The magnitude and the duration of the haptoglobin response...... was found to correlate well with the severity of clinical signs (fever) and with the extent of lung consolidation while SAA responded most rapidly to infection....

Amyloid precursor protein secretases as therapeutic targets for traumatic brain injury

OpenAIRE

Loane, David J; Pocivavsek, Ana; Moussa, Charbel E-H; Thompson, Rachel; Matsuoka, Yasuji; Faden, Alan I; Rebeck, G William; Burns, Mark P

2009-01-01

Amyloid-β (Aβ) peptides, found in Alzheimer’s disease brain, accumulate rapidly after traumatic brain injury (TBI) in both humans and animals. Here we show that blocking either β- or γ-secretase, enzymes required for production of Aβ from amyloid precursor protein (APP), can ameliorate motor and cognitive deficits and reduce cell loss after experimental TBI in mice. Thus, APP secretases are promising targets for treatment of TBI.

Confinement-induced liquid crystalline transitions in amyloid fibril cholesteric tactoids

Science.gov (United States)

Nyström, Gustav; Arcari, Mario; Mezzenga, Raffaele

2018-04-01

Chirality is ubiquitous in nature and plays crucial roles in biology, medicine, physics and materials science. Understanding and controlling chirality is therefore an important research challenge with broad implications. Unlike other chiral colloids, such as nanocellulose or filamentous viruses, amyloid fibrils form nematic phases but appear to miss their twisted form, the cholesteric or chiral nematic phases, despite a well-defined chirality at the single fibril level. Here we report the discovery of cholesteric phases in amyloids, using β-lactoglobulin fibrils shortened by shear stresses. The physical behaviour of these new cholesteric materials exhibits unprecedented structural complexity, with confinement-driven ordering transitions between at least three types of nematic and cholesteric tactoids. We use energy functional theory to rationalize these results and observe a chirality inversion from the left-handed amyloids to right-handed cholesteric droplets. These findings deepen our understanding of cholesteric phases, advancing their use in soft nanotechnology, nanomaterial templating and self-assembly.

Amyloid cascade hypothesis: Pathogenesis and therapeutic strategies in Alzheimer's disease.

Science.gov (United States)

Barage, Sagar H; Sonawane, Kailas D

2015-08-01

Alzheimer's disease is an irreversible, progressive neurodegenerative disorder. Various therapeutic approaches are being used to improve the cholinergic neurotransmission, but their role in AD pathogenesis is still unknown. Although, an increase in tau protein concentration in CSF has been described in AD, but several issues remains unclear. Extensive and accurate analysis of CSF could be helpful to define presence of tau proteins in physiological conditions, or released during the progression of neurodegenerative disease. The amyloid cascade hypothesis postulates that the neurodegeneration in AD caused by abnormal accumulation of amyloid beta (Aβ) plaques in various areas of the brain. The amyloid hypothesis has continued to gain support over the last two decades, particularly from genetic studies. Therefore, current research progress in several areas of therapies shall provide an effective treatment to cure this devastating disease. This review critically evaluates general biochemical and physiological functions of Aβ directed therapeutics and their relevance. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Behavioural problems and personality change related to cerebral amyloid angiopathy].

Science.gov (United States)

Gahr, Maximilian; Connemann, Bernhard J; Schönfeldt-Lecuona, Carlos

2012-11-01

Cerebral amyloid angiopathy (CAA) belongs to the group of amyloidoses that are characterized by the deposition of insoluble and tissue-damaging amyloid proteins. Spontaneous intracerebral hemorrhage is the common clinical presentation of CAA resulting from the degenerative effect of beta amyloid on the cerebral vascular system. Though CAA is rather a neurological disease psychiatric symptoms can occur and even dominate the clinical picture. A case report is presented in order to illustrate the association between CAA and psychiatric symptoms. We report the case of a 54-year-old female patient with radiologic references to a probable CAA and mild cognitive impairment who developed behavioural difficulties and personality change that necessitated a psychiatric treatment. Psychiatric symptoms were most likely due to CAA. CAA can be associated with psychiatric symptoms and hence should be considered in the treatment of elderly patients with behavioural problems or personality changes. Diagnostic neuroimaging and examination of cerebrospinal fluid is recommended. © Georg Thieme Verlag KG Stuttgart · New York.

Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

Energy Technology Data Exchange (ETDEWEB)

Bayliss, D L; Walsh, J L; Iza, F; Kong, M G [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Shama, G [Department of Chemical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)], E-mail: m.g.kong@lboro.ac.uk

2009-11-15

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

NARCIS (Netherlands)

Giacomelli, CE; Norde, W

2005-01-01

The conformational change of the 39-43 residues of the amyloid beta-peptide (A beta) toward a beta-sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

Conformational changes of the amyloid beta-peptide (1-40) adsorbed on solid surfaces

NARCIS (Netherlands)

Giacomelli, C.E.; Norde, W.

2005-01-01

The conformational change of the 39-43 residues of the amyloid beta -peptide (A beta) toward a beta -sheet enriched state promotes self-aggregation of the peptide molecules and constitutes the major peptide component of the amyloid plaques in Alzheimer patients. The crucial question behind the

Insights into the variability of nucleated amyloid polymerization by a minimalistic model of stochastic protein assembly

Energy Technology Data Exchange (ETDEWEB)

Eugène, Sarah, E-mail: Sarah.Eugene@inria.fr; Doumic, Marie, E-mail: Philippe.Robert@inria.fr, E-mail: Marie.Doumic@inria.fr [INRIA de Paris, 2 Rue Simone Iff, CS 42112, 75589 Paris Cedex 12 (France); Sorbonne Universités, UPMC Université Pierre et Marie Curie, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005 Paris (France); Xue, Wei-Feng, E-mail: W.F.Xue@kent.ac.uk [School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ (United Kingdom); Robert, Philippe, E-mail: Philippe.Robert@inria.fr [INRIA de Paris, 2 Rue Simone Iff, CS 42112, 75589 Paris Cedex 12 (France)

2016-05-07

Self-assembly of proteins into amyloid aggregates is an important biological phenomenon associated with human diseases such as Alzheimer’s disease. Amyloid fibrils also have potential applications in nano-engineering of biomaterials. The kinetics of amyloid assembly show an exponential growth phase preceded by a lag phase, variable in duration as seen in bulk experiments and experiments that mimic the small volumes of cells. Here, to investigate the origins and the properties of the observed variability in the lag phase of amyloid assembly currently not accounted for by deterministic nucleation dependent mechanisms, we formulate a new stochastic minimal model that is capable of describing the characteristics of amyloid growth curves despite its simplicity. We then solve the stochastic differential equations of our model and give mathematical proof of a central limit theorem for the sample growth trajectories of the nucleated aggregation process. These results give an asymptotic description for our simple model, from which closed form analytical results capable of describing and predicting the variability of nucleated amyloid assembly were derived. We also demonstrate the application of our results to inform experiments in a conceptually friendly and clear fashion. Our model offers a new perspective and paves the way for a new and efficient approach on extracting vital information regarding the key initial events of amyloid formation.

Amyloid formation and disaggregation of α-synuclein and its tandem repeat (α-TR)

International Nuclear Information System (INIS)

Bae, Song Yi; Kim, Seulgi; Hwang, Heejin; Kim, Hyun-Kyung; Yoon, Hyun C.; Kim, Jae Ho; Lee, SangYoon; Kim, T. Doohun

2010-01-01

Research highlights: → Formation of the α-synuclein amyloid fibrils by [BIMbF 3 Im]. → Disaggregation of amyloid fibrils by epigallocatechin gallate (EGCG) and baicalein. → Amyloid formation of α-synuclein tandem repeat (α-TR). -- Abstract: The aggregation of α-synuclein is clearly related to the pathogenesis of Parkinson's disease. Therefore, detailed understanding of the mechanism of fibril formation is highly valuable for the development of clinical treatment and also of the diagnostic tools. Here, we have investigated the interaction of α-synuclein with ionic liquids by using several biochemical techniques including Thioflavin T assays and transmission electron microscopy (TEM). Our data shows a rapid formation of α-synuclein amyloid fibrils was stimulated by 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BIMbF 3 Im], and these fibrils could be disaggregated by polyphenols such as epigallocatechin gallate (EGCG) and baicalein. Furthermore, the effect of [BIMbF 3 Im] on the α-synuclein tandem repeat (α-TR) in the aggregation process was studied.

Functional and structural effects of amyloid-β aggregate on Xenopus laevis oocytes.

Science.gov (United States)

Parodi, Jorge; Ochoa-de la Paz, Lenin; Miledi, Ricardo; Martínez-Torres, Ataúlfo

2012-10-01

Xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of "spontaneous" blips ranging in amplitude from 3.8 ± 0.9 nA at the beginning of the recordings to 6.8 ± 1.7 nA after 15 min of exposure to 1 μM aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 ± 1.2 nA) and gramicidin (6.3 ± 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca(2+) was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca(2+)-dependent Cl(-) currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (T(out)) and the serum-activated, oscillatory Cl(-) currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca(2+)-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication.

Long-term TNF-alpha blockade in patients with amyloid A amyloidosis complicating rheumatic diseases.

Science.gov (United States)

Fernández-Nebro, Antonio; Olivé, Alejandro; Castro, María Carmen; Varela, Angela Herranz; Riera, Elena; Irigoyen, Maria V; García de Yébenes, María Jesús; García-Vicuña, Rosario

2010-05-01

To evaluate the effectiveness and safety of anti-tumor necrosis factor therapy in patients with amyloid A amyloidosis. Multicenter, controlled, dynamic prospective cohort study of 36 patients with amyloid A amyloidosis (94% kidney involvement) treated with anti-tumor necrosis factor agents (drug exposure of 102.97 patient-years). As an external control group, 35 propensity score-matched non-amyloid patients were chosen from the Base de Datos de Productos Biológicos de la Sociedad Española de Reumatología registry. The end points were kidney response and progression, anti-tumor necrosis factor continuation rate, patient survival, and adverse events. At the end of follow-up, a kidney response was observed in 12 of 22 patients (54.5%) and a kidney progression was observed in 6 of 36 patients (17%). The kidney amyloidosis remained stable in 16 of 36 patients (44%). The level of acute phase reactants diminished but did not reach the normal level. The continuation rates of anti-tumor necrosis factor drugs among patients with amyloid A amyloidosis after 1, 2, 3, and 4 or more years were 80%, 80%, 61%, and 52%, respectively, comparable to controls. The 5-year cumulative survival of amyloid A amyloidosis cases was 90.6%, and the 10-year survival was 78.5%. In a multivariate Cox regression analysis, the duration of amyloidosis and the level of proteinuria at the onset of anti-tumor necrosis factor treatment were independent predictors of treatment failure, whereas the level of proteinuria was the only factor that predicts mortality. Most adverse events were similar in both groups, although the number of infections was 3 times higher in amyloid A amyloidosis cases. Anti-tumor necrosis factor drugs are effective in treating amyloid A amyloidosis, although they might increase the risk of infection. Copyright 2010 Elsevier Inc. All rights reserved.

Real-time amyloid aggregation monitoring with a photonic crystal-based approach.

Science.gov (United States)

Santi, Sara; Musi, Valeria; Descrovi, Emiliano; Paeder, Vincent; Di Francesco, Joab; Hvozdara, Lubos; van der Wal, Peter; Lashuel, Hilal A; Pastore, Annalisa; Neier, Reinhard; Herzig, Hans Peter

2013-10-21

We propose the application of a new label-free optical technique based on photonic nanostructures to real-time monitor the amyloid-beta 1-42 (Aβ(1-42)) fibrillization, including the early stages of the aggregation process, which are related to the onset of the Alzheimer's Disease (AD). The aggregation of Aβ peptides into amyloid fibrils has commonly been associated with neuronal death, which culminates in the clinical features of the incurable degenerative AD. Recent studies revealed that cell toxicity is determined by the formation of soluble oligomeric forms of Aβ peptides in the early stages of aggregation. At this phase, classical amyloid detection techniques lack in sensitivity. Upon a chemical passivation of the sensing surface by means of polyethylene glycol, the proposed approach allows an accurate, real-time monitoring of the refractive index variation of the solution, wherein Aβ(1-42) peptides are aggregating. This measurement is directly related to the aggregation state of the peptide throughout oligomerization and subsequent fibrillization. Our findings open new perspectives in the understanding of the dynamics of amyloid formation, and validate this approach as a new and powerful method to screen aggregation at early stages. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoscopic and Photonic Ultrastructural Characterization of Two Distinct Insulin Amyloid States

Directory of Open Access Journals (Sweden)

Mikael Lindgren

2012-02-01

Full Text Available Two different conformational isoforms or amyloid strains of insulin with different cytotoxic capacity have been described previously. Herein these filamentous and fibrillar amyloid states of insulin were investigated using biophysical and spectroscopic techniques in combination with luminescent conjugated oligothiophenes (LCO. This new class of fluorescent probes has a well defined molecular structure with a distinct number of thiophene units that can adopt different dihedral angles depending on its binding site to an amyloid structure. Based on data from surface charge, hydrophobicity, fluorescence spectroscopy and imaging, along with atomic force microscopy (AFM, we deduce the ultrastructure and fluorescent properties of LCO stained insulin fibrils and filaments. Combined total internal reflection fluorescence microscopy (TIRFM and AFM revealed rigid linear fibrous assemblies of fibrils whereas filaments showed a short curvilinear morphology which assemble into cloudy deposits. All studied LCOs bound to the filaments afforded more blue-shifted excitation and emission spectra in contrast to those corresponding to the fibril indicating a different LCO binding site, which was also supported by less efficient hydrophobic probe binding. Taken together, the multi-tool approach used here indicates the power of ultrastructure identification applying AFM together with LCO fluorescence interrogation, including TIRFM, to resolve structural differences between amyloid states.

Native human serum amyloid P component is a single pentamer

DEFF Research Database (Denmark)

Sørensen, Inge Juul; Andersen, Ove; Nielsen, EH

1995-01-01

Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer...... by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum....

Influence of dendrimer's structure on its activity against amyloid fibril formation

International Nuclear Information System (INIS)

Klajnert, B.; Cortijo-Arellano, M.; Cladera, J.; Bryszewska, M.

2006-01-01

Inhibition of fibril assembly is a potential therapeutic strategy in neurodegenerative disorders such as prion and Alzheimer's diseases. Highly branched, globular polymers-dendrimers-are novel promising inhibitors of fibril formation. In this study, the effect of polyamidoamine (PAMAM) dendrimers (generations 3rd, 4th, and 5th) on amyloid aggregation of the prion peptide PrP 185-208 and the Alzheimer's peptide Aβ 1-28 was examined. Amyloid fibrils were produced in vitro and their formation was monitored using the dye thioflavin T (ThT). Fluorescence studies were complemented with electron microscopy. The results show that the higher the dendrimer generation, the larger the degree of inhibition of the amyloid aggregation process and the more effective are dendrimers in disrupting the already existing fibrils. A hypothesis on dendrimer-peptide interaction mechanism is presented based on the dendrimers' molecular structure

Viscoelasticity of amyloid plaques in transgenic mouse brain studied by Brillouin microspectroscopy and correlative Raman analysis

Directory of Open Access Journals (Sweden)

Sara Mattana

2017-11-01

Full Text Available Amyloidopathy is one of the most prominent hallmarks of Alzheimer’s disease (AD, the leading cause of dementia worldwide, and is characterized by the accumulation of amyloid plaques in the brain parenchyma. The plaques consist of abnormal deposits mainly composed of an aggregation-prone protein fragment, β-amyloid 1-40/1-42, into the extracellular matrix. Brillouin microspectroscopy is an all-optical contactless technique that is based on the interaction between visible light and longitudinal acoustic waves or phonons, giving access to the viscoelasticity of a sample on a subcellular scale. Here, we describe the first application of micromechanical mapping based on Brillouin scattering spectroscopy to probe the stiffness of individual amyloid plaques in the hippocampal part of the brain of a β-amyloid overexpressing transgenic mouse. Correlative analysis based on Brillouin and Raman microspectroscopy showed that amyloid plaques have a complex structure with a rigid core of β-pleated sheet conformation (β-amyloid protein surrounded by a softer ring-shaped region richer in lipids and other protein conformations. These preliminary results give a new insight into the plaque biophysics and biomechanics, and a valuable contrast mechanism for the study and diagnosis of amyloidopathy.

Use of amyloid PET across the spectrum of Alzheimer's disease: clinical utility and associated ethical issues.

Science.gov (United States)

Leuzy, Antoine; Zimmer, Eduardo Rigon; Heurling, Kerstin; Rosa-Neto, Pedro; Gauthier, Serge

2014-09-01

Abstract Recent advances have made possible the in vivo detection of beta-amyloid (Aβ) pathology using positron emission tomography. While the gold standard for amyloid imaging, carbon-11 labeled Pittsburgh compound B is increasingly being replaced by fluorine-18 labeled radiopharmaceuticals, with three already approved for clinical use by US and European regulatory bodies. Appropriate use criteria proposed by an amyloid imaging taskforce convened by the Alzheimer's Association and the Society of Nuclear Medicine and Molecular Imaging recommend restricting use of this technology to the evaluation of patients with mild cognitive impairment or atypical dementia syndromes. While use among asymptomatic individuals is currently viewed as inappropriate due prognostic uncertainty, elevated levels of brain Aβ among asymptomatic individuals may represent preclinical Alzheimer's disease. Amyloid imaging is likewise expected to play a role in the design of clinical trials. Though preliminary results suggest amyloid imaging to possess clinical utility and cost-effectiveness, both domains have yet to be assessed systematically. As the field moves toward adoption of a pro-disclosure stance for amyloid imaging findings, it is imperative that a broad range of stakeholders be involved to ensure the appropriateness of emerging policies and protocols.

Multimodal imaging Gd-nanoparticles functionalized with Pittsburgh compound B or a nanobody for amyloid plaques targeting.

Science.gov (United States)

Pansieri, Jonathan; Plissonneau, Marie; Stransky-Heilkron, Nathalie; Dumoulin, Mireille; Heinrich-Balard, Laurence; Rivory, Pascaline; Morfin, Jean-François; Toth, Eva; Saraiva, Maria Joao; Allémann, Eric; Tillement, Olivier; Forge, Vincent; Lux, François; Marquette, Christel

2017-07-01

Gadolinium-based nanoparticles were functionalized with either the Pittsburgh compound B or a nanobody (B10AP) in order to create multimodal tools for an early diagnosis of amyloidoses. The ability of the functionalized nanoparticles to target amyloid fibrils made of β-amyloid peptide, amylin or Val30Met-mutated transthyretin formed in vitro or from pathological tissues was investigated by a range of spectroscopic and biophysics techniques including fluorescence microscopy. Nanoparticles functionalized by both probes efficiently interacted with the three types of amyloid fibrils, with K D values in 10 micromolar and 10 nanomolar range for, respectively, Pittsburgh compound B and B10AP nanoparticles. Moreover, they allowed the detection of amyloid deposits on pathological tissues. Such functionalized nanoparticles could represent promising flexible and multimodal imaging tools for the early diagnostic of amyloid diseases, in other words, Alzheimer's disease, Type 2 diabetes mellitus and the familial amyloidotic polyneuropathy.

Measurement of amyloid formation by turbidity assay-seeing through the cloud.

Science.gov (United States)

Zhao, Ran; So, Masatomo; Maat, Hendrik; Ray, Nicholas J; Arisaka, Fumio; Goto, Yuji; Carver, John A; Hall, Damien

2016-01-01

Detection of amyloid growth is commonly carried out by measurement of solution turbidity, a low-cost assay procedure based on the intrinsic light scattering properties of the protein aggregate. Here, we review the biophysical chemistry associated with the turbidimetric assay methodology, exploring the reviewed literature using a series of pedagogical kinetic simulations. In turn, these simulations are used to interrogate the literature concerned with in vitro drug screening and the assessment of amyloid aggregation mechanisms.

Stereoselective determination of amino acids in beta-amyloid peptides and senile plaques.

Science.gov (United States)

Thorsén, G; Bergquist, J; Westlind-Danielsson, A; Josefsson, B

2001-06-01

A novel method for the determination of the enantiomeric composition of peptides is presented. In this paper, the focus has been on beta-amyloid peptides from deceased Alzheimer's disease patients. The peptides are hydrolyzed using mineral acid. The free amino acids are derivatized with the chiral reagent (+)- or (-)-1-(9-anthryl)-2-propyl chloroformate and subsequently separated using micellar electrokinetic chromatography (MEKC) and detected using laser-induced fluorescence (LIF) detection. The high separation efficiency of the MEKC-LIF system, yielding approximately 1 million theoretical plates/m for most amino acids, facilitates the simultaneous chiral determination of nine amino acids. The samples that have been analyzed were standard 1-40 beta-amyloid peptides, in vitro precipitated beta-amyloid fibrils, and human senile plaque samples.

Benzofuranone derivatives as effective small molecules related to insulin amyloid fibrillation: a structure-function study

DEFF Research Database (Denmark)

Rabiee, Atefeh; Ebrahim-Habibi, Azadeh; Navidpour, Latifeh

2011-01-01

amyloid fibrils under slightly destabilizing conditions in vitro and may form amyloid structures when subcutaneously injected into patients with diabetes. There is a great deal of interest in developing novel small molecule inhibitors of amyloidogenic processes, as potential therapeutic compounds...... of the five tested compounds was observed to enhance amyloid fibrillation, while the others inhibited the process when used at micromolar concentrations, which could make them interesting potential lead compounds for the design of therapeutic antiamyloidogenic compounds....

Amyloid-β positron emission tomography imaging probes

DEFF Research Database (Denmark)

Kepe, Vladimir; Moghbel, Mateen C; Långström, Bengt

2013-01-01

, a number of factors appear to preclude these probes from clinical utilization. As the available "amyloid specific" positron emission tomography imaging probes have failed to demonstrate diagnostic value and have shown limited utility for monitoring therapeutic interventions in humans, a debate...

Inhalable Andrographolide-β-cyclodextrin Inclusion Complexes for Treatment of Staphylococcus aureus Pneumonia by Regulating Immune Responses.

Science.gov (United States)

Zhang, Tongtong; Zhu, Lifei; Li, Miao; Hu, Yuzhen; Zhang, Erfeng; Jiang, Qingcheng; Han, Guang; Jin, Yiguang

2017-05-01

Bacterial pneumonia is a serious disease with high mortality if no appropriate and immediate therapy is available. Andrographolide (AG) is an anti-inflammatory agent extracted from a traditional Chinese herb andrographis paniculata. Oral AG tablets and pills are clinically applied for treatment of upper respiratory tract infections. However, the low solubility and bioavailability of AG lead to high doses and long-term therapy. Here we developed an andrographolide-β-cyclodextrin inclusion complex (AG-β-CD) for inhalation therapy of Staphylococcus aureus pneumonia. AG-β-CD was identified with X-ray diffraction and FT-IR. Surprisingly, both AG-β-CD and AG showed little in vitro anti-S. aureus activity. However, pulmonary delivery of AG, AG-β-CD, or penicillin had significant anti-S. aureus pneumonia effects. Leukocytes, neutrophils, white blood cells, total proteins, TNF-α, IL-6, NF-κB p65 expression, and bacterial colonies in the bronchoalveolar lavage fluids were detected. Pulmonary delivery of AG and AG-β-CD led to bacterial inhibition and inflammation alleviation by regulating immune responses, while penicillin only killed bacteria without significant immune regulation. Moreover, the antipneumonia activity of AG-β-CD was much higher than that of AG, probably resulting from locally accelerated AG dissolution due to β-CD inclusion. The aerodynamic diameter of AG-β-CD powders was 2.03 μm, suitable for pulmonary delivery. Inhalable AG-β-CD is a promising antibacterial and anti-inflammatory medicine for the treatment of S. aureus pneumonia by regulating immune responses, and the effect is enhanced by β-CD inclusion. AG and its formulations might be potent weapons against the resistant bacterial pneumonia due to their specific mechanism in the future.

The Common Inhalational Anesthetic Sevoflurane Induces Apoptosis and Increases β-Amyloid Protein Levels

Science.gov (United States)

Dong, Yuanlin; Zhang, Guohua; Zhang, Bin; Moir, Robert D.; Xia, Weiming; Marcantonio, Edward R.; Culley, Deborah J.; Crosby, Gregory; Tanzi, Rudolph E.; Xie, Zhongcong

2009-01-01

Objective: To assess the effects of sevoflurane, the most commonly used inhalation anesthetic, on apoptosis and β-amyloid protein (Aβ) levels in vitro and in vivo. Subjects: Naive mice, H4 human neuroglioma cells, and H4 human neuroglioma cells stably transfected to express full-length amyloid precursor protein. Interventions: Human H4 neuroglioma cells stably transfected to express full-length amyloid precursor protein were exposed to 4.1% sevoflurane for 6 hours. Mice received 2.5% sevoflurane for 2 hours. Caspase-3 activation, apoptosis, and Aβ levels were assessed. Results: Sevoflurane induced apoptosis and elevated levels of β-site amyloid precursor protein-cleaving enzyme and Aβ in vitro and in vivo. The caspase inhibitor Z-VAD decreased the effects of sevoflurane on apoptosis and Aβ. Sevoflurane-induced caspase-3 activation was attenuated by the γ-secretase inhibitor L-685,458 and was potentiated by Aβ. These results suggest that sevoflurane induces caspase activation which, in turn, enhances β-site amyloid precursor protein–cleaving enzyme and Aβ levels. Increased Aβ levels then induce further rounds of apoptosis. Conclusions: These results suggest that inhalational anesthetic sevoflurane may promote Alzheimer disease neuropathogenesis. If confirmed in human subjects, it may be prudent to caution against the use of sevoflurane as an anesthetic, especially in those suspected of possessing excessive levels of cerebral Aβ. PMID:19433662

PEGylated nanoparticles bind to and alter amyloid-beta peptide conformation

DEFF Research Database (Denmark)

Brambilla, Davide; Verpillot, Romain; Le Droumaguet, Benjamin

2012-01-01

We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs on the int......We have demonstrated that the polyethylene glycol (PEG) corona of long-circulating polymeric nanoparticles (NPs) favors interaction with the amyloid-beta (Aß(1-42)) peptide both in solution and in serum. The influence of PEGylation of poly(alkyl cyanoacrylate) and poly(lactic acid) NPs...

Optimal parameters for near infrared fluorescence imaging of amyloid plaques in Alzheimer's disease mouse models

International Nuclear Information System (INIS)

Raymond, S B; Kumar, A T N; Boas, D A; Bacskai, B J

2009-01-01

Amyloid-β plaques are an Alzheimer's disease biomarker which present unique challenges for near-infrared fluorescence tomography because of size (<50 μm diameter) and distribution. We used high-resolution simulations of fluorescence in a digital Alzheimer's disease mouse model to investigate the optimal fluorophore and imaging parameters for near-infrared fluorescence tomography of amyloid plaques. Fluorescence was simulated for amyloid-targeted probes with emission at 630 and 800 nm, plaque-to-background ratios from 1-1000, amyloid burden from 0-10%, and for transmission and reflection measurement geometries. Fluorophores with high plaque-to-background contrast ratios and 800 nm emission performed significantly better than current amyloid imaging probes. We tested idealized fluorophores in transmission and full-angle tomographic measurement schemes (900 source-detector pairs), with and without anatomical priors. Transmission reconstructions demonstrated strong linear correlation with increasing amyloid burden, but underestimated fluorescence yield and suffered from localization artifacts. Full-angle measurements did not improve upon the transmission reconstruction qualitatively or in semi-quantitative measures of accuracy; anatomical and initial-value priors did improve reconstruction localization and accuracy for both transmission and full-angle schemes. Region-based reconstructions, in which the unknowns were reduced to a few distinct anatomical regions, produced highly accurate yield estimates for cortex, hippocampus and brain regions, even with a reduced number of measurements (144 source-detector pairs).

