Investigation of an Adventitious Agent Test False Positive Signal in a Plant-Derived Influenza Vaccine

2018 ◽  
Vol 17 ◽  
Author(s):  
Todd Talarico ◽  
Michael Murphy ◽  
Raymond Nims ◽  
Dan Hastings ◽  
Jeri Ann Boose ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
False Positive ◽  
Positive Signal ◽  
False Positive Signal

T7 exo-mediated FRET-breaking combined with DSN–RNAse–TdT for the detection of microRNA with ultrahigh signal-amplification

The Analyst ◽  
2019 ◽  
Vol 144 (10) ◽  
pp. 3216-3220 ◽  
Author(s):  
Van Thang Nguyen ◽  
Binh Huy Le ◽  
Young Jun Seo
Keyword(s):  
False Positive ◽  
Signal Amplification ◽  
High Sensitivity ◽  
Positive Signal ◽  
False Positive Signal ◽  
Breaking Mechanism ◽  
Very High

A DSN–RNAse–TdT–T7 exo probing system allows the detection of miRNA 21 with very high sensitivity (LOD = 2.57 fM) and selectivity—the result of (i) avoiding the false-positive signal from miRNA reacting with TdT polymerase and (ii) signal amplification occurring through a FRET-breaking mechanism involving T7 exo.

False positive signal-averaged electrocardiogram produced by atrial flutter

1990 ◽  
Vol 120 (3) ◽  
pp. 698-699 ◽  
Author(s):  
Stanley S. Schrem ◽  
Mark Nachamie ◽  
Edwin Weiss
Keyword(s):  
Atrial Flutter ◽  
False Positive ◽  
Positive Signal ◽  
False Positive Signal

Optimal late potential criteria for reducing false positive signal-averaged electrocardiograms

1992 ◽  
Vol 123 (2) ◽  
pp. 412-416 ◽  
Author(s):  
Debra K. Moser ◽  
William G. Stevenson ◽  
Mary A. Woo
Keyword(s):  
False Positive ◽  
Positive Signal ◽  
False Positive Signal ◽  
Late Potential

scholarly journals Development of an Immunochromatographic Test Strip for Detection of Cholera Toxin

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Eiki Yamasaki ◽  
Ryuta Sakamoto ◽  
Takashi Matsumoto ◽  
Fumiki Morimatsu ◽  
Takayuki Kurazono ◽  
...  
Keyword(s):  
Detection Limit ◽  
Cholera Toxin ◽  
False Positive ◽  
Culture Supernatant ◽  
Polyclonal Antibodies ◽  
High Specificity ◽  
Test Strip ◽  
Immunochromatographic Test ◽  
Positive Signal ◽  
False Positive Signal

Because cholera toxin (CT) is responsible for most of the symptoms induced byVibrio choleraeinfection, detection of CT is critical for diagnosis of the disease. In this study, we constructed an immunochromatographic test strip for detection of CT (CT-IC) with polyclonal antibodies developed against purified recombinant whole CT protein. The detection limit of the CT-IC was 10 ng/mL of purified recombinant CT, and it could detect the CT in culture supernatant of all 15 toxigenicV. choleraeisolates examined, whereas no false-positive signal was detected in all 5 nontoxigenicV. choleraeisolates examined. The specificity of the CT-IC was examined with recombinant heat-labile toxin (LT), which shares high homology with CT, and it was revealed that the minimum detection limit for LT was 100 times higher than that for CT. In addition,ltgene-positive enterotoxigenicEscherichia coli(ETEC) was examined by CT-IC. The false-positive signals were observed in 3 out of 12 ETEC isolates, but these signals were considerably faint. The CT-IC did not develop false-positive signals with all 7V. parahaemolyticusisolates. These results showed the high specificity of CT-IC and the feasible use of it for the detection and surveillance of toxigenicV. cholerae.

False positive signal-averaged ECG produced by junctional rhythm with retrograde P waves

1992 ◽  
Vol 123 (6) ◽  
pp. 1701-1703 ◽  
Author(s):  
Eric Taylor ◽  
Mark Effron ◽  
Enrico P. Veltri
Keyword(s):  
False Positive ◽  
Positive Signal ◽  
P Waves ◽  
Junctional Rhythm ◽  
False Positive Signal

Overcoming multimeric target interference in a bridging immunogenicity assay with soluble target receptor, target immunodepletion and mild acidic assay pH

Bioanalysis ◽  
2020 ◽  
Vol 12 (15) ◽  
pp. 1071-1085
Author(s):  
Jihua Chen ◽  
Kimberly Kendra ◽  
Albert Torri ◽  
Giane Sumner
Keyword(s):  
False Positive ◽  
Magnetic Beads ◽  
Positive Signal ◽  
Background Signal ◽  
Serum Samples ◽  
Post Dose ◽  
High Background ◽  
False Positive Signal ◽  
Acidic Conditions ◽  
Immunogenicity Assay

