Overall Coefficient Of Variation Research Articles

A 10-year follow-up study of yearly indoor radon measurements in homes, review of other studies and implications on lung cancer risk estimates

Uncertainty on long-term average radon concentration has a large impact on lung cancer risk assessment in epidemiological studies. The uncertainty can be estimated by year-to-year radon concentration variability, however few data are available. In Italy a study has been planned and conducted to evaluate year-to-year radon variability over several years in normally inhabited dwellings, mainly located in Rome. This is the longest study of this kind in Europe; repeat radon measurements are carried out for 10 years using LR-115 radon detectors in the same home in consecutive years. The study includes 84 dwellings with long-term average radon concentration ranging from 28 to 636 Bq/m3. The result shows that year-to-year variability of repeated measurements made in the same home in different years is low, with an overall coefficient of variation of 17%. This is smaller than most of those observed in studies from other European countries and USA, ranging from 15% to 62%. Influencing factors that may explain the differences between this study and other studies have been discussed. Due to the low yearly variability estimated in the present 10-year study, a negligible impact on lung cancer risk estimate for the Italian epidemiological study is expected.

ThicknessTool: automated ImageJ retinal layer thickness and profile in digital images

To develop an automated retina layer thickness measurement tool for the ImageJ platform, to quantitate nuclear layers following the retina contour. We developed the ThicknessTool (TT), an automated thickness measurement plugin for the ImageJ platform. To calibrate TT, we created a calibration dataset of mock binary skeletonized mask images with increasing thickness masks and different rotations. Following, we created a training dataset and performed an agreement analysis of thickness measurements between TT and two masked manual observers. Finally, we tested the performance of TT measurements in a validation dataset of retinal detachment images. In the calibration dataset, there were no differences in layer thickness between measured and known thickness masks, with an overall coefficient of variation of 0.00%. Training dataset measurements of immunofluorescence retina nuclear layers disclosed no significant differences between TT and any observer’s average outer nuclear layer (ONL) (p = 0.998), inner nuclear layer (INL) (p = 0.807), and ONL/INL ratio (p = 0.944) measurements. Agreement analysis showed that bias between TT vs. observers’ mean was lower than between any observers’ mean against each other in the ONL (0.77 ± 0.34 µm vs 3.25 ± 0.33 µm) and INL (1.59 ± 0.28 µm vs 2.82 ± 0.36 µm). Validation dataset showed that TT can detect significant and true ONL thinning (p = 0.006), more sensitive than manual measurement capabilities (p = 0.069). ThicknessTool can measure retina nuclear layers thickness in a fast, accurate, and precise manner with multi-platform capabilities. In addition, the TT can be customized to user preferences and is freely available to download.

The Gap between Urban and Rural Development Levels Narrowed

The difference between urban and rural development levels (URDL) and the deficiency of rural development level have become the weak points for China to achieve balanced and high-quality development. In order to reveal the changing trend of urban-rural differences in China over the years and provide a reference for the policy-making of the balanced development of urban and rural areas and high-quality economic development, this paper uses the United Nations Development Program-adjusted Human Development Index (HDI) calculation method to calculate the urban and rural areas, based on 1995–2017 national time series data and provincial panel data. On this basis, this paper uses the Logarithmic Mean Weight Divisia to decompose the dynamic changes of the difference of URDL and analyzes the spatial equilibrium of the change trend of the differences of URDL, supplementing the shortcomings of the existing literature which only focuses on income, education, and other local areas and lacks continuity and comparison. The research finds that 1. based on the time series analysis of the difference of URDL, this paper firstly proposes the “inverted U” curve for the difference of URDL in China, which shows that the difference of URDL in China has experienced a process from expansion (1995–2001) to high fluctuation (2001–2011) to continuous convergence (2011–2017). 2. From the factor decomposition effect of the difference of URDL, the difference expansion period is caused by the increase in the gap between the Health Index, the Education Index, and the Income Index. With the decline in the gap between education levels and life expectancy, the growth trend of China’s urban-rural gap has been suppressed, and it has entered a high platform period with relative small fluctuation. After 2011, benefiting from the large decline in income level gaps, China’s urban-rural difference has entered a period of convergence. 3. From the perspective of the spatial evolution characteristics of the gap of URDL, the overall coefficient of variation of the country has shown a downward trend. The degree of spatial equilibrium is gradually increasing, and the overall changes in the east, west, and northeast are the same as the overall trend of the country. The decline in the northeast is the largest, the west is the second, and the east is the least. The middle shows a slight upward trend, but the value of each year is always smaller compared with other regions. Generally speaking, the gap of URDL is relatively good in the middle and northeast, followed by the east, and there is still much room for improvement in the balance of the west.

