Difference Plots Research Articles

7938 Validation of Inflammatory Cytokine Multiplex Array With Variations in Target Panel

Abstract Disclosure: W.M. Sanders: None. C.A. Karvonen-Gutierrez: None. D.S. McConnell: None. Background: Multiplex arrays are an invaluable tool for conducting large-scale biomarker research as they provide a high-throughput, cost-effective method for quantifying a panel of endocrine markers. However, the shared reaction environment between antibodies of differing reactivities creates the potential for inducing a technical difference in the assay methods due to any variation in panel selection. Methods: We evaluated the R&D Systems Luminex HS Cytokine Panel A (Catalog # FCSTM09) for systematic differences when measuring a “panel” of IL-1β, TNF-α, and IL-10 vs. measuring “IL-10 only.” We selected 72 serum samples and assayed them in singleton 4 times: 2 separate “panel” batches, and 2 separate “IL-10 only” batches. Differences in log-transformed IL-10 results for sample replicates within and between the “panel” and “IL-10 only” batches were assessed for significance with paired t-tests (α=.01). We also assessed the differences graphically with Bland-Altman plots of differences and absolute percent differences.All batches included control materials from R&D Systems and internal lab serum pools (male and female). To retroactively assess the test batches, we graphically compared their quality control results to those of the subsequent, larger assay project we were piloting. Results: The “IL-10 only” assay yielded an average result of .879 pg/mL (SD .57) on batch 1 and .712 pg/mL (SD .58) on batch 2, with an average paired sample difference of .167 pg/mL, and an average absolute percent difference of 28.8%. The “panel” assay produced an average IL-10 result of .645 pg/mL (SD .50) on batch 1 and .720 pg/mL (SD .52) on batch 2, with an average paired sample difference of .075 pg/mL, and an average absolute percent difference of 15.5%. Comparing pooled IL-10 results from the “IL-10 only” batches with the “panel” batches, there was an average paired difference of .113 pg/mL and absolute percent difference of 16.2%. Paired t-testing of log-transformed results for within “panel,” within “IL-10 only,” and between pooled results from the two methods demonstrated that each had significant differences (p<.0001). The Bland-Altman plots further revealed that these differences were ubiquitously large for samples with low concentrations of IL-10.Test batch quality control results were consistent with those in the primary assay project. The serum pool QCs exhibited significant inter-assay variation – the male pool average result was .41 pg/mL (SD .10) vs. .359 in the test batches, and the female pool average was .57 pg/mL (SD .10) vs. .548 in the test batches. Conclusion: The multiplex assay had considerable inter-assay variation at low concentrations of IL-10, and low results were prevalent. Due to this, we determined that any methodological differences between the “panel” and “IL-10 only” methods were undetectable compared to ambient variation, and irrelevant given the sample characteristics. Presentation: 6/3/2024

B-112 Regression Analysis Techniques for Assessing Calibration Reproducibility Within and Between Instruments. A Practical Example with Blood Ca²⁺ Assayed with Two cobas® b 221Analyzers

Abstract Background Reproducibility of the calibration curve within the analytical measurement range (AMR) is crucial for ensuring reliable patient values within and between laboratory instruments to detect shifts and trends of clinical significance. In this practical example for ionized calcium (Ca²⁺) assayed with two cobas b221® instruments, the equality of calibration lines and the verification with patient specimen comparison study was assessed with regression analysis techniques. Methods Instruments: Two cobas b 221 (Roche Diagnostics). Calibration material: COOX/MSS™ (Five levels, Roche Diagnostics). This was independently assayed either three or five times in parallel with both instruments. The patient specimens were obtained by venipuncture in Na/Li-heparin BD™ tubes (Becton-Dickinson). Upon receipt, specimens were assayed with both instruments within two minutes. The data were transferred to Minitab® (Version 21, Minitab Inc) statistical software and analyzed with polynomial ordinary least squares (POLS), orthogonal and locally weighted scatterplot smoother (lowess) regression analysis models. The aptness of the model was assessed with standardized residuals (std. res.) diagnostics. For acceptable total error the CLIA’s criterion target value ± 10% was adopted. Results While the POLS model did not show probabilistically significant differences between instruments (P=0.8), it showed probabilistically significant differences between years (P=0.003). However, this was due to a small MSE (= 0.003 mg/dL), which is not clinically significant. The test for linearity showed probabilistically significant lack-of-fit (P<0.0001) due to a small MS pure error (<0.0001 mg/dL). The lowess for the standardized deleted residuals by the fitted value showed a quasi-linear relationship. The multiple comparisons (P=0.3) and the Levene’s (P=0.4) tests did not detect probabilistically significant heteroscedasticity of the variance by reference value. The plot of the std. res. by the leverage showed two possible outliers (std. res.>|3|) and no influential observations (Hi<0.5). These diagnostics proved the aptness of the POLS model. The harmonization between the two instruments was verified with patient specimens. The orthogonal regression model showed in the interval 3-6 mg/dL a quasi-linear relationship between the values as obtained with the two instruments. The orthogonal regression line (y=0.1+1.02 n) and the OLS regression line (y=0.03+601 n) were very similar. There was no probabilistically significant lack-of-fit (P=0.5). The plot of the std. res. by the leverage showed one possible outlier (std.res.>|3|) and no influential observations. Additionally, the plot of the relative differences between the values as obtained with b221#9371 and b221#24796 by the values as obtained with b221#9371 showed only one value exceeding half of the total allowable error. Conclusions The POLS model clearly showed that the calibration lines for the two instruments were quasi-linear in the interval 2-10 mg/dL and reproducible within and between instruments. Additionally, this reliable performance was verified with patient specimens in the interval 3-6 mg/dL. The differences between values as obtained with each instrument were within half of the CLIA’s total allowable error. This clearly showed that equality of calibration lines ensured interchangeable patient values between instruments. Finally, electronic transfer of data and the availability of statistical software like Minitab was crucial for conducting this study.

