scholarly journals Assessment of Digital PCR as a Primary Reference Measurement Procedure to Support Advances in Precision Medicine

2018 ◽  
Vol 64 (9) ◽  
pp. 1296-1307 ◽  
Author(s):  
Alexandra S Whale ◽  
Gerwyn M Jones ◽  
Jernej Pavšič ◽  
Tanja Dreo ◽  
Nicholas Redshaw ◽  
...  
Keyword(s):  
Precision Medicine ◽  
Copy Number ◽  
Digital Pcr ◽  
Measurement Procedure ◽  
Patient Treatment ◽  
Molecular Diagnostic ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
Wide Range ◽  
Primary Reference

Abstract BACKGROUND Genetic testing of tumor tissue and circulating cell-free DNA for somatic variants guides patient treatment of many cancers. Such measurements will be fundamental in the future support of precision medicine. However, there are currently no primary reference measurement procedures available for nucleic acid quantification that would support translation of tests for circulating tumor DNA into routine use. METHODS We assessed the accuracy of digital PCR (dPCR) for copy number quantification of a frequently occurring single-nucleotide variant in colorectal cancer (KRAS c.35G>A, p.Gly12Asp, from hereon termed G12D) by evaluating potential sources of uncertainty that influence dPCR measurement. RESULTS Concentration values for samples of KRAS G12D and wild-type plasmid templates varied by <1.2-fold when measured using 5 different assays with varying detection chemistry (hydrolysis, scorpion probes, and intercalating dyes) and <1.3-fold with 4 commercial dPCR platforms. Measurement trueness of a selected dPCR assay and platform was validated by comparison with an orthogonal method (inductively coupled plasma mass spectrometry). The candidate dPCR reference measurement procedure showed linear quantification over a wide range of copies per reaction and high repeatability and interlaboratory reproducibility (CV, 2%–8% and 5%–10%, respectively). CONCLUSIONS This work validates dPCR as an SI-traceable reference measurement procedure based on enumeration and demonstrates how it can be applied for assignment of copy number concentration and fractional abundance values to DNA reference materials in an aqueous solution. High-accuracy measurements using dPCR will support the implementation and traceable standardization of molecular diagnostic procedures needed for advancements in precision medicine.

Ratio primary reference measurement procedure (RPRMP) for the certification of chromium content in biological reference materials

2019 ◽  
Vol 107 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Iga Zuba ◽  
Halina Polkowska-Motrenko
Keyword(s):  
Chromium Content ◽  
Measurement Procedure ◽  
Radiochemical Neutron Activation Analysis ◽  
Animal Tissues ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
Primary Reference ◽  
Definition Of ◽  
Certified Values

Abstract Primary reference measurement procedure for Cr determination in biological samples by radiochemical neutron activation analysis (RNAA) has been elaborated. The procedure is based on quantitative and selective separation of chromium from neutron irradiated sample by column chromatography using MnO2-Resin and determination of 51Cr by γ-ray spectrometry. Quality components have been incorporated into the RNAA method which makes it possible to meet the requirements of the definition of ratio primary reference measurement procedure. The usefulness of the elaborated procedure to assign the certified values for Cr in new certified reference material (CRMs) based on animal tissues is demonstrated. The tentative certified values for Cr have been proposed for: MODAS M-4 Cormorant Tissue and M-5 Cod Tissue CRMs.

Reference measurement procedures for the accurate determination of cell concentrations: present status and future developments/Referenzmessverfahren für die genaue Bestimmung von Zellkonzentrationen: Status und zukünftige Entwicklungen

2012 ◽  
Vol 36 (1) ◽  
Author(s):  
Martin Kammel ◽  
Andreas Kummrow ◽  
Jörg Neukammer
Keyword(s):  
Accurate Determination ◽  
Measurement Procedure ◽  
Cell Counting ◽  
Complete Analysis ◽  
Reference Measurement ◽  
Future Developments ◽  
Reference Measurement Procedure ◽  
Primary Reference ◽  
Cell Concentrations

AbstractAccurate determination of cell concentrations serves as a valuable tool to support medical diagnosis and therapy control, e.g., in haematology, immunology and transfusion medicine. Intra- and inter-laboratory comparability of measurement results is essential for patient safety. To derive the so-called “conventional quantity value” of a measurand as target value for intra- or inter-laboratory quality assurance and to establish a traceability chain to the international System of Units (SI), a primary reference measurement procedure is needed, defined as a procedure which includes a complete analysis of influence quantities and perturbing factors and a complete description of measurement uncertainties. We describe a primary reference measurement procedure for the determination of erythrocyte concentration, based on flow cytometric cell counting by impedance measurements. To correct for instrument- and sample-dependent counting loss due to random coincidences, dilution series are prepared. The reference quantity value of the cell concentration is derived by extrapolation to vanishing volume fraction of the sample in the measurement suspension. Typically, for erythrocyte and leucocyte concentrations respective uncertainties of approximately 0.75% and 2% are reached. Future developments concern the extension of the procedures validated for erythrocyte and leucocyte counting by including immunological staining and microscopic techniques.

