Epilepsy, affecting over 50 million people globally, presents a significant neurological challenge. Effective prevention of epileptic seizures relies on proper administration and monitoring of Anti-Seizure Medication (ASMs). Therapeutic Drug Monitoring (TDM) ensures optimal dosage adjustment, minimizing adverse effects and potential drug interactions. While traditional venous blood collection for TDM may be stressful, emerging alternative sampling methods, particularly Dried Blood Spot (DBS) or oral fluid offer less invasive way of sampling. This study aimed to develop and validate an analytical method for the determination of lamotrigine in such alternative samples. The sample, either DBS or oral fluid, was subjected to extraction, evaporation, and reconstitution in 15 % acetonitrile containing 0.1 % formic acid. A Kinetex C18 Polar column was used for liquid chromatographic separation and MS in ESI+ mode was used for detection and quantitation of lamotrigine using an isotopically labelled internal standard according to EMA guidelines. The calibration range of the developed method enables the determination of lamotrigine in the concentration range of 1-30 μg/mL in DBS and 0.5-20 μg/mL in oral fluid. Oral fluid and DBS samples from patients treated with lamotrigine analysed by the developed method were compared to plasma concentrations measured by the hospital's accredited laboratory. Preliminary results indicate a promising potential for these alternative matrices in clinical TDM applications. By offering a less invasive sampling approach, this method improves the accessibility and safety of pharmacotherapy for epilepsy patients. The results of this study lay the foundation for further clinical applications by implementing alternative matrix TDM, which may significantly advance personalized care in epilepsy management.
- Klíčová slova
- Alternative matrix, Antiepileptics, Dried blood spot, Lamotrigine, Quantification, Saliva, Validation,
- MeSH
- antikonvulziva * analýza krev MeSH
- chromatografie kapalinová metody MeSH
- epilepsie farmakoterapie MeSH
- kalibrace MeSH
- kapalinová chromatografie-hmotnostní spektrometrie MeSH
- lamotrigin * analýza krev MeSH
- lidé MeSH
- limita detekce MeSH
- monitorování léčiv * metody MeSH
- reprodukovatelnost výsledků MeSH
- sliny * chemie MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- test suché kapky krve * metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- validační studie MeSH
- Názvy látek
- antikonvulziva * MeSH
- lamotrigin * MeSH
PURPOSE: The aim of this study was to develop a simple, robust, and easy-to-use calibration procedure for correcting misalignments in rosette MRI k-space sampling, with the objective of producing images with minimal artifacts. METHODS: Quick automatic calibration scans were proposed for the beginning of the measurement to collect information on the time course of the rosette acquisition trajectory. A two-parameter model was devised to match the measured time-varying readout gradient delays and approximate the actual rosette sampling trajectory. The proposed calibration approach was implemented, and performance assessment was conducted on both phantoms and human subjects. RESULTS: The fidelity of phantom and in vivo images exhibited significant improvement compared with uncorrected rosette data. The two-parameter calibration approach also demonstrated enhanced precision and reliability, as evidenced by quantitative T 2 * $$ {\mathrm{T}}_2^{\ast } $$ relaxometry analyses. CONCLUSION: Adequate correction of data sampling is a crucial step in rosette MRI. The presented experimental results underscore the robustness, ease of implementation, and suitability for routine experimental use of the proposed two-parameter rosette trajectory calibration approach.
