Search

Background: Digital pathology systems (DPS) are emerging as capable technologies for clinical practice. Studies have analyzed pathologists' diagnostic concordance by comparing reviews of whole slide images (WSIs) to glass slides (e.g., accuracy). This observational study evaluated the reproducibility of pathologists' diagnostic reviews using the Aperio GT 450 DX under slightly different conditions (precision). Method: Diagnostic precision was tested in three conditions: intra-system (within systems), inter-system/site (between systems/sites), and intra- and inter-pathologist (within and between pathologists). A total of five study/reading pathologists (one pathologist each for intra-system, inter-system/site, and three for intra-pathologist/inter-pathologist analyses) were assigned to the respective sub-studies.A panel of 69 glass slides with 23 unique histological features was used to evaluate the WSI system's precision. Each glass slide was scanned to generate a unique WSI. From each WSI, the field of view (FOV) was generated (at least 2 FOVs/WSI), which included the selected features (1–3 features/FOV). Each pathologist reviewed the digital slides and identified which morphological features, if any, were present in each defined FOV. To minimize recall bias, an additional 12 wild card slides from different organ types were used for which FOVs were extracted. The pathologists also read these wild card slides FOVs; however, the corresponding feature identification was not included in the final data analysis. Results: Each measured endpoint met the pre-defined acceptance criteria of the lower bound of the 95% confidence interval (CI) overall agreement (OA) rate being ≥85% for each sub-study. The lower bound of the 95% CI for the intra-system OA rate was 95.8%; for inter-system analysis, it was 94.9%; for intra-pathologist analysis, 92.4%, whereas for inter-pathologist analyses, the lower bound of the 95% CI of the OA was 90.6%. Conclusion: The study results indicate that pathologists using the Aperio GT 450 DX WSI system can precisely identify histological features that may be required for accurately diagnosing anatomic pathology cases.

Hundreds of molecular species make up the cellular lipidome. In this minireview, considerations for interpreting membrane and storage lipid profile changes that are often the focal point of lipidomic studies are discussed. In addition, insights how the most conserved molecular patterns are formed in eukaryotic systems and the consequences for the perturbation of lipid homeostasis are addressed. The implications of lipid identification specificity and experimental variability on modeling membrane structure and systemic responses are also discussed. The profile changes of membrane and storage lipids are bound to the kinetics of the metabolic system, and experimental design and functional interpretation in lipidomic research should be adapted accordingly. [ABSTRACT FROM AUTHOR]

NanoSIMS has been widely used for in-situ sulfur isotopic analysis (32S and 34S) of micron-sized grains or complex zoning in sulfide in terrestrial and extraterrestrial samples. However, the conventional spot mode analysis is restricted by depth effects at the spatial resolution < 0.5–1 μm. Thus sufficient signal amount cannot be achieved due to limited analytical depths, resulting in low analytical precision (1.5‰). Here we report a new method that simultaneously improves spatial resolution and precision of sulfur isotopic analysis based on the NanoSIMS imaging mode. This method uses a long acquisition time (e.g., 3 h) for each analytical area to obtain sufficient signal amount, rastered with the Cs+ primary beam of ∼100 nm in diameter. Due to the high acquisition time, primary ion beam (FCP) intensity drifting and quasi-simultaneous arrival (QSA) significantly affects the sulfur isotopic measurement of secondary ion images. Therefore, the interpolation correction was used to eliminate the effect of FCP intensity variation, and the coefficients for the QSA correction were determined with sulfide isotopic standards. Then, the sulfur isotopic composition was acquired by the segmentation and calculation of the calibrated isotopic images. The optimal spatial resolution of ∼ 100 nm (Sampling volume of 5 nm × 1.5 μm2) for sulfur isotopic analysis can be implemented with an analytical precision of ∼1‰ (1SD). Our study demonstrates that imaging analysis is superior to spot-mode analysis in irregular analytical areas where relatively high spatial resolution and precision are required and may be widely applied to other isotopic analyses.

This paper discussed the analytical precision on equations of motion in some practical studies that use 2-D DDA, 2D-Coupled analysis of NMM & DDA, and 3D-DDA. We point out the main reason for numerical instability in DDA is loss of the effective digits when superposing the global stiffness matrix under the variable conditions of large and the small blocks. Categories of analyses are distributed in 2D-DDA static masonry structures such as the Great Pyramid and the Pont du Gard, 2D-DDA dynamic rock fall problems and the sensitivity of its analysis on the velocity ratio and the penalty, earthquake response analysis of rock slopes, 2D-NMM, 2D-coupled analysis of DDA and NMM and 3D-DDA rock fall problem. The selected examples on the Great Pyramid, Pont du Gard and Bayon Temple at Angkor Thom are located in Egypt, France and Cambodia respectively as UNESCO world heritages sites. The authors evaluated the applicability of the methods and the reliability of the results by comparing different methods and site observations from the practical problems. [ABSTRACT FROM AUTHOR]

