Academic literature on the topic 'Oxidatie'
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Journal articles on the topic "Oxidatie"
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Sun, Qi-An, Nageswara Madamanchi, and Marschall Runge. "Oxidative stress, NADPH oxidases, and arteries." Hämostaseologie 36, no. 02 (2016): 77–88. http://dx.doi.org/10.5482/hamo-14-11-0076.
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ZusammenfassungDie Atherosklerose und ihre wichtigsten Komplikationen – Myokardinfarkt und Schlaganfall – sind die Hauptursachen für Tod und Behinderung in den USA und weltweit. Eine dramatische Zunahme bei Adipositas und Diabetes mellitus wird wahrscheinlich auch in Zukunft zu einer hohen Prävalenz kardiovaskulärer Erkrankungen (CVD) und deren Auswirkungen auf das Gesundheitswesen führen. Große Fortschritte gibt es bei der Entwicklung neuer Therapien zur Senkung der Inzidenz von Atherosklerose und CVD, besonders bei der Behandlung der Hypercholesterinämie und Hypertonie. Der gemeinsame mechanistische Nenner bei vielen Risikofaktoren für CVD ist oxidativer Stress. Erst seit kurzem verfügen wir über Methoden, um die Schnittstelle zwischen oxidativem Stress und CVD im Tiermodell zu untersuchen. Die wichtigste Quelle für reaktive Sauerstoffspezies (und damit für oxidativen Stress) in vaskulären Zellen sind die Formen der Nicotin - amidadenindinukleotidphosphat-Oxidase (NADPH-Oxidase). Die jüngsten Studien belegen eindeutig, dass 1. NADPH-Oxidasen im Tiermodell von grundlegender Bedeutung für Atherosklerose und Hypertonie sind und 2. der vaskuläre oxidative Stress, angesichts der gewebespezifischen Expression wichtiger Bestandteile der NADPH-Oxidase, ein Ziel bei der Prävention der CVD sein könnte.
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Turchetto, Edoardo, Giovanni Lercker, and Renzo Bortolomeazzi. "Oxisterol Determination in Selected Coffees." Toxicology and Industrial Health 9, no. 3 (1993): 519–27. http://dx.doi.org/10.1177/074823379300900311.
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The main aim of green-coffee processing techniques, such as decqffeination and roasting, is always to maintain a very high level of quality in taste and flavor, the beverage's most important cliaracteristics to consumers. Oxidative alterations of coffee lipids, which can occur in roasting, exert a very marked influence on these quality traits. Determining the extent of oxidation thus can provide an indication of the product's potential shelf-life and reveal traces of any newly-formed oxidative products that might prove nutritionally unsafe. Yet, while much attention has recently been focused on certain by-products induced by cholesterol oxidation and their proven toxicity as risk factors in atherosclerosis and cancer, oxidated phytosterols have largely gone unnoticed, being considered along with β-sitosterol as not very dangerous in that neither is absorbed by the intestinal tract. The present study investigates the substances derived from phytosterol oxidation (oxisterols) in samples of regular and decaffeinated commercial coffees. The findings show that oxisterols were absent in some samples and that the traces of oxidate phytosterols detected in others were well below the threshold considered as toxicologically active.
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Lesnefsky, Edward J., Qun Chen, Thomas J. Slabe, et al. "Ischemia, rather than reperfusion, inhibits respiration through cytochrome oxidase in the isolated, perfused rabbit heart: role of cardiolipin." American Journal of Physiology-Heart and Circulatory Physiology 287, no. 1 (2004): H258—H267. http://dx.doi.org/10.1152/ajpheart.00348.2003.
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Ischemia and reperfusion result in mitochondrial dysfunction, with decreases in oxidative capacity, loss of cytochrome c, and generation of reactive oxygen species. During ischemia of the isolated perfused rabbit heart, subsarcolemmal mitochondria, located beneath the plasma membrane, sustain a loss of the phospholipid cardiolipin, with decreases in oxidative metabolism through cytochrome oxidase and the loss of cytochrome c. We asked whether additional injury to the distal electron chain involving cardiolipin with loss of cytochrome c and cytochrome oxidase occurs during reperfusion. Reperfusion did not lead to additional damage in the distal electron transport chain. Oxidation through cytochrome oxidase and the content of cytochrome c did not further decrease during reperfusion. Thus injury to cardiolipin, cytochrome c, and cytochrome oxidase occurs during ischemia rather than during reperfusion. The ischemic injury leads to persistent defects in oxidative function during the early reperfusion period. The decrease in cardiolipin content accompanied by persistent decrements in the content of cytochrome c and oxidation through cytochrome oxidase is a potential mechanism of additional myocyte injury during reperfusion.
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Judge, A. R., and S. L. Dodd. "Xanthine oxidase and activated neutrophils cause oxidative damage to skeletal muscle after contractile claudication." American Journal of Physiology-Heart and Circulatory Physiology 286, no. 1 (2004): H252—H256. http://dx.doi.org/10.1152/ajpheart.00684.2003.
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We previously showed oxidative damage and edema within skeletal muscle after contractile claudication. To investigate the sources of this oxidative damage in the gastrocnemius muscle, we administered allopurinol (Allo, to inhibit xanthine oxidase) and cyclophosphamide (Cyclo, to deplete neutrophils) before inducing contractile claudication in male Sprague Dawley rats. Contractile claudication (ligated stimulated, LS) caused a significant increase in xanthine oxidase activity [sham ligated stimulated (SS) = 2.57 ± 0.07; LS = 3.22 ± 0.07] and neutrophil infiltration (SS = 0.47 ± 0.03; LS = 0.91 ± 0.10) compared with controls (SS), and this was associated with increased lipid peroxidation, protein oxidation, muscle damage, and edema. Pretreatment with Allo attenuated the increase in xanthine oxidase activity and attenuated lipid hydroperoxides (control LS = 12.85 ± 0.50; Allo LS = 9.96 ± 0.71), muscle damage, and neutrophil infiltration (control LS = 0.91 ± 0.10; Allo LS = 0.61 ± 0.07). This latter finding suggests that xanthine oxidase-derived oxidants are chemotactic to neutrophils. Pretreatment with Cyclo reduced neutrophil infiltration (control LS = 0.91 ± 0.10; Cyclo LS = 0.55 ± 0.02) and attenuated lipid peroxidation (control LS = 12.85 ± 0.50; Cyclo LS = 6.462 ± 0.62), protein oxidation (control LS = 2.59 ± 0.47; Cyclo LS = 1.77 ± 0.60), muscle damage, and edema. Together, these data indicate that contractile claudication causes an increase in xanthine oxidase activity and neutrophils in muscle and that inhibition of these oxidant sources protects against oxidative stress, muscle damage, and edema.
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Tonda, Rachel, Arlene Lamptey, and Brenda Reid. "PSV-15 Variability in the Oxidative Status of Fats and Oils Used in Livestock Diets in North America." Journal of Animal Science 99, Supplement_1 (2021): 197–98. http://dx.doi.org/10.1093/jas/skab054.322.
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Abstract Lipids are essential energy sources in nearly every animal’s diet. However, lipids used in feed formulations today are highly variable in both composition and susceptibility to oxidation – a major source of decreased lipid quality. Feeding oxidized lipids negatively influences animal health and performance, yet data on the oxidative status of commercially used lipids is limited. Herein, the oxidative stability results of lipid samples submitted to Kemin Customer Laboratory Services (CLS) for analysis since 2018 is summarized. Of the 392 samples evaluated, corn oil (n=122), choice white grease (CWG; n=101) and soybean oil (n=66) were the most common. Current oxidation status was assessed by measuring active oxidation markers, including peroxide values (PV; target < 5 meq/kg) and secondary oxidative molecules (hexanal and 2,4-decadienal; target < 50 ppm total). Resistance to future oxidation was evaluated by Oxidative Stability Index (OSI) at 100° C. Lipid PVs ranged from 0 meq/kg to 47.8 meq/kg, with an average PV of 3.4 meq/kg. Total secondary oxidatives averaged 28 ppm, ranging from below the limit of quantitation (5 ppm) to 313 ppm. Based on current oxidative markers, 39% of samples showed no signs of oxidation, 40% had early signs of oxidation, 16% were undergoing active oxidation and 5% were severely oxidized. Lipid OSI times ranged from 0.2 to 144 hours, averaging 17.4 hours. Fifty percent of samples had OSI times of < 10 hours. Further, 46% of animal fats had an OSI < 5 hours, indicating enhanced susceptibility of these fats to future oxidation. In conclusion, >60% of samples showed signs of oxidation, and significant variability in the oxidative status of commercial lipids was observed. To optimize nutritional efficiency and minimize adverse effects of oxidation on overall health of livestock, managing lipid quality – including understanding oxidation risks – should be a major consideration for producers.
