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1
O'Hagan, C. E. "Physiological catalysts of LDL oxidation". Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396887.
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Bozac, Anna Elena. "Determining exogenous glucose oxidation during moderate exercise". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28736.
Testo completoAbstract (sommario):
The purpose of this study was to determine the quantity of a glucose drink oxidized during cycle ergometer exercise at 60% VO₂max for 75 minutes. A second purpose was to determine if the glucose drink improved sprint time to exhaustion at 90% VO₂max after 75 minutes of exercise. Six trained male cyclists (VO₂max > 60 ml•kg⁻¹•min•¹) exercised on three occasions during which they ingested either water ad lib (W), ¹³C-cornsyrup (100 g, 2.02 M) + water ad lib (CS), or NaH¹²CO₃/NaH¹³CO₃ mixture (5 mg•kg⁻¹, 1% ¹³C-enriched) + water ad lib (B). Treatments B and CS were ingested after 5 minutes of cycling at 60% VO₂max. During exercise, there was no difference between treatments in plasma lactate response, changes in plasma volume, sprint time to exhaustion, or in respiratory exchange ratio (RER), VO₂, or VCO₂. RER showed a significant decline (p< .01) from 5 minutes (1.00±0.05, X±SD) to 75 minutes (0.96±0.05), and VO₂ showed a significant positive shift (p< .01) from 3.15(±0.29) to 3.52(±0.45) l•min⁻¹. A transient rise in plasma glucose was observed with CS. Changes from rest in ¹³C/¹²C ratio (∂13C) showed a significant increase (p< .01) following CS. Peak glucose oxidation rate was 7.26 g•15 min⁻¹ which occurred after 75 minutes. Total dose of exogenous ¹³C-glucose recovered as ¹³CO₂ (above baseline) was 22%. These observations suggest that (1) during moderate exercise of 75 minutes duration, oxidation of exogenous glucose occurs within 15 minutes but contributes marginally to total carbohydrate utilization as RER continued to fall with or without CS, and (2) sprint time to exhaustion after 75 minutes of cycling is not improved with glucose ingestion.Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
3
Chang, Hui. "Oxidative stress in the retina an experimental study in the rat /". Lund : Dept. of Ophthalmology, University Hospital, Lund University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39725792.html.
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Kerry, Nicole Louise. "The effect of natural dietary antioxidants on low density lipoprotein oxidation and atherosclerosis /". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phk418.pdf.
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Rein, Neil Berthold. "Biological sulphide oxidation in heterotrophic environments". Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1003978.
Testo completoAbstract (sommario):
Acid mine drainage is a major environmental pollution concern associated with the mining of sulphide-containing ore bodies. Both physicochemical and biological options have been investigated for the treatment of acid mine drainage with recent interest in biological processes targeting low-cost and passive treatment applications. All acid mine drainage biological treatment processes are based to some extent on the activity of sulphate reducing bacteria, and their ability to reduce sulphate to sulphide in the presence of a range of carbon and electron donor sources. A portion of the sulphide produced may be consumed in the precipitation of heavy metals present in the mine drainage. Residual sulphide must be removed, not only due to its toxicity, but especially to prevent its reoxidation to sulphate where salinity reduction is a target of the treatment process. The partial oxidation of sulphide to elemental sulphur is an option that has received considerable attention and both physicochemical and biological options have been investigated. Biological processes have substantial potential cost advantages and run at ambient temperatures and pressures. However, the oxidation of sulphide to elemental sulphur is poised over a narrow redox range and process control to maintain optimum conditions remains a serious problem. In addition little has been reported in the literature on process control of sulphide oxidation to elemental sulphur, in the heterotrophic conditions prevailing in the reaction environment following sulphate reduction. This study undertook an investigation of biological sulphide oxidation under heterotrophic conditions in order to establish the effect of organic compounds on biological sulphide oxidation, and to determine whether the presence of organics, and associated heterotrophic oxygen consumption, may be manipulated to maintain the defined redox conditions required for the production of elemental sulphur. Biological sulphide oxidation under heterotrophic conditions was investigated in a series of flask experiments. Based on these results three different reactor configurations, a Fixed-Film Trickle Filter Reactor, Submerged Fixed-Film Reactor and a Silicone Tubular Reactor were used to investigate sulphur production. The flask studies indicated that organics, and associated heterotrophic metabolism in the presence of excess oxygen in the sulphide oxidation reaction environment, did contribute to the poising of redox conditions and thereby enabling the production of elemental sulphur. While the Fixed-Film Trickle Filter Reactor was found to be redox unstable, probably due to excess oxygen ingress to the system, a reduced oxygen challenge in the Submerged Fixed-Film Reactor configuration was found to be more successful for production of elemental sulphur. However, due to the production of a predominantly filamentous sulphur producing microbial population, recovery of sulphur from the column was intermittent and unpredictable. Extended residence times for produced sulphur on the column increased the likelihood for its eventual oxidation to sulphate. The Silicone Tubular Reactor was found to support a vigorous sulphide oxidising biofilm and produced elemental sulphur effectively. Electron microscopic studies showed that this occurred as both biologically produced sulphur and, probably mainly, as crystalline sulphur in the ortho-rhomic form. Given the linear extension of the sulphur production reaction environment it is was possible to investigate the sequence of the reaction mechanism in grater detail than is possible in mixed systems. Based on these findings a model explaining sulphur production under heterotrophic conditions has been proposed and is presented. The commercial implications of the development have also been noted.
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Collins, Tracey Helen. "Investigation into the Effects of Oxidative Stress on Reproductive Development". The University of Waikato, 2007. http://hdl.handle.net/10289/2364.
Testo completoAbstract (sommario):
Nuclear transfer (NT), or cloning, which is the transfer of a donor nucleus to a recipient enucleated oocyte, has been successfully achieved to produce viable offspring in many species. The process is very inefficient, as reprogramming of the donor nucleus is required, and losses are high throughout development. Placentation abnormalities are a common feature amongst cloned animals. Incomplete nuclear reprogramming and erroneous epigenetic imprinting may contribute to aberrant protein transcription and DNA mutations, affecting mitochondrial metabolism and inducing cellular stress. In vitro produced embryos under high oxygen culture conditions may also suffer oxidative stress, with the resulting reactive oxygen species causing mitochondrial DNA mutations and cellular stress similar to clones. In this study, expression of oxidative stress protein markers (Hsp60, SOD2, Hsp70) in NT cotyledons were compared to artificial insemination (AI) at different time points of gestation (days 50, 100, and 150). As a continuum of the oxidative stress investigation in cloned cotyledons, in vitro produced embryos were cultured under 20% oxygen compared to the control 7% oxygen laboratory standard culture, with oxidative stress protein markers examined between the groups at blastocyst stage (day 7) and day 15. Embryo morphology was also observed to determine apparent physiological differences between the treatment and control embryos. No previous studies to date have investigated the developmental effects of oxidative stress in day 15 bovine embryos. The significant differences in oxidative stress proteins observed at several time points in the NT and AI groups were not repeatable, possibly due to sample freeze/thaw degradation. Morphological differences observed between embryos cultured in 20% oxygen and control groups were visually apparent, although not quantified. At day 15 manganese superoxide dismutase expression was significantly lower in the 20% group compared to control. The 20% oxygen group did not show higher heat shock protein 60 expression than control, however the same results have been observed in another study at blastocyst stage. The results of this study suggest that the effect of oxidative stress on embryonic development is evident yet inconclusive in bovine NT cotyledons, however does not appear apparent in day 15 embryos following culture in 20% oxygen.
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Chen, Yuan-Han. "The active site chemistry of factor inhibiting HIF-1, coordination, bonding, and reaction". Amherst, Mass. : University of Massachusetts Amherst, 2009. http://scholarworks.umass.edu/dissertations/AAI3372258/.
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Yi, Dong-Hui Chemistry Faculty of Science UNSW. "The Study of Biomarkers of Protein Oxidative Damage and Aging by Mass Spectrometry". Awarded by:University of New South Wales. School of Chemistry, 1999. http://handle.unsw.edu.au/1959.4/17636.
Testo completoAbstract (sommario):
The physiologically important free radicals, nitrogen monoxide and superoxide, can combine to form the reactive intermediate peroxynitrite. Peroxynitrite can react with proteins and their constituent amino acids, such as tyrosine, resulting in protein peroxidation, oxidation and nitration. The nitration of proteins, assessed by the analysis of 3-nitrotyrosine, is a proposed index of pathophysiological activity of peroxynitrite. The aim of the work was to investigate the reaction products between peroxynitrite and protein, develop an assay for 3-nitrotyrosine and measure its levels in biological samples. To study the amino acid products arising from the reaction of peroxynitrite and protein, both liquid chromatography (LC) and gas chromatography (GC) combined with mass spectrometry (MS) were adopted. Approaches to 3-nitrotyrosine assay development were first, to take advantage of the intrinsic sensitivity of electron capture negative ionization GC-MS. Secondly, to avoid possible artefactual problems associated with the derivatisation step in GC-MS, an assay for 3-nitrotyrosine based on combined LC-MS-MS was developed. When a selection of peptides was exposed to peroxynitrite under physiological conditions in vitro, the hydrolysis products showed that 3-nitrotyrosine was the major product. Detectable minor products were 3,5-dinitrotyrosine and DOPA. The GC-MS assay was found to be fraught with difficulty due to artefactual formation of 3-nitrotyrosine. In order to quantify and correct for artefact formation, this complication was approached by incorporating a second isotopomer. This method, however, was confounded by large errors that reduced the overall sensitivity. Either negative or zero levels of endogenous 3-nitrotyrosine were found in tested samples after correction for artefact formation. The LC-MS-MS assay was then used to analyse 3-nitrotyrosine levels in a range of biological samples, including human plasma from healthy volunteers, synovial fluid samples from arthritis patients and tissue extracts from a mouse model of amyotropic lateral sclerosis. In contrast to published data, 3-nitrotyrosine levels were found to be below the limit of detection (1 pg/????L, 10 pg o/c) for all samples - a result somewhat consistent with the negative GC-MS data. It is suggested that the high 3-nitrotyrosine levels previously reported in the literature might reflect artefactual generation of 3-nitrotyrosine and that other approaches to assessing pathophysiological nitration should be sought in future.
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Telles, Scott Gerard. "Change in zinc permeability of lipid bilayers as a function of fluidity and oxidation". Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1061869.
