scholarly journals IUPAC Collaborative Trial Study of a Method To Detect Genetically Modified Soy Beans and Maize in Dried Powder

1999 ◽  
Vol 82 (4) ◽  
pp. 923-928 ◽  
Author(s):  
Markus Lipp ◽  
Peter Brodmann ◽  
Klaus Pietsch ◽  
Jean Pauwels ◽  
Elke Anklam ◽  
...  
Keyword(s):  
Genetically Modified Organisms ◽  
Genetically Modified ◽  
False Negative ◽  
35S Promoter ◽  
Lower Sensitivity ◽  
Correct Identification ◽  
Collaborative Trial ◽  
Negative Results ◽  
False Negative Results ◽  
Nos Terminator

Abstract This paper presents results of a collaborative trial study (IUPAC project No. 650/93/97) involving 29 laboratories in 13 countries applying a method for detecting genetically modified organisms (GMOs) in food. The method is based on using the polymerase chain reaction to determine the 35S promoter and the NOS terminator for detection of GMOs. Reference materials were produced that were derived from genetically modified soy beans and maize. Correct identification of samples containing 2% GMOs is achievable for both soy beans and maize. For samples containing 0.5% genetically modified soy beans, analysis of the 35S promoter resulted also in a 100% correct classification. However, 3 false-negative results (out of 105 samples analyzed) were reported for analysis of the NOS terminator, which is due to the lower sensitivity of this method. Because of the bigger genomic DNA of maize, the probability of encountering false-negative results for samples containing 0.5% GMOs is greater for maize than for soy beans. For blank samples (0% GMO), only 2 false-positive results for soy beans and one for maize were reported. These results appeared as very weak signals and were most probably due to contamination of laboratory equipment.

scholarly journals Detection of Genetically Modified Organisms in Foods by Protein- and DNA-Based Techniques: Bridging the Methods

2002 ◽  
Vol 85 (3) ◽  
pp. 787-791 ◽  
Author(s):  
Gert van Duijn ◽  
Ria van Biert ◽  
Henriette Bleeker-Marcelis ◽  
Ineke van Boeijen ◽  
Abdi Jama Adan ◽  
...  
Keyword(s):  
Genetically Modified Organisms ◽  
Matrix Effects ◽  
Polyclonal Antibodies ◽  
Genetically Modified ◽  
False Negative ◽  
Detection Methods ◽  
Vegetable Crops ◽  
Food Ingredients ◽  
Negative Results ◽  
Maize Varieties

Abstract According to European Commission (EC) Regulation 1139/98, foods and food ingredients that are to be delivered to the final consumer in which either protein or DNA resulting from genetic modification is present, shall be subject to additional specific labeling requirements. Since 1994, genetically altered tomatoes, squash, potatoes, canola, cotton, and soy have been on the market. Recently, insect-resistant and herbicide-tolerant maize varieties have been introduced. Soy and maize are 2 of the most important vegetable crops in the world. During the past 4 years, both protein- and DNA-based methods have been developed and applied for detection of transgenic soy and maize, and their derivatives. For protein-based detection, specific monoclonal and polyclonal antibodies have been developed; for immunochemical detection, Western blot analysis and enzyme-linked immunosorbent assays are the most prominent examples. For detection of genetically modified organisms (GMOs) at the level of DNA, polymerase chain reaction-based methods are mainly used. For these reactions, highly specific primer sets are needed. This study compares the principally different methods. Specificity of methods and the possible risks of false-positive or false-negative results are considered in relation to sampling, matrix effects, and food processing procedures. In addition, quantitative aspects of protein- and DNA-based GM detection methods are presented and discussed. This is especially relevant as EC regulation 49/2000, which defines a threshold for an unintentional comingling of 1%, came into force on April 10, 2000.

scholarly journals Rapid diagnostics of orthopedic implant-associated infections using Unyvero ITI implant and tissue infection application is not optimal for Staphylococcus species identification

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Hege Vangstein Aamot ◽  
Bjørn Odd Johnsen ◽  
Inge Skråmm
Keyword(s):  
Antibiotic Resistance ◽  
Antibiotic Treatment ◽  
False Negative ◽  
Treatment Recommendation ◽  
Lower Sensitivity ◽  
Orthopedic Implant ◽  
Rapid Diagnostics ◽  
Negative Results ◽  
False Negative Results ◽  
Time To Detection

