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Micromachines Feb 2022Lymphatic filariasis (LF) is a leading cause of permanent disability worldwide that has been listed as a neglected tropical disease by the World Health Organization....
Lymphatic filariasis (LF) is a leading cause of permanent disability worldwide that has been listed as a neglected tropical disease by the World Health Organization. Significant progress made by the Global Program to Eliminate Lymphatic Filariasis (GPELF) has led to a substantial decline in the population of the worm that causes LF infection. Diagnostic assays capable of detecting low levels of parasite presence are needed to diagnose LF. There is also a need for new tools that can be used in areas where multiple filarial species are coendemic and for mass screening or for use in a point-of-care setting. In the present study, we applied our previously developed semi-automated microfluidic device in combination with our recently developed mini polymerase chain reaction (miniPCR) with a duplex lateral flow dipstick (DLFD) (miniPCR-DLFD) for rapid mass screening and visual species identification of lymphatic filariae in human blood. The study samples comprised 20 microfilariae (mf) positive human blood samples, 14 mf positive human blood samples and 100 mf negative human blood samples. Microfilariae detection and visual species identification was performed using the microfluidic device. To identify the species of the mf trapped in the microfluidic chips, DNA of the trapped mf was extracted for miniPCR amplification of and DNA followed by DLFD. Thick blood smear staining for microfilariae detection was used as the gold standard technique. Microfilariae screening and visual species identification using our microfluidic device plus miniPCR-DLFD platform yielded results concordant with those of the gold standard thick blood smear technique. The microfluidic device, the miniPCR and the DLFD are all portable and do not require additional equipment. Use of this screening and visual species identification platform will facilitate reliable, cost-effective, and rapid surveillance for the presence of LF infection in resource-poor settings.
PubMed: 35208460
DOI: 10.3390/mi13020336 -
Journal of Veterinary Diagnostic... Sep 2023Standard visual urine dipstick analysis (UDA) is performed routinely in veterinary medicine; results can be influenced by both the operator and the method. We evaluated...
Standard visual urine dipstick analysis (UDA) is performed routinely in veterinary medicine; results can be influenced by both the operator and the method. We evaluated the agreement of results for canine and feline urine samples analyzed using a 10-patch dipstick (Multistix10SG; Siemens), both visually under double-anonymized conditions by students and a laboratory technician, and with an automated device (AD; Clinitek Status, Siemens). The mean concordance for semiquantitative urinalysis results between students and the technician and between students and the AD was fair (κ0.21-0.40) in dogs and cats; concordance was moderate between the technician and the AD (κ0.41-0.60) in dogs and good (κ0.61-0.80) in cats. For pH, the mean concordance between students and the technician and between the technician and the AD was good (ρ0.80-0.92) in dogs and cats; concordance was good between students and the AD (ρ0.80-0.92) in dogs and moderate (ρ0.59-0.79) in cats. Repeatability was higher ( < 0.001) for the technician and the AD than for a student. We found good agreement between UDA performed by an experienced operator and an AD in dogs and cats but found low reproducibility and low repeatability for urinalysis performed by an inexperienced operator.
Topics: Cats; Dogs; Animals; Cat Diseases; Reproducibility of Results; Observer Variation; Dog Diseases; Reagent Strips; Urinalysis
PubMed: 37326167
DOI: 10.1177/10406387231181579 -
MSphere May 2021Isothermal nucleic acid amplification tests (iNATs), such as loop-mediated isothermal amplification (LAMP), are good alternatives to PCR-based amplification assays,...
Isothermal nucleic acid amplification tests (iNATs), such as loop-mediated isothermal amplification (LAMP), are good alternatives to PCR-based amplification assays, especially for point-of-care and low-resource use, in part because they can be carried out with relatively simple instrumentation. However, iNATs can often generate spurious amplicons, especially in the absence of target sequences, resulting in false-positive results. This is especially true if signals are based on non-sequence-specific probes, such as intercalating dyes or pH changes. In addition, pathogens often prove to be moving, evolving targets and can accumulate mutations that will lead to inefficient primer binding and thus false-negative results. Multiplex assays targeting different regions of the analyte and logical signal readout using sequence-specific probes can help to reduce both false negatives and false positives. Here, we describe rapid conversion of three previously described SARS-CoV-2 LAMP assays that relied on a non-sequence-specific readout into individual and multiplex one-pot assays that can be visually read using sequence-specific oligonucleotide strand exchange (OSD) probes. We describe both fluorescence-based and Boolean logic-gated colorimetric lateral flow readout methods and demonstrate detection of SARS-CoV-2 virions in crude human saliva. One of the key approaches to treatment and control of infectious diseases, such as COVID-19, is accurate and rapid diagnostics that is widely deployable in a timely and scalable manner. To achieve this, it is essential to go beyond the traditional gold standard of quantitative PCR (qPCR) that is often faced with difficulties in scaling due to the complexity of infrastructure and human resource requirements. Isothermal nucleic acid amplification methods, such as loop-mediated isothermal amplification (LAMP), have been long pursued as ideal, low-tech alternatives for rapid, portable testing. However, isothermal approaches often suffer from false signals due to employment of nonspecific readout methods. We describe general principles for rapidly converting nonspecifically read LAMP assays into assays that are read in a sequence-specific manner by using oligonucleotide strand displacement (OSD) probes. We also demonstrate that inclusion of OSD probes in LAMP assays maintains the simplicity of one-pot assays and a visual yes/no readout by using fluorescence or colorimetric lateral-flow dipsticks while providing accurate sequence-specific readout and the ability to logically query multiplex amplicons for redundancy or copresence. These principles not only yielded high-surety isothermal assays for SARS-CoV-2 but might also aid in the design of more sophisticated molecular assays for other analytes.