Testo completoAbstract (sommario):
The main goal in my project was find out if the rate of zinc crossing the bilayer was either due to the fluidity of vesicles or the level of oxidation of the vesicles.To measure the oxidation a simple procedure called the TBA Test was used to measure each PC tested. The fluidity measurement was a calculation using the temperature the vesicles went from gel to liquid crystalline phase and the experimental temperature.Measuring the rate at which zinc crossed the bilayer was done using spectral changes that occur as zinc binds with APIII, a metal chelator entrapped inside the vesicles. To measure these rates we used k', the rate constant at which zinc is crossing the bilayer at a certain concentration and k, the second order diffusion rate constant which is the slope of k' vs. [Zn].The rates at which zinc was crossing the bilayer for each PC was then compared to the fluidity and oxidation levels for each PC. There was no direct correlation between the rates and fluidity but there was a good linear correlation between the rates and oxidation.So it seemed as if oxidation was the main reason zinc was crossing the bilayer so we wanted to see if our measurements could be obtained by biological cells. The comparison showed that rates obtained by biological cells can only be matched by the vesicle models when there oxidation levels are found to be high.In conclusion we believe that the reason zinc is crossing the bilayer is due to oxidation that occurs to the vesicle and as oxidation increases so do the rates at which zinc crosses the bilayer.Department of Chemistry
10
Wright, Adam. "Investigations of singlet oxygen-mediated amino acid, peptide and protein oxidation". Thesis, The University of Sydney, 2002. https://hdl.handle.net/2123/27830.
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Osborn, Anna. "Measurements of Human Plasma Oxidation". Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1426.
Testo completoAbstract (sommario):
The oxidation of lipids and antioxidants has been extensively studied in human plasma but little attention has been given to how plasma proteins are oxidised. Proteins make up the majority of biomolecules in cells and plasma and therefore are the most likely reactants with oxidants and free radicals. Previous studies in the laboratory had shown that peroxyl radicals generated by the thermolytic decay of 2-azobis (2-amdinopropane) dihydrochloride (AAPH) generated significant amounts of protein hydroperoxides, but only after a six hour lag period. In this study the existence of the six hour lag period was confirmed and shown by dialysis of the plasma to be due to the presence of low molecular weight antioxidants. The addition of both uric acid and ascorbic acid to the dialysed plasma restored the lag phase suggesting that in vivo these antioxidants act to prevent protein hydroperoxide formation. Lipid oxidation was also observed in the plasma but only after a two hour lag phase. This was the first time lipid oxidation has been observed in the absence of protein oxidation. The lipid lag phase was also abolished by dialysis of the plasma and restored by the addition of ascorbic acid and uric acid. The kinetics of tocopherol loss suggests that the tocopherol radicals act to inhibit lipid oxidation by transferring the electrons to the water-soluble ascorbate. The loss of ascorbate appears to cause the formation of a tocopherol radical mediate the lipid peroxidation process. Overall the data shows ascorbic acid scavenging the peroxyl radicals while uric acid acts to reduce the overall AAPH generated radical flux. In a separate investigation, the production of protein-bound DOPA (PB-DOPA) on albumin during X-ray radiolysis and copper mediate Fenton oxidation was investigated using a fluorescence based derivatisation method (ED-DOPA), which was compared with the more specific acid hydrolysis and HPLC analysis method. The ED-DOPA method consistently gave a much higher reading that the HPLC based methods, suggesting that the ED-DOPA method was measuring DOPA plus DOPA oxidation products. This was confirmed by oxidising X-ray radiolysis generated PB-DOPA with Cu++ to cause DOPA oxidation. The Cu++ treatment drastically increased the level of signal given by the ED-DOPA assay while HPLC analysis showed all the DOPA had been oxidised.
12
Bjorklund, Chad Christopher. "The effects of nucleosome core particle packaging on DNA charge transport". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/c_bjorklund_120606.pdf.
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Little, Laura Grace. "Response of a NEIL1 deficient murine epithelial cell line to chromate". CONNECT TO THIS TITLE ONLINE, 2008. http://etd.lib.umt.edu/theses/available/etd-04172008-090537/.
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Pradhan, Arati S. "Diffusion of zinc through oxidized lipid bilayers". Virtual Press, 2000. http://liblink.bsu.edu/uhtbin/catkey/1166400.
Testo completoAbstract (sommario):
Egg phosphatidylcholine was oxidized by atmospheric oxygen under UV light for 16 hours, and the oxidized products formed were fractionated with high-pressure liquid chromatography in reverse phase. Three fractions that appeared at retention times of 19 minutes, 21 minutes and 24 minutes respectively (fraction 19, fraction 21 and fraction 24) were isolated and stabilized by reduction with triphenylphosphine. Zinc diffusion across 1-palmitoyl-2 oleoyl-sn-glycero-3-phosphocholine (POPC) liposome bilayers mixed with the isolated oxidized fractions was measured. The rate constant for zinc diffusion through the POPC liposome was highest in fraction 19 followed by fraction 21 and fraction 24.NMR data suggests that all oxidized fractions were derived from the major egg polyunsaturated PC, 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine. The primary oxidized product, fraction 24 contains a mixture of isomers in which the linoleoyl group has formed the 9-hydroxy-10,12-trans-cis diene and trans-trans diene or the 13-hydroxy12,10-trans-cis diene and trans-trans diene. The primary oxidized products on further oxidation, result in secondary oxidized products, contained in fraction 21 and fraction 19.Experimental data indicates that the major components of fraction 21 are the 9-hydroxy12,13-epoxy-l0-trans-monoene (and 13-hydroxy-9,10-epoxy-11-trans-monoene) and the major components of fraction 19 are the 9,12,13-trihydroxy-l0-trans-monoene (and 9,10,13-trihydroxy-1 l-trans-monoene).Department of Chemistry
15
Levy, Mark A. "The role of dietary zinc and CuZnSOD gene expression in response to oxidative stress in the lung and brain". Columbus, OH : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1054069625.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xiii, 155 p.: ill (some col.). Includes abstract and vita. Advisor: Tammy Bray, Nutrition Program. Includes bibliographical references (p. 139-155).
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Jiao, Yongqin Asimow Paul David Newman Dianne K. "Physiological and mechanistic studies of phototropic Fe(II) oxidation in purple non-sulfur bacteria /". Diss., Pasadena, Calif. : California Institute of Technology, 2007. http://resolver.caltech.edu/CaltechETD:etd-01242007-141030.
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Stroup, Laurie B. "Radioactive pyruvate oxidation and the effects of fatty acid inhibition in the aging rat". Virtual Press, 1989. http://liblink.bsu.edu/uhtbin/catkey/560276.
Testo completoAbstract (sommario):
To investigate the possible changes in pyruvate oxidation during the rapid growth period in an animal model, the oxidation of radioactive labeled pyruvate was measured in mitochondria isolated from the gastrocnemius muscle of Sprague--Dawley rats between 4 and 16 weeks of age. The influence of the fatty acid derivative palmitylcarnitine, as an inhibitor of pyruvate oxidation, was also tested.The gastrocnemius muscle was removed from anesthesized animals at 4, 8 and 16 weeks of age. Isolated mitochondria from the muscle samples were incubated with C1--14C] pyruvate and E1-14C] pyruvate + palmitylcarnitine in a KC1 medium. The decarboxylation of pyruvate was measured by the evolution of radioactive labeled carbon dioxide. Pyruvate oxidation significantly (p .; 0.0001) increased from ages 4 to 16 weeks. The initial low rate of pyruvate oxidation was attributed to the residual metabolic effects of the pre-weaned animal' high-fat diet. The subsequent increase in the capacity of pyruvate oxidation was then explained by the shift in the animaldiet to high-carbohydrate lab chow. These results may also be attributed to the maturation of the hindlimb muscle fibers during this period: the differentiation of predominately red, oxidative fibers to an increase in the percentage of white, glycolytic fibers, common in the adult hindlimb. The fatty acid derivative, palmitylcarnitine, failed to inhibitpyruvate oxidation at the level of decarboxylation. This finding supports the proposal that fatty acids do not inhibit glucose oxidation directly, but instead suppress glycogen breakdown. Thus, the findings indicate an increase in the capacity for- pyruvate oxidation during the rapid growth period without inhibition by the fatty acid derivative, palmitylc_arnitine.Department of Biology
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Bédard, Charles. "Methane and carbon monoxide oxidation in a lake with an anoxic hypolimnion". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64032.
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Chow, Ka-man. "The antioxidant effect of lycium fruit extract on hyperglycemia-induced oxidative stress in human liver and rat muscle cell lines". View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36186132.
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Kanase, Nilesh. "The impact of oxidative stress and potential antioxidant therapy on function and survival of cultured pancreatic β-islet cells". Thesis, University of the Highlands and Islands, 2011. https://pure.uhi.ac.uk/portal/en/studentthesis/the-impact-of-oxidative-stress-and-potential-antioxidant-therapy-on-function-and-survival-of-cultured-pancreatic-islet-cells(ec0cd703-3902-4410-8c58-e7c7e49f33e7).html.
Testo completoAbstract (sommario):
Dietary antioxidant curcumin derived from turmeric has been suggested to decrease the risk of many chronic diseases. Much of the existing data for curcumin stem from experiments performed at supra-physiological concentrations (μM-mM) that are impossible to attain through oral ingestion. It was therefore hypothesized that curcumin at low plasma achievable concentration, though itself not acting as a direct antioxidant might up-regulate the intracellular antioxidants and thus helping combat oxidative stress and protect β-islet cells. The results indicated that Curcumin, DMC and BDMC were able to scavenge hydroxyl radicals, but showed little scavenging ability against superoxide and nitric oxide radicals. Nanomolar concentrations of curcuminoids easily prevented the deleterious effects of H2O2 in pancreatic β-islet RINm5F cells. Non of the curcuminoids showed a detrimental effect on insulin secretion, but the model did not allow assessment of any potential positive effect on insulin secretion. The findings confirmed that nanomolar concentrations of curcumin offered protection in pancreatic β-islet cells against H2O2-indicated damage by modulating the proportion of oxidised GSH (GSSG): reduced GSH in the favour of GSH and the increasing the activity of SOD. This increase in GSH and SOD levels was, at least in part, on account of an increase in GR, SOD-1 and SOD-2 gene expression. The intracellular mechanism driving this modulation of antioxidant gene was, by virtue of blocking the H2O2 induced NF-κB activation.
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McNulty, Richard. "Regulation of tissue oxygen levels in the ocular lens". Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050922.134414/index.html.
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Takeshita, Shigeru. "Genetic and physiological studies to discover novel anti-diabetic agents". 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215223.
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Boon, Ai Ching. "Physiological Effects of Bilirubin: Protection from Protein Oxidation, Kidney Dysfunction and Regulation of Hepatic Lipid Metabolism". Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367250.
Testo completoAbstract (sommario):
Clinical evidence indicates that hyperbilirubinaemic individuals with Gilbert’s syndrome (GS) are at reduced risk of developing cardiovascular and chronic kidney disease. This thesis consists of five manuscripts which review and explore various mechanisms whereby unconjugated bilirubin (UCB) may prevent cardiovascular disease (CVD) and chronic kidney disease (CKD). The first study of this thesis followed and extended upon the candidate’s Master of Medical Research program. Forty-four age, gender and body mass index matched Gilbert’s syndrome (GS) and healthy controls were recruited and blood was analysed for lipid parameters and plasma antioxidants/oxidative stress status. Individuals with GS had elevated unconjugated bilirubin (UCB), reduced thiol and glutathione concentrations compared to controls. Oxidative stress biomarkers including oxidised glutathione, protein carbonyl and oxidised low-density lipoprotein concentration were significantly reduced in GS and were negatively correlated with UCB concentrations.
