Inter-day Variations Research Articles

Quantitative estimation of molnupiravir by UV- Spectrophotometric method

A simple, rapid, accurate and economical UV-spectrophotometric method has been developed for estimation of Molnupiravir from bulk and pharmaceutical formulation. The λ of Molnupiravir in Distilled water was found to be 235 nm. The is for zero order of drug and for Zero order AUC. The AUC of the drug was found to be in the range of 228.00 – 243.40 nm. The drug follows linearity in the concentration range 5-30 µg/ml with correlation coefficient value 0.999. The proposed method was applied to pharmaceutical formulation and % amount of drug estimated 99.99was found in good agreement with the label claim. The accuracy of the method was checked by recovery experiment performed at three different levels i.e., 80%, 100% and 120 % w/w. The % recovery was found to be in the range 98.15%– 99.97% for method A and 98.85% — 99.56% for method B. The low values of % R.S.D. are indicative of the accuracy and reproducibility of the method. The precision of the method was studied as an intra-day, inter-day variations and repeatability. The % R.S.D. value less than 2 indicate that the method is precise. Ruggedness of the proposed method was studied with the help of two analysts. The above method was a rapid and cost-effective quality-control tool for routine analysis of Molnupiravir in bulk and in pharmaceutical dosage form.

Urinary Profile of Endogenous Gamma-Hydroxybutyric Acid and its Biomarker Metabolites in Healthy Korean Females: Determination of Age-Dependent and Intra-Individual Variability and Identification of Metabolites Correlated With Gamma-Hydroxybutyric Acid.

Gamma-hydroxybutyric acid (GHB), used as a therapeutic and an illegal anesthetic, is a human neurotransmitter produced during gamma-aminobutyric acid (GABA) biosynthesis and metabolism. Potential biomarker metabolites of GHB intoxication have been identified previously; however, reference concentrations have not been set due to the lack of clinical study data. Urinary profiling of endogenous GHB and its biomarker metabolites in urine samples (n = 472) of 206 healthy females was performed based on differences in age and time of sample collection using liquid chromatography-tandem mass spectrometry following validation studies. The unadjusted and creatinine-adjusted urinary concentrations ranges were obtained after urinary profiling. The creatinine-adjusted concentrations of glutamic and succinic acids and succinylcarnitine significantly increased, whereas that of glycolic acid significantly decreased with advancing age. Significant inter-day variation of GABA concentration and intra-day variation of 3,4-dihydroxybutyric acid and succinylcarnitine concentrations were observed. The urinary concentrations of 2,4-dihydroxybutyric acid, succinic acid, and 3,4-dihydroxybutyric acid showed the highest correlation with that of GHB. Data from this study suggest population reference limits to facilitate clinical and forensic decisions related to GHB intoxication and could be useful for identification of biomarkers following comparison with urinary profiles of GHB-administered populations.

Mass spectrometric study of variation in kinin peptide profiles in nasal fluids and plasma of adult healthy individuals

BackgroundThe kallikrein-kinin system is assumed to have a multifunctional role in health and disease, but its in vivo role in humans currently remains unclear owing to the divergence of plasma kinin level data published ranging from the low picomolar to high nanomolar range, even in healthy volunteers. Moreover, existing data are often restricted on reporting levels of single kinins, thus neglecting the distinct effects of active kinins on bradykinin (BK) receptors considering diverse metabolic pathways. A well-characterized and comprehensively evaluated healthy cohort is imperative for a better understanding of the biological variability of kinin profiles to enable reliable differentiation concerning disease-specific kinin profiles.MethodsTo study biological levels and variability of kinin profiles comprehensively, 28 healthy adult volunteers were enrolled. Nasal lavage fluid and plasma were sampled in customized protease inhibitor prespiked tubes using standardized protocols, proven to limit inter-day and interindividual variability significantly. Nine kinins were quantitatively assessed using validated LC–MS/MS platforms: kallidin (KD), Hyp4-KD, KD1-9, BK, Hyp3-BK, BK1-8, BK1-7, BK1-5, and BK2-9. Kinin concentrations in nasal epithelial lining fluid were estimated by correlation using urea.ResultsCirculating plasma kinin levels were confirmed in the very low picomolar range with levels below 4.2 pM for BK and even lower levels for the other kinins. Endogenous kinin levels in nasal epithelial lining fluids were substantially higher, including median levels of 80.0 pM for KD and 139.1 pM for BK. Hydroxylated BK levels were higher than mean BK concentrations (Hyp3-BK/BK = 1.6), but hydroxylated KD levels were substantially lower than KD (Hyp4-KD/KD = 0.37). No gender-specific differences on endogenous kinin levels were found.ConclusionsThis well-characterized healthy cohort enables investigation of the potential of kinins as biomarkers and would provide a valid control group to study alterations of kinin profiles in diseases, such as angioedema, sepsis, stroke, Alzheimer’s disease, and COVID-19.