Topics: COVID-19; COVID-19 Testing; Humans; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Point-of-Care Testing; RNA, Viral; SARS-CoV-2; Saliva
PubMed: 34011690
DOI: 10.1128/mSphere.00911-20 -
Biosensors Dec 2023Ketones are well-known biomarkers of fat oxidation produced in the liver as a result of lipolysis. These biomarkers include acetoacetic acid and β-hydroxybutyric acid...
Ketones are well-known biomarkers of fat oxidation produced in the liver as a result of lipolysis. These biomarkers include acetoacetic acid and β-hydroxybutyric acid in the blood/urine and acetone in our breath and skin. Monitoring ketone production in the body is essential for people who use caloric intake deficit to reduce body weight or use ketogenic diets for wellness or therapeutic treatments. Current methods to monitor ketones include urine dipsticks, capillary blood monitors, and breath analyzers. However, these existing methods have certain disadvantages that preclude them from being used more widely. In this work, we introduce a novel acetone sensor device that can detect acetone levels in breath and overcome the drawbacks of existing sensing approaches. The critical element of the device is a robust sensor with the capability to measure acetone using a complementary metal oxide semiconductor (CMOS) chip and convenient data analysis from a red, green, and blue deconvolution imaging approach. The acetone sensor device demonstrated sensitivity of detection in the micromolar-concentration range, selectivity for detection of acetone in breath, and a lifetime stability of at least one month. The sensor device utility was probed with real tests on breath samples using an established blood ketone reference method.
Topics: Humans; Acetone; Body Fluids; Ketones; 3-Hydroxybutyric Acid; Biomarkers
PubMed: 38248381
DOI: 10.3390/bios14010004 -
Critical Reviews in Analytical Chemistry 2022A newly developed research topic, fabricated paper-based microfluidic sensors, was discussed in the field of low-cost environmental detection. Distinguished with the... (Review)
Review
A newly developed research topic, fabricated paper-based microfluidic sensors, was discussed in the field of low-cost environmental detection. Distinguished with the traditional dipstick or lateral-flow setups, these paper-based microfluidic sensors can serve as a tool for onsite quantitative and semi-quantitative measurements, without risks to cause environmental pollution. They have attracted increasing interest since the first easy-fabricated paper-based setup reported by Whitesides group in 2007. Most of the publications utilized paper-based sensors in clinical detection. In recent years, some groups started to use these sensors in environmental measurement, leading to precise, easy operation, low-cost, and eco-friendly methods for onsite detection. In this review, paper-based microfluidic sensors were briefly introduced, followed by literatures review and discussion for future perspectives.
Topics: Microfluidic Analytical Techniques; Microfluidics; Paper
PubMed: 33660571
DOI: 10.1080/10408347.2021.1886900 -
Clinica Chimica Acta; International... Aug 2023To address the situation that the accuracy of concentration intervals (CI) corresponding to dipstick grades is not given by the manufacturers or literature, we developed...
BACKGROUND
To address the situation that the accuracy of concentration intervals (CI) corresponding to dipstick grades is not given by the manufacturers or literature, we developed a method that determined reasonable dipstick grades with concentration intervals (GCIs) based on the percent agreement (PA) and discussed the GCI application to comparability among currently dipstick tests.
METHODS
By comparing the results of 2 dipstick tests (iChem and KU-500) with the quantitative test (AU5800), the GCIs were verified and established based on the PAs, which were calculated and used as an indicator of GCI's accuracy. The overlap (percent) between the 2 GCIs with the same grade (2 dipstick devices), was calculated and used to evaluate the agreement between their test results.