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Lesnefsky, Edward J., Thomas J. Slabe, Maria S. K. Stoll, Paul E. Minkler, and Charles L. Hoppel. "Myocardial ischemia selectively depletes cardiolipin in rabbit heart subsarcolemmal mitochondria." American Journal of Physiology-Heart and Circulatory Physiology 280, no. 6 (2001): H2770—H2778. http://dx.doi.org/10.1152/ajpheart.2001.280.6.h2770.
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Mitochondria contribute to myocyte injury during ischemia. After 30 and 45 min of ischemia in the isolated perfused rabbit heart, subsarcolemmal mitochondria (SSM), located beneath the plasma membrane, sustain a decrease in oxidative phosphorylation through cytochrome oxidase. In contrast, oxidation through cytochrome oxidase in interfibrillar mitochondria (IFM), located between the myofibrils, remains unaffected. Cytochrome oxidase activity in the intact membrane requires an inner mitochondrial membrane lipid environment enriched in cardiolipin. During ischemia, the content of cardiolipin decreased only in SSM, whereas the content of other phospholipids was preserved. Ischemia did not alter the composition of the cardiolipin that remained in SSM. Cardiolipin content was preserved in IFM during ischemia. Thus cardiolipin is a relatively early target of ischemic mitochondrial damage, leading to loss of oxidative phosphorylation through cytochrome oxidase in SSM.
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LaManna, J. C., T. J. Sick, S. M. Pikarsky, and M. Rosenthal. "Detection of an oxidizable fraction of cytochrome oxidase in intact rat brain." American Journal of Physiology-Cell Physiology 253, no. 3 (1987): C477—C483. http://dx.doi.org/10.1152/ajpcell.1987.253.3.c477.
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Rapid-scanning reflectance spectrophotometry was used to evaluate the reduction-oxidation state of cytochrome oxidase in normoxic rat brain. Reflectance spectra were recorded from intact blood-perfused cerebral cortices after increased oxidative metabolic activity induced by direct cortical stimulation. Reflectance spectra taken from blood-free rat brain and from the rat ear vascular bed were used to identify cytochrome and hemoglobin components of spectra taken from intact brain. Cortical stimulation provoked shifts toward increased oxidation of cytochrome oxidase that were detectable in reflectance spectra. Observations of an oxidizable fraction of cytochrome oxidase demonstrate that a fraction of the cytochrome oxidase pool exists in a reduced state in normoxic brain. The presence of reduced cytochrome oxidase suggests that oxygen delivery to the brain is restricted by microvascular control mechanisms either as a function of brain metabolic physiology or as protection against oxygen toxicity.
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Moyes, C. D., T. W. Moon, and J. S. Ballantyne. "Osmotic effects on amino acid oxidation in skate liver mitochondria." Journal of Experimental Biology 125, no. 1 (1986): 181–95. http://dx.doi.org/10.1242/jeb.125.1.181.
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The mechanism responsible for the osmotic sensitivity of sarcosine oxidation by liver mitochondria from the little skate, Raja erinacea Mitchill, is examined. Assay medium tonicity, rather than a solute effect (urea or trimethylamine oxide), is probably responsible for the inverse relationship between osmolarity and the rate of oxidation of sarcosine by these mitochondria. Sarcosine oxidation proceeds through the flavin-linked sarcosine oxidase with the resultant glycine catabolized in the NAD-linked glycine cleavage system. The tonicity-sensitive component of the sarcosine oxidative pathway is not the glycine cleavage system. Sarcosine oxidation in the presence of rotenone is sensitive to medium tonicity. Oxidation of serine, which is also catabolized through the glycine cleavage system, is not as sensitive to tonicity as is sarcosine oxidation. Mitochondrial volume changes also appear to affect the transport of glycine. Although sarcosine does not appear to share the glycine transporter, it is possible that sarcosine transport is similarly sensitive to medium tonicity. The effects of osmolarity on the oxidation of dimethylglycine appear to support this hypothesis. Tonicity effects on sarcosine oxidase cannot yet be eliminated.
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Zhou, Li, Ping Chen, Yating Peng, and Ruoyun Ouyang. "Role of Oxidative Stress in the Neurocognitive Dysfunction of Obstructive Sleep Apnea Syndrome." Oxidative Medicine and Cellular Longevity 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/9626831.
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Obstructive sleep apnea syndrome (OSAS) is characterized by chronic nocturnal intermittent hypoxia and sleep fragmentations. Neurocognitive dysfunction, a significant and extraordinary complication of OSAS, influences patients’ career, family, and social life and reduces quality of life to some extent. Previous researches revealed that repetitive hypoxia and reoxygenation caused mitochondria and endoplasmic reticulum dysfunction, overactivated NADPH oxidase, xanthine oxidase, and uncoupling nitric oxide synthase, induced an imbalance between prooxidants and antioxidants, and then got rise to a series of oxidative stress (OS) responses, such as protein oxidation, lipid peroxidation, and DNA oxidation along with inflammatory reaction. OS in brain could trigger neuron injury especially in the hippocampus and cerebral cortex regions. Those two regions are fairly susceptible to hypoxia and oxidative stress production which could consequently result in cognitive dysfunction. Apart from continuous positive airway pressure (CPAP), antioxidant may be a promising therapeutic method to improve partially reversible neurocognitive function. Understanding the role that OS played in the cognitive deficits is crucial for future research and therapeutic strategy development. In this paper, recent important literature concerning the relationship between oxidative stress and cognitive impairment in OSAS will be summarized and the results can provide a rewarding overview for future breakthrough in this field.
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Rutkevich, Lori A., and David B. Williams. "Vitamin K epoxide reductase contributes to protein disulfide formation and redox homeostasis within the endoplasmic reticulum." Molecular Biology of the Cell 23, no. 11 (2012): 2017–27. http://dx.doi.org/10.1091/mbc.e12-02-0102.
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The transfer of oxidizing equivalents from the endoplasmic reticulum (ER) oxidoreductin (Ero1) oxidase to protein disulfide isomerase is an important pathway leading to disulfide formation in nascent proteins within the ER. However, Ero1-deficient mouse cells still support oxidative protein folding, which led to the discovery that peroxiredoxin IV (PRDX4) catalyzes a parallel oxidation pathway. To identify additional pathways, we used RNA interference in human hepatoma cells and evaluated the relative contributions to oxidative protein folding and ER redox homeostasis of Ero1, PRDX4, and the candidate oxidants quiescin-sulfhydryl oxidase 1 (QSOX1) and vitamin K epoxide reductase (VKOR). We show that Ero1 is primarily responsible for maintaining cell growth, protein secretion, and recovery from a reductive challenge. We further show by combined depletion with Ero1 that PRDX4 and, for the first time, VKOR contribute to ER oxidation and that depletion of all three activities results in cell death. Of importance, Ero1, PRDX4, or VKOR was individually capable of supporting cell viability, secretion, and recovery after reductive challenge in the near absence of the other two activities. In contrast, no involvement of QSOX1 in ER oxidative processes could be detected. These findings establish VKOR as a significant contributor to disulfide bond formation within the ER.
