Heather A. Nelson

Introduction: Cerebrospinal fluid (CSF) biomarkers for Alzheimer disease are US Food and Drug Administration approved and implemented on automated platforms, allowing for widespread use and higher throughput. Although low-bind polypropylene tubes for accurate quantification of amyloid-β (Aβ) have been well studied, less is known about the impact of other common preanalytical variables on quantification of biomarkers for Alzheimer disease. This study evaluated the effects of refrigerated transportation and hemolysis on the concentrations of Aβ42, phosphorylated tau 181, and total tau. Methods: The Roche Diagnostics Elecsys β-Amyloid (1-42) CSF II, Elecsys Phospho-Tau (181P) CSF, and Elecsys Total-Tau CSF assays were used on the Roche cobas pro e 801 platform to measure protein concentrations in residual CSF samples. Paired-difference testing was performed to determine the effects of simulated transportation and hemolysis on each analyte. Results: For all 3 analytes, less than 10% difference was observed between the concentrations measured on day 0 and after 14 days of transportation and refrigeration. In contrast, 2.26 g/L free hemoglobin resulted in more than 10% negative bias in Aβ42 measurement compared with the 0 g/L control but did not affect phosphorylated tau 181 or total tau concentrations. Discussion: Refrigerated transportation did not affect the analysis of Aβ42, phosphorylated tau 181, or total tau, whereas hemolysis can negatively affect results of Aβ42.

Background: A common problem in clinical laboratories and outpatient clinics is processing specimens rapidly to comply with specimen stability criteria. Currently, for therapeutic drug monitoring, the laboratory must centrifuge specimens and remove the serum or plasma from cells within 2 hours. Many of these drugs are monitored in the outpatient setting, which may require longer transportation times. This creates challenges for the laboratory in processing samples within 2 hours and may result in unnecessary rejection of otherwise acceptable specimens if blood is left on cells too long. The objective of this study was to determine the effect of storage time before centrifugation on the stability of digoxin, lithium, phenytoin, valproic acid, and vancomycin in blood. Methods: The concentration of 5 therapeutic drugs was examined following extended on-cell storage at room temperature (RT). For each drug studied, 3 red-top, no gel serum tubes per patient were collected and maintained at RT for 0.5, 6, and 12 hours after collection. Statistically significant changes from the 0.5-hour control were determined using repeated-measures ANOVA. Phenytoin studies were supplemented with spiked specimens. The spiked whole blood samples were mixed and left at RT for 0.5, 2, 4, 6, or 12 hours after collection. Results: The concentration of digoxin, lithium, phenytoin, valproic acid, and vancomycin were all within ±10% of the baseline concentration when left at RT on cells up to 12 hours. Conclusion: All 5 drugs showed adequate stability in unprocessed clotted blood for up to 12 hours at RT. This data can alleviate constraints on processing samples for therapeutic drug monitoring in the clinical laboratory.

Context: There are currently 2 classes of thyroid-stimulating hormone receptor (TSHR) antibody assays, namely TSHR antibody (TRAb) assays and thyroid-stimulating immunoglobulin (TSI) assays. Clinical guidelines do not currently specify appropriate use of TSHR autoantibody tests in the diagnosis of hyperthyroidism, which may result in paired orders for both tests with the possibility of discordant results and excessive costs. Objective: This work aimed to evaluate the clinical and analytical redundancy of paired TSHR autoantibody testing—specifically TRAb and TSI assays—in the diagnosis of autoimmune-mediated hyperthyroidism, by analyzing the frequency of paired orders, assay concordance, and clinical correlation across a large cohort of patient encounters. Methods: Over 189 000 patient encounters with TRAb and TSI bioassay (TSI-BA) or TSI bridge immunoassay (TSI-Br) test orders were examined to assess the frequency of paired orders and qualitative agreement of TRAB/TSI. A chart review was performed on a subset of patients for clinical correlation. Lastly, a cost analysis was performed to estimate the financial burden of unnecessary paired testing. Results: TRAb and TSI were co-ordered on the same encounter in 14.3% of TRAb/TSI-BA orders and 17.4% of TRAb/TSI-Br orders. Qualitative comparison showed discordance in 12.5% (1590) of TRAb and TSI-BA paired orders and 6.6% (1149) of TRAb and TSI-Br paired orders. Based on patient free thyroxine and TSH concentrations and disease status, the TSI assays aligned better with hyperthyroidism and confirmed Graves disease diagnoses. Paired orders resulted in a 31% to 325% increase in potentially unnecessary testing costs. Conclusion: We observed good clinical and analytical agreement between TRAb and TSI assays, suggesting that paired orders for TRAb and TSI are redundant in the assessment of autoimmune-mediated hyperthyroidism. Use of a single test to assess TRAb would be appropriate in most scenarios and may lead to considerable savings of health care dollars.