Interpretation of clot-based lupus anticoagulant assays-Normalizing clotting time against different denominators.

The endpoint for all lupus anticoagulant (LA) assays is a clotting time in seconds. This study aimed to clarify the use of normalizing clotting time to ratio and how the use of different denominators is relevant. Whether normalization could reduce reagent variability and possess better diagnostic performances was assessed; denominators included reference interval (RI) mean, local-obtained pooled plasma clotting time, standard plasma clotting time, and control plasma clotting time (CNPPct). Moreover, whether day-to-day variation in CNPPct would impact its application was studied. If not normalized, significant difference existed among different reagent batches; if normalized (against any denominators), no statistically significant difference existed anymore. The validation of in-house RIs achieved a 100% success rate. Normalization against different denominators had different RIs, but the same diagnostic efficacies (when a prolonged LA1 is used to suggest further LA-related testings, normalized LA1 demonstrated a better sensitivity: 1.0 vs. 0.95). Normalization against a "daily" CNPPct (obtained alongside test plasmas day to day) demonstrated low inter-day variations (LA1: ~1%, LA2: ~1%), and it could employ the RI for normalization against a "fixed" CNPPct (obtained alongside normal plasmas when the RI was established). Normalizing clotting time reduces reagent-batch variability and promotes the adoption of common RIs, and therefore reduces the necessity of establishing RI for new reagent batches. Normalized LA1 is more sensitive when used to suggest further LA-related testings, and therefore reduces the rate of missed LA diagnosis. All denominators are of the same application value. Day-to-day variation in CNPPct did not impact its application as a reliable denominator.

Assessing variability of aerosols generated from e-Cigarettes

While some in vitro and in vivo experiments have studied the toxic effects of e-cigarette (e-cig) components, the typical aerosol properties released from e-cigarettes have not been well characterized. In the present study, we characterized the variability in mass concentration and particle size distribution associated with the aerosol generation of different devices and e-liquid compositions in an experimental setup. The findings of this study indicate a large inter-day variability in the experiments, likely due to poor quality control in some e-cig devices, pointing to the need for a better understanding of all the factors affecting exposures in in vitro and in vivo experiments, and the development of standardized protocols for generation and measurement of e-cig aerosols.

Development and Validation of Stability Indicating Method of UV-Spectrophotometry for the Estimation of Flavoxate in Bulk and Tablet Dosage form

Literature survey reveals that few spectrophotometric, high performance liquid chromatographic (HPLC) and High Performance Thin Layer Chromatographic (HPTLC) methods were reported for the estimation of Flavoxate HCl in single and in combined dosage forms. But there is no any stability indicating UV spectroscopic study is reported for Flavoxate in single dosage form. So the present study was aimed to development of simple, accurate, rapid and economical UV-spectrophotometric stability indicating assay method were established for the determination of Flavoxate HCl in bulk and tablet formulation. The solvent was selected for stock solution preparation is water and required concentrations were prepared by using the same solvent. The λmax for detection of Flavoxate HCl is 211nm. In this method Flavoxate followed linearity in the concentrations of 1, 3, 5, 7, 9µg/ml with regression coefficient (r2) 0.999. The percent drug content was found to be 98.81±0.39 for FLV in tablet formulation. Recovery study results of FLV ranges from 99.11 to 100.49%. The method was found to be accurate and precise, as indicate by recovery studies as recoveries were close to 100% and %RSD is less than 2. Inter-day and intraday variation was found to be 0.75 and 0.45%, respectively. The LOD and LOQ values were found to be 0.719µg/ml and 2.186µg/ml, respectively. The stability study of Flavoxate was investigated when the drug was subjected to hydrolytic, peroxide, heat and photolytic (UV and sunlight) degradation. The results express that the Flavoxate is under thermal and photolytic (sunlight and UV light) conditions are more stable. In acidic, basic and hydrogen peroxide conditions Flavoxate is degraded in higher amount.

