A decade of HPLC-MS/MS in the routine clinical laboratory--goals for further developments

mRNA Fragmentation Pattern Detected by SHAPE

The success of messenger RNA (mRNA) vaccines in controlling COVID-19 has warranted further developments in new technology. Currently, their quality control process largely relies on low-resolution electrophoresis for detecting chain breaks. Here, we present an approach using multi-primer reverse transcription sequencing (MPRT-seq) to identify degradation fragments in mRNA products. Using this in-house-made mRNA containing two antigens and untranslated regions (UTRs), we analyzed the mRNA completeness and degradation pattern at a nucleotide resolution. We then analyzed the sensitive base sequence and its correlation with the secondary structure. Our MPRT-seq mapping shows that certain sequences on the 5' of bulge-stem-loop structures can result in preferential chain breaks. Our results agree with commonly used capillary electrophoresis (CE) integrity analysis but at a much higher resolution, and can improve mRNA stability by providing information to remove sensitive structures or sequences in the mRNA sequence design.

Comparison of vancomycin assays in patients undergoing hemodialysis

Vancomycin is a glycopeptide antibiotic mainly excreted by glomerular filtration. Therefore, patients undergoing hemodialysis tend to accumulate its crystalline degradation product, which has been associated with cross-reaction in commercial immunoassays. The aim of this study was to assess the performance of two commercial immunoassays for measuring vancomycin levels in patients undergoing hemodialysis. This method-comparison study enrolled patients undergoing hemodialysis at two hospitals in Porto Alegre, Brazil. Vancomycin serum concentrations measured by Chemiluminescent Microparticle Assay (CMIA) and measured by Kinetic Interaction of Microparticles in Solution (KIMS) were compared with Liquid Chromatography coupled with Tandem Mass Spectrometry (LC-MS/MS). A total of 64 samples from 42 patients and 54 samples from 23 patients were included in CMIA and KIMS groups. Both measurements were highly correlated with LC-MS/MS, with Spearman rank correlation coefficient r = 0.840 (p < 0.001) and r = 0.926 (p < 0.001), respectively. No deviation of linearity was observed (p = 0.81 and p = 0.49, respectively). The mean difference between CMIA and LC-MS/MS was -1.19 μg/mL and between KIMS and LC-MS/MS was -2.28 μg/mL. LC-MS/MS measured levels were, on average, 2.64 % higher than CMIA and 8.81 % higher than KIMS. CMIA and KIMS revealed accurate commercial methods to measure vancomycin serum concentrations in patients undergoing hemodialysis.

LncRNA MAGI2-AS3-Encoded Polypeptide Restrains the Proliferation and Migration of Breast Cancer Cells

Accumulating articles have reported the coding potential of long non-coding RNAs (lncRNAs). However, only a few lncRNAs-encoded peptides have been studied. Breast cancer (BRCA) progression-related gene modules were determined by weighted gene co-expression network analysis (WGCNA). Cell viability, proliferation, and migration capacities were assessed by Cell counting kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), and transwell assays. Immunofluorescence (IF) assay was implemented to observe protein expression. Co-immunoprecipitation (Co-IP) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) were employed to analyze MAGI2 antisense RNA 3 (MAGI2-AS3)-ORF5-interacted proteins. WGCNA identified that MEpurple and MEblack modules were significantly negatively correlated with T stage in BRCA patients. MAGI2-AS3 was screened as one of the differentially expressed (DE) lncRNAs with translational potential in MEblack and MEpurple modules in BRCA. The data in The Cancer Genome Atlas (TCGA) uncovered that MAGI2-AS3 abundance was significantly decreased in invasive BRCA patients, and it had high diagnostic and prognostic values. MAGI2-AS3-ORF5 notably restrained BRCA cell viability, proliferation, and migration. Mechanically, MAGI2-AS3-ORF5 might affect the progression of BRCA cells by binding to extracellular matrix (ECM)-related proteins. MAGI2-AS3-ORF5 played an anti-tumor role by inhibiting BRCA cell viability, proliferation, and migration. MAGI2-AS3-ORF5 might modulate BRCA cell migration through ECM-associated proteins.

Preparation of magnetic amphiphilic resin microspheres via the one-step polymerization method and extraction of four glucocorticoids for HPLC-MS analysis

Amphiphilic materials can be used for sample preparation of chromatography or mass spectrometry. Amphiphilic materials with magnetic properties in combination with magnetic suction devices allow for automated sample preparation. However, conventional synthesis methods are cumbersome and not suitable for the mass production of the material. In this study, a micro-suspension polymerization method was developed to synthesize magnetic amphiphilic resin microspheres (MARMs), providing new ideas for the preparation of amphiphilic microspheres. MARMs with particle sizes ranging from 3 to 6 μm were successfully prepared, with BET surface area up to 653.2 m2/g. A magnetic solid-phase extraction method based on MARM-5 was developed for the extraction of four glucocorticoids including Cortisone, Hydrocortisone, Cortodoxone, and Corticosterone. This method had a very short adsorption time of 0.5 min and a total extraction time of only 13 min. The limit of detection for the four glucocorticoids ranged from 0.22 to 0.82 ng/L. There was a good linear relationship between sample concentration and peak area in the range of 25∼500 ng/L. Relative recovery of 98 %∼108 % and internal standard normalized matrix effect factors of 95∼114 % were obtained, and the relative standard deviation was between 2.3 % and 6.3 %. The MARMs would be used as excellent solid extraction material for glucocorticoids.

Electrospray triple quadrupole mass spectrometry guides pathologists to suggest appropriate molecular testing in the identification of rare hemoglobin variants

Background

The presumptive diagnosis of hemoglobinopathies relies on routine tests such as Complete Blood Count (CBC), peripheral blood smear, Liquid Chromatography (LC), and Capillary Electrophoresis (CE), along with clinical findings. Pathologists suggest molecular sequencing of HBA and HBB genes to correlate blood picture with clinical findings in order to identify unknown rare haemoglobin (Hb) variants or variants that coelute with Hb. This paper presents a low-resolution mass spectrometry (MS)-based method for presumptive identification of variants that eluted in zone 12 of CE, followed by molecular sequencing of the HBB gene for a definitive diagnosis of hemoglobinopathies.

Methods

Eight patient samples with a variant peak in zone 12 of CE (Sebia) were analyzed using MS. The mass-to-charge ratio (m/z) observed was deconvoluted to determine the mass of Hb variants. The β variants were subsequently confirmed through molecular sequencing.

Results

Based on the intact mass of the variants, there were two samples of the α variant (α + 58 Da and α + 44 Da), and six samples of the β variant. Out of these six β variant samples, three were the β + 58 Da variant, and three were the β + 30 Da variant. By correlating the intact mass information with the CE pattern and considering the ethnicity of the patients, it was presumed that the α variants were HbJ Meerut (α + 58 Da, x-axis 102) and HbJ Paris-I (α + 44 Da, x-axis 80). Molecular analysis confirmed the identity of β variants as Hb Rambam/HbJ Cambridge, HbJ Bangkok (+58 Da), and Hb Hofu (+30 Da).

Conclusion

The mass information of Hb variants obtained using Electrospray triple quadrupole MS assists pathologists in recommending the appropriate molecular sequencing for identifying unknown variants.

Behind the Curtain: Therapeutic Drug Monitoring of Psychotropic Drugs from a Laboratory Analytical Perspective

PURPOSE

Therapeutic drug monitoring (TDM) is a well-established tool for guiding psychopharmacotherapy and improving patient care. Despite their established roles in the prescription of psychotropic drugs, the "behind the curtain" processes of TDM requests are invariably obscure to clinicians, and literature addressing this topic is scarce.

