Search Results (130)

Background: Peritoneal dialysis (PD) effluent of kidney failure patients represents an accessible liquid biopsy of the peritoneal cavity, yet the mechanisms determining its molecular composition remain poorly understood. We applied an integrative multi-omics approach to characterize the composition, transport dynamics, and molecular origin of the PD effluentome. Methods: Cell-free effluent, effluent cells, and plasma were collected from stable PD patients during standardized peritoneal equilibration tests in a randomized clinical trial. Targeted metabolomics, proteomics, and transcriptomic profiling were integrated with a reference human plasma proteome to investigate temporal molecular changes, peritoneal transport characteristics, and protein origin. Results: A total of 207 metabolites and 2970 proteins were identified in PD effluent. Metabolites exhibited distinct class-specific transport kinetics, with rapid equilibration of amino acids and biogenic amines, whereas lipids remained markedly underrepresented despite prolonged dwell times, indicating that transport is governed by physicochemical properties beyond molecular size alone. The effluent proteome underwent concordant alteration, with dwell time-dependent enrichment of pathways related to extracellular matrix organization, angiogenesis, coagulation, and tissue repair. Integrative analysis of the effluent proteome, effluent-cell transcriptome, and human plasma proteome resolved distinct plasma-associated, effluent cell-associated, resident peritoneal tissue-associated, and mixed-origin protein populations. Conclusions: This study establishes the first systems-level approach describing the composition, transport dynamics, and molecular origin of the PD effluentome. By transforming PD effluent into a biologically interpretable molecular readout of peritoneal membrane biology, this work provides a reference for the mechanistic interpretation of effluent-derived biomarkers and supports future therapeutic monitoring and precision medicine in PD. Full article

Free amino acids (FAAs) are important low-molecular-weight metabolites involved in osmotic regulation, acid–base balance, and nitrogen metabolism in fish exposed to saline–alkaline environments. To characterize tissue-specific FAA responses in mandarin fish (Siniperca chuatsi), 10 cm juveniles were exposed for 96 h to freshwater control (FW), salinity stress (S, salinity 8), alkalinity stress (A, alkalinity 20 mmol/L), or combined saline–alkaline stress (SA, salinity 8 + alkalinity 20 mmol/L). The contents of 19 FAAs were compared among plasma, muscle, liver, brain, and kidney. FAA profiles showed clear tissue specificity. Total FAA (17) decreased in plasma under all stress treatments, increased in muscle under S and SA but decreased under A, increased in liver and kidney, and decreased under single stress but increased under combined stress in brain. Distinct tissue distribution patterns were observed for functional FAA groups. Under salinity stress, osmoregulation-related FAAs, particularly Ala and Pro, showed higher contents mainly in muscle, liver, and kidney. Under alkalinity stress, kidney showed concurrent increases in multiple FAAs, including Ala, Pro, Glu, Gln, Val, Ile, and Leu, whereas brain was characterized by a high Gln content. Under combined saline–alkaline stress, liver was the main tissue in which multiple functional FAA groups increased simultaneously, kidney maintained elevated levels of several FAAs, and brain showed treatment-specific high levels of Gln and Tau. Redundancy analysis (RDA) indicated weak constrained explanatory power of salinity and alkalinity for the overall FAA profile, whereas tissue-specific differentiation was evident. Glu, Gln, and Pro showed directional consistency with the salinity vector, whereas Val and Leu tended to align with the alkalinity-related ordination direction. Overall, acute saline–alkaline exposure induced a functional and tissue-specific distribution pattern of FAAs rather than a uniform whole-body shift in mandarin fish. Full article

