Cobas e601 immunoassay analyzer

Baseline serum CA19-9 levels were examined within 1 week before the initiation diagnosis of pancreatic adenocarcinoma. Serum CA19-9 levels were detected using an electrochemiluminescence immunoassay on the Roche Cobas e601 immunoassay analyzer (Roche Diagnostics, Mannheim, Germany). Normal CA19-9 was defined as CA19-9 level lower than 37 U/mL [27 (link)].

Serum concentration of 25-hydroxyvitamin D (25(OH)D) was assessed for vitamin D status. Fasting blood samples were collected by qualified phlebotomists and transported to the Sabah Hospital National Reference Laboratory for processing, storage and analysis. Serum 25(OH)D concentration was analyzed on a Cobas e601 immunoassay analyzer (Roche Diagnostics, USA) using manufacturer’s kit. The kit is based on the electrochemiluminescence principle, using streptavidin coated paramagnetic microparticles as universal solid phase reagent, and biotin bound ligand and Ruthenium Bipyridyl (Ru(bpy)₃²⁺ complex as the label. The reagent kits are pre-calibrated and the master curve is readjusted before each batch of assay using a 2-point calibrator set provided in the kit. Manufacturer’s control sera (Preci-Control, Roche Diagnostics) were used as internal control and Bio-Rad EQAS and Randox International Quality Assurance Scheme were used for external quality assurance. The serum sample was incubated with Biotin –vitamin D and polyclonal anti-vitamin D₃ antibody-(Ru(bpy)₃²⁺ complex. Solid phase is added and after further incubation, the bound complex is captured and washed and signal generated. The assay was standardized against LC-MS/MS method. The inter-assay CV was 5–8 % and the assay range was 4–100 ng/ml.

For the qualitative determination of antibodies against SARS-CoV-2, 5.0 ml of whole blood was collected, and after centrifugation at 1800 g for 15 min, the serum was obtained. Then, a highly sensitive and specific sandwich electrochemiluminescence immunoassay (Elecsys^® Anti-SARS-CoV-2 assay, Roche Diagnostics) was used to detect IgM and IgG antibodies against the SARS-CoV-2 nucleocapsid antigen according to the manufacturer's instruction using a fully automated Cobas^® e601 immunoassay analyzer (Roche Diagnostics) ²⁴ (link) .

In this study, we also compared CTCs with some common tumor markers, including serum CEA, CA199, CA50, CA724 and CA242. Serum levels of these tumor markers were assayed using electrochemiluminescence immunoassay technique by cobas e 601 immunoassay analyzers (Roche Diagnostics GmbH). The assays were performed according to the manufacturer's protocols.

Automated assays for sFlt-1 and PlGF (with both levels measured in picograms per milliliter) were performed using the fully automated Elecsys assays on an electrochemiluminescence immunoassay platform (cobas E 601 immunoassay analyzers, Roche Diagnostics) [33 (link)]. The interassay coefficient of variance for sFlt-1 and PlGF immunoassays ranged from 2.6 to 3.0% and 2.0 to 2.4%, respectively. Test results were blinded to both patients and their physicians.

Blood samples were obtained at baseline and during each anthracycline cycle and before each CMR examination. Glucose, glycated hemoglobin, triglycerides, high and low-density lipoprotein cholesterol (Beckman Coulter, AU5800 Beckman Coulter Analyzer, United States) were obtained at baseline after 12 h of fasting. CK, CK-MB (Beckman Coulter, AU5800 Beckman Coulter Analyzer, United States) and high-sensitive troponin T (cTnT) (Roche, Cobas e601 immunoassay analyzers, Roche Diagnostics, Germany) were obtained at baseline, before each anthracycline cycle, and before each CMR visit.