METHODS

In the present narrative review, we provide a comprehensive overview of the various steps, starting from requesting TDM to interpreting TDM findings, in routine clinical practice. Our goal was to improve clinicians' insights into the numerous factors that may explain the variations in TDM findings due to methodological issues.

RESULTS

We discussed challenges throughout the TDM process, starting from the analyte and its major variation forms, through sampling procedures and pre-analytical conditions, time of blood sampling, sample matrices, and collection tubes, to analytical methods, their advantages and shortcomings, and the applied quality procedures. Additionally, we critically reviewed the current and future advances in the TDM of psychotropic drugs.

CONCLUSIONS

The "behind the curtain" processes enabling TDM involve a multidisciplinary team, which faces numerous challenges in clinical routine. A better understanding of these processes will allow clinicians to join the efforts for achieving higher-quality TDM findings, which will in turn improve treatment effectiveness and safety outcomes of psychotropic agents.

Simultaneous determination of 28 illegal drugs in sewage by high throughput online SPE-ISTD-UHPLC-MS/MS

This study developed an online solid-phase extraction ultra-high performance liquid chromatography-tandem mass spectrometry (Online-SPE-UHPLC-MS/MS) method for the analysis of 28 illegal drugs in sewage. To achieve this, 28 isotope internal standards (ISTDs) were added to 3 mL sewage samples, the pH was adjusted to 7-8 using hydrochloric acid or 20% ammonia water, followed by centrifugation, filtration, and analysis using UHPLC-MS/MS. The results indicated an excellent linearity of 1-300 ng L-1, and cotinine in the concentration range of 20-6000 ng L-1, linear correlation coefficient R2 > 0.995, with the limit of detection (LOD) of 0.01-6 ng L-1, and a limit of quantification (LOQ) of 0.1-20 ng L-1. The addition of three concentrates of low (2 ng L-1/40 ng L-1), medium (20 ng L-1/400 ng L-1), and high concentration (200 ng L-1/4000 ng L-1) demonstrated the matrix effect of the target compound between ± 22.0%. The extraction recovery was 70.0-119.4%, and a percent accuracy of 75.7-118.1%. Similarly, the intra- and inter-day precisions were 1.8-20.0% and 1.5-18.9%, respectively. The results cemented the sensitivity, accuracy, reliability, strong specificity, and reproducibility, which can be used to screen 28 illegal drugs in sewage for trace analysis.

Dose optimization and target attainment of vancomycin in children

Vancomycin is a glycopeptide antibiotic that has been adopted in clinical practice to treat gram-positive infections for more than 70 years. Despite vancomycin's long history of therapeutic use, optimal dose adjustments and pharmacokinetic/pharmacodynamic (PK/PD) target attainment in children are still under debate. Therapeutic drug monitoring (TDM) has been widely integrated into pediatric clinical practice to maximize efficacy and safety of vancomycin treatment. Area under the curve (AUC)-guided TDM has been recently recommended instead of trough-only TDM to ensure PK/PD target attainment of AUC0-24h/minimal inhibitory concentration (MIC) > 400 to 600 and minimize acute kidney injury risk. Bayesian forecasting in pediatric patients allows estimation of population PK to accurately predict individual vancomycin concentrations over time, and consequently total vancomycin exposure. AUC-guided TDM for vancomycin, preferably with Bayesian forecasting, is therefore suggested for all pediatric age groups and special pediatric populations. In this review we aim to analyze the current literature on the pediatric use of vancomycin and summarize the current knowledge on dosing optimization for target attainment in special patient populations.

Vitamin D Status and Reference Intervals Measured by Liquid Chromatography-Tandem Mass Spectrometry for the Early Adulthood to Geriatric Ages in a South Korean Population during 2017-2022

This study aimed to describe the latest 25-hydroxyvitamin D (25(OH)D) status of the South Korean population aged ≥ 20 years using 25(OH)D concentrations measured by liquid chromatography-tandem mass spectrometry and to determine the factors associated with total 25(OH)D concentrations. This cross-sectional, retrospective study consecutively selected 119,335 subjects with a median age of 57 (20-101) years who underwent health checkups among 13 Korean cities during 2017-2022. The total 25(OH)D concentration was 54.5 ± 24.0 nmol/L (mean ± SD). The 7.6%, 47.5%, and 82.9% of participants had 25(OH)D less than 25, 50, and 75 nmol/L, respectively. The prevalence of 25(OH)D deficiency (<25 nmol/L) was higher in females than in males (8.9% vs. 6.1%) and varied between age groups, decreasing in older subjects. Those aged 20-29 years had the highest prevalence of 25(OH)D deficiency (23.0% in females and 20.1% in males), which also varied between cities. In the adjusted model, female sex, older age, summer and autumn seasons, lower body mass index (<25 kg/m2), and lower high-sensitivity C-reactive protein concentration (<1 mg/L) were associated with higher total 25(OH)D concentrations. This study could provide an exact understanding of the status of vitamin D and help devise strategies to prevent vitamin D deficiency among the Korean population.

Is it Time to Migrate to Liquid Chromatography Automated Platforms in the Clinical Laboratory? A Brief Point of View

Liquid chromatography coupled to mass spectrometry already started to surpass the major drawbacks in terms of sensitivity, specificity and cross-reactivity that some analytical methods used in the clinical laboratory exhibit. This hyphenated technique is already preferred for specific applications while finding its own place in the clinical laboratory setting. However, large-scale usage, high-throughput analysis and lack of automation emerge as shortcomings that liquid chromatography coupled to mass spectrometry still has to overrun in order to be used on a larger scale in the clinical laboratory. The aim of this review article is to point out the present-day position of the liquid chromatography coupled to mass spectrometry technique while trying to understand how this analytical method relates to the basic working framework of the clinical laboratory. This paper offers insights about the main regulation and traceability criteria that this coupling method has to align and comply to, automation and standardization issues and finally the critical steps in sample preparation workflows all related to the high-throughput analysis framework. Further steps are to be made toward automation, speed and easy-to-use concept; however, the current technological and quality premises are favorable for chromatographic coupled to mass spectral methods.

Therapeutic drug monitoring of glycopeptide antimicrobials: An overview of liquid chromatography-tandem mass spectrometry methods

Therapeutic drug monitoring (TDM) is a critical clinical tool used to optimize the safety and effectiveness of drugs by measuring their concentration in biological fluids. These fluids are primarily plasma or blood. TDM, together with real-time dosage adjustment, contributes highly to the successful management of glycopeptide antimicrobial therapies. Understanding pharmacokinetic/pharmacodynamic (PK/PD) properties is vital for optimizing antimicrobial therapies, as the efficacy of these therapies depends on both the exposure of the patient to the drug (PK) and pharmacodynamic (PD) parameters such as the in vitro estimated minimum drug concentration that inhibits bacterial growth (MIC). Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is widely recognized as the gold standard for measuring small molecules, such as antibiotics. This review provides a comprehensive overview of LC-MS/MS methods available for TDM of glycopeptide antibiotics, including vancomycin, teicoplanin, dalbavancin, oritavancin, and telavancin.

