| 1. |
- Andreasson, Ulf, 1968, et al.
(författare)
-
A Practical Guide to Immunoassay Method Validation.
- 2015
-
Ingår i: Frontiers in neurology. - : Frontiers Media SA. - 1664-2295. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Biochemical markers have a central position in the diagnosis and management of patients in clinical medicine, and also in clinical research and drug development, also for brain disorders, such as Alzheimer's disease. The enzyme-linked immunosorbent assay (ELISA) is frequently used for measurement of low-abundance biomarkers. However, the quality of ELISA methods varies, which may introduce both systematic and random errors. This urges the need for more rigorous control of assay performance, regardless of its use in a research setting, in clinical routine, or drug development. The aim of a method validation is to present objective evidence that a method fulfills the requirements for its intended use. Although much has been published on which parameters to investigate in a method validation, less is available on a detailed level on how to perform the corresponding experiments. To remedy this, standard operating procedures (SOPs) with step-by-step instructions for a number of different validation parameters is included in the present work together with a validation report template, which allow for a well-ordered presentation of the results. Even though the SOPs were developed with the intended use for immunochemical methods and to be used for multicenter evaluations, most of them are generic and can be used for other technologies as well.
|
|
| 2. |
- Bjerke, Maria, 1977, et al.
(författare)
-
Assessing the commutability of reference material formats for the harmonization of amyloid beta measurements.
- 2016
-
Ingår i: Clinical chemistry and laboratory medicine : CCLM / FESCC. - : Walter de Gruyter GmbH. - 1437-4331 .- 1434-6621. ; 54:7, s. 1177-91
-
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.
|
|
| 3. |
|
|
| 4. |
- De Vos, Ann, et al.
(författare)
-
Neurogranin and tau in cerebrospinal fluid and plasma of patients with acute ischemic stroke.
- 2017
-
Ingår i: BMC neurology. - : Springer Science and Business Media LLC. - 1471-2377. ; 17:1
-
Tidskriftsartikel (refereegranskat)abstract
- While neurogranin has no value as plasma biomarker for Alzheimer's disease, it may be a potential blood biomarker for traumatic brain injury. This evokes the question whether there are changes in neurogranin levels in blood in other conditions of brain injury, such as acute ischemic stroke (AIS).We therefore explored neurogranin in paired cerebrospinal fluid (CSF)/plasma samples of AIS patients (n = 50) from a well-described prospective study. In parallel, we investigated another neuronal protein, i.e. tau, which has already been suggested as potential AIS biomarker in CSF and blood. ELISA as well as Single Molecule Array (Simoa) technology were used for the biochemical analyses. Statistical analyses included Shapiro-Wilk testing, Mann-Whitney analyses and Pearson's correlation analysis.In contrast to tau, of which high levels in both CSF and plasma were related to stroke characteristics like severity and long-term outcome, plasma neurogranin levels were only correlated with infarct volume. Likewise, CSF neurogranin levels were significantly higher in patients with an infarct volume > 5 mL than in patients with smaller infarct volumes. Finally, neurogranin and tau were significantly correlated in CSF, whereas a weaker relationship was observed in plasma.These findings indicate that although plasma and CSF neurogranin may reflect the volume of acute cerebral ischemia, this synaptic protein is less likely to be a potential AIS biomarker. Levels of tau correlated with severity and outcome of stroke in both plasma and CSF, in the present study as well as previous reports, confirming the potential of tau as an AIS biomarker.
|
|
| 5. |
- Willemse, Eline A J, et al.
(författare)
-
Neurogranin as Cerebrospinal Fluid Biomarker for Alzheimer Disease: An Assay Comparison Study.
- 2018
-
Ingår i: Clinical chemistry. - : Oxford University Press (OUP). - 1530-8561 .- 0009-9147. ; 64:6, s. 927-937
-
Tidskriftsartikel (refereegranskat)abstract
- Neurogranin in cerebrospinal fluid (CSF) correlates with cognitive decline and is a potential novel biomarker for Alzheimer disease (AD) dementia. We investigated the analytical and diagnostic performance of 3 commonly used neurogranin assays in the same cohort of patients to improve the interpretability of CSF neurogranin test results.The neurogranin Singulex assay from Washington University, St. Louis, MO (WashU); ELISA from ADx Neurosciences; and ELISA from Gothenburg University, Mölndal, Sweden (UGot), were compared using silver staining and Western blot after gel electrophoresis. Clinical performance of the 3 assays was compared in samples from individuals diagnosed with subjective cognitive decline (n = 22), and in patients with AD (n = 22), frontotemporal dementia (n = 22), dementia with Lewy bodies (n = 22), or vascular dementia (n = 20), adjusted for sex and age.The assays detected different epitopes of neurogranin: the WashU assay the N-terminal part of neurogranin (S10-D23) and a C-terminal part (G49-G60), the ADx assay C-terminal neurogranin truncated at P75, and the UGot assay the C-terminal neurogranin with intact ending (D78). Spearman ρ was 0.95 between ADx and WashU, 0.87 between UGot and WashU, and 0.81 between UGot and ADx. ANCOVA (analysis of covariance) showed group differences for ranked neurogranin concentrations in each assay (allP< 0.05), with specific increases in AD.Although the 3 assays target different epitopes on neurogranin and have different calibrators, the high correlations and the similar group differences suggest that the different forms of neurogranin in CSF carry similar diagnostic information, at least in the context of neurodegenerative diseases.
|
|
