Head-to-head comparison of nasal and nasopharyngeal sampling using SARS-CoV-2 rapid antigen testing in Lesotho

Objectives To assess the real-world diagnostic performance of nasal and nasopharyngeal swabs for SD Biosensor STANDARD Q COVID-19 Antigen Rapid Diagnostic Test (Ag-RDT). Methods Individuals ≥5 years with COVID-19 compatible symptoms or history of exposure to SARS-CoV-2 presenting at hospitals in Lesotho received two nasopharyngeal and one nasal swab. Ag-RDT from nasal and nasopharyngeal swabs were performed as point-of-care on site, the second nasopharyngeal swab used for polymerase chain reaction (PCR) as the reference standard. Results Out of 2198 participants enrolled, 2131 had a valid PCR result (61% female, median age 41 years, 8% children), 84.5% were symptomatic. Overall PCR positivity rate was 5.8%. The sensitivity for nasopharyngeal, nasal, and combined nasal and nasopharyngeal Ag-RDT result was 70.2% (95%CI: 61.3-78.0), 67.3% (57.3-76.3) and 74.4% (65.5-82.0), respectively. The respective specificity was 97.9% (97.1-98.4), 97.9% (97.2-98.5) and 97.5% (96.7-98.2). For both sampling modalities, sensitivity was higher in participants with symptom duration ≤ 3days versus ≤ 7days. Agreement between nasal and nasopharyngeal Ag-RDT was 99.4%. Conclusions The STANDARD Q Ag-RDT showed high specificity. Sensitivity was, however, below the WHO recommended minimum requirement of ≥ 80%. The high agreement between nasal and nasopharyngeal sampling suggests that for Ag-RDT nasal sampling is a good alternative to nasopharyngeal sampling.

Comparison of prenatal central nervous system abnormalities with postmortem findings in fetuses following termination of pregnancy and clinical utility of postmortem examination

Objectives In this study, we aimed to compare prenatal ultrasound (USG) and postmortem examination findings of central nervous system (CNS) abnormalities in fetuses following termination of pregnancy (TOP). Methods A total of 190 fetuses with USG-confirmed fetal CNS abnormalities of terminated pregnancies between January 2001 and January 2017 were retrospectively analyzed and USG and postmortem examination findings were compared. Results The most frequent CNS abnormalities were acrania/anencephaly (n=45, 24%), spina bifida (n=43, 23%), and ventriculomegaly (n=35, 18%). In 144 of the 190 (76%) cases, there was total agreement between USG and postmortem examination diagnosis. Postmortem examination provided minor findings which did not change the major clinical diagnosis in two (1%) cases with spina bifida and ventriculomegaly. In six (3%) cases, the diagnosis changed after postmortem examination. In 25 of the 190 (13%) cases with multiple abnormalities as evidenced by USG, CNS abnormality was unable to be confirmed at postmortem examination. Conclusions Our study results show an overall high agreement (76%) between USG and postmortem examination findings for CNS malformations. Due to autolysis and fluid structure, USG-confirmed CNS diagnosis cannot be always confirmed by postmortem examination. This potential discrepancy should be explained to patients before considering TOP. Postmortem examination is the gold standard to confirm prenatal diagnosis.

Adjectival and verbal agreement in the oral production of early and late bilinguals

Extended oral production has seldom been used to explore adjectival and verbal agreement in L2 Spanish. This study examines oral narrations to compare the agreement behavior, speech rates, and patterns of errors of highly proficient Spanish heritage and L2 learners (early and late bilinguals, respectively), whose L1 is English, with those of native controls. Although both bilingual groups displayed high agreement accuracy scores, only the early bilinguals performed at or close to ceiling. In addition, the L2 learners spoke significantly more slowly than the heritage and native speakers, who displayed similar speech rates. Explanations accounting for the differences in speech rates and agreement accuracy include age of acquisition of Spanish, syntactic distance between a noun and its adjective, and task effects. All of these factors favored the early bilinguals, enhancing their advantages over L2 learners. Findings suggest that the integrated knowledge and automatic access needed for native-like attainment in agreement behavior in extended oral production is more easily achievable by early than by late bilinguals.

