scholarly journals Lateral Flow Immunochromatography Assay for Detection of Furosemide in Slimming Health Foods

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2041
Author(s):  
Yingying Li ◽  
Haihuan Xie ◽  
Jin Wang ◽  
Xiangmei Li ◽  
Zhili Xiao ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Limit Of Detection ◽  
False Negative ◽  
Sample Pretreatment ◽  
Lateral Flow ◽  
Initial Screening ◽  
Negative Results ◽  
False Negative Results ◽  
High Consistency ◽  
First Time

In recent years, furosemide has been found to be abused in slimming health foods. There is an urgent need for a simpler, faster method for detecting furosemide in slimming health foods. In this study, a rapid, convenient and sensitive lateral flow immunochromatography (LFIA) based on Au nanoparticles (AuNPs) was established for the first time. Under optimal conditions, the qualitative limit of detection (LOD) of the AuNPs-based LFIA was 1.0~1.2 μg/g in slimming health foods with different substrates. AuNPs-LFIA could specifically detect furosemide within 12 min (including sample pretreatment) and be read by the naked eye. The developed AuNPs-LFIA showed high consistency with liquid chromatography with tandem mass spectrometry (LC-MS/MS), and no false positive or false negative results were found in spiked slimming health foods, proving that the AuNPs-LFIA should be accurate and reliable. The AuNPs-LFIA reported here provides a serviceable analytical tool for the on-site detection and rapid initial screening of furosemide for the first time.

scholarly journals Distribution of SARS-CoV-2 PCR Cycle Threshold Values Provide Practical Insight Into Overall and Target-Specific Sensitivity Among Symptomatic Patients

2020 ◽  
Vol 154 (4) ◽  
pp. 479-485 ◽  
Author(s):  
Blake W Buchan ◽  
Jessica S Hoff ◽  
Cameron G Gmehlin ◽  
Adriana Perez ◽  
Matthew L Faron ◽  
...  
Keyword(s):  
Viral Load ◽  
Limit Of Detection ◽  
False Negative ◽  
Age Group ◽  
Rt Pcr ◽  
Patient Age ◽  
Cycle Threshold ◽  
Negative Results ◽  
Patient Âgé ◽  
False Negative Results

Abstract Objectives We examined the distribution of reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (CT) values obtained from symptomatic patients being evaluated for coronavirus disease 2019 (COVID-19) to determine the proportion of specimens containing a viral load near the assay limit of detection (LoD) to gain practical insight to the risk of false-negative results. We also examined the relationship between CT value and patient age to determine any age-dependent difference in viral load or test sensitivity. Methods We collected CT values obtained from the cobas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay corresponding to 1,213 combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals that were reported as positive or presumptive positive for SARS-CoV-2. CT values were stratified by SARS-CoV target and patient age group. Results In total, 93.3% to 98.4% of specimens demonstrated CT values greater than 3× the assay LoD, at which point false-negative results would not be expected. The mean of CT values between age groups was statistically equivalent with the exception of patients in age group 80 to 89 years, which demonstrated slightly lower CTs. Conclusions Based on the distribution of observed CT values, including the small proportion of specimens with values near the assay LoD, there is a low risk of false-negative RT-PCR results in combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals.

scholarly journals Validation of Two Commercial Lateral Flow Devices for the Detection of Peanut Proteins in Cookies: Interlaboratory Study

2006 ◽  
Vol 89 (2) ◽  
pp. 462-468 ◽  
Author(s):  
Arjon J van Hengel ◽  
Claudia Capelletti ◽  
Marcel Brohee ◽  
Elke Anklam ◽  
M-C S Baumgartner ◽  
...  
Keyword(s):  
False Negative ◽  
Lateral Flow ◽  
Food Matrix ◽  
Negative Results ◽  
False Negative Results ◽  
Test Kit ◽  
Interlaboratory Validation ◽  
Peanut Proteins ◽  
Flow Devices ◽  
Positive Results

