| 1. |
- Bjerke, Maria, 1977, et al.
(författare)
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Assessing the commutability of reference material formats for the harmonization of amyloid beta measurements.
- 2016
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Ingår i: Clinical chemistry and laboratory medicine : CCLM / FESCC. - : Walter de Gruyter GmbH. - 1437-4331 .- 1434-6621. ; 54:7, s. 1177-91
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The cerebrospinal fluid (CSF) amyloid-β (Aβ42) peptide is an important biomarker for Alzheimer's disease (AD). Variability in measured Aβ42 concentrations at different laboratories may be overcome by standardization and establishing traceability to a reference system. Candidate certified reference materials (CRMs) are validated herein for this purpose. METHODS: Commutability of 16 candidate CRM formats was assessed across five CSF Aβ42 immunoassays and one mass spectrometry (MS) method in a set of 48 individual clinical CSF samples. Promising candidate CRM formats (neat CSF and CSF spiked with Aβ42) were identified and subjected to validation across eight (Elecsys, EUROIMMUN, IBL, INNO-BIA AlzBio3, INNOTEST, MSD, Simoa, and Saladax) immunoassays and the MS method in 32 individual CSF samples. Commutability was evaluated by Passing-Bablok regression and the candidate CRM termed commutable when found within the prediction interval (PI). The relative distance to the regression line was assessed. RESULTS: The neat CSF candidate CRM format was commutable for almost all method comparisons, except for the Simoa/MSD, Simoa/MS and MS/IBL where it was found just outside the 95% PI. However, the neat CSF was found within 5% relative distance to the regression line for MS/IBL, between 5% and 10% for Simoa/MS and between 10% and 15% for Simoa/MSD comparisons. CONCLUSIONS: The neat CSF candidate CRM format was commutable for 33 of 36 method comparisons, only one comparison more than expected given the 95% PI acceptance limit. We conclude that the neat CSF candidate CRM can be used for value assignment of the kit calibrators for the different Aβ42 methods.
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| 2. |
- Bjerke, Maria, 1977, et al.
(författare)
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Cerebrospinal Fluid Matrix Metalloproteinases and Tissue Inhibitor of Metalloproteinases in Combination with Subcortical and Cortical Biomarkers in Vascular Dementia and Alzheimer's Disease.
- 2011
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Ingår i: Journal of Alzheimer's disease : JAD. - 1387-2877. ; 27:3, s. 665-676
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) and vascular dementia (VaD) are intertwined by mixed dementia (MD) harboring varying degrees of AD pathology in combination with cerebrovascular disease. The aim was to assess whether there is a difference in the cerebrospinal fluid (CSF) profile, of selected proteins, between patients with VaD and MD with subcortical vascular disease (SVD), AD, and healthy controls that could contribute in the separation of the groups. The study included 30 controls, 26 SVD patients (9 VaD and 17 MD) and 30 AD patients. The protein panel included total tau (T-tau), hyperphosphorylated tau 181 (P-tau181), amyloid β 1-42 (Aβ1-42), neurofilament light (NF-L), myelin basic protein (MBP), heart fatty acid binding protein (H-FABP), matrix metalloproteinases (MMP-1, -2, -3, -9, and -10), and tissue inhibitors of metalloproteinases (TIMP-1 and -2). Immunochemical methods were utilized for quantification of the proteins in CSF and data analysis was performed with a multivariate discriminant algorithm. The concentrations of MBP, TIMP-1, P-tau181, NF-L, T-tau, MMP-9, Aβ1-42, and MMP-2 contributed the most to the separation between SVD and AD, with a sensitivity of 89% and a specificity of 90% (AUC = 0.92). MBP and NF-L performed the best in discriminating SVD from controls, while T-tau and Aβ1-42 contributed the most in segregating AD from controls. The CSF biomarkers reflecting AD pathology (T-tau, P-tau181, and Aβ1-42), white matter lesions (NF-L and MBP) and matrix remodeling (MMP-9 and TIMP-1) perform well in differentiating between SVD and AD patients.
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| 3. |
- Bjerke, Maria, 1977, et al.
(författare)
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Confounding factors influencing amyloid Beta concentration in cerebrospinal fluid.
