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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.
1

Surface-Enhanced Raman Spectroscopy of Thiobarbituric Acid (TBA) and TBA Reactive Compounds

Haputhanthri, Pravindya Rukshani 09 December 2011 (has links)
Malondialdehyde (MDA) is the commonly accepted biomarker of lipid peroxidation. We reported the surface-enhanced Raman (SERS) detection of MDA using Thiobarbituric acid (TBA) as a molecular probe. The lowest concentration of HPLC purified TBA-MDA adduct that can be determined with reasonable signal to noise ratio is 0.45 nM. The specificity of the SERS technique has been demonstrated by comparing the SERS spectrum of TBA-MDA adduct with other TBA-aldehyde adducts. As a small organosulfur compound, TBA exhibits tremendous structural complexity. Discussed in this thesis is the drastic pH and concentration dependence of TBA SERS spectral features. To understand the origins of the TBA SERS spectral variations, UV-Vis spectra of TBA were also acquired under same experimental conditions of SERS. Density function calculations (DFT) were performed for different TBA tautomers with different charge states to facilitate the SERS spectral interpretation, allowing us to speculate the type of tautomers dominating the nanoparticle surfaces.
2

Comparison of Color and Thiobarbituric Acid (TBA) Values of Cooked Hamburger Patties and Top Sirloin Steaks after Storage of Fresh Beef Chubs and Raw Steaks in Modified Atmospheres of 80% Oxygen or 0.4% Carbon Monoxide

John, Liza 01 May 2004 (has links)
This study compared the effect of packaging method (0.4% carbon monoxide, 80% oxygen or vacuum), storage time (7, 14 and 21 days) and internal cooking temperature 49, 57, 66, 71 and 79°C) on color and thiobarbituric acid (TBA) values of top sirloin steaks and ground beef patties. Ground beef was obtained from 3 different sources (chuck, loin and trim). All samples were stored at 2°C for 7, 14 and 21 days. All raw ground beef samples stored in 0.4% carbon monoxide remained bright red throughout the 21-day storage period. The phenomenon of premature browning (appearance of cooked color at lower than normal cooking temperatures) was observed in samples stored in high oxygen. TBA values were highest for the samples stored in 80% oxygen. Internal a* redness values were lowest for samples stored in 80% oxygen. Percent myogobin denaturation (PMD) increased with increase in internal cooking temperature and was highest for the ground beef samples stored in 80% oxygen. The a* redness values were highest for raw steaks stored in 0.4% CO. Steaks stored in vacuum had a uniform purple color, but some browning was noticed on the surface of the samples by day 14. PMD and TBA values of cooked top sirloin steaks were highest for the samples stored in 80% oxygen This study confirms that high oxygen packaging promotes rancidity in ground beef and top sirloin steaks. Packaging in 0.4% carbon monoxide helps maintain a bright cherry red color in ground beef and top sirloin steaks for up to 21 days.
3

Comparative Effects of Sodium Levulinate and Sodium Lactate on Microbial Growth, Color, and Thiobarbituric Acid (TBA) Values of Fresh Pork and Turkey Sausages During Storage

Vasavada, Mihir N. 01 May 2004 (has links)
This study compared the effects of 1.4 or 2.7% sodium levulinate or sodium lactate on aerobic plate count (APC), color, pH, and TBA value of fresh pork and turkey sausage. Both sodium lactate and Jevulinate inhibited growth of aerobic microorganisms during storage, compared to controls. Bacteriostatic effects of sodium lactate were dose dependent, wherein 2.7% lactate was significantly more antimicrobial than 1.4% lactate. This was not the case for sodium levulinate, where 1.4% sodium levulinate was as inhibitory to microbial growth as 2.7% sodium levulinate. Additionally, 1.4% sodium levulinate was as inhibitory to microbial growth as the higher level (2.7%) of sodium lactate. TBA values, color, and pH were not affected by treatment with sodium lactate or levulinate. In conclusion, sodium levulinate may have potential as an antimicrobial agent in fresh sausages if it can be obtained at a reasonable cost on a commercial basis.
4

