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Watermelon produces many byproducts (watermelon rind and skin) even though those components contain various bioactive compounds, including citrulline. This study evaluated the citrulline concentration, total phenolic content, and antioxidant activity (DPPH and FRAP assays) of different parts of watermelon and investigated the bioavailability of citrulline from different parts of watermelon using an in vitro human intestinal epithelial Caco-2 cell monolayer model. Solid-phase extracted watermelon flesh, rind, and skin samples were treated on a Caco-2 cell monolayer for 1, 2, and 4 h. The collected basolateral solution at each time point was analyzed for the percentage of citrulline transport. Watermelon flesh had the highest citrulline content, but the watermelon skin had the highest total phenolic content and antioxidant activity compared to other watermelon parts. The citrulline bioavailability showed greater % transport in watermelon skin than in watermelon flesh, rind, and L-citrulline standard. It may be due to the different food matrices of watermelon parts. This suggests that the utilization of watermelon by-products such as skin would help develop value-added products with better bioavailability of citrulline. However, since this study was conducted with an in vitro cell model, more extensive research with in vivo studies will be needed. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the effect of citrulline on the pyroptosis of mouse macrophage RAW264.7 and the mechanism. We investigated the effect of citrulline on pyroptosis of RAW264.7 cell induced by lipopolysaccharide (LPS), and the modulation of nuclear factor‐kappaB (NF‐κB) signaling. Methods: Pyroptosis was evaluated using flow cytometry and caspase‐1/sytox double staining. Cell counting kit‐8 assay was performed to evaluate cell viability. Results: Citrulline promoted cell viability and inhibited the pyroptosis of RAW264.7 cell stimulated by LPS. Furthermore, citrulline inactivated NF‐κb/p65 signaling pathway by suppressing p65 nuclear translocation induced by LPS. An NF‐κb signaling pathway activator, betulinic acid, reversed the inhibition of pyroptosis induced by citrulline. Conclusion: Citrulline inhibited LPS‐induced pyrophosis, which may be closely related to the inactivation of NF‐κB/p65 signaling pathway. [ABSTRACT FROM AUTHOR]

Peptidyl arginine deiminases (PADs) are a family of post-translational modification enzymes that irreversibly citrullinate (deiminate) arginine residues of protein and convert them to a non-classical amino acid citrulline in the presence of calcium ions. It has five isotypes, such as PAD1, PAD2, PAD3, PAD4, and PAD6, found in mammalian species. It has been suggested that increased PAD expression in various tissues contributes to the development of multiple inflammatory diseases, including rheumatoid arthritis (RA), cancer, diabetes, and neurological disorders. Elevation of PAD enzyme expression depends on several factors like rising intracellular Ca2+ levels, oxidative stress, and proinflammatory cytokines. PAD inhibitors originating from natural or synthetic sources can be used as a novel therapeutic approach concerning inflammatory disorders. Here, we review the pathological role of PAD in several inflammatory disorders, factors that trigger PAD expression, epigenetic role and finally, decipher the therapeutic approach of PAD inhibitors in multiple inflammatory disorders. [ABSTRACT FROM AUTHOR]

In recent years, arginine deiminase (ADI, EC 3.5.3.6) has attracted much attention as a biocatalyst that produces the functional amino acid l‐citrulline from l‐arginine and also as an anticancer enzyme. Here, we identified and characterized a putative ADI from the thermophilic bacterium Halothermothrix orenii. The H. orenii ADI (H‐ADI) protein was expressed in Escherichia coli BL21(DE3) with a specific activity of 91.8 U/mg protein at 55°C and pH 6.5. The enzyme remained at 74% relative activity after incubation at 45°C for 180 min, only 25% at 50°C. The melting temperature was 56°C. H‐ADI is not a metal‐requiring enzyme; Ni2+ slightly improved the catalytic activity. The Km and Vmax for l‐arginine were 55.5 mM and 156.8 μmol/min/mg protein, respectively. Moreover, three residues (Arg183, Arg237, and His273) were key to the formation of l‐citrulline, as analyzed by alanine‐scanning mutagenesis. Finally, the enzymatic synthesis of l‐citrulline was carried out at 50°C with a conversion ratio reaching 99.03%. Together, these findings show that H‐ADI is a promising biocatalyst for the production of l‐citrulline. [ABSTRACT FROM AUTHOR]

Aims: Excess biuret, a common impurity in urea fertilizers, is toxic to plants. Little is known about the mechanisms of biuret toxicity in plants. This study aimed to investigate the accumulation of biuret and the changes in metabolites in rice (Oryza sativa) plants under biuret toxicity. Methods: A previous study had shown that transgenic rice plants overexpressing bacterial biuret hydrolase had improved biuret tolerance. Here, we grew wild-type and bacterial biuret hydrolase-overexpressing rice plants in hydroponics at different biuret levels. Concentrations of biuret and allantoin, a nitrogenous intermediate in the purine degradation pathway, in the plants were determined. The expression levels of genes related to purine degradation and ureide metabolisms were analyzed using wild-type plants. Additionally, we performed a metabolome analysis using rice suspension cells. Results: The biuret hydrolase-overexpressing plants did not contain biuret, whereas wild-type plants accumulated biuret in shoots in the order of mmol L−1 tissue water. The concentration of allantoin in shoots of wild-type plants under biuret toxicity was higher than those in control conditions. Inhibition of allantoinase activity by biuret was not detected, and allantoin accumulation appeared to be associated with changes in the expression of allantoinase, allantoate amidohydrolase and putative allantoin transporter genes. Furthermore, another nitrogenous compound citrulline, which is a non-protein amino acid, accumulated in rice suspension cells under biuret toxicity. Conclusion: The accumulation of these compounds suggests that rice plants subjected to biuret toxicity need to reduce the concentration of surplus ammonium ions via synthesizing nitrogen-rich compounds. [ABSTRACT FROM AUTHOR]

An altered amino acid metabolism has been described in frail older adults which may contribute to muscle loss and functional decline associated with frailty. In the present investigation, we compared circulating amino acid profiles of older adults with physical frailty and sarcopenia (PF&S, n = 94), frail/pre-frail older adults with type 2 diabetes mellitus (F-T2DM, n = 66), and robust non-diabetic controls (n = 40). Partial least squares discriminant analysis (PLS–DA) models were built to define the amino acid signatures associated with the different frailty phenotypes. PLS–DA allowed correct classification of participants with 78.2 ± 1.9% accuracy. Older adults with F-T2DM showed an amino acid profile characterized by higher levels of 3-methylhistidine, alanine, arginine, ethanolamine, and glutamic acid. PF&S and control participants were discriminated based on serum concentrations of aminoadipic acid, aspartate, citrulline, cystine, taurine, and tryptophan. These findings suggest that different types of frailty may be characterized by distinct metabolic perturbations. Amino acid profiling may therefore serve as a valuable tool for frailty biomarker discovery. [ABSTRACT FROM AUTHOR]

Postmenopausal women (PMW) may experience endothelial dysfunction associated with arginine (ARG) deficiency relative to asymmetric dimethylarginine (ADMA) caused by oxidative stress. Endothelial dysfunction contributes to increased blood pressure (BP) responsiveness to sympathoexcitation induced by the cold pressor test (CPT). We investigated the effects of citrulline alone (CIT) and combined with the antioxidant glutathione (CIT+GSH) on vascular function. Forty-four healthy PMW were randomized to CIT (6 g), CIT+GSH (2 g + 200 mg: Setria®) or placebo (PL) for 4 weeks. Brachial artery flow-mediated dilation (FMD), aortic stiffness (pulse wave velocity, PWV), brachial and aortic BP reactivity to CPT, and serum fasting blood glucose (FBG), ARG, and ARG/ADMA ratio were measured. Baseline FBG was higher in CIT+GSH vs. PL. FMD increased after CIT+GSH vs. PL (p < 0.05). CIT and CIT+GSH increased ARG/ADMA (p < 0.05), but did not affect aortic PWV. CIT+GSH attenuated the brachial and aortic systolic BP and mean arterial pressure (MAP) responses to CPT vs. PL and CIT (p < 0.05). The improvements in FMD were related to baseline FMD (r = −0.39, p < 0.05) and aortic MAP response to CPT (r = −0.33, p < 0.05). This study showed that CIT+GSH improved FMD and attenuated systolic BP and MAP reactivity in PMW. Although CIT increased ARG/ADMA, it did not improve FMD in healthy PMW. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is an important signaling molecule for many physiological and pathological processes. Diseases associated with abnormal NO synthesis include cardiovascular diseases, insulin-dependent diabetes, or chronic kidney disease (CKD). The aim of the paper was to evaluate NO synthesis metabolites, i.e., asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), dimethylamine (DMA), arginine, citrulline in plasma of patients with different severity of CKD and to seek possible links between these parameters and the development of this disease. Forty-eight CKD children and thirty-three age-matched controls were examined. Patients were divided into groups depending on the CKD stages (Group II-stage II, Group III-stage III, Group IV-stage IV, and Group RRT children on dialysis). To determine the concentrations of the above-mentioned metabolites in plasma liquid chromatography-mass spectrometry was used. There were significant differences observed in levels of ADMA, SDMA, DMA, and citrulline between control vis CKD groups (p values ranging from p = 0.01; RRT vis III-IV stages of CKD: p < 0.046). Citrulline levels in CKD children were statistically significantly higher in RRT group vis control (p < 0.001). Children with CKD develop disturbances in most metabolites of NO synthesis. Dialysis children treated show the greatest disturbances of plasma ADMA and citrulline levels. ADMA seems to be a good indicator of the gradual progression of the CKD, which is proved by the negative correlation with eGFR.

