Combined Liquid Chromatography-tandem Mass Spectrometry Research Articles

Reference intervals for LC-MS /MS measurements of plasma renin activity, aldosterone, angiotensin II, and 24-hour urinary aldosterone in Northern Chinese Han population

BackgroundExamination of aldosterone to Renin Ratio (ARR) and plasma aldosterone concentration (PAC) or 24-h urinary aldosterone excretion (24-h UALD) was the necessary tests in confirmatory tests for primary aldosteronism (PA). We developed a combined liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for plasma renin activity (PRA), PAC, and angiotensin II (Ang II) and investigated their reference intervals (RIs) in northern Chinese Han population. The RIs of 24-h UALD excretion were also studied using LC-MS/MS. MethodsA total of 309 healthy volunteers were recruited in 3 cities in China. PRA, PAC, Ang II, and 24-h UALD were measured using the laboratory-developed LC-MS/MS. Multiple linear regression and the variance component model were applied to determine if the RI needed to be split. The RIs of PRA, PAC, and Ang II were determined using the nonparametric percentile method. ResultsThe laboratory-developed LC-MS/MS method was verified and showed good performance. Standard deviation ratio (SDR) sex for PAC and SDR region for Ang II are 0.466 and 0.407, respectively, indicating that the RIs of PAC and Ang II must be divided by sex and region, respectively. In addition, the SDR 24hUK for 24-h UALD is 0.579, indicating that the RI of 24-h UALD must be partitioned by urine potassium. ConclusionRIs were established for tests related to the renin-angiotensin-aldosterone system in the apparently healthy northern Chinese Han population by the LC-MS/MS method.

Development and validation of a combined liquid chromatography tandem-mass spectrometry assay for the quantification of aprepitant and dexamethasone in human plasma to support pharmacokinetic studies in pediatric patients

A pharmacokinetic study was set up to investigate the pharmacokinetics of the anti-emetic agents aprepitant and dexamethasone and the drug-drug interaction between these drugs in children. In order to quantify aprepitant and dexamethasone, a liquid chromatography-tandem mass spectrometry assay was developed and validated for the simultaneous analysis of aprepitant and dexamethasone. Protein precipitation with acetonitrile-methanol (1:1, v/v) was used to extract the analytes from plasma. The assay was based on reversed-phase chromatography coupled with tandem mass spectrometry detection operating in the positive ion mode. The assay was validated based on the guidelines on bioanalytical methods by the US Food and Drug Administration and European Medicines Agency. The calibration model was linear and a weighting factor of 1/concentration2 was used over the range of 0.1–50 ng/mL for aprepitant and 1–500 ng/mL for dexamethasone. Intra-assay and inter-assay bias were within ±20% for all analytes at the lower limit of quantification and within ±15% at remaining concentrations. Dilution integrity tests showed that samples exceeding the upper limit of quantification can be diluted 100 times in control matrix. Stability experiments showed that the compounds are stable in the biomatrix for 25 h at room temperatures and 89 days at −20 °C. This assay is considered suitable for pharmacokinetic studies and will be used to study the drug-drug interaction between aprepitant and dexamethasone in pediatric patients.

Expression of key auxin biosynthesis genes correlates with auxin and starch content of developing wheat (Triticum aestivum) grains.

The effect of auxin on wheat (Triticum aestivum L.) grain size is contentious. Additionally, the contributions to the IAA pool from de novo synthesis versus hydrolysis of IAA-glucose are unclear. Here, we describe the first comprehensive study of tryptophan aminotransferase and indole-3-pyruvate mono-oxygenase expression from 5 to 20 days after anthesis. A comparison of expression data with measurements of endogenous IAA via combined liquid chromatography-tandem mass spectrometry using heavy isotope labelled internal standards indicates that TaTAR2-B3, TaYUC9-A1, TaYUC9-B, TaYUC9-D1, TaYUC10-A and TaYUC10-D are primarily responsible for IAA production in developing grains. Furthermore, these genes are expressed specifically in developing grains, like those found in rice (Oryza sativa L.) and maize (Zea mays L.). Our results cast doubt on the proposed role of THOUSAND-GRAIN WEIGHT gene, TaTGW6, in promoting larger grain size via negative effects on grain IAA content. Work on this gene overlooked the contribution of IAA biosynthesis from tryptophan. Although IAA synthesis occurs primarily in the endosperm, we show the TaYUC9-1 group is also strongly expressed in the embryo. Within the endosperm, TaYUC9-1 expression is highest in aleurone and transfer cells, suggesting that IAA has a key role in differentiation of these tissues as has been proposed for other cereals.