RESULTS
After verification and adjustment, the GCI and PA combinations for iChem Velocity were as follows: - (<0.1 g/l, 85 %), ± (0.1-0.3 g/l, 66 %), 1+ (0.3-1 g/l, 78 %), 2+ (1-3 g/l, 74 %), 3+ (3-6 g/l, 77 %), and 4+ (≥6 g/l, 84 %). The determined GCI and PA combinations for KU-500 were: - (<0.1.2 g/l, 75 %), ± (0.12-0.5 g/l, 63 %), 1+ (0.5-1.2 g/l, 69 %), 2+ (1.2-3.2 g/l, 76 %), and 3+ (≥3.2 g/l, 82 %). The GCI overlaps between the 2 dipstick devices were - (83 %), ± (45 %), 1+ (56 %), 2+ (82 %), and 3+ or ≥3+ (94 %). The overall overlap was 72 %. Since the overlaps ± (45 %) and 1+ (56 %) were within the overlap reject limit for any grade (70 %), and the overall overlap (72 %) was within the overall overlap reject limit (80 %), the test results of the 2 devices were not comparable.
CONCLUSIONS
GCIs can be verified and established correctly based on PAs, and industry standards for dipstick tests can be established based on GCIs and PAs. Comparability between dipstick devices, historical data, and literature data can be roughly determined based on the overlap.
Topics: Humans; Sensitivity and Specificity; Urinalysis; Reagent Strips
PubMed: 37500032
DOI: 10.1016/j.cca.2023.117500 -
BMC Nephrology Jun 2021Most studies of chronic kidney disease (CKD) in Sub-Saharan Africa (SSA) have been conducted in urban settings. They relied on GFR estimated from serum creatinine alone...
BACKGROUND
Most studies of chronic kidney disease (CKD) in Sub-Saharan Africa (SSA) have been conducted in urban settings. They relied on GFR estimated from serum creatinine alone and on the inexpensive, convenient urinary dipstick to assess proteinuria. The dipstick for proteinuria has not been directly compared with the gold standard albumin-to-creatinine ratio (ACR) in a large-sized study in SSA. We hereby assessed the influence of rural versus urban location on the level, interpretation, and diagnostic performance of proteinuria dipstick versus ACR.
METHODS
In a cross-sectional population-based study of CKD in both urban (n = 587) and rural (n = 730) settings in South-Kivu, Democratic Republic of Congo (DRC), we assessed the prevalence, performance (sensitivity, specificity, positive predictive value and negative predictive value) and determinants of a positive dipstick proteinuria as compared with albuminuria (ACR). Albuminuria was subdivided into: A1 (< 30 mg/g creatinine), A2 (30 to 299 mg/g creatinine) and A3 (≥ 300 mg/g creatinine).
RESULTS
The overall prevalence of positive dipstick proteinuria (≥ 1+) was 9.6 % (95 % CI, 7.9-11.3) and was higher in rural than in urban residents (13.1 % vs. 4.8 %, p < 0.001), whereas the prevalence of albuminuria (A2 or A3) was similar in both sites (6 % rural vs. 7.6 % urban, p = 0.31). In both sites, dipstick proteinuria ≥ 1 + had a poor sensitivity (< 50 %) and positive predictive value (< 11 %) for the detection of A2 or A3. The negative predictive value was 95 %. Diabetes [aOR 6.12 (1.52-24.53)] was a significant predictor of A3 whereas alkaline [aOR 7.45 (3.28-16.93)] and diluted urine [aOR 2.19 (1.35-3.57)] were the main predictors of positive dipstick proteinuria.
CONCLUSIONS
ACR and dipstick proteinuria have similar positivity rates in the urban site whereas, in the rural site, dipstick was 2-fold more often positive than ACR. The poor sensitivity and positive predictive value of the dipstick as compared with ACR makes it unattractive as a screening tool in community studies of CKD in SSA.