Abstract Results are reported for an interlaboratory validation study of 2 commercially available lateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 030 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide, which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing <21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

scholarly journals Recurrent SARS-CoV-2 Infection: Case Reports and Review of the Literature

2021 ◽  
Vol 2 (2) ◽  
pp. 1-4
Author(s):  
Brian Conway ◽  
Keyword(s):  
Limit Of Detection ◽  
Case Reports ◽  
False Negative ◽  
Recurrent Infection ◽  
Family Unit ◽  
Her Family ◽  
Negative Results ◽  
False Negative Results ◽  
Clinical Syndromes ◽  
Relapsing Remitting

We describe a 37-year-old woman who became infected with SARS-CoV-2. Over time, 4 other members in her family unit became infected, with 3/5 developing 2-3 separate clinical syndromes over two months. It is possible that each person had a single prolonged infection, with the literature reporting RNA detection for as long as 83 days in some cases. Syndromes of relapsing/remitting infection have also been well described. Intermittent negative RNA readings may represent “false negative” results with intermittent levels of viremia that occasionally fall below the limit of detection of the assay. An alternative explanation may be multiple episodes of infection, clearance, and re-infection within the family unit. Preliminary reports in the literature suggest onward transmission after recurrent infection in 3 reported cases. An understanding of the prevalence of cases series such as ours and their pathophysiologic and immunologic significance will improve our knowledge about SARS-CoV-2 infection and strategies to control it.

scholarly journals Importance of Adequate qPCR Controls in Infection Control

Diagnostics ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2373
Author(s):  
Matthew Oughton ◽  
Ivan Brukner ◽  
Shaun Eintracht ◽  
Andreas I. Papadakis ◽  
Alan Spatz ◽  
...  
Keyword(s):  
Infection Control ◽  
False Negative ◽  
Significant Proportion ◽  
Control Measures ◽  
Negative Results ◽  
Minimal Sample ◽  
Infection Control Measures ◽  
False Negative Results ◽  
Quantitative Sample ◽  
First Time

Respiratory screening assays lacking Sample Adequacy Controls (SAC) may result in inadequate sample quality and thus false negative results. The non-adequate samples might represent a significant proportion of the total performed tests, thus resulting in sub-optimal infection control measures with implications that may be critical during pandemic times. The quantitative sample adequacy threshold can be established empirically, measuring the change in the frequency of positive results, as a function of the numerical value of “sample adequacy”. Establishing a quantitative threshold for SAC requires a big number/volume of tests to be analyzed in order to have a statistically valid result. Herein, we are offering for the first time clear clinical evidence that a subset of results, which did not pass minimal sample adequacy criteria, have a significantly lower frequency of positivity compared with the “adequate” samples. Flagging these results and/or re-sampling them is a mitigation strategy, which can dramatically improve infection control measures.

scholarly journals High-Throughput Nucleotide Resolution Predictions of Assay Limitations Increase the Reliability and Concordance of Clinical Tests

2021 ◽  
pp. 1085-1095
Author(s):  
Jonathan Bieler ◽  
Christian Pozzorini ◽  
Jessica Garcia ◽  
Alex C. Tuck ◽  
Morgane Macheret ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
False Negative ◽  
Variant Calling ◽  
Biophysical Model ◽  
Sequencing Error ◽  
Genomic Context ◽  
Negative Results ◽  
False Negative Results ◽  
Estimate Reliability ◽  
Nucleotide Resolution