TMT-MS/MS proteomic analysis of the carbohydrate-active enzymes in the fruiting body of Pleurotus tuoliensis during storage.

The fruiting body of Pleurotus tuoliensis deteriorates rapidly after harvest, causing a decline in its commercial value and a great reduction in its shelf life. According to the present research, carbohydrate-active enzymes (CAZymes) may cause the softening, liquefaction and autolysis of mature mushrooms after harvest. To further understand the in vivo molecular mechanism of CAZymes affecting the postharvest quality of P. tuoliensis fruiting bodies, a tandem mass tags labelling combined liquid chromatography-tandem mass spectrometry (TMT-MS/MS) proteomic analysis was performed on P. tuoliensis fruiting bodies during storage at 25 °C. A total of 4737 proteins were identified, which had at least one unique peptide and had a confidence level above 95%. Consequently, 1307 differentially expressed proteins (DEPs) were recruited using the criteria of abundance fold change (FC) >1.5 or < 0.67 and P < 0.05. The identified proteins were annotated by dbCAN2, a meta server for automated CAZymes annotation. Subsequently, 222 CAZymes were obtained. Several CAZymes participating in the cell wall degradation process, including β-glucosidase, glucan 1,3-β-glucosidase, endo-1,3(4)-β-glucanase and chitinases, were significantly upregulated during storage. The protein expression level of CAZymes, such as xylanase, amylase and glucoamylase, were upregulated significantly, which may participate in the P. tuoliensis polysaccharide degradation. The identified CAZymes degraded the polysaccharides and lignin, destroying the cell wall structure, preventing cell wall remodeling, causing a loss of nutrients and the browning phenomenon, accelerating the deterioration of P. tuoliensis fruiting body. © 2020 Society of Chemical Industry.

Production and roles of IAA and ABA during development of superior and inferior rice grains.

Current understanding of the role of plant hormones during cereal grain filling is confounded by contradictory reports on hormone production that is based on poor methodology. We report here on the accurate measurement of indole-3-acetic acid (IAA) and abscisic acid (ABA) by combined liquid chromatography-tandem mass spectrometry in multiple reaction-monitoring mode with heavy isotope labelled internal standards. ABA and IAA contents of superior versus inferior rice grains (ABA maxima 159 ng g-1 FW and 109 ng g-1 FW, IAA maxima 2 µg g-1 FW and 1.7 µg g-1 FW respectively) correlated with the expression of biosynthetic genes and with grain fill. Results confirm that grain ABA is produced primarily by OsNCED2(5), but suggest that ABA import and metabolism also play important roles in ABA regulation. The IAA content of grains is primarily influenced by OsYUC9 and OsYUC11. However, the distinct expression profile of OsYUC12 suggests a specific role for IAA produced by this enzyme. Co-expression of OsYUC12 with OsIAA29 indicates their involvement in a common signalling pathway. Co-expression and cis-element analysis identified several aleurone-specific transcriptional regulators as well as glutelin as strong candidates for detailed investigation for direct regulation by the auxin-signalling pathway.

Quantitative proteomic characterization of lung tissue in idiopathic pulmonary fibrosis

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive, eventually fatal disease. IPF is characterized by excessive accumulation of the extracellular matrix (ECM) in the alveolar parenchyma and progressive lung scarring. The pathogenesis of IPF and whether the ECM involved in the process remain unknown.MethodsTo identify potential treatment target and ECM associated proteins that may be involved in the development of IPF, we employed isobaric tag for relative and absolute quantitation (iTRAQ) combined liquid chromatography–tandem mass spectrometry (LC–MS/MS) approach to examine protein expression in lung tissues from IPF patients.ResultsA total of 662 proteins with altered expression (455 upregulated proteins and 207 downregulated proteins) were identified in lung tissue of IPF patients compared with control. KEGG pathway enrichment analysis showed that the altered proteins in lung tissue mainly belonged to the PI3K-Akt signaling, focal adhesion, ECM-receptor interaction, and carbon metabolism pathways. According to the bioinformatic definition of the matrisome, 229 matrisome proteins were identified in lung tissue. These proteins comprised the ECM of lung, of which 104 were core matrisome proteins, and 125 were matrisome-associated proteins. Of the 229 ECM quantified proteins, 56 significantly differentially expressed proteins (19 upregulated proteins and 37 downregulated proteins) were detected in IPF lung tissue samples. In addition to proteins with well-known functions such as COL1A1, SCGB1A1, TAGLN, PSEN2, TSPAN1, CTSB, AGR2, CSPG2, and SERPINB3, we identified several novel ECM proteins with unknown function deposited in IPF lung tissue including LGALS7, ASPN, HSP90AA1 and HSP90AB1. Some of these differentially expressed proteins were further verified using Western blot analysis and immunohistochemical staining.ConclusionsThis study provides a list of proteomes that were detected in IPF lung tissue by iTRAQ technology combined with LC–MS/MS. The findings of this study will contribute better understanding to the pathogenesis of IPF and facilitate the development of therapeutic targets.