- Klíčová slova
- gradient imperfections, k‐space misalignment, rosette trajectory, trajectory estimation,
- MeSH
- algoritmy * MeSH
- artefakty * MeSH
- fantomy radiodiagnostické * MeSH
- kalibrace MeSH
- lidé MeSH
- magnetická rezonanční tomografie * metody MeSH
- mozek diagnostické zobrazování MeSH
- počítačové zpracování obrazu * metody MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This paper deals with evaluation of photogrammetric measurements of pavement macrotexture for the purposes of new non-contact method for determination of pavement skid resistance. The aim was to create a method that yields results comparable to existing pavement friction measurement techniques, particularly the sand method, and to assess whether the measurements obtained using the non-contact approach are equally effective. Additionally, the goal was to introduce and define limits for camera calibration applicable to similar cases of object measurements at close distances. Based on existing standards, specific pavement samples exhibiting various macrotexture qualities were selected. The authors conducted 23 different combinations of photogrammetric measurements based on their findings during the evaluations. A comparison of the applied procedures with a reference measurement using the sand method was made, and the measurement error rate was calculated. By evaluating the different variations of the road surface models created, it was concluded that the most reliable results for defining friction are obtained by interleaving the test specimen through a plane based on the principle of best fit using the four highest points of the macrotexture. The ideal size of the sub-areas for applying the mask is 7.5-10 mm. Photogrammetry has proven to be a suitable and accurate tool for assessing pavement surface texture and can be considered as a suitable alternative to other skid resistance measurement approaches.
- MeSH
- fotogrammetrie * metody MeSH
- kalibrace MeSH
- tření * MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE: With the increasing use of proton therapy, there is a growing emphasis on including radiation quality, often quantified by linear energy transfer, as a treatment plan optimization factor. The Timepix detectors offer energy-sensitive particle tracking useful for the characterization of proton linear energy transfer. To improve the detector's performance in mixed radiation fields produced in proton therapy, we customized the detector settings and performed the per-pixel energy calibration. METHODS: The detection threshold and per-pixel signal shaping time (IKrum current) were customized, and energy calibration was performed for MiniPIX Timepix3. The detector calibration was verified using α source and clinical proton beams, as well as Monte Carlo simulations. The effects on the detector's performance, in terms of spectral saturation and pixel occupancy, were evaluated. RESULTS: Measurements with proton beams showed a good agreement with simulations. With the customized settings, the measurable energy range in the detector data-driven mode was extended, and the signal duration time was reduced by 80%, while the yield of pixel time occupancy reduction depends on the number of occupied pixels. For performed measurements with proton beams, the number of occupied pixels was further reduced up to 40% due to the increased threshold. CONCLUSIONS: Customized detector configuration of the Timepix3 detector allowed for reduced pixel occupancy and mitigation of signal saturation in a data-driven mode without significantly interfering with the energy deposition measurement. The presented approach enables the extension of the operational range, including higher intensities and mixed-radiation fields in particle radiotherapy environments.
- Klíčová slova
- Pixel detector, Proton therapy, Semiconductor detector,
- MeSH
- časové faktory MeSH
- kalibrace MeSH
- lineární přenos energie MeSH
- metoda Monte Carlo MeSH
- protonová terapie * MeSH
- Publikační typ
- časopisecké články MeSH
Soil spectroscopy is a widely used method for estimating soil properties that are important to environmental and agricultural monitoring. However, a bottleneck to its more widespread adoption is the need for establishing large reference datasets for training machine learning (ML) models, which are called soil spectral libraries (SSLs). Similarly, the prediction capacity of new samples is also subject to the number and diversity of soil types and conditions represented in the SSLs. To help bridge this gap and enable hundreds of stakeholders to collect more affordable soil data by leveraging a centralized open resource, the Soil Spectroscopy for Global Good initiative has created the Open Soil Spectral Library (OSSL). In this paper, we describe the procedures for collecting and harmonizing several SSLs that are incorporated into the OSSL, followed by exploratory analysis and predictive modeling. The results of 10-fold cross-validation with refitting show that, in general, mid-infrared (MIR)-based models are significantly more accurate than visible and near-infrared (VisNIR) or near-infrared (NIR) models. From independent model evaluation, we found that Cubist comes out as the best-performing ML algorithm for the calibration and delivery of reliable outputs (prediction uncertainty and representation flag). Although many soil properties are well predicted, total sulfur, extractable sodium, and electrical conductivity performed poorly in all spectral regions, with some other extractable nutrients and physical soil properties also performing poorly in one or two spectral regions (VisNIR or NIR). Hence, the use of predictive models based solely on spectral variations has limitations. This study also presents and discusses several other open resources that were developed from the OSSL, aspects of opening data, current limitations, and future development. With this genuinely open science project, we hope that OSSL becomes a driver of the soil spectroscopy community to accelerate the pace of scientific discovery and innovation.