Gestational diabetes mellitus (GDM), as one of the most common metabolic disorders occurring during pregnancy, represents a significant public health concern due to its rising prevalence and the numerous complications that can affect both the mother and the foetus. In recent years, there has been growing interest in the use of omics technologies, such as metabolomics and proteomics, in research on the pathogenesis and early detection of GDM. The aim of this paper was to summarise the current knowledge on metabolomic and proteomic changes observed in women with GDM and to assess the potential usefulness of these methods in identifying biomarkers of the disease. The narrative review was conducted in accordance with the PRISMA 2020 statement, using PubMed and Web of Science until 23 December 2025. The studies analysed show that GDM is associated with abnormalities in the metabolism of lipids, amino acids, carbohydrates and metabolites associated with the gut microbiota. The most commonly observed changes included: elevated levels of branched-chain amino acids, free fatty acids and purine metabolites, as well as changes in the metabolism of phospholipids and acylcarnitines. Multi-omics studies also indicate significant changes in plasma protein and lipid profiles. The data collected suggest that omics technologies may be a promising tool for identifying early biomarkers of GDM and for developing our understanding of the pathophysiological mechanisms of this condition. Nevertheless, further studies involving larger and more diverse patient populations are needed to confirm their diagnostic and clinical value. Full article

This study integrated echocardiography with widely targeted metabolomics to decipher how plasma metabolic dynamics couple with cardiac geometry in Yili horses during incremental treadmill exercise. Nine speed-type horses underwent a graded exercise test (6% incline; 0 to 9 m/s). Jugular venous blood samples collected at rest (0 m/s) and at 3, 5, 7, and 9 m/s were profiled by LC-MS, and Pearson correlation analysis was applied to relate differentially expressed metabolites (DEMs) to twenty echocardiographic structural indices. A core set of 314 shared DEMs (124 upregulated, 190 downregulated) was identified across all exercise comparisons, spanning amino acids, organic acids, and fatty acyls. These metabolites were mapped to ABC transporter, thermogenesis, aldosterone-regulated sodium reabsorption, steroid hormone biosynthesis, and one-carbon folate metabolism pathways. At rest (0 m/s), right ventricular end-diastolic dimension correlated positively with arginyl-isoleucine (p < 0.001), whereas left ventricular free wall thickness (diastolic and systolic) correlated positively with undecanedioic acid (p < 0.001) and proline-hydroxyproline (p < 0.01). At peak exercise (9 m/s), left ventricular mass and left ventricular mass index correlated positively with succinic acid (p < 0.05) and methylmalonic acid (p < 0.05), while left ventricular minor axis correlated with carnitine C14:2 and carnitine C12:1 (p < 0.05). Left ventricular end-systolic dimension and left atrial end-diastolic dimension correlated negatively with cysteine-glutathione disulfide and N2-(1-carboxyethyl)-L-arginine, respectively. These findings illuminate a robust metabolic–cardiac structure axis: amino acid metabolites support collagen matrix turnover and redox homeostasis, organic acids sustain mitochondrial energy flux and antioxidant defense, and fatty acyls fuel continuous contractile activity via enhanced fatty acid oxidation. This metabolome-informed framework furnishes a mechanistic basis for precision training and performance phenotyping in equine athletes. Full article

Metabolic health extends beyond BMI: some obese individuals remain metabolically resilient, while many normal-weight individuals exhibit hidden dysfunction. In Qatar, where obesity and metabolic disorders are widespread, understanding these divergent phenotypes is clinically paramount. This study maps the circulating metabolites and biological pathways associated with metabolic dysfunction. Clinical data from 6000 adults in the Qatar Biobank were used to determine obesity prevalence and classify metabolic health status among individuals with normal-weight and obese individuals. Comprehensive statistical analyses were conducted to determine associations between metabolic phenotypes and clinical parameters. Untargeted plasma metabolomics were performed in a subset of participants. Differential metabolite expression and pathway enrichment analyses were conducted to identify the distinct metabolic signatures underlying metabolic health. Mean age ranged from 30.9 ± 11.3 years in metabolically healthy normal-weight (MHNW) individuals to 46.0 ± 10.9 years in metabolically unhealthy obese (MUHO) individuals, with females predominating in the MHO group (65.2%). MUHO participants had higher rates of diabetes (21%), hypertension (34.7%), and insulin resistance (96.8%). Elevated C-peptide, uric acid, ferritin, and inflammatory markers were positively associated with metabolic unhealthiness, particularly in obese females, whereas estradiol and free thyroxine showed protective associations. Metabolomic profiling revealed distinct lipid and amino acid signatures differentiating MHO, MUHO, and MHNW phenotypes, with pathway analysis highlighting disruptions in lipid metabolism, amino acid pathways, and membrane transport. Metabolic heterogeneity in obesity reflects differences in coordinated biochemical regulation rather than adiposity alone. Identified metabolite signatures and ratios may serve as biomarkers of metabolic resilience and early risk stratification. Full article

