Plasma concentrations and urinary excretion of purine bases (uric acid, hypoxanthine, and xanthine) and oxypurinol after rigorous exercise

Exercise and hyperuricemia: an opinion article

Hyperuricaemia (HUA) is an abnormally high concentration of serum urate caused by either an excess of uric acid production or decreased excretion capacity in the body. Serum urate concentration forms sodium salts that deposit in the soft tissues of the joints, ultimately leading to gout. Additionally, HUA is strongly associated with several acute and chronic illnesses. In various clinical guidelines and practices, xanthine oxidase inhibitors, such as allopurinol and febuxostat, are commonly used as the initial medication for treating HUA. However, extended usage of urate-lowering drugs may have risks, including cardiovascular thrombotic events and hepatic impairment. Implementing a scientifically informed fitness diet in conjunction with appropriate exercise may decrease HUA. Unfortunately, there is currently a shortfall in exercise intervention trials for individuals suffering from HUA. Most of the previous evidence suggesting that exercise improves serum urate levels comes from intervention trials in other populations, and serum urate is only one of the outcomes observed. This opinion article analyses the causes of HUA, offers dietary and exercise guidance with the aim of furnishing a point of reference for individuals with HUA or fitness enthusiasts.

Nonlinear dose-response association of moderate-to-vigorous physical activity with hyperuricemia in US adults: NHANES 2007-2018

BACKGROUND

The relationship between physical activity and hyperuricemia (HUA) remains inconsistent, and the dose-response association between moderate-to- vigorous physical activity (MVPA) level and HUA still unclear. In this study, we aimed to investigate the dose-response association of MVPA with HUA, and to explore an appropriate range of MVPA level for preventing HUA.

METHODS

Data from the US National Health and Nutrition Examination Survey (NHANES) 2007-2018 were used, including 28740 non-gout adult Americans. MVPA level was self-reported using the Global Physical Activity Questionnaire and serum uric acid was measured using timed endpoint method. The dose-response relationship between MVPA level and HUA was modeled with restricted cubic spline analysis. Logistic regression analysis were applied to estimate odd ratios (ORs) and 95% confidence intervals (CIs) of the relationships between MVPA level and HUA.

RESULTS

A total of 28740 adults were included in the study (weighted mean age, 47.3 years; 46.5% men), with a prevalence rate of HUA was 17.6%. The restricted cubic spline functions depicted a general U-shaped relationship between MVPA level and HUA. The MVPA level of 933 and 3423 metabolic equivalent (MET) -min/wk were the cut-off discriminating for the risk of HUA. Participants with MVPA levels in the range of 933-3423 MET-min/wk had lower risk of HUA and they had the lowest risk when MVPA levels at around 1556 MET-min/wk. Compared with the moderate-activity group (600-2999 Met-min/wk), the low-activity group (< 600 Met-min/wk) had a greater risk of HUA (OR, 1.13 [95%CI, 1.02-1.26]) after fully adjusting for potential confounders.

CONCLUSIONS

Compared with the moderate MVPA level, the low MVPA level was associated with the higher risk of HUA. And there may be a U-shaped dose-response relationship between MVPA level and HUA. When MVPA level was approximately 933-3423 MET-min/wk, the risk of HUA may at a lower level and the risk reached the lowest when MVPA level at around 1556 MET-min/wk.

Association between serum uric acid and cardiovascular fitness among US adults: A cross-sectional study

Background

While serum uric acid (SUA) is known as a cardiovascular disease risk factor and is associated with increased cardiovascular mortality, the relationship between SUA and cardiovascular adaptability under exercise stress remains unclear.

Aims

This study aims to elucidate the relationship between SUA levels and cardiovascular fitness, particularly as manifested during cardiopulmonary exercise testing.

Methods

Utilizing data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004, this study included 5765 participants aged 12-49 years. Heart rate recovery (HRR) during cardiopulmonary exercise testing was measured as an indicator of cardiovascular fitness. Multivariate linear regression analysis was used to explore the association between SUA levels and heart rate recovery at 1 min (HRR1) and 2 min (HRR2) post-exercise.

Results

After adjusting for potential confounders, an inverse relationship was found between SUA levels and both HRR1 and HRR2. Multivariate adjusted smoothing spline plots demonstrated a decrease in HRR1 and HRR2 with increasing SUA levels. This negative correlation was observed across nearly all subgroups.

Conclusions

Elevated SUA levels are indicative of poorer cardiovascular adaptability in the adult US population.

Seasonal variations for newly prescribed urate-lowering drugs for asymptomatic hyperuricemia and gout in Japan