Clinical Proteomics for Solid Organ Tissues

The evaluation of biopsied solid organ tissue has long relied on visual examination using a microscope. Immunohistochemistry is critical in this process, labeling and detecting cell lineage markers and therapeutic targets. However, while the practice of immunohistochemistry has reshaped diagnostic pathology and facilitated improvements in cancer treatment, it has also been subject to pervasive challenges with respect to standardization and reproducibility. Efforts are ongoing to improve immunohistochemistry, but for some applications, the benefit of such initiatives could be impeded by its reliance on monospecific antibody-protein reagents and limited multiplexing capacity. This perspective surveys the relevant challenges facing traditional immunohistochemistry and describes how mass spectrometry, particularly liquid chromatography-tandem mass spectrometry, could help alleviate problems. In particular, targeted mass spectrometry assays could facilitate measurements of individual proteins or analyte panels, using internal standards for more robust quantification and improved interlaboratory reproducibility. Meanwhile, untargeted mass spectrometry, showcased to date clinically in the form of amyloid typing, is inherently multiplexed, facilitating the detection and crude quantification of 100s to 1000s of proteins in a single analysis. Further, data-independent acquisition has yet to be applied in clinical practice, but offers particular strengths that could appeal to clinical users. Finally, we discuss the guidance that is needed to facilitate broader utilization in clinical environments and achieve standardization.

Evaluation of the clinical and quantitative performance of a practical HPLC-UV platform for in-hospital routine therapeutic drug monitoring of multiple drugs

BACKGROUND

In-hospital therapeutic drug monitoring (TDM) requires a suitable quantification method for target drugs from the viewpoint of precision, throughput, and testing costs. We previously developed a practical HPLC-UV platform for quantification of serum levels of various drugs. In this report, the platform was effectively applied to the quantification of patient serum levels of five different drugs by clinical professionals in our hospital during their daily work.

METHODS

The residual sera of patients receiving carbamazepine (CBZ), phenytoin (PHT), lamotrigine (LTG), vancomycin (VCM), or voriconazole (VRCZ) were used in the present clinical study. The quantification method for each drug consisted of rapid solid-phase extraction (SPE) of each drug in the patient serum, followed by optimized HPLC-UV analysis of the drug in the SPE eluate. Furthermore, patient serum levels of PHT, CBZ, and VCM were also measured by ligand-binding assay using a cobas® analyzer in our hospital, and those of LTG and VRCZ were measured by HPLC-MS/MS at an outsourced provider. Passing-Bablok regression analysis and Bland-Altman analysis were employed to analyze the agreement of drug levels in patient sera, which was separately quantified using two different methods-our HPLC-UV platform and the cobas analyzer, or HPLC-UV and HPLC-MS/MS.

RESULTS

All analytical conditions of the present method using our HPLC-UV platform were well optimized for each target drug quantification in the patient's serum, and the quantification method for each drug was fully validated for accuracy, precision and reproducibility. Furthermore, Passing-Bablok regression analysis and Bland-Altman analysis revealed that patient serum levels of PHT, CBZ, and VCM quantified by our HPLC-UV platform were closely correlated with those quantified by the cobas® analyzer, and the levels of LTG and VRCZ quantified by our HPLC-UV platform were also correlated with those quantified by HPLC-MS/MS.

CONCLUSIONS

Our HPLC-UV platform can be performed without requiring special analytical techniques. This platform is expected to be used for the measurement of blood levels of multiple drugs for in-hospital routine TDM.

Analytical Concordance of Total Vitamin D on a Fully Automated Random-Access LC-MS/MS Platform

BACKGROUND

The adoption of LC-MS/MS laboratory developed tests in the clinical laboratory is limited by many factors including the lack of automation. Recently, the Cascadion™ clinical analyzer was introduced as a fully automated random-access LC-MS/MS platform. Here, the analytical concordance between the platform and a Roche immunoassay analyzer was investigated for vitamin D analysis in human serum, including samples selected for high triglyceride levels.

METHODS

Analytical precision was evaluated on 3 levels of QC samples (10, 30, and 90 ng/mL) within days (n = 4, 5 days) and between days (20 days). Assay comparison to the Roche was performed using reference samples from the CDC and CAP programs for accuracy. Concordance was also monitored using routine patient samples, as well as samples selected for elevated triglyceride levels (>250 mg/dL).

RESULTS

Precision met manufacturer specifications (<10% CV and <15% bias), whereas the accuracy evaluations showed a linear fit (y = 0.97x - 1.1, r = 0.995) with 1:1 correlation to reference samples, independent of C-3-epi-vitamin D levels. A mean positive bias (11%) was observed for the Roche measurements in normal patient samples, whereas a mean negative bias (-8%) was observed in samples selected for elevated triglyceride levels.

CONCLUSIONS

Cascadion measurements of total vitamin D compared favorably with Roche results in our laboratory, although discordance was observed in the analysis of patient serum, which could be explained in terms of known differences between the 2 assays. However, operational issues need to be addressed to effect clinical adoption.

Point of care assay for blood aripiprazole concentrations: development, validation and utility

BACKGROUND

The antipsychotic aripiprazole is often used in the treatment of first-episode psychosis. Measuring aripiprazole blood levels provides an objective measure of treatment adherence, but this currently involves taking a venous blood sample and sending to a laboratory for analysis.

AIMS

To detail the development, validation and utility of a new point of care (POC) test for finger-stick capillary blood concentrations of aripiprazole.

METHOD

Analytical performance (sensitivity, precision, recovery and linearity) of the assay were established using spiked whole blood and control samples of varying aripiprazole concentration. Assay validation was performed over a 14-month period starting in July 2021. Eligible patients were asked to provide a finger-stick capillary sample in addition to their usual venous blood sample. Capillary blood samples were tested by the MyCare™ Insite POC analyser, which provided measurement of aripiprazole concentration in 6 min, and the venous blood sample was tested by the standard laboratory method.

RESULTS

A total of 101 patients agreed to measurements by the two methods. Venous blood aripiprazole concentrations as assessed by the laboratory method ranged from 17 to 909 ng/mL, and from 1 to 791 ng/mL using POC testing. The correlation coefficient between the two methods (r) was 0.96 and there was minimal bias (slope 0.91, intercept 4 ng/ml).

CONCLUSIONS

The MyCare Insite POC analyser is sufficiently accurate and reliable for clinical use. The availability of this technology will improve the assessment of adherence to aripiprazole and the optimising of aripiprazole dosing.

An effective pretreatment technique based on multi-walled carbon nanotubes to reduce the matrix effect in plasma samples analyzed by a new type probe electrospray ionization method

The quantitative analysis of drug plasma samples plays an important role in the drug development and drug clinical use. Our research team developed a new electrospray ion source-Micro probe electrospray ionization (μPESI) in the early stage, which was combined with mass spectrometry (μPESI-MS/MS) showing good qualitative and quantitative analysis performance. However, matrix effect severely interfered the sensitivity in μPESI-MS/MS analysis. To solve this problem, we recently developed a Solid-phase purification method based on multi-walled carbon nanotubes (MWCNTs), which was used for removing matrix interfering substances (especially phospholipid compounds) in the preparation of plasma samples, so as to reduce the matrix effect. In this study, aripiprazole (APZ), carbamazepine (CBZ) and omeprazole (OME) were used as representative analytes, the quantitative analysis related to the plasma samples spiked with the analytes above and the mechanism of the MWCNTs to reduce matrix effect were both investigated. Compared with the ordinary protein precipitation, MWCNTs could reduced the matrix effect for several to dozens of times, which resulting from the removement of phospholipid compounds from the plasma samples by MWCNTs in the selective adsorption manner. We further validated the linearity, precision and accuracy of this pretreatment technique by the μPESI-MS/MS method. These parameters all met the requirements of FDA guidelines. It was showed that MWCNTs have a good application prospect in the drug quantitative analysis of plasma samples using the μPESI-ESI-MS/MS method.