• New SLC25A13 frameshift variant linked to citrullinemia in a Hispanic neonate. • This case study expands the citrin deficiency (CD) variant spectrum. • Integrating Clinical, biochemical, and genetic data better informs CD management. Citrin deficiency (CD) is an autosomal recessive metabolic disorder affecting the urea cycle and energy production. Diagnosis involves measuring ammonia and amino acid levels (eg: citrulline), with confirmation through solute carrier family 25 member 13 (SLC25A13) gene mutation analysis. Herein, we present a case report of a variant in the SLC25A13 gene that has not been previously reported in the literature. The subject was a full-term Hispanic girl infant who was provisionally diagnosed with amino aciduria/urea cycle disorder with citrullinemia of unidentified type based on the second newborn screen performed at the 10th day of life. Sequence analysis and deletion/duplication testing using a panel consisting of 5 genes pertaining to citrullinemia revealed the patient carried a frameshift variant in the SLC25A13 gene (c.429_430del; pArg144fs) consistent with elevated citrulline results. The variant is not found in population databases (gnomAD). While ClinVar has only one entry for this variant (Variation ID: 1076508) and classifies it as pathogenic/likely pathogenic, no case report association exists between this variant and citrullinemia/CD or any SLC25A13 -related conditions. This case study expands the CD variant spectrum and describes a frameshift variant in the SLC25A13 gene in a patient linked to pathology. The finding emphasizes the importance of integrating clinical features with biochemical and genetic analysis to better understand genotype-phenotype correlations in CD and improve management strategies. [ABSTRACT FROM AUTHOR]

This study investigated the effects of arginine family amino acids supplementation on growth, whole-body amino acid profiles, antioxidant capacity, and gene expression of juvenile largemouth bass (9.43 ± 0.13 g). Five isonitrogenous and isolipidic diets were formulated, using 24% fish meal and 15% casein as primary protein sources, supplemented with 5.75% alanine, 2.84% arginine, 12.75% glutamic acid, 5.01% proline, and 0.74% citrulline (dry matter). Each diet was randomly allocated to three tanks (300 L) containing 15 fish, and the fish were fed to satiation twice daily. After 8 weeks of feeding, the glutamic acid group showed significantly lower weight gain (WG; P < 0.05) than the alanine group. The hepatosomatic index of the proline group was significantly increased than that of the alanine group (P < 0.05). Compared to the alanine group, adding arginine and citrulline significantly increased the whole-body arginine concentration of largemouth bass (P < 0.05). The retention rates of branched-chain amino acids (leucine, isoleucine, valine), glutamic acid, aspartic acid, and lysine in fish of the arginine and citrulline groups were significantly reduced (P < 0.05). The liver arginase activity and urea cycle-related enzyme mRNA expression levels in the citrulline group were significantly higher than those in the alanine group (P < 0.05). The citrulline group increased the activity of total nitric oxide synthase, total antioxidant capacity, and superoxide dismutase activities than the alanine group. The concentrations of glutathione in both the arginine group and citrulline group were markedly elevated compared to those in the other groups (P < 0.05). Malondialdehyde content was significantly higher in the proline group than in the other groups (P < 0.05). Although citrulline was not helpful in improving growth performance in this study, it played an important role in improving antioxidant capacity and endogenous synthesis of arginine. These findings indicated that citrulline is an effective arginine alternative for maintaining fish health. • The addition of citrulline can promote arginine synthesis in largemouth bass. • The citrulline group can raise the mRNA level of urea cycle-related enzymes. • The citrulline supplementation can increase liver T-NOS activity. • The citrulline addition can improve the antioxidant capacity of largemouth bass. [ABSTRACT FROM AUTHOR]

There are few reliable biomarkers for gastrointestinal toxicity, and the further identification of such markers can improve the accuracy and speed of toxicological evaluations. This study aimed to evaluate the effectiveness of several recently proposed biomarkers—plasma citrulline, fecal calprotectin, fecal bile acid, and plasma miRNAs (miR-194 and -215)—in detecting intestinal toxicity. To this end, cysteamine hydrocholoride (cysteamine, 600 or 900 mg/kg, PO), indomethacin (10 mg/kg, PO), or 2,4-Dinitrobenzenesulfonic acid hydrate (DNBS, 20 mg/kg, IR) were administered to male Wistar rats to establish models of gastric/duodenal, jejunum/ileum, or colonic damage, respectively. Both novel biomarkers and traditional toxicological parameters were evaluated in these rat models. Standard in-life observations, such as fecal properties or body weight, were inadequate for monitoring intestinal toxicity, as there were few observable changes indicative of intestinal injury, especially in the cysteamine and indomethacin models. Plasma citrulline drastically decreased in cysteamine or indomethacin-treated rats, with a milder decrease in DNBS-treated animals. Fecal total bile acids and calprotectin levels increased only in rats treated with indomethacin or DNBS, but not with cysteamine. While plasma miR-194 remained unchanged across all models, miR-215 levels decreased after cysteamine treatment. Together, these results suggest that plasma citrulline and fecal calprotectin may be effective biomarkers for monitoring intestinal injury. Fecal TBA and plasma miR-215 also show potential as useful biomarkers, but further research is needed to confirm their efficacy. Specifically, plasma citrulline is indicative of damage from the stomach to the ileum, fecal total bile acids and calprotectin are indicative of damage from the jejunum to the rectum, and plasma miR-215 is indicative of damage from the stomach and the duodenum. Integrating these novel biomarkers with standard toxicological parameters will help in predicting actual intestinal sites of damage. This integration has the potential to improve the quality of toxicological evaluations. Our findings support the use of these biomarkers in clinical settings. • The study evaluates citrulline, calprotectin, bile acid, and miRNAs for detecting intestinal toxicity. • Plasma citrulline decreased drastically in cysteamine or indomethacin-treated rats. • Fecal total bile acids and calprotectin levels increased in indomethacin or DNBS-treated rats. • Plasma miR-215 levels decreased in cysteamine-treated rats. • These new biomarkers may enhance the monitoring and the predictability of damage sites within the intestine. [ABSTRACT FROM AUTHOR]

Cyanobacteria are among the oldest organisms colonizing Earth. Their great biodiversity and ability to biosynthesize secondary metabolites through a variety of routes makes them attractive resources for biotechnological applications and drug discovery. In this pioneer study, four filamentous cyanobacteria (Cephalothrix lacustris LEGE 15493, Leptolyngbya boryana LEGE 15486, Nodosilinea nodulosa LEGE 06104 and Leptothoe sp. LEGE 11479) were explored for their anti-inflammatory potential in cell and cell-free in vitro bioassays, involving different inflammatory mediators and enzymes. Extracts of different polarities were sequentially prepared and chemically characterized for their content of phycobiliproteins (PBPs) and carotenoids. HPLC-PDA analysis of the acetone extracts revealed β-carotene to be the dominant carotenoid (18.4–44.3 mg/g) and zeaxanthin as the dominant xanthophyll (52.7–192.9 mg/g), with Leptothoe sp. LEGE 11479 and Nodosilinea nodulosa LEGE 06104, respectively, being the richest strains. The PBP profile was in accordance with the color presented by the aqueous extracts, with Leptolyngbya boryana LEGE 15486 being the richest in phycocyanin (204.5 μg/mg) and Leptothoe sp. LEGE 11479 the richest in phycoerythrin (78.5 μg/mg). Aqueous extracts were more effective in superoxide anion radical scavenging, while acetone ones were more effective in scavenging nitric oxide radical (●NO) and in inhibiting lipoxygenase. Acetone extracts also reduced ●NO production in lipopolysaccharide-stimulated RAW 264.7 macrophages, with the mechanistic study suggesting a downregulation of the inducible nitric oxide synthase expression. Nodosilinea nodulosa LEGE 06104 and Leptothoe sp. LEGE 11479 acetone extracts presented the lowest IC50 values for the mentioned assays, pointing them out as promising resources for the development of new multi-target anti-inflammatory therapies.