Background: Urate-lowering drugs (ULDs) have been approved for treatment of asymptomatic hyperuricemia and gout in Japan. Although serum urate levels and rates of gout onset are known to have seasonal variations, no survey results regarding the seasonality of ULD prescriptions for asymptomatic hyperuricemia and gout have been reported. Methods: A large-scale database of medical claims in Japan filed between January 2019 and December 2022 was accessed. In addition to total size of the recorded population for each month examined, the numbers of patients every month with newly prescribed ULDs for asymptomatic hyperuricemia and gout were noted, based on the International Classification of Diseases, 10th Revision, codes E79.0 and M10. Results: The results identified 201,008 patients with newly prescribed ULDs (median age 49.0 years, male 95.6%). Of those, 64.0% were prescribed ULDs for asymptomatic hyperuricemia and 36.0% for gout. The proportion of new ULD prescriptions was seasonal, with that significantly (p < 0.001) higher in summer (June-August) [risk ratio (RR) 1.322, 95% CI 1.218 to 1.436] and autumn (September-November) (RR 1.227, 95% CI 1.129-1.335) than in winter (December-February), whereas the proportion in spring (March-May) was not significantly different from winter. There was no significant difference after stratification by drug type (uric acid production inhibitor/uricosuric agent) or size of the medical institution, nor subgrouping by age or sex (p for interaction = 0.739, 0.727, 0.886, and 0.978, respectively). On the other hand, the proportions of new ULD prescriptions for asymptomatic hyperuricemia were significantly lower and for gout significantly higher in spring than winter, while those were similar in summer and autumn for both groups (p for interaction<0.001). Conclusion: The present findings indicate that new prescriptions for ULDs to treat asymptomatic hyperuricemia or gout in Japan show seasonal differences, with higher rates noted in summer and autumn as compared to winter.

Modulation of host glutamine anabolism enhances the sensitivity of small cell lung cancer to chemotherapy

Small cell lung cancer (SCLC) is one of the deadliest human cancers, with a 5-year survival rate of ∼7%. Here, we performed a targeted proteomics analysis of human SCLC samples and thereby identified hypoxanthine phosphoribosyltransferase 1 (HPRT1) in the salvage purine synthesis pathway as a factor that contributes to SCLC malignancy by promoting cell survival in a glutamine-starved environment. Inhibition of HPRT1 by 6-mercaptopurine (6-MP) in combination with methotrexate (MTX), which blocks the de novo purine synthesis pathway, attenuated the growth of SCLC in mouse xenograft models. Moreover, modulation of host glutamine anabolism with the glutamine synthetase inhibitor methionine sulfoximine (MSO) in combination with 6-MP and MTX treatment resulted in marked tumor suppression and prolongation of host survival. Our results thus suggest that modulation of host glutamine anabolism combined with simultaneous inhibition of the de novo and salvage purine synthesis pathways may be of therapeutic benefit for SCLC.

Surface-Enhanced Raman Analysis of Uric Acid and Hypoxanthine Analysis in Fractionated Bodily Fluids

In recent years, the disease burden of hyperuricemia has been increasing, especially in high-income countries and the economically developing world with a Western lifestyle. Abnormal levels of uric acid and hypoxanthine are associated with many diseases, and therefore, to demonstrate improved methods of uric acid and hypoxanthine detection, three different bodily fluids were analysed using surface-enhanced Raman spectroscopy (SERS) and high-performance liquid chromatography (HPLC). Gold nanostar suspensions were mixed with series dilutions of uric acid and hypoxanthine, 3 kDa centrifugally filtered human blood serum, urine and saliva. The results show that gold nanostars enable the quantitative detection of the concentration of uric acid and hypoxanthine in the range 5-50 μg/mL and 50-250 ng/mL, respectively. The peak areas of HPLC and maximum peak intensity of SERS have strongly correlated, notably with the peaks of uric acid and hypoxanthine at 1000 and 640 cm^-1, respectively. The r² is 0.975 and 0.959 for uric acid and hypoxanthine, respectively. Each of the three body fluids has a number of spectral features in common with uric acid and hypoxanthine. The large overlap of the spectral bands of the SERS of uric acid against three body fluids at spectra peaks were at 442, 712, 802, 1000, 1086, 1206, 1343, 1436 and 1560 cm^-1. The features at 560, 640, 803, 1206, 1290 and 1620 cm^-1 from hypoxanthine were common to serum, saliva and urine. There is no statistical difference between HPLC and SERS for determination of the concentration of uric acid and hypoxanthine (p > 0.05). For clinical applications, 3 kDa centrifugal filtration followed by SERS can be used for uric acid and hypoxanthine screening is, which can be used to reveal the subtle abnormalities enhancing the great potential of vibrational spectroscopy as an analytical tool. Our work supports the hypnosis that it is possible to obtain the specific concentration of uric acid and hypoxanthine by comparing the SER signals of serum, saliva and urine. In the future, the analysis of other biofluids can be employed to detect biomarkers for the diagnosis of systemic pathologies.

Serum Metabolites Associated with Muscle Hypertrophy after 8 Weeks of High- and Low-Load Resistance Training

The mechanisms responsible for the similar muscle growth attained with high- and low-load resistance training (RT) have not yet been fully elucidated. One mechanism is related to the mechanical stimulus and the level of motor unit recruitment; another mechanism is related to the metabolic response. We investigated the electromyographic signal amplitude (sEMG) and the general metabolic response to high-load RT (HL) and low-load resistance training (LL). We measured muscle thickness by ultrasound, sEMG amplitude by electromyography, and analysis of metabolites expressed through metabolomics. No differences were observed between the HL and LL groups for metabolic response and muscle thickness. A greater amplitude of sEMG was observed in the HL group. In addition, a correlation was observed between changes in muscle thickness of the vastus lateralis muscle in the HL group and levels of the metabolites carnitine, creatine, 3-hydroxyisovalerate, phenylalanine, asparagine, creatine phosphate, and methionine. In the LL group, a correlation was observed between changes in muscle thickness of the vastus lateralis muscle and levels of the metabolites acetoacetate, creatine phosphate, and oxypurinol. These correlations seem to be related to the characteristics of activated muscle fibers, the metabolic demand of the training protocols used, and the process of protein synthesis.

