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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

The molecular and mechanical mechanisms of the age-associated increase in the severity of experimental ventilator induced lung injury

Herbert, Joseph Ames 01 January 2016 (has links)
Abstract Background The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and mortality. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Pulmonary edema is a hallmark of VILI and the severity of edema increases with age. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress (ARDS) patients, but has not been investigated in VILI. We hypothesized that age-associated increases in pulmonary edema promote age-related increases in ventilator-associated mortality. Endoplasmic reticulum (ER) stress can disrupt cellular functions and plays a key role in many disease states. The severity of ER stress also increases with age. We hypothesized that age-associated increases in ER stress also increase in the severity of VILI. Finally, serum Vitamin C (VitC) levels also decrease with age. VitC treatments have been shown to decrease mortality rates in murine models of ARDS by and attenuate pulmonary edema. We hypothesize that VitC treatments will attenuate ventilator induced pulmonary edema in our aged murine subjects. Methods Mechanical Ventilation: Young and old mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for with either liberal or conservative fluid support. One group received VitC treatment prior to ventilation. Cell Stretch: Alveolar epithelial cells (ATIIs) from young and old mice were harvested, cultured, and mechanically stretched. Treatment groups received ER stress inhibitor 4-PBA. Results Both advanced age and HVT ventilation significantly increased inflammation, injury, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema decreased mortality rates. VitC treatments significantly decreased pulmonary edema and improved pulmonary mechanics. Mechanical stretch promoted ER Stress and upregulated proinflammatory gene expression and secretion in aged ATIIs. ER stress inhibition attenuated all of these effects. Conclusion Conservative fluid management alone attenuated age-associated increases in ventilator-associated mortality. VitC treatments decreased pulmonary edema and partially restore pulmonary mechanics in old mice ventilated with HVT. ER stress inhibition decreased stretch induced proinflammatory gene expression and protein secretion in aged mechanically stretched ATII cells.
182

Efeitos do ácido ascórbico em biomarcadores de estresse oxidativo em nadadores de alto rendimento de Ribeirão Preto/SP / Effects of ascorbic acid on oxidative stress biomarkers in high-performance swimmers of Ribeirão Preto/SP