Heterologous amyloid seeding: revisiting the role of acetylcholinesterase in Alzheimer's disease.

Directory of Open Access Journals (Sweden)

Létitia Jean

2007-07-01

Full Text Available Neurodegenerative diseases associated with abnormal protein folding and ordered aggregation require an initial trigger which may be infectious, inherited, post-inflammatory or idiopathic. Proteolytic cleavage to generate vulnerable precursors, such as amyloid-beta peptide (Abeta production via beta and gamma secretases in Alzheimer's Disease (AD, is one such trigger, but the proteolytic removal of these fragments is also aetiologically important. The levels of Abeta in the central nervous system are regulated by several catabolic proteases, including insulysin (IDE and neprilysin (NEP. The known association of human acetylcholinesterase (hAChE with pathological aggregates in AD together with its ability to increase Abeta fibrilization prompted us to search for proteolytic triggers that could enhance this process. The hAChE C-terminal domain (T40, AChE(575-614 is an exposed amphiphilic alpha-helix involved in enzyme oligomerisation, but it also contains a conformational switch region (CSR with high propensity for conversion to non-native (hidden beta-strand, a property associated with amyloidogenicity. A synthetic peptide (AChE(586-599 encompassing the CSR region shares homology with Abeta and forms beta-sheet amyloid fibrils. We investigated the influence of IDE and NEP proteolysis on the formation and degradation of relevant hAChE beta-sheet species. By combining reverse-phase HPLC and mass spectrometry, we established that the enzyme digestion profiles on T40 versus AChE(586-599, or versus Abeta, differed. Moreover, IDE digestion of T40 triggered the conformational switch from alpha- to beta-structures, resulting in surfactant CSR species that self-assembled into amyloid fibril precursors (oligomers. Crucially, these CSR species significantly increased Abeta fibril formation both by seeding the energetically unfavorable formation of amyloid nuclei and by enhancing the rate of amyloid elongation. Hence, these results may offer an explanation

Quantitative Amyloid Imaging in Autosomal Dominant Alzheimer’s Disease: Results from the DIAN Study Group

Science.gov (United States)

Su, Yi; Blazey, Tyler M.; Owen, Christopher J.; Christensen, Jon J.; Friedrichsen, Karl; Joseph-Mathurin, Nelly; Wang, Qing; Hornbeck, Russ C.; Ances, Beau M.; Snyder, Abraham Z.; Cash, Lisa A.; Koeppe, Robert A.; Klunk, William E.; Galasko, Douglas; Brickman, Adam M.; McDade, Eric; Ringman, John M.; Thompson, Paul M.; Saykin, Andrew J.; Ghetti, Bernardino; Sperling, Reisa A.; Johnson, Keith A.; Salloway, Stephen P.; Schofield, Peter R.; Masters, Colin L.; Villemagne, Victor L.; Fox, Nick C.; Förster, Stefan; Chen, Kewei; Reiman, Eric M.; Xiong, Chengjie; Marcus, Daniel S.; Weiner, Michael W.; Morris, John C.; Bateman, Randall J.; Benzinger, Tammie L. S.

2016-01-01

Amyloid imaging plays an important role in the research and diagnosis of dementing disorders. Substantial variation in quantitative methods to measure brain amyloid burden exists in the field. The aim of this work is to investigate the impact of methodological variations to the quantification of amyloid burden using data from the Dominantly Inherited Alzheimer’s Network (DIAN), an autosomal dominant Alzheimer’s disease population. Cross-sectional and longitudinal [11C]-Pittsburgh Compound B (PiB) PET imaging data from the DIAN study were analyzed. Four candidate reference regions were investigated for estimation of brain amyloid burden. A regional spread function based technique was also investigated for the correction of partial volume effects. Cerebellar cortex, brain-stem, and white matter regions all had stable tracer retention during the course of disease. Partial volume correction consistently improves sensitivity to group differences and longitudinal changes over time. White matter referencing improved statistical power in the detecting longitudinal changes in relative tracer retention; however, the reason for this improvement is unclear and requires further investigation. Full dynamic acquisition and kinetic modeling improved statistical power although it may add cost and time. Several technical variations to amyloid burden quantification were examined in this study. Partial volume correction emerged as the strategy that most consistently improved statistical power for the detection of both longitudinal changes and across-group differences. For the autosomal dominant Alzheimer’s disease population with PiB imaging, utilizing brainstem as a reference region with partial volume correction may be optimal for current interventional trials. Further investigation of technical issues in quantitative amyloid imaging in different study populations using different amyloid imaging tracers is warranted. PMID:27010959

Serum amyloid A and haptoglobin concentrations and liver fat percentage in lactating dairy cows with abomasal displacement.

Science.gov (United States)

Guzelbektes, H; Sen, I; Ok, M; Constable, P D; Boydak, M; Coskun, A

2010-01-01

There has been increased interest in measuring the serum concentration of acute phase reactants such as serum amyloid A [SAA] and haptoglobin [haptoglobin] in periparturient cattle in order to provide a method for detecting the presence of inflammation or bacterial infection. To determine whether [SAA] and [haptoglobin] are increased in cows with displaced abomasum as compared with healthy dairy cows. Fifty-four adult dairy cows in early lactation that had left displaced abomasum (LDA, n = 34), right displaced abomasum or abomasal volvulus (RDA/AV, n = 11), or were healthy on physical examination (control, n = 9). Inflammatory diseases or bacterial infections such as mastitis, metritis, or pneumonia were not clinically apparent in any animal. Jugular venous blood was obtained from all cows and analyzed. Liver samples were obtained by biopsy in cattle with abomasal displacement. [SAA] and [haptoglobin] concentrations were increased in cows with LDA or RDA/AV as compared with healthy controls. Cows with displaced abomasum had mild to moderate hepatic lipidosis, based on liver fat percentages of 9.3 +/- 5.3% (mean +/- SD, LDA) and 10.8 +/- 7.7% (RDA/AV). [SAA] and [haptoglobin] were most strongly associated with liver fat percentage, r(s) = +0.55 (P hepatic lipidosis in cattle with abomasal displacement.

The treatment of bacterial vaginosis in pregnancy with clindamycin to reduce the risk of infection-related preterm birth

DEFF Research Database (Denmark)

Lamont, Ronald F.; Keelan, Jeffrey A.; Larsson, Per G.

2017-01-01

and Gynecology advised against the use of clindamycin for the treatment of bacterial vaginosis in pregnancy to reduce the risk of spontaneous preterm birth based on lack of evidence of efficacy. We believe that the evidence for the use of clindamycin for this indication is robust and that this recommendation...... was reached erroneously on the basis of flawed inclusion criteria: the inclusion of an unpublished study with poorly diagnosed bacterial vaginosis and the exclusion of an important pivotal study on the use of clindamycin in early pregnancy for the prevention of preterm birth. Had these errors been corrected...

[Development of anti-Alzheimer's disease drug based on beta-amyloid hypothesis].

Science.gov (United States)

Sugimoto, Hachiro

2010-04-01

Currently, there are five anti-Alzheimer's disease drugs approved. These are tacrine, donepezil, rivastigmine, galantamine, and memantine. The mechanism of the first four drugs is acetylcholinesterase inhibition, while memantine is an NMDA-receptor antagonist. However, these drugs do not cure Alzheimer's, but are only symptomatic treatments. Therefore, a cure for Alzheimer's disease is truly needed. Alzheimer's disease is a progressive neurodegenerative disease characterized by cognitive deficits. The cause of the disease is not well understood, but research indicates that the aggregation of beta-amyloid is the fundamental cause. This theory suggests that beta-amyloid aggregation causes neurotoxicity. Therefore, development of the next anti-Alzheimer's disease drug is based on the beta-amyloid theory. We are now studying natural products, such as mulberry leaf extracts and curcumin derivatives, as potential cure for Alzheimer's disease. In this report, we describe some data about these natural products and derivatives.

A Binding-Site Barrier Affects Imaging Efficiency of High Affinity Amyloid-Reactive Peptide Radiotracers In Vivo

OpenAIRE

Wall, Jonathan S.; Williams, Angela; Richey, Tina; Stuckey, Alan; Huang, Ying; Wooliver, Craig; Macy, Sallie; Heidel, Eric; Gupta, Neil; Lee, Angela; Rader, Brianna; Martin, Emily B.; Kennel, Stephen J.

2013-01-01

Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selecti...

A routine PET/CT protocol with simple calculations for assessing cardiac amyloid using 18F-Florbetapir

Directory of Open Access Journals (Sweden)

Dustin Ryan Osborne

2015-05-01

Full Text Available Introduction: Cardiac amyloidosis is a rare condition characterized by the deposition of well-structured protein fibrils, proteoglycans, and serum proteins as amyloid. Recent work has shown that it may be possible to use 18F-Florbetapir to image cardiac amyloidosis. Current methods for assessment include invasive biopsy techniques. This work enhances foundational work by Dorbala et al. by developing a routine imaging and analysis protocol using 18F-Florbetapir for cardiac amyloid assessment.Methods: Ten patients, 3 healthy controls and 7 amyloid positive patients, were imaged using 18F-Florbetapir to assess cardiac amyloid burden. Four of the patients also were imaged using 82Rb-Chloride to evaluate possible 18F-Florbetapir retention because of reduced myocardial blood flow. Quantitative methods using modeling, SUVs and SUV ratios were used to define a new streamlined clinical imaging protocol that could be used routinely and provide patient stratification.Results: Quantitative analysis of 18F-Florbetapir cardiac amyloid data were compiled from a 20 minute listmode protocol with data histogrammed into two static images at 0-5 minutes and, 10-15 min or 15-20 min. Data analysis indicated the use of SUVs or ratios of SUVs calculated from regions draw in the septal wall were adequate in identification of all healthy controls from amyloid positive patients in this small cohort. Additionally, we found that it may be possible to use this method to differentiate patients suffering from AL vs. TTR amyloid.Conclusions: This work builds on the seminal work by Dorbala et Al. by describing a short 18F-Florbetapir imaging protocol that is suitable for routine clinical use and uses a simple method for quantitative analysis of cardiac amyloid disease.

Investigation of the inhibitory effects of TiO{sub 2} on the β-amyloid peptide aggregation

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Mukhtar H., E-mail: ahmed-m@email.ulster.ac.uk [School of Chemical Science, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); Nanotechnology Integrated Bioengineering Centre, University of Ulster, Jordanstown, BT37 0QB Belfast (United Kingdom); Byrne, John A. [Nanotechnology Integrated Bioengineering Centre, University of Ulster, Jordanstown, BT37 0QB Belfast (United Kingdom); Keyes, Tia E. [School of Chemical Science, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland)

2014-06-01

TiO{sub 2} thin films are of great interest as biocompatible coatings and also as photocatalytic self-cleaning and antimicrobial coatings. In this work we used β-amyloid as a model for infectious protein to investigate the attachment and photocatalytic degradation. TiO{sub 2} films were prepared on stainless steel substrates using magnetron sputtering. The films were characterised before and after exposure to β-amyloid (1–42), using XRD, Raman spectroscopy, XPS and AFM. The TiO{sub 2} film was mostly composed of the anatase phase with a relatively high surface roughness. The presence of Raman peaks at 1668 cm{sup −1} and 1263 cm{sup −1}, with the XPS spectral feature for nitrogen at 400 eV, confirmed the adsorption of amyloid on surface. Following exposure of the β-amyloid contaminated TiO{sub 2} to UV-B irradiation a slight shift of amide modes was observed. Furthermore, the amide I spectra show an overall decrease in α-helix content with presence of a minor peak around 1591 cm{sup −1}, which is related to tryptophanyl and tyrosinyl radicals, which can lead to conformational change of β-amyloid. The C1s band at 292.2 eV suggests the formation of free carboxylic acid. The loss in the crucial structure of β-amyloid leads to reduce the fibril formation, thought to be induced through a photocatalytic process. - Highlights: • TiO{sub 2} thin films synthesised and characterised • Absorption study using β-amyloid (1–42) • Investigation of peptide configuration via Raman, AFM and XPS spectroscopies • β-Amyloid was subsequently degraded by photocatalytic activity of TiO{sub 2}.

Imaging Amyloid Tissues Stained with Luminescent Conjugated Oligothiophenes by Hyperspectral Confocal Microscopy and Fluorescence Lifetime Imaging.

Science.gov (United States)

Nyström, Sofie; Bäck, Marcus; Nilsson, K Peter R; Hammarström, Per

2017-10-20

Proteins that deposit as amyloid in tissues throughout the body can be the cause or consequence of a large number of diseases. Among these we find neurodegenerative diseases such as Alzheimer's and Parkinson's disease afflicting primarily the central nervous system, and systemic amyloidosis where serum amyloid A, transthyretin and IgG light chains deposit as amyloid in liver, carpal tunnel, spleen, kidney, heart, and other peripheral tissues. Amyloid has been known and studied for more than a century, often using amyloid specific dyes such as Congo red and Thioflavin T (ThT) or Thioflavin (ThS). In this paper, we present heptamer-formyl thiophene acetic acid (hFTAA) as an example of recently developed complements to these dyes called luminescent conjugated oligothiophenes (LCOs). hFTAA is easy to use and is compatible with co-staining in immunofluorescence or with other cellular markers. Extensive research has proven that hFTAA detects a wider range of disease associated protein aggregates than conventional amyloid dyes. In addition, hFTAA can also be applied for optical assignment of distinct aggregated morphotypes to allow studies of amyloid fibril polymorphism. While the imaging methodology applied is optional, we here demonstrate hyperspectral imaging (HIS), laser scanning confocal microscopy and fluorescence lifetime imaging (FLIM). These examples show some of the imaging techniques where LCOs can be used as tools to gain more detailed knowledge of the formation and structural properties of amyloids. An important limitation to the technique is, as for all conventional optical microscopy techniques, the requirement for microscopic size of aggregates to allow detection. Furthermore, the aggregate should comprise a repetitive β-sheet structure to allow for hFTAA binding. Excessive fixation and/or epitope exposure that modify the aggregate structure or conformation can render poor hFTAA binding and hence pose limitations to accurate imaging.

Calcium signaling and amyloid toxicity in Alzheimer disease.

Science.gov (United States)

Demuro, Angelo; Parker, Ian; Stutzmann, Grace E

2010-04-23

Intracellular Ca(2+) signaling is fundamental to neuronal physiology and viability. Because of its ubiquitous roles, disruptions in Ca(2+) homeostasis are implicated in diverse disease processes and have become a major focus of study in multifactorial neurodegenerative diseases such as Alzheimer disease (AD). A hallmark of AD is the excessive production of beta-amyloid (Abeta) and its massive accumulation in amyloid plaques. In this minireview, we highlight the pathogenic interactions between altered cellular Ca(2+) signaling and Abeta in its different aggregation states and how these elements coalesce to alter the course of the neurodegenerative disease. Ca(2+) and Abeta intersect at several functional levels and temporal stages of AD, thereby altering neurotransmitter receptor properties, disrupting membrane integrity, and initiating apoptotic signaling cascades. Notably, there are reciprocal interactions between Ca(2+) pathways and amyloid pathology; altered Ca(2+) signaling accelerates Abeta formation, whereas Abeta peptides, particularly in soluble oligomeric forms, induce Ca(2+) disruptions. A degenerative feed-forward cycle of toxic Abeta generation and Ca(2+) perturbations results, which in turn can spin off to accelerate more global neuropathological cascades, ultimately leading to synaptic breakdown, cell death, and devastating memory loss. Although no cause or cure is currently known, targeting Ca(2+) dyshomeostasis as an underlying and integral component of AD pathology may result in novel and effective treatments for AD.

AMYPdb: A database dedicated to amyloid precursor proteins

Directory of Open Access Journals (Sweden)

Delamarche Christian

2008-06-01

Full Text Available Abstract Background Misfolding and aggregation of proteins into ordered fibrillar structures is associated with a number of severe pathologies, including Alzheimer's disease, prion diseases, and type II diabetes. The rapid accumulation of knowledge about the sequences and structures of these proteins allows using of in silico methods to investigate the molecular mechanisms of their abnormal conformational changes and assembly. However, such an approach requires the collection of accurate data, which are inconveniently dispersed among several generalist databases. Results We therefore created a free online knowledge database (AMYPdb dedicated to amyloid precursor proteins and we have performed large scale sequence analysis of the included data. Currently, AMYPdb integrates data on 31 families, including 1,705 proteins from nearly 600 organisms. It displays links to more than 2,300 bibliographic references and 1,200 3D-structures. A Wiki system is available to insert data into the database, providing a sharing and collaboration environment. We generated and analyzed 3,621 amino acid sequence patterns, reporting highly specific patterns for each amyloid family, along with patterns likely to be involved in protein misfolding and aggregation. Conclusion AMYPdb is a comprehensive online database aiming at the centralization of bioinformatic data regarding all amyloid proteins and their precursors. Our sequence pattern discovery and analysis approach unveiled protein regions of significant interest. AMYPdb is freely accessible 1.

Cognitive and functional patterns of nondemented subjects with equivocal visual amyloid PET findings

International Nuclear Information System (INIS)

Payoux, P.; Delrieu, J.; Gallini, A.; Cantet, C.; Voisin, T.; Gillette-Guyonnet, S.; Vellas, B.; Adel, D.; Salabert, A.S.; Hitzel, A.; Tafani, M.; Verbizier, D. de; Darcourt, J.; Fernandez, P.; Monteil, J.; Carrie, I.; Pontecorvo, M.; Andrieu, S.

2015-01-01

Despite good to excellent inter-reader agreement in the evaluation of amyloid load on PET scans in subjects with Alzheimer's disease, some equivocal findings have been reported in the literature. We aimed to describe the clinical characteristics of subjects with equivocal PET images. Nondemented subjects aged 70 years or more were enrolled from the MAPT trial. Cognitive and functional assessments were conducted at baseline, at 6 months, and annually for 3 years. During the follow-up period, 271 subjects had 18 F-AV45 PET scans. Images were visually assessed by three observers and classified as positive, negative or equivocal (if one observer disagreed). After debate, equivocal images were reclassified as positive (EP+) or negative (EP-). Scans were also classified by semiautomated quantitative analysis using mean amyloid uptake of cortical regions. We evaluated agreement among the observers, and between visual and quantitative assessments using kappa coefficients, and compared the clinical characteristics of the subjects according to their PET results. In 158 subjects (58.30 %) the PET scan was negative for amyloid, in 77 (28.41 %) the scan was positive and in 36 (13.28 %) the scan was equivocal. Agreement among the three observers was excellent (kappa 0.80). Subjects with equivocal images were more frequently men (58 % vs. 37 %) and exhibited intermediate scores on cognitive and functional scales between those of subjects with positive and negative scans. Amyloid load differed between the EP- and negative groups and between the EP+ and positive groups after reclassification. Equivocal amyloid PET images could represent a neuroimaging entity with intermediate amyloid load but without a specific neuropsychological pattern. Clinical follow-up to assess cognitive evolution in subjects with equivocal scans is needed. (orig.)

Cognitive and functional patterns of nondemented subjects with equivocal visual amyloid PET findings

Energy Technology Data Exchange (ETDEWEB)

Payoux, P. [Purpan University Hospital, Department of Nuclear Medicine, CHU Toulouse, Toulouse (France); Inserm, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Universite de Toulouse, UPS, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); INSERM U825, CHU Purpan, Toulouse Cedex (France); Delrieu, J. [Purpan University Hospital, Gerontopole, Department of Geriatrics, CHU Toulouse, Toulouse (France); INSERM UMR 1027, Toulouse (France); Gallini, A.; Cantet, C.; Voisin, T.; Gillette-Guyonnet, S.; Vellas, B. [Universite de Toulouse, UPS, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Purpan University Hospital, Gerontopole, Department of Geriatrics, CHU Toulouse, Toulouse (France); INSERM UMR 1027, Toulouse (France); Adel, D.; Salabert, A.S. [Inserm, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Hitzel, A. [Purpan University Hospital, Department of Nuclear Medicine, CHU Toulouse, Toulouse (France); Universite de Toulouse, UPS, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Tafani, M. [Purpan University Hospital, Department of Nuclear Medicine, CHU Toulouse, Toulouse (France); Inserm, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Universite de Toulouse, UPS, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Verbizier, D. de [Montpellier University Hospital, Department of Nuclear Medicine, Montpellier (France); Darcourt, J. [Centre Antoine Lacassagne, Nuclear Medicine Department, Nice (France); University of Nice-Sophia Antipolis, Nice (France); Fernandez, P. [Pellegrin University Hospital Bordeaux, Nuclear Medicine Department, Bordeaux (France); University Bordeaux II, CNRS UMR 5287 - INCIA, Victor Segalen, Bordeaux (France); Monteil, J. [University Hospital, Department of Nuclear Medicine, Limoges (France); University of Limoges, Limoges (France); Carrie, I. [Purpan University Hospital, Gerontopole, Department of Geriatrics, CHU Toulouse, Toulouse (France); Pontecorvo, M. [Avid Radiopharmaceuticals, Philadelphia, PA (United States); Andrieu, S. [Universite de Toulouse, UPS, Imagerie Cerebrale et Handicaps Neurologiques, UMR 825, Toulouse (France); Purpan University Hospital, Gerontopole, Department of Geriatrics, CHU Toulouse, Toulouse (France); INSERM UMR 1027, Toulouse (France); CHU Toulouse, Department of Epidemiology and Public Health, Toulouse (France)

2015-08-15

Despite good to excellent inter-reader agreement in the evaluation of amyloid load on PET scans in subjects with Alzheimer's disease, some equivocal findings have been reported in the literature. We aimed to describe the clinical characteristics of subjects with equivocal PET images. Nondemented subjects aged 70 years or more were enrolled from the MAPT trial. Cognitive and functional assessments were conducted at baseline, at 6 months, and annually for 3 years. During the follow-up period, 271 subjects had {sup 18}F-AV45 PET scans. Images were visually assessed by three observers and classified as positive, negative or equivocal (if one observer disagreed). After debate, equivocal images were reclassified as positive (EP+) or negative (EP-). Scans were also classified by semiautomated quantitative analysis using mean amyloid uptake of cortical regions. We evaluated agreement among the observers, and between visual and quantitative assessments using kappa coefficients, and compared the clinical characteristics of the subjects according to their PET results. In 158 subjects (58.30 %) the PET scan was negative for amyloid, in 77 (28.41 %) the scan was positive and in 36 (13.28 %) the scan was equivocal. Agreement among the three observers was excellent (kappa 0.80). Subjects with equivocal images were more frequently men (58 % vs. 37 %) and exhibited intermediate scores on cognitive and functional scales between those of subjects with positive and negative scans. Amyloid load differed between the EP- and negative groups and between the EP+ and positive groups after reclassification. Equivocal amyloid PET images could represent a neuroimaging entity with intermediate amyloid load but without a specific neuropsychological pattern. Clinical follow-up to assess cognitive evolution in subjects with equivocal scans is needed. (orig.)

The Role of Functional Amyloids in Multicellular Growth and Development of Gram-Positive Bacteria

NARCIS (Netherlands)

Dragoš, A.; Kovács, Á.T.; Claessen, D.

2017-01-01

Amyloid fibrils play pivotal roles in all domains of life. In bacteria, these fibrillar structures are often part of an extracellular matrix that surrounds the producing organism and thereby provides protection to harsh environmental conditions. Here, we discuss the role of amyloid fibrils in the

The Role of Functional Amyloids in Multicellular Growth and Development of Gram-Positive Bacteria

DEFF Research Database (Denmark)

Dragoš, Anna; Kovács, Ákos T.; Claessen, Dennis

2017-01-01

Amyloid fibrils play pivotal roles in all domains of life. In bacteria, these fibrillar structures are often part of an extracellular matrix that surrounds the producing organism and thereby provides protection to harsh environmental conditions. Here, we discuss the role of amyloid fibrils...... in the two distant Gram-positive bacteria, Streptomyces coelicolor and Bacillus subtilis. We describe how amyloid fibrils contribute to a multitude of developmental processes in each of these systems, including multicellular growth and community development. Despite this variety of tasks, we know...... surprisingly little about how their assembly is organized to fulfill all these roles....

A comparison of serum amyloid A (SAA) synthesis with that of the pentraxins: Serum amyloid P (SAP) and C-reactive protein (CRP)

International Nuclear Information System (INIS)

Tatsuta, E.; Shirahama, T.; Sipe, J.D.; Skinner, M.

1986-01-01

Serum amyloid A (SAA) and serum amyloid P (SAP) were detected in cultures of hepatocytes which had been isolated from normal CBA/J mice by the collagenase perfusion technique. SAP production in 24 h cultures was more resistant than SAA and total protein synthesis to inhibition by actinomycin D, but was more sensitive to inhibition by 48 h. However, the production of SAP was more sensitive to cycloheximide than SAA and total protein throughout the 48 hr incubation period. SAP and SAA levels in the culture media were suppressed by treatment of liver cells with 10 -6 M of colchicine for 48 h. Inhibition of SAP production by colchicine was the same regardless of culture condition, but the effect of colchicine on SAA synthesis varied according to the presence of serum of monokine. These observations also support the concept that the two amyloid proteins are produced under different regulatory mechanisms. When C-reactive protein (CRP) was not detected in the sera of patients with severe chronic liver diseases, the SAA levels were very low. When CRP was detected, SAA values were within the normal range. Thus, in order to produce SAA, liver cells in these patients not only were viable but also maintained their specialized function

APP processing and the APP-KPI domain involvement in the amyloid cascade.

Science.gov (United States)

Menéndez-González, M; Pérez-Pinera, P; Martínez-Rivera, M; Calatayud, M T; Blázquez Menes, B

2005-01-01

Alternative APP mRNA splicing can generate isoforms of APP containing a Kunitz protease inhibitor (KPI) domain. KPI is one of the main serine protease inhibitors. Protein and mRNA KPI(+)APP levels are elevated in Alzheimer's disease (AD) brain and are associated with increased amyloid beta deposition. In the last years increasing evidence on multiple points in the amyloid cascade where KPI(+)APP is involved has been accumulated, admitting an outstanding position in the pathogenesis of AD to the KPI domain. This review focuses on the APP processing, the molecular activity of KPI and its physiological and pathological roles and the KPI involvement in the amyloid cascade through the nerve growth factor, the lipoprotein receptor-related protein, the tumor necrosis factor-alpha converting enzyme and the Notch1 protein.

Inhibitory Activities of Antioxidant Flavonoids from Tamarix gallica on Amyloid Aggregation Related to Alzheimer's and Type 2 Diabetes Diseases.

Science.gov (United States)

Ben Hmidene, Asma; Hanaki, Mizuho; Murakami, Kazuma; Irie, Kazuhiro; Isoda, Hiroko; Shigemori, Hideyuki

2017-01-01

The prevention of amyloid aggregation is promising for the treatment of age-related diseases such as Alzheimer's (AD) and type 2 diabetes (T2D). Ten antioxidant flavonoids isolated from the medicinal halophyte Tamarix gallica were tested for their amyloid aggregation inhibition potential. Glucuronosylated flavonoids show relatively strong inhibitory activity of Amyloid β (Aβ) and human islet amyloid polypeptide (hIAPP) aggregation compared to their aglycone analogs. Structure-activity relationship of the flavonoids suggests that the catechol moiety is important for amyloid aggregation inhibition, while the methylation of the carboxyl group in the glucuronide moiety and of the hydroxyl group in the aglycone flavonoids decreased it.

