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Free fatty acids (FFAs) are important energy sources and significant for energy transport in the body. They also play a crucial role in cellular oxidative stress responses, following cell membrane depolarization, making accurate quantification of FFAs essential. This study presents a novel supercritical fluid chromatography-mass spectrometry (SFC-MS) method using selected ion recording in negative electrospray ionization mode, enabling rapid quantification of 31 FFAs within 6 min without derivatization. FFAs are identified and quantified using an HSS C18 SB column and a secondary mobile phase consisting of methanol with formic acid by detecting their [M − H]⁻ ions. Calibration curves showed strong linearity (R² ≥ 0.9910), spanning 1000–12,000 ng/mL for short-chain FFAs and 50–1200 ng/mL for medium- and long-chain FFAs. The method achieves detection limits as low as 1 ng/µL for short-chain FFAs and 0.05 pg/µL for other FFAs per on-column injection. The method demonstrated high accuracy and precision, with bias and coefficients of variation maintained below 15% across five quality control levels. Freeze–thaw and autosampler stability studies confirmed the behavior of matrix-matched standards under optimal storage conditions. The validated method was applied to the analysis of pharmaceutical-grade egg yolk powders, using 13 deuterated FFAs as internal standards (IS) in comparison with heptadecanoic acid (C17:0). Significant variations in FFA quantification using two different IS approaches underscore the importance of selecting an appropriate IS. In summary, this study introduces a reliable and validated SFC-MS method for analyzing FFAs ranging from C4 to C26, requiring minimal sample preparation.

Tryptophan-derived metabolites, a group of neurotransmitters essential for various brain functions, play key roles in regulating mood, movement, sleep, and cognition. However, the comprehensive characterisation of tryptophan-melatonin pathway metabolites is challenging due to factors such as their structural diversity, chemical complexity, low concentrations, and instability of these metabolites. In this study, we developed and validated an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) methodology with electrospray ionisation for the simultaneous separation and quantification of tryptophan metabolites in human plasma. The analytical calibration ranges in plasma were 0.50-200 ng/mL for serotonin, 0.01-5 ng/mL for N-acetylserotonin, 0.01-20 ng/mL for tryptamine, 0.01-20 ng/mL for 6-sulfatoxymelatonin, 0.01-20 ng/mL for 6-hydroxymelatonin, 0.01-100 ng/mL for melatonin, and 0.10-20 ng/mL for N-acetyltryptamine, with correlation coefficients ranging from 0.954 for N-acetyltryptamine to 0.997 for tryptamine. The intraday and interday precision remained consistently below 15 % for all analytes. Most analytes met the accuracy criteria, except for N-acetyltryptamine at the lowest quality control level (0.2 ng/mL), where the intraday and interday accuracy were 22.4 % and 17.4 %, respectively. In conclusion, this novel method allows for rapid identification of tryptophan-melatonin pathway intermediates in less than ten minutes, including seven distinct melatonin-related analytes. This suggests that it may find use in everyday clinical and scientific endeavours.

This study explores the metabolic differences between human and murine plasma in addition to differences between murine subcutaneous and visceral white adipose tissue. A quantitative and semi-quantitative targeted method was developed and validated for this purpose. The quantitative method includes tryptophan and its metabolites in addition to tyrosine, phenylalanine, taurine, B vitamins, neopterin, cystathionine and hypoxanthine. While the semi-quantitative method includes; 3-indoleacetic acid, 5-hydroxyindoleacetic acid, acetylcholine, asymmetric dimethylarginine, citrulline and methionine. Sample preparation was based on protein precipitation, while quantification was conducted using ultrahigh-performance liquid chromatography coupled to a quadrupole Orbitrap tandem mass spectrometer with electrospray ionization in the parallel reaction monitoring (PRM) mode. The low limit of quantification for all metabolites ranged from 1 to 200 ng mL^-1. Matrix effects and recoveries for stable isotope labelled internal standards were evaluated, with most having a coefficient of variation (CV) of less than 15%. Results showed that a majority of the analytes passed both the intra- and interday precision and accuracy criteria. The comparative analysis of human and murine plasma metabolites reveals species-specific variations within the tryptophan metabolic pathway. Notably, murine plasma generally exhibits elevated concentrations of most compounds in this pathway, with the exceptions of kynurenine and quinolinic acid. Moreover, the investigation uncovers noteworthy metabolic disparities between murine visceral and subcutaneous white adipose tissues, with the subcutaneous tissue demonstrating significantly higher concentrations of tryptophan, phenylalanine, tyrosine, and serotonin. The findings also show that even a semi-quantitative method can provide comparable results to quantitative methods from other studies and be effective for assessing metabolites in a complex sample. Overall, this study provides a robust platform to compare human and murine metabolism, providing a valuable insight to future investigations. A validated HRMS method for measuring tryptophan metabolites and related compounds has been developed, with simple sample preparation, successfully applied in human and murine plasma, as well as murine white adipose tissue.