Fats and Iron in the Rat Colon: Effects on Lipid Peroxidation

Chin, Ji Jenny 01 May 1996 (has links)
Preliminary studies were undertaken to investigate whether or not added iron (0, 35, 880 ppm of iron as ferrous fumarate) and fat type (corn oil, beef tallow, or menhaden oil ) influenced the oxidation of the rat diet during storage . Iron level affected thiobarbituric acid (TBA) values only in the menhaden oil diets. Storage for 4 d did not affect TBA values of the diets . Neither food intake nor body weight of the rats was affected by the different diets, suggesting all diets were equally acceptable to rats. The effects of iron supplementation and fat type on in vivo lipid peroxidation in rat colon were studied. Semi-synthetic diets were formulated to contain 15% (wt/wt) total fat, an amount comparable with human diets, as either 15% corn oil (C), 1% corn oil + 14% beef tallow (B), or 1% corn oil + 14% menhaden oil (M). Diets of each fat type were formuIated with ferrous fumarate to contain 35 ppm iron, a level sufficient to meet the requirement of the rats, or 880 ppm iron, a level similar to that found in iron-fortified breakfast cereals. During a 6-wk study, each of 6 groups of 10 male weanling Sprague-Dawley rats was fed one of the 6 diets (C35, C880, B35, B880, M35, M880). Lipid peroxidation products in the colon mucosa and in the feces were measured as thiobarbituric acid reactive substances (TBARS), and other possible physiological changes were monitored by measuring body weight, and iron levels of the feces and colon mucosa, and by observing the histology of the colon. At the beginning of the trial, each group of rats had similar body weights and TBARS in the feces. After the feeding trial, groups of rats remained similar in body weight, and no histological changes were observed in the colon. However, rats fed the different dietary fats had different (p < 0.05) TBARS in the feces and colon mucosa (BThus, the type of dietary fat was a significant determinant of in vivo lipid peroxidation, independent of dietary iron level. Rats fed the high iron diets had higher TBARS in both the feces and colon mucosa. When compared by dietary fat type, rats fed high iron diets had higher TBARS in the mucosa only if they were also fed the menhaden oil diet. Thus, dietarv iron was a significant determinant of in vivo lipid peroxidation only in combination with menhaden oil. The long-term intake of iron-fortified foods with high menhaden oil may lead to significant increased in vivo lipid peroxidation.
5

Kokta äggs hållbarhet i rumstemperatur. : Studie av lipidoxidation och mikrobiell förekomst. / Shelf life of boiled eggs at room temperature. : Study of lipid oxidation and microbial occurrence.

Carlegård, Cecilia January 2023 (has links)
Eggs are a popular food widely consumed worldwide, due to their nutrient density and shelf life even at room temperature. This study aimed to investigate if eggs keep better in the refrigerator than at room temperature post-boiling. The shelf life of boiled eggs stored at room temperature and refrigerated was analyzed regarding lipid oxidation and microbiological growth. Lipid oxidation was determined by measuring thiobarbituric acid reaction substances (TBARS) at 532 nm, formed as the oxidation product malondialdehyde and thiobarbituric acid (TBA). Microbiological presence and growth were analyzed on egg yolk and egg white determining total counts of aerobic microorganisms on agar incubated for three days at room temperature. No difference in counts of aerobic microorganisms between boiled eggs stored at room temperature or in the refrigerator was detected for either lipid oxidation or microbiological growth. After 14 days, a difference in lipid oxidation was noted as compared to 7 days. The study found that boiled eggs have a long shelf life and can be stored at room temperature for 7 days. / Ägg är ett omtyckt livsmedel som konsumeras flitigt i hela världen, och det är inte förvånande på grund av dess näringstäthet samt dess hållbarhet, även i rumstemperatur. Syftet med denna studie var att undersöka hur bra ägg håller i rumstemperatur efter kokning jämfört med i kylskåp. Hållbarheten på kokta ägg förvarade i rumstemperatur och kyl har analyserades med avseende på lipidoxidation och mikrobiologisk tillväxt. Lipidoxidation bestämdes genom att mäta thiobarbituric acid reactive substances (TBARS), vid 532nm, som bildas genom att oxidationsprodukten malondialdehyd reagerar med thiobarbituric acid (TBA). Mikrobiell förekomst och tillväxt i äggulan och äggvitan bestämdes på plate count agar efter inkubation i tre dagar i rumstemperatur. Ingen skillnad mellan kokta ägg förvarade i rumstemperatur eller kyl observerades för vare sig lipidoxidation eller mikrobiologisk tillväxt. Efter 14 dagar noterades en skillnad avseende lipidoxidationen i äggula jämfört med 7 dagar. Studien visade att kokta ägg har en lång hållbarhet och kan förvaras i rumstemperatur i upp till 7 dagar.
6

Estresse oxidativo e lipoperoxidação devido à anemia induzida por perda aguda de sangue em ovinos