The Effect of Low and Moderate Exercise on Hyperuricemia: Protocol for a Randomized Controlled Study

BACKGROUND

Hyperuricemia (HUA) is a metabolic disease by purine metabolism disorders. It is a risk factor for many chronic diseases, including diabetes, hypertension, and heart disease. Studies have shown that exercise can effectively reduce serum uric acid (SUA), but the optimal exercise dose, intensity, and mode of exercise for improving HUA have not been verified in clinical studies. Therefore, this study aims to explore the effect of different exercise intensities in improving SUA of patients with HUA.

METHODS AND ANALYSIS

A randomized, single-blind, parallel controlled trial will be conducted in this study. 186 HUA patients who meet the inclusion criteria will be randomly divided into a 1:1:1 ratio (1): control group (2), low-intensity exercise group (brisk walking, 57-63% maximum heart rate, 150 min/week, 12 months), and (3) moderate-intensity exercise group (jogging, 64-76% maximum heart rate, 150 min/week, 12 months). The three groups of subjects will receive the same health education and prohibition of high-purine diet during the intervention period. The primary outcomes will be SUA concentration, SUA concentration change (mg/dL), SUA change rate (%), and the proportion of HUA patients. Secondary outcomes will include anthropometric parameters (body weight, waist circumference, hip circumference, BMI); physiological indicators (blood pressure, grip, vital capacity, maximum oxygen); biochemical indicators (blood lipid, blood sugar, liver enzyme, creatinine, and blood urea nitrogen). Each group of patients will go through an assessment at baseline, 3rd, 6th, and 12th months.

DISCUSSION

This study will evaluate the effect of 12-month low-intensity exercise and moderate-intensity exercise on HUA patients. We hypothesize that both low-intensity and moderate-intensity exercise would improve HUA as compared with no-exercise control, and that moderate-intensity exercise would be more effective than low-intensity exercise in improving HUA. These results can provide a basis for the current physical activity guidelines for HUA's healthy lifestyle management.

ETHICS AND DISSEMINATION

This study has been approved by the Ethical Review Committee of the Shanghai University of Sport (approval number: 102772020RT005). Informed consent will be obtained from all participants or their guardians. The authors intend to submit the study findings to peer-reviewed journals or academic conferences to be published.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry, identifier ChiCTR2100042643.

Gicht – auch eine Frage des Lebensstiles

Mit steigenden Harnsäurewerten steigt das Risiko einer Gicht. Da die Harnsäure-Homöostase von zahlreichen Lebensstilfaktoren beeinflusst wird, ist das Auftreten einer Gicht fast immer auch mit der Lebensweise assoziiert. Lange schon ist bekannt, dass die Zufuhr purinreicher Lebensmittel (z. B. Fleisch, Meeresfrüchte) über vermehrte Harnsäurebildung aus exogen zugeführten Purinen zu Gichtanfällen führen kann. Auch Fruktose-haltige Getränke haben über einen vermehrten Abbau von ATP bei der Verstoffwechslung von Fruktose eine Hyperurikämie zur Folge, wogegen bei vermehrter Alkoholzufuhr und Adipositas eine verminderte renale Harnsäureausscheidung für die Hyperurikämie ursächlich ist. Einige Lebensmittel (z. B. Milch, Kaffee) scheinen einen harnsäuresenkenden Effekt zu haben und können Patienten explizit empfohlen werden. Mit Blick auf den Lebensstil spielen jedoch nicht nur Ernährungsfaktoren (Lebensmittel) eine wichtige Rolle. So kommt es beim aktuell sehr populären Heilfasten durch die entstehende Ketose und häufig gleichzeitig zu geringer Flüssigkeitszufuhr zu einer verminderten Harnsäureausscheidung über die Niere und konsekutiv Harnsäureanstieg. Auch Extremsport wie Marathon stellt aufgrund der katabolen Stoffwechsellage (Ketose) und hohen mechanischen Belastung (Mikrotraumata) bereits arthrotisch vorgeschädigter Gelenke einen Risikofaktor für das gehäufte Auftreten von Gichtanfällen dar. Patienten mit einer Hyperurikämie sollten als Basismaßnahme immer über eine mögliche Ernährungsumstellung beraten werden, zumal die Hyperurikämie eng mit dem metabolischen Syndrom assoziiert ist, häufigen Stoffwechselkrankheiten wie Diabetes mellitus, Hyperlipidämien und Adipositas, die ebenfalls durch eine Lebensstilmodifikation günstig zu beeinflussen sind. Eine manifeste (langjährige) Gicht kann allerdings durch eine alleinige Ernährungsumstellung nur selten erfolgreich behandelt werden. Der Zusammenhang zwischen Lebensstil und Gicht ist seit Jahrhunderten bekannt. Leider beschränken sich die wenigen Studien zu diesem Thema meist auf epidemiologische Erhebungen, über die in dieser Arbeit eine Übersicht gegeben werden soll.

