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| 3. |
- Wilson, D., et al.
(författare)
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Development and multi-center validation of a fully automated digital immunoassay for neurofilament light chain: toward a clinical blood test for neuronal injury
- 2024
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Ingår i: Clinical Chemistry and Laboratory Medicine. - 1434-6621 .- 1437-4331. ; 62:2, s. 322-331
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Tidskriftsartikel (refereegranskat)abstract
- Objectives Neurofilament light chain (NfL) has emerged as a promising biomarker for detecting and monitoring axonal injury. Until recently, NfL could only be reliably measured in cerebrospinal fluid, but digital single molecule array (Simoa) technology has enabled its precise measurement in blood samples where it is typically 50-100 times less abundant. We report development and multi-center validation of a novel fully automated digital immunoassay for NfL in serum for informing axonal injury status.Methods A 45-min immunoassay for serum NfL was developed for use on an automated digital analyzer based on Simoa technology. The analytical performance (sensitivity, precision, reproducibility, linearity, sample type) was characterized and then cross validated across 17 laboratories in 10 countries. Analytical performance for clinical NfL measurement was examined in individual patients with relapsing remitting multiple sclerosis (RRMS) after 3 months of disease modifying treatment (DMT) with fingolimod.Results The assay exhibited a lower limit of detection (LLoD) of 0.05 ng/L, a lower limit of quantification (LLoQ) of 0.8 ng/L, and between-laboratory imprecision <10 % across 17 validation sites. All tested samples had measurable NfL concentrations well above the LLoQ. In matched pre-post treatment samples, decreases in NfL were observed in 26/29 RRMS patients three months after DMT start, with significant decreases detected in a majority of patients.Conclusions The sensitivity characteristics and reproducible performance across laboratories combined with full automation make this assay suitable for clinical use for NfL assessment, monitoring in individual patients, and cross-comparisons of results across multiple sites.
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| 4. |
- Pannee, Josef, 1979, et al.
(författare)
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The global Alzheimer's Association round robin study on plasma amyloid beta methods
- 2021
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Blood-based assays to measure brain amyloid beta (A beta) 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 A beta 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 A beta concentrations. Results Correlations were weak for A beta 42 while A beta 40 correlations were stronger. The ratio A beta 42/A beta 40 did not improve the correlations and showed weak correlations. Discussion The poor correlations for A beta 42 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 A beta 42. 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.
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| 5. |
- Bader, J. M., et al.
(författare)
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Proteome profiling in cerebrospinal fluid reveals novel biomarkers of Alzheimer's disease
- 2020
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Ingår i: Molecular Systems Biology. - : EMBO. - 1744-4292. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- Neurodegenerative diseases are a growing burden, and there is an urgent need for better biomarkers for diagnosis, prognosis, and treatment efficacy. Structural and functional brain alterations are reflected in the protein composition of cerebrospinal fluid (CSF). Alzheimer's disease (AD) patients have higherCSFlevels of tau, but we lack knowledge of systems-wide changes ofCSFprotein levels that accompanyAD. Here, we present a highly reproducible mass spectrometry (MS)-based proteomics workflow for the in-depth analysis ofCSFfrom minimal sample amounts. From three independent studies (197 individuals), we characterize differences in proteins byADstatus (> 1,000 proteins,CV < 20%). Proteins with previous links to neurodegeneration such as tau,SOD1, andPARK7 differed most strongly byADstatus, providing strong positive controls for our approach.CSFproteome changes in Alzheimer's disease prove to be widespread and often correlated with tau concentrations. Our unbiased screen also reveals a consistent glycolytic signature across our cohorts and a recent study. Machine learning suggests clinical utility of this proteomic signature.
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| 6. |
- Boulo, S., et al.
(författare)
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First amyloid β1-42 certified reference material for re-calibrating commercial immunoassays
- 2020
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 16:11, s. 1493-1503
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Reference materials based on human cerebrospinal fluid were certified for the mass concentration of amyloid beta (Aβ)1-42 (Aβ42). They are intended to be used to calibrate diagnostic assays for Aβ42. Methods: The three certified reference materials (CRMs), ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC, were prepared at three concentration levels and characterized using isotope dilution mass spectrometry methods. Roche, EUROIMMUN, and Fujirebio used the three CRMs to re-calibrate their immunoassays. Results: The certified Aβ42 mass concentrations in ERM-DA480/IFCC, ERM-DA481/IFCC, and ERM-DA482/IFCC are 0.45, 0.72, and 1.22μg/L, respectively, with expanded uncertainties (k=2) of 0.07, 0.11, and 0.18μg/L, respectively. Before re-calibration, a good correlation (Pearson's r>0.97), yet large biases, were observed between results from different commercial assays. After re-calibration the between-assay bias was reduced to<5%. Discussion: The Aβ42 CRMs can ensure the equivalence of results between methods and across platforms for the measurement of Aβ42. © 2020 the Alzheimer's Association
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| 7. |
- Cullen, Nicholas C., et al.
