On-site test to detect syphilis in pregnancy: a systematic review of test accuracy studies.

BACKGROUND: Syphilis in pregnancy can lead to fetal and neonatal death or congenital anomalies. Accurate on-site tests are an essential part of effective prevention of mother-to-child transmission of the disease. OBJECTIVE: This systematic review assessed the accuracy of on-site tests to detect infection with Treponema pallidum in pregnant women. SEARCH STRATEGY: Major databases were searched from inception to January 2016 using terms: 'pregnancy', 'antenatal', 'syphilis', 'Treponema pallidum' with their variations, and the search limit for the relevant study design. SELECTION CRITERIA: We included studies that used dual reference standard (non-treponemal and treponemal tests) to detected syphilis in pregnancy. DATA COLLECTION AND ANALYSIS: Extracted accuracy data were tabulated and pooled using hierarchical, bivariate random effects model. MAIN RESULTS: Seven studies (combined sample 17 546) reporting the accuracy of four on-site tests met the eligibility criteria. On average, Determine™ and SD BioLine Syphilis 3.0 had the highest sensitivity of all the evaluated tests: 0.83 (95% CI 0.58, 0.98) and 0.86 (95% CI 0.82, 0.89), respectively, with a high specificity 0.96 (95% CI 0.89, 1.00) and 0.99 (95% CI 0.94, 1.00), respectively. The Qualitative Rapid Plasma Reagin card commonly used in clinical practice had a pooled sensitivity of 0.70 (95% CI 0.54, 0.88) and specificity of 0.97 (95% CI 0.96, 0.99). CONCLUSION: Immunochromatographic tests such as Determine™ and SD BioLine Syphilis 3.0 seem to be acceptable options in antenatal testing for syphilis, especially in resource-limited settings. Future research should seek more evidence to strengthen this claim. TWEETABLE ABSTRACT: On-site test to detect syphilis-options during antenatal care.

Safety assessment of sand casting explosion accidents by testing cavity pressure of the sand mold to protect employee health.

Excessive cavity pressure may result in a sand casting explosion, and corresponding measures should be adopted to prevent these consequences. In this study, the pressure variations in the cavity were first investigated based upon on-site testing by taking the resin contents into consideration, and then the evolution characteristics of sand casting explosion accidents were analyzed in depth by system dynamics, chaos theory, and the bow-tie model. When the resin contents are 1.3 wt%, 1.4 wt%, and 1.5 wt%, the pressures of the gas vent increase by 27.0 Pa, 32.8 Pa, and 35.6 Pa, respectively. To reduce the pressure of the cavity, the resin content should be reduced. The evolutionary process of sand casting explosion accidents has a noticeable butterfly effect and randomness, whose occurrence is comprehensively affected by human, object, environment, management and emergency subsystems. The leading causes of sand casting explosion accidents mainly include the extensive gas evolution characteristics of foundry sand, cavity exhaust blockage, and inadequate safety monitoring. The leading consequences of sand casting explosion accidents mainly include casualties, secondary disasters, and social panic. The implications of these findings concerning sand casting explosion accidents can be regarded as the foundation for accident prevention in practice.

Colorimetric aptasensor based on spherical nucleic acid-induced hybridization chain reaction for sensitive detection of exosomes.

Exosomes are one of the most promising biomarkers for tumor diagnosis and prognosis. Therefore, the development of convenient and sensitive exosome sensing strategies is of great significance. Herein, we integrated aptamer-based spherical nucleic acids (SNAs) and hybridization chain reaction (HCR) into a colorimetric aptasensor platform and applied it to the detection of exosomes. In this design, the CD63-specific aptamer pre-immobilized on the microplate was used to capture target exosomes, while the SNAs conjugated with nucleolin-specific aptamer and trigger probe H1 were designed for amplifying signal. In the presence of target exosomes, the SNAs can be attached to the microplate by the bridge effect of exosomes, resulting in the trigger of HCR. This process is accompanied by the formation of abundant G-quadruplex/hemin DNAzyme, enabling the visual quantitative analysis of exosomes. Featured with the dual amplification of SNAs and HCR, the proposed aptasensor achieved a considerable detection limit of 50 particles/µL. The practicability of this method was further verified by testing the different clinical samples. Given the ability of the aptasensor to visually detect exosomes in scenarios lacking instruments and resources, we believe that the aptasensor can be serve as a potential on-site test for liquid biopsy.

A Rapid Nucleic Acid Visualization Assay for Infectious Bovine Rhinotracheitis Virus That Targets the TK Gene.

