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Influence of the antioxidants vitamin E and idebenone on retinal cell injury mediated by chemical ischemia, hypoglycemia, or oxidative stress

Rego, Ana Cristina; Santos, Maria Sancha; Oliveira, Catarina R.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
Português
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66.28%
A role for the antioxidants vitamin E and idebenone in decreasing retinal cell injury, after metabolic inhibition induced by chemical ischemia and hypoglycemia, was investigated and compared with oxidative stress conditions. Preincubation of the antioxidants, vitamin E (20 [mu]M) and idebenone (10 [mu]M), effectively protected from retinal cell injury after oxidative stress or hypoglycemia, whereas the protection afforded after postincubation of both antioxidants was decreased. Delayed retinal cell damage, mediated by chemical ischemia, was attenuated at 10 or 12 h postischemia, only after exposure to the antioxidants during all the experimental procedure. An antagonist of the N-methyl--aspartate (NMDA) receptors, an inhibitor of nitric oxide synthase (NOS) or a blocker of -type Ca2+ channels were ineffective in reducing cell injury induced by chemical ischemia, hypoglycemia or oxidative stress. Oxidative stress and hypoglycemia increased (about 1.2-fold) significantly the fluorescence of the probe DCFH2-DA, that is indicative of intracellular ROS formation. Free radical generation detected with the probe dihydrorhodamine 123 (DHR 123) was enhanced after oxidative stress, chemical ischemia or hypoglycemia (about 2-fold). Nevertheless...

Inducible Nitric Oxide Synthase Inhibition Attenuates Physical Stress-Induced Lung Hyper-Responsiveness and Oxidative Stress in Animals with Lung Inflammation

Marques, Ricardo Henrique; Reis, Fabiana G.; Starling, Claudia M.; Cabido, Claudia; de Almeida-Reis, Rafael; Dohlnikoff, Marisa; Prado, Carla M.; Leick, Edna A.; Martins, Milton A.; Tiberio, Iolanda F. L. C.
Fonte: KARGER; BASEL Publicador: KARGER; BASEL
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.28%
Mechanisms involved in stress-induced asthmatic alterations have been poorly characterised. We assessed whether inducible nitric oxide synthase (iNOS) inhibition modulates the stress-amplified lung parenchyma responsiveness, oxidative stress and extracellular matrix remodelling that was previously increased by chronic lung inflammation. Guinea pigs were subjected to 7 exposures to ovalbumin (1-5 mg/ml) or saline (OVA and SAL groups) over 4 weeks. To induce behavioural stress, animals were subjected to a forced swimming protocol (5 times/week, over 2 weeks; SAL-Stress and OVA-Stress groups) 24 h after the 4th inhalation. 1400W (iNOS-specific inhibitor) was administered intraperitoneally in the last 4 days of the protocol (SAL-1400W, OVA-1400W, SAL-Stress+1400W and OVA-Stress+1400W groups). Seventy-two hours after the last inhalation, animals were anaesthetised and exsanguinated, and adrenal glands were removed. Lung tissue resistance and elastance were evaluated by oscillatory mechanics and submitted for histopathological evaluation. Stressed animals had higher adrenal weights compared to non-stressed groups, which were reduced by 1400W treatment. Behavioural stress in sensitised animals amplified the resistance and elastance responses after antigen challenge...

Decreased oxidative stress in patients with ulcerative colitis supplemented with fish oil omega-3 fatty acids

Barbosa, D. S.; Cecchini, R.; El Kadri, M. Z.; Rodriguez, MAM; Burini, R. C.; Dichi, I
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 837-842
Português
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OBJECTIVE: the potential pathogenicity of free radicals may have a pivotal role in ulcerative colitis. Fish oil omega-3 fatty acids exert anti-inflammatory effects on patients with ulcerative colitis (UC), but the precise mechanism of the action of fish oil on oxidative stress is still controversial. The aim of the present work was to verify the blood oxidative stress in patients with UC and determine whether the association of sulfasalazine to fish oil omega-3 fatty acids is more effective than isolated use of sulfasalazine to reduce the oxidative stress.METHODS:, Nine patients (seven female and two male; me. an age = 40 +/- 11 y) with mild or moderate active UC were studied in a randomized crossover design. In addition to their usual medication (2 g/d of sulfasalazine), they received fish oil omega-3 fatty acids (4.5 g/d) or placebo for 2-mo treatment periods that were separated by 2 mo, when they only received sulfasalazine. Nine healthy individuals served as control subjects to study the oxidative stress status. Disease activity was assessed by laboratory indicators (C-reactive protein, alpha(1)-acid glycoprotein, alpha(1)-antitrypsin, erythrocyte sedimentation rate, albumin, hemoglobin, and platelet count), sigmoidoscopy, and histology scores. Analysis of oxidative stress was assessed by plasma chemiluminescence and erythrocyte lipid peroxidation...

