Accurate Mass Spectrometry Research Articles

Comprehensive Coverage of Glycolysis and Pentose Phosphate Metabolic Pathways by Isomer-Selective Accurate Targeted Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Assay.

The accurate liquid chromatography-tandem mass spectrometry analysis of phosphorylated isomers from glycolysis and pentose phosphate pathways is a challenging analytical problem in metabolomics due to extraction problems from the biological matrix, adherence to stainless steel surfaces leading to tailing in LC, and incomplete separation of hexose and pentose phosphate isomers. In this study, we present a targeted HILIC-ESI-MS/MS method based on a BEH amide fully porous 1.7 μm particle column with an inert surface coating of column hardware and multiple reaction monitoring (MRM) acquisition fully covering the glycolysis and pentose phosphate pathway metabolites. To minimize contact of the phosphorylated analytes with stainless steel surfaces, a μ-ESI-MS probe with a hybrid electrode made of PEEKsil was employed. Optimized HILIC gradient elution conditions with 100 mM ammonium formate (pH 11) provided the separation of hexose monophosphate and pentose phosphate isomers. To ensure good retention time repeatability in HILIC, perfluoroalkoxy alkane bottles were used for the mobile phase (with sd over 60 runs between 0.01 and 0.02 min). For the quantitative assay, the U-13C-labeled cell extract was spiked prior to extraction by metal oxide-based affinity chromatography (MOAC) with TiO2 beads. The concentrations of the 24 targets were quantified in HeLa and human embryonic kidney (HEK293) cells. Erastin-induced ferroptosis in HEK293 cells was accompanied by enhanced levels of fructose-1,6-bis-phosphate, 2- and 3-phosphoglycerate, and 2,3-bis-phosphoglycerate.

Simultaneous determination of some coccidiostat antibiotics in food by liquid chromatography tandem mass spectrometry (LC-MS/MS)

Coccidiostats (anticoccidial antibiotics) are veterinary drugs widely used for the prevention and treatment of coccidiosis, especially in poultry farming. The illegal use of anticoccidial antibiotics, in the wrong dosage and duration, can lead to antibiotic residues in animal products and harm the health of consumers. In this study, a highly sensitive and accurate liquid chromatography-tandem mass spectrometry method was developed for the simultaneous analysis of anticoccidial antibiotics (diclazuril, nicarbazin, robenidin and salinomycin) in food. Samples were extracted using the QuEChERS method with acetonitrile (ACN) as the extraction solvent and cleaned with C18 adsorbent. The cleaned extracts were analyzed on an LC-MS/MS system with a C18 reversed-phase chromatography column (2.1 x 150 mm, 3.5 µm) and corresponding pre-column. The mobile phase used was 0.1% HCOOH in water and methanol (MeOH), the flow rate was 0.5 mL/min. The method had good specificity, the linear range was established in the range of 10-100 ng/mL, the correlation coefficient R2 > 0.998. The method recovery was in the range of 81-109% and the relative standard deviation (RSD%) was in the range of 1.77-10.13% for milk and meat samples. The limit of quantification and limit of detection of the method for four coccidiostat antibiotics were 3.0 µg/kg and 10 µg/kg, respectively. The method was applied to analyze the content of these four antibiotics in 31 food samples (meat and meat products, milk and dairy products) randomly purchased in Hanoi. The results did not detect four coccidiostat antibiotics in all 31 samples, initially showing that the residual contamination of coccidiostat antibiotics is basically safely controlled.