Dissertations / Theses on the topic "Oxidatie"
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Grunsven, Elisabeth Gerarda van. "Functions and dysfunctions of peroxisomal fatty acid [beta]-oxidation in man." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/82102.
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Ferdinandusse, Sacha. "New insights in peroxisomal [beta]-oxidation." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/64403.
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Rispens, Minze Theunis. "Enantioselective oxidation using transition metal catalysts." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1996. http://irs.ub.rug.nl/ppn/291237975.
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Beilen, Jan Berthold van. "Alkane oxidation by Pseudomonas oleovorans: genes and proteins." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1994. http://irs.ub.rug.nl/ppn/292892500.
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Wubbolts, Marcel Gerhardus. "Xylene and alkane mono-oxygenases from Pseudomonas putida genetics, regulated expression and utilization in the synthesis of optically active synthons /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1994. http://irs.ub.rug.nl/ppn/29797291X.
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Zondervan, Charon. "Homogeneous catalytic oxidation a ligand approach /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1997. http://irs.ub.rug.nl/ppn/298195445.
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Boer, Johannes Wietse de. "cis-Dihydroxylation and epoxidation of alkenes by manganese catalysts selectivity, reactivity and mechanism /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2008. http://irs.ub.rug.nl/ppn/.
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Dinamarco, Taísa Magnani. "Clonagem, expressão e caracterização do gene da oxidase alternativa mitocrondial de Aspergilus fumigatus." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/60/60135/tde-21102008-102221/.
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O Aspergillus fumigatus é um fungo filamentoso e saprofítico, encontrado em todas as regiões do mundo, desempenhando um importante papel na reciclagem de carbono e nitrogênio do solo. A principal forma de infecção ocorre através da inalação dos conídios com predominância de infecções no trato respiratório, principalmente em pacientes imunocomprometidos. A mitocôndria de A. fumigatus foi caracterizada em nosso laboratório, que revelou a presença de uma respiração resistente a cianeto mediada pela oxidase alternativa. A clonagem e sequenciamento deste gene foram realizadas através de screening de uma biblioteca de DNA genômico. O alinhamento das sequências genômica e de cDNA mostrou a presença de dois introns, que após splicing codifica uma proteína contendo 352 aminoácidos, possuindo uma massa molecular estimada de 40,84 kDa e um pI teórico de 9,51. Além disso, foram identificados domínios altamente conservados (LET, NERMHL, LEEA e RADEH) que interagem com átomos de ferro e estão contidos em -hélices propostas como responsáveis pela organização estrutural da enzima. A fim de caracterizar bioquimicamente esta proteína, a sequência de cDNA do gene foi clonada em plasmídeo pYES2 e expressa em S. cerevisiae INVSc1 como um modelo eucarioto. Após expressão, a proteína encontrou-se de forma ativa, conferindo à levedura uma respiração resistente a cianeto. Esta característica herdada provocou uma discreta diminuição na taxa de crescimento em meio não-fermentativo e uma capacidade de sobrevivência na presença de KCN. Acredita-se que a atividade das AOXs esteja diretamente relacionada com a presença de diferentes espécies reativas de oxigênio (ERO). Neste contexto, a avaliação do efeito de diferentes agentes pró-oxidantes provocou um aumento na atividade e na expressão da enzima. Paralelamente, a caracterização funcional do gene foi realizada através da técnica de interferência por RNA, utilizando o vetor de expressão pALB1. Em meio contendo maltose, as cepas pALB1/aoxAf apresentaram coloração branca devido ao silenciamento do gene alb1. Os níveis de mRNA do gene aoxAf foram determinados por Real time RT-PCR, mostrando o eficiente silenciamento do gene alvo com a construção utilizada. Devido à relação já descrita entre ERO e a atividade das AOXs, avaliou-se a produção de espécies reativas de oxigênio nas cepas silenciadas utilizando-se a sonda CM-H2DCFDA, observando maior produção na cepa pALB1/aoxAf. Além disso, a viabilidade destas cepas foi determinada por citometria de fluxo após a exposição com agentes pró-oxidantes, a qual indicou maior letalidade na cepa pALB1/aoxAf, quando comparada com CEA e pALB1. Da mesma forma, após a incubação dos conídios das cepas silenciadas com macrófagos de camundongos foi verificada uma maior atividade microbicida dos macrófagos na cepa duplamente silenciada pALB1/aoxAf, quando comparada com as outras cepas. Com estes resultados podemos concluir que a oxidase alternativa apresenta uma importante atividade antioxidante, além de contribuir nos mecanismos de defesa durante o processo de infecção de A. fumigatus.The saprophytic species Aspergillus fumigatus is a deuteromycete fungus found worldwide, which has an essential role in recycling carbon and nitrogen. Following inhalation of conidia by the immunocompetent host, the innate cellular immune system is responsible for killing the conidia, exposing them to reactive oxygen. However, A. fumigatus is capable of surviving and replicating within the phagolysosomal compartment of immunocompromised macrophages. It was previously demonstrated that A. fumigatus mitochondria possess an alternative oxidase (aoxAf) wich is a cyanide-resistant protein. A partial genomic DNA library was screened to cloning an aoxAf gene. The alignment between the cDNA and genomic DNA sequences revealed the existence of two introns which after splicing encodes a 352 amino acid sequence with a calculated molecular mass of 40 kDa and a theoretical pI of 9.51. The deduced amino acid sequence revealed four regions completely conserved among the AOXs sequences (LET, NERMHL, LEEA and RADE-H), where six conserved amino acids residues are proposed to be a metal ligand site. To characterize the AOX protein, a cDNA of aoxAf gene was cloned into pYES2 plasmid and transformed in S. cerevisiae INVSc1. After the incubation of the cells in a nonfermentable medium in the presence of KCN, S. cerevisiae expressing AOX was able to grow, while it was lethal for the control yeast. These results suggest that the recombinant AOXAf is properly targeted to the S. cerevisiae mitochondria where it has functional activity. Studies with different species demonstrated that AOX is induced by a variety of treatments usually labeled as stresses. To verify the function of AOX in A. fumigatus under oxidative stress conditions, conidia were treated with different donors of ROS. These treatments caused an increase in aoxAf activity and transcription levels. To identify genetically attributes of virulence and oxidative defense in A. fumigatus, we construct a RNA interference plasmid. Two inverted repeated sequences of conserved region of an interest gene were amplified and cloned in pALB1 plasmid. In maltose medium pALB1 and pALB1/aoxAf transformants demonstrated white colonies, attributable to the reduction of alb1 gene expression. The aoxAf mRNA levels were analyzed by Real time RT-PCR, showing an efficient alternative oxidase gene silencing in pALB1 plasmid construction. It was previously demonstrated that ROS can stimulate the AOXs activity, so, we used the dye CM-H2DCFDA to measure ROS production in RNAi transformants, showing that the decrease in aoxAf gene expression caused an increase in ROS production. After incubation with ROS donors the viability of these strains was determined by flow cytometry analysis. The pALB1/aoxAf strain showed higher lethality, when compared with CEA and pALB1, suggesting the involvement of AOX in antioxidant defense in A. fumigatus. Besides, ROS produced by alveolar macrophages play an essential role in the killing of A. fumigatus conidia. In the same way, phagocytosis assay revealed that pALB1/aoxAf strain was more lethal than CEA and pALB1. With these results, we concluded that alternative oxidase is an efficient antioxidant system and might contribute with defense mechanism of A. fumigatus.
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Pérez, Sampietro María. "Mecanismes implicats en la senyalització i la defensa front l'estrès per selenit en Saccharomyces cerevisiae." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/129646.