Evaluation of a protein deficient diet in rats through blood oxidative stress biomarkers

Prada, F. J A; Macedo, D. V.; De Mello, Maria Alice Rostom
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 213-228
Português
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Protein malnutrition leads to functional impairment in several organs, which is not fully restored with nutritional recovery. Little is known about the role of oxidative stress in the genesis of these alterations. This study was designed to assess the sensitivity of blood oxidative stress biomarkers to a dietary protein restriction. Male Wistar rats were divided into two groups, according to the diet fed from weaning (21 days) to 60 day old: normal protein (17% protein) and low protein (6% protein). Serum protein, albumin, free fatty acid and liver glycogen and lipids were evaluated to assess the nutritional status. Blood glutathione reductase (GR) and catalase (CAT) activities, plasma total sulfhydryl groups concentration (TSG) as well as plasma thiobarbituric acid reactive substances (TBARs) and reactive carbonyl derivatives (RCD) were measured as biomarkers of the antioxidant system and oxidative damage, respectively. The glucose metabolism in soleus muscle was also evaluated as an index of stress severity imposed to muscular mass by protein malnutrition. No difference was observed in muscle glucose metabolism or plasma RCD concentration between both groups. However, our results showed that the low protein group had higher plasma TBARs (62%) concentration and lower TSG (44%) concentration than control group...

Possíveis marcadores de estresse oxidativo para câncer de pele não melanoma : efeito da suplementação de vitamina C, E e mineral zinco em indivíduos que tiveram câncer de pele não melanoma; Possibles markers of oxidative stress for non- melanoma skin câncer : effect of suplemmentation of vitamin C,E e zinc in individuals who had non-melanoma skin cancer

Betânia de Jesus e Silva de Almendra Freitas
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/07/2014 Português
Relevância na Pesquisa
66.33%
Estudos acerca da influência do estresse oxidativo sobre o equilíbrio cutâneo, sobretudo por seus efeitos devastadores sobre a integridade da pele, são essenciais para a proposição de estratégias de intervenção preventivas para o desenvolvimento do câncer de pele. O objetivo do estudo foi comparar o estresse oxidativo de indivíduos que tiveram e não tiveram câncer de pele não melanoma e avaliar o efeito da suplementação combinada de vitaminas C, E e mineral Zinco no estresse oxidativo de indivíduos que apresentaram a doença. O estudo foi dividido em duas fases: a fase 1 foi um estudo transversal com controles, cuja população foi constituída por pessoas saudáveis (n = 24) e o grupo caso constituído por indivíduos que apresentaram câncer de pele não melanoma já submetidas a tratamento cirúrgico (n = 60). E a fase 2, um ensaio clínico randomizado e duplo cego, no qual os pacientes do grupo caso foram randomizados em dois subgrupos: grupo placebo (n = 34) e grupo suplementado (n = 26) com 50 mg de vitamina C, 60 mg de vitamina E e 40 mg de Zinco durante 8 semanas. As amostras de sangue dos sujeitos foram obtidas no período basal e após intervenção para a avaliação dos biomarcadores de estresse oxidativo (F2-isoprostano...

Estresse oxidativo em Leishmania amazonensis : do encurtamento dos telômeros ao deslocamento de LaRPA-1 do complexo telomérico = Oxidative stress in Leishmania amazonensis : from telomere shortening to displacement of LaRPA-1 from telomeric complex; Oxidative stress in Leishmania amazonensis : from telomere shortening to displacement of LaRPA-1 from telomeric complex

