scholarly journals Validation of a novel fluorescent lateral flow assay for rapid qualitative and quantitative assessment of total anti-SARS-CoV-2 S-RBD binding antibody units (BAU) from plasma or fingerstick whole-blood of COVID-19 vaccinees

2022 ◽  
Author(s):  
Nadin Younes ◽  
Duaa Walid Al-Sadeq ◽  
Farah Shurrab ◽  
Hadeel Zedan ◽  
Haissam Abou Saleh ◽  
...  
Keyword(s):  
Whole Blood ◽  
Quantitative Measurement ◽  
Pearson Correlation ◽  
Protein S ◽  
Receptor Binding Domain ◽  
Moderate Correlation ◽  
Post Vaccination ◽  
Qualitative And Quantitative ◽  
Rapid Prediction ◽  
Binding Antibody

Background: Limited commercial LFA assays are available to provide a reliable quantitative measurement of the total binding antibody units (BAU/mL) against the receptor-binding domain of the SARS-CoV-2 spike protein (S-RBD). Aim: To evaluate the performance of FinecareTM2019-nCoV S-RBD LFA and its fluorescent reader (FinecareTM-FIA Meter) against the following reference methods (i) The FDA-approved Genscript surrogate virus-neutralizing assay (sVNT), and (ii) three highly performing automated immunoassays: BioMerieux VIDAS, Ortho VITROS, and Mindray CL-900i. Methods: Plasma from 488 vaccinees were tested by all aforementioned assays. Fingerstick whole-blood samples from 156 vaccinees were also tested by FinecareTM. Results and conclusions: FinecareTM showed 100% specificity as none of the pre-pandemic samples tested positive. Equivalent FinecareTM results were observed among the samples taken from fingerstick or plasma (Pearson correlation r=0.9, p<0.0001), suggesting that fingerstick samples are sufficient to quantitate the S-RBD BAU/mL. A moderate correlation was observed between FinecareTM and sVNT (r=0.5, p<0.0001), indicating that FinecareTM can be used for rapid prediction of the neutralization antibody post-vaccination. FinecareTM BAU results showed strong correlation with VIDAS (r=0.6, p<0.0001), and moderate correlation with VITROS (r=0.5, p<0.0001), and CL-900 (r=0.4, p<0.0001), suggesting that FinecareTM be used as a surrogate for the advanced automated assays to measure S-RBD BAU/mL.

scholarly journals Performance evaluation of novel fluorescent-based lateral immune flow assay (LIFA) for rapid detection and quantitation of total anti-SARS-CoV-2 S-RBD binding antibodies in infected individuals

2022 ◽  
Author(s):  
Farah M. Shurrab ◽  
Nadin Younes ◽  
Duaa W. Al-Sadeq ◽  
Hamda Qotba ◽  
Laith J. Abu-Raddad ◽  
...  
Keyword(s):  
Quantitative Measurement ◽  
Neutralizing Antibody ◽  
Kappa Statistic ◽  
Protein S ◽  
Rt Pcr ◽  
Qualitative And Quantitative ◽  
Automated Assay ◽  
Quantitative Validation ◽  
Binding Antibody ◽  
Response Post

1.AbstractBackgroundThe vast majority of the commercially available LFIA is used to detect SARS-CoV-2 antibodies qualitatively. Recently, a novel fluorescence-based LIFA test was developed for quantitative measurement of the total binding antibody units (BAU/mL) against the receptor-binding domain of the SARS-CoV-2 spike protein (S-RBD).AimTo evaluate the performance of the fluorescence LIFA Finecare™ 2019-nCoV S-RBD test along with its reader (Model No.: FS-113).MethodsPlasma from 150 RT-PCR confirmed-positive individuals and 100 pre-pandemic samples were tested by FinCare™ to access sensitivity and specificity. For qualitative and quantitative validation of the FinCar™ measurements, the BAU/mL results of FinCare™ were compared with results of two reference assays: the surrogate virus-neutralizing test (sVNT, GenScript, USA), and the VIDAS®3 automated assay (BioMérieux, France).ResultsFinecare™ showed 92% sensitivity and 100% specificity compared to PCR. Cohen’s Kappa statistic denoted moderate and excellent agreement with sVNT and VIDAS®3, ranging from 0.557 (95% CI: 0.32-0.78) to 0.731 (95% CI: 0.51-0.95), respectively. A strong correlation was observed between Finecare™/sVNT (r=0.7, p<0.0001) and Finecare™/VIDAS®3 (r=0.8, p<0.0001).ConclusionFinecare™ is a reliable assay and can be used as a surrogate to assess binding and neutralizing antibody response post-infection or vaccination, particularly in none or small laboratory settings.