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El seleni és un element essencial en la dieta humana present en selenoproteïnes, que té propietats
anticancerígenes a concentracions baixes tot i que és tòxic a dosis elevades. Contràriament als
microorganismes multicel•lulars, el Se no és essencial pel creixement de Saccharomyces
cerevisiae, ja que manca de selenoproteïnes. La proteïna quinasa Snf1/AMPK juga un paper
central en la regulació de l’homeòstasi del metabolisme del carboni en S. cerevisiae. En aquest
treball s’ha demostrat que l’activitat d’aquesta quinasa és necessària per protegir les cèl•lules
front la toxicitat per selenit. A més, Snf1 juga un paper protector quan l’homeòstasi redox del
metabolisme del glutatió es troba alterada cap a un ambient intracel•lular més oxidant. D’altra
banda, aquest treball demostra que el selenit provoca la inducció del reguló Aft1 de forma
específica i diferent del que s’observa en condicions de dèficit de ferro. Mentre que Aft1
protegeix les cèl•lules front la toxicitat per selenit depenent dels nivells de ferro intracel•lulars,
Aft2, factor transcripcional paràleg d’Aft1, juga una funció independent front aquesta protecció.
A més, Rim101 (qui regula la via de resposta a pH alcalí) també protegeix front al selenit, tot i
que el seu rol protector no està relacionat ni amb Aft1 ni amb Aft2. Addicionalment, Rim101
regula l’expressió de gens d’algunes subunitats de l’ATPasa V-H+ al llarg d’un tractament amb
selenit.El selenio es un elemento esencial en la dieta humana presente en forma en selenoproteínas, que tiene propiedades anticancerígenas a concentraciones bajas aunque es tóxico a dosis elevadas. Contrariamente a los microorganismos multicelulares, el Se no es esencial para el crecimiento de Saccharomyces cerevisiae, ya que carece de selenoproteínas. La proteína quinasa Snf1/AMPK juega un papel central en la regulación de la homeostasis del metabolismo del carbono en S. cerevisiae. En este trabajo se ha demostrado que la actividad de esta quinasa es necesaria para proteger las células frente a la toxicidad por selenito. Además, Snf1 juega un papel protector cuando la homeostasis redox del metabolismo del glutatión se encuentra alterada hacia un ambiente intracelular más oxidante.Por otra parte, este trabajo demuestra que el selenito provoca la inducción del regulón Aft1 de forma específica y diferente de lo que se observa en condiciones de déficit de hierro. Mientras que Aft1 protege las células frente a la toxicidad por selenito dependiendo de los niveles de hierro intracelulares, Aft2, factor transcripcional parálogo de Aft1, juega una función independiente frente a esta protección. Además, Rim101 (quien regula la vía de respuesta a pH alcalino) también protege frente al selenito, aunque su rol protector no está relacionado ni con Aft1 ni con Aft2. Adicionalmente, Rim101 regula la expresión de genes de algunas subunidades de la ATPasa V-H+ a lo largo de un tratamiento con selenito.
Selenium is an essential element in human diet present in a number of selenoproteins, which has anticarcinogenic properties at low concentrations although it is toxic at high dosis. In contrast to multicellular organisms, Se is not essential for growth of Saccharomyces cerevisiae, which lacks selenoproteins. The AMPK/Snf1 protein kinase has a central role in carbon metabolism in S. cerevisiae. In this study it has been demonstrated that Snf1 activity is needed for protection against selenite toxicity. Moreover, Snf1 plays a role in protecting yeast cells when glutathionedependent redox homeostasis is altered to a more oxidant intracellular environment.On the other hand, this study demonstrates that selenite provokes the induction of the Aft1 regulon in a specific manner, and different from that observed in iron limitation conditions. While Aft1 protects cells against selenite in an iron-dependent manner, Aft2, Aft1 paralog transcription factor, has independent roles in such protection. Moreover, Rim101 (which mediates the alkaline pH response pathway) also protects against selenite, although its role is not related neither to Aft1 nor to Aft2. Additionally, Rim101 regulates the expression of some genes encoding ATPase VH+ vacuolar subunits during selenite treatment.
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Thiesen, Kenya. "Mecanismos fisiopatológicos do desequilíbrio redox em células neointimais vasculares." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-27042010-113336/.
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O crescimento de uma camada neoíntima é o marcador central do processo aterosclerótico, bem como do remodelamento vascular associado à reestenose após intervenções vasculares terapêuticas, tais como angioplastia ou colocação de stents. A célula neointimal é essencialmente uma célula com fenótipo muscular liso indiferenciado, cuja origem pode ser múltipla e com característica ação secretora de matriz extracelular. Dentre os fatores que coordenam a (des)diferenciação, proliferação e migração destas células, há evidências de que processos redox tenham papel preponderante, porém os mecanismos de tais processos não estão claros. A compreensão mais profunda de tais mecanismos redox tem sido dificultada pela falta de modelos de células neointimais cultivadas. Os objetivos específicos deste trabalho são: 1) Desenvolver um modelo de cultura de células neointimais de artéria ilíaca de coelho obtidas após lesão por catéter-balão. 2) Avaliar em tais células índices do estado redox e potenciais fontes enzimáticas de ERO, com ênfase no complexo NAD(P)H oxidase. 3)Avaliar marcadores de estresse do retículo endoplasmático e sua correlação com os índices do estado redox. 4) Estudar o efeito de estímulos proapoptóticos como deprivação de soro, estressores do RE e particularmente administração exógena de NO na viabilidade e estado redox de células neointimais. Os resultados obtidos demonstram que: é possível obter células neointimais em cultura de modo reproduzível e estável. Células provenientes da artéria lesada mantém um estado persistente de aumento do estresse oxidativo. O estresse oxidativo nessas células decorre de produção aumentada de radical superóxido e ativação do complexo da NADPH oxidase vascular. Diferentemente do observado em vasos lesados, os marcadores do estresse do reticulo endoplasmático não se apresentam alterados se comparados a células musculares lisas normais. Células neointimais têm resposta aumentada a agonistas da NADPH oxidase e estressores celulares. A exposição a óxido nitrico promove aumento da produção de superóxido, particularmente acentuado em células neointimais. As curvas de viabilidade celular indicam uma sensibilidade aumentada a estressores do RE, doadores de NO e particularmente a oxidantes exógenos. Em conjunto, estes resultados permitem concluir que o fenótipo neointimal é um fenótipo de estresse oxidativo acentuado e persistente, mesmo em condições de cultura celular, e que este estresse oxidativo decorre pelo menos em parte da ativação do complexo NADPH oxidase no contexto de uma adaptação à resposta celular integrada ao estresse. Estes dados indicam novas perspectivas no entendimento dos mecanismos envolvidos na fisiopatologia redox da neoíntima, podendo suscitar o desenho de intervenções terapêuticas racionais.Formation of a neointimal layer is the hallmark of most vascular diseases, such as atherosclerosis and restenosis after angioplasty. Neointimal cells display an undifferentiated noncontractile smooth muscle phenotype with marked extracellular matrix secretion. Their origin can be multiple. Among factors that govern the (de)differentiation, proliferation and migration of neointimal cells, there is evidence for a key role of redox processes, but the underlying mechanisms are unclear. Advancing the knowledge about such redox mechanisms has been difficulted by the absence of a reproducible method of neointimal cell culture. The objectives of this work are: 1) To develop a model of neointimal cell culture, in which cells are harvested from rabbit iliac arteries 14 days after overdistention balloon injury. 2) To assess the redox status in such neointimal cells and the possible enzymatic source of reactive oxygen, with emphasis in the NAD(P)H oxidase complex. 3) To investigate the expression of endoplasmic reticulum stress markers and their corralation with redox status. 4) To investigate the effects of proapoptotic stimuli such as serum deprivation, endoplasmic reticulum stressors and particularly the exogenous administration of nitric oxide in viability and redox status of neointimal cells. Our results show that it is possible to harvest and cultivate neointimal cells after balloon injury. The neointimal cells in culture, even after several passages, exhibit increased indexes of oxidative stress. Oxidative stress in such cells is associated with increased activation of the vascular NAD(P)H oxidase complex. Contrarily to what was observed in healing arteries harvested from in vivo rabbits, markers of ER stress did not show any change when compared with primary smooth muscle cells kept in similar conditions. Oxidative stress response was increased after NADPH oxidase agonists; in particular, exposure to exogenous nitric oxide markedly increased superoxide radical production in neointimal cells. Cell viability curves showed increased sensitivity to ER stressors, NO donors and, particularly, exogenous oxidants. Therefore, the neointimal phenotype is a phenotype of intrinsic sustained oxidative stress even after several passages in culture. Such oxidative stress is due at least in part to activation of the NAD(P)H oxidase complex in the context of adaptation to an integrated stress response. This data provide new perspectives to understand redox mechanisms associated with neointimal pathophysiology and can lead to development of rational therapeutic interventions.