Comparison between one and two-dimensional liquid chromatographic approaches for the determination of plasmatic stroke biomarkers by isotope dilution and tandem mass spectrometry

This work presents the evaluation of one- and two-dimensional liquid chromatography for the quantification of three stroke outcome predictors in plasma. Isotopically labelled analogues of L-arginine (L-Arg), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are used to quantify the three analytes by isotope dilution and tandem mass spectrometry. Chromatographic isotope effects were not observed between natural L-Arg and its ¹⁵N-labelled analogue but they were observed between natural ADMA and SDMA and their multiple deuterated analogues. Under these conditions, bidimensional chromatography through the use of an automated multiple heart cutting mode provided unsatisfactory results for ADMA and SDMA due to the different amounts of natural and labelled compounds transferred from the first to the second chromatographic dimension. In contrast, using one dimensional liquid chromatography after a derivatization step to esterify carboxylic groups, chromatographic isotope effects did not alter the initial mass balance as full coelution of natural and labelled analogues or baseline resolution between the analytes was not required. This method was successfully validated following the Clinical & Laboratory Standards Institute guidelines and applied to the analysis of plasma samples from patients who had suffered from an intraparenchymal haemorrhagic stroke.

Pharmacological data science perspective on fatal incidents of morphine treatment

Morphine prescribed for analgesia has caused drug-related deaths at an estimated incidence of 0.3% to 4%. Morphine has pharmacological properties that make it particularly difficult to assess the causality of morphine administration with a patient's death, such as its slow transfer between plasma and central nervous sites of action and the existence of the active metabolite morphine-6-glucuronide with opioid agonistic effects, Furthermore, there is no well-defined toxic dose or plasma/blood concentration for morphine. Dosing is often adjusted for adequate pain relief. Here, we summarize reported deaths associated with morphine therapy, including associated morphine exposure and modulating patient factors such as pharmacogenetics, concomitant medications, or comorbidities. In addition, we systematically analyzed published numerical information on the stability of concentrations of morphine and its relevant metabolites in biological samples collected postmortem. A medicolegal case is presented in which the causality of morphine administration with death was in dispute and pharmacokinetic modeling was applied to infer the administered dose. The results of this analytical review suggest that (i) inference from postmortem blood concentrations to the morphine dose administered has low validity and (ii) causality between a patient's death and the morphine dose administered remains a highly context-dependent and collaborative assessment among experts from different medical specialties.

Magnetic Molecularly Imprinted Polymers for the Rapid and Selective Extraction and Detection of Methotrexatein Serum by HPLC-UV Analysis

In this work, novel selective recognition materials, namely magnetic molecularly imprinted polymers (MMIPs), were prepared. The recognition materials were used as pretreatment materials for magnetic molecularly imprinted solid-phase extraction (MSPE) to achieve the efficient adsorption, selective recognition, and rapid magnetic separation of methotrexate (MTX) in the patients' plasma. This method was combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) to achieve accurate and rapid detection of the plasma MTX concentration, providing a new method for the clinical detection and monitoring of the MTX concentration. The MMIPs for the selective adsorption of MTX were prepared by the sol-gel method. The materials were characterized by transmission electron microscopy, Fourier transform-infrared spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry. The MTX adsorption properties of the MMIPs were evaluated using static, dynamic, and selective adsorption experiments. On this basis, the extraction conditions were optimized systematically. The adsorption capacity of MMIPs for MTX was 39.56 mgg^-1, the imprinting factor was 9.40, and the adsorption equilibrium time was 60 min. The optimal extraction conditions were as follows: the amount of MMIP was 100 mg, the loading time was 120 min, the leachate was 8:2 (v/v) water-methanol, the eluent was 4:1 (v/v) methanol-acetic acid, and the elution time was 60 min. MTX was linear in the range of 0.00005-0.25 mg mL^-1, and the detection limit was 12.51 ng mL^-1. The accuracy of the MSPE-HPLC-UV method for MTX detection was excellent, and the result was consistent with that of a drug concentration analyzer.

Advances in detecting N6-methyladenosine modification in circRNAs

Circular RNAs (circRNAs) are a class of noncoding RNAs with covalently single-stranded closed loop structures derived from back-splicing event of linear precursor mRNAs (pre-mRNAs). N6-methyladenosine (m⁶A), the most abundant epigenetic modification in eukaryotic RNAs, has been shown to play a crucial role in regulating the fate and biological function of circRNAs, and thus affecting various physiological and pathological processes. Accurate identification of m⁶A modification in circRNAs is an essential step to fully elucidate the crosstalk between m⁶A and circRNAs. In recent years, the rapid development of high-throughput sequencing technology and bioinformatic methodology has propelled the establishment of a multitude of approaches to detect circRNAs and m⁶A modification, including in vitro-based and in silico methods. Based on this, the research community has started on a new journey to develop methods for identification of m⁶A modification in circRNAs. In this review, we provide a comprehensive review and evaluation of the existing methods responsible for detecting circRNAs, m⁶A modification, and especially, m⁶A modification in circRNAs, which mainly focused on those developed based on high-throughput technologies and methodology of bioinformatics. This handy reference can help researchers figure out towards which direction this field will go.

DNA N6-Methyladenine Modification in Eukaryotic Genome

DNA methylation is treated as an important epigenetic mark in various biological activities. In the past, a large number of articles focused on 5 mC while lacking attention to N6-methyladenine (6 mA). The presence of 6 mA modification was previously discovered only in prokaryotes. Recently, with the development of detection technologies, 6 mA has been found in several eukaryotes, including protozoans, metazoans, plants, and fungi. The importance of 6 mA in prokaryotes and single-celled eukaryotes has been widely accepted. However, due to the incredibly low density of 6 mA and restrictions on detection technologies, the prevalence of 6 mA and its role in biological processes in eukaryotic organisms are highly debated. In this review, we first summarize the advantages and disadvantages of 6 mA detection methods. Then, we conclude existing reports on the prevalence of 6 mA in eukaryotic organisms. Next, we highlight possible methyltransferases, demethylases, and the recognition proteins of 6 mA. In addition, we summarize the functions of 6 mA in eukaryotes. Last but not least, we summarize our point of view and put forward the problems that need further research.

Global and Comparative Proteome Signatures in the Lens Capsule, Trabecular Meshwork, and Iris of Patients With Pseudoexfoliation Glaucoma

Pseudoexfoliation (PXF) is characterized by the accumulation of the exfoliative material in the eye and high rates of blindness if left untreated. Pseudoexfoliation glaucoma (PXG) is generally diagnosed too late due to its asymptomatic nature, necessitating the development of new effective screening tools for the early diagnosis of the disease. Thus, the increasing prevalence of this disease due to an aging population has demanded the identification of suitable biomarkers for the early detection of the disease or detection of the onset of glaucoma in the eyes with PXF. We applied a proteomics strategy based on a high-throughput screening method for the determination of proteins involving PXF and PXG pathogenesis. The lens capsule (LC), iris, and trabecular meshwork (TM) samples with PXF and PXG were taken by surgical trabeculectomy, and control samples were taken from the donor corneal buttons obtained from the institutional eye bank to characterize the proteome profile. Peptides from the LC were analyzed using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The protein of interest and cytokine/chemokine profiles were verified using immunohistochemistry and the bio-plex kit assay, respectively. There were a total of 1433 proteins identified in the human LC, of which 27 proteins were overexpressed and eight proteins were underexpressed in PXG compared with PXF. Overexpressed proteins such as fibromodulin, decorin, lysyl oxidase homolog 1, collagen alpha-1(I) chain, collagen alpha-3(VI) chain, and biglycan were the major components of the extracellular matrix (ECM) proteins involved in cell-matrix interactions or ECM proteoglycans and the assembly and cross-linking of collagen fibrils. The ECM composition and homeostasis are altered in glaucoma. Thus, quantitative proteomics is a method to discover molecular markers in the eye. Monitoring these events can help evaluate disease progression in future studies.