Comparison of Saliva and Mid-Turbinate Swabs for Detection of COVID-19

BackgroundSaliva is an attractive sample for detecting SARS-CoV-2 because it is easy to collect and minimally invasive. However, contradictory reports exist concerning the sensitivity of saliva versus nasal swabs.MethodsWe recruited and followed close contacts of COVID-19 cases for up to 14 days from their last exposure and collected self-reported symptoms, mid-turbinate swabs (MTS) and saliva every two or three days. Ct values and frequency of viral detection by MTS and saliva were compared. Logistic regression was used to estimate the probability of detection by days since symptom onset for the two sample types.ResultsWe enrolled 58 contacts who provided a total of 200 saliva and MTS sample pairs; 14 contacts (13 with symptoms) had one or more positive samples. Overall, saliva and MTS had similar rates of viral detection (p=0.78). Although Ct values for saliva were significantly greater than for MTS (p=0.014), Cohen’s Kappa demonstrated substantial agreement (κ=0.83). However, sensitivity varied significantly with time relative to symptom onset. Early in the course of infection (days -3 to 2), saliva had 12 times (95%CI: 1.2, 130) greater likelihood of detecting viral RNA compared to MTS. After day 2, there was a non-significant trend to greater sensitivity using MTS samples.ConclusionSaliva and MTS specimens demonstrated high agreement, making saliva a suitable alternative to MTS nasal swabs for COVID-19 detection. Furthermore, saliva was more sensitive than MTS early in the course of infection, suggesting that it may be a superior and cost-effective screening tool for COVID-19.Key PointsSaliva is more sensitive in detecting symptomatic cases of COVID-19 than MTS early in the course of infection.Saliva performs best in the pre-symptomatic period.Saliva and MTS demonstrated high agreement making saliva a suitable and cost-effective COVID-19 screening tool.

In vivo Imaging of Retina and Choroid in Guinea Pigs

Purpose: To evaluate the feasibility of in-vivo imaging of the retina and choroid using spectral domain optical coherence tomography (OCT) in guinea pigs.Methods: The study included 19 pigmented guinea pigs (age: 3–4 weeks) which underwent sonographic axial length measurements and OCT imaging. At study end, the animals were sacrificed and histomorphometric examinations of the retina and choroid were performed. We assessed the reproducibility of the OCT measurements and compared in-vivo measurements to histomorphometric data.Results: The mean thickness of the retina and choroid near the optic nerve head was 175.6 ± 25.8 and 63.4 ± 16.5 μm, respectively, and mean Bruch's membrane opening (BMO) diameter was 831 ± 121 μm. The intra-observer comparison of measurements of retinal thickness (intraclass correlation coefficient (ICC) = 0.92, 95% CI: 0.86–0.96; P < 0.001), choroidal thickness (ICC = 0.92, 95% CI: 0.86–0.96; P < 0.001), and BMO diameter (ICC = 0.92, 95% CI: 0.86–0.96; P < 0.001) showed a high correlation. A high agreement was present also for the inter-observer reproducibility of the measurements of retinal thickness (Pearson correlation coefficient (R) = 0.98; P < 0.001), choroidal thickness (R = 0.96; P < 0.001), and BMO diameter (R = 0.98; P < 0.001). The Bland-Altman plots showed that 2.6% (1/38), 5.3% (2/38), and 7.9% (3/38) of the measurement points of retinal thickness, choroidal thickness and BMO diameter, respectively, were located outside of the 95% limits of agreement. The OCT-based thickness measurements of retina and choroid were significantly higher than those measured by histomorphometry (both P-values <0.01).Conclusion: OCT-based in-vivo morphometric imaging of the retina and choroid in guinea pigs is feasible with an acceptable intra-observer repeatability and inter-observer reproducibility.

Dual-band all textile antenna with AMC for heartbeat monitor and pacemaker control applications

All textile integrated dual-band monopole antenna with an artificial magnetic conductor (AMC) is proposed. The proposed design operates at 2.4 and 5.8 GHz for wearable medical applications to monitor the heartbeat. A flexible and low-profile E- shaped CPW dual-band textile antenna is integrated with a 4 × 4 dual-band textile AMC reflector to enhance the gain and specific absorption rate (SAR). The SAR is reduced by nearly 95% at both 1 and 10 g. The design was measured on the body with a 2 mm separation. The simulated and measured results appear in high agreement in the case of with and without AMC array integration. The measurement was performed in the indoor environment and in an anechoic chamber to validate the design based on reflection coefficient and radiation pattern measurements.

Model of a prototype vehicle powered by a hybrid hydrogen system

The paper presents a physical mathematical model of the movement of a prototype vehicle equipped with an electric drive system powered by two sources of hydrogen fuel cell and supercapacitors. The model is based on the analysis of the forces acting on the vehicle during motion, taking into account both resistance to motion and propulsion. The model also considers the flow of electrical energy from two sources: a hydrogen fuel cell and supercapacitors, taking into account energy buffering. The aim of the model was to develop a tool to analyse fuel consumption at different control strategies of energy flow in a vehicle. The paper also presents the results of model identification for the Hydros prototype vehicle developed at Lublin University of Technology for the Shell Eco Marathon competition. Model validation was performed for a selected run during the 2019 London competition. High agreement of the model with the results of the actual vehicle was obtained.