Reliability of the Minimum Masking Level as Outcome Variable in Tinnitus Clinical Research

2020 ◽  
Vol 29 (3) ◽  
pp. 429-435
Author(s):  
Patricia C. Mancini ◽  
Richard S. Tyler ◽  
Hyung Jin Jun ◽  
Tang-Chuan Wang ◽  
Helena Ji ◽  
...  
Keyword(s):  
Standard Deviation ◽  
High Frequency ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Outcome Variable ◽  
Reliable Estimate ◽  
Moderate Correlation ◽  
Trained Subjects ◽  
The Relationship ◽  
Minimum Intensity

Purpose The minimum masking level (MML) is the minimum intensity of a stimulus required to just totally mask the tinnitus. Treatments aimed at reducing the tinnitus itself should attempt to measure the magnitude of the tinnitus. The objective of this study was to evaluate the reliability of the MML. Method Sample consisted of 59 tinnitus patients who reported stable tinnitus. We obtained MML measures on two visits, separated by about 2–3 weeks. We used two noise types: speech-shaped noise and high-frequency emphasis noise. We also investigated the relationship between the MML and tinnitus loudness estimates and the Tinnitus Handicap Questionnaire (THQ). Results There were differences across the different noise types. The within-session standard deviation averaged across subjects varied between 1.3 and 1.8 dB. Across the two sessions, the Pearson correlation coefficients, range was r = .84. There was a weak relationship between the dB SL MML and loudness, and between the MML and the THQ. A moderate correlation ( r = .44) was found between the THQ and loudness estimates. Conclusions We conclude that the dB SL MML can be a reliable estimate of tinnitus magnitude, with expected standard deviations in trained subjects of about 1.5 dB. It appears that the dB SL MML and loudness estimates are not closely related.

scholarly journals Molecular Species of the Alcohol Biomarker Phosphatidylethanol in Human Blood Measured by LC-MS

2009 ◽  
Vol 55 (7) ◽  
pp. 1395-1405 ◽  
Author(s):  
Anders Helander ◽  
Yufang Zheng
Keyword(s):  
Fatty Acid ◽  
Human Blood ◽  
Molecular Species ◽  
Quantitative Measurement ◽  
Selected Ion Monitoring ◽  
Blood Samples ◽  
Qualitative And Quantitative ◽  
Ms Analysis ◽  
Alcohol Biomarker ◽  
Product Ions

Abstract Background: The alcohol biomarker phosphatidylethanol (PEth) comprises a group of ethanol-derived phospholipids formed from phosphatidylcholine by phospholipase D. The PEth molecular species have a common phosphoethanol head group onto which 2 fatty acid moieties are attached. We developed an electrospray ionization (ESI) LC-MS method for qualitative and quantitative measurement of different PEth species in human blood. Methods: We subjected a total lipid extract of whole blood to HPLC gradient separation on a C4 column and performed LC-ESI-MS analysis using selected ion monitoring of deprotonated molecules for the PEth species and phosphatidylpropanol (internal standard). Identification of individual PEth species was based on ESI–tandem mass spectrometry (MS/MS) analysis of product ions. Results: The fatty acid moieties were the major product ions of PEth, based on comparison with PEth-16:0/16:0, 18:1/18:1, and 16:0/18:1 reference material. For LC-MS analysis of different PEth species in blood, we used a calibration curve covering 0.2–7.0 μmol/L PEth-16:0/18:1. The lower limit of quantitation of the method was &lt;0.1 μmol/L, and intra- and interassay CVs were &lt;9% and &lt;11%. In blood samples collected from 38 alcohol patients, the total PEth concentration ranged between 0.1 and 21.7 μmol/L (mean 8.9). PEth-16:0/18:1 and 16:0/18:2 were the predominant molecular species, accounting for approximately 37% and 25%, respectively, of total PEth. PEth-16:0/20:4 and mixtures of 18:1/18:1 plus 18:0/18:2 (not separated using selected ion monitoring because of identical molecular masses) and 16:0/20:3 plus 18:1/18.2 made up approximately 13%, 12%, and 8%. Conclusions: This LC-MS method allows simultaneous qualitative and quantitative measurement of several PEth molecular species in whole blood samples.