Quality Control Procedures and Baseline Values for Electroretinography, Perimetry, Color Vision, and Visual Acuity in an International Multicenter Study: Observations from a Safety Trial in Chronic Stable Angina Pectoris.

PurposeTo describe quality control procedures and baseline values of electroretinography (ERG), kinetic and static perimetry, color discrimination, and best-corrected visual acuity from a multicenter ocular safety study.MethodsA multicenter prospective longitudinal randomized placebo-controlled study was conducted at 11 ophthalmic centers that had received certification following training, instruction, and monitoring. ERGs were obtained with the Espion E2 Ganzfeld console, perimetry with the Octopus 101 perimeter, color discrimination with the Lanthony desaturated D15 test, and best-corrected visual acuity with the Early Treatment Diabetic Retinopathy Study chart. Ophthalmic eligibility required satisfactory outcomes for ERG and perimetry by the second or third pre-inclusion attempts, respectively. Quality control for the ERG was undertaken by two central readers.ResultsThe mean (SD) age of the 97 individuals was 63.5 (7.9) range, 44–83 years. The overall coefficients of variation (CVs) for the ERG peak times were less than those of the only comparable single-center study. The CV for the mean defect of standard automated perimetry was approximately one-third that of the Ocular Hypertension Treatment Study. With increasing age, ERG peak times and color discrimination Total Error Score increased while ERG amplitudes and isopter area all decreased.ConclusionsThe data illustrate the benefit of identical equipment, stringent on-site instruction and training, quality control, certification, and validation methods. The latter are recommended for planning and conducting multicenter trials using ERG and perimetry to monitor safety and/or efficacy of treatment intervention.Translational RelevanceStringent quality control procedures and reliable reference values are indispensable prerequisites for informative clinical trials.

Evaluation of the Uncertainty of Passive Cavitation Measurements for Blood–Brain Barrier Disruption Monitoring

Exposure to ultrasound combined with intravenous injection of microbubbles is a technique that can be used to temporarily disrupt the blood–brain barrier. Transcranial monitoring of cavitation can be done with one or more passive cavitation detectors (PCDs). However, the positioning of the PCDs relative to the cavitation site and the attenuation of these signals by the skull are two sources of error in the quantification of cavitation activity. The aim of this study was to evaluate in vitro the amplitude variation of cavitation signals that can be expected for an excised porcine skull model. The variation caused by the relative positioning of the PCD with respect to the cavitation site was quantified. A position-based correction of the signal amplitude was evaluated. Pig skull samples were used to assess variation in signal amplitude caused by bone. The overall coefficient of variation of the signals owing to these measurement biases was estimated at 30.8%.

