The purpose of this investigation was to determine how dietary levels of α-tocopherol, γ-tocopherol and iron influence oxidative stress and ras-p21 levels in the colon. Rats were fed diets deficient in tocopherols (-E) or supplemented with either 0.156 mmol of α-tocopherol (AE)/kg diet or 0.156 mmol of γ-tocopherol (GE)/kg of diet. Half the rats in each of these three groups received dietary iron at a level of 35 mg/kg diet and the other half at eight times this level (280 mg/kg diet). Rats fed the AE diets had higher levels of Vitamin E in feces, colonocytes, plasma and liver than did rats fed the GE diets. Dietary iron levels did not influence tocopherol levels in plasma, liver or feces. For colonocytes, high dietary iron decreased tocopherol levels. The ratio of γ-tocopherol (in the GE groups) to α-tocopherol (in the AE groups) was 0.13 for plasma, 0.11 for liver, 0.28 for colonocytes and 0.51 for feces. The plasma ratio is not, therefore, predictive of the ratio in colonocytes and feces. High levels of dietary iron increased levels of fecal lipid hydroperoxides. Moreover, rats fed the GE diets had lower levels of fecal lipid hydroperoxides than rats fed the AE diets. The levels of ras-p21 were significantly lower in rats fed the GE diets compared with rats fed the AE diets. The γ-tocopherol may, therefore, play a significant role in preventing colon cancer. High levels of dietary iron were found to promote oxidative stress in feces and colonocytes.

No description available.

alpha-tocopherol is the most abundant form of vitamin E in human plasma and tissues. Inter-individual differences in plasma alpha-tocopherol concentration or its response to dietary alpha-tocopherol may be due, in part, to polymorphisms in vitamin E metabolism genes (alpha-tocopherol transfer protein (alpha-TTP), tocopherol associated protein (TAP) and CYP4F2). The thesis objectives were to determine whether common polymorphisms in the alpha-TTP (rs6994076 A>T), TAP (rs2072157 C>T and Arg11Lys) and CYP4F2 (Val433Met) genes influence plasma alpha-tocopherol concentration or modify the association between dietary and plasma alpha-tocopherol. Subjects (n=1248), 20 to 29 years from the Toronto Nutrigenomics and Health study completed a food frequency questionnaire. Fasting blood samples were used for genotyping and to measure plasma alpha-tocopherol concentration. The alpha-TTP and TAP Arg11Lys polymorphisms significantly altered plasma alpha-tocopherol. The alpha-TTP polymorphism only influenced plasma alpha-tocopherol in individuals not using supplements. None of the polymorphisms examined modified the plasma alpha-tocopherol response to dietary alpha-tocopherol.

alpha-tocopherol is the most abundant form of vitamin E in human plasma and tissues. Inter-individual differences in plasma alpha-tocopherol concentration or its response to dietary alpha-tocopherol may be due, in part, to polymorphisms in vitamin E metabolism genes (alpha-tocopherol transfer protein (alpha-TTP), tocopherol associated protein (TAP) and CYP4F2). The thesis objectives were to determine whether common polymorphisms in the alpha-TTP (rs6994076 A>T), TAP (rs2072157 C>T and Arg11Lys) and CYP4F2 (Val433Met) genes influence plasma alpha-tocopherol concentration or modify the association between dietary and plasma alpha-tocopherol. Subjects (n=1248), 20 to 29 years from the Toronto Nutrigenomics and Health study completed a food frequency questionnaire. Fasting blood samples were used for genotyping and to measure plasma alpha-tocopherol concentration. The alpha-TTP and TAP Arg11Lys polymorphisms significantly altered plasma alpha-tocopherol. The alpha-TTP polymorphism only influenced plasma alpha-tocopherol in individuals not using supplements. None of the polymorphisms examined modified the plasma alpha-tocopherol response to dietary alpha-tocopherol.

