Changes in the Concentration of Purine and Pyridine as a Response to Single Whole-Body Cryostimulation

To our knowledge, this is the first study in which we provide evidence that a single whole-body cryostimulation treatment leads to changes associated with erythrocyte energy metabolism. These changes are beneficial from the point of view of cellular bioenergetics, because they are associated with an increase in ATP concentration and erythrocyte energy potential expressed by an increase in the ATP/ADP and ATP/AMP ratios and the value of adenylate energy charge (AEC). In addition, as affected by cryogenic temperatures, there is a decrease in the concentration of purine catabolism products, i.e., inosine and hypoxanthine in the blood.

Пуриновый обмен у пациентов с острой хирургической патологией органов брюшной полости

Цель работы - изучение динамики активности основного фермента пуринового катаболизма ксантиноксидазы у пациентов с острой хирургической патологией органов брюшной полости в послеоперационном периоде. Методика. В клиническую группу вошли 238 больных (166 мужчин и 72 женщины) в возрасте 18-62 лет с различной острой хирургической патологией органов брюшной полости. Оценивали состояние мочекислого обмена и ПОЛ. Определяли активность ксантиноксидазы модифицированным методом J.H. Marimont, M. London. В параллельных пробах крови определяли концентрацию молекул средней массы (СМ254 и СМ280), уровень мочевины, креатинина, гемоглобина, билирубина, калия, глюкозы и общего белка, активность ферментов АлАТ и АсАТ, а также проводили подсчет количества лейкоцитов, эритроцитов, рассчитывали лейкоцитарный индекс интоксикации. Уровень малонового диальдегида определяли согласно рекомендациям A.L. Tappel, H. Lalkin, СМ254 и СМ280 - по Holloway C. и соавт. Нормой служила случайная выборка показателей, полученных при обследовании жителей Чувашской Республики. Результаты. Активность ксантиноксидазы больных при поступлении статистически значимо превышало норму. Начиная с 1-х сут после операции активность фермента возрастала, достигая максимума на 3-и сут, затем снижалась, приближаясь к 7-м сут к исходным значениям. Установлена прямая корреляция активности ксантиноксидазы с уровнем малонового диальдегида, что подтверждает сопряженность усиления пуринового катаболизма при острой хирургической патологии с активацией ПОЛ. Полученные результаты согласуются с данными авторов о вовлеченности ксантиноксидазы в продукцию свободных радикалов. Интенсификация процессов ПОЛ тесно связана с уровнем интоксикации в организме. Это доказывают выявленные нами прямые сильные корреляционные связи активности ксантиноксидазы с уровнем СМ254 и СМ280, количеством лейкоцитов и величиной лейкоцитарного индекса интоксикации. При неблагоприятном течении послеоперационного периода обнаружено 2 типа изменений активности фермента: у одних больных активность ксантиноксидазы статистически значимо повышалась, превышая исходный уровень, у других статистически значимо снижалась. Заключение. Изменение активности ксантиноксидазы при нарастании клинических признаков интоксикации, повышении лейкоцитарного индекса и уровня лейкоцитов может служить дополнительным прогностическим признаком развития послеоперационных осложнений.Introduction. Purine metabolism was studied in 238 patients aged 18 to 62 with various acute surgical pathologies of abdominal organs. The aim of the work was to study the dynamics of xanthine oxidase (XO), the major enzyme of purine catabolism, in patients with acute surgical pathology of abdominal organs in the postoperative period. Methods. The clinical group included 238 patients with various acute surgical pathologies of abdominal organs. Mean age of patients was 37.5+1.0, from 18 to 62. The group consisted of 166 males (69.7%) and 72 females (30.3%). In parallel blood samples, we measured indexes of lipid peroxidation (LP), uric acid metabolism, concentrations of middle molecules, bilirubin, alanine transaminase and aspartate transaminase, urea, creatinine, potassium, glucose, and crude protein; counted leukocytes and erythrocytes; and determined the hemoglobin value and leukocyte intoxication index (LII). XO activity was determined according to a method of J.H. Marimont and M. London modified at the Medical School of I. N. Uliyanov Chuvash State University. Concentration of malonic dialdehyde (MDA) was measured according to the recommendations of A.L. Tappel and H. Lalkin, and concentrations of middle molecules (MM254 and MM280) were measured according to C. Holloway et al. Normal values for serum concentrations of XO, MDA, MM254, and MM280 were determined using a random sample of Chuvash Republic residents. Results. Upon admission of patients, their XO activity significantly exceeded normal values. Starting from postoperative day 1, the enzyme activity increased, reached its maximum at day 3, then decreased, and approached the baseline values by day 7. A direct correlation of XO and MDA, the end product of lipid peroxidation (LP), was established, which confirmed that the increase in purine catabolism associated with acute surgical pathology is coupled with LP activation. The correlation between the increase in purine catabolism and LP activation in acute surgical pathology is consistent with multiple reports of XO involvement in free radical production. Conclusions. Intensity of LP processes is closely related to the degree of intoxication as evidences by direct, strong correlations of XO with concentrations of middle molecule 254, middle molecule 280, leukocyte count, and LII. In case of unfavorable postoperative course, two types of changes in the XO activity were identified. In some patients, the postoperative XO activity remained high significantly exceeding the normal values, whereas others had significantly decreased XO activity as compared to normal values. An increase or a sharp decrease in the XO activity with progressive clinical signs of intoxication along with increases in leukocyte count and LII can serve as an additional diagnostic sign of developing postoperative complications.