Fonteque, Joandes Henrique [UNESP] January 2005 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2005Bitstream added on 2014-06-13T19:20:19Z : No. of bitstreams: 1 fonteque_jh_dr_botfmvz.pdf: 314172 bytes, checksum: a0386e439bd656f3236dc3ec523e7bea (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A produção de espécies reativas de oxigênio (ERO) é um evento presente em todas as células do organismo e pode estar aumentada em condições como hipóxia induzida pela anemia causando lesões em moléculas como DNA, lipídeos e proteínas. Com o objetivo de avaliar o estresse oxidativo na anemia induzida por perda aguda de sangue, foram utilizados 10 ovinos, mestiços da raça Texel, machos e fêmeas, com idade entre seis e oito meses, clinicamente sadios, mantidos em regime de confinamento. Os animais foram submetidos a duas flebotomias para a retirada de 30% e 20% do volume sangüíneo com intervalo de 12 horas. Amostras de sangue foram colhidas imediatamente antes da flebotomia, 6h e 12h após a primeira flebotomia, 6h, 12h, 24h, 48h, 72 horas, 4d, 5d, 6d, 10d, 14d, 21d e 28 dias após a segunda flebotomia. Foram avaliados o óxido nítrico, substâncias reativas ao ácido tiobarbitúrico, malondialdeído, cortisol e lactato séricos, hemograma e bioquímica sérica. A análise estatística dos dados foi realizada por meio do Teste de Análise de Variância de Medidas Repetidas (ANOVA) ao nível de 5% de significância. Os resultados demonstraram que o protocolo de indução de anemia foi capaz de induzir anemia 12 horas após a segunda flebotomia, estresse oxidativo e lipoperoxidação caracterizado pelo aumento das substâncias reativas ao ácido tiobarbitúrico. O cortisol elevou-se e alterou o leucograma aumentando o número de leucócitos, neutrófilos e a relação neutrófilo:linfócito. Todos os animais recuperaram-se dentro do período de 28 dias após a flebotomia. Conclui-se que a retirada de 30% e 20% do volume de sangue com intervalo de 12 horas provoca estresse oxidativo e lipoperoxidação em ovinos. / Reactive oxygen species (ROS) are produced in all cells and an increase can be associated with hypoxia induced by anemia. This results in DNA, lipid and protein damage. The aim of this work was to evaluate the oxidative stress induced by experimental acute blood loss. Ten healthy cross Texel sheep underwent two phlebotomies with 12 hours interval. Blood samples were collected before the first phlebotomy (30% of blood volume) and 6 and 12 hours after. A second phlebotomy was performed 12 hours after the first one (20% of blood volume) and blood samples were collected, 6h, 12h, 24h, 48h, 72h, 4 days, 5 days, 6 days, 10 days, 14 days, 21 days and 28 days after. Thiobarbituric acid-reactive substances, malondialdehyde, nitric oxide, lipid peroxidation, serum cortisol, serum lactate, CBC and serum biochemistry were evaluated. Statistical analysis was reformed using repeated measures ANOVA. The experimental protocol used was able to induce anemia 12 hours after the second phlebotomy resulting in oxidative stress and lipoperoxiation characterized by the thiobarbituric acid-reactive substances increase. There was also a cortisol increase causing white blood cell changes: increased number of leukocytes, neutrophils and neutrophil and lymphocyte rate. All animals were normal 28 days after the phlebotomy. In conclusion, the protocol used showed that phlebotomy causing 30 and 20% at blood loss can induce oxidative stress and, lipid peroxidation in sheep.
7

Estresse oxidativo e lipoperoxidação devido à anemia induzida por perda aguda de sangue em ovinos /