Histological evaluation of pineapple transgenic plants following 8 years of field growth

Pineapple is among the most important fruits worldwide. However, the narrow genetic base of current commercial cultivars renders the industry at risk from environmental and other biological threats. Hence, there is a need to develop improved cultivars with tolerance to biotic and abiotic stresses. Our prior research resulted in the establishment of a method for genetic transformation of pineapple. The genetically modified pineapple plants generated were characterized following acclimatization and during the subsequent 8 years under field conditions. The current work highlights the results obtained for histological characterization of roots and leaves of transgenic pineapple plants. The four treatments investigated were macropropagated control plants (untransformed), micropropagated control plants (untransformed), and micropropagated genetically transformed plants (clones 90 and 98). Twenty indicators were measured in plants: two of them did not show statistically significant differences among the four groups of plants (2/20 = 10.0%); six showed “Low” overall coefficients of variation (OCV) (6/20 = 30.0%); 12 showed “Medium” OCVs (12/20 = 60.0%); and only two indicators showed “High” OCVs (2/20 = 10.0%). Consideration of medium OCVs showed that the biomass of transgenic plants was slightly greater than those of the non-transgenic controls. Statistically significant differences between the lines were recorded except in the central cylinder diameter of roots and the D leaf adaxial cuticle thickness. “High” OCVs were observed for root exo- and endodermis thickness where transgenic clones showed statistically significantly higher values. In terms of the roots, five out of nine histological indicators showed “Medium” OCVs: cortex, rhyzodermis, and parenchyma thicknesses, pith diameter, and thickness of the transversal root ratio. Again, genetically transformed materials showed statistically significantly higher averages. Only three out of seven histological indicators showed “Medium” OCVs in the leaves: D leaf abaxial cuticle thickness, chlorophyll parenchyma thickness, and D leaf aquifer parenchyma thickness. As noted above, statistically significantly higher values were recorded in the transgenic pineapple plants. Since the differences observed did not ultimately affect fruit yield (as shown in our previous work), they do not appear to be consequences of genetic transformation that impact on reproductive yield.

Alternative Algorithm for Automatically Driving Best-Fit Building Energy Baseline Models Using a Data—Driven Grid Search

Change-point regression models are often used to develop building energy baselines that can be used to predict energy use and determine energy savings during a given performance period. However, the reliability of building energy baselines can depend on how well the change-point model fits the data measured during the baseline period. This research proposes the use of segmented linear regression models with one or two change points for automatically driving best-fit building energy baseline models, along with an algorithm using a data-driven grid search to find the optimal change point(s) within a given data boundary for the proposed models. The algorithm was programmed and tested with actual measured data (e.g., daily gas and electricity use) for case-study buildings. Graphical and statistical analysis was also performed to validate its reliability within acceptable deviations of an overall coefficient of variation of the root mean squared error (i.e., CV(RMSE)) of 1%, as compared to the results derived from the ASHRAE Inverse Model Toolkit (IMT) that was developed as a public domain program to manually derive the change-point model with user specified parameters. Consequently, it is expected that the algorithm can be applied for automatically deriving best-fit building energy baseline models with optimal change point(s) from measured data.

Laboratory Performance of Serum Holotranscobalamin Assay in the United Kingdom (UK) As Assessed By the UK National External Quality Assessment Scheme for Haematinics