Purine Catabolism Shows a Dampened Circadian Rhythmicity in a High-fat Diet-Induced Mouse Model of Obesity

High-calorie diet, circadian rhythms and metabolic features are intimately linked. However, the mediator(s) between nutritional status, circadian rhythms and metabolism remain largely unknown. This article aims to clarify the key metabolic pathways bridging nutritional status and circadian rhythms based on a combination of metabolomics and molecular biological techniques. A mouse model of high-fat diet-induced obesity was established and serum samples were collected in obese and normal mice at different zeitgeber times. Gas chromatography/mass spectrometry, multivariate/univariate data analyses and metabolic pathway analysis were used to reveal changes in metabolism. Metabolites involved in the metabolism of purines, carbohydrates, fatty acids and amino acids were markedly perturbed in accordance with circadian related variations, among which purine catabolism showed a typical oscillation. What’s more, the rhythmicity of purine catabolism dampened in the high-fat diet group. The expressions of clock genes and metabolic enzymes in the liver were measured. The mRNA expression of Xanthine oxidase (Xor) was highly correlated with the rhythmicity of Clock, Rev-erbα and Bmal1, as well as the metabolites involved in purine catabolism. These data showed that a high-fat diet altered the circadian rhythm of metabolic pathways, especially purine catabolism. It had an obvious circadian oscillation and a high-fat diet dampened its circadian rhythmicity. It was suggested that circadian rhythmicity of purine catabolism is related to circadian oscillations of expression of Xor, Uox and corresponding clock genes.

Excess Iron Enhances Purine Catabolism Through Activation of Xanthine Oxidase and Impairs Myelination in the Hippocampus of Nursing Piglets

Background Few studies have addressed the risk of nutritional iron overexposure in infancy. We previously found that excess dietary iron in nursing piglets resulted in iron overload in the liver and hippocampus and diminished socialization with novel conspecifics in a test for social novelty preference. Objectives This experiment aimed to identify metabolites and metabolic pathways affected by iron overload in the liver and hippocampus of nursing piglets. Methods Liver and hippocampal tissues collected from 22-d-old piglets (Hampshire × Yorkshire crossbreed; 5.28 ± 0.53 kg body weight; 50% male) that received orally 0 (NI group) or 50 mg iron/(d · kg body weight) (HI group) from postnatal day (PD) 2 to PD21 were analyzed for mRNA and protein expression and enzyme activity of xanthine oxidase (XO). Untargeted metabolomics was performed using GC-MS. Expression of myelin basic protein (MBP) in the hippocampus was determined using western blot. Results There were 108 and 126 metabolites identified in the hippocampus and liver, respectively. Compared with NI, HI altered 15 metabolites (P < 0.05, q < 0.2) in the hippocampus, including a reduction in myo-inositol (0.86-fold) and N-acetylaspartic acid (0.84-fold), 2 metabolites important for neuronal function and myelination. Seven metabolites involved in purine and pyrimidine metabolism (e.g., hypoxanthine, xanthine, and β-alanine) were coordinately changed in the hippocampus (P < 0.05, q < 0.2), suggesting that iron excess enhanced purine catabolism. The mRNA expression (2.3-fold) (P < 0.05) and activity of XO, a rate-limiting enzyme in purine degradation, was increased. Excess iron increased hippocampal lipid peroxidation by 74% (P < 0.05) and decreased MBP by 44% (P = 0.053). The hepatic metabolome was unaffected. Conclusions In nursing piglets, excess iron enhances hippocampal purine degradation through activation of XO, which may induce oxidative stress and alter energy metabolism in the developing brain.

