The human population sample (n = 1419) was derived from participants in the baseline survey of the MIND-China,19 (link) a participating project of the World-Wide FINGERS Network.26 (link) AD was diagnosed according to the National Institute of Aging-Alzheimer's Association (NIA-AA) criteria,27 (link) for probable AD, as previously reported.28 (link) Multiple-PCR amplification analysis of genomic DNA was performed for participants to detect KIBRA gene Single Nucleotide Polymorphism (SNP) risk loci and exon region.29 Plasma total-tau, Aβ40, and Aβ42 levels were measured on a Simoa platform (Quanterix Corp, MA, USA) with Human Neurology 3-Plex A assay (N3PA), following the manufacturer's instructions.23 (link)
Simoa platform
Manufactured by Quanterix
Sourced in United States
The Simoa platform is a high-sensitivity digital immunoassay system developed by Quanterix. It is designed to quantify low-abundance protein biomarkers in biological samples with high precision and sensitivity.
Automatically generated - may contain errors
Lab products found in correlation
Nf light kit, by Quanterix (3 mentions)
Nf light kit, by UmanDiagnostics (2 mentions)
Human total tau 2.0 kit, by Quanterix (2 mentions)
Human neurology 3 plex a assay, by Mesoscale (2 mentions)
Nf light advantage kit, by Mesoscale (2 mentions)
Hd 1 analyzer, by Quanterix (2 mentions)
Pnf heavy discovery kit, by Quanterix (2 mentions)
Nf light advantage kit, by Quanterix (2 mentions)
Simoa assay kit, by Quanterix (2 mentions)
Human neurology 3 plex a assay, by Quanterix (1 mentions)
Innotest enzyme linked immunosorbent assay elisa, by Fujirebio (1 mentions)
Msd 5 plex assays, by Mesoscale (1 mentions)
Homebrew kit, by Quanterix (1 mentions)
Nf light elisa, by UmanDiagnostics (1 mentions)
Cobas e601, by Roche (1 mentions)
Innotest elisa, by Fujirebio (1 mentions)
Luciferase assay, by Promega (1 mentions)
Recombinant mouse ifnα2, by Thermo Fisher Scientific (1 mentions)
35 protocols using simoa platform
1
Alzheimer's Disease Biomarkers in Chinese
2
Plasma Aβ Quantification with Simoa
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Blood processing for plasma collection was performed within 3 h of blood draw, in the morning under fasting conditions, and stored at −80 °C. Plasma Aβ concentrations were measured employing the Amyblood test on the Simoa platform (HDx instrument, Quanterix) using N-terminal-specific monoclonal antibodies provided by ADx NeuroSciences, as described previously [18 (link),19 (link)]. Briefly, for Aβ1-40, C-terminal-specific ADx103 (2G3, Aβx-40) was used as the capture antibody and N-terminal-specific ADx101 (3D6, Aβ1-x) was used as the detector antibody. For Aβ1-42, C-terminal-specific ADx102 (21F12, x-42) was used as the capture antibody and N-terminal-specific ADx101 was used as the detector antibody. The percent coefficients of variation (CV) of the three quality control samples ranged between 0–4% and 0–19% for Aβ1-40 and Aβ1-42, respectively. The apolipoprotein E (APOE) ε4 genotype status, used as a dichotomous variable (presence/absence), of each study participant was accessed from the DIAN database [20 (link)].
3
Plasma GFAP Quantification using Simoa
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Plasma GFAP
concentration was measured at University
College London using the Simoa platform (HD-x instrument) and the
Simoa GFAP Discovery Kit according to the manufacturer’s instructions
(Quanterix, Billerica, MA). First, samples were added neat to the
plate and then diluted × 4 on board the instrument. The samples
were then incubated with the mixture of capture antibody-modified
magnetic microbeads and biotinylated conjugate for 35 min. The microbeads
were incubated with streptavidin-ß-galactosidase (SBG) for 5
min, followed by a washup step, and then resuspended in a resorufin
ß-d -galactopyranoside (RGP) substrate solution to generate
optical signal. The concentrations of GFAP were obtained using a four-parameter
1/Y2 weighted curve fit with seven calibrator points between 1.37
and 1000 pg/mL. These calibrator points were measured from a serial
dilution of concentrated calibrator in the assay kit. Three plasma
samples were used as the quality controls with GFAP concentrations
of 283.0 pg/mL (high), 61.0 pg/mL (medium), and 13.6 pg/mL (low).
Coefficient of variation (CV) was calculated as a ratio of the standard
deviation (SD) to the mean of the duplicate Simoa measurements, as
a measure of the accuracy of the measured GFAP concentration. CV values
below 30% were considered acceptable.
concentration was measured at University
College London using the Simoa platform (HD-x instrument) and the
Simoa GFAP Discovery Kit according to the manufacturer’s instructions
(Quanterix, Billerica, MA). First, samples were added neat to the
plate and then diluted × 4 on board the instrument. The samples
were then incubated with the mixture of capture antibody-modified
magnetic microbeads and biotinylated conjugate for 35 min. The microbeads
were incubated with streptavidin-ß-galactosidase (SBG) for 5
min, followed by a washup step, and then resuspended in a resorufin
ß-
optical signal. The concentrations of GFAP were obtained using a four-parameter
1/Y2 weighted curve fit with seven calibrator points between 1.37
and 1000 pg/mL. These calibrator points were measured from a serial
dilution of concentrated calibrator in the assay kit. Three plasma
samples were used as the quality controls with GFAP concentrations
of 283.0 pg/mL (high), 61.0 pg/mL (medium), and 13.6 pg/mL (low).