A-045 Analytical and Clinical Evaluation of A1c Test by HPLC - Lifotronic™ H100Plus Analyzer - in a Brazilian Clinical Laboratory

Abstract Background Over the years, the measurement of Glycated Hemoglobin (A1c) has solidified as an important risk marker for pre-diabetic patients and for the diagnosis and control of diabetic patients. The High-Performance Liquid Chromatography (CLAE) method has been adopted in prospective studies such as the DDCT, and international certification by the NGSP is available. In this study, analytical performance metrics including imprecision, correlation, linearity, carryover, and detection of hemoglobin variants were evaluated for the Lifotronic® H100 Plus analyzer from China. Methods The results were evaluated following CLSI guidelines on samples within stability, collected according to standardized procedures. For the comparative method, 40 patient samples ranging from 4 to 15.4% were analyzed, and two concentrations of internal quality control material were used for intra-assay (5 repetitions per day) and inter-assay (over five days) imprecision testing. Linearity was assessed using samples at two concentrations, one low (4.5%) and another high (17.2%). For carryover evaluation, low (4.98%), intermediate (9.97%), and high (14.96%) concentrations were assayed in an interleaved manner. Hemoglobin variants found in the studied population were determined using the same method employed in correlation tests (HbS, HbF, HbC, HbE, and HbD). Results The method comparison study revealed a Total Error for decision levels of 5.6%: 2.23% and 6.5%: 1.70%, which were lower than the maximum allowable Total Error of 3.3% (EFLM - EuBIVAS). The difference plot showed that 95% of the results fell within acceptable limits. Positive bias was observed in 7 out of 40 tested samples, predominantly in samples with concentrations above 6,5%, although the medical team assessed it as having no clinical impact. For intra-assay imprecision, the obtained result was 0.86%, and for inter-assay imprecision, it was 0.87%, both deemed acceptable according to the 3.0 % specification proposed by the supplier for the two tested levels.Linearity tests were approved for concentrations proposed by the manufacturer between 3 and 18%, and no carryover was found between samples. All hemoglobin variants previously detected in the comparative method were also identified in the test method without exception, although the specific type of Hb variant was not identified. Conclusions The Lifotronic™ H100Plus analyzer demonstrated approved analytical performance with some notable observations: positive bias was observed in samples with concentrations above 6,5%, though it was not considered clinically relevant, the throughput of 58 tests per hour could be a limitation for laboratories with high testing volumes and the analyzer detected the presence of Hb variants, although it did not identify their specific types.

A-116 Pleural Fluid pH - Are We Collecting and Measuring It Correctly?