Detection of Stimulants and Narcotics by Liquid Chromatography-Tandem Mass Spectrometry and Gas Chromatography-Mass Spectrometry for Sports Doping Control.

Sports drug testing laboratories are required to detect several classes of compounds that are prohibited at all times, which include anabolic agents, peptide hormones, growth factors, beta-2 agonists, hormones and metabolic modulators, and diuretics/masking agents. Other classes of compounds such as stimulants, narcotics, cannabinoids, and glucocorticoids are also prohibited, but only when an athlete is in competition. A single class of compounds can contain a large number of prohibited substances and all of the compounds should be detected by the testing procedure. Since there are almost 70 stimulants on the prohibited list it can be a challenge to develop a single screening method that will optimally detect all the compounds. We describe a combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) testing method for detection of all the stimulants and narcotics on the World Anti-Doping Agency prohibited list. Urine for LC-MS/MS testing does not require sample pretreatment and is a direct dilute and shoot method. Urine samples for the GC-MS method require a liquid-liquid extraction followed by derivatization with trifluoroacetic anhydride.

Combined Liquid Chromatography–Tandem Mass Spectrometry Analysis of Progesterone Metabolites

Progesterone has a number of important functions throughout the human body. While the roles of progesterone are well known, the possible actions and implications of progesterone metabolites in different tissues remain to be determined. There is a growing body of evidence that these metabolites are not inactive, but can have significant biological effects, as anesthetics, anxiolytics and anticonvulsants. Furthermore, they can facilitate synthesis of myelin components in the peripheral nervous system, have effects on human pregnancy and onset of labour, and have a neuroprotective role. For a better understanding of the functions of progesterone metabolites, improved analytical methods are essential. We have developed a combined liquid chromatography—tandem mass spectrometry (LC-MS/MS) method for detection and quantification of progesterone and 16 progesterone metabolites that has femtomolar sensitivity and good reproducibility in a single chromatographic run. MS/MS analyses were performed in positive mode and under constant electrospray ionization conditions. To increase the sensitivity, all of the transitions were recorded using the Scheduled MRM algorithm. This LC-MS/MS method requires small sample volumes and minimal sample preparation, and there is no need for derivatization. Here, we show the application of this method for evaluation of progesterone metabolism in the HES endometrial cell line. In HES cells, the metabolism of progesterone proceeds mainly to (20S)-20-hydroxy-pregn-4-ene-3-one, (20S)-20-hydroxy-5α-pregnane-3-one and (20S)-5α-pregnane-3α,20-diol. The investigation of possible biological effects of these metabolites on the endometrium is currently undergoing.

Simultaneous Determination of α- and γ-Mangostins in Mouse Plasma by HPLC–MS/MS Method: Application to a Pharmacokinetic Study of Mangosteen Extract in Mouse

Recently, extracts from the pericarp of mangosteen, Garcinia mangostana L., exhibited various pharmacological properties such as anti-oxidative, anti-inflammatory, anti-bacterial and chemopreventive activities. Albeit it has diverse application, there is little information about its pharmacokinetic aspects. Thus, the present study was undertaken to develop the simultaneous determination of α- and γ-mangostins (α- and γ-MG), major and active compounds, from extracts for the application of pharmacokinetic studies in mice using combined liquid chromatography–tandem mass-spectrometry and microsampling systems. The intra- and inter-validation, precision, accuracy, stability, recovery and matrix effects of α- and γ-MG were conducted in mouse plasma. Based on the developed analytical methods, pharmacokinetic parameters of α- and γ-MG after intravenous and oral administration of mangosteen extract were calculated. In sample preparation steps, the biological samples were deproteinized by acetonitrile and chromatographic separation was accomplished on a C18 column. The detection was accomplished by multiple-reaction monitoring scanning after electrospray ionization source in the positive ionization mode. The optimized mass transition ion pairs (m/z) for quantitation were 411.062 → 354.900, 397.384 → 340.900, and 808.379 → 527.200 for α- and γ-MG and docetaxel (internal standard), respectively. The total run time was 5 min. The results provided a meaningful basis for the preclinical and clinical application of mangosteen extract.