Infectious bovine rhinotracheitis virus (IBRV) can cause various degrees of symptoms in the respiratory system, reproductive system, and whole body of cattle. It also can lead to persistent and latent infection in cattle, posing a challenge to timely control of infectious bovine rhinotracheitis (IBR) in farms and causing large financial losses in the global cattle industry. Therefore, the goal of this study was to establish a rapid, simple, and accurate method that can detect IBRV in order to facilitate the control and eradication of IBR in cattle. We combined recombinant polymerase amplification (RPA) with a closed vertical flow visualization strip (VF) and established an RPA-VF assay that targets the thymidine kinase (TK) gene to rapidly detect IBRV. This method (reaction at 42°C for 25 min) was able to detect a minimum of 3.8 × 101 copies/µL of positive plasmid and 1.09 × 101 50% tissue culture infective dose (TCID50) of the IBRV. This assay has high specificity for IBRV and does not cross-react with other respiratory pathogens in cattle. The concordance between the RPA-VF assay and the gold standard was 100%. In addition, this assay was also suitable for the detection of DNA from clinical samples extracted by a simple method (heating at 95°C for 5 min), which can achieve the rapid detection of clinical samples in the field. Overall, the present sensitivity, specificity, and clinical applicability assessments indicated that the RPA-VF assay we developed can be utilized as a quick and accurate on-site test for IBRV detection in farms. IMPORTANCE IBRV causes different degrees of clinical symptoms in cattle and poses a great threat to the cattle industry. The infection is persistent and latent, and the elimination of IBRV in infected herds is difficult. A rapid, simple, and accurate method to detect IBRV is therefore vital to control and eradicate IBR. Combining RPA with an VF, we established an RPA-VF assay for the rapid detection of IBRV, which can complete the test of clinical samples in 35 min. The assay shows good sensitivity, specificity, and clinical applicability and can be used as an on-site test for IBRV in farms.

Rapid Robot-Aided On-site Testing of Fume Cupboards.

Although containment testing of fume cupboards (FC) according to the standards EN 14175-3 (2019) or ANSI/ASHRAE 110 (2016) is well established for type testing, its application is currently much less accepted and practised for evaluating containment on-site. Few of the several million FC in the market have been tested at installation and commissioning, and even less undergo verification of containment during their service life in the laboratories. Several reasons have led to this unsafe situation. To address this challenge, a new concept has been developed to allow for rapid on-site testing of FC to gain knowledge as to the functional efficiency as well as to safety aspects for the operator. The concept consists of a movable robot-aided test equipment that can be installed quickly to the FC in running labs. Multiple sensors detect the tracer gas isopropanol. Within a test run of only 10-min data is collected to quantify containment at the sash opening and to determine purge efficiency. The method reveals impact from interfering effects such as draughts, air distribution, and movements and from equipment installed, and is a tool for the optimization of operating conditions of a lab. This article presents an advanced alternative to the existing containment tests, particularly for on-site testing. The method assesses not only proper operation of the FC in its environment, but also the suitability of a FC for a given use under aspects of health and safety evaluation.

All-in-one: Accurate quantification, on-site detection, and bioimaging of sulfite using a colorimetric and ratiometric fluorescent probe in vitro and in vivo.

SO2 and its derivatives (SO32-/HSO3-) are used widely in food, beverages, and pharmaceutical production. However, they could induce multiple diseases in respiratory, nervous, and cardiovascular systems. Although several fluorescent probes have been developed for detecting SO32-/HSO3-, reports on rapid fluorescent probes for the on-site detection of SO2 derivatives are scarce. Herein, a colorimetric and ratiometric fluorescent probe 1 based on the intramolecular charge transfer (ICT) was reported. Probe 1 resulted in a 122 nm blue-shift in fluorescent emission and decrement of absorbance at 500 nm upon the addition of sulfite. Therefore, probe 1 could quantify SO32-/HSO3- using both UV-Vis and fluorescent methods (LOD: UV-Vis method 34 nM; fluorescent method 51 nM). Importantly, probe 1 was used for a rapid (60 s) and convenient (1 step, on-site) measurement of the SO2 derivatives in real samples (LOD: 0.47 µM) using smartphone based on the colorimetric method. The SO32-/HSO3--sensing mechanism was confirmed as the Michael addition reaction. Furthermore, the probe was used for the real-time monitoring of SO32-/HSO3- in A549 cells and zebrafish. In summary, an all-in-one fluorescent probe was successfully developed for the accurate quantification, on-site detection, and bioimaging of SO32-/HSO3-.

"Aptamer-locker" DNA coupling with CRISPR/Cas12a-guided biosensing for high-efficiency melamine analysis.