Inadequate choline intake-induced choline metabolic stress (CMS) has been divergently linked to metabolic dysfunction-associated steatotic liver disease (MASLD), yet underlying mechanisms remain unclear. We hypothesized that CMS modifies plasma-free amino acid (PFAA) signatures to influence MASLD risk. In a nested case–control study of 125 participants, dietary choline intake and blood choline metabolites were assessed together with targeted metabolomics and transcriptomic profiling. MASLD was characterized by low choline intake, reduced plasma betaine/choline ratio (Pbcr), elevated homocysteine, increased branched-chain amino acids (BCAAs), and depleted serine/glycine, achieving strong predictive accuracy (AUC = 0.90). CMS was associated with reduced lymphocytic transcripts involved in BCAA catabolism and altered mTORC1/Akt/IRS1 signaling. Nonlinear Pbcr- and intake-dependent MASLD risk patterns were attenuated after adjustment for genetic–metabolite networks. These findings identify CMS-responsive metabolic mediators supporting precision choline interventions. Full article

Fibromyalgia (FM) is a complex chronic syndrome marked by widespread musculoskeletal pain, neurocognitive dysfunction (“fibro-fog”), and autonomic disturbances. Clinical management remains challenging due to subjective symptom reporting and the lack of definitive diagnostics. Emerging evidence points to a multifactorial origin involving central sensitization, neuroendocrine imbalance, and systemic immune-inflammatory alterations. A wide array of candidate biomarkers has been reported in FM, encompassing neurotransmitters (serotonin, norepinephrine), excitatory and inhibitory amino acids, metabolic and glycolytic enzymes, stress-related proteins, autoantibodies, oxidative stress markers and pro-inflammatory cytokines. This molecular heterogeneity reflects the systemic and multidimensional nature of FM. However, most of these biomarkers have been primarily investigated in serum or plasma, where analytical validation and reference ranges are more established. In contrast, the exploration of salivary biomarkers—although highly attractive due to its non-invasive, stress-free, and repeatable collection—remains comparatively limited. Saliva contains a reduced concentration range of many systemic markers and is strongly influenced by circadian rhythms, stress, flow rate, and oral health conditions. While promising candidates such as α-amylase, cortisol, calgranulins, and selected metabolic enzymes have shown potential in saliva, many proposed FM-related biomarkers lack full analytical validation, standardized protocols, and clinically defined reference intervals in this matrix. In this context, non-invasive electrochemical biosensors represent a transformative technological approach. Advanced electrode architectures incorporating nucleic acid probes, redox reporters, and nanostructured materials offer high sensitivity in low-volume and low-concentration biofluids such as saliva. The integration of multiplexed biomarker panels into portable platforms could enable real-time, longitudinal monitoring of FM pathophysiology, supporting phenotype stratification, personalized therapeutic adjustment, and objective disease activity tracking. Full article