Identification of chemical constituents and pharmacokinetic characteristics of Xiaoyan Tuire Granule in rats

Xiaoyan Tuire Granule is a type of Chinese patent medicine that has been proven effective in treating respiratory tract infections. However, while it has been successfully introduced into clinical use, more knowledge is still needed regarding its chemical components and pharmacokinetics. This study investigated the chemical profile in the medicine and rat plasma by ultra high-performance liquid chromatography coupled with Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Orbitrap-MS/MS). Subsequently, it developed a validated ultra high-performance liquid chromatography coupled with quadrupole mass spectrometry (UHPLC-MS/MS) method for determining five components in rat plasma after oral administration of Xiaoyan Tuire Granule. As a result, a total of 106 constituents were inferred, including 9 terpenoids, 29 flavonoids, 33 organic acids, 12 phenylpropanoids and 23 other compounds. After administration, 86 compounds were inferred in rat plasma, including 73 prototypes and 13 metabolites. The metabolic pathways were primarily hydrogenation, glucuronic acid conjugation, sulfate conjugation, hydrolysis and methylation. The established method determined the contents of esculetin, esculin, isovitexin, caffeic acid and p-coumaric acid had a good separation, and all the legal verification met the requirements. The pharmacokinetic results indicate that the absorption rate of the five compounds in vivo was rapid, with a Tmax of less than 0.25 h, and the elimination rate was also fast, with a half-time (T1/2) ranging from 1.22 h to 2.19 h. It is worth noting that esculin and esculetin have similar half-time in vivo due to their structural similarities. Among these five compounds, the AUC0-∞ and MRT0-∞ of p-coumaric acid and esculetin were relatively higher, indicating higher exposure and longer residence time of both compounds in vivo. In conclusion, this paper researched the chemical constituents and pharmacokinetics of Xiaoyan Tuire Granule, which provided the reference for further study.

PFAS Levels, Early Life Factors, and Mammographic Breast Density in Premenopausal Women.

Mammographic breast density (MBD) is a strong risk factor and an intermediate phenotype for breast cancer, yet there are limited studies on how environmental pollutants are associated with MBD. We investigated associations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonate (PFHxS) levels with measures of MBD and evaluated if early life factors modified any associations. Metabolon performed metabolomics analysis using ultrahigh-performance liquid chromatography/tandem accurate mass spectrometry in fasting blood from 705 premenopausal women completing their annual screening mammogram in St. Louis, Missouri. We calculated least square means (LSM) of mammographic volumetric percent density (VPD), dense volume (DV), and nondense volume (NDV) by quartiles (Q) of PFOS, PFOA, and PFHxS from multivariable linear regression modeling overall and stratified by recruitment period, race, age at menarche, and body shape at age 10. Models were adjusted for age, age at menarche, body fat percentage, race, family history of breast cancer, oral contraceptive use, alcohol consumption, parity/age at first birth, and body shape at age 10. PFOS, PFOA, and PFHxS were not significantly associated with VPD or NDV. PFHxS was significantly positively associated with DV (, , , ; ). PFOS was positively associated with DV (, , , ; ) with DV being 8.1%, 12%, and 12.3% higher in Q2, Q3, and Q4 compared to Q1. Among women who were underweight/normal weight at age 10, PFOS was positively associated with VPD (, , , ; ) while there was an inverse association among women who were overweight/obese at age 10 (, , , ; ) (). We report novel associations of PFHxS and PFOS with DV in premenopausal women. PFOS, PFOA, and PFHxS were not associated with VPD and NDV. In addition, body shape at age 10 may modify the associations of PFOS with MBD. Further studies are needed to validate our findings and to evaluate the associations of other per- and polyfluoroalkyl substances (PFAS), as well as mixtures of PFAS, with MBD. https://doi.org/10.1289/EHP14065.

Determination of Anthropogenic Pollutants in Adipose Tissue of the Caspian Seal Pusa caspica Gmelin, 1788 by High-Resolution Accurate Mass Spectrometry.