scholarly journals Proposed Serum Cholesterol Reference Measurement Procedure by Gas Chromatography–Isotope Dilution Mass Spectrometry

2011 ◽  
Vol 57 (4) ◽  
pp. 614-622 ◽  
Author(s):  
Selvin H Edwards ◽  
Mary M Kimberly ◽  
Susan D Pyatt ◽  
Shelton L Stribling ◽  
Kara D Dobbin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Serum Cholesterol ◽  
Isotope Dilution ◽  
Isotope Dilution Mass Spectrometry ◽  
Measurement Procedure ◽  
Standard Reference Materials ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
The Mean

BACKGROUND Our purpose was to establish a mass spectrometry reference measurement procedure (RMP) for cholesterol to use in the CDC's standardization programs. We explored a gas chromatography–isotope dilution mass spectrometry (GC-IDMS) procedure using a multilevel standard calibration curve to quantify samples with varying cholesterol concentrations. METHODS We calibrated the mass spectrometry instrument by isotope dilution with a pure primary standard reference material and an isotopically enriched cholesterol analog as the internal standard (IS). We diluted the serum samples with Tris-HCl buffer (pH 7.4, 0.05 mol/L, 0.25% Triton X-100) before analysis. We used 17 serum pools, 10 native samples, and 2 standard reference materials (SRMs). We compared the GC-IDMS measurements with the CDC's modified Abell–Levy–Brodie–Kendall (AK) RMP measurements and assessed method accuracy by analyzing 2 SRMs. We evaluated the procedure for lack of interference by analyzing serum spiked with a mixture of 7 sterols. RESULTS The mean percent bias between the AK and the GC-IDMS RMP was 1.6% for all samples examined. The mean percent bias from NIST's RMP was 0.5% for the SRMs. The total %CVs for SRM 1951b levels I and II were 0.61 and 0.73%, respectively. We found that none of the sterols investigated interfered with the cholesterol measurement. CONCLUSIONS The low imprecision, linear response, lack of interferences, and acceptable bias vs the NIST primary RMP qualifies this procedure as an RMP for determining serum cholesterol. The CDC will adopt and implement this GC-IDMS procedure for cholesterol standardization.

Verification of Low-Density Lipoprotein Cholesterol Levels Measured by Anion-Exchange High-Performance Liquid Chromatography in Comparison with Beta Quantification Reference Measurement Procedure

2020 ◽  
Author(s):  
Daisuke Manita ◽  
Hiroshi Yoshida ◽  
Isao Koyama ◽  
Masakazu Nakamura ◽  
Yuji Hirowatari
Keyword(s):  
Anion Exchange ◽  
Clinical Laboratory ◽  
Measurement Procedure ◽  
Calculation Methods ◽  
Serum Samples ◽  
Cvd Risk ◽  
Blood Samples ◽  
Reference Measurement ◽  
Reference Measurement Procedure ◽  
Homogeneous Assays

Abstract Background A new lipoprotein testing method based on anion-exchange HPLC (AEX-HPLC) was recently established. We verified the accuracy of LDL-C levels, a primary therapeutic target for the prevention of cardiovascular disease (CVD), measured by AEX-HPLC comparing with LDL-C levels measured by beta quantification-reference measurement procedure (BQ-RMP), homogenous assays, and calculation methods. Methods We compared LDL-C levels measured by AEX-HPLC (adLDL-Ch: LDL-Ch and IDL-Ch) and BQ-RMP using blood samples from 52 volunteers. AdLDL-Ch levels were also compared with those measurements by homogeneous assays and calculation methods (Friedewald equation, Martin equation, and Sampson equation) using blood samples from 411 participants with dyslipidemia and/or type 2 diabetes. Results The precision and accuracy of adLDL-Ch were verified by BQ-RMP. The mean percentage bias [bias (%)] for LDL-C was 1.2%, and the correlation was y = 0.990x + 3.361 (r = 0.990). These results met the acceptable range of accuracy prescribed by the National Cholesterol Education Program. Additionally, adLDL-Ch levels were correlated with LDL-C levels measured by the 2 homogeneous assays (r > 0.967) and the calculation methods (r > 0.939), in serum samples from patients with hypertriglyceridemia. Conclusions AEX-HPLC is a reliable method for measuring LDL-C levels for CVD risk in daily clinical laboratory analyses.

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