Alcohol is the most abused substance in Western society, resulting in major economic losses and negative health consequences. Therefore, there is a need for a selective and robust detection method for alcohol consumption in various clinical and forensic settings. This study aimed to validate a mass spectrometry method for quantifying phosphatidylethanol (PEth) and perform retrospective data analysis from the patient population of a national reference laboratory. Quantification of PEth in whole blood was accomplished using an LC–MS-MS assay. Isotopically labeled internal standard for the two PEth homologues was added to the whole-blood specimen, followed by protein precipitation with a mixture of acetonitrile and isopropyl alcohol. After centrifugation, an aliquot of the supernatant was buffered with ammonium acetate before LC–MS–MS analysis on an Agilent 6470 triple quadrupole mass spectrometer coupled to an Agilent 1260 Infinity II LC system. This LC–MS-MS assay was validated for clinical use in accordance with Clinical & Laboratory Standards Institute guidelines. The analytical measurement range, 10–2000 ng/mL, was linear with R2 of 0.999. The within-run and total imprecision was < 5% CV for the low (20 ng/mL), medium (200 ng/mL), and high QC (1000 ng/mL). Results from accuracy and method comparison experiments met the bias criteria of ±15%. Retrospective data analysis showed ∼27% of patients had PEth concentrations <20 ng/mL. Males and females had similar positivity rates for PEth and the positivity rate of women of reproductive age (15–44 years old) was 35% in comparison to 25% in women 45–89 years old. This study’s LC–MS-MS method showed acceptable analytical performance in quantifying PEth as a sensitive and specific biomarker for evaluating alcohol consumption. Results from this study may provide an opportunity to educate women of reproductive age on drinking during pregnancy and the long-term effects of alcohol use.

Objectives: Early rheumatoid arthritis (RA) detection is crucial for improving patient prognosis. Anticyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factors (RF) support RA diagnosis but are undetectable in ∼20 % of cases. Recently, antibodies against mutated citrullinated vimentin (anti-MCV) and detection of 14-3-3 eta have emerged with implications for preclinical RA diagnosis and monitoring treatment. The objective of this study was to assess the clinical performance of anti-MCV antibodies and 14-3-3 eta in RA and to compare it to current RA criteria anti-CCP and RF markers, individually and in combination. Methods: A retrospective chart review of 326 subjects submitted for RA serology testing identified 134 RA positive and 192 RA negative disease control individuals. Fifty healthy controls specimens were also included. Performance of anti-MCV and 14-3-3 eta, alone and combined with CCP3.1 and RF, was assessed. Results: Anti-MCV had a sensitivity of 71 % and a specificity of 92 %. 14-3-3 eta had a sensitivity of 43 % and a specificity of 90 %. In comparison, CCP3.1 and RF displayed a sensitivity of 79 % and 84 % and a specificity of 92 % and 61 %, respectively. ROC curve analysis demonstrated CCP3.1 and anti-MCV had superior diagnostic performance compared to RF and 14-3-3 eta. In our cohort, anti-MCV and 14-3-3 eta failed to identify seronegative RA patients. Different combinations of double antibody positivity increased specificity at the cost of lost sensitivity. Conclusions: Individually, 14-3-3 eta, anti-MCV and CCP3.1 assays had ≥90 % specificity in diagnosed RA patients, with better sensitivities for anti-MCV and CCP3.1 than 14-3-3 eta. Overall diagnostic performance of anti-MCV was similar to CCP3.1 and RF, all of which outperformed 14-3-3 eta in our cohort.

Background: Detection of anticyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factors (RF) in sera support the diagnosis of rheumatoid arthritis (RA); however, these markers are not detected in about 20% of RA patients. More recently, antibodies against carbamylated proteins (anti-CarP) have emerged with implications for preclinical RA diagnosis. The objective of this study was to assess the clinical performance of anti-CarP and correlate with disease severity in routine clinical practice. Methods: Retrospective chart review of 331 subjects submitted for RA panel serology: 136 clinically defined RA-positive and 195 RA-negative patients. Fifty additional individuals were recruited for healthy controls. Patients’ sera were tested for anti-CCP, anti-CarP, and RF antibodies. Clinical performance characteristics were evaluated for anti-CarP individually and in combination with anti-CCP and RF. Documented erosions and synovitis were correlated with anti-CarP positivity. Results: Anti-CarP had a clinical sensitivity and specificity of 27% and 94%, respectively, for established RA. This sensitivity was lower than anti-CCP (79%) and RF (85%). The specificity of anti-CarP was similar to anti-CCP (93%) and higher than RF (69%). Anti-CarP in combination with anti-CCP and RF increased specificity (100%) but decreased sensitivity (21%). There was no correlation of anti-CarP positivity with presence of bone erosions; however, there was an increase in anti-CarP positivity among patients with synovitis. Conclusions: Anti-CarP demonstrates high specificity in diagnosis of established RA but lacks clinical sensitivity. In combination, anti-CarP does not improve clinical performance of anti-CCP and RF but may be useful in anti-CCP negative patients and in identifying patients with more active disease.

The pancreatic islets of Langerhans, which are small 3D collections of specialized endocrine and supporting cells interspersed throughout the pancreas, have a central role in the control of glucose homeostasis through the secretion of insulin by beta cells, which lowers blood glucose, and glucagon by alpha cells, which raises blood glucose. Intracellular signaling pathways, including those mediated by cAMP, are key for regulated alpha and beta cell hormone secretion. The 3D islet structure, while essential for coordinated islet function, presents experimental challenges for mechanistic studies of the intracellular signaling pathways in primary human islet cells. To overcome these challenges and limitations, this protocol describes an integrated live-cell imaging and microfluidic platform using primary human pseudoislets generated from donors without diabetes that resemble native islets in their morphology, composition, and function. These pseudoislets are size-controlled through the dispersion and reaggregation process of primary human islet cells. In the dispersed state, islet cell gene expression can be manipulated; for example, biosensors such as the genetically encoded cAMP biosensor, cADDis, can be introduced. Once formed, pseudoislets expressing a genetically encoded biosensor, in combination with confocal microscopy and a microperifusion platform, allow for the synchronous assessment of fluorescent biosensor dynamics and alpha and beta cell hormone secretory profiles to provide more insight into cellular processes and function.