Abstract Background Pleural fluid pH has diagnostic, therapeutic, and prognostic implications in the management of pleural space infections and malignancy. Pleural fluid sample collection, transportation and processing are known for source of pre-analytical error which contribute to inaccuracy of measured pH with clinical implication to patient care. Some clinical practices observed locally include pleural fluid collection in sterile container for ease of other biochemistry analytes measurement in addition to pH. This study aimed to compare the differences in pleural fluid pH and other commonly ordered biochemistry analytes collected using sterile container against heparinized blood gas syringe. Methods Total 20 Pleural fluid samples were collected from patient using a procedure called thoracentesis from, with approximately 2 to 3ml of fluid directly transferred into heparinized blood gas syringe as well as in a sterile container. Both samples were then transported to Clinical Biochemistry Laboratory within an hour. Both samples were analyzed on 3 analytical systems; 1) pH on Roche COBAS b221 blood gas analyzer, 2) Glucose, Total Protein, LDH on Beckman AU System and 3) Specific Gravity on Reflectometer. Statistical analysis was performed using Analyze-It software. Results pH fluid collected in sterile container demonstrates significant high bias (absolute of 0.4 units or 5%) as compared to sample collected in heparinizes blood gas syringe. Other commonly ordered tests in fluid profile (Glucose, Total Protein, LDH and SG) demonstrate good correlation (Altman-Bland Difference Plot <5%) for pleural fluid collected in sterile container as compared to heparinized syringe. Conclusions This positive bias observed is likely attributed to air exposure in pleural fluid collection in sterile container as compared to heparinized syringe. The accuracy of measured pleural pH is critically dependent on the method of sample collection. This study highlights the need for a standardized protocol for pleural pH collection for accurate measurement.

A-323 Advancing Point-of-Care Testing: Independent Evaluation of the Truvian Platform

Abstract Background To address the deficiencies of long turnaround time, increased cost and delayed medical intervention in the current paradigm of routine blood testing, Truvian has developed an automated blood testing platform that provides timely and lab-accurate results at the point of care. With 300 µL from a single Lithium Heparin blood sample, the Truvian solution generates 34 test results, including CMP, Lipid, HbA1c, TSH and CBC in under 30 minutes (TruWellness PanelTM).The present study focused on rigorous evaluation of the reliability and accuracy of Truvian's platform in a real-world clinical setting by untrained operators. Platform precision was measured over time on multiple Truvian instruments under standardized protocol. Accuracy and reliability were assessed independently at the UC San Diego Anti-Viral Research Center (AVRC) by testing samples from donors with chronic medical conditions and comparing against FDA cleared devices, Roche Cobas and Sysmex-XN. Methods Precision was assessed using the control workflow where three commercially available controls, were loaded as sample inputs into the Truvian consumables to perform the TruWellness Panel(TM). Three levels of controls were run in quadruplicate daily on 4 instruments (N > 100 per instrument). Within and between run, day, instrument, and consumable lot variance components were assessed.Accuracy was assessed as part of an IRB-approved method comparison study at AVRC by untrained operators. A total of 50 unique donors representing various disease states were consented and enrolled. Three 4-mL blood samples were collected from each donor: one Lithium Heparin (LiHep) sample for the Truvian System's TruWellness PanelTM, another LiHep gel tube for Roche Cobas clinical chemistry and TSH assays, and an EDTA sample for the Sysmex complete blood count with 3-part differential and HbA1c. All samples were tested on the Truvian System within an hour of collection or processed for central lab testing. Concordance to comparator devices was assessed via relative difference plots, Passing-Bablok and/or Deming regression analyses. Results Our results indicated that the performance of Truvian's instrument met pre-specified reliability, precision and accuracy criteria (per preliminary analysis of the first 50 patients). Reproducibility results showed 100% (69/69) of all tests met specifications. Interim analysis of the first 50 patients in the method comparison study indicates a robust concordance with predicate devices with 20 out of 23 tests showing a correlation coefficient of ≥ 0.9. During donor testing, the instrument demonstrated 96% (48/50) run reliability with only a single operator-induced error where the blood tube was not loaded correctly, highlighting the robustness and ease of use of the platform. Conclusions The present evaluation underscores Truvian's instrument as an easy-to-operate platform that can be run by untrained operators, maintain reliability in real-world clinical settings, and deliver accurate and precise results. Enrollment and sample testing are ongoing, with plans to expand the sample size to 200 donors and study completion planned for May 2024. Broadening the study to encompass a wider range of analyte measurements among chronic disease patients is expected to enhance performance data. This independent evaluation provided confidence in Truvian Platform’s performance and suitability for practical healthcare applications.