PURPOSE The ability of next-generation sequencing (NGS) assays to interrogate thousands of genomic loci has revolutionized genetic testing. However, translation to the clinic is impeded by false-negative results that pose a risk to patients. In response, regulatory bodies are calling for reliability measures to be reported alongside NGS results. Existing methods to estimate reliability do not account for sample- and position-specific variability, which can be significant. Here, we report an approach that computes reliability metrics for every genomic position and sample interrogated by an NGS assay. METHODS Our approach predicts the limit of detection (LOD), the lowest reliably detectable variant fraction, by taking technical factors into account. We initially explored how LOD is affected by input material amount, library conversion rate, sequencing coverage, and sequencing error rate. This revealed that LOD depends heavily on genomic context and sample properties. Using these insights, we developed a computational approach to predict LOD on the basis of a biophysical model of the NGS workflow. We focused on targeted assays for cell-free DNA, but, in principle, this approach applies to any NGS assay. RESULTS We validated our approach by showing that it accurately predicts LOD and distinguishes reliable from unreliable results when screening 580 lung cancer samples for actionable mutations. Compared with a standard variant calling workflow, our approach avoided most false negatives and improved interassay concordance from 94% to 99%. CONCLUSION Our approach, which we name LAVA (LOD-aware variant analysis), reports the LOD for every position and sample interrogated by an NGS assay. This enables reliable results to be identified and improves the transparency and safety of genetic tests.

scholarly journals Detection of a Giardia lamblia coproantigen by using a commercially available immunoenzymatic assay, in Belo Horizonte, Brazil

1999 ◽  
Vol 41 (3) ◽  
pp. 151-154 ◽  
Author(s):  
Míriam Oliveira e ROCHA ◽  
Rômulo Teixeira de MELLO ◽  
Tânia Mara Pinto Dabés GUIMARÃES ◽  
Vicente de Paulo Coelho Peixoto de TOLEDO ◽  
Maria da Conceição Carneiro Gonçalves MOREIRA ◽  
...  
Keyword(s):  
Giardia Lamblia ◽  
Intestinal Parasites ◽  
False Negative ◽  
Good Alternative ◽  
Fecal Examination ◽  
Negative Results ◽  
False Negative Results ◽  
Belo Horizonte ◽  
First Time ◽  
Immunoenzymatic Assay

It is known that fecal examination to detect Giardia lamblia cysts or trophozoites produces a high percentage of false-negative results. A commercially available immunoenzymatic assay (ProSpecT Giardia Microplate Assay, Alexon, Inc., BIOBRÁS) to detect G. lamblia specific coproantigen was evaluated for the first time in Brazil. A total of 90 specimens were tested. Each specimen was first tested as unpreserved stool, and then it was preserved in 10% Formalin to be tested 2 months later. The assay was able to identify all the 30 positive patients (sensitivity = 100.0%) by visual or spectrophotometric examination in the unpreserved specimens and was negative in 57 of the 60 patients without G. lamblia (specificity = 95.0%). The assay identified 27 of the 30 positive patients (sensitivity = 90.0%) and was negative in 59 of the 60 negatives (specificity = 98.3%) in the preserved stools according to both readings. A marked difference was observed in the optical densities in both groups, preserved and unpreserved stools, when the G. lamblia-positive specimens were compared to the negative or positive for other intestinal parasites than G. lamblia. The assay seems a good alternative for giardiasis diagnosis, especially when the fecal examination was repeatedly negative and the patient presents giardiasislike symptoms.

scholarly journals Genotype classification and fluorescence visual identification of the Rhizoma Paridis of Paris polyphylla var. yunnanensis based on the SNPs of ITS sequence 

2020 ◽  
Author(s):  
Chi Gao ◽  
Kaiyuan Zhang ◽  
Qinghe Wang ◽  
Ling Zhao ◽  
Rong Chen ◽  
...  
Keyword(s):  
Internal Transcribed Spacer ◽  
False Negative ◽  
Identification System ◽  
Accurate Identification ◽  
Negative Results ◽  
Visual Identification ◽  
False Negative Results ◽  
Paris Polyphylla ◽  
Green Fluorescent ◽  
First Time