Background Although serum B12 assay is the most commonly used routine test for assessing cobalamin status in the body, it has its limitations (Mackenzie F and Devalia V (2018) Laboratory performance of serum B12 assay in the United Kingdom (UK) as assessed by the UK National External Quality Assessment Scheme for haematinics: implications for clinical interpretation. BLOOD, 132, suppl 1, 2230). Holotranscobalamin assay(HoloTC), also known as 'Active B12' assay, is an alternative test which is increasingly used as a first line test since it is felt to represent the assessment of the functional component of the cobalamin status of the body, and possibly a more relevant assessment clinically. However, its technical performance in terms of reliability and suitability in a routine diagnostic laboratory for clinical assessment has not been published. In the United Kingdom, there are over 30 laboratories performing the assay using five different platforms. The numerical value obtained of any sample can vary considerably between the different methodologies used.. External quality assessment of the assays is organised by UK NEQAS for Haematinics by sending three serum samples every 3 months. An 'all participants' consensus mean is calculated and used as the target value and the results analysed with respect to intra-group variation. The percentage bias from the target value is used to assess performance. Aim We present data on one such assessment to demonstrate the performance of the serum holotranscobalamin assay (Survey number 248, April 2018) and also how it is interpreted by the laboratory for clinical use. Method Three serum samples with a HoloTC target value of approximately 7.98 (low/indeterminate), 35.7 (normal/indeterminate) and 53.2 (normal) pmol/L were sent to participating laboratories for analysis (labelled as 248A, B and C respectively: see figure 1). Laboratories were also asked for an interpretation of their result which would be reported to the requesting clinician, namely from low to high (see figure 2). Results Fig 1 shows an individual laboratory's result in relation to all laboratories using the same technology (shaded histogram) or all methods (open histogram). There is a significant variation with an overall co-efficient of variation of around 10% within all the three different samples. Fig 2 shows the distribution of results in the different methodologies used and how each laboratory interpreted its result. It demonstrates the bias of results obtained by the different methods.The vast majority use the Abbot Architect (AB13) platform, and there is a suggestion of a trend of the results obtained to lie on the lower side than the other platforms used. For sample 248A, all laboratories reported it as 'low' or deficient. For sample 248B, there is a significant variation is reporting the sample as 'low', 'normal' or 'indeterminate' within the same platform used, clearly seen in the Abbot Architecture group. Indeed, the interpretation provided by the laboratory varies even with the same numerical value of the result. Discussion These data demonstrate that serum HoloTC assay has an overall co-efficient of variation around 10%. The numerical value obtained of any sample can vary considerably according to the technology used, and the clinical interpretation provided by the laboratory can be variable and not entirely concordant with the numerical result of the assay used. This is particularly evident around the 30-40 pmol/L range. This may be partly explained by the fact that it is not quite clear what would be regarded as the normal or reference range, which has been previously taken as 40 - 200 pmol/L (according to previous publications). Conclusion The UK NEQAS Haematinics Programme is unique in providing external quality assessment for laboratories using HoloTC assays for determining body cobalamin status in a style that is also unique across EQA/ PT schemes. Laboratories need to assess their performance in analysis of serum HoloTC levels in order to provide appropriate clinical advice. Ideally clinicians should be aware of the limitations of the HoloTC assay as demonstrated in this external quality assessment scheme exercise. Disclosures No relevant conflicts of interest to declare.

Abstract 2239: Analysis of nucleosomal DNA as an extraction control for plasma-based circulating tumor DNA assays

Abstract Purpose: Challenges to accurate quantitative measurements of circulating tumor DNA (ctDNA) include variable contamination with large DNA fragments released during mononuclear cell lysis, and potential variability in extraction efficiency. We investigated optimal procedures for plasma processing and the potential utility of a DNA spike-in as a process control for extraction efficiency. Methods: Initial experiments analyzed the potential benefits of different centrifugation protocols (1600 x g vs. 1600 x g followed by 16000 x g) for plasma separation by analyzing the size distribution of extracted DNA using a BioAnalyzer. In subsequent experiments we used droplet digital PCR (ddPCR) to compare differences in extraction efficiency between nucleosomal DNA (nDNA) and genomic DNA (gDNA) spiked into healthy donor plasma and extracted using the QIAamp DSP Circulating NA Kit (Qiagen). To evaluate the properties of the purification columns with respect to the yield of different DNA sizes, we compared the plasma results to experiments extracting purified nDNA and gDNA spiked into PBS instead of plasma. We investigated the potential competitive effect of large DNA on the extraction efficiency of small DNA by mixing nDNA with commercially available human gDNA in different concentrations. To assess if nDNA, when spiked into patient plasma, would track with endogenous ctDNA, we spiked a pool of plasma from patients with BRAFV600E mutations with known quantities of nDNA purified from NRASQ61K mutant cells (CHP212). The spiked plasma pool was divided and extracted using multiple separate columns. Copies/ml and mutant fraction were determined by ddPCR assays for BRAFV600E and NRASQ61K. Coefficients of variation were also calculated. Results: Comparison of different centrifugation speeds for plasma processing before and after freeze-thaw indicated that a 2nd high-speed centrifugation (16000 x g), either before or after a freeze-thaw cycle, minimizes large DNA in plasma samples prior to ctDNA extraction. In initial spike-in experiments extraction efficiency for nDNA was 87.7% compared to 42% for gDNA. We obtained similar results when purifying the nDNA and gDNA from PBS instead of plasma. We observed greater variability in nDNA extraction efficiency when increasing amounts of gDNA were added as a contaminant. Finally, we found that the slight, paralell variations in extraction yields of externally spiked NRASQ61K mutant nDNA and endogenous BRAFV600E ctDNA in 7/9 replicate extractions. The overall coefficients of variation (total copies/mL) for 9 extractions for BRAFV600E and NRASQ61K were 3.9 and 4.2 respectively. Conclusion: A second centrifugation step helps reduce potential contamination of ctDNA with large DNA, and may improve the recovery of ctDNA from plasma samples. Nucleosomal DNA can potentially be used as a process control for extracting ctDNA from plasma samples. Citation Format: Mahrukh M. Syeda, George Karlin-Neumann, Iman Osman, David Polsky. Analysis of nucleosomal DNA as an extraction control for plasma-based circulating tumor DNA assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2239.