Tissue contamination with persistent organic pollutants (POPs) in organisms proved possible to comprehensively characterize in a single test by combining gas chromatography and high-resolution accurate mass spectrometry. Adipose tissue samples were collected from two Caspian seals (Pusa caspica Gmelin, 1788) found dead on the Caspian Sea shore in 2020. Organochlorine pesticides, primarily DDT and HCH, and polychlorinated biphenyls (PCBs) were major pollutants found in the Caspian seals. The distribution of metabolites indicated the absence of recent pesticide use. The PCB content was relatively high, but still at the lower limit of the range of values determined previously, as was also the case with pesticides. Chlordanes, polychlorinated naphthalenes, and polybrominated diphenyl ethers were detected in minor quantities and were therefore not considered to be major pollutants of the Caspian seal. The pollutant levels were below a threshold at which a distinct effect on seal health can be expected. High-resolution accurate mass (HRAM) spectrometry was found to provide a convenient tool for both targeted and nontargeted analyses of a wide range of organic pollutants in a single experiment.

Improved multi-food allergen analysis of processed foods using HRAM-LC-MS/MS with an ELISA-validated extraction solution and MS sample prep kit.

Food allergens in processed foods are affected by heating, processing, and the food matrix. To conduct highly reliable tests, extracting allergens into test solutions is necessary for appropriate detection. In addition to the commonly used enzyme-linked immunosorbent assay (ELISA), liquid chromatography-mass spectrometry (LC-MS), which has the advantage of simultaneously detecting multiple allergens in foods, is being increasingly used. When managing food allergens at food manufacturing sites, obtaining the same measured values is desirable, regardless of the analytical method used. Therefore, in this study, we focused on the importance of pretreatment steps for LC-MS when examining food allergens in processed foods, which can be difficult to analyze. The ELISA method uses food extracts optimized for analyzing allergens in processed foods. We developed a high-resolution accurate mass spectrometry (HRAM)-LC-MS/MS method using the same food extract used in the ELISA method and an MS sample preparation kit. Multiple food allergen analysis was performed using 1, 5, 10, and 20ppm of allergen-incurred processed foods. Overall, a strong correlation was observed between the measured values of HRAM-LC-MS/MS and ELISA, demonstrating the applicability of multi-allergen analysis using LC-MS.

Exploring Pottery Function and Cooking Practices in Bronze Age Sicily: The Results of High-resolution GC-MS of Organic Residues

ABSTRACT Despite the extended application of GC-MS for detecting organic residues from archaeological ceramics, the potential of gas chromatography – high-resolution and accuracy mass spectrometry (GC-HRAMS) has not yet been fully explored. This study conducted lipid residue analysis (using an Exactive Orbitrap GC-MS system) of dolia and jars from two Early and Middle Bronze Age (2200-1450 BC) archaeological sites in south-eastern Sicily, comparing chromatograms obtained by both GC-HRAMS and GC coupled to quadrupole, low-resolution MS (GC-LRMS). The archaeological question aimed at verifying the use of the selected vessels for cooking purposes and exploring hypotheses concerning their employment in different cooking methods (boiling or roasting) based on the analysis of morphological features and burning traces on the surfaces. The results showed clear advantages of using GC-HRAMS in targeted and untargeted approaches.

Degradation of Isotianil in Water and Soil: Kinetics, Degradation Pathways, Mechanisms, and Ecotoxicity Assessments.

Pesticides are transported and transformed in soil and can enter surface water through various pathways. They undergo hydrolysis, oxidation, and photoconversion in surface water. Isotianil is a new fungicide that effectively controls rice blast. However, there are limited reports on its degradation. Herein, the hydrolysis and photolysis of isotianil in water and its degradation in soil samples from five provinces of China were investigated. The degradation products of isotianil were identified using ultrahigh-performance liquid chromatography-Q exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry, and four compounds were discovered for the first time. The degradation pathways of isotianil were inferred, and the reaction active site and degradation mechanism of isotianil were clarified based on density functional theory calculations. The ecotoxicity of the degradation product M118 (aminobenzonitrile) was found to be moderate toward Daphnia magna, which was predicted and confirmed by Ecological Structure Activity Relationships and the experiment, respectively. The results of this study will contribute to a better understanding of the fate of isotianil in the environment.

