Evaluation of the Atellica TnIH cardiac troponin I assay and assessment of biological equivalence

Objectives We evaluated the analytical performance characteristics and the biological equivalence of the Atellica TnIH assay. Methods Precision, detection capability, linearity, and sex specific 99th percentiles were determined de novo. Classification of patients relative to the 99th percentiles was used to assess biological equivalence. Results Analytical precision and detection capability of the Atellica TnIH assay is excellent with a limit of blank <1 ng/L and 62.5% of women and 93% of men had results above the limit of detection. The 99th percentiles (90% CI) in women were 49 ng/L (31–67) and 70 ng/L (48–121) in men. An asymmetrical distribution involving 5% of results was notable. Agreement was moderate (Kappa 0.58, 95% CI 0.53–0.63) with 20% of patients discordantly classified with Atellica TnIH below and Access hsTnI above the 99th percentiles. Serial results in 195 patients demonstrated good agreement (Kappa 0.84, 95% CI 0.77–0.90). Differences greater than the assay specific reference change values (z≥±1.96) occurred in 65% (95% CI 53–76%) of 99th percentile discordant patients compared to 2.7% (p<0.001) and 76% (p=0.17) of the concordant low and high cTnI groups respectively. Conclusions The 99th percentile discordant and the concordantly elevated groups are more alike with respect to their z≥±1.96 rates. This favours an overestimated Atellica TnIH 99th percentile as more likely, and we hypothesize that antibody interference resulting in asymmetric scatter of nearly 5% samples may be the underlying mechanism. Analytical accuracy and interferences in cardiac troponin assays should be investigated and resolved with high priority.

A Comprehensive, Targeted NGS Approach to Assessing Molecular Diagnosis of Lysosomal Storage Diseases

With over 60 different disorders and a combined incidence occurring in 1:5000–7000 live births, lysosomal storage diseases (LSDs) represent a major public health problem and constitute an enormous burden for affected individuals and their families. Several reasons make the diagnosis of LSDs an arduous task for clinicians, including the phenotype and penetrance variability, the shared signs and symptoms, and the uncertainties related to biochemical enzymatic assay results. Developing a powerful diagnostic tool based on next generation sequencing (NGS) technology may help reduce the delayed diagnostic process for these families, leading to better outcomes for current therapies and providing the basis for more appropriate genetic counseling. Herein, we employed a targeted NGS-based panel to scan the coding regions of 65 LSD-causative genes. A reference group sample (n = 26) with previously known genetic mutations was used to test and validate the entire workflow. Our approach demonstrated elevated analytical accuracy, sensitivity, and specificity. We believe the adoption of comprehensive targeted sequencing strategies into a routine diagnostic route may accelerate both the identification and management of LSDs with overlapping clinical profiles, producing a significant reduction in delayed diagnostic response with beneficial results in the treatment outcome.

Validation of a Novel IoT and AI based Point-of-Care Testing Laboratory: Analytical Accuracy and Clinical Agreement

Point-of-care testing (POCT) offers several advantages over traditional laboratory testing. Offering less invasive testing with a faster turnaround time is not enough if not associated with an acceptable level of accuracy. Here, we show the analytical validation behind the multi-analyte POCT immunochromatography analyser, Hilab Flow (HiF). Analyses from 4,518 clinical samples were compared to College of American Pathologists accredited laboratories for ten quantitative and thirteen qualitative exams. Compatibility between methods was evaluated in terms of association/correlation and clinical agreement. Strong correlation/ concordance was observed between quantitative (CHOL, HDL-c, TG, HbA1c, Glycemia, 25-Hydroxy Vitamin D, TSH, Uric Acid, Creatinine, Urea) and qualitative methods (COVID-19 IgG/ IgM, Beta-hCG, Syphilis, Anti-HBsAg, Zika IgG/ IgM, Influenza A/B, HIV, HCV, HBsAg, Dengue NS1, COVID-19 Ag, Dengue IgG/ IgM, PSA). Approval criteria was obtaining a kappa agreement > 0.8 or a Pearson correlation > 0.9 depending on the exam. Overall percentage agreement was greater than 95% for all exams, indicating a good clinical agreement to gold-standard laboratory-based tests. Results indicate all exams are suitable for POCT and present a reliable performance. Data support the analyser is a useful tool to aid decision-making at the clinical setting, with potential to contribute with healthcare solutions in diagnostic medicine worldwide.