Comprehensive quantification of sesame allergens in processed food using liquid chromatography-tandem mass spectrometry

Sesame (Sesamum indicum) is a well-recognized food allergen, and sesame-related allergies have been increasingly reported worldwide. Patients with sesame allergy are specifically allergic to different sesame proteins (Ses i 1–7). Because of the increasing burden associated with allergies to sesame, there is an urgent need to develop sensitive and quantitative analytical methods capable of detecting sesame allergen contaminants. Targeted proteomic approach employing liquid chromatography/tandem mass spectrometry (LC-MS/MS) has emerged as a promising technique that offers increased specificity and reproducibility compared to antibody and DNA-based technologies. In this study, we developed a qualitative and absolute quantification method based on the LC-MS/MS-multiple reaction monitoring (MRM) system utilizing stable isotope-labeled internal standard (SIIS) peptides. We optimized extraction and trypsin digestion conditions and selected signature and absolute quantification (AQUA) peptides for seven sesame allergen proteins respectively. This quantitative method produced a linear relationship (R2 > 0.99) in a wide concentration range (0.4–2000 fmol/μL), and the overall coefficient of variation was <5% in multiple tests. Limits of detection (LOD) and Limits of quantification (LOQ) for the seven sesame allergens AQUA peptides were determined to range from 0.1 to 140.0 fmol/μL and 0.4–400 fmol/μL respectively. The results showed that the accuracy of 20, 50, 100 ppm incurred protein Ses i 2 were 90%, 92%, 94% in non-processed material and 92%, 95%,102% in processed material respectively. Overall, this method allowed for rapid and simultaneous absolute quantification of seven sesame allergens. The newly developed LC-MS/MS assay will likely increase the safety of sesame processed foods and add diagnostic value to the sesame allergy testing.

Proton density fat fraction MRI of vertebral bone marrow: Accuracy, repeatability, and reproducibility among readers, field strengths, and imaging platforms.