A comparative study of the pharmacokinetics of traditional and automated dosing/blood sampling systems using gabapentin

Objective:The present study was undertaken to investigate the pharmacokinetics (PKs) of gabapentin as determined by traditional manual blood sampling and by using an automated dosing/blood sampling technique in awake and freely moving rats using combined liquid chromatography tandem mass-spectrometry (LC-MS/MS).Materials and Methods:PK comparisons were conducted by allocating rats into two groups; an automated dosing/blood sampling (ADI/ABS) group (IV study, n = 6 and intragastric study, n = 6) and a manual group (IV study, n = 6 and oral study, n = 6). A series of blood samples from carotid artery were taken at specified times and analyzed using a validated LC-MS/MS method. Various PK parameters like area under curve (AUCinf), maximum concentration, time to reach maximum concentration, terminal half life, distribution volume at the steady state, and total clearance were calculated and the two study groups were compared with respect to these parameters.Results:Significant differences in PK parameters were observed between the manual group and the ADI/ABS group and respective bioavailability were measured (46.82 ± 19.45% and 61.54 ± 21.23%, respectively) which is 1.31-fold difference (P = 0.0051, P<0.05).Conclusion:The described ADI/ABS method was found to be a useful drug development tool for accelerating the pace of preclinical in vivo studies and for obtaining reliable and accurate PK parameters even from single animals as it minimized interanimal and physiological variations.

Chemical evidence for wine production around 4000 BCE in the Late Chalcolithic Near Eastern highlands

Archaeological excavations in the Areni-1 cave complex in southeastern Armenia revealed installations and artifacts dating to around 4000 cal. BCE that are strongly indicative of wine production. Chemical evidence for this hypothesis is presented here using a new method to detect the anthocyanin malvidin that gives grapes and pomegranates their red color. Using solid phase extraction (SPE) and alkaline treatment of the samples, followed by combined liquid chromatography-tandem mass spectrometry (LC-MS/MS), this method was applied to authentic standards and four ancient potsherds from Armenia and Syria. A positive result was observed for two of the samples from the Areni-1 cave complex, adding evidence supporting the hypothesis that wine was produced in the Near Eastern highlands in the Late Chalcolithic Period.

Method for determination of methadone in exhaled breath collected from subjects undergoing methadone maintenance treatment

At present drugs of abuse testing using exhaled breath as specimen is only possible for alcohol. However, we recently discovered that using modern liquid chromatography–mass spectrometry technique amphetamine and methamphetamine is detectable in exhaled breath following intake in drug addicts. We therefore undertook to develop a method for determination of methadone in exhaled breath from patients undergoing methadone maintenance treatment. Exhaled breath was collected from 13 patients after intake of the daily methadone dose. The compounds were trapped by filtering the air through a C18 modified silica surface. After elution of any trapped methadone the extract was analysed by a combined liquid chromatography–tandem mass spectrometry method. Recovery of trapped methadone from the filter surface was 96%, no significant matrix effect was observed, and the quantification using methadone-d3 as an internal standard was accurate (<10% bias) and precise (coefficient of variation 1.6–2.0%). Methadone was indisputably identified by means of the mass spectrometry technique in exhaled breath samples from all 13 patients. Identification was based on monitoring two product ions in selected reaction monitoring mode with correct relative ratio (±20%) and correct retention time. Excretion rates ranged from 0.39 to 78 ng/min. No methadone was detected in 10 control subjects. This finding confirms that breath testing is a new possibility for drugs of abuse testing. Collection of exhaled breath specimen is likely to be more convenient and safe as compared to other matrices presently in use.

Amphetamines Detected in Exhaled Breath from Drug Addicts: A New Possible Method for Drugs-of-Abuse Testing