Agentes estressores em piscicultura intensiva afetam a condição fisiológica e o sistema imune dos peixes aumentando a susceptibilidade a infecções e causando prejuízos econômicos. Para contornar este problema, o uso de nutrientes moduladores do sistema imunológico na dieta, como o tocoferol, se tornam estratégia profilática para as pisciculturas assegurarem uma maior sobrevivência e consequente produtividade. O presente estudo visou avaliar a exigência nutricional do dourado, Salminus brasiliensis, por meio de um ensaio dose-resposta e aferir seu efeito imunomodulador. O delineamento utilizado foi o inteiramente casualizado, com sete tratamentos/dietas semi purificadas elaboradas com doses crescentes de vitamina E (0; 50; 100; 150; 200, 250 e 3500 mg kg-1α-tocoferol acetato) (n=4). Quinze juvenis de dourado foram alojados em caixas de polipropileno, em sistema de recirculação fechado com filtragem mecânica e biológica, trocador de calor com termostato e aeração forçada através de sopradores e pedras difusoras. Após serem alimentados por 30 dias com a dieta basal para depleção de vitamina E nas reservas corporais de vitamina, os animais foram pesados (20,04 ± 0,09 g), redistribuídos em 28 tanques (500 L; 15 peixes por tanque) e alimentados durante 78 dias até saciedade aparente (duas refeições diárias: 08h00m e 17h00m). Os peixes apresentaram diferença no ganho de peso, porém não de maneira dependente do tratamento de vitamina E. Após o período de alimentação os peixes foram desafiados com a bactéria Aeromonas hydrophila. Os parâmetros imunológicos foram aferidos antes e após o desafio e não houveram diferenças significativas para: atividade respiratória dos leucócitos, atividade da lisozima sérica, proteína e albumina total no soro e sobrevivência. Houve aumento da concentração das globulinas totais no soro após infecção em função do nível de vitamina E na dieta, e a dose ótima foi definida por meio da regressão segmentada: 151,07 mg kg-1 de vitamina E na ração. A exigência de vitamina E para o dourado foi determinada em 58,90 mg kg-1 pelas substâncias reativas ao ácido tiobarbiturico da fração mitocondrial do fígado por análise de regressão segmentada. / Stressors in intensive fish farming affect fish physiological conditions and immune system, promoting susceptibility to infections and causing economic losses. To overcome this issue, using immunomodulatory nutrients such as tocopherol on fish feeds may become a prophylactic strategy to fish farms to ensure a higher survival and productivity. The present study aimed at determining vitamin E requirement of dourado, Salminus brasiliensis, through a dose dependent trial and how the immune system responded to vitamin E crescent doses. The experiment design was randomly distributed in seven treatments (n=4) of semi purified diets (0; 50; 100; 150; 200; 250 and 3,500 mg kg-1). After exposing the fish during 30 days for tocopherol depletion, fifteen dourado juveniles (20.04 ± 0.09 g) were stocked in 500 L tanks in a closed loop system and fed twice a day until apparent satiation. Differences in weight gain were observed however not in a vitamin E dose dependent way. After feeding for 78 days fish were challenged with intraperitoneal bacterial infection (Aeromonas hydrophila). Immunological parameters were measured before and after infection and no significant differences were observed in: blood leukocyte burst respiratory activity, serum lysozyme activity, serum protein and albumin, and survival. However a higher total serum globulin was detected after infection and the best response determined through a broken-line regression was 151.07 mg kg-1 of vitamin E on fish feed. Dietary requirement of vitamin E was determined by broken-line regression from thiobarbituric reactive substances of liver mithocondrial fraction to be 58.90 mg/kg of α-tocopherol acetate.