Fonteque, Joandes Henrique. January 2005 (has links)
Orientador: Aguemi Kohayagawa. / Resumo: A produção de espécies reativas de oxigênio (ERO) é um evento presente em todas as células do organismo e pode estar aumentada em condições como hipóxia induzida pela anemia causando lesões em moléculas como DNA, lipídeos e proteínas. Com o objetivo de avaliar o estresse oxidativo na anemia induzida por perda aguda de sangue, foram utilizados 10 ovinos, mestiços da raça Texel, machos e fêmeas, com idade entre seis e oito meses, clinicamente sadios, mantidos em regime de confinamento. Os animais foram submetidos a duas flebotomias para a retirada de 30% e 20% do volume sangüíneo com intervalo de 12 horas. Amostras de sangue foram colhidas imediatamente antes da flebotomia, 6h e 12h após a primeira flebotomia, 6h, 12h, 24h, 48h, 72 horas, 4d, 5d, 6d, 10d, 14d, 21d e 28 dias após a segunda flebotomia. Foram avaliados o óxido nítrico, substâncias reativas ao ácido tiobarbitúrico, malondialdeído, cortisol e lactato séricos, hemograma e bioquímica sérica. A análise estatística dos dados foi realizada por meio do Teste de Análise de Variância de Medidas Repetidas (ANOVA) ao nível de 5% de significância. Os resultados demonstraram que o protocolo de indução de anemia foi capaz de induzir anemia 12 horas após a segunda flebotomia, estresse oxidativo e lipoperoxidação caracterizado pelo aumento das substâncias reativas ao ácido tiobarbitúrico. O cortisol elevou-se e alterou o leucograma aumentando o número de leucócitos, neutrófilos e a relação neutrófilo:linfócito. Todos os animais recuperaram-se dentro do período de 28 dias após a flebotomia. Conclui-se que a retirada de 30% e 20% do volume de sangue com intervalo de 12 horas provoca estresse oxidativo e lipoperoxidação em ovinos. / Abstract: Reactive oxygen species (ROS) are produced in all cells and an increase can be associated with hypoxia induced by anemia. This results in DNA, lipid and protein damage. The aim of this work was to evaluate the oxidative stress induced by experimental acute blood loss. Ten healthy cross Texel sheep underwent two phlebotomies with 12 hours interval. Blood samples were collected before the first phlebotomy (30% of blood volume) and 6 and 12 hours after. A second phlebotomy was performed 12 hours after the first one (20% of blood volume) and blood samples were collected, 6h, 12h, 24h, 48h, 72h, 4 days, 5 days, 6 days, 10 days, 14 days, 21 days and 28 days after. Thiobarbituric acid-reactive substances, malondialdehyde, nitric oxide, lipid peroxidation, serum cortisol, serum lactate, CBC and serum biochemistry were evaluated. Statistical analysis was reformed using repeated measures ANOVA. The experimental protocol used was able to induce anemia 12 hours after the second phlebotomy resulting in oxidative stress and lipoperoxiation characterized by the thiobarbituric acid-reactive substances increase. There was also a cortisol increase causing white blood cell changes: increased number of leukocytes, neutrophils and neutrophil and lymphocyte rate. All animals were normal 28 days after the phlebotomy. In conclusion, the protocol used showed that phlebotomy causing 30 and 20% at blood loss can induce oxidative stress and, lipid peroxidation in sheep. / Doutor
8

Efeitos da quercetina na atividade da cetilcolinesterase, na peroxidação lipídica e nos testes comportamentais em ratos diabéticos induzidos por estreptozotocina / Effects of activity in quercetin acetylcholinesterase, in lipid peroxidation and behaviour in tests in rats streptozotocin-induced diabetic