Quantification of amino acids secreted by yeast cells by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

Monitoring the levels of amino acids (AAs) in biological cell cultures provides key information to understand the regulation of cell growth and metabolism. Saccharomyces cerevisiae can naturally excrete AAs, making accurate detection and determination of amino acid levels within the cultivation medium pivotal for gaining insights into this still poorly known process. Given that most AAs lack ultraviolet (UV) chromophores or fluorophores necessary for UV and fluorescence detection, derivatization is commonly utilized to enhance amino acid detectability via UV absorption. Unfortunately, this can lead to drawbacks such as derivative instability, labor intensiveness, and poor reproducibility. Hence, this study aimed to develop an accurate and stable hydrophilic interaction liquid chromatography-tandem mass spectrometry analytical method for the separation of all 20 AAs within a short 17-min run time. The method provides satisfactory linearity and sensitivity for all analytes. The method has been validated for intra- and inter-day precision, accuracy, recovery, matrix effect, and stability. It has been successfully applied to quantify 20 AAs in samples of yeast cultivation medium. This endeavor seeks to enhance our comprehension of amino acid profiles in the context of cell growth and metabolism within yeast cultivation media.

Effect of biological sex and short-term high-fat diet on cellular proliferation, ribosomal biogenesis, and targeted protein abundance in murine articular cartilage

ObjectiveTo identify factors contributing to sex-differences in OA risk by evaluating the short-term effect of high-fat (HF) diet on sex-specific changes in cartilage cell proliferation, ribosomal biogenesis, and targeted extra-cellular and cellular protein abundance. Materials and methodsKnee cartilage was harvested to the subchondral bone from 20-week-old female and male C57BL/6J mice fed a low-fat or HF diet for 4 weeks and labeled with deuterium oxide for 1, 3, 5, 7, 15, or 21 days. Deuterium enrichment was quantified in isolated DNA and RNA to measure cell proliferation and ribosomal biogenesis, respectively. Protein concentration was measured using targeted high resolution accurate mass spectrometry. ResultsHF diet increased the maximal deuterium incorporation into DNA from approximately 40 to 50%, albeit at a slower rate. These findings, which were magnified in female versus male mice, indicate a greater number of proliferating cells with longer half-lives under HF diet conditions. HF diet caused distinct sex-dependent effects on deuterium incorporation into RNA, increasing the fraction of ribosomes undergoing biogenesis in male mice and doubling the rate of ribosome biogenesis in female mice. HF diet altered cartilage protein abundance similarly in both sexes, except for matrilin-3, which was more abundant in HF versus LF conditions in female mice only. Overall, HF diet treatment had a stronger effect than sex on cartilage protein abundance, with most changes involving extracellular matrix and matrix-associated proteins. ConclusionsShort-term HF diet broadly altered cartilage matrix protein abundance, while sex-dependent effects primarily involved differences in cell proliferation and ribosomal biogenesis.

Non-targeted identification of tianeptine photodegradation products in water samples by UHPLC-QTOF MS/MS

This study aims the characterization of several tianeptine transformation products in ultrapure water by simulated sunlight irradiation. Tianeptine was completely degraded after 106 h of exposition following pseudo-first-order kinetics (half-life time = 12.0 ± 2.4 h). Furthermore, an ultra-high-performance liquid chromatography coupled with a high-resolution quadrupole time-of-flight-mass spectrometry method was developed and fully validated taking into account different method performance parameters for the quantification of tianeptine in river water up to a concentration of 400 pg L−1. Following a non-targeted approach based on mass data-independent acquisition, eight different transformation products not previously reported in the literature were identified and accordingly elucidated, proposing a photodegradation mechanism based on the accurate tandem mass spectrometry information acquired. Irradiation experiments were replicated for a tianeptine solution prepared in a blank river water sample, resulting in the formation of the same transformation products and similar degradation kinetics. In addition, a toxicity assessment of the photoproducts was performed by in silico method, being generally all TPs of comparable toxicity to the precursor except for TP1, and showing a similar persistence in the environment except for TP2 and TP6, while TP4 was the only TP predicted as mutagenic. The developed method was applied for the analysis of four river water samples.