Problem: Preterm birth (PTB) is a leading cause of infant mortality and morbidity. The pathogenesis of PTB is complex and involves many factors, including socioeconomy, inflammation and infection. Asymmetric dimethylarginine, ADMA and symmetric dimethylarginine, SDMA are involved in labor as inhibitors of nitric oxide, a known relaxant of the uterine smooth muscles. Arginines are scarcely studied in relation to PTB and we aimed to investigate arginines (ADMA, SDMA and L-arginine) in women with spontaneous PTB and term birth.

Methods of the Study: The study was based on data from the population-based, prospective cohort BASIC study conducted in Uppsala County, Sweden, between September 2009 and November 2018. Arginines were analyzed by Ultra-High Performance Liquid Chromatography using plasma samples taken at the onset of labor from women with spontaneous PTB (n = 34) and term birth (n = 45). We also analyzed the inflammation markers CRP, TNF-R1 and TNF-R2 and GDF-15.

Results: Women with spontaneous PTB had higher plasma levels of ADMA (p < 0.001), and L-Arginine (p = 0.03). In addition, inflammation marker, TNF-R1 (p = 0.01) was higher in spontaneous PTB compared to term birth. Further, in spontaneous PTB, no significant correlations could be observed when comparing levels of arginines with inflammation markers, except ADMA versus CRP.

Conclusions: These findings provide novel evidence for the potential involvement of arginines in the pathogenesis of spontaneous PTB and it seems that arginine levels at labor vary independently of several inflammatory markers. Further research is warranted to investigate the potential of arginines as therapeutic targets in the prevention and management of spontaneous PTB.

Phytosterols are essential structural components of plant cell membranes and possess health-related benefits, including lowering blood cholesterol levels in humans. Numerous analytical methods are being used to profile plant and animal sterols. Chromatography hyphenated to tandem mass spectrometry, is a better option due to its specificity, selectivity, and sensitivity. An ultra-performance supercritical fluid chromatography hyphenated with atmospheric pressure chemical ionization (APCI) tandem mass spectrometric method was developed and eval-uated for fingerprint analysis of seven phytosterols. Mass spectrometry fragmentation behavior was used for phytosterol identification, and multiple reaction monitoring scanning was utilized for phytosterol confirmation, where APCI outperformed superiority in terms of ion intensity, particularly in the production of [M + H-H2O]+ ions rather than [M + H]+ ions. The chromatographic conditions were thoroughly evaluated, and the ionization parameters were optimized as well. In a 3 min. run, the seven phytosterols were separated concurrently. The calibration and repeatability tests were conducted to check the instrument's performance, and the results indicated that all of the phytosterols tested had correlation coefficients (r2) greater than 0.9911 over the con-centration range of 5-5000 ng/mL. The limit of quantification was below 20 ng/mL for all the tested analytes except for stigmasterol and campesterol. The partially validated method was applied for the evaluation of phytosterols in pure coconut oil and palm oil in order to demonstrate its applicability. Total sterols in coconut and palm oils were 126.77 ng/mL and 101.73 ng/mL, respectively. In comparison to earlier methods of phytosterol analysis, the novel method offers a far faster, more sensitive, and more selective analytical process.

Recently, traditional rice cultivars have become more popular than new, enhanced rice varieties, with the main focus being on their health benefits. Few rice cultivars have been thoroughly studied to understand their nutritional and health benefits. Inductively coupled plasma atomic emission/mass spectroscopy methods were used to determine the concentrations of 24 key nutrients and trace elements in 104 traditional rice types (Oryza sativa L.) grown in Sri Lanka. Compared to the Codex Alimentarius provisional tolerable daily intake for 24 different elements, the concentrations of toxic elements such as As, Cd, Pb and Cr were significantly lower (P < 0.05), and most of the nutritional elemental concentrations were substantially higher (P < 0.05) in evaluated traditional rice varieties. Furthermore, Pb, Bi, B, K, Mg, S, Zn and Fe concentrations among traditional rice varieties were not substantially different (P > 0.05). Notably, several traditional rice varieties (i.e. Rathu Heenati, Pragathi Wee, Weda Heenati, etc.) contained significantly high levels of selenium (& AP;250 & mu;g L-1 DM, P < 0.05), an important trace element that is deficient in the diets of 1 billion people globally.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder among women, and the majority suffers from hyperandrogenism. Hyperandrogenism causes psychological morbidity and impaired quality of life in women with PCOS during the reproductive years, but data on prevalence and impact during midlife are lacking. Thus, this study aimed to address whether hyperandrogenism persists into midlife and, if so, what impact it has on quality of life. In order to answer this question, we performed a multicenter prospective cohort study, where we included women already diagnosed with PCOS who had reached the age of 45 years or more and age-matched controls. All participants underwent a physical exam, structured medical interview, biochemical testing and filled out self-assessment questionnaires. More than 40% of the women with PCOS and 82% of those who presented with the hyperandrogenic phenotype at the diagnostic work-up still suffered from hirsutism. Circulating testosterone levels were similar between women with PCOS and controls while free androgen index was higher in women with PCOS, independent of weight. Women with hyperandrogenic PCOS expressed persisting concerns regarding hirsutism at the follow-up assessment. In conclusion, women with PCOS who present with hyperandrogenic symptoms at the time they are diagnosed with PCOS have a higher risk of persistent androgenic symptoms and impaired quality of life in midlife.