Metabolomics profiling of plasma, urine and saliva after short term training in young professional football players in Saudi Arabia

Metabolomics profiling was carried out to observe the effect of short-term intensive physical activity on the metabolome of young Saudi professional football players. Urine, plasma and saliva were collected on 2 days pre- and post-training. An Orbitrap Exactive mass spectrometer was used to analyze the samples. A reversed-phase (RP) column was used for the analysis of non-polar plasma metabolites, and a ZIC-pHILIC column was used for the analysis of plasma, saliva and urine. mzMine was used to extract the data, and the results were modelled using Simca-P 14.1 software. There was no marked variation in the metabolite profiles between pre day 1 and 2 or between post day 1 and 2 according to principal components analysis (PCA). When orthogonal partial least squares (OPLSDA) modelling was also used, and then models could be fitted based on a total number of metabolites of 75, 16 and 32 for urine, plasma and saliva using hydrophilic interaction chromatography (HILIC) and 6 for analysis of plasma with reversed-phase (RP) chromatography respectively. The present study concludes that acylcarnitine may increase post-exercise in football players suggesting that they may burn fat rather than glucose. The levels of carnitine metabolites in plasma post-exercise could provide an important indicator of fitness.

Comparison of plasma nucleotide metabolites and amino acids pattern in patients with binge eating disorder and obesity

Binge eating disorder (BED) increasingly affects population, but the mechanisms of the disease and its biomarkers are not well characterized. Recently, plasma purines, pyrimidines, amino acid and nicotinamide metabolites profiling attracted attention in studies on pathology and biomarkers of mental disorders but has not been adequately studied in BED. Blood and plasma samples were taken from patients with adult obese with BED (n = 20) and control adult obese without BED (n = 17). Plasma samples were analyzed for nucleotides and amino acid concentrations with high-performance liquid chromatography-mass spectrometry. BED had a significantly (p < 0.05) lower uridine and hypoxanthine to creatinine ratio compared to the control group. Among the amino acids BED patients had significantly (p < 0.05) lower concentrations of glutamic acid, leucine, isoleucine and the whole branched-chain amino acids group, while the concentration of citrulline was increased. Among nicotinamide metabolites, 1-methylnicotinamide levels were significantly (p < 0.05) lower. This study highlights potential use of profiling nucleotide metabolite and amino acid pattern in BED patients that may provide information on mechanisms and potential biomarkers. However, further investigation in larger population is necessary to identify clinical correlates of the observed changes.

Uridine Metabolism and Its Role in Glucose, Lipid, and Amino Acid Homeostasis

Pyrimidine nucleoside uridine plays a critical role in maintaining cellular function and energy metabolism. In addition to its role in nucleoside synthesis, uridine and its derivatives contribute to reduction of cytotoxicity and suppression of drug-induced hepatic steatosis. Uridine is mostly present in blood and cerebrospinal fluid, where it contributes to the maintenance of basic cellular functions affected by UPase enzyme activity, feeding habits, and ATP depletion. Uridine metabolism depends on three stages: de novo synthesis, salvage synthesis pathway and catabolism, and homeostasis, which is tightly relating to glucose homeostasis and lipid and amino acid metabolism. This review is devoted to uridine metabolism and its role in glucose, lipid, and amino acid homeostasis.

Changes in Water Soluble Uremic Toxins and Urinary Acute Kidney Injury Biomarkers After 10- and 100-km Runs

Acute kidney injury (AKI) is described as a relatively common complication of exercise. In clinical practice the diagnosis of AKI is based on serum creatinine, the level of which is dependent not only on glomerular filtration rate but also on muscle mass and injury. Therefore, the diagnosis of AKI is overestimated after physical exercise. The aim of this study was to determine changes in uremic toxins: creatinine, urea, uric acid, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), trimethylamine N-oxide (TMAO) and urinary makers of AKI: albumin, neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule-1 and cystatin-C (uCyst-C) after long runs. Sixteen runners, mean age 36.7 ± 8.2 years, (2 women, 14 men) participating in 10- and 100-km races were studied. Blood and urine were taken before and after the races to assess markers of AKI. A statistically significant increase in creatinine, urea, uric acid, SDMA and all studied urinary AKI markers was observed. TMAO and ADMA levels did not change. The changes in studied markers seem to be a physiological reaction, because they were observed almost in every runner. The diagnosis of kidney failure after exercise is challenging. The most valuable novel markers which can help in post-exercise AKI diagnosis are uCyst-C and uNGAL.

Prenatal Maternal Stress from a Natural Disaster Alters Urinary Metabolomic Profiles in Project Ice Storm Participants

Prenatal stress is known to epigenetically program offspring physiology and behaviour, and may become a risk factor for adult complex diseases. To gain insight into the underlying environment-gene interactions, we used proton nuclear magnetic resonance spectroscopy to analyze urinary metabolomes of male and female adolescents who were in utero during the 1998 Quebec Ice Storm. Metabolomic profiles in adolescent groups were found to be significantly different. Higher prenatal stress exposure generated alterations in metabolic pathways involved in energy metabolism and protein biosynthesis, such as branched-chain amino acid synthesis, alanine metabolism, and ketone body metabolism. Dysregulation of energy and protein metabolism suggests an increased risk of metabolic diseases like insulin resistance, diabetes, and obesity. These findings are consistent with prior observations of physiological phenotypes from this cohort. Understanding the impact of natural disasters on health risks will provide new and improved therapeutic strategies to mitigate stress-associated adverse health outcomes. Using metabolomic biomarkers may also assist in the prediction and prevention of these adverse outcomes.