(författare)
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Test-retest variability of plasma biomarkers in Alzheimer's disease and its effects on clinical prediction models
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:3, s. 797-806
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION The effect of random error on the performance of blood-based biomarkers for Alzheimer's disease (AD) must be determined before clinical implementation. METHODS We measured test-retest variability of plasma amyloid beta (A beta)42/A beta 40, neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and phosphorylated tau (p-tau)217 and simulated effects of this variability on biomarker performance when predicting either cerebrospinal fluid (CSF) A beta status or conversion to AD dementia in 399 non-demented participants with cognitive symptoms. RESULTS Clinical performance was highest when combining all biomarkers. Among single-biomarkers, p-tau217 performed best. Test-retest variability ranged from 4.1% (A beta 42/A beta 40) to 25% (GFAP). This variability reduced the performance of the biomarkers (approximate to Delta AUC [area under the curve] -1% to -4%) with the least effects on models with p-tau217. The percent of individuals with unstable predicted outcomes was lowest for the multi-biomarker combination (14%). DISCUSSION Clinical prediction models combining plasma biomarkers-particularly p-tau217-exhibit high performance and are less effected by random error. Individuals with unstable predicted outcomes ("gray zone") should be recommended for further tests.
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| 8. |
- Janelidze, S., et al.
(författare)
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Head-to-Head Comparison of 8 Plasma Amyloid-beta 42/40 Assays in Alzheimer Disease
- 2021
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Ingår i: Jama Neurology. - : American Medical Association (AMA). - 2168-6149. ; 78:11, s. 1375-1382
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Blood-based tests for brain amyloid-beta (A beta) pathology are needed for widespread implementation of Alzheimer disease (AD) biomarkers in clinical care and to facilitate patient screening and monitoring of treatment responses in clinical trials. OBJECTIVE To compare the performance of plasma A beta 42/40 measured using 8 different A beta assays when detecting abnormal brain A beta status in patients with early AD. DESIGN, SETTING, AND PARTICIPANTS This study included 182 cognitively unimpaired participants and 104 patients with mild cognitive impairment from the BioFINDER cohort who were enrolled at 3 different hospitals in Sweden and underwent A beta positron emission tomography (PET) imaging and cerebrospinal fluid (CSF) and plasma collection from 2010 to 2014. Plasma A beta 42/40 was measured using an immunoprecipitation-coupled mass spectrometry developed at Washington University (IP-MS-WashU), antibody-free liquid chromatography MS developed by Araclon (LC-MS-Arc), and immunoassays from Roche Diagnostics (IA-Elc); Euroimmun (IA-EI); and Amsterdam University Medical Center, ADx Neurosciences, and Quanterix (IA-N4PE). Plasma A beta 42/40 was also measured using an IP-MS-based method from Shimadzu in 200 participants (IP-MS-Shim) and an IP-MS-based method from the University of Gothenburg (IP-MS-UGOT) and another immunoassay from Quanterix (IA-Quan) among 227 participants. For validation, 122 participants (51 cognitively normal, 51 with mild cognitive impairment, and 20 with AD dementia) were included from the Alzheimer Disease Neuroimaging Initiative who underwent A beta-PET and plasma A beta assessments using IP-MS-WashU, IP-MS-Shim, IP-MS-UGOT, IA-Elc, IA-N4PE, and IA-Quan assays. MAIN OUTCOMES AND MEASURES Discriminative accuracy of plasma A beta 42/40 quantified using 8 different assays for abnormal CSF A beta 42/40 and A beta-PET status. RESULTS A total of 408 participants were included in this study. In the BioFINDER cohort, the mean (SD) age was 71.6 (5.6) years and 49.3% of the cohort were women. When identifying participants with abnormal CSF A beta 42/40 in the whole cohort, plasma IP-MS-WashU A beta 42/40 showed significantly higher accuracy (area under the receiver operating characteristic curve [AUC], 0.86; 95% CI, 0.81-0.90) than LC-MS-Arc A beta 42/40, IA-Elc A beta 42/40, IA-EI A beta 42/40, and IA-N4PE A beta 42/40 (AUC range, 0.69-0.78; P < .05). Plasma IP-MS-WashU A beta 42/40 performed significantly better than IP-MS-UGOT A beta 42/40 and IA-Quan A beta 42/40 (AUC, 0.84 vs 0.68 and 0.64, respectively; P < .001), while there was no difference in the AUCs between IP-MS-WashU A beta 42/40 and IP-MS-Shim A beta 42/40 (0.87 vs 0.83; P = .16) in the 2 subcohorts where these biomarkers were available. The results were similar when using A beta-PET as outcome. Plasma IPMS-WashU A beta 42/40 and IPMS-Shim A beta 42/40 showed highest coefficients for correlations with CSF A beta 42/40 (r range, 0.56-0.65). The BioFINDER results were replicated in the Alzheimer Disease Neuroimaging Initiative cohort (mean [SD] age, 72.4 [5.4] years; 43.4% women), where the IP-MS-WashU assay performed significantly better than the IP-MS-UGOT, IA-Elc, IA-N4PE, and IA-Quan assays but not the IP-MS-Shim assay. CONCLUSIONS AND RELEVANCE The results from 2 independent cohorts indicate that certain MS-based methods performed better than most of the immunoassays for plasma A beta 42/40 when detecting brain A beta pathology.
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| 9. |
- Johnson, S. C., et al.
(författare)
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Identifying clinically useful biomarkers in neurodegenerative disease through a collaborative approach: the NeuroToolKit
- 2023
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Ingår i: Alzheimers Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Alzheimer's disease (AD) is a complex and heterogeneous disease, which requires reliable biomarkers for diagnosis and monitoring disease activity. Preanalytical protocol and technical variability associated with biomarker immunoassays makes comparability of biomarker data across multiple cohorts difficult. This study aimed to compare cerebrospinal fluid (CSF) biomarker results across independent cohorts, including participants spanning the AD continuum.Methods Measured on the NeuroToolKit (NTK) prototype panel of immunoassays, 12 CSF biomarkers were evaluated from three cohorts (ALFA+, Wisconsin, and Abby/Blaze). A correction factor was applied to biomarkers found to be affected by preanalytical procedures (amyloid-beta(1-42), amyloid-beta(1-40), and alpha-synuclein), and results between cohorts for each disease stage were compared. The relationship between CSF biomarker concentration and cognitive scores was evaluated.Results Biomarker distributions were comparable across cohorts following correction. Correlations of biomarker values were consistent across cohorts, regardless of disease stage. Disease stage differentiation was highest for neurofilament light (NfL), phosphorylated tau, and total tau, regardless of the cohort. Correlation between biomarker concentration and cognitive scores was comparable across cohorts, and strongest for NfL, chitinase-3-like protein-1 (YKL40), and glial fibrillary acidic protein.Discussion The precision of the NTK enables merging of biomarker datasets, after correction for preanalytical confounders. Assessment of multiple cohorts is crucial to increase power in future studies into AD pathogenesis.
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| 10. |
- Palmqvist, Sebastian, et al.
(författare)
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An accurate fully automated panel of plasma biomarkers for Alzheimer's disease
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:4, s. 1204-1215
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Tidskriftsartikel (refereegranskat)abstract
- Introduction There is a great need for fully automated plasma assays that can measure amyloid beta (A beta) pathology and predict future Alzheimer's disease (AD) dementia. Methods Two cohorts (n = 920) were examined: Panel A+ (n = 32 cognitively unimpaired [CU], n = 106 mild cognitive impairment [MCI], and n = 89 AD) and BioFINDER-1 (n = 461 CU, n = 232 MCI). Plasma A beta 42/A beta 40, phosphorylated tau (p-tau)181, two p-tau217 variants, ApoE4 protein, neurofilament light, and GFAP were measured using Elecsys prototype immunoassays. Results The best biomarker for discriminating A beta-positive versus A beta-negative participants was A beta 42/A beta 40 (are under the curve [AUC] 0.83-0.87). Combining A beta 42/A beta 40, p-tau181, and ApoE4 improved the AUCs significantly (0.90 to 0.93; P< 0.01). Adding additional biomarkers had marginal effects (Delta AUC <= 0.01). In BioFINDER, p-tau181, p-tau217, and ApoE4 predicted AD dementia within 6 years in CU (AUC 0.88) and p-tau181, p-tau217, and A beta 42/A beta 40 in MCI (AUC 0.87). Discussion The high accuracies for A beta pathology and future AD dementia using fully automated instruments are promising for implementing plasma biomarkers in clinical trials and clinical routine.