Books on the topic "Oxidatie"
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Ramakrishnan, Venugopal. Oxidative inactivation of glucose oxidase. National Library of Canada = Bibliothèque nationale du Canada, 1993.
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Modern carbohydrate chemistry. M. Dekker, 1988.
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1934-, Hlavica P., and Damani L. A. 1949-, eds. N-oxidation of drugs: Biochemistry, pharmacology, toxicology. Chapman & Hall, 1991.
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Molecular basis of oxidative stress: Chemistry, mechanisms, and disease pathogenesis. Wiley, 2013.
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Bekturov, E. A. Catalysis by polymers. Wiley-VCH, 2002.
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(Firm), Knovel, ed. Applications of hydrogen peroxide and derivatives. Royal Society of Chemistry, 1999.
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Brett, Blackman, and Jo Hanjoong, eds. Hemodynamics and mechanobiology of endothelium. World Scientific, 2010.
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Reyes, Adolfo M. Handbook on oxidative stress: New research. Nova Science Publisher's, 2011.
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Vserossiĭskai︠a︡ konferent︠s︡ii︠a︡ molodykh uchenykh i shkola im. akademika N.M. Ėmanuėli︠a︡ (2008 Moscow, Russia). Okislenie, okislitelʹnyĭ stress, antioksidanty: Vserossiĭskai︠a︡ konferent︠s︡ii︠a︡ molodykh uchenykh i III shkola im. akademika N.M. Ėmanuėli︠a︡, 1-3 okti︠a︡bri︠a︡ 2008 g., Moskva : doklady i tezisy. Rossiĭskiĭ universitet druzhby narodov, 2008.
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Harald, Gröger, ed. Asymmetric organocatalysis: From biomimetic concepts to applications in asymmetric synthesis. Wiley-VCH, 2005.
Book chapters on the topic "Oxidatie"
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Pina, Cristina Della, Ermelinda Falletta, and Michele Rossi. "Oxidative Conversion of Renewable Feedstock: Carbohydrate Oxidation." In Liquid Phase Aerobic Oxidation Catalysis: Industrial Applications and Academic Perspectives. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527690121.ch21.
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Raijmakers, Maarten T. M., Wilbert H. M. Peters, Christianne J. de Groot, and Eric A. P. Steegers. "Oxidative Stress and Protein Oxidation in Pre-Eclampsia." In Redox Proteomics. John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471973122.ch25.
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Cohen, G. "Monoamine oxidase and oxidative stress at dopaminergic synapses." In Amine Oxidases and Their Impact on Neurobiology. Springer Vienna, 1990. http://dx.doi.org/10.1007/978-3-7091-9113-2_33.
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Cruel Sigüenza, Joseph, Carla Bernal Villavicencio, María Elizabeth Canchingre, Christie Durán García, and Juan E. Tacoronte. "Eco-Sustainable Catalytic System for Green Oxidation of Spirostanic Alcohols Using Hypervalent Iodine (III) Tempo-4-n-Acetoxyamine System." In Green Chemistry - New Perspectives. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103855.
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The oxidation of the 3β-hydroxy group in the steroidal substrates obtained from naturally occurring sources, i.e., solanaceae steroidal sapogenins, is an important process in the preparation of ecdysteroid analogs. The need for selective green oxidation methodologies for steroidal alcohols (spirostenols, diosgenine, and derivatives) avoid the use of toxic Cr (VI) derivatives, without the isomerization of the double bond at 5,6 position and also without the oxidative cleavage of the spirocetal moiety is of great methodological significance. Herein, we report the oxidation of spirostanic steroidal alcohols to their carbonyl analogs using hypervalent iodine (III)/TEMPO-4-N-acetoxyamine system. The present method is simple, eco-sustainable, efficient, and high-yielding process for the oxidative transformation of secondary steroidal alcohols without any over-oxidation, isomerization of the double bond, or oxidative cleavage of spirocetalic fragment in different substrates. Therefore, this method does not involve toxic heavy metals and is expected to have wide utility in the oxidation process of these compounds.
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Frey, Perry A., and Adrian D. Hegeman. "Oxidases and Oxygenases." In Enzymatic Reaction Mechanisms. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195122589.003.0021.
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An oxidase catalyzes the oxidation of a substrate by O2 without incorporating an oxygen atom into the product. A monooxygenase catalyzes oxidation by O2 with incorporation of one oxygen atom into the product, and oxidation by a dioxygenase proceeds with incorporation of both atoms of O2 into the product. These reactions generally require an organic or metallic coenzyme, with few exceptions, notably urate oxidase. Mechanisms of action of phenylalanine hydroxylase, galactose oxidase, and ascorbate oxidase are provided in chapter 4 in connection with the introduction of metallic coenzymes. In this chapter, we present cases of well-studied coenzyme and metal-dependent oxidases and oxygenases, and we consider one example of an oxidase that does not require a cofactor. Biochemical diversity may be a characteristic of oxidases, which include flavoproteins, heme proteins, copper proteins, and quinoproteins. The actions of copper and topaquinone-dependent amine oxidases are presented in chapter 3, and in chapter 4, two copper-dependent oxidases are discussed. In this chapter, we discuss flavin-dependent oxidases, a mononuclear iron oxidase, and a cofactor-independent oxidase. Flavin-dependent oxidases catalyze the reaction of O2 with an alcohol or amine to produce the corresponding carbonyl compound and H2O2. Examples include glucose oxidase, which produces gluconolactone and H2O2 from glucose and O2 according to. A D-Amino acid oxidase (EC 1.4.3.3) catalyzes a formally similar reaction to produce an α-keto acid from the corresponding α-D-amino acid. The oxidation of an amino acid by an oxidase produces ammonium ion in addition to hydrogen peroxide and the ketoacid, and so it is formally more complex. It proceeds in the three phases described in, the reduction of FAD to FADH2 by the amino acid, hydrolysis of the resultant α-iminoacid to the corresponding α-ketoacid and NH4, and oxidation of FADH2 by O2 to form H2O2. D-Amino acid oxidase is a thoroughly studied example of a flavoprotein oxidase. The enzyme is a 84-kDa homodimer containing one molecule of FAD per subunit. The mechanisms of the hydrolysis of imines and of the oxidation of dihydroflavins are discussed in chapters 1 and 3.
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Uyanik, Muhammet, and Kazuaki Ishihara. "Oxidation: Asymmetric Oxidative Dearomatization." In Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-32-390644-9.00028-7.
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Casano, G., and O. Ouari. "1.2.Nitroxides in Organic Synthesis." In Free Radicals: Fundamentals and Applications in Organic Synthesis 1. Georg Thieme Verlag KG, 2021. http://dx.doi.org/10.1055/sos-sd-234-00022.
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AbstractThis review describes selected methods using nitroxides such as TEMPO and AZADO for selective oxidative transformations including oxidation of alcohols and diols, N-alkylation of amines, C—H activation, C—C bond formation, and cross-coupling radical reactions.
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N. Onyango, Arnold. "Lipid Peroxidation as a Link Between Unhealthy Diets and the Metabolic Syndrome." In Lipid Peroxidation [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98183.