This paper presents a methodological framework for inter-instrument comparison of different particle-size analysers. The framework consists of: (i) quantifying the difference between complete particle-size distributions; (ii) identifying the best regression model for homogenizing data sets of particle-size distributions measured by different instruments; (iii) quantifying the precision of a range of particle-size analysers; and (iv) identifying the most appropriate instrument for analysing a given set of samples. The log-ratio transform is applied to particle-size distributions throughout this study to avoid the pitfalls of analysing percentage-frequency data in 'closed-space'. A Normalized Distance statistic is used to quantify the difference between particle-size distributions and assess the performance of log-ratio regression models. Forty-six different regression models are applied to sediment samples measured by both sieve-pipette and laser analysis. Interactive quadratic regression models offer the best means of homogenizing data sets of particle-size distributions measured by different instruments into a comparable format. However, quadratic interactive log-ratio regression models require a large number of training samples ( n > 80) to achieve optimal performance compared to linear regression models ( n = 50). The precision of ten particle-size analysis instruments was assessed using a data set of ten replicate measurements made of four previously published silty sediment samples. Instrument precision is quantified as the median Normalized Difference measured between the ten replicate measurements made for each sediment sample. The Differentiation Power statistic is introduced to assess the ability of each instrument to detect differences between the four sediment samples. Differentiation Power scores show that instruments based on laser diffraction principles are able to differentiate most effectively between the samples of silty sediment at a 95% confidence level. Instruments applying the principles of sedimentation offer the next most precise approach. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To evaluate the effect of general anesthesia on plasma cTnI concentrations in horses. Animals, materials and methods: Thirty-two horses undergoing general anesthesia and either elective surgery or MRI without surgery were prospectively studied. Twenty-nine horses (22 surgical, 7 imaging) completed the study. Plasma cTnI concentrations were determined prior to anesthesia and at 6, 12 and 24 h following discontinuation of the inhalant anesthetic. Results: All horses had cTnI values within the reference range at all time points. Six horses (21%) developed detectable cTnI 6 or 12 h following anesthesia. Risk factors for detectable cTnI include increasing age and dorsal recumbency. Horses with detectable cTnI had significantly lower mean and diastolic arterial blood pressures than those without detectable cTnI. Conclusion: Uncomplicated general anesthesia with or without surgery does not result in cardiac troponin I elevations above the reference range in the first 24 h postoperatively. [Copyright &y& Elsevier]

Abstract: To assess the analytical accuracies and precisions of archaeometric elemental analyses by different techniques, a relatively homogeneous material such as obsidian must be studied. An assessment of published elemental concentration data from two Anatolian obsidian sources shows that while in most cases analytical accuracy is as high as is commonly expected, in some cases it is not. It also shows that the dispersions of elemental concentration data (indicators of analytical precisions) coming from modern analytical procedures are akin to the estimated homogeneity of the obsidian. Based on this latter observation, if one has element dispersion data from a single analytical technique, with a single source of obsidian as a control, data sets that contain multiple, but similar sources of obsidian may be differentiated. [Copyright &y& Elsevier]

Bacteria holding-time experiments of up to 62 h were performed on five surface-water samples from four urban stream sites in the vicinity of Atlanta, GA, USA that had relatively high densities of coliform bacteria ( Escherichia coli densities were all well above the US Environmental Protection Agency criterion of 126 colonies (100 ml) − 1 for recreational waters). Holding-time experiments were done for fecal coliform using the membrane filtration modified fecal coliform (mFC) agar method and for total coliform and E. coli using the Colilert®-18 Quanti-Tray® method. The precisions of these analytical methods were quantified. Precisions determined for fecal coliform indicated that the upper bound of the ideal range of counts could reasonably be extended upward and would improve precision. For the Colilert®-18 method, analytical precisions were similar to the theoretical precisions for this method. Fecal and total coliform densities did not change significantly with holding times up to about 27 h. Limited information indicated that fecal coliform densities might be stable for holding times of up to 62 h, whereas total coliform densities might not be stable for holding times greater than about 27 h. E. coli densities were stable for holding times of up to 18 h—a shorter period than indicated from a previous studies. These results should be applicable to non-regulatory monitoring sampling designs for similar urban surface-water sample types. [ABSTRACT FROM AUTHOR]

Background: Cardiac troponins currently represent the preferred biomarkers for the detection of myocardial necrosis. The objective of the present study was to compare the performance of the Access® AccuTnI® assay (Beckman Coulter) measured on two different platforms, the UniCel® DxI 800 and the Access® 2 (Beckman Coulter). In particular, the serum cardiac troponin I (cTnI) concentration corresponding to 10% coefficient of variation (CV), the cTnI assay minimum detectable concentration (MDC), and the serum cTnI 99th percentile in healthy subjects were calculated. Methods: The Access® AccuTnI® is a paramagnetic particle chemiluminescent immunoassay. Imprecision profiles were determined according to the Clinical and Laboratory Standards Institute EP5-A protocol using serum pools. The MDC was calculated as mean+3 SD of 20 determinations of the zero calibrator during one run. The 99th percentile was determined analyzing serum samples from 679 healthy blood donors (523 males, 156 females; 18–71 years old). Results: cTnI concentrations are given in μg/L. 10% CV values (95% confidence interval, CI) were 0.0577 (0.0467–0.0750) (UniCel® DxI 800) and 0.0486 (0.0255–0.0596) (Access® 2). MDC values were 0.011 (UniCel® DxI 800) and 0.012 (Access® 2). The 99th percentile (95% CI) value was 0.0340 (0.0298–0.0410). Conclusions: Our data confirm the reliability of the evaluated cTnI assay and demonstrate the comparability of the cTnI values between the platforms studied. Clin Chem Lab Med 2009;47:367–71. [ABSTRACT FROM AUTHOR]