Picchi, Monike Garlipp 06 October 2010 (has links)
O exercício físico intenso altera o sistema antioxidante, aumentando a geração de radicais livres e/ou diminuindo a concentração de antioxidantes. Assim o objetivo deste estudo foi verificar os efeitos da oferta de vitamina C através de um suplemento alimentar e dieta rica em ácido ascórbico no estresse oxidativo induzido pelo exercício. A amostra foi composta por 13 nadadores de elite (6 homens e 7 mulheres), com idades entre 18 e 26 anos, IMC médio 21,8kg/m², que treinavam em média 19,4h semanais. Os atletas foram submetidos à carga de exercício aguda em 3 fases, controle (C), dieta rica em vitamina C (D) e suplemento de vitamina C (S), nas quais amostras de sangue foram colhidas antes, imediatamente após e 24 horas depois do exercício, para determinação bioquímica e do estresse oxidativo. O uso de suplementos alimentares foi feito pela maioria dos nadadores (92,3%), e os suplementos mais usados eram Maltodextrina, associação de proteína e carboidrato, enquanto o relato do consumo de antioxidantes não foi muito freqüente (25%). Em relação ao consumo de antioxidantes, os nadadores apresentavam consumo alimentar variável de vitamina C, sendo que muitos deles apenas adequaram o consumo devido à adição feita pelo estudo. O consumo de vitamina E foi inadequado para todos os atletas, já o consumo de selênio, retinol e zinco tiveram uma grande oscilação. Durante as fases o único antioxidante que apresentou flutuações foi o ácido ascórbico, que foi menor na fase C em relação às outras fases. Para a maioria dos indivíduos o consumo de carboidrato e fibras se mostrou insuficiente, e o de lipídeos e calorias adequados, enquanto o consumo de proteínas variou bastante. O uso de dieta rica em vitamina C favoreceu uma menor peroxidação lipídica em nadadores de alto rendimento, já que apresentou menores valores de FOX, e diminuição da peroxidação lipídica após exercício, pela diminuição dos valores de TBARS, enquanto tiveram aumento dos níveis de vitamina C no plasma logo após o exercício. Enquanto o uso de suplemento de vitamina C, que também conteve a peroxidação lipídica após exercício, aumentou o poder antioxidante nos mesmos nadadores, devido maiores níveis do antioxidante GSH. Os quais sem uso de nenhuma adição de vitamina C tiveram um maior dano hepático e tecidual, pois apresentaram maiores níveis de TGO, menores níveis de antioxidantes, devido aos baixos níveis de vitamina C e GSH, e um aumento do ácido úrico, um antioxidante que aumenta em situações onde há grande quantidade de radicais livres presentes. Ainda pode-se verificar que, antes do exercício, quanto mais ácido ascórbico na dieta mais vitamina C, menos TGO e menos ácido úrico no sangue; e ainda logo após o exercício e 24 horas depois quanto mais ácido ascórbico menos TGO e menos ácido úrico séricos. Sendo assim as mudanças observadas com a adição de vitamina C à dieta de nadadores de alto rendimento sugere um importante papel do ácido ascórbico plasmático e da suplementação alimentar na defesa contra o estresse oxidativo induzido pelo exercício / The strenuous exercise alters the antioxidant system by increasing the generation of free radicals and / or decreasing the concentration of antioxidants. Then the aim of this study was to investigate the effects of supply of vitamin C through a dietary supplement and diet rich in ascorbic acid in the exercise-induced oxidative stress. The sample was compound of 13 elite swimmers (6 men and 7 women) aged between 18 and 26 years, average BMI 21.8 kg / m², who trained on average 19.4 hours per week. The athletes were submitted to acute exercise load in three phases: control (C), diet rich in vitamin C (D) and supplement vitamin C (S), in which blood samples were collected before, immediately after and 24 hours after exercise to biochemical determination and oxidative stress. The use of dietary supplements is done by most of the swimmers (92.3%), and supplements most used were maltodextrin, association of protein and carbohydrate, while the report of consumption of antioxidants was not very frequent (25%). Regarding the consumption of antioxidants, the swimmers had dietary vitamin C variable, and many of them just adjusted consumption due to addition made by the study. The consumption of vitamin E was inadequate for all athletes, while the consumption of selenium, retinol and zinc had a great oscillation. During the phases the only antioxidant that showed fluctuations was ascorbic acid, which was lower in phases C when compared to other phases. For most individuals the consumption of carbohydrates and fibers were insufficient, and lipid and calories adequate, while protein intake varied widely. The use of diet rich in vitamin C favored a lower lipid peroxidation in swimmers high performance, then showed lower values of FOX, and decreased lipid peroxidation after exercise by the decrease in TBARS values, while they had increased levels of vitamin C plasma immediately after exercise. While the use of supplement vitamin C, which also contained the lipid peroxidation after exercise, increased the antioxidant power of the same swimmers, due higher levels of the antioxidant GSH. This without use addition of vitamin C had a greater damage liver and tissue, because they showed higher levels of TGO, lower levels of antioxidants, due lower levels of vitamin C and GSH, and increased uric acid, an antioxidant that increases in situations where there are lots amount the free radicals presents. Further can be seen that, before exercise, the more ascorbic acid in vitamin C diet, less TGO and less uric acid in blood, and even after exercise and 24 hours after the more ascorbic acid less serum TGO and uric acid. Thus the observed change with the addition of vitamin C to the diet of high-performance swimmers suggests an important role of ascorbic acid and dietary supplementation in protecting against exercise-induced oxidative stress.
183

Desenvolvimento, caracterização e aplicação de microcápsulas de ácido ascórbico obtidas por spray chilling / Development, characterization and application of ascorbic acid microcapsules obtained by spray chilling