Exploring the early steps of aggregation of amyloid-forming peptide KFFE

International Nuclear Information System (INIS)

Wei Guanghong; Mousseau, Normand; Derreumaux, Philippe

2004-01-01

It has been shown recently that even a tetrapeptide can form amyloid fibrils sharing all the characteristics of amyloid fibrils built from large proteins. Recent experimental studies also suggest that the toxicity observed in several neurodegenerative diseases, such as Alzheimer's disease and Creutzfeldt-Jakob disease, is not only related to the mature fibrils themselves, but also to the soluble oligomers formed early in the process of fibrillogenesis. This raises the interest in studying the early steps of the aggregation process. Although fibril formation follows the nucleation-condensation process, characterized by the presence of lag phase, the exact pathways remain to be determined. In this study, we used the activation-relaxation technique and a generic energy model to explore the process of self-assembly and the structures of the resulting aggregates of eight KFFE peptides. Our simulations show, starting from different states with a preformed antiparallel dimer, that eight chains can self-assemble to adopt, with various orientations, four possible distant oligomeric well-aligned structures of similar energy. Two of these structures show a double-layer β-sheet organization, in agreement with the structure of amyloid fibrils as observed by x-ray diffraction; another two are mixtures of dimers and trimers. Our results also suggest that octamers are likely to be below the critical size for nucleation of amyloid fibrils for small peptides

Exploring the early steps of aggregation of amyloid-forming peptide KFFE

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Wei Guanghong [Departement de Physique and Regroupement Quebecois sur les Materiaux de Pointe, Universite de Montreal, CP 6128, succursale centre-ville, Montreal, QC, H3C 3J7 (Canada); Mousseau, Normand [Departement de Physique and Regroupement Quebecois sur les Materiaux de Pointe, Universite de Montreal, CP 6128, succursale centre-ville, Montreal, QC, H3C 3J7 (Canada); Derreumaux, Philippe [Laboratoire de Biochimie, Theorique, UPR 9080 CNRS, IBPC, Universite Paris 7 Denis-Diderot, 13 rue Pierre et Marie Curie, 75005 Paris (France)

2004-11-10

It has been shown recently that even a tetrapeptide can form amyloid fibrils sharing all the characteristics of amyloid fibrils built from large proteins. Recent experimental studies also suggest that the toxicity observed in several neurodegenerative diseases, such as Alzheimer's disease and Creutzfeldt-Jakob disease, is not only related to the mature fibrils themselves, but also to the soluble oligomers formed early in the process of fibrillogenesis. This raises the interest in studying the early steps of the aggregation process. Although fibril formation follows the nucleation-condensation process, characterized by the presence of lag phase, the exact pathways remain to be determined. In this study, we used the activation-relaxation technique and a generic energy model to explore the process of self-assembly and the structures of the resulting aggregates of eight KFFE peptides. Our simulations show, starting from different states with a preformed antiparallel dimer, that eight chains can self-assemble to adopt, with various orientations, four possible distant oligomeric well-aligned structures of similar energy. Two of these structures show a double-layer {beta}-sheet organization, in agreement with the structure of amyloid fibrils as observed by x-ray diffraction; another two are mixtures of dimers and trimers. Our results also suggest that octamers are likely to be below the critical size for nucleation of amyloid fibrils for small peptides.

Microglia kill amyloid-beta1-42 damaged neurons by a CD14-dependent process

NARCIS (Netherlands)

Bate, Clive; Veerhuis, Robert; Eikelenboom, Piet; Williams, Alun

2004-01-01

Activated microglia are closely associated with neuronal damage in Alzheimer's disease. In the present study, neurons exposed to low concentrations of amyloid-beta1-42, a toxic fragment of the amyloid-beta protein, were killed by microglia in a process that required cell-cell contact. Pre-treating

Cerebral Amyloid Angiopathy-Related Inflammation: Report of a Case with Very Difficult Therapeutic Management

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Francesca Crosta

2015-01-01

Full Text Available Background. Cerebral amyloid angiopathy-related inflammation (CAA-ri results from autoimmune response to beta-amyloid deposits in cerebral vessels. Its clinical course and complications have seldom been described in literature. Case Report. In a patient presenting with delirium and left hemiparesis the diagnosis of CAA-ri was supported by the finding of elevated anti-amyloid autoantibodies in the cerebrospinal fluid (CSF. Steroid therapy produced significant improvements in clinical and investigational assessments, but after two months, it caused Acute Respiratory Distress Syndrome. After steroid therapy discontinuation the patient presented a rapidly progressive dementia, Guillain-Barré syndrome, new cerebral ischemic lesions, and thrombosis of the right cephalic and subclavian veins that were treated with subcutaneous heparin. After a week the patient died because of brain hemorrhage. Conclusion. This case suggests caution in steroid therapy discontinuation and antithrombotic therapy administration in patients with CAA-ri. The CSF search of anti-amyloid autoantibodies could be helpful to support the diagnosis.

Development of a Standardized Approach to Disclosing Amyloid Imaging Research Results in Mild Cognitive Impairment.

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Lingler, Jennifer H; Butters, Meryl A; Gentry, Amanda L; Hu, Lu; Hunsaker, Amanda E; Klunk, William E; Mattos, Meghan K; Parker, Lisa A; Roberts, J Scott; Schulz, Richard

2016-03-08

The increased use of PET amyloid imaging in clinical research has sparked numerous concerns about whether and how to return such research test results to study participants. Chief among these is the question of how best to disclose amyloid imaging research results to individuals who have cognitive symptoms that could impede comprehension of the information conveyed. We systematically developed and evaluated informational materials for use in pre-test counseling and post-test disclosures of amyloid imaging research results in mild cognitive impairment (MCI). Using simulated sessions, persons with MCI and their family care partners (N = 10 dyads) received fictitious but realistic information regarding brain amyloid status, followed by an explanation of how results impact Alzheimer's disease risk. Satisfaction surveys, comprehension assessments, and focus group data were analyzed to evaluate the materials developed. The majority of persons with MCI and their care partners comprehended and were highly satisfied with the information presented. Focus group data reinforced findings of high satisfaction and included 6 recommendations for practice: 1) offer pre-test counseling, 2) use clear graphics, 3) review participants' own brain images during disclosures, 4) offer take-home materials, 5) call participants post-disclosure to address emerging questions, and 6) communicate seamlessly with primary care providers. Further analysis of focus group data revealed that participants understood the limitations of amyloid imaging, but nevertheless viewed the prospect of learning one's amyloid status as valuable and empowering.

Development and characterization of a TAPIR-like mouse monoclonal antibody to amyloid-beta.

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Wang, Jun; Hara, Hideo; Makifuchi, Takao; Tabira, Takeshi

2008-06-01

Tissue amyloid plaque immuno-reactive (TAPIR) antibody was better related to the effect of immunotherapy in Alzheimer's disease (AD) than ELISA antibody. Here we used a hybridoma technique to develop a TAPIR-like anti-human amyloid-beta (Abeta) mouse monoclonal antibody. The obtained monoclonal antibody, 3.4A10, was an IgG2b isotype and recognized N-terminal portion of Abeta1-42 without binding denatured or native amyloid-beta protein precursor. It had higher affinity to Abeta1-42 than to Abeta1-40 by Biacore affinity analysis and stained preferably the peripheral part of senile plaques and recognized the plaque core less than 4G8. It inhibited the Abeta1-42 fibril formation as well as degraded pre-aggregated Abeta1-42 peptide in a thioflavin T fluorescence spectrophotometry assay. The in vivo studies showed that 3.4A10 treatment decreased amyloid burden compared to the control group and significantly reduced Abeta42 levels rather than Abeta40 levels in brain lysates as well as the Abeta*56 oligomer (12mer) in TBS fraction of the brain lysates. 3.4A10 entered brain and decorated some plaques, which is surrounded by more Iba1-positive microglia. 3.4A10 therapy did not induce lymphocytic infiltration and obvious increase in microhemorrhage. We conclude that 3.4A10 is a TAPIR-like anti-human amyloid monoclonal antibody, and has a potential of therapeutic application for AD.

High plasma levels of islet amyloid polypeptide in young with new-onset of type 1 diabetes mellitus.

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Johan F Paulsson

Full Text Available AIMS/HYPOTHESIS: Islet amyloid polypeptide (IAPP is a beta cell hormone secreted together with insulin upon glucose stimulation. IAPP participates in normal glucose regulation, but IAPP is also known for its ability to misfold and form islet amyloid. Amyloid fibrils form through smaller cell toxic intermediates and deposited amyloid disrupts normal islet architecture. Even though IAPP and amyloid formation are much discussed in type 2 diabetes, our aim was to study the significance of IAPP in type 1 diabetes. RESULTS: Plasma IAPP levels in children and adolescents with newly diagnosed type 1 diabetes (n = 224 were analysed and concentrations exceeding 100 pmol/L (127.2-888.7 pmol/L were found in 11% (25/224. The IAPP increase did not correlate with C-peptide levels. CONCLUSIONS/INTERPRETATION: Plasma levels of IAPP and insulin deviate in a subpopulation of young with newly-diagnosed type 1 diabetes. The determined elevated levels of IAPP might increase the risk for IAPP misfolding and formation of cell toxic amyloid in beta cells. This finding add IAPP-aggregation to the list over putative pathological factors causing type 1 diabetes.

Mapping local structural perturbations in the native state of stefin B (cystatin B under amyloid forming conditions

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Robert eParamore

2012-10-01

Full Text Available Unlike a number of amyloid-forming proteins, stefins, in particular stefin B (cystatin B form amyloids under conditions where the native state predominates. In order to trigger oligomerization processes, the stability of the protein needs to be compromised, favoring structural re-arrangement however, accelerating fibril formation is not a simple function of protein stability. We report here on how optimal conditions for amyloid formation lead to the destabilization of dimeric and tetrameric states of the protein in favor of the monomer. Small, highly localized structural changes can be mapped out that allow us to visualize directly areas of the protein which eventually become responsible for triggering amyloid formation. These regions of the protein overlap with the Cu (II-binding sites which we identify here for the first time. We hypothesize that in vivo modulators of amyloid formation may act similarly to painstakingly optimized solvent conditions developed in vitro. We discuss these data in the light of current structural models of stefin B amyloid fibrils based on H-exchange data, where the detachment of the helical part and the extension of loops were observed.

alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

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de Fiebre, Nancyellen C; de Fiebre, Christopher M

2005-01-03

The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

Disease Transmission by Misfolded Prion-Protein Isoforms, Prion-Like Amyloids, Functional Amyloids and the Central Dogma.

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Daus, Martin L

2016-01-04

In 1982, the term "prions" (proteinaceous infectious particles) was coined to specify a new principle of infection. A misfolded isoform of a cellular protein has been described as the causative agent of a fatal neurodegenerative disease. At the beginning of prion research scientists assumed that the infectious agent causing transmissible spongiform encephalopathy (TSE) was a virus, but some unconventional properties of these pathogens were difficult to bring in line with the prevailing viral model. The discovery that prions (obviously devoid of any coding nucleic acid) can store and transmit information similarly to DNA was initially even denoted as being "heretical" but is nowadays mainly accepted by the scientific community. This review describes, from a historical point of view, how the "protein-only hypothesis" expands the Central Dogma. Definition of both, the prion principle and the Central Dogma, have been essential steps to understand information storage and transfer within and among cells and organisms. Furthermore, the current understanding of the infectivity of prion-proteins after misfolding is summarized succinctly. Finally, prion-like amyloids and functional amyloids, as found in yeast and bacteria, will be discussed.

Disease Transmission by Misfolded Prion-Protein Isoforms, Prion-Like Amyloids, Functional Amyloids and the Central Dogma

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Martin L. Daus

2016-01-01

Full Text Available In 1982, the term “prions” (proteinaceous infectious particles was coined to specify a new principle of infection. A misfolded isoform of a cellular protein has been described as the causative agent of a fatal neurodegenerative disease. At the beginning of prion research scientists assumed that the infectious agent causing transmissible spongiform encephalopathy (TSE was a virus, but some unconventional properties of these pathogens were difficult to bring in line with the prevailing viral model. The discovery that prions (obviously devoid of any coding nucleic acid can store and transmit information similarly to DNA was initially even denoted as being “heretical” but is nowadays mainly accepted by the scientific community. This review describes, from a historical point of view, how the “protein-only hypothesis” expands the Central Dogma. Definition of both, the prion principle and the Central Dogma, have been essential steps to understand information storage and transfer within and among cells and organisms. Furthermore, the current understanding of the infectivity of prion-proteins after misfolding is summarized succinctly. Finally, prion-like amyloids and functional amyloids, as found in yeast and bacteria, will be discussed.

Advances toward multifunctional cholinesterase and β-amyloid aggregation inhibitors.

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Panek, Dawid; Wichur, Tomasz; Godyń, Justyna; Pasieka, Anna; Malawska, Barbara

2017-10-01

The emergence of a multitarget design approach in the development of new potential anti-Alzheimer's disease agents has resulted in the discovery of many multifunctional compounds focusing on various targets. Among them the largest group comprises inhibitors of both cholinesterases, with additional anti-β-amyloid aggregation activity. This review describes recent advances in this research area and presents the most interesting compounds reported over a 2-year span (2015-2016). The majority of hybrids possess heterodimeric structures obtained by linking structurally active fragments interacting with different targets. Multipotent cholinesterase inhibitors with β-amyloid antiaggregating activity may additionally possess antioxidative, neuroprotective or metal-chelating properties or less common features such as anti-β-secretase or τ-antiaggregation activity.

Role of the disaggregase ClpB in processing of proteins aggregated as inclusion bodies.

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Zblewska, Kamila; Krajewska, Joanna; Zolkiewski, Michal; Kędzierska-Mieszkowska, Sabina

2014-08-01

Overproduction of heterologous proteins in bacterial systems often results in the formation of insoluble inclusion bodies (IBs), which is a major impediment in biochemical research and biotechnology. In principle, the activity of molecular chaperones could be employed to gain control over the IB formation and to improve the recombinant protein yields, but the potential of each of the major bacterial chaperones (DnaK/J, GroEL/ES, and ClpB) to process IBs has not been fully established yet. We investigated the formation of inclusion bodies (IBs) of two aggregation-prone proteins, VP1LAC and VP1GFP, overproduced in Escherichiacoli in the presence and absence of the chaperone ClpB. We found that both ClpB isoforms, ClpB95 and ClpB80 accumulated in E. coli cells during the production of IBs. The amount of IB proteins increased in the absence of ClpB. ClpB supported the resolubilization and reactivation of the aggregated VP1LAC and VP1GFP in E. coli cells. The IB disaggregation was optimal in the presence of both ClpB95 and ClpB80. Our results indicate an essential role of ClpB in controlling protein aggregation and inclusion body formation in bacteria. Copyright © 2014 Elsevier Inc. All rights reserved.

Contact between the β1 and β2 Segments of α-Synuclein that Inhibits Amyloid Formation.

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Shaykhalishahi, Hamed; Gauhar, Aziz; Wördehoff, Michael M; Grüning, Clara S R; Klein, Antonia N; Bannach, Oliver; Stoldt, Matthias; Willbold, Dieter; Härd, Torleif; Hoyer, Wolfgang

2015-07-20

Conversion of the intrinsically disordered protein α-synuclein (α-syn) into amyloid aggregates is a key process in Parkinson's disease. The sequence region 35-59 contains β-strand segments β1 and β2 of α-syn amyloid fibril models and most disease-related mutations. β1 and β2 frequently engage in transient interactions in monomeric α-syn. The consequences of β1-β2 contacts are evaluated by disulfide engineering, biophysical techniques, and cell viability assays. The double-cysteine mutant α-synCC, with a disulfide linking β1 and β2, is aggregation-incompetent and inhibits aggregation and toxicity of wild-type α-syn. We show that α-syn delays the aggregation of amyloid-β peptide and islet amyloid polypeptide involved in Alzheimer's disease and type 2 diabetes, an effect enhanced in the α-synCC mutant. Tertiary interactions in the β1-β2 region of α-syn interfere with the nucleation of amyloid formation, suggesting promotion of such interactions as a potential therapeutic approach. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evidence for a central role of PrP helix 2 in the nucleation of amyloid fibrils.

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Honda, Ryo; Kuwata, Kazuo

2018-02-01

Amyloid fibrils are filamentous protein aggregates associated with the pathogenesis of a wide variety of human diseases. The formation of such aggregates typically follows nucleation-dependent kinetics, wherein the assembly and structural conversion of amyloidogenic proteins into oligomeric aggregates (nuclei) is the rate-limiting step of the overall reaction. In this study, we sought to gain structural insights into the oligomeric nuclei of the human prion protein (PrP) by preparing a series of deletion mutants lacking 14-44 of the C-terminal 107 residues of PrP and examined the kinetics and thermodynamics of these mutants in amyloid formation. An analysis of the experimental data using the concepts of the Φ-value analysis indicated that the helix 2 region (residues 168-196) acquires an amyloid-like β-sheet during nucleation, whereas the other regions preserves a relatively disordered structure in the nuclei. This finding suggests that the helix 2 region serves as the nucleation site for the assembly of amyloid fibrils.-Honda, R., Kuwata, K. Evidence for a central role of PrP helix 2 in the nucleation of amyloid fibrils.

To estimate effective antiamyloidogenic property of melatonin and fisetin and their actions to destabilize amyloid fibrils.

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Aarabi, Mohammad Hossein; Mirhashemi, Seyyed Mehdi

2017-09-01

Aggregating of amylin as pancreatic deposition is connected with pancreas degeneration in type 2 diabetes mellitus. Suppression of the amylin accumulation and so instability of the pre-formed pancreatic β-amyloid, may be attractive curative goal for mediation of diabetes mellitus. Fluorimetric assay by Thioflavin-T was utilized for investigating the properties of melatonin and fisetin on the generation and instability of β-amyloid near to physiological conditions. The results showed that after 168 hours incubation by shaker incubator in 37oC, melatonin at 10μM and 40 µM repressed amylin amyloid formation by 20.1% and 27.5% respectively (p<0.05) and the similar values of fisetin inhibited the formation of β-sheet structure by 16.5% and 23.2% respectively (p<0.05).The obtained data also confirmed that amyloidal sheet opening was induced by melatonin and fisetin significantly (p<0.05). It may be concluded that islet amyloid cytotoxicity to β-cells may be reduced by melatonin and fisetin, and they should be important constituents of new drugs for diabetes mellitus treatment.

Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation.

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Michaels, Thomas C T; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M; Knowles, Tuomas P J

2018-04-20

Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

Chemical Kinetics for Bridging Molecular Mechanisms and Macroscopic Measurements of Amyloid Fibril Formation

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Michaels, Thomas C. T.; Šarić, Anđela; Habchi, Johnny; Chia, Sean; Meisl, Georg; Vendruscolo, Michele; Dobson, Christopher M.; Knowles, Tuomas P. J.

2018-04-01

Understanding how normally soluble peptides and proteins aggregate to form amyloid fibrils is central to many areas of modern biomolecular science, ranging from the development of functional biomaterials to the design of rational therapeutic strategies against increasingly prevalent medical conditions such as Alzheimer's and Parkinson's diseases. As such, there is a great need to develop models to mechanistically describe how amyloid fibrils are formed from precursor peptides and proteins. Here we review and discuss how ideas and concepts from chemical reaction kinetics can help to achieve this objective. In particular, we show how a combination of theory, experiments, and computer simulations, based on chemical kinetics, provides a general formalism for uncovering, at the molecular level, the mechanistic steps that underlie the phenomenon of amyloid fibril formation.

Distinct Prion Domain Sequences Ensure Efficient Amyloid Propagation by Promoting Chaperone Binding or Processing In Vivo.

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Christine R Langlois

2016-11-01

Full Text Available Prions are a group of proteins that can adopt a spectrum of metastable conformations in vivo. These alternative states change protein function and are self-replicating and transmissible, creating protein-based elements of inheritance and infectivity. Prion conformational flexibility is encoded in the amino acid composition and sequence of the protein, which dictate its ability not only to form an ordered aggregate known as amyloid but also to maintain and transmit this structure in vivo. But, while we can effectively predict amyloid propensity in vitro, the mechanism by which sequence elements promote prion propagation in vivo remains unclear. In yeast, propagation of the [PSI+] prion, the amyloid form of the Sup35 protein, has been linked to an oligopeptide repeat region of the protein. Here, we demonstrate that this region is composed of separable functional elements, the repeats themselves and a repeat proximal region, which are both required for efficient prion propagation. Changes in the numbers of these elements do not alter the physical properties of Sup35 amyloid, but their presence promotes amyloid fragmentation, and therefore maintenance, by molecular chaperones. Rather than acting redundantly, our observations suggest that these sequence elements make complementary contributions to prion propagation, with the repeat proximal region promoting chaperone binding to and the repeats promoting chaperone processing of Sup35 amyloid.

Small heat shock proteins potentiate amyloid dissolution by protein disaggregases from yeast and humans.

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Martin L Duennwald

Full Text Available How small heat shock proteins (sHsps might empower proteostasis networks to control beneficial prions or disassemble pathological amyloid is unknown. Here, we establish that yeast sHsps, Hsp26 and Hsp42, inhibit prionogenesis by the [PSI+] prion protein, Sup35, via distinct and synergistic mechanisms. Hsp42 prevents conformational rearrangements within molten oligomers that enable de novo prionogenesis and collaborates with Hsp70 to attenuate self-templating. By contrast, Hsp26 inhibits self-templating upon binding assembled prions. sHsp binding destabilizes Sup35 prions and promotes their disaggregation by Hsp104, Hsp70, and Hsp40. In yeast, Hsp26 or Hsp42 overexpression prevents [PSI+] induction, cures [PSI+], and potentiates [PSI+]-curing by Hsp104 overexpression. In vitro, sHsps enhance Hsp104-catalyzed disaggregation of pathological amyloid forms of α-synuclein and polyglutamine. Unexpectedly, in the absence of Hsp104, sHsps promote an unprecedented, gradual depolymerization of Sup35 prions by Hsp110, Hsp70, and Hsp40. This unanticipated amyloid-depolymerase activity is conserved from yeast to humans, which lack Hsp104 orthologues. A human sHsp, HspB5, stimulates depolymerization of α-synuclein amyloid by human Hsp110, Hsp70, and Hsp40. Thus, we elucidate a heretofore-unrecognized human amyloid-depolymerase system that could have applications in various neurodegenerative disorders.

Amyloid β Is Not the Major Factor Accounting for Impaired Adult Hippocampal Neurogenesis in Mice Overexpressing Amyloid Precursor Protein

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Hongyu Pan

2016-10-01

Full Text Available Adult hippocampal neurogenesis was impaired in several Alzheimer's disease models overexpressing mutant human amyloid precursor protein (hAPP. However, the effects of wild-type hAPP on adult neurogenesis and whether the impaired adult hippocampal neurogenesis was caused by amyloid β (Aβ or APP remained unclear. Here, we found that neurogenesis was impaired in the dentate gyrus (DG of adult mice overexpressing wild-type hAPP (hAPP-I5 compared with controls. However, the adult hippocampal neurogenesis was more severely impaired in hAPP-I5 than that in hAPP-J20 mice, which express similar levels of hAPP mRNA but much higher levels of Aβ. Furthermore, reducing Aβ levels did not affect the number of doublecortin-positive cells in the DG of hAPP-J20 mice. Our results suggested that hAPP was more likely an important factor inhibiting adult neurogenesis, and Aβ was not the major factor affecting neurogenesis in the adult hippocampus of hAPP mice.

Fibrils from designed non-amyloid-related synthetic peptides induce AA-amyloidosis during inflammation in an animal model.

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Per Westermark

Full Text Available BACKGROUND: Mouse AA-amyloidosis is a transmissible disease by a prion-like mechanism where amyloid fibrils act by seeding. Synthetic peptides with no amyloid relationship can assemble into amyloid-like fibrils and these may have seeding capacity for amyloid proteins. PRINCIPAL FINDINGS: Several synthetic peptides, designed for nanotechnology, have been examined for their ability to produce fibrils with Congo red affinity and concomitant green birefringence, affinity for thioflavin S and to accelerate AA-amyloidosis in mice. It is shown that some amphiphilic fibril-forming peptides not only produced Congo red birefringence and showed affinity for thioflavin S, but they also shortened the lag phase for systemic AA-amyloidosis in mice when they were given intravenously at the time of inflammatory induction with silver nitride. Peptides, not forming amyloid-like fibrils, did not have such properties. CONCLUSIONS: These observations should caution researchers and those who work with synthetic peptides and their derivatives to be aware of the potential health concerns.