Profiling of bioactive compounds identified in functional gummies by metabolomics analysis using High-Resolution Accurate Mass-Spectrometry

The consumers demand for healthier and fortified products received much attention these days. The main aim of this study was to prepare functional gummies that contain beneficial bioactive compounds such as flavonoids, terpenoids, polyphenols, and phenolics. The gummies were prepared using varying concentrations of jamun pulp and pear pomace powder, which are both known for their health benefits. Optimization of the prepared gummies was done on the basis of their antioxidant profile. The bioactive compounds found in the gummies were characterized by High-Resolution Accurate Mass-Spectrometry. These bioactive compounds were divided into different categories, such as phenolic acids, flavonoids, as well as terpenoids. Analytical characterization was employed to identify both known and unknown bioactive compounds and metabolites in the optimized product. The results showed that the optimized gummies (FG3) exhibited desirable sensory, textural, and functional properties. FG3 contains a substantial amount of dietary fibre and bioactive compounds, including flavonoids, terpenoids, phenolics, triterpenes, which exhibits health benefits such as anti-cancerous, anti-inflammatory etc., Overall, the developed gummies provide a promising solution to address health-related issues.

Detection and quantification of organosulfur species in the Tagish Lake Meteorite by highly sensitive LC‐MS

AbstractWe analyzed the methanol extracts of six pristine specimens of the Tagish Lake meteorite (TL1, TL4, TL5A, TL6, TL7, and TL10a) and heated and unheated samples of Allende using high‐performance liquid chromatography coupled with high‐resolution, accurate mass–mass spectrometry (HPLC‐HRAM‐MS). All samples contained ppm levels of sulfate and methyl sulfate. The most abundant organosulfur compound in the methanol extracts of the Tagish Lake and Allende samples was methyl sulfate, which was likely formed primarily via an esterification reaction between intrinsic sources of methanol and sulfate. A homologous series of polythionic acids was also observed in the extracts of the Tagish Lake specimens and Allende. The polythionic acids were the most abundant soluble inorganic sulfur species found in the meteorites. Our results were confirmed using retention time, accurate mass, isotope matching, and tandem mass spectrometry (MS/MS). Hydroxymethanesulfonic acid, previously reported in Tagish Lake, was found only in an unheated Allende sample and in low abundance. Here, we propose possible sulfate formation pathways that begin with interstellar dimethyl sulfide, dimethyl disulfide, methyl sulfide, or methanethiol via cold, nebular processes within the interstellar medium and continue via MSA as an intermediary compound ending within planetary bodies with sulfate and methyl sulfate as the final products.

Determination of vancomycin and meropenem in serum and synovial fluid of patients with prosthetic joint infections using UPLC-MS/MS.

Numerous studies have suggested that intra-articular administration of antibiotics following primary revision surgery may be one of the methods for treating prosthetic joint infection (PJI). Vancomycin and meropenem are the two most commonly used antibiotics for local application. Determining the concentrations of vancomycin and meropenem in the serum and synovial fluid of patients with PJI plays a significant role in further optimizing local medication schemes and effectively eradicating biofilm infections. This study aimed to establish a rapid, sensitive, and accurate ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining the concentrations of vancomycin and meropenem in human serum and synovial fluid. Serum samples were processed using acetonitrile precipitation of proteins and dichloromethane extraction, while synovial fluid samples were diluted before analysis. Chromatographic separation was achieved in 6min on a Waters Acquity UPLC BEH C18 column, with the mobile phase consisting of 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). Quantification was carried out using a Waters XEVO TQD triple quadrupole mass spectrometer with an electrospray ionization (ESI) source in positive ion mode. The multiple reaction monitoring (MRM) mode was employed to detect the following quantifier ion transitions: 717.95-99.97 (norvancomycin), 725.90-100.04 (vancomycin), 384.16-67.99 (meropenem). The method validation conformed to the guidelines of the FDA and the Chinese Pharmacopoeia. The method demonstrated good linearity within the range of 0.5-50 μg/ml for serum and 0.5-100 μg/ml for synovial fluid. Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, matrix effect, and stability validation results all met the required standards. This method has been successfully applied in the pharmacokinetic/pharmacodynamic (PK/PD) studies of patients with PJI.

