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 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.

Prevalence of porA pseudogene deletion among Neisseria gonorrhoeae isolates referred to the UK’s Gonococcal Resistance to Antimicrobials Surveillance Program

Sexual Health ◽  
2017 ◽  
Vol 14 (4) ◽  
pp. 392 ◽  
Author(s):  
Martina Toby ◽  
Pamela Saunders ◽  
Michelle Cole ◽  
Vlad Grigorjev ◽  
Sarah Alexander ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
False Negative ◽  
Public Health Problem ◽  
Surveillance Program ◽  
Major Public Health Problem ◽  
Negative Results ◽  
False Negative Results ◽  
Confirmatory Tests ◽  
Polymerase Chain ◽  
Low Prevalence

porA pseudogene-negative Neisseria gonorrhoeae isolates produce false-negative results when examined by polymerase chain reaction (PCR) with porA pseudogene targets. In the present study, 533 representative gonococcal isolates received in 2011 via the Gonococcal Resistance to Antimicrobials Surveillance Program were examined to determine the prevalence of porA-negative isolates. Less than 0.4% (2/533) of isolates were found to be reproducibly negative with the porA real-time PCR but were confirmed as N. gonorrhoeae with molecular, biochemical and immunological confirmatory tests. Sequencing revealed both isolates contained the Neisseria meningitidis porA gene. Low prevalence indicates that although these isolates do not present a major public health problem, microbiologists should remain vigilant.

Clinical utility of stimulation tests in infants with suspected adrenal insufficiency (AI)

2019 ◽  
Vol 32 (5) ◽  
pp. 529-531
Author(s):  
Preneet Cheema Brar
Keyword(s):  
Adrenal Insufficiency ◽  
Clinical Utility ◽  
Plasma Concentrations ◽  
False Negative ◽  
Relative Adrenal Insufficiency ◽  
Term Infants ◽  
Negative Results ◽  
False Negative Results ◽  
Confirmatory Tests ◽  
Stimulation Tests

Abstract Diagnosis of adrenal insufficiency (AI) in infants can be difficult. While a low random cortisol can signal AI, often confirmatory tests are required when clinical suspicion is strong but the cortisol levels are equivocal. Several studies have demonstrated that in sick preterm infants, there is relative adrenal insufficiency (RAI) defined as an inadequate cortisol production relative to the degree of stress or illness, a condition which can last for several weeks, while in term infants the adrenal axis is mature at birth (Bagnoli F, Mori A, Fommei C, Coriolani G, Badii S, et al. ACTH and cortisol cord plasma concentrations in preterm and term infants. J Perinatol 2013;33:520–4). Adrenocorticotrophic hormone (ACTH) and corticotrophin releasing hormone (CRH) stimulation tests have been validated in infants in several studies. In light of recent reports of false-negative results of stimulation tests, it is imperative to highlight the pitfalls of these tests. The purpose of this communication is to bring attention to the accuracy of timing of these tests in infants.

Driving Impairment Cases Involving Etizolam and Flubromazolam

2020 ◽  
Author(s):  
Timothy P Rohrig ◽  
Kei A Osawa ◽  
Tyson R Baird ◽  
Kimberly B Youso
Keyword(s):  
False Negative ◽  
Pharmacological Effects ◽  
Psychoactive Substances ◽  
Blood Concentrations ◽  
Routine Testing ◽  
Negative Results ◽  
Driving Impairment ◽  
Low Concentrations ◽  
False Negative Results ◽  
The Mean

Abstract This study describes 12 cases of drivers stopped for impaired driving, where a designer benzodiazepine was detected, specifically etizolam or flubromazolam. Etizolam was detected in three cases, with blood concentrations ranging from 40 to 330 ng/mL. Two of these cases had low concentrations of methamphetamine and/or amphetamine, and in the third case tetrahydrocannabinol (THC) was detected. Flubromazolam was detected in nine cases; in all cases, at least one other drug was detected, with THC being the most prevalent. The mean blood concentration of flubromazolam was 16.3 ng/mL and had a median concentration of 17.0 ng/mL, ranging from 7.0 to 31 ng/mL. The low concentrations of designer benzodiazepines that produce pharmacological effects may allow many of these drugs to go undetected using routine testing in laboratories; therefore, it is necessary to include these novel compounds within validated analytical methods to reduce the chance of reporting false negative results. The prevalence in which laboratories are detecting the presence of novel benzodiazepines in impaired drivers illustrates the increased threat to public safety. These case studies demonstrate the importance of investigating agencies and forensic laboratories to be vigilant in monitoring the emerging novel psychoactive substances in their region.

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.

Detection of Streptococcus pneumoniae in Sputum Samples by Real- Time PCR.

2020 ◽  
Vol 18 ◽  
Author(s):  
Pegah Shakib ◽  
Mohammad Reza Zolfaghari
Keyword(s):  
Streptococcus Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
False Negative ◽  
Cross Sectional Study ◽  
Laboratory Culture ◽  
Cross Sectional ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Method

Background: Conventional laboratory culture-based methods for diagnosis of Streptococcus pneumoniae are time-consuming and yield false negative results. Molecular methods including real-time (RT)-PCR rapid methods and conventional PCR due to higher sensitivity and accuracy have been replaced instead traditional culture assay. The aim of the current study was to evaluate lytA gene for detection of Streptococcus pneumoniae in the cerebrospinal fluid of human patients with meningitis using real-time PCR assay. Material and Methods: In this cross-sectional study, a total of 30 clinical specimens were collected from patients in a period from September to December 2018. In order to evaluate the presence of lytA gene, conventional and real-time PCR methods were used without culture. Results: From 30 sputum samples five (16.66%) isolates were identified as S. pneumoniae by lytA PCR and sequencing. Discussion: In this research, an accurate and rapid real-time PCR method was used, which is based on lytA gene for diagnosis of bacteria so that it can be diagnosed. Based on the sequencing results, the sensitivity for detection of lytA gene was 100% (5/5).

COVID-19: how nuclear medicine can provide a differential diagnosis in very dubious case

Coronaviruses ◽  
2020 ◽  
Vol 01 ◽  
Author(s):  
Maria Silvia De Feo ◽  
Viviana Frantellizzi ◽  
Giuseppe De Vincentis
Keyword(s):  
Infectious Disease ◽  
Differential Diagnosis ◽  
Ct Scan ◽  
Imaging Technique ◽  
False Negative ◽  
Clinical Signs ◽  
Negative Results ◽  
Infectious Disease Department ◽  
False Negative Results ◽  
99Mtc Hmpao

Background: We present the case of a 55-year-old woman, admitted to the Infectious Disease Department of Policlinico Umberto I, Rome, in mid-March 2020, with suspicion of COVID-19 infection. Objective: The rRT-PCR was negative and the following CT scan, performed to exclude false-negative results and help diagnosis, was inconclusive. Methods: It was decided to submit the patient to 99mTc-HMPAO-labelled leukocyte scan. Results: This exam led to the diagnosis of infective endocarditis. Conclusion: In the present pandemic scenario, 99mTc-HMPAO-labelled leukocyte scan represents a reliable imaging technique for differential diagnosis with COVID-19 in patients with confusing clinical signs, possible false-negative rRT-PCR results and inconclusive CT scan.

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