Spatial patterns of brain amyloid-beta burden and atrophy rate associations in mild cognitive impairment

NARCIS (Netherlands)

Tosun, Duygu; Schuff, Norbert; Mathis, Chester A.; Jagust, William; Weiner, Michael W.; Saradha, A.; Abdi, Herve; Abdulkadir, Ahmed; Abeliovich, Asa; Abellan van Kan, Gabor; Abner, Erin; Acharya, Deepa; Agrusti, Antonella; Agyemang, Alex; Ahdidan, Jamila; Ahmed, Shiek; Ahn, Jae Eun; Aisen, Paul; Aksu, Yaman; Al-Akhras, Mousa; Alarcon, Marcelo; Alberca, Roman; Alexander, Gene; Alexander, Daniel; Alin, Aylin; Almeida, Fabio; Amlien, Inge; Anand, Shyam; Anderson, Dallas; Andrew, Marilee; Angersbach, Steve; Anjum, Ayesha; Aoyama, Eiji; Arfanakis, Konstantinos; Armor, Tom; Arnold, Steven; Arunagiri, Vidhya; Asatryan, Albert; Ashe-McNalley, Cody; Ashiga, Hirokazu; Assareh, Arezoo; Le Page, Aurelie; Avants, Brian; Avinash, Gopal; Aviv, Richard; Awasthi, Sukrati; Ayan-Oshodi, Mosun; Babic, Tomislav; Baek, Young; Bagci, Ulas; Bai, Shuyang; Baird, Geoffrey; Baker, John; Banks, Sarah; Bard, Jonathan; Barnes, Josephine; Bartlett, Jonathan; Bartzokis, George; Barua, Neil; Bauer, Corinna; Bayley, Peter; Beck, Irene; Becker, James; Becker, J. Alex; Beckett, Laurel; Bednar, Martin; Beg, Mirza Faisal; Bek, Stephan; Belaroussi, Boubakeur; Belmokhtar, Nabil; Bernard, Charlotte; Bertram, Lars; Bhaskar, Uday; Biffi, Alessandro; Bigler, Erin; Bilgic, Basar; Bishop, Courtney; Bittner, Daniel; Black, Ronald; Bogorodzki, Piotr; Bokde, Arun; Bonner-Jackson, Aaron; Boppana, Madhu; Bourgeat, Pierrick; Bowes, Mike; Bowman, DuBois; Bowman, Gene; Braskie, Meredith; Braunewell, Karl; Breitner, Joihn; Bresell, Anders; Brewer, James; Brickman, Adam; Britschgi, Markus; Broadbent, Steve; Brogren, Jacob; Brooks, David; Browndyke, Jeffrey; Brunton, Simon; Buchert, Ralph; Buchsbaum, Monte; Buckley, Chris; Buerger, Katharina; Burger, Cyrill; Burnham, Samantha; Burns, Jeffrey; Burton, David; Butman, John; Cabeza, Rafael; Cairns, Nigel; Callhoff, Johanna; Calvini, Piero; Cantillon, Marc; Capella, Heraldo; Carbotti, Angela; Cardona-Sanclemente, Luis Eduardo; Carle, Adam; Carmasin, Jeremy; Carranza-Ath, Fredy; Casabianca, Jodi; Casanova, Ramon; Cash, David; Cedarbaum, Jesse; Cella, Massimo; Celsis, Pierre; Chanu, Pascal; Chao, Linda; Charil, Arnaud; Chemali, Zeina; Chen, Rong; Chen, Jake; Chen, Gennan; Chen, Wei; Chen, Kewei; Chen, Shuzhong; Chen, Minhua; Cheng, Wei-Chen; Cherkas, Yauheniya; Chertkow, Howard; Cheung, Charlton; Cheung, Vinci; Chiang, Gloria; Chiba, Koji; Chin, Simon; Chisholm, Jane; Cho, Youngsang; Choe, John; Choubey, Suresh; Chowbina, Sudhir; Christensen, Anette Luther; Clark, David; Clark, Chris; Clarkson, Matt; Clayton, David; Clunie, David; Coen, Michael; Coimbra, Alexandre; Compton, David; Coppola, Giovanni; Coulin, Samuel; Cover, Keith S.; Crane, Paul; Crans, Gerald; Croop, Robert; Crowther, Daniel; Crum, William; Cui, Yue; Curry, Charles; Curtis, Steven; Cutter, Gary; Daiello, Lori; Dake, Michael; Dale, Anders; Daliri, Mohammad Reza; Damato, Vito Domenico; Darby, Eveleen; Darkner, Sune; Davatzikos, Christos; Dave, Jay; David, Renaud; DavidPrakash, Bhaskaran; Davidson, Julie; de Bruijne, Marleen; de Meyer, Geert; de Nunzio, Giorgio; Decarli, Charles; Dechairo, Bryan; DeDuck, Kristina; Dehghan, Hossein; Dejkam, Arsalan; Delfino, Manuel; Della Rosa, Pasquale Anthony; Dellavedova, Luca; Delpassand, Ebrahim; Delrieu, Julien; DeOrchis, Vincent; Depy Carron, Delphine; deToledo-Morrell, Leyla; Devanand, Davangere; Devanarayan, Viswanath; DeVous, Michael; Diaz-Arrastia, Ramon; Bradford, Dickerson; Ding, Xiaobo; Dinov, Ivo; Dobson, Howard; Dodge, Hiroko; Donohue, Michael; Dore, Vincent; Dorflinger, Ernest; Dowling, Maritza; Duan, Xujun; Dubal, Dena; Duchesne, Simon; Duff, Kevin; Dukart, Jrgen; Durazzo, Timothy; Dykstra, Kevin; Earl, Nancy; Edula, Goutham; Ekin, Ahmet; Elcoroaristizabal, Xabier; Emahazion, Tesfai; Engelman, Corinne; Epstein, Noam; Erten-Lyons, Deniz; Eskildsen, Simon; Falcone, Guido; Fan, Lingzhong; Fan, Yong; Farahibozorg, Seyedehrezvan; Farb, Norman; Farnum, Michael; Farrer, Lindsay; Farzan, Ali; Faux, Noel; Feldman, Betsy; Feldman, Howard; Feldman, Susan; Fennema-Notestine, Christine; Fernandes, Michel; Fernandez, Elsa; Ferrarini, Luca; Ferreira, Manuel Joao; Ferrer, Eugene; Figurski, Michal; Filipovych, Roman; Fillit, Howard; Finch, Stephen; Finlay, Daniel; Fiot, Jean-Baptiste; Flenniken, Derek; Fletcher, P. Thomas; Fletcher, Evan; Flynn Longmire, Crystal; Focke, Niels; Forman, Mark; Forsythe, Alan; Fox, Steven; Fox-Bosetti, Sabrina; Francis, Alexander L.; Franco-Villalobos, Conrado; Franko, Edit; Freeman, Stefanie; Friedrich, Christoph M.; Friesenhahn, Michel; Frings, Lars; Frisoni, Giovanni; Fritzsche, Klaus; Fujimoto, Yoko; Fujiwara, Ken; Fullerton, Terence; Furney, Simon; Gallins, Paul; Galvin, Ben; Gamst, Anthony; Gan, Ke; Garcia, Maria Teresa; Garg, Gaurav; Gaser, Christian; Gastineau, Edward; Gauthier, Serge; Gavett, Brandon; Gavidia, Giovana; Gazdzinski, Stefan; Ge, Qi; Ge, Tian; Gemme, Gianluca; Geraci, Joseph; Ghassabi, Zeinab; Gieschke, Ronald; Gil, Juan E.; Gill, Ryan; Gitelman, Darren; Gleason, Carey; Glymour, M. Maria; Godbey, Michael; Goghari, Vina; Gold, Michael; Goldberg, Terry; Goldman, Jennifer; Gomeni, Roberto; Gong, Shangwenyan; Gonzales, Celedon; Goodro, Robert; Gordon, Brian; Gore, Chris; Gorriz, Juan Manuel; Grachev, Igor; Grandey, Emily; Grasela, Thaddeus; Gratt, Jeremy; Gray, Katherine; Greenberg, Barry; Gregg, Keith; Gregory, Erik; Greicius, Michael; Greve, Douglas; Grill, Joshua; Gross, Alden; Gross, Alan; Guignot, Isabelle; Guo, Jeffrey; Guo, Qimiao; Guo, Hongbin; Guo, Lianghao; Habeck, Christian; Hai, Yizhen; Haight, Thaddeus; Hammarstrom, Per; Hampel, Harald; Han, Duke; Han, Jian; Han, Tony; Hanif, Muhammad; Hanna, Yousef; Hardy, Peter; Harvey, Danielle; Hasan, Md Kamrul; Hayashi, Toshihiro; Hazart, Aurelien; He, Huiguang; He, Yong; Head, Denise; Heckemann, Rolf; Heidebrink, Judith; Henderson, David; Henrard, Sebastien; Herholz, Karl; Hernandez, Monica; Herskovits, A. Zara; Hess, Christopher; Hildenbrand, Maike; Hobart, Jeremy; Hoffman, John; Holder, Daniel; Hollingworth, Paul; Holmes, Robin; Honigberg, Lee; Hoppin, Jack; Hou, Yangyang; Hsu, Ailing; Hsu, Wei-Wen; Hu, Xiaolan; Hu, Zhiwei; Hu, William; Huang, Juebin; Huang, Chien-Chih; Huang, Chingwen; Huang, Shuai; Huang, Yifan; Huang, Fude; Huang, Chun-Jung; Huang, Shu-Pang; Hubbard, Rebecca; Huentelman, Matthew; Hui, Shen; Huppertz, Hans-Jürgen; Hurko, Orest; Hurt, Stephen; Huyck, Susan; Hwang, Scott; Hyun, JungMoon; Ifeachor, Emmanuel; Iglesias, Martina; Ikari, Yasuhiko; Ikonomidou, Vasiliki; Imani, Farzin; Immermann, Fred; Inlow, Mark; Inoue, Lurdes; Insel, Philip; Irizarry, Michael; Irungu, Benson mwangi; Ishibashi, Taro; Ishii, Kenji; Ismail, Sara; Ismail, Shahina; Ito, Kaori; Iturria-Medina, Yasser; Iwatsubo, Takeshi; Jacobson, Mark; Jacqmin, Philippe; Jafari, Aria; Jafari-Khouzani, Kourosh; Jaffe, Carl; Jara, Hernan; Jasperse, Bas; Jedynak, Bruno; Jefferson, Angela; Jennings, J. Richard; Jessen, Walter; Jia, Fucang; Jiang, Tianzi; Jing, Huang; Johnson, Julene; Johnson, Sterling; Johnson, David K.; Jones, Richard; Juengling, Freimut; Juh, Rahyeong; Julin, Per; Kadish, Bill; Kahle-Wrobleski, Kristin; Kallam, Hanimi Reddy; Kamboh, M. Ilyas; Kaneko, Tomoki; Kaneta, Tomohiro; Kang, Ju Hee; Karageorgiou, Elissaios; Karantzoulis, Stella; Karlawish, Jason; Katz, Elyse; Kaushik, Sandeep S.; Kauwe, John; Kawakami, Hirofumi; Kazimipoor, Borhan; Kelleher, Thomas; Kennedy, Richard; Kerchner, Geoffrey; Kerrouche, Nacer; Khalil, Iya; Khalil, Andre; Killeen, Neil; Killiany, Ron; Kim, Jong Hun; Kim, Heeyoung; Kim, Ana; Kim, Yeonhee; Kim, Hyoungkyu; Kim, Seongkyun; Kim, Hyewon; Kimberg, Daniel; Kimura, Tokunori; King, Richard; Kirby, Justin; Kirsch, Wolff; Klimas, Michael; Kline, Richard; Kling, Mitchel; Klopfenstein, Erin; Koikkalainen, Juha; Kokomoor, Anders; Kolasny, Anthony; Koppel, Jeremy; Korolev, Igor; Kotran, Nickolas; Kouassi, Alex; Kowalczyk, Adam; Kozma, Lynn; Krams, Michael; Kratzer, Martina; Kuceyeski, Amy; Kuhn, Felix Pierre; Kumar, Sreedhar; Kuo, Hsun Ting; Kuo, Julie; Kurosawa, Ken; Kwon, Oh Hun; Labrish, Catherine; Laforet, Genevieve; Lai, Song; Lakatos, Anita; Lam, On Ki; Lampron, Antoine; Landau, Susan; Landen, Jaren; Lane, Richard; Langbaum, Jessica; Langford, Dianne; Lanius, Vivian; Laxamana, Joel; Le, Trung; Leahy, Richard; Lee, Jong-Min; Lee, Vita; Lee, Joseph H.; Lee, Grace; Lee, Dongsoo; Lee, Noah; Lefkimmiatis, Stamatis; Lemaitre, Herve; Lenfant, Pierre; Lenz, Robert; Leoutsakos, Jeannie-Marie; Lester, Gayle; Levey, Allan; Li, Shi-jiang; Li, Shanshan; Li, Wenjun; Li, Chin-Shang; Li, Xiaodong; Li, Rui; Li, Ming; Li, Lexin; Li, Jinhe; Li, Yi; Li, Quanzheng; Li, Gang; Liang, Kuchang; Liang, Peipeng; Liang, Lichen; Liao, Yuan-Lin; Lin, Ling-chih; Lin, Lan; Lin, Mingkuan; Lin, Ai-Ling; Liu, Songling; Liu, Yuan; Liu, Tianming; Liu, Meijie; Liu, Xiuwen; Liu, Li; Liu, Honggang; Liu, Pu; Liu, Tao; Liu, Sophia; Liu, Dazhong; Lo, Raymond; Lobanov, Victor; Loewenstein, David; Logovinsky, Veronika; Long, Xiaojing; Long, Ziyi; Looi, Jeffrey; Lu, Po-Haong; Lukic, Ana; Lull, Juan J.; Luo, Xiongjian; Lynch, John; Ma, Lei; Mackin, Scott; Mada, Marius; Magda, Sebastian; Maglio, Silvio; Maikusa, Norihide; Mak, Henry Ka-Fung; Malave, Vicente; Maldjian, Joseph; Mandal, Pravat; Mangin, Jean-Francois; Manjon, Jose; Mantri, Ninad; Manzour, Amir; Marambaud, Philippe; Marchewka, Artur; Marek, Kenneth; Markind, Samuel; Marshall, Gad; Martinez Torteya, Antonio; Mather, Mara; Mathis, Chester; Matoug, Sofia; Matsuo, Yoshiyuki; Mattei, Peter; Matthews, Dawn; McArdle, John; McCarroll, Steven; McEvoy, Linda; McGeown, William; McGonigle, John; McIntyre, John; McLaren, Donald; McQuail, Joseph; Meadowcroft, Mark; Meda, Shashwath; Mehta, Nirav; Melie-Garcia, Lester; Melrose, Rebecca; Mendonca, Brian; Menendez, Manuel; Meredith, Jere; Merrill, David; Mesulam, Marek-Marsel; Metti, Andrea; Meyer, Carsten; Mez, Jesse; Mickael, Guedj; Miftahof, Roustem; Mikhno, Arthur; Miller, David; Millikin, Colleen; Min, Ye; Mirza, Mubeena; Mistridis, Panagiota; Mitchell, Meghan; Mitsis, Effie; Mohan, Ananth; Moore, Dana; Moradi Birgani, Parmida; Moratal, David; Morimoto, Bruce; Mormino, Elizabeth; Mortamet, Benedicte; Moscato, Pablo; Mueller, Kathyrne; Mueller, Susanne; Mueller, Notger; Mukherjee, Shubhabrata; Mulder, Emma; Murayama, Shigeo; Murphy, Michael; Murray, Brian; Musiek, Erik; Myers, Amanda; Najafi, Shahla; Nazarparvar, Babak; Nazeri, Arash; Nettiksimmons, Jasmine; Neu, Scott; Ng, Yen-Bee; Nguyen, Nghi; Nguyen Xuan, Tuong; Nichols, Thomas; Nicodemus, Kristin; Niecko, Timothy; Nielsen, Casper; Notomi, Keiji; Nutakki, Gopi Chand; O'Bryant, Sid; O'Neil, Alison; Obisesan, Thomas; Oh, Dong Hoon; Oh, Joonmi; Okonkwo, Ozioma; Olde Rikkert, Marcel; Olmos, Salvador; Ortner, Marion; Ostrowitzki, Susanne; Oswald, Annahita; Ott, Brian; Ourselin, Sebastien; Ouyang, Gaoxiang; Paiva, Renata; Pan, Zhifang; Pande, Yogesh; Pardo, Jose; Pardoe, Heath; Park, Hyunjin; Park, Lovingly; Park, Moon Ho; Park, Sang hyun; Park, Kee Hyung; Park, Sujin; Parsey, Ramin; Parveen, Riswana; Paskavitz, James; Patel, Yogen; Patil, Manasi; Pawlak, Mikolaj; Payoux, Pierre; Pearson, Jim; Peavy, Guerry; Pell, Gaby; Peng, Yahong; Pennec, Xavier; Pepin, Jean louis; Perea, Rodrigo; Perneczky, Robert; Petitti, Diana; Petrella, Jeffrey; Peyrat, Jean-Marc; Pezoa, Jorge; Pham, Chi-Tuan; Phillips, Justin; Phillips, Nicole; Pierson, Ronald; Piovezan, Mauro; Podhorski, Adam; Pollari, Mika; Pontecorvo, Michael; Poppenk, Jordan; Posner, Holly; Potkin, Steven; Potter, Guy; Potter, Elizabeth; Poulin, Stephane; Prasad, Gautam; Prenger, Kurt; Prince, Jerry; Priya, Anandh; Puchakayala, Shashidhar Reddy; Qiu, Ruolun; Qiu, Anqi; Qiu, Wendy; Qualls, Constance Dean; Rabie, Huwaida; Rajeesh, Rajeesh; Rallabandi, V. P. Subramanyam; Ramage, Amy; Randolph, Christopher; Rao, Anil; Rao, Divya; Raubertas, Richard; Ray, Debashis; Razak, Hana; Redolfi, Alberto; Reed, Bruce; Reid, Andrew; Reilhac, Anthonin; Reinsberger, Claus; Restrepo, Lucas; Retico, Alessandra; Richards, John; Riddle, William; Ries, Michele; Rincon, Mariano; Rischall, Matt; Rizk-Jackson, Angela; Robieson, Weining; Rocha-Rego, Vanessa; Rogalski, Emily; Rogers, Elizabeth; Rojas, Ignacio; Rojas Balderrama, Javier; Romero, Klaus; Rorden, Chris; Rosand, Jonathan; Rosen, Allyson; Rosen, Ori; Rosenberg, Paul; Ross, David; Roubini, Eli; Rousseau, François; Rowe, Christopher; Rubin, Daniel; Rubright, Jonathan; Ruiz, Agustin; Rusinek, Henry; Ryan, Laurie; Saad, Ahmed; Sabbagh, Marway; Sabuncu, Mert; Sachs, Michael; Sadeghi, Ali; Said, Yasmine; Saint-Aubert, Laure; Sakata, Muneyuki; Salat, David; Salmon, David; Salter, Hugh; Samwald, Matthias; Sanchez, Luciano; Sanders, Elizabeth; Sanjo, Nobuo; Sarnel, Haldun; Sato, Hajime; Sato, Shinji; Saumier, Daniel; Savio, Alexandre; Sawada, Ikuhisa; Saykin, Andrew; Schaffer, J. David; Scharre, Douglas; Schegerin, Marc; Schlosser, Gretchen; Schmand, Ben; Schmansky, Nick; Schmidt, Mark; Schmidt-Wilcke, Tobias; Schneider, Lon; Schramm, Hauke; Schuerch, Markus; Schwartz, Eben; Schwartz, Craig; Schwarz, Adam; Seethamraju, Ravi; Seixas, Flavio; Selnes, Per; Senjem, Matthew; Senlin, Wang; Seo, Sang Won; Sethuraman, Gopalan; Sevigny, Jeffrey; Sfikas, Giorgos; Sghedoni, Roberto; Shah, Said Khalid; Shahbaba, Babak; Shams, Soheil; Shattuck, David; Shaw, Leslie; Sheela, Jaba; Shen, Weijia; Shen, Qian; Shera, David; Sherman, John; Sherva, Richard; Shi, Feng; Shukla, Vinay; Shuler, Catherine; Shulman, Joshua; Siegel, Rene; Siemers, Eric; Silveira, Margarida; Silver, Michael; Silverman, Daniel; Sim, Ida; Simmons, Andy; Simoes, Rita; Simon, Melvin; Simpson, Ivor; Singh, Simer Preet; Singh, Nikhil; Siuciak, Judy; Sjogren, Niclas; Skinner, Jeannine; Skup, Martha; Small, Gary; Smith, Michael; Smith, Benjamin; Smith, Charles; Smyth, Timothy; Snow, Sarah; Soares, Holly; Soldea, Octavian; Solomon, Paul; Solomon, Alan; Som, Subhojit; Song, Changhong; Song, Mingli; Sosova, Iveta; Soudah, Eduardo; Soydemir, Melih; Spampinato, Maria Vittoria; Spenger, Christian; Sperling, Reisa; Spiegel, Rene; Spies, Lothar; Squarcia, Sandro; Squire, Larry; Staff, Roger; Stern, Yaakov; Straw, Jack; Stricker, Nikki; Strittmatter, Stephen; Stühler, Elisabeth; Styren, Scot; Subramanian, Vijayalakshmi; Sugishita, Morihiro; Sukkar, Rafid; Sun, Jia; Sun, Ying; Sun, Yu; Sundell, Karen; Suri, Muhammad; Suzuki, Akiyuki; Svetnik, Vladimir; Swan, Melanie; Takahasi, Tetsuhiko; Takeuchi, Tomoko; Tanaka, Shoji; Tanchi, Chaturaphat; Tancredi, Daniel; Tao, Wenwen; Tao, Dacheng; Taylor-Reinwald, Lisa; Teng, Edmond; Terlizzi, Rita; Thames, April; Thiele, Frank; Thomas, Benjamin; Thomas, Ronald; Thompson, Paul; Thompson, Wesley; Thornton-Wells, Tricia; Thorvaldsson, Valgeir; Thurfjell, Lennart; Titeux, Laurence; Tokuda, Takahiko; Toledo, Juan B.; Tolli, Tuomas; Toma, Ahmed; Tomita, Naoki; Toro, Roberto; Torrealdea, Patxi; Tousian, Mona; Toussaint, Paule; Toyoshiba, Hiroyoshi; Tractenberg, Rochelle E.; Trittschuh, Emily; Trojanowski, John; Truran, Diana; Tsechpenakis, Gavriil; Tucker-Drob, Elliot; Tufail, Ahsan; Tung, Joyce; Turken, And; Ueda, Yoji; Ullrich, Lauren; Umadevi Venkataraju, Kannan; Umar, Nisser; Uzunbas, Gokhan; van de Nes, Joseph; van der Brug, Marcel; van Horn, John; van Leemput, Koen; van Train, Kenneth; van Zeeland, Ashley; Vasanawala, Minal; Vemuri, Prashanthi; Verwaerde, Philippe; Videbaek, Charlotte; Vidoni, Eric; Villanueva-Meyer, Javier; Visser, Pieter Jelle; Vitolo, Ottavio; Vounou, Maria; Wade, Sara; Walhovd, Kristine B.; Wan, Hong; Wang, Huanli; Wang, Yongmei Michelle; Wang, Yalin; Wang, Angela; Wang, Lei; Wang, Yue; Wang, Xu; Wang, Ze; Wang, Yaping; Wang, Tiger; Wang, Alex; Wang, Huali; Wang, Li-San; Wang, Wei; Wang, Li; Ward, Michael; Warfield, Simon; Waring, Stephen; Watanabe, Toshiyuki; Webb, David; Wei, Lili; Weiner, Michael; Wen, Shu-Hui; Wenjing, Li; Wenzel, Fabian; Westlye, Lars T.; Whitcher, Brandon; Whitlow, Christopher; Whitwell, Jennifer; Wilhelmsen, Kirk; Williams, David; Wilmot, Beth; Wimsatt, Matt; Wingo, Thomas; Wiste, Heather; Wolfson, Tanya; Wolke, Ira; Wolz, Robin; Woo, Jongwook; Woo, Ellen; Woods, Lynn; Worth, Andrew; Worth, Eric; Wouters, Hans; Wu, Teresa; Wu, Yi-Gen; Wu, Liang; Wu, Xiaoling; Wyman, Bradley; Wyss-Coray, Tony; Xiao, Guanghua; Xiao, Liu; Xie, Sharon; Xu, Shunbin; Xu, Ye; Xu, Yi-Zheng; Xu, Guofan; Xu, Jun; Yamane, Tomohiko; Yamashita, Fumio; Yan, Yunyi; Yan, Pingkun; Yang, Eric; Yang, Jinzhong; Yang, Qing X.; Yang, Zijiang; Yang, Guang; Yang, Zhitong; Yang, Wenlu; Ye, Liang; Ye, Byoung Seok; Ye, Jieping; Ye, Jong; Yee, Laura; Yesavage, Jerome; Ying, Song; Yoo, Bongin; Young, Jonathan; Yu, Shiwei; Yu, Dongchuan; Yuan, Guihong; Yuan, Kai; Yushkevich, Paul; Zaborszky, Laszlo; Zagorodnov, Vitali; Zagorski, Michael; Zawadzki, Rezi; Zeitzer, Jamie; Zelinski, Elizabeth; Zhang, Kurt; Zhang, Huixiong; Zhang, Tianhao; Zhang, Xin; Zhang, Ping; Zhang, Bin; Zhang, Jing; Zhang, Linda; Zhang, Lijun; Zhang, Zhiguo; Zhao, Qinying; Zhao, Jim; Zhao, Peng; Zhen, Xiantong; Zheng, Yuanjie; Zhijun, Yao; Zhou, Bin; Zhou, Sheng; Zhu, Wen; Zhu, Hongtu; Zhu, Wanlin; Zilka, Samantha; Zito, Giancarlo; Zou, Heng

2011-01-01

Amyloid-β accumulation in the brain is thought to be one of the earliest events in Alzheimer's disease, possibly leading to synaptic dysfunction, neurodegeneration and cognitive/functional decline. The earliest detectable changes seen with neuroimaging appear to be amyloid-β accumulation detected by

Diagnostic performance and prognostic value of extravascular retention of I-123-labeled serum amyloid P component in systemic amyloidosis

NARCIS (Netherlands)

Hazenberg, Bouke P. C.; van Rijswijk, Martin H.; Lub-de Hooge, Marjolijn N.; Vellenga, Edo; Haagsma, Elizabeth B.; Posthumus, Marcel D.; Jager, Pieter L.

Serum amyloid P component (SAP) binds to amyloid.I-123-SAP scintigraphy is used to evaluate the extent and distribution of amyloid in systemic amyloidosis and has great clinical value in the detection of systemic amyloidosis. The aim of the study was to assess during scintigraphy the diagnostic

Staphylococcal Bap Proteins Build Amyloid Scaffold Biofilm Matrices in Response to Environmental Signals.

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Agustina Taglialegna

2016-06-01

Full Text Available Biofilms are communities of bacteria that grow encased in an extracellular matrix that often contains proteins. The spatial organization and the molecular interactions between matrix scaffold proteins remain in most cases largely unknown. Here, we report that Bap protein of Staphylococcus aureus self-assembles into functional amyloid aggregates to build the biofilm matrix in response to environmental conditions. Specifically, Bap is processed and fragments containing at least the N-terminus of the protein become aggregation-prone and self-assemble into amyloid-like structures under acidic pHs and low concentrations of calcium. The molten globule-like state of Bap fragments is stabilized upon binding of the cation, hindering its self-assembly into amyloid fibers. These findings define a dual function for Bap, first as a sensor and then as a scaffold protein to promote biofilm development under specific environmental conditions. Since the pH-driven multicellular behavior mediated by Bap occurs in coagulase-negative staphylococci and many other bacteria exploit Bap-like proteins to build a biofilm matrix, the mechanism of amyloid-like aggregation described here may be widespread among pathogenic bacteria.

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases.

Science.gov (United States)

Alam, Parvez; Chaturvedi, Sumit Kumar; Siddiqi, Mohammad Khursheed; Rajpoot, Ravi Kant; Ajmal, Mohd Rehan; Zaman, Masihuz; Khan, Rizwan Hasan

2016-05-27

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer's, Parkinson's and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and Aβ-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demonstrated that vitamin k3 significantly inhibits fibril formation as well as the inhibitory effect is dose dependent manner. Our experimental studies inferred that vitamin k3 exert its neuro protective effect against amyloid induced cytotoxicity through concerted pathway, modifying the aggregation formation towards formation of nontoxic aggregates. Molecular docking demonstrated that vitamin k3 mediated inhibition of HEWL and Aβ-42 fibrillogenesis may be initiated by interacting with proteolytic resistant and aggregation prone regions respectively. This work would provide an insight into the mechanism of protein aggregation inhibition by vitamin k3; pave the way for discovery of other small molecules that may exert similar effect against amyloid formation and its associated neurodegenerative diseases.

Dual role of interleukin-1β in islet amyloid formation and its β-cell toxicity: Implications for type 2 diabetes and islet transplantation.

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Park, Yoo Jin; Warnock, Garth L; Ao, Ziliang; Safikhan, Nooshin; Meloche, Mark; Asadi, Ali; Kieffer, Timothy J; Marzban, Lucy

2017-05-01

Islet amyloid, formed by aggregation of human islet amyloid polypeptide (hIAPP), contributes to β-cell failure in type 2 diabetes, cultured and transplanted islets. We previously showed that biosynthetic hIAPP aggregates induce β-cell Fas upregulation and activation of the Fas apoptotic pathway. We used cultured human and hIAPP-expressing mouse islets to investigate: (1) the role of interleukin-1β (IL-1β) in amyloid-induced Fas upregulation; and (2) the effects of IL-1β-induced β-cell dysfunction on pro-islet amyloid polypeptide (proIAPP) processing and amyloid formation. Human and h IAPP -expressing mouse islets were cultured to form amyloid without or with the IL-1 receptor antagonist (IL-1Ra) anakinra, in the presence or absence of recombinant IL-1β. Human islets in which amyloid formation was prevented (amyloid inhibitor or Ad-prohIAPP-siRNA) were cultured similarly. β-cell function, apoptosis, Fas expression, caspase-8 activation, islet IL-1β, β-cell area, β-/α-cell ratio, amyloid formation, and (pro)IAPP forms were assessed. hIAPP aggregates were found to increase IL-1β levels in cultured human islets that correlated with β-cell Fas upregulation, caspase-8 activation and apoptosis, all of which were reduced by IL-1Ra treatment or prevention of amyloid formation. Moreover, IL-1Ra improved culture-induced β-cell dysfunction and restored impaired proIAPP processing, leading to lower amyloid formation. IL-1β treatment potentiated impaired proIAPP processing and increased amyloid formation in cultured human and h IAPP -expressing mouse islets, which were prevented by IL-1Ra. IL-1β plays a dual role by: (1) mediating amyloid-induced Fas upregulation and β-cell apoptosis; (2) inducing impaired proIAPP processing thereby potentiating amyloid formation. Blocking IL-1β may provide a new strategy to preserve β cells in conditions associated with islet amyloid formation. © 2017 John Wiley & Sons Ltd.

Quantitative Analyses of Force-Induced Amyloid Formation in Candida albicans Als5p: Activation by Standard Laboratory Procedures.