Matos Junior, Fernando Eustáquio de 05 December 2013 (has links)
O aumento da conscientização por parte da população em relação ao impacto da alimentação no estado de saúde tem imposto à indústria de alimentos uma série de novos desafios, entre eles a necessidade de desenvolver alimentos com maior apelo de \"saudabilidade\" e que promovam bem-estar físico e mental. Em função das recentes exigências do consumidor, os compostos bioativos, aqueles capazes de otimizar funções fisiológicas atuando na promoção e prevenção da saúde têm sido alvos de inúmeras pesquisas. Incorporar compostos bioativos em alimentos é um difícil tarefa, pois muitos compostos bioativos são altamente susceptíveis à degradação quando incorporado à matriz alimentícia. Entre esses compostos está o ácido ascórbico, considerado um composto bioativo por ser um potente antioxidante, que além do seu papel no organismo humano, inclusive vitamínico, também exerce função de aditivo alimentar atuando como um antioxidante natural capaz de evitar ou retardar a oxidação de componentes da matriz alimentícia, evitando assim, alterações de cor e/ou odor desagradáveis. Uma alternativa viável e promissora de incorporar ácido ascórbico à matriz alimentícia evitando sua degradação seria o uso da tecnologia de microencapsulação. Das numerosas técnicas de microencapsulação disponíveis, spray chilling, também conhecida como spray congealing ou spray cooling, vem recebendo especial atenção nos últimos anos em função do seu baixo custo e facilidade de execução. Neste sentido, este trabalho objetivou-se estudar a microencapsulação do ácido ascórbico pela técnica de spray chilling e aplicar as micropartículas carregadas em um produto cárneo emulsionado, não apenas para desenvolvimento de um alimento contendo composto funcional, mas também para substituir o antioxidante até então utilizado na indústria de alimentos para o produto cárneo em questão. O estudo foi dividido em 3 etapas, duas delas compreenderam o desenvolvimento e caracterização das micropartículas lipídicas sólidas carregadas com ácido ascórbico e a terceira à aplicação do ácido ascórbico encapsulado em salsicha produzida com carne de frango. A estabilidade do ácido ascórbico microencapsulado foi consideravelmente melhorada em comparação com sua forma livre. A tecnologia de spray chilling revelouse como uma técnica eficaz de microencapsulação para atender o objetivo proposto. A aplicação do ácido ascórbico encapsulado em salsicha foi bem sucedida, foi produzido um alimento com características similares ao convencional, inclusive, com aceitação sensorial favorável. Foi atendido o objetivo de microencapsular o ácido ascórbico e promover sua aplicação em uma matriz alimentícia. Os resultados desse trabalho poderão subsidiar novos estudos com intuito de microencapsular outros compostos bioativos e de aplicar o ácido ascórbico microencapsulado em outras matrizes alimentícias seja com objetivo de desenvolver alimentos funcionais e/ou de substituir aditivos alimentares atualmente utilizados que não oferecem nenhum benefício adicional à saúde do consumidor por um composto que além de atuar como antioxidante na matriz alimentícia, tem função vitamínica e de composto bioativo no organismo favorecendo a manutenção da saúde do consumidor, e assim, atendendo as novas tendências de busca por alimentos mais saudáveis. / The increased awareness on the part of the population in relation to the impact of food on health has imposed the food industry a series of new challenges, among them the need to develop foods with greater appeal of healthfulness and that promote wellbeing. Due to recents demands consumer, the bioactive compounds, those able to optimize physiological functions working in health promotion and disease prevention have been the targets of numerous studies. Incorporate bioactive compounds in foods is a difficult task because many bioactive compounds are highly susceptible to degradation when incorporated into the food matrix. Among these compounds is ascorbic acid, considered as a bioactive compound to be a potent antioxidant in addition to its role in the human body, including vitamin, also exerts a function as a food additive acting as a natural antioxidant can prevent or retard oxidation Component the food matrix, thus avoiding color change and/or unpleasant odor. A viable and promising alternative to incorporating ascorbic acid to the food matrix preventing their degradation would be the use of microencapsulation technology. Of the numerous techniques available microencapsulation, spray chilling, also known as spray congealing or spray cooling, has received special attention in recent years due to their low cost and ease of implementation. Thus, this work aimed to study the microencapsulation of ascorbic acid by spray chilling technique and apply the loaded microparticles in a emulsified meat product, not only for the development of a food containing functional compound, but also to replace the hitherto used antioxidant in the food industry for meat product in question. The study was divided into three stages, two of which comprised the development and characterization of solid lipid microparticles loaded with ascorbic acid and third application of ascorbic acid produced sausage with encapsulated in chicken. The stability of the microencapsulated ascorbic acid has been considerably improved compared to the free form. The spray chilling technology proved to be an effective technique of microencapsulation to meet the objective. The application of ascorbic acid encapsulated in sausage was successful food was produced with characteristics similar to conventional inclusive, with favorable sensory acceptability. Was served the purpose of microencapsulate ascorbic acid and promote its application in a food matrix. The results of this study may support further studies aiming to microencapsulate other bioactive compounds and apply ascorbic acid microencapsulated other food matrix is aiming to develop functional foods and/or replace currently used food additives that offer no additional benefit to health consumer for a compound that in addition to acting as an antioxidant in food matrix has vitamin function and bioactive compound in the body favoring the maintenance of the health of the consumer, and thus, given the new trends search for healthier foods.
184

