Evaluation of an Electrochemiluminescent SARS-CoV-2 Antibody Assay

BACKGROUND

Little is known about the performance of the Roche novel severe acute respiratory syndrome coronavirus 2 antibody (anti-SARS-CoV-2) assay. We provide an extensive evaluation of this fully automated assay on Cobas e801/e602 immunoassay analyzers.

METHODS

We assessed the linearity, precision, and throughput of the Roche anti-SARS-CoV-2 assay. Sensitivity was calculated from 349 SARS-CoV-2 polymerase chain reaction (PCR) positive samples; specificity was determined from 715 coronavirus disease 2019 (COVID-19)-naive samples. We examined cross-reactivity against other antibody positive samples [syphilis, rheumatoid factor (RF), antinuclear antibody (ANA), double-stranded DNA (ds-DNA), influenza, dengue, hepatitis B (HBV), hepatitis C (HCV)] and the anti-SARS-CoV-2 kinetics.

RESULTS

The assay cut-off index (COI) was linear up to 90.8. The interassay precision was 2.9% for a negative control (COI = 0.1) and 5.1% for a positive control (COI = 3.0). Assay time is 18 min and results are available 1 min later; throughput for 300 samples was 76 min. Only 1 case positive for HBsAg tested falsely positive; specificity was 99.9%. The assay has a sensitivity of 97.1% 14 days after PCR positivity (POS) and 100% at ≥21 days POS; 48.2% of cases had anti-SARS-CoV-2 within 6 days POS. In 11 patients in whom serum was available prior to a positive antibody signal (COI ≥1.0) the interval between the last negative and first positive COI (time to "seroconversion") on average is 3 days (range 1-6 days) and 4 more days (range 1-7) for the anti-SARS-CoV-2 to plateau.

CONCLUSION

The Roche anti-SARS-CoV-2 assay shows excellent performance with minimal cross-reactivity from other viral and confounding antibodies. Antibody development and seroconversion appears quite early.

A novel evaluation index for adolescent idiopathic scoliosis progression measurement and diagnosis

Adolescent idiopathic scoliosis is a trunk deformity of the spine with lateral deviation and rotation in the transverse plane. The most traditional measurement index and parameter for scoliosis diagnosis is the Cobb's angle, which evaluates the curves of the scoliotic spine on the radiographic projection of the trunk. Although this method is widely accepted as the benchmark in scoliosis assessment, it has some limitations and restrictions in practical applications because it is measured on a PA (posterior-anterior or back to front) X-ray image, such as potential harmfulness from radiation exposure and high cost.In this paper, a novel evaluation index for adolescent idiopathic scoliosis measurement and diagnosis is introduced to complement the existing assessment index, such as the Cobb's angle, the differences of shoulder height, etc. The new evaluation index is based on the phenomenon of the tilt and deviation of the vertebras in a scoliotic spine, which forms the tilt angles between each pair of adjacent vertebras.A data sample of 30 X-ray images of scoliotic spines was used in this research to evaluate and examine the usability and validity of the new index. The Cobb's angle and the new index were calculated and compared using the same data sample. The correlation between the Cobb's angle and the index was also determined, and a high correlation is found which demonstrated the usefulness of this proposed index. In this paper, it has been shown that the newly-proposed index has the potential to be used as a tool to support the traditional scoliosis measurement methods.This method can also be generalized on the sagittal plane to define other evaluation indices for assessing the severity of kyphosis and lordosis. The idea of using angular separation to evaluate spinal deformity in multiple planes or in three-dimensional spaces will be discussed in future research.