Erythrocyte Storage Lesion Improvements Mediated by Naringin Screened from Vegetable/Fruit Juice Using Cell Extract and HPLC-MS

In blood banking, storage at 4°C for weeks is known to cause damages to erythrocytes, called storage lesions that may later cause transfusion-related adverse events. In previous experiments, we found that vegetable/fruit juices can effectively reduce the storage lesion. Currently, we attempt to analyze the potential bioactive components and test whether the compounds can improve the storage lesions of erythrocytes. Equal portions in wet weight of 20 fresh vegetables and fruits were blended with phosphate buffered solution (PBS), and clear solutions were produced as additive to the packed erythrocytes from consented blood donors at 1 : 10 ratio (ml : gram). The blood samples were stored for 35 days at 4°C, and the supernatants were performed high liquid chromatography-mass spectrometry (HPLC-MS) analysis at 0 days, 14 days, and 35 days. The blood bags supplemented with identified bioactive components were stored in a refrigerator for 35 days, and the morphology, complete blood count (CBC), phosphatidylserine (PS) extroversion, hemolysis, and reactive oxygen species (ROS) levels were measured at the end of storage. Five potential bioactive components from vegetable/fruit juices contributed to the improvements of storage lesion. One of the compounds was unequivocally identified as naringin, and two were tentatively assigned as vitexin 6″-O-malonyl 2″-O-xyloside and luteolin 7-(6″-malonyl neohesperidoside). Naringin alleviated the storage lesion of red blood cells (RBCs) by reducing ROS levels and living cell extraction with HPLC-MS is a simple, reliable, and effective method for screening potential bioactive components.

A sensitive and simple HPLC-FLD-based method for the measurement of intracellular glucose uptake

Glucose is a primary source of energy used in most organisms. Thus, development of reliable approaches to measure intracellular glucose uptake is an important research issue. 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG), as a fluorescent glucose derivative, has been widely used to track intracellular glucose uptake by fluorescence imaging and measuring in mammalian cells. However, the avoid-less cross-interference of intrinsic autofluorescence background and tested fluorescent compounds limits its ability to provide trustworthy information on intracellular glucose uptake. By the extraction, separation and detection of 2-NBDG, a simple, sensitive and accurate HPLC-FLD method was established and validated for the measurement of intracellular glucose uptake in HepG2 cells. The developed method has been employed successfully to assess the glucose uptake activity of anti-diabetic drugs and fluorescent natural products. A fit-for-purpose partial validation was further performed for quantification and comparison of glucose uptake in AML12, LO2 hepatocytes, L6 myoblasts and 3T3-L1 preadipocytes.

Phytohormone profiles and related gene expressions after endodormancy release in developing Pinus tabuliformis male strobili

Development after endo-dormancy release ensures perennial plants, such as forest trees, proper response to environmental changes and enhances their adaptability. In northern hemisphere, megasporophore and microsporophore of conifers undergo dormancy to complete their development. Here combined with transcriptome data, we used high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (ESI-HPLC-MS/MS) to quantitatively analyse the various hormones (Abscisic Acid (ABA), 3-Indoleacetic acid (IAA), Gibberellins (GAs), Cytokinin (CTK), Jasmonic acid (JA) and Salicylic acid (SA)) of Chinese pine (Pinus tabuliformis Carr.) male strobili after endo-dormancy release. More specifically, we analysed endogenous hormones and their related-genes and verified the important role of ABA in plants growth and development. We observed rapid decrease in ABA content after dormancy release, resulting in reducing the inhibitory effect on male strobili growth. Similarly, rapid drop in ABA/GA ratio was observed and was associated with the start of male strobili growth and development. Combined with transcriptome data, we found that HAB2-SnRK2.10 played a central role in the ABA pathway in the entire network of hormones regulating male strobili development. Due to external environment warming, the differentially expressed HAB2-SnRK gene led to ABA content rapid decline, thus initiating male strobili growth. We constructed a network of hormone-regulated development to understand the interactions between hormones after male strobili dormancy release of male strobili. This study provided essential foundations for studying megasporophore and microsporophore growth mechanism after endo-dormancy and offered new ideas for flower development in gymnosperms and angiosperms.

Development of Chromium(III) Selective Potentiometric Sensors for Its Determination in Petroleum Water Samples Using Synthesized Nano Schiff Base Complex as an Ionophore

BACKGROUND

Many analytical techniques, such as X-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and even traditional spectroscopic and fluorimetric methods, are used for the measurement of Cr(III) ions. These methods are sophisticated and very expensive. So, the chipset and the low cost ion selective electrodes were used.

OBJECTIVE

The quantification of Cr(III) ions in various samples of petroleum water using ion selective electrodes was suggested. Nano chromium modified carbon paste sensor (MCPE) and nano chromium modified screen printed sensor (MSPE) based on Schiff base Cr(III) complex are developed.

METHOD

The developed nano Cr(III) Schiff base chelate was characterized utilizing elemental, spectroscopic, and thermal analysis techniques. The proposed nano Cr(III) has a good properties for antibacterial and antifungal activity. The modified carbon paste and screen-printed sensors were fabricated for determination of Cr(III) ion.

RESULT

The proposed MCPE (sensor I) and MSPE (sensor II) obeys Nernstian equation upon incorporating nono Cr(III) ionophore in the paste at 25 °C with a trivalent cationic slope of 18.8 ± 0.2 and 20.0 ± 0.4 mV/decade. They have showed fast response time around 8 and 5 s, and they may be utilized for at least 98 and 240 days without significant changes in MCPE and MSPE potential, respectively. The sensors I and II showed good selectivity for Cr(III) ion toward a wide variety of metal ions or anions as confirmed by potentiometric selectivity coefficients values. The detection and quantification limits were defined alongside the other process validation parameters. The results have been compared well to those obtained by atomic absorption spectrometry (AAS) and the data of F- and t-test indicated no significant difference between the proposed and AAS methods.

CONCLUSION

These sensors have been utilized to determine Cr(III) ions in genuine spiked different petroleum well water samples with satisfactory percentage recoveries, low standard and relative standard deviation values using direct potentiometric and standard addition methods. The proposed method of producing nano Cr(III) complex as a sensor material possesses the distinct advantages of being simple, easily reproducible, appropriate for operation, and highly selective and sensitive.

HIGHLIGHTS

Modified carbon paste and screen-printed electrodes were fabricated based on nano Cr(III) complex as ionophore. The electrodes follow Nernstian behavior and they optimized according to IUPAC recommendation. They showed a high selectivity for Cr(III) ion over many bi or trivalent metal ions and anions. The results obtained compared well with those obtained using atomic absorption spectrometry (AAS). They successfully applied for determination of Cr(III) in petroleum water samples.

Collision energy-breakdown curves - An additional tool to characterize MS/MS methods

Background

In tandem mass spectrometry, analyte detection is based on collision-induced fragmentation, which is modulated by the collision energy (CE) setting. Variation in CE leads to differential ion yield, and optimization is usually performed empirically as "tuning" during method development. Our aim was to build a method to objectify the impact of collision energy settings on ion yield for individual compounds.

Methods

Collision energy (CE)-breakdown curves were generated based on acquisition files in which a large number of quasi-identical mass transitions were recorded simultaneously, with variation of CE over a defined range within a single injection. Ion yield (normalized to an internal standard recorded with a locked collision energy) was plotted as a curve versus CE settings. Piperacillin and testosterone were studied as exemplary analytes in matrix-free and serum matrix-based liquid chromatography tandem mass spectrometry (LC-MS/MS) measurements. More detailed testosterone CE-breakdown curves were investigated with regard to sample preparation techniques and the isotope labeling pattern of corresponding internal standards.