Background: This study aimed to evaluate whether mucous fistula refeeding (MFR) is safe and beneficial for the growth and intestinal adaptation of preterm infants with enterostomies. Methods: This exploratory randomized controlled trial enrolled infants born before 35 weeks' gestation with enterostomy. If the stomal output was ≥ 40 mL/kg/day, infants were assigned to the high-output MFR group and received MFR. If the stoma output was < 40 mL/kg/day, infants were randomized to the normal-output MFR group or the control group. Growth, serum citrulline levels, and bowel diameter in loopograms were compared. The safety of MFR was evaluated. Results: Twenty infants were included. The growth rate increased considerably, and the colon diameter was significantly larger after MFR. However, the citrulline levels did not significantly differ between the normal-output MFR and the control group. One case of bowel perforation occurred during the manual reduction for stoma prolapse. Although the association with MFR was unclear, two cases of culture-proven sepsis during MFR were noted. Conclusions: MFR benefits the growth and intestinal adaptation of preterm infants with enterostomy and can be safely implemented with a standardized protocol. However, infectious complications need to be investigated further. Trial registration: clinicaltrials.gov NCT02812095, retrospectively registered on June 6, 2016. [ABSTRACT FROM AUTHOR]

Introduction: Extracellular vesicles (EVs) have been recognized as key players in numerous physiological functions. These vesicles alter their compositions attuned to the health and disease states of the organism. In men, significant changes in the proteomic composition(s) of seminal plasma EVs (sEVs) have already been found to be related to infertility. Methods: Methods: In this study, we analyze the posttranslational configuration of sEV proteomes from normozoospermic (NZ) men and nonnormozoospermic (non-NZ) men diagnosed with teratozoospermia and/or asthenozoospermia by unbiased, discovery-driven proteomics and advanced bioinformatics, specifically focusing on citrulline (Cit) and homocitrulline (hCit) posttranscriptional residues, both considered product of ureido protein modifications. Results and discussion: Significant increase in the proteome-wide cumulative presence of hCit together with downregulation of Cit in specific proteins related to decisive molecular functions have been encountered in sEVs of non-NZ subjects. These findings identify novel culprits with a higher chance of affecting fundamental aspects of sperm functional quality and define potential specific diagnostic and prognostic non-invasive markers for male infertility. [ABSTRACT FROM AUTHOR]

We hypothesized that patients with chronic kidney disease (CKD) display an altered plasma amino acid (AA) metabolomic profile that could contribute to abnormal vascular maintenance of peripheral circulation in uremia. The relationships between plasma AAs and endothelial and vascular smooth muscle function in the microcirculation of CKD patients are not well understood. The objective of this study is to investigate to what extent the levels of AAs and its metabolites are changed in CKD patients and to test their relationship with endothelial and vascular smooth muscle function. Patients with CKD stages 3 and 5 and non-CKD controls are included in this study. We report that there was a significant reduction of the biopterin (BH4/BH2) ratio, which was accompanied by increased plasma levels of BH2, asymmetric dimethylarginine (ADMA) and citrulline in patients with CKD-5 vs. CKD-3 vs. controls. In vivo augmentation index measurement showed a positive association with ADMA in all participants. The contribution of nitric oxide, assessed by ex vivo assay, showed a negative association with creatinine, ADMA and citrulline in all participants. In CKD-5, BH4 negatively correlated with ADMA and ornithine levels, and the ex vivo endothelium-mediated dilatation positively correlated with phenylalanine levels. In conclusion, uremia is associated with alterations in AA metabolism that may affect endothelium-dependent dilatation and vascular stiffness in microcirculation. Interventional strategies aiming to normalize the AA metabolism could be of interest as treatment options. [ABSTRACT FROM AUTHOR]

Objective: Stress may have an important role in the origin and progress of depression and can impair metabolic homeostasis. The one-carbon cycle (1-CC) metabolism and amino acid (AA) profile are some of the consequences related to stress. In this study, we investigated the Paroxetine treatment effect on the plasma metabolite alterations induced by forced swim stress-induced depression in mice. Materials and Methods: In this experimental study that was carried out in 2021, thirty male NMRI mice (6-8 weeks age, 30 ± 5 g) were divided into five groups: control, sham, paroxetine treatment only (7 mg/kg BW/day), depression induction, and Paroxetine+depression. Mice were subjected to a forced swim test (FST) to induce depression and then were treated with Paroxetine, for 35 consecutive days. The swimming and immobility times were recorded during the interventions. Then, animals were sacrificed, plasma was prepared and the concentration of 1-CC factors and twenty AAs was measured by spectrophotometry and high-performance liquid chromatography system (HPLC) techniques. Data were analyzed by SPSS, using One-Way ANOVA and Pearson Correlation, and P<0.05 was considered significant. Results: Plasma concentrations of phenylalanine, glutamate, aspartate, arginine, ornithine, citrulline, threonine, histidine, and alanine were significantly reduced in the depression group in comparison with the control group. The Homocysteine (Hcy) plasma level was increased in the Paroxetine group which can be associated with hyperhomocysteinemia. Moreover, vitamin B12, phenylalanine, glutamate, ornithine, citrulline, and glycine plasma levels were significantly reduced in the depression group after Paroxetine treatment. Conclusion: This study has demonstrated an impairment in the plasma metabolites’ homeostasis in depression and normal conditions after Paroxetine treatment, although, further studies are required. [ABSTRACT FROM AUTHOR]

The aim of this issue is to highlight novel findings or hypotheses in amino acid metabolism and regulation, especially in terms of health and disease, beyond its fundamental roles as protein constituents and nutrition (e.g., the major nitrogen sources). Therefore, slightly low protein diets with less than 4% reduced crude protein plus first four limiting amino acids (lysine (Lys), Met, threonine, and Trp) are used to improve nitrogen secretion, diarrhea, and gut health with no negative impacts of their growth performance. Four Seminal Reviews Kumar et al. 2021 overviewed the roles of hydrogen sulfide (H SB 2 sb S, a gasotransmitter with potent/diverse physiological functions that enzymatically derives from sulfur-containing amino acids), substance P (an eleven-amino-acid neuropeptide involved in vasodilation, inflammation, and pain), and adhesion molecules, including ICAM-1, VCAM-1, and selectins, in acute pancreatitis, one of the main reasons for hospitalization amongst gastrointestinal disorders [[15]]. The Special Issue "Amino Acid Metabolism and Regulation in Health and Disease 2.0", edited by us, is the successor of the previous "Amino Acid Metabolism and Regulation in Health and Disease", edited by Dr. Hieronim Jakubowski (New Jersey Medical School) and us. [Extracted from the article]

Ornithine and citrulline are amino acids used in dietary supplements and nutritional products consumed by healthy consumers, but the safe supplementation levels of these compounds are unknown. The objective of this study was to conduct two 4-week clinical trials to evaluate the safety and tolerability of graded dosages of oral ornithine (as hydrochloride) and citrulline. Healthy male adults (n = 60, age 41.4 ± 1.5 years) completed graded dosages of either ornithine hydrochloride (3.2, 6, 9.2, and 12 g/day) or citrulline (6, 12, 18, and 24 g/day) supplement for 4 weeks with 2-week wash-out periods in between. Primary outcomes included vitals, a broad spectrum of circulating biochemical analytes, body weight, sleep quality, and mental self-assessment. In the ornithine hydrochloride supplementation group, minor increase in plasma aspartic acid and glutamic acid concentrations was observed at the highest intake dosages. In the citrulline supplementation group, minor changes in laboratory data for serum lactate dehydrogenase and plasma amino acid concentration of lysine, methionine, threonine, aspartic acid, glutamic acid, glutamine and ornithine, arginine, and citrulline itself were measured. No other changes in measured parameters were observed, and study subjects tolerated 4-week-long oral supplementation of ornithine hydrochloride or citrulline without treatment-related adverse events. A clinical, no-observed-adverse-effect-level (NOAEL) of ornithine hydrochloride and citrulline supplementation in healthy adult males was determined to be 12 g/day and 24 g/day (4 weeks), respectively. [ABSTRACT FROM AUTHOR]

The sustained immunosuppression associated with severe sepsis favors an increased susceptibility to secondary infections and remains incompletely understood. Plasmablast and plasma cell subsets, whose primary function is to secrete antibodies, have emerged as important suppressive populations that expand during sepsis. In particular, sepsis supports CD39hi plasmablast metabolic reprogramming associated with adenosine‐mediated suppressive activity. Arginine deficiency has been linked to an increased risk of secondary infections in sepsis. Overcoming arginine shortage by citrulline administration efficiently improves sepsis‐induced immunosuppression and secondary infections in the cecal ligation and puncture murine model. Here, we aimed to determine the impact of citrulline administration on B cell suppressive responses in sepsis. We demonstrate that restoring arginine bioavailability through citrulline administration markedly reduces the dominant extrafollicular B cell response, decreasing the immunosuppressive LAG3+ and CD39+ plasma cell populations, and restoring splenic follicles. At the molecular level, the IRF4/MYC‐mediated B cell reprogramming required for extrafollicular plasma cell differentiation is shunted in the splenic B cells of mice fed with citrulline. Our study reveals a prominent impact of nutrition on B cell responses and plasma cell differentiation and further supports the development of citrulline‐based clinical studies to prevent sepsis‐associated immune dysfunction. [ABSTRACT FROM AUTHOR]

Fulvic acid (FA) can significantly alleviate cadmium (Cd) stress, but the specific metabolic response of FA to Cd toxicity is still not clarified. In the present study, we used untargeted metabolomic [gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS)] analysis to profile cucumber metabolism in response to Cd stress after spray application of FA. Our results showed that 331 differentially enriched metabolites (DEMs) were identified in leaf materials. These DEMs were enriched in 21 shared pathways in comparative groups of "Cd treatment vs. the control treatment" and "FA + Cd treatment vs. the Cd treatment." Specifically, treatment with FA significantly enhanced the organic acid content (citric acid, isocitric acid, 2-oxoglutaric acid, fumaric acid, and malic acid), which would contribute to provide sufficient substrates for the tricarboxylic acid (TCA) cycle and amino acid biosynthesis, thereby ensuring the normal production of energy and amino acid. At the same time, FA significantly increased the amino acid content (aspartate, citrulline, histidine, leucine, and phenylalanine). The accumulation of organic acid and amino acid can act as chelating agents for heavy metal ions and as scavengers of reactive oxygen species (ROS), thereby reducing intracellular oxidative damage. Furthermore, the application of FA improves antioxidant enzymes and accelerates ROS clearance. The improved contents of organic acid and amino acid, and the increased activity of antioxidant enzymes both played a central role in the reduction of malondialdehyde (MDA, 14.08%), hydrogen peroxide (H2O2, 61.70%) contents, and superoxide anion radical (O2−, 30.41%) production rate in plants under Cd stress. Taken together, the present study demonstrates the effects of FA on the antioxidant capacity and carbohydrate and amino acid metabolism of cucumber seedlings exposed to Cd stress, which provides comprehensive insights into the regulation of plants' response to Cd toxicity with FA was applied in cucumber. [ABSTRACT FROM AUTHOR]