Intra- and Inter-Day Element Variability in Human Breast Milk: Pilot Study.

For infants in the first months of life, breast milk is a complete source of nutrition; however, it can also contain elements that are harmful to the infant. It is therefore critical for infant health to characterize breast milk. The aim of this study was to determine the intra- and inter-day variation of elements in breast milk, for which there is currently limited information, as a pilot study for a larger study. Firstly, we developed a simple and robust analytical method for the determination of multiple elements in breast milk. It was accurate (accuracy ranged from 98% to 107%) for measurement of 26 elements in breast milk by quadrupole inductively coupled plasma-mass spectrometry. Intra- and inter-day variation of elements, protein, and fat in breast milk was determined by analyzing breast milk collected from 11 women at 12 sampling points over three days and calculating intraclass correlation coefficients. Intraclass correlation coefficients showed that while some elements were consistent across time points (e.g., Sr, Ca, and Cu), others showed very high variability (e.g., As, Cd, and Ni). Correlation analyses between elements in breast milk showed strong relationships between those including Fe and Mo, Ca and Sr, and Cd and Fe.

Preformulation Study of Glimepiride: An Insight for Formulation and Development of Parenteral Formulation

Aim: The objective of preformulation study is to develop the elegant, stable, effective and safe dosage form by establishing kinetic profile, compatibility with other formulation excipients and physico-chemical parameters of new drug substance. This could provide important information for formulation design or support the need for molecular modification. So, in the present study preformulation studies were performed on Glimepiride (GMP) to assess its suitability for parenteral formulation. Glimepiride is the first IIIrd generation sulphonyl urea used to treat type –II diabetes mellitus.
 Methods: The authenticity of GMP was established by DSC and FTIR spectra. A UV spectrophotometric method and HPLC method were employed for determination of GMP in bulk active pharmaceutical ingredient (API).
 Results: The UV method was linear in the range of 3-10 μg/ml. The low % CV values of intra-day and inter-day variations revealed that the proposed method is robust. The retention time of GMP in HPLC method was found to be 1.9 min. The method was proven robust by obtaining very high regression coefficient value (0.999).
 Conclusions: The results of the physicochemical study of drug revealed suitability of GMP for parenteral route. Moreover, the drug was found stable in both solid as well as liquid state at different conditions.

Characterizing Fixational Eye Motion Variance Over Time as Recorded by the Tracking Scanning Laser Ophthalmoscope.

PurposeThe purpose of this study was to characterize the benign biological variance of fixational microsaccades in a control population using a tracking scanning laser ophthalmoscope (TSLO), accounting for machine accuracy and precision, to determine ideal testing conditions to detect pathologic change in fixational eye motion (FEM).MethodsWe quantified the accuracy and precision of the TSLO, analyzing measurements made by three operators on a model eye. Repeated, 10-second retinal motion traces were then recorded in 17 controls, 3 times a day (morning, afternoon, and evening), on 3 separate days. Microsaccade metrics (MMs) of frequency, average amplitude, peak velocity, and peak acceleration were extracted. Trace to trace, interday, and intraday variability were calculated across all subjects.ResultsIntra-operator and machine variation contributed minimally to total variation, with only 0.007% and 0.14% contribution for frequency and amplitude respectively. Bias was detected, with lower accuracy for higher amplitudes. Participants had an average (SD) microsaccade frequency of 0.84 Hz (0.52 Hz), amplitude of 0.32 degrees (0.11 degrees), peak velocity of 43.68 degrees/s (14.02 degrees/s), and peak acceleration of 13,920.04 degrees/s2 (4,186.84 degrees/s2). The first trace recorded within a session significantly differed from the second two in both microsaccade acceleration and velocity (P < 0.05), and frequency was 0.098 Hz higher in the evenings (P < 0.05). There was no MM difference between days and no evidence of a session-level learning effect (P > 0.05).ConclusionsThe TSLO is both accurate and precise. However, biological inter- and intra-individual variance is present. Trace to trace variability and time of day should be accounted for to optimize detection of pathologic change.

A Single-Step Digestion for the Quantification and Characterization of Trace Particulate Silica Content in Biological Matrices Using Single Particle Inductively Coupled Plasma-Mass Spectrometry.

