Artykuły w czasopismach na temat „Physiological oxidation”
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Tardo-Dino, Pierre-Emmanuel, Julianne Touron, Stéphane Baugé, Stéphanie Bourdon, Nathalie Koulmann i Alexandra Malgoyre. "The effect of a physiological increase in temperature on mitochondrial fatty acid oxidation in rat myofibers". Journal of Applied Physiology 127, nr 2 (1.08.2019): 312–19. http://dx.doi.org/10.1152/japplphysiol.00652.2018.
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We investigated the effect of temperature increase on mitochondrial fatty acid (FA) and carbohydrate oxidation in the slow-oxidative skeletal muscles (soleus) of rats. We measured mitochondrial respiration at 35°C and 40°C with the physiological substrates pyruvate + 4 mM malate (Pyr) and palmitoyl-CoA (PCoA) + 0.5 mM malate + 2 mM carnitine in permeabilized myofibers under nonphosphorylating ([Formula: see text]) or phosphorylating ([Formula: see text]) conditions. Mitochondrial efficiency was calculated by the respiratory control ratio (RCR = [Formula: see text]/[Formula: see text]). We used guanosine triphosphate (GTP), an inhibitor of uncoupling protein (UCP), to study the mechanisms responsible for alterations of mitochondrial efficiency. We measured hydrogen peroxide (H2O2) production under nonphosphorylating and phosphorylating conditions at both temperatures and substrates. We studied citrate synthase (CS) and 3-hydroxyl acyl coenzyme A dehydrogenase (3-HAD) activities at both temperatures. Elevating the temperature from 35°C to 40°C increased PCoA-[Formula: see text] and decreased PCoA-RCR, corresponding to the uncoupling of oxidative phosphorylation (OXPHOS). GTP blocked the heat-induced increase of PCoA-[Formula: see text]. Rising temperature moved toward a Pyr-[Formula: see text] increase, without significance. Heat did not alter H2O2 production, resulting from either PCoA or Pyr oxidation. Heat induced an increase in 3-HAD but not in CS activities. In conclusion, heat induced OXPHOS uncoupling for PCoA oxidation, which was at least partially mediated by UCP and independent of oxidative stress. The classically described heat-induced glucose shift may actually be mostly due to a less efficient FA oxidation. These findings raise questions concerning the consequences of heat-induced alterations in mitochondrial efficiency of FA metabolism on thermoregulation. NEW & NOTEWORTHY Ex vivo exposure of skeletal myofibers to heat uncouples substrate oxidation from ADP phosphorylation, decreasing the efficiency of mitochondria to produce ATP. This heat effect alters fatty acids (FAs) more than carbohydrate oxidation. Alteration of FA oxidation involves uncoupling proteins without inducing oxidative stress. This alteration in lipid metabolism may underlie the preferential use of carbohydrates in the heat and could decrease aerobic endurance.
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Kelley, D. E., J. P. Reilly, T. Veneman i L. J. Mandarino. "Effects of insulin on skeletal muscle glucose storage, oxidation, and glycolysis in humans". American Journal of Physiology-Endocrinology and Metabolism 258, nr 6 (1.06.1990): E923—E929. http://dx.doi.org/10.1152/ajpendo.1990.258.6.e923.
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The effects of physiological hyperinsulinemia (approximately 75 mU/l) on glucose storage, oxidation, and glycolysis in skeletal muscle were assessed with euglycemic clamps performed in seven healthy volunteers, in conjunction with leg balance for glucose, lactate, alanine, O2, and CO2. Infusion of insulin increased leg glucose uptake, storage, and oxidation but did not alter net release of lactate and alanine. The respiratory quotient (RQ) across the leg increased from a basal value of 0.74 +/- 0.02 to 0.99 +/- 0.02 during hyperinsulinemia. Under conditions of insulin stimulation, 49 +/- 5% of leg glucose uptake was stored, 37 +/- 4% was oxidized, and 14 +/- 2% was released as lactate and alanine. We conclude that during physiological hyperinsulinemia and euglycemia 1) skeletal muscle lipid oxidation is nearly entirely suppressed and glucose becomes the primary oxidative substrate of muscle, 2) glucose storage and oxidation are the major pathways of skeletal muscle glucose metabolism and are quantitatively similar at physiological insulin levels, and 3) the majority of insulin-stimulated glycolysis is oxidized, with only a small portion released as lactate or alanine.
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Stadtman, E. R., i C. N. Oliver. "Metal-catalyzed oxidation of proteins. Physiological consequences". Journal of Biological Chemistry 266, nr 4 (luty 1991): 2005–8. http://dx.doi.org/10.1016/s0021-9258(18)52199-2.
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Thomas, Michael J. "Physiological aspects of low-density lipoprotein oxidation". Current Opinion in Lipidology 11, nr 3 (czerwiec 2000): 297–301. http://dx.doi.org/10.1097/00041433-200006000-00011.
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Drazic, Adrian, i Jeannette Winter. "The physiological role of reversible methionine oxidation". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1844, nr 8 (sierpień 2014): 1367–82. http://dx.doi.org/10.1016/j.bbapap.2014.01.001.
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Ford, Megan M., Amanda L. Smythers, Evan W. McConnell, Sarah C. Lowery, Derrick R. J. Kolling i Leslie M. Hicks. "Inhibition of TOR in Chlamydomonas reinhardtii Leads to Rapid Cysteine Oxidation Reflecting Sustained Physiological Changes". Cells 8, nr 10 (28.09.2019): 1171. http://dx.doi.org/10.3390/cells8101171.
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The target of rapamycin (TOR) kinase is a master metabolic regulator with roles in nutritional sensing, protein translation, and autophagy. In Chlamydomonas reinhardtii, a unicellular green alga, TOR has been linked to the regulation of increased triacylglycerol (TAG) accumulation, suggesting that TOR or a downstream target(s) is responsible for the elusive “lipid switch” in control of increasing TAG accumulation under nutrient limitation. However, while TOR has been well characterized in mammalian systems, it is still poorly understood in photosynthetic systems, and little work has been done to show the role of oxidative signaling in TOR regulation. In this study, the TOR inhibitor AZD8055 was used to relate reversible thiol oxidation to the physiological changes seen under TOR inhibition, including increased TAG content. Using oxidized cysteine resin-assisted capture enrichment coupled with label-free quantitative proteomics, 401 proteins were determined to have significant changes in oxidation following TOR inhibition. These oxidative changes mirrored characterized physiological modifications, supporting the role of reversible thiol oxidation in TOR regulation of TAG production, protein translation, carbohydrate catabolism, and photosynthesis through the use of reversible thiol oxidation. The delineation of redox-controlled proteins under TOR inhibition provides a framework for further characterization of the TOR pathway in photosynthetic eukaryotes.
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Bonadonna, R. C., S. del Prato, E. Bonora, G. Gulli, A. Solini i R. A. DeFronzo. "Effects of physiological hyperinsulinemia on the intracellular metabolic partition of plasma glucose". American Journal of Physiology-Endocrinology and Metabolism 265, nr 6 (1.12.1993): E943—E953. http://dx.doi.org/10.1152/ajpendo.1993.265.6.e943.
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Methodology for assessing the glycolytic and oxidative fluxes from plasma glucose, by measuring 3H2O and 14CO2 rates of production during [3-3H]- and [U-14C]glucose infusion, was tested in healthy subjects. In study 1, during staircase 3H2O infusion in six subjects, calculated rates of 3H2O appearance agreed closely with 3H2O infusion rates. In study 2, when [2-3H]glucose and NaH14CO3 were infused in four subjects in the basal state and during a 4-h euglycemic insulin (approximately 70 microU/ml) clamp, accurate estimates of the rates of [2-3H]glucose detritiation were obtained (94-97% of the expected values), and the recovery factor of NaH14CO3 did not change during hyperinsulinemia. In study 3, 11 subjects underwent a 4-h euglycemic insulin (approximately 70 microU/ml) clamp with [3-3H]- and [U-14C]glucose infusion and measurement of gaseous exchanges by indirect calorimetry to estimate the rates of total glycolysis, glycogen synthesis, glucose oxidation, nonoxidative glycolysis, hepatic glucose production, glucose recycling, and glucose conversion to fat. Hyperinsulinemia stimulated glycogen synthesis above baseline more than glycolysis [increment of 4.78 +/- 0.37 vs. 2.0 +/- 0.17 mg.min-1 x kg-1 of lean body mass (LBM), respectively, P < 0.01] and incompletely suppressed (approximately 87%) hepatic glucose production. The major component of nonoxidative glycolysis shifted from glucose recycling in the postabsorptive state (approximately 57% of nonoxidative glycolysis) to glucose conversion to fat during hyperinsulinemia (approximately 59% of nonoxidative glycolysis). Lipid oxidation during the insulin clamp was negatively correlated with both isotopic glucose oxidation (r = -0.822, P < 0.002) and glycolysis (r = -0.582, P < 0.07). In conclusion, in healthy subjects, glycogen synthesis plays a greater role than glycolysis and glucose oxidation in determining insulin-mediated glucose disposal. Part of insulin-mediated increase in glycolysis/oxidation might be secondary to the relief of the competition between fat and glucose for oxidation.
