Faber, Jennifer

Abstract Background We evaluated the Tecan Fluent Mix and Pierce Workstation as an automated platform to aliquot directly from whole blood collection tubes. The Fluent Mix and Pierce Workstation uses the Tube Rotator™, an on-deck rotisserie, to keep whole blood in suspension, and 8 Piercing Tips™ to cross the pierceable caps of collection tubes to aliquot samples. Methods We performed accuracy and precision testing by aliquoting residual whole blood specimens into an on-deck gravimetric scale. To test carryover, we aliquoted alternating blanks and high calibrators for several analytes and performed mass spectrometry on the blanks. We performed 168 runs over a 21-day period to test the robustness of the platform. We aliquoted and analyzed 2 batches of samples on both our clinical platform and the Mix and Pierce Workstation to check concordance. Results We observed that the Fluent Mix and Pierce Workstation can aliquot 200 µL with 0.5% inaccuracy and 0.9%CV and can aliquot 300 µL with 0.1% inaccuracy and 0.7%CV. We were unable to detect any analyte carryover using mass spectrometry. We observed no hardware failures during the instrument stress test. Clinical comparison runs indicated that the performance of aliquots made on the Fluent Mix and Pierce Workstation was equivalent to that of aliquots made by our current clinical method. Conclusions Overall, our evaluation showed that the Tecan Fluent Mix and Pierce Workstation is a viable platform for aliquoting whole blood for downstream work flows and can eliminate labor-intensive sample decapping and recapping in high-throughput settings.

AbstractBackground and purposeClinical trials in spinocerebellar ataxia type 3 (SCA3) will require biomarkers for use as outcome measures.MethodsTo evaluate total tau (t‐tau), glial fibrillary acidic protein (GFAP), ubiquitin carboxy‐terminal hydrolase L1 (UCHL1) and neurofilament light‐chain (NfL) as fluid biomarkers in SCA3, ATXN3 mutation carriers (n = 143) and controls (n = 172) were clinically assessed, and the plasma concentrations of the four proteins were analysed on the Simoa HD‐1 platform. Eleven ATXN3 mutation carrier cerebrospinal fluid samples were analysed for t‐tau and phosphorylated tau (p‐tau181). A transgenic SCA3 mouse model (MJDTg) was used to measure cerebellar t‐tau levels.ResultsPlasma t‐tau levels were higher in mutation carriers below the age of 50 compared to controls, and the Inventory of Non‐Ataxia Signs was associated with t‐tau in ataxic patients (p = 0.004). Pre‐ataxic carriers showed higher cerebrospinal fluid t‐tau and p‐tau181 concentrations compared to ataxic patients (p = 0.025 and p = 0.014, respectively). Cerebellar t‐tau was elevated in MJDTg mice compared to wild‐type (p = 0.033) only in the early stages of the disease. GFAP and UCHL1 did not show higher levels in mutation carriers compared to controls. Plasma NfL concentrations were higher in mutation carriers compared to controls, and differences were greater for younger carriers. The Scale for the Assessment and Rating of Ataxia was the strongest predictor of NfL in ataxic patients (p < 0.001).ConclusionOur results suggest that tau might be a marker of early disease stages in SCA3. NfL can discriminate mutation carriers from controls and is associated with different clinical variables. Longitudinal studies are required to confirm their potential role as biomarkers in clinical trials.

Background:The combination of trimethoprim (TMP) and sulfamethoxazole (SMX) is used to treat a number of bacterial infections. TMP/SMX concentrations in serum are conventionally monitored using high-performance liquid chromatography (HPLC) or liquid chromatography tandem mass spectrometry. These methods require laborious manual extraction techniques and relatively long sample analysis times, necessitating the development of a simple, high-throughput method. A simple, high-throughput method to measure TMP/SMX using ultra-fast solid-phase extraction (SPE)–tandem mass spectrometry has been developed.Methods:Calibration standards, quality control materials, and patient samples were precipitated with acetonitrile containing isotopically labeled internal standards. Samples were vortexed, centrifuged for 5 minutes at 2053g, and the resulting supernatant was diluted in aqueous mobile phase and injected onto the C18 SPE cartridge. MS/MS analysis was performed by electrospray ionization in positive ion mode at a rate of <20 seconds per sample. A 5-point linear 1/x calibration curve was used to calculate sample concentrations.Results:The intra-assay precision coefficients of variation were <6% and <7% for SMX and TMP, respectively, and <10% for both interassay precision coefficients of variation. Comparison studies using 50 patient and spiked serum samples showed r2values of 0.9890 and 0.9853 andy-intercept values of −1.918 and −1.357, respectively compared with the HPLC reference method. All data points were <±15% of the mean. Linearity [r2= 0.9952 (SMX) and 0.9954 (TMP)] was established from 12 to 400 mcg/mL with a detection limit of 0.47 mcg/mL, and 1.2–40 mcg/mL with a detection limit of 0.06 mcg/mL, for SMX and TMP, respectively. For either drug, no significant carryover was observed after samples at the upper limit of quantification. No interference was observed from any of the 77 drugs and respective metabolites tested.Conclusions:A high-throughput SPE–tandem mass spectrometry method for TMP/SMX quantification was developed. The <20 seconds analysis time is a significant improvement compared with traditional HPLC and liquid chromatography tandem mass spectrometry methods, without sacrificing analytical performance.