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| 11. |
- Phillips, C., et al.
(författare)
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A compilation of tri-allelic SNPs from 1000 Genomes and use of the most polymorphic loci for a large-scale human identification panel
- 2020
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Ingår i: Forensic Science International. - : ELSEVIER IRELAND LTD. - 1872-4973 .- 1878-0326. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- In a directed search of 1000 Genomes Phase III variation data, 271,934 tri-allelic single nucleotide polymorphisms (SNPs) were identified amongst the genotypes of 2,504 individuals from 26 populations. The majority of tri-allelic SNPs have three nucleotide substitution-based alleles at the same position, while a much smaller proportion, which we did not compile, have a nucleotide insertion/deletion plus substitution alleles. SNPs with three alleles have higher discrimination power than binary loci but keep the same characteristic of optimum amplification of the fragmented DNA found in highly degraded forensic samples. Although most of the tri-allelic SNPs identified had one or two alleles at low frequencies, often single observations, we present a full compilation of the genome positions, rs-numbers and genotypes of all tri-allelic SNPs detected by the 1000 Genomes project from the more detailed analyses it applied to Phase III sequence data. A total of 8,705 tri-allelic SNPs had overall heterozygosities (averaged across all 1000 Genomes populations) higher than the binary SNP maximum value of 0.5. Of these, 1,637 displayed the highest average heterozygosity values of 0.6-0.666. The most informative tri-allelic SNPs we identified were used to construct a large-scale human identification panel for massively parallel sequencing, designed for the identification of missing persons. The large-scale MPS identification panel comprised: 1,241 autosomal tri-allelic SNPs and 29 X tri-allelic SNPs (plus 46 microhaplotypes adapted for genotyping from reduced length sequences). Allele frequency estimates are detailed for African, European, South Asian and East Asian population groups plus the Peruvian population sampled by 1000 Genomes for the 1,270 tri-allelic SNPs of the final MPS panel. We describe the selection criteria, kinship simulation experiments and genomic analyses used to select the tri-allelic SNP components of the panel. Approximately 5 % of the tri-allelic SNPs selected for the large-scale MPS identification panel gave three-genotype patterns in single individual samples or discordant genotypes for genomic control DNAs. A likely explanation for some of these unreliably genotyped loci is that they map to multiple sites in the genome - high-lighting the need for caution and detailed scrutiny of multiple-allele variant data when designing future forensic SNP panels, as such patterns can arise from common structural variation in the genome, such as segmental duplications.
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| 12. |
- Rabe, C., et al.
(författare)
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Clinical performance and robustness evaluation of plasma amyloid-beta(42/40) prescreening
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:4, s. 1393-1402
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Further evidence is needed to support the use of plasma amyloid beta (A beta) biomarkers as Alzheimer's disease prescreening tools. This study evaluated the clinical performance and robustness of plasma A beta(42)/A beta(40) for amyloid positivity prescreening. Methods Data were collected from 333 BioFINDER and 121 Alzheimer's Disease Neuroimaging Initiative study participants. Risk and predictive values versus percentile of plasma A beta(42)/A beta(40) evaluated the actionability of plasma A beta(42)/A beta(40), and simulations modeled the impact of potential uncertainties and biases. Amyloid PET was the brain amyloidosis reference standard. Results Elecsys plasma A beta(42)/A beta(40) could potentially rule out amyloid pathology in populations with low-to-moderate amyloid positivity prevalence. However, simulations showed small measurement or pre-analytical errors in A beta(42) and/or A beta(40) cause misclassifications, impacting sensitivity or specificity. The minor fold change between amyloid PET positive and negative cases explains the biomarkers low robustness. Discussion Implementing plasma A beta(42)/A beta(40) for routine clinical use may pose significant challenges, with misclassification risks. Highlights Plasma A beta(42)/A beta(40) ruled out amyloid PET positivity in a setting of low amyloid-positive prevalence. Including (pre-) analytical errors or measurement biases caused misclassifications. Plasma A beta(42)/A beta(40) had a low inherent dynamic range, independent of analytical method. Other blood biomarkers may be easier to implement as robust prescreening tools.
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