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Hirota, Yuko, Dongchon Kang i Tomotake Kanki. "The Physiological Role of Mitophagy: New Insights into Phosphorylation Events". International Journal of Cell Biology 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/354914.
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Mitochondria play an essential role in oxidative phosphorylation, fatty acid oxidation, and the regulation of apoptosis. However, this organelle also produces reactive oxygen species (ROS) that continually inflict oxidative damage on mitochondrial DNA, proteins, and lipids, which causes further production of ROS. To oppose this oxidative stress, mitochondria possess quality control systems that include antioxidant enzymes and the repair or degradation of damaged mitochondrial DNA and proteins. If the oxidative stress exceeds the capacity of the mitochondrial quality control system, it seems that autophagy degrades the damaged mitochondria to maintain cellular homeostasis. Indeed, recent evidence from yeast to mammals indicates that the autophagy-dependent degradation of mitochondria (mitophagy) contributes to eliminate dysfunctional, aged, or excess mitochondria. In this paper, we describe the molecular processes and regulatory mechanisms of mitophagy in yeast and mammalian cells.
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Harper, M. E., R. M. Dent, V. Bezaire, A. Antoniou, A. Gauthier, S. Monemdjou i R. McPherson. "UCP3 and its putative function: consistencies and controversies". Biochemical Society Transactions 29, nr 6 (1.11.2001): 768–73. http://dx.doi.org/10.1042/bst0290768.
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The physiological function of uncoupling protein 3 (UCP3) is as yet unknown. Based on its 57% homology to UCP1 whose physiologic function is uncoupling and thermogenesis, UCP3 was attributed with the function of mitochondrial uncoupling through proton-leak reactions. UCP3 is expressed selectively in muscle, a tissue in which it has been estimated that proton leak accounts for approx. 50% of resting energy metabolism. Genetic linkage, association and variant studies suggest a role for UCP3 in obesity and/or diabetes. Studies of the heterologous expression of UCP3 in yeast provide support for the idea that UCP3 can uncouple mitochondrial oxidative phosphorylation, but the physiological relevance of these results is questionable. In vitro studies of mitochondria from Ucp3− − mice provide support, but there are no changes in resting metabolic rate (RMR) of mice. In vivo studies demonstrate increased ATP synthesis, but estimates of substrate oxidation rate indicate no change. Mice that greatly overexpress Ucp3 in muscle have increased RMR. Inconsistent with the function of uncoupling are the observations that fasting results in increased expression of UCP3, but no change in muscle proton leak. Moreover, fasting decreases energy expenditure in muscle. Expression patterns for Ucp3 and lipid-metabolism genes support a physiological role in fatty acid oxidation. Overall, findings support a role for Ucp3 in fatty acid metabolism that may have implications for obesity and/or Type II diabetes.
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Burgoyne, Joseph R., i Philip Eaton. "Contemporary techniques for detecting and identifying proteins susceptible to reversible thiol oxidation". Biochemical Society Transactions 39, nr 5 (21.09.2011): 1260–67. http://dx.doi.org/10.1042/bst0391260.
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Elevated protein oxidation is a widely reported hallmark of most major diseases. Historically, this ‘oxidative stress’ has been considered causatively detrimental, as the protein oxidation events were interpreted simply as damage. However, recent advances have changed this antiquated view; sensitive methodology for detecting and identifying proteins susceptible to oxidation has revealed a fundamental role for this modification in physiological cell signalling during health. Reversible protein oxidation that is dynamically coupled with cellular reducing systems allows oxidative protein modifications to regulate protein function, analogous to phosphoregulation. However, the relatively labile nature of many reversible protein oxidation states hampers the reliable detection and identification of modified proteins. Consequently, specialized methods to stabilize protein oxidation in combination with techniques to detect specific types of modification have been developed. Here, these techniques are discussed, and their sensitivity, selectivity and ability to reliably identify reversibly oxidized proteins are critically assessed.
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Bode, Helge B., Axel Zeeck, Kirsten Pl�ckhahn i Dieter Jendrossek. "Physiological and Chemical Investigations into Microbial Degradation of Synthetic Poly(cis-1,4-isoprene)". Applied and Environmental Microbiology 66, nr 9 (1.09.2000): 3680–85. http://dx.doi.org/10.1128/aem.66.9.3680-3685.2000.
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ABSTRACT Streptomyces coelicolor 1A and Pseudomonas citronellolis were able to degrade synthetic high-molecular-weight poly(cis-1,4-isoprene) and vulcanized natural rubber. Growth on the polymers was poor but significantly greater than that of the nondegrading strain Streptomyces lividans 1326 (control). Measurement of the molecular weight distribution of the polymer before and after degradation showed a time-dependent increase in low-molecular-weight polymer molecules forS. coelicolor 1A and P. citronellolis, whereas the molecular weight distribution for the control (S. lividans 1326) remained almost constant. Three degradation products were isolated from the culture fluid of S. coelicolor 1A grown on vulcanized rubber and were identified as (6Z)-2,6-dimethyl-10-oxo-undec-6-enoic acid, (5Z)-6-methyl-undec-5-ene-2,9-dione, and (5Z,9Z)-6,10-dimethyl-pentadec-5,9-diene-2,13-dione. An oxidative pathway from poly(cis-1,4-isoprene) to methyl-branched diketones is proposed. It includes (i) oxidation of an aldehyde intermediate to a carboxylic acid, (ii) one cycle of β-oxidation, (iii) oxidation of the conjugated double bond resulting in a β-keto acid, and (iv) decarboxylation.
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Webster, Keith A., Howard Prentice i Nanette H. Bishopric. "Oxidation of Zinc Finger Transcription Factors: Physiological Consequences". Antioxidants & Redox Signaling 3, nr 4 (sierpień 2001): 535–48. http://dx.doi.org/10.1089/15230860152542916.
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Zierath, J. R., L. A. Nolte, E. Wahlström, D. Galuska, P. R. Shepherd, B. B. Kahn i H. Wallberg-Henriksson. "Carrier-mediated fructose uptake significantly contributes to carbohydrate metabolism in human skeletal muscle". Biochemical Journal 311, nr 2 (15.10.1995): 517–21. http://dx.doi.org/10.1042/bj3110517.
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To determine whether fructose can be utilized as a metabolic substrate for skeletal muscle in man, we investigated its incorporation into glycogen, its oxidation and lactate production in isolated human skeletal muscle. Rates of fructose oxidation and incorporation into glycogen increased in the presence of increasing fructose concentrations (0.1-1.0 mM). Lactate production increased 3-fold when extracellular fructose was increased from 0.1 to 0.5 mM. Cytochalasin B, a competitive inhibitor of hexose transport mediated by the GLUT1 and GLUT4 facilitative glucose transporters, completely inhibited insulin-stimulated glucose incorporation into glycogen and glucose oxidation (P < 0.01), but did not alter fructose incorporation into glycogen or fructose oxidation. Insulin (1000 mu-units/ml) increased glucose incorporation into glycogen 2.7-fold and glucose oxidation 2.3-fold, whereas no effect on fructose incorporation into glycogen or fructose oxidation was noted. A physiological concentration of glucose (5 mM) decreased the rate of 0.5 mM fructose incorporation into glycogen by 60% (P < 0.001), whereas fructose oxidation was not altered in the presence of 5 mM glucose. Irrespective of fructose concentration, the majority of fructose taken up underwent non-oxidative metabolism. Lactate production accounted for approx. 80% of the fructose metabolism in the basal state and approx. 70% in the insulin (1000 mu-units/ml)-stimulated state. In the presence of 5 mM glucose, physiological concentrations of fructose could account for approximately 10-30% of hexose (glucose + fructose) incorporation into glycogen under non-insulin-stimulated conditions. In conclusion, fructose appears to be transported into human skeletal muscle via a carrier-mediated system that does not involve GLUT4 or GLUT1. Furthermore, under physiological conditions, fructose can significantly contribute to carbohydrate metabolism in human skeletal muscle.