Background: Gastrointestinal (GI) dysfunction is common in the intensive care unit (ICU), although there is no consensus on biomarkers of GI dysfunction. We aimed to evaluate ultrasound‐based gastric antrum measurements and serum intestinal fatty acid–binding protein (IFABP) and citrulline levels in relation to GI dysfunction in critically ill patients. Methods: Adult critically ill patients receiving enteral nutrition and stayed for in the ICU for ≥48 h was included. GI dysfunction was described using Gastrointestinal Dysfunction Score (GIDS). Gastric antrum measurements, including craniocaudal (CC) diameter, anteroposterior diameter, and antral–cross sectional area (CSA), as well as serum levels for IFABP and citrulline, were prospectively recorded at baseline and on day 3 and day 5 of enteral nutrition. The receiver operating characteristic (ROC) analysis was performed to evaluate gastric ultrasound parameters, serum IFABP, and citrulline concentrations in predicting GI dysfunction. Results: Thirty‐nine participants with a median age of 60 years were recruited and 46.2% of participants had GI dysfunction. ROC analysis revealed that the cutoff value of CSA score to predict GI dysfunction was 4.48 cm2, which provided 72.7% sensitivity and 77.2% specificity (area under the curve = 0.768, 95% CI: 0.555–0.980). At baseline, gastric residual volume was highly correlated with CC diameter and CSA (r = 0.764, P < 0.001 and r = 0.675, P < 0.001, respectively). Serum IFABP and citrulline levels had no correlation with GI dysfunction or gastric ultrasound parameters (P > 0.05). Conclusion: CSA was associated with GI dysfunction in critically ill patients. Serum IFABP and citrulline concentrations were poor in predicting GI dysfunction. [ABSTRACT FROM AUTHOR]

Objective: Serum levels of amino acids related to urea cycle are associated with risk of type 2 diabetes mellitus (T2DM). Our study aimed to explore whether serum levels of amino acids related to urea cycle, i.e., arginine, citrulline, and ornithine, are also associated with increased risk of chronic kidney disease (CKD) in T2DM. Methods: We extracted medical records of 1032 consecutive patients with T2DM from the Electronic Administrative System of Liaoning Medical University First Affiliated Hospital (LMUFAH) system from May 2015 to August 2016. Of them, 855 patients with completed data available were used in the analysis. CKD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². Serum amino acids were measured by mass spectrometry (MS) technology. Binary logistic regression was performed to obtain odds ratios (ORs) and their 95% confidence intervals (CIs). Results: 52.3% of the 855 T2DM patients were male, and 143 had CKD. In univariable analysis, high serum citrulline, high ratio of arginine to ornithine, and low ratio of ornithine to citrulline were associated with markedly increased risk of CKD (OR of top vs. bottom tertile: 2.87, 95%CI, 1.79-4.62 & 1.98, 95%CI,1.25-3.14 & 2.56, 95%CI, 1.61-4.07, respectively). In multivariable analysis, the ORs of citrulline and ornithine/citrulline ratio for CKD remained significant (OR of top vs. bottom tertile: 2.22, 95%CI, 1.29-3.82 & 2.24, 1.29-3.87, respectively). Conclusions: In Chinese patients with T2DM, high citrulline and low ornithine/ citrulline ratio were associated with increased risk of CKD. [ABSTRACT FROM AUTHOR]

Domestic cats and dogs are carnivores that have evolved differentially in the nutrition and metabolism of amino acids. This article highlights both proteinogenic and nonproteinogenic amino acids. Dogs inadequately synthesize citrulline (the precursor of arginine) from glutamine, glutamate, and proline in the small intestine. Although most breeds of dogs have potential for adequately converting cysteine into taurine in the liver, a small proportion (1.3%–2.5%) of the Newfoundland dogs fed commercially available balanced diets exhibit a deficiency of taurine possibly due to gene mutations. Certain breeds of dogs (e.g., golden retrievers) are more prone to taurine deficiency possibly due to lower hepatic activities of cysteine dioxygenase and cysteine sulfinate decarboxylase. De novo synthesis of arginine and taurine is very limited in cats. Thus, concentrations of both taurine and arginine in feline milk are the greatest among domestic mammals. Compared with dogs, cats have greater endogenous nitrogen losses and higher dietary requirements for many amino acids (e.g., arginine, taurine, cysteine, and tyrosine), and are less sensitive to amino acid imbalances and antagonisms. Throughout adulthood, cats and dogs may lose 34% and 21% of their lean body mass, respectively. Adequate intakes of high-quality protein (i.e., 32% and 40% animal protein in diets of aging dogs and cats, respectively; dry matter basis) are recommended to alleviate aging-associated reductions in the mass and function of skeletal muscles and bones. Pet-food grade animal-sourced foodstuffs are excellent sources of both proteinogenic amino acids and taurine for cats and dogs, and can help to optimize their growth, development, and health. [ABSTRACT FROM AUTHOR]

Climate change has escalated the effect of drought on crop production as it has negatively altered the environmental condition. Wild watermelon grows abundantly in the Kgalagadi desert even though the environment is characterized by minimal rainfall, high temperatures and intense sunshine during growing season. This area is also characterized by sandy soils with low water holding capacity, thus bringing about drought stress. Drought stress affects crop productivity through its effects on development and physiological functions as dictated by molecular responses. Not only one or two physiological process or genes are responsible for drought tolerance, but a combination of various factors do work together to aid crop tolerance mechanism. Various studies have shown that wild watermelon possess superior qualities that aid its survival in unfavorable conditions. These mechanisms include resilient root growth, timely stomatal closure, chlorophyll fluorescence quenching under water deficit as key physiological responses. At biochemical and molecular level, the crop responds through citrulline accumulation and expression of genes associated with drought tolerance in this species and other plants. Previous salinity stress studies involving other plants have identified citrulline accumulation and expression of some of these genes (chloroplast APX, Type-2 metallothionein), to be associated with tolerance. Emerging evidence indicates that the upstream of functional genes are the transcription factor that regulates drought and salinity stress responses as well as adaptation. In this review we discuss the drought tolerance mechanisms in watermelons and some of its common indicators to salinity at physiological, biochemical and molecular level. [ABSTRACT FROM AUTHOR]

Globally, dental caries is one of the most common non-communicable diseases for patients of all ages; Streptococcus mutans (S. mutans) is its principal pathogen. Lactobacillus paracasei (L. paracasei) shows excellent anti-pathogens and immune-regulation functions in the host. The aim of this study is to evaluate the effects of L. paracasei ET-22 on the formation of S. mutans biofilms. The living bacteria, heat-killed bacteria, and secretions of L. paracasei ET-22 were prepared using the same number of bacteria. In vitro, they were added into artificial-saliva medium, and used to coculture with the S. mutans. Results showed that the living bacteria and secretions of L. paracasei ET-22 inhibited biofilm-growth, the synthesis of water-soluble polysaccharide and water-insoluble polysaccharide, and virulence-gene-expression levels related to the formation of S. mutans biofilms. Surprisingly, the heat-killed L. paracasei ET-22, which is a postbiotic, also showed a similar regulation function. Non-targeted metabonomics technology was used to identify multiple potential active-substances in the postbiotics of L. paracasei ET-22 that inhibit the formation of S. mutans biofilms, including phenyllactic acid, zidovudine monophosphate, and citrulline. In conclusion, live bacteria and its postbiotics of L. paracasei ET-22 all have inhibitory effects on the formation of S. mutans biofilm. The postbiotics of L. paracasei ET-22 may be a promising biological anticariogenic-agent. [ABSTRACT FROM AUTHOR]

Arginine:glycine amidinotransferase (AGAT) catalyzes mainly two reactions that generate 1) L-homoarginine (hArg) from L-arginine and L-lysine (Kharg) and 2) guanidinoacetate (GAA) and L-ornithine from L-arginine and glycine (Kgaa). Previously, we found that pharmacological treatment of Becker muscular dystrophy (BMD) patients with metformin or L-citrulline resulted in antidromic effects on serum hArg and GAA concentrations, seemingly acting as an inhibitor and effector of AGAT activity, respectively. Here, we used data of this study as a model to determine Kharg and Kgaa values by using the concentrations of the participating amino acids measured in serum samples of the BMD patients. The study aimed to prove the general utility of this approach to investigate effects of amino acids and drugs on AGAT-catalyzed reactions in vivo in humans. [ABSTRACT FROM AUTHOR]