Contribution of branched-chain amino acids to purine nucleotide cycle: a pilot study

BACKGROUND/OBJECTIVES

Branched-chain amino acids (BCAAs) and purine nucleotide cycle (PNC) are both associated with energy metabolism. The purpose of this study was to explore the influences of BCAA supplementation on the PNC activity of male athletes in response to a bout of endurance running exercise.

SUBJECTS/METHODS

Twelve male athletes (20.3±1.4 years) participated in the study. Each of the athletes received 12 g of a BCAA supplement (leucine 54%, isoleucine 19% and valine 27%) per day during the study. They performed two identical 60-min running exercises (65-70% maximum heart rate reserved) before and after receiving the BCAA supplements for 15 days. In addition to body composition measurement, plasma and urinary samples were also collected. Plasma samples were examined for the concentrations of glucose, lactate, BCAAs, alanine, glutamine, aspartate, hypoxanthine and uric acid. Urinary samples were examined for the concentrations of urea nitrogen, hydroxyproline, 3-methylhistidine and creatinine.

RESULTS

Body composition and the concentrations of urinary metabolites were not affected by BCAA supplementation, whereas clearance of plasma lactate after recovery from exercise was enhanced by BCAA supplementation (P<0.05). Plasma aspartate concentration was increased (P<0.05), whereas plasma glutamine, hypoxanthine and uric acid concentrations were decreased (P<0.05) by BCAA supplementation.

CONCLUSIONS

The findings suggest that BCAA supplements not only provided additional substrate to meet the energy demands of the athletes during endurance exercise but also reduced their PNC activity, and subsequently decreased uric acid production and reduced the incidence of gout in a person engaging in endurance exercise.

Serum metabolite profiles of postoperative fatigue syndrome in rat following partial hepatectomy

Postoperative fatigue syndrome is a general complication after surgery. However, there is no ‘‘gold standard’’ for fatigue assessment due to the lack of objective biomarkers. In this study, a rodent model of postoperative fatigue syndrome based on partial hepatectomy was firstly established and serum metabonomic method based on ultra-high performance liquid chromatography coupled with Q-TOF mass spectrometry was applied. Partial least-squares discriminant analysis was used to identify the differential metabolites in 70% partial hepatectomy rats relative to sham rats and 30% partial hepatectomy rats, which showed 70% partial hepatectomy group was significantly distinguishable from 30% partial hepatectomy group and sham group. Eighteen serum metabolites responsible for the discrimination were identified. The levels of hypoxanthine, kynurenine, tryptophan, uric acid, phenylalanine, palmitic acid, arachidonic acid and oleic acid showed progressive elevation from sham group to 30% partial hepatectomy group to 70% partial hepatectomy group, and levels of valine, tyrosine, isoleucine, linoleyl carnitine, palmitoylcarnitine, lysophosphatidylcholine (16:0), lysophosphatidylcholine (20:3), citric acid, succinic acid and hippuric acid showed progressive declining trend from sham group to 30% partial hepatectomy group to 70% partial hepatectomy group. These potential biomarkers help to understand of etiology, pathophysiology and treatment of postoperative fatigue syndrome.

Individual variability in human blood metabolites identifies age-related differences

Metabolites present in human blood document individual physiological states influenced by genetic, epigenetic, and lifestyle factors. Using high-resolution liquid chromatography-mass spectrometry (LC-MS), we performed nontargeted, quantitative metabolomics analysis in blood of 15 young (29 ± 4 y of age) and 15 elderly (81 ± 7 y of age) individuals. Coefficients of variation (CV = SD/mean) were obtained for 126 blood metabolites of all 30 donors. Fifty-five RBC-enriched metabolites, for which metabolomics studies have been scarce, are highlighted here. We found 14 blood compounds that show remarkable age-related increases or decreases; they include 1,5-anhydroglucitol, dimethyl-guanosine, acetyl-carnosine, carnosine, ophthalmic acid, UDP-acetyl-glucosamine,N-acetyl-arginine,N6-acetyl-lysine, pantothenate, citrulline, leucine, isoleucine, NAD(+), and NADP(+) Six of them are RBC-enriched, suggesting that RBC metabolomics is highly valuable for human aging research. Age differences are partly explained by a decrease in antioxidant production or increasing inefficiency of urea metabolism among the elderly. Pearson's coefficients demonstrated that some age-related compounds are correlated, suggesting that aging affects them concomitantly. Although our CV values are mostly consistent with those CVs previously published, we here report previously unidentified CVs of 51 blood compounds. Compounds having moderate to high CV values (0.4-2.5) are often modified. Compounds having low CV values, such as ATP and glutathione, may be related to various diseases because their concentrations are strictly controlled, and changes in them would compromise health. Thus, human blood is a rich source of information about individual metabolic differences.

Identified metabolic signature for assessing red blood cell unit quality is associated with endothelial damage markers and clinical outcomes

BACKGROUND

There has been interest in determining whether older red blood cell (RBC) units have negative clinical effects. Numerous observational studies have shown that older RBC units are an independent factor for patient mortality. However, recently published randomized clinical trials have shown no difference of clinical outcome for patients receiving old or fresh RBCs. An overlooked but essential issue in assessing RBC unit quality and ultimately designing the necessary clinical trials is a metric for what constitutes an old or fresh RBC unit.