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Drevet, Joël R., i Robert John Aitken. "Oxidation of Sperm Nucleus in Mammals: A Physiological Necessity to Some Extent with Adverse Impacts on Oocyte and Offspring". Antioxidants 9, nr 2 (23.01.2020): 95. http://dx.doi.org/10.3390/antiox9020095.
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Sperm cells have long been known to be good producers of reactive oxygen species, while they are also known to be particularly sensitive to oxidative damage affecting their structures and functions. As with all organic cellular components, sperm nuclear components and, in particular, nucleic acids undergo oxidative alterations that have recently been shown to be commonly encountered in clinical practice. This review will attempt to provide an overview of this situation. After a brief coverage of the biological reasons why the sperm nucleus and associated DNA are sensitive to oxidative damage, a summary of the most recent results concerning the oxidation of sperm DNA in animal and human models will be presented. The study will then attempt to cover the possible consequences of sperm nuclear oxidation on male fertility and beyond.
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Poggetti, R. S., E. E. Moore, F. A. Moore, K. Koike, R. Tuder, B. O. Anderson i A. Banerjee. "Quantifying oxidative injury in the liver". American Journal of Physiology-Gastrointestinal and Liver Physiology 268, nr 3 (1.03.1995): G471—G479. http://dx.doi.org/10.1152/ajpgi.1995.268.3.g471.
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Oxidative injury is a mechanism common to both ischemia-reperfusion (IR) and leukocyte-mediated injury. Reperfused tissue beds and elaborated mediators can activate a cascade of intercellular and interorgan injuries that often precipitates multiple organ failure. Initiation of lung injury by gut IR is a case in point, but concomitant liver injury may have been overlooked because of the absence of comparably sensitive physiological markers. In this study, we explore the hypothesis that occurrence of portally derived oxidant-induced liver dysfunction may be detected with both sensitivity and specificity. We simulated pure oxidative injury to the liver and separated the contributions from secondary systemic oxidation. Both tissue and plasma indicators were evaluated, each reflecting aspects of oxidation, membrane integrity, and metabolic function. Tissue markers readily detect oxidative liver injury, but systemic 3-hydroxybutyrate (3-OHB) concentration and ketone body ratio (KBR) are the most sensitive. Comparison of 3-OHB concentrations against the corresponding KBR can be used to distinguish adjustments within a physiological range from the transition into injury.
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Santarelli, Lindsey Ciali, Jianguo Chen, Stefan H. Heinemann i Toshinori Hoshi. "The β1 Subunit Enhances Oxidative Regulation of Large-Conductance Calcium-activated K+ Channels". Journal of General Physiology 124, nr 4 (27.09.2004): 357–70. http://dx.doi.org/10.1085/jgp.200409144.
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Oxidative stress may alter the functions of many proteins including the Slo1 large conductance calcium-activated potassium channel (BKCa). Previous results demonstrated that in the virtual absence of Ca2+, the oxidant chloramine-T (Ch-T), without the involvement of cysteine oxidation, increases the open probability and slows the deactivation of BKCa channels formed by human Slo1 (hSlo1) α subunits alone. Because native BKCa channel complexes may include the auxiliary subunit β1, we investigated whether β1 influences the oxidative regulation of hSlo1. Oxidation by Ch-T with β1 present shifted the half-activation voltage much further in the hyperpolarizing direction (−75 mV) as compared with that with α alone (−30 mV). This shift was eliminated in the presence of high [Ca2+]i, but the increase in open probability in the virtual absence of Ca2+ remained significant at physiologically relevant voltages. Furthermore, the slowing of channel deactivation after oxidation was even more dramatic in the presence of β1. Oxidation of cysteine and methionine residues within β1 was not involved in these potentiated effects because expression of mutant β1 subunits lacking cysteine or methionine residues produced results similar to those with wild-type β1. Unlike the results with α alone, oxidation by Ch-T caused a significant acceleration of channel activation only when β1 was present. The β1 M177 mutation disrupted normal channel activation and prevented the Ch-T–induced acceleration of activation. Overall, the functional effects of oxidation of the hSlo1 pore-forming α subunit are greatly amplified by the presence of β1, which leads to the additional increase in channel open probability and the slowing of deactivation. Furthermore, M177 within β1 is a critical structural determinant of channel activation and oxidative sensitivity. Together, the oxidized BKCa channel complex with β1 has a considerable chance of being open within the physiological voltage range even at low [Ca2+]i.
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Murray, Andrew J., Hugh E. Montgomery, Martin Feelisch, Michael P. W. Grocott i Daniel S. Martin. "Metabolic adjustment to high-altitude hypoxia: from genetic signals to physiological implications". Biochemical Society Transactions 46, nr 3 (20.04.2018): 599–607. http://dx.doi.org/10.1042/bst20170502.
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Ascent to high altitude is associated with physiological responses that counter the stress of hypobaric hypoxia by increasing oxygen delivery and by altering tissue oxygen utilisation via metabolic modulation. At the cellular level, the transcriptional response to hypoxia is mediated by the hypoxia-inducible factor (HIF) pathway and results in promotion of glycolytic capacity and suppression of oxidative metabolism. In Tibetan highlanders, gene variants encoding components of the HIF pathway have undergone selection and are associated with adaptive phenotypic changes, including suppression of erythropoiesis and increased blood lactate levels. In some highland populations, there has also been a selection of variants in PPARA, encoding peroxisome proliferator-activated receptor alpha (PPARα), a transcriptional regulator of fatty acid metabolism. In one such population, the Sherpas, lower muscle PPARA expression is associated with a decreased capacity for fatty acid oxidation, potentially improving the efficiency of oxygen utilisation. In lowlanders ascending to altitude, a similar suppression of fatty acid oxidation occurs, although the underlying molecular mechanism appears to differ along with the consequences. Unlike lowlanders, Sherpas appear to be protected against oxidative stress and the accumulation of intramuscular lipid intermediates at altitude. Moreover, Sherpas are able to defend muscle ATP and phosphocreatine levels in the face of decreased oxygen delivery, possibly due to suppression of ATP demand pathways. The molecular mechanisms allowing Sherpas to successfully live, work and reproduce at altitude may hold the key to novel therapeutic strategies for the treatment of diseases to which hypoxia is a fundamental contributor.
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Allen, Tara J., i Christopher D. Hardin. "Influence of glycogen storage on vascular smooth muscle metabolism". American Journal of Physiology-Heart and Circulatory Physiology 278, nr 6 (1.06.2000): H1993—H2002. http://dx.doi.org/10.1152/ajpheart.2000.278.6.h1993.
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The role of glycogen as an oxidative substrate for vascular smooth muscle (VSM) remains controversial. To elucidate the importance of glycogen as an oxidative substrate and the influence of glycogen flux on VSM substrate selection, we systematically altered glycogen levels and measured metabolism of glucose, acetate, and glycogen. Hog carotid arteries with glycogen contents ranging from 1 to 11 μmol/g were isometrically contracted in physiological salt solution containing 5 mM [1-13C]glucose and 1 mM [1,2-13C]acetate at 37°C for 6 h. [1-13C]glucose, [1,2-13C]acetate, and glycogen oxidation were simultaneously measured with the use of a 13C-labeled isotopomer analysis of glutamate. Although oxidation of glycogen increased with the glycogen content of the tissue, glycogen oxidation contributed only ∼10% of the substrate oxidized by VSM. Whereas [1-13C]glucose flux, [3-13C]lactate production from [1-13C]glucose, and [1,2-13C]acetate oxidation were not regulated by glycogen content, [1-13C]glucose oxidation was significantly affected by the glycogen content of VSM. However, [1-13C]glucose remained the primary (∼40–50%) contributor to substrate oxidation. Therefore, we conclude that glucose is the predominate substrate oxidized by VSM, and glycogen oxidation contributes minimally to substrate oxidation.