- 2010
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Ingår i: International journal of Alzheimer's disease. - : Hindawi Limited. - 2090-0252. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- Background. Patients afflicted with Alzheimer's disease (AD) exhibit a decrease in the cerebrospinal fluid (CSF) concentration of the 42 amino acid form of beta-amyloid (Abeta(42)). However, a high discrepancy between different centers in measured Abeta(42) levels reduces the utility of this biomarker as a diagnostic tool and in monitoring the effect of disease modifying drugs. Preanalytical and analytical confounding factors were examined with respect to their effect on the measured Abeta(42) level. Methods. Aliquots of CSF samples were either treated differently prior to Abeta(42) measurement or analyzed using different commercially available xMAP or ELISA assays. Results. Confounding factors affecting CSF Abeta(42) levels were storage in different types of test tubes, dilution with detergent-containing buffer, plasma contamination, heat treatment, and the origin of the immunoassays used for quantification. Conclusion. In order to conduct multicenter studies, a standardized protocol to minimize preanalytical and analytical confounding factors is warranted.
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| 4. |
- Bjerke, Maria, 1977, et al.
(författare)
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Subcortical vascular dementia biomarker pattern in mild cognitive impairment.
- 2009
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Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1421-9824 .- 1420-8008. ; 28:4, s. 348-56
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mild cognitive impairment (MCI) is an etiologically unclear disorder. Cerebrospinal fluid (CSF) biomarkers are potentially useful for the differentiation between various MCI etiologies. AIM: The aim of the study was to assess whether baseline CSF hyperphosphorylated tau (P-tau), total tau (T-tau), amyloid beta 1-42 (Abeta(42)) and neurofilament light (NF-L) in patients with MCI could predict subcortical vascular dementia (SVD) and Alzheimer's disease (AD) at follow-up. METHODS: Biomarker levels were assessed by Luminex xMAP technology and ELISA. RESULTS: Increased baseline concentrations of NF-L significantly separated MCI-SVD from stable MCI. The MCI-SVD patients were inseparable from stable MCI but separable from patients developing AD (MCI-AD) on the basis of Abeta(42,) T-tau and P-tau(181) levels. CONCLUSION: A combination of the biomarkers Abeta(42), T-tau, P-tau(181) and NF-L has the potential to improve the clinical separation of MCI-SVD patients from stable MCI and MCI-AD patients.
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| 5. |
- 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 1.22 μg/L, respectively, with expanded uncertainties (k = 2) of 0.07, 0.11, and 0.18 μg/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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| 6. |
- Brinkmalm, Gunnar, et al.
(författare)
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Soluble amyloid precursor protein α and β in CSF in Alzheimer's disease.
- 2013
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Ingår i: Brain research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1513, s. 117-26
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral accumulation of amyloid β (Aβ) is a pathological hallmark of Alzheimer's disease (AD). Proteolytic processing of amyloid precursor protein (APP) by α- or β-secretase results in two soluble metabolites, sAPPα and sAPPβ, respectively. However, previous data have shown that both α- and β-secretase have multiple cleavage sites. The aim of this study was to characterize the C-termini of sAPPα and sAPPβ in cerebrospinal fluid (CSF) by mass spectrometry (MS) and to evaluate whether different combinations of these fragments better separate between AD patients and controls by comparing two different sAPP immunoassays. Methods: Using immunoprecipitation and high resolution MS, the APP species present in CSF were investigated. CSF levels of sAPPα and sAPPβ from patients with AD (n=43) and from non-demented controls (n=44) were measured using AlphaLISA and MSD immunoassays that employ different antibodies for C-terminal recognition of sAPPα. Results: Four different C-terminal forms of sAPP were identified, sAPPβ-M671, sAPPβ-Y681, sAPPα-Q686, and sAPPα-K687 (APP770 numbering). Neither immunoassay for the sAPP species could separate the two patient groups. The correlation (R(2)) between the two immunoassays was 0.41 for sAPPα and 0.45 for sAPPβ. Conclusion: Using high resolution MS, we show here for the first time that sAPPα in CSF ends at Q686 and K687. The findings also support the conclusion from several previous studies that sAPPα and sAPPβ levels are unaltered in AD.