STUDY DESIGN AND METHODS

Twenty RBC units were profiled using quantitative metabolomics over 42 days of storage in SAGM with 3- to 4-day time intervals. Metabolic pathway usage during storage was assessed using systems biology methods. The detected time intervals of the metabolic states were compared to clinical outcomes.

RESULTS

Using multivariate statistics, we identified a nonlinear decay process exhibiting three distinct metabolic states (Days 0-10, 10-17, and 17-42). Hematologic variables traditionally measured in the transfusion setting (e.g., pH, hemolysis, RBC indices) did not distinguish these three states. Systemic changes in pathway usage occurred between the three states, with key pathways changing in both magnitude and direction. Finally, an association was found between the time periods of the metabolic states with the clinical outcomes of more than 280,000 patients in the country of Denmark transfused over the past 15 years and endothelial damage markers in healthy volunteers undergoing autologous transfusions.

CONCLUSION

The state of RBC metabolism may be a better indicator of cellular quality than traditional hematologic variables.

Metabolomics reveals hippocampal metabolic fluctuations of postoperative fatigue syndrome and anti-fatigue effect of Carthamus tinctorius L extract in rat model

Postoperative fatigue syndrome (POFS) is a common clinical complication followed by almost every major abdominal surgery. There is not a full explanation to the etiology of POFS, especially its central mechanism. Carthamus tinctorius L is a classic traditional Chinese medicine (TCM) which could exert the anti-fatigue effect on POFS. However, its mechanism is still lacking. Here, ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOFMS) based metabonomic approach was used to characterize hippocampal metabolic fluctuations of POFS in a rat model induced by partial hepatectomy (PHx), and to evaluate the anti-fatigue effect of Carthamus tinctorius L extract (CTLE). With partial least-squares discriminant analysis for classification and selection of biomarkers, fifteen hippocampal metabolites related to POFS were identified, primarily involving alanine, aspartate and glutamate metabolism, valine, leucine and isoleucine degradation, purine metabolism, phenylalanine metabolism, tryptophan metabolism, phospholipid metabolism and fatty acid metabolism. With these altered metabolic pathways as possible drug targets, we systematically analyzed the protective effect of CTLE, which showed that CTLE could provide anti-fatigue effect on POFS through partially regulating the perturbed metabolic pathways. This study indicated that UHPLC-Q-TOFMS-based metabolomics provided a powerful tool to reveal hippocampal metabolic fluctuations of POFS and study the mechanism of TCM. This article is protected by copyright. All rights reserved.

Nonpharmacological Management of Gout and Hyperuricemia: Hints for Better Lifestyle

We reviewed lifestyle factors that influence serum uric acid levels and risk of gout flare, and how to improve their deleterious effects. Since obesity increases uric acid and weight gain increases gout risk, weight reduction by daily exercise and limiting intake of excess calories is recommended. However, strenuous exercise, which causes adenine nucleotide degradation; starvation, which decreases uric acid excretion; and dehydration may raise the level of uric acid in serum and trigger gout. Increased intake of purine-rich foods, such as meat and seafood, raise the level of uric acid in serum and is associated with increased risk of gout, whereas dairy products, especially low-fat types, are associated with a lower risk of gout. Also, heavy alcohol drinking raises the uric acid level and increases the risk of gout through adenine nucleotide degradation and lactate production. Sweet fruits and soft drinks containing fructose should be moderated, since fructose may raise uric acid and increase gout risk through uric acid production and/or decreased excretion. On the other hand, the Mediterranean diet is recommended for gout patients, since it may also help prevent hyperuricemia. Furthermore, coffee and vitamin C supplementation could be considered as preventive measures, as those can lower serum uric acid levels as well as the risk of gout.

Whey protein hydrolysate enhances the exercise-induced heat shock protein (HSP70) response in rats

Whey protein has been suggested to be potential protective agent against various forms of stress. The heat shock protein HSP70 confers greater cellular tolerance against stressors. The present study evaluated the effects of whey protein intake on HSP70 expression. Forty-eight male Wistar rats were divided into sedentary and exercised groups, and each group was fed as a protein source casein (CAS), whey protein (WP) or whey protein hydrolysate (WPH) for 3weeks. Exercise on a treadmill was used as the source of stress in the animals from the exercised group. The results showed a larger increase in HSP70 expression in the soleus, gastrocnemius and lung of the WPH-fed rats than WP or casein-fed rats. HSP70 expression in the sedentary rats was very low, independent of the diet or tissue. Protein carbonyls were lower in the group that consumed WPH. These data suggest that the consumption of WPH enhances HSP70 expression.