Testing for drugs of abuse in sample matrices alternative to urine such as blood, sweat, and saliva have received increasing attention and is needed, for example, in traffic medicine. Human breath is known to contain a large number of substances including non-volatile molecules. We explore whether intake of amphetamines could be detected by analytical investigation of exhaled breath from drug addicts. Exhaled breath was collected from 12 drug addict patients after recovering from acute intoxication. Self-reported intake of "amphetamine" was confirmed by analysis of urine and plasma. The compounds were trapped by filtering the air through a modified silica surface and subsequently analyzed by a combined liquid chromatography-tandem mass spectrometry method. As a control, exhaled breath was collected in the same way from eight healthy volunteers. Here we report for the first time that amphetamine and methamphetamine are present in exhaled breath following ingestion of these compounds by drug addicts. Both amphetamine and methamphetamine were indisputably identified by means of the mass spectrometry technique in exhaled breath samples from all 12 patients. Identifications were based on monitoring two product ions in selected reaction monitoring mode and having correct relative ratios (+/- 20%). Excretion rates ranged from 0.2 to 139 pg/min. No amphetamine or methamphetamine was detected in the control subjects. This finding, using a yet non-validated sampling procedure, opens a new possibility for drugs-of-abuse testing. Collection of exhaled breath is likely to be more convenient and safe as compared to matrices presently in use.

Stimulation of sphingosine 1-phosphate signaling as an alveolar cell survival strategy in emphysema.

Vascular endothelial growth factor receptor (VEGFR) inhibition increases ceramides in lung structural cells of the alveolus, initiating apoptosis and alveolar destruction morphologically resembling emphysema. The effects of increased endogenous ceramides could be offset by sphingosine 1-phosphate (S1P), a prosurvival by-product of ceramide metabolism. The aims of our work were to investigate the sphingosine-S1P-S1P receptor axis in the VEGFR inhibition model of emphysema and to determine whether stimulation of S1P signaling is sufficient to functionally antagonize alveolar space enlargement. Concurrent to VEGFR blockade in mice, S1P signaling augmentation was achieved via treatment with the S1P precursor sphingosine, S1P agonist FTY720, or S1P receptor-1 (S1PR1) agonist SEW2871. Outcomes included sphingosine kinase-1 RNA expression and activity, sphingolipid measurements by combined liquid chromatography-tandem mass spectrometry, immunoblotting for prosurvival signaling pathways, caspase-3 activity and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assays, and airspace morphometry. Consistent with previously reported de novo activation of ceramide synthesis, VEGFR inhibition triggered increases in lung ceramides, dihydroceramides, and dihydrosphingosine, but did not alter sphingosine kinase activity or S1P levels. Administration of sphingosine decreased the ceramide-to-S1P ratio in the lung and inhibited alveolar space enlargement, along with activation of prosurvival signaling pathways and decreased lung parenchyma cell apoptosis. Sphingosine significantly opposed ceramide-induced apoptosis in cultured lung endothelial cells, but not epithelial cells. FTY720 or SEW2871 recapitulated the protective effects of sphingosine on airspace enlargement concomitant with attenuation of VEGFR inhibitor-induced lung apoptosis. Strategies aimed at augmenting the S1P-S1PR1 signaling may be effective in ameliorating the apoptotic mechanisms of emphysema development.

Detection of breast cancer biomarkers in nipple aspirate fluid by SELDI-TOF and their identification by combined liquid chromatography-tandem mass spectrometry

Screening mammography is the most effective tool available for breast cancer detection. While screening mammography saves lives, it has intrinsic problems that limit further improvement. We hypothesize that protein biomarkers in nipple aspirate fluid (NAF) may separate the cancer from the non-cancer state, and therefore can be used for breast cancer detection. In this study the proteins in NAF were analyzed by surface-enhanced laser desorption ionization coupled to time-of-flight mass spectrometry (SELDI-TOF) in the m/z 5,000-85,000 range. Two methods were used to normalize spectra. Then differentially expressed signals that separate cancer from non-cancer conditions were selected by two specifically developed statistical algorithms. Proteins of interest were identified by combined liquid chromatography-tandem mass spectrometry. A set of 8 markers were identified which collectively gave 63% sensitivity, 89% specificity and 76% accuracy for distinguishing cancer from non-cancer. Further improvements in the specificity and sensitivity of this strategy could come from the development of methods for more precise quantification of the biomarkers of interest and also from focusing on the low abundant components that are not evident when unfractionated NAF is analyzed directly.

Combined liquid chromatography–Tandem mass spectrometry as an analytical method for high throughput screening for X-linked adrenoleukodystrophy and other peroxisomal disorders: Preliminary findings

Utilizing combined liquid chromatography–tandem mass spectrometry (LC–MS/MS) as the analytical method, we have demonstrated a ten to sixtyfold excess of lysophosphatidyl choline containing hexacosanoic acid (26:0) in dried blood spots on a filter paper matrix from 25 male patients with X-linked adrenoleukodystrophy and nine patients with peroxisome biogenesis disorders compared to 19 controls. There was no overlap between normal subjects versus affected subjects.