Elevated blood purine levels as a biomarker of seizures and epilepsy.

OBJECTIVE: There is a major unmet need for a molecular biomarker of seizures or epilepsy that lends itself to fast, affordable detection in an easy-to-use point-of-care device. Purines such as adenosine triphosphate and adenosine are potent neuromodulators released during excessive neuronal activity that are also present in biofluids. Their biomarker potential for seizures and epilepsy in peripheral blood has, however, not yet been investigated. The aim of the present study was to determine whether blood purine nucleoside measurements can serve as a biomarker for the recent occurrence of seizures and to support the diagnosis of epilepsy. METHODS: Blood purine concentrations were measured via a point-of-care diagnostic technology based on the summated electrochemical detection of adenosine and adenosine breakdown products (inosine, hypoxanthine, and xanthine; SMARTChip). Measurements of blood purine concentrations were carried out using samples from mice subjected to intra-amygdala kainic acid-induced status epilepticus and in video-electroencephalogram (EEG)-monitored adult patients with epilepsy. RESULTS: In mice, blood purine concentrations were rapidly increased approximately two- to threefold after status epilepticus (2.32 ± .40 µmol·L-1 [control] vs. 8.93 ± 1.03 µmol·L-1 [after status epilepticus]), and levels correlated with seizure burden and postseizure neurodegeneration in the hippocampus. Blood purine concentrations were also elevated in patients with video-EEG-diagnosed epilepsy (2.39 ± .34 µmol·L-1 [control, n = 13] vs. 4.35 ± .38 µmol·L-1 [epilepsy, n = 26]). SIGNIFICANCE: Our data provide proof of concept that the measurement of blood purine concentrations may offer a rapid, low-volume bedside test to support the diagnosis of seizures and epilepsy.

Sensitive ratiometric fluorescence assay for detecting xanthine in serum based on the inner filter effect of enzyme-catalyzed oxidation products to silicon nanoparticles.

A new type of fluorescent silicon nanoparticles (SiNPs) were prepared via a facile one-pot hydrothermal method by using N-[3-(trimethoxysilyl)propyl]-ethylenediamine (DAMO) and glucose as reagents, and were subsequently applied to construct a ratiometric fluorescence assay for sensitive and rapid determination of xanthine in human serum. Two catalytic oxidation reactions were employed to induce a fluorescence response of the testing system towards xanthine. Under the catalysis of xanthine oxidase (XOD), xanthine in serum samples was oxidized and produced hydrogen peroxide (H2O2). By utilizing o-phenylenediamine (OPD) as the substrate for horseradish peroxidase (HRP) in the presence of H2O2, fluorescent 2,3-diaminophenazine (DAP) was finally generated. A ratiometric fluorescence assay for xanthine was established by determining the ratio of the green-yellow fluorescence emission of DAP and the blue fluorescence emitted from SiNPs under the inner filter effect (IFE) of DAP. Instead of traditional multi-step procedures for adding reacting reagents to the testing solution, all the reaction reagents were mixed with serum samples in a single step for this assay to shorten the total reaction time. This assay demonstrates superiority over a solo DAP fluorescence-based assay as well as other reported methods, with excellent sensitivity and reduced testing time. The strategies proposed in this work for both synthesis and application of fluorescent SiNPs can be used in future fabrication of novel fluorescent probes, especially for sensing biological metabolites involved in H2O2-generation or consumption reactions.

Improved ultra-high performance liquid chromatographic method for simultaneous determination of five gout-related metabolites in human serum.

Creatinine and purines are gout-related metabolites commonly quantified by liquid chromatography coupled with ultraviolet and mass spectrometry. However, the high cost of liquid chromatography coupled with mass spectrometry hindered its extensive use in ordinary hospitals and clinical laboratories. Using the traditional liquid chromatography method, the full separation of these metabolites in complex biological samples is still not achieved. In this study, an improved ultra-high-performance liquid chromatography with ultraviolet spectroscopy method was reported for quantitative determination of five gout-related metabolites (i.e., creatinine, uric acid, hypoxanthine, xanthine, and inosine) in human serum within 10 min. A UHPLC system equipped with a hydrophilic C18 column was used to improve separation, shorten analysis time, and increase analysis throughput. The performance of the method was validated by evaluating linearity (squared correlation coefficient > 0.9991), recovery (92.8-100.0%, with relative standard deviation < 4.7%), accuracy (relative errors < 14.6%), precision (0.2-4.1% for intraday and 2.1-7.3% for interday) and stability (-14.1 to 8.3% in autosampler for 12 h and -13.3 to 2.2% for freeze-thaw cycles). This method was successfully applied to quantify gout-related metabolites in serum samples of healthy controls and gout patients, which was expected to be used in the clinical investigation of gout at different stages.