Yucca decipiens is a native species from arid and semi-arid regions with emerging nutritional and biotechnological potential. This study evaluated its proximate composition, elemental profile determined by inductively coupled plasma mass spectrometry (ICP-MS), and growth performance under nursery conditions. Proximate analysis revealed a high dietary fiber content in leaves (58.93%) and higher carbohydrate levels in stems (28.83%). Free amino acid content was significantly higher in stems (2.75 g histidine equivalents kg⁻¹) than in leaves (1.76 g kg⁻¹). Multi-elemental profiling (63 elements) showed organ-specific accumulation patterns, with essential macro- and micronutrients predominantly concentrated in leaves, including potassium (28,334 ppm) and calcium (15,345 ppm), while iron was the most abundant trace element in stems (1253 ppm). Principal component analysis (PCA) revealed clear organ-specific mineral partitioning between leaves and stems, indicating differentiated physiological roles and potential selective biomass utilization. Growth assessment conducted over a two-year period demonstrated steady biomass accumulation and good adaptive performance under nursery conditions. Overall, the results highlight the emerging nutritional and agroindustrial relevance of Yucca decipiens for applications in semi-arid environments. Full article

Reusable enzyme carriers are valuable for proteomic workflows, yet many supports are expensive or lack robustness. This study describes the covalent immobilization of recombinant trypsin on micrometer-sized corundum particles and assesses their performance in protein digestion and antibody analysis. The corundum surface was cleaned with potassium hydroxide, silanized with 3-aminopropyltriethoxysilane and activated with glutaraldehyde. Recombinant trypsin was then attached, and the resulting imines were reduced with sodium cyanoborohydride. Aromatic amino acid analysis (AAAA) estimated an enzyme loading of approximately 1 µg/mg. Non-specific adsorption of human plasma proteins was suppressed by blocking residual aldehydes with a Tris-glycine-lysine buffer. Compared with free trypsin, immobilization shifted the temperature optimum from 50 to 60 °C and greatly improved stability in 1 M guanidinium hydrochloride. Activity remained above 80% across several reuse cycles, and storage at 4 °C preserved functionality for weeks. When applied to digesting the NISTmAb, immobilized trypsin provided peptide yields and sequence coverage comparable to soluble enzyme and outperformed it at elevated temperatures. MALDI-TOF MS analysis of Herceptin digests yielded fingerprint spectra that correctly identified the antibody and achieved >60% sequence coverage. The combination of low cost, robustness and analytical performance makes corundum-immobilized trypsin an attractive option for research and routine proteomic workflows. Full article

Background/Objectives: Chronic Obstructive Pulmonary Disease (COPD) exacerbations affect health and mortality, yet current risk assessments based on previous events have limitations and are less preventative. This study used metabolomics to assess if amino acid profiles are linked to higher COPD exacerbation risk, compared to an amino acid-based panel to standard risk stratification methods, and explored its clinical decision-making and prevention potential. Methods: This prospective cohort study measured plasma concentrations of 19 amino acids in 88 individuals with COPD using ultra-performance liquid chromatography. Participants were observed for 2.5 years to track occurrences of moderate and severe COPD exacerbations. Results: During follow-up, 44 participants (50%) had an exacerbation. Tyrosine and hsCRP were independently linked to exacerbations in multivariable analysis and formed the basis of the “COPDAE score.” This score independently predicted future exacerbations after adjusting for Global Initiative for Chronic Obstructive Lung Disease (GOLD) classifications. A COPDAE score above 1.73 correlated with lower event-free survival in several subgroups: GOLD group A (log-rank = 13.7, p < 0.001), groups A and B (log-rank = 5.0, p = 0.025), and groups A and C (log-rank = 15.2, p < 0.001). Conclusions: Tyrosine and hsCRP together form a biomarker panel to assess and stratify COPD exacerbation risk. This score can help identify stable patients at risk, even with mild symptoms or few prior events, enabling earlier, more personalized interventions. Full article