Marcelo Santos da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/08/2014 Português
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66.33%
A leishmaniose é um espectro de doenças causadas por parasitos do gênero Leishmania, que afeta milhões de pessoas em todo o mundo. Durante a infecção, os parasitos usam diferentes estratégias para sobreviver as defesas do hospedeiro, incluindo superar a exposição intensa a espécies reativas de oxigênio (ROS), principais responsáveis por causar danos no DNA, sobretudo nos telômeros, induzindo instabilidade genômica, senescência e morte celular. Telômeros são estruturas nos terminais dos cromossomos compostos por sequências de DNA repetitivas e proteínas, cuja função é proteger as extremidades dos cromossomos, evitando fusões terminais e degradação nucleolítica. Neste trabalho nós induzimos estresse oxidativo agudo em formas promastigotas de L. amazonensis através do tratamento com 2 mM de peróxido de hidrogênio (H2O2) por 1h, o qual foi capaz de aumentar os níveis de ROS intracelular, como demonstrado pela reação utilizando CM-H2DCFDA. Além disso, o estresse oxidativo induziu danos no DNA, como mostrado por análise quantitativa de 8-oxodG e núcleos positivos para o ensaio TUNEL. Observamos também, através de parâmetros qualitativos e quantitativos (Southern blot, telomere-PCR e flow-FISH), que o estresse oxidativo...

Efeitos do ômega-3 em marcadores de estresse oxidativo em músculos distróficos do camundongo mdx; Effects of omega-3 therapy on markes of oxidative stress in dystrophic muscles of the mdx mice

Viviane Panegassi Perim
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/03/2015 Português
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A Distrofia Muscular de Duchenne (DMD) é uma doença causada pela ausência da proteína distrofina e se caracteriza por degeneração muscular progressiva. A deficiência da distrofina na DMD e nos camundongos mdx, modelo experimental da DMD, promove mionecrose. O processo inflamatório que se instala exacerba a mionecrose e aumenta o estresse oxidativo. O estresse oxidativo tem sido proposto como um fator importante para a progressão da doença. As espécies reativas de oxigênio promovem danos nas fibras distróficas, comprometendo proteínas e lipídios da membrana, gerando grandes quantidades de lipofuscina e 4-HNE, indicadores de estresse oxidativo. Este trabalho tem como objetivo verificar se o ômega-3 diminui o estresse oxidativo em diferentes músculos distróficos (bíceps, diafragma e quadríceps) do camundongo mdx jovem. Observamos que o ômega-3 diminuiu a lipofuscina e o 4-HNE nos músculos estudados. A atividade das enzimas antioxidantes SOD, GPx e GR estava aparentemente diminuída no diafragma distrófico, quando comparado ao diafragma normal. No diafragma, o ômega-3 promoveu aumento discreto da atividade da SOD e da GPx. O músculo quadríceps não apresentou alterações significativas destas enzimas, tanto no mdx controle...

Oxidative stress markers, cognitive functions, and psychosocial functioning in bipolar disorder: an empirical cross-sectional study

Aydemir,Ömer; Çubukçuoğlu,Zeynep; Erdin,Soner; Taş,Cumhur; Onur,Ece; Berk,Michael
Fonte: Associação Brasileira de Psiquiatria - ABP Publicador: Associação Brasileira de Psiquiatria - ABP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 Português
Relevância na Pesquisa
66.3%
Objective: This study aimed to evaluate the relationship between oxidative stress markers and cognitive functions and domains of psychosocial functioning in bipolar disorder. Methods: Oxidative stress markers, cognitive functions, and domains of psychosocial functioning were evaluated in 51 patients with bipolar disorder who were in remission. Correlation analyses between these parameters were calculated with data controlled for duration of illness and number of episodes. Results: There was no statistically significant correlation between oxidative stress markers and cognitive functions. In terms of psychosocial functioning, significant correlations were found between malondialdehyde and sense of stigmatization (r = -0.502); household activities and superoxide dismutase (r = 0.501); participation in social activities and nitric oxide (r = 0.414); hobbies and leisure time activities and total glutathione (r = -0.567), superoxide dismutase (r = 0.667), and neurotrophin 4 (r = 0.450); and taking initiative and self-sufficiency and superoxide dismutase (r = 0.597). There was no correlation between other domains of psychosocial functioning and oxidative stress markers. Conclusion: These results imply that oxidative stress markers do not appear to correlate clearly with cognitive impairment and reduced psychosocial functioning. However...