Abstract Objectives This pilot study aimed to compare the commercial Unyvero ITI multiplex PCR application (U-ITI, Curetis GmbH) with conventional culturing concerning (a) detection of pathogens, (b) time to detection of pathogens and (c) time to and quality of antibiotic treatment recommendation in diagnostics of orthopedic implant-associated infections (OIAI). Results 72 tissue biopsies from 15 consecutive patients with deep OIAI infections were analyzed with conventional culturing including phenotypic antibiotic susceptibility testing and the U-ITI. U-ITI showed lower sensitivity than conventional culturing concerning detection of pathogens (73% vs 93%). 4/15 patients would have been given false negative results by U-ITI, all of which were culture-positive for Staphylococcus species. Median time to detection of pathogens was 47 h and antibiotic resistance 89 h by conventional methods compared to 13.5 h with the U-ITI. The U-ITI did not detect antibiotic resistance, whereas conventional culturing showed resistance to antibiotics covered by the U-ITI panel in 2 patients. Time to detection of pathogens was improved, but the detection limit for staphylococci was unsatisfactory. Although the time to antibiotic treatment recommendation was significantly reduced, the U-ITI would have resulted in incorrect antibiotic recommendation in 2 patients. Our data do not support use of this assay in diagnostics.

scholarly journals Performance of SARS-CoV-2 antigen testing in symptomatic and asymptomatic adults: a single-center evaluation

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Stephanie L. Mitchell ◽  
Steven Orris ◽  
Tanner Freeman ◽  
Megan C. Freeman ◽  
Michelle Adam ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Point Of Care ◽  
False Negative ◽  
Poor Performance ◽  
Nasopharyngeal Swab ◽  
Lower Sensitivity ◽  
Negative Results ◽  
Asymptomatic Patients ◽  
False Negative Results ◽  
Antigen Testing

Abstract Background Antigen testing offers rapid and inexpensive testing for SARS-CoV-2 but concerns regarding performance, especially sensitivity, remain. Limited data exists for use of antigen testing in asymptomatic patients; thus, performance and reliability of antigen testing remains unclear. Methods 148 symptomatic and 144 asymptomatic adults were included. A nasal swab was collected for testing by Quidel Sofia SARS IFA (Sofia) as point of care. A nasopharyngeal swab was also collected and transported to the laboratory for testing by Cepheid Xpert Xpress SARS-CoV-2/Flu/RSV RT-PCR (Cepheid). Results Overall, Sofia had good agreement with Cepheid (> 95%) in adults, however was less sensitive. Sofia had a sensitivity of 87.8% and 33.3% for symptomatic and asymptomatic patients, respectively. Among symptomatic patients, testing > 5 days post symptom onset resulted in lower sensitivity (82%) when compared with testing within 5 days of symptom onset (90%). Of the four Sofia false-negative results in the asymptomatic cohort, 50% went on to develop COVID-19 disease within 5 days of testing. Specificity in both symptomatic and asymptomatic cohorts was 100%. Conclusions Sofia has acceptable performance in symptomatic adults when tested < 5 days of symptom onset. Caution should be taken when testing patients with ≥ 5 days of symptoms. The combination of low prevalence and reduced sensitivity results in relatively poor performance of in asymptomatic patients. NAAT-based diagnostic assays should be considered in when antigen testing is unreliable, particularly in symptomatic patients with > 5 days of symptom onset and asymptomatic patients.

scholarly journals Analytical Challenges for Identification of New Psychoactive Substances: A Literature-Based Study for Seized Drugs

2021 ◽  
Author(s):  
Aline Bruni ◽  
Caio Rodrigues ◽  
Christiano dos Santos ◽  
Jade de Castro ◽  
Livia Mariotto ◽  
...  
Keyword(s):  
Law Enforcement ◽  
False Negative ◽  
Synthetic Cannabinoids ◽  
Confirmatory Test ◽  
New Psychoactive Substances ◽  
Correct Identification ◽  
Psychoactive Substances ◽  
Negative Results ◽  
False Negative Results ◽  
Confirmatory Tests

Correct identification of substances is essential to understand drug use and trafficking trends and guide measures for harm reduction and treatment. Two steps are needed to verify the nature of a substance properly: a presumptive test and a confirmatory test. There are presumptive tests which presents deficiencies, such as providing false-positive and false-negative results. Confirmatory tests are more reliable, but they are more expensive. With the appearance of New Psychoactive Substances (NPS), identifying and characterizing illicit substances has become more challenging. This paper focuses on presenting information about NPS characteristics and analysis. For this purpose, we have reviewed the literature to address the main aspects of five groups of NPS: amphetamine-type stimulants, synthetic cannabinoids, N-methoxybenzyl-methoxyphenylethylamine (NBOMe), synthetic opioids, and benzodiazepines. We present the main characteristics of each group and certain aspects of presumptive and confirmatory tests regarding these groups. Our findings show obstacles in developing methodologies that can correctly identify these substances, and problems can increase as new structures appear. This information can be helpful to drive research into identifying NPS and inform law enforcement and law practitioners about the main characteristics of each group and the main questions involving their identification.