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Unhealthy diets, such as those high in saturated fat and sugar accelerate the development of non-communicable diseases. The metabolic syndrome is a conglomeration of disorders such as abdominal obesity, hypertension, impaired glucose regulation and dyslipidemia, which increases the risk for diabetes and cardiovascular disease. The prevalence of the metabolic syndrome is increasing globally, and dietary interventions may help to reverse this trend. A good understanding of its pathophysiological mechanisms is needed for the proper design of such interventions. This chapter discusses how lipid peroxidation is associated with the development of this syndrome, mainly through the formation of bioactive aldehydes, such as 4-hydroxy-2-nonenal, malondialdehyde, acrolein and glyoxal, which modify biomolecules to induce cellular dysfunction, including the enhancement of oxidative stress and inflammatory signaling. It gives a current understanding of the mechanisms of formation of these aldehydes and how dietary components such as saturated fatty acids promote oxidative stress, leading to lipid oxidation. It also outlines mechanisms, apart from free radical scavenging and singlet oxygen quenching, by which various dietary constituents prevent oxidative stress and lipid oxidation in vivo.
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María Descalzo, Adriana, Sergio Aníbal Rizzo, Carolina Daiana Pérez, et al. "Oxidative Stability and Sensory Properties of Pecan Nuts." In Nut Crops - New Insights [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106175.
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Pecans are the nut with the higher oil content. In addition, they present a large number of polyunsaturated fatty acids, which are susceptible to oxidation. Oxidative damage in pecans is traduced in lower quality aspects, appearance of rancidity and acidity, loss of sweetness and firmness, darker kernels, and darker shells. The use of different strategies for the conservation of entire and shelled nuts is discussed in terms of oxidation and the consequences on nuts quality.
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Pophaly, Sarang Dilip, Manorama Chauhan, Jitesh Tarak, Shekhar Banala Bashetty, Tejinder Pal Singh, and Sudhir Kumar Tomar. "Aerobic Respiration in Lactic Acid Bacteria." In Microbial Cultures and Enzymes in Dairy Technology. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5363-2.ch005.
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Lactic acid bacteria (LAB) are used as food-grade microorganisms for production of a variety of fermented milk products. They are also the most common probiotic organisms used for making functional foods. Lactic acid bacteria are well known for their fermentative metabolism wherein they convert simple carbohydrates to organic acids and other end products. Fermentation helps the bacteria to generate ATP required for various cellular activities via substrate level phosphorylation reaction. Fermentation results in incomplete oxidation of substrate and hence is an inefficient process with a low ATP yield. However, some LAB are genetically capable of activating an auxiliary respiratory metabolism in which a quinol oxidase serves as the final electron acceptor and high ATP production is achieved due to oxidative phosphorylation. The respiratory process is associated with high biomass production of LAB and more robust bacterial cells, which are essentially required for manufacture of high viability starter culture. This chapter explores LAB's current and future applications in dairy starter cultures.
Conference papers on the topic "Oxidatie"
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MARIN, G. B. "HIGH TEMPERATURE OXIDATION PROCESSES: OXIDATIVE COUPLING OF METHANE." In Proceedings of the NIOK (Netherlands Institute for Catalysis Research) Course on Catalytic Oxidation. WORLD SCIENTIFIC, 1995. http://dx.doi.org/10.1142/9789814503884_0006.
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Kim, Jong-Nam, Chang Hyun Ko, Sang Sup Han, Hee Tae Beum, Jihye Park, and Sam Mok Lim. "Removal of Sulfur-Oxidated Compounds in Oxidative Desulfurization Process." In 14th Asia Pacific Confederation of Chemical Engineering Congress. Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-1445-1_500.
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Cheenkachorn, Kraipat, Wallis A. Lloyd, and Joseph M. Perez. "Use of Pressurized Differential Scanning Calorimetry (PDSC) to Evaluate Effectiveness of Additives in Vegetable Oil Lubricants." In ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0657.
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Use of renewable resources to replace petroleum base stocks in lubricants is attractive. Research on additives enhanced by current advances in genetic and chemical modifications has resulted in improved oxidative stability of vegetable oils. Like most oxidation processes, the oxidative degradation of vegetable oils is complex. The auto-oxidation free radical mechanisms and hydroperoxide theories of oxidation have been well studied. Factors that influence the degradation of oils include temperature, surface reactivity, rates of formation of radicals, chemical composition factors such as olefin and aromatic content and additive effectiveness. This uses pressurized differential scanning calorimetry to evaluate the oxidative stability of four biodegradable fluids with and without additives. The oleic acid content of the four fluids ranged from 83 to 23 percent. Reaction kinetics are used to explain observed differences in phase transformation and polymerization reactions. Additive selection to obtain maximum effectiveness in the base stocks is reported.
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Hendricks, Keshia, Eunice To, Ross Vlahos, Brad Broughton, Hitesh Peshavariya, and Stavros Selemidis. "Influenza A virus causes vascular endothelial cell oxidative stress via NOX2 oxidase." In ERS International Congress 2016 abstracts. European Respiratory Society, 2016. http://dx.doi.org/10.1183/13993003.congress-2016.pa3967.
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Devlin, Mark T., Randall E. Baren, Samuel H. Tersigni, and Tze-Chi Jao. "Effect of Detailed Base Oil Structure on Oxidation Performance of Automatic Transmission Fluids." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63563.
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Automatic transmission fluids (ATF) should be oxidatively stable so that their frictional properties are maintained as the fluids are aged. To test the oxidative stability of ATFs, automobile manufacturers have created oxidation tests in which ATFs are aged in operating transmissions. In these tests, the total acid number (TAN) of the oil is measured throughout the test, and at the end of the test the TAN of the oil must be below specified limits. In general, oxidation of oils occurs by formation of free radicals that can react with the oils to form acidic species that are detected by the TAN of the used oils [1, 2]. Peroxides also form when an oil is oxidized and the peroxides can react with the oil to form acids [1,2]. Base oil structure, presence of wear metals, and the amount of oxygen dissolved in the oil can all affect the oxidative stability of oils [1,2]. Therefore, we investigated how each of these three factors affect changes in TAN as oils are aged in the GM cycling and GM oxidation tests (GMOT). Base oil structure is the major factor affecting the oxidative stability of ATFs. In particular, we have found that the cyclo-paraffin concentration in the base oils used to formulate ATFs can be related to oxidative stability. The lower the number of cycloparaffins in the base oil, the better the oxidative stability of the ATF.
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Deshmukh, K., and K. S. V. Santhanam. "Polymeric Electrode for Sodium Borohydride Fuel Cell." In ASME 2004 2nd International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2004. http://dx.doi.org/10.1115/fuelcell2004-2513.
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Reported here is the first example of sodium borohydride fuel cell constructed with electro-active conducting Polycarbazole (Pcz) and oxygen cathode. A Pcz electrode is made by depositing a thin film of the polymer on Stainless Steel (SS) substrate. The multistage oxidation process of borohydride is expected to involve 8e− with borate as the end product. The oxidative process at the Pcz electrode has been examined by Cyclic Voltametry (CV). The direct oxidation of borohydride on SS was not observed in CV; however it is distinctly visible at the Pcz electrode. The borohydride oxidation at the Pcz electrode occurs at Ep = −0.29 V vs. saturated calomel electrode (SCE). The process was studied using scan rates of 10 mV/s to 100 mV/s. The anodic peak current increases linearly with the sweep rate and also with concentration of borohydride, suggesting that the oxidative process is diffusion controlled. The mechanism of borohydride oxidation has been investigated and compared with the oxidation on platinum or gold electrode. The results suggest that the borohydride fuel cell as operating efficiently with the Pcz anode or cathode. Preliminary results will be reported.
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Sobolev, Roman, Yuliya Frolova, Varuzhan Sarkisyan, and Alla Kochetkova. "Study of the Oxidative Stability of Oleogels Structured with Beeswax Fractions." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/zbfu3245.