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Cho X J Chan

Full Text Available Candida albicans adhesins have amyloid-forming sequences. In Als5p, these amyloid sequences cluster cell surface adhesins to create high avidity surface adhesion nanodomains. Such nanodomains form after force is applied to the cell surface by atomic force microscopy or laminar flow. Here we report centrifuging and resuspending S. cerevisiae cells expressing Als5p led to 1.7-fold increase in initial rate of adhesion to ligand coated beads. Furthermore, mechanical stress from vortex-mixing of Als5p cells or C. albicans cells also induced additional formation of amyloid nanodomains and consequent activation of adhesion. Vortex-mixing for 60 seconds increased the initial rate of adhesion 1.6-fold. The effects of vortex-mixing were replicated in heat-killed cells as well. Activation was accompanied by increases in thioflavin T cell surface fluorescence measured by flow cytometry or by confocal microscopy. There was no adhesion activation in cells expressing amyloid-impaired Als5pV326N or in cells incubated with inhibitory concentrations of anti-amyloid dyes. Together these results demonstrated the activation of cell surface amyloid nanodomains in yeast expressing Als adhesins, and further delineate the forces that can activate adhesion in vivo. Consequently there is quantitative support for the hypothesis that amyloid forming adhesins act as both force sensors and effectors.

Proactive Semantic Interference is Associated with Total and Regional Abnormal Amyloid Load in Non-Demented Community-Dwelling Elders: A Preliminary Study.

Science.gov (United States)

Loewenstein, David A; Greig, Maria T; Curiel, Rosie; Rodriguez, Rosemarie; Wicklund, Meredith; Barker, Warren W; Hidalgo, Jacqueline; Rosado, Marian; Duara, Ranjan

2015-12-01

To evaluate the relationship between susceptibility to proactive semantic interference (PSI) and retroactive semantic interference (RSI) and brain amyloid load in non-demented elders. 27 participants (11 cognitively normal [CN] with subjective memory complaints, 8 CN without memory complaints, and 8 with mild cognitive impairment [MCI]) underwent complete neurological and neuropsychological evaluations. Participants also received the Semantic Interference Test (SIT) and AV-45 amyloid PET imaging. High levels of association were present between total amyloid load, regional amyloid levels, and the PSI measure (in the entire sample and a subsample excluding MCI subjects). RSI and other memory measures showed much weaker associations or no associations with total and regional amyloid load. No associations between amyloid levels and non-memory performance were observed. In non-demented individuals, vulnerability to PSI was highly associated with total and regional beta-amyloid load and may be an early cognitive marker of brain pathology. Copyright © 2015 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

The amyloid architecture provides a scaffold for enzyme-like catalysts.

Science.gov (United States)

Al-Garawi, Z S; McIntosh, B A; Neill-Hall, D; Hatimy, A A; Sweet, S M; Bagley, M C; Serpell, L C

2017-08-03

Natural biological enzymes possess catalytic sites that are generally surrounded by a large three-dimensional scaffold. However, the proportion of the protein molecule that participates in the catalytic reaction is relatively small. The generation of artificial or miniature enzymes has long been a focus of research because enzyme mimetics can be produced with high activity at low cost. These enzymes aim to mimic the active sites without the additional architecture contributed by the protein chain. Previous work has shown that amyloidogenic peptides are able to self-assemble to create an active site that is capable of binding zinc and catalysing an esterase reaction. Here, we describe the structural characterisation of a set of designed peptides that form an amyloid-like architecture and reveal that their capability to mimic carbonic anhydrase and serve as enzyme-like catalysts is related to their ability to self-assemble. These amyloid fibril structures can bind the metal ion Zn 2+ via a three-dimensional arrangement of His residues created by the amyloid architecture. Our results suggest that the catalytic efficiency of amyloid-like assembly is not only zinc-dependent but also depends on an active centre created by the peptides which is, in turn, dependent on the ordered architecture. These fibrils have good esterase activity, and they may serve as good models for the evolution of modern-day enzymes. Furthermore, they may be useful in designing self-assembling fibrils for applications as metal ion catalysts. This study also demonstrates that the ligands surrounding the catalytic site affect the affinity of the zinc-binding site to bind the substrate contributing to the enzymatic activity of the assembled peptides.

Dissociation between brain amyloid deposition and metabolism in early mild cognitive impairment.

Directory of Open Access Journals (Sweden)

Liyong Wu

Full Text Available The hypothetical model of dynamic biomarkers for Alzheimer's disease (AD describes high amyloid deposition and hypometabolism at the mild cognitive impairment (MCI stage. However, it remains unknown whether brain amyloidosis and hypometabolism follow the same trajectories in MCI individuals. We used the concept of early MCI (EMCI and late MCI (LMCI as defined by the Alzheimer's disease Neuroimaging Initiative (ADNI-Go in order to compare the biomarker profile between EMCI and LMCI.To examine the global and voxel-based neocortical amyloid burden and metabolism among individuals who are cognitively normal (CN, as well as those with EMCI, LMCI and mild AD.In the present study, 354 participants, including CN (n = 109, EMCI (n = 157, LMCI (n = 39 and AD (n = 49, were enrolled between September 2009 and November 2011 through ADNI-GO and ADNI-2. Brain amyloid load and metabolism were estimated using [(18F]AV45 and [(18F]fluorodeoxyglucose ([(18F]FDG PET, respectively. Uptake ratio images of [(18F]AV45 and [(18F]FDG were calculated by dividing the summed PET image by the median counts of the grey matter of the cerebellum and pons, respectively. Group differences of global [(18F]AV45 and [(18F]FDG were analyzed using ANOVA, while the voxel-based group differences were estimated using statistic parametric mapping (SPM.EMCI patients showed higher global [(18F]AV45 retention compared to CN and lower uptake compared to LMCI. SPM detected higher [(18F]AV45 uptake in EMCI compared to CN in the precuneus, posterior cingulate, medial and dorsal lateral prefrontal cortices, bilaterally. EMCI showed lower [(18F]AV45 retention than LMCI in the superior temporal, inferior parietal, as well as dorsal lateral prefrontal cortices, bilaterally. Regarding to the global [(18F]FDG, EMCI patients showed no significant difference from CN and a higher uptake ratio compared to LMCI. At the voxel level, EMCI showed higher metabolism in precuneus, hippocampus, entorhinal and

Amyloid arthropathy of the hip joint: MR demonstration of presumed amyloid lesions in 152 patients with long-term hemodialysis

International Nuclear Information System (INIS)

Otake, S.; Yamana, D.; Tsuruta, Y.; Mizutani, H.; Ohba, S.

1998-01-01

The aim of this study was to determine the spectrum of MR findings of presumed amyloid arthropathy of the hip joints in patients on long-term hemodialysis. We prospectively performed T1- and T2-weighted spin-echo imaging on 152 consecutive patients on hemodialysis. The duration of hemodialysis ranged from 5 months to 24 years, 2 months (mean: 8 years, 8 months). The frequency, location, and signal intensity of bone lesions were assessed. In 12 cases with contrast-enhanced MR examination, enhancement pattern of bone lesions, synovial lesions, and intra-articular lesions were characterized. Bone lesions presumed to be amyloid deposits were identified in 60 patients (39 %). Magnetic resonance imaging revealed that amyloid lesions were more extensive than anticipated by plain radiographs. All bone lesions showed decreased signal intensity on T1-weighted images. On T2-weighted images, bone lesions showed increased signal intensity in 32 patients (54 %), decreased signal intensity in 11 patients (18 %), and both increased and decreased signal intensity in 17 patients (28 %). Following intravenous injection of gadolinium-based contrast, all bone lesions showed moderate enhancement. Synovial thickening could not be identified on T1- and T2-weighted images. However, contrast-enhanced images showed thickened synovial membrane, which could be differentiated from joint fluid. Intra-articular nodules showed decreased or intermediate signal intensity on T1-weighted images and decreased signal intensity on T2-weighted images; the intra-articular nodules were contiguous with subchondral bone lesions. Magnetic resonance imaging is useful for evaluating the distribution and extent of amyloidosis of the hip joints in patients undergoing long-term hemodialysis. (orig.) (orig.)

Effects of diet-induced hypercholesterolemia on amyloid ...

Indian Academy of Sciences (India)

2012-10-27

Oct 27, 2012 ... A central hypothesis in the study of Alzheimer's disease (AD) is the accumulation and aggregation of β-amyloid ... protein (APP) and estrogen has been implicated in the pre- .... inant in HCL in the intensity of the expression was lower ..... estrogen replacement therapy of the Women's Health Initiative.

Sequence-Dependent Self-Assembly and Structural Diversity of Islet Amyloid Polypeptide-Derived β-Sheet Fibrils

International Nuclear Information System (INIS)

Wang, Shih-Ting; Lin, Yiyang; Spencer, Ryan K.; Thomas, Michael R.; Nguyen, Andy I.

2017-01-01

Determining the structural origins of amyloid fibrillation is essential for understanding both the pathology of amyloidosis and the rational design of inhibitors to prevent or reverse amyloid formation. In this work, the decisive roles of peptide structures on amyloid self-assembly and morphological diversity were investigated by the design of eight amyloidogenic peptides derived from islet amyloid polypeptide. Among the segments, two distinct morphologies were highlighted in the form of twisted and planar (untwisted) ribbons with varied diameters, thicknesses, and lengths. In particular, transformation of amyloid fibrils from twisted ribbons into untwisted structures was triggered by substitution of the C-terminal serine with threonine, where the side chain methyl group was responsible for the distinct morphological change. This effect was confirmed following serine substitution with alanine and valine and was ascribed to the restriction of intersheet torsional strain through the increased hydrophobic interactions and hydrogen bonding. We also studied the variation of fibril morphology (i.e., association and helicity) and peptide aggregation propensity by increasing the hydrophobicity of the peptide side group, capping the N-terminus, and extending sequence length. Lastly, we anticipate that our insights into sequence-dependent fibrillation and morphological diversity will shed light on the structural interpretation of amyloidogenesis and development of structure-specific imaging agents and aggregation inhibitors.

Breast cancer and amyloid bodies: is there a role for amyloidosis in cancer-cell dormancy?

Directory of Open Access Journals (Sweden)

Mizejewski GJ

2017-04-01

Full Text Available Gerald J Mizejewski Wadsworth Center, New York State Department of Health, Albany, NY, USA Abstract: Breast cancer and Alzheimer’s disease (AD are major causes of death in older women. Interestingly, breast cancer occurs less frequently in AD patients than in the general population. Amyloidosis, the aggregation of amyloid proteins to form amyloid bodies, plays a central role in the pathogenesis of AD and other human neuropathies by forming intracellular fibrillary proteins. Contrary to popular belief, amyloidosis is a common occurrence in mammalian cells, and has recently been reported to be a natural physiological process in response to environmental stress stimulations (such as pH and temperature extremes, hypoxia, and oxidative stress. Many proteins contain an intrinsic “amyloid-converting motif”, which acts in conjunction with a specific noncoding RNA to induce formation of proteinaceous amyloid bodies that are stored in intracellular bundles. In cancer cells such as breast and prostate, the process of amyloidosis induces cells to enter a dormant or resting stage devoid of cell division and proliferation. Therefore, cancer cells undergo growth cessation and enter a dormant stage following amyloidosis in the cell; this is akin to giving the cell AD to cease growth. Keywords: α-fetoprotein, noncoding RNA, amyloid bodies, dormancy, breast cancer, Alzheimer’s disease

New Cyclolignans from Origanumglandulosum Active Against b -amyloid Aggregation

Directory of Open Access Journals (Sweden)

Abdelkader Basli

2014-05-01

Full Text Available Origanum glandulosum Desf is an endemic flavoring herb widely distributed in North Africa that is commonly used in traditional medicine. This oregano species is rich in essential oils but little is known about its phenolic composition. In the present study, a crude extract of O. glandulosum was prepared in order to isolate and investigate its neuroprotective potential to inhibit β-amyloid peptide (Aβ aggregation. The three major compounds of the extract were isolated: rosmarinic acid and two cyclolignans in Origanum genus, globoidnan A and a new derivative named globoidnan B. Rosmarinic acid and globoidnan A showed significant anti-aggregative activity against β amyloid aggregation (IC50 7.0 and 12.0 µM, respectively. In contrast, globoidnan B was found to be less active.

Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein

Directory of Open Access Journals (Sweden)

Masahiro Kawahara

2011-01-01

Full Text Available Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP play crucial roles in the pathogenesis of Alzheimer's disease (AD. Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”, and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.

Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome.

Directory of Open Access Journals (Sweden)

Juliet A Moncaster

2010-05-01

Full Text Available Down syndrome (DS, trisomy 21 is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21 encoding the Alzheimer's disease (AD amyloid precursor protein (APP. Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta, early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Abeta accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Abeta pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Abeta accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Abeta aggregates (approximately 5 to 50 nm identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Abeta in DS lenses. Incubation of synthetic Abeta with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Abeta

New fluorescent probes for detection and characterization of amyloid fibrils

Science.gov (United States)

Gorbenko, Galyna; Trusova, Valeriya; Kirilova, Elena; Kirilov, Georgiy; Kalnina, Inta; Vasilev, Aleksey; Kaloyanova, Stefka; Deligeorgiev, Todor

2010-08-01

The applicability of the novel fluorescent probes, aminoderivative of benzanthrone ABM, squaraine dye SQ-1 and polymethine dye V2 to identification and structural analysis of amyloid fibrils has been evaluated using the lysozyme model system in which fibrillar aggregates have been formed in concentrated ethanol solution. The association constant, binding stoichiometry and molar fluorescence of the bound dye have been determined. ABM was found to surpass classical amyloid marker ThT in the sensitivity to the presence of fibrillar aggregates. Resonance energy transfer measurements involving ABM-SQ-1 and SQ-1-V2 donor-acceptor pairs yielded the limits for fractal-like dimension of lysozyme fibrils.

Serum amyloid A and C-reactive protein combined determination for diagnosis of bacterial infection in neonates%血清淀粉样蛋白A与C反应蛋白联合检测在新生儿细菌感染诊断中的应用

Institute of Scientific and Technical Information of China (English)

沈伟虹; 岳朝艳; 孙振东; 应春妹

2016-01-01

目的：研究血清淀粉样蛋白 A（SAA）和 C 反应蛋白（CRP）以及白细胞总数在新生儿细菌感染诊断中的应用价值。方法分别检测80例细菌感染新生儿及58名体检正常的新生儿（非感染组）SAA、CRP 和白细胞总数并做比较。结果新生儿细菌感染组 SAA 与 CRP 水平分别为（67.3±38.4）、（19.2±11.2）mg/L，明显高于非感染组[（8.7±2.1）、（5.6±2.5）mg/L]（P15.00×109/L，明显高于非感染组[24例（41%）]。结论 SAA 和 CRP 可作为新生儿细菌感染诊断的重要指标，SAA 较 CRP 更为敏感，SAA 与 CRP 的联合检测能够提高新生儿细菌感染的检出率，为疾病的早期诊断和监测提供实验依据。%Objective To study the significance of serum amyloid A(SAA),C-reactive protein(CRP)and white blood cell count determinations for diagnosis of bacterial infection in neonates. Methods SAA,CRP and white blood cell count were determined in 80 neonates with bacterial infection and 58 healthy neonates(non-bacterial infection group),and the results were analyzed. Results The concentrations of SAA and CRP in infection group [(67.3±38.4)and(19.2±11.2) mg/L] were significantly higher than those in non-bacterial infection group [(8.7±2.1)and(5.6±2.5)mg/L](P15.00×109/L in 64 neonates of 80 cases of infection group(80%),which was higher than that in non-bacterial infection group [24 cases(41%)]. Conclusions SAA and CRP could be used as important markers for monitoring bacterial infection in neonates,and SAA is more sensitive than CRP. The combined determination of SAA and CRP could improve the determination rate of bacterial infection,which provides an experimental reference for early diagnosis and monitoring of bacterial infection.

[18F]Fluoroazabenzoxazoles as potential amyloid plaque PET tracers: synthesis and in vivo evaluation in rhesus monkey

International Nuclear Information System (INIS)

Hostetler, Eric D.; Sanabria-Bohórquez, Sandra; Fan Hong; Zeng, Zhizhen; Gammage, Linda; Miller, Patricia; O'Malley, Stacey; Connolly, Brett; Mulhearn, James; Harrison, Scott T.; Wolkenberg, Scott E.; Barrow, James C.; Williams, David L.; Hargreaves, Richard J.; Sur, Cyrille; Cook, Jacquelynn J.

2011-01-01

Introduction: An 18 F-labeled positron emission tomography (PET) tracer for amyloid plaque is desirable for early diagnosis of Alzheimer's disease, particularly to enable preventative treatment once effective therapeutics are available. Similarly, such a tracer would be useful as a biomarker for enrollment of patients in clinical trials for evaluation of antiamyloid therapeutics. Furthermore, changes in the level of plaque burden as quantified by an amyloid plaque PET tracer may provide valuable insights into the effectiveness of amyloid-targeted therapeutics. This work describes our approach to evaluate and select a candidate PET tracer for in vivo quantification of human amyloid plaque. Methods: Ligands were evaluated for their in vitro binding to human amyloid plaques, lipophilicity and predicted blood–brain barrier permeability. Candidates with favorable in vitro properties were radiolabeled with 18 F and evaluated in vivo. Baseline PET scans in rhesus monkey were conducted to evaluate the regional distribution and kinetics of each tracer using tracer kinetic modeling methods. High binding potential in cerebral white matter and cortical grey matter was considered an unfavorable feature of the candidate tracers. Results: [ 18 F]MK-3328 showed the most favorable combination of low in vivo binding potential in white matter and cortical grey matter in rhesus monkeys, low lipophilicity (Log D=2.91) and high affinity for human amyloid plaques (IC 50 =10.5±1.3 nM). Conclusions: [ 18 F]MK-3328 was identified as a promising PET tracer for in vivo quantification of amyloid plaques, and further evaluation in humans is warranted.

Toxic β-Amyloid (Aβ) Alzheimer's Ion Channels: From Structure to Function and Design

Science.gov (United States)

Nussinov, Ruth

2012-02-01

Full-length amyloid beta peptides (Aβ1-40/42) form neuritic amyloid plaques in Alzheimer's disease (AD) patients and are implicated in AD pathology. Recent biophysical and cell biological studies suggest a direct mechanism of amyloid beta toxicity -- ion channel mediated loss of calcium homeostasis. Truncated amyloid beta fragments (Aβ11-42 and Aβ17-42), commonly termed as non-amyloidogenic are also found in amyloid plaques of Alzheimer's disease (AD) and in the preamyloid lesions of Down's syndrome (DS), a model system for early onset AD study. Very little is known about the structure and activity of these smaller peptides although they could be key AD and DS pathological agents. Using complementary techniques of explicit solvent molecular dynamics (MD) simulations, atomic force microscopy (AFM), channel conductance measurements, cell calcium uptake assays, neurite degeneration and cell death assays, we have shown that non-amyloidogenic Aβ9-42 and Aβ17-42 peptides form ion channels with loosely attached subunits and elicit single channel conductances. The subunits appear mobile suggesting insertion of small oligomers, followed by dynamic channel assembly and dissociation. These channels allow calcium uptake in APP-deficient cells and cause neurite degeneration in human cortical neurons. Channel conductance, calcium uptake and neurite degeneration are selectively inhibited by zinc, a blocker of amyloid ion channel activity. Thus truncated Aβ fragments could account for undefined roles played by full length Aβs and provide a novel mechanism of AD and DS pathology. The emerging picture from our large-scale simulations is that toxic ion channels formed by β-sheets are highly polymorphic, and spontaneously break into loosely interacting dynamic units (though still maintaining ion channel structures as imaged with AFM), that associate and dissociate leading to toxic ion flux. This sharply contrasts intact conventional gated ion channels that consist of tightly

AFM-based force spectroscopy measurements of mature amyloid fibrils of the peptide glucagon

DEFF Research Database (Denmark)

Dong, M. D.; Hovgaard, M. B.; Mamdouh, W.

2008-01-01

We report on the mechanical characterization of individual mature amyloid fibrils by atomic force microscopy (AFM) and AFM-based single-molecule force spectroscopy (SMFS). These self-assembling materials, formed from the 29-residue amphiphatic peptide hormone glucagon, were found to display...... a reversible elastic behaviour. Based on AFM morphology and SMFS studies, we suggest that the observed elasticity is due to a force-induced conformational transition which is reversible due to the beta-helical conformation of protofibrils, allowing a high degree of extension. The elastic properties...... of such mature fibrils contribute to their high stability, suggesting that the internal hydrophobic interactions of amyloid fibrils are likely to be of fundamental importance in the assembly of amyloid fibrils and therefore for the understanding of the progression of their associated pathogenic disorders...

Diverging longitudinal changes in astrocytosis and amyloid PET in autosomal dominant Alzheimer's disease.

Science.gov (United States)

Rodriguez-Vieitez, Elena; Saint-Aubert, Laure; Carter, Stephen F; Almkvist, Ove; Farid, Karim; Schöll, Michael; Chiotis, Konstantinos; Thordardottir, Steinunn; Graff, Caroline; Wall, Anders; Långström, Bengt; Nordberg, Agneta

2016-03-01

Alzheimer's disease is a multifactorial dementia disorder characterized by early amyloid-β, tau deposition, glial activation and neurodegeneration, where the interrelationships between the different pathophysiological events are not yet well characterized. In this study, longitudinal multitracer positron emission tomography imaging of individuals with autosomal dominant or sporadic Alzheimer's disease was used to quantify the changes in regional distribution of brain astrocytosis (tracer (11)C-deuterium-L-deprenyl), fibrillar amyloid-β plaque deposition ((11)C-Pittsburgh compound B), and glucose metabolism ((18)F-fluorodeoxyglucose) from early presymptomatic stages over an extended period to clinical symptoms. The 52 baseline participants comprised autosomal dominant Alzheimer's disease mutation carriers (n = 11; 49.6 ± 10.3 years old) and non-carriers (n = 16; 51.1 ± 14.2 years old; 10 male), and patients with sporadic mild cognitive impairment (n = 17; 61.9 ± 6.4 years old; nine male) and sporadic Alzheimer's disease (n = 8; 63.0 ± 6.5 years old; five male); for confidentiality reasons, the gender of mutation carriers is not revealed. The autosomal dominant Alzheimer's disease participants belonged to families with known mutations in either presenilin 1 (PSEN1) or amyloid precursor protein (APPswe or APParc) genes. Sporadic mild cognitive impairment patients were further divided into (11)C-Pittsburgh compound B-positive (n = 13; 62.0 ± 6.4; seven male) and (11)C-Pittsburgh compound B-negative (n = 4; 61.8 ± 7.5 years old; two male) groups using a neocortical standardized uptake value ratio cut-off value of 1.41, which was calculated with respect to the cerebellar grey matter. All baseline participants underwent multitracer positron emission tomography scans, cerebrospinal fluid biomarker analysis and neuropsychological assessment. Twenty-six of the participants underwent clinical and imaging follow-up examinations after 2.8 ± 0.6 years. By using linear

Interaction of the amyloid β peptide with sodium dodecyl sulfate as a membrane-mimicking detergent.

NARCIS (Netherlands)

Hashemi, Shabestari M.; Meeuwenoord, N.J.; Filippov, D.V.; Huber, M.I.

2016-01-01

The amyloid β (A β) peptide is important in the context of Alzheimer's disease, since it is one of the major components of the fibrils that constitute amyloid plaques. Agents that can influence fibril formation are important, and of those, membrane mimics are particularly relevant, because the

Evaluation of Amyloid Protective Factors and Alzheimer Disease Neurodegeneration Protective Factors in Elderly Individuals.

Science.gov (United States)

Vemuri, Prashanthi; Knopman, David S; Lesnick, Timothy G; Przybelski, Scott A; Mielke, Michelle M; Graff-Radford, Jonathan; Murray, Melissa E; Roberts, Rosebud O; Vassilaki, Maria; Lowe, Val J; Machulda, Mary M; Jones, David T; Petersen, Ronald C; Jack, Clifford R

2017-06-01

While amyloid and neurodegeneration are viewed together as Alzheimer disease pathophysiology (ADP), the factors that influence amyloid and AD-pattern neurodegeneration may be considerably different. Protection from these ADP factors may be important for aging without significant ADP. To identify the combined and independent protective factors for amyloid and AD-pattern neurodegeneration in a population-based sample and to test the hypothesis that "exceptional agers" with advanced ages do not have significant ADP because they have protective factors for amyloid and neurodegeneration. This cohort study conducted a prospective analysis of 942 elderly individuals (70-≥90 years) with magnetic resonance imaging and Pittsburgh compound B-positron emission tomography scans enrolled in the Mayo Clinic Study of Aging, a longitudinal population-based study of cognitive aging in Olmsted County, Minnesota. We operationalized "exceptional aging" without ADP by considering individuals 85 years or older to be without significant evidence of ADP. We evaluated predictors including demographics, APOE, intellectual enrichment, midlife risk factors (physical inactivity, obesity, smoking, diabetes, hypertension, and dyslipidemia), and the total number of late-life cardiac and metabolic conditions. We used multivariate linear regression models to identify the combined and independent protective factors for amyloid and AD-pattern neurodegeneration. Using a subsample of the cohort 85 years of age or older, we computed Cohen d-based effect size estimations to compare the quantitative strength of each predictor variable in their contribution with exceptional aging without ADP. The study participants included 423 (45%) women and the average age of participants was 79.7 (5.9) years. Apart from demographics and the APOE genotype, only midlife dyslipidemia was associated with amyloid deposition. Obesity, smoking, diabetes, hypertension, and cardiac and metabolic conditions, but not

Structural and Thermodynamic Properties of Amyloid-β Peptides: Impact of Fragment Size

Science.gov (United States)

Kitahara, T.; Wise-Scira, O.; Coskuner, O.

2010-10-01

Alzheimer's disease is a progressive neurodegenerative disease whose physiological characteristics include the accumulation of amyloid-containing deposits in the brain and consequent synapse and neuron loss. Unfortunately, most widely used drugs for the treatment can palliate the outer symptoms but cannot cure the disease itself. Hence, developing a new drug that can cure it. Most recently, the ``early aggregation and monomer'' hypothesis has become popular and a few drugs have been developed based on this hypothesis. Detailed understanding of the amyloid-β peptide structure can better help us to determine more effective treatment strategies; indeed, the structure of Amyloid has been studied extensively employing experimental and theoretical tools. Nevertheless, those studies have employed different fragment sizes of Amyloid and characterized its conformational nature in different media. Thus, the structural properties might be different from each other and provide a reason for the existing debates in the literature. Here, we performed all-atom MD simulations and present the structural and thermodynamic properties of Aβ1-16, Aβ1-28, and Aβ1-42 in the gas phase and in aqueous solution. Our studies show that the overall structures, secondary structures, and the calculated thermodynamic properties change with increasing peptide size. In addition, we find that the structural properties of those peptides are different from each other in the gas phase and in aqueous solution.

Clinical Utility of Amyloid PET Imaging in the Differential Diagnosis of Atypical Dementias and Its Impact on Caregivers.

Science.gov (United States)

Bensaïdane, Mohamed Reda; Beauregard, Jean-Mathieu; Poulin, Stéphane; Buteau, François-Alexandre; Guimond, Jean; Bergeron, David; Verret, Louis; Fortin, Marie-Pierre; Houde, Michèle; Bouchard, Rémi W; Soucy, Jean-Paul; Laforce, Robert

2016-04-18

Recent studies have supported a role for amyloid positron emission tomography (PET) imaging in distinguishing Alzheimer's disease (AD) pathology from other pathological protein accumulations leading to dementia. We investigated the clinical utility of amyloid PET in the differential diagnosis of atypical dementia cases and its impact on caregivers. Using the amyloid tracer 18F-NAV4694, we prospectively scanned 28 patients (mean age 59.3 y, s.d. 5.8; mean MMSE 21.4, s.d. 6.0) with an atypical dementia syndrome. Following a comprehensive diagnostic workup (i.e., history taking, neurological examination, blood tests, neuropsychological evaluation, MRI, and FDG-PET), no certain diagnosis could be arrived at. Amyloid PET was then conducted and classified as positive or negative. Attending physicians were asked to evaluate whether this result led to a change in diagnosis or altered management. They also reported their degree of confidence in the diagnosis. Caregivers were met after disclosure of amyloid PET results and completed a questionnaire/interview to assess the impact of the scan. Our cohort was evenly divided between positive (14/28) and negative (14/28) 18F-NAV4694 cases. Amyloid PET resulted in a diagnostic change in 9/28 cases (32.1%: 17.8% changed from AD to non-AD, 14.3% from non-AD to AD). There was a 44% increase in diagnostic confidence. Altered management occurred in 71.4% (20/28) of cases. Knowledge of amyloid status improved caregivers' outcomes in all domains (anxiety, depression, disease perception, future anticipation, and quality of life). This study suggests a useful additive role for amyloid PET in atypical cases with an unclear diagnosis beyond the extensive workup of a tertiary memory clinic. Amyloid PET increased diagnostic confidence and led to clinically significant alterations in management. The information gained from that test was well received by caregivers and encouraged spending quality time with their loved ones.