PROBLEM: The exact biochemical mechanisms that initiate labor are not yet fully understood. Nitric oxide is a potent relaxant of uterine smooth muscles until labor starts, and its precursor is L-arginine. Asymmetric (ADMA) and symmetric (SDMA) dimethylarginines, are potent NO-inhibitors. However, arginines (dimethylarginines and L-arginine) are scarcely studied in relation to labor and childbirth. We aimed to investigate arginines in women with spontaneous (SLVB) and induced (ILVB) term labor with vaginal birth and in women undergoing elective caesarean section (ECS).

METHOD OF STUDY: Women at gestational week 16-18 were recruited to the population-based prospective cohort study BASIC at the Uppsala University Hospital, Sweden. Plasma samples taken at start of labor were analyzed for arginines, from SLVB (n = 45), ILVB (n = 45), and ECS (n = 45), using Ultra-High Performance Liquid Chromatography. Between-group differences were assessed using Kruskal-Wallis and Mann-Whitney U-test.

RESULTS: Women with SLVB and ILVB had higher levels of ADMA (p < .0001), SDMA (p < .05) and lower L-arginines (p < .01), L-arginine/ADMA (p < .0001), and L-arginine/SDMA (p < .01, respectively <.001) compared to ECS. However, ILVB had higher ADMA (p < .0001) and lower L-arginine (p < .01), L-arginine/ADMA (p < .0001), and L-arginine/SDMA (p < .01) compared to SLVB. Results are adjusted for gestational length at birth and cervical dilatation at sampling.

CONCLUSION: Our novel findings of higher levels of dimethylarginines in term vaginal births compared to ECS give insights into the biochemical mechanisms of labor. These findings might also serve as a basis for further studies of arginines in complicated pregnancies and labor.

Evaluating total parenteral nutrition (TPN) products for quality assurance and quality control is crucial due to the chemical complexity of its components. With the advent of exploring different approaches for analysing TPN components using tandem mass spectrometry techniques, there is still a need for a robust and reproducible method for industrial routine analyses. This study allows simple, simultaneous determination of 22 fatty acids (FAs) commonly found in TPN components using gas chromatography-mass spectrometry (GC-MS). Five different transesterification techniques were applied for the FA standards and the sodium methoxide in methanol-dimethyl carbonate method was selected due to its good methylation efficiency. Fatty acid methyl esters (FAMEs) were separated in gas chromatography using an HP-5MS UI column with helium as the carrier gas. Mass spectrometry was used to fragment and quantify FAMEs using electron ionization (EI) and selected ion monitoring (SIM) mode. The analytical method was evaluated using the guidelines from the US Food and Drug Agency (FDA) and European Medicines Agency (EMA) in compliance with the International Council for Harmonization (ICH) document Q2(R2). Correlation coefficients (R-2) of the calibration curves for FAMEs were 0.99, except for C24:1 n-9 and C24:0, both R-2 = 0.98. The limits of detection (LOD) and quantification (LOQ) were found to be 1.69 mu g mL(-1) and 5.14 mu g mL(-1), respectively. The linear range was from 3.10-179.9 mu g mL(-1) for most FAMEs, except for C18:1 n-7 (3.96-224.9 mu g mL(-1)) and C18:1 n-9 (6.30-349.57 mu g mL(-1)). The intra-day and inter-day precision coefficients of variance (CV) of the method were less than 11.10% and 11.30%, respectively. Freeze-thaw cycles and ambient temperature measurements were performed for assessing sample stability. The validated method was applied to analyse major TPN components-fish and olive oils, and an unidentified lipid sample. The presented GC-MS method is simple and robust in the identification and quantification of 22 fatty acids simultaneously in the tested TPN components.

Gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system (CNS) and outside of the CNS, found in the highest concentrations in immune cells and pancreatic beta-cells. GABA is gaining increasing interest in diabetes research due to its immune-modulatory and beta-cell stimulatory effects and is a highly interesting drug candidate for the treatment of type 1 diabetes (T1D). GABA is synthesized from glutamate by glutamic acid decarboxylase (GAD), one of the targets for autoantibodies linked to T1D. Using mass spectrometry, we have quantified the endogenous circulating levels of GABA in patients with new-onset and long-standing T1D and found that the levels are unaltered when compared to healthy controls, i.e., T1D patients do not have a deficit of systemic GABA levels. In T1D, GABA levels were negatively correlated with IL-1 beta, IL-12, and IL-15 15 and positively correlated to levels of IL-36 beta and IL-37. Interestingly, GABA levels were also correlated to the levels of GAD-autoantibodies. The unaltered levels of GABA in T1D patients suggest that the GABA secretion from beta-cells only has a minor impact on the circulating systemic levels. However, the local levels of GABA could be altered within pancreatic islets in the presence of GAD-autoantibodies.