Topics: Adult; Creatinine; Cross-Sectional Studies; Democratic Republic of the Congo; Female; Glomerular Filtration Rate; Humans; Hydrogen-Ion Concentration; Male; Predictive Value of Tests; Proteinuria; Reagent Strips; Renal Insufficiency, Chronic; Rural Health; Urban Health; Urine
PubMed: 34172013
DOI: 10.1186/s12882-021-02431-w -
Biosensors Sep 2021The fast detection of trace amounts of hazardous contaminations can prevent serious damage to the environment. Paper-based sensors offer a new perspective on the world... (Review)
Review
The fast detection of trace amounts of hazardous contaminations can prevent serious damage to the environment. Paper-based sensors offer a new perspective on the world of analytical methods, overcoming previous limitations by fabricating a simple device with valuable benefits such as flexibility, biocompatibility, disposability, biodegradability, easy operation, large surface-to-volume ratio, and cost-effectiveness. Depending on the performance type, the device can be used to analyze the analyte in the liquid or vapor phase. For liquid samples, various structures (including a dipstick, as well as microfluidic and lateral flow) have been constructed. Paper-based 3D sensors are prepared by gluing and folding different layers of a piece of paper, being more user-friendly, due to the combination of several preparation methods, the integration of different sensor elements, and the connection between two methods of detection in a small set. Paper sensors can be used in chromatographic, electrochemical, and colorimetric processes, depending on the type of transducer. Additionally, in recent years, the applicability of these sensors has been investigated in various applications, such as food and water quality, environmental monitoring, disease diagnosis, and medical sciences. Here, we review the development (from 2010 to 2021) of paper methods in the field of the detection and determination of toxic substances.
Topics: Biosensing Techniques; Colorimetry; Environmental Monitoring; Hazardous Substances; Microfluidics; Paper; Point-of-Care Systems
PubMed: 34562906
DOI: 10.3390/bios11090316 -
Parasite (Paris, France) 2021Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis and threatens warm-blooded animal and human health worldwide. Simple and...
Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis and threatens warm-blooded animal and human health worldwide. Simple and applicable diagnostic methods are urgently needed to guide development of effective approaches for prevention of toxoplasmosis. Most molecular diagnostic tools for T. gondii infection require high technical skills, sophisticated equipment, and a controlled lab environment. In this study, we developed a loop-mediated isothermal amplification-lateral-flow-dipstick (LAMP-LFD) assay that specifically targets the 529 bp for detecting T. gondii infection. This novel portable device is universal, fast, user-friendly, and guarantees experimental sensitivity as well as low risk of aerosol contamination. Our LAMP-LFD assay has a detection limit of 1 fg of T. gondii DNA, and shows no cross-reaction with other parasitic pathogens, including Cryptosporidium parvum, Leishmania donovani, and Plasmodium vivax. We validated the developed assay by detecting T. gondii in DNA extracted from blood samples collected from 318 stray cats and dogs sampled from Deqing, Wenzhou, Yiwu, Lishui and Zhoushan cities across Zhejiang province, Eastern China. The LAMP-LFD device detected T. gondii DNA in 4.76 and 4.69% of stray cats and dogs, respectively. In conclusion, the developed LAMP-LFD assay is efficient, minimizes aerosol contamination, and is therefore suitable for detecting T. gondii across basic medical institutions and field settings.
Topics: Animals; Cats; China; Cryptosporidiosis; Cryptosporidium; Dogs; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Sensitivity and Specificity; Toxoplasma
PubMed: 33944774
DOI: 10.1051/parasite/2021039 -
Veterinary Clinical Pathology Dec 2022Urine dipstick and Heller's reaction are easy first-line screening tests for the detection of proteinuria; however, the performance of these methods in alkaline ovine...
BACKGROUND
Urine dipstick and Heller's reaction are easy first-line screening tests for the detection of proteinuria; however, the performance of these methods in alkaline ovine urine is largely unknown.
OBJECTIVE
The aim of this study was to evaluate the diagnostic performance of Heller's reaction alone or in combination with dipstick for the detection of proteinuria in sheep, using the urine protein to creatinine ratio (UP/C) with two cut-off values as the reference method.
METHODS
Ninety-eight urine samples were collected from sheep using the transient apnea method. Heller's reaction, the dipstick method, and the UP/C ratio were used to assess proteinuria. The results were statistically analyzed twice, based on two different UP/C cut-off values of 0.2 and 0.5. Cohen's kappa value was used to determine the agreement between the UP/C ratios and Heller's reaction, the dipstick method, or the combination of methods. Sensitivity, specificity, and positive and negative likelihood ratios were calculated. ROC curves were also generated, and the areas under the curve (AUC) were evaluated to determine the optimal threshold for the numerical values of the two methods.
RESULTS
Heller's reaction is more specific (96.67% and 96.00% when the cut-off value is 0.2 and 0.5, respectively) than the dipstick method, while the dipstick method was more sensitive (91.18% and 91.30%, when the cut-off value was 0.2 and 0.5, respectively) than Heller's reaction for the detection of proteinuria. Both tests were accurate when any grade >0 was considered positive.
CONCLUSIONS
Proteinuria can almost be excluded in ovine urine samples with negative Heller's reaction and dipstick test.
Topics: Sheep; Animals; Reagent Strips; Creatinine; Sensitivity and Specificity; Proteinuria; ROC Curve; Urinalysis; Sheep Diseases
PubMed: 35624545
DOI: 10.1111/vcp.13131