Herein, we report a method that combined "aptamer-locker" DNA with CRISPR/Cas12a-based biosensing for sensitive and rapid melamine analysis. Three strategies were harnessed for designing the DNA sensors that were well characterized by circular dichroism (CD) spectroscopy and isothermal titration calorimetry (ITC) in the absence and presence of melamine. The detection parameters were optimized to achieve good analytic performance. As a result, a limit of detection (LOD) as low as 38 nM was achieved, which is below the threshold (1.0 mg/kg) of allowable melamine in infant milk products. In addition, the sensors show high selectivity for melamine against other analogues such as cyanuric acid, ammeline and ammelide. Moreover, our method was effective for rapid melamine analysis in whole milk samples, with or without sample pretreatment, in less than 20 min. Adopting a commercially available portable fluorimeter, on-site analysis of melamine in milk was accomplished. The strategies demonstrated here can expand to detect other non-nucleic-acid targets by simply replacing the aptamers.

A Rapid Colorimetric Assay for On-Site Authentication of Cephalopod Species.

A colorimetric assay, exploiting the combination of loop-mediated isothermal amplification (LAMP) with DNA barcoding, was developed to address the authentication of some cephalopod species, a relevant group in the context of seafood traceability, due to the intensive processing from the fishing sites to the shelf. The discriminating strategy relies on accurate design of species-specific LAMP primers within the conventional 5' end of the mitochondrial COI DNA barcode region and allows for the identification of Loligo vulgaris among two closely related and less valuable species. The assay, coupled to rapid genomic DNA extraction, is suitable for large-scale screenings and on-site applications due to its easy procedures, with fast (30 min) and visual readout.

Evaluation of an on-site test device for the heroin metabolite 6-acetylmorphine in urine.

Detection of heroin use is an important task in clinical drug testing and can be best performed by using 6-acetylmorphine as the target analyte. This study was performed to evaluate an on-site test for 6-acetylmorphine screening in urine with an assigned cut-off limit at 10 ng/mL. The reference method was a forensic accredited liquid chromatography-tandem mass spectrometry method. The study confirmed that negative controls and negative authentic specimen resulted in negative readings. Low cross-reactivity was recorded from other potential interfering opioids. Prepared standards and commercial calibrators demonstrated that the cutoff level of the test was lower than the assigned value and rather 2 ng/mL. A study using authentic specimens from patients on substitution treatment with methadone, morphine, and buprenorphine confirmed that the real cut-off level was 2 ng/mL. Using this value as cutoff limit the sensitivity and specificity of the test was 100%.

Screening methods for rapid determination of new psychoactive substances (NPS) in conventional and non-conventional biological matrices.

In the last years, a global awareness has arisen from the reported harmful effects and public health risks associated with the consumption of new psychoactive substances (NPSs). Improving efforts in the detection and identification of these substances have emerged as a global analytical challenge involving the large range of NPSs' chemical structures and the variety of conventional and non-conventional biological matrices. Indeed, detection capabilities and screening tools impact many fields and settings, including seized products analysis, workplace and roadside drug controls, emergency rooms, drug addiction treatment clinics, post-mortem and criminal caseworks, law enforcement and health interventions. Colorimetric, immunochemical and chromatographic-mass spectrometry techniques have been investigated and developed for the rapid identification of NPSs. Considering the continuous emergence of new substances, this review offers a panoramic view on the current status of analytical approaches for the rapid screening of NPSs, including, when available, data on conventional and non-conventional biological matrices. Although some of the presented methods are sound and promising, their applications are still limited, thus proving the importance of further investigations. New screening and sensitive targeted methods for NPS and their metabolites should be developed in different types of biological matrices, where concentration of substances and matrix effects can be significantly different.

Development of an immunochromatographic assay for the ß-adrenergic agonist feed additive zilpaterol.

Zilpaterol is a ß-adrenergic agonist feed additive approved in the United States to increase weight gain and improve feed efficiency of cattle. A zilpaterol immunochromatographic assay was developed as an economical and user-friendly rapid detection method for zilpaterol and validated using urine and tissue samples derived from animal studies. The assay sensitivity was 1.7-23.2 ng g-1 or mL-1 across a variety of feed and animal matrices and did not cross-react with clenbuterol or ractopamine. No sample pre-treatment of cattle and sheep urine was needed, but horse urine and feed required dilution; skeletal muscle required solvent extraction prior to testing. Of 32 incurred sheep urine samples tested, zilpaterol content was correctly identified in all but 2 samples. Horse urine containing >10 ng mL-1 of incurred zilpaterol residue (n = 48) was correctly identified as zilpaterol positive. The assay correctly identified 0-day withdrawal sheep muscle samples as zilpaterol positive and the control and longer withdrawal day sheep muscle samples as negative. Zilpaterol was demonstrated to be stable in horse urine when stored at -20°C for 7 years.