Results

CE-breakdown curves were found characteristically for the piperacillin quantifier transition with respect to CE-related maximum ion yield, as well as curve width and shape. A diverging curve profile was observed for the piperacillin qualifier transition. For testosterone analyses, no impact from different sample preparation techniques or the isotope labeling patterns on the selected CE was shown.

Conclusion

CE-breakdown curves are a convenient and valuable tool to verify LC-MS/MS methods regarding consistent fragmentation characteristics between sample sources or native analytes and isotope-labeled counterparts.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) based assay for the simultaneous quantification of 18-hydroxycorticosterone, 18-hydroxycortisol and 18-oxocortisol in human plasma

18-hydroxycorticosterone (18-OHB), 18-hydroxycortisol (18-OHF) and 18-oxocortisol (18-OXOF) are important biomarkers for the diagnosis of subtypes of primary aldosteronism. The detection of these three analytes by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is free from structurally similar compounds. The aim of this study was to develop and validate a new LC-MS/MS assay for the simultaneous quantification of 18-OHB, 18-OHF and 18-OXOF in plasma and to establish a reference intervals for apparently healthy population. Plasma samples were prepared by solid phase extraction and separated in an ultra-high performance reversed phase column. MS detection was achieved using a triple quadrupole mass spectrometer in both positive and negative ionization modes. The developed assay was then validated against standard guidelines. We collected 691 plasma samples from apparently healthy individuals (M:398, F:293) to establish the reference intervals. The analytes were separated and quantified within 5 min. The newly developed method demonstrated linearity for the detected steroid concentration in range of 5 to 3000 pg/ml for 18-OXOF (r² = 0.999) and 20 to 3000 pg/ml for 18-OHB (r² = 0.997) and 18-OHF (r² = 0.997). The lower limit of quantification (LLOQ) was 2.5 pg/ml, 20 pg/ml and 20 pg/m for 18-OXOF, 18-OHB and 18-OHF respectively. Specificity, precision, accuracy and stability were tested, and met the requirements of the guidelines. 18-OHB was higher in females than in males, but 18-OHF were higher in males than females. The reference intervals of 18-OHB, 18-OHF and 18-OXOF for both genders together were 90.5-1040.6 pg/ml, 224.4-1685.2 pg/ml, 4.0-70.5 pg/ml, respectively. Age was also an important factor influencing the levels of these three hormones. We have developed a sensitive and reliable method for the simultaneous quantification of 18-OHB, 18-OHF, and 18-OXOF. Our work provides a reference interval for the clinical application of these three steroid hormones.

Discovery of metabolic biomarkers for gestational diabetes mellitus in a Chinese population

Background

Gestational diabetes mellitus (GDM), one of the most common pregnancy complications, can lead to morbidity and mortality in both the mother and the infant. Metabolomics has provided new insights into the pathology of GDM and systemic analysis of GDM with metabolites is required for providing more clues for GDM diagnosis and mechanism research. This study aims to reveal metabolic differences between normal pregnant women and GDM patients in the second- and third-trimester stages and to confirm the clinical relevance of these new findings.

Methods

Metabolites were quantitated with the serum samples of 200 healthy pregnant women and 200 GDM women in the second trimester, 199 normal controls, and 199 GDM patients in the third trimester. Both function and pathway analyses were applied to explore biological roles involved in the two sets of metabolites. Then the trimester stage-specific GDM metabolite biomarkers were identified by combining machine learning approaches, and the logistic regression models were constructed to evaluate predictive efficiency. Finally, the weighted gene co-expression network analysis method was used to further capture the associations between metabolite modules with biomarkers and clinical indices.

Results

This study revealed that 57 differentially expressed metabolites (DEMs) were discovered in the second-trimester group, among which the most significant one was 3-methyl-2-oxovaleric acid. Similarly, 72 DEMs were found in the third-trimester group, and the most significant metabolites were ketoleucine and alpha-ketoisovaleric acid. These DEMs were mainly involved in the metabolism pathway of amino acids, fatty acids and bile acids. The logistic regression models for selected metabolite biomarkers achieved the area under the curve values of 0.807 and 0.81 for the second- and third-trimester groups. Furthermore, significant associations were found between DEMs/biomarkers and GDM-related indices.

Conclusions

Metabolic differences between healthy pregnant women and GDM patients were found. Associations between biomarkers and clinical indices were also investigated, which may provide insights into pathology of GDM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00606-8.

Total Value of Ownership and Overall Equipment Effectiveness analysis to evaluate the impact of automation on time and costs of therapeutic drug monitoring

Total Value of Ownership (TVO) and Overall Equipment Effectiveness (OEE) analysis are novel tools capable of monitoring and analyzing industrial processes by assessing the efficiency of the entire instrumental equipment and calculating instrument capacity utilization. Such integrated analysis, measuring quality indicators of the testing process, could also provide new perspectives and methodologies for the workflow organization of clinical laboratories. In this study, TVO and OEE were employed for the evaluation of two different configurations of a therapeutic drug monitoring sector, comparing the results obtained for immunosuppressant (ISD) and anti-epileptic drugs (AED) analysis as well as checking their quantitative performance in terms of limit of quantification, accuracy and precision. TVO analysis was performed for ISDs, including the Total Direct Labor Time, Total Cycle Time and Turnaround Time as well as cost of testing. Instruments' performance and workload were assessed using OEE indicator, studying Availability, Performance and Quality factors. Total Cycle Time for a batch was 3.55 h, decreasing of 1.5 h in the new setting where personnel are engaged for 0.98 h, 25% of total testing time. The calculated cost per sample was 6.60 euro. Availability values were significantly higher for automated sample-handling system and ISDs analysis by LC-MS. Higher Performance values were obtained for LC-MS system for AED and other TDM. Quality values were >0.94 for all instruments. TVO and OEE proved to be applicable to clinical laboratory environment, quantifying benefits and costs of newly developed semi-automated therapeutic drug monitoring sector. This novel approach based on an integrated analysis may help activity planning and quality improvement and could be used in the future for benchmarking progress as a product/process comparison tool in other laboratory fields.

Comprehensive and Rapid Quality Evaluation Method for the Ayurvedic Medicine Divya-Swasari-Vati Using Two Analytical Techniques: UPLC/QToF MS and HPLC-DAD

Divya-Swasari-Vati (DSV) is a calcium-containing herbal medicine formulated for the symptomatic control of respiratory illnesses observed in the current COVID-19 pandemic. DSV is an Ayurvedic medicine used for the treatment of chronic cough and inflammation. The formulation has shown its pharmacological effects against SARS-CoV-2 induced inflammation in the humanized zebrafish model. The present inventive research aimed to establish comprehensive quality parameters of the DSV formulation using validated chromatographic analytical tools. Exhaustive identification of signature marker compounds present in the plant ingredients was carried out using ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/QToF MS). This was followed by simultaneous estimation of selected marker components using rapid and reliable high-performance liquid chromatography (HPLC) analysis. Eleven marker components, namely gallic acid, protocatechuic acid, methyl gallate, ellagic acid, coumarin, cinnamic acid, glycyrrhizin, eugenol, 6-gingerol, piperine and glabridin, were selected out of seventy-four identified makers for the quantitative analysis in DSV formulation. Validation of the HPLC method was evaluated by its linearity, precision, and accuracy tests as per the International Council of Harmonization (ICH) guidelines. Calibration curves for the eleven marker compounds showed good linear regression (r2 > 0.999). The relative standard deviation (RSD) value of intraday and interday precision tests were within the prescribed limits. The accuracy test results ranged from 92.75% to 100.13%. Thus, the present inclusive approach is first of its kind employing multi-chromatographic platforms for identification and quantification of the marker components in DSV, which could be applied for routine standardization of DSV and other related formulations.