JNK-Regulated Autophagy as a Defensive Mechanism Against Oxidative Stress in Drosophila Melanogaster

Wu, Hai ; Bohmann, Dirk
Fonte: Universidade de Rochester Publicador: Universidade de Rochester
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
66.38%
Thesis (Ph.D.)--University of Rochester. School of Medicine and Dentistry. Dept. of Biomedical Genetics, 2009.; Organisms commonly encounter oxidative stress originating from endogenous sources or in the form of exogenous stressors. Oxidative stress has been implicated in the pathogenesis of various diseases and aging. Thus, boosting the resistance against oxidative stress might be a strategy to delay or prevent the onset of diseases, promote organismal survival, and slow down aging. Recent findings have implicated autophagy, a conserved catabolic process, into the cellular defense against various biological and xenobiotic stresses including oxidative stress. However, the regulation of autophagy in response to oxidative stress remains largely elusive. One central regulatory system of the organism’s defense against oxidative stress is the JNK pathway. It has been shown previously that JNK gain-of-function mutants are more resistant to acute stress exposure. Furthermore, the JNK pathway has been reported to affect the lifespan of metazoans, presumably be deflecting oxidative damage. The downstream effectors of JNK in this context are not completely understood. In this thesis, I studied the regulation of autophagy by JNK signaling upon oxidative stress exposure...

Oxidative stress in psychiatric disorders: evidence base and therapeutic implications

Ng, F.; Berk, M.; Dean, O.; Bush, A.
Fonte: Cambridge Univ Press Publicador: Cambridge Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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66.31%
Oxidative stress has been implicated in the pathogenesis of diverse disease states, and may be a common pathogenic mechanism underlying many major psychiatric disorders, as the brain has comparatively greater vulnerability to oxidative damage. This review aims to examine the current evidence for the role of oxidative stress in psychiatric disorders, and its academic and clinical implications. A literature search was conducted using the Medline, Pubmed, PsycINFO, CINAHL PLUS, BIOSIS Previews, and Cochrane databases, with a time-frame extending to September 2007. The broadest data for oxidative stress mechanisms have been derived from studies conducted in schizophrenia, where evidence is available from different areas of oxidative research, including oxidative marker assays, psychopharmacology studies, and clinical trials of antioxidants. For bipolar disorder and depression, a solid foundation for oxidative stress hypotheses has been provided by biochemical, genetic, pharmacological, preclinical therapeutic studies and one clinical trial. Oxidative pathophysiology in anxiety disorders is strongly supported by animal models, and also by human biochemical data. Pilot studies have suggested efficacy of N-acetylcysteine in cocaine dependence...

Investigation of the role of oxidative stress in male infertility.

Tunc, Ozlem
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011 Português
Relevância na Pesquisa
66.38%
In recent years, there has been some suggestion of an increase in male factor infertility in the industrialized countries with a decline in sperm counts and a rise in sperm pathology. Male factor infertility is a multifactorial phenomenon that is observed in approximately half of infertile couples and affects one man in 20 in the general population. The potential causes of male infertility arise from a number of factors including genetic, lifestyle factors and chronic diseases. However, a high proportion of infertile male patients have now been shown to have defective sperm functions related to oxidative stress. Oxidative stress in semen has been speculated as one of the major factors causing male infertility and has been identified in 30-80% of cases of male infertility. While oxidative stress is accepted as a significant pathology, there is currently an inadequate knowledge of the exact mechanisms by which oxidative stress develops in male infertility, as well as a lack of an easy and reliable method for the measurement of seminal oxidative stress in routine clinical use. The main objective of this doctoral thesis is to investigate the underlying causes for oxidative stress in infertile men and the mechanisms by which oxidative stress develops. Furthermore it will also examine the effectiveness of an oral antioxidant therapy for treatment of seminal oxidative stress. During these doctoral studies experiments were designed with the aims of: • Developing a standardized protocol for the measurement of seminal oxidative stress...

Molecular responses to low oxygen levels/oxidative stress in zebrafish.

Moussavi Nik, Seyyed Hani
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011 Português
Relevância na Pesquisa
66.3%
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with pathologies such as neuron loss, glial cell proliferation, extracellular deposition of senile plaques from the accumulation of amyloid beta (Aβ) peptides and deposition of intracellular neurofibrillary tangles. Aβ is created from the cleavage of the Amyloid Precursor Protein (APP) by two different types of aspartyl proteases, β- and γ-secretase. The majority of AD cases are sporadic and have a late onset.Mutations in the genes encoding APP, PRESENILIN1 and 2 (PSEN1 and PSEN2) genes cause an autosomal dominant inherited form of the disease with an early onset known as familial AD. In some sporadic cases an aberrant splice variant of PSEN2named PS2V is formed that can be found in inclusion bodies in the brain. PS2V results from the binding of the High Mobility Group A1a (HMGA1a) protein close to the splice donor site of exon 5 of PSEN2. The High Mobility Group A1 protein,HMGA1, is widely expressed during embryo development but not in adults. Its expression can be induced in adult neurons by hypoxia/oxidative stress and it is commonly reactivated in many types of cancer. Hypoxia can be a direct consequence of hypoperfusion, a common vascular component among Alzheimer’s disease risk factors and may play an important role in AD pathogenesis. BETA-SITE AMYLOID BETA A4 PRECURSOR PROTEIN-CLEAVING ENZYME 1...