Renal Reabsorptive Transport of Uric Acid Precursor Xanthine by URAT1 and GLUT9.

Xanthine and hypoxanthine are intermediate metabolites of uric acid and a source of reactive oxidative species (ROS) by xanthine oxidoreductase (XOR), suggesting that facilitating their elimination is beneficial. Since they are reabsorbed in renal proximal tubules, we investigated their reabsorption mechanism by focusing on the renal uric acid transporters URAT1 and GLUT9, and examined the effect of clinically used URAT1 inhibitor on their renal clearance when their plasma concentration is increased by XOR inhibitor. Uptake study for [3H]xanthine and [3H]hypoxanthine was performed using URAT1- and GLUT9-expressing Xenopus oocytes. Transcellular transport study for [3H]xanthine was carried out using Madin-Darby canine kidney (MDCK)II cells co-expressing URAT1 and GLUT9. In in vivo pharmacokinetic study, renal clearance of xanthine was estimated based on plasma concentration and urinary recovery. Uptake by URAT1- and GLUT9-expressing oocytes demonstrated that xanthine is a substrate of URAT1 and GLUT9, while hypoxanthine is not. Transcellular transport of xanthine in MDCKII cells co-expressing URAT1 and GLUT9 was significantly higher than those in mock cells and cells expressing URAT1 or GLUT9 alone. Furthermore, dotinurad, a URAT1 inhibitor, increased renal clearance of xanthine in rats treated with topiroxostat to inhibit XOR. It was suggested that xanthine is reabsorbed in the same manner as uric acid through URAT1 and GLUT9, while hypoxanthine is not. Accordingly, it is expected that treatment with XOR and URAT1 inhibitors will effectively decrease purine pools in the body and prevent cell injury due to ROS generated during XOR-mediated reactions.

Nitrogen-doped graphene quantum dot-based sensing platform for metabolite detection.

A novel fluorescent sensing platform based on nitrogen-doped graphene quantum dots (N-GQDs) is presented, which is able to detect various metabolites (cholesterol, glucose, lactate, and xanthine) rapidly, sensitively, and selectively. Hg2+ can attach on the surface of N-GQDs, leading to the quenching of N-GQD fluorescence. In the presence of cysteine (Cys), Hg2+ is released from N-GQDs and associates with Cys. Then, the fluorescence of N-GQDs is recovered. Hydrogen peroxide, resulting from the enzymatic oxidation of metabolites, can convert two molecules of Cys into one molecule of cystine, which cannot bind with Hg2+. So, the fluorescence of N-GQDs quenched again. For cholesterol, glucose, lactate, and xanthine, the limits of detection are 0.035 µmol/L, 0.025 µmol/L, 0.07 µmol/L, and 0.04 µmol/L, respectively, and the linear ranges are 1-12 µmol/L, 0.06-3 µmol/L, 0.2-70 µmol/L, and 0.12-17 µmol/L, respectively. The presented method was applied to quantify metabolites in human blood samples with satisfactory results. Graphical abstract.

Convenient synthesis of three-dimensional hierarchical CuS@Pd core-shell cauliflowers decorated on nitrogen-doped reduced graphene oxide for non-enzymatic electrochemical sensing of xanthine.