Abstract A fluorescent visual identification system of Paris polyphylla var. yunnanensis was established based on internal transcribed spacer barcoding. It is proposed for the first time that P. polyphylla var. yunnanensis should be divided into two types of genotypes: YN-I and YN-II according to single nucleotide polymorphism of internal transcribed spacer. In order to avoid false-negative results, two pairs of specific primers for YN-I and YN-II were designed, respectively, and specific visual fluorescent identification systems was established by SYBR Green I fluorescent dye was directly introduced into the PCR system which can be observed directly with the naked eye for the green fluorescent color of PCR system. Therefrom, it has realized the rapid and directly visual identification of two genotypes of P. polyphylla var. yunnanensis from its common nine adulterants. This study proposed for the first time the existence of different genotypes on the legal basis of Rhizoma Paridis, and provided a model for the accurate identification of different genotypes.

Detection of microsatellite instability in a panel of solid tumours with the Idylla MSI Test using extracted DNA

2020 ◽  
Vol 74 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Adrien Pécriaux ◽  
Loetitia Favre ◽  
Julien Calderaro ◽  
Cécile Charpy ◽  
Jonathan Derman ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
False Negative ◽  
Solid Tumours ◽  
Automated System ◽  
Ovarian Carcinomas ◽  
Negative Results ◽  
False Negative Results ◽  
Large Panel ◽  
Msi Analysis

AimDuring the last few years, determination of microstatellite instability (MSI) status has become a routine part of clinical practice, essentially to detect Lynch syndrome. Recently, MSI testing has increased with the development of immunotherapy and has expanded to a large panel of solid tumours. The aim of our work was to evaluate a fully automated system developed by Biocartis, the Idylla MSI Test, which performs an MSI analysis within 150 min.MethodsA comparison between pentaplex PCR, immunohistochemistry and Idylla MSI Test was performed in 53 colorectal carcinoma samples, 7 small intestine adenocarcinomas, 15 duodenal and pancreatic adenocarcinomas, 16 gastric tumours, 15 endometrial adenocarcinomas, 5 ovarian carcinomas and 4 cases of urinary tract tumours using extracted DNA. Limit-of-detection (LOD) experiment was also done using a commercial DNA known to harbour MSI phenotype.ResultsThe overall sensitivity was 94% and the overall specificity was 100%. Two invalid and three false-negative results were observed. Our experiments showed that the amount of DNA loaded into the cartridge was decisive and should be superior to 25 ng. LOD comprised between 4% and 8%.ConclusionOverall, we have demonstrated that the Idylla MSI Test is a rapid and valid option to detect MSI phenotype which can be used in a large panel of solid tumours.

Genotype Classification and Fluorescence Visual Identification of the Rhizoma Paridis of Paris Polyphylla Var. Yunnanensis based on the SNPs of ITS Sequence

2020 ◽  
Author(s):  
Chi Gao ◽  
Kaiyuan Zhang ◽  
Qinghe Wang ◽  
Ling Zhao ◽  
Rong Chen ◽  
...  
Keyword(s):  
Internal Transcribed Spacer ◽  
False Negative ◽  
Identification System ◽  
Accurate Identification ◽  
Negative Results ◽  
Visual Identification ◽  
False Negative Results ◽  
Paris Polyphylla ◽  
Green Fluorescent ◽  
First Time

Abstract A fluorescent visual identification system of Paris polyphylla var. yunnanensis was established based on internal transcribed spacer barcoding. It is proposed for the first time that P. polyphylla var. yunnanensis should be divided into two types of genotypes: YN-I and YN-II according to single nucleotide polymorphism of internal transcribed spacer. In order to avoid false-negative results, two pairs of specific primers for YN-I and YN-II were designed, respectively, and specific visual fluorescent identification systems was established by SYBR Green I fluorescent dye was directly introduced into the PCR system which can be observed directly with the naked eye for the green fluorescent color of PCR system. Therefrom, it has realized the rapid and directly visual identification of two genotypes of P. polyphylla var. yunnanensis from its common nine adulterants. This study proposed for the first time the existence of different genotypes on the legal basis of Rhizoma Paridis, and provided a model for the accurate identification of different genotypes.

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