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Vatrál, Jaroslav, Roman Boča i Wolfgang Linert. "Oxidation properties of dopamine at and near physiological conditions". Monatshefte für Chemie - Chemical Monthly 146, nr 11 (1.09.2015): 1799–805. http://dx.doi.org/10.1007/s00706-015-1560-2.
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Stanisz, Jolanta, Burton M. Wice i David E. Kennell. "Serum factors that stimulate fatty acid oxidation: Physiological specificity". Journal of Cellular Physiology 126, nr 1 (styczeń 1986): 141–46. http://dx.doi.org/10.1002/jcp.1041260119.
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Fischer, Manuel, Sebastian Horn, Anouar Belkacemi, Kerstin Kojer, Carmelina Petrungaro, Markus Habich, Muna Ali i in. "Protein import and oxidative folding in the mitochondrial intermembrane space of intact mammalian cells". Molecular Biology of the Cell 24, nr 14 (15.07.2013): 2160–70. http://dx.doi.org/10.1091/mbc.e12-12-0862.
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Oxidation of cysteine residues to disulfides drives import of many proteins into the intermembrane space of mitochondria. Recent studies in yeast unraveled the basic principles of mitochondrial protein oxidation, but the kinetics under physiological conditions is unknown. We developed assays to follow protein oxidation in living mammalian cells, which reveal that import and oxidative folding of proteins are kinetically and functionally coupled and depend on the oxidoreductase Mia40, the sulfhydryl oxidase augmenter of liver regeneration (ALR), and the intracellular glutathione pool. Kinetics of substrate oxidation depends on the amount of Mia40 and requires tightly balanced amounts of ALR. Mia40-dependent import of Cox19 in human cells depends on the inner membrane potential. Our observations reveal considerable differences in the velocities of mitochondrial import pathways: whereas preproteins with bipartite targeting sequences are imported within seconds, substrates of Mia40 remain in the cytosol for several minutes and apparently escape premature degradation and oxidation.
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Lee, Tae-Hee, i Tae-Hong Kang. "DNA Oxidation and Excision Repair Pathways". International Journal of Molecular Sciences 20, nr 23 (3.12.2019): 6092. http://dx.doi.org/10.3390/ijms20236092.
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The physiological impact of the aberrant oxidation products on genomic DNA were demonstrated by embryonic lethality or the cancer susceptibility and/or neurological symptoms of animal impaired in the base excision repair (BER); the major pathway to maintain genomic integrity against non-bulky DNA oxidation. However, growing evidence suggests that other DNA repair pathways or factors that are not primarily associated with the classical BER pathway are also actively involved in the mitigation of oxidative assaults on the genomic DNA, according to the corresponding types of DNA oxidation. Among others, factors dedicated to lesion recognition in the nucleotide excision repair (NER) pathway have been shown to play eminent roles in the process of lesion recognition and stimulation of the enzyme activity of some sets of BER factors. Besides, substantial bulky DNA oxidation can be preferentially removed by a canonical NER mechanism; therefore, loss of function in the NER pathway shares common features arising from BER defects, including cancer predisposition and neurological disorders, although NER defects generally are nonlethal. Here we discuss recent achievements for delineating newly arising roles of NER lesion recognition factors to facilitate the BER process, and cooperative works of BER and NER pathways in response to the genotoxic oxidative stress.
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Das, D., P. K. De i R. K. Banerjee. "Thiocyanate, a plausible physiological electron donor of gastric peroxidase". Biochemical Journal 305, nr 1 (1.01.1995): 59–64. http://dx.doi.org/10.1042/bj3050059.
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Gastric peroxidase (GPO) was purified to apparent homogeneity to characterize its major physiological electron donor. The enzyme (RZ = 0.7), with a subunit molecular mass of 50 kDa, is a glycoprotein, with a relative abundance of aspartic and glutamic acid over arginine and lysine. It has a Soret maximum at 412 nm, which is shifted to 426 nm by H2O2 due to formation of compound II. Although the physiological electron donors I-, Br- and SCN-, but not Cl-, are oxidized by GPO optimally at acid pH, only I- and SCN- are oxidized appreciably at physiological pH. Considering that the I- concentration in stomach is less than 1 microM, whereas the SCN- concentration is about 250 microM, SCN- may act as a major electron donor for GPO. Moreover, SCN- oxidation remains unaltered in the presence of physiological concentrations of other halides. The second-order rate constant for the reaction of GPO with H2O2 (k1) and compound I with SCN- (k2) at pH 7 was found to be 8 x 10(7) M-1.s-1 and 2 x 10(5) M-1.s-1 respectively. GPO has significant pseudocatalase activity also in the presence of I- or Br-, but it is blocked by SCN-. The SCN- oxidation product OSCN- may be reduced back to SCN- by cellular GSH, and GSSG may be reduced back to GSH by glutathione reductase and NADPH. In a system reconstituted with pure glutathione reductase, NADPH, GSH, SCN- and H2O2. GPO-catalysed SCN- oxidation could be coupled to NADPH oxidation. This system where GPO utilizes SCN- as the major physiological electron donor may operate efficiently to scavenge intracellular H2O2.
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Hondorp, Elise R., i Rowena G. Matthews. "Oxidation of Cysteine 645 of Cobalamin-Independent Methionine Synthase Causes a Methionine Limitation in Escherichia coli". Journal of Bacteriology 191, nr 10 (13.03.2009): 3407–10. http://dx.doi.org/10.1128/jb.01722-08.
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ABSTRACT Cobalamin-independent methionine synthase (MetE) catalyzes the final step in Escherichia coli methionine biosynthesis but is inactivated under oxidative conditions, triggering a methionine deficiency. This study demonstrates that the mutation of MetE cysteine 645 to alanine completely eliminates the methionine auxotrophy imposed by diamide treatment, suggesting that modulation of MetE activity via cysteine 645 oxidation has significant physiological consequences for oxidatively stressed cells.
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Pedersen, Line, Caroline Holkmann Olsen, Bente Klarlund Pedersen i Pernille Hojman. "Muscle-derived expression of the chemokine CXCL1 attenuates diet-induced obesity and improves fatty acid oxidation in the muscle". American Journal of Physiology-Endocrinology and Metabolism 302, nr 7 (1.04.2012): E831—E840. http://dx.doi.org/10.1152/ajpendo.00339.2011.
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Serum levels and muscle expression of the chemokine CXCL1 increase markedly in response to exercise in mice. Because several studies have established muscle-derived factors as important contributors of metabolic effects of exercise, this study aimed at investigating the effect of increased expression of muscle-derived CXCL1 on systemic and intramuscular metabolic parameters, with focus on fatty acid oxidation and oxidative metabolism in skeletal muscle. By overexpression of CXCL1 in the tibialis cranialis muscle in mice, significant elevations in muscle and serum CXCL1 within a physiological range were obtained. At 3 mo of high-fat feeding, visceral and subcutaneous fat mass were 32.4 ( P < 0.01) and 22.4% ( P < 0.05) lower, respectively, in CXCL1-overexpressing mice compared with control mice. Also, chow-fed CXCL-transfected mice had 35.4% ( P < 0.05) lower visceral fat mass and 33.4% ( P < 0.05) lower subcutaneous fat mass compared with chow-fed control mice. These reductions in accumulation of adipose tissue were accompanied by improved glucose tolerance and insulin sensitivity. Furthermore, in CXCL1-transfected muscles, muscular ex vivo fatty acid oxidation was significantly enhanced compared with control muscles (chow fed: 2.2-fold, P < 0.05; high-fat fed: 2-fold, P < 0.05) and also showed increased expression levels of major fatty acid oxidation genes (CD36, CPT I, and HADH). Finally, CXCL1 expression was associated with increased muscle mRNA expression of VEGF and CD31, suggesting a role for CXCL1 in muscle angiogenesis. In conclusion, our data show that overexpression of CXCL1 within a physiological range attenuates diet-induced obesity, likely mediated through a CXCL1-induced improvement of fatty acid oxidation and oxidative capacity in skeletal muscle tissue.
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Takahama, Umeo. "Oxidation of vacuolar and apoplastic phenolic substrates by peroxidase: Physiological significance of the oxidation reactions". Phytochemistry Reviews 3, nr 1-2 (styczeń 2004): 207–19. http://dx.doi.org/10.1023/b:phyt.0000047805.08470.e3.
