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- Perez-Grijalba, V, et al.
(författare)
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Plasma Aβ42/40 Ratio Detects Early Stages of Alzheimer's Disease and Correlates with CSF and Neuroimaging Biomarkers in the AB255 Study
- 2019
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Ingår i: The journal of prevention of Alzheimer's disease. - : SERDI. - 2426-0266 .- 2274-5807. ; 6:1, s. 34-41
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Tidskriftsartikel (refereegranskat)abstract
- Background: Easily accessible biomarkers are needed for the early identification of individuals at risk of developing Alzheimer’s disease (AD) in large population screening strategies. Objectives: This study evaluated the potential of plasma β-amyloid (Aβ) biomarkers in identifying early stages of AD and predicting cognitive decline over the following two years. Design: Total plasma Aβ42/40 ratio (TP42/40) was determined in 83 cognitively normal individuals (CN) and 145 subjects with amnestic mild cognitive impairment (a-MCI) stratified by an FDG-PET AD-risk pattern. Results: Significant lower TP42/40 ratio was found in a-MCI patients compared to CN. Moreover, a-MCIs with a high-risk FDG-PET pattern for AD showed even lower plasma ratio levels. Low TP42/40 at baseline increased the risk of progression to dementia by 70%. Furthermore, TP42/40 was inversely associated with neocortical amyloid deposition (measured with PiB-PET) and was concordant with the AD biomarker profile in cerebrospinal fluid (CSF). Conclusions: TP42/40 demonstrated value in the identification of individuals suffering a-MCI, in the prediction of progression to dementia, and in the detection of underlying AD pathology revealed by FDG-PET, Amyloid-PET and CSF biomarkers, being, thus, consistently associated with all the well-established indicators of AD.
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| 2. |
- Perez-Grijalba, V, et al.
(författare)
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Plasma Aβ42/40 ratio alone or combined with FDG-PET can accurately predict amyloid-PET positivity: a cross-sectional analysis from the AB255 Study
- 2019
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Ingår i: Alzheimer's research & therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 11:1, s. 96-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundTo facilitate population screening and clinical trials of disease-modifying therapies for Alzheimer’s disease, supportive biomarker information is necessary. This study was aimed to investigate the association of plasma amyloid-beta (Aβ) levels with the presence of pathological accumulation of Aβ in the brain measured by amyloid-PET. Both plasma Aβ42/40 ratio alone or combined with an FDG-PET-based biomarker of neurodegeneration were assessed as potential AD biomarkers.MethodsWe included 39 cognitively normal subjects and 20 patients with mild cognitive impairment from the AB255 Study who had undergone PiB-PET scans. Total Aβ40 and Aβ42 levels in plasma (TP42/40) were quantified using ABtest kits. Subjects were dichotomized as Aβ-PET positive or negative, and the ability of TP42/40 to detect Aβ-PET positivity was assessed by logistic regression and receiver operating characteristic analyses. Combination of plasma Aβ biomarkers and FDG-PET was further assessed as an improvement for brain amyloidosis detection and diagnosis classification.ResultsEighteen (30.5%) subjects were Aβ-PET positive. TP42/40 ratio alone identified Aβ-PET status with an area under the curve (AUC) of 0.881 (95% confidence interval [CI] = 0.779–0.982). Discriminating performance of TP42/40 to detect Aβ-PET-positive subjects yielded sensitivity and specificity values at Youden’s cutoff of 77.8% and 87.5%, respectively, with a positive predictive value of 0.732 and negative predictive value of 0.900. All these parameters improved after adjusting the model for significant covariates. Applying TP42/40 as the first screening tool in a sequential diagnostic work-up would reduce the number of Aβ-PET scans by 64%. Combination of both FDG-PET scores and plasma Aβ biomarkers was found to be the most accurate Aβ-PET predictor, with an AUC of 0.965 (95% CI = 0.913–0.100).ConclusionsPlasma TP42/40 ratio showed a relevant and significant potential as a screening tool to identify brain Aβ positivity in preclinical and prodromal stages of Alzheimer’s disease.
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| 6. |
- Fan, Jiandong, et al.
(författare)
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Influence of the Annealing Atmosphere on the Performance of ZnO Nanowire Dye-Sensitized Solar Cells
- 2013
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:32, s. 16349-16356
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Tidskriftsartikel (refereegranskat)abstract
- Postsynthesis thermal treatments are key to promote crystallinity and reduce the defect density in solution-processed nanomaterials. In particular, the annealing atmosphere strongly influences the functional properties of ZnO nanowires (NWs) and specifically their performance as photoanodes in dye-sensitized solar cells (DSCs). We prepared vertically aligned ZnO NWs by a low-cost, high-yield, and up-scalable hydrothermal method and studied the effect of the postannealing atmosphere on their optoelectronic properties and on their performance as electrodes in DSCs. When annealing ZnO NWs under argon, instead of air, significantly higher photoluminescence (PL) UV emission and relatively lower defects-related visible PL emission were obtained. At the same time, Ar-annealing rendered ZnO NWs with higher electrical conductivities, as observed from single NW measurements using conductive-atomic force microscopy. Furthermore, DSCs based on ZnO NWs annealed in argon were characterized by 50% higher photocurrents than those obtained from air-annealed ZnO. As a result 30% efficiency increases were systematically obtained when using argon as the annealing atmosphere. These results are discussed within the framework of a multiple trapping model for transport and charge transfer, taking into account differences in the defect concentration introduced during the annealing.
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