Background: Soluble multimeric target proteins can generate a target-mediated false-positive signal in bridging anti-drug antibody (ADA) assays. A high background signal due to target interference was observed in our anti-REGN-Y antibody assay, and two different strategies were evaluated to mitigate this false-positive signal. Results: Multiple anti-target antibodies were tested and found to be ineffective at reducing target interference, so soluble target receptor and co-factor proteins were used in combination to inhibit the target-mediated signal. These competitive blockers synergistically inhibited target interference and increased target tolerance levels, especially when the assay was performed under mild acidic conditions. A separate approach, target immunodepletion using magnetic beads conjugated with an anti-target antibody, was also effective at mitigating the target-mediated signal, also in combination with mild acidic assay pH. Both methods allowed detection of a true ADA signal in monkey and human post-dose serum samples. Conclusion: These methods provide alternative strategies for mitigating target interference when standard anti-target antibodies are ineffective, with the competitive blocker method being recommended, if possible, due to its higher throughput and easier execution.

scholarly journals False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

2021 ◽  
Vol 12 ◽  
Author(s):  
Nastya Kharlamova ◽  
Nicky Dunn ◽  
Sahl K. Bedri ◽  
Svante Jerling ◽  
Malin Almgren ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
False Positive ◽  
Inflammatory Diseases ◽  
Serological Tests ◽  
Chronic Inflammatory Diseases ◽  
Negative Results ◽  
False Positive Signal ◽  
Lateral Flow Assays ◽  
Positive Results ◽  
Multiplex Bead

Patients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless they tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays using samples from patients with chronic inflammatory diseases collected prior to April 2019, thus defined as negative. Samples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and systemic lupus erythematosus (SLE, n=10) with or without RF, were analyzed for SARS-CoV-2 antibodies using 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed IgG multiplex bead-based assay. Six LFA and the in-house validated IgG assay correctly produced negative results for all samples. However, the majority of assays (n=13), gave false positive signal for samples from patients with RA and SLE. This was most notable in samples from RF positive RA patients. No false positive samples were detected in any assay using samples from patients with MS. Poor specificity of commercial serological assays could possibly be, at least partly, due to interfering antibodies in samples from patients with chronic inflammatory diseases. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

Tracking recorded fires using charcoal morphology from the sedimentary sequence of Prosser Lake, British Columbia (Canada)

2006 ◽  
Vol 65 (02) ◽  
pp. 282-292 ◽  
Author(s):  
Mihaela D. Enache ◽  
Brian F. Cumming
Keyword(s):  
British Columbia ◽  
Minor Axis ◽  
Burned Area ◽  
High Porosity ◽  
Positive Signal ◽  
Axis Ratio ◽  
Area Burned ◽  
False Positive Signal ◽  
Quantitative Analyses ◽  
Sedimentation Processes

AbstractQuantitative analyses of variations in morphological features of charcoal were undertaken in a 210Pb-dated sediment core from Prosser Lake (British Columbia, Canada). Seven morphological types of charcoal were defined by particle shape, major–minor axis ratio, apparent porosity and progradation to unburned material. The distribution of morphotypes and total charcoal abundances were assessed as a proxy for fire events recorded between 1919 and 2000 and to subsequent mechanisms of transportation–sedimentation to lake sediments. Charcoal morphotypes showed distinct relationships to recorded area burned by fires. Fragile charcoal fragments with highly irregular porosity (termed Type M) displayed the strongest correlation to burned area (r2 = 0.51; P = 0.0001) and did not produce any false-positive signal for fires recorded within a radius of 20 km around the lake. We infer that high porosity and low density Type M fragments are aerially transported and directly deposited on the lake, and that the fragility of Type M charcoal prevents significant quantities from being secondarily transported and incorporated into the sedimentary record. We propose that charcoal morphology is an important but underutilized technique that can yield important insights into fire type, proximity and transportation–sedimentation processes.

scholarly journals SARS-CoV-2 serological tests can generate false positive results for samples from patients with chronic inflammatory diseases

2020 ◽  
Author(s):  
Nastya Kharlamova ◽  
Nicky Dunn ◽  
Sahl K Bedri ◽  
Svante Jerling ◽  
Malin Almgren ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
False Positive ◽  
Inflammatory Diseases ◽  
Serological Tests ◽  
Chronic Inflammatory Diseases ◽  
Negative Results ◽  
False Positive Signal ◽  
Lateral Flow Assays ◽  
Positive Results ◽  
Multiplex Bead

AbstractObjectivesPatients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless the tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays with samples from patients with chronic inflammatory diseases collected before April 2019, thus defined as negative.MethodsSamples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and RF +/- systemic lupus erythematosus (SLE, n=10), were tested with 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed multiplex bead-based assay.ResultsSix LFA and the in-house IgG assay gave the correct negative results for all samples. However, the majority of assays (n=13), gave false positive signal with samples from patients with RA and SLE. This was most notable in RF positive RA samples. MS samples did not give any false positive in any of the assays.ConclusionThe majority of the verified serological assays were sensitive to interfering antibodies in samples from patients with chronic inflammatory diseases and therefore may have poor specificity in this context. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

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