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Groop, L. C., R. C. Bonadonna, D. C. Simonson, A. S. Petrides, M. Shank i R. A. DeFronzo. "Effect of insulin on oxidative and nonoxidative pathways of free fatty acid metabolism in human obesity". American Journal of Physiology-Endocrinology and Metabolism 263, nr 1 (1.07.1992): E79—E84. http://dx.doi.org/10.1152/ajpendo.1992.263.1.e79.
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The dose-response relationship between the plasma insulin concentration and oxidative and nonoxidative pathways of free fatty acid (FFA) metabolism was examined in 11 obese and 7 lean subjects using a stepwise insulin clamp technique in combination with indirect calorimetry and infusion of [1-14C]palmitate. The fasting plasma FFA concentration was elevated in obese subjects (793 +/- 43 vs. 642 +/- 39 mumol/l; P less than 0.01) and was associated with an increased basal rate of plasma FFA turnover, FFA oxidation, and nonoxidative FFA disposal, i.e., reesterification (all P less than 0.01). Suppression of plasma FFA turnover by physiological increments in plasma insulin was impaired in obese compared with lean subjects. However, plasma FFA turnover expressed per kilogram fat mass was normally suppressed by insulin in obese subjects. Although insulin suppressed plasma FFA oxidation to the same extent in lean and obese subjects, inhibition of total lipid oxidation by insulin was impaired in the obese group. Obese subjects had an enhanced basal rate of nonoxidative FFA disposal, which was suppressed less by physiological increments in plasma insulin compared with lean controls. Therefore, we conclude that 1) lipolysis in uncomplicated obesity is normally sensitive to insulin; the enhanced FFA flux is simply a consequence of the increased fat mass. 2) Nonoxidative FFA disposal expressed per lean body mass is enhanced in obese subjects and correlates with the increase in plasma FFA concentration and fat mass. 3) Enhanced oxidation of intracellular lipids contributes to the enhanced rate of total lipid oxidation in obese subjects.
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Rasmusson, Allan G., i Sabá V. Wallström. "Involvement of mitochondria in the control of plant cell NAD(P)H reduction levels". Biochemical Society Transactions 38, nr 2 (22.03.2010): 661–66. http://dx.doi.org/10.1042/bst0380661.
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NADPH and NADH mediate reductant flow between cellular processes, linking central carbon and energy metabolism with intermediary metabolism, stress defence and development. Recent investigations have revealed paths of functional interactions, and have suggested that mitochondrial NADPH oxidation, especially together with the oxidative pentose phosphate pathway, is an important regulator of the cytosolic NADPH reduction level. Furthermore, stress-dependent metabolic pathways substantially affect the NADPH reduction level in particular physiological situations. The mitochondrial impact on the NADPH reduction level provides a model example of the physiological significance of the mitochondrial NAD(P)H dehydrogenase set-up, which is more complex in plants than in other organisms.
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Tretter, Verena, Beatrix Hochreiter, Marie Louise Zach, Katharina Krenn i Klaus Ulrich Klein. "Understanding Cellular Redox Homeostasis: A Challenge for Precision Medicine". International Journal of Molecular Sciences 23, nr 1 (22.12.2021): 106. http://dx.doi.org/10.3390/ijms23010106.
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Living organisms use a large repertoire of anabolic and catabolic reactions to maintain their physiological body functions, many of which include oxidation and reduction of substrates. The scientific field of redox biology tries to understand how redox homeostasis is regulated and maintained and which mechanisms are derailed in diverse pathological developments of diseases, where oxidative or reductive stress is an issue. The term “oxidative stress” is defined as an imbalance between the generation of oxidants and the local antioxidative defense. Key mediators of oxidative stress are reactive species derived from oxygen, nitrogen, and sulfur that are signal factors at physiological concentrations but can damage cellular macromolecules when they accumulate. However, therapeutical targeting of oxidative stress in disease has proven more difficult than previously expected. Major reasons for this are the very delicate cellular redox systems that differ in the subcellular compartments with regard to their concentrations and depending on the physiological or pathological status of cells and organelles (i.e., circadian rhythm, cell cycle, metabolic need, disease stadium). As reactive species are used as signaling molecules, non-targeted broad-spectrum antioxidants in many cases will fail their therapeutic aim. Precision medicine is called to remedy the situation.
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Kanemura, Shingo, Elza Firdiani Sofia, Naoya Hirai, Masaki Okumura, Hiroshi Kadokura i Kenji Inaba. "Characterization of the endoplasmic reticulum–resident peroxidases GPx7 and GPx8 shows the higher oxidative activity of GPx7 and its linkage to oxidative protein folding". Journal of Biological Chemistry 295, nr 36 (21.07.2020): 12772–85. http://dx.doi.org/10.1074/jbc.ra120.013607.
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Oxidative protein folding occurs primarily in the mammalian endoplasmic reticulum, enabled by a diverse network comprising more than 20 members of the protein disulfide isomerase (PDI) family and more than five PDI oxidases. Although the canonical disulfide bond formation pathway involving Ero1α and PDI has been well-studied so far, the physiological roles of the newly identified PDI oxidases, glutathione peroxidase-7 (GPx7) and -8 (GPx8), are only poorly understood. We here demonstrated that human GPx7 has much higher reactivity with H2O2 and hence greater PDI oxidation activity than human GPx8. The high reactivity of GPx7 is due to the presence of a catalytic tetrad at the redox-active site, which stabilizes the sulfenylated species generated upon the reaction with H2O2. Although it was previously postulated that GPx7 catalysis involved a highly reactive peroxidatic cysteine that can be sulfenylated by H2O2, we revealed that a resolving cysteine instead regulates the PDI oxidation activity of GPx7. We also determined that GPx7 formed complexes preferentially with PDI and P5 in H2O2-treated cells. Altogether, these results suggest that human GPx7 functions as an H2O2-dependent PDI oxidase in cells, whereas PDI oxidation may not be the central physiological role of human GPx8.
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Timoshnikov, Viktor A., Lilia A. Kichigina, Olga Yu Selyutina, Nikolay E. Polyakov i George J. Kontoghiorghes. "Antioxidant Activity of Deferasirox and Its Metal Complexes in Model Systems of Oxidative Damage: Comparison with Deferiprone". Molecules 26, nr 16 (20.08.2021): 5064. http://dx.doi.org/10.3390/molecules26165064.
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Deferasirox is an orally active, lipophilic iron chelating drug used on thousands of patients worldwide for the treatment of transfusional iron overload. The essential transition metals iron and copper are the primary catalysts of reactive oxygen species and oxidative damage in biological systems. The redox effects of deferasirox and its metal complexes with iron, copper and other metals are of pharmacological, toxicological, biological and physiological importance. Several molecular model systems of oxidative damage caused by iron and copper catalysis including the oxidation of ascorbic acid, the peroxidation of linoleic acid micelles and the oxidation of dihydropyridine have been investigated in the presence of deferasirox using UV-visible and NMR spectroscopy. Deferasirox has shown antioxidant activity in all three model systems, causing substantial reduction in the rate of oxidation and oxidative damage. Deferasirox showed the greatest antioxidant activity in the oxidation of ascorbic acid with the participation of iron ions and reduced the reaction rate by about a 100 times. Overall, deferasirox appears to have lower affinity for copper in comparison to iron. Comparative studies of the antioxidant activity of deferasirox and the hydrophilic oral iron chelating drug deferiprone in the peroxidation of linoleic acid micelles showed lower efficiency of deferasirox in comparison to deferiprone.
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Hernández, José A., Rosa C. López-Sánchez i Adela Rendón-Ramírez. "Lipids and Oxidative Stress Associated with Ethanol-Induced Neurological Damage". Oxidative Medicine and Cellular Longevity 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/1543809.
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The excessive intake of alcohol is a serious public health problem, especially given the severe damage provoked by chronic or prenatal exposure to alcohol that affects many physiological processes, such as memory, motor function, and cognitive abilities. This damage is related to the ethanol oxidation in the brain. The metabolism of ethanol to acetaldehyde and then to acetate is associated with the production of reactive oxygen species that accentuate the oxidative state of cells. This metabolism of ethanol can induce the oxidation of the fatty acids in phospholipids, and the bioactive aldehydes produced are known to be associated with neurotoxicity and neurodegeneration. As such, here we will review the role of lipids in the neuronal damage induced by ethanol-related oxidative stress and the role that lipids play in the related compensatory or defense mechanisms.