Large dependency of intracellular NAD and CoA pools on cultivation conditions in Saccharomyces cerevisiae

Objective The objective of this study was to investigate the variation of NAD and CoA metabolite pools in Saccharomyces cerevisiae cultivated under various cultivation conditions. This study complements a previous report on glycolytic, pentose phosphate pathway, tricarboxylic acid cycle, amino acids, and deoxy-/nucleoside phosphate pools determined under the same cultivation conditions. Results S. cerevisiae pellets from batch (four carbohydrate sources) and chemostat (carbon-, nitrogen-, phosphate—limited and a range of dilution rates) bioreactor cultivations were extracted and analyzed with two recently established absolute quantitative liquid chromatography mass spectrometry (LC–MS/MS) methods for NAD and CoA metabolites. Both methods apply 13C internal standard dilution strategy for the enhanced analytical accuracy and precision. Individual metabolite pools were relatively constant for the different growth rates within the same mode of cultivation, but large differences were observed among some of the modes, i.e. NAD metabolites were 10 to 100-fold lower in nitrogen limited chemostats compared to the other modes, and phosphate limited chemostats were characterized with much lower CoA metabolite pools. The results complement the previous results and together provide a comprehensive insight into primary metabolite pools variations at a large range in growth and carbon source consumption rates.

Quantitative Electron-Excited X-ray Microanalysis With Low-Energy L-shell X-ray Peaks Measured With Energy-Dispersive Spectrometry

Quantification of electron-exited X-ray spectra following the standards-based “k-ratio” (unknown/standard intensity) protocol with corrections for “matrix effects” (electron energy loss and backscattering, X-ray absorption, and secondary X-ray fluorescence) is a well-established method with a record of rigorous testing and extensive experience. Two recent studies by Gopon et al. working in the Fe–Si system and Llovet et al. working in the Ni–Si system have renewed interest in studying the accuracy of measurements made using L-shell X-ray peaks. Both have reported unexpectedly large deviations in analytical accuracy when analyzing intermetallic compounds when using the low photon energy Fe or Ni L-shell X-ray peaks with pure element standards and wavelength-dispersive X-ray spectrometry. This study confirms those observations on the Ni-based intermetallic compounds using energy-dispersive X-ray spectrometry and extends the study of analysis with low photon energy L-shell peaks to a wide range of elements, Ti to Se. Within this range of elements, anomalies in analytical accuracy have been found for Fe, Co, and Ge in addition to Ni. For these elements, the use of compound standards instead of pure elements usually resulted in significantly improved analytical accuracy. However, compound standards do not always provide satisfactory accuracy as is demonstrated for L-shell peak analysis in the Fe–S system: FeS and FeS2 unexpectedly do not provide good accuracy when used as mutual standards.

Evaluation of Surf Field Mastitis Test (SFMT) For the Detection of Subclinical Mastitis in Dairy Cows

Background: Subclinical mastitis (SCM) continues to be one of the major economic diseases of dairy animal. For effective management of SCM prompt early detection is required at the field level. Present study deals with evaluation of Surf Field Mastitis Test (SFMT) - the cow side, on-farm and field level SCM detection test and its comparison with established tests. Methods: Holstein Friesian and Jersey crossbred dairy cows quarter milk (n=72) were tested for SCM using California Mastitis Test (CMT) and somatic cell count (SCC). Result: In comparison, CMT showed higher inclusivity and negative predictivity; while, SFMT had higher exclusivity and positive predictivity. Nevertheless, both CMT and SFMT tests performed equally in the detection of SCM as measured by analytical accuracy (84.72%). In comparison to the SCC, both CMT and SFMT showed strong concordance (kappa value of 0.7 agreements each). However, between CMT and SFMT moderate agreement was observed (kappa value 0.58). Further, in comparison to SCC, SFMT showed higher diagnostic sensitivity of 94.74% than the CMT 73.68%; specificity of CMT was higher (97.06%) than the SFMT (73.53%). Results of the present study indicated practical applications of SFMT for the detection of SCM owing to accessibility and ease of doing SFMT and its diagnostic capabilities in comparison to the widely accepted CMT. Keeping in view, the economic significance of SCM among crossbred dairy cows and need for its early diagnosis at the field level; findings of this study recommend popularization of SFMT among dairy farmers so as to control SCM in time and avoid associated economic losses to the dairy farmers.

