Browsing by Author "Portelius, Erik"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Amyloid polymorphisms constitute distinct clouds of conformational variants in different etiological subtypes of Alzheimer's disease
    (National Academy of Sciences, 2017-12-05) Rasmussen, Jay; Mahler, Jasmin; Beschorner, Natalie; Kaeser, Stephan A.; Häsler, Lisa M.; Baumann, Frank; Nyström, Sofie; Portelius, Erik; Blennow, Kaj; Lashley, Tammaryn; Fox, Nick C.; Sepulveda-Falla, Diego; Glatzel, Markus; Oblak, Adrian L.; Ghetti, Bernardino; Nilsson, K. Peter R.; Hammarström, Per; Staufenbiel, Matthias; Walker, Lary C.; Jucker, Mathias; Pathology and Laboratory Medicine, School of Medicine
    The molecular architecture of amyloids formed in vivo can be interrogated using luminescent conjugated oligothiophenes (LCOs), a unique class of amyloid dyes. When bound to amyloid, LCOs yield fluorescence emission spectra that reflect the 3D structure of the protein aggregates. Given that synthetic amyloid-β peptide (Aβ) has been shown to adopt distinct structural conformations with different biological activities, we asked whether Aβ can assume structurally and functionally distinct conformations within the brain. To this end, we analyzed the LCO-stained cores of β-amyloid plaques in postmortem tissue sections from frontal, temporal, and occipital neocortices in 40 cases of familial Alzheimer's disease (AD) or sporadic (idiopathic) AD (sAD). The spectral attributes of LCO-bound plaques varied markedly in the brain, but the mean spectral properties of the amyloid cores were generally similar in all three cortical regions of individual patients. Remarkably, the LCO amyloid spectra differed significantly among some of the familial and sAD subtypes, and between typical patients with sAD and those with posterior cortical atrophy AD. Neither the amount of Aβ nor its protease resistance correlated with LCO spectral properties. LCO spectral amyloid phenotypes could be partially conveyed to Aβ plaques induced by experimental transmission in a mouse model. These findings indicate that polymorphic Aβ-amyloid deposits within the brain cluster as clouds of conformational variants in different AD cases. Heterogeneity in the molecular architecture of pathogenic Aβ among individuals and in etiologically distinct subtypes of AD justifies further studies to assess putative links between Aβ conformation and clinical phenotype.
  • Thumbnail Image
    Item
    The global Alzheimer's Association round robin study on plasma amyloid β methods
    (Wiley, 2021-10-14) Pannee, Josef; Shaw, Leslie M.; Korecka, Magdalena; Waligorska, Teresa; Teunissen, Charlotte E.; Stoops, Erik; Vanderstichele, Hugo M. J.; Mauroo, Kimberley; Verberk, Inge M. W.; Keshavan, Ashvini; Pesini, Pedro; Sarasa, Leticia; Pascual-Lucas, Maria; Fandos, Noelia; Allué, José-Antonio; Portelius, Erik; Andreasson, Ulf; Yoda, Ritsuko; Nakamura, Akinori; Kaneko, Naoki; Yang, Shieh-Yueh; Liu, Huei-Chun; Palme, Stefan; Bittner, Tobias; Mawuenyega, Kwasi G.; Ovod, Vitaliy; Bollinger, James; Bateman, Randall J.; Li, Yan; Dage, Jeffrey L.; Stomrud, Erik; Hansson, Oskar; Schott, Jonathan M.; Blennow, Kaj; Zetterberg, Henrik; Neurology, School of Medicine
    Introduction: Blood-based assays to measure brain amyloid beta (Aβ) deposition are an attractive alternative to the cerebrospinal fluid (CSF)-based assays currently used in clinical settings. In this study, we examined different blood-based assays to measure Aβ and how they compare among centers and assays. Methods: Aliquots from 81 plasma samples were distributed to 10 participating centers. Seven immunological assays and four mass-spectrometric methods were used to measure plasma Aβ concentrations. Results: Correlations were weak for Aβ42 while Aβ40 correlations were stronger. The ratio Aβ42/Aβ40 did not improve the correlations and showed weak correlations. Discussion: The poor correlations for Aβ42 in plasma might have several potential explanations, such as the high levels of plasma proteins (compared to CSF), sensitivity to pre-analytical sample handling and specificity, and cross-reactivity of different antibodies. Different methods might also measure different pools of plasma Aβ42. We, however, hypothesize that greater correlations might be seen in future studies because many of the methods have been refined during completion of this study.