Relation of Maximal Ankle Dorsiflexion Angle and Passive Resistive Torque to Passive-Elastic Stiffness of Ankle Dorsiflexion Stretch

2002 ◽  
Vol 95 (1) ◽  
pp. 323-325 ◽  
Author(s):  
Richard L. Gajdosik ◽  
Ann K. Williams
Keyword(s):  
Multiple Regression ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Elastic Stiffness ◽  
Ankle Dorsiflexion ◽  
Regression Analyses ◽  
Moderate Correlation ◽  
Ankle Stiffness ◽  
Resistive Torque ◽  
Clinical Measurements

The maximal passive ankle dorsiflexion angle and the maximal passive resistive torque at this angle were measured for 81 women 20 to 84 years of age and correlated with the passive-elastic stiffness (stiffness) of an ankle dorsiflexion stretch. Pearson correlation coefficients and multiple regression analyses were used to examine whether the two clinical measurements could predict ankle stiffness. The maximal passive resistive torque showed a moderate correlation with stiffness in the full stretch range ( r = .69) and high correlation with stiffness in the last half of the full stretch range ( r = .84). The maximal dorsiflexion angle showed a low correlation with stiffness in the full stretch range ( r = .27) and in the last half of the full stretch range ( r = .36). The maximal passive resistive torque and the dorsiflexion angle together accounted for 54% of the stiffness variance in the full stretch range and 76% of the stiffness variance in the last half of the full stretch range. Thus, the clinical measurements of the maximal passive dorsiflexion angle and the maximal passive resistive torque were directly and significantly related to the ankle dorsiflexion passive-elastic stiffness and good predictors of stiffness in the last half of the passive ankle dorsiflexion stretch.

scholarly journals Quantitative measurement of IgG to SARS-CoV-2 proteins using ImmunoCAP

2020 ◽  
Author(s):  
Behnam Keshavarz ◽  
Joesph R. Wiencek ◽  
Lisa J. Workman ◽  
Matthew D. Straesser ◽  
Lyndsey M. Muehling ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Quantitative Measurement ◽  
Solid Phase ◽  
Performance Characteristics ◽  
Quantitative Assay ◽  
Receptor Binding Domain ◽  
Serum Samples ◽  
Detailed Understanding ◽  
Antibody Assays

AbstractBackgroundDetailed understanding of the immune response to SARS-CoV-2, the cause of coronavirus disease 2019 (COVID-19), has been hampered by a lack of quantitative antibody assays.ObjectiveTo develop a quantitative assay for IgG to SARS-CoV-2 proteins that could readily be implemented in clinical and research laboratories.MethodsThe biotin-streptavidin technique was used to conjugate SARS-CoV-2 spike receptor-binding-domain (RBD) or nucleocapsid protein to the solid-phase of the ImmunoCAP resin. Plasma and serum samples from patients with COVID-19 (n=51) and samples from donors banked prior to the emergence of COVID-19 (n=109) were used in the assay. SARS-CoV-2 IgG levels were followed longitudinally in a subset of samples and were related to total IgG and IgG to reference antigens using an ImmunoCAP 250 platform.ResultsPerformance characteristics demonstrated 100% sensitivity and 99% specificity at a cut-off level of 2.5 µg/mL for both SARS-CoV-2 proteins. Among 36 patients evaluated in a post-hospital follow-up clinic, median levels of IgG to spike-RBD and nucleocapsid were 34.7 µg/mL (IQR 18-52) and 24.5 µg/mL (IQR 9-59), respectively. Among 17 patients with longitudinal samples there was a wide variation in the magnitude of IgG responses, but generally the response to spike-RBD and to nucleocapsid occurred in parallel, with peak levels approaching 100 µg/mL, or 1% of total IgG.ConclusionsWe have described a quantitative assay to measure IgG to SARS-CoV-2 that could be used in clinical and research laboratories and implemented at scale. The assay can easily be adapted to measure IgG to novel antigens, has good performance characteristics and a read-out in standardized units.

scholarly journals Convergent Antibody Responses to SARS-CoV-2 Infection in Convalescent Individuals

2020 ◽  
Author(s):  
Davide F. Robbiani ◽  
Christian Gaebler ◽  
Frauke Muecksch ◽  
Julio C. C. Lorenzi ◽  
Zijun Wang ◽  
...  
Keyword(s):  
Virus Entry ◽  
Protein S ◽  
Memory B Cells ◽  
Antibody Responses ◽  
Spike Protein ◽  
Human Antibody ◽  
Receptor Binding Domain ◽  
Single Digit ◽  
Specific Antibodies ◽  
Specific Memory