Characterization and quantitation of a sulfoconjugated metabolite for detection of methyltestosterone misuse and direct identification by LC-MS

Methyltestosterone (MT) is one of the most frequently misused anabolic androgenic steroids detected in doping control analysis. The metabolism of MT in humans leads to several phase І metabolites and their corresponding phase Ⅱ conjugates. Previous studies have postulated the 3α-sulfoconjugate of 17α-methyl-5β-androstane-3α,17β-diol (S2) as principal sulfate metabolite of MT, with a detection window exceeding 10 days. However, a final direct and unambiguous confirmation of the structure of this metabolite is missing until now. In this study, we established an approach to detect and identify S2, using intact analysis by liquid chromatography hyphenated with tandem mass spectrometry (LC-MS/MS) without complex sample pretreatment. An in vitro study yielded the LC-MS/MS reference retention times of all 3-sulfated 17-methylandrostane-3,17-diol diastereomers, allowing for accurate structure assignment of potentially detected metabolites. In an in vivo excretion study with a single healthy male volunteer, the presence of the metabolite S2 was confirmed after a single oral dose of 10 mg MT. The reference standard was chemically synthesized, characterized by accurate mass mass spectrometry (MS) and nuclear magnetic resonance (NMR), and quantified by quantitative NMR (qNMR). Thus, this study finally provides accurate structure information on the S2 metabolite and a direct analytical method for detection of MT misuse. The availability of the reference material is expected to facilitate further evaluation and subsequent analytical method validation in anti-doping research.

Urinary metabolites indicative of the administration of hypoxen monitored by liquid chromatography-high resolution/accurate mass tandem mass spectrometry.

Hypoxen, a poly(dihydroxyphenylene) thiosulfonate-based drug, has been investigated concerning its effect on mitochondrial respiration and the utilization of lactate, especially in the context of strenuous exercise. Since 2023, patterns of use regarding hypoxen amongst the athletic population are monitored by the World Anti-Doping Agency (WADA) and its accredited anti-doping laboratories, necessitating information on suitable urinary markers indicative of the administration of hypoxen. In this exploratory study, urine samples collected post-administration of 1.5 and 2.0g of hypoxen were analyzed by means of liquid chromatography-high resolution/high mass accuracy (tandem) mass spectrometry, which allowed for the identification of eight analytes that were plausibly attributable to metabolites of hypoxen. The identified species were assigned to the unconjugated species of S-(2,2',5,5'-tetrahydroxy-[1,1'-biphenyl]-3-yl) sulfurothioate and its glucuronide and additional tentatively identified analytes comprising a mercaptobenzene core structure. Including the identified markers into routine doping control analytical procedures enabled the detection of hypoxen use in athletes' doping control samples, thus contributing relevant information to WADA's monitoring program.