The increased use of amorphous silica nanoparticles (SiNPs) in food products, materials science, cosmetics, and pharmaceuticals has raised questions about potential hazards in the environment and in human health. Although SiNPs are generally thought to be benign, recent studies have demonstrated toxicity in different cell and animal models. Despite their ubiquitous use, SiNPs are rarely analyzed quantitatively. Often, the methods used to analyze silicon and SiNPs are difficult, costly, require the use of dangerous reagents, and are prone to interferences. Additionally, characterization of SiNPs in complex matrices requires extensive sample preparation. To address this, we propose a single-step digestion method for the determination of trace SiNP content in biological matrices. For conventional inductively coupled plasma-mass spectrometry (ICP-MS) analysis, biological samples are often digested with concentrated HNO3. We found that with conventional ICP-MS, lower limits of detection (LLOD) of silicon are too high for trace analysis. However, we found that SiNPs are stable at a strong acidic pH; thus, concentrated HNO3 could be used to digest biological samples leaving SiNPs intact. Then, by analysis with single particle ICP-MS, we found that the smallest SiNP that could be read was 185nm in size. The concentration for the LLOD was found to be 0.032ppb with interday variability in sizing and concentration at 2.5% and 6.8% respectively. Utilizing this method, SiNPs were accurately sized and counted in cell pellets and media. Our proposed method can be used to accurately quantify and characterize SiNPs (or agglomerated SiNPs) larger than the derived LLOD in a variety of biological matrices and will assist in determining relationships between exposures of SiNPs and toxicity in humans and the environment.

The influence of intra-personal variations in human hand odor on the determination of sample donor

A dual effort investigation was conducted to study (a) the naturally occurring variation in same-donor human hand odor samples over time and (b) the accuracy in associating same-donor human hand odor samples. Hand odor samples were collected from 8 donors throughout 5 sampling sessions; samples were collected in triplicate and analyzed by HS-SPME-GC-MS at each sampling session. The resulting human hand odor profiles were analyzed to investigate (a) the variability of human hand odor profiles as a function of time and (b) the ability to determine the source origin of human hand odor samples, determining samples to be from the same source or different sources. The researchers observed greater variation in 2-dimensional human scent profile patterning schemes among inter-day, inter-subject samples and less variation in inter-day, intra-subject samples. Although intra-subject samples revealed less variation than inter-subject samples, there was still notable variability among inter-day, intra-subject human scent profiles, with an observed time dependency. Two proof of concept models for the source determination of human hand odor samples were developed with maximum performance measuring TPR = 0.817/ FPR = 0.308 and TPR = 1.000/ FPR = 0.206 for models one and two, respectively. The study quantified same-donor human hand odor profile variation over time displayed within a larger goal of determining sample source origin.

Improvement of downscaled ozone concentrations from the transnational scale to the kilometric scale: Need, interest and new insights

BackgroundGround-level ozone is a major public health issue worldwide. An accurate assessment of ozone exposure is necessary. Modeling tools have been developed to tackle this issue in large areas. However, these models could present inaccuracies at the local scale. ObjectivesThe objective of this study was i) to assess whether O3 concentrations estimated by transnational modeling at the kilometric scale (9 km2) could be improved, ii) to propose a potential correction of these downscaled ozone concentrations and iii) to evaluate the efficiency and applicability of such a correction. MethodThe present work was carried out in three phases. First, the performance of a transnational modeling platform (PREV’EST) was assessed at 6 geographic points by comparison with data from 6 air quality monitoring stations. Performance indicators were used for this purpose (MBE (mean bias error), MAE (mean absolute error), RMSE (root mean square error), r (Pearson correlation coefficient), and target plots). Second, several corrections were developed using MARS (multivariate adaptive regression splines) and integrating different sets of variables (mean temperature, relative humidity, rainfall amount, wind speed, elevation, and date). Their performance was evaluated. Third, external validation of the corrections was conducted using the data from six additional air quality monitoring stations. ResultsThe uncorrected PREV’EST model presented a lack of exactitude and precision. These concentrations did not reproduce the interday variability of the measurements, leading to a lack of temporal contrast in exposure data. For the best performance enhancement, the correction applied improved MBE, MAE, RMSE and r from 14.67, 19.23, 23.18 and 0.67 to 0.00, 8.00, 10.19 and 0.91, respectively. External validation confirmed the efficiency of the corrections at the regional scale. ConclusionsWe propose a validated and efficient methodology integrating local environmental variables. The methodology is adaptable according to the context, needs and data available.