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| 7. |
- Kuhlmann, Julia, et al.
(författare)
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CSF Aβ1-42 - an excellent but complicated Alzheimer's biomarker - a route to standardisation.
- 2017
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Ingår i: Clinica chimica acta; international journal of clinical chemistry. - : Elsevier BV. - 1873-3492. ; 467
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Tidskriftsartikel (refereegranskat)abstract
- The 42 amino acid form of amyloid β (Aβ1-42) in cerebrospinal fluid (CSF) has been widely accepted as a central biomarker for Alzheimer's disease. Several immunoassays for CSF Aβ1-42 are commercially available, but can suffer from between laboratory and batch-to-batch variability as well as lack of standardisation across assays. As a consequence, no general cut-off values have been established for a specific context of use (e.g., clinical diagnostics) and selection of individuals for enrolment in clinical trials (patient stratification) remains challenging. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has initiated a working group for CSF proteins (WG-CSF) to facilitate standardisation of CSF Aβ1-42 measurement results. The efforts of the IFCC WG-CSF include the development of certified reference materials (CRMs) and reference measurement procedures (RMPs) for key biomarkers. Two candidate RMPs for quantification of Aβ1-42 in CSF based on liquid chromatography tandem mass spectrometry have been developed and tested in two ring trials. Furthermore, two commutability studies including native CSF pools, artificial CSF and spiked materials have been completed. On the basis of these studies, human CSF pools containing only endogenous Aβ1-42 at three concentrations were selected as the format for future CRMs that are now being processed.
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| 8. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Reference measurement procedures for Alzheimer's disease cerebrospinal fluid biomarkers: definitions and approaches with focus on amyloid β42.
- 2012
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Ingår i: Biomarkers in medicine. - : Future Medicine Ltd. - 1752-0371 .- 1752-0363. ; 6:4, s. 409-17
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Tidskriftsartikel (refereegranskat)abstract
- Cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) are increasingly used in clinical settings, research and drug trials. However, their broad-scale use on different technology platforms is hampered by the lack of standardization at the level of sample handling, determination of concentrations of analytes and the absence of well-defined performance criteria for in vitro diagnostic or companion diagnostic assays, which influences the apparent concentration of the analytes measured and the subsequent interpretation of the data. There is a need for harmonization of CSF AD biomarker assays that can reliably, across centers, quantitate CSF biomarkers with high analytical precision, selectivity and stability over long time periods. In this position paper, we discuss reference procedures for the measurement of CSF AD biomarkers, especially amyloid β42 and tau. We describe possible technical approaches, focusing on a selected reaction monitoring mass spectrometry assay as a candidate reference method for quantification of CSF amyloid β42.
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| 9. |
- Olsson, Bob, 1969, et al.
(författare)
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CSF and blood biomarkers for the diagnosis of Alzheimer's disease: a systematic review and meta-analysis.
- 2016
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Ingår i: The Lancet. Neurology. - 1474-4465. ; 15:7
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease biomarkers are important for early diagnosis in routine clinical practice and research. Three core CSF biomarkers for the diagnosis of Alzheimer's disease (Aβ42, T-tau, and P-tau) have been assessed in numerous studies, and several other Alzheimer's disease markers are emerging in the literature. However, there have been no comprehensive meta-analyses of their diagnostic performance. We systematically reviewed the literature for 15 biomarkers in both CSF and blood to assess which of these were most altered in Alzheimer's disease.
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| 10. |
- Rosén, Christoffer, 1986, et al.
(författare)
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Increased Levels of Chitotriosidase and YKL-40 in Cerebrospinal Fluid from Patients with Alzheimer's Disease.
- 2014
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Ingår i: Dementia and geriatric cognitive disorders extra. - : S. Karger AG. - 1664-5464. ; 4:2, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- The cerebrospinal fluid (CSF) biomarkers total tau, abnormally phosphorylated tau and amyloid β 1-42 are strongly associated with Alzheimer's disease (AD). Apart from the pathologic hallmarks that these biomarkers represent, other processes such as inflammation and microglial activation are present in the brains of patients with AD. New biomarkers related to these processes could be valuable for the diagnosis and follow-up of AD patients and for the evaluation of inflammation-related pathologies.
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