460 Changes in Lipid Profiles with Progression of Pregnancy in Black Women

OBJECTIVES/GOALS: Pregnant African American (Black women) have higher rates of adverse pregnancy outcomes compared to other races and routine monitoring of lipid levels is not currently in practice in prenatal care. We hypothesized that lipid profiles would show variation across pregnancy indicative of specific requirements during gestation and fetal development. METHODS/STUDY POPULATION: We used an untargeted lipidome analysis approach to investigate lipid metabolism with the progression of pregnancy. Pregnant Black women were recruited at prenatal clinics in Midwest (Metro Detroit, Michigan and Columbus, Ohio), women under 18 or above 45 years of age were not enrolled due to metabolic changes associated with these age groups. Women signed the consent forms and plasma samples were collected at 8-18 weeks at (T1), 22-29 weeks (T2) and 30-36 weeks (T3) of pregnancy. Samples from sixty-three women (mean age 27.41 ± 5.61 years) who had term birth (completed 37 weeks of pregnancy) were subjected to “shotgun” Orbitrap high resolution/ accurate mass spectrometry. Mixed-effects models were used to quantify systematic changes in relative lipid abundances over time using R lme4 and ggplot2 packages. RESULTS/ANTICIPATED RESULTS: Total lipids and some major lipid classes showed a significant increase with the progression of pregnancy. Phospholipids and glycerolipids exhibited a gradual increase throughout pregnancy, while sphingolipids and total sterol lipids displayed a more pronounced increase at the T3 timepoint. Acylcarnitines, hydroxy acylcarnitines and Lyso phospholipids levels significantly decrease from T1 to T3. One of the interesting finding was that non-esterified fatty acids decreased from T1 to T2 and increased again from T2 to T3, suggesting a possible role for these lipids during the later stages of pregnancy. The fatty acids showing this trend included key fatty acids- Linoleic Acid, Arachidonic Acid, Alpha-linolenic acid, Eicosapentaenoic acid, Docosapentaenoic acid, Docosahexaenoic acid. DISCUSSION/SIGNIFICANCE: Mapping lipid trends during pregnancy could lend support to a precision health approach to reduce perinatal health disparities among pregnant Black women. The findings from this study will be used to identify biomarkers and study associations with social and environmental factors responsible for adverse perinatal outcome in pregnant Black women.

Novel method for determination of colistin sulfate in human plasma by high-performance liquid chromatography-tandem mass spectrometry and its clinical applications in critically ill patients

Colistin is a last-resort antibiotic used for treating infections caused by carbapenem-resistant Gram-negative bacteria, particularly in critically patients, nevertheless its therapeutic window is narrow, and requires monitoring. A determination method suitable for clinical detection is conducive to ensure its efficacy and safety of patients with severe infection. We developed and validated a concise and accurate high-performance liquid chromatography-tandem mass spectrometry method for the determination of colistin A and B in human plasma. We used a Kinetex C18 column (50 mm × 2.1 mm, 2.6 μm) with acetonitrile (containing 0.1% formic acid) as the protein precipitant and water (containing 0.2% formic acid and 5 mmol/L ammonium formate) - acetonitrile (containing 0.2% formic acid) as the gradient elution. The calibration curves were linear over concentration ranges of 0.06–4.00 μg/mL (colistin A) and 0.1–7.0 μg/mL (colistin B). The precision, accuracy, matrix effect, extraction recovery, and stability were all validated. This method was applied to the therapeutic drug monitoring for 50 critically ill patients. The trough, peak, and average steady-state concentrations of these patients were 0.8 ± 0.4, 1.4 ± 0.5, and 1.0 ± 0.4 μg/mL, respectively. And the concentrations of colistin in human plasma were closely related to the patient's renal function.

Mass Spectrometry-Based Method to Measure Aflatoxin B1 DNA Adducts in Formalin-Fixed Paraffin-Embedded Tissues.