This study determined the effects of gestational obesity on the short- and long-term metabolic statuses of post-partum mothers and whether obesity management during pregnancy could attenuate these effects. At 120 days prior to estrus, eight ewes received 100% of the National Research Council (NRC) nutrient requirements (control group), and twenty-four ewes had free access to feed (obesity induction). Embryos from superovulated ewes with normal body condition were transferred to the uteri of control-fed or obese ewes on day 6 post-estrus to generate genetically similar singleton pregnancies. Thirty-five days after embryo transfer, eight obese ewes were subject to restricted feeding (65% of feed intake for the 100% NRC-fed control group) until parturition, and the remaining sixteen obese ewes (eight ewes/group) continued to have free access to feed throughout gestation. Following parturition, all but one group of obese ewes (that continued to have free access to feed) were fed 100% of NRC nutrient requirements. At post-partum days (PPD) 1 and 150, glucose tolerance tests were conducted with ewes. At both PPD1 and PPD150, obesity resulted in insulin resistance, impairment of whole-body glucose utilization, increased levels of circulating leptin, and altered profiles of amino acids in plasma, and these effects were attenuated in ewes receiving obesity management during or after gestation. At PPD150, obesity increased circulating levels of ammonia and urea in ewes, which were prevented by realimentation to 100% NRC requirements. These results indicate that weight reduction in obese ewes during pregnancy or after parturition can ameliorate the adverse metabolic effects of gestational obesity in ewes. Full article

Background/Objectives: Phenylketonuria (PKU) is an inherited metabolic disorder requiring early and lifelong dietary management through a low-phenylalanine (Phe) diet supplemented with Phe-free protein substitutes (PS). Recently developed slow-release PS formulations aim to mimic natural protein absorption, enhancing metabolic stability and tolerability. The PREMP study (effect of Protein RElease on the Microbiota composition and function in Phenylketonuric subjects) assessed the effects of a slow-release, Phe-free PS on gut microbiota composition and metabolic parameters in patients with PKU. Methods: Patients aged ≥6 years with PKU were enrolled from two Italian centers (Milan and Naples). Participants replaced ≥50% of their usual protein equivalent (P.Eq.) intake from Phe-free PS with a slow-release PS for 4 months. Clinical, biochemical, and nutritional assessments were performed at baseline and post-intervention. Gut microbiota composition was analyzed by 16S rRNA gene sequencing, and fecal fatty acids were quantified by gas chromatography–mass spectrometry. Results: Thirteen patients (median age 17 years) completed the intervention, replacing on average 78% of their usual P.Eq. intake with the slow-release formulation. Plasma phenylalanine and tyrosine levels remained stable, while fasting insulin (p = 0.0185) and HOMA-IR (p = 0.0099) significantly decreased, indicating improved insulin sensitivity. Anthropometric and dietary parameters showed no significant changes. Gut microbiota diversity remained stable, with modest increases in microbial richness and beneficial genera such as Bacteroides, Bifidobacterium, and Gemmiger, while Hafnia, Anaerostipes and Romboutsia decreased. Fecal butyrate and other fatty acids showed slight, non-significant increases. Conclusions: The slow-release PS was safe, well-tolerated, and improved insulin sensitivity without affecting amino acid or nutritional status. Microbial changes suggest potential benefits for gut health, warranting confirmation in larger, long-term studies. Full article

Hydrolysed collagen is used as a supplement for horses with osteoarthritis, hoof horn growth problems, and gastric ulcers. To determine the oral availability of a specific hydrolysed collagen supplement and the appropriate dose, six Warmblood mares were fed two different concentrations of the supplement: 100 g HC (C_H), 50 g HC (C_L), and a control of 0 g HC (C_N) during one week in a randomised cross-over design. On day 7, 14 and 21, blood sampling for amino acid (AA) analysis was performed, just prior to feeding the supplement (t = 0) and every hour after feeding for 8 h (t = 1–8). Statistical analysis revealed differences in mean plasma AA concentrations between the CH and CN doses for alanine, arginine, glutamine, glycine, proline, serine and hydroxyproline. Similarly, statistical differences were observed between the CL and CN doses for arginine, glycine, proline and hydroxyproline. This study demonstrated the availability of amino acids from the supplemented hydrolysed collagen. Although clinical efficacy was not evaluated in this study, a dose of 100 g HC once daily resulted in higher plasma concentrations, which remained detectable for at least 24 h, suggesting greater clinical relevance. Full article