Cross validation of pharmacokinetic bioanalytical methods: Experimental and statistical design

Pharmacokinetic (PK) analysis is an integral part of drug development. Health agency guidance provides development and validation recommendations for PK bioanalytical methods run in one laboratory. However, as a drug development program progresses, a PK bioanalytical method may need to be run in more than one laboratory. Additionally, a PK bioanalytical method format may change and a new method platform may be validated and implemented during the drug development cycle. Here we describe the cross validation strategy for comparisons of two validated bioanalytical methods used to generate PK data within the same study or across different studies. Current guidance for cross validations is limited and, therefore, Genentech, Inc. has developed a cross validation experimental strategy that utilizes incurred samples along with a comprehensive statistical analysis. One hundred incurred study samples over the applicable range of concentrations are selected based on four quartiles (Q) of in-study concentration levels. The samples are assayed once in the two bioanalytical methods. Bioanalytical method equivalency is assessed for the 100 samples based on pre-specified acceptability criterion: the two methods are considered equivalent if the percent differences in the lower and upper bound limits of the 90 % confidence interval (CI) are both within ±30 %. Quartile by concentration analysis using the same criterion may also need to be performed. A Bland-Altman plot of the percent difference of sample concentrations versus the mean concentration of each sample is also created to help further characterize the data. This strategy is a robust assessment of PK bioanalytical method equivalency and includes subgroup analyses by concentration to assess for biases. This strategy was implemented in two case studies: 1) two different laboratories using the same bioanalytical method and 2) a bioanalytical method platform change from enzyme-linked immunosorbent assay (ELISA) to multiplexing immunoaffinity (IA) liquid chromatography tandem mass spectrometry (IA LC-MS/MS).

Identification and Characterization of Key Genes Associated with Amelogenesis

Abstract Objectives The identification of key genes associated with amelogenesis would be helpful in finding solutions to genetic disorders in oral biology. The study aimed to use in silico analysis to identify the key genes involved in tooth development associated with preameloblasts (PABs) and secretory ameloblasts (SABs). Material and Methods The data was subjected to quality analysis and uniform manifold approximation and projection analysis. To examine the distribution of the genes and identify important upregulated loci, a p-value histogram, a quantile plot, a mean difference and mean-variance plot, and a volcano plot were generated. Finally, protein-protein interaction and gene enrichment analyses were performed to determine the ontology, relevant biological processes, and molecular functions of selected genes. Results A total of 157 genes were found to be significant in the PAB versus SAB comparison. HIST1H31 revealed strong interaction with HIST1H2BM, and EXO1, ASPM, SPC25, and TTK showed strong interactions with one other. The STRING database revealed that NCAPG, CENPU, NUSAP1, HIST1H2BM, and HIST1H31 are involved in biological processes. NCAPG, CENPU, SPC25, ETV5, TTK, ETV1, FAM9A, NUSAP1, HIST1H2BM, and HIST1H31 are involved in cellular components. Conclusion The TTK, NUSAP1, CENPU, NCAPG, FAM9A, ASPM, SPC25, and HIST1H31 genes demonstrate functions in cell division. These genes might play a role in ameloblast development. These results will be useful in developing new methods to stimulate ameloblast development, which is essential for tooth regeneration and tissue engineering. However, more research is required to validate the functions of these genes and the genes with which they interact. A wide variety of genetic, epigenetic, and exogenous signaling factors regulate these genes and pathways throughout development and differentiation, cell fate, and behavior.

Comparative study of erythrocyte sedimentation rate measurement between Celltac Alpha+ (MEK-1305) ESR Analyzer and standard Westergren method

Background: The Westergren method, a gold standard method for erythrocyte sedimentation rate (ESR) measurement, is one of the screening tests for routine clinical hematology that can be used as an inflammation marker. Since the results can be altered by numerous factors, new methodologies have been established to manage the possible pitfalls. Objective: This study compared erythrocyte sedimentation rate measurements obtained by the Celltac Alpha+ (MEK-1305) Automated Hematology and ESR analyzer with those obtained by the standard Westergren method. Materials and methods: The Celltac Alpha+ (MEK-1305) Automated Hematology and ESR analyzer was used to assess the performance of ESR measurement compared to the standard Westergren method. A total of 220 random EDTA whole blood samples from patients were included and analyzed in parallel using the automated analyzer and the standard Westergren method. Results: Spearman’s rank correlation coefficient (ρ = 0.916) obtained a good correlation between the two methods. In addition, the precision was good and acceptable according to the criteria, with a %CV of less than 10% in both intra-run and inter-run precision. There was no contamination between blood samples from using a single capillary probe. Moreover, Bland-Altman mean difference plot also indicated a good agreement, with a mean bias of -1.4 (95% CI: -0.8 to 2.1), an upper LOA of 7.6 (95% CI: 6.6 to 8.7) and a lower LOA = -10.5 (95% CI: -11.6 to -9.5). Conclusion: This comparative study indicated that the Celltac Alpha+ (MEK-1305) Automated Hematology and ESR analyzer is applicable within clinical routine practice along with proper measurement regulation. Even though the principles between these two methods are completely different, an acceptable interrelation was obtained due to the calibration process by Nihon Kohden corporation.