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POURCEL, L., J. ROUTABOUL, V. CHEYNIER, L. LEPINIEC i I. DEBEAUJON. "Flavonoid oxidation in plants: from biochemical properties to physiological functions". Trends in Plant Science 12, nr 1 (styczeń 2007): 29–36. http://dx.doi.org/10.1016/j.tplants.2006.11.006.
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Sarkar, Bipul, Arnab Kumar De i M. K. Adak. "Physiological characterization of SUB1 trait in rice under subsequent submergence and re-aeration with interaction of chemical elicitors". Plant Science Today 4, nr 4 (27.11.2017): 177–90. http://dx.doi.org/10.14719/pst.2017.4.4.351.
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In the present study, the sensitivity of two chemical elicitors: polyamine (PA) and salicylic (SA) acid were exercised for submergence sensitivity in Swarna Sub1A rice variety. Under 5 days of submergence, the antioxidation responses were more distinguished in plants against control. Along with the anti-oxidation modules, significant changes in biomolecule loss were registered through lipid and protein oxidation by 1.91 and 1.46 -fold respectively. PA and SA treated plants were the reliever to recover the membrane potential. Total carbohydrate and reducing sugars were varied under submergence by down regulation of 36.66 and 44.44% as compared to control. This was also supported by regulation of ?-amylase activity under submergence that also recovered significantly with PA and SA treatments against submergence. In association with carbohydrate metabolism, Under submergence Swarna Sub1A recorded to be prone with oxidative stress through O2.- (1.55 fold) and peroxide (1.70-fold) over-accumulation but recovered as PA and SA applied. In both cases, sustenance of non-enzymatic anti-oxidant like total carotenoid and lycopene content were also contributory through down-regulation. The enzymatic anti-oxidation paths like SOD, GPX, CAT and GR were regulated by 11.11, 19.54, 13.65, 10.03% declined respectively and thoroughly discussed with reference to PA and SA interactions.
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Dulloo, A. G., S. Samec i J. Seydoux. "Uncoupling protein 3 and fatty acid metabolism". Biochemical Society Transactions 29, nr 6 (1.11.2001): 785–91. http://dx.doi.org/10.1042/bst0290785.
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A role for uncoupling protein (UCP) 3 in fatty acid metabolism is reviewed within the context of our proposal, first put forward in 1998, that this homologue of UCP1 may be involved in the regulation of lipids as fuel substrate rather than in the mediation of thermogenesis. Since then, the demonstrations of muscle-type differences in UCP3 gene regulation in response to dietary manipulations (starvation, high-fat feeding) or to pharmacological interferences with the flux of lipid substrates between adipose-tissue stores and skeletal-muscle mitochondrial oxidation are all in accord with this proposed role for UCP3 in regulating lipids as fuel substrate. However, given the current limitations of gene-knockout technology for evaluating/interpreting the functional importance of genes encoding mitochondrial membrane proteins, the transition from ‘associative’ to ‘cause-and-effect’ evidence for a physiological role of UCP3 in regulating fatty acid metabolism will have to await the development of assays that are sensitive to changes in UCP3 activity. Furthermore, in evaluating the physiological regulators of UCP3, the available evidence points to the existence of adipose-derived factor(s) which, independently of circulating levels of free fatty acids, initiates events leading to the transcription of genes encoding UCP3 and key enzymes of lipid oxidation in the fast glycolytic or fast oxidative-glycolytic muscles, i.e. in the bulk of the skeletal-muscle mass. It is proposed that in tissues where UCP3 co-exists with UCP2 (skeletal muscle, brown adipose tissue, heart) they may act in concert in the overall regulation of lipid oxidation, concomitant to the prevention of lipid-induced oxidative damage.
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Bjugstad, Kimberly, Paul Gutowski, Jennifer Pekarek, Pamela Bourg, Charles Mains i David Bar-Or. "Redox Changes in Amateur Race Car Drivers Before and After Racing". Sports Medicine International Open 1, nr 06 (październik 2017): E212—E219. http://dx.doi.org/10.1055/s-0043-119065.
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AbstractDespite the unique opportunity race car driving provides to study exercise in extreme conditions, the sport of racing is under-represented. A better understanding of how racing changes physiological measures combined with driver demographics may help reduce driver risks and expand the field of driver science. This study charted the changes in heart rate, body temperature, blood pressure, static oxidation reduction potential (sORP), and antioxidant capacity in drivers before and after racing (n=23). The interaction between racing and driver characteristics on physiological variables were evaluated. Heart rate, body temperature, and sORP were elevated after racing (P<0.05). Age, cockpit temperature, experience, and speed did not correlate with physiological or oxidative measures (P>0.05). Elevated post-race sORP values were associated with higher pre-race systolic blood pressure and lower antioxidant capacity (P<0.05). We conclude that racing alters the redox response in drivers and that drivers’ pre-race systolic blood pressure and antioxidant capacity can further alter it. A better understanding of the physical and oxidative changes which result from racing may help minimize the unique risks
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Yeh, Hsien-Wei, Kuan-Hung Lin, Syue-Yi Lyu, Yi-Shan Li, Chun-Man Huang, Yung-Lin Wang, Hao-Wei Shih, Ning-Shian Hsu, Chang-Jer Wu i Tsung-Lin Li. "Biochemical and structural explorations of α-hydroxyacid oxidases reveal a four-electron oxidative decarboxylation reaction". Acta Crystallographica Section D Structural Biology 75, nr 8 (30.07.2019): 733–42. http://dx.doi.org/10.1107/s2059798319009574.
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p-Hydroxymandelate oxidase (Hmo) is a flavin mononucleotide (FMN)-dependent enzyme that oxidizes mandelate to benzoylformate. How the FMN-dependent oxidation is executed by Hmo remains unclear at the molecular level. A continuum of snapshots from crystal structures of Hmo and its mutants in complex with physiological/nonphysiological substrates, products and inhibitors provides a rationale for its substrate enantioselectivity/promiscuity, its active-site geometry/reactivity and its direct hydride-transfer mechanism. A single mutant, Y128F, that extends the two-electron oxidation reaction to a four-electron oxidative decarboxylation reaction was unexpectedly observed. Biochemical and structural approaches, including biochemistry, kinetics, stable isotope labeling and X-ray crystallography, were exploited to reach these conclusions and provide additional insights.
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Lian, Di, Ming-Ming Chen, Hanyu Wu, Shoulong Deng i Xiaoxiang Hu. "The Role of Oxidative Stress in Skeletal Muscle Myogenesis and Muscle Disease". Antioxidants 11, nr 4 (11.04.2022): 755. http://dx.doi.org/10.3390/antiox11040755.
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The contractile activity, high oxygen consumption and metabolic rate of skeletal muscle cause it to continuously produce moderate levels of oxidant species, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). Under normal physiological conditions, there is a dynamic balance between the production and elimination of ROS/RNS. However, when the oxidation products exceed the antioxidant defense capacity, the body enters a state of oxidative stress. Myogenesis is an important process to maintain muscle homeostasis and the physiological function of skeletal muscle. Accumulating evidence suggests that oxidative stress plays a key role in myogenesis and skeletal muscle physiology and pathology. In this review, we summarize the sources of reactive oxygen species in skeletal muscle and the causes of oxidative stress and analyze the key role of oxidative stress in myogenesis. Then, we discuss the relationship between oxidative stress and muscle homeostasis and physiopathology. This work systematically summarizes the role of oxidative stress in myogenesis and muscle diseases and provides targets for subsequent antioxidant therapy and repair of inflammatory damage in noninflammatory muscle diseases.
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Alonso-Alvarez, Carlos, Sophie Bertrand, Bruno Faivre, Olivier Chastel i Gabriele Sorci. "Testosterone and oxidative stress: the oxidation handicap hypothesis". Proceedings of the Royal Society B: Biological Sciences 274, nr 1611 (19.12.2006): 819–25. http://dx.doi.org/10.1098/rspb.2006.3764.