Identification of a Formate-Dependent Uric Acid Degradation Pathway inEscherichia coli

ABSTRACTPurine is a nitrogen-containing compound that is abundant in nature. In organisms that utilize purine as a nitrogen source, purine is converted to uric acid, which is then converted to allantoin. Allantoin is then converted to ammonia. InEscherichia coli, neither urate-degrading activity nor a gene encoding an enzyme homologous to the known urate-degrading enzymes had previously been found. Here, we demonstrate urate-degrading activity inE. coli. We first identifiedaegAas anE. coligene involved in oxidative stress tolerance. An examination of gene expression revealed that bothaegAand its paralogygfTare expressed under both microaerobic and anaerobic conditions. TheygfTgene is localized within a chromosomal gene cluster presumably involved in purine catabolism. Accordingly, the expression ofygfTincreased in the presence of exogenous uric acid, suggesting thatygfTis involved in urate degradation. Examination of the change of uric acid levels in the growth medium with time revealed urate-degrading activity under microaerobic and anaerobic conditions in the wild-type strain but not in theaegA ygfTdouble-deletion mutant. Furthermore, AegA- and YgfT-dependent urate-degrading activity was detected only in the presence of formate and formate dehydrogenase H. Collectively, these observations indicate the presence of urate-degrading activity inE. colithat is operational under microaerobic and anaerobic conditions. The activity requires formate, formate dehydrogenase H, and eitheraegAorygfT. We also identified other putative genes which are involved not only in formate-dependent but also in formate-independent urate degradation and may function in the regulation or cofactor synthesis in purine catabolism.IMPORTANCEThe metabolic pathway of uric acid degradation to date has been elucidated only in aerobic environments and is not understood in anaerobic and microaerobic environments. In the current study, we showed thatEscherichia coli, a facultative anaerobic organism, uses uric acid as a sole source of nitrogen under anaerobic and microaerobic conditions. We also showed that formate, formate dehydrogenase H, and either AegA or YgfT are involved in uric acid degradation. We propose that formate may act as an electron donor for a uric acid-degrading enzyme in this bacterium.

Pre-mature senescence in the oldest leaves of low nitrate-grown Atxdh1 mutant uncovers a role for purine catabolism in plant nitrogen metabolism

ABSTRACTThe nitrogen rich ureides allantoin and allantoate, are known to play a role in nitrogen delivery in Leguminosae, in addition to their role as reactive oxygen species scavengers. However, their role as a nitrogen source in non-legume plants has not been shown. Xanthine dehydrogenase1 (AtXDH1) activity is a catalytic bottleneck step in purine catabolism. Atxdh1 mutant exhibited early leaf senescence, lower soluble protein and organic-N levels as compared to wild-type (WT) older leaves when grown with 1 mM nitrate, whereas under 5mM, mutant plants were comparable to WT. Similar nitrate-dependent senescence phenotypes were evident in the older leaves of allantoinase (Ataln) and allantoate amidohydrolase (Ataah) mutants, impaired in further downstream steps of purine catabolism. Importantly, under low nitrate conditions, xanthine was accumulated in older leaves of Atxdh1, whereas allantoin in both older and younger leaves of Ataln but not in WT leaves, indicating remobilization of xanthine degraded products from older to younger leaves. Supporting this notion, ureide transporters UPS1, UPS2 and UPS5 were enhanced in older leaves of 1 mM nitrate-fed WT as compared to 5 mM. Enhanced AtXDH, AtAAH and purine catabolic transcripts, were detected in WT grown in low nitrate, indicating regulation at protein and transcript levels. Higher nitrate reductase activity in Atxdh1 than WT leaves, indicates their need for nitrate assimilation products. It is further demonstrated that the absence of remobilized purine-degraded N from older leaves is the cause for senescence symptoms, a result of higher chloroplastic protein degradation in older leaves of nitrate starved Atxdh1 plants.SummaryThe absence of remobilized purine-degraded N from older to the young growing leaves is the cause for senescence symptoms, a result of higher chloroplastic protein degradation in older leaves of nitrate starved Atxdh1 plants.

BIOCHEMICAL ROLE OF XANTHINE OXIDOREDUCTASE AND ITS NATURAL INHIBITORS: AN OVERVIEW

<p>Xanthine oxidoreductase (XOR) is a widely distributed housekeeping enzyme in mammals that catalyzes the last two steps in human purine catabolism to produce uric acid. The enzyme exists as a homodimer with independent electron transfer in each monomer. This has been studied extensively as a major constituent of the milk fat globule membrane (MFGM) which surrounds fat globules in cow's milk even though purine catabolism is the most accepted function of XOR. A huge number of literature highlights on the different catalytic forms of XOR and their importance in the generation of reactive oxygen species/reactive nitrogen species (ROS/RNS) and synthesis of uric acid which are involved in many physiological and pathological processes. However, a slight ambiguity resides in their biochemical functions. The aim of this article was to review the literature published on the structural, catalytical, physiological and pathological role of XOR and to resolve the ambiguity in biochemical processes and to firm up various natural inhibitors of XOR collectively. Uric acid, the product of purine catabolism shows antioxidant activity, and XOR-derived ROS and RNS play a role in innate immunity, milk secretion and also be involved in signaling and metabolism of xenobiotics. Furthermore, XOR is likely to be engaged in pathology because of excessive production of uric acid and ROS/RNS. This review also reports natural XOR inhibitors in plants which inhibit the enzyme to treat XOR associated pathology.</p>