Papers by Florent Vanstapel
Clinical Chemistry and Laboratory Medicine (CCLM)
Objectives According to ISO 15189:2022, analytical performance specifications (APS) should relate... more Objectives According to ISO 15189:2022, analytical performance specifications (APS) should relate to intended clinical use and impact on patient care. Therefore, we aimed to develop a web application for laboratory professionals to calculate APS based on a simulation of the impact of measurement uncertainty (MU) on the outcome using the chosen decision limits, agreement thresholds, and data of the population of interest. Methods We developed the “APS Calculator” allowing users to upload and select data of concern, specify decision limits and agreement thresholds, and conduct simulations to determine APS for MU. The simulation involved categorizing original measurand concentrations, generating measured (simulated) results by introducing different degrees of MU, and recategorizing measured concentrations based on clinical decision limits and acceptable clinical misclassification rates. The agreements between original and simulated result categories were assessed, and values that met o...
Laboratornaâ služba, 2022
Carbohydrate Research, 1998
Clinical Chemistry and Laboratory Medicine, Sep 17, 2021
Clinical Chemistry and Laboratory Medicine, Jun 1, 2023
Basic Research in Cardiology, 1994
31P-NMR spectroscopy has become the major tool for studying myocardial high energy phosphates. Co... more 31P-NMR spectroscopy has become the major tool for studying myocardial high energy phosphates. Conflicting results concerning NMR visibility of ATP in ischaemic myocardium were reported. A detailed study was undertaken to resolve this controversy. After cardioplegic arrest, canine hearts were excised and preserved for 24 h at 1 degree C (group 1) or for 6h at 23 degrees C (group 2). ATP breakdown was followed by 31P-NMR spectroscopy in a transmural piece of the anterior wall introduced in the NMR magnet, and by HPLC analysis using serial transmural biopsies from the rest of the anterior wall. At both temperatures, identical relative ATP decay curves were obtained, whether measured by NMR or by HPLC. Absolute quantification of ATP was carried out after varying periods of ischaemia at 1 degree C. The NMR-measured ATP concentration was 106 +/- 8% of the ATP concentration determined by HPLC. From our experiments, we conclude that ATP visibility for 31P-NMR spectroscopy is complete and constant during prolonged periods of hypothermic ischaemia in canine hearts.
Clinical Chemistry and Laboratory Medicine, 2016
We verified the analytical performance of strip-based handheld glucose meters (GM) for prescripti... more We verified the analytical performance of strip-based handheld glucose meters (GM) for prescription use, in a comparative split-sample protocol using blood gas samples from a surgical intensive care unit (ICU). Freestyle Precision Pro (Abbott), StatStrip Connectivity Meter (Nova), ACCU-CHEK Inform II (Roche) were evaluated for recovery/linearity, imprecision/repeatability. The GMs and the ABL90 (Radiometer) blood gas analyzer (BGA) were tested for relative accuracy vs. the comparator hexokinase glucose-6-phosphate-dehydrogenase (HK/G6PDH) assay on a Cobas c702 analyzer (Roche). Recovery of spiked glucose was linear up to 19.3 mmol/L (347 mg/dL) with a slope of 0.91-0.94 for all GMs. Repeatability estimated by pooling duplicate measurements on samples below (n=9), in (n=51) or above (n=80) the 4.2-5.9 mM (74-106 mg/dL) range were for Freestyle Precision Pro: 4.2%, 4.0%, 3.6%; StatStrip Connectivity Meter: 4.0%, 4.3%, 4.5%; and ACCU-CHEK Inform II: 1.4%, 2.5%, 3.5%. GMs were in agreement with the comparator method. The BGA outperformed the GMs, with a MARD of 3.9% compared to 6.5%, 5.8% and 4.4% for the FreeStyle, StatStrip and ACCU-CHEK, respectively. Zero % of the BGA results deviated more than the FDA 10% criterion as compared to 9.4%, 3.7% and 2.2% for the FreeStyle, StatStrip and ACCU-CHEK, respectively. For all GMs, icodextrin did not interfere. Variation in the putative influence factors hematocrit and O2 tension could not explain observed differences with the comparator method. GMs quantified blood glucose in whole blood at about the 10% total error criterion, proposed by the FDA for prescription use.