Monitoring SARS-CoV-2 in sewage: toward sentinels with analytical accuracy

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemia has been one of the most difficult challenges humankind has recently faced. Wastewater-based epidemiology has emerged as a tool for surveillance and mitigation of potential viral outbreaks, circumventing biases introduced by clinical patient testing. Due to the situation urgency, protocols followed for isolating viral RNA from sewage were not adapted for such sample matrices. In parallel to their implementation for fast collection of data to sustain surveillance and mitigation decisions, molecular protocols need to be harmonized to deliver accurate, reproducible, and comparable analytical outputs. Here we studied analytical variabilities linked to viral RNA isolation methods from sewage. Three different influent wastewater volumes were used to assess the effect of filtered volumes (50, 100 or 500 mL) for capturing viral particles. Three different concentration strategies were tested by electronegative membranes, polyethersulfone membranes, and anion-exchange diethylaminoethyl cellulose columns. To compare the number of viral particles, different RNA isolation methods (column-based vs. magnetic beads) were compared. The effect of extra RNA purification steps and different RT-qPCR strategies (one step vs. two-step) were also evaluated. Results showed that the combination of 500 mL filtration volume through electronegative membranes and without multiple RNA purification steps (using column-based RNA purification) using two-step RT-qPCR avoided false negatives when basal viral load in sewage are present and yielded more consistent results during the surveillance done during the second-wave in Delft (The Hague area, The Netherlands). By paving the way for standardization of methods for the sampling, concentration and molecular detection of SARS-CoV-2 viruses from sewage, these findings can help water and health surveillance authorities to use and trust results coming from wastewater based epidemiology studies in order to anticipate SARS-CoV-2 outbreaks.

Thin Film Plastic Antibody-Based Microplate Assay for Human Serum Albumin Determination

Herein we demonstrate molecularly imprinted polymers (MIP) as plastic antibodies for a microplate-based assay. As the most abundant plasma protein, human serum albumin (HSA) was selected as the target analyte model. Thin film MIP was synthesized by the surface molecular imprinting approach using HSA as the template. The optimized polymer consisted of acrylic acid (AA) and N-vinylpyrrolidone (VP) in a 2:3 (w/w) ratio, crosslinked with N,N′-(1,2-dihydroxyethylene) bisacrylamide (DHEBA) and then coated on the microplate well. The binding of MIP toward the bound HSA was achieved via the Bradford reaction. The assay revealed a dynamic detection range toward HSA standards in the clinically relevant 1–10 g/dL range, with a 0.01 g/dL detection limit. HSA-MIP showed minimal interference from other serum protein components: γ-globulin had 11% of the HSA response, α-globulin of high-density lipoprotein had 9%, and β-globulin of low-density lipoprotein had 7%. The analytical accuracy of the assay was 89–106% at the 95% confidence interval, with precision at 4–9%. The MIP-coated microplate was stored for 2 months at room temperature without losing its binding ability. The results suggest that the thin film plastic antibody system can be successfully applied to analytical/pseudoimmunological HSA determinations in clinical applications.

Quantification of Teicoplanin Using the HPLC-UV Method for Clinical Applications in Critically Ill Patients in Korea

A high-performance liquid chromatography-ultraviolet detector (HPLC-UV) method has been used to quantify teicoplanin concentrations in human plasma. However, the limited analytical accuracy of previously bioanalytical methods for teicoplanin has given rise to uncertainty due to the use of an external standard. In this study, an internal standard (IS), polymyxin B, was applied to devise a precise, accurate, and feasible HPLC-UV method. The deproteinized plasma sample containing teicoplanin and an IS of acetonitrile was chromatographed on a C18 column with an acidic mobile phase consisting of NaH2PO4 buffer and acetonitrile (78:22, v/v) by isocratic elution and detection at 220 nm. The linearity was in the range 7.8–500 mg/L calculated by the ratio of the teicoplanin signal to the IS signal. This analytical method, validated by FDA guidelines with ICH Q2 (R1), was successfully applied to analyze the plasma samples of patients in the intensive care unit for treating serious resistant bacterial infectious diseases, such as those by methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. The methods suggested the potential for use in routine clinical practice for therapeutic drug monitoring of teicoplanin, providing both improved accuracy and a wide range of linearity from lower than steady-state trough concentrations (10 mg/L) to much higher concentrations.