Desenvolvimento de matrizes poliméricas como veículo de ácido ascórbico: caracterização e avaliação da estabilidade / Development of polymeric matrix as ascorbic acid vehicle: characterization and stability evaluation

Garcia, Vitor Augusto dos Santos 12 February 2016 (has links)
A administração de princípios ativos pela mucosa oral é uma forma eficiente para a distribuição de fármacos e nutrientes, oferecendo diversas vantagens como uma fácil aplicação, evitando o metabolismo de primeira passagem hepática e potencialmente melhorando a biodisponibilidade dessas substâncias. A acerola e o camu-camu apresentam uma alta concentração de vitamina C e são consideradas fontes de diferentes compostos ativos, porém a vitamina C presente nas frutas é facilmente oxidada pelos fatores ambientais, e essas frutas são pouco acessíveis ao consumo populacional. Filmes de desintegração oral (FDO) podem apresentar rápido tempo de desintegração e fácil administração, o que os torna um material interessante para a veiculação de compostos com atividades farmacêuticas ou nutricionais. Assim, este trabalho teve como objetivo o desenvolvimento e caracterização de filmes de desintegração oral à base de amido e gelatina com adição de extrato seco de acerola e camu-camu produzidos por \"spray dryer\" como uma alternativa para a administração de vitamina C. Os FDOs foram produzidos pela técnica de casting, variando-se a proporção de amido e gelatina. Como plastificante foi utilizado o sorbitol (20 g / 100 g de polímero), mantendo-se constante a concentração de polímeros (2 g /100 g de solução filmogênica) e de extrato seco de acerola (4 g /100 g de solução filmogênica) e camu-camu (4 g / 100 g de solução filmogênica). Os extratos secos de acerola e camu-camu foram caracterizados com relação à concentração da vitamina C e da estabilidade desses extratos nessas condições (30 °C, UR 75 % e 40 °C, UR 75%). Os FDOs foram caracterizados em relação a espessura, propriedades mecânicas, ângulo de contato, FT-IR, microscopia electrônica de varredura, concentração de vitamina C, atividade antioxidante, atividade antimicrobiana, estabilidade da vitamina C, tempo de desintegração, estabilidade da atividade de eliminação de radicais de DPPH•, avaliação sensorial. Os extratos secos apresentaram uma boa estabilidade em relação à vitamina C e aos compostos antioxidantes (sequestro do radical DPPH•). Os FDOs sem adição de extrato, independente da formulação, mostraram-se homogêneos, com ausência de partículas insolúveis e alta capacidade de formação de filme. Para os FDOs com maior concentração de amido foi observado reduzido tempo de desintegração e pH próximo ao bucal. Após a adição dos extratos, os FDOs apresentaram redução do tempo de desintegração, boa aceitação sensorial, propriedades antioxidantes e estabilidade pelo sequestro do radical DPPH•. O pH de superfície dos filmes com adição de extrato seco de acerola foi mais próximo ao bucal quando comparado com os filmes com camu-camu. No entanto, os FDOs com acerola apresentaram reduzida estabilidade da vitamina C em relação ao tempo de armazenamento, enquanto que os filmes com camu-camu apresentaram melhor estabilidade. De modo geral, na formulação produzida apenas com amido (100 g de amido / 100 g de polímeros) observou-se uma maior concentração da vitamina C no final da estabilidade realizada à 30 °C e umidade relativa de 75 %, elevada estabilidade dos compostos ativos (DPPH) e alta taxa de uniformidade na distribuição da vitamina C no filme de desintegração oral. Dessa forma, os FDOs podem ser considerados uma boa alternativa para a suplementação de vitamina C. / The administration of active ingredients through the oral mucosa is an efficient way to deliver drugs and nutrients because it offers various advantages such as easy application, avoiding the hepatic metabolism of the first pass and potentially improving the bioavailability these substances. Acerola and camu-camu have high concentration of vitamin C and are considered sources of different active compounds, however the vitamin C present in fruits is easily oxidized by environmental factors, and such fruits are poorly accessible to population consumption. Orally disintegrating films (ODF) can provide rapid disintegration and easy administration, which makes them interesting materials to deliver compounds with pharmaceutical or nutritional properties. This work aimed at the development and characterization of orally disintegrating films based on starch and gelatin with addition of acerola and camu-camu dry extract produced by spray dryer as an alternative to vitamin C administration. ODFs were produced with casting technique by varying the ratio of starch and gelatin. Sorbitol (20 g / 100 g polymer) was used as plasticizer, with constant the concentration of polymer (2 g / 100 g filmogenic solution), and dry extracts of acerola and camu-camu (4 g / 100 g filmogenic solution). Acerola and camu-camu dry extracts were characterized regarding vitamin C concentration and stability (30 °C, RH 75% and 40 °C, RH 75%). ODFs were characterized considering thickness, mechanical properties, contact angle, FT-IR, scanning electron microscopy, vitamin C concentration, antioxidant activity, antimicrobial activity, vitamin C stability, disintegration time, stability of the scavenging activity of DPPH• radical, and sensory evaluation. Dry extracts showed good stability for vitamin C and antioxidant compounds (scavenging activity of DPPH• radical). ODFs without extract addition, regardless of the formulation, were homogeneous, without insoluble particles and with high film formation capacity. Reduced disintegration time and pH similar to oral pH was observed for ODFs with high starch concentration. After the addition of extracts, ODFs presented decreased disintegration time and good sensorial acceptation, antioxidant properties and stability of the scavenging activity of DPPH• radical. Surface pH of films with acerola dry extract was the closest to oral pH when compared with films with camu-camu dry extracts. However, ODFs with acerola dry extract showed reduced stability of vitamin C regarding storage time, whereas films with camu-camu dry extract showed better stability. In general, the formulation produced only with starch (100 g starch / 100 g polymer) presented higher concentration of vitamin C at the end of stability assay performed at 30 °C and 75% relative humidity, as well as high stability of active compounds (DPPH) and high uniformity rate in vitamin C distribution in the orally disintegrating film. Thus, ODFs can be considered a good alternative for the supplementation of vitamin C.
185