Coefficient of variation (CV) was calculated as a ratio of the standard
deviation (SD) to the mean of the duplicate Simoa measurements, as
a measure of the accuracy of the measured GFAP concentration. CV values
below 30% were considered acceptable.
4
Serum NfL in Multisystem Inflammatory Syndrome
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Whole blood samples (4 ml) were drawn from all patients with MIS at admission, and serum samples were isolated following centrifugation for 20 min at 2,000 g at room temperature. Then, serum samples were stored at −80°C until analysis. At the same time, 40 age- and sex-matched healthy controls were selected, and their serum samples were obtained after their enrollment in the study. Serum NfL (sNfL) concentrations were measured using a SiMoAplatform (Quanterix, Lexington, MA, United States) as described (26 (link)). All serum samples were analyzed in duplicates for inter-test validation, and the two results were averaged to determine the mean concentration. The mean intra-assay variability (the coefficient of the variation of concentrations) was <10%, and the inter-assay coefficient of variation was <15%.
5
Quantifying Neurofilament Light Levels
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CSF NFL levels were determined using the NF-Light kit from UmanDiagnostics (UmanDiagnostics, Umeå, Sweden) according to the manufacturer's instructions. Samples were run in duplicate with an intra-assayvariability of 3.5% and a lower detection threshold of 32 pg/ml. Plasma NFL levels were determined using the same NFL antibodies from UmanDiagnostics, transferred onto the Simoa™ platform using a homebrew kit (Quanterix Corp, Boston, MA, USA). The lower limit of quantification (LLoQ), determined by the blank mean signal + 10 SD, was 1.95 pg/ml. All samples measured were above LLoQ in a pilot run on plasma from 100 patients and controls, where a range from 2.2 to 403 pg/mL could be demonstrated. The analyses were performed by a board-certified laboratory technician using one batch of reagents with intra-assay coefficients of variation below 10%.
6
Cerebrospinal Fluid Biomarker Quantification
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Ten millilitres of CSF were collected into polypropylene tubes (Nunc™, cat. no. 339650), whereas blood samples were collected by venipuncture into ethylenediaminetetraacetic acid tubes (BD Vacutainer®, SKU 367863). All samples were centrifuged (10 min at 25°C 2000 × g), separated, divided into aliquots and stored at −80°C within 1 h of the collection according to consensus protocol pending for biochemical analysis.28 (link) The CSF NFL levels were measured with enzyme-linked immunosorbent assay (ELISA) (NF-Light™ ELISA; Tecan, cat. no. 30112458) according to the manufacturer’s recommendations. NFL levels in plasma were measured using the Simoa platform (Quanterix, cat. no. 103400). All samples were analysed in duplicates (CSF) or triplicates (plasma) using the same batch of reagents by two certificated laboratory technicians who were blinded to clinical information.
7
CSF Biomarker Quantification Protocol
8
CSF Biomarker Quantification Protocol
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CSF was drawn the morning after fasting since midnight according to current ADRC best practices/National Institute on Aging guidelines. CSF lumbar draw was performed by a trained neurologist at the SBCoA (G.A.J) and then banked by the UK‐ADRC Neuropathology Core. CSF was collected using a 20‐gauge needle, 15 mL sterile polypropylene collection tubes, and was stored in single‐use 0.5 mL aliquots in polypropylene storage tubes at –80°C. CSF was analyzed using the Quanterix Simoa platform. Aβ1‐42, p‐tau181, and t‐tau were measured on the HD‐1 instrument using the Neuro 3‐plex A (Aβ40, Aβ42, t‐tau) assay at 1:200 and the p‐tau181 assay at 1:20 according to manufacturer's instructions. CSF samples were quantified in units of picograms per milliliter (pg/mL).
9
Serum Biomarker Quantification Protocol
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Blood samples were obtained via venous puncture and centrifuged immediately for 10 min at 2000× g. Serum was transferred into Eppendorf tubes and stored at −80 °C until measurement. The analyses were performed using an in-house assay on the SIMOA platform (Quanterix, Lexington, MA, USA), as per the manufacturer’s instructions. The intra-assay coefficient of variation of the assay was <10%. Laboratory analyses were blinded to the patient’s identity or diagnosis.
10
Quantification of Plasma Tau and NfL
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The concentrations of tau and NfL in plasma were measured using the NF-light and Total Tau 2.0 kits using the Simoa platform (Quanterix, Billerica, MA) as previously described in detail [20 (link)]. Calibrators were run in duplicates, while samples were run in singlicates with a 4 fold dilution. Two quality control (QC) samples from plasma were run in duplicates in the beginning and the end of each run. For NfL, between-run precision was 6.0% at 8.5 pg/mL and 5.1% at 121 pg/mL, while for T-tau, between-run precision was 7.3% at 32.2 pg/mL and 7.0% at 7.5 pg/mL. Plasma NSE, serum S100B and CSF S100B and NSE concentrations were measured as singlicates on the cobas Elecsys platform, according to the manufacturer’s recommendations. CSF T-tau was measured using the INNOTEST enzyme-linked immunosorbent assay (ELISA, Fujirebio Europe, Ghent, Belgium), while CSF NfL was measured using an in-house ELISA as described previously in detail [21 (link)]. Elecsys- and ELISA-based methods were chosen for biomarkers for which Simoa ultrasensitivity was not needed. Between-run precision was <10% for all these assays. All measurements of CSF and plasma/serum concentrations were performed in one round of experiments using a single batch of reagents for each assay by board-certified laboratory technicians who were blinded to clinical data.
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