A veterinary-calibrated point-of-care glucometer accurately measures blood glucose concentration in dogs and cats.

To determine the clinical and analytical accuracy of a new veterinary-calibrated portable blood glucose monitor (PBGM) compared to a reference laboratory analyzer. Client-owned dogs (n = 77) and cats (n = 64). Peripheral and paired capillary whole-blood glucose concentrations measured via PBGM were compared to plasma glucose concentrations measured via a Cobas c501 reference analyzer (Roche). Analytical accuracy was evaluated with the Spearman rank correlation coefficient, Bland-Altman difference plot analysis, and Deming regression. Clinical accuracy was evaluated with Parkes error grid analysis. Paired peripheral and capillary blood samples were compared with the Wilcoxon matched-pairs signed-rank test. There was a high correlation between PBGM and reference analyzer readings in dogs and cats. Human quality assurance standards (International Organization for Standardization 15197:2013 guidelines) for analytical accuracy were met for 95% of feline peripheral blood samples and 89% of canine samples. Similar veterinary standards (American Society of Veterinary Clinical Pathology guidelines) were met for 89% of canine and 92% of feline peripheral blood glucose measurements. Error grid analysis showed that all peripheral canine and 97% of feline measurements were clinically accurate (zone A). Any altered clinical decision for the remaining feline measurements was expected to minimally impact outcome (zone B). No significant difference was found between peripheral and capillary blood glucose measurements in either species. The PBGM produced clinically accurate results and is suitable for use in veterinary and home settings to measure blood glucose.

Experimental and theoretical investigations into the surface chemical properties and separation of serpentine from quartz using xanthomonas campestris as a selective flocculant

Separation of fine serpentine (SPT) from quartz (QZ) both of d80 close to 20 µm using an eco-friendly microbial exo-polysaccharide, xanthomonas campestris (XCT), as a selective flocculant for SPT was conducted experimentally and substantiated theoretically. The adsorption of XCT onto SPT was observed to decrease with increase in pH, whereas that of QZ was nearly nil beyond pH 2.1. Zeta potential of SPT in presence of XCT decreased with increase in pH further attesting to the adsorption and anionicity of XCT. The FTIR studies confirmed the interaction of XCT with SPT in presence of sodium hexametaphosphate. The nature of intermolecular interactions present in complexes formed on SPT surface was revealed by quantum theory of atoms in molecules to be non-covalent. The electron density difference plot conducted on formed complexes indicated that electrons drifted from XCT to the surface of SPT. Selective flocculation SPT-QZ (1:1) mixture conducted at pH 6 and pH 7.5 in presence of 4 mg/L and 2 mg/L of sodium hexametaphosphate coupled with 100 mg/L of XCT yielded separation efficiency and selectivity ratio of 96.5 % and 71.2, respectively, after three desliming stages. Therefore, XCT is a potential selective flocculant for serpentine.

Modulation of magnetic properties of trilayer MoS2/ZnO/VS2 van der Waals heterostructure via strain engineering for spintronics application

MoS2/ZnO/VS2 trilayer van der Waals (vdW) heterostructure is reported for its electronic and magnetic properties for the first time. Heyd-Scuseria-Ernzerhof (HSE) hybrid functional is used to compute the electronic band structure and it is observed that the heterojunction exhibits an indirect transition. The trilayer showed type II band alignment. This along with the Charge Density Difference (CDD) isosurface and plot showed the charge transfer in both the spin channels from ZnO to both MoS2 and VS2 monolayer. Monte Carlo (MC) simulation revealed a low Curie temperature (TC) value of 65 K. Effect of compressive and tensile biaxial strain on the trilayer was studied where all the strained system turned metallic. Under both biaxial tensile and compressive strain, the TC at first increased and then gradually decreased which hints at tuning the TC with strain engineering. Thus, the metallic strained MoS2/ZnO/VS2 trilayer has potential application in the spintronics devices.

Accurate non-ceruloplasmin bound copper: a new biomarker for the assessment and monitoring of Wilson disease patients using HPLC coupled to ICP-MS/MS.