Camu cream

Bacuilima Ñañez, Valeria Rocío, Barrientos Del Aguila, Johanna Ibeth, Chacón Acuña, Ruth Esteffany, Valdivia Medina, Giancarlo Guillermo, Latour Culquicondor, Alonso Enrique 02 July 2019 (has links)
Camu Cream es una crema hidratante hecha de una fruta natural del Amazonas. Este producto, que se utiliza como crema facial, se distingue por tener una serie de cualidades. Esta crema también ayuda a las personas a cuidar su piel ya que, provee vitamina C a la rutina facial diaria. En otras palabras. esta crema busca complacer todas las expectativas del consumidor al ofrecer una amplia variedad de beneficios. El público objetivo evaluado para la implementación del producto son aquellas mujeres que se preocupan por su cuidado de la piel y que pertenecen a los niveles socioeconómicos A, B y C, ya que el precio se comercializa. Esta es la estrategia de marketing correcta para tener una mejor llegada a otros lugares. La fuente inicial de financiamiento se basará en un modelo de capital propio de los accionistas de la compañía, inicialmente es muy poco probable que obtenga financiamiento externo, por lo que se decide optar por el modelo mencionado. Además de aplicar todas las herramientas aprendidas a lo largo de la carrera universitaria para poder evaluar la rentabilidad y la viabilidad del proyecto. / Camu Cream is a moisturizer made from a natural fruit from the Amazon. This product, which is used as a facial cream, is distinguished by having a series of qualities. It can also help people to take care of their skin by providing vitamin C to their daily facial routine. In other words, this cream seeks to meet all consumer expectations by ofering a wide variety of benefits. The target audience evaluated for product implementation are those women who care about their skin care and who belong to socioeconomic levels A, B and C, since the price is marketed. This is the correct marketing strategy to have a better arrival to other places. The initial source of financing will be based on a model of own capital by the shareholders of the company, initially it is very unlikely to obtain external financing, so that it is decided to opt for the aforementioned model. In addition to apply all the tools learned throughout the university career to be able to evaluate the profitability and viability of the project. / Trabajo de investigación
186