Orientador: Neuza Jorge / Banca: Odair Zenebon / Banca: Mieko Kimura / Resumo: O presente trabalho teve como objetivos avaliar, em condições de termoxidação, o compor tamento e a atividade antioxidante do a- tocoferol naturalmente presente em óleo de soja e adicionado em óleo de soja pur ificado, o compor tamento e a atividade antioxidante do extrato de alecr im adicionado em óleo de soja com seus tocoferóis or iginais e pur ificado e, ainda, ver ificar a influência do alecr im na res is tência do a- tocoferol natural ou adicionado em óleo de soja. Para is so foram realizados três ensaios. No pr imeiro deles, o óleo pur ificado com alumina foi acres cido de vár ias concentrações de a- tocoferol ou de extrato de alecr im e, por meio de uma determinação preliminar da atividade antioxidante, as concentrações de 600 mg/kg para o a- tocoferol e de 1.000 mg/kg para o extrato de alecr im foram selecionadas a fim de serem submetidas aos ensaios poster iores. Nos segundo e terceiro ensaios, o óleo pur ificado adicionado das concentrações selecionadas dos antioxidantes citados ou da mistura dos mesmos e o óleo natural adicionado da concentração selecionada de extrato de alecr im foram aquecidos à temperatura de 180ºC por 10 horas. Os resultados obtidos das determinações analíticas foram submetidos às análises de var iância, em esquema fator ial, no delineamento inteiramente casualizado, de modo a determinar a influência dos fatores antioxidantes e tempos de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aims of this work were to evaluate, in thermoxidation conditions, the behavior and antioxidant activity of a tocopherol naturally present in soybean oil and the one added in pur ified soybean oil, the behavior and antioxidant activity of rosemary extract added in soybean oil with its or iginal and pur ified tocopherols and, also, to ver ify rosemary influence on the res is tance of natural a- tocoferol or the one added in soybean oil. In order to do that, three exper iments were car r ied out. In the fir st one, a number of a- tocopherol or rosemary extract concentrations were added to the oil pur ified with alumina and, through a preliminary determination of the antioxidant activity, the concentrations of 600 mg/kg for a- tocoferol and 1.000 mg/kg for rosemary extract were selected in order to be submitted to the fur ther exper iments. In the second and third exper iments, the pur ified oil added with the selected concentrations of the cited antioxidants or the mixture of them and the natural oil added with the selected concentration of rosemary extract were heated until the temperature of 180°C dur ing ten hours. T he results obtained from the analytical determinations were submitted to var iance analys is, in a factor ial s cheme, employing the completely randomized statis tical design, in order to determine the influence of antioxidant factors and per iods of heating... (Complete abstract, click electronic access below) / Mestre

Alfalfa is Generally regarded as one of the world's most valuable cultivated forage crops. Few crops, if any, are equal to it in capacity to produce heavy yields of highly nutritious, palatable feed. A combination of desirable attributes as a forage plant and adaptation to a wide diversity of soil and climatic conditions has led to the use of alfalfa in the world to an extent probably exceeding that of any other single legume or grass. Alfalfa constantly proves itself as a valuable feed for most types of livestock. This is especially true in the states where a large amount of hay is harvested and stored for the wintering of livestock, and where it is dehydrated, ground and incorporated into poultry rations. As better methods are developed for the harvesting, handling and storage of alfalfa so as to retain maximum nutrient value, its importance will constatly increase. The nutrient value of the hay may be influenced by the variety of alfalfa grown as shown by Thompson (1949) and the fertility level of the soil as shown by several authors encluding Barakat (1950), kashemsri (1952) and Jones (1953). Because of alfalfa's growing importance it is desirable to determine the most economical methods of producing maximum yields of hay with high nutritive value.