β-Hairpin of Islet Amyloid Polypeptide Bound to an Aggregation Inhibitor

Science.gov (United States)

Mirecka, Ewa A.; Feuerstein, Sophie; Gremer, Lothar; Schröder, Gunnar F.; Stoldt, Matthias; Willbold, Dieter; Hoyer, Wolfgang

2016-01-01

In type 2 diabetes, the formation of islet amyloid consisting of islet amyloid polypeptide (IAPP) is associated with reduction in β-cell mass and contributes to the failure of islet cell transplantation. Rational design of inhibitors of IAPP amyloid formation has therapeutic potential, but is hampered by the lack of structural information on inhibitor complexes of the conformationally flexible, aggregation-prone IAPP. Here we characterize a β-hairpin conformation of IAPP in complex with the engineered binding protein β-wrapin HI18. The β-strands correspond to two amyloidogenic motifs, 12-LANFLVH-18 and 22-NFGAILS-28, which are connected by a turn established around Ser-20. Besides backbone hydrogen bonding, the IAPP:HI18 interaction surface is dominated by non-polar contacts involving hydrophobic side chains of the IAPP β-strands. Apart from monomers, HI18 binds oligomers and fibrils and inhibits IAPP aggregation and toxicity at low substoichiometric concentrations. The IAPP β-hairpin can serve as a molecular recognition motif enabling control of IAPP aggregation. PMID:27641459

The development of cerebral amyloid angiopathy in cerebral vessels. A review with illustrations based upon own investigated post mortem cases.

Science.gov (United States)

Mendel, T A; Wierzba-Bobrowicz, T; Lewandowska, E; Stępień, T; Szpak, G M

2013-12-01

The process of β-amyloid accumulation in cerebral vessels is presented. Cerebral amyloid angiopathy (CAA) was confirmed during an autopsy. It was diagnosed according to the Boston criteria. Cerebral amyloid angiopathy can involve all kinds of cerebral vessels (cortical and leptomeningeal arterioles, capillaries and veins). The development of CAA is a progressive process. β-amyloid appears first in the tunica media, surrounding smooth muscle cells, and in the adventitia. β-amyloid is progressively accumulated, causing a gradual loss of smooth muscle cells in the vessel wall and finally replacing them. Then, the detachment and delamination of the outer part of the tunica media results in the "double barrel" appearance, fibrinoid necrosis, and microaneurysm formation. Microbleeding with perivascular deposition of erythrocytes and blood breakdown products can also occur. β-amyloid can also be deposited in the surrounding of the affected vessels of the brain parenchyma, known as "dysphoric CAA". Ultrastructurally, when deposits of amyloid fibers were localized in or outside the arteriolar wall, the degenerating vascular smooth muscle cells were observed. In the Institute of Psychiatry and Neurology the study was carried out in a group of 48 patients who died due to intracerebral hemorrhage caused by sporadic CAA.

Amyloid precursor protein overexpression depresses excitatory transmission through both presynaptic and postsynaptic mechanisms

OpenAIRE

Ting, Jonathan T.; Kelley, Brooke G.; Lambert, Talley J.; Cook, David G.; Sullivan, Jane M.

2006-01-01

Overexpression of the amyloid precursor protein (APP) in hippocampal neurons leads to elevated β-amyloid peptide (Aβ) production and consequent depression of excitatory transmission. The precise mechanisms underlying APP-induced synaptic depression are poorly understood. Uncovering these mechanisms could provide insight into how neuronal function is compromised before cell death during the early stages of Alzheimer's disease. Here we verify that APP up-regulation leads to depression of transm...

Social inclusion and inclusive education

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Marsela Robo

2014-07-01

In line with global debate on social inclusion and exclusion, the author brings the way this debate has now pervaded both the official and development policy discourse in Albania.Social inclusion is considered as one of the priorities of the current government, with poverty reduction as its main focus, which will be ensured not only through economic development. In the end, the article focuses on the role of education as a very important and useful tool for ensuring social inclusion.Social inclusion through education, in particular through vocational education, considered by the author as the only way towards sustainable development of Albanian society.

A Cultivated Form of a Red Seaweed (Chondrus crispus, Suppresses β-Amyloid-Induced Paralysis in Caenorhabditis elegans

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Jatinder Singh Sangha

2015-10-01

Full Text Available We report here the protective effects of a methanol extract from a cultivated strain of the red seaweed, Chondrus crispus, against β-amyloid-induced toxicity, in a transgenic Caenorhabditis elegans, expressing human Aβ1-42 gene. The methanol extract of C. crispus (CCE, delayed β-amyloid-induced paralysis, whereas the water extract (CCW was not effective. The CCE treatment did not affect the transcript abundance of amy1; however, Western blot analysis revealed a significant decrease of Aβ species, as compared to untreated worms. The transcript abundance of stress response genes; sod3, hsp16.2 and skn1 increased in CCE-treated worms. Bioassay guided fractionation of the CCE yielded a fraction enriched in monogalactosyl diacylglycerols (MGDG that significantly delayed the onset of β-amyloid-induced paralysis. Taken together, these results suggested that the cultivated strain of C. crispus, whilst providing dietary nutritional value, may also have significant protective effects against β-amyloid-induced toxicity in C. elegans, partly through reduced β-amyloid species, up-regulation of stress induced genes and reduced accumulation of reactive oxygen species (ROS.

Semen amyloids participate in spermatozoa selection and clearance.

Science.gov (United States)

Roan, Nadia R; Sandi-Monroy, Nathallie; Kohgadai, Nargis; Usmani, Shariq M; Hamil, Katherine G; Neidleman, Jason; Montano, Mauricio; Ständker, Ludger; Röcker, Annika; Cavrois, Marielle; Rosen, Jared; Marson, Kara; Smith, James F; Pilcher, Christopher D; Gagsteiger, Friedrich; Sakk, Olena; O'Rand, Michael; Lishko, Polina V; Kirchhoff, Frank; Münch, Jan; Greene, Warner C

2017-06-27

Unlike other human biological fluids, semen contains multiple types of amyloid fibrils in the absence of disease. These fibrils enhance HIV infection by promoting viral fusion to cellular targets, but their natural function remained unknown. The similarities shared between HIV fusion to host cell and sperm fusion to oocyte led us to examine whether these fibrils promote fertilization. Surprisingly, the fibrils inhibited fertilization by immobilizing sperm. Interestingly, however, this immobilization facilitated uptake and clearance of sperm by macrophages, which are known to infiltrate the female reproductive tract (FRT) following semen exposure. In the presence of semen fibrils, damaged and apoptotic sperm were more rapidly phagocytosed than healthy ones, suggesting that deposition of semen fibrils in the lower FRT facilitates clearance of poor-quality sperm. Our findings suggest that amyloid fibrils in semen may play a role in reproduction by participating in sperm selection and facilitating the rapid removal of sperm antigens.

A proteomic approach for the diagnosis of bacterial meningitis.

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Sarah Jesse

Full Text Available BACKGROUND: The discrimination of bacterial meningitis (BM versus viral meningitis (VM shapes up as a problem, when laboratory data are not equivocal, in particular, when Gram stain is negative. METHODOLOGY/PRINCIPAL FINDINGS: With the aim to determine reliable marker for bacterial or viral meningitis, we subjected cerebrospinal fluid (CSF to a quantitative proteomic screening. By using a recently established 2D-DIGE protocol which was adapted to the individual CSF flow, we compared a small set of patients with proven BM and VM. Thereby, we identified six potential biomarkers out of which Prostaglandin-H2 D-isomerase was already described in BM, showing proof of concept. In the subsequent validation phase on a more comprehensive collective of 80 patients, we could validate that in BM high levels of glial fibrillary acidic protein (GFAP and low levels of soluble amyloid precursor protein alpha/beta (sAPPalpha/beta are present as possible binding partner of Fibulin-1. CONCLUSIONS/SIGNIFICANCE: We conclude that our CSF flow-adapted 2D-DIGE protocol is valid especially in comparing samples with high differences in total protein and suppose that GFAP and sAPPalpha/beta have a high potential as additional diagnostic markers for differentiation of BM from VM. In the clinical setting, this might lead to an improved early diagnosis and to an individual therapy.

Engineered aggregation inhibitor fusion for production of highly amyloidogenic human islet amyloid polypeptide.

Science.gov (United States)

Mirecka, Ewa Agnieszka; Gremer, Lothar; Schiefer, Stephanie; Oesterhelt, Filipp; Stoldt, Matthias; Willbold, Dieter; Hoyer, Wolfgang

2014-12-10

Human islet amyloid polypeptide (IAPP) is the major component of pancreatic amyloid deposits in type 2 diabetes. The structural conversion of IAPP from a monomeric state into amyloid assemblies is the subject of intense research. Recombinant production of IAPP is, however, difficult due to its extreme aggregation propensity. Here we describe a novel strategy for expression of IAPP in Escherichia coli, based on an engineered protein tag, which sequesters IAPP monomers and prevents IAPP aggregation. The IAPP-binding protein HI18 was selected by phage display from a β-wrapin library. Fusion of HI18 to IAPP enabled the soluble expression of the construct. IAPP was cleaved from the fusion construct and purified to homogeneity with a yield of 3mg of isotopically labeled peptide per liter of culture. In the monomeric state, IAPP was largely disordered as evidenced by far-UV CD and liquid-state NMR spectroscopy but competent to form amyloid fibrils according to atomic force microscopy. These results demonstrate the ability of the engineered β-wrapin HI18 for shielding the hydrophobic sequence of IAPP during expression and purification. Fusion of aggregation-inhibiting β-wrapins is a suitable approach for the recombinant production of aggregation-prone proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

Cellular and substrate adhesion molecules (integrins) and their ligands in cerebral amyloid plaques in Alzheimer's disease

NARCIS (Netherlands)

Eikelenboom, P.; Zhan, S. S.; Kamphorst, W.; van der Valk, P.; Rozemuller, J. M.

1994-01-01

Integrins belonging to different subfamilies can be identified immunohistochemically in cerebral amyloid plaques. Monoclonal antibodies against the VLA family beta 1-integrins show staining of the corona of classical amyloid plaques for beta 1, alpha 3 and alpha 6. Immunostaining reveal also the

Human amyloid beta protein gene locus: HaeIII RFLP

Energy Technology Data Exchange (ETDEWEB)

Taylor, J E; Gonzalez-DeWhitt, P A; Fuller, F; Cordell, B; Frossard, P M [California Biotechnology Inc., Mountain View (USA); Tinklenberg, J R; Davies, H D; Eng, L F; Yesavage, J A [Stanford Univ. School of Medicine, Palo Alto, CA (USA)

1988-07-25

A 2.2 kb EcoRI-EcoRI fragment from the 5{prime} end of the human amyloid beta protein cDNA was isolated from a human fibroblast cDNA library and subcloned into pGEM3. HaeIII (GGCC) detects 6 invariant bands at 0.5 kb, 1.0 kb, 1.1 kb, 1.3 kb, 1.4 kb and 1.6 kb and a two-allele polymorphism with bands at either 1.9 kb or 2.1 kb. Its frequency was studied in 50 North Americans. Human amyloid beta protein gene mapped to the long arm of chromosome 21 (21q11.2-21q21) by Southern blot analysis of human-rodent somatic cell hybrids. Co-dominant segregation was observed in two families (15 individuals).

Quantifying the pattern of beta/A4 amyloid protein distribution in Alzheimer's disease by image analysis.

Science.gov (United States)

Bruce, C V; Clinton, J; Gentleman, S M; Roberts, G W; Royston, M C

1992-04-01

We have undertaken a study of the distribution of the beta/A4 amyloid deposited in the cerebral cortex in Alzheimer's disease. Previous studies which have examined the differential distribution of amyloid in the cortex in order to determine the laminar pattern of cortical pathology have not proved to be conclusive. We have developed an alternative method for the solution of this problem. It involves the immunostaining of sections followed by computer-enhanced image analysis. A mathematical model is then used to describe both the amount and the pattern of amyloid across the cortex. This method is both accurate and reliable and also removes many of the problems concerning inter and intra-rater variability in measurement. This method will provide the basis for further quantitative studies on the differential distribution of amyloid in Alzheimer's disease and other cases of dementia where cerebral amyloidosis occurs.

Simultaneous measurement of amyloid fibril formation by dynamic light scattering and fluorescence reveals complex aggregation kinetics.

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Aaron M Streets

Full Text Available An apparatus that combines dynamic light scattering and Thioflavin T fluorescence detection is used to simultaneously probe fibril formation in polyglutamine peptides, the aggregating subunit associated with Huntington's disease, in vitro. Huntington's disease is a neurodegenerative disorder in a class of human pathologies that includes Alzheimer's and Parkinson's disease. These pathologies are all related by the propensity of their associated protein or polypeptide to form insoluble, β-sheet rich, amyloid fibrils. Despite the wide range of amino acid sequence in the aggregation prone polypeptides associated with these diseases, the resulting amyloids display strikingly similar physical structure, an observation which suggests a physical basis for amyloid fibril formation. Thioflavin T fluorescence reports β-sheet fibril content while dynamic light scattering measures particle size distributions. The combined techniques allow elucidation of complex aggregation kinetics and are used to reveal multiple stages of amyloid fibril formation.

Covalent Tethering and Residues with Bulky Hydrophobic Side Chains Enable Self-Assembly of Distinct Amyloid Structures.

Science.gov (United States)

Ruiz, Jérémy; Boehringer, Régis; Grogg, Marcel; Raya, Jésus; Schirer, Alicia; Crucifix, Corinne; Hellwig, Petra; Schultz, Patrick; Torbeev, Vladimir

2016-12-02

Polymorphism is a common property of amyloid fibers that complicates their detailed structural and functional studies. Here we report experiments illustrating the chemical principles that enable the formation of amyloid polymorphs with distinct stoichiometric composition. Using appropriate covalent tethering we programmed self-assembly of a model peptide corresponding to the [20-41] fragment of human β2-microglobulin into fibers with either trimeric or dimeric amyloid cores. Using a set of biophysical and biochemical methods we demonstrated their distinct structural, morphological, and templating properties. Furthermore, we showed that supramolecular approaches in which the peptide is modified with bulky substituents can also be applied to modulate the formation of different fiber polymorphs. Such strategies, when applied to disease-related peptides and proteins, will greatly help in the evaluation of the biological properties of structurally distinct amyloids. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Differential regulation of amyloid-β-protein mRNA expression within hippocampal neuronal subpopulations in Alzheimer disease

International Nuclear Information System (INIS)

Higgins, G.A.; Lewis, D.A.; Bahmanyar, S.; Goldgaber, D.; Gajdusek, D.C.; Young, W.G.; Morrison, J.H.; Wilson, M.C.

1988-01-01

The authors have mapped the neuroanatomical distribution of amyloid-β-protein mRNA within neuronal subpopulations of the hippocampal formation in the cynomolgus monkey (Macaca fascicularis), normal aged human, and patients with Alzheimer disease. Amyloid-β-protein mRNA appears to be expressed in all hippocampal neurons, but at different levels of abundance. In the central nervous system of monkey and normal aged human, image analysis shows that neurons of the dentate gyrus and cornu Ammonis fields contain a 2.5-times-greater hybridization signal than is present in neurons of the subiculum and entorhinal cortex. In contrast, in the Alzheimer disease hippocampal formation, the levels of amyloid-β-protein mRNA in the cornu Ammonis field 3 and parasubiculum are equivalent. These findings suggest that within certain neuronal subpopulations cell type-specific regulation of amyloid-β-protein gene expression may be altered in Alzheimer disease

Alzheimer’s disease: How metal ions define β-amyloid function

DEFF Research Database (Denmark)

Kepp, Kasper Planeta

2017-01-01

focuses on the essential coordination chemistry and biochemistry that relate transition metal ions iron, copper, and zinc to β-amyloid (Aβ) and most likely define the peptide's roles in neurons. The metal-Aβ interactions have elements of both gain of toxic function, as usually considered, but also loss......Alzheimer’s disease is increasingly recognized to be linked to the function and status of metal ions, and recently, the amyloid hypothesis has been strongly intertwined with the metal ion hypothesis; in fact, these two hypotheses fit well together and are not mutually contradictory. This review...... of natural functions, as emphasized in this review. Both these aspects and their relationships are discussed and their implications for future therapeutic strategies are outlined....

Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases

OpenAIRE

Parvez Alam; Sumit Kumar Chaturvedi; Mohammad Khursheed Siddiqi; Ravi Kant Rajpoot; Mohd Rehan Ajmal; Masihuz Zaman; Rizwan Hasan Khan

2016-01-01

Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer?s, Parkinson?s and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and A?-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demons...

How ionic strength affects the conformational behavior of human and rat beta amyloids--a computational study.

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Zdeněk Kříž

Full Text Available Progressive cerebral deposition of amyloid beta occurs in Alzheimers disease and during the aging of certain mammals (human, monkey, dog, bear, cow, cat but not others (rat, mouse. It is possibly due to different amino acid sequences at positions 5, 10 and 13. To address this issue, we performed series of 100 ns long trajectories (each trajectory was run twice with different initial velocity distribution on amyloid beta (1-42 with the human and rat amino acid sequence in three different environments: water with only counter ions, water with NaCl at a concentration of 0.15 M as a model of intracellular Na(+ concentration at steady state, and water with NaCl at a concentration of 0.30 M as a model of intracellular Na(+ concentration under stimulated conditions. We analyzed secondary structure stability, internal hydrogen bonds, and residual fluctuation. It was observed that the change in ionic strength affects the stability of internal hydrogen bonds. Increasing the ionic strength increases atomic fluctuation in the hydrophobic core of the human amyloid, and decreases the atomic fluctuation in the case of rat amyloid. The secondary structure analyses show a stable α-helix part between residues 10 and 20. However, C-terminus of investigated amyloids is much more flexible showing no stable secondary structure elements. Increasing ionic strength of the solvent leads to decreasing stability of the secondary structural elements. The difference in conformational behavior of the three amino acids at position 5, 10 and 13 for human and rat amyloids significantly changes the conformational behavior of the whole peptide.

Carbon nanospecies affecting amyloid formation

Czech Academy of Sciences Publication Activity Database

Holubová, Monika; Konefal, Rafal; Morávková, Zuzana; Zhigunov, Alexander; Svoboda, Jan; Pop-Georgievski, Ognen; Hromádková, Jiřina; Groborz, Ondřej; Štěpánek, Petr; Hrubý, Martin

2017-01-01

Roč. 7, č. 85 (2017), s. 53887-53898 ISSN 2046-2069 R&D Projects: GA MŠk(CZ) LM2015064; GA MZd(CZ) NV16-30544A; GA ČR(CZ) GA16-03156S; GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1507 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : amyloid fibril * nanodiamond * fullerene Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.108, year: 2016

The Nucleation of Protein Aggregates - From Crystals to Amyloid Fibrils.

Science.gov (United States)

Buell, Alexander K

2017-01-01

The condensation and aggregation of individual protein molecules into dense insoluble phases is of relevance in such diverse fields as materials science, medicine, structural biology and pharmacology. A common feature of these condensation phenomena is that they usually are nucleated processes, i.e. the first piece of the condensed phase is energetically costly to create and hence forms slowly compared to its subsequent growth. Here we give a compact overview of the differences and similarities of various protein nucleation phenomena, their theoretical description in the framework of colloid and polymer science and their experimental study. Particular emphasis is put on the nucleation of a specific type of filamentous protein aggregates, amyloid fibrils. The current experimentally derived knowledge on amyloid fibril nucleation is critically assessed, and we argue that it is less advanced than is generally believed. This is due to (I) the lack of emphasis that has been put on the distinction between homogeneous and heterogeneous nucleation in experimental studies (II) the use of oversimplifying and/or inappropriate theoretical frameworks for the analysis of kinetic data of amyloid fibril nucleation. A strategy is outlined and advocated of how our understanding of this important class of processes can be improved in the future. © 2017 Elsevier Inc. All rights reserved.

Dynamic relationships between age, amyloid-β deposition, and glucose metabolism link to the regional vulnerability to Alzheimer’s disease

Science.gov (United States)

Madison, Cindee; Baker, Suzanne; Rabinovici, Gil; Jagust, William

2016-01-01

Abstract See Hansson and Gouras (doi:10.1093/aww146) for a scientific commentary on this article. Although some brain regions such as precuneus and lateral temporo-parietal cortex have been shown to be more vulnerable to Alzheimer’s disease than other areas, a mechanism underlying the differential regional vulnerability to Alzheimer’s disease remains to be elucidated. Using fluorodeoxyglucose and Pittsburgh compound B positron emission tomography imaging glucose metabolism and amyloid-β deposition, we tested whether and how life-long changes in glucose metabolism relate to amyloid-β deposition and Alzheimer’s disease-related hypometabolism. Nine healthy young adults (age range: 20–30), 96 cognitively normal older adults (age range: 61–96), and 20 patients with Alzheimer’s disease (age range: 50–90) were scanned using fluorodeoxyglucose and Pittsburgh compound B positron emission tomography. Among cognitively normal older subjects, 32 were further classified as amyloid-positive, with 64 as amyloid-negative. To assess the contribution of glucose metabolism to the regional vulnerability to amyloid-β deposition, we defined the highest and lowest metabolic regions in young adults and examined differences in amyloid deposition between these regions across groups. Two-way analyses of variance were conducted to assess regional differences in age and amyloid-β-related changes in glucose metabolism. Multiple regressions were applied to examine the association between amyloid-β deposition and regional glucose metabolism. Both region of interest and whole-brain voxelwise analyses were conducted to complement and confirm the results derived from the other approach. Regional differences in glucose metabolism between the highest and lowest metabolism regions defined in young adults (T = 12.85, P glucose metabolism regions defined in young adults (T = 2.05, P glucose metabolism were found such that frontal glucose metabolism was reduced with age, while glucose

Interferon-γ increases neuronal death in response to amyloid-β1-42

Directory of Open Access Journals (Sweden)

Williams Alun

2006-03-01

Full Text Available Abstract Background Alzheimer's disease is a neurodegenerative disorder characterized by a progressive cognitive impairment, the consequence of neuronal dysfunction and ultimately the death of neurons. The amyloid hypothesis proposes that neuronal damage results from the accumulation of insoluble, hydrophobic, fibrillar peptides such as amyloid-β1-42. These peptides activate enzymes resulting in a cascade of second messengers including prostaglandins and platelet-activating factor. Apoptosis of neurons is thought to follow as a consequence of the uncontrolled release of second messengers. Biochemical, histopathological and genetic studies suggest that pro-inflammatory cytokines play a role in neurodegeneration during Alzheimer's disease. In the current study we examined the effects of interferon (IFN-γ, tumour necrosis factor (TNFα, interleukin (IL-1β and IL-6 on neurons. Methods Primary murine cortical or cerebellar neurons, or human SH-SY5Y neuroblastoma cells, were grown in vitro. Neurons were treated with cytokines prior to incubation with different neuronal insults. Cell survival, caspase-3 activity (a measure of apoptosis and prostaglandin production were measured. Immunoblots were used to determine the effects of cytokines on the levels of cytoplasmic phospholipase A2 or phospholipase C γ-1. Results While none of the cytokines tested were directly neurotoxic, pre-treatment with IFN-γ sensitised neurons to the toxic effects of amyloid-β1-42 or HuPrP82-146 (a neurotoxic peptide found in prion diseases. The effects of IFN-γ were seen on cortical and cerebellar neurons, and on SH-SY5Y neuroblastoma cells. However, pre-treatment with IFN-γ did not affect the sensitivity to neurons treated with staurosporine or hydrogen peroxide. Pre-treatment with IFN-γ increased the levels of cytoplasmic phospholipase A2 in SH-SY5Y cells and increased prostaglandin E2 production in response to amyloid-β1-42. Conclusion Treatment of neuronal cells

Quantification of amyloid-beta 40 in cerebrospinal fluid

NARCIS (Netherlands)

Verwey, N.A.; Veerhuis, R.; Twaalfhoven, H.A.M.; Wouters, D.; Hoozemans, J.J.M.; Bollen, Y.J.M.; Killestein, J.; Bibl, M.; Wiltfang, J.; Hack, C.E.; Scheltens, P.; Blankenstein, M.A.

2009-01-01

Background: Truncated forms and full-length forms of the amyloid-beta 40 (Aβ40) are key molecules in the pathogenesis of dementia, and are detectable in CSF. Reliable methods to detect these biomarkers in CSF are of great importance for understanding the disease mechanisms and for diagnostic

Human serum amyloid genes--molecular characterization

International Nuclear Information System (INIS)

Sack, G.H.; Lease, J.J.

1986-01-01

Three clones containing human genes for serum amyloid A protein (SAA) have been isolated and characterized. Each of two clones, GSAA 1 and 2 (of 12.8 and 15.9 kilobases, respectively), contains two exons, accouting for amino acids 12-58 and 58-103 of mature SAA; the extreme 5' termini and 5' untranslated regions have not yet been defined but are anticipated to be close based on studies of murine SAA genes. Initial amino acid sequence comparisons show 78/89 identical residues. At 4 of the 11 discrepant residues, the amino acid specified by the codon is the same as the corresponding residue in murine SAA. Identification of regions containing coding regions has permitted use of selected subclones for blot hybridization studies of larger human SAA chromosomal gene organization. The third clone, GSAA 3 also contains SAA coding information by DNA sequence analysis but has a different organization which has not yet been fully described. We have reported the isolation of clones of human DNA hybridizing with pRS48 - a plasmid containing a complementary DNA (cDNA) clone for murine serum amyloid A (SAA; 1, 2). We now present more detailed data confirming the identity and defining some of the organizational features of these clones

Schisandrin B protects PC12 cells by decreasing the expression of amyloid precursor protein and vacuolar protein sorting 35★

Science.gov (United States)

Yan, Mingmin; Mao, Shanping; Dong, Huimin; Liu, Baohui; Zhang, Qian; Pan, Gaofeng; Fu, Zhiping

2012-01-01

PC12 cell injury was induced using 20 μM amyloid β-protein 25–35 to establish a model of Alzheimer's disease. The cells were then treated with 5, 10, and 25 μM Schisandrin B. Methylthiazolyldiphenyl-tetrazolium bromide assays and Hoechst 33342 staining results showed that with increasing Schisandrin B concentration, the survival rate of PC12 cells injured by amyloid β-protein 25–35 gradually increased and the rate of apoptosis gradually decreased. Reverse transcription-PCR, immunocytochemical staining and western blot results showed that with increasing Schisandrin B concentration, the mRNA and protein expression of vacuolar protein sorting 35 and amyloid precursor protein were gradually decreased. Vacuolar protein sorting 35 and amyloid precursor protein showed a consistent trend for change. These findings suggest that 5, 10, and 25 μM Schisandrin B antagonizes the cellular injury induced by amyloid β-protein 25–35 in a dose-dependent manner. This may be caused by decreasing the expression of vacuolar protein sorting 35 and amyloid precursor protein. PMID:25745458

Broad neutralization of calcium-permeable amyloid pore channels with a chimeric Alzheimer/Parkinson peptide targeting brain gangliosides.