Chemical shift-encoding based water-fat MRI is an emerging method to noninvasively assess proton density fat fraction (PDFF), a promising quantitative imaging biomarker for estimating tissue fat concentration. However, in vivo validation of PDFF is still lacking for bone marrow applications. To determine the accuracy and precision of MRI-determined vertebral bone marrow PDFF among different readers and across different field strengths and imager manufacturers. Repeatability/reproducibility. Twenty-four adult volunteers underwent lumbar spine MRI with one 1.5T and two different 3.0T MR scanners from two vendors on the same day. 1.5T and 3.0T/3D spoiled-gradient echo multipoint Dixon sequences. Two independent readers measured intravertebral PDFF for the three most central slices of the L1-5 vertebral bodies. Single-voxel MR spectroscopy (MRS)-determined PDFF served as the reference standard for PDFF estimation. Accuracy and bias were assessed by Pearson correlation, linear regression analysis, and Bland-Altman plots. Repeatability and reproducibility were evaluated by Wilcoxon signed rank test, Friedman test, and coefficients of variation. Intraclass correlation coefficients were used to validate intra- and interreader as well as intraimager agreements. MRI-based PDFF estimates of lumbar bone marrow were highly correlated (r2 = 0.899) and accurate (mean bias, -0.6%) against the MRS-determined PDFF reference standard. PDFF showed high linearity (r2 = 0.972-0.978) and small mean bias (0.6-1.5%) with 95% limits of agreement within ±3.4% across field strengths, imaging platforms, and readers. Repeatability and reproducibility of PDFF were high, with the mean overall coefficient of variation being 0.86% and 2.77%, respectively. The overall intraclass correlation coefficient was 0.986 as a measure for an excellent interreader agreement. MRI-based quantification of vertebral bone marrow PDFF is highly accurate, repeatable, and reproducible among readers, field strengths, and MRI platforms, indicating its robustness as a quantitative imaging biomarker for multicentric studies. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1762-1772.

Assessment of Pru p 1 and Pru p 3 in peach fruit by liquid chromatography–tandem mass spectrometry

Pru p 1 and Pru p 3 are proteins found in peach (Prunus persica (L.) Batsch), and they are members of the pathogenesis-related protein 10 (PR-10) and non-specific lipid transfer protein (nsLTP) families, respectively. They are the main allergens of peach. In this paper, we describe a quantitative method for these proteins based on protein absolute quantification with liquid chromatography–tandem mass spectrometry, and LVASPSGGSIIK[13C6,15N2] and ISASTNC[CAM]ATVK[13C6,15N2] (C[CAM]: carbamidomethyl-modified C), stable isotope-labelled internal standard peptides. We show that this method exhibits linearity with r2 > 0.97 in a dose range of 3.1–200 fmol/μL for LVASPSGGSIIK[13C6,15N2] and 13–200 fmol/μL for ISASTNC[CAM]ATVK[13C6,15N2]), and overall coefficients of variation for multiple tests of 11.6–30.1%. This approach is therefore helpful for screening and breeding low allergenic peach cultivars.

A volumetric absorptive microsampling LC-MS/MS method for five immunosuppressants and their hematocrit effects.

Aim: The aim of this study was to develop and validate a LC-MS/MS assay for tacrolimus, sirolimus, everolimus, cyclosporin A and mycophenolic acid using volumetric absorptive microsampling tips as a sampling device and to investigate the effect on the recoveries of the analyte concentration in combination with the hematocrit (HT), which included temsirolimus (a structural analog). Results: The maximum observed overall bias was 9.6% for the sirolimus LLOQ, while the maximum overall coefficient of variation was 8.3% for the everolimus LLOQ. All five immunosuppressants demonstrated to be stable in the volumetic absorbtive microsampling tips for at least 14 days at 25°C. Biases caused by HT effects were within 15% for all immunosuppressants between HT levels of 0.20 and 0.60l/l, except for cyclosporin A, which was valid between 0.27 and 0.60l/l. Reduced recoveries were observed at high analyte concentrations in combination with low HT values for sirolimus, everolimus and temsirolimus. Conclusion: A robust extraction and analysis method in volumetric absorptive microsampling tips was developed and fully validated. HT- and concentration-related recovery effects were observed but were within requirements of the purpose of the analytical method.