The role of TRPM2 channels in oxidative stress-induced liver damage.

Kheradpezhouh. Ehsan
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015 Português
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66.33%
The increased production of highly reactive oxygen and nitrogen species plays a significant role in development of a number of liver disorders associated with hepatocellular death and impaired cell regeneration. Liver injury induced by drug toxicity, ischemia-reperfusion, excessive alcohol consumption and different types of viral hepatitis is in large part mediated by oxidative stress. Liver damage due to oxidative stress induced by drugs, including acetaminophen, accounts for 5% of all hospital admissions and for almost half of all acute liver failures. One of the features of hepatocellular death mediated by oxidative stress is Ca²⁺ overload due its release from intracellular organelles and activation of ion channels on the plasma membrane. Ca²⁺ is fundamental for normal cellular functioning. Ca²⁺ signalling, mediated by the rise in free cytoplasmic Ca²⁺ concentration ([Ca²⁺]c)[c subscript], regulates many cellular events. However, a sustained rise in [Ca²⁺]c [c subscript] can be detrimental, leading to mitochondrial dysfunction and cell death through apoptosis and necrosis. Although it is well recognised that Ca²⁺ plays a significant role in oxidative stress-induced liver damage, the molecular identities of the ion channels that provide a pathway for Ca²⁺ entry in hepatocytes remain unidentified. One of the potential candidates that could be responsible for such Ca²⁺ entry pathway in hepatocytes is Transient Receptor Potential Melastatin 2 (TRPM2) channel. TRPM2 is a non-selective cation channel permeable to Na⁺ and Ca²⁺. The main physiological activator of TRPM2 channel is ADP-ribose...

Untersuchungen zur Bedeutung von oxidativem Stress bei Präeklampsie; Investigations about the importance of oxidative stress in preeclampsia

Amraei Davijani, Felor
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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66.36%
Präeklampsie ist eine der häufigsten schwerwiegenden Schwangerschafts-Komplikationen, die durch Hypertonie, Proteinurie und Ödeme charakterisiert ist. Die Pathogenese ist weitgehend unklar. Viele Untersuchungen legen nahe, dass Präeklampsie mit oxidativem Stress im mütterlichen Organismus verbunden ist. In der vorliegenden Arbeit wurden zunächst Indikatoren des oxidativen Stresses durch in-vitro-Versuche charakterisiert. Dabei wurde mit H2O2, t-BHP, KO2 und Xanthin/XOD künstlicher oxidativer Stress im Plasma gesunder Probandinnen induziert. Zur Erfassung der Parameter für oxidativen Stress diente die gesamte antioxidative Kapazität (TRAP) sowie die Peakhöhe der Chemilumineszenz der AAPH-Reaktion (2,2’-Azobis (2-amidiniopropan)-hydrochlorid). Diese wurde durch die verwendeten Oxidantien vermindert. Zusätzlich wurden die Konzentrationen der Thiole im Plasma untersucht. Unter der Einwirkung der Oxidantien wurde eine Abnahme der freien Thiolgruppen, vor allem der an Proteine gebundenen, im Plasma festgestellt. Auf die Malondialdehyd-Konzentration hatte die Inkubation mit H2O2 keinen Effekt, t-BHP verursachte eine Zunahme. Auch bei der Wirkung auf die ATP-Konzentration in Erythrozyten wurde eine viel stärkere Abnahme des ATP durch t-BHP im Vergleich zu H2O2 gefunden. Danach wurde durch klinisch-chemische Blutanalyse der Frage nachgegangen...