Journal of Magnetic Resonance, Series B, Sep 1, 1994
Clinical Chemistry and Laboratory Medicine (CCLM), 2019
This paper reflects the opinion of the European Federation of Clinical Chemistry and Laboratory M... more This paper reflects the opinion of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group Accreditation and ISO/CEN standards (WG-A/ISO). It aims to provide guidance for drawing up local/national documents about validation and verification of laboratory methods. We demonstrate how risk evaluation can be used to optimize laboratory policies to meet intended use requirements as well as requirements of standards. This is translated in a number of recommendations on how to introduce risk evaluation in various stages of the implementation of new methods ultimately covering the whole process cycle.
Journal of Applied Physiology, 1993
Using in vivo 31P-nuclear magnetic resonance spectroscopy, we studied the skeletal muscle metabol... more Using in vivo 31P-nuclear magnetic resonance spectroscopy, we studied the skeletal muscle metabolism of 17 anesthetized malignant hyperthermia-susceptible piglets and 25 control piglets during and after a halothane stress test. At rest, the phosphocreatine- (PCr) to-ATP ratio was 12% higher in the anesthetized piglets than in the control piglets, which may reflect a higher proportion of fast glycolytic fibers in the former. About 15 min of halothane administration sufficed to provoke onset of a reaction, which was characterized by a reciprocal drop in PCr and an increase in Pi with commencing intracellular acidosis. Halothane was withdrawn after a 20% drop in PCr. Within the next few minutes, intracellular pH dropped sharply and phosphomonoesters (PME) accumulated excessively. ATP was observed to decrease in 8 of the 17 animals. Halothane inhalation provoked a switch of metabolism toward glycolysis. Accumulation of PME suggests a mismatch between glycogenolysis and glycolysis. Despi...
Journal of Applied Physiology, 1996
This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine suppl... more This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine supplementation in combination with caffeine (Cr+C) on muscle phosphocreatine (PCr) level and performance in healthy male volunteers (n = 9). Before and after 6 days of placebo, Cr (0.5 g x kg-1 x day-1), or Cr (0.5 g x kg-1 x day-1) + C (5 mg x kg-1 x day-1) supplementation, 31P-nuclear magnetic resonance spectroscopy of the gastrocnemius muscle and a maximal intermittent exercise fatigue test of the knee extensors on an isokinetic dynamometer were performed. The exercise consisted of three consecutive maximal isometric contractions and three interval series of 90, 80, and 50 maximal voluntary contractions performed with a rest interval of 2 min between the series. Muscle ATP concentration remained constant over the three experimental conditions. Cr and Cr+C increased (P < 0.05) muscle PCr concentration by 4-6%. Dynamic torque production, however, was increased by 10-23% (P < 0.05) by ...
Clinical chemistry and laboratory medicine, Mar 1, 2017
Clinical Chemistry and Laboratory Medicine (CCLM), 2016
This document is based on the original recommendation of the Expert Panel on the Theory of Refere... more This document is based on the original recommendation of the Expert Panel on the Theory of Reference Values of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC), updated guidelines were recently published under the auspices of the IFCC and the Clinical and Laboratory Standards Institute (CLSI). This document summarizes proposals for recommendations on: (i) The terminology, which is often confusing, noticeably concerning the terms of reference limits and decision limits. (ii) The method for the determination of reference limits according to the original procedure and the conditions, which should be used. (iii) A simple procedure allowing the medical laboratories to fulfill the requirements of the regulation and standards. The updated document proposes to verify that published reference limits are applicable to the laboratory involved. Finally, the strengths and limits of the revised recommendations (especially the selection of the reference population,...
Informatics in Medicine Unlocked
Biochemical Journal, Oct 15, 1984
Journal of Biological Chemistry, Apr 1, 1987
Pediatric Nephrology, 2011
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Papers by Florent Vanstapel