Assessment of Wilson disease is complicated, with neither ceruloplasmin, nor serum or urine copper, being reliable. Two new indices, accurate non-ceruloplasmin copper (ANCC) and relative ANCC were developed and applied to a cohort of 71 patients, as part of a Wilson Disease Registry Study. Elemental copper-protein speciation was developed for holo-ceruloplasmin quantitation using strong anion exchange chromatography coupled to triple quadrupole inductively coupled plasma mass spectrometry. The serum proteins were separated using gradient elution and measured at m/z 63 (63Cu+) and 48 (32S16O+) using oxygen reaction mode and Cu-EDTA as calibration standard. The ANCC was calculated by subtraction of the ceruloplasmin bound copper from the total serum copper and the RelANCC was the percentage of total copper present as the ANCC. The accuracy of the holo-ceruloplasmin measurement was established using two certified reference materials, giving a mean recovery of 94.2 %. Regression analysis between the sum of the copper containing species and total copper concentration in the patient samples was acceptable (slope=0.964, intercept=0, r=0.987) and a difference plot, gave a mean difference for copper of 0.38 μmol/L. Intra-day precision for holo-ceruloplasmin at serum copper concentrations of 0.48 and 3.20 μmol/L were 5.2 and 5.6 % CVand the intermediate precision at concentrations of 0.80 and 5.99 μmol/L were 6.4 and 6.4 % CV, respectively. The limit of detection (LOD) and lower limit of quantification (LLOQ) for holo-ceruloplasmin were 0.08 and 0.27 μmol/L as copper, respectively. ANCC and Relative ANCC are important new diagnostic and monitoring biomarker indices for Wilson disease (WD).

A frugal machine-intelligent paper sensor for quantification of glucose through standalone desktop application: A computational and experimental approach

A paper-based electrochemical sensor utilizing MoS2 as sensing material is developed to quantitatively estimate glucose in a complex extracellular fluid matrix. The contribution of MoS2 as sensing material is substantiated in the context of density functional theory formalism. The molecular modelling of MoS2 and glucose interaction is elucidated through the theoretical estimation of non-covalent interactions and charge density difference plots. The charge transfer phenomenon during the oxidation of glucose molecule in electrochemical experiments is verified through electronic band structure analysis and frontier orbital theory. The electrochemical responses indicate that the sensor exhibits an average accuracy of nearly 96%, with a quantification limit of 100 nM. Furthermore, the chronoamperometric measurements highlight the superior sensitivity of the device in presence of various perturbing molecules. The obtained DPV responses were integrated with a robust machine learning-driven standalone app GluQuantify. This app precisely predicts the glucose concentrations in serum samples. The utilization of GluQuantify substantially elevates the overall accuracy of the sensing platform to 99% and automates the detection process. The application also enhances the resolution of the sensor to 0.01 µM, which mitigates the sensor resolution-related issues in manual estimation.

Quantification of C1 inhibitor activity using a chromogenic automated assay: analytical and clinical performances.

The quantification of functional C1 inhibitor activity (fC1-INH) is an important tool to diagnose bradykinin-mediated angioedema (AE), whether hereditary or acquired. For that an accurate assay is necessary, therefore we evaluated the analytical performances of a fC1-INH chromogenic assay (Berichrom®, Siemens) performed utilizing an Optilite turbidimeter (Binding Site). fC1-INH was quantified by means of the chromogenic assay Berichrom®. Internal quality controls were used to determine the precision of the assay. Stability under various storage and matrix conditions, uncertainty, linearity, interference (of hemolysis, lipemia, and icterus), agreement with the manual Technochrom® assay, and diagnostic performances were further evaluated on samples from patients and healthy donors. The fC1-INH Berichrom® assay presented good performances regarding intra- and inter-assay precision (CV: 1.3-4.5 % and 3.0-6.0 %, respectively), expanded uncertainty (5.5 % at normal level and 12.5 % at the clinical threshold) and linearity (rho2>0.99: range 7-130 % activity). Addition of interfering substances (hemoglobin <16 g/L, intralipid® <12 g/L, and bilirubin <1 g/L) did not affect fC1-INH quantification. fC1-INH activity from healthy donors remained stable in citrate whole blood until 4 days at room temperature, and 7 days when plasma was collected. Agreement between the automated Berichrom® assay and the manual Technochrom® assay (n=47) was excellent as obtained with both quantitative (Deming regression and Bland-Altman difference plot) and qualitative (Kappa index=1) analyses. Finally, the diagnostic performance of the quantification of fC1-INH for AE evaluated on 81 patients revealed a sensitivity of 100 %, a specificity of 97.2 %, a positive predictive value of 83.3 % and a negative predictive value of 100 %. The automated fC1-INH Berichrom® assay showed good performance, both at the analytical and diagnostic/clinical levels that allowed its usage in a clinical laboratory for C1-INH-dependent bradykinin-mediated AE research in combination with quantitative C1-INH and C4 determinations.