Point-of-care measurement of clozapine concentration using a finger-stick blood sample

BACKGROUND

The use of clozapine demands regular monitoring of clozapine plasma concentrations and of white blood cell parameters. The delay between sending blood samples for analysis and receiving the results hinders clinical care. Point-of-care testing (POCT) can provide drug assay results within a few minutes.

AIM

This study aimed to investigate the utility of a novel point-of-care device that can measure clozapine concentrations using capillary blood samples collected via a finger stick.

METHOD

During a five-week period starting in June 2019 eligible patients were asked to provide a finger-stick capillary sample in addition to their usual venous blood sample. Samples were analysed by the novel point-of-care device and by the standard laboratory method. Capillary blood samples were tested by the MyCare™ Insite POCT analyser, and a quantitative measurement of clozapine concentration was provided within six minutes.

RESULTS

A total of 309 patients agreed to measurements by the two methods. Analysis revealed clozapine concentrations in venous blood as determined by the laboratory method ranged from 20 to 1310 ng/mL and by POCT from 7 to 1425 ng/mL. There was a strong positive correlation (R = 0.89) between the results from the venous and the capillary sample methods. The slope of the association between standard assay and MyCare™ Insite was 1.0 with an intercept of -21 ng/mL, indicating minimal bias.

CONCLUSION

Clozapine concentrations can be accurately measured at the point of care using capillary blood samples collected via a finger stick. This approach may be more acceptable than venous sampling to patients and, with almost instant results available, more useful to clinicians.

Outcomes in treatment-resistant schizophrenia: symptoms, function and clozapine plasma concentrations

BACKGROUND

Clozapine is the only medication licenced for treating patients with treatment-refractory schizophrenia. However, there are no evidence-based guidelines as to the optimal plasma level of clozapine to aim for, and their association with clinical and functional outcome.

OBJECTIVE

We assessed the relationship between clinical and functional outcome measures and blood concentrations of clozapine among patients with treatment-refractory psychosis.

METHODS

Data were reviewed in 82 patients with treatment-refractory psychosis admitted to a specialised tertiary-level service and treated with clozapine. Analysis focussed on the relationship between clozapine and norclozapine plasma concentrations and the patient's clinical symptoms and functional status.

RESULTS

Clinical symptom improvement was positively correlated with norclozapine plasma concentrations and inversely correlated with clozapine to norclozapine plasma concentrations ratio. Clozapine concentrations showed a bimodal association with clinical improvement (peaks around 350 and 660 ng/ml). Clinical symptom improvement correlated with functional outcomes, although there was no significant correlation between the latter and clozapine or norclozapine plasma concentrations.

CONCLUSION

Clozapine treatment was associated with optimal clinical improvement at two different peak plasma concentrations around 350 and 650 ng/ml. Clinical improvement was associated with functional outcome; however, functionality was not directly associated with clozapine concentrations. A subset of patients may require higher clozapine plasma concentrations to achieve clinical improvement.

Perfluorooctanesulfonic Acid Detection Using Molecularly Imprinted Polyaniline on a Paper Substrate

Perfluorinated compounds like perfluorooctanesulfonic acid (PFOS) are synthetic water pollutants and have accumulated in environments for decades, causing a serious global health issue. Conventional assays rely on liquid chromatography and mass spectroscopy that are very expensive and complicated and thus limit the large-scale monitoring of PFOS in wastewater. To achieve low-cost and accurate detection of PFOS, we designed a paper-based sensor with molecularly imprinted polyaniline electrodes that have recognition sites specific to PFOS. The calibration curve of resistivity ratios as a function of PFOS concentrations has a linear range from 1 to 100 ppt with a coefficient of determination of 0.995. The estimated limit of detection is 1.02 ppt. We also investigated attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) spectra of the surface of the polyaniline (PANI) electrodes to propose the potential recognition sites in polyaniline matrix and the detection mechanism. This electrical paper sensor with low cost and excellent sensitivity and selectivity provides the potential for large-scale monitoring of wastewater.

A systematic review on chromatography-based method validation for quantification of vancomycin in biological matrices

A fully validated bioanalytical methods are prerequisite for pharmacokinetic and bioequivalence studies as well as for therapeutic drug monitoring. Due to high pharmacokinetic variability and narrow therapeutic index, vancomycin requires reliable quantification methods for therapeutic drug monitoring. To identify published chromatographic based bioanalytical methods for vancomycin in current systematic review, PubMed and ScienceDirect databases were searched. The selected records were evaluated against the method validation criteria derived from international guidelines for critical assessment. The major deficiencies were identified in method validation parameters specifically for accuracy, precision and number of calibration and validation standards, which compromised the reliability of the validated bioanalytical methods. The systematic review enacts to adapt the recommended international guidelines for suggested validation parameters to make bioanalysis reliable.

Local aromatase activity alterations in breast cancer tissues: A potential way of decision support for clinicians

BACKGROUND AND AIMS

It is becoming evident that local estrogen exposure is important in postmenopausal breast cancer patients. The microenvironment is established by breast stromal cells based on communication with tumor cells that is essential to cancer development, invasion, and metastasis. Here we investigated aromatase activity levels in both tumor and matched stromal tissues by showing their impact on the manufacturing of local estrogen and tumor progression in cases of invasive ductal carcinoma (IDC).

METHODS

Tumor (T) and tumor-associated stroma (TAS) neighboring tissues were acquired from each postmenopausal patient, diagnosed with IDC, and categorized as luminal A (n = 20). The control group was formed from tumor-free breast tissue samples (N, n = 12). A microsomal-based technique was created to compare breast tissue aromatase activities using liquid chromatography - mass spectrometry.

FINDINGS

We observed that the TAS tissues have the highest aromatase activities (p < 0.05). High progesterone receptor (PR) intensity levels were found to be decreasing the activity level in these tissues significantly (p < 0.05). Tumor tissue specific aromatase activity levels of postmenopausal patients' were tend to be lower compared to healthy premenopausal subjects' (3 fold, p < 0.001). In addition low activity in tumor tissues were associated with low grade and late stage cancers.

CONCLUSIONS

Early detection and personalized therapy is essential for postmenopausal breast cancer patients. Together, our in-house tandem mass spectrometry technique has the potential for further development and standardization for the measurement of aromatase activity and may assist clinicians decide on therapy policies for postmenopausal IDC patients which could be an invaluable asset for precise and specific evaluation.

The Potential of Steroid Profiling by Mass Spectrometry in the Management of Adrenocortical Carcinoma

Radiological and endocrinological work up of adrenal neoplasms is aimed at distinguishing between frequent non-functioning adenomas and rare but very aggressive adrenocortical carcinoma (ACC). Relevant research has addressed the identification of molecular, genetic and hormonal markers that could have clinical significance for malignancy, as well as a prognostic value. Regarding endocrine aspects, attention has been paid to the pattern of steroid secretion that can be affected by altered steroidogenic pathway in ACC. The advent of mass spectrometry techniques has overcome many limitations usually associated with immunoassays, allowing the determination of both common and rarely measured steroids in a single analysis with high specificity and sensitivity. Indeed, mass spectrometry strategies may be able to identify an individualized steroid profile of ACC, allowing a rapid diagnosis and a specific follow-up. In this review, insights, strengths and limitations of mass spectrometry-based approaches in steroid profiling, as well as of immunoassay in steroid measurements, will be specifically discussed. Moreover, the latest findings on steroid profiling by mass spectrometry-based techniques, the most promising analytical tool, will be summarized to evaluate if steroid profiling might be the clue for solving the clinical dilemma in differentiating ACC from non-functioning adrenocortical adenomas (ACA).