Science.gov (United States)

Di Scala, Coralie; Yahi, Nouara; Flores, Alessandra; Boutemeur, Sonia; Kourdougli, Nazim; Chahinian, Henri; Fantini, Jacques

2016-02-01

Growing evidence supports a role for brain gangliosides in the pathogenesis of neurodegenerative diseases including Alzheimer's and Parkinson's. Recently we deciphered the ganglioside-recognition code controlling specific ganglioside binding to Alzheimer's β-amyloid (Aβ1-42) peptide and Parkinson's disease-associated protein α-synuclein. Cracking this code allowed us to engineer a short chimeric Aβ/α-synuclein peptide that recognizes all brain gangliosides. Here we show that ganglioside-deprived neural cells do no longer sustain the formation of zinc-sensitive amyloid pore channels induced by either Aβ1-42 or α-synuclein, as assessed by single-cell Ca(2+) fluorescence microscopy. Thus, amyloid channel formation, now considered a key step in neurodegeneration, is a ganglioside-dependent process. Nanomolar concentrations of chimeric peptide competitively inhibited amyloid pore formation induced by Aβ1-42 or α-synuclein in cultured neural cells. Moreover, this peptide abrogated the intracellular calcium increases induced by Parkinson's-associated mutant forms of α-synuclein (A30P, E46K and A53T). The chimeric peptide also prevented the deleterious effects of Aβ1-42 on synaptic vesicle trafficking and decreased the Aβ1-42-induced impairment of spontaneous activity in rat hippocampal slices. Taken together, these data show that the chimeric peptide has broad anti-amyloid pore activity, suggesting that a common therapeutic strategy based on the prevention of amyloid-ganglioside interactions is a reachable goal for both Alzheimer's and Parkinson's diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Beta-secretase-cleaved amyloid precursor protein in Alzheimer brain: a morphologic study

DEFF Research Database (Denmark)

Sennvik, Kristina; Bogdanovic, N; Volkmann, Inga

2004-01-01

beta-amyloid (Abeta) is the main constituent of senile plaques seen in Alzheimer's disease. Abeta is derived from the amyloid precursor protein (APP) via proteolytic cleavage by proteases beta- and gamma-secretase. In this study, we examined content and localization of beta-secretase-cleaved APP...... the beta-sAPP immunostaining to be stronger and more extensive in gray matter in Alzheimer disease (AD) cases than controls. The axonal beta-sAPP staining was patchy and unevenly distributed for the AD cases, indicating impaired axonal transport. beta-sAPP was also found surrounding senile plaques...

Benzothiazole aniline tetra(ethylene glycol) and 3-amino-1,2,4-triazole inhibit neuroprotection against amyloid peptides by catalase overexpression in vitro.

Science.gov (United States)

Chilumuri, Amrutha; Odell, Mark; Milton, Nathaniel G N

2013-11-20

Alzheimer's disease, Familial British dementia, Familial Danish dementia, Type 2 diabetes mellitus, plus Creutzfeldt-Jakob disease are associated with amyloid fibril deposition and oxidative stress. The antioxidant enzyme catalase is a neuroprotective amyloid binding protein. Herein the effects of catalase overexpression in SH-SY5Y neuronal cells on the toxicity of amyloid-β (Aβ), amyloid-Bri (ABri), amyloid-Dan (ADan), amylin (IAPP), and prion protein (PrP) peptides were determined. Results showed catalase overexpression was neuroprotective against Aβ, ABri, ADan, IAPP, and PrP peptides. The catalase inhibitor 3-amino-1,2,4-triazole (3-AT) and catalase-amyloid interaction inhibitor benzothiazole aniline tetra(ethylene glycol) (BTA-EG4) significantly enhanced neurotoxicity of amyloid peptides in catalase overexpressing neuronal cells. This suggests catalase neuroprotection involves breakdown of hydrogen peroxide (H2O2) plus a direct binding interaction between catalase and the Aβ, ABri, ADan, IAPP, and PrP peptides. Kisspeptin 45-50 had additive neuroprotective actions against the Aβ peptide in catalase overexpressing cells. The effects of 3-AT had an intracellular site of action, while catalase-amyloid interactions had an extracellular component. These results suggest that the 3-AT and BTA-EG4 compounds may be able to inhibit endogenous catalase mediated neuroprotection. Use of BTA-EG4, or compounds that inhibit catalase binding to amyloid peptides, as potential therapeutics for Neurodegenerative diseases may therefore result in unwanted effects.

Benzothiazole Aniline Tetra(ethylene glycol) and 3-Amino-1,2,4-triazole Inhibit Neuroprotection against Amyloid Peptides by Catalase Overexpression in Vitro

Science.gov (United States)

2013-01-01

Alzheimer’s disease, Familial British dementia, Familial Danish dementia, Type 2 diabetes mellitus, plus Creutzfeldt-Jakob disease are associated with amyloid fibril deposition and oxidative stress. The antioxidant enzyme catalase is a neuroprotective amyloid binding protein. Herein the effects of catalase overexpression in SH-SY5Y neuronal cells on the toxicity of amyloid-β (Aβ), amyloid-Bri (ABri), amyloid-Dan (ADan), amylin (IAPP), and prion protein (PrP) peptides were determined. Results showed catalase overexpression was neuroprotective against Aβ, ABri, ADan, IAPP, and PrP peptides. The catalase inhibitor 3-amino-1,2,4-triazole (3-AT) and catalase-amyloid interaction inhibitor benzothiazole aniline tetra(ethylene glycol) (BTA-EG4) significantly enhanced neurotoxicity of amyloid peptides in catalase overexpressing neuronal cells. This suggests catalase neuroprotection involves breakdown of hydrogen peroxide (H2O2) plus a direct binding interaction between catalase and the Aβ, ABri, ADan, IAPP, and PrP peptides. Kisspeptin 45–50 had additive neuroprotective actions against the Aβ peptide in catalase overexpressing cells. The effects of 3-AT had an intracellular site of action, while catalase-amyloid interactions had an extracellular component. These results suggest that the 3-AT and BTA-EG4 compounds may be able to inhibit endogenous catalase mediated neuroprotection. Use of BTA-EG4, or compounds that inhibit catalase binding to amyloid peptides, as potential therapeutics for Neurodegenerative diseases may therefore result in unwanted effects. PMID:23968537

Glutamate system, amyloid β peptides and tau protein: functional interrelationships and relevance to Alzheimer disease pathology

Science.gov (United States)

Revett, Timothy J.; Baker, Glen B.; Jhamandas, Jack; Kar, Satyabrata

2013-01-01

Alzheimer disease is the most prevalent form of dementia globally and is characterized premortem by a gradual memory loss and deterioration of higher cognitive functions and postmortem by neuritic plaques containing amyloid β peptide and neurofibrillary tangles containing phospho-tau protein. Glutamate is the most abundant neurotransmitter in the brain and is essential to memory formation through processes such as long-term potentiation and so might be pivotal to Alzheimer disease progression. This review discusses how the glutamatergic system is impaired in Alzheimer disease and how interactions of amyloid β and glutamate influence synaptic function, tau phosphorylation and neurodegeneration. Interestingly, glutamate not only influences amyloid β production, but also amyloid β can alter the levels of glutamate at the synapse, indicating that small changes in the concentrations of both molecules could influence Alzheimer disease progression. Finally, we describe how the glutamate receptor antagonist, memantine, has been used in the treatment of individuals with Alzheimer disease and discuss its effectiveness. PMID:22894822

Orientation of aromatic residues in amyloid cores: Structural insights into prion fiber diversity

KAUST Repository

Reymer, Anna

2014-11-17

Structural conversion of one given protein sequence into different amyloid states, resulting in distinct phenotypes, is one of the most intriguing phenomena of protein biology. Despite great efforts the structural origin of prion diversity remains elusive, mainly because amyloids are insoluble yet noncrystalline and therefore not easily amenable to traditional structural-biology methods. We investigate two different phenotypic prion strains, weak and strong, of yeast translation termination factor Sup35 with respect to angular orientation of tyrosines using polarized light spectroscopy. By applying a combination of alignment methods the degree of fiber orientation can be assessed, which allows a relatively accurate determination of the aromatic ring angles. Surprisingly, the strains show identical average orientations of the tyrosines, which are evenly spread through the amyloid core. Small variations between the two strains are related to the local environment of a fraction of tyrosines outside the core, potentially reflecting differences in fibril packing.

Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth.

Science.gov (United States)

Foley, Joseph; Hill, Shannon E; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

2013-09-28

Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth

Science.gov (United States)

Foley, Joseph; Hill, Shannon E.; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

2013-09-01

Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

Amyloid PET imaging in Alzheimer's disease: a comparison of three radiotracers

Energy Technology Data Exchange (ETDEWEB)

Landau, S.M.; Jagust, W.J. [University of California, Berkeley, Helen Wills Neuroscience Institute, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, CA (United States); Thomas, B.A. [University College London, Institute of Nuclear Medicine, London (United Kingdom); Thurfjell, L. [GE Healthcare, Uppsala (Sweden); Schmidt, M. [Janssen Pharmaceutica, NV, Beerse (Belgium); Margolin, R. [Janssen Alzheimer Immunotherapy, South San Francisco, CA (United States); Mintun, M.; Pontecorvo, M. [Avid Radiopharmaceuticals, Inc., Philadelphia, PA (United States); Baker, S.L. [Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, CA (United States); Collaboration: The Alzheimer' s Disease Neuroimaging Initiative

2014-07-15

The increasing use of amyloid PET in Alzheimer's disease research and clinical trials has motivated efforts to standardize methodology. We compared retention of the {sup 11}C radiotracer Pittsburgh Compound B (PiB) and that of two {sup 18}F amyloid radiotracers (florbetapir and flutemetamol) using two study populations. We also examined the feasibility of converting between tracer-specific measures, using PiB as the common link between the two {sup 18}F tracers. One group of 40 subjects underwent PiB and flutemetamol imaging sessions and a separate group of 32 subjects underwent PiB and florbetapir imaging sessions. We compared cortical and white matter retention for each {sup 18}F tracer relative to that of PiB, as well as retention in several reference regions and image analysis methods. Correlations between tracer pairs were used to convert tracer-specific threshold values for amyloid positivity between tracers. Cortical retention for each pair of tracers was strongly correlated regardless of reference region (PiB-flutemetamol, ρ = 0.84-0.99; PiB-florbetapir, ρ = 0.83-0.97) and analysis method (ρ = 0.90-0.99). Compared to PiB, flutemetamol had higher white matter retention, while florbetapir had lower cortical retention. Two previously established independent thresholds for amyloid positivity were highly consistent when values were converted between tracer pairs. Despite differing white and grey matter retention characteristics, cortical retention for each {sup 18}F tracer was highly correlated with that of PiB, enabling conversion of thresholds across tracer measurement scales with a high level of internal consistency. Standardization of analysis methods and measurement scales may facilitate the comparison of amyloid PET data obtained using different tracers. (orig.)

Two-dimensional sum-frequency generation (2D SFG) spectroscopy: summary of principles and its application to amyloid fiber monolayers.

Science.gov (United States)

Ghosh, Ayanjeet; Ho, Jia-Jung; Serrano, Arnaldo L; Skoff, David R; Zhang, Tianqi; Zanni, Martin T

2015-01-01

By adding a mid-infrared pulse shaper to a sum-frequency generation (SFG) spectrometer, we have built a 2D SFG spectrometer capable of measuring spectra analogous to 2D IR spectra but with monolayer sensitivity and SFG selection rules. In this paper, we describe the experimental apparatus and provide an introduction to 2D SFG spectroscopy to help the reader interpret 2D SFG spectra. The main aim of this manuscript is to report 2D SFG spectra of the amyloid forming peptide FGAIL. FGAIL is a critical segment of the human islet amyloid polypeptide (hIAPP or amylin) that aggregates in people with type 2 diabetes. FGAIL is catalyzed into amyloid fibers by many types of surfaces. Here, we study the structure of FGAIL upon deposition onto a gold surface covered with a self-assembled monolayer of methyl-4-mercaptobenzoate (MMB) that produces an ester coating. FGAIL deposited on bare gold does not form ordered layers. The measured 2D SFG spectrum is consistent with amyloid fiber formation, exhibiting both the parallel (a+) and perpendicular (a-) symmetry modes associated with amyloid β-sheets. Cross peaks are observed between the ester stretches of the coating and the FGAIL peptides. Simulations are presented for two possible structures of FGAIL amyloid β-sheets that illustrate the sensitivity of the 2D SFG spectra to structure and orientation. These results provide some of the first molecular insights into surface catalyzed amyloid fiber structure.

Michler’s Hydrol Blue: A Sensitive Probe for Amyloid Fibril Detection

KAUST Repository

Kitts, Catherine C.

2011-05-03

Michler\\'s hydrol blue (MHB) is investigated with respect to photophysical properties in varied solvent environment and when bound to insulin and lysozyme fibrils. The MHB chromophore is shown to act like a molecular rotor and bind well to amyloid fibrils, where it exhibits a characteristic red-shift in its excitation spectrum and an increase in the emission quantum yield upon binding. MHB is more sensitive to environmental changes than Thioflavin T (ThT) and furthermore, in contrast to the latter amyloid probe, can differentiate between insulin and lysozyme fibrils by a more red-shifted excitation spectrum for insulin fibrils. To support the experimental observations, time-dependent density functional theory (TDDFT) calculations were performed on MHB at several levels of theory. The predicted changes of spectral properties as a function of the environment are in good agreement with the experimental results. Linear dichroism (LD) is used to determine the orientation of the MHB within the fibrils. It was shown through LD and molecular modeling that MHB aligns itself preferentially parallel with the amyloid fiber at an angle of 14°-22° to the fibril axis and along the grooves of the β-sheet. © 2011 American Chemical Society.

Evaluation of Sialic Acid and Acute Phase Proteins (Haptoglobin and Serum Amyloid A in Clinical and Subclinical Bovine Mastitis

Directory of Open Access Journals (Sweden)

S. Nazifi*, M. Haghkhah1, Z. Asadi, M. Ansari-Lari2, M. R. Tabandeh3, Z. Esmailnezhad and M. Aghamiri

2011-01-01

Full Text Available The present study was conducted to evaluate the concentrations of sialic acids (total, lipid bound and protein bound and their correlation with acute phase proteins (haptoglobin and serum amyloid A in clinical and subclinical mastitis of cattle. Thirty subclinical mastitic cows with positive California mastitis test (CMT test and no clinical signs of mastitis, 10 clinical mastitic cows and 10 healthy cows with negative CMT test and normal somatic cell count were selected. Milk and blood samples were collected after confirmation of clinical and subclinical mastitis by somatic cell count and bacterial identification. Serum haptoglobin (Hp, serum amyloid A (SAA, total sialic acid (TSA, lipid bound sialic acid (LBSA and protein bound sialic acid (PBSA were measured by validated standard methods. Haptoglobin and SAA increased significantly in both types of mastitis compared with control group (P<0.001. However, the ratio of HP/SAA was significantly different from the control group only in clinical mastitis. The results showed that TSA and LBSA were significantly different in control group compared with clinical and subclinical mastitis (P<0.001. Protein bound sialic acid did not change in subclinical mastitis in comparison with control group (P=0.86. There was positive correlation between LBSA and PBSA in clinical mastitis (r=0.72, P=0.02 whereas significant negative correlation was observed between LBSA and PBSA in subclinical mastitis (r=-0.62, P<0.001. Results also showed no correlation between Hp and SAA with each other or with any other parameters in study groups.

Beta-amyloid, cholinergní neurony a Alzheimerova choroba

Czech Academy of Sciences Publication Activity Database

Kašparová, Jana; Doležal, Vladimír

2002-01-01

Roč. 51, č. 2 (2002), s. 82-94 ISSN 0009-0557 R&D Projects: GA MZd NF5183; GA ČR GA305/01/0283 Institutional research plan: CEZ:AV0Z5011922 Keywords : Alzheimer 's disease * beta-amyloid * cholinergic neurons Subject RIV: FR - Pharmacology ; Medidal Chemistry

Gold Nanoparticles and Microwave Irradiation Inhibit Beta-Amyloid Amyloidogenesis

Directory of Open Access Journals (Sweden)

Bastus Neus

2008-01-01

Full Text Available Abstract Peptide-Gold nanoparticles selectively attached to β-amyloid protein (Aβ amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the Aβ aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer’s disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer’s disease.

Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Elena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Gath, Julia [ETH Zurich, Physical Chemistry (Switzerland); Habenstein, Birgit [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Ravotti, Francesco; Szekely, Kathrin; Huber, Matthias [ETH Zurich, Physical Chemistry (Switzerland); Buchner, Lena [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany); Boeckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS/Universite de Lyon 1, Institut de Biologie et Chimie des Proteines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Guentert, Peter, E-mail: guentert@em.uni-frankfurt.de [Goethe University Frankfurt am Main, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry (Germany)

2013-07-15

Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218-289) and {alpha}-synuclein yielded 88-97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77-90 % correctness if also assignments classified as tentative by the algorithm are included.

Pollution monitoring of coastal and estuarine areas: 1. Bacterial indicators along the south Gujarat Coast

Digital Repository Service at National Institute of Oceanography (India)

Mohandass, C.; Nair, S.; Achuthankutty, C.T.; LokaBharathi, P.A.

. Total coliforms and total vibrios were retrieved in 27 and 55 % of the samples. The validity of these bacterial groups as water quality indicators is discussed with statistical relations. It is sugested that inclusion of these groups could be made...

α-Synuclein Amyloids Hijack Prion Protein to Gain Cell Entry, Facilitate Cell-to-Cell Spreading and Block Prion Replication.

Science.gov (United States)

Aulić, Suzana; Masperone, Lara; Narkiewicz, Joanna; Isopi, Elisa; Bistaffa, Edoardo; Ambrosetti, Elena; Pastore, Beatrice; De Cecco, Elena; Scaini, Denis; Zago, Paola; Moda, Fabio; Tagliavini, Fabrizio; Legname, Giuseppe

2017-08-30

The precise molecular mechanism of how misfolded α-synuclein (α-Syn) accumulates and spreads in synucleinopathies is still unknown. Here, we show the role of the cellular prion protein (PrP C ) in mediating the uptake and the spread of recombinant α-Syn amyloids. The in vitro data revealed that the presence of PrP C fosters the higher uptake of α-Syn amyloid fibrils, which was also confirmed in vivo in wild type (Prnp +/+ ) compared to PrP knock-out (Prnp -/- ) mice. Additionally, the presence of α-Syn amyloids blocked the replication of scrapie prions (PrP Sc ) in vitro and ex vivo, indicating a link between the two proteins. Indeed, whilst PrP C is mediating the internalization of α-Syn amyloids, PrP Sc is not able to replicate in their presence. This observation has pathological relevance, since several reported case studies show that the accumulation of α-Syn amyloid deposits in Creutzfeldt-Jakob disease patients is accompanied by a longer disease course.

Arf6 controls beta-amyloid production by regulating macropinocytosis of the Amyloid Precursor Protein to lysosomes.

Science.gov (United States)

Tang, Weihao; Tam, Joshua H K; Seah, Claudia; Chiu, Justin; Tyrer, Andrea; Cregan, Sean P; Meakin, Susan O; Pasternak, Stephen H

2015-07-14

Alzheimer's disease (AD) is characterized by the deposition of Beta-Amyloid (Aβ) peptides in the brain. Aβ peptides are generated by cleavage of the Amyloid Precursor Protein (APP) by the β - and γ - secretase enzymes. Although this process is tightly linked to the internalization of cell surface APP, the compartments responsible are not well defined. We have found that APP can be rapidly internalized from the cell surface to lysosomes, bypassing early and late endosomes. Here we show by confocal microscopy and electron microscopy that this pathway is mediated by macropinocytosis. APP internalization is enhanced by antibody binding/crosslinking of APP suggesting that APP may function as a receptor. Furthermore, a dominant negative mutant of Arf6 blocks direct transport of APP to lysosomes, but does not affect classical endocytosis to endosomes. Arf6 expression increases through the hippocampus with the development of Alzheimer's disease, being expressed mostly in the CA1 and CA2 regions in normal individuals but spreading through the CA3 and CA4 regions in individuals with pathologically diagnosed AD. Disruption of lysosomal transport of APP reduces both Aβ40 and Aβ42 production by more than 30 %. Our findings suggest that the lysosome is an important site for Aβ production and that altering APP trafficking represents a viable strategy to reduce Aβ production.

Visuospatial Functioning in Cerebral Amyloid Angiopathy : A Pilot Study

NARCIS (Netherlands)

Valenti, Raffaella; Charidimou, Andreas; Xiong, Li; Boulouis, Gregoire; Fotiadis, Panagiotis; Ayres, Alison; Riley, Grace; Kuijf, Hugo J.; Reijmer, Yael D.; Pantoni, Leonardo; Gurol, M. Edip; Davidsdottir, Sigurros; Greenberg, Steven M.; Viswanathan, Anand

2017-01-01

Cerebral amyloid angiopathy (CAA) is a contributor to cognitive impairment in the elderly. We hypothesized that the posterior cortical predilection of CAA would cause visual-processing impairment. We systematically evaluated visuospatial abilities in 22 non-demented CAA patients. Neurocognitive

Amyloid domains in the cell nucleus controlled by nucleoskeletal protein lamin B1 reveal a new pathway of mercury neurotoxicity

Science.gov (United States)

Arnhold, Florian; Gührs, Karl-Heinz

2015-01-01

Mercury (Hg) is a bioaccumulating trace metal that globally circulates the atmosphere and waters in its elemental, inorganic and organic chemical forms. While Hg represents a notorious neurotoxicant, the underlying cellular pathways are insufficiently understood. We identify amyloid protein aggregation in the cell nucleus as a novel pathway of Hg-bio-interactions. By mass spectrometry of purified protein aggregates, a subset of spliceosomal components and nucleoskeletal protein lamin B1 were detected as constituent parts of an Hg-induced nuclear aggregome network. The aggregome network was located by confocal imaging of amyloid-specific antibodies and dyes to amyloid cores within splicing-speckles that additionally recruit components of the ubiquitin-proteasome system. Hg significantly enhances global proteasomal activity in the nucleus, suggesting that formation of amyloid speckles plays a role in maintenance of protein homeostasis. RNAi knock down showed that lamin B1 for its part regulates amyloid speckle formation and thus likewise participates in nuclear protein homeostasis. As the Hg-induced cascade of interactions between the nucleoskeleton and protein homeostasis reduces neuronal signalling, amyloid fibrillation in the cell nucleus is introduced as a feature of Hg-neurotoxicity that opens new avenues of future research. Similar to protein aggregation events in the cytoplasm that are controlled by the cytoskeleton, amyloid fibrillation of nuclear proteins may be driven by the nucleoskeleton. PMID:25699204

Reversal of autophagy dysfunction in the TgCRND8 mouse model of Alzheimer's disease ameliorates amyloid pathologies and memory deficits.

Science.gov (United States)

Yang, Dun-Sheng; Stavrides, Philip; Mohan, Panaiyur S; Kaushik, Susmita; Kumar, Asok; Ohno, Masuo; Schmidt, Stephen D; Wesson, Daniel; Bandyopadhyay, Urmi; Jiang, Ying; Pawlik, Monika; Peterhoff, Corrinne M; Yang, Austin J; Wilson, Donald A; St George-Hyslop, Peter; Westaway, David; Mathews, Paul M; Levy, Efrat; Cuervo, Ana M; Nixon, Ralph A

2011-01-01

Autophagy, a major degradative pathway for proteins and organelles, is essential for survival of mature neurons. Extensive autophagic-lysosomal pathology in Alzheimer's disease brain contributes to Alzheimer's disease pathogenesis, although the underlying mechanisms are not well understood. Here, we identified and characterized marked intraneuronal amyloid-β peptide/amyloid and lysosomal system pathology in the Alzheimer's disease mouse model TgCRND8 similar to that previously described in Alzheimer's disease brains. We further establish that the basis for these pathologies involves defective proteolytic clearance of neuronal autophagic substrates including amyloid-β peptide. To establish the pathogenic significance of these abnormalities, we enhanced lysosomal cathepsin activities and rates of autophagic protein turnover in TgCRND8 mice by genetically deleting cystatin B, an endogenous inhibitor of lysosomal cysteine proteases. Cystatin B deletion rescued autophagic-lysosomal pathology, reduced abnormal accumulations of amyloid-β peptide, ubiquitinated proteins and other autophagic substrates within autolysosomes/lysosomes and reduced intraneuronal amyloid-β peptide. The amelioration of lysosomal function in TgCRND8 markedly decreased extracellular amyloid deposition and total brain amyloid-β peptide 40 and 42 levels, and prevented the development of deficits of learning and memory in fear conditioning and olfactory habituation tests. Our findings support the pathogenic significance of autophagic-lysosomal dysfunction in Alzheimer's disease and indicate the potential value of restoring normal autophagy as an innovative therapeutic strategy for Alzheimer's disease.

Heparan sulfate proteoglycan is associated with amyloid plaques and neuroanatomically targeted PrP pathology throughout the incubation period of scrapie-infected mice

NARCIS (Netherlands)

McBride, P. A.; Wilson, M. I.; Eikelenboom, P.; Tunstall, A.; Bruce, M. E.

1998-01-01

Heparan sulfate proteoglycan (HSPG) has been found to be associated with amyloid deposits in a number of diseases including the cerebral amyloid plaques of Alzheimer's disease and the transmissible spongiform encephalopathies (TSEs). The role of HSPG in amyloid formation and the neurodegenerative

Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers

Directory of Open Access Journals (Sweden)

Rasool Suhail

2007-09-01

Full Text Available Abstract Background Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD, amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. Results We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type

Histological regression of amyloid in AL amyloidosis is exclusively seen after normalization of serum free light chain

NARCIS (Netherlands)

van Gameren, Ingrid I.; van Rijswijk, Martin H.; Bijzet, Johan; Vellenga, Edo; Hazenberg, Bouke P.

Background Histological regression of amyloid has not been studied systematically but is assessed by clinical parameters. We analyzed the change of amyloid deposition in fat tissue in patients with AL amyloidosis following chemotherapy and studied the relation with type of hematologic response.

Human stefin B normal and patho-physiological role: molecular and cellular aspects of amyloid-type aggregation of certain EPM1 mutants.