Allopurinol reduces antigen-specific and polyclonal activation of human T cells

Allopurinol is the most popular commercially available xanthine oxidase inhibitor and it is widely used for treatment of symptomatic hyperuricaemia, or gout. Although, several anti-inflammatory actions of allopurinol have been demonstrated in vivo and in vitro, there have been few studies on the action of allopurinol on T cells. In the current study, we have assessed the effect of allopurinol on antigen-specific and mitogen-driven activation and cytokine production in human T cells. Allopurinol markedly decreased the frequency of IFN-γ and IL-2-producing T cells, either after polyclonal or antigen-specific stimulation with Herpes Simplex virus 1, Influenza (Flu) virus, tetanus toxoid and Trypanosoma cruzi-derived antigens. Allopurinol attenuated CD69 upregulation after CD3 and CD28 engagement and significantly reduced the levels of spontaneous and mitogen-induced intracellular reactive oxygen species in T cells. The diminished T cell activation and cytokine production in the presence of allopurinol support a direct action of allopurinol on human T cells, offering a potential pharmacological tool for the management of cell-mediated inflammatory diseases.

Alterations in purine metabolism in middle-aged elite, amateur, and recreational runners across a 1-year training cycle

Changes in purine derivatives may be considered as signs of training-induced metabolic adaptations. The purpose of this study was to assess the effect of a 1-year training cycle on the response of hypoxanthine (Hx) concentration and Hx-guanine phosphoribosyltransferase (HGPRT) activity. Three groups of middle-aged male runners were examined: 11 elite master runners (EL; 46.0 ± 3.8 years), 9 amateur runners (AM; 45.1 ± 4.7 years), and 10 recreational runners (RE; 45.9 ± 6.1 years). Plasma Hx concentration and erythrocyte HGPRT activity were measured in three characteristic training phases of the annual cycle. Significant differences in post-exercise Hx concentration and resting HGPRT activity were demonstrated between the EL, AM, and RE groups across consecutive training phases. The EL group showed lowest Hx concentration and highest HGPRT activity compared to the AM and RE groups. Analogous differences were observed between the AM and RE groups during specific preparation. For the EL group, the changes were observed across all examinations and the lowest Hx concentration and highest HGPRT activity were found in the competition phase. Significant change was also revealed in the AM group between the general and specific preparation, but not in the competition phase. No significant changes were found in the RE runners who did not use anaerobic exercise in their training. In conclusion, a long-lasting endurance training, incorporating high-intensity exercise, results in significant changes in purine metabolism, whereas training characterized by constant low-intensity exercise does not. Plasma Hx concentration and erythrocyte HGPRT activity may be sensitive indicators of training adaptation and training status in middle-aged athletes.

Effects of acute creatine supplementation on iron homeostasis and uric acid-based antioxidant capacity of plasma after wingate test

Background

Dietary creatine has been largely used as an ergogenic aid to improve strength and athletic performance, especially in short-term and high energy-demanding anaerobic exercise. Recent findings have also suggested a possible antioxidant role for creatine in muscle tissues during exercise. Here we evaluate the effects of a 1-week regimen of 20 g/day creatine supplementation on the plasma antioxidant capacity, free and heme iron content, and uric acid and lipid peroxidation levels of young subjects (23.1 ± 5.8 years old) immediately before and 5 and 60 min after the exhaustive Wingate test.

Results

Maximum anaerobic power was improved by acute creatine supplementation (10.5 %), but it was accompanied by a 2.4-fold increase in pro-oxidant free iron ions in the plasma. However, potential iron-driven oxidative insult was adequately counterbalanced by proportional increases in antioxidant ferric-reducing activity in plasma (FRAP), leading to unaltered lipid peroxidation levels. Interestingly, the FRAP index, found to be highly dependent on uric acid levels in the placebo group, also had an additional contribution from other circulating metabolites in creatine-fed subjects.

Conclusions

Our data suggest that acute creatine supplementation improved the anaerobic performance of athletes and limited short-term oxidative insults, since creatine-induced iron overload was efficiently circumvented by acquired FRAP capacity attributed to: overproduction of uric acid in energy-depleted muscles (as an end-product of purine metabolism and a powerful iron chelating agent) and inherent antioxidant activity of creatine.

Mental and physical fatigue-related biochemical alterations

OBJECTIVE

To confirm fatigue-related biochemical alterations, we measured various parameters just before and after relaxation and fatigue-inducing mental or physical sessions.

METHODS

Fifty-four healthy volunteers were randomized to perform relaxation and fatigue-inducing mental and physical sessions for 4 h in a double-blind, three-crossover design. Before and after each session, subjects were asked to rate their subjective sensations of fatigue, and blood, saliva, and urine samples were taken.

RESULTS

After the fatigue-inducing mental and physical sessions, subjective scores of fatigue were increased. After the fatigue-inducing mental session, the vanillylmandelic acid level in urine was higher and plasma valine level was lower than after the relaxation session. In contrast, after the fatigue-inducing physical session, serum citric acid, triacylglycerol, free fatty acid, ketone bodies, total carnitine, acylcarnitine, uric acid, creatine kinase, aspartate aminotransferase, lactate dehydrogenase, cortisol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, plasma branched-chain amino acids, transforming growth factor-beta1 and -beta2, white blood cell and neutrophil counts, saliva cortisol and amylase, and urine vanillylmandelic acid levels were higher and serum free carnitine and plasma total amino acids and alanine levels were lower than those after the relaxation session.

CONCLUSION

Some mental or physical fatigue-related biochemical changes were determined. Various biochemical alterations reflecting homeostatic perturbation and its responses might be shown. We believe that our results contribute to clarifying the mechanism of fatigue, developing evaluation methods, and establishing a basis for treatment.