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Combining the beeswax fractions is an effective way of structuring edible oils. However, their effect on oleogel oxidative stability is still not studied. Thus, the study on the influence of beeswax and combinations of its fractions on the edible oleogels oxidation was the objective of this research.Four fractions of beeswax (A, B, C, D) were isolated using preparative flash-chromatography and characterized by TLC and HPLC-ELSD. Sunflower oil was used to prepare oleogels (at 90 °C for 30 minutes) with a 6% of gelator. The fatty acid composition was evaluated by GC. The samples were stored at 35°C for 20 days, monitoring the oxidation using: PV, AV, CDV, TOTOX, HS-SPME-GC-MS. The induction period was determined using the OXITEST reactor.We have shown that fraction A contained hydrocarbons ( >99%); B - monoesters ( >95%); C - wax esters ( >66%), alcohols ( >29%), and free fatty acids ( >4%); D - alcohols ( >49%), free fatty acids ( >40%) and wax esters ( >10%). Combinations of A+B, A+B+C, and A+B+D gelators were made using fractions in equal amounts. The fatty acid composition of freshly prepared oleogels and oil didn't differ (p >0.05). Sunflower oil had the best oxidative stability among all samples. The A+B-based oleogel had the highest oxidative stability among the oleogels. Hexanal is shown to be the main volatile organic compound formed during the oxidation of sunflower oil. The volatile compounds profile of the oleogels also included ketones, alcohols, and terpenes. Beeswax-based oleogel had the lowest induction period, which indicates the presence of prooxidant components. A close correlation was found between the oxidation rate of oleogels and the content of free fatty acids (r2=0.8195) in the gelator.This study shows that the use of beeswax fractions, compared to beeswax itself, results in fat-containing products with higher oxidation stability.
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Lukasiewicz, Marcin, Szczepan Bednarz, Anna Ptaszek, et al. "Microwave assisted oxidative degradation of starch - estimation of degree of oxidation of the modified biopolymer." In The 11th International Electronic Conference on Synthetic Organic Chemistry. MDPI, 2007. http://dx.doi.org/10.3390/ecsoc-11-01347.
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Kriedt, Frederick A., Cedric F. Walker, Harvey T. Swanson, Sheldon F. Gottlieb, and Keith W. Van Meter. "Cytochrome oxidase reduction/oxidation charge-coupled monitor with large-area pickup optode." In BiOS 2000 The International Symposium on Biomedical Optics, edited by Anita Mahadevan-Jansen and Gerwin J. Puppels. SPIE, 2000. http://dx.doi.org/10.1117/12.384952.
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Raju, Gagan, Soumyabrata Banik, Sindhoora Kaniyala Melanthota, Yana Baycerova, Yury Kistenev, and Nirmal Mazumder. "Machine learning approach to study the effect of oxidation in edible almond oils using combined spectroscopy and principal component analysis." In Frontiers in Optics. Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.jw4a.13.
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Oxidative deterioration of edible oils makes it unfit for consumption and poses several serious health hazards on mankind. Present study employs PCA based machine learning along with spectroscopy to investigate the effect of oxidation on edible oils.
Reports on the topic "Oxidatie"
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Steffens, John, Eithan Harel, and Alfred Mayer. Coding, Expression, Targeting, Import and Processing of Distinct Polyphenoloxidases in Tissues of Higher Plants. United States Department of Agriculture, 1994. http://dx.doi.org/10.32747/1994.7613008.bard.
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Polyphenol oxidase (PPO) catalyzes the oxidation of phenols to quinones at the expense of O2. PPOs are ubiquitous in higer plants, and their role in oxidative browning of plant tissues causes large annual losses to food production. Despite the importance of PPOs to agriculture, the function(s) of PPOs in higher plants are not understood. Among other roles, PPOs have been proposed to participate in aspects of chloroplast metabolism, based on their occurrence in plastids and high Km for O2. Due to the ability of PPO to catalyze formation of highly reactive quinones, PPOs have also been proposed to be involved in a wide array of defensive interactions with insect, bacterial, and fungal pests. Physiological and biochemical studies of PPO have provided few answers to the major problems of PPO function, subcellular localization, and biochemical properties. This proposal achieved the following major objectives: cloning of PPO cDNAs in potato and tomato; characterization of the tomato PPO gene family; antisense downregulation of the tomato PPO gene family; and reduction in post-harvest enzymic browning of potato through expression of antisense PPO genes under the control of tuber-specific promoters. In addition, we established the lumenal localization of PPO, characterized and clarified the means by which PPOs are imported and processed by chloroplasts, and provided insight into the factors which control localization of PPOs. This proposal has thereby provided fundamental advances in the understanding of this enzyme and the control of its expression.
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Phelps, M. R., and W. A. Wilcox. Oxidative reduction of glove box wipers with a downdraft thermal oxidation system. Office of Scientific and Technical Information (OSTI), 1996. http://dx.doi.org/10.2172/239332.
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Schutt, Timothy C., and Manoj K. Shukla. Computational Investigation on Interactions Between Some Munitions Compounds and Humic Substances. Engineer Research and Development Center (U.S.), 2021. http://dx.doi.org/10.21079/11681/39703.
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Humic acid substances (HAs) in natural soil and sediment environments effect the retention and degradation of insensitive munitions compounds and legacy high explosives (MCs): DNAN, DNi- NH4+, nMNA, NQ, NTO (neutral and anionic forms), TNT, and RDX.A humic acid model compound has been considered using molecular dynamics, thermodynamic integration, and density functional theory to characterize the munition binding ability, ionization potential, and electron affinity compared to that in the water solution. Humic acids bind most compounds and act as both a sink and source for electrons. Ionization potentials suggest HAs are more susceptible to oxidation than the MCs studied. The electron affinity of HAs are very conformation-dependent and spans the same range as the munition compounds. When HAs and MCs are complexed the HAs tend to radicalize first thus buffering MCs against reductive as well as oxidative attacks.
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Apostolov, Anton A. On the Oxidation Induction Time and Oxidation Induction Temperature for Characterization of the Oxidative Stability of Poly(ethylene-co-propylene) Pipes. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, 2018. http://dx.doi.org/10.7546/crabs.2018.01.05.
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Apostolov, Anton A. On the Oxidation Induction Time and Oxidation Induction Temperature for Characterization of the Oxidative Stability of Poly(ethylene-co-propylene) Pipes. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, 2018. http://dx.doi.org/10.7546/grabs2018.1.05.
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Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
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To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Horwitz, Benjamin A., and Barbara Gillian Turgeon. Fungal Iron Acquisition, Oxidative Stress and Virulence in the Cochliobolus-maize Interaction. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7709885.bard.
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Our project focused on genes for high affinity iron acquisition in Cochliobolus heterostrophus, a necrotrophic pathogen of maize, and their intertwined relationship to oxidative stress status and virulence of the fungus on the host. An intriguing question was why mutants lacking the nonribosomal peptide synthetase (NRPS) gene (NPS6) responsible for synthesis of the extracellular siderophore, coprogen, are sensitive to oxidative stress. Our overall objective was to understand the mechanistic connection between iron stress and oxidative stress as related to virulence of a plant pathogen to its host. The first objective was to examine the interface where small molecule peptide and reactive oxygen species (ROS) mechanisms overlap. The second objective was to determine if the molecular explanation for common function is common signal transduction pathways. These pathways, built around sensor kinases, response regulators, and transcription factors may link sequestering of iron, production of antioxidants, resistance to oxidative stress, and virulence. We tested these hypotheses by genetic manipulation of the pathogen, virulence assays on the host plant, and by following the expression of key fungal genes. An addition to the original program, made in the first year, was to develop, for fungi, a genetically encoded indicator of redox state based on the commercially available Gfp-based probe pHyper, designed for animal cell biology. We implemented several tools including a genetically encoded indicator of redox state, a procedure to grow iron-depleted plants, and constructed a number of new mutants in regulatory genes. Lack of the major Fe acquisition pathways results in an almost completely avirulent phenotype, showing how critical Fe acquisition is for the pathogen to cause disease. Mutants in conserved signaling pathways have normal ability to regulate NPS6 in response to Fe levels, as do mutants in Lae1 and Vel1, two master regulators of gene expression. Vel1 mutants are sensitive to oxidative stress, and the reason may be underexpression of a catalase gene. In nps6 mutants, CAT3 is also underexpressed, perhaps explaining the sensitivity to oxidative stress. We constructed a deletion mutant for the Fe sensor-regulator SreA and found that it is required for down regulation of NPS6 under Fe-replete conditions. Lack of SreA, though, did not make the fungus over-sensitive to ROS, though the mutant had a slow growth rate. This suggests that overproduction of siderophore under Fe-replete conditions is not very damaging. On the other hand, increasing Fe levels protected nps6 mutants from inhibition by ROS, implying that Fe-catalyzed Fenton reactions are not the main factor in its sensitivity to ROS. We have made some progress in understanding why siderophore mutants are sensitive to oxidative stress, and in doing so, defined some novel regulatory relationships. Catalase genes, which are not directly related to siderophore biosynthesis, are underexpressed in nps6 mutants, suggesting that the siderophore product (with or without bound Fe) may act as a signal. Siderophores, therefore, could be a target for intervention in the field, either by supplying an incorrect signal or blocking a signal normally provided during infection. We already know that nps6 mutants cause smaller lesions and have difficulty establishing invasive growth in the host. Lae1 and Vel1 are the first factors shown to regulate both super virulence conferred by T-toxin, and basic pathogenicity, due to unknown factors. The mutants are also altered in oxidative stress responses, key to success in the infection court, asexual and sexual development, essential for fungal dissemination in the field, aerial hyphal growth, and pigment biosynthesis, essential for survival in the field. Mutants in genes encoding NADPH oxidase (Nox) are compromised in development and virulence. Indeed the triple mutant, which should lack all Nox activity, was nearly avirulent. Again, gene expression experiments provided us with initial evidence that superoxide produced by the fungus may be most important as a signal. Blocking oxidant production by the pathogen may be a way to protect the plant host, in interactions with necrotrophs such as C. heterostrophus which seem to thrive in an oxidant environment.