To better characterise bilirubin’s ability to inhibit atherogenesis based upon its antioxidant capacity, study two investigated the susceptibility of plasma to myeloperoxidase induced oxidation was tested in hyperbilirubinaemic humans and rodents. Plasma with exogenous UCB supplementation (15.6-250 µM) inhibited HOCl (100 µM) and (100 nM)-hydrogen peroxide (H2O2; 50-100 µM) induced chloramine formation in a dose dependent manner. Chloramine formation was significantly reduced in GS plasma and Gunn rat serum and which was negatively correlated with UCB concentrations. Chloramine decomposition, including protein carbonyl and malondialdehyde formations were significantly reduced in a dose-dependent manner. This study suggested that UCB could inhibit protein and lipid oxidation induced by the formation of biologically relevant radicals/oxidants in vitro.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
Full Text
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Miley, Timothy Brian. "Studies of the respiratory chain of Methylococcus capsulatus (bath)". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1252.
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Liu, Jing Xin. "Investigation of the protecting roles of the deacetylase SIRT3 against nonalcoholic fatty liver disease, and its natural activator,honokiol, against oxidative injury in hepatocytes". Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952500.
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Fredriksson, Åsa. "On the role of protein oxidation and heat shock proteins in senescence and fitness /". Göteborg : Göteborg University, 2006. http://www.loc.gov/catdir/toc/fy0708/2006421399.html.
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Ghosh, Avik Kumar. "Charge migration and one-electron oxidation at adenine and thymidine containing DNA strands and role of guanine N1 imino proton in long range charge migration through DNA". Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-05132007-000502/.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.Wartell, Roger, Committee Member ; Bunz, Uwe, Committee Member ; Doyle, Donald, Committee Member ; Fahrni, Christoph, Committee Member ; Schuster, Gary, Committee Chair.
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Roberts, Lezah Wilette. "Effect of Netropsin on One-electron Oxidation of DNA". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7228.
Testo completoAbstract (sommario):
One electron oxidation of DNA has been studied extensively over the years. When a charge is injected into a DNA duplex, it migrates through the DNA until it reaches a trap. Upon further reactions, damage occurs in this area and strand cleavage can occur. Many works have been performed to see what can affect this damage to DNA. Netropsin is a minor groove binder that can bind to tracts of four to five A:T base pairs. It has been used in the studies within to determine if it can protect DNA against oxidative damage, caused by one-electron oxidation, when it is bound within the minor groove of the DNA. By using a naphthacenedione derivative as a photosensitizer, several DNA duplexes containing netropsin binding sites as well as those without binding sites, were irradiated at 420 nm, analyzed, and visualized to determine its effect on oxidative damage. It has been determined netropsin creates a quenching sphere of an average of 5.8 * 108 Šwhether bound to the DNA or not. Herein we will show netropsin protects DNA against oxidative damage whether it is free in solutions or bound within the minor groove of a DNA duplex.
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Cook, Denham Grant. "The effects of harvesting procedures on physiological and biochemical properties of chinook salmon (Oncorhynchus tshawytscha) white muscle prior to and during frozen storage". Thesis, University of Canterbury. Biological Sciences, 2008. http://hdl.handle.net/10092/1514.
Testo completoAbstract (sommario):
The object of this thesis was to investigate the role of two different harvest protocols on the post mortem physiology of Chinook salmon, and associated deteriorative processes that occur during frozen storage of the white muscle tissue. The two different harvest methods employed, termed 'rested' and 'exercised', were selected because of the contrasting levels of activity of the animal prior to, and upon, slaughter. While the latter represents conventional harvest techniques Rested and exercised harvesting protocols produced tissue in significantly different physiological states. Immediately post harvest, rested tissue maintained high metabolic energy stores of ATP and glycogen within the tissue, with low concentrations of tissue and plasma lactate. Exercised tissue exhibited near depleted concentrations of ATP and glycogen and a marked metabolic acidosis and lactate accumulation. When frozen immediately post harvest, rested white muscle tissue stored at -19℃ showed no significant changes in these metabolite concentrations over a six month period of profiling. However, during storage of rested tissue at -9℃, hydrolysis of ATP and glycogen with no coincident increase in lactate was observed. No significant changes in metabolite levels were observed within exercised tissue stored at -19 and -9℃, owing to the lack of metabolic energy stores. Transfer of tissue from frozen (-80 and -19℃) to chilled (-1 and +4℃) temperatures witnessed a rapid depletion of tissue ATP and glycogen stores, with rapid increases in tissue lactate concentrations. This metabolic activity was more significant in rested tissue owing to the larger concentrations of metabolic energy stores. This metabolic activity was identified to occur between the temperatures of -3 and -1.5℃ and occurred abruptly (i.e. ATP concentrations depleting in less than one hour) in time. During frozen storage (-19℃ and -9℃), harvest treatment had no significant effect on lipid oxidation processes. However, rested tissue showed a significant ability to retard lipid oxidation processes once removed from frozen storage and placed at chilled temperatures. Throughout six months storage at -19℃ storage, harvest treatment had a significant effect on the rate of protein denaturation as rested tissue consistently held higher concentrations of soluble protein over the storage period. No significant effect was observed between treatments in the rate of protein denaturation during one month frozen (-19℃) then chilled (+4℃) storage. In a supplementary frozen (-80℃) then chilled (-1℃) storage experiment, post mortem storage of rested, whole fish, at chilled (+5℃) temperatures prior to white muscle excision and freezing, was compared to rested and exercised tissue in which the white muscle had been excised and then frozen immediately post harvest. In this experiment rested tissue exposed to a 6 or 24 hour post mortem chilled storage period demonstrated significant retardation of lipid oxidation processes when compared to rested white muscle tissue that was excised and frozen immediately post harvest. Further comparison of the six and 24 hour post mortem stored tissue showed a significant increase in lipid oxidation products after 21 and 24 days chilled storage, respectively. Comparison of results from the six and 24 hour post mortem storage experiment were bordering on significance (p=0.083), warranting further investigation on the effect of post mortem storage of rested tissue on lipid oxidation processes.
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Parker, Nicole Renee. "The role of kynurenine and UV light in lens protein modification". Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060720.111305/index.html.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--University of Wollongong, 2005.Typescript. EMBARGOED - This thesis is subject to a 12 month embargo (07/03/06 to 07/03/07) and may only be viewed and copied with the permission of the author. For further information please Contact the Archivist. Includes bibliographical references: leaf 236-266.
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Chow, Ka-man, e 鄒嘉敏. "The antioxidant effect of lycium fruit extract on hyperglycemia-induced oxidative stress in human liver and rat muscle cell lines". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36186132.
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Winger, Alison Marie. "Impact of 4-hydroxy-2-nonenal in Arabidopsis mitochondria /". Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0121.
Testo completo
33
Wang, Xiao Suo. "A novel ELISA to detect methionine sulfoxide-containing apolipoprotein A-I". Connect to full text, 2009. http://hdl.handle.net/2123/5423.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Sydney, 2009.Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Pathology, Faculty of Medicine. Title from title screen (viewed Sept. 30, 2009) Includes bibliography. Also available in print form.
34
Farhat, Elie. "Physiological Responses of Goldfish and Naked Mole-Rats to Chronic Hypoxia: Membrane, Mitochondrial and Molecular Mechanisms for Metabolic Suppression". Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42595.
Testo completoAbstract (sommario):
Chronic hypoxia is a state of oxygen limitation that is common in many aquatic and terrestrial environments. Metabolic suppression is an essential strategy that is used by hypoxia-tolerant champions such as goldfish and naked mole-rats to cope with prolonged low oxygen. This thesis examines the physiological processes used by goldfish and naked mole-rats to survive in low oxygen environments. It proposes a novel mechanism - the remodeling of membrane lipids - to reduce ATP use and production. Temperature (homeoviscous adaptation), diet (natural doping in migrant birds) and body mass (membrane pacemaker of metabolism) have an impact on the lipid composition of membranes that, in turn, modulates metabolism. In chapters 2 and 3 of this thesis, I demonstrate that vertebrate champions of hypoxia tolerance undergo extensive changes in membrane lipid composition upon in vivo exposure to low oxygen. These changes and those observed in hibernating mammals can promote the downregulation of Na⁺/K⁺-ATPase (major ATP consumers), mitochondrial respiration capacity [OXPHOS (phosphorylating conditions), proton leak (non-phosphorylating conditions), cytochrome c oxidase], and energy metabolism (β-oxidation and glycolysis) as discussed in chapters 3 and 4. A common membrane signal regulating the joint inhibition of ion pumps and channels could be an exquisite way to preserve the balance between ATP supply and demand in hypometabolic states. In chapter 5, I show that the reduction in ATP turnover is also orchestrated by mechanisms that involve post-translational and post-transcriptional modifications and epigenetic changes. Membrane remodeling, together with these more traditional molecular mechanisms, could work in concert to cause metabolic suppression.
35
Liu, Chia-chi. "Oxidation of ascorbate by protein radicals in simple systems and in cells". Phd thesis, Australia : Macquarie University, 2007. http://hdl.handle.net/1959.14/16746.
Testo completoAbstract (sommario):
Thesis (PhD) -- Macquarie University, Division of Environmental and Life Sciences, Dept. of Chemistry and Biomolecular Sciences, 2007.Bibliography: leaves 295-322.
Generation of peroxide groups in proteins exposed to a wide variety of reactive oxygen species (ROS) requires an initial formation of protein carbon-centred or peroxyl free radicals, which can be reduced to hydroperoxides. Both protein radicals and protein hydroperoxides are capable of oxidizing important biomolecules and thus initiate biological damage. In this study, we investigated the inhibition of protein hydroperoxide formation by ascorbate and GSH in gamma-irradiated HL-60 cells.--We used HL-60 cells as a model for general protection of living organisms by ascorbate (Asc) and glutathione (GSH) from the deleterious effects of protein hydroperoxides generated by radicals produced by gamma radiation. Measurement by HPLC indicated that incubation of HL-60 cells with Asc in the presence of ascorbate oxidase resulted in the accumulation of intracellular Asc. The intracellular Asc levels were lowered by irradiation, demonstrating intracellular consumption of Asc by the radiation-generated radicals. Exposure of HL-60 cells to increasing gamma irradiation doses resulted in increasing accumulation of protein peroxides in the cells. This was measured by the FOX assay. A significant decrease in intracellular protein hydroperoxides was noted when the cells were treated with ascorbic acid before irradiation. A dose-dependent protective effect of Asc was observed. Asc loading also provided strong protection from radiation-generated protein hydroperoxides independently of the composition of the external medium, showing that only the radicals formed within the cells were effective in oxidizing the cell proteins. Similarly, protein peroxidation was inhibited in cells with enhanced levels of GSH and increased when the intracellular GSH concentration was reduced. These findings indicate that ascorbate and GSH are important antioxidants in protecting cells from oxidative stress associated with the generation of protein hydroperoxide.