Edoxaban plasma levels in patients with non-valvular atrial fibrillation: Inter and intra-individual variability, correlation with coagulation screening test and renal function

BackgroundHigh inter-individual variability of the anticoagulant plasma levels of the first three direct oral anticoagulants was previously reported. Aims of the present study were to evaluate edoxaban inter and intra-individual variability in patients with non valvular atrial fibrillation and to assess correlation between edoxaban plasma levels and coagulation screening test and renal function. MethodsFrom January 31st 2017 to June 30th 2018, a total of 101 NVAF patients were enrolled: 48 patients were on edoxaban 60 mg and 53 on edoxaban 30 mg, once daily. Blood samples were taken at C-trough and at C-peak within the first month (15–25 days) of treatment and then at C-trough each three months. Prothrombin time (PT), activated partial thromboplastin time (aPTT), specific anti-FXa chromogenic test were performed. Creatinine clearance (CrCl) was calculated using the Cockcroft-Gault formula. ResultsMean inter-individual variability expressed as overall coefficient of variation (CV%) values was lower at C-peak (CV% = 49) than at C-trough (CV% = 68). Mean CV% intra-individual variability was 26.5. No significant correlation was found between edoxaban plasma levels and CrCl (C-trough r/r2 = −0.007/0.000; C-peak r/r2 = 0.129/0.017). Correlations (r/r2), at C-trough and C-peak, between edoxaban levels and PT and aPTT, were 0.386/0.149–0.922/0.851 and 0.283/0.080–0.567/0.321, respectively. Significant discrepancies between PT or aPTT and edoxaban levels were found. ConclusionsThis study confirms also for edoxaban a high inter-individual variability in NVAF patients. PT and aPTT are not useful to measure this drug. As for the other two anti-FXa drugs, the absence of a significant correlation between CrCl and edoxaban plasma levels was observed.

Ankle and Foot Ultrasound: Reliability of Side-to-Side Comparison of Small Anatomic Structures.

In sonography of clinically relevant small structures of the ankle and foot, the healthy contralateral side can be used as a reference to identify subtle abnormalities. Intrasubject side-to-side variability must be minimal. The aim of this study was to assess the reliability of side-to-side sonographic evaluation of small structures of the ankle and foot. Thirty healthy volunteers were prospectively studied. Small structures of the ankle and foot were evaluated bilaterally by 2 musculoskeletal radiologists in separate sessions. The deep peroneal nerve, superior extensor retinacula, calcaneofibular ligament, superior peroneal retinacula, tibialis posterior tendon, tibial nerve, Achilles tendon, plantaris tendon, plantar fascia, and sural nerve were considered. To assess intra- and interreader agreements, 30 (100%) examinations were repeated. A nonparametric statistic was used. Data were not normally distributed (P > .001). Intrareader agreement was k = 0.67 (95% confidence interval, 0.57-0.78) and interreader agreement was k = 0.73 (95% confidence interval, 0.68-0.77). The mean values and standard deviation for all the structures were 0.36 ± 1.85 mm. The overall coefficient of variation was 18.5%. The intraclass correlation coefficient was 0.93 (95% confidence interval, 0.92-0.94). In ankle and foot sonography, the healthy contralateral side can be used as a reference during a real-time musculoskeletal ultrasound evaluation of small structures.

Study on Sample Size of Small Batch Precast Concrete Components

In the sampling test, in the absence of actual data of the eigenvalues, combined with the actual conditions of the project, the total coefficient of variation under various distribution types can be used to estimate the sample size required for sampling. The article studies the sampling inspection of the strength of small batches of precast concrete components, and obtains the overall coefficient of variation under the normal distribution type, and then it can calculate the sample size required for different total amount of corresponding sampling inspection.

Site variability analysis using cone penetration test data

This paper presents a comprehensive methodology for quantification of site variability in a way that can be used in geotechnical practice. Site variability is separated into horizontal and vertical variability. To quantify vertical variability in a CPT sounding, a vertical variability index is proposed based on the complexity of the soil profile, the overall coefficient of variation for the depth range of interest, and intra-layer variability measures. To quantify horizontal site variability, a horizontal variability index is proposed based on the similarity of soundings performed at the same site. The method is illustrated using CPT data from five sites.

