Browsing by Subject "Luminescent Measurements"
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Item Open Access Analytical performance evaluation of the Elecsys® Troponin T Gen 5 STAT assay.(Clinica chimica acta; international journal of clinical chemistry, 2019-08) Fitzgerald, Robert L; Hollander, Judd E; Peacock, W Frank; Limkakeng, Alexander T; Breitenbeck, Nancy; Blechschmidt, Kareen; Laimighofer, Michael; deFilippi, ChristopherBACKGROUND:We report the analytical performance of the Elecsys® Troponin T Gen 5 STAT (TnT Gen 5 STAT; Roche Diagnostics) assay. METHODS:Measuring limits/ranges were determined in lithium-heparin plasma samples per Clinical and Laboratory Standards Institute (CLSI) EP17-A2. Precision was evaluated per CLSI EP05-A2 using lithium-heparin plasma/quality control samples on cobas e 411/cobas e 601 analyzers; two duplicated runs per day for 21 days (n = 84). Cross-reactivity with other troponin forms and interference from endogenous substances/drugs was tested; recovery criterion for no cross-reactivity was within ±10%. RESULTS:Coefficients of variation (CV) for repeatability/intermediate precision were 0.7-5.6%/1.4-10.3% (cobas e 411; mean cardiac troponin T [cTnT]: 7.3-9341 ng/L) and 0.7-3.0%/1.5-6.4% (cobas e 601; mean cTnT: 7.4-9455 ng/L). There was no cross-reactivity with skeletal muscle troponin T (≤ 10,000 ng/L), skeletal muscle troponin I (≤ 100,000 ng/L), cardiac troponin I (≤ 10,000 ng/L), or human troponin C (≤ 80,000 ng/L). No interference was observed with biotin (≤ 20 ng/mL) or 34 drugs. CONCLUSION:The TnT Gen 5 STAT assay demonstrated a CV of <10% at the 99th percentile upper reference limit, meeting precision requirements (Fourth Universal Definition of Myocardial Infarction) for high-sensitivity troponin assays.Item Open Access Measuring fast gene dynamics in single cells with time-lapse luminescence microscopy.(Mol Biol Cell, 2014-11-05) Mazo-Vargas, Anyimilehidi; Park, Heungwon; Aydin, Mert; Buchler, Nicolas ETime-lapse fluorescence microscopy is an important tool for measuring in vivo gene dynamics in single cells. However, fluorescent proteins are limited by slow chromophore maturation times and the cellular autofluorescence or phototoxicity that arises from light excitation. An alternative is luciferase, an enzyme that emits photons and is active upon folding. The photon flux per luciferase is significantly lower than that for fluorescent proteins. Thus time-lapse luminescence microscopy has been successfully used to track gene dynamics only in larger organisms and for slower processes, for which more total photons can be collected in one exposure. Here we tested green, yellow, and red beetle luciferases and optimized substrate conditions for in vivo luminescence. By combining time-lapse luminescence microscopy with a microfluidic device, we tracked the dynamics of cell cycle genes in single yeast with subminute exposure times over many generations. Our method was faster and in cells with much smaller volumes than previous work. Fluorescence of an optimized reporter (Venus) lagged luminescence by 15-20 min, which is consistent with its known rate of chromophore maturation in yeast. Our work demonstrates that luciferases are better than fluorescent proteins at faithfully tracking the underlying gene expression.