Microscopic melt inclusions found in magmatic minerals are undoubtedly one of the most important sources of information on the chemical composition of melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laser ablation (LA) - inductively coupled plasma-mass spectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) in individual melt inclusions hosted in quartz from the Mount Pinatubo dacites, Philippines. The determined elements cover a concentration range of five orders of magnitude. Femtosecond LA-ICP-MS analyses of twenty-eight individual melt inclusions demonstrate the efficiency of the microanalytical technique and suggests a spectacular homogeneity of the entrapped melt, at least with respect to the following incompatible trace elements: Rb, Sr, Nb, Cs, Ba, La, Ce, Pr, Nd, Pb, Th. The analytical precision (1s) for Na, Ca, Rb, Sr, Y, Nb, Ba and LREE ranged from 3 to 20%. Comparison of trace element concentrations in Mt. Pinatubo melt inclusions determined by femtosecond LA-ICP-MS with those of melt inclusions previously analysed by secondary ion mass spectrometry analysis (SIMS) and those of matrix glasses previously determined by nanosecond LA-ICP-MS showed an agreement typically within 30–40%. The homogeneity of trace element concentrations of the Mt. Pinatubo melt inclusions and the matrix glasses is consistent with the melt inclusion origin as homogeneous rhyolitic melt that was trapped in quartz phenocrysts at the final crystallisation stages of the host adakite (dacite) magma. [ABSTRACT FROM AUTHOR]

Nutrition labels guide consumers in making their food choice. New requirements for mandatory nutrition labelling have been in force in Australia since late 2002. The present study, analysing 350 samples comprising 70 different products for nutritional compounds declared on the label, is the first larger attempt to quantify the precision in nutrition labelling of food products on the Australian market. A significant discrepancy between actual and declared values was detected with an average variation in precision of -13% to +61% for individual nutritional components. There is no tolerance limit established in the Australian food legislation but a ± 20% discrepancy is allowed in some countries and others have separate upper and lower limits and allow a maximum discrepancy of -20% for beneficial nutritional compounds and +20% for unfavourable compounds. Only 16% of the 70 products in the study would fully comply should a leeway of ±20% be introduced for any nutritional compound on the label. With separate upper and lower limits, 51% of products would fully comply. Compliance improved to 27% and 70% of products, respectively, when excluding variations in minor amounts irrelevant to consumers (counting all variations of less than 1g/100g, or 10kJ/100g for energy and 10mg/100g for sodium, potassium, calcium and cholesterol, as compliant). It is proposed that adoption of an upper and lower tolerance limit, excluding minor amounts, be considered as a way of better assisting the consumer in making relevant comparisons of product nutritional value and that any nutritional component should comply with the limit for the product to comply. Applying such a limit, 30% of products in the survey would not be compliant. [ABSTRACT FROM AUTHOR]

Metabolic serotypes sensitive to caloric intake may enable sera metabolomic profiles to validate epidemiological parameters and predict disease risk in humans. This long-range goal is complicated by the lack of known state markers and the requirement for simultaneous monitoring of multiple small changes. Therefore, analytical precision for appropriate high data density studies using HPLC separations coupled with coulometric array detectors was evaluated over a two month period in pooled rat sera samples (previously collected and stored at −80 °C), and in authentic biochemical standards. In sera, mean coefficients of variation (CV) of retention time and ratio accuracy within the established metabolic serotype varied within ±1% and ±3%, respectively. In sets of purified standards, the same parameters fluctuated, correspondently, in ranges of ±0.1% and ±1%. Median CV of the metabolite concentrations were ~13% in standards and ~11-19% in sera, and varied non-monotonically with the analytical system status and experimental design. These parameters were shown to be sufficiently controlled so as not to dominate intra-group biological variability in serum metabolomics studies. Continuation of experimental runs across an analytical breakpoint (column replacement) was associated with disproportionate changes in metabolite concentrations, independent of maintained analytical precision. These changes were sufficient to shift overall profile localization in megavariate projection analyses. We developed a mathematical approach to normalize this break and use partial least squares projection to latent structure discriminant analysis to confirm validity of this normalization approach. This generally applicable mathematical correction helps enable longer term high data density studies by removing a critical source of systemic variation. [ABSTRACT FROM AUTHOR]