Simultaneous analysis of derivatized allyl isothiocyanate together with its phase II metabolites by ultra-high-performance liquid chromatography/tandem mass spectrometry.

Allyl isothiocyanate (AITC) in food products such as wasabi is commonly analyzed by gas chromatography/mass spectrometry (GC/MS), while liquid chromatography/mass spectrometry (LC/MS) is more suitable for the polar metabolites. The development of an effective method for the simultaneous determination of AITC and its phase II metabolites is needed to support drug metabolism and pharmacokinetics (DMPK) studies. Derivatization of AITC by reaction with N-(tert-butoxycarbonyl)-L-cysteine methyl ester (t BocCysME) was used for ultra-high-performance liquid chromatography/electrospray ionization mass spectrometry (UHPLC/ESI-MS) analysis, allowing the simultaneous determination with its phase II metabolites. At room temperature, reaction conditions have been optimized to maximize the reaction of AITC with t BocCysME quantitively. Reaction selectivity was examined by the presence of AITC metabolites. Quantification of AITC was performed by multiple reaction monitoring (MRM) with an external calibration method and applied on the serum of C57BL/6J mouse for a DMPK study. The limit of quantification (LOQ) was determined to be 0.842 nM from the derivatization method and by UHPLC/MS/MS analysis. The method accuracy in the mouse serum samples was 75 ± 2% with a relative standard deviation (RSD) of 3.0% of method variation. The UHPLC/MS/MS analysis gave RSDs of 0.2% and 1.8% for intra-day and inter-day variations. With the newly developed method, AITC could be detected in mouse serum upon oral administration for the first time. An analytical method involving a rapid derivatization pre-treatment and quantitative UHPLC/ESI-QqQ-MS/MS analysis has been developed for a biological sample assay of AITC, enabling selective and sensitive detection of the AITC derivative and AITC metabolites simultaneously. The method developed could be applied to the DMPK study of AITC as well.

Day-to-day Variation of The Heart Rate, Heart Rate Variability, and Energy Expenditure During FIFA 11+ and Dynamic Warm-up Exercises.

There seems to be a scarcity in literature investigating day-to-day warm-up (WU) variations. We investigated day-to-day variation of psychophysiological responses during Fédération Internationale de Football Association (FIFA) 11+ and dynamic warm-up (DWU) exercises. Twenty-one male collegiate soccer players were randomly assigned to the FIFA 11+ (n = 10) or DWU group (n = 11). Each group performed the assigned WU protocol on three different occasions with a 48-h interval in between. The inter-day variation of the heart rate (HR), time distribution of HR zones, heart rate variability (HRV), estimated energy expenditure (EE), blood lactate (BL) concentration, and the Borg rating of perceived exertion (RPE) were recorded. A two-way repeated measures of analysis of variance was used to compare the differences in chosen variables [group (2) × day (3)]. The coefficient of variation was used to determine the dispersion of the variables over the sessions. The interclass correlation coefficient (ICC) with a two-way random model and a single measure (ICC2,1) was used to determine inter-day reliability. There were no significant differences in time spent at particular HR zones and EE in both groups. The FIFA 11+ exercises showed high reliability of exercise duration, average HR (HRaverage), minimal HR (HRmin), peak HR (HRpeak), and post-exercise RPE. In the DWU group, high reliability was found only in HRaverage, HRpeak, and post-exercise RPE. The FIFA 11+ exercises showed similar EE, exercise HR patterns, BL, and RPE compared to the DWU. The FIFA 11+ program is an intense WU protocol with a characteristically low variation of day-to-day exercise HR and RPE responses.

Simultaneous quantitative analysis of seven steroid hormones in human saliva: A novel method based on O-ethylhydroxylamine hydrochloride as derivatization reagent.