Mode of access: World Wide Web.
xxix, 322 leaves ill
36
Winger, Alison Marie. "Impact of 4-hydroxy-2-nonenal in Arabidopsis mitochondria". University of Western Australia. Biochemistry and Molecular Biology Discipline Group, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0121.
Testo completoAbstract (sommario):
[Truncated abstract] A range of biotic and abiotic stresses increase levels of reactive oxygen species (ROS) in plants due to perturbations of chloroplast and mitochondrial metabolism and the generation of ROS in defence responses. The polyunsaturated fatty acids of membrane lipids are susceptible to ROS induced peroxidation yielding various aldehydes, alkenals and hydroxyalkenals including the cytotoxic compound 4-hydroxy- 2-nonenal (HNE). HNE has the potential to cause substantial oxidative damage in cells via its reactivity with sulfhydryl groups of cysteine (Cys) and lipoic acid, the imidazole group of histidine (His) and the ?-amino group of lysine (Lys) protein residues. Analysis of the components of the plant respiratory electron transport chain to HNE revealed a particular susceptibility to inhibition of activity of the alternative oxidase (Aox). Incubation with HNE prevented dimerisation of Aox protein, suggesting that one site of modification was the conserved cysteine residue involved in dimerisation and activation of this enzyme (Cys1). However, a naturally occurring isoform of Aox lacking Cys1 and unable to dimerise, LeAox1b from tomato, was equally sensitive to HNE inhibition, showing that other amino acid residues in Aox also interact with HNE and are likely responsible for inactivation of the enzyme. ... The broader impact of HNE on the whole Arabidopsis mitochondrial proteome was examined by use of various 2-dimensional gel separation techniques coupled with use of HNE-adduct antibodies. 32 proteins involved in a number of mitochondrial functions were found to be susceptible to modification by HNE, including components of the electron transport chain, the TCA cycle, as well as proteins involved amino acid metabolism and stress-responses. Implications of modification of these proteins by HNE are discussed. As HNE is produced in vivo during oxidative stress, the profile of mitochondrial targets of HNE was examined from Arabidopsis cell cultures exposed to various oxidative stress inducers. Menadione and hydrogen peroxide induced oxidative stress throughout the cell, while antimycin A initiated a mitochondrial targeted stress. A differential profile of mitochondrial proteins was observed to be modified by HNE in the various treatments. These results also showed that induction of stress within a whole cell can impact lipid peroxidation within the mitochondria. Overall, this work showed the presence and production of HNE in plant cells, and that HNE, both exogenous and endogenous, has the ability to modify a specific subset of mitochondrial proteins. In several cases this HNE modification was shown to have functional or structural consequences.
37
Wang, Xiao Suo. "A Novel ELISA to Detect Methionine Sulfoxide−Containing Apolipoprotein A−I". Thesis, The University of Sydney, 2009. http://hdl.handle.net/2123/5423.
Testo completoAbstract (sommario):
Atherosclerosis manifests a state of increased oxidative stress characterized by comparable lipid and protein oxidation in the affected arterial wall. While oxidative modification of low density lipoprotein (LDL) has been extensively studied, increasing attention has been focused recently on oxidation of high-density lipoproteins (HDL) and its functional consequences in relation to atherosclerosis. Oxidative modification is thought to generate “dysfunctional” HDL that has lost anti-atherosclerotic activities, including the ability to remove cholesterol from lipid-laden cells. Therefore, there has been much interest in the detection of oxidized HDL. Unfortunately, available methods to detect oxidized HDL are limited at present, in part because oxidative modification of HDL is a complex process and ‘oxidized HDL’ is not a chemically defined entity. What is known however is that conversion of methionine (Met) residues of apolipoprotein (apo) A-I to methionine sulfoxide (MetO) is a process that occurs commonly as HDL undergoes oxidative modification. For example, human apoA-I+16 (containing MetO86 or MetO112) and apoA-I+32 (MetO86 plus MetO112) are generated when apoA-I reacts with lipid hydroperoxides formed as a consequence of the lipoprotein being exposed to 1e−oxidants. The formation of MetO in apoA−I induced by 2e−oxidants (i.e., hydrogen peroxide, hypochlorous acid or myeloperoxidase/hydrogen peroxide/chloride system) is associated with an impaired ability of the apolipoprotein to facilitate reactions relevant to reverse cholesterol transport. In addition, a previous study has suggested the plasma content of apoA-I+32 to be increased in certain subjects that have an increased risk to develop cardiovascular disease (CVD). Moreover, the MetO content in circulating, HDL−associated apoA−I is elevated in type 1 diabetes, a disorder commonly associated with increased oxidative stress and a risk factor for atherosclerosis. Therefore, in the present study, an existing HPLC method was applied to HDL samples from the Fletcher−Challenge study, a nested case control study, to test the potential usefulness of MetO-containing apoA-I as a marker of oxidative stress and/or CVD in a general population. Plasma samples whose HDL contained detectable apoA-I+16 and/or apoA-I+32 had significantly elevated levels of F2-isoprostanes, a marker of in vivo lipid oxidation, consistent with MetO-containing apoA-I being a useful marker of in vivo protein oxidation. Despite this however, there was no significant difference between controls and cases in their concentrations of HDL apoA-I+16 and apoA-I+32 or F2-isoprostanes, suggesting that markers of protein and lipid oxidation are not associated with the risk of coronary heart disease (CHD) in this general population. A limitation of the Fletcher−Challenge study was that only 22% of the 534 HDL samples analyzed contained apoA-I+16 and/or apoA-I+32. In addition, the HPLC−based method used is expensive and time−consuming and may lack the sensitivity needed for apolipoproteins to clinical studies. Thus, a mouse monoclonal anti-human apoA-I+32 antibody (MOA−1) was raised using HPLC−purified apoA-I+32 as immunogen. A sensitive ELISA was then developed using a commercial anti-human apoA-I monoclonal antibody as capture and biotinylated MOA−1 as detection antibody, respectively. The assay detected lipid−free HPLC−purified human apoA-I+32 in a concentration-dependent manner and with a significantly lower limit of detection (i.e., 3 ng/mL) than the HPLC method (1 μg/mL). The ELISA also detected lipid-free apoA-I modified by 2e-oxidants (hydrogen peroxide, hypochlorous acid, peroxynitrite), and HDL oxidized by 1e- or 2e-oxidants and present in buffer or human plasma. Moreover, the extent of recognition of MetO by MOA−1 increased with increasing numbers of MetO in apoA−I, as assessed by the experiments with H2O2−oxidized forms of apoA−I mutants, in which one, two or three Met residues were replaced with Leu. Their detection was concentration-dependent, reproducible, and exhibited a linear response over a physiologically plausible range of concentrations of oxidized HDL. In contrast, MOA-I failed to recognize native apoA-I, native apoA-II, apoA-I modified by hydroxyl radicals or metal ions, or LDL modified by 2e-oxidants. Furthermore, MOA−1 did not detect other Met−containing proteins oxidized by either hypochlorous acid or hydrogen peroxide. Taken together, the results showed that recognition of oxidized proteins by MOA−1 is limited to MetO contained in apoA−I. Finally, in a pilot study, plasma samples obtained from subjects with coronary artery disease (CAD) proven by angiography, and samples from CAD patients undergoing percutaneous coronary intervention (PCI) were analyzed by the ELISA. The preliminary data obtained showed elevated levels of MetO-containing apoA-I in plasma samples of CAD patients compared to those of corresponding control subjects. Unexpectedly, levels of MetOcontaining apoA-I decreased PCI compared to before PCI. A possible explanation for these results is that HDL−associated apoA−I become displaced by acute phase proteins, such as serum amyloid A, in response to PCI. In summary, the ELISA developed here specifically detects apoA-I containing MetO in HDL and human plasma. As such it may provide a useful tool for investigating the relationship between oxidized HDL and CAD.
38
Hernández, García Iker. "Flavan-3-ol and ascorbate accumulation and oxidation in plants, and its physiological significance / Acumulación y oxidación de flavan-3-oles y ascorbato en plantas, y su significado fisiológico". Doctoral thesis, Universitat de Barcelona, 2007. http://hdl.handle.net/10803/948.
Testo completoAbstract (sommario):
Flavonoids have received much attention in biology and medicine because of their high in vitro antioxidant activities. However, little is known about the physiological significance of this capacities in plants under stress conditions, but for anthocyanins, which act as photoprotective screens. The final objective of the present work was to determine the role of the accumulation and oxidation of flavonoids in plants under abiotic stress conditions, and to compare it with that of a well known antioxidant: ascorbate. To accomplish this objective, a multi-disciplinary approach was applied, including plant physiology, biochemistry and molecular biology techniques. First, the total phenolic content of three Mediterranean species -Salvia officinalis (L), Melissa officinalis (L) and Cistus clusii (Dunal)- was analyzed as well as the changes they showed during a drought treatment. C. clusii plants showed the highest phenolic levels among the studied species, and these phenolics increased during the drought treatment. It is suggested that the biosynthesis of phenolics may serve as an alternative carbon, reduction equivalents and ATP sink. Second, the main antioxidant flavonoids in C. clusii leaf extreacts were identified to be (-)-epigallocatechin gallate (EGCG), (-)-epicatechin (EC) and (-)-epicatechin gallate (ECG). Levels of these flavan-3-ols increased during the drought treatment in a simmilar manner as ascorbate did, which moreover reduced the levels of its oxidized form, dehydroascorbate (DHA). It is suggested that aside ot the mentioned role as phenolics, flavan-3-ols may act as antioxidants in C. clusii plants under stress. Next, the role of these flavan-3-ols in different aged C. clusii plants in field conditions was studied. In this experiment it is shown that the accumulation of monomeric reduced flavan-3-ols is triggered by incident light (maximum radiation or photoperiod). Moreover, the accumulation of monomeric reduced, monomeric oxidized (quinones) and polymeric (proanthocyanidins) flavan-3-ols may serve also an alternative carbon, reduction equivalents and ATP sink as well as an antioxidant mechanism as plants age. Next, the oxidation of monomeric reduced flavan-3-ols to their respective quinones was studied in tea plants under severe drught stress. EC and EGCG oxidize to their respective quinones in such conditions, suggesting that EC and EGCG may act as membrane antioxidants. Finally, the role of ascorbate oxidation state in the apoplast as a cell signal was studied. Tobacco transgenic plants with shifted ascorbate oxidase activity modulated showed shifted transcript profile. Many cell preocesses were altered at gene expression levels upon shifting the ascorbate oxidation state in the apoplast, including H2O2 homeostasis, electron transport and stress responses. Moreover, Ca2+ is shown to be a key component of the ascorbate oxidation state signal transduction pathway to the nucleus.