- MeSH
- algoritmy MeSH
- kalibrace MeSH
- monitorování životního prostředí * metody MeSH
- půda * chemie MeSH
- spektrální analýza * metody MeSH
- strojové učení MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- půda * MeSH
The approaches to matrix effects determination and reduction in ultra-high performance supercritical fluid chromatography with mass spectrometry detection have been evaluated in this study using different sample preparation methods and investigation of different calibration models. Five sample preparation methods, including protein precipitation, liquid-liquid extraction, supported liquid extraction, and solid phase extraction based on both "bind and elute" and "interferent removal" modes, were optimized with an emphasis on the matrix effects and recovery of 8 forms of vitamin E, including α-, β-, γ-, and δ-tocopherols and tocotrienols, from plasma. The matrix effect evaluation included the use and comparison of external and internal calibration using three models, i.e., least square with no transformation and no weighting (1/x0), with 1/x2 weighting, and with logarithmic transformation. The calibration model with logarithmic transformation provided the lowest %-errors and the best fits. Moreover, the type of the calibration model significantly affected not only the fit of the data but also the matrix effects when evaluating them based on the comparison of calibration curve slopes. Indeed, based on the used calibration model, the matrix effects calculated from calibration slopes ranged from +92% to - 72% for α-tocopherol and from -77% to +19% in the case of δ-tocotrienol. Thus, it was crucial to calculate the matrix effect by Matuszewski's post-extraction approach at six concentration levels. Indeed, a strong concentration dependence was observed for all optimized sample preparation methods, even if the stable isotopically labelled internal standards (SIL-IS) were used for compensation. The significant differences between individual concentration levels and compounds were observed, even when the tested calibration range covered only one order of magnitude. In methods with wider calibration ranges, the inappropriate use of calibration slope comparison instead of the post-extraction addition approach could result in false negative results of matrix effects. In the selected example of vitamin E, solid-phase extraction was the least affected by matrix effects when used in interferent removal mode, but supported liquid extraction resulted in the highest recoveries. We showed that the calibration model, the use of a SIL-IS, and the analyte concentration level played a crucial role in the matrix effects. Moreover, the matrix effects can significantly differ for compounds with similar physicochemical properties and close retention times. Thus, in all bioanalytical applications, where different analytes are typically determined in one analytical run, it is necessary to carefully select the data processing in addition to the method for the sample preparation, SIL-IS, and chromatography.
- Klíčová slova
- Calibration curve, Electrospray ionization, Matrix effects, Post-extraction addition, Sample preparation, Single quadrupole mass spectrometry, Ultra-high performance supercritical fluid chromatography,
- MeSH
- extrakce na pevné fázi metody MeSH
- hmotnostní spektrometrie * metody MeSH
- kalibrace MeSH
- lidé MeSH
- superkritická fluidní chromatografie * metody MeSH
- vitamin E * krev analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- vitamin E * MeSH
Redox regulations and antioxidant defence play a central role in the acclimation of plants to their environment. Glutathione represents an essential component of the cellular antioxidant defence system, which keeps levels of reactive oxygen species (ROS) under control. High-performance liquid chromatography (HPLC) separation with fluorescence detection is a sensitive method that enables analysis of reduced and oxidised glutathione levels in small samples of plant tissues or plant cell culture. We aimed to optimise the method to obtain more accurate information about the total level of glutathione and the proportion of the reduced form (GSH) by choosing the most suitable reduction reagent and the conditions under which the reduction occurs. The applicability of the developed method was verified by analysing tobacco cells treated with hydrogen peroxide, which caused a decrease in the GSH/total glutathione ratio. Significant changes in the level of glutathione as well as in the GSH/total glutathione ratio were also observed during tobacco cell culture development.