Assistive obstacle detection and navigation devices for vision-impaired users

Quality of life for the visually impaired is an urgent worldwide issue that needs to be addressed. Obstacle detection is one of the most important navigation tasks for the visually impaired. In this research, a novel range sensor placement scheme is proposed in this paper for the development of obstacle detection devices. Based on this scheme, two prototypes have been developed targeting at different user groups. This paper discusses the design issues, functional modules and the evaluation tests carried out for both prototypes. Implications for Rehabilitation Visual impairment problem is becoming more severe due to the worldwide ageing population. Individuals with visual impairment require assistance from assistive devices in daily navigation tasks. Traditional assistive devices that assist navigation may have certain drawbacks, such as the limited sensing range of a white cane. Obstacle detection devices applying the range sensor technology can identify road conditions with a higher sensing range to notify the users of potential dangers in advance.

Dissipation of atrazine, enrofloxacin, and sulfamethazine in wood chip bioreactors and impact on denitrification

Wood chip bioreactors are receiving increasing attention as a means of reducing nitrate in subsurface tile drainage systems. Agrochemicals in tile drainage water entering wood chip bioreactors can be retained or degraded and may affect denitrification. The degradation of 5 mg L atrazine, enrofloxacin, and sulfamethazine under denitrifying conditions in wood chips from an in situ reactor was determined. The impact of these chemicals on denitrifying microorganisms was assessed using the denitrification potential assay, most probable number (MPN), and quantitative polymerase chain reaction targeting the gene of the denitrifiers. Initial half-lives for these chemicals in the aqueous phase were 0.98 d for atrazine, 0.17 d for enrofloxacin, and 6.2 d for sulfamethazine. Similar rates of disappearance in autoclaved and nonautoclaved wood chip solutions during the first 48 h suggested sorption was the dominant mechanism. The presence of atrazine did not impair denitrification potential, the MPN, or the copy number. The denitrifier MPN and copy number in sulfamethazine- and enrofloxacin-treated microcosms were less than the control within the first 5 d after chemical addition, whereas the denitrification potentials were not affected. However, after 45 d the denitrification rate, MPN and gene copy numbers for sulfamethazine and enrofloxacin were similar to that of the no-chemical control, indicating that acclimation of the denitrifier population to the antibiotic or reduced bioavailability over time allowed recovery of the denitrifier population.

Region-restricted rapid keypoint registration

A two-stage keypoint registration approach is proposed to achieve frame-rate performance, while maintaining high accuracy under large perspective and scale variations. First, an agglomerative clustering algorithm based on an effective edge significance measure is adopted to derive the corresponding regions for keypoint detection. Next, a light-weight detector and a compact descriptor are utilized to obtain the exact location of the keypoints. In conjunction with the point transferring method, the proposed approach can perform registration task in textureless regions robustly. Experiments are conducted to demonstrate that the approach can handle the real-time tracking tasks.

The effectiveness of detector combinations

In this paper, the performance improvement benefiting from the combination of local feature detectors for image matching and registration is evaluated. Possible combinations of five types of representative interest point detectors and region detectors are integrated into the testing framework. The performance is compared using the number of correspondences and the repeatability rate, as well as an original evaluation criterion named the Reconstruction Similarity (RS), which reflects not only the number of matches, but also the degree of matching error. It is observed that the combination of DoG extremum and MSCR outperforms any single detectors and other detector combinations in most cases. Furthermore, MDSS, a hybrid algorithm for accurate image matching, is proposed. Compared with standard SIFT and GLOH, its average RS rate exceeds more than 3.56%, and takes up even less computational time.

Treatment of wastewater containing phenol using a tubular ceramic membrane bioreactor

