PubMed · 10166421
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W A Check. 1996. Hematology analyzer decisions not 'automatic'.. https://pubmed.ncbi.nlm.nih.gov/10166421/
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BACKGROUND: Use of protein array technology over conventional assay methods has advantages that include simultaneous detection of multiple analytes, reduction in sample and reagent volumes, and high output of test results. The susceptibility of ligands to denaturation, however, has impeded production of a stable, reproducible biochip platform, limiting most array assays to manual or, at most, semiautomated processing techniques. Such limitations may be overcome by novel biochip fabrication procedures. METHODS: After selection of a suitable biochip substrate, biochip surfaces were chemically modified and assessed to enable optimization of biochip fabrication procedures for different test panels. The assay procedure was then automated on a dedicated instrument, and assay performance was determined for a panel of cytokine markers. Assay results were then compared with a commercial method for measurement of cytokine markers. RESULTS: Secondary ion mass spectrometry and x-ray photoelectron spectroscopy demonstrated appropriate and reproducible modification of the biochip surface. Contact-angle studies also confirmed generation of hydrophobic surfaces that enabled containment of droplets for fabrication of discrete test regions. Automation of the biochip assays on a dedicated instrument produced excellent cytokine marker performance with intra- and interassay imprecision <10% for most analytes. Comparison studies showed good agreement with other methods (r = 0.95-0.99) for cytokines. CONCLUSION: Performance data from this automated biochip array analyzer provide evidence that it is now possible to produce stable and reproducible biochips for output of more than 2000 test results per hour.
BACKGROUND: Serum is often used for the measurement of cardiac troponin I (cTnI). Previous reports suggest that fibrin present in serum samples collected for cTnI analysis may interfere with measurement of this marker. We investigated the incidence and magnitude of fibrin interference in serum specimens submitted for cTnI measurement using the AxSYM analyzer by performing duplicate analysis of all specimens with increased cTnI results. METHODS: Over a 4-month period, we analyzed 3692 specimens for cTnI with the Abbott AxSYM. Of these, 307 (8.3%) showed increased cTnI. A threshold of three times the precision of the method (15%) was used to judge discrepancies between duplicate analyses of specimens; all specimens being recentrifuged between the initial and repeat cTnI analyses. RESULTS: Of 307 patient specimens with elevated cTnI concentrations, 24 (7.8%) demonstrated differences of greater than 45% between duplicate analyses. Concentrations of cTnI obtained on initial analysis of these 24 specimens ranged from 2.4 to 24.0 microg/l. Repeat analysis showed the repeat values for 20 (83%) to be within the normal reference interval, with 16 (67%) showing concentrations of less than 0.3 microg/l. CONCLUSIONS: Our finding indicates that interference should be highly suspected in serum specimens where the initially measured cTnI concentrations is in the range of 2.0-25.0 microg/l when using the Abbott AxSYM. The finding of no interference in specimens with measured troponin concentration greater than 25.0 microg/l suggests that the interference effect of fibrin is generally not sufficient to cause spurious elevations of cTnI into this range. In addition, since switching to plasma as the specimen of choice for the AxSYM, we have not observed any discrepant cTnI results following duplicate analysis of over 200 patient samples with initial measured cTnI concentrations of 2.0 microg/l or greater.
BACKGROUND: We developed a sensitive, specific method for the low-molecular-mass thiols cysteine, cysteinylglycine, glutathione, and homocysteine and validated the method for measurement of glutathione in blood. METHODS: The technique was based on reversed-phase chromatography (RPC) coupled on line with cold vapor generation atomic fluorescence spectrometry (CVGAFS). Thiols were derivatized before introduction on the column by use of a p-hydroxymercuribenzoate (PHMB) mercurial probe and separated as thiol-PHMB complexes on a Vydac C4 column. Postcolumn on-line reaction of derivatized thiols with bromine allowed rapid conversion of the thiol-PHMB complexes to inorganic mercury with recovery of 100 (2)% of the sample. HgII was selectively detected by atomic fluorescence spectrometry in an Ar/H2 miniaturized flame after sodium borohydride reduction to Hg0. RESULTS: The relationship between thiol-PHMB complex concentration and peak area (CVGAFS signal) was linear over the concentration range 0.01-1400 micromol/L (injected). The detection limits were 1, 1, 0.6, and 0.8 nmol/L for cysteine, cysteinylglycine, homocysteine, and glutathione in the injected sample, respectively. The CVs for thiols were 1.5%-2.2% for calibrator solutions and 2.1% and 3.0% for real samples. The RPC-CVGAFS method allowed speciation of glutathione (reduced and oxidized) in human whole blood from healthy donors and from the coronary sinus of patients with idiopathic dilated cardiomyopathy during and after chronotropic stress. CONCLUSION: The RPC-CVGAFS method could be used to measure reduced and oxidized glutathione in human whole blood as disease biomarkers.