Maciel, Roberto Marinho 28 February 2013 (has links)
Diabetes mellitus (DM) refers to a group of common metabolic disorders that share the phenotype of hyperglycemia, is a chronic condition that arises when the pancreas does not produce enough insulin or when the body can not effectively use the insulin produced.The condition of chronic hyperglycemia promotes an imbalance between the production of free radicals and endogenous antioxidant defense, causing oxidative stress and finally lipid peroxidation, structures and cell membranes rich in lipids. Quercetin (QUE) is a flavonoid that has antioxidant and anti-inflammatory properties and is therefore investigated as a possible adjuvant in the treatment of diabetes. In this study we analyzed the actions of excess free radicals, promoted by type 1 diabetes mellitus (DM T1) at both systemic and mainly in the cholinergic system. Moreover, the possible effects of antioxidant protection and anti-inflammatory of QUE were analysed. We used 130 male Wistar rats, weighing 160 to 250 g and divided into 2 groups: non-diabetic and diabetic, which are divided into 5 treatments: 0.9% saline, 25% ethanol and QUE (5, 25 and 50 mg/kg).The induction of DM T1 occurred with a single intraperitoneal injection of 70 mg/kg streptozotocin (STZ). Fifteen days later, the treatment with QUE for 40 days started. At the end of the experiment behavioral tests and collection of biological material (blood and tissues) were performed. The untreated diabetic group compared to non-diabetic control showed: reduction of the islets and beta-cell population, weight loss, chronic hyperglycemia, leukopenia associated with neutropenia, decreased insulin and albumin, increase in fructosamine, triglycerides, urea, alkaline phosphatase (ALP), alanine aminotransferase (ALT), in addition to protein fractions of beta and gamma globulin.The increase of thiobarbituric acid reactive substances (TBARS) levels was accompanied by a reduction in the concentration of hepatic superoxide dismutase. Failed aversive memory formation and anxious behavior were observed in these animals, as well as increase in the activity of acetylcholinesterase (AChE) in brain structures and sites (cortex, hippocampus, striatum and synaptosomes) and TBARS (cortex, hippocampus and striatum). Diabetic rats treated with QUE in relation to diabetic control had increased albumin (50 mg/kg), reduction in betaglobulins (25 and 50 mg/kg) and gamma globulins (50 mg/kg), decreased triglycerides (5, 25 and 50 mg/kg). Quercetin reverted the aversive memory failure and showed anxiolytic properties. AChE activity were decreased in the cortex (50 mg/kg), hippocampus (5 and 50 mg/kg) and synaptosomes (50 mg/kg). Levels of TBARS were reduced in the cortex, hippocampus and striatum (5, 25 and 50 mg/kg). Quercetin increased the concentration of insulin in non-diabetic and diabetic groups (5, 25 and 50 mg/kg). When administered in non-diabetic animals, QUE increased the uneasiness of the animals (50 mg/kg) increased AChE activity in the hippocampus (5, 25 and 50 mg/kg), striatum (5 mg/kg) and synaptosomes (25 mg/kg), lowering in the cortex (5 mg/kg), furthermore, increased the level of TBARS in the cortex (25 mg/kg).From these results we conclude that QUE have antioxidant and anti-inflammatory properties which may be used in conjunction with treatment of diabetes. However, it also had undesirable properties, such as pro-oxidant effect and induces insulin resistance. / Diabetes melito (DM) refere-se a um grupo de distúrbios metabólicos comuns que compartilham o fenótipo da hiperglicemia, sendo uma condição crônica que surge quando o pâncreas não produz insulina em quantidade suficiente ou quando o organismo não consegue utilizar de modo eficaz a insulina produzida. A condição de hiperglicemia crônica favorece o desequilíbrio entre a produção de radicais livres e a defesa antioxidante endógena, gerando o estresse oxidativo e por fim a peroxidação lipídica de estruturas e membranas celulares, ricas em lipídios. A quercetina (QUE) é um flavonoide que apresenta propriedades antioxidantes e anti-inflamatórias, sendo por isso, investigada como possível adjuvante no tratamento do DM. No presente trabalho foram analisadas as ações do excesso de radicais livres, promovido pelo diabetes melito tipo 1 (DM T1) tanto em nível sistêmico como, principalmente, no sistema colinérgico. Além disso, os possíveis efeitos de proteção antioxidante e anti-inflamatória da QUE. Foram utilizados 130 ratos Wistar, machos, pesando entre 160 a 250 g, distribuidos em 2 grupos: não diabéticos e diabéticos, sendo cada um deles divididos em 5 tratamentos: salina 0,9%, etanol 25% e QUE (5, 25 e 50 mg/Kg). A indução do DM T1 se deu com uma única injeção intraperitoneal de 70 mg/Kg de estreptozotocina (STZ). Quinze dias depois, teve início o tratamento com QUE por 40 dias. Ao término do experimento, foram realizados os testes comportamentais e a coleta de material biológico (sangue e tecidos corporais). O grupo diabético sem tratamento em relação ao controle não diabético apresentou: redução das ilhotas de Langerhans e da população de células beta, perda de peso, hiperglicemia crônica, leucopenia associada à neutropenia, redução na insulina e albumina, elevação na frutosamina, triglicerídeos, ureia, fosfatase alcalina (FA), alanina aminotransferase (ALT), além das frações proteicas de beta e gamaglobulinas. Houve aumento das substâncias reativas ao ácido tiobarbitúrico (TBARS) sérico e redução na atividade de superóxido dismutase hepática. Falha na formação de memória aversiva e comportamento ansioso foram observados nesses animais, bem como, elevação na atividade da acetilcolinesterase (AChE) nas estruturas e sítios cerebrais (córtex, hipocampo, estriado e sinaptossomas) e TBARS (córtex, hipocampo e estriado). Os ratos diabéticos tratados com QUE em relação ao grupo controle diabético: apresentaram elevação na albumina (50 mg/Kg), redução nas betaglobulinas (25 e 50 mg/Kg) e gamaglobulinas (50 mg/Kg), diminuição dos triglicerídeos (5, 25 e 50 mg/Kg). A quercetina nas concentrações utilizadas reverteu a falha de memória aversiva e apresentou propriedades ansiolíticas. A atividade da AChE foi reduzida: no córtex (50 mg/Kg), no hipocampo (5 e 50 mg/Kg) e sinaptossomas (50 mg/Kg). Houve diminuição nos níveis séricos das TBARS no córtex, hipocampo e estriado (5, 25 e 50 mg/Kg). A quercetina elevou a concentração da insulina, nos grupos não diabéticos e diabéticos (5, 25 e 50 mg/Kg). Quando administrada em animais não diabéticos a QUE aumentou a inquietação dos animais (50 mg/Kg); aumentou a atividade da AChE no hipocampo (5, 25 e 50 mg/Kg), estriado (5 mg/Kg) e sinaptossomas (25 mg/Kg), diminuindo no córtex (5 mg/Kg). Além disso, aumentou o nível de TBARS no córtex (25 mg/Kg). A partir desses resultados conclui-se que a QUE possui propriedades antioxidantes e anti-inflamatórias que podem ser utilizadas no tratamento auxiliar do DM. Contudo, também apresentou propriedades não desejáveis, como efeito pró-oxidante, o que sugere a resistência à insulina.
9