Directory of Open Access Journals (Sweden)

Mira ePolajnar

2012-08-01

Full Text Available Epilepsies are characterised by abnormal electrophysiological activity of the brain. Among various types of inherited epilepsies different epilepsy syndromes, among them progressive myoclonus epilepsies with features of ataxia and neurodegeneration, are counted. The progressive myoclonus epilepsy of type 1 (EPM1, also known as Unverricht-Lundborg disease presents with features of cerebellar atrophy and increased oxidative stress. It has been found that EPM1 is caused by mutations in human cystatin B gene (human stefin B. We first describe the role of protein aggregation in other neurodegenerative conditions. Protein aggregates appear intraneurally but are also excreted, such as is the case with senile plaques of amyloid- β (Aβ that accumulate in the brain parenchyma and vessel walls. A common characteristic of such diseases is the change of the protein conformation towards β secondary structure that accounts for the strong tendency of such proteins to aggregate and form amyloid fibrils. Second, we describe the patho-physiology of EPM1 and the normal and aberrant roles of stefin B in a mouse model of the disease. Furthermore, we discuss how the increased protein aggregation observed with some of the mutants of human stefin B may relate to the neurodegeneration that occurs in rare EPM1 patients. Our hypothesis (Ceru et al., 2005 states that some of the EPM1 mutants of human stefin B may undergo aggregation in neural cells, thus gaining additional toxic function (apart from loss of normal function. Our in vitro experiments thus far have confirmed that 4 mutants undergo increased aggregation relative to the wild-type protein. It has been shown that the R68X mutant forms amyloid-fibrils very rapidly, even at neutral pH and forms perinuclear inclusions, whereas the G4R mutant exhibits a prolonged lag phase, during which the toxic prefibrillar aggregates accumulate and are scattered more diffusely over the cytoplasm. Initial experiments on the G50E

Kinetic studies with iodine-123-labeled serum amyloid P component in patients with systemic AA and AL amyloidosis and assessment of clinical value

NARCIS (Netherlands)

Jager, PL; Hazenberg, BPC; Franssen, EJF; Limburg, PC; van Rijswijk, MH; Piers, DA

In systemic amyloidosis, widespread amyloid deposition interferes with organ function, frequently with fatal consequences. Diagnosis rests on demonstrating amyloid deposits in the tissues, traditionally with histology although scintigraphic imaging with radiolabeled serum amyloid P component (SAP)

Polymorphism of amyloid-like fibrils can be defined by the concentration of seeds

Directory of Open Access Journals (Sweden)

Tomas Sneideris

2015-08-01

Full Text Available Prions are infectious proteins where the same protein may express distinct strains. The strains are enciphered by different misfolded conformations. Strain-like phenomena have also been reported in a number of other amyloid-forming proteins. One of the features of amyloid strains is the ability to self-propagate, maintaining a constant set of physical properties despite being propagated under conditions different from those that allowed initial formation of the strain. Here we report a cross-seeding experiment using strains formed under different conditions. Using high concentrations of seeds results in rapid elongation and new fibrils preserve the properties of the seeding fibrils. At low seed concentrations, secondary nucleation plays the major role and new fibrils gain properties predicted by the environment rather than the structure of the seeds. Our findings could explain conformational switching between amyloid strains observed in a wide variety of in vivo and in vitro experiments.

An infrared spectroscopy approach to follow β-sheet formation in peptide amyloid assemblies

Science.gov (United States)

Seo, Jongcheol; Hoffmann, Waldemar; Warnke, Stephan; Huang, Xing; Gewinner, Sandy; Schöllkopf, Wieland; Bowers, Michael T.; von Helden, Gert; Pagel, Kevin

2017-01-01

Amyloidogenic peptides and proteins play a crucial role in a variety of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These proteins undergo a spontaneous transition from a soluble, often partially folded form, into insoluble amyloid fibrils that are rich in β-sheets. Increasing evidence suggests that highly dynamic, polydisperse folding intermediates, which occur during fibril formation, are the toxic species in the amyloid-related diseases. Traditional condensed-phase methods are of limited use for characterizing these states because they typically only provide ensemble averages rather than information about individual oligomers. Here we report the first direct secondary-structure analysis of individual amyloid intermediates using a combination of ion mobility spectrometry-mass spectrometry and gas-phase infrared spectroscopy. Our data reveal that oligomers of the fibril-forming peptide segments VEALYL and YVEALL, which consist of 4-9 peptide strands, can contain a significant amount of β-sheet. In addition, our data show that the more-extended variants of each oligomer generally exhibit increased β-sheet content.

Dynamic PET and SPECT imaging with radioiodinated, amyloid-reactive peptide p5 in mice: a positive role for peptide dehalogenation.

Science.gov (United States)

Martin, Emily B; Kennel, Stephen J; Richey, Tina; Wooliver, Craig; Osborne, Dustin; Williams, Angela; Stuckey, Alan; Wall, Jonathan S

2014-10-01

Dynamic molecular imaging provides bio-kinetic data that is used to characterize novel radiolabeled tracers for the detection of disease. Amyloidosis is a rare protein misfolding disease that can affect many organs. It is characterized by extracellular deposits composed principally of fibrillar proteins and hypersulfated proteoglycans. We have previously described a peptide, p5, which binds preferentially to amyloid deposits in a murine model of reactive (AA) amyloidosis. We have determined the whole body distribution of amyloid by molecular imaging techniques using radioiodinated p5. The loss of radioiodide from imaging probes due to enzymatic reaction has plagued the use of radioiodinated peptides and antibodies. Therefore, we studied iodine-124-labeled p5 by using dynamic PET imaging of both amyloid-laden and healthy mice to assess the rates of amyloid binding, the relevance of dehalogenation and the fate of the radiolabeled peptide. Rates of blood pool clearance, tissue accumulation and dehalogenation of the peptide were estimated from the images. Comparisons of these properties between the amyloid-laden and healthy mice provided kinetic profiles whose differences may prove to be indicative of the disease state. Additionally, we performed longitudinal SPECT/CT imaging with iodine-125-labeled p5 up to 72h post injection to determine the stability of the radioiodinated peptide when bound to the extracellular amyloid. Our data show that amyloid-associated peptide, in contrast to the unbound peptide, is resistant to dehalogenation resulting in enhanced amyloid-specific imaging. These data further support the utility of this peptide for detecting amyloidosis and monitoring potential therapeutic strategies in patients. Copyright © 2014 Elsevier Inc. All rights reserved.

Islet amyloid polypeptide and high hydrostatic pressure: towards an understanding of the fibrillization process

Science.gov (United States)

Lopes, D. H. J.; Smirnovas, V.; Winter, R.

2008-07-01

Type II Diabetes Mellitus is a disease which is characterized by peripheral insulin resistance coupled with a progressive loss of insulin secretion that is associated with a decrease in pancreatic islet β-cell mass and the deposition of amyloid in the extracellular matrix of β-cells, which lead to islet cell death. The principal component of the islet amyloid is a pancreatic hormone called islet amyloid polypeptide (IAPP). High-pressure coupled with FT-IR, CD, ThT fluorescence spectroscopic and AFM studies were carried out to reveal information on the aggregation pathway as well as the aggregate structure of IAPP. Our data indicate that IAPP pre-formed fibrils exhibit a strong polymorphism with heterogeneous structures very sensitive to high hydrostatic pressure, indicating a high percentage of ionic and hydrophobic interactions being responsible for the stability the IAPP fibrils.

Microspectroscopy (μFTIR) reveals co-localization of lipid oxidation and amyloid plaques in human Alzheimer disease brains.

Science.gov (United States)

Benseny-Cases, Núria; Klementieva, Oxana; Cotte, Marine; Ferrer, Isidre; Cladera, Josep

2014-12-16

Amyloid peptides are the main component of one of the characteristic pathological hallmarks of Alzheimer's disease (AD): senile plaques. According to the amyloid cascade hypothesis, amyloid peptides may play a central role in the sequence of events that leads to neurodegeneration. However, there are other factors, such as oxidative stress, that may be crucial for the development of the disease. In the present paper, we show that it is possible, by using Fourier tranform infrared (FTIR) microscopy, to co-localize amyloid deposits and lipid peroxidation in tissue slides from patients affected by Alzheimer's disease. Plaques and lipids can be analyzed in the same sample, making use of the characteristic infrared bands for peptide aggregation and lipid oxidation. The results show that, in samples from patients diagnosed with AD, the plaques and their immediate surroundings are always characterized by the presence of oxidized lipids. As for samples from non-AD individuals, those without amyloid plaques show a lower level of lipid oxidation than AD individuals. However, it is known that plaques can be detected in the brains of some non-AD individuals. Our results show that, in such cases, the lipid in the plaques and their surroundings display oxidation levels that are similar to those of tissues with no plaques. These results point to lipid oxidation as a possible key factor in the path that goes from showing the typical neurophatological hallmarks to suffering from dementia. In this process, the oxidative power of the amyloid peptide, possibly in the form of nonfibrillar aggregates, could play a central role.

Transmission electron microscopy of amyloid fibrils.

Science.gov (United States)

Gras, Sally L; Waddington, Lynne J; Goldie, Kenneth N

2011-01-01

Transmission Electron Microscopy of negatively stained and cryo-prepared specimens allows amyloid fibrils to be visualised at high resolution in a dried or a hydrated state, and is an essential method for characterising the morphology of fibrils and pre-fibrillar species. We outline the key steps involved in the preparation and observation of samples using negative staining and cryo-electron preservation. We also discuss methods to measure fibril characteristics, such as fibril width, from electron micrographs.

Docosahexaenoic Acid Reduces Amyloid β Production via Multiple Pleiotropic Mechanisms*

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Grimm, Marcus O. W.; Kuchenbecker, Johanna; Grösgen, Sven; Burg, Verena K.; Hundsdörfer, Benjamin; Rothhaar, Tatjana L.; Friess, Petra; de Wilde, Martijn C.; Broersen, Laus M.; Penke, Botond; Péter, Mária; Vígh, László; Grimm, Heike S.; Hartmann, Tobias

2011-01-01

Alzheimer disease is characterized by accumulation of the β-amyloid peptide (Aβ) generated by β- and γ-secretase processing of the amyloid precursor protein (APP). The intake of the polyunsaturated fatty acid docosahexaenoic acid (DHA) has been associated with decreased amyloid deposition and a reduced risk in Alzheimer disease in several epidemiological trials; however, the exact underlying molecular mechanism remains to be elucidated. Here, we systematically investigate the effect of DHA on amyloidogenic and nonamyloidogenic APP processing and the potential cross-links to cholesterol metabolism in vivo and in vitro. DHA reduces amyloidogenic processing by decreasing β- and γ-secretase activity, whereas the expression and protein levels of BACE1 and presenilin1 remain unchanged. In addition, DHA increases protein stability of α-secretase resulting in increased nonamyloidogenic processing. Besides the known effect of DHA to decrease cholesterol de novo synthesis, we found cholesterol distribution in plasma membrane to be altered. In the presence of DHA, cholesterol shifts from raft to non-raft domains, and this is accompanied by a shift in γ-secretase activity and presenilin1 protein levels. Taken together, DHA directs amyloidogenic processing of APP toward nonamyloidogenic processing, effectively reducing Aβ release. DHA has a typical pleiotropic effect; DHA-mediated Aβ reduction is not the consequence of a single major mechanism but is the result of combined multiple effects. PMID:21324907

Apolipoproteins E and J interfere with amyloid-beta uptake by primary human astrocytes and microglia in vitro

NARCIS (Netherlands)

Mulder, S.D.; Nielsen, H.M.; Blankenstein, M.A.; Eikelenboom, P.; Veerhuis, R.

2014-01-01

Defective clearance of the amyloid-β peptide (Aβ) from the brain is considered a strong promoter in Alzheimer's disease (AD) pathogenesis. Astrocytes and microglia are important mediators of Aβ clearance and Aβ aggregation state and the presence of amyloid associated proteins (AAPs), such as

Amyloid fibers provide structural integrity to Bacillus subtilis biofilms.

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Romero, Diego; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

2010-02-02

Bacillus subtilis forms biofilms whose constituent cells are held together by an extracellular matrix. Previous studies have shown that the protein TasA and an exopolysaccharide are the main components of the matrix. Given the importance of TasA in biofilm formation, we characterized the physicochemical properties of this protein. We report that purified TasA forms fibers of variable length and 10-15 nm in width. Biochemical analyses, in combination with the use of specific dyes and microscopic analyses, indicate that TasA forms amyloid fibers. Consistent with this hypothesis, TasA fibers required harsh treatments (e.g., formic acid) to be depolymerized. When added to a culture of a tasA mutant, purified TasA restored wild-type biofilm morphology, indicating that the purified protein retained biological activity. We propose that TasA forms amyloid fibers that bind cells together in the biofilm.

The contrasting effect of macromolecular crowding on amyloid fibril formation.

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Qian Ma

Full Text Available Amyloid fibrils associated with neurodegenerative diseases can be considered biologically relevant failures of cellular quality control mechanisms. It is known that in vivo human Tau protein, human prion protein, and human copper, zinc superoxide dismutase (SOD1 have the tendency to form fibril deposits in a variety of tissues and they are associated with different neurodegenerative diseases, while rabbit prion protein and hen egg white lysozyme do not readily form fibrils and are unlikely to cause neurodegenerative diseases. In this study, we have investigated the contrasting effect of macromolecular crowding on fibril formation of different proteins.As revealed by assays based on thioflavin T binding and turbidity, human Tau fragments, when phosphorylated by glycogen synthase kinase-3β, do not form filaments in the absence of a crowding agent but do form fibrils in the presence of a crowding agent, and the presence of a strong crowding agent dramatically promotes amyloid fibril formation of human prion protein and its two pathogenic mutants E196K and D178N. Such an enhancing effect of macromolecular crowding on fibril formation is also observed for a pathological human SOD1 mutant A4V. On the other hand, rabbit prion protein and hen lysozyme do not form amyloid fibrils when a crowding agent at 300 g/l is used but do form fibrils in the absence of a crowding agent. Furthermore, aggregation of these two proteins is remarkably inhibited by Ficoll 70 and dextran 70 at 200 g/l.We suggest that proteins associated with neurodegenerative diseases are more likely to form amyloid fibrils under crowded conditions than in dilute solutions. By contrast, some of the proteins that are not neurodegenerative disease-associated are unlikely to misfold in crowded physiological environments. A possible explanation for the contrasting effect of macromolecular crowding on these two sets of proteins (amyloidogenic proteins and non-amyloidogenic proteins has been

Characterization of interactions between inclusion membrane proteins from Chlamydia trachomatis

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Emilie eGauliard

2015-02-01

Full Text Available Chlamydiae are obligate intracellular pathogens of eukaryotes. The bacteria grow in an intracellular vesicle called an inclusion, the membrane of which is heavily modified by chlamydial proteins called Incs (Inclusion membrane proteins. Incs represent 7-10% of the genomes of Chlamydia and, given their localization at the interface between the host and the pathogen, likely play a key role in the development and pathogenesis of the bacterium. However, their functions remain largely unknown. Here, we characterized the interaction properties between various Inc proteins of C. trachomatis, using a bacterial two-hybrid (BACTH method suitable for detecting interactions between integral membrane proteins. To validate this approach, we first examined the oligomerization properties of the well-characterized IncA protein and showed that both the cytoplasmic domain and the transmembrane region independently contribute to IncA oligomerization. We then analyzed a set of Inc proteins and identified novel interactions between these components. Two small Incs, IncF and Ct222, were found here to interact with many other Inc proteins and may thus represent interaction nodes within the inclusion membrane. Our data suggest that the Inc proteins may assemble in the membrane of the inclusion to form specific multi-molecular complexes in an hierarchical and temporal manner. These studies will help to better define the putative functions of the Inc proteins in the infectious process of Chlamydia.

Iron Biochemistry is Correlated with Amyloid Plaque Morphology in an Established Mouse Model of Alzheimer's Disease.

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Telling, Neil D; Everett, James; Collingwood, Joanna F; Dobson, Jon; van der Laan, Gerrit; Gallagher, Joseph J; Wang, Jian; Hitchcock, Adam P

2017-10-19

A signature characteristic of Alzheimer's disease (AD) is aggregation of amyloid-beta (Aβ) fibrils in the brain. Nevertheless, the links between Aβ and AD pathology remain incompletely understood. It has been proposed that neurotoxicity arising from aggregation of the Aβ 1-42 peptide can in part be explained by metal ion binding interactions. Using advanced X-ray microscopy techniques at sub-micron resolution, we investigated relationships between iron biochemistry and AD pathology in intact cortex from an established mouse model over-producing Aβ. We found a direct correlation of amyloid plaque morphology with iron, and evidence for the formation of an iron-amyloid complex. We also show that iron biomineral deposits in the cortical tissue contain the mineral magnetite, and provide evidence that Aβ-induced chemical reduction of iron could occur in vivo. Our observations point to the specific role of iron in amyloid deposition and AD pathology, and may impact development of iron-modifying therapeutics for AD. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Automated solid-state NMR resonance assignment of protein microcrystals and amyloids

International Nuclear Information System (INIS)

Schmidt, Elena; Gath, Julia; Habenstein, Birgit; Ravotti, Francesco; Székely, Kathrin; Huber, Matthias; Buchner, Lena; Böckmann, Anja; Meier, Beat H.; Güntert, Peter

2013-01-01

Solid-state NMR is an emerging structure determination technique for crystalline and non-crystalline protein assemblies, e.g., amyloids. Resonance assignment constitutes the first and often very time-consuming step to a structure. We present ssFLYA, a generally applicable algorithm for automatic assignment of protein solid-state NMR spectra. Application to microcrystals of ubiquitin and the Ure2 prion C-terminal domain, as well as amyloids of HET-s(218–289) and α-synuclein yielded 88–97 % correctness for the backbone and side-chain assignments that are classified as self-consistent by the algorithm, and 77–90 % correctness if also assignments classified as tentative by the algorithm are included

Amyloid- and FDG-PET imaging in amyotrophic lateral sclerosis

Energy Technology Data Exchange (ETDEWEB)

Matias-Guiu, Jordi A.; Pytel, Vanesa; Galan, Lucia; Valles-Salgado, Maria; Guerrero, Antonio; Moreno-Ramos, Teresa; Matias-Guiu, Jorge [Hospital Clinico San Carlos, San Carlos Institute for Health Research (IdISSC), Universidad Complutense de Madrid, Department of Neurology, Madrid (Spain); Cabrera-Martin, Maria Nieves; Carreras, Jose Luis [Hospital Clinico San Carlos, San Carlos Institute for Health Research (IdISSC), Universidad Complutense de Madrid, Department of Nuclear Medicine, Madrid (Spain)

2016-10-15

We aimed to study brain metabolism and presence of beta-amyloid deposits using positron emission tomography (PET) in patients with amyotrophic lateral sclerosis (ALS). This prospective cross-sectional study included 18 patients with definite or probable ALS according to the revised El Escorial diagnostic criteria, and 24 healthy controls. Patients underwent neurological and neuropsychological assessments, PET with {sup 18}F-fluorodeoxyglucose (FDG), and amyloid-PET with {sup 18}F-florbetaben. Patients with ALS showed hypometabolism in the frontal area and hypermetabolism in the cerebellum compared to healthy controls. Four patients (22 %) displayed cognitive impairment and decreased metabolism in the frontal area extending bilaterally to the parietal regions, and increased metabolism in the posterior area of the cerebellum. In patients with no cognitive impairment, metabolism was lower in the left superior frontal gyrus and higher in the anterior and posterior lobes of the cerebellum. In the individual analysis, six patients (35 %) displayed more anterior involvement with hypometabolism affecting the superior frontal, medial, and inferior gyri; six patients (35 %) exhibited a more posterior pattern with hypometabolism in the precentral and postcentral gyri and in the superior and inferior parietal lobules; two patients (11 %) showed a mixed pattern; and three patients (17 %) showed no alterations in brain metabolism. Three (16 %) showed increased {sup 18}F-florbetaben uptake compared to controls. We have identified two main patterns of brain metabolism with an association to cognitive status. Only a subgroup of patients showed an increased uptake of the amyloid tracer. Our results suggest that ALS is heterogeneous from a clinical, metabolic, and molecular standpoint. (orig.)

Amyloid- and FDG-PET imaging in amyotrophic lateral sclerosis

International Nuclear Information System (INIS)

Matias-Guiu, Jordi A.; Pytel, Vanesa; Galan, Lucia; Valles-Salgado, Maria; Guerrero, Antonio; Moreno-Ramos, Teresa; Matias-Guiu, Jorge; Cabrera-Martin, Maria Nieves; Carreras, Jose Luis

2016-01-01

We aimed to study brain metabolism and presence of beta-amyloid deposits using positron emission tomography (PET) in patients with amyotrophic lateral sclerosis (ALS). This prospective cross-sectional study included 18 patients with definite or probable ALS according to the revised El Escorial diagnostic criteria, and 24 healthy controls. Patients underwent neurological and neuropsychological assessments, PET with 18 F-fluorodeoxyglucose (FDG), and amyloid-PET with 18 F-florbetaben. Patients with ALS showed hypometabolism in the frontal area and hypermetabolism in the cerebellum compared to healthy controls. Four patients (22 %) displayed cognitive impairment and decreased metabolism in the frontal area extending bilaterally to the parietal regions, and increased metabolism in the posterior area of the cerebellum. In patients with no cognitive impairment, metabolism was lower in the left superior frontal gyrus and higher in the anterior and posterior lobes of the cerebellum. In the individual analysis, six patients (35 %) displayed more anterior involvement with hypometabolism affecting the superior frontal, medial, and inferior gyri; six patients (35 %) exhibited a more posterior pattern with hypometabolism in the precentral and postcentral gyri and in the superior and inferior parietal lobules; two patients (11 %) showed a mixed pattern; and three patients (17 %) showed no alterations in brain metabolism. Three (16 %) showed increased 18 F-florbetaben uptake compared to controls. We have identified two main patterns of brain metabolism with an association to cognitive status. Only a subgroup of patients showed an increased uptake of the amyloid tracer. Our results suggest that ALS is heterogeneous from a clinical, metabolic, and molecular standpoint. (orig.)

In vivo amyloid imaging with PET in frontotemporal dementia

International Nuclear Information System (INIS)

Engler, Henry; Santillo, Alexander F.; Lindau, Maria; Lannfelt, Lars; Kilander, Lena; Wang, Shu Xia; Savitcheva, Irina; Nordberg, Agneta; Laangstroem, Bengt

2008-01-01

N-methyl[11C]2-(4'methylaminophenyl)-6-hydroxy-benzothiazole (PIB) is a positron emission tomography (PET) tracer with amyloid binding properties which allows in vivo measurement of cerebral amyloid load in Alzheimer's disease (AD). Frontotemporal dementia (FTD) is a syndrome that can be clinically difficult to distinguish from AD, but in FTD amyloid deposition is not a characteristic pathological finding. The aim of this study is to investigate PIB retention in FTD. Ten patients with the diagnosis of FTD participated. The diagnosis was based on clinical and neuropsychological examination, computed tomography or magnetic resonance imaging scan, and PET with 18Fluoro-2-deoxy-d-glucose (FDG). The PIB retention, measured in regions of interest, was normalised to a reference region (cerebellum). The results were compared with PIB retention data previously obtained from 17 AD patients with positive PIB retention and eight healthy controls (HC) with negative PIB retention. Statistical analysis was performed with a students t-test with significance level set to 0.00625 after Bonferroni correction. Eight FTD patients showed significantly lower PIB retention compared to AD in frontal (p < 0.0001), parietal (p < 0.0001), temporal (p = 0.0001), and occipital (p = 0.0003) cortices as well as in putamina (p < 0.0001). The PIB uptake in these FTD patients did not differ significantly from the HC in any region. However, two of the 10 FTD patients showed PIB retention similar to AD patients. The majority of FTD patients displayed no PIB retention. Thus, PIB could potentially aid in differentiating between FTD and AD. (orig.)

In vivo amyloid imaging with PET in frontotemporal dementia

Energy Technology Data Exchange (ETDEWEB)

Engler, Henry [Uruguay University Hospital of Clinics and Faculty of Science, Department of Nuclear Medicine, Montevideo (Uruguay); Uppsala University Hospital, Department of Nuclear Medicine, Uppsala (Sweden); Uppsala University, Department of Medical Sciences, Uppsala (Sweden); GE Healthcare, Uppsala Imanet, Uppsala (Sweden); Santillo, Alexander F.; Lindau, Maria; Lannfelt, Lars; Kilander, Lena [Uppsala University, Department of Public Health and Caring Sciences/Geriatrics, Uppsala (Sweden); Wang, Shu Xia [Guangdong Provincial People' s Hospital, Weilun PET Centre, Guangzhou (China); Savitcheva, Irina [Uppsala University Hospital, Department of Nuclear Medicine, Uppsala (Sweden); Nordberg, Agneta [Karolinska Institute, Division of Molecular Neuropharmacology, Stockholm (Sweden); Karolinska University Hospital Huddinge, Department of Geriatric Medicine, Stockholm (Sweden); Laangstroem, Bengt [GE Healthcare, Uppsala Imanet, Uppsala (Sweden); Uppsala University, Departments of Biochemistry and Organic Chemistry, Uppsala (Sweden)

2008-01-15

N-methyl[11C]2-(4'methylaminophenyl)-6-hydroxy-benzothiazole (PIB) is a positron emission tomography (PET) tracer with amyloid binding properties which allows in vivo measurement of cerebral amyloid load in Alzheimer's disease (AD). Frontotemporal dementia (FTD) is a syndrome that can be clinically difficult to distinguish from AD, but in FTD amyloid deposition is not a characteristic pathological finding. The aim of this study is to investigate PIB retention in FTD. Ten patients with the diagnosis of FTD participated. The diagnosis was based on clinical and neuropsychological examination, computed tomography or magnetic resonance imaging scan, and PET with 18Fluoro-2-deoxy-d-glucose (FDG). The PIB retention, measured in regions of interest, was normalised to a reference region (cerebellum). The results were compared with PIB retention data previously obtained from 17 AD patients with positive PIB retention and eight healthy controls (HC) with negative PIB retention. Statistical analysis was performed with a students t-test with significance level set to 0.00625 after Bonferroni correction. Eight FTD patients showed significantly lower PIB retention compared to AD in frontal (p < 0.0001), parietal (p < 0.0001), temporal (p = 0.0001), and occipital (p = 0.0003) cortices as well as in putamina (p < 0.0001). The PIB uptake in these FTD patients did not differ significantly from the HC in any region. However, two of the 10 FTD patients showed PIB retention similar to AD patients. The majority of FTD patients displayed no PIB retention. Thus, PIB could potentially aid in differentiating between FTD and AD. (orig.)

Multimodal PET Imaging of Amyloid and Tau Pathology in Alzheimer Disease and Non-Alzheimer Disease Dementias.

Science.gov (United States)

Xia, Chenjie; Dickerson, Bradford C

2017-07-01

Biomarkers of the molecular pathology underpinning dementia syndromes are increasingly recognized as crucial for diagnosis and development of disease-modifying treatments. Amyloid PET imaging is an integral part of the diagnostic assessment of Alzheimer disease. Its use has also deepened understanding of the role of amyloid pathology in Lewy body disorders and aging. Tau PET imaging is an imaging biomarker that will likely play an important role in the diagnosis, monitoring, and treatment in dementias. Using tau PET imaging to examine how tau pathology relates to amyloid and other markers of neurodegeneration will serve to better understand the pathophysiologic cascade that leads to dementia. Copyright © 2017 Elsevier Inc. All rights reserved.

Tackling amyloidogenesis in Alzheimer's disease with A2V variants of Amyloid-β.

Science.gov (United States)

Di Fede, Giuseppe; Catania, Marcella; Maderna, Emanuela; Morbin, Michela; Moda, Fabio; Colombo, Laura; Rossi, Alessandro; Cagnotto, Alfredo; Virgilio, Tommaso; Palamara, Luisa; Ruggerone, Margherita; Giaccone, Giorgio; Campagnani, Ilaria; Costanza, Massimo; Pedotti, Rosetta; Salvalaglio, Matteo; Salmona, Mario; Tagliavini, Fabrizio

2016-02-11

We developed a novel therapeutic strategy for Alzheimer's disease (AD) exploiting the properties of a natural variant of Amyloid-β (Aβ) carrying the A2V substitution, which protects heterozygous carriers from AD by its ability to interact with wild-type Aβ, hindering conformational changes and assembly thereof. As prototypic compound we designed a six-mer mutated peptide (Aβ1-6A2V), linked to the HIV-related TAT protein, which is widely used for brain delivery and cell membrane penetration of drugs. The resulting molecule [Aβ1-6A2VTAT(D)] revealed strong anti-amyloidogenic effects in vitro and protected human neuroblastoma cells from Aβ toxicity. Preclinical studies in AD mouse models showed that short-term treatment with Aβ1-6A2VTAT(D) inhibits Aβ aggregation and cerebral amyloid deposition, but a long treatment schedule unexpectedly increases amyloid burden, although preventing cognitive deterioration. Our data support the view that the AβA2V-based strategy can be successfully used for the development of treatments for AD, as suggested by the natural protection against the disease in human A2V heterozygous carriers. The undesirable outcome of the prolonged treatment with Aβ1-6A2VTAT(D) was likely due to the TAT intrinsic attitude to increase Aβ production, avidly bind amyloid and boost its seeding activity, warning against the use of the TAT carrier in the design of AD therapeutics.