AbstractDuring the COVID-19 pandemic, SARS-CoV-2 infected millions of people and claimed hundreds of thousands of lives. Virus entry into cells depends on the receptor binding domain (RBD) of the SARS-CoV-2 spike protein (S). Although there is no vaccine, it is likely that antibodies will be essential for protection. However, little is known about the human antibody response to SARS-CoV-21–5. Here we report on 149 COVID-19 convalescent individuals. Plasmas collected an average of 39 days after the onset of symptoms had variable half-maximal neutralizing titers ranging from undetectable in 33% to below 1:1000 in 79%, while only 1% showed titers >1:5000. Antibody cloning revealed expanded clones of RBD-specific memory B cells expressing closely related antibodies in different individuals. Despite low plasma titers, antibodies to three distinct epitopes on RBD neutralized at half-maximal inhibitory concentrations (IC50s) as low as single digit ng/mL. Thus, most convalescent plasmas obtained from individuals who recover from COVID-19 do not contain high levels of neutralizing activity. Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective.

scholarly journals The correlation strength of the most important cryptocurrencies in the bull and bear market

2020 ◽  
Vol 17 (3) ◽  
pp. 67-81
Author(s):  
Sebastian Lahajnar ◽  
Alenka Rožanec
Keyword(s):  
Correlation Coefficient ◽  
Strong Correlation ◽  
Pearson Correlation ◽  
Pearson Correlation Coefficient ◽  
Strongly Correlated ◽  
Moderate Correlation ◽  
Bear Market ◽  
Research Findings ◽  
Correlation Strength ◽  
Over Time

The article explores the correlation strength of the ten most important cryptocurrencies, emphasizing the examination of differences during the periods of rising and falling prices. The daily and weekly returns of selected cryptocurrencies are taken as the basis for calculating and determining the correlation strength using the Pearson correlation coefficient. The survey covers the period from the beginning of 2017 to Bitcoin’s last local bottom in mid-March 2020. Research findings are as follows: 1) the most important cryptocurrencies are mostly moderately positively correlated with each other over time; 2) correlation strength decreases slightly during the bull period, but mostly remain in the range of moderate correlation; 3) correlation strength increases significantly during the bear period, with most cryptocurrencies strongly correlated with each other. The results do not change significantly if the daily or weekly cryptocurrency returns are used as the basis. A strong correlation in the period of falling prices prevents the effective diversification of the cryptocurrency portfolio, which must be considered when investing funds in the cryptocurrency market.

scholarly journals SARS-CoV-2 Convalescent Sera Binding and Neutralizing Antibody Concentrations Compared with COVID-19 Vaccine Efficacy Estimates Against Symptomatic Infection

2021 ◽  
Author(s):  
Amy J. Schuh ◽  
Panayampalli S. Satheshkumar ◽  
Stephanie Dietz ◽  
Lara Bull-Otterson ◽  
Myrna Charles ◽  
...  
Keyword(s):  
Vaccine Efficacy ◽  
Neutralizing Antibody ◽  
Published Data ◽  
Symptomatic Infection ◽  
Convenience Sample ◽  
Post Vaccination ◽  
Antibody Assays ◽  
Study Population ◽  
Binding Antibody ◽  
Induced Immunity

Previous vaccine efficacy (VE) studies have estimated neutralizing and binding antibody concentrations that correlate with protection from symptomatic infection; how these estimates compare to those generated in response to SARS-CoV-2 infection is unclear. Here, we assessed quantitative neutralizing and binding antibody concentrations using standardized SARS-CoV-2 assays on 3,067 serum specimens collected during July 27, 2020-August 27, 2020 from COVID-19 unvaccinated persons with detectable anti-SARS-CoV-2 antibodies using qualitative antibody assays. Quantitative neutralizing and binding antibody concentrations were strongly positively correlated (r=0.76, p<0.0001) and were noted to be several fold lower in the unvaccinated study population as compared to published data on concentrations noted 28 days post-vaccination. In this convenience sample, ~88% of neutralizing and ~63-86% of binding antibody concentrations met or exceeded concentrations associated with 70% COVID-19 VE against symptomatic infection from published VE studies; ~30% of neutralizing and 1-14% of binding antibody concentrations met or exceeded concentrations associated with 90% COVID-19 VE. These data support observations of infection-induced immunity and current recommendations for vaccination post infection to maximize protection against symptomatic COVID-19.

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