Pharmacological ascorbate enhances oxygen consumption and epigenetic reprogramming in pancreatic cancer

Gibson, Adrienne Rae 01 August 2018 (has links)
Pharmacological ascorbate treatment (P-AscH-, high-dose, intravenous vitamin C) results in a short-term increased flux of H2O2 that is preferentially cytotoxic to cancer cells vs. normal cells. We hypothesized that there may be a sustained effect (> 24 h) of P-AscH- that may contribute to cytotoxicity. P-AscH- significantly increased sustained oxygen consumption (OCR), DCFH-DA oxidation, and extracellular acidification (ECAR) in tumor lines with no change in non-tumorigenic cells. One possible source of this sustained ROS and OCR, the NADPH oxidase family of enzymes Dual Oxidase 1 and 2 (DUOX), which are epigenetically silenced by methylation in vitro and in vivo in PDAC, are up-regulated with P-AscH- treatment. Catalase pretreatment reversed the P-AscH--induced increases in DUOX, while DUOX inhibition partially rescues P-AscH- toxicity. Additionally, nutritional ascorbate is unable to mediate the increase in DUOX expression. Together these results suggest that P-AscH--induced toxicity may be enhanced by late metabolic and epigenetic shifts in tumor cells resulting in a feed-forward mechanism of H2O2 generation and induction of metabolic stress via enhanced DUOX expression and OCR. These data highlight a novel epigenetic mechanism of action for P-AscH-.
187

The effect of pharmaceutical excipients on the release of indomethacin from chitosan beads / Riana Havinga

Havinga, Riana January 2006 (has links)
Contents: Chitosan -- Controlled drug delivery -- Indomethacin -- Inotropic gelation -- Tripolyphosphate (TPP) -- Explotab® -- Ac-Di-Sol® -- Vitamin C / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
188

Airway antioxidant responses to oxidative air pollution and vitamin supplementation

Behndig, Annelie January 2006 (has links)
Air pollutants, such as ozone (O3) and diesel exhaust particles, elicit oxidative stress in the lung. Antioxidants within the respiratory tract lining fluid (RTLF) protect the underlying tissue from oxidative injury. Supplementation with vitamins has been shown to modulate the acute ozone-induced effects, but the mechanisms behind this have not been fully clarified. The aim of this thesis was to investigate the airway responses to diesel exhaust and ozone exposure in healthy humans, with the emphasis on inflammatory and antioxidant responses. Furthermore, to study whether oral supplementation with vitamin C could increase ascorbate concentration in the RTLF and whether vitamin supplementation could modulate the negative effects induced by ozone exposure. Diesel exhaust (100 µg/m3 PM10 for 2h), evaluated 18 hours post exposure (PE), induced a neutrophilic airway inflammation and an increase in bronchoalveolar (BAL) urate and reduced glutathione. During O3 exposure (0.2 ppm for 2h), significant losses of nasal RTLF urate and ascorbate concentrations were observed. Six hours PE, a neutrophilic inflammation was evident in the bronchial wash (BW), together with enhanced concentrations of urate and total glutathione. In the bronchoalveolar lavage (BAL), where vitamin C, urate and glutathione concentrations were augmented, no inflammatory response was seen. In alveolar lavage leukocytes, there was a significant loss of glutathione and cysteine, whereas an increase in ascorbate was found in bronchial tissue samples. Following supplementation with increasing doses of vitamin C (60-1,000 mg/day, for 14 days), evaluated 24 hours after the last dose, ascorbate concentrations were unchanged in the nasal RTLF, despite elevated concentrations in plasma and urine. In contrast, following a single dose of 1g of vitamin C, vitamin C concentrations increased significantly in both plasma and nasal lavage two hours post supplementation, before returning to baseline levels at 24 hours. Notably, dehydroascorbate (DHA) accounted for the largest part of RTLF vitamin C and a number of control experiments were performed to ensure the authenticity of this finding. Healthy O3 responders were exposed to O3 (0.2 ppm for 2 h) and air, following seven days of supplementation with vitamin C and E or placebo. No protective effect on lung function or airway inflammation was observed following supplementation. BW and BAL-DHA were enhanced after O3, with further increases following supplementation. In conclusion, oxidative air pollutants induce airway inflammation, as well as a broad spectrum of antioxidant adaptations, which could ultimately limit the airway inflammatory responses. Oral vitamin supplementation was shown to augment RTLF-vitamin C concentrations, but it did not provide protection from the ozone-induced airway responses following a single insult of ozone. The finding of high concentrations of DHA in the RTLF could indicate that DHA represents an important transport form of vitamin C onto the surface of the lung.
189