Saliva has been widely accepted as a more convenient alternative to serum or plasma in the field of clinical diagnosis. However, the detection of trace components in saliva has been a bottleneck problem. The aim of this work was to develop a highly sensitive and reliable method for simultaneously determining the trace steroid hormones including some with poor ionization efficiency in human saliva by liquid chromatography/tandem mass spectrometry (LC/MS). Saliva was deproteinated by acetonitrile containing mixed isotope internal standards and extracted with methyl tert-butyl ether. The extraction solution was dried under a stream of nitrogen and the residue was derivatized using 50 mM O-ethylhydroxylamine hydrochloride in 80% methanol/water solution (v/v). The processed sample was determined by LC/MS in multiple reaction monitoring (MRM) mode. The method was successfully established for the simultaneous quantification of seven steroid hormones in human saliva and showed excellent specificity and sensitivity. The limits of quantification (LOQs) of all steroid hormones were below 5pg/mL, in particular, the LOQ of progesterone was as low as 0.15 pg/mL. The linear correlation coefficients (r) were greater than 0.9990 in the range of 2-200 pg/mL for T, DHEA, A4, P4, P5, and 17OHP4 and in the range of 5-500 pg/mL for 17OHP5. The intra-day and inter-day variability ranged from 1.86% to 7.83% and 1.95% to 10.4%, respectively. The recovery of the method ranged from 86.9% to 111.1% for all steroid hormones using three spiked concentrations. A novel LC/MS/MS method was developed for the simultaneous quantification of seven kinds of trace steroid hormones in human saliva. The results of the methodological study showed that the method exhibited excellent sensitivity and reliability for the evaluation of free steroid hormones in the human body. It is believed that this method could provide useful information of steroid hormone metabolism for auxiliary diagnosis of some endocrine disorders.

Spectrofluorimetric determination of ondansetron in pharmaceutical tablets: Applicability to human urine and content uniformity testing

Ondansetron is used in chemotherapy and radiotherapy for treatment of nausea and vomiting. The objective of present study is to describe a rapid and sensitive spectrofluorimetric analysis of ondansetron in tablets. The method was basically due to native fluorescence of drug in aqueous medium with excitation and emission wavelength of 316 nm and 353 nm, respectively. The drug shows broad linearity over concentration 0.2 – 2 μg/mL. The detection and quantiation limits are 0.04 and 0.11 μg/mL. The %RSD for interday and intraday variation i.e.0.91–1.09 % and 0.64 – 0.79%.The accuracy was found to be in the range of 98 – 102 % for 0.4–1.2 µg/mL. The developed method is selective, specific, sensitive, precise and accurate for quantification of ondansetron in pharmaceutical tablets. The proposed procedure is valid and can be applicable for determination of content uniformity for available brands of ondansetron and spiked human urine samples. This method is applicable for the daily routine quality control quantitative analysis of ondansetron.

Reliable measurement of plasma kinin peptides: Importance of preanalytical variables

BackgroundThe kallikrein‐kinin system is involved in many (patho)physiological processes and kinin peptides are considered potential clinical biomarkers. Variance in blood specimen collection and processing, artificial ex vivo bradykinin formation, and rapid degradation of kinins have contributed to divergence in published plasma levels, therefore limiting their significance. Thus, reliable preanalytical settings are highly required. ObjectivesThis study aimed to develop and evaluate a standardized preanalytical procedure for reliable kinin quantification. The procedure was based on identification of the most impactful variables on ex vivo plasma level alterations. MethodsSuitable protease inhibitors and blood specimen collection and handling conditions were systematically investigated. Their influence on plasma levels of seven kinins was monitored using an established in‐house liquid chromatography–tandem mass spectrometry platform. ResultsIn nonstandardized settings, ex vivo rise of bradykinin was found to already occur 30 seconds after blood sampling with high interindividual variation. The screening of 17 protease inhibitors resulted in a customized seven‐component protease inhibitor, which efficiently stabilized ex vivo kinin levels. The reliability of kinin levels was substantially jeopardized by prolonged rest time until centrifugation, phlebotomy methodology (eg, straight needles, catheters), vacuum sampling technique, or any time delays during venipuncture. The subsequently developed standardized procedure was applied to healthy volunteers and proved it significantly limited interday and interindividual kinin level variability. ConclusionThe developed procedure for blood specimen collection and handling is feasible in clinical settings and allows for determination of reliable kinin levels. It may contribute to further elucidating the role of the kallikrein‐kinin system in diseases like angioedema, sepsis, or coronavirus disease 2019.