The performance of a membrane bioreactor (MBR) with a tubular ceramic membrane for phenol removal was evaluated under varying hydraulic retention times (HRT) and a fixed sludge residence time (SRT) of 30 days. The tubular ceramic membrane was operated with a mode of 15 minutes of filtration followed by 15 seconds of permeate backwashing at a flux of 250 l m(-2)hr(-1) along with an extended backwashing of 30 seconds every 3 hours of operation, which maintained the transmembrane pressure (TMP) below 100 kPa. Using a simulated municipal wastewater with varying phenol concentrations, the chemical oxygen demand (COD) and phenol removals observed were greater than 88% with excellent suspended solids (SS) removal of 100% at low phenol concentrations (approx. 100 mg l(-1) of phenol). Step increases in phenol concentration showed that inhibition was observed between 600 to 800 mg l(-1) of phenol with decreased sludge production rate, mixed liquor suspended solids (MLSS) concentration, and removal performance. The sludge volume index (SVI) of the biomass increased to about 450 ml g(-1) for a phenol input concentration of 800 mg l(-1). When the phenol concentration was decreased to 100 mg l(-1), the ceramic tubular MBR was found to recover rapidly indicating that the MBR is a robust system retaining most of the biomass. Experimental runs using wastewater containing phenol indicated that the MBR can be operated safely without upsets for concentrations up to 600 mg l(-1) of phenol at 2-4 hours HRT and 30 days SRT.

Nitrification and denitrification in partially aerated biological aerated filter (BAF) with dual size sand media

A 104-mm (4-inch) diameter pilot-scale biological aerated filter (BAF) with a media depth of 2.5 m (8.3 feet) was operated with an anaerobic, anoxic and oxic zone at a temperature of 23 degrees C. The medium for the anaerobic and anoxic zones was 10 mm diameter sand while the medium for the oxic zone was 5 mm diameter sand. The influent sCOD and total nitrogen concentrations in the feedwater were approximately 250 mg/L and 35 mg N/L, respectively. sCOD removal at optimum hydraulic retention time (HRT) of 3 h with recirculation rates of 100, 200 and 300% in the column was above 96%. Nitrification was found to be more than 96% for 3 h HRT at 200 and 300% recirculation. Total nitrogen removal was consistent at more than 80% for 4 and 6 h HRT at 300% recirculation. For 3 h HRT and 300% recirculation, total nitrogen removal was approximately 79%. The ammonia loading rates for maximum ammonia removed were 0.15 and 0.19 kg NH3-N/m3-day for 100 and 200% recirculation, respectively. The experimental results demonstrated that the BAF can be operated at an HRT of 3h with 200-300% recirculation rates with more than 96% removal of sCOD and ammonia and at least 75% removal of total nitrogen.

Registration using natural features for augmented reality systems

Registration is one of the most difficult problems in augmented reality (AR) systems. In this paper, a simple registration method using natural features based on the projective reconstruction technique is proposed. This method consists of two steps: embedding and rendering. Embedding involves specifying four points to build the world coordinate system on which a virtual object will be superimposed. In rendering, the Kanade-Lucas-Tomasi (KLT) feature tracker is used to track the natural feature correspondences in the live video. The natural features that have been tracked are used to estimate the corresponding projective matrix in the image sequence. Next, the projective reconstruction technique is used to transfer the four specified points to compute the registration matrix for augmentation. This paper also proposes a robust method for estimating the projective matrix, where the natural features that have been tracked are normalized (translation and scaling) and used as the input data. The estimated projective matrix will be used as an initial estimate for a nonlinear optimization method that minimizes the actual residual errors based on the Levenberg-Marquardt (LM) minimization method, thus making the results more robust and stable. The proposed registration method has three major advantages: 1) It is simple, as no predefined fiducials or markers are used for registration for either indoor and outdoor AR applications. 2) It is robust, because it remains effective as long as at least six natural features are tracked during the entire augmentation, and the existence of the corresponding projective matrices in the live video is guaranteed. Meanwhile, the robust method to estimate the projective matrix can obtain stable results even when there are some outliers during the tracking process. 3) Virtual objects can still be superimposed on the specified areas, even if some parts of the areas are occluded during the entire process. Some indoor and outdoor experiments have been conducted to validate the performance of this proposed method.