Aflatoxin B1 (AFB1) is a potent human liver carcinogen produced by certain molds, particularly Aspergillus flavus and Aspergillus parasiticus, which contaminate peanuts, corn, rice, cottonseed, and ground and tree nuts, principally in warm and humid climates. AFB1 undergoes bioactivation in the liver to produce AFB1-exo-8,9-epoxide, which forms the covalently bound cationic AFB1-N7-guanine (AFB1-N7-Gua) DNA adduct. This adduct is unstable and undergoes base-catalyzed opening of the guanine imidazolium ring to form two ring-opened diastereomeric 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxy-aflatoxin B1 (AFB1-FapyGua) adducts. The AFB1 formamidopyrimidine (Fapy) adducts induce G → T transversion mutations and are likely responsible for the carcinogenic effects of AFB1. Quantitative liquid chromatography-mass spectrometry (LC-MS) methods have shown that AFB1-N7-Gua is eliminated in rodent and human urine, whereas ring-opened AFB1-FapyGua adducts persist in rodent liver. However, fresh frozen biopsy tissues are seldom available for biomonitoring AFB1 DNA adducts in humans, impeding research advances in this potent liver carcinogen. In contrast, formalin-fixed paraffin-embedded (FFPE) specimens used for histopathological analysis are often accessible for molecular studies. However, ensuring nucleic acid quality presents a challenge due to incomplete reversal of formalin-mediated DNA cross-links, which can preclude accurate quantitative measurements of DNA adducts. In this study, employing ion trap or high-resolution accurate Orbitrap mass spectrometry, we demonstrate that ring-opened AFB1-FapyGua adducts formed in AFB1-exposed newborn mice are stable to the formalin fixation and DNA de-cross-linking retrieval processes. The AFB1-FapyGua adducts can be detected at levels comparable to those in a match of fresh frozen liver. Orbitrap MS2 measurements can detect AFB1-FapyGua at a quantification limit of 4.0 adducts per 108 bases when only 0.8 μg of DNA is assayed on the column. Thus, our breakthrough DNA retrieval technology can be adapted to screen for AFB1 DNA adducts in FFPE human liver specimens from cohorts at risk of this potent liver carcinogen.

Comparative pharmacokinetics of six components in normal and rheumatoid arthritis rats after intragastrical administration of Qianghuo Shengshi Decoction granules by LC-MS/MS

ObjectiveTo investigate the plasma pharmacokinetics of six representative components (nodakenin, osthole, 5-O-methylvisammioside, ferulic acid, liquiritigenin, and liquiritin), which were the ingredients of Qianghuo Shengshi Decoction (QSD) granules, in normal and rheumatoid arthritis (RA) rats administrated QSD granules intragastrically. MethodsA rapid and accurate ultra-high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of six components in plasma, and it showed a good specificity, linearity, intra-day and inter-day precision, intra-day and inter-day accuracy, extraction recovery, stability, and the less matrix effect. ResultsThe validated LC-MS/MS method was successfully used to compare the plasma pharmacokinetics of six ingredients between normal and RA rats after intragastrical administration of QSD granules and differences in the pharmacokinetics were found in two types of rats. The absorption rate in the RA rats was lower for nodakenin, osthole, 5-O-methylvisammioside, liquiritigenin and liquiritin than in the normal group, while the absorption rate of ferulic acid remained constant in two groups. Incomparisonwith the normal rats, the exposure concentration of nodakenin was higher and that of other five components except for nodakenin was lower under pathological conditions. Additionally, the absorptive amount of nodakenin, osthole, 5-O-methylvisammioside and liquiritin was increased and that of ferulic acid and liquiritigenin was reduced in the RA rats than in the normal rats. Compared with the normal rats, the retention time of nodakenin, ferulic acid and liquiritin was reduced in vivo, whereas the retention time of osthole, 5-O-methylvisammioside and liquiritigenin was raised in the body for the RA rats. In contrast to the normal rats, the data demonstrated an increase in the elimination velocity of nodakenin and a decrease in the elimination velocity of the other five components except for nodakenin in the pathological state. ConclusionThis study showed that the pharmacokinetic behavior of the six components, nodakenin, osthole, 5-O-methylvisammioside, ferulic acid, liquiritigenin, and liquiritin, is different in vivo between normal and pathological states of rats, and this research provided the necessary experimental data to explain the pharmacokinetics of QSD granules in both normal and pathological states and provide some references for its clinical application at some level.