BACKGROUND: Time-restricted feeding (TRF) is an effective means that can efficiently regulate the metabolism and health of animals and humans. However, the effect of TRF on hypothalamic function remains unclear. RESULTS: Results showed that TRF significantly increased the activities of digestive enzymes lipase, maltase in the duodenum and lipase, trypsin in the pancreas whereas significantly decreased serum gastrointestinal hormones gastrin, glucagon-like peptide-1, cholecystokinin, peptide YY, and ghrelin. Metabolites related to amino acid metabolism, including citrulline, kynurenine, N-acetylleucine, L-tryptophan, and L-tyrosine, significantly increased in the TRF group. Differential metabolites were mainly enriched in phenylalanine, tyrosine, and tryptophan biosynthesis and tryptophan metabolism. Transcriptomic analysis of hypothalamus showed that a total of 462 differentially expressed genes (DEGs) were significantly changed by TRF. In particular, DEGs such as DDC, TH, GOT2, and DBH involved in aromatic amino acid metabolism pathways were significantly downregulated, whereas the expression of CYP1B1 was significantly upregulated. Moreover, DEGs (PDYN and PPP3CA) involved in amphetamine addiction and cocaine addiction were also downregulated in the TRF group. CONCLUSION: Taken together, these results suggested that TRF improved the digestion and absorption of nutrients and thus increased the accessibilities of aromatic amino acids. The increasing of circulating aromatic amino acids might mediate the regulatory neuroendocrine effects of TRF regimes on the hypothalamus functions, especially on drug addictions. This study reveals a possible mechanism underlying the effects of regulating feeding patterns on the function of the hypothalamus by altering aromatic amino acids metabolism. [ABSTRACT FROM AUTHOR]

Background: This study examined the efficacy of L-citrulline supplementation on the arginine/nitric oxide metabolism, and intestinal functions of broilers during arginine deficiency. A total of 288 day-old Arbor Acre broilers were randomly assigned to either an arginine deficient basal diet (NC diet), NC diet + 0.50% L-arginine (PC diet), or NC diet + 0.50% L-citrulline (NCL diet). Production performance was recorded, and at 21 days old, chickens were euthanized for tissue collection. Results: The dietary treatments did not affect the growth performance of broilers (P > 0.05), although NC diet increased the plasma alanine aminotransferase, urate, and several amino acids, except arginine (P < 0.05). In contrast, NCL diet elevated the arginine and ornithine concentration higher than NC diet, and it increased the plasma citrulline greater than the PC diet (P < 0.05). The nitric oxide concentration in the kidney and liver tissues, along with the plasma and liver eNOS activities were promoted by NCL diet higher than PC diet (P < 0.05). In the liver, the activities of arginase 1, ASS, and ASL, as well as, the gene expression of iNOS and OTC were induced by PC diet greater than NC diet (P < 0.05). In the kidney, the arginase 1, ASS and ASL enzymes were also increased by PC diet significantly higher than the NC and NCL diets. Comparatively, the kidney had higher abundance of nNOS, ASS, ARG2, and OTC genes than the liver tissue (P < 0.05). In addition, NCL diet upregulated (P < 0.05) the mRNA expression of intestinal nutrient transporters (EAAT3 and PEPT1), tight junction proteins (Claudin 1 and Occludin), and intestinal mucosal defense (MUC2 and pIgR). The intestinal morphology revealed that both PC and NCL diets improved (P < 0.05) the ileal VH/CD ratio and the jejunal VH and VH/CD ratio compared to the NC fed broilers. Conclusion: This study revealed that NCL diet supported arginine metabolism, nitric oxide synthesis, and promoted the intestinal function of broilers. Thus, L-citrulline may serve as a partial arginine replacement in broiler's diet without detrimental impacts on the performance, arginine metabolism and gut health of chickens. [ABSTRACT FROM AUTHOR]

Two emerging biomarkers of environmental enteric dysfunction (EED) include plasma citrulline (CIT), and the kynurenine (KYN): tryptophan (TRP)/ (KT) ratio. We sought to investigate the plasma concentration of CIT and KT ratio among the children having dehydrating diarrhea and examine associations between concentrations of CIT and KT ratio with concurrent factors. For this analysis, we used cross-sectional data from a total of 102, 6–36 months old male children who suffered from non-cholera acute watery diarrhea and had some dehydration admitted to an urban diarrheal hospital, in Bangladesh. CIT, TRP, and KYN concentrations were determined at enrollment from plasma samples using ELIZA. At enrollment, the mean plasma CIT concentration was 864.48 ± 388.55 µmol/L. The mean plasma kynurenine, tryptophan concentrations, and the KT ratio (× 1000) were 6.93 ± 3.08 µmol/L, 33.44 ± 16.39 µmol/L, and 12.12 ± 18.10, respectively. With increasing child age, KYN concentration decreased (coefficient: − 0.26; 95%CI: − 0.49, − 0.04; p = 0.021); with increasing lymphocyte count, CIT concentration decreased (coef.: − 0.01; 95% CI: − 0.02,0.001, p = 0.004); the wasted child had decreased KT ratio (coef.: − 0.6; 95% CI: − 1.18, − 0.02; p = 0.042) after adjusting for potential covariates. The CIT concentration was associated with blood neutrophils (coef.: 0.02; 95% CI: 0.01, 0.03; p < 0.001), lymphocytes (coef.: − 0.02; 95% CI: − 0.03, − 0.02; p < 0.001) and monocyte (coef.: 0.06; 95% CI: 0.01, 0.11; p = 0.021); KYN concentration was negatively associated with basophil (coef.: − 0.62; 95% CI: − 1.23, − 0.01; p = 0.048) after adjusting for age. In addition, total stool output (gm) increased (coef.: 793.84; 95% CI: 187.16, 1400.52; p = 0.011) and also increased duration of hospital stay (hour) (coef.: 22.89; 95% CI: 10.24, 35.54; p = 0.001) with increasing CIT concentration. The morphological changes associated with EED may increase the risk of enteric infection and diarrheal disease among children. Further research is critically needed to better understand the complex mechanisms by which EED biomarkers may impact susceptibility to dehydrating diarrhea in children. [ABSTRACT FROM AUTHOR]

Sperm cryopreservation maintains the diversities of porcine genetic resources and improves utilization efficiency of boar semen in artificial insemination practices. Freezability of boar semen presents remarkable differences among individuals. However, metabolic markers for boar semen freezability in both sperm and seminal plasma largely remain unknown. The present study thus aims to determine differences in metabolites of sperm and seminal plasma between poor (PF) and good (GF) freezability semen from a Chinese native pig and screen potential markers for semen freezability. A total of 72,048 metabolites in sperm and 66,551 metabolites in seminal plasma were identified by liquid chromatography-mass spectrometry, respectively. The proportion of lipid molecules among all metabolites in both sperm and seminal plasma was the maximum regardless of negative or positive mode. Furthermore, we identified 21 differentially expressed metabolites (DEMs) in sperm and 185 DEMs in seminal plasma between PF and GF group. Additionally, clustering analysis showed that DEMs in sperm and seminal plasma exhibited significant changes between PF and GF group. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DEMs in sperm were mainly enriched in metabolic pathways of amino acids and caffeine. DEMs in seminal plasma were associated with AMPK and cAMP signaling pathways. Taken together, these results demonstrate that sperm and seminal plasma of native pigs present differential metabolome between PF and GF semen. • Metabolome of boar sperm and seminal plasma significantly differs between poor and good freezability sperm. • Sperm-borne l -citrulline and seminal plasma-derived tryptophan could be potential sperm freezability markers. • Differential metabolites are mainly enriched in pathways associated with sperm quality. [ABSTRACT FROM AUTHOR]

Bio-based alternatives for petroleum-based thermosets are crucial for implementing sustainable practices in fiber-reinforced polymer composites. Therefore, the mechanical properties of diglycidyl ether of bisphenol a (DGEBA) cured with either l-arginine, l-citrulline, γ -aminobutyric acid, l-glutamine, l-tryptophan, or l-tyrosine were investigated to determine the potential of amino acids as bio-based curing agents for epoxy resins. Depending on the curing agent, the glass transition temperature, Young's modulus, tensile strength, and critical stress intensity factor range from 98.1   ∘ C to 188.3   ∘ C , 2.6   G Pa to 3.5   G Pa , 39.4   M Pa to 46.4   M Pa , and 0.48   M Pa m 0.5 to 1.34   M Pa m 0.5 , respectively. This shows that amino acids as curing agents for epoxy resins result in thermosets with a wide range of thermo-mechanical properties and that the choice of curing agent has significant influence on the thermoset's properties. After collecting the results of dynamic mechanical analysis (DMA), tensile, flexural, compression, and compact tension tests, the functionality f, cross-link density ν C , glass transition temperature T g , Young's modulus E T , compression yield strength σ Cy , critical stress intensity factor in mode I K IC , fracture energy G IC , and diameter of the plastic zone d p are correlated with one another to analyze their inter-dependencies. Here, the cross-link density correlates strongly positively with T g , E T , and σ Cy , and strongly negatively with K IC , G IC , and d p . This shows that the cross-link density of DGEBA cured with amino acids has a crucial influence on their thermo-mechanical properties and that the thermosets considered may either be stiff and strong or tough, but hardly both at the same time. [ABSTRACT FROM AUTHOR]

The experiment was to study the effect of whole strain of hybrid Broussonetia papyrifera fermented feed on the content and composition of amino acids in muscle of pigs. A total of 48 fattening pigs with similar weight were randomly selected and divided into two groups, with three replicates in each group and eight pigs in each replicate. The pigs in control group were fed with basic diet, and the pigs in test group were fed with 3% whole plant hybrid Broussonetia papyrifera fermentation feed instead of soybean meal. The test period was 60 d. The results showed that compared with control group, the average daily feed intake and average daily gain of the fattening pigs in test group decreased by 9.00% and 0.28%, respectively (P>0.05). Compared with control group, the content of leucine, lysine, tryptophan, phenylalanine, valine, glutamate, serine, glycine, citrulline, proline, arginine and methionine in the muscle of fattened pigs in test group were significantly increased (P<0.05). Compared with control group, the total amino acid content in the longissimus dorsi muscle of the fattening pigs in test group increased by 18.59% (P<0.05), the essential amino acid content increased by 19.30% (P<0.05), and the flavor amino acid content increased by 19.90% (P<0.05). The scores of essential amino acids in muscle of finishing pigs in test group were higher than those in control group and WHO/FAO model. The study indicates that adding 3% whole plant fermented hybrid Broussonetia papyrifera feed to diet instead of protein feed for fattening pigs can increase the content of free amino acids in pork, improve the composition of protein amino acids, and effectively improve the flavor quality and nutritional value of pork. [ABSTRACT FROM AUTHOR]