A novel hybrid with three-dimensional (3D) hierarchical CuS@Pd core-shell cauliflowers decorated on nitrogen-doped reduced graphene oxide (CuS@Pd/N-RGO) has been prepared by a facile wet-chemical route without utilizing any template molecules and surfactants. The characterization results reveal that the 3D flower-like structure of CuS "core" is composed of interconnecting nanoplates, which is conductive to the loading of Pd nanoparticles' "shell" and results in the robust interaction between the core and shell for the formation of CuS@Pd cauliflowers. Anchoring such appealing CuS@Pd cauliflowers on the two-dimensional N-RGO can efficaciously inhibit the aggregation of CuS@Pd cauliflowers and accelerate the kinetics of xanthine oxidation. Benefiting from the multi-functional properties and unique morphology, the sensor constructed by CuS@Pd/N-RGO exhibits excellent performance for non-enzymatic detection of xanthine including a wide detection range of 0.7-200.0 µM (0.94 V vs. SCE), a low detection limit of 28 nM (S/N = 3), high reproducibility (relative standard deviation (RSD) = 4.1%), and commendable stability (retained 90% of the initial electrochemical responses after storage for 30 days), which is amongst the best of various electrochemical sensors reported for xanthine assays till date. Reliable and satisfying recoveries (95-105%, RSD ≤ 4.1%) are achieved for xanthine detection in real samples. The inspiring results make the uniquely structural CuS@Pd/N-RGO greatly promising in non-enzymatic electrochemical sensing applications. Graphical abstract A high-performance non-enzymatic xanthine sensor has been constructed by the three-dimensional hierarchical CuS@Pd core-shell cauliflowers decorated on nitrogen-doped reduced graphene oxide.

Change in Lactate, Ammonia, and Hypoxanthine Concentrations in a 1-Year Training Cycle in Highly Trained Athletes: Applying Biomarkers as Tools to Assess Training Status.

Wlodarczyk, M, Kusy, K, Slominska, E, Krasinski, Z, and Zielinski, J. Change in lactate, ammonia, and hypoxanthine concentrations in a 1-year training cycle in highly trained athletes: applying biomarkers as tools to assess training status. J Strength Cond Res 34(2): 355-364, 2020-The aim was to determine changes in biomarker (LA, NH3, purine metabolites) blood concentration during graded exercise and recovery throughout an annual training cycle in highly trained athletes of different training profiles. The study included 12 sprinters (SP, 21-30 years), 11 triathletes (TR, 20-31 years), 12 futsal players (FU, 19-31 years), and 13 amateur runners (AM, 20-33 years). Purine metabolite (hypoxanthine, xanthine, uric acid), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes postexercise) in 4 phases of an annual training cycle. Purine metabolite concentration was determined from plasma, whereas LA and NH3 from whole blood. For LA during exercise and recovery, certain significant differences between training phases within groups were observed for FU, TR, and SP but not for AM. For NH3, the greatest differences between examination points were observed for SP and TR near maximal exercise and in the first few stages of recovery. For hypoxanthine (Hx), the largest amount of differences between examination points was observed for FU, TR, and FU throughout the entire exercise spectrum. Biomarker concentration dynamics change during an incremental exercise test and postexercise in an annual training cycle. Biomarker responses differ depending on training type and magnitude of training loads used in various phases of an annual training cycle. When assessing training status using an incremental exercise test throughout an annual training cycle, NH3 and Hx concentration changes are more sensitive compared with LA.

Study on the diagnosis of gout with xanthine and hypoxanthine.

BACKGROUND: Hyperuricemia is the only biochemical index in the classification of acute gouty arthritis in American Rheumatism Association 1977 and the main basis of clinical diagnosis for most doctors. However, nearly half of the time gout occurs without hyperuricemia, especially in an acute attack，which leads to an urgent need to find a new substitute diadynamic criteria of gout. Xanthine and hypoxanthine, as precursors of uric acid, have been reported to be high in gout patients with hyperuricemia and presumed to be gout biomarkers. OBJECTIVES: To further explore the possibility of xanthine and hypoxanthine to be gout biomarkers as substitutes for uric acid. METHODS: A reversed-phase HPLC-UV method was employed for simultaneous quantitative detection of uric acid (UA), xanthine (X), and hypoxanthine (HX) in gout patients' (with and without hyperuricemia) and healthy persons' serum. RESULTS: The xanthine and hypoxanthine concentrations in gout patients with hyperuricemia and without hyperuricemia are higher than in healthy persons with a P < 0.001. CONCLUSIONS: This study supplements previous researches by confirming that xanthine and hypoxanthine are significantly elevated in gout patients' serum especially in patients' with normouricemia, which supported xanthine and hypoxanthine may have clinical application for the diagnosis of gout.

Changes in Blood Concentration of Adenosine Triphosphate Metabolism Biomarkers During Incremental Exercise in Highly Trained Athletes of Different Sport Specializations.