After another decade: LC-MS/MS became routine in clinical diagnostics

Tandem mass spectrometry - especially in combination with liquid chromatography (LC-MS/MS) - is applied in a multitude of important diagnostic niches of laboratory medicine. It is unquestioned in its routine use and is often unreplaceable by alternative technologies. This overview illustrates the development in the past decade (2009-2019) and intends to provide insight into the current standing and future directions of the field. The instrumentation matured significantly, the applications are well understood, and the in vitro diagnostics (IVD) industry is shaping the market by providing assay kits, certified instruments, and the first laboratory automated LC-MS/MS instruments as an analytical core. In many settings the application of LC-MS/MS is still burdensome with locally lab developed test (LDT) designs relying on highly specialized staff. The current routine applications cover a wide range of analytes in therapeutic drug monitoring, endocrinology including newborn screening, and toxicology. The tasks that remain to be mastered are, for example, the quantification of proteins by means of LC-MS/MS and the transition from targeted to untargeted omics approaches relying on pattern recognition/pattern discrimination as a key technology for the establishment of diagnostic decisions.

Serum Steroid Profiling by Liquid Chromatography-Tandem Mass Spectrometry for the Rapid Confirmation and Early Treatment of Congenital Adrenal Hyperplasia: A Neonatal Case Report

Congenital adrenal hyperplasia (CAH) describes a group of autosomal recessive disorders of steroid biosynthesis, in 95% of cases due to 21-hydroxylase deficiency. The resulting hormonal imbalances lead to increased 17-hydroxyprogesterone and androgens levels, at the expense of decreased concentrations of glucocorticoids and, in some cases, of mineralocorticoids. A variety of clinical presentations accompany a range of severities, which are described as different forms of CAH, and are the result of these hormonal imbalances. The incidence of CAH worldwide is approximately 1 in 15,000 live births, and is population-dependent; thus, its inclusion in neonatal screening tests is widely discussed. Diagnosis of CAH is based on the quantification of 17-hydroxyprogesterone, usually by immunoassay, which has low specificity and high false-positive rates, resulting in a relatively high demand for a second-tier confirmation test. We report a case of a newborn recognized as female at birth, but showing ambiguous genitalia and other CAH clinical features, including hypernatremia, in the first days of life. In addition to the classical assays, liquid chromatography–tandem mass spectrometry was used to determine the serum steroid profile, allowing for the accurate and simultaneous quantification of seven steroids in the same analysis. Such an application immediately revealed an alteration in the levels of specific steroids related to CAH, leading to an early intervention by hormone replacement therapy. Subsequently, the diagnosis of classic CAH due to 21-hydroxylase deficiency was further confirmed by molecular testing.

Multi-Omics Approach for Studying Tears in Treatment-Naïve Glaucoma Patients

Primary open-angle glaucoma (POAG) represents the leading cause of irreversible blindness worldwide and is a multifactorial, chronic neurodegenerative disease characterized by retinal ganglion cell and visual field loss. There are many factors that are associated with the risk of developing POAG, with increased intraocular pressure being one of the most prevalent. Due to the asymptomatic nature of the disease, the diagnosis of POAG often occurs too late, which necessitates development of new effective screening strategies for early diagnosis of the disease. However, this task still remains unfulfilled. In order to provide further insights into the pathophysiology of POAG, we applied a targeted metabolomics strategy based on a high-throughput screening method for the determination of tear amino acids, free carnitine, acylcarnitines, succinylacetone, nucleosides, and lysophospholipids in naïve to therapy glaucomatous patients and normal controls. Also, we conducted proteomic analyses of the whole lacrimal fluid and purified extracellular vesicles obtained from POAG patients and healthy subjects. This multi-omics approach allowed us to conclude that POAG patients had lower levels of certain tear amino acids and lysophospholipids compared with controls. These targeted analyses also highlighted the low amount of acetylcarnitine (C2) in POAG patient which correlated well with proteomics data. Moreover, POAG tear proteins seemed to derive from extracellular vesicles, which carried a specific pro-inflammatory protein cargo.

Microflow UPLC and high-resolution MS as a sensitive and robust platform for quantitation of intact peptide hormones

Aim: Recent advances in microflow ultra performance liquid chromatography (UPLC) systems offer higher sensitivity with robustness to meet the routine bioanalytical demands. Modern high-resolution mass spectrometers (HRMS) enable the development of highly selective methods with broad dynamic range. Results: The quantitative performances of tandem quadrupole MS and HRMS were comprehensively compared using seven intact peptide hormones up to 9.4 kDa. Results show comparable performance between two platforms in sensitivity, accuracy and linearity. For some peptides, HRMS provided lower background interference. The benefit of increased sensitivity using microflow UPLC was also demonstrated. Conclusion: HRMS is a versatile platform capable of both basic characterization and reliable quantitation in complex matrices. Microflow UPLC provides lower LLOQs than conventional flow systems, even with less sample volume injected.

Quantification of apixaban in human plasma using ultra performance liquid chromatography coupled with tandem mass spectrometry

Apixaban, an inhibitor of direct factor Xa, is used for the treatment of venous thromboembolic events or prevention of stroke. Unlike many other anticoagulant agents, it does not need periodic monitoring. However, monitoring is still required to determine the risk of bleeding due to overdose or surgery. Usually, apixaban concentrations are indirectly quantified using an anti-factor Xa assay. However, this method has a relatively narrow analytical concentration range, poor selectivity, and requires an external calibrator. Therefore, the goal of current study was to establish an analytical method for determining plasma levels of apixaban using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). To this end, apixaban was separated using 2.5 mM ammonium formate (pH 3.0) (A) and 100% methanol containing 0.1% formic acid (B) using the gradient method with a Thermo hypersil GOLD column. The mass detector condition was optimized using the electrospray ionization (ESI) positive mode for apixaban quantification. The developed method showed sufficient linearity (coefficient of determination [r2 ≥ 0.997]) at calibration curve ranges. The percentage (%) changes in accuracy, precision, and all stability tests were within 15% of the nominal concentration. Apixaban concentration in plasma from healthy volunteers was quantified using the developed method. The mean maximum plasma concentration (Cmax) was 371.57 ng/mL, and the median time to achieve the Cmax (Tmax) was 4 h after administration of 10 mg apixaban alone. Although the results showed low extraction efficiency (~16%), the reproducibility (% change was within 15% of nominal concentration) was reliable. Therefore, the developed method could be used for clinical pharmacokinetic studies.

Searching for biomarkers of chronic obstructive pulmonary disease using proteomics: The current state

Detection of proteins which may be potential biomarkers of disorders represents a big step forward in understanding the molecular mechanisms that underlie pathological processes. In this context proteomics plays the important role of opening a path for the identification of molecular signatures that can potentially assist in early diagnosis of several clinical disturbances. Aim of this report is to provide an overview of the wide variety of proteomic strategies that have been applied to the investigation of chronic obstructive pulmonary disease (COPD), a severe disorder that causes an irreversible damage to the lungs and for which there is no cure yet. The results in this area published over the past decade show that proteomics indeed has the ability of monitoring alterations in expression profiles of proteins from fluids/tissues of patients affected by COPD and healthy controls. However, these data also suggest that proteomics, while being an attractive tool for the identification of novel pathological mediators of COPD, remains a technique mainly generated and developed in research laboratories. Great efforts dedicated to the validation of these biological signatures will result in the proof of their clinical utility.