Lysine 2-hydroxyisobutyrylation (Khib) is a newly discovered post-translational modification in recent years, which has been identified in several species and is associated with diverse cellular functions. Botrytis cinerea, as a broad host pathogen, is very destructive and causes serious losses to agricultural economy. Argininosuccinate synthetase (ASS, citrulline-aspartate ligase) is the rate-limiting enzyme in the catalytic arginine synthesis pathway. Arginine deficiency can affect the growth of Botrytis cinerea. The Khib site Lys120 was found in functional domain of argininosuccinate synthetase 1 from Botrytis cinerea (Bcass1), which is located in conserved loop. It is worth exploring how K120hib affects the conformation of Bcass1. In this study, molecular dynamics (MD) simulations, binding free energy calculation, principal component analysis (PCA), and dynamic cross-correlation analysis were used to explore the influence of K120hib on the conformation of Bcass1. The increase of root-mean-square fluctuation (RMSF) value of related residues and PCA results suggests that K120hib increases the flexibility of some regions of Bcass1. Moreover, K120hib weakens the binding free energy between Bcass1 and the two substrates. These results will help to understand the effects of K120hib on Bcass1 and provide new ideas for regulating the pathogenicity of Botrytis cinerea. [ABSTRACT FROM AUTHOR]

Canine distemper virus (CDV) is the etiological agent of severe disease in domestic and wild carnivores. Clinical diagnosis of CDV is challenging because of its similarity to other canine respiratory and intestinal diseases. We aimed to determine certain cytokine (interleukin [IL]-1β, IL-2, IL-4, IL-6, IL-10, and tumor necrosis factor-α [TNF-α]), interferon (IFN)-γ, canine serum amyloid A (SAA), and canine citrulline (CIT) levels for the first time in CDV-positive dogs. For this purpose, 10 CDV-positive dogs with compatible clinical findings (i.e., neurological symptoms such as tremors and myoclonus, ocular and nasal discharge, and wheezing) and 10 healthy dogs based on the clinical examinations and rapid test results were enrolled. It was observed that the CIT, INF-γ, IL-1β, IL-2, IL-6, and TNF-α levels were significantly decreased in the CDV-positive dogs than that of the healthy ones (P<0.05). As a result, it was observed that CDV causes immunosuppression and accordingly, the inflammatory response might cause decreased cytokine and acute-phase protein synthesis. Therefore, it was concluded that further investigation of inflammatory pathways and CIT interactions may provide crucial clinical information at different stages of CDV, and aforementioned parameters may serve as important biomarkers for CDV in terms of demonstrating the presence of immunosuppression. [ABSTRACT FROM AUTHOR]

Hypertension is highly prevalent in postmenopausal women. Endothelial dysfunction is associated with hypertension and the age-related decreases in muscle mass and strength. L-citrulline supplementation (CIT) and slow velocity low-intensity resistance training (SVLIRT) have improved vascular function, but their effect on muscle mass is unclear. We investigated whether combined CIT and SVLIRT (CIT + SVLIRT) would have additional benefits on leg endothelial function (superficial femoral artery flow-mediated dilation (sfemFMD)), lean mass (LM), and strength in hypertensive postmenopausal women. Participants were randomized to CIT (10 g/day, n = 13) or placebo (PL, n = 11) alone for 4 weeks and CIT + SVLIRT or PL + SVLIRT for another 4 weeks. sfemFMD, leg LM and muscle strength were measured at 0, 4, and 8 weeks. CIT increased sfemFMD after 4 weeks (CIT: Δ1.8 ± 0.3% vs. PL: Δ−0.2 ± 0.5%, p < 0.05) and 8 weeks (CIT + SVLIRT: Δ2.7 ± 0.5% vs. PL + SVLIRT: Δ−0.02 ± 0.5, p = 0.003). Leg LM improved after CIT + SVLIRT compared to PL + SVLIRT (Δ0.49 ± 0.15 kg vs. Δ0.07 ± 0.12 kg, p < 0.05). Leg curl strength increased greater with CIT + SVLIRT compared to PL + SVLIRT (Δ6.9 ± 0.9 kg vs. Δ4.0 ± 1.0 kg, p < 0.05). CIT supplementation alone improved leg endothelial function and when combined with SVLIRT has additive benefits on leg LM and curl strength in hypertensive postmenopausal women. [ABSTRACT FROM AUTHOR]

Objectives: To examine the effects of lipid-based nutrient supplements (LNS) containing milk protein (MP) and/or whey permeate (WP) on markers of intestinal inflammation and enterocyte mass among stunted children. Furthermore, to explore whether gut status modifies effects of LNS on growth and micronutrient status., Methods: In a 2 × 2 factorial trial 12-59 months-old Ugandan children with stunting were randomized to four LNS formulations (100 g/day for 12 weeks) containing MP or soy protein and WP or maltodextrin, or to no supplementation. Linear mixed-effects models were used to explore faecal myeloperoxidase (f-MPO) and plasma citrulline (p-cit) as outcomes and modifiers of the intervention effects (ISRCTN13093195)., Results: Of 750 children, mean ± SD age was 32.0 ± 11.7 months and height-for-age Z-score was -3.02 ± 0.74. Neither MP nor WP had effects on p-cit or f-MPO. f-MPO decreased over time among controls (ratio of change 0.54, 95% confidence interval [CI]: 0.35, 0.84), but not among those given LNS (0.99, 95% CI: 0.79, 1.23) (p = 0.016). In contrast, LNS had no effect on p-cit (p = 0.27). The effect of LNS on cobalamin (B12) status was reduced in children with p-cit <20 µmol/L; whereby there was 20% (95% CI: 2, 35) lower increase in plasma cobalamin and 59% (95% CI: 13, 125) smaller decrease in plasma methylmalonic acid. p-cit or f-MPO did not modify the effects of LNS on growth or other micronutrient markers., Conclusion: LNS had no effect on enterocyte mass and possibly increased intestinal inflammation. The effect of LNS on cobalamin status was reduced in those with low enterocyte mass., (© 2025 The Author(s). Journal of Pediatric Gastroenterology and Nutrition published by Wiley Periodicals LLC on behalf of European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.)

European Research Network for evaluation and improvement of screening, Diagnosis, and treatment of Inherited disorders of Metabolism (ERNDIM) provides proficiency testing to clinical laboratories that offer biochemical testing, including urine organic acids analysis. Following an educational challenge, ERNDIM provided a mass spectrum of the 'trimethylsilyl derivative of cyclic derivative of citrulline' to participating laboratories. Though there is knowledge among some in the biochemical genetics' community, that the cyclic derivative of citrulline can be identified in urine of patients with citrullinemia type I, we could not find any published literature regarding this analyte in patient samples, nor were able to obtain any standard material. We did note two publications that proposed chemical structures for the cyclic derivative of citrulline, but neither suggested a clinical utility for this compound and the two proposed structures differed. Here, we used the mass spectrum provided by ERNDIM to retrospectively evaluate existing urine organic acids data from patients affected with conditions associated with elevated levels of plasma citrulline to learn more about this marker in urine and to correlate it with plasma citrulline data in diagnostic and follow-up samples. We document a positive correlation between the concentration of this compound in patient urine and the concentration of citrulline in concurrently collected plasma. We establish that this analyte is a good marker for citrullinemia type I but is not unique to this condition. Finally, we correlate the mass spectrum with the chemical structure originally proposed by Wilson et al. in 1978., Competing Interests: Declaration of competing interest None., (Copyright © 2025. Published by Elsevier Inc.)