Wlodarczyk, M, Kusy, K, Slominska, E, Krasinski, Z, and Zielinski, J. Changes in blood concentration of adenosine triphosphate metabolism biomarkers during incremental exercise in highly trained athletes of different sport specializations. J Strength Cond Res 33(5): 1192-1200, 2019-We hypothesized that (a) high-level specialized sport training causes different adaptations that induce specific biomarker release dynamics during exercise and recovery and (b) skeletal muscle mass affects biomarker release. Eleven sprinters (21-30 years), 16 endurance runners (18-31 years), 12 futsal players (18-29 years), and 12 amateur runners as controls (22-33 years) were examined. Hypoxanthine (Hx), xanthine (X), uric acid (UA), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes after exercise). Hx, X, and UA concentration was determined from plasma, while LA and NH3 from whole blood, and muscle mass was assessed using dual X-ray absorptiometry method. At rest, during incremental exercise, and up to 30 minutes into the postexercise recovery period, sprinters had lowest Hx, X, and UA concentrations, and endurance athletes had lowest NH3 concentrations. For LA during exercise, the lowest concentrations were noted in endurance athletes, except when reaching maximum intensity, where the differences between groups were not significant. There were no significant correlations observed between skeletal muscle mass and biomarker concentration at maximal intensity and recovery in any group. In conclusion, the magnitude of exercise-induced biomarker concentration is only related to training adaptations through specific training profile but not to muscle mass. In addition, the results suggest that combined measuring of LA, NH3, and Hx concentration in blood is useful in indirectly reflecting key changes in exercise- and training-induced energy status. Further research should focus on studying how specific training sessions affect individual biomarker response in highly trained athletes.

A non-enzymatic voltammetric xanthine sensor based on the use of platinum nanoparticles loaded with a metal-organic framework of type MIL-101(Cr). Application to simultaneous detection of dopamine, uric acid, xanthine and hypoxanthine.

A Cr-based metal-organic framework MIL-101(Cr) was used to load platinum nanoparticles (PtNPs) that were placed on a glassy carbon electrode (GCE). The modified GCE was used as a non-enzymatic xanthine sensor. Compared to bare GCE, it requires a strongly decreased working potential and an increased signal current for xanthine oxidation. This is due to the crystalline ordered structure and large specific surface of the MIL-101(Cr), and to the high conductivity of the Pt NPs. Differential pulse voltammetry (DPV) shows the sensor to have a wide linear range (0.5 - 162 µM), a low detection limit (0.42 µM), and high selectivity. It was applied to the simultaneous determination of dopamine, uric acid, xanthine and hypoxanthine at working potentials of 0.13, 0.28, 0.68 and 1.05 V, respectively (vs. Ag/AgCl) and to quantify xanthine in spiked serum samples. Graphical abstract This is the first report of non-enzymatic xanthine electrochemical sensor based on metal-organic framework loaded with nanoparticles.

Uric Acid and Xanthine Levels in Pregnancy Complicated by Gestational Diabetes Mellitus-The Effect on Adverse Pregnancy Outcomes.

Uric acid (UA) levels are associated with many diseases including those related to lifestyle. The aim of this study was to evaluate the influence of clinical and anthropometric parameters on UA and xanthine (X) levels during pregnancy and postpartum in women with physiological pregnancy and pregnancy complicated by gestational diabetes mellitus (GDM), and to evaluate their impact on adverse perinatal outcomes. A total of 143 participants were included. Analyte levels were determined by HPLC with ultraviolet detection (HPLC-UV). Several single-nucleotide polymorphisms (SNPs) in UA transporters were genotyped using commercial assays. UA levels were higher within GDM women with pre-gestational obesity, those in high-risk groups, and those who required insulin during pregnancy. X levels were higher in the GDM group during pregnancy and also postpartum. Positive correlations between UA and X levels with body mass index (BMI) and glycemia levels were found. Gestational age at delivery was negatively correlated with UA and X levels postpartum. Postpartum X levels were significantly higher in women who underwent caesarean sections. Our data support a possible link between increased UA levels and a high-risk GDM subtype. UA levels were higher among women whose glucose tolerance was severely disturbed. Mid-gestational UA and X levels were not linked to adverse perinatal outcomes.

Global and targeted serum metabolic profiling of colorectal cancer progression.