Oxidative Stress Mediates Physiological Costs of Begging in Magpie (Pica pica) Nestlings

Moreno-Rueda, Gregorio; Redondo, Tom??s; Trenzado Romero, Cristina E.; Sanz Rus, Ana; Z????iga, Jes??s M.
Fonte: Public Library of Science (PLOS) Publicador: Public Library of Science (PLOS)
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
66.3%
[Background] Theoretical models predict that a cost is necessary to guarantee honesty in begging displays given by offspring to solicit food from their parents. There is evidence for begging costs in the form of a reduced growth rate and immunocompetence. Moreover, begging implies vigorous physical activity and attentiveness, which should increase metabolism and thus the releasing of pro-oxidant substances. Consequently, we predict that soliciting offspring incur a cost in terms of oxidative stress, and growth rate and immune response (processes that generate pro-oxidants substances) are reduced in order to maintain oxidative balance. [Methodology/Principal Findings] We test whether magpie (Pica pica) nestlings incur a cost in terms of oxidative stress when experimentally forced to beg intensively, and whether oxidative balance is maintained by reducing growth rate and immune response. Our results show that begging provokes oxidative stress, and that nestlings begging for longer bouts reduce growth and immune response, thereby maintaining their oxidative status. [Conclusions/Significance] These findings help explaining the physiological link between begging and its associated growth and immunocompetence costs, which seems to be mediated by oxidative stress. Our study is a unique example of the complex relationships between the intensity of a communicative display (begging)...

Status de selênio de uma população residente em área de risco de contaminação por mercúrio. Influência de polimorfismos e ação sobre o estresse oxidativo; Selenium status of a population living in a mercury contamination risk area. Influence of polymorphisms and action on oxidative stress

Rocha, Ariana Vieira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/02/2015 Português
Relevância na Pesquisa
66.32%
Estudos apontam que a região Amazônica apresenta concentrações significativas de selênio nos solos e que, por isso, a população não estaria susceptível à deficiência desse mineral. Em contrapartida, a região também apresenta dados de concentrações elevadas de mercúrio nos solos e rios, entretanto, a população não apresenta sinais clínicos evidentes de contaminação. Acredita-se que o selênio, um mineral antioxidante, possa ser um possível colaborador para a aparente tolerância ao mercúrio, pois uma das ações desse mineral é a de destoxificar o organismo contra metais tóxicos. Dependendo das concentrações no organismo, o mercúrio pode potencializar a geração das espécies reativas de oxigênio e, dessa forma, as defesas antioxidantes intrínsecas das células podem ser prejudicadas, resultando na condição conhecida por estresse oxidativo. A contaminação por mercúrio pode, ainda, comprometer a saúde tanto das mulheres quanto das crianças, pois esse metal, na forma de metilmercúrio, pode atravessar a barreira placentária e se concentrar, principalmente, no cérebro do feto. Aliado a isso, a presença de polimorfismos em certos genes podem alterar a expressão de enzimas antioxidantes como a glutationa peroxidase 1...

Exercise and oxidative stress: p,otential effects of antioxidant dietary strategies in sports

Pingitore, Alessandro; Pereira Lima, Giuseppina Pace; Mastorci, Francesca; Quinones, Alfredo; Iervasi, Giorgio; Vassalle, Cristina
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Revisão Formato: 916-922
Português
Relevância na Pesquisa
66.3%
Free radicals are produced during aerobic cellular metabolism and have key roles as regulatory mediators in signaling processes. Oxidative stress reflects an imbalance between production of reactive oxygen species and an adequate antioxidant defense. This adverse condition may lead to cellular and tissue damage of components, and is involved in different physiopathological states, including aging, exercise, inflammatory, cardiovascular and neurodegenerative diseases, and cancer. In particular, the relationship between exercise and oxidative stress is extremely complex, depending on the mode, intensity, and duration of exercise. Regular moderate training appears beneficial for oxidative stress and health. Conversely, acute exercise leads to increased oxidative stress, although this same stimulus is necessary to allow an up-regulation in endogenous antioxidant defenses (hormesis). Supporting endogenous defenses with additional oral antioxidant supplementation may represent a suitable noninvasive tool for preventing or reducing oxidative stress during training. However, excess of exogenous antioxidants may have detrimental effects on health and performance. Whole foods, rather than capsules, contain antioxidants in natural ratios and proportions...