Screening for resistance to cucurbit yellow stunting disorder virus, gummy stem blight, and monosporascus root rot and detection of RAPD markers associated with QLT for soluble solids, sugars, and vitamin C in melon (Cucumis melo l.)

Sinclair, Jonathan Walker 17 February 2005 (has links)
Cucurbit yellow stunting disorder virus (CYSDV) is a relatively new virus affecting cantaloupe production in South Texas and worldwide. No resistant commercial cultivars are available. A cross of ‘Dulce’ (susceptible) x ‘TGR1551’ (resistant) was made and populations were developed for screening. Although no complete resistance was recovered, ‘TGR1551’ showed some tolerance and may be useful in breeding efforts. Sugar components such as sucrose, fructose, glucose, and total soluble solids are major factors in determining mature melon fruit sweetness, and Vitamin C is important for human health. A F2 population was developed from the melon cross ‘Dulce’ (high values) x ‘TGR1551’ (low values) and bulked segregant analysis was used to detect random amplified polymorphic DNA (RAPD) markers associated with quantitative trait loci (QTL) for each trait. Out of 500 primers, fifteen RAPD markers were found to be significantly associated with fruit quality QTL. These markers could be useful in a marker assisted selection program to transfer these genes into a low quality cultivar or breeding line to enhance fruit quality. Gummy stem blight (Didymella brioniae) affects melon production in South Texas as well as other melon production areas in the U.S. A cross between ‘TMS’ (susceptible) and PI 140471 (resistant) was made and a F2 population was screened with a strain of the disease from South Texas. F2 plants exhibited symptoms ranging from resistant to susceptible. PI 140471 may be useful in developing commercial varieties of melon resistant to the disease in Texas. Monosporascus root rot and vine decline (Monosporascus cannonballus) affects melon production in South Texas as well as other melon production areas in the US. A cross was made between ‘TGR1551’ (moderately resistant) and ‘Deltex’ (resistant) to develop a F2 population. Both parents and the F2 were planted in infested soil. Once symptoms appeared, plant roots were removed from the soil and rated. ‘TGR1551’ showed greater resistance than ‘Deltex’ and should be utilized in breeding to develop improved resistant cultivars.
190

Mega-doses of L-ascorbic acid alter the antineoplastic effects of ionizing radiation in EMT6 cells in vitro

Lund, Karina Ann 15 November 2006 (has links)
Despite the common usage of high-dose vitamin C among breast cancer patients, the published medical literature is not in agreement as to how mega-dose vitamin C may interact with conventional therapy to affect clinical outcomes. The purpose of this study was to investigate the interaction of mega-dose vitamin C with radiation therapy and with doxorubicin in the treatment of breast cancer. Cultures of EMT6 mouse mammary tumor cells were treated concurrently with varying dose of vitamin C and either radiation or doxorubicin. A clonogenic assay was then performed to determine the surviving fraction of the cells. The surviving fractions of cells in cultures receiving different doses of vitamin C were compared among themselves as well as with controls and dose response curves were generated. Results show that ascorbic acid administered in concentrations of 1 mM or 10 mM 4 hours before x-irradiation protected the cells from radiation-induced cytotoxicity. The dose-modifying factors for 1 mM and 10 mM ascorbic acid as compared to controls were 1.23 and 1.37 respectively. These results support the hypothesis that mega dose vitamin C, when taken concurrently with radiation therapy, protects cancer cells from the cytotoxic effects of ionizing radiation. No evidence was found to suggest that mega-dose vitamin C alters the antineoplastic effects of doxorubicin.

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