Background: Peripheral artery disease (PAD) is a major public health concern due to its high prevalence, severe impact on individuals' health and quality of life, and substantial economic burden. Pharmacological interventions are still limited with numbers needed-to-treat ranging from 6 (cilostazol) to 50 (aspirin, statins, and vorapaxar)., Objectives: This randomized, placebo-controlled, double-blinded crossover interventional trial aims to measure the effect of L-citrulline and tetrahydrobiopterin (H 4 Bip) on walking distance in patients with PAD, stratified by plasma levels of asymmetric dimethyl L-arginine (ADMA), the endogenous inhibitor of endothelial nitric oxide (NO) synthase., Methods: We measured preinterventional ADMA levels in 51 patients with PAD in Australia and Germany with mean changes in absolute claudication distance (dACD) as the primary outcome upon orally supplementing the L-arginine precursor, L-citrulline (3 g) twice daily for 12 weeks, and, in one arm, additionally H 4 Bip (0.45 g) once per day for a further 2 weeks., Results: Preinterventional ADMA levels were pathological (>0.4 μM) in 34 patients. Supplementation with L-citrulline significantly increased the mean plasma levels of both L-citrulline and L-arginine, from 41.8 ± 2.7 μmol/l to 246.3 ± 67.3 μmol/l (P = 0.004) and from 75.2 ± 4.2 μmol/l to 119.2 ± 6.9 μmol/l (P < 0.0001) respectively, when compared with placebo. dACD in % of control was significantly improved by L-citrulline vs placebo (20.11% ± 4.50% vs 5.73% ± 2.74%, respectively; P = 0.011). Further addition of H 4 Bip increased the mean percentage dACD to 28.15% ± 6.84% (P = 0.021), but only in patients with preinterventional pathological ADMA levels., Conclusions: L-citrulline and, when ADMA levels are pathological, H 4 Bip are effective nutritional interventions in patients with PAD warranting further confirmatory trials., Competing Interests: Funding Support and Author Disclosures This work was supported by the National Health and Medical Research Council, Australia (595964), the European Research Council Advanced Investigator programme (RadMed), the European Union's Horizon 2020 research and innovation programme under grant agreement No. 777111 (REPO-TRIAL), the REPO4EU project funded by the European Union under grant agreement No. 101057619. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or European Health and Digital Executive Agency (HADEA). Neither the European Union nor the granting authority can be held responsible for them. This reflects only the author's view, and the European Commission is not responsible for any use that may be made of the information it contains. The funders had no role in the design, data collection, statistical analysis, writing of this manuscript, or decision to publish. The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2025. Published by Elsevier Inc.)

The main purpose of this study was to optimize the L-citrulline production process using Plackett-Burman and Box-Behnken designs. L-citrulline-producing bacterium BH-01 was isolated from raw buffalo milk. The isolate was tested for probiotic activities such as tolerance to simulated gastric and intestinal juices, antagonistic activity against six antibiotic-resistant bacteria, and temperature tolerance. L-citrulline production and arginine deiminase (ADI) activity were optimized using statistical designs. The bacterial isolate was molecularly identified as Bacillus subtilis strain AUMC B-498 (accession number PP574248.1). The strain exhibited resistance at pH 2.0 and bile salt 0.5% for a two-hour exposure period. It could inhibit the growth of Escherichia coli, Klebsiella pneumonia, Serratia sp., Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae. From the results of statistical optimization, the Plackett-Burman design identified temperature, L-arginine, incubation period, and peptone as the most effective factors among the eight selected variables. Based on these, the Box-Behnken design was used to optimize the factors required to maximize citrulline production. The maximum L-citrulline was 632.5 µg/L, and ADI activity was 1.42 U/mL. Therefore, BH-01 isolated from Buffalo milk might be a promising candidate in food, biotechnological, and pharmaceutical applications due to its dual functionality for citrulline production and probiotic characteristics., Competing Interests: Declarations. Ethical approval: this study does not contain any studies involving human participants and/or animals. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Increasing global life expectancy motivates investigations of molecular mechanisms of aging and age-related diseases. This study examines age-associated changes in red blood cells (RBCs), the most numerous host cell in humans. Four cohorts, including healthy individuals and patients with sickle cell disease, were analyzed to define age-dependent changes in RBC metabolism. Over 15,700 specimens from 13,757 humans were examined, a major expansion over previous studies of RBCs in aging. Multi-omics approaches identified chronological age-related alterations in the arginine pathway with increased arginine utilization in RBCs from older individuals. These changes were consistent across healthy and sickle cell disease cohorts and were influenced by genetic variation, sex, and body mass index. Integrating multi-omics data and metabolite quantitative trait loci (mQTL) in humans and 525 diversity outbred mice functionally linked metabolism of arginine during RBC storage to increased vesiculation-a hallmark of RBC aging-and lower post-transfusion hemoglobin increments. Thus, arginine metabolism is a biomarker of RBC and organismal aging, suggesting potential new targets for addressing sequelae of aging., (© 2024 The Author(s). Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)

Background: Preeclampsia (PE) contributes to maternal and fetal mortality and morbidity. Supplementation with L-arginine, the precursor of nitric oxide, has not proven effective, possibly due to extensive arginine catabolism in the splanchnic bed. Citrulline is converted by the kidney to L-arginine. Citrulline, therefore, could be a more effective nitric oxide donor in the treatment of PE., Objectives: The study aimed to determine whether oral L-citrulline supplementation would prolong the delay between diagnosis and delivery in preeclamptic females., Methods: A total of 115 females with monofetal preeclamptic pregnancy were enrolled before 36 weeks of gestation in a multicenter randomized, double-blind trial: 58 received oral L-citrulline supplementation, and 57 received placebo. The duration of pregnancy, neonatal and maternal outcomes, and soluble fms-like tyrosine kinase 1/placental growth factor ratio, an index of placental dysfunction, were monitored., Results: Gestational age at inclusion was similar in both groups. The duration of pregnancy between inclusion and delivery was unaltered (hazard ratio: 0.90; 95% confidence interval: 0.62, 1.31). Neither neonatal weight nor pregnancy outcome differed between groups. Liver enzymes were higher on the day of delivery in the treated, compared to the placebo group (65.1 compared with 33.2 UI and 70.4 compared with 33.7 UI for alanine aminotransferase and aspartate aminotransferase, respectively, (estimate: 5.92; 95% confidence interval: 1.09, 10.74). Systolic blood pressure (BP) was higher at delivery in the citrulline group compared with the control group (P = 0.015), whereas the diastolic BP showed no difference. We did not find any difference in neonatal outcomes nor soluble fms-like tyrosine kinase 1/placental growth factor ratio., Conclusions: The current trial found no benefit of oral L-citrulline supplementation to females with PE regarding either the duration of pregnancy, fetal growth, or maternal and neonatal outcomes. Systolic BP and liver enzymes levels were found to increase at delivery in the treated group. L-citrulline oral supplementation does not seem to be a promising candidate as a therapeutic intervention in pregnancies with PE. This trial was registered at CITRUPE as NCT02801695., Competing Interests: Conflict of interest NW declares participation as expert and speaker activities for Roche Diagnostics France. All other authors report no conflicts of interest., (Copyright © 2024 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Tumor cells must optimize metabolite acquisition between synthesis and uptake from a microenvironment characterized by hypoxia, lactate accumulation, and depletion of many amino acids, including arginine. We performed a metabolism-focused functional screen using CRISPR-Cas9 to identify pathways and factors that enable tumor growth in an arginine-depleted environment. Our screen identified the SLC-family transporter SLC7A5 as required for growth, and we hypothesized that this protein functions as a high-affinity citrulline transporter. Using isotope tracing experiments, we show that citrulline uptake and metabolism into arginine are dependent upon expression of SLC7A5. Pharmacological inhibition of SLC7A5 blocks growth under low-arginine conditions across a diverse group of cancer cell lines. Loss of SLC7A5 reduces tumor growth and citrulline import in a mouse tumor model. We identify a conditionally essential role for SLC7A5 in arginine metabolism, and we propose that SLC7A5-targeting therapeutic strategies in cancer may be effective in the context of arginine limitation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Rheumatoid arthritis (RA) is associated with high-risk HLA class II alleles known as the "RA shared epitope." Among prevalent shared epitope alleles, study of DRB1*04:04 has been limited. To define relevant epitopes, we identified citrullinated peptide sequences from synovial antigens that were predicted to bind to HLA-DRB1*04:04 and utilized a systematic approach to confirm their binding and assess their recognition by CD4 T cells. After confirming the immunogenicity of 13 peptides derived from aggrecan, cartilage intermediate layer protein (CILP), α-enolase, vimentin, and fibrinogen, we assessed their recognition by T cells from a synovial tissue sample, observing measurable responses to 8 of the 13 peptides. We then implemented a multicolor tetramer panel to evaluate the frequency and phenotype of antigen-specific CD4 T cells in individuals with anti-citrullinated protein antibody-positive RA and controls. In subjects with RA, CILP-specific T-cell frequencies were significantly higher than those of other antigens. The surface phenotypes exhibited by antigen-specific T cells were heterogeneous, but Th1-like and Th2-like cells predominated. Stratifying based on disease status and activity, antigen-specific T cells were more frequent and most strongly polarized in RA subjects with high disease activity. In total, these findings identify novel citrullinated epitopes that can be used to interrogate antigen-specific CD4 T cells and show that antigen-specific T-cell frequency is elevated in subjects with high disease activity., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Immunology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Purpose: To enhance the detection rate of Neonatal Intrahepatic Cholestasis caused by Citrin Deficiency (NICCD) through newborn screening (NBS), we analyzed the metabolic profiles of missed patients and proposed a more reliable method for early diagnosis., Methods: In this retrospective study, NICCD patients were classified into "Newborn Screening" (64 individuals) and "Missed Screening" (52 individuals) groups. Metabolic profiles were analyzed using the non-derivatized MS/MS Kit, and genetic mutations were identified via next-generation sequencing and confirmed by Sanger sequencing. Receiver Operating Characteristic (ROC) analysis evaluated the predictive value of amino acids and acylcarnitines in dried blood spots (DBS) for identifying missed patients including 40 missed patients and 17,269 healthy individuals, with additional validation using 12 missed patients and 454 healthy controls., Results: The age of diagnosis was significantly higher in the "Missed Screening" group compared to the "Newborn Screening" group (74.50 vs. 18.00 days, P < 0.001). ROC analysis revealed that citrulline had excellent diagnostic accuracy for missed patients, with an AUC of 0.970 and a cut-off value of 17.57 µmol/L. Additionally, glycine, phenylalanine, ornithine, and C8 were significant markers, each with an AUC greater than 0.70. A combination of these markers achieved an AUC of 0.996 with a cut-off value of 0.00195. Validation demonstrated a true positive rate of 91.67% and a true negative rate of 96.48%. Common SLC25A13 mutations in both groups were c.852&#95;855del, IVS16ins3kb, and c.615 + 5G > A., Conclusions: Combining multiple metabolic markers during NBS significantly improves sensitivity and specificity for detecting missed NICCD cases. However, the relationship between genetic mutations and missed cases remains unclear., Competing Interests: Declarations. Ethics approval and consent to participate: This study was approved by the Institutional Review Board of the Ethics Committee in Children’s Hospital, Zhejiang University School of Medicine (reference number: 2021-IRB-292). Written consents were obtained from parents for sample collection and data publication. Consent for publication: We confirm that the family has signed a written informed consent for the publication of their children’s genetic data, clinical details, and/or any accompanying images. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Background: Ornithine transcarbamylase deficiency exhibits a high degree of clinical heterogeneity, making its screening and classification challenging in some instances. In this study, we first established a simple and stable method for testing ornithine transcarbamylase activity using micro blood from newborns, rather than relying on venous blood., Methods: The activity of ornithine transcarbamylase was assessed by measuring the concentration of citrulline produced in the reaction with carbamoyl phosphate and ornithine, using serum, plasma or micro blood. Correlation analysis was evaluated using Sangerbox Tools. The Receiver Operating Characteristic curve was used in SPSS Statistics 17.0 to evaluate the diagnostic efficiency of Ornithine transcarbamylase deficiency., Results: A strong linear relationship was observed between ornithine transcarbamylase activity and both micro blood volume and reaction time (R 2  = 0.9793, 0.9922 respectively). The intra-coefficient variation and inter-coefficient variation were 11% and 12.5% with a 1-h reaction time, and 6.77% and 9.58% with a 3-h reaction time, respectively. And the inter-coefficient variation was lower than the most widely used colorimetry method (5.1-21.1%). The Limit of Blank was 0.57 nmol/mL/h. The reference interval for normal newborn population is greater than or equal to 39.6 nmol/mL/h. Notably, the method exhibited a 100% sensitivity, surpassing the sensitivity of colorimetry method (94.3%), along with and a specificity of 96.9% for diagnosing ornithine transcarbamylase deficiency., Conclusions: We pioneered a method for testing OTC activity that normally carried on venous blood can be effectively performed on microblood heel samples. Meanwhile, our method presents a simpler, more stable and reproducible approach compared to colorimetry., Competing Interests: Declarations. Ethics approval and consent to participate: The human studies were conducted following the ethical standards of the institutional and/or national research committee (Nanjing Women and Children's Healthcare Hospital + [2014]36) and the 2013 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from the patients or their guardians. Consent for publication: All authors read and approved the final manuscript. Competing interests: There are no conflicts to declare., (© 2025. The Author(s).)