BACKGROUND: Patients with colorectal adenoma polyps (PLPs) are at higher risk for developing colorectal cancer (CRC). However, the development of improved and robust biomarkers to enable the screening, surveillance, and early detection of PLPs and CRC continues to be a challenge. The aim of this study was to identify biomarkers of progression to CRC through metabolomic profiling of human serum samples with a multistage approach. METHODS: Metabolomic profiling was conducted with the Metabolon platform for 30 CRC patients, 30 PLP patients, and 30 control subjects, and this was followed by the targeted validation of the top metabolites in an additional set of 50 CRC patients, 50 PLP patients, and 50 controls with liquid chromatography-tandem mass spectrometry. Unconditional multivariate logistic regression models, adjusted for covariates, were used to evaluate associations with PLP and CRC risk. RESULTS: For the discovery phase, 404 serum metabolites were detected, with 50 metabolites showing differential levels between CRC patients, PLP patients, and controls (P for trend < .05). After validation, the 3 top metabolites (xanthine, hypoxanthine, and d-mannose) were validated: lower levels of xanthine and hypoxanthine and higher levels of d-mannose were found in PLP and CRC cases versus controls. A further exploratory analysis of metabolic pathways revealed key roles for the urea cycle and caffeine metabolism associated with PLP and CRC risk. In addition, a joint effect of the top metabolites with smoking and a significant interaction with the body mass index were observed. An analysis of the ratio of hypoxanthine levels to xanthine levels indicated an association with CRC progression. CONCLUSIONS: These results suggest the potential utility of circulating metabolites as novel biomarkers for the early detection of CRC. Cancer 2017;123:4066-74. © 2017 American Cancer Society.

Development and evaluation of a hydrophilic interaction liquid chromatography-MS/MS method to quantify 19 nucleobases and nucleosides in rat plasma.

As essential endogenous compounds, nucleobases and nucleosides fulfill various functions in living organisms. This study presents the development and validation of a new hydrophilic interaction liquid chromatography tandem mass spectrometry method for simultaneous quantification of 19 nucleobases and nucleosides in rat plasma. For the sample preparation, 15 kinds of protein precipitants were evaluated according to the chromatographic profile and ion response of analytes. The optimization of chromatographic separation was respectively performed using reversed-phase liquid chromatography and hydrophilic interaction liquid chromatography mode; each separation mode included two test columns with different stationary phases. The chromatographic profile and parameters such as half-width (W1/2 ), capacity factor (K') and tailing factor (ft ) were used to evaluate the separation efficiencies. Furthermore, the adopted composition of two mobile phase systems and the concentrations of the additives in the optimum buffer system were also investigated. The developed method was fully validated and successfully applied quantitatively to determine 19 nucleobases and nucleosides in plasma from normal and diabetic nephropathy (DN) rats. Significant differences between normal and DN rats were found in plasma levels of cytosine, xanthine, thymidine, adenosine, guanosine, inosine and 8-hydroxy-2'-deoxyguanosine. This information may provide a useful reference for the discovery of potential biomarkers of DN.

Mouse model for molybdenum cofactor deficiency type B recapitulates the phenotype observed in molybdenum cofactor deficient patients.

Molybdenum cofactor (MoCo) deficiency is a rare, autosomal-recessive disorder, mainly caused by mutations in MOCS1 (MoCo deficiency type A) or MOCS2 (MoCo deficiency type B) genes; the absence of active MoCo results in a deficiency in all MoCo-dependent enzymes. Patients with MoCo deficiency present with neonatal seizures, feeding difficulties, severe developmental delay, brain atrophy and early childhood death. Although substitution therapy with cyclic pyranopterin monophosphate (cPMP) has been successfully used in both Mocs1 knockout mice and in patients with MoCo deficiency type A, there is currently no Mocs2 knockout mouse and no curative therapy for patients with MoCo deficiency type B. Therefore, we generated and characterized a Mocs2-null mouse model of MoCo deficiency type B. Expression analyses of Mocs2 revealed a ubiquitous expression pattern; however, at the cellular level, specific cells show prominent Mocs2 expression, e.g., neuronal cells in cortex, hippocampus and brainstem. Phenotypic analyses demonstrated that Mocs2 knockout mice failed to thrive and died within 11 days after birth. None of the tested MoCo-dependent enzymes were active in Mocs2-deficient mice, leading to elevated concentrations of purines, such as hypoxanthine and xanthine, and non-detectable levels of uric acid in the serum and urine. Moreover, elevated concentrations of S-sulfocysteine were measured in the serum and urine. Increased levels of xanthine resulted in bladder and kidney stone formation, whereas increased concentrations of toxic sulfite triggered neuronal apoptosis. In conclusion, Mocs2-deficient mice recapitulate the severe phenotype observed in humans and can now serve as a model for preclinical therapeutic approaches for MoCo deficiency type B.