Objectives: The impact of combining animal and plant protein sources on digestibility is unclear, despite their increasing clinical use. Using a non-invasive dual stable isotope tracer approach, we assessed the digestibility, bioavailability and utilization of distinct protein blends in older adults, and associated plasma amino acid profiles and muscle protein synthesis (MPS) rates. Methods: Thirty-two older men (69 ± 3 y) consumed one of four protein blends (A (51:49, casein/soy); B and C (35:25:20:20, whey/casein/soy/pea); D (80:20, casein/whey)) alongside primed constant infusions of [1,2-¹³C₂] leucine for 8 h. Arterialized blood and vastus lateralis muscle biopsies were collected during a trickle feed protocol with all blends providing 20 g total protein, universally labeled ¹³C-spirulina, and ²H-cell free amino acid mix to determine digestibility. This trial was registered at Clinicaltrials.gov (ID-NCT07038655). Results: No differences (¹³C:²H ratios) were found in digestibility between the protein blends (p > 0.05). Mean (±SEM) fed state MPS at 2.5 h was 0.078 ± 0.009%/h, 0.075 ± 0.012%/h, 0.085 ± 0.007%/h and 0.065 ± 0.011%/h for drinks A, B, C and D, respectively, with a main time effect observed (p < 0.01), but no significant differences between drinks. Plasma essential amino acids (EAAs) increased significantly from baseline for all blends by 40 min (p < 0.05), with no differences between blends at any time point. Conclusions: These findings suggest that protein quantity (and/or leucine content), rather than composition, appears to be the most important factor driving MPS. Future work should focus on clinical populations where protein requirements and digestibility characteristics may differ. Full article

Background: Type 2 diabetes (T2D), the most common form of diabetes, is associated with a significantly elevated risk of cardiovascular and cerebrovascular complications. However, circulating metabolic signatures that reliably predict the transition to insulin resistance, and are potentially linked to increased vascular risk, remain incompletely characterized. Rodent models, particularly those induced by a high-fat diet (HFD) combined with low-dose streptozotocin (STZ), are widely used to study the progression of T2D. However, the systemic metabolic shifts associated with this model, especially at the plasma level, are poorly defined. Methods: In this study, we performed untargeted liquid chromatography–mass spectrometry (LC-MS)-based metabolomic profiling on plasma samples from control, HFD-only (obese, insulin-sensitive), and HFD + STZ (obese, insulin-resistant) C57BL/6 mice. Results: In the HFD + STZ cohort, plasma profiles showed a global shift toward lipid classes; depletion of aromatic and branched-chain amino acids (BCAAs); accumulation of phenylalanine-derived co-metabolites, consistent with gut–liver axis dysregulation; elevations in glucose, fructose-6-phosphate, and nucleoside catabolites, indicating impaired glucose handling and heightened nucleotide turnover; increased free fatty acids, reflecting membrane remodeling and lipotoxic stress; and higher cAMP, thyroxine, hydrocortisone, and uric acid, consistent with endocrine and redox imbalance. By contrast, HFD-only mice exhibited elevations in aromatic amino acids and BCAAs relative to controls, a pattern compatible with early obesity-associated adaptation while insulin signaling remained partially preserved. KEGG analysis revealed disturbances in carbohydrate metabolism, amino acid degradation, nucleotide turnover, and hormone-related pathways, and HMDB mapping linked these changes to T2D, obesity, heart failure, and renal dysfunction. Conclusion: Collectively, these findings delineate insulin resistance-specific plasma signatures of metabolic inflexibility and inflammatory stress in the HFD + STZ model, distinguishing it from HFD alone and supporting its utility for mechanistic studies and biomarker discovery. Importantly, this plasma metabolomics study shows that insulin-sensitive and insulin-resistant states exhibit distinct variation in circulating metabolites and cardiovascular risk factors, underscoring the translational value of plasma profiling. Full article