In conclusion, in this study it is demonstrated the presence of EC, EGCG y ECG in C. clusii and that the levels of these flavan-3-ols increase with drought. These flavan-3-ols may serve as an alternative C, reduction equivalents and ATP sink. Flavan-3-ols accumulate in plants as they age, especially during streass periods. Flavan-3-ols are oxidized to their respective quinones under severe drought stress, particularly in tea plants, and they may act as membrane antioxidants. The oxidation state of the ascorbate in the apoplast acts as a cell signal regulating different processes within the symplast at gene expression levels, including H2O2 homeostasis.
39
Arstall, Margaret Anne. "Studies in myocardial ischaemia and infarction : effects of N-acetylcysteine on oxidative stress and myocardial salvage /". Title page, contents and summary only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09pha783.pdf.
Testo completo
40
Ahmadi, Sirous. "Monitoring muscle oxygenation and myoelectric activity after damage-inducing exercise". Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/2240.
Testo completoAbstract (sommario):
In this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.
41
Ahmadi, Sirous. "Monitoring muscle oxygenation and myoelectric activity after damage-inducing exercise". University of Sydney, 2007. http://hdl.handle.net/2123/2240.
Testo completoAbstract (sommario):
Doctor of PhilosophyIn this thesis, three experiments were conducted to monitor: (i) muscle oxygenation and electromyographic activity of the biceps brachii after exercise-induced muscle damage (ii) muscle oxygenation after downhill walking-induced muscle damage, and, (iii) muscle oxygenation following a bout of vigorous concentric exercise. Maximal eccentric exercise (EE) of biceps brachii resulted in significantly increased mean resting oxygen saturation and decreased deoxyhaemoglobin. During isometric contractions at 50% and 80% of subjects’ maximum voluntary torque (MVT), oxygen desaturation and resaturation kinetics and volume were significantly decreased after EE, and these declines were significantly prevalent over the following 6 days. Additionally, a significant shift in median frequency intercept (measured by electromyography; EMG) towards lower frequencies was observed during isometric contractions at both 50% and 80% MVT after EE in the exercised arm. After an exhaustive session of downhill walking, another form of EE, resting total haemoglobin and oxyhaemoglobin decreased. Furthermore, during isometric contractions at 30%, 50% and 80% of MVT, prolonged and significant increases were observed in oxygen desaturation and resaturation kinetics and volumes after ambulatory EE. In contrast to the two EE experiments, concentric contractions did not evoke any prolonged changes in muscle oxygenation. Collectively, the findings of this thesis revealed significant and prolonged changes in muscle oxygenation at rest and during exercise, following sessions of strenuous eccentric exercise. Although not clear, the possible mechanism responsible for the changes in muscle oxygenation after EE could be increased resting muscle oxygen utilization due to probable muscle damage and a subsequent requirement of energy demanding repair processes. Concentric exercise resulted in fatigue, but it did not affect muscle oxygenation. Although a prolonged reduction in EMG median frequency intercept was observed after EE, this was not closely time-associated with the biochemical, anthropometric or functional markers of muscle damage.
42
Mizdrak, Jasminka. "Human lens chemistry: UV filters and age-related nuclear cataract". Australia : Macquarie University, 2007. http://hdl.handle.net/1959.14/16855.
Testo completoAbstract (sommario):
"A thesis submitted in partial fulfillment of the requirements for the award of the degree of Doctor of Philosophy".Thesis (PhD) -- Macquarie University, Division of Environmental and Life Sciences, Dept. of Chemistry and Biomolecular Sciences, 2007.
Bibliography: p. 243-277.
Introduction -- A convenient synthesis of 30HKG -- Facile synthesis of the UV filter compounds 30HKyn and AHBG -- Synthesis, identification and quantification of novel human lens metabolites -- Modification of bovine lens protein with UV filters and related metabolites -- Effect of UV light on UV filter-treated lens proteins -- Conclusions and future directions.
The kynurenine-based UV filters are unstable under physiological conditions and undergo side chain deamination, resulting in α,β-unsaturated carbonyl compounds. These compounds can react with free or protein bound nucleophiles in the lens via Michael addition. The key sites of the UV filters kynurenine (Kyn) and 3-hydroxykynurenine (3OHKyn) modification in human lenses include cysteine (Cys), and to a lesser extent, lysine (Lys) and histidine (His) residues. Recent in vivo studies have revealed that 3-hydroxykynurenine-O-β-D-glucoside (3OHKG) binds to Cys residues of lens crystallins in older normal human lenses. As a result of this binding, human lens proteins become progressively modified by UV filters in an age-dependent manner, contributing to changes that occur with the development of age-related nuclear (ARN) cataract. Upon exposure to UV light, free UV filters are poor photosensitisers, however the role of protein-bound species is less clear. It has been recently demonstrated that Kyn, when bound to lens proteins, becomes more susceptible to photo-oxidation by UV light. Therefore, the investigation of 3OHKG binding to lens proteins, and the effect of UV light on proteins modified with 3OHKG and 3OHKyn, were major aims of this study. As a result of the role of these compounds as UV filters and their possible involvement in ARN cataract formation, it is crucial to understand the nature, concentration and modes of action of the UV filters and their metabolites present in the human lenses. Therefore, an additional aim was to investigate human lenses for the presence of novel kynurenine-based human lens metabolites and examine their reactivity.--As 3OHKG is not commercially available, to conduct protein binding studies, an initial aim of this study was to synthesise 3OHKG (Chapter 2). Through the expansion and optimisation of a literature procedure, 3OHKG was successfully synthesised using commercially available and inexpensive reagents, and applying green chemistry principles, where toxic and corrosive reagents were replaced with benign reagents and solvent-free and microwave chemistry was used. A detailed investigation of different reaction conditions was also conducted, resulting in either the improvement of reaction yields or reaction time compared to the literature method. Applying the same synthetic strategy, and using key precursors from the synthesis of 3OHKG, the UV filters 3OHKyn and 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid-O-β-D-glucoside (AHBG), were also successfully synthesised (Chapter 3).
Chapter 4 describes the investigation of both normal and cataractous human lenses in an attempt to identify novel human lens metabolites derived from deaminated Kyn and 3OHKyn (Chapter 4, Part A). Initially, 4-(2-aminophenyl)-4-oxobutanoic acid (AHA), glutathionyl-kynurenine (GSH-Kyn), kynurenine yellow (Kyn yellow), 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid (AHB), glutathionyl-3-hydroxykynurenine (GSH-3OHKyn) and 3-hydroxykynurenine yellow (3OHKyn yellow) were synthesised and human lenses were examined for their presence. AHA and AHB were synthesised from similar precursors to those used in the synthesis of 3OHKG, while the GSH adducts and yellow compounds were synthesised from Kyn and 3OHKyn via base induced deamination. Following isolation and structural elucidation, AHA, AHB and GSH-Kyn were confirmed as novel human lens metabolites. They were quantified in low pmol/mg lens (dry mass) levels in normal and cataractous lenses of all ages, while GSH-3OHKyn, Kyn yellow and 3OHKyn yellow were not detected. In contrast to AHA, the lens metabolites AHB, GSH-Kyn and GSH-3OHKyn were found to be unstable at physiological pH. The spectral properties of these compounds suggest that they may act as UV filters. --Chapter 4 (Part B) also describes the identification and characterisation of a novel human lens UV filter, cysteinyl-3-hydroxykynurenine -O-β-D-glucoside (Cys-3OHKG). An authentic standard was synthesised via Michael addition of cysteine to deaminated 3OHKG. Cys-3OHKG was detected in low pmol/mg lens (dry mass) levels in normal lenses only after the 5th decade of life and was absent in cataractous lenses. Cys-3OHKG showed rapid decomposition at physiological pH.
Chapter 5 describes the identification and quantification of amino acids involved in covalent binding of 3OHKG to lens proteins. Model studies with bovine lens proteins and 3OHKG at pH 7.2 and 9.5 were undertaken. The amino acid adducts were identified via total synthesis and spectral analysis, and subsequently quantified upon acid hydrolysis of the modified lens proteins. Under both pH conditions, 3OHKG was found to react with lens proteins predominantly via Cys residues with low levels of binding also detected at Lys residues. Comparative studies with Kyn (pH 9.5) and 3OHKyn (pH 7.2 and 9.5) resulted in modified lens proteins at Cys residues, with only minor modification at Lys residues at pH 9.5. The extent of modification was found to be significantly higher at pH 9.5 in all cases. His adducts were not identified. 3OHKG-, Kyn- and 3OHKyn-modified lens proteins were found to be coloured and fluorescent, resembling those of aged and ARN cataractous lenses. In contrast, AHB and AHA, which can not form α,β-unsaturated carbonyl compounds, resulted in non-covalent modification of lens proteins. AHB may contribute to lens colouration and fluorescence as further reactions of this material yielded species that have similar characteristics to those identified from 3OHKyn modification. These species are postulated to arise via auto-oxidation of the o-aminophenol moiety present in both 3OHKyn and AHB.--In Chapter 6, the potential roles of 3OHKG and 3OHKyn, and the related species AHA and AHB, in generating reactive oxygen species and protein damage following illumination with UV light was examined. The UV filter compounds were examined in both their free and protein-bound forms. Kyn-modified proteins were used as a positive control. Exposure of these compounds to UV light (λ 305-385 nm) has been shown to generate H2O2 and protein-bound peroxides in a time-dependent manner, with shorter wavelengths generating more peroxides. The yields of peroxides were observed to be highly dependent on the nature of the UV filter compound and whether these species were free or protein bound, with much higher levels being detected with the bound species. Thus, protein-bound 3OHKyn yielded higher levels of peroxide than 3OHKG, with these levels, in turn, higher than for the free UV filter compounds. AHB-treated lens proteins resulted in formation of low but statistically significant levels of peroxides, while AHA-treated lens proteins resulted in insignificant peroxide formation. The consequences of these photochemical reactions have been examined by quantifying protein-bound tyrosine oxidation products (3,4-dihydroxyphenylalanine [DOPA], di-tyrosine [di-Tyr]) and protein cross-linking. 3OHKG-modified proteins gave elevated levels of di-Tyr, but not DOPA, whereas 3OHKyn-modified protein gave the inverse. DOPA formation was observed to be independent of illumination and most likely arose via o-aminophenol auto-oxidation. AHB- and AHA-treated lens proteins resulted in statistically insignificant di-Tyr formation, while a light independent increase in DOPA was observed for both samples. Both reducible (disulfide) and non-reducible cross-links were detected in modified proteins following illumination. These linkages were present at lower levels in modified, but non-illuminated proteins, and absent from unmodified protein samples.