Registration based on projective reconstruction technique for augmented reality systems

In AR systems, registration is one of the most difficult problems currently limiting their application. In this paper, we propose a simple registration method using projective reconstruction. This method consists of two steps: embedding and tracking. Embedding involves specifying four points to build the world coordinate system on which a virtual object will be superimposed. In tracking, a projective reconstruction technique is used to track these four specified points to compute the model view transformation for augmentation. This method is simple, as only four points need to be specified at the embedding stage and the virtual object can then be easily augmented onto a real scene from a video sequence. In addition, it can be extended to a scenario using the projective matrix that has been obtained from previous registration results using the same AR system. The proposed method has three advantages: 1) It is fast because the linear least square method can be used to estimate the related matrix in the algorithm and it is not necessary to calculate the fundamental matrix in the extended case. 2) A virtual object can still be superimposed on a related area even if some parts of the specified area are occluded during the whole process. 3) This method is robust because it remains effective even when not all the reference points are detected during the whole process, as long as at least six pairs of related reference points correspondences can be found. Some experiments have been conducted to validate the performance of the proposed method.

Degradation and metabolite production of tylosin in anaerobic and aerobic swine-manure lagoons

Watershed contamination from antibiotics is becoming a critical issue because of increased numbers of confined animal-feeding operations and the use of antibiotics in animal production. To understand the fate of tylosin in manure before it is land-applied, degradation in manure lagoon slurries at 22 degrees C was studied. Tylosin disappearance followed a biphasic pattern, where rapid initial loss was followed by a slow removal phase. The 90% disappearance times for tylosin, relomycin (tylosin D), and desmycosin (tylosin B) in anaerobically incubated slurries were 30 to 130 hours. Aerating the slurries reduced the 90% disappearance times to between 12 and 26 hours. Biodegradation and abiotic degradation occur, but strong sorption to slurry solids was probably the primary mechanism of tylosin disappearance. Dihydrodesmycosin and an unknown degradate with molecular mass of m/z 934.5 were detected. Residual tylosin remained in slurry after eight months of incubation, indicating that degradation in lagoons is incomplete and that residues will enter agricultural fields.

Cold weather nitrogen removal deficiencies of aerated lagoons

Aerated lagoons are widely used throughout the state of Iowa, USA by small communities, due to their relatively low costs and maintenance requirements. Although aerated lagoons were not initially designed for ammonia removal many of these facilities have been assigned effluent ammonia limits in recent years Since widespread monitoring began, it has been found that aerated lagoons tend to have problems with high effluent ammonia concentrations during the winter and early spring. This study collected and analyzed data from 10 aerated lagoon facilities in central Iowa to determine the factors governing cold weather nitrogen removal in aerated lagoons. The factors found to affect performance were temperature and detention time. None of the following factors were found to significantly affect performance: dissolved oxygen (DO), pH, CBOD5 loading, total nitrogen loading, aerated cell depth and design standards governing the design. It should be noted that DO and pH were relatively constant and generally favorable for nitrification. Increased mixing energy was correlated with poorer performance, but this correlation may not be correct as the expected benefit of more intense mixing conditions may masked by the overwhelming benefit of long detention times.