Effects of diet, physical activity and performance, and body weight on incident gout in ostensibly healthy, vigorously active men

BACKGROUND

Physical activity and cardiorespiratory fitness are not currently recognized as factors related to preventing gout, nor are risk factors for gout in physically active men well understood.

OBJECTIVE

The objective was to identify risk factors for gout in ostensibly healthy, vigorously active men.

DESIGN

Incident self-reported gout was compared with baseline diet, body mass index (BMI; in kg/m(2)), physical activity (in km/d run), and cardiorespiratory fitness (in m/s during 10-km footrace) prospectively in 28,990 male runners.

RESULTS

Men (n = 228; 0.79%) self-reported incident gout during 7.74 y of follow-up. The risk of gout increased with higher alcohol intake [per 10 g/d; relative risk (RR): 1.19; 95% CI: 1.12, 1.26; P < 0.0001], meat consumption (per servings/d; RR: 1.45; 95% CI: 1.06, 1.92; P = 0.002), and BMI (RR: 1.19; 95% CI: 1.15, 1.23; P < 0.0001) and declined with greater fruit intake (per pieces/d; RR: 0.73; 95% CI: 0.62, 0.84; P < 0.0001), running distance (per km/d; RR: 0.92; 95% CI: 0.88, 0.97; P < 0.001), and fitness (per m/s; RR: 0.55; 95% CI: 0.41, 0.75; P < 0.0001). The RR per 10 g alcohol/d consumed as wine (1.27; P = 0.002), beer (1.19; P < 0.0001), and mixed drinks (1.13; P = 0.18) was not significantly different from each other. Men who consumed > 15 g alcohol/d had 93% greater risk than abstainers, and men who averaged > 2 pieces fruit/d had 50% less risk than those who ate < 0.5 fruit/d. Risk of gout was 16-fold greater for BMI > 27.5 than < 20. Compared with the least active or fit men, those who ran > or = 8 km/d or > 4.0 m/s had 50% and 65% lower risk of gout, respectively. Lower BMI contributed to the risk reductions associated with distance run and fitness.

CONCLUSION

These findings, based on male runners, suggest that the risk of gout is lower in men who are more physically active, maintain ideal body weight, and consume diets enriched in fruit and limited in meat and alcohol.

Effects of exercise and grape juice ingestion in combination on plasma concentrations of purine bases and uridine

BACKGROUND

Since grape juice contains considerable amounts of fructose, which may increase the plasma concentration of urate, the combination of exercise and grape juice may increase the plasma concentration of urate to a greater degree than grape juice or exercise alone.

METHODS

We performed 3 experiments with 6 healthy male Japanese. The first was exercise alone (exercise alone experiment), the second was grape juice ingestion alone (grape juice alone experiment), and the third was a combination of exercise and grape juice ingestion (combination experiment).

RESULTS

In the exercise alone experiment, the concentrations of purine bases and uridine in plasma, and lactate in blood, as well as the urinary excretion of oxypurines were increased, whereas the urinary excretion of uric acid and fractional excretion of purine bases were decreased. In the grape juice alone experiment, the concentrations of purine bases and uridine, as well as lactate in blood were increased, whereas the fractional excretion of uric acid was decreased. In the combination experiment, the concentrations of purine bases and uridine in plasma, and lactate in blood, as well as the urinary excretion of oxypurines were increased, whereas the urinary excretion of uric acid and fractional excretion of hypoxanthine, xanthine, and uric acid were decreased. The increase in plasma concentration of urate by the combination of exercise and grape juice was greater than that by each alone, though it was not significantly different from the sum of increases in those 2 experiments.

CONCLUSION

Increases in adenine nucleotide degradation and lactic acid production caused by both exercise and grape juice ingestion play an important role in the increase in plasma concentration of urate, while those in combination have an additive effect on that concentration.

Effects of sucrose on plasma concentrations and urinary excretion of purine bases

To determine whether an increase in the plasma concentration of uric acid by sucrose intake is ascribable to enhanced purine degradation and/or decreased urinary excretion of uric acid, we measured the plasma concentrations of purine bases (uric acid, hypoxanthine, and xanthine) and uridine, as well as the urinary excretion of purine bases in 7 healthy subjects before and after administering sucrose at 1.5 g/kg of body weight in 2 related experiments, with and without an administration of 300 mg of allopurinol. In addition, in the control experiment without an administration of sugar and with an administration of 300 mg of allopurinol, we measured the same parameters in those 7 subjects. Without added allopurinol, sucrose increased the plasma concentration of uric acid by 11% (P<.01) as well as that of uridine, although it did not significantly increase the plasma concentrations of hypoxanthine and xanthine or the urinary excretion of uric acid. On the other hand, the plasma concentration and urinary excretion of hypoxanthine were increased by 2.4-fold (P<.05) and 3.42-fold (P<.05), respectively, and the plasma concentration of xanthine was increased by 1.2-fold (P<.05) together with an increase in the plasma concentration of uridine in the experiment with allopurinol administration. In contrast, the plasma concentration and urinary excretion of uric acid and the urinary excretion of xanthine were not increased. In addition, in the control experiment, all parameters did not change significantly. These results indicate that purine degradation enhanced by sucrose plays a major role in the increased plasma concentration of uric acid.