Automatic detection of Alzheimer's disease from EEG signals using an improved AFS-GA hybrid algorithm.

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by energy diffusion and partial disconnection in the brain, with its main feature being an insidious onset and subtle clinical symptoms. Electroencephalogram (EEG) as a primary tool for assessing and aiding in the diagnosis of brain diseases has been widely used in AD detection. Accurate diagnosis is crucial for preventing the transition from early cognitive impairment to AD and providing early treatment for AD patients. This study aims to establish a hybrid model based on the Improved Artificial Fish Swarm Algorithm (IAFS) and Genetic Algorithm (GA)-IAFS-GA, to determine the optimal channel combination for AD detection under multiple EEG signals. Geometric features and complexity features of AD EEG signals were extracted using Second Order Difference Plot (SODP) and entropy analysis across the full frequency band. Subsequently, Pearson correlation was used for feature ranking, selecting the six least correlated features for each channel. The Relief algorithm was then used to fuse these selected features, with one fused feature representing one channel. Based on this, a feature selection optimization algorithm, IAFS-GA, combining the improved artificial fish swarm algorithm and genetic algorithm, was proposed. Finally, the feature combination was input into a Naive Bayes classifier for the identification of AD patients and normal controls. The feature combination was input into a Naive Bayes classifier for the identification of AD patients and normal controls. Using a five-fold cross-validation strategy across the entire frequency band, the classification accuracy reached 93.53%, with a sensitivity of 98.74%, specificity of 98.25%, and an AUC area of 97.82%. This framework can quickly select appropriate brain channels to enhance the efficiency of detecting AD and other neurological diseases. Moreover, it is the first time that an improved artificial fish swarm genetic combination algorithm and SODP features has been used for channel selection in EEG, proving to be an effective method for AD detection. It is based on SODP analysis, entropy analysis, and intelligent algorithms, which can assist clinicians in rapidly diagnosing AD, reducing the misdiagnosis rate of false positives, and expanding our understanding of brain function in patients with neurological diseases.

A STUDY TO ESTABLISH THE AGREEMENT BETWEEN THE RESULTS OF ELECTROLYTES (SERUM SODIUM AND POTASSIUM) ESTIMATED BY A WET CHEMISTRY INSTRUMENT (EASYLYTE) WITH THAT OBTAINED BY A DRY CHEMISTRY ANALYZER (VITROS 350)

Objectives: The objective of the study was to assess the agreement between results of electrolytes (serum sodium and potassium) estimated by a wet chemistry instrument with that obtained by a dry chemistry analyzer. Methods: It was an observational analytical cross-sectional study done in the Departmental clinical laboratory. The samples were selected randomly from the usual lab workflow. All the samples were first run on the Easylyte (wet chemistry) and then run on the Vitros 350 (dry chemistry). The paired data thus obtained were compiled and tabulated and then statistically analyzed. Results: The agreement of the results between the two methods was evaluated using the Bland–Altman difference plot and the Passing–Bablok Regression Equation and the Deming regression studies. By analyzing the diagram of Bland–Altman, it is seen that for sodium, the average bias is of −2.22; limits of agreement being −26.12–21.77. For potassium, Bland Altman plots show a bias of −0.21; limits of agreement −0.61–0.19. Passing Bablock regression calculated an intercept of −56.86, 95% confidence interval (CI) (−100, −28) and Slope of 1.43 for sodium measurements and calculated an intercept of −0.706, 95% CI (−0.66, −0.45) and Slope of 1.2 for potassium estimation. Conclusion: Statistical analysis revealed conflicting solutions. There is a great discrepancy between the results of the electrolyte estimation by the two methods since the methodologies are not identical.

Assessment of MR blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity under general anesthesia in children with moyamoya.

Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve. However, non-compliant or younger children require general anesthesia to achieve BOLD-CVR imaging. To determine the same-day repeatability of BOLD-CVR imaging under general anesthesia in children with moyamoya. Twenty-eight examination pairs were included (mean patient age = 7.3 ± 4.0years). Positive and negatively reacting voxels were averaged over signals and counted over brain tissue and vascular territory. The intraclass correlation coefficient (ICC), Wilcoxon signed-rank test, and Bland-Altman plots were used to assess the variability between the scans. There was excellent-to-good (≥ 0.59) within-day repeatability in 18 out of 28 paired studies (64.3%). Wilcoxon signed-rank tests demonstrated no significant difference in the grey and white matter CVR estimates, between repeat scans (all p-values > 0.05). Bland-Altman plots of differences in mean magnitude of positive and negative and fractional positive and negative CVR estimates illustrated a reasonable degree of agreement between repeat scans and no systematic bias. BOLD-CVR imaging provides repeatable assessment of cerebrovascular reserve in children with moyamoya imaged under general anesthesia.