The Mechanism of False in Vitro Elevation of Uric Acid Level in Mouse Blood.

Thirty minutes incubation at room temperature elevates the uric acid (UA) level of mouse blood in a test tube, and has previously been reported as "false in vitro elevation of the uric acid level." However the UA level of human blood does not elevate using the same incubation. We clarified the mechanism of the false in vitro UA elevation using mice with highly active hypoxanthine phosphoribosyl transferase (Hprt) of B6-ChrXC(MSM), a consomic mouse strain with the chromosome portion of Mus musculus morocinus in the Hprt gene site, or mice with a targeted deletion of the urate oxidase gene (Uox) (Uox-knockout (KO)). The plasma levels of UA, hypoxanthine, and xanthine, determined by HPLC, were compared with those of C57BL/6J laboratory mice used as controls. The uric acid level of Uox-KO mice was approximately 10 times higher than that of control, did not elevated after incubation in the test tube. With allopurinol, the hypoxanthine levels of B6-ChrXC(MSM) and Uox-KO were significantly lower than that of controls. Without allopurinol, the UA and xanthine levels of B6-ChrXC(MSM) were significantly lower than those of C57BL/6J controls. Even with allopurinol, the UA and xanthine levels were still significantly lower than that of controls. In conclusion, "false in vitro elevation of uric acid level" seems to be caused by low levels of erythrocyte HPRT activity and the low plasma uric acid level of laboratory mice.

Modeling and Simulation for Estimating the Influence of Renal Dysfunction on the Hypouricemic Effect of Febuxostat in Hyperuricemic Patients Due to Overproduction or Underexcretion of Uric Acid.

Whether renal dysfunction influences the hypouricemic effect of febuxostat, a xanthine oxidase (XO) inhibitor, in patients with hyperuricemia due to overproduction or underexcretion of uric acid (UA) remains unclear. We aimed to address this question with a modeling and simulation approach. The pharmacokinetics (PK) of febuxostat were analyzed using data from the literature. A kinetic model of UA was retrieved from a previous human study. Renal UA clearance was estimated as a function of creatinine clearance (CLcr) but non-renal UA clearance was assumed constant. A reversible inhibition model for bovine XO was adopted. Integrating these kinetic formulas, we developed a PK-pharmacodynamic (PK-PD) model for estimating the time course of the hypouricemic effect of febuxostat as a function of baseline UA level, febuxostat dose, treatment duration, body weight, and CLcr. Using the Monte Carlo simulation method, we examined the performance of the model by comparing predicted UA levels with those reported in the literature. We also modified the models for application to hyperuricemia due to UA overproduction or underexcretion. Thirty-nine data sets comprising 735 volunteers or patients were retrieved from the literature. A good correlation was observed between the hypouricemic effects of febuxostat estimated by our PK-PD model and those reported in the articles (observed) (r=0.89, p<0.001). The hypouricemic effect was estimated to be augmented in patients with renal dysfunction irrespective of the etiology of hyperuricemia. While validation in clinical studies is needed, the modeling and simulation approach may be useful for individualizing febuxostat doses in patients with various clinical characteristics.

Integrated metabolomic profiling of hepatocellular carcinoma in hepatitis C cirrhosis through GC/MS and UPLC/MS-MS.