scholarly journals PCR Primer Specific CaMV 35S Promoter to Detect Transgenic Soybean in Indonesia Commercial Soy Bean and Tempeh

2017 ◽  
Vol 17 (3) ◽  
pp. 415 ◽  
Author(s):  
Tri Joko Raharjo ◽  
Surajiman Surajiman
Keyword(s):  
False Negative ◽  
Pcr Amplification ◽  
Camv 35S Promoter ◽  
35S Promoter ◽  
Good Precision ◽  
Transgenic Soybean ◽  
Camv 35S ◽  
Negative Results ◽  
False Negative Results ◽  
Total Dna

In the framework of the supervision and enforcement of the regulation regarding the content of soybean transgenic in food and processed foods such as tempeh, a reliable testing method is indispensable. Performance specific primer PCR amplification with promoter of CaMV 35S tested to detect the presence of GMOs. The parameters tested were specificity, precision and cut off detection using CRM transgenic soybean. The method is reliable to detect transgenic soybean specifically and has the annealing temperature at 59 °C during the 30 cycle standard PCR condition. The method did not show any false positive and false negative results meaning good precision. The cut off the methods is up to 2 copies total DNA of soybean or less than 104 copies of the CaMV 35S promoter. Observation to the commercial soybeans and tempeh found that most of the commercially available soybean in Indonesia are transgenic (8 of 10 sample) while all tested tempeh sample were detected have been fermented from transgenic soybeans.

Patients with chronic pain on opioid therapy taking dronabinol: Incidence of false negatives using radioimmunoassay

2018 ◽  
Vol 4 (1) ◽  
pp. 21 ◽  
Author(s):  
Sanjeet Narang, MD ◽  
Ajay D. Wasan, MD, MSc ◽  
Edgar L. Ross, MD ◽  
Edward Michna, MD ◽  
Jui-Yuan Chen, MD ◽  
...  
Keyword(s):  
False Negative ◽  
Study Drug ◽  
Serum Levels ◽  
Opioid Therapy ◽  
Lower Sensitivity ◽  
Lower Serum ◽  
Double Blind ◽  
Blood Samples ◽  
Negative Results ◽  
False Negative Results

Background: Serum blood toxicology screens are believed to be important to monitor compliance and to identify levels of illicit substances in patients taking opioids for their chronic pain.Methods: In this study, the authors examine the incidence of tetrahydrocannabinol (THC) in consecutive blood samples of patients given dronabinol. We assessed the incidence of THC in 27 patients who participated in a single-dose, double-blind crossover trial of dronabinol (Marinol® capsules), a synthetic Δ9-THC, as part of a larger study, to determine the reliability of the toxicology screening. Subjects were randomly administered 10 mg or 20 mg of dronabinol or placebo over the course of three 8-hour visits for a combined 228 serum blood samples. Levels of THC were quantified using radioimmunoassay.Results: The majority of the samples (57.4 percent) showed presence of study drug as expected. However, 43 samples (42.6 percent) showed no detectable evidence of THC 4 and 8 hours after administration of dronabinol. Five subjects showed lower serum levels on the higher dose (20 mg) than on the lower dose (10 mg) after 4 hours, and two subjects showed lower levels with the higher dose after 8 hours. One subject had no detectable THC on any dose of dronabinol.Conclusions: These toxicology reports point to higher than anticipated false-negative results with radioimmunoassay blood serum screening. Results could be explained by the lower sensitivity of this screening technique and also in how oral cannabinoids are metabolized. Further investigations are needed on the accuracy of the detection of THC among patients known to have used dronabinol.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Scoring System for the Diagnosis of COVID-19

2020 ◽  
Vol 13 (1) ◽  
pp. 413-414 ◽  
Author(s):  
Mohamed Farouk Allam
Keyword(s):  
Scoring System ◽  
Clinical Symptoms ◽  
False Negative ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Negative Results ◽  
False Negative Results ◽  
Symptoms And Signs

Due to the international spread of COVID-19, the difficulty of collecting nasopharyngeal swab specimen from all suspected patients, the costs of RT-PCR and CT, and the false negative results of RT-PCR assay in 41% of COVID-19 patients, a scoring system is needed to classify the suspected patients in order to determine the need for follow-up, home isolation, quarantine or the conduction of further investigations. A scoring system is proposed as a diagnostic tool for suspected patients. It includes Epidemiological Evidence of Exposure, Clinical Symptoms and Signs, and Investigations (if available). This scoring system is simple, could be calculated in a few minutes, and incorporates the main possible data/findings of any patient.

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