The development, and day-to-day variation, of a Military-Specific Auditory N-Back Task and Shoot-/Don’t -Shoot Task

Abstract During military operations, soldiers are required to successfully complete numerous physical and cognitive tasks concurrently. Understanding the typical variance in research tools that may be used to provide insight into the interrelationship between physical and cognitive performance is therefore highly important. This study assessed the inter-day variability of two military-specific cognitive assessments: a Military-Specific Auditory N-Back Task (MSANT) and a Shoot-/Don’t-Shoot Task (SDST) in 28 participants. Limits of agreement ±95% confidence intervals, standard error of the mean, and smallest detectable change were calculated to quantify the typical variance in task performance. All parameters within the MSANT and SDST demonstrated no mean difference for trial visit in either the seated or walking condition, with equivalency demonstrated for the majority of comparisons. Collectively, these data provided an indication of the typical variance in MSANT and SDST performance, while demonstrating that both assessments can be used during seated and walking conditions.

Evaluation of rapid and standard tandem mass spectrometric methods to analyse veterinary drugs and their metabolites in antemortem bodily fluids from food animals

ABSTRACT Antemortem bodily fluids can serve as an indicator of veterinary medicine exposure prior to food animal slaughter. A multi-residue, rapid screen electrospray ionisation mass spectrometric (RS-ESI-MS) method was developed to analyse 10 veterinary drugs or metabolites (clenbuterol, erythromycin, flunixin, 5-hydroxyflunixin, meloxicam, ractopamine, ractopamine-glucuronide, salbutamol, tylosin, and zilpaterol) in hog oral fluid and bovine urine. Simple acetonitrile extraction with salting-out was employed to remove the analytes from matrices in less than 30 minutes. Instrumental analysis time was < 1 min/injection. Regression coefficients of matrix-matched calibration curves ranged 0.9743–0.9999 across all compounds with limits of detection ranging from 0.46–108 ng mL−1 for cattle urine and 0.19–64.4 ng mL−1 for hog oral fluid across all analytes. Except for ractopamine-glucuronide, analyte recoveries ranged from 92.7–106% for oral fluid and urine fortified at 30, 100, and 300 ng mL−1, with inter-day variations of < 25%. Ractopamine-glucuronide recovery was 93.3% for oral fluid fortified at 300 ng mL−1. The RS-ESI-MS method accurately identified ractopamine and/or ractopamine-glucuronide in incurred cattle urine with results correlating well with traditional LC-MS/MS and HPLC fluorescence methods. As far as we are aware, this is the first report of the direct quantification of ractopamine-glucuronide from biological matrices without lengthy hydrolysis and cleanup steps.

Highly specific β‑glucuronidase light-up natural fluorescent probe with aggregation-induced emission and excited-state intramolecular proton transfer for inhibitors screening and in situ imaging in Escherichia coli

Expression of β-glucuronidase (GUS) in intestinal bacteria has attracted more and more attentions because of its relevant to drug-inducing enteropathy and enterohepatic circulation. Hence it is essential to develop a facile method for efficient inhibitors screening and in situ activity tracking of GUS. Here, a novel light-up natural fluorescent probe, quercetin-3-O-β-D-glucuronide (obtained from Bupleurum scorzonerifolium), for rapid, sensitive, and specific analysis of GUS activity was found. Hydrophilic quercetin-3-O-β-D-glucuronide was catalyzed by GUS to produce hydrophobic quercetin aggregates in situ. The occurrence of quercetin fluorescence at 540 nm (Stokes shift = 175 nm) with aggregation-induced emission and excited-state intramolecular proton transfer characteristics was light-up, which can be used to evaluate GUS activity. A good linear range (5.0–60.0 μg mL−1, R2 = 0.9904), high sensitivity (limit of detection at 0.7 μg mL−1), satisfying precision (relative standard deviation values at 1.2% and 3.0% for intra-day and inter-day variations) and superior selectivity to GUS were obtained. Then, a facile platform for screening of GUS inhibitors from natural compounds library was constructed successfully. Three natural compounds, resveratrol (IC50 = 0.45 ± 0.04 μM), hesperidin (IC50 = 1.46 ± 0.07 μM), and ursolic acid (IC50 = 7.85 ± 0.26 μM)) were screened out with stronger inhibitory efficiency. Furthermore, on account of the outstanding photostability and excellent biocompatibility, quercetin-3-O-β-D-glucuronide has been employed for in situ imaging of endogenous GUS in Escherichia coli noninvasively with low background noise. Results demonstrated the advantage of natural products for novel fluorescent probes and the great potential of quercetin-3-O-β-D-glucuronide in high-throughput inhibitors screening, GUS-related drug discovery, and disease diagnosis.