Soil Particle Size Composition and Differences of Different Grassland Types in the Southern Slope of Qilian Mountain

In this paper, we collected soil samples of different grassland types in the southern slope of Qilian Mountain in Qinghai province and analyzed the soil particle size composition and differences. The research result shows that: The soil particle size composition of different grassland types is obviously different, and the soil texture is in silt-sandy soil level. The soil texture from fine to coarse of each grassland is: temperate steppe> alpine meadow> alpine steppe> degenerated grassland> swamp meadow; the overall coefficient of variation(CV) of soil particle size content in different grassland types shows a large difference, the variation of soil silt content in each grassland type was small, while the content of soil sand and clay content fluctuate greatly; the variation degree of soil sand content in each grassland type is moderately variable, but the content of silt and clay is moderately weak, the change rule is sand> clay> silt.

Interlaboratory proficiency processing scheme in CSF aliquoting: implementation and assessment based on biomarkers of Alzheimer\u2019s disease

BackgroundIn this study, we tested to which extent possible between-center differences in standardized operating procedures (SOPs) for biobanking of cerebrospinal fluid (CSF) samples influence the homogeneity of the resulting aliquots and, consequently, the concentrations of the centrally analyzed selected Alzheimer’s disease biomarkers.MethodsProficiency processing samples (PPSs), prepared by pooling of four individual CSF samples, were sent to 10 participating centers, which were asked to perform aliquoting of the PPSs into two secondary aliquots (SAs) under their local SOPs. The resulting SAs were shipped to the central laboratory, where the concentrations of amyloid beta (Aβ) 1–42, pTau181, and albumin were measured in one run with validated routine analytical methods. Total variability of the concentrations, and its within-center and between-center components, were analyzed with hierarchical regression models.ResultsWe observed neglectable variability in the concentrations of pTau181 and albumin across the centers and the aliquots. In contrast, the variability of the Aβ1–42 concentrations was much larger (overall coefficient of variation 31%), with 28% of the between-laboratory component and 10% of the within-laboratory (i.e., between-aliquot) component. We identified duration of the preparation of the aliquots and the centrifugation force as two potential confounders influencing within-center variability and biomarker concentrations, respectively.ConclusionsProficiency processing schemes provide objective evidence for the most critical preanalytical variables. Standardization of these variables may significantly enhance the quality of the collected biospecimens. Studies utilizing retrospective samples collected under different local SOPs need to consider such differences in the statistical evaluations of the data.

Cross-validation Studies of a Novel Low-cost Hepatitis B Virus Quantitative Polymerase Chain Reaction System.

AimThis research focused on the results of the cross-validation program related with the performance of a Cuban novel low-cost real-time quantitative polymerase chain reaction (qPCR) assay for hepatitis B virus (HBV) quantification developed by the Therapeutic Vaccine against Hepatitis B Department, Vaccines Division, Center for Genetic Engineering and Biotechnology (CIGB), Havana, Cuba.Materials and methodsDilution series with the plasmid standard at concentrations of 900,000 to 0.09 copies/reaction (c/r) were made for each PCR instrument. The mean cycles threshold (Ct) values and PCR efficiency were compared among the cyclers. Hepatitis B virus-positive serum samples were used for the calculation of reproducibility of the HBV assay. Biotecon Diagnostics (BCD) also ordered the oligo sequences from a second supplier and compared the PCR performance to those provided from the CIGB.ResultsAll PCR cyclers were able to detect concentrations up to 0.09 c/r. However, below the concentration of 9 c/r, the variation of results increased within and between the cyclers. The PCR efficiency showed satisfying results. The overall coefficient of variation (CV) cycler values were 1.29 and 0.91% for M6 and M19 respectively. No significance was observed between the different primer suppliers.ConclusionThe HBV assay was performed with a good concordance between the five real-time instruments from different suppliers. The HBV assay was also performed with a high reproducibility for samples with a high and a low viral load. The HBV assay is robust against different primer suppliers.How to cite this article: Aguiar J, Silva JA, García G, Guillén G, Aguilar JC. Cross-validation Studies of a Novel Low-cost Hepatitis B Virus Quantitative Polymerase Chain Reaction System. Euroasian J Hepato-Gastroenterol 2018;8(1):38-41.