Background: Meat goat production is a worldwide industry with products such as meat, milk, soap, and fiber being produced. There are approximately 2.6 million meat goats in the United States. For breeding female ruminants, early pregnancy loss is estimated to be 30% within the first month of gestation. Extracellular L-citrulline (a precursor to L-arginine) is not degraded by ruminal microbes due to the lack of uptake. L-Arginine and thus L-citrulline, have beneficial impacts on placentation and, subsequently, fetal-placental development and survival. This study aimed to determine the impact of feeding L-citrulline to meat goats during gestation to improve reproductive success. Meat goats were fed either a control (CON) or L-citrulline (CIT) supplemented diet from d 12 to 82 of gestation. Blood samples were collected and sera were subjected to high-performance liquid chromatography analyses to quantify the abundance of amino acids. Pregnancy rates were determined on d 30, 61, and 90 of gestation, and litter weight, individual birth weights, and 90 d adjusted weaning weights were collected., Results: The concentrations of citrulline, ornithine, and arginine were greater in CIT does compared to CON does, but there was no difference in pregnancy rates between CON and CIT does. Birth weight was greater for male kids born as singles when compared to females, but this phenotype was not observed for kids born as twins or triplets. Further, males born to CON does had greater 90 d adjusted weaning weights than females, but this was not observed in the CIT group. Female kids born to CON and CIT Boer goats had heavier 90 d adjusted weaning weights than those born to Spanish or F1 Boer-Spanish does., Conclusion: This study provides proof of concept that feeding dietary L-citrulline increases concentrations of citrulline and arginine in blood of gestating meat goats. However, further studies are needed to understand the cellular mechanisms impacted by feeding this supplement. Regardless, this study demonstrated that feeding L-citrulline has the potential to increase reproductive performance in gestating ruminants., Competing Interests: Declarations. Ethics approval and consent to participate: All experimental procedures followed the Guide for the Use of Agriculture Animals in Research and Teaching and were approved by the Institutional Animal Care and Use Committee at Prairieview A&M University. Consent for publication: Not applicable. Competing interests: The authors have no conflict of interest to declare., (© 2025. The Author(s).)

Severe intestinal mucositis (IM) increases the risk of bloodstream infections (BSI) and inflammatory toxicity during acute lymphoblastic leukaemia (ALL) induction treatment. However, the implications of IM in subsequent ALL therapy phases after achieving remission remain unknown. This study investigated the relationship between IM (measured by plasma citrulline and the chemokine CCL20) and the development of BSI and systemic inflammation (reflected by C-reactive protein, CRP) in children with ALL during high-dose methotrexate (HDMTX) treatment, an important part of ALL consolidation therapy. The study compared patients treated according to the NOPHO ALL 2008 protocol (n = 52) and the ALLTogether1 protocol (n = 42), both with identical HDMTX procedures but different scheduling. One week post-HDMTX, citrulline dropped to median levels of 14.5 and 16.9 μM for patients treated according to the NOPHO ALL 2008 and ALLTogether1 protocols, respectively (p = 0.11). In a protocol and neutrophil count-adjusted analysis, hypocitrullinaemia (<10 μmol/L) was associated with increased odds of BSI within 3 weeks from HDMTX (OR = 26.2, p = 0.0074). Patients treated according to the NOPHO ALL 2008 protocol exhibited increased mucosal- and systemic inflammation post-HDMTX compared to patients treated according to ALLTogether1, with increased CCL20 (14.6 vs. 3.7 pg/mL, p < 0.0001) and CRP levels (10.0 vs. 1.0 mg/L, p < 0.0001). Both citrulline and CCL20 correlated with CRP for these patients (r s  = -0.44, p = 0.0016 and r s  = 0.35, p = 0.016, respectively). These results suggest that hypocitrullinaemia following HDMTX increases the risk of BSI, confirming previous observations from more intensive treatments. Moreover, these data indicate that the patients' vulnerability to mucositis and inflammatory toxicity after chemotherapy varies with treatment protocol., (© 2024 The Author(s). International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Background: Cross-sectional plasma citrulline concentration (CIT) is considered a marker of enterocyte mass. The role of CIT in clinical practice in patients with short bowel syndrome (SBS) is not clearly defined., Aim: To assess the accuracy of CIT to discriminate SBS from healthy controls (HC) and SBS with intestinal failure (SBS-IF), requiring intravenous supplementation (IVS), from SBS with intestinal insufficiency (SBS-II)., Methods: Cross-sectional study on unselected outpatients (31 SBS-II, 113 SBS-IF) and 19 healthy controls (HC). Demographic data, SBS characteristics, nutritional status, oral intake, intestinal fat absorption, renal function and IF severity, categorized by the volume of the required IVS, were collected at time of CIT evaluation (µmol/L). Data as mean±SD., Results: CIT was 36.6 ± 6.0 in HC, 30.2 ± 14.0 in SBS-II and 18.8 ± 12.3 in SBS-IF (p < 0.001). CIT cutoff was 31 for the diagnosis of SBS (sensitivity 79 %, specificity 89 %), and 14 for the discrimination between SBS-IF and SBS-II (sensitivity 100 %, specificity 51 %). Wide ranges of CIT were observed in all SBS-IF severity categories., Conclusions: In unselected SBS patients, CIT was accurate to diagnose SBS, had high sensitivity to diagnose SBS-IF but showed low specificity for SBS-II. In SBS-IF, CIT was not an accurate marker of IF severity., Competing Interests: Conflict of interest LP: Participation on Data Safety Monitoring Board and Advisory Board for Takeda; consulting fees for Takeda, Northsea Therapeutics, NAPO Therapeutics, Lionhealth, Nestlè; honoraria for lectures for Baxter. MG, ASS, CC, GA, MGA, CB, LL, LM, AN, FP, CR, FS, MS, LB: none, (Copyright © 2024 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

An autoimmune condition known as rheumatoid arthritis (RA) is characterized by persistent polyarticular inflammation. Within two years of the disease's onset, irreparable bone and joint deterioration can occur as a result of the inflammatory course of the illness, leading to joint deformity and loss of function. In most patients diagnosed with RA, a range of autoantibodies, particularly anti-citrullinated protein antibodies (ACPA), can be detected months to years before the onset of clinically recognizable disease. Additionally, an increasing number of studies suggest that ACPA is involved in the pathogenesis of RA and may play a direct pathogenic role in the disease. This paper focuses on the role of ACPA in the pathomechanism of RA and discusses its unique clinical applications for the early identification and prediction of RA, as well as the influencing factors. Moreover, this article outlines the association of ACPA-positive (ACPA + ) RA with other autoimmune diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)