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Handa, Avtar K., Yuval Eshdat, Avichai Perl, Bruce A. Watkins, Doron Holland, and David Levy. Enhancing Quality Attributes of Potato and Tomato by Modifying and Controlling their Oxidative Stress Outcome. United States Department of Agriculture, 2004. http://dx.doi.org/10.32747/2004.7586532.bard.
Full textAbstract:
General The final goal and overall objective of the current research has been to modify lipid hydroperoxidation in order to create desirable phenotypes in two important crops, potato and tomato, which normally are exposed to abiotic stress associated with such oxidation. The specific original objectives were: (i) the roles of lipoxygenase (LOX) and phospholipids hydroperoxide glutathione peroxidase (PHGPx) in regulating endogenous levels of lipid peroxidation in plant tissues; (ii) the effect of modified lipid peroxidation on fruit ripening, tuber quality, crop productivity and abiotic stress tolerance; (iii) the effect of simultaneous reduction of LOX and increase of PHGPx activities on fruit ripening and tuber quality; and (iv) the role of lipid peroxidation on expression of specific genes. We proposed to accomplish the research goal by genetic engineering of the metabolic activities of LOX and PHGPx using regulatable and tissue specific promoters, and study of the relationships between these two consecutive enzymes in the metabolism and catabolism of phospholipids hydroperoxides. USA Significant progress was made in accomplishing all objectives of proposed research. Due to inability to regenerate tomato plants after transforming with 35S-PHGPx chimeric gene construct, the role of low catalase induced oxidative stress instead of PHGPx was evaluated on agronomical performance of tomato plant and fruit quality attributes. Effects of polyamine, that protects DNA from oxidative stress, were also evaluated. The transgenic plants under expressing lipoxygenase (LOX-sup) were crossed with catalase antisense (CAT-anti) plants or polyamine over producing plants (SAM-over) and the lines homozygous for the two transgenes were selected. Agronomical performance of these line showed that low catalase induced oxidative stress negatively affected growth and development of tomato plants and resulted in a massive change in fruit gene expression. These effects of low catalase activity induced oxidative stress, including the massive shift in gene expression, were greatly overcome by the low lipoxygenase activity. Collectively results show that oxidative stress plays significant role in plant growth including the fruit growth. These results also for the first time indicated that a crosstalk between oxidative stress and lipoxygenase regulated processes determine the outcome during plant growth and development. Israel Regarding PHGPx, most of the study has concentrated on the first and the last specific objectives, since it became evident that plant transformation with this gene is not obvious. Following inability to achieve efficient transformation of potato and tomato using a variety of promoters, model plant systems (tobacco and potato cell cultures, tobacco calli and plantlets, and Arabidopsis) were used to establish the factors and to study the obstacles which prohibited the regeneration of plants carrying the genetic machinery for overproduction of PHGPx. Our results clearly demonstrate that while genetic transformation and over-expression of PHGPx occurs in pre-developmental tissue stage (cell culture, calli clusters) or in completed plant (Arabidopsis), it is likely that over-expression of this enzyme before tissue differentiation is leading to a halt of the regeneration process. To support this assumption, experiments, in which genetic engineering of a point-mutated PHGPx gene enable transformation and over-expression in plants of PhSPY modified in its catalytic site and thus inactive enzymatically, were successfully carried out. These combined results strongly suggest, that if in fact, like in animals and as we established in vitro, the plant PHGPx exhibits PH peroxidase activity, these peroxides are vital for the organisms developmental process.
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Pesis, Edna, and Mikal Saltveit. Postharvest Delay of Fruit Ripening by Metabolites of Anaerobic Respiration: Acetaldehyde and Ethanol. United States Department of Agriculture, 1995. http://dx.doi.org/10.32747/1995.7604923.bard.
Full textAbstract:
The use of pretreatments for 24 h prior to storage, under anaerobic condtions, or in the presence of the natural metabolic products, acetaldehyde (AA) and ethanol, to delay fruit ripening, was found to be effective with several climacteric fruits, among them avocado, mango, peach and tomato. The delay in ripening of avocado, peach and tomato was accompanied by inhibition of ethylene production and of fruit softening. The maintenance of fruit firmness was associated with a decrease in the activities of cell-wall-degrading enzymes, including endoglucanases (Cx), polygalacturonases (PG) and b-galactosidases. In peaches the AA- and N2-treated fruits were firmer after 3 weeks storage and contained higher amount of insoluble pectin than untreated controls. We showed that AA vapors are able to inhibit ripening, ethylene production and ethylene induction in the presence of 1-amino-cyclopropane-1-carboxylic acid (ADD) in avocado and mango tissue. Ethylene induced by ACC is taken as an indicator of ACC oxidase activity. ACC oxidase activity in AA-treated avocado fruit was much lower than in the untreated fruit. In carnation flowers very little ethylene was produced by ethanol-treated flowers, and the normal increases in ACC content and ACC oxidase activity were also suppressed. Using kinetic studies and inhibitors of alcohol dehydrogenase (ADH), we showed that AA, not ethanol, was the active molecule in inhibiting ripening of tomato fruit. Application of anaerobiosis or anaerobic metabolites was effective in reduction of chilling injury (CI) in various plant tissues. Pretreatment with a low-O2 atmosphere reduced CI symptoms in avocado; this effect was associated with higher content of the free sylfhydryl (SH) group, and induction of the detoxification enzymes, catalase and peroxidase. Application of AA maintained firmer and brighter pulp tissue (non-oxidative), which was associated with higher free SH content, lower ethylene and ACC oxidase activities, and higher activities of catalase and peroxidase. Ethanol was found to reduce CI in other plant tissue. In roots of 24-h-old germinated cucumber seeds, exposure to 0.4-M ethanol shock for 4 h reduced chilling-induced ion leakage. In cucumber cotyledons it appears that alcohols may reduce CI by inducing stomata closure. In cotyledon discs held in N2 at 10C for 1 day, there accumulated sufficient endogenously synthesized ethanol to confer tolerance to chilling at 2.5C for 5 days.
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Charles A. Gentile, John J. Parker, Gregory L. Guttadora, and Lloyd P. Ciebiera. Oxidative Tritium Decontamination System. Office of Scientific and Technical Information (OSTI), 2002. http://dx.doi.org/10.2172/796125.
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