Optoelectronic and photocatalytic behaviour of a type-II GaAlS2/HfS2 heterostructure: ab initio study

Theoretical examination based on first principle computation has been conducted for van der Waals heterostructure (vdwHS) GaAlS2/HfS2 including structural, optoelectronic and photocatalytic characteristics. From the adhesion energy calculation, the AB configuration of GaAlS2/HfS2 vdwHS is the most stable. A type-II GaAlS2/HfS2 vdwHS is a dynamically and thermally stable structure. The band edge position, projected band, and projected charge densities verify the type-II alignment of GaAlS2/HfS2 vdwHS. For GaAlS2/HfS2, GaAlS2 is acting as a donor and HfS2 is acting as an acceptor ensured by the charge density difference plot. The electron localized function validates the weak van der Waals interaction between GaAlS2 and HfS2. The GaAlS2/HfS2 vdwHS possess an indirect bandgap of 1.54 eV with notable absorption in the visible range. The findings assure that the GaAlS2/HfS2 vdwHS is an efficient photocatalyst for pH 4–8. The band alignment of GaAlS2/HfS2 is suitable for Z-scheme charge transfer. The strain influenced band edge suggests that the GaAlS2/HfS2 vdwHS remains photocatalytic for strain −4% to +6% in both cases of uniaxial and biaxial strains.

Epileptic Seizure Detection from Decomposed EEG Signal through 1D and 2D Feature Representation and Convolutional Neural Network

Electroencephalogram (EEG) has emerged as the most favorable source for recognizing brain disorders like epileptic seizure (ES) using deep learning (DL) methods. This study investigated the well-performed EEG-based ES detection method by decomposing EEG signals. Specifically, empirical mode decomposition (EMD) decomposes EEG signals into six intrinsic mode functions (IMFs). Three distinct features, namely, fluctuation index, variance, and ellipse area of the second order difference plot (SODP), were extracted from each of the IMFs. The feature values from all EEG channels were arranged in two composite feature forms: a 1D (i.e., unidimensional) form and a 2D image-like form. For ES recognition, the convolutional neural network (CNN), the most prominent DL model for 2D input, was considered for the 2D feature form, and a 1D version of CNN was employed for the 1D feature form. The experiment was conducted on a benchmark CHB-MIT dataset as well as a dataset prepared from the EEG signals of ES patients from Prince Hospital Khulna (PHK), Bangladesh. The 2D feature-based CNN model outperformed the other 1D feature-based models, showing an accuracy of 99.78% for CHB-MIT and 95.26% for PHK. Furthermore, the cross-dataset evaluations also showed favorable outcomes. Therefore, the proposed method with 2D composite feature form can be a promising ES detection method.

Gas Detecting Evaluation by Graphitic-based Silicon Carbide Nanosurface doped with Manganese: A Promising Device for Air Pollution Monitoring

Silicon carbide (SiC) as a direct broad bandgap semiconducting material has the potential to bring a considerable developement into optoelectronic and electronic devices. This article aims to investigate Physico-chemical properties of manganese (Mn)–doped graphene-like silicon carbide (SiC) monolayer sheet by the first-principles methods based on the density functional theory (DFT) for scavenging of CO, CO2, NO, NO2 gas molecules. The results recommend that the adsorption of these gas molecules on Mn-embedded SiC sheet monolayer is more energetically desired than that on the pristine ones. Gas molecules of CO, CO2, NO, NO2 have been adsorbed on the Mn site of doped SiC monolayer through the formation of covalent bonds. The assumption of chemical adsorptions has been approved by the projected density of states (PDOS) and charge density difference plots. Charge density difference calculations also indicate that the electronic densities were mainly accumulated on the adsorbate of CO, CO2, NO, NO2 gas molecules. The ability of SiC nanosheet for monitoring of CO, CO2, NO and NO2 is fluctuated by their selectivity and sensitivity through NMR, NQR, IR and HOMO/LUMO approaches which can represent the efficiency of Mn–doped SiC surface as the promising sensors toward air pollution detecting.