This work has provided an optimised synthetic procedure for 3OHKG and other lens metabolites (Chapters 2 and 3). Four novel lens metabolites have been identified and quantified in normal and cataractous human lenses (Chapter 4). Subsequent experiments, described in Chapter 5, identified the major covalent binding sites of 3OHKG to lens proteins, while AHA and AHB showed non-covalent binding. Further work described in Chapter 6 showed that protein-bound 3OHKG, Kyn and 3OHKyn were better photosensitisers of oxidative damage than in their unbound state. Together, this research has provided strong evidence that post-translational modifications of lens proteins by kynurenine-based metabolites and their interaction with UV light appear, at least in part, responsible for the age-dependent colouration of human lenses and an elevated level of oxidative stress in older lenses. These processes may contribute to the progression of ARN cataract.
Mode of access: World Wide Web.
xxxix, 308 p. ill. (some col.)
43
Ferreira, Thalita Montoril. "Biochemical and physiological responses of sorghum plants submitted to salt stress". Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17086.
Testo completoAbstract (sommario):
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThe plants are frequently exposed to environmental stresses, which cause imbalances in physiological and biochemical metabolism. This work aimed to study the physiological and biochemical changes of plant forage sorghum (Sorghum bicolor) genotype CSF18, depending on the time of salt stress. The seeds were sown in vermiculite moistened with distilled water, in a greenhouse conditions, and after seven days, the seedlings were transferred to trays with Hoagland solution diluted 1:2. After seven days, treatment was established stress saline (75 mM NaCl), one group of plants kept in nutrient solution in the absence of salt (control). Samples were collected at 0, 5, 10 and 15 days after the initiation of stress. We evaluated the growth, gas exchange, contents and chlorophyll fluorescence, the concentration of organic solutes (proline, N-amino solutes, soluble carbohydrates, soluble proteins and polyamines free) and inorganic (Na+, Cl- and K+), as well as the activity of ribonuclease (RNase). We also determined the activities of catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaicol peroxidase (GPX), as well as the levels of H2O2, ascorbate and glutathione in leaves and roots. Salinity reduced plant growth, being observed reductions in leaf area, and fresh and dry weights of shoots and roots. This was related to a reduction in net photosynthesis rate, even with the transpiration rate and stomatal conductance is not affected. The salinity increased contents of Na+ and Cl- in plant tissues, but the K+ decreased. The levels of organic solutes in leaves and roots increased, particularly at five and ten days of stress. The polyamines putrescine and spermidine were found at very low levels in both leaves and roots, while spermine was not detected in any analyzed portion of the plant. Although putrescine increased in salt stress, some must have contributed to the osmotic adjustment, however, their participation in oxidative protection was suggested. The salinity increased the activity of SOD, APX and GPX and the redox state of ascorbate, especially in the leaves, and this is related to the maintenance of H2O2 levels and increased protection against oxidative damage. The CAT showed the main enzyme remover H2O2 in the leaves while the roots that role was played by GPX. The RNase activity in leaves, stems and roots of sorghum increased in stress conditions, but their role in protection against the deleterious effects of salinity is not yet fully understood. In general, the data show that the antioxidative system (enzymatic and non-enzymatic) can play a key role in the acclimation of sorghum plants to salt stress, and that the reduction of plant growth was probably due to inhibition of biochemical phase of photosynthesis, caused by accumulation of toxic ions, Na+ and Cl-, reducing the relation K+/Na+ at levels harmful to the metabolism
As plantas estÃo freqÃentemente expostas a estresses ambientais, os quais causam desequilÃbrios no metabolismo fisiolÃgico e bioquÃmico. Este trabalho teve por objetivo estudar as alteraÃÃes fisiolÃgicas e bioquÃmicas de plantas de sorgo forrageiro [Sorghum bicolor (L.) Moench], genÃtipo CSF 18, em funÃÃo do tempo de exposiÃÃo ao estresse salino. As sementes foram semeadas em vermiculita umedecida com Ãgua destilada, em casa de vegetaÃÃo e, apÃs sete dias, as plÃntulas foram transferidas para bandejas com soluÃÃo nutritiva de Hoagland diluÃda 1:2. ApÃs sete dias, foi estabelecido o tratamento de estresse salino (NaCl a 75 mM), sendo um grupo de plantas mantido em soluÃÃo nutritiva na ausÃncia de sal (controle). As coletas foram realizadas aos 0, 5, 10 e 15 dias apÃs o inÃcio do estresse. Avaliou-se o crescimento, as trocas gasosas, os teores e a fluorescÃncia da clorofila, os teores de solutos orgÃnicos (prolina, N-aminossolÃveis, carboidratos solÃveis, proteÃnas solÃveis e poliaminas livres) e inorgÃnicos (Na+, Cl- e K+), bem como a atividade da ribonuclease (RNase). TambÃm foram determinadas as atividades das enzimas catalase (CAT), dismutase do superÃxido (SOD), peroxidase do ascorbato (APX) e peroxidase do guaicol (GPX), bem como os teores de H2O2, glutationa e ascorbato em folhas e raÃzes. O estresse salino reduziu o crescimento das plantas, sendo observadas reduÃÃes na Ãrea foliar, e nas matÃrias fresca e seca da parte aÃrea e das raÃzes. Isto foi relacionado com a reduÃÃo na taxa de fotossÃntese lÃquida, mesmo com a taxa de transpiraÃÃo e a condutÃncia estomÃtica nÃo sendo afetadas. A salinidade aumentou os teores de Na+ e Cl nos tecidos das plantas, porÃm, diminuiu os de K+. Os teores de solutos orgÃnicos em folhas e raÃzes aumentaram, principalmente aos cinco e dez dias de estresse. As poliaminas putrescina e espermidina foram encontradas em nÃveis muito baixos tanto em folhas como raÃzes, enquanto a espermina nÃo foi detectada em qualquer dos tecidos analisados. Embora a putrescina tenha aumentado em condiÃÃes de estresse salino, pouco deve ter contribuÃdo para o ajustamento osmÃtico, contudo, foi sugerida sua participaÃÃo na proteÃÃo oxidativa. A salinidade aumentou a atividade das enzimas SOD, APX e GPX e o estado redox do ascorbato, especialmente nas folhas, sendo isto relacionado com a manutenÃÃo dos nÃveis de H2O2 e com o aumento da proteÃÃo contra os danos oxidativos. A CAT mostrou-se a principal enzima removedora de H2O2 nas folhas, enquanto nas raÃzes esse papel foi desempenhado pela GPX. A atividade da RNase, em folhas, colmos e raÃzes de sorgo aumentou em condiÃÃes de estresse, porÃm seu papel na proteÃÃo contra os efeitos deletÃrios da salinidade ainda nÃo està totalmente esclarecido. Em geral, os dados mostram que o sistema antioxidativo (enzimÃtico e nÃo-enzimÃtico) pode desempenhar papel fundamental na aclimataÃÃo das plantas de sorgo ao estresse salino e que os efeitos deletÃrios da salinidade no crescimento das plantas, devem-se, provavelmente, à inibiÃÃo da fase bioquÃmica da fotossÃntese, causada pelo acÃmulo de Ãons tÃxicos, Na+ e Cl-, reduzindo a relaÃÃo K+/Na+ a nÃveis prejudiciais ao metabolismo.
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Reilly, Kim. "Oxidative stress related genes in cassava post-harvest physiological deterioration". Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760766.
Testo completo
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Trevizani, Jéssica Luiza Bueno. "Descoloração e degradação do azo corante vermelho BR por ozonização". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1364.
Testo completoAbstract (sommario):
CAPESA indústria têxtil é responsável pela geração de efluentes com elevada carga orgânica, cor e toxicidade. O principal objetivo deste trabalho foi avaliar a eficiência de remoção de um corante azo-reativo (Vermelho BR) pelo processo de ozonização em variações de pH e concentração inicial do corante para duas soluções: solução aquosa acrescida de corante (Solução 1) e solução de efluente sintético acrescido de corante (Solução 2). Para tal, os ensaios foram realizados em pH 4 (ácido), pH 7 (neutro) e pH 10 (alcalino) e a concentração inicial do corante foi variada em 50, 100 e 150 mg/L. As coletas foram realizadas de 15 em 15 minutos e os parâmetros analisados para Solução 1 foram: temperatura, remoção de cor, turbidez, ozônio dissolvido, off-gas e ozônio consumido; para Solução 2, além desses parâmetros também foi analisada a remoção de matéria orgânica (DQO). O tempo de ozonização ocorreu até a remoção significativa da cor (>90%) e variou entre 60 e 240 min. A produção de ozônio utilizada neste trabalho foi a máxima obtida pelo gerador de 0,702 gO3/h em vazão máxima de ar (15 L/min). A eficiência máxima de transferência de ozônio para o líquido foi de 73% em meio alcalino (pH igual a 10) e mínimas em condições ácidas (pH igual a 4) para ambas as soluções analisadas. Através da aplicação do delineamento de composto central (DCC) e dos gráficos de superfície de resposta, pode-se verificar a influência dos fatores concentração inicial de corante (Fator 1) e pH (Fator 2) na variável resposta remoção de corante. Dessa forma pode-se observar que a influência da concentração inicial do corante é mais significativa do que a influência do pH na eficiência de remoção do corante. A eficiência máxima de remoção foi de 98% para Solução 1 e para Solução 2 em pH 10 e 4 respectivamente e com concentração inicial de corante de 50 mg/L. A fim de analisar a toxicidade das soluções, antes e após a ozonização, foram realizados testes de toxicidade aguda com o organismo teste Daphinia similis e verificou-se toxicidade em todas as amostras analisadas. Ao longo deste trabalho pode-se observar que a ozonização tem resultados eficientes na oxidação do corante têxtil Vermelho BR em todas as variações de pH e concentração de corante.
The textile industry is responsible for generating wastewater with high organic content, color and toxicity. The direct objective of this study was to evaluate the hum dye removal efficiency azo-Reactive (Red BR) by ozonation process in pH variations and initial dye concentration. For two solutions: dye plus aqueous solution (Solution 1) and synthetic effluent solution plus dye (Solution 2). To this end, tests were performed at pH 4 (acid), pH 7 (neutral) and pH 10 (alkaline) and the initial dye concentration varied among 50, 100 and 150mg / L As samples were performed from 15 to 15 minutes and the parameters were analyzed. for Solution 1 were: temperature, color removal, turbidity, dissolved ozone, off-gas and ozone consumed. For solution 2, besides these parameters, was also analyzed the removal of organic matter (COD). The rate of ozonation has occurred up to a significant removal of color (> 90%) and between 60 and 240 min.The Ozone production used in this work was a Maximum obtained with Generator 0702 GO3 / h in air flow Maximum (15 L / min). The Maximu m Efficiency of transfer Ozone to the net was 73% in alkaline medium (pH 10) and minimum under acidic conditions (pH 4) For both analyzed solutions. through the application of the central compound design (DCC) and Polling Surface Graphics, it is possible to check the initial dye concentration factors of influence (Factor 1) and pH (Factor 2) in the Variable Voting dye removal. This can be observed as forms of Influence of the initial dye concentration and more significant is that the influence of pH dye removal efficiency. Maximum efficiency removal was 98% For Solution 1 and 2 sat pH 10:04 and initial concentration of dye 50 mg / L. In order to analyze the toxicity of solutions, the before and after process of ozonation, tests were performed as toxicity test with the body similis daphinia and found toxicity at all samples. During this work, it was observed that the ozonation has results in efficient oxidation of dye textile Red BR in all pH variations and dye concentration.