Alpha-tocopherol, the most abundant form of vitamin E in man, is transported in the circulation by plasma lipoproteins. It plays important roles, not only in preventing lipid peroxidation, but also in modulating several cell functions such as cell signaling and gene expression. While chylomicrons transport dietary alpha-tocopherol after intestinal absorption, LDL and HDL are the major carriers of alpha-tocopherol in fasting plasma and largely contribute to its delivery to cells and tissues. Exchanges of alpha-tocopherol occur between plasma lipoproteins. In addition, alpha-tocopherol transfers have also been observed, in both directions, between plasma lipoproteins and artificial chylomicrons such as intravenous lipid emulsion particles used in parenteral nutrition. In acute conditions, intravenous supply of vitamin E via lipid emulsions, which bypasses the intestinal tract, may offer some advantages over oral administration to rapidly increase alpha-tocopherol plasma concentration. However, many questions remain unanswered regarding kinetics and factors facilitating vitamin E exchanges between lipid emulsions and plasma lipoproteins. The first part of this work aimed at characterizing alpha-tocopherol transfers between alpha-tocopherol rich emulsion particles and plasma lipoproteins as well as the potential for plasma proteins to modulate such transfers. An in vitro model of incubation was used in which emulsion triglyceride concentration was relatively low and lipoprotein levels comparable to those commonly found in the circulation. Results indicate a high capacity for LDL and HDL to acquire extra-amounts of alpha-tocopherol by rapid mass transfers from alpha-tocopherol-rich emulsion particles. Data further shows that, at a fixed alpha-tocopherol concentration provided by emulsion particles, the limiting factor for alpha-tocopherol enrichment is not the capacity of plasma lipoproteins to accommodate extra-amounts of alpha-tocopherol but the facilitating effect of plasma proteins on alpha-tocopherol transfer, the duration of the incubation and possibly the competition between different acceptor particles. Two lipid transfer proteins, PLTP and CETP, appear to largely mediate facilitation of alpha-tocopherol transfer; however, other plasma proteins may be involved. Data further shows that alpha-tocopherol enriched LDL and HDL can readily transfer newly acquired alpha-tocopherol to cells, without any regulation by plasma proteins. Short-term prophylactic vitamin E supplementation has been suggested to be beneficial in some patients in acute conditions who present reduced plasma vitamin E concentrations in association with important changes in plasma lipids and severe oxidative stress. However, it was not clear whether low plasma vitamin E concentration in critically ill patients is related to changes in the composition of plasma lipoproteins or to a decrease in the number of alpha-tocopherol carriers. In the second part of this work, two clinical studies were conducted to analyze changes of lipoprotein concentration and composition in relation to inflammatory reaction and oxidative stress in selected subgroups of critically ill patients, namely patients undergoing cardiac surgery with different procedures. Important changes in LDL and HDL lipid content were observed, some of which contrast with previous observations made in critically ill septic patients. The reduced plasma level of alpha-tocopherol measured after cardiac surgery is entirely due to a reduced number of circulating LDL and HDL particles. Data suggests that such reduced number in alpha-tocopherol carriers post-surgery may impede the delivery of alpha-tocopherol to cells in conditions of increased requirements due to oxidative stress. Avoidance of extracorporeal circulation during cardiac surgery does not reduce inflammation-related changes in plasma lipids but largely prevents oxidative stress. This data on changes occurring in plasma lipoproteins may help to better define strategies against pro-inflammatory changes or oxidative stress. If further studies would confirm a clinical benefit with evidence-based rationale, alpha-tocopherol enriched lipid emulsions may be used to guarantee a sufficient alpha-tocopherol supply in acute conditions associated with fewer alpha-tocopherol transporters and increased requirements due to high risk of oxidative tissue injury.

No description available.

This study aimed to examine potential mechanisms for glucocorticoid (GC)-induced decreases in glucose clearance, and to determine if a reduction in oxidative stress load via dietary pre-treatment with an antioxidant-rich diet has a positive net effect on glucose tolerance following a sub-chronic treatment with the GC analogue dexamethasone (DEX). Rats fed a diet supplemented with 700IU of -tocopherol for two weeks had improved glucose clearance after five days of DEX-treatment relative to unsupplemented rats as well as decreased markers of oxidative stress. Following an intraperitoneal bolus of insulin, phosphorylation of AMP activated protein kinase (AMPK) was preserved in the supplemented groups despite no significant differences in upstream insulin signalling cascade intermediates between DEX-treated groups. This was corroborated by a similar increase (p<0.05) in phosphorylation of the downstream AMPK substrate acetyl CoA carboxylase. This study demonstrated that -tocopherol supplementation can attenuate GC-induced decreases in glucose clearance in an AMPK-dependent manner. / Nutrition and Metabolism