- Klíčová slova
- Glutathione, HPLC analysis, Monochlorobimane reagent, Nicotiana tabacum, tris(2-carboxyethyl)phosphine,
- MeSH
- glutathion * analýza MeSH
- kalibrace MeSH
- kultivované buňky MeSH
- oxidace-redukce MeSH
- oxidační stres * MeSH
- peroxid vodíku farmakologie MeSH
- rostlinné buňky * MeSH
- tabák * genetika metabolismus MeSH
- vysokoúčinná kapalinová chromatografie * metody MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- glutathion * MeSH
- peroxid vodíku MeSH
In this community effort, we compare measurements between 34 laboratories from 19 countries, utilizing mixtures of labelled authentic synthetic standards, to quantify by mass spectrometry four clinically used ceramide species in the NIST (National Institute of Standards and Technology) human blood plasma Standard Reference Material (SRM) 1950, as well as a set of candidate plasma reference materials (RM 8231). Participants either utilized a provided validated method and/or their method of choice. Mean concentration values, and intra- and inter-laboratory coefficients of variation (CV) were calculated using single-point and multi-point calibrations, respectively. These results are the most precise (intra-laboratory CVs ≤ 4.2%) and concordant (inter-laboratory CVs < 14%) community-derived absolute concentration values reported to date for four clinically used ceramides in the commonly analyzed SRM 1950. We demonstrate that calibration using authentic labelled standards dramatically reduces data variability. Furthermore, we show how the use of shared RM can correct systematic quantitative biases and help in harmonizing lipidomics. Collectively, the results from the present study provide a significant knowledge base for translation of lipidomic technologies to future clinical applications that might require the determination of reference intervals (RIs) in various human populations or might need to estimate reference change values (RCV), when analytical variability is a key factor for recall during multiple testing of individuals.
- MeSH
- ceramidy * krev MeSH
- hmotnostní spektrometrie metody MeSH
- kalibrace MeSH
- laboratoře * normy MeSH
- lidé MeSH
- lipidomika metody MeSH
- referenční standardy * MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ceramidy * MeSH
Many applications in laboratory, industrial and R&D practice involve utilization of standard chemical vapor mixtures, therefore their availability, ease of preparation and reliability play a crucial role. This work is presenting a new instrumentation based on the innovated dynamic preparation method using the injection of liquid sample, fast evaporation, and uniform mixing with carrier gas. The combination of precise syringe drives, quantitative evaporation and controlled flow of carrier gas provides very high level of accuracy and stability of the generation process. The system is robust with minimal requirements for calibration, and it is suitable for producing single or multi component mixtures.
- Klíčová slova
- Evaporation, Gas generator, Injection, Vapor mixture, Volatile organic compounds,
- MeSH
- kalibrace MeSH
- plyny * MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- plyny * MeSH
Machine learning methods and agent-based models enable the optimization of the operation of high-capacity facilities. In this paper, we propose a method for automatically extracting and cleaning pedestrian traffic detector data for subsequent calibration of the ingress pedestrian model. The data was obtained from the waiting room traffic of a vaccination center. Walking speed distribution, the number of stops, the distribution of waiting times, and the locations of waiting points were extracted. Of the 9 machine learning algorithms, the random forest model achieved the highest accuracy in classifying valid data and noise. The proposed microscopic calibration allows for more accurate capacity assessment testing, procedural changes testing, and geometric modifications testing in parts of the facility adjacent to the calibrated parts. The results show that the proposed method achieves state-of-the-art performance on a violent-flows dataset. The proposed method has the potential to significantly improve the accuracy and efficiency of input model predictions and optimize the operation of high-capacity facilities.