46
Morse, Willis Michael. "Oxidative capacity of rat skeletal muscle with increased and decreased training". Virtual Press, 1986. http://liblink.bsu.edu/uhtbin/catkey/459904.
Testo completoAbstract (sommario):
Sixty-nine female Wistar rats were studied to determine if the oxidative capacity and glycogen concentration of skeletal muscle was affected by either an increase or decrease in training duration following a 9 wk program of treadmill running. Initially, 30 rats were randomly assigned to one of three sedentary control groups. Subgroups (N=10) of sedentary animals were kept inactive and were sacrificed at week 0 (Cl), week 9 (C2) and week 11 (C3) of the study. Thirty-nine rats were initially trained 5 days/wk for 9 wks using a standard exercise protocol. At the end of 9 wks of treadmill running, endurance trained animals were separated into four groups: 1) Eleven rats (ET) were killed. 2) Ten rats (CT) continued to train for 2 additional weeks following the same protocol and were killed at the end of 11 wks of training. 3) Ten rats (DT) decreased the duration of daily running by 66% and after 14 days were killed. 4) Eight rats (IT) increased the duration of daily running by 500% in an attempt to simulate overtraining in humans, and after 6 days were killed. The respiratory capacity (Qo2) and citrate synthase activity (CSA) of the soleus (SOL) and plantaris (PLANT) muscles were significantly increased (p< 0.05) over all control groups by nine weeks of treadmill running (ET). The Qo2 and CSA of CT rats were significantly higher than all control groups, and the PLANT CSA was significantly higher (p< 0.05) than ET rats. The SOL and PLANT Qo2 and CSA remained significantly higher (p< 0.05) than all control groups with fourteen days of decreased training. Six days of increased training significantly increased (p< 0.05) SOL and PLANT Qo2 and CSA over all control groups. In addition IT rats had SOL and PLANT CSA that were significantly higher (p< 0.05) than ET rats. The SOL and WV glycogen concentrations were unaffected by all training protocols. Only the CT and IT PLANT and liver had significantly more (p< 0.05) glycogen than all sedentary control groups. The results of this study indicate that the rat is a very adaptable animal, and to thoroughly study it as a possible model for the study of overtraining in humans would require an examination of various exercise protocols. In addition, the exercise-induced increase in the oxidative capacity of trained skeletal muscle is not readily reversible during decreased training.
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Santos, Gustavo Barbosa dos 1981. "Melatonina reduz o estresse oxidativo e as alterações cardiovasculares induzidas pelo estanozolol em ratos submetidos ao exercicio de natação". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314571.
Testo completoAbstract (sommario):
Orientador: Miguel Arcanjo AreasDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-15T12:08:35Z (GMT). No. of bitstreams: 1 Santos_GustavoBarbosados_M.pdf: 1865766 bytes, checksum: 33bc98691c7f175ef683408a35219198 (MD5) Previous issue date: 2010
Resumo: Esteróides androgênicos anabolizantes (EAA) são indicados clinicamente para promover aumento da síntese protéica após queimaduras, cirurgias, radioterapia, no tratamento contraceptivo, no hipogonadismo, na osteoporose, na sarcopenia relacionada à idade e à pacientes portadores de HIV. Por outro lado, o uso indiscriminado dos EAA, com intuito de aumentar o desenvolvimento muscular, o desempenho físico, a capacidade aeróbia, a tolerância ao treinamento de alta intensidade e até mesmo para fins estéticos, é crescente entre atletas e esportistas recreacionais. O uso abusivo de EAA está relacionado à toxicidade cardíaca e hepática em consequência do aumento do estresse oxidativo. Por outro lado, estudos apontam a melatonina como substância com significativa ação antioxidante, apresentando efeitos benéficos no tratamento de doenças cardíacas. Este trabalho teve por objetivo avaliar os efeitos da melatonina sobre biomarcadores do estresse oxidativo e parâmetros cardiovasculares e hepáticos em ratos adultos sedentários ou treinados com natação e tratados com estanozolol. Os ratos foram distribuídos nos seguintes grupos: sedentário (S), sedentário+estanozolol (SE), sedentário+estanozolol+melatonina (SEM), treinado (T), treinado+estanozolol (TE) e treinado+estanozolol+melatonina (TEM). Realizou-se avaliação eletrocardiográfica no início e ao final do período experimental (6 semanas), sendo, então, determinada a pressão arterial, atividade de enzimas antioxidantes e da fosfatase alcalina e histologia do coração e do fígado. Os resultados mostraram que o estanozolol provocou bradicardia, queda do peso relativo do fígado e aumento da atividade das enzimas superóxido dismutase cardíaca e hepática, catalase cardíaca e fostatase alcalina hepática. Quando associado ao treinamento, estanozolol aumentou a pressão arterial sistólica e diastólica, o peso relativo do coração, desviou o eixo elétrico cardíaco para esquerda e provocou alterações hepatotóxicas. A administração da melatonina nos ratos tratados com EST, por sua vez, impediu o aumento da pressão arterial sistólica e diastólica e da atividade das enzimas catalase cardíaca, fostatase alcalina hepática além de impedir o desvio do eixo elétrico cardíaco causado pela hipertrofia ventricular esquerda induzida pelo estanozolol. Além disso, melatonina reduziu as alterações nos hepatócitos induzidas pelo estanozolol. Concluímos que, em nossas condições experimentais, a melatonina atenuou os efeitos adversos ao sistema cardiovascular e ao fígado causados pelo uso de doses suprafisiológicas de estanozolol
Abstract: Anabolic androgenic steroids (AAS) are nominated for clinical use to promote protein synthesis after burns, surgery, radiotherapy, on contraceptive treatment, osteoporosis, hypogonadism, age-related sarcopenia and HIV patients. However, the indiscriminate use of ASS aiming to stimulate muscular development, physical performance, aerobic capacity, tolerance to high-intensity training and with aesthetic purpose is increasing among athletes and recreational sportsmen. The abusive use of ASS is related to oxidative stress-induced cardiac and hepatic toxicity. Nonetheless, many studies point to melatonin as a substance with antioxidant properties, with beneficial effects on cardiovascular diseases treatment. The purpose of this study was to assess melatonin's effects on oxidative stress biomarkers, cardiovascular and liver parameters in stanozolol-treated trained rats. Rats were divided into the following groups: sedentary (S), sedentary+stanozolol (SS), sedentary+stanozolol+melatonin (SSM), trained (T), trained+stanozolol (TS) and trained+stanozolol+melatonin (TSM). Electrocardiography assessment were performed at the beginning and at the end of experimental period, and then, blood pressure, antioxidant enzymes and phosphatase alkaline activities, heart and liver histology were determined. Stanozolol induced bradycardia, relative liver weight decreased and increased cardiac and liver superoxide dismutase, cardiac catalase and liver phosphatase alkaline activities. Stanazolol plus training induced increased systolic and diastolic blood pressure, relative heart weight, left cardiac axis deviation and toxic liver damage. Melatonin induced decreased systolic and diastolic blood pressure, cardiac catalase and liver phosphatase alkaline activities, and prevented stanazolol-induced left cardiac axis deviation. Furthermore, melatonin decreased stanozolol-induced liver damage. In conclusion, under our experimental conditions, the side effects of supraphysiology doses of stanozolol on liver and cardiovascular system are mitigated by melatonin
Mestrado
Fisiologia
Mestre em Biologia Funcional e Molecular
48
Osório, João Vasco de Carvalho. "Mucosal and physiological responses of Atlantic salmon (Salmo salar) in brackish water RAS following peracetic acid-based disinfection". Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2020. http://hdl.handle.net/10400.5/20695.
Testo completoAbstract (sommario):
Dissertação de Mestrado Integrado em Medicina VeterináriaPeracetic acid (PAA), a strong oxidative disinfectant, is effective against several microorganisms at low concentrations, requires short contact time and degrades rapidly into innocuous residues, thus considered a promising option for routine disinfection in aquaculture production. However, comprehensive knowledge of the impacts of the oxidant PAA on fish health is required for its safe application. This study documented the physiological impacts of periodic PAA exposure in Atlantic salmon (Salmo salar) post-smolts reared in brackish water recirculating aquaculture system. Salmon were exposed to PAA at a concentration of 1 mg/L every 3 days over 6 weeks. Three extensive tissue samplings were conducted (before exposure, 22 and 45 days of periodic PAA exposure). In addition, a stress test was performed before exposure and 45 days post-exposure to assess the effects of periodic exposure during a secondary stress encounter. There was no clear pattern on the changes in plasma stress parameters throughout the exposure trial, except with the glucose level, which significantly decreased over time. Oxidative stress was likely triggered by periodic oxidant exposure, as indicated by the documented significant increase in plasma antioxidants. PAA-induced expression of genes encoding for antioxidants, cytokines, heat shock proteins and mucins demonstrated a tissue-specific pattern: downregulation was observed in the gills and olfactory rosette, upregulation occurred in the skin, and no changes in the liver. Periodic oxidant exposure resulted in histological changes in key mucosal organs (olfactory rosette, skin and gills); pathological alterations were predominant in the gills where cases of epithelial lifting, hypertrophy, hyperplasia and lamellar clubbing were the most commonly identified. Lastly, periodic oxidant exposure did not alter the ability of salmon to mount robust physiological stress responses to a secondary stressor. Collectively, the present study demonstrated that periodic PAA exposure constituted an environmental stressor for which salmon were capable of mounting adaptive responses, both at the systemic and mucosal levels. In addition, periodic PAA exposure promoted the maintenance of stable microbiological water quality and did not affect the biofilter performance. The consequences of this disinfection protocol underscored the potential of PAA as a routine oxidant-based disinfection in salmon RAS production.