Evaluation of antimicrobial susceptibility testing of Nocardia spp. isolates by broth microdilution with resazurin and spectrophotometry

Background Nocardia species are ubiquitous in natural environments and can cause nocardiosis. In the present study, the use of Resazurin salt and Spectrophotometry were proposed as alternative methods to reduce subjectivity in the interpretation of susceptibility results to antimicrobials by the broth microdilution method for Nocardia spp. Results The susceptibility of Nocardia spp. isolates to Amikacin, Ciprofloxacin, Minocycline and Trimethoprim-Sulfamethoxazole was evaluated by Minimum Inhibitory Concentration (MIC) determinations by the broth microdilution method. To verify cellular growth, the colour-changing dye Resazurin was applied, the Optical Densities were measured on a spectrophotometer, and both were compared to Clinical and Laboratory Standards Institute (CLSI) Gold Standard method (visual MIC determination). Percentages of essential and categorical agreements and interpretative categorical errors were calculated within each method (intra-reading) and between them (inter-reading). The Gold Standard visual reading demonstrated 100% of essential and categorical intra-reading agreements for Amikacin, and there was no error when compared with the alternative methods. For Ciprofloxacin, the comparison between the Gold Standard and the Spectrophotometric reading showed 91.5% of essential agreement. In the categorical intra-reading analysis for Minocycline, there were 88.1 and 91.7% in the Gold Standard and in the Spectrophotometric readings, respectively, and 86.4% of concordance between them. High rates of categorical agreement were also observed on the Trimethoprim-Sulfamethoxazole analyses, with 93.7% for the Gold Standard, 84.9% for the Resazurin readings, and 80.5% between them. Conclusions The alternative methods with Resazurin and Spectrophotometric readings showed high agreement rates with the Gold Standard.

Validated Simple HPLC-UV Method for Mycophenolic Acid (MPA) Monitoring in Human Plasma. Internal Standardization: Is It Necessary?

The aim of the work was to prepare a simple but reliable HPLC-UV method for the routine monitoring of mycophenolic acid (MPA). Sample preparation was based on plasma protein precipitation with acetonitrile. The isocratic separation of MPA and internal standard (IS) fenbufen was made on Supelcosil LC-CN column (150 × 4.6 mm, 5 µm) using a mobile phase: CH3CN:H2O:0.5M KH2PO4:H3PO4 (260:700:40:0.4, v/v). UV detection was set at 305 nm. The calibration covered the MPA concentration range: 0.1–40 µg/mL. The precision was satisfactory with RSD of 0.97–7.06% for intra-assay and of 1.92–5.15% for inter-assay. The inaccuracy was found between −5.72% and +2.96% (+15.40% at LLOQ) and between −8.82% and +5.31% (+19.00% at LLOQ) for intra- and inter-assay, respectively, fulfilling acceptance criteria. After a two-year period of successful application, the presented method has been retrospectively calibrated using the raw data disregarding the IS in the calculations. The validation and stability parameters were similar for both calculation methods. MPA concentrations were recalculated and compared in 1187 consecutive routine therapeutic drug monitoring (TDM) trough plasma samples from mycophenolate-treated patients. A high agreement (r2 = 0.9931, p < 0.0001) of the results was found. A Bland–Altman test revealed a mean bias of −0.011 μg/mL (95% CI: −0.017; −0.005) comprising −0.14% (95% Cl: −0.39; +0.11), whereas the Passing–Bablok regression was y = 0.986x + 0.014. The presented method can be recommended as an attractive analytical tool for medical (hospital) laboratories equipped with solely basic HPLC apparatus. The procedure can be further simplified by disapplying an internal standard while maintaining appropriate precision and accuracy of measurements.

FE-Simulation Based Design of Wear-Optimized Cutting Edge Roundings

The performance of cutting tools can be significantly enhanced by matching the cutting edge rounding to the process and material properties. However, the conventional cutting edge rounding design is characterized by a significant number of experimental machining studies, which involve considerable cost, time, and resources. In this study, a novel approach to cutting edge rounding design using FEM-based chip formation simulations is presented. Based on a parameterized simulation model, tool temperatures, stresses and relative velocities can be calculated as a function of tool microgeometry. It can be shown that the external tool loads can be simulated with high agreement. With the help of these loads and the use of wear models, the resulting tool wear and the optimum cutting edge rounding can be determined. The final experimental investigations show a qualitatively high agreement to the simulation, which will enable a reduced effort design of the cutting edge in the future.