BACKGROUND & AIMS: The metabolic pathway disturbances associated with hepatocellular carcinoma (HCC) remain unsatisfactorily characterized. Determination of the metabolic alterations associated with the presence of HCC can improve our understanding of the pathophysiology of this cancer and may provide opportunities for improved disease monitoring of patients at risk for HCC development. To characterize the global metabolic alterations associated with HCC arising from hepatitis C (HCV)-associated cirrhosis using an integrated non-targeted metabolomics methodology employing both gas chromatography/mass spectrometry (GC/MS) and ultrahigh-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC/MS-MS). METHODS: The global serum metabolomes of 30 HCC patients, 27 hepatitis C cirrhosis disease controls and 30 healthy volunteers were characterized using a metabolomics approach that combined two metabolomics platforms, GC/MS and UPLC/MS-MS. Random forest, multivariate statistics and receiver operator characteristic analysis were performed to identify the most significantly altered metabolites in HCC patients vs. HCV-cirrhosis controls and which therefore exhibited a close association with the presence of HCC. RESULTS: Elevated 12-hydroxyeicosatetraenoic acid (12-HETE), 15-HETE, sphingosine, γ-glutamyl oxidative stress-associated metabolites, xanthine, amino acids serine, glycine and aspartate, and acylcarnitines were strongly associated with the presence of HCC. Elevations in bile acids and dicarboxylic acids were highly correlated with cirrhosis. CONCLUSIONS: Integrated metabolomic profiling through GC/MS and UPLC/MS-MS identified global metabolic disturbances in HCC and HCV-cirrhosis. Aberrant amino acid biosynthesis, cell turnover regulation, reactive oxygen species neutralization and eicosanoid pathways may be hallmarks of HCC. Aberrant dicarboxylic acid metabolism, enhanced bile acid metabolism and elevations in fibrinogen cleavage peptides may be signatures of cirrhosis.

[Effect of concomitant chronic kidney disease on the xanthine metabolism in patients with chronic heart failure].

It is believed that patients with decreased glomerular filtration rate have stronger association between serum uric acid levels and increased risk of cardіоvascular disease. However, it is unclear whether the presence of concomitant chronic kidney disease modifies the xanthine metabolism. The aim of this study was to examine xanthine metabolism violations in chronic heart failure (CHF) patients with concomitant chronic kidney disease (CKD), and evaluate its impact on uric acid levels and xanthine oxidase activity. The study population consisted of 112 patients, aged 72,5±0,98 years. The main group of patients consisted of 72 within CKD patients and the comparison group - of 40 non-CKD participants. We noted high and almost equal detection of xanthine metabolism violations in CHF patients with CKD as well as in non-CKD patients. This data indicate greater severity of the xanthine metabolism violations in patients with concomitant CKD.

Hypoxanthine as a predictor of performance in highly trained athletes.

Purine metabolism reflects the exercise-induced muscle adaptations and training status. This study evaluated the utility of plasma hypoxanthine in the prediction of actual sport performance. We studied male athletes: 28 triathletes (21.4±2.9 years), 12 long-distance runners (23.2±1.9 years), 13 middle-distance runners (22.9±1.8 years) and 18 sprinters (22.0±2.7 years). Season-best race times were considered, achieved over standard triathlon, 5 000 m, 1 500 m and 100 m, respectively. Incremental treadmill test was administered to determine maximum and "threshold" oxygen uptake. Resting and post-exercise plasma concentrations of hypoxanthine, xanthine, uric acid and lactate were measured as well as resting erythrocyte hypoxanthine-guanine phosphoribosyltransferase activity. Simple and multiple regression analyses were used to identify significant contributors to the variance in performance. Hypoxanthine considered alone explained more variance in triathletes, long-distance runners, middle-distance runners and sprinters (r 2=0.81, 0.81, 0.88 and 0.78, respectively) than models based on aerobic capacity and lactate (R 2=0.51, 0.37, 0.59 and 0.31, respectively). Combining purine metabolites and cardiorespiratory variables resulted in the best prediction (R 2=0.86, 0.93, 0.93 and 0.91; r=0.93, 0.96, 0.96 and 0.95, respectively). In summary, hypoxanthine is a strong predictor of performance in highly trained athletes and its prediction ability is very high regardless of sport specialization, spanning the continuum from speed-power to endurance disciplines.

Analysis of purine metabolites in maternal serum for evaluating the risk of gestosis.

Metabolome analysis of the serum from pregnant patients aimed at detection of low-molecular-weight biomarkers of gestation process disorders indicated a relationship between the metabolic profile of maternal serum and risk of gestosis. In women with pre-eclampsia or preterm delivery, analysis of serum purine metabolites revealed changes in the metabolite concentrations, associated with pregnancy complications.