Use of solvents to enhance PAH biodegradation of coal tar-contaminated soils

Bioremediation of coal tar-contaminated soils containing polycyclic aromatic hydrocarbons (PAHs) is highly challenging because of the low solubility and strong sorption properties of PAHs. Five coal tar-contaminated soils from former manufactured gas plant (MGP) sites were pretreated with two solvents, acetone and ethanol to enhance the bioavailability of the PAH compounds. The biodegradation of various PAHs in the pretreated soils was assessed using soil slurry reactors. The total PAH degradation rates for soils pretreated with solvents were estimated to be about two times faster than soils that were not pretreated with solvents. For example, the total PAH first order degradation rate constants were 0.165+/-0.032, 0.147+/-0.020, and 0.076+/-0.009 day(-1) for Vandalia (EXC) soil that were pretreated with acetone, ethanol, and with no solvent, respectively. A distinctive advantage for soils pretreated with solvents was the enhanced removal of 5-ring PAH compounds such as benzo(a)pyrene and to a limited extent 4-ring compounds such as chrysene. Even for soils with 3.5% or more organic carbon content (two soils out of five), the degradation rate constants of chrysene were found to be two times faster than soils that were not pretreated. The degradation rate constants of benzo(a)pyrene were enhanced by 2-6 times for all five contaminated soils that were pretreated with solvents. To further elucidate trends that control the solvent treatment, the percent improvement in degradation rate constants (100 x rate constants for pretreated soils/rate constants for non-treated soils) for 16 PAHs were found to correlate well with the PAH partition coefficients (K(oc)). Except for phenanthrene and the clay fraction of the soil, correlations between the percent improvement in degradation rates constants and several physical properties of the soils were poor and sporadic. This implies that the enhancement in PAH availability using solvent treatment was driven by the distribution of the PAHs between the solvent and the adsorbed PAHs.

Air sparging effectiveness: laboratory characterization of air-channel mass transfer zone for VOC volatilization

Air sparging in conjunction with soil vapor extraction is one of many technologies currently being applied for the remediation of groundwater contaminated with volatile organic compounds (VOCs). Mass transfer at the air-water interface during air sparging is affected by various soil and VOC properties. In this study with a single air-channel apparatus, mass transfer of VOCs was shown to occur within a thin layer of saturated porous media next to the air channel. In this zone, the VOCs were found to rapidly deplete during air sparging resulting in a steep concentration gradient while the VOC concentration outside the zone remained fairly constant. The sizes of the mass transfer zone were found to range from 17 to 41 mm or 70d(50) and 215d(50) (d(50)=mean particle size) for low organic carbon content media (<0.01% OC). The size of the mass transfer zone was found to be proportional to the square root of the aqueous diffusivity of the VOC, and was affected by the mean particle size, and the uniformity coefficient. Effects of the volatility of the VOCs as represented by the Henry's law constants and the airflow rates on the mass transfer zone were found to be negligible but VOC mass transfer from air-water interface to bulk air phase seems to play a role. A general correlation for predicting the size of the mass transfer zone was developed. The model was developed using data from nine different VOCs and verified by two other VOCs. The existence of the mass transfer zone provides an explanation for the tailing effect of the air phase concentration under prolonged air sparging and the rebound in the VOC air phase concentration after the sparging system is turned off.

African Burkitt's lymphoma: a new perspective

High titres of antibody to Epstein-Barr virus (EBV) late genes identify individuals at risk of developing endemic Burkitt's lymphoma (eBL). Viral lytic cycle early and intermediate-early gene expression in BL is associated with a favourable tumour response to chemotherapy. Our study investigated whether serological data identifying antibody expression to zta, a viral function that activates lytic-cycle gene expression, correlate with expression of its gene in tumours, and could have prognostic value. Studies on 10 Malawian patients, with presumed BL on clinical grounds, showed good correlations, suggesting that serum antibody responses might predict treatment responsiveness. The results with 1 patient were particularly striking. When admitted in January 1998, prognosis was poor as he was unable to walk, and had tumour cells, characteristic of stage IV disease, in his bone marrow. Laboratory investigations showed particularly high levels both of serum zta antibodies and of gene expression in his tumour. Follow-up confirmed him alive 6 months after hospital discharge. Among the EBV-positive cases, 2 were ultimately diagnosed as rhabdomyosarcoma, a tumour not previously associated with this virus. The findings from this small study, if confirmed, should have value for future BL management in resource-poor parts of the world.

