Development and analytical performance evaluation of an automated chemiluminescent immunoassay for pro-gastrin releasing peptide (ProGRP)

Background: Pro-gastrin releasing peptide ( ProGRP) concentrations in blood play an important role in the diagnosis and treatment of patients with small cell lung cancer (SCLC). The automated quantitative ARCHITECT (R) ProGRP assay was developed to aid in the differential diagnosis and in the management of SCLC. The purpose of this study was to evaluate the analytical performance of this chemiluminescent microparticle immunoassay at multiple sites. Methods: ARCHITECT ProGRP measures ProGRP using a two-step sandwich using monoclonal anti-ProGRP antibodies coated on paramagnetic microparticles and labeled with acridinium. Analytical performance of the assay was evaluated at four sites: Abbott Japan, Denka Seiken, the Johns Hopkins University, and the University of Munich. Results: Total precision (%CV) for nine analyte concentrations was between 2.2 and 5.7. The analytical sensitivity of the assay was between 0.20 pg/mL and 0.88 pg/mL. The functional sensitivity at 20% CV was between 0.66 pg/mL and 1.73 pg/mL. The assay was linear up to 50,000 pg/mL using a 1:10 autodilution protocol. The calibration curve was stable for 30 days. Comparison with the Fujirebio microtiter plate enzyme-linked immunosorbent assay (EIA) ProGRP assay gave a slope of 0.93 and a correlation coefficient (r) of 0.99. Conclusions: These results demonstrate that the ARCHITECT ProGRP assay has excellent sensitivity, precision, and correlation to a reference method. This assay provides a convenient automated method for ProGRP measurement in serum and plasma in hospitals and clinical laboratories. Clin Chem Lab Med 2009;47:1557-63

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements