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

Liquid chromatography-tandem mass spectrometry in clinical laboratory protein measurement

Proteins are essential components of human cells and tissues, and they are commonly measured in clinical laboratories using immunoassays. However, these assays have certain limitations, such as non-specificity binding, insufficient selectivity, and interference of antibodies. More sensitive, accurate, and efficient technology is required to overcome these limitations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical tool that provides high sensitivity and specificity, making it superior to traditional methods such as biochemical methods and immunoassays. While LC-MS/MS has been increasingly used for detecting small molecular analytes and steroid hormones in clinical practice recently, its application for protein or peptide analysis is still in its early stages. Established methods for quantifying proteins and peptides by LC-MS/MS are mainly focused on scientific research, and only a few proteins and peptides can be or have the potential to be detected and applied in clinical practice. Therefore, this article aims to review the clinical applications, advantages, and challenges of analyzing proteins and peptides using LC-MS/MS in clinical laboratories.

Analysis types and quantification methods applied in UHPLC-MS metabolomics research: a tutorial

BACKGROUND

Different types of analytical methods, with different characteristics, are applied in metabolomics and lipidomics research and include untargeted, targeted and semi-targeted methods. Ultra High Performance Liquid Chromatography-Mass Spectrometry is one of the most frequently applied measurement instruments in metabolomics because of its ability to detect a large number of water-soluble and lipid metabolites over a wide range of concentrations in short analysis times. Methods applied for the detection and quantification of metabolites differ and can either report a (normalised) peak area or an absolute concentration.

AIM OF REVIEW

In this tutorial we aim to (1) define similarities and differences between different analytical approaches applied in metabolomics and (2) define how amounts or absolute concentrations of endogenous metabolites can be determined together with the advantages and limitations of each approach in relation to the accuracy and precision when concentrations are reported.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The pre-analysis knowledge of metabolites to be targeted, the requirement for (normalised) peak responses or absolute concentrations to be reported and the number of metabolites to be reported define whether an untargeted, targeted or semi-targeted method is applied. Fully untargeted methods can only provide (normalised) peak responses and fold changes which can be reported even when the structural identity of the metabolite is not known. Targeted methods, where the analytes are known prior to the analysis, can also report fold changes. Semi-targeted methods apply a mix of characteristics of both untargeted and targeted assays. For the reporting of absolute concentrations of metabolites, the analytes are not only predefined but optimized analytical methods should be developed and validated for each analyte so that the accuracy and precision of concentration data collected for biological samples can be reported as fit for purpose and be reviewed by the scientific community.

Multi-omics combined to explore the purging mechanism of Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex

Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex have been used together to treat constipation in the clinical practices for more than 2000 years. Nonetheless, their compatibility mechanism is still unclear. In this study, the amelioration of Rhei Radix et Rhizoma combined with Magnoliae Officinalis Cortex on constipation was systematically and comprehensively evaluated. The results showed that their compatibility could markedly shorten gastrointestinal transport time, increase fecal water content and frequency of defecation, improve gastrointestinal hormone disorders and protect colon tissue of constipation rats compared with the single drug. Furthermore, according to 16S rRNA sequencing in conjunction with UPLC-Q-TOF/MS, the combination of two herbal medications could greatly raise the number of salutary bacteria (Lachnospiraceae, Romboutsia and Subdoligranulum) while decreasing the abundance of pathogenic bacteria (Erysipelatoclostridiaceae). And two herb drugs could markedly improve the disorder of fecal metabolic profiles. A total of 7 different metabolites associated with constipation were remarkably shifted by the compatibility of two herbs, which were mainly related to arachidonic acid metabolism, alpha-linolenic acid metabolism, unsaturated fatty acid biosynthesis and other metabolic ways. Thus, the regulation of intestinal microbiome and its metabolism could be a potential target for Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex herb pair to treat constipation. Furthermore, the multi-omics approach utilized in this study, which integrated the microbiome and metabolome, had potential for investigating the mechanism of traditional Chinese medicines.

Lipid metabolites abnormally expressed in pelvic fluid as potential biomarkers for ovarian cancer: A case-control study

BACKGROUND

Ovarian cancer is insidious and usually detected in advanced stages of the disease. As the ovaries are pelvic organs, changes in their pelvic fluid metabolites may be associated with ovarian cancer.

METHODS

Metabolomic changes in the pelvic fluid were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patients with ovarian cancer, ovarian cysts and uterine fibroids. Area under the curve (AUC) analysis was used to assess the diagnostic performance of lipid metabolites and blood tumor indices. The Pearson correlation algorithm was used to analyze the correlation between clinical characteristics and lipid metabolites in ovarian cancer patients.

RESULTS

There were 24 lipid metabolites significantly changed in the pelvic fluid of ovarian cancer patients (p < 0.05). Palmitoylcarnitine, lipoamide, lipid metabolites, and blood tumor indices (CA15-3 and CA125) showed AUC > 0.8, with palmitoylcarnitine reaching a high of 0.942. In addition, we found that some lipid metabolites were significantly associated with the clinical stage, abdominal water volume, lymphatic metastasis, and recurrence (p < 0.05, r > 0.5).

CONCLUSION

Levels of specific lipid metabolites are potential biomarkers of ovarian cancer and may play a key role in the early diagnosis and prognostic assessment of ovarian cancer.

SIGNIFICANCE

Our results showed that pelvic metabolites, especially some lipid metabolites, play an important role in the diagnosis of ovarian cancer. Meanwhile, partial lipid metabolites were closely associated with the clinical presentation and prognosis of patients with ovarian cancer. We believe that our study makes a significant contribution to the literature because it provides a potential approach that is more effective for ovarian cancer detection.

Plasma infrared fingerprinting with machine learning enables single-measurement multi-phenotype health screening

Infrared spectroscopy is a powerful technique for probing the molecular profiles of complex biofluids, offering a promising avenue for high-throughput in vitro diagnostics. While several studies showcased its potential in detecting health conditions, a large-scale analysis of a naturally heterogeneous potential patient population has not been attempted. Using a population-based cohort, here we analyze 5,184 blood plasma samples from 3,169 individuals using Fourier transform infrared (FTIR) spectroscopy. Applying a multi-task classification to distinguish between dyslipidemia, hypertension, prediabetes, type 2 diabetes, and healthy states, we find that the approach can accurately single out healthy individuals and characterize chronic multimorbid states. We further identify the capacity to forecast the development of metabolic syndrome years in advance of onset. Dataset-independent testing confirms the robustness of infrared signatures against variations in sample handling, storage time, and measurement regimes. This study provides the framework that establishes infrared molecular fingerprinting as an efficient modality for populational health diagnostics.

UPLC-MS/MS determination of 71 neuropsychotropic drugs in human serum

In this study, a UPLC-MS/MS method was developed for the rapid detection of 71 neuropsychotropic drugs in human serum for drug concentration monitoring and toxicity screening. The analytes were separated from the biological matrix by protein precipitation using a methanol-acetonitrile solvent mixture. The chromatographic separation was performed on a Kromasil ClassicShell C18 column (2.1*50 mm, 2.5 μ m) with gradient elution using acetonitrile-0.2 % acetic acid and 10 mM ammonium acetate as the mobile phases (flow rate 0.4 mL/min, column temperature 40 °C, injection volume 5 μL). An electrospray ion source in both positive and negative ion modes with multiple ion monitoring was used. The total run time was 6 min. All compounds were quantified using the isotope internal standard method. Totally, 71 drugs were detected within their linear ranges with correlation coefficients greater than 0.990. The intra- and inter-batch precision relative standard deviations (RSDs) for the low, medium, and high concentration points were less than 15 %, with an accuracy of 90%-110 %. All compounds except Moclobemide N-oxindole are stabilised within 7 days. The relative matrix effect results for each analyte were within ±20 % of the requirements. The method is validated according to Clinical and Laboratory Standards Institute guidelines, easy to use, and has a low cost.

A validated dilute-and-shoot LC-MS-MS urine screening for the analysis of 95 illicit drugs and medicines: Insights from clinical and forensic Brazilian cases

Urine toxicological analysis is a relevant tool in both clinical and forensic scenarios, enabling the diagnosis of acute poisonings, elucidation of deaths, verification of substance use in the workplace and identification of drug-facilitated crimes. For these analyses, the dilute-and-shoot technique associated with liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) is a promising alternative since it has demonstrated satisfactory results and broad applicability. This study developed and validated a comprehensive LC-MS-MS screening method to analyze 95 illicit drugs and medicines in urine samples and application to clinical and forensic Brazilian cases. The dilute-and-shoot protocol was defined through multivariate optimization studies and was set using 100 µL of sample and 300 µL of solvent. The total chromatographic run time was 7.5 min. The method was validated following the recommendations of the ANSI/ASB Standard 036 Guideline. The lower limits of quantification varied from 20 to 100 ng/mL. Within-run and between-run precision coefficient of variations% were <20%, and bias was within ± 20%. Only 4 of the 95 analytes presented significant ionization suppression or enhancement (>25%). As proof of applicability, 839 urine samples from in vivo and postmortem cases were analyzed. In total, 90.9% of the analyzed samples were positive for at least one substance, and 78 of the 95 analytes were detected. The most prevalent substances were lidocaine (40.2%), acetaminophen (38.0%) and benzoylecgonine (31.5%). The developed method proved to be an efficient and simplified alternative for analyzing 95 therapeutic and illicit drugs in urine samples. Additionally, the results obtained from sample analysis are essential for understanding the profile of Brazilian substance use, serving as a valuable database for the promotion of health and safety public policies.

LC-MS/MS determination of N-acetyl-l-cysteine in chicken plasma

N-acetyl-l-cysteine (NAC) shows beneficial effects in cases of aflatoxicosis and heat stress in poultry but little is known about its pharmacokinetics in chickens. Therefore, the study aimed to develop and validate a sensitive LC-MS/MS analytical method for quantitative analysis of NAC in chicken plasma. A split calibration curve approach was used for determination of NAC in chicken plasma. Standard curves for low (0.05-2.5 μg/ml) and high (2.5-100 μg/ml) ranges of concentrations were prepared. The standard curves for low (r2 = 0.9987) and high (r2 = 0.9899) concentrations were linear within the tested range. The limits of detection (LOD) and of quantification (LOQ) for the standard at low concentrations were 0.093 and 0.28 μg/ml, respectively. The accuracy was from 97.35 to 101.33%. The values of LOD and LOQ for the standard at high concentrations were 0.76 and 2.30 μg/ml, respectively. The accuracy was between 99.77 and 112.14%. The intra- and inter-day precisions for all concentrations from both standards did not exceed 8.57% and 10.69%, respectively. The recovery for all concentrations was between 92.45 and 105.52%. The validated method for determination of NAC in chicken plasma can be applied in future pharmacokinetic studies in chickens without dilution of samples and their repeated analysis.

Bio-synthesis, purification and structural analysis of Cyclosporine-A produced by Tolypocladium inflatum with valorization of agro-industrial wastes

Cyclosporine A (CyA) holds significant importance as a strategic immunosuppressive drug for organ transplant patients. In this study, we aimed to produce pure and cost-effective Cyclosporine A (CyA) by fermenting a culture medium containing dairy sludge, using Tolypocladium inflatum PTCC 5253. Following the fermentation stage, ethyl acetate extraction and fast protein liquid chromatography were employed for sample purification. The initial evaluation of the effectiveness of CyA obtained from these processes was performed through bioassay, wherein the antimicrobial clear zone diameter was found to be larger compared to the sample obtained from the fermentation culture. The concentration of CyA was determined using high-performance liquid chromatography, yielding values of 334 mg/L, 456 mg/L, and 578 mg/L for the fermented, extracted, and purified samples, respectively. Further analysis utilizing liquid chromatography tandem mass spectrometry (LC/MS/MS) confirmed a purity of 91.9% and proper agreement with the standard sample based on the ion intensity of Z/m 1205. To validate the structure of CyA, nuclear magnetic resonance spectroscopy, Fourier-transform infrared (FT-IR), and Raman spectroscopy were employed. X-ray diffraction and differential scanning calorimetry analyses demonstrated that the purified CyA exhibited a crystal structure similar to the standard sample, characterized by two broad peaks at 2θ = 9° and 20°, and comparable glass transition temperatures (57-68 °C for the purified sample; 53-64 °C for the standard sample). Dynamic light scattering analysis confirmed a uniform particle size distribution in both the purified and standard samples. The zeta potentials of the purified and standard samples were determined to be - 25.8 ± 0.16 and - 23.63 ± 0.12 mV, respectively. Our results demonstrate that dairy sludge can serve as a suitable culture medium for the production of (CyA).

A high throughput immuno-affinity mass spectrometry method for detection and quantitation of SARS-CoV-2 nucleoprotein in human saliva and its comparison with RT-PCR, RT-LAMP, and lateral flow rapid antigen test

OBJECTIVES

Many reverse transcription polymerase chain reaction (RT-PCR) methods exist that can detect SARS-CoV-2 RNA in different matrices. RT-PCR is highly sensitive, although viral RNA may be detected long after active infection has taken place. SARS-CoV-2 proteins have shorter detection windows hence their detection might be more meaningful. Given salivary droplets represent a main source of transmission, we explored the detection of viral RNA and protein using four different detection platforms including SISCAPA peptide immunoaffinity liquid chromatography-mass spectrometry (SISCAPA-LC-MS) using polyclonal capture antibodies.

METHODS

The SISCAPA-LC MS method was compared to RT-PCR, RT-loop-mediated isothermal amplification (RT-LAMP), and a lateral flow rapid antigen test (RAT) for the detection of virus material in the drool saliva of 102 patients hospitalised after infection with SARS-CoV-2. Cycle thresholds (Ct) of RT-PCR (E gene) were compared to RT-LAMP time-to-positive (TTP) (NE and Orf1a genes), RAT optical densitometry measurements (test line/control line ratio) and to SISCAPA-LC-MS for measurements of viral protein.

RESULTS

SISCAPA-LC-MS showed low sensitivity (37.7 %) but high specificity (89.8 %). RAT showed lower sensitivity (24.5 %) and high specificity (100 %). RT-LAMP had high sensitivity (83.0 %) and specificity (100.0 %). At high initial viral RNA loads (<20 Ct), results obtained using SISCAPA-LC-MS correlated with RT-PCR (R2 0.57, p-value 0.002).

CONCLUSIONS

Detection of SARS-CoV-2 nucleoprotein in saliva was less frequent than the detection of viral RNA. The SISCAPA-LC-MS method allowed processing of multiple samples in <150 min and was scalable, enabling high throughput.

Absolute protein quantification based on calibrated particle counting using electrospray-differential mobility analysis

The traceability of in vitro diagnostics or drug products is based on the accurate quantification of proteins. In this study, we developed an absolute quantification approach for proteins. This method is based on calibrated particle counting using electrospray-differential mobility analysis (ES-DMA) coupled with a condensation particle counter (CPC). The absolute concentration of proteins was quantified with the observed protein particle number measured with ES-DMA-CPC, and the detection efficiency was determined by calibrators. The measurement performance and quantitative level were verified using two certificated reference materials, BSA and NIMCmAb. The linear regression fit for the detection efficiency values of three reference materials and one highly purified protein (myoglobin, BSA, NIMCmAb and fibrinogen) indicated that the detection efficiency and the particle size distribution of these proteins exhibited a linear relationship. Moreover, to explore the suitability of the detection efficiency-particle size curve for protein quantification, the concentrations of three typical proteinaceous particles, including two high molecular weight proteins (NIST reference material 8671 and D-dimer) and one protein complex (glutathione S-transferase dimer), were determined. This work suggests that this calibrated particle counting method is an efficient approach for nondestructive, rapid and accurate quantification of proteins, especially for measuring proteinaceous particles with tremendous size and without reference standards.

Determination of amino acid metabolic diseases from dried blood spots with a rapid extraction method coupled with nanoelectrospray ionization mass spectrometry

In this work, a rapid extraction method of methanol/water (95:5 v/v) with 0.1% formic acid was developed for extraction of amino acids from dried blood spots (DBS) for inherited metabolic diseases (IMDs). The combination of this extraction procedure with nanoelectrospray ionization mass spectrometry (nESI-MS) was used for the rapid analysis of amino acids. This approach with eliminating the chromatographic separation required only 2 min for the extraction of amino acids from DBS, which simplified the configuration and improved the timeliness. Dependence of the sensitivity on the operating parameters was systematically investigated. The LOD of 91.2-262.5 nmol/L and LOQ of 304-875 nmol/L which were lower than the cut-off values were obtained for amino acids within DBS. The accuracy was determined to be 93.82%-103.07% and the precision was determined to be less than 8.30%. The effectiveness of this method was also compared with the gold standard method (e.g., LC-MS/MS). The desalination mechanism was explored with interference mainly originated from the blood. These findings indicated that the rapid extraction procedure coupled with nESI-MS is capable of screening indicators for IMDs in complex biological samples.

Urban and agricultural influences on the coastal dissolved organic matter pool in the Algoa Bay estuaries

While anthropogenic pollution is a major threat to aquatic ecosystem health, our knowledge of the presence of xenobiotics in coastal Dissolved Organic Matter (DOM) is still relatively poor. This is especially true for water bodies in the Global South with limited information gained mostly from targeted studies that rely on comparison with authentic standards. In recent years, non-targeted tandem mass spectrometry has emerged as a powerful tool to collectively detect and identify pollutants and biogenic DOM components in the environment, but this approach has yet to be widely utilized for monitoring ecologically important aquatic systems. In this study we compared the DOM composition of Algoa Bay, Eastern Cape, South Africa, and its two estuaries. The Swartkops Estuary is highly urbanized and severely impacted by anthropogenic pollution, while the Sundays Estuary is impacted by commercial agriculture in its catchment. We employed solid-phase extraction followed by liquid chromatography tandem mass spectrometry to annotate more than 200 pharmaceuticals, pesticides, urban xenobiotics, and natural products based on spectral matching. The identification with authentic standards confirmed the presence of methamphetamine, carbamazepine, sulfamethoxazole, N-acetylsulfamethoxazole, imazapyr, caffeine and hexa(methoxymethyl)melamine, and allowed semi-quantitative estimations for annotated xenobiotics. The Swartkops Estuary DOM composition was strongly impacted by features annotated as urban pollutants including pharmaceuticals such as melamines and antiretrovirals. By contrast, the Sundays Estuary exhibited significant enrichment of molecules annotated as agrochemicals widely used in the citrus farming industry, with predicted concentrations for some of them exceeding predicted no-effect concentrations. This study provides new insight into anthropogenic impact on the Algoa Bay system and demonstrates the utility of non-targeted tandem mass spectrometry as a sensitive tool for assessing the health of ecologically important coastal ecosystems and will serve as a valuable foundation for strategizing long-term monitoring efforts.

High-Performance, Low-Cost, Additively Manufactured Electrospray Ion Sources for Mass Spectrometry

We report novel 3D-printed electrospray sources for mass spectrometry (MS) that produce twice the signal strength of their mainstream counterparts. Leveraging 3D printing to fabricate in bulk nano- and microscale-featured electrospray emitters, this work shows a path for scalable integration in clinically relevant diagnostics. This solution improves the device performance by simultaneously tuning the surface hydrophilicity, solvent evaporation, and geometry. The emitters are made of stainless-steel (SS) 316L via binder jetting and coated in a conformal, hydrothermally grown zinc oxide nanowire (ZnONW) forest. The printed emitters are designed as surface mount devices that can be directly soldered to printed circuit boards with built-in digital microfluidics as part of an automated device assembly. The electrospray sources use a novel extractor electrode design that enables operation at ∼24% larger bias voltages compared with conventional MS cylindrical inlets. The 3D-printed electrospray emitters were characterized against their state-of-the-art counterparts (coated blades and paper spray). MS data from the 3D-printed electrospray emitters show detection of therapeutically relevant targets at 1 μg/ml concentrations with a variety of solvents; for nicardipine, such emitters attain 116% higher signal-to-noise ratios and far greater stability than their counterparts.

Oxidative Stress Biomarkers in Male Infertility: Established Methodologies and Future Perspectives

Male fertility can be affected by oxidative stress (OS), which occurs when an imbalance between the production of reactive oxygen species (ROS) and the body's ability to neutralize them arises. OS can damage cells and influence sperm production. High levels of lipid peroxidation have been linked to reduced sperm motility and decreased fertilization ability. This literature review discusses the most commonly used biomarkers to measure sperm damage caused by ROS, such as the high level of OS in seminal plasma as an indicator of imbalance in antioxidant activity. The investigated biomarkers include 8-hydroxy-2-deoxyguanosine acid (8-OHdG), a marker of DNA damage caused by ROS, and F2 isoprostanoids (8-isoprostanes) produced by lipid peroxidation. Furthermore, this review focuses on recent methodologies including the NGS polymorphisms and differentially expressed gene (DEG) analysis, as well as the epigenetic mechanisms linked to ROS during spermatogenesis along with new methodologies developed to evaluate OS biomarkers. Finally, this review addresses a valuable insight into the mechanisms of male infertility provided by these advances and how they have led to new treatment possibilities. Overall, the use of biomarkers to evaluate OS in male infertility has supplied innovative diagnostic and therapeutic approaches, enhancing our understanding of male infertility mechanisms.

Evaluation of five multisteroid LC‒MS/MS methods used for routine clinical analysis: comparable performance was obtained for nine analytes

OBJECTIVES

A mass spectrometry (LC‒MS/MS)-based interlaboratory comparison study was performed for nine steroid analytes with five participating laboratories. The sample set contained 40 pooled samples of human serum generated from preanalyzed leftovers. To obtain a well-balanced distribution across reference intervals of each steroid, the leftovers first underwent a targeted mixing step.

METHODS

All participants measured a sample set once using their own multianalyte protocols and calibrators. Four participants used in-house developed measurement platforms, including IVD-CE certified calibrators, which were used by three participants; the 5th lab used the whole LC‒MS kit from an IVD manufacturer. All labs reported results for 17-hydroxyprogesterone, androstenedione, cortisol, and testosterone, and four labs reported results for 11-deoxycortisol, corticosterone, cortisone, dehydroepiandrosterone sulfate (DHEAS), and progesterone.

RESULTS

Good or acceptable overall comparability was found in Bland‒Altman and Passing‒Bablok analyses. Mean bias against the overall mean remained less than ±10 % except for DHEAS, androstenedione, and progesterone at one site and for cortisol and corticosterone at two sites (max. -18.9 % for androstenedione). The main analytical problems unraveled by this study included a bias not previously identified in proficiency testing, operator errors, non-supported matrix types and higher inaccuracy and imprecision at lower ends of measuring intervals.

CONCLUSIONS

This study shows that intermethod comparison is essential for monitoring the validity of an assay and should serve as an example of how external quality assessment could work in addition to organized proficiency testing schemes.

A method for measuring serum levels of melanin-associated indole metabolites using LC-MS/MS and its application to malignant melanoma

BACKGROUND AND AIMS

With the development of novel therapies for advanced malignant melanoma (MM), biomarkers that can accurately reflect the progression of MM are needed. Serum levels of melanin-related indole metabolites such as 5-hydroxy-6-methoxyindole-2-carboxylic acid (5H6MI2C) and 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C) are potential biomarkers for MM. Here, we describe the development of a mass spectrometry (MS)-based assay to determine serum levels of 5H6MI2C and 6H5MI2C.

MATERIALS AND METHODS

We developed a stable isotope dilution-selective reaction monitoring-MS protocol using liquid chromatography tandem mass spectrometry (LC-MS/MS) to measure human serum 5H6MI2C and 6H5MI2C levels. Analytical evaluations of the method were performed and the method was applied to serum samples from MM patients (n = 81).

RESULTS

The method established in this study showed high reproducibility and linearity. This novel method also found that serum 6H5MI2C levels were significantly elevated in patients with metastatic MM compared to those with non-metastatic MM. Unfortunately, 5H6MI2C did not show a comparable significant difference.

CONCLUSION

We successfully established measurement methods for serum 5H6MI2C and 6H5MI2C levels using LC-MS/MS. Serum 6H5MI2C levels offer a potential marker for MM.

Plasma metabolomic analysis reveals the metabolic characteristics and potential diagnostic biomarkers of spinal tuberculosis

Objectives

This study aimed to conduct a non-targeted metabolomic analysis of plasma from patients with spinal tuberculosis (STB) to systematically elucidate the metabolomic alterations associated with STB, and explore potential diagnostic biomarkers for STB.

Methods

From January 2020 to January 2022, 30 patients with spinal tuberculosis (STBs) clinically diagnosed at the General Hospital of Ningxia Medical University and 30 age- and sex-matched healthy controls (HCs) were selected for this study. Using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) based metabolomics, we analyzed the metabolic profiles of 60 plasma samples. Statistical analyses, pathway enrichment, and receiver operating characteristic (ROC) analyses were performed to screen and evaluate potential diagnostic biomarkers.

Results

Metabolomic profiling revealed distinct alterations between the STBs and HCs cohorts. A total of 1635 differential metabolites were screened, functionally clustered, and annotated. The results showed that the differential metabolites were enriched in sphingolipid metabolism, tuberculosis, cutin, suberine and wax biosynthesis, beta-alanine metabolism, methane metabolism, and other pathways. Through the random forest algorithm, LysoPE (18:1(11Z)/0:0), 8-Demethyl-8-formylriboflavin 5'-phosphate, Glutaminyl-Gamma-glutamate, (2R)-O-Phospho-3-sulfolactate, and LysoPE (P-16:0/0:0) were determined to have high independent diagnostic value.

Conclusions

STBs exhibited significantly altered metabolite profiles compared with HCs. Here, we provide a global metabolomic profile and identify potential diagnostic biomarkers of STB. Five potential independent diagnostic biomarkers with high diagnostic value were screened. This study provides novel insights into the pathogenesis, diagnosis, and treatment strategies of STB.

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.

A biomarker panel of secondary hypertension is simultaneously quantified by coupling of magnetic solid-phase extraction and liquid chromatography-tandem mass spectrometry

RATIONALE

Secondary hypertension is often caused by activation of complex multi-organ endocrine systems, while renin activity indicated by angiotensins (Angs), aldosterone (ALD) and cortisol (COR) in such systems are generally accepted as its diagnostic markers. As antibody-based methods cannot offer comparable quantification for these biomarkers, a liquid chromatography (LC)-tandem mass spectrometry (MS/MS)-based approach was developed to quantify them simultaneously and accurately.

METHODS

Five different beads for magnetic solid-phase extraction (MSPE) were evaluated towards their enrichment efficiency for these biomarkers. An LC system with optimized elution gradient and a triple-quadrupole MS with tuned parameters were coupled to quantitatively monitor the extracted analytes. The method performance was further examined such as linearity, precision, stability, recovery rate and matrix effect. Based on the developed method, the abundance of Ang II, ALD and COR in plasma was measured and the quantification was compared with that derived from commercial ELISA kits.

RESULTS

As compared with other MSPEs, Angs, ALD and COR were highly enriched by the HLB magnetic beads with satisfactory recoveries. These analytes were simultaneously quantified by LC/MS/MS and all the method parameters for quantification were well matched with the requirements of clinical testing. Comparison of the quantitative results derived from ELISA and LC/MS/MS exhibited that the two methods offered basically comparable values with Pearson r values at 0.896, 0.895 and 0.835, respectively. The stability test for plasma Angs at room temperature indicated that the abundance of Ang II was relatively stable within 3 h, whereas that of Ang I and Ang 1-7 was time-dependently changed.

CONCLUSIONS

Coupling of HLB beads and LC/MS/MS thus enables simultaneous quantification of a set of biomarkers related to secondary hypertension.

Novel quality control strategies for the determination of 25-hydroxyvitamin D by LC-MS/MS

Mass spectrometry analysis has been applied in many important diagnostic fields of laboratory medicine. However, there is little literature to guide quality management systems for LC-MS/MS methods. In this study, LC-MS/MS 25-hydroxyvitamin D (25(OH)D) was used as an example to establish internal quality control strategies to ensure the accuracy of clinical vitamin D results. A total of 141 batches of samples were analyzed. Sample internal standard peak area variability, ion pair ratio, and physical examination population data were monitored as quality control strategies for 25(OH)D results. The analytical performance was evaluated by calculated Sigma metrics. Applying our quality control strategies, several abnormal data were monitored in the routine analysis. The daily peak area CV of 25(OH)D fluctuated within a certain range. By selecting P99 CV as the control target, two abnormal batches were found. The ratio of 25(OH)VD3 ion pairs was relatively stable. Among them, batch20230120 had a high CV value, which may be due to the bias caused by the limited number. According to the physical examination data, batch20220913 and batch20220919 exceeded the alarm limit. Sigma level of 25(OH)VD3 in the laboratory was 6.52, which achieved "excellent" performance. In conclusion, we established comprehensive quality control strategies for the determination of 25(OH)D by LC-MS/MS, which has high analytical performance and can provide more accurate reports for the clinic.

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.

LC-MS bioanalysis of protein biomarkers and protein therapeutics in formalin-fixed paraffin-embedded tissue specimens

Formalin-fixed paraffin-embedded (FFPE) is a form of preservation and preparation for biopsy specimens. FFPE tissue specimens are readily available as part of oncology studies because they are often collected for disease diagnosis or confirmation. FFPE tissue specimens could be extremely useful for retrospective studies on protein biomarkers because the samples preserved in FFPE blocks could be stable for decades. However, LC-MS bioanalysis of FFPE tissues poses significant challenges. In this Perspective, we review the benefits and recent developments in LC-MS approach for targeted protein biomarker and protein therapeutic analysis using FFPE tissues and their clinical and translational applications. We believe that LC-MS bioanalysis of protein biomarkers in FFPE tissue specimens represents a great potential for its clinical applications.

Urine biomarkers for Alzheimer's disease: A new opportunity for wastewater-based epidemiology?

While Alzheimer's disease (AD) diagnosis, management, and care have become priorities for healthcare providers and researcher's worldwide due to rapid population aging, epidemiologic surveillance efforts are currently limited by costly, invasive diagnostic procedures, particularly in low to middle income countries (LMIC). In recent years, wastewater-based epidemiology (WBE) has emerged as a promising tool for public health assessment through detection and quantification of specific biomarkers in wastewater, but applications for non-infectious diseases such as AD remain limited. This early review seeks to summarize AD-related biomarkers and urine and other peripheral biofluids and discuss their potential integration to WBE platforms to guide the first prospective efforts in the field. Promising results have been reported in clinical settings, indicating the potential of amyloid β, tau, neural thread protein, long non-coding RNAs, oxidative stress markers and other dysregulated metabolites for AD diagnosis, but questions regarding their concentration and stability in wastewater and the correlation between clinical levels and sewage circulation must be addressed in future studies before comprehensive WBE systems can be developed.

Recent developments in mass-spectrometry-based targeted proteomics of clinical cancer biomarkers

Routine measurement of cancer biomarkers is performed for early detection, risk classification, and treatment monitoring, among other applications, and has substantially contributed to better clinical outcomes for patients. However, there remains an unmet need for clinically validated assays of cancer protein biomarkers. Protein tumor markers are of particular interest since proteins carry out the majority of biological processes and thus dynamically reflect changes in cancer pathophysiology. Mass spectrometry-based targeted proteomics is a powerful tool for absolute peptide and protein quantification in biological matrices with numerous advantages that make it attractive for clinical applications in oncology. The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) based methodologies has allowed laboratories to overcome challenges associated with immunoassays that are more widely used for tumor marker measurements. Yet, clinical implementation of targeted proteomics methodologies has so far been limited to a few cancer markers. This is due to numerous challenges associated with paucity of robust validation studies of new biomarkers and the labor-intensive and operationally complex nature of LC-MS/MS workflows. The purpose of this review is to provide an overview of targeted proteomics applications in cancer, workflows used in targeted proteomics, and requirements for clinical validation and implementation of targeted proteomics assays. We will also discuss advantages and challenges of targeted MS-based proteomics assays for clinical cancer biomarker analysis and highlight some recent developments that will positively contribute to the implementation of this technique into clinical laboratories.

Targeted LC-MS/MS profiling of bile acids reveals primary/secondary bile acid ratio as a novel biomarker for necrotizing enterocolitis

Bile acids (BAs) are involved in the development of necrotizing enterocolitis (NEC), which mainly occurs in preterm infants. We aim to identify the change of BAs in preterm infants and validate its potential value in the detection of NEC. Targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed to measure the plasma BAs in healthy preterm infants and patients with NEC. By analyzing the level of BAs in healthy preterm infants, we found that the plasma concentrations of BAs were related to sex, gestational/postnatal age, birth weight, mode of birth, and feeding type after birth. The plasma levels of TCA, GCA, TCDCA, GCDCA, primary BAs, and total BAs and the primary/secondary BA ratio were decreased, while DCA, UDCA, and secondary BAs were increased in NEC. The primary/secondary BA ratio (cutoff point 62.9) can effectively differentiate NEC from healthy preterm infants, with an AUC of 0.9, a sensitivity of 94.5%, and a specificity of 78.1%. Combining the ratio with high-risk factors of NEC can better distinguish between NEC and control, with an AUC of 0.95. Importantly, significantly lower levels of primary/secondary BA ratio were found in infants with surgical NEC than in nonsurgical NEC cases. The cutoff point of 28.7 identified surgical NEC from nonsurgical NEC with sensitivity and specificity of 76.9% and 100%. Thus, our study identified that the primary/secondary BA ratio in the plasma can differentiate NEC from healthy preterm infants and effectively differentiate the surgical NEC from nonsurgical NEC. Therefore, LC-MS/MS was expected to be a novel measurement platform used to distinguish infants who are most in need of close monitoring or early surgical intervention.

Post mortem blood bromazolam concentrations and co-findings in 96 coronial cases within England and Wales

Bromazolam is a newly emerging benzodiazepine drug which is not licensed for medicinal use. It may be sourced as a New Psychoactive Substance (NPS) for its desired effects or be consumed unknowingly via counterfeit Xanax® or Valium® preparations. As part of our Coronial workload, we observed an increase in the detection of bromazolam from September 2021 to November 2022. We report a series of 96 cases in which bromazolam was quantitated by high resolution accurate mass - mass spectrometry (HRAM - MS) in post-mortem blood. The mean (SD) post-mortem blood bromazolam concentration from our case series was 64.6 ( ± 79.4) µg/L (range <1-425 µg/L). Routine toxicological screening results have also been reported; the most commonly encountered drugs taken in combination with bromazolam were cocaine, gabapentinoids and diazepam. In 48% of cases at least one further designer benzodiazepine drug was also present (etizolam, flualprazolam, flubromazolam, flubromazepam). It is essential that laboratories providing toxicological investigations are aware of the limitations of their assays; and inclusion of bromazolam within targeted screening panels using LC-MS/MS is encouraged. Bromazolam has not been associated with death in isolation from resulting toxic concentrations; however, it is likely to enhance adverse clinical effects when taken in combination with stimulant and/or centrally-acting depressant drugs (poly-drug deaths). Bromazolam, similar to other benzodiazepines, may also impair cognition and decision making skills.

Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function

Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.

Challenges to Laboratory Monitoring of Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) exert anticoagulation effect by directly inhibiting Factor Xa (rivaroxaban, apixaban, and edoxaban) or thrombin (dabigatran). Though DOACs are characterized by fixed-dose prescribing and generally do not require routine laboratory drug-level monitoring (DLM), circumstances may arise where the DLM may aid in clinical decision-making, including DOAC dose adjustment, anticoagulant class change, or decisions to withhold or administer reversal agents. We review the current literature that describes high-risk patient groups in which DLM may be beneficial for improved patient anticoagulation management and stewardship. The review also summarizes the limitations of conventional coagulation testing and discuss the emerging utility of quantitative methods for routine and rapid emergent evaluation of DOAC drug levels-in particular, the Anti-Xa activity to detect Factor Xa Inhibitors (rivaroxaban, apixaban, and edoxaban). Both technical and regulatory barriers to widespread DLM implementation are limiting factors to further clinical research that must be overcome, in order to propose universal DOAC DLM strategies and provide clinical-laboratory correlation to formally classify high-risk patient groups.

Multiplex Immunosuppressant (ISD) Method for the Measurement of Cyclosporine A, Tacrolimus, Sirolimus/Rapamycin, and Everolimus in Whole Blood Using MassTrak™ Kit

Cyclosporine A, everolimus, sirolimus, and tacrolimus are the most commonly used immunosuppressant drugs in organ transplant and auto-immune patients. The narrow therapeutic window of these immunosuppressant drugs requires close monitoring of drug blood levels to ensure proper therapeutic response. A quick, robust high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was introduced for monitoring whole blood levels of these immunosuppressant drugs with the use of the MassTrak™ Immunosuppressant kit. The assay was carried out in 96-well plate format and requires a simple precipitation step; after which, the supernatant is subjected to liquid chromatography separation (2 min total run time) using a C18 Cartridge column. Identification and quantitation of cyclosporine A, everolimus, sirolimus, and tacrolimus was achieved by employing multiple reaction monitoring (MRM) in positive mode electrospray ionization (ESI). The method exhibits a linear measuring range from 10 to 1500 ng/mL (Cyclosporine A), 1.0-30.0 ng/mL (Everolimus), 1.0-26.0 ng/mL (Sirolimus), and 1.0-30.0 ng/mL (Tacrolimus) and has a within-run and between-run imprecision of <10%.

The identification of novel stroke-related sphingolipid biomarkers using UPLC-MS/MS

BACKGROUND

Stroke is a prominent contributor to global mortality and morbidity, thus necessitating the establishment of dependable diagnostic indicators. The objective of this study was to ascertain metabolites linked to sphingolipid metabolism and assess their viability as diagnostic markers for stroke.

METHODS

Two cohorts, consisting of 56 S patients and 56 healthy volunteers, were incorporated into this investigation. Metabolite data was obtained through the utilization of Ultra Performance Liquid Chromatography and Tandem Mass Spectrometry (UPLC-MS/MS). The mass spectrometry data underwent targeted analysis and quantitative evaluation utilizing the multiple reaction monitoring mode of triple quadrupole mass spectrometry. Various data analysis techniques, including Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA), least absolute shrinkage and selection operator (LASSO) regression, Support Vector Machine (SVM), logistic regression, and Receiver Operating Characteristic (ROC) curves were employed.

RESULTS

A comprehensive analysis detected a total of 129 metabolites related to sphingolipid metabolism, encompassing ceramides, 1-phosphoceramides, phytoceramides, glycosphingolipids, sphingomyelins, and sphingomyelins. The implementation of OPLS-DA analysis revealed significant disparities between individuals with stroke and controls, as it successfully identified 31 metabolites that exhibited significant differential expression between the two groups. Furthermore, functional enrichment analysis indicated the participation of these metabolites in diverse biological processes. Six metabolic markers, namely CerP(d18:1/20:3), CerP(d18:1/18:1), CerP(d18:1/18:0), CerP(d18:1/16:0), SM(d18:1/26:1), and Cer(d18:0/20:0), were successfully validated as potential diagnostic markers for stroke. The utilization of ROC analysis further confirmed their diagnostic potential, while a logistic regression model incorporating these markers demonstrated robust efficacy in distinguishing stroke patients from healthy controls.

CONCLUSION

these identified metabolic markers exhibit clinical significance and hold promise as valuable tools for the diagnosis of stroke.

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.

High-Throughput Liquid Chromatographic Analysis Using a Segmented Flow Injector with a 1 s Cycle Time

High-throughput screening (HTS) workflows are revolutionizing many fields, including drug discovery, reaction discovery and optimization, diagnostics, sensing, and enzyme engineering. Liquid chromatography (LC) is commonly deployed during HTS to reduce matrix effects, distinguish isomers, and preconcentrate prior to detection, but LC separation time often limits throughput. Although subsecond LC separations have been demonstrated, they are rarely utilized during HTS due to limitations associated with the speed of common autosamplers. In this work, these limits are overcome by utilizing droplet microfluidics for sample introduction. In the method, a train of samples segmented by air are continuously pumped into the inlet of an LC injection valve that is actuated once each sample fills the sample loop. Coupled with 2.1 mm diameter × 5 mm long columns packed with 2.7 μm superficially porous C18 particles operated at 5 mL/min, the injector enabled separation of 3 components at 1 s/sample and analysis of a 96-well plate in 1.6 min with <2% peak area relative standard deviation. Analyte-dependent carryover was minimized by including wash droplets composed of organic solvent in between sample droplets. High-throughput LC coupled with mass spectrometric detection using the segmented flow injector was applied to a screen of inhibitors of a cytochrome P450-catalyzed hydroxylation reaction. Measurements of the reaction substrate and product concentrations made using fast LC with the segmented flow injector correlated well with measurements made using a more conventional, 3 min LC method. These results demonstrate the potential for droplet microfluidics to be used for sample introduction during high-throughput LC analysis.

Advances in minimal residual disease monitoring in multiple myeloma

Multiple myeloma (MM) is characterized by the clonal expansion of plasma cells and the excretion of a monoclonal immunoglobulin (M-protein), or fragments thereof. This biomarker plays a key role in the diagnosis and monitoring of MM. Although there is currently no cure for MM, novel treatment modalities such as bispecific antibodies and CAR T-cell therapies have led to substantial improvement in survival. With the introduction of several classes of effective drugs, an increasing percentage of patients achieve a complete response. This poses new challenges to traditional electrophoretic and immunochemical M-protein diagnostics because these methods lack sensitivity to monitor minimal residual disease (MRD). In 2016, the International Myeloma Working Group (IMWG) expanded their disease response criteria with bone marrow-based MRD assessment using flow cytometry or next-generation sequencing in combination with imaging-based disease monitoring of extramedullary disease. MRD status is an important independent prognostic marker and its potential as a surrogate endpoint for progression-free survival is currently being studied. In addition, numerous clinical trials are investigating the added clinical value of MRD-guided therapy decisions in individual patients. Because of these novel clinical applications, repeated MRD evaluation is becoming common practice in clinical trials as well as in the management of patients outside clinical trials. In response to this, novel mass spectrometric methods that have been developed for blood-based MRD monitoring represent attractive minimally invasive alternatives to bone marrow-based MRD evaluation. This paves the way for dynamic MRD monitoring to allow the detection of early disease relapse, which may prove to be a crucial factor in facilitating future clinical implementation of MRD-guided therapy. This review provides an overview of state-of-the-art of MRD monitoring, describes new developments and applications of blood-based MRD monitoring, and suggests future directions for its successful integration into the clinical management of MM patients.

Simultaneous quantification of total and free testosterone in human serum by LC-MS/MS

Testosterone (TTe) and free testosterone (FTe) are clinically important indicators for the diagnosis of androgen disorders, so accurate quantitative determination of them in serum is clinically of paramount significance. Currently, there is no available method suitable for routine and simultaneous measurement of TTe and FTe. Here, we developed a new UPLC-MS/MS method to quantify serum TTe and FTe simultaneously and accurately. Rapid equilibrium dialysis was used to obtain FTe in serum followed by derivatization with hydroxylamine hydrochloride. With these strategies, TTe and FTe could be measured in single injection. After optimizing the extraction and derivatization conditions, the performance of LC-MS/MS was evaluated and applied to quantify the levels of TTe and FTe in clinical samples from 42 patients. The assays were linear for TTe within the range of 0.2-30 ng/mL and for FTe within the range of 1.5-1000 pg/mL. This improved method provided a limit of quantification for TTe of 0.2 ng/mL and for FTe of 1.5 pg/mL. The intra- and inter-run CVs were less than 4.3% and 3.6% for TTe and less than 8.2% and 6.7% for FTe, respectively. The intra- and inter-run accuracies for both TTe and FTe were in the range of 96.1-108.1%. Interference, carryover effect, and matrix effect were in acceptable range. In conclusion, our new LC-MS/MS method is simple to perform and can serve as a reliable method for simultaneous determination of TTe and FTe in clinical practice, providing important information for diagnosis, treatment, and monitoring of androgen-related diseases.

Automated LC-MS/MS: Ready for the clinical routine Laboratory?

Background

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a sensitive method with high specificity. However, its routine use in the clinical laboratory is hampered by its high complexity and lack of automation. Studies demonstrate excellent analytical performance using the first fully automated LC-MS/MS for 25-hydroxy vitamin D and immunosuppressant drugs (ISD) in hospital routine laboratories.

Objectives

Our objectives were (1) to verify the suitability of an automated LC-MS/MS in a commercial laboratory, which differs from the needs of hospital laboratories, and (2) examine its usability among operators with various professional backgrounds.

Methods

We assessed the analytical assay performance for vitamin D and the ISDs cyclosporine A and tacrolimus over five months. The assays were compared to an identical analyzer in a hospital laboratory, to in-house LC-MS/MS methods, and to chemiluminescent microparticle immunoassays (CMIA). Nine operators evaluated the usability of the fully automated LC-MS/MS system by means of a structured questionnaire.

Results

The automated system exhibited a high precision (CV < 8%), accuracy (bias < 7%) and good agreement with concentrations of external quality assessment (EQA) samples. Comparable results were obtained with an identical analyzer in a hospital routine laboratory. Acceptable median deviations of results versus an in-house LC-MS/MS were observed for 25-OH vitamin D3 (-10.6%), cyclosporine A (-4.3%) and tacrolimus (-6.6%). The median bias between the automated system and immunoassays was only acceptable for 25-OH vitamin D3 (6.6%). All users stated that they had had a good experience with the fully automated LC-MS/MS system.

Conclusions

A fully automated LC-MS/MS can be easily integrated for routine diagnostics in a commercial laboratory.

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.

A novel long noncoding RNA located on the antisense strand of MAL promotes the invasion and metastasis of oral squamous cell carcinoma

OBJECTIVES

This study aims to investigate the role of the long non-coding RNA-AC103563.8 (lncRNA) in promoting oral squamous cell carcinoma (OSCC) development and to conduct preliminary research on its mechanism.

DESIGN

Microarray technology were used to screen out a lncRNA significantly upregulated in OSCC. Fluorescence in situ hybridization was used to analyze the position of lncRNA-AC103563.8 in cells. A Cal-27 cell line with knockout of the lncRNA-AC103563.8 gene was constructed. Transwell assay and tumor xenograft experiment was used to determine the metastasis and invasion of the cell. Detection of mutations in genes encoding myelin and lymphocyte proteins (MAL) by pyrosequencing. Identification of RNA-Binding Proteins by Mass Spectrometry (ChIRP-MS) experiments were carried out to enrich the proteins that directly bind to lncRNA-AC103563.8. Bioinformatics was used to analyze the target proteins. Some of the selected proteins were verified by parallel reaction monitoring (PRM) to confirm their binding to lncRNA-AC103563.8.

RESULTS

lncRNA-AC103563.8 is upregulated in OSCC tissue and the presence of lncRNA-AC103563.8 in both the nucleus and the cytoplasm. lncRNA-AC103563.8 promoted OSCC cell invasion and metastasis. Methylation occurs in MAL gene promoter. ChIRP-MS identified 330 proteins binding to lncRNA-AC103563.8, and bioinformatics analysis showed that they were involved in a variety of biological processes. PRM experiments confirmed some protein directly bound to lncRNA-AC103563.8.

CONCLUSION

lncRNA-AC103563.8 is a functional lncRNA that promotes OSCC development by acting on MAL or interacting with other tumor-related proteins. This study also indicates that this lncRNA may exert regulatory functions in OSCC and is a potential target for OSCC therapy.

Fourteen Deaths from Suspected Heparin Overdose in an Italian Primary-Level Hospital

Healthcare-related homicidal cases are not novel within the medical-legal landscape, but investigations are often made difficult with the scarcity of material evidence related to the crime. For this reason, it is necessary to carefully analyze the clinical documentation and employ ancillary forensic resources such as radiology, histopathology, and toxicology. In the presented scenario, the observation of 14 deaths from abnormal bleeding in a First-Level Italian Hospital revealed the administration of massive doses of heparin by a nurse. On behalf of the Judicial Authority, a multidisciplinary medical team investigated the case through the following steps: a thorough review of the clinical documentation, exhumation of the bodies belonging to the deceased patients, performing PMCT and autopsy, and collecting tissue samples for histopathological, immunohistochemical, and toxicological investigations. All the analyzed cases have been characterized by the observation of fatal hemorrhagic episodes not explained with the clinical conditions of the patients, confirmed using autopsy observations and the histological demonstration of the vitality of the lesions. However, due to the limited availability of biological material for the toxicological analysis, the indirect evidence from hematological analyses in hospitalized patients was crucial in demonstrating heparin overdose and its link to the recorded deaths. The present scenario demonstrates the fundamental importance of a multidisciplinary approach to cases of judicial interest related to the healthcare context. Therefore, the illustrated methodologies can be interpreted as an operational framework for similar future cases.

An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure (RMP) for the quantification of methotrexate in human serum and plasma

OBJECTIVES

To develop an isotope dilution-liquid chromatography-tandem mass spectrometry-(ID-LC-MS/MS)-based candidate reference measurement procedure (RMP) for quantification of methotrexate in human serum and plasma.

METHODS

Quantitative nuclear magnetic resonance (qNMR) was used to determine absolute methotrexate content in the standard. Separation was achieved on a biphenyl reversed-phase analytical column with mobile phases based on water and acetonitrile, both containing 0.1% formic acid. Sample preparation included protein precipitation in combination with high sample dilution, and method validation according to current guidelines. The following were assessed: selectivity (using analyte-spiked samples, and relevant structural-related compounds and interferences); specificity and matrix effects (via post-column infusion and comparison of human matrix vs. neat samples); precision and accuracy (in a five-day validation analysis). RMP results were compared between two independent laboratories. Measurement uncertainty was evaluated according to current guidelines.

RESULTS

The RMP separated methotrexate from potentially interfering compounds and enabled measurement over a calibration range of 7.200-5,700 ng/mL (0.01584-12.54 μmol/L), with no evidence of matrix effects. All pre-defined acceptance criteria were met; intermediate precision was ≤4.3% and repeatability 1.5-2.1% for all analyte concentrations. Bias was -3.0 to 2.1% for samples within the measuring range and 0.8-4.5% for diluted samples, independent of the sample matrix. RMP results equivalence was demonstrated between two independent laboratories (Pearson correlation coefficient 0.997). Expanded measurement uncertainty of target value-assigned samples was ≤3.4%.

CONCLUSIONS

This ID-LC-MS/MS-based approach provides a candidate RMP for methotrexate quantification. Traceability of methotrexate standard and the LC-MS/MS platform were assured by qNMR assessment and extensive method validation.

Systematic characterization of Lysergic Acid Diethylamide metabolites in Caenorhabditis elegans by ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry

Psychedelic compounds have gained renewed interest for their potential therapeutic applications, but their metabolism and effects on complex biological systems remain poorly understood. Here, we present a systematic characterization of Lysergic Acid Diethylamide (LSD) metabolites in the model organism Caenorhabditis elegans using state-of-the-art analytical techniques. By employing ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry, we putatively identified a range of LSD metabolites, shedding light on their metabolic pathways and offering insights into their pharmacokinetics. Our study demonstrates the suitability of Caenorhabditis elegans as a valuable model system for investigating the metabolism of psychedelic compounds and provides a foundation for further research on the therapeutic potential of LSD.

Immunoaffinity LC-MS/MS Quantification of the Sepsis Biomarker Procalcitonin Using Magnetic- and Polystyrene-Bead Immobilized Polyclonal Antibodies

Procalcitonin (PCT) is a biomarker for bacterial sepsis, and accurate quantification of PCT is critical for sepsis diagnosis and treatment. Immunological PCT quantification methods are routinely used in clinical laboratories, yet there is a need for harmonization of PCT quantification protocols. An orthogonal method to clinical immunological assays, such as LC-MS/MS, is required. In this study, a highly sensitive and robust immunoaffinity LC-MRM quantitative method for detecting procalcitonin in human serum has been developed. An initial comparison of immunocapture of PCT with a polyclonal anti-PCT antibody immobilized on polystyrene nanoparticles (Latex) and magnetic beads demonstrated superior performance with magnetic beads. Three tryptic PCT peptides from the N- and C-terminal regions of PCT were selected for LC-MS/MS quantification. For PCT quantification, an LLOQ of 0.25 ng/mL of PCT in human serum was achieved using a sample volume of 1 mL. The method's trueness and precision consistently lie within the 15% margin. The parallel measurement of three PCT peptides may allow future differentiation of intact PCT vs other PCT forms originating from potential degradation, processing, or polymorphisms. An established and validated LC-MRM-based quantification of PCT will be relevant as an orthogonal method for harmonization and standardization of clinical assays for PCT.

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.

Biomolecular map of albumin identifies signatures of severity and early mortality in acute liver failure

BACKGROUND & AIMS

Acute liver failure (ALF) is associated with high mortality. Alterations in albumin structure and function have been shown to correlate with outcomes in cirrhosis. We undertook a biomolecular analysis of albumin to determine its correlation with hepatocellular injury and early mortality in ALF.

METHODS

Altogether, 225 participants (200 patients with ALF and 25 healthy controls [HC]) were enrolled. Albumin was purified from the baseline plasma of the training cohort (ALF, n = 40; survivors, n = 8; non-survivors, n = 32; and HC, n = 5); analysed for modifications, functionality, and bound multi-omics signatures; and validated in a test cohort (ALF, n = 160; survivors, n = 53; non-survivors, n = 107; and HC, n = 20).

RESULTS

In patients with ALF, albumin is more oxidised and glycosylated with a distinct multi-omics profile than that in HC, more so in non-survivors (p <0.05). In non-survivors, albumin was more often bound (p <0.05, false discovery rate <0.01) to proteins associated with inflammation, advanced glycation end product, metabolites linked to arginine, proline metabolism, bile acid, and mitochondrial breakdown products. Increased bacterial taxa (Listeria, Clostridium, etc.) correlated with lipids (triglycerides [4:0/12:0/12:0] and phosphatidylserine [39:0]) and metabolites (porphobilinogen and nicotinic acid) in non-survivors (r2 >0.7). Multi-omics signature-based probability of detection for non-survival was >90% and showed direct correlation with albumin functionality and clinical parameters (r2 >0.85). Probability-of-detection metabolites built on the top five metabolites, namely, nicotinic acid, l-acetyl carnitine, l-carnitine, pregnenolone sulfate, and N-(3-hydroxybutanoyl)-l-homoserine lactone, showed diagnostic accuracy of 98% (AUC 0.98, 95% CI 0.95-1.0) and distinguish patients with ALF predisposed to early mortality (log-rank <0.05). On validation using high-resolution mass spectrometry and five machine learning algorithms in test cohort 1 (plasma and paired one-drop blood), the metabolome panel showed >92% accuracy/sensitivity and specificity for prediction of mortality.

CONCLUSIONS

In ALF, albumin is hyperoxidised and substantially dysfunctional. Our study outlines distinct 'albuminome' signatures capable of distinguishing patients with ALF predisposed to early mortality or requiring emergency liver transplantation.

IMPACTS AND IMPLICATIONS

Here, we report that the biomolecular map of albumin is distinct and linked to severity and outcome in patients with acute liver failure (ALF). Detailed structural, functional, and albumin-omics analysis in patients with ALF led to the identification and classification of albumin-bound biomolecules, which could segregate patients with ALF predisposed to early mortality. More importantly, we found albumin-bound metabolites indicative of mitochondrial damage and hyperinflammation as a putative indicator of <30-day mortality in patients with ALF. This preclinical study validates the utility of albuminome analysis for understanding the pathophysiology and development of poor outcome indicators in patients with ALF.

Tutorial review for peptide assays: An ounce of pre-analytics is worth a pound of cure

The recent increase in peptidomimetic-based medications and the growing interest in peptide hormones has brought new attention to the quantification of peptides for diagnostic purposes. Indeed, the circulating concentrations of peptide hormones in the blood provide a snapshot of the state of the body and could eventually lead to detecting a particular health condition. Although extremely useful, the quantification of such molecules, preferably by liquid chromatography coupled to mass spectrometry, might be quite tricky. First, peptides are subjected to hydrolysis, oxidation, and other post-translational modifications, and, most importantly, they are substrates of specific and nonspecific proteases in biological matrixes. All these events might continue after sampling, changing the peptide hormone concentrations. Second, because they include positively and negatively charged groups and hydrophilic and hydrophobic residues, they interact with their environment; these interactions might lead to a local change in the measured concentrations. A phenomenon such as nonspecific adsorption to lab glassware or materials has often a tremendous effect on the concentration and needs to be controlled with particular care. Finally, the circulating levels of peptides might be low (pico- or femtomolar range), increasing the impact of the aforementioned effects and inducing the need for highly sensitive instruments and well-optimized methods. Thus, despite the extreme diversity of these peptides and their matrixes, there is a common challenge for all the assays: the need to keep concentrations unchanged from sampling to analysis. While significant efforts are often placed on optimizing the analysis, few studies consider in depth the impact of pre-analytical steps on the results. By working through practical examples, this solution-oriented tutorial review addresses typical pre-analytical challenges encountered during the development of a peptide assay from the standpoint of a clinical laboratory. We provide tips and tricks to avoid pitfalls as well as strategies to guide all new developments. Our ultimate goal is to increase pre-analytical awareness to ensure that newly developed peptide assays produce robust and accurate results.

Evaluation of four automated clinical analyzers for the determination of total 25(OH)D in comparison to a certified LC-MS/MS

OBJECTIVES

The aim of this study was to compare the results of five methods for the determination of total 25(OH)D. For that purpose, two mass spectrometry and three immunoassay methods were used.

METHODS

A total of 124 serum samples were analyzed on five different methods (i.e., a reference LC-MS/MS, Cascadion, Lumipulse, Roche Elecsys II and Roche Elecsys III). Analytical performance against LC-MS/MS was evaluated and compared to the Milan models 1 (analytical performance based on the clinical outcome using thresholds of 12, 20 and 30 ng/mL) and 2 (analytical performance based on biological variation). Additionally, imprecision studies and accuracy using NIST SRM972a samples were carried out.

RESULTS

Compared to the reference LC-MS/MS method, the Lumipulse and the Roche Elecsys III assays reached the optimal criterion for bias, while the Cascadion met the desirable one. The Roche Elecsys II was not able to reach the minimal criteria. The proportion of correctly classified patients was higher using the Cascadion (95.2%) compared to the three immunoassays. In addition to its better precision, the Cascadion was not impacted by a high concentration of 3-epi-25(OH)D3 compared to the three immunoassays.

CONCLUSIONS

Compared to the LC-MS/MS reference method, the Cascadion presented the highest level of concordance at medical decision cut-offs for total 25(OH)D and reached the desirable specification for bias. Moreover, the presence of 3-epi-25(OH)D3 in enriched samples was only problematic in immunoassay methods, and especially considering Roche Elecsys methods. The release of performant fully automated mass spectrometry assays with high throughput might therefore facilitate the wide scale adoption of LC-MS/MS, even in non-specialized clinical laboratories.

NanoLC-EI-MS: Perspectives in Biochemical Analysis

Although LC-MS with atmospheric pressure ionization (API) sources is the primary technique used in modern bioanalytical studies, electron ionization mass spectrometry (EI-MS) can provide some substantial advantages over it. EI-MS is a matrix effect-free technique that provides reproducible and comparable mass spectra, serving as a compound fingerprint for easy identification through automated comparison with spectral libraries. Leveraging EI-MS in biochemical studies can yield critical analytical benefits for targeted and untargeted analyses. However, to fully utilize EI-MS for heavy and non-volatile molecules, a new technology that enables the coupling of liquid chromatography with EI-MS is needed. Recent advancements in nanoLC have addressed the compatibility issues between LC and EI-MS, and innovative interfacing strategies such as Direct-EI, liquid electron ionization (LEI), and Cold-EI have extended the application of EI-MS beyond the determination of volatile organic molecules. This review provides an overview of the latest developments in nanoLC-EI-MS interfacing technologies, discussing their scope and limitations. Additionally, selected examples of nanoLC-EI-MS applications in the field of biochemical analysis are presented, highlighting the potential prospects and benefits that the establishment of this technique can bring to this field.

Altered plasma levels of apixaban in major gastrointestinal tract surgery: a case report and review of the literature

Altered direct oral anticoagulant (DOAC) plasma levels can lead either to spontaneous hemorrhagic or thrombotic complications. We describe a case of suspected altered apixaban disposition in a patient with an upper gastrointestinal cancer resection treated with apixaban for non-valvular atrial fibrillation. Diagnosis of ischemic stroke for left hemiparesis was confirmed due to recent emergence of a hypodense area in the posterior capsular nucleus of ischemic reference in a context of binuclear capsular lacunar lesions. Thus, apixaban underexposure was suspected from anamnestic data and oral anticoagulation was switched to parenteral at the next scheduled dose for stroke recurrence. Before switching apixaban pharmacokinetic analysis was performed and unexpectedly showed apixaban plasma overexposure. After 3 days from the switch, the patient experienced spontaneous bleeding complications, for which the risk-benefit profile of continuing anticoagulant treatment for stroke recurrences warranted treatment discontinuation. Unexpected DOAC plasma exposure may present in special patient populations with thrombotic and bleeding complications. Though universally recognized therapeutic ranges have yet to be established for DOACs, periodic drug monitoring may aid in guiding optimization of DOAC therapy and reduce the risk of adverse events in special patient populations.

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.