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Secondary sexual traits (SST) are usually thought to have evolved as honest signals of individual quality during mate choice. Honesty of SST is guaranteed by the cost of producing/maintaining them. In males, the expression of many SST is testosterone-dependent. The immunocompetence handicap hypothesis has been proposed as a possible mechanism ensuring honesty of SST on the basis that testosterone, in addition to its effect on sexual signals, also has an immunosuppressive effect. The immunocompetence handicap hypothesis has received mixed support. However, the cost of testosterone-based signalling is not limited to immunosuppression and might involve other physiological functions such as the antioxidant machinery. Here, we tested the hypothesis that testosterone depresses resistance to oxidative stress in a species with a testosterone-dependent sexual signal, the zebra finch. Male zebra finches received subcutaneous implants filled with flutamide (an anti-androgen) or testosterone, or kept empty (control). In agreement with the prediction, we found that red blood cell resistance to a free radical attack was the highest in males implanted with flutamide and the lowest in males implanted with testosterone. We also found that cell-mediated immune response was depressed in testosterone-treated birds, supporting the immunocompetence handicap hypothesis. The recent finding that red blood cell resistance to free radicals is negatively associated with mortality in this species suggests that benefits of sexual signalling might trade against the costs derived from oxidation.
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Graham, Brian J., Ian W. Windsor, Brian Gold i Ronald T. Raines. "Boronic acid with high oxidative stability and utility in biological contexts". Proceedings of the National Academy of Sciences 118, nr 10 (2.03.2021): e2013691118. http://dx.doi.org/10.1073/pnas.2013691118.
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Despite their desirable attributes, boronic acids have had a minimal impact in biological contexts. A significant problem has been their oxidative instability. At physiological pH, phenylboronic acid and its boronate esters are oxidized by reactive oxygen species at rates comparable to those of thiols. After considering the mechanism and kinetics of the oxidation reaction, we reasoned that diminishing electron density on boron could enhance oxidative stability. We found that a boralactone, in which a carboxyl group serves as an intramolecular ligand for the boron, increases stability by 104-fold. Computational analyses revealed that the resistance to oxidation arises from diminished stabilization of the p orbital of boron that develops in the rate-limiting transition state of the oxidation reaction. Like simple boronic acids and boronate esters, a boralactone binds covalently and reversibly to 1,2-diols such as those in saccharides. The kinetic stability of its complexes is, however, at least 20-fold greater. A boralactone also binds covalently to a serine side chain in a protein. These attributes confer unprecedented utility upon boralactones in the realms of chemical biology and medicinal chemistry.
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Islam, Hashim, Logan K. Townsend i Tom J. Hazell. "Modified sprint interval training protocols. Part I. Physiological responses". Applied Physiology, Nutrition, and Metabolism 42, nr 4 (kwiecień 2017): 339–46. http://dx.doi.org/10.1139/apnm-2016-0478.
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Adaptations to sprint interval training (SIT) are observed with brief (≤15-s) work bouts highlighting peak power generation as an important metabolic stimulus. This study examined the effects of manipulating SIT work bout and recovery period duration on energy expenditure (EE) during and postexercise, as well as postexercise fat oxidation rates. Nine active males completed a resting control session (CTRL) and 3 SIT sessions in randomized order: (i) 30:240 (4 × 30-s bouts, 240-s recovery); (ii) 15:120 (8 × 15-s bouts, 120-s recovery); (3) 5:40 (24 × 5-s bouts, 40-s recovery). Protocols were matched for the total duration of work (2 min) and recovery (16 min), as well as the work-to-recovery ratio (1:8 s). EE and fat oxidation rates were derived from gas exchange measured before, during, and for 3 h postexercise. All protocols increased EE versus CTRL (P < 0.001). Exercise EE was greater (P < 0.001) with 5:40 (209 kcal) versus both 15:120 (163 kcal) and 30:240 (138 kcal), while 15:120 was also greater (P < 0.001) than 30:240. Postexercise EE was greater (P = 0.014) with 15:120 (313 kcal) versus 5:40 (294 kcal), though both were similar (P > 0.077) to 30:240 (309 kcal). Postexercise fat oxidation was similar (P = 0.650) after 15:120 (0.104 g·min−1) and 30:240 (0.116 g·min−1) and both were greater (P < 0.030) than 5:40 (0.072 g·min−1) and CTRL (0.049 g·min−1). In conclusion, shorter SIT work bouts that target peak power generation increase exercise EE without compromising postexercise EE, though longer bouts promote greater postexercise fat utilization.
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Eseberri, Itziar, Claire Laurens, Jonatan Miranda, Katie Louche, Arrate Lasa, Cedric Moro i Maria P. Portillo. "Effects of Physiological Doses of Resveratrol and Quercetin on Glucose Metabolism in Primary Myotubes". International Journal of Molecular Sciences 22, nr 3 (30.01.2021): 1384. http://dx.doi.org/10.3390/ijms22031384.
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Phenolic compounds have emerged in recent years as an option to face insulin resistance and diabetes. The central aim of this study was: (1) to demonstrate that physiological doses of resveratrol (RSV) or quercetin (Q) can influence glucose metabolism in human myotubes, (2) to establish whether AMP-activated protein kinase (AMPK) and protein kinase B –PKB- (Akt) pathways are involved in this effect. In addition, the effects of these polyphenols on mitochondrial biogenesis and fatty acid oxidation were analysed. Myotubes from healthy donors were cultured for 24 h with either 0.1 μM of RSV or with 10 μM of Q. Glucose metabolism, such as glycogen synthesis, glucose oxidation, and lactate production, were measured with D[U-14C]glucose. β-oxidation using [1–14C]palmitate as well as the expression of key metabolic genes and proteins by Real Time PCR and Western blot were also assessed. Although RSV and Q increased pgc1α expression, they did not significantly change either glucose oxidation or β-oxidation. Q increased AMPK, insulin receptor substrate 1 (IRS-1), and AS160 phosphorylation in basal conditions and glycogen synthase kinase 3 (GSK3β) in insulin-stimulated conditions. RSV tended to increase the phosphorylation rates of AMPK and GSK3β. Both of the polyphenols increased insulin-stimulated glycogen synthesis and reduced lactate production in human myotubes. Thus, physiological doses of RSV or Q may exhibit anti-diabetic actions in human myotubes.
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Bouayed, Jaouad, i Torsten Bohn. "Exogenous Antioxidants—Double-Edged Swords in Cellular Redox State: Health Beneficial Effects at Physiologic Doses versus Deleterious Effects at High Doses". Oxidative Medicine and Cellular Longevity 3, nr 4 (2010): 228–37. http://dx.doi.org/10.4161/oxim.3.4.12858.
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The balance between oxidation and antioxidation is believed to be critical in maintaining healthy biological systems. Under physiological conditions, the human antioxidative defense system including e.g., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and others, allows the elimination of excess reactive oxygen species (ROS) including, among others superoxide anions (O2.-), hydroxyl radicals (OH.), alkoxyl radicals (RO.) and peroxyradicals (ROO.). However, our endogenous antioxidant defense systems are incomplete without exogenous originating reducing compounds such as vitamin C, vitamin E, carotenoids and polyphenols, playing an essential role in many antioxidant mechanisms in living organisms. Therefore, there is continuous demand for exogenous antioxidants in order to prevent oxidative stress, representing a disequilibrium redox state in favor of oxidation. However, high doses of isolated compounds may be toxic, owing to prooxidative effects at high concentrations or their potential to react with beneficial concentrations of ROS normally present at physiological conditions that are required for optimal cellular functioning. This review aims to examine the double-edged effects of dietary originating antioxidants with a focus on the most abundant compounds, especially polyphenols, vitamin C, vitamin E and carotenoids. Different approaches to enrich our body with exogenous antioxidants such as via synthetic antioxidants, diets rich in fruits and vegetables and taking supplements will be reviewed and experimental and epidemiological evidences discussed, highlighting that antioxidants at physiological doses are generally safe, exhibiting interesting health beneficial effects.
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Elahi, Maqsood M., Yu Xiang Kong i Bashir M. Matata. "Oxidative Stress as a Mediator of Cardiovascular Disease". Oxidative Medicine and Cellular Longevity 2, nr 5 (2009): 259–69. http://dx.doi.org/10.4161/oxim.2.5.9441.