Immunoglobulin D multiple myeloma in our hospital--a rare occurrence

Immunoglobulin (Ig) D multiple myeloma is a rare presentation, usually with an aggressive course and a poorer prognosis. It accounts for about 1-2% of newly diagnosed mulitple myeloma patients. Due to its rarity, reports on Ig D multiple myeloma are limited in the literature. We therefore present 4 cases of Ig D multiple myeloma in our hospital over a period of 8 years between 1990 to 1998. The average age of presentation of our patients was 44 years old with a female preponderance. Common presenting symptoms were appetite and weight loss and bone pain. Two patients presented with neurological symptoms and 2 with renal impairment. Three patients had an associated lambda paraproteinaemia and the fourth had a kappa paraproteinaemia. A common finding in Ig D myeloma is a small or no spike seen on serum electrophoresis together with heavy Bence Jones proteinuria. A review of the literature on Ig D myeloma is also presented.

Pre-operative chemotherapy for squamous cell carcinoma of the oesophagus: do histological assessment and p53 overexpression predict chemo-responsiveness?

Pre-operative chemotherapy is increasingly used in the treatment of oesophageal carcinoma. However, no features have been identified which can reliably predict a positive response to chemotherapy. The aim of this study was to examine whether histological features and p53 overexpression could predict such response. Prechemotherapy endoscopic biopsies from 55 patients, who subsequently completed two courses of chemotherapy followed by surgical resection, were studied. Patients were classified into responders and non-responders according to clinical and pathological findings. Pathological features of the endoscopic biopsies examined included adequacy of the tumour tissue, histological grade, degree of keratinisation, histologic patterns, mitotic rates and nuclear pleomorphism. Biopsy specimens were also tested for p53 overexpression using p53 protein specific mouse monoclonal antibody DO-7 on paraffin sections. Histologic features and p53 expression were correlated to chemoresponsiveness. 76% (42 of 55) of patients had sufficient biopsy tissue for assessment. Response to chemotherapy was evident in 64% (n = 27) of patients. None of the non-responders had tumours with high-grade nuclear pleomorphism compared with 37% (10 of 27) of responders (P = 0.01). All patients with high-grade nuclear pleomorphism responded to chemotherapy. No significant differences were found between the responders and non-responders with respect to tumour differentiation (P = 0.7), degree of keratinisation (P = 0.3) and mitotic rates (P = 0.8). Overall, p53 overexpression was noted in 67% (28 of 42) of patients. This was more prevalent in non-responders (12/15) compared to responders (16/27), but this was not statistically significant (P = 0.08). The degree of p53 overexpression had no significant relationship with responsiveness to chemotherapy. High-grade nuclear pleomorphism, identified on pretreatment biopsy specimens, correlated with response to chemotherapy, whereas p53 overexpression did not correlate with response. Improved tissue sampling and further investigations should be done so that the assessment of prechemotherapeutic endoscopic biopsies can have significant impact on clinical decision making.

Termination of pregnancy in cases of intrauterine fetal death, missed abortion, molar and anencephalic pregnancy with intramuscular administration of 2a 2b dihomo 15(S) 15 methyl PGF2 alpha methyl ester--a multicentre study

2a 2b dihomo 15(S) 15 methyl PGF2 alpha methyl ester (dihomo 15 me PGF2 alpha) in intramuscular doses of 0.5 mg 8 hourly was used in 631 patients with abnormal intrauterine pregnancy comprising 282 cases of intrauterine fetal death, 233 cases of missed abortion, 34 and 82 cases respectively anencephalic and molar pregnancies. The study was carried out as a collaborative project between the University Departments of Obstetrics and Gynaecology in Singapore (Singapore), Medan (Indonesia) and Kuala Lumpur (Malaysia) during the period June 1974 and November 1979. Six hundred patients (95.1%) aborted or delivered in a mean time of 11.3 hours (S.D. +/- 7.0) with an average of 1.8 injections of the prostaglandin analogue per patient. Side effects included vomiting (23.6%; mean 0.45 episodes per patient), diarrhoea (44.4%; mean 1.00 episode per patient), cold and shivering (11.9%) and pyrexia (12.4%). One patient sustained a cervical laceration which did not require repair. There were no complications.