Effect of oxidative stress upon absorption of glucose by the human placenta: in vitro studies with BeWo cells

Pereira, Ana Cláudia
Fonte: Instituto Politécnico do Porto. Escola Superior de Tecnologia da Saúde do Porto Publicador: Instituto Politécnico do Porto. Escola Superior de Tecnologia da Saúde do Porto
Tipo: Dissertação de Mestrado
Publicado em //2012 Português
Relevância na Pesquisa
66.31%
Pregnancy is a dynamic state and the placenta is a temporary organ that, among other important functions, plays a crucial role in the transport of nutrients and metabolites between the mother and the fetus, which is essential for a successful pregnancy. Among these nutrients, glucose is considered a primary source of energy and, therefore, fundamental to insure proper fetus development. Several studies have shown that glucose uptake is dependent on several morphological and biochemical placental conditions. Oxidative stress results from the unbalance between reactive oxygen species (ROS) and antioxidants, in favor of the first. During pregnancy, ROS, and therefore oxidative stress, increase, due to increased tissue oxygenation. Moreover, the relation between ROS and some pathological conditions during pregnancy has been well established. For these reasons, it becomes essential to understand if oxidative stress can compromise the uptake of glucose by the placenta. To make this study possible, a trophoblastic cell line, the BeWo cell line, was used. Experiments regarding glucose uptake, either under normal or oxidative stress conditions, were conducted using tert-butylhydroperoxide (tBOOH) as an oxidative stress inducer, and 3H-2-deoxy-D-glucose (3H-DG) as a glucose analogue. Afterwards...

Oxidative stress in Huntington's disease knock-in striatal cells

Ribeiro, Márcio José do Coito
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
66.3%
A doença de Huntington (DH) é uma doença neurodegenerativa progressiva caracterizada por distúrbios motores e psíquicos e declínio cognitivo, afectando o estriado. A DH é umadoença de poliglutaminas causada por uma expansão de CAGs no gene HTT, conduzindo à expressão de huntingtina mutante (Httm). A proteína mutante tem sido associada a vários mecanismos patológicos, incluindo a desregulação da transcrição, disfunção mitocondrial e stresse oxidativo, que poderá resultar da desregulação da função mitocondrial e/ou do défice de antioxidantes. Neste contexto, o tratamento com compostos utilizados em ensaios clínicos da DH apresentaram actividade antioxidante. Por outro lado, o factor de crescimento semelhante à insulina tipo 1 (IGF-1) protegeu as células DH, enquanto a insulina preveniu o stresse oxidativo neuronal. Contudo, o papel da via IGF-1/Akt na DH permanence controverso. O principal objectivo desta tese foi clarificar os mecanismos de (des)regulação redox após expressão da forma completa da Httm. Pretendemos avaliar as alterações de antioxidantes, nomeadamente o sistema redox da glutationa, assim como a eficácia de compostos usados em clínica (creatina e cistamina) com potencial actividade antioxidante...

Effects of oxidative stress on plasma membrane fluidity: biological consequences

de la Haba Fonteboa, Carlos
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2015 Português
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El estrés oxidativo (OS) es característico de muchas enfermedades y se produce cuando hay un desequilibrio entre oxidantes y antioxidantes, lo cual favorece un estado oxidativo que genera especies reactivas de oxígeno y de nitrógeno. Los lípidos de la membrana plasmática son dianas preferentes del OS y ello tiene como consecuencia la peroxidación lipídica. Este proceso modifica propiedades de la membrana tales como su fluidez, característica física muy importante conocida por modular la localización de las proteínas de membrana y las uniones receptor-ligando. Objetivos: 1) Evaluar el efecto del OS en la regionalización de la fluidez en la membrana plasmática de células vivas tales como macrófagos THP-1 y linfocitos MEC-1, de manera individualizada. 2) Analizar, en estas células, la relación entre la peroxidación lipídica y la fluidez de membrana. 3) Estudiar el efecto del OS sobre la unión receptor-ligando y sobre la fluidez de membrana: lipopolisacárido/receptores de tipo Toll (TLR2/4) en macrófagos y progesterone-induced blocking factor (PIBF)/PIBF-receptor en linfocitos. Material y Métodos: Se estandarizó la metodología two-photon microscopy por primera vez en la Universidad Autónoma de Barcelona, para analizar la fluidez de membrana en células vivas individuales. Conjuntamente se ha desarrollado un nuevo software capaz de medir el tamaño y el número de los dominios lipídicos de membrana. El OS se indujo mediante H2O2 y se empleó la sonda fluorescente Laurdan para detectar las diferencias de fluidez en la membrana plasmática. Se utilizaron LPS y PIBF soluble en macrófagos y linfocitos respectivamente...