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During physiological processes molecules undergo chemical changes involving reducing and oxidizing reactions. A molecule with an unpaired electron can combine with a molecule capable of donating an electron. The donation of an electron is termed as oxidation whereas the gaining of an electron is called reduction. Reduction and oxidation can render the reduced molecule unstable and make it free to react with other molecules to cause damage to cellular and sub-cellular components such as membranes, proteins and DNA. In this paper, we have discussed the formation of reactive oxidant species originating from a variety of sources such as nitric oxide (NO) synthase (NOS), xanthine oxidases (XO), the cyclooxygenases, nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase isoforms and metal-catalyzed reactions. In addition, we present a treatise on the physiological defences such as specialized enzymes and antioxidants that maintain reduction-oxidation (redox) balance. We have also given an account of how enzymes and antioxidants can be exhausted by the excessive production of reactive oxidant species (ROS) resulting in oxidative stress/nitrosative stress, a process that is an important mediator of cell damage. Important aspects of redox imbalance that triggers the activity of a number of signaling pathways including transcription factors activity, a process that is ubiquitous in cardiovascular disease related to ischemia/reperfusion injury have also been presented.
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Sun, Yi, Wen-Jia Zhang, Xin Zhao, Ren-Pei Yuan, Hui Jiang i Xiao-Ping Pu. "PARK7 protein translocating into spermatozoa mitochondria in Chinese asthenozoospermia". REPRODUCTION 148, nr 3 (wrzesień 2014): 249–57. http://dx.doi.org/10.1530/rep-14-0222.
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PARK7 (DJ1) is a multifunctional oxidative stress response protein that protects cells against reactive oxygen species (ROS) and mitochondrial damage. PARK7 defects are known to cause various physiological dysfunctions, including infertility. Asthenozoospermia (AS), i.e. low-motile spermatozoa in the ejaculate, is a common cause of human male infertility. In this study, we found that downregulation of PARK7 resulted in increased levels of lipid peroxide and ROS, decreased mitochondrial membrane potential, and reduced mitochondrial complex I enzyme activity in the spermatozoa from AS patients. Furthermore, it was observed that PARK7 was translocated into the mitochondria of damaged spermatozoa in AS. Finally, we examined the oxidative state of PARK7 and the results demonstrated the enhancement of oxidation, expressed by increased sulfonic acid residues, the highest form of oxidation, as the sperm motility decreased. Taken together, these results revealed that PARK7 deficiency may increase the oxidative stress damage to spermatozoa. Our present findings open new avenues of therapeutic intervention targeting PARK7 for the treatment of AS.
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Ando, Chika, i Yasujiro Morimitsu. "A proposed antioxidation mechanism of ergothioneine based on the chemically derived oxidation product hercynine and further decomposition products". Bioscience, Biotechnology, and Biochemistry 85, nr 5 (21.01.2021): 1175–82. http://dx.doi.org/10.1093/bbb/zbab006.
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ABSTRACT Ergothioneine (ERGO), a thiohistidine betaine, exists in various fungi, plants, and animals. Humans take in ERGO from their diet. ERGO is a strong biological antioxidant, but there are only a limited number of reports about its redox mechanism. The purpose of this study was to clarify the oxidation mechanism of ERGO. Reactions of ERGO with chemical oxidants were performed. The oxidation products of ERGO were analyzed by nuclear magnetic resonance and liquid chromatography-mass spectrometry (LC-MS). The major product of oxidation of ERGO by hydrogen peroxide in physiological conditions was identified as hercynine (histidine betaine). One molecule of ERGO was able to reduce 2 molecules of hydrogen peroxide. Hercynine was found to react with the more potent oxidant hypochlorite. One unstable decomposition product was detected by LC-MS. As a result, a mechanism of oxidation of ERGO, and hence its physiological antioxidant activity, was developed.
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Xinastle-Castillo, Luis Omar, i Abraham Landa. "Physiological and modulatory role of thioredoxins in the cellular function". Open Medicine 17, nr 1 (1.01.2022): 2021–35. http://dx.doi.org/10.1515/med-2022-0596.
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Abstract Thioredoxins (TRXs) are a class of ubiquitous and multifunctional protein. Mammal cells present three isoforms: a cytosolic and extracellular called thioredoxin 1 (TRX1), a mitochondrial (TRX2), and one specific in spermatozoids (TRX3). Besides, a truncated form called TRX80 exists, which results from the post-translational cleavage performed on TRX1. TRXs’ main function is to maintain the reduction–oxidation homeostasis of the cell, reducing the proteins through a thiol-disulfide exchange that depends on two cysteines located in the active site of the protein (Cys32-X-X-Cys35 in humans). In addition, TRX1 performs S-nitrosylation, a post-translational modification of proteins that depends on cysteines of its C-terminal region (Cys62, Cys69, and Cys73 in human TRX1). These modifications allow the TRXs to modulate the protein function and participate in regulating diverse cellular processes, such as oxidative stress, transcription, signaling cascades, apoptosis, inflammation, and immunologic response. This points out the crucial relevance of TRXs for cell function, signaling it as a strategic target for the treatment of many diseases and its possible use as a therapeutic factor.
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Guzmán, M., C. Bijleveld i M. J. H. Geelen. "Flexibility of zonation of fatty acid oxidation in rat liver". Biochemical Journal 311, nr 3 (1.11.1995): 853–60. http://dx.doi.org/10.1042/bj3110853.
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Periportal and perivenous hepatocytes were isolated from rats subjected to different treatments that induce (starvation, cold exposure) or depress (refeeding after starvation) hepatic fatty acid oxidation. These experiments were designed to determine factors that may be involved in creating and maintaining the asymmetrical distribution of this metabolic pathway in the acinus of the liver. The uneven distribution of mitochondrial [14C]-palmitate oxidation within the acinus (i) was very flexible and changed markedly with the physiological status of the animal (periportal/perivenous ratio: 1.5, 2.0, 1.0 and 0.4 for fed, starved, refed and cold-exposed animals respectively), (ii) coincided with a similar zonation of carnitine palmitoyltransferase I activity in fed as well as in cold-exposed animals, (iii) was paralleled by a comparable zonation of mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase activity in starved animals, and (iv) was not determined by zonal differences in any of the following parameters: sensitivity of carnitine palmitoyltransferase I to malonyl-CoA, intracellular concentration of malonyl-CoA, fatty acid synthesizing capacity, acetyl-CoA carboxylase activity, fatty acid synthase activity or relative content of the two hepatic acetyl-CoA carboxylase isoforms. Unlike mitochondrial oxidation, peroxisomal [14C]palmitate oxidation was always zonated towards the perivenous zone of the liver irrespective of the physiological status of the animal. The data presented show that changes in the acinar distribution of mitochondrial long-chain fatty acid oxidation involve specific long-term mechanisms under different physiological conditions.
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Monirujjaman, Md, i Afroza Ferdouse. "Metabolic and Physiological Roles of Branched-Chain Amino Acids". Advances in Molecular Biology 2014 (19.08.2014): 1–6. http://dx.doi.org/10.1155/2014/364976.
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Branch chain amino acids (BCAAs) have unique properties with diverse physiological and metabolic roles. They have functions other than simple nutrition. Different diseases including metabolic disease lead to protein loss, especially muscle protein. Supplementation of BCAAs promotes protein synthesis and reduces break down, as well as improving disease conditions. They are important regulators of mTOR signaling pathway and regulate protein synthesis as well as protein turnover. BCAAs facilitate glucose uptake by liver and SK muscle and also enhance glycogen synthesis. Oxidation of BCAAs seems to be beneficial for metabolic health as their catabolism increases fatty acid oxidation and reduces risk of obesity. BCAAs are also important in immunity, brain function, and other physiological aspects of well-being. All three BCAAs are absolutely required for lymphocyte growth and proliferation. They are also important for proper immune cell function. BCAAs may influence brain protein synthesis, and production of energy and may influence synthesis of different neurotransmitters. BCAAs can be used therapeutically and future studies may be directed to investigating the diverse effects of BCAAs in different tissues and their signaling pathways.
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Schmalhausen, Elena V., i Vladimir I. Muronetz. "An Uncoupling of the Processes of Oxidation and Phosphorylation in Glycolysis". Bioscience Reports 17, nr 6 (1.12.1997): 521–27. http://dx.doi.org/10.1023/a:1027356106330.
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Data on alterations of the properties of glyceraldehyde-3-phosphate dehydrogenase upon oxidation of its functional groups are reviewed; a mechanism of uncoupling of oxidation and phosphorylation in glycolysis is considered. Possible ways of regulating uncoupling, and the physiological importance of this process, are discussed.