RESUMO - O ácido paracético (PAA), um desinfetante com fortes propriedades oxidantes, é eficaz contra diversos microrganismos a baixas concentrações, requer um curto tempo de contacto e degrada-se rapidamente em resíduos inócuos, sendo, portanto, considerado uma alternativa promissora para a desinfeção de rotina em aquacultura. No entanto, é necessário um extenso conhecimento relativo aos impactos do PAA na saúde dos peixes para garantir a sua utilização segura. Este estudo documentou as consequências fisiológicas da exposição periódica ao PAA em Salmão do Atlântico (Salmo salar) na fase “post-smolt”, produzido num sistema de recirculação em aquacultura (RAS) de água salobra. Os peixes foram expostos ao PAA a uma concentração de 1 mg/L a cada 3 dias durante 6 semanas. Foram realizadas três recolhas extensivas de tecidos (antes da exposição, e aos dias 22 e 45 de exposição periódica). Além disso, foi realizado um desafio de stress antes do início de exposição e no dia 45 de exposição para avaliar os efeitos da exposição periódica na resposta a um estímulo secundário de stress. Durante o estudo não foi observado nenhum padrão óbvio na evolução dos parâmetros plasmáticos de stress, excetuando os níveis de glucose, que desceram significativamente ao longo do tempo. O stress oxidativo foi induzido provavelmente pela exposição periódica ao oxidante, tal como indicado pelo aumento nos níveis de antioxidantes plasmáticos. A expressão dos genes que codificam antioxidantes, citoquinas, proteínas de choque térmico e mucinas revelou que existe um padrão tecidular específico em resposta ao PAA: foi registado um padrão de inibição nas brânquias e na roseta olfatória, um padrão de indução na pele, enquanto no fígado não foram registadas alterações. A exposição ao PAA provocou alterações histológicas nas brânquias, pele e roseta olfatória, sendo as alterações predominantemente observadas nas brânquias, onde as alterações mais comuns foram casos de edema epitelial, hipertrofia, hiperplasia e “lamelar clubbing”. A exposição periódica ao PAA não afetou a capacidade do salmão para estabelecer uma resposta fisiológica eficiente na presença de um estímulo indutor de stress. De forma geral, este estudo demonstrou que a exposição periódica ao PAA constituiu um estímulo stressante para o qual os peixes foram capazes de apresentar respostas adaptativas, tanto a nível sistémico como nas mucosas. Além disso, a exposição ao PAA promoveu a manutenção da qualidade microbiológica da água e não afetou a performance do biofiltro. As respostas observadas neste protocolo de desinfeção destacam o potencial do PAA como um desinfetante de rotina na produção de salmão em RAS.
N/A
49
Macvanin, Mirjana. "The Physiological Cost of Antibiotic Resistance". Doctoral thesis, Uppsala University, Department of Cell and Molecular Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3761.
Testo completoAbstract (sommario):
Becoming antibiotic resistant is often associated with fitness costs for the resistant bacteria. This is seen as a loss of competitiveness against the antibiotic-sensitive wild-type in an antibiotic-free environment. In this study, the physiological alterations associated with fitness cost of antibiotic resistance in vitro (in the laboratory medium), and in vivo (in a mouse infection model), are identified in the model system of fusidic acid resistant (FusR) Salmonella enterica serovar Typhimurium.
FusR mutants have mutations in fusA, the gene that encodes translation elongation factor G (EF-G). FusR EF-G has a slow rate of regeneration of active EF-G·GTP off the ribosome, resulting in a slow rate of protein synthesis. The low fitness of FusR mutants in vitro, and in vivo, can be explained in part by a slow rate of protein synthesis and resulting slow growth. However, some FusR mutants with normal rates of protein synthesis still suffer from reduced fitness in vivo. We observed that FusR mutants have perturbed levels of the global regulatory molecule ppGpp. One consequence of this is an inefficient induction of RpoS, a regulator of general stress reponse and an important virulence factor for Salmonella. In addition, we found that FusR mutants have reduced amounts of heme, a co-factor of catalases and cytochromes. As a consequence of the heme defect, FusR mutants have a reduced ability to withstand oxidative stress and a low rate of aerobic respiration.
The pleiotropic phenotypes of FusR mutants suggest that antibiotic resistance can be associated with broad changes in bacterial physiology. Knowledge of physiological alterations that reduce the fitness of antibiotic-resistant mutants can be useful in identifying novel targets for antimicrobial agents. Drugs that alter the levels of global transcriptional regulators such as ppGpp or RpoS deserve attention as potential antimicrobial agents. Finally, the observation that FusR mutants have increased sensitivity to several unrelated classes of antibiotics suggests that the identification of physiological cost of resistance can help in optimizing treatment of resistant bacterial populations.
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Carvalho, Marcia Eugenia Amaral de. "Integrated approach of anatomical, physiological and biochemical parameters for the study of tolerance mechanisms to cadmium in tomato accessions". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-09102017-172803/.
Testo completoAbstract (sommario):
Tomato (Solanum lycopersicum L.) consumption has increased every year due to the fruit attractiveness, several utilizations, and beneficial effects for human health. However, tomato fruits can accumulate a Cd concentration that exceeds the safety threshold for human consumption of vegetables, even when plants are grown in soil with acceptable Cd level. Cd is a non-essential, hazardous element to biological systems, triggering several diseases in humans. In plants, Cd disturbs the antioxidant machinery, changes the nutritional status, and impairs the photoassimilate production and/or partitioning, hence reducing fruit yield and quality. However, distinct tomato accessions can present contrasting tolerance degree to Cd toxicity, as detected by our group in previous studies. The use of these accessions is a powerful approach to identify strategies employed by plants to cope with Cdinduced challenges, and the acknowledgement of such strategies can be potentially used in breeding and biotechnological programs to improve fruit yield and quality in crops that were cultivated in contaminated fields. The set of studies that compose the present thesis aimed (i) to identify the main mechanisms for the contrasting tolerance degree to Cd-induced toxicity in tomato accessions after short and long-term Cd exposure; (ii) to evaluate the relationship among tolerance degree and fruits attributes in plants that were grown in Cd-containing soil, and (iii) to determine the transgenerational effects of Cd-induced stress. In the first experiment, nine tomato accessions with a varied tolerance degree, which was based on biomass accumulation, to Cd exposure were grown in hydroponic solution containing CdCl2 35 μM for 6 days. Avoidance of high Mg concentration in roots was identified as a plant strategy to mitigate Cd toxicity by preventing formation of root hairs. Regarding the mode of action of Cd toxicity, Mn excess in leaves, in addition to the high Cd concentration per se, seems to be coupled to leaf damages that are enhanced by the increased Zn and B concentrations in the photosynthetic tissues. In the second experiment, tolerant (Yoshimatsu) and sensitive (Tropic Two Orders) genotypes were grown in Cd-containing soil, in order to evaluated production parameters. After plant exposure to Cd, the tolerant genotype presented an increased fruit diameter, height and weight, when compared to the control plants. In both cultivars, Cd concentration varied according to the following descending order: roots = leaf blade > (floral receptacle, peduncle and sepals) > stem = fruit peel = fruit pulp. Moreover, data suggested that floral receptacle and its related-structures acted as a barrier to the Cd transportation to the fruits, but it was not enough to avoid Cd reaching the fruits. Furthermore, Cd exposure provoked remarkable reductions in the Mg concentration in roots of sensitive and tolerant genotypes, revealing that both tomato cultivars are able to employ this mechanism for plant acclimation to long-term Cd exposure. Considering such information, it is possible that, under the short-term Cd exposure, tolerant accessions activate this mechanism either early or faster than sensitive genotypes. In addition, positive transgenerational effects on seed germination and vigor of the tolerant genotype were triggered by the plant-mother cultivation in Cd-containing media, despite of the increased chromosomal abnormality. This work reported new insights about the effects of Cd exposure on tomato development, tolerance mechanisms, fruit quality and yield of tomato, as well as Cd distribution in the plants.O consumo de tomate (Solanum lycopersicum L.) tem aumentado a cada ano devido a atratividade dos frutos, suas diversas utilizações e efeitos benéficos para a saúde humana. No entanto, os frutos de tomate podem acumular uma concentração de cádmio (Cd) que excede o limiar de segurança para o consumo humano, mesmo quando as plantas são cultivadas em solo com níveis aceitáveis de Cd. Cádmio e um elemento não-essencial, extremamente perigoso para os sistemas biológicos, desencadeando varias doenças em seres humanos. Nas plantas, o Cd perturba a maquinaria antioxidante, altera o estado nutricional e prejudica a produção e /ou o particionamento de fotoassimilados, frequentemente reduzindo a produtividade e qualidade de frutos. No entanto, diferentes acessos de tomateiros podem apresentar contrastantes graus de tolerância a toxicidade gerada pela exposição ao Cd, como detectado em estudos anteriores de nosso grupo. O uso desses acessos e uma abordagem poderosa para identificar as estratégias empregadas pelas plantas para lidar com os desafios induzidos pelo Cd; e o conhecimento de tais estratégias pode ser potencialmente utilizado em programas biotecnológicos e de melhoramento genético. Deste modo, o conjunto de estudos que compõem a presente tese objetivou (i) identificar os principais mecanismos que suportam o grau de tolerância contrastante a toxicidade induzida por Cd em acessos de tomate após exposição a curto e longo prazos a este metal pesado; (ii) avaliar a relação entre o grau de tolerância e os atributos físico-químico de frutos oriundos de tomateiros cultivados em solo contendo Cd, e (iii) determinar os efeitos transgeracionais do estresse induzido por Cd. No primeiro experimento, nove acessos de tomateiro com graus variados de tolerância a exposição ao Cd, baseado na acumulação de biomassa, foram cultivados em solução hidropônica contendo 35 μM de CdCl2 durante 6 dias. O impedimento de elevada concentração de magnésio (Mg) em raízes foi identificado como possível estratégia da planta para mitigar a toxicidade de Cd, por meio da evitação da formação de pelos radiculares. Em relação ao modo de ação da toxicidade induzida por Cd, o excesso de Mn, em adição a elevada concentração de Cd, parece estar acoplado aos danos foliares que são acentuados ainda mais pelas altas concentrações de zinco (Zn) e boro (B) nos tecidos fotossintéticos de plantas sob exposição ao Cd. No segundo experimento, os genótipos tolerantes (Yoshimatsu) e sensíveis (Tropic Two Orders) foram cultivados em solo contendo Cd, a fim de avaliar os parâmetros de produção. O genótipo tolerante apresentou frutos com maior diâmetro, altura e peso após o cultivo em solo contendo Cd, quando comparado as plantas controle. Em ambas as cultivares, a concentração de Cd variou de acordo com a seguinte ordem descendente: raízes = folíolos> (receptáculo floral, pedúnculo e sépalas) > caule = casca de fruta = polpa de fruta. Alem disso, dados sugerem que o receptáculo floral e suas estruturas atuaram como uma barreira ao transporte de Cd para os frutos, entretanto, ela não foi suficiente para evitar que o Cd atingisse os frutos. Em adição, a exposição ao Cd provocou notáveis reduções na concentração de Mg nas raízes de genótipos sensíveis e tolerantes, revelando que a aclimatação das plantas depende do baixo status de Mg em tecidos radiculares. Desde que ambas as cultivares são capazes de empregar este mecanismo, os dados sugerem que, durante a exposição a curto prazo ao Cd, acessos tolerantes são capazes de ativa-lo ou mais cedo ou mais rápido do que acessos sensíveis. Ademais, efeitos transgeracionais positivos na germinação e vigor das sementes do genótipo tolerante foram desencadeados pelo cultivo planta-mãe em solo com Cd, apesar do aumento de anormalidades cromossômicas. Este trabalho reportou novos conhecimentos sobre os efeitos da exposição ao Cd sobre o desenvolvimento do tomateiro, mecanismos de tolerância, qualidade e rendimento de frutos, bem como a distribuição de Cd dentro da planta.