Triple A Syndrome: Preliminary Response to the Antioxidant N-Acetylcysteine Treatment in a Child

Barisson Villares Fragoso, Maria Candida, Vasco de Albuquerque Albuquerque, Edoarda, de Almeida Cardoso, Ana Luiza, Lopes da Rosa, Paula Waki, Bomeny de Paulo, Rodrigo, Massola Schimizu, Maria Heloisa, Seguro, Antonio Carlos, Passarelli, Marisa, Köhler, Katrin, Hübner, Angela, Almeida, Madson Q., Latronico, Ana Claudia, Prado Arnhold, Ivo Jorge, Bilharinho Mendonca, Berenice 22 May 2020 (has links)
Introduction: Triple A syndrome (AAAS) is a rare autosomal recessive disorder characterized by alacrima, achalasia, ACTH-resistant adrenal insufficiency, autonomic dysfunction, and progressive neurodegeneration. Increased oxidative stress, demonstrated in patients’ fibroblasts in vitro, may be a central disease mechanism. N-acetylcysteine protects renal function in patients with kidney injuries associated with increased oxidative stress and improves viability of AAAS-knockdown adrenal cells in vitro. Patient and Results: A boy diagnosed with AAAS presented with short stature and increased oxidative stress in vivo assessed by increased thiobarbituric acid reactive substances (TBARS), which are markers of lipid peroxidation, and by the susceptibility of LDL to oxidation and the capacity of HDL to prevent it. A homozygous missense germline mutation (c.523G>T, p.Val175Phe) in AAAS was identified. N-acetylcysteine (600 mg orally, twice daily) decreased oxidative stress but did not change the patient’s growth pattern. Conclusions: An increase in oxidative stress is reported for the first time in vivo in an AAAS patient. N-acetylcysteine was capable of decreasing TBARS levels, reducing the susceptibility of LDL to oxidation and improving the antioxidant role of HDL. The longterm effect of antioxidant treatment should be evaluated to determine the real benefit for the prevention of the degenerative process in AAAS.
10

Effects of UV Irradiation on the Reduction of Bacterial Pathogens and Chemical Indicators of Milk

Matak, Kristen E. 03 December 2004 (has links)
Consumer demand for fresher and minimally processed foods has brought about a movement to find effective, non-thermal processing technologies for the treatment of milk. The influence of temperature on bacterial reduction in UV irradiated milk was tested. Commercially processed skim, reduced fat (2%), and whole milk samples were inoculated with a naladixic acid resistant E. coli O157:H7 surrogate (ATCC 25922), maintained at or brought to 4oC and 20oC, respectively, and then exposed to a UV light dose between 5.3-6.3 mJ/cm2 for approximately 1.5 sec using the CiderSure 3500 apparatus (FPE Inc., Macedon, NY). Bacterial concentrations before and after UV exposure were enumerated and the results indicated that processing temperature was not significantly related to bacterial reduction (p > 0.05). The results did indicate that skim milk samples had a greater bacterial reduction, regardless of processing temperature compared to reduced fat milk and whole milk samples (p < 0.05). Solids such as milk fat, protein, lactose and minerals, in the milk have a greater effect over bacterial reductions than processing temperatures. Traditional goat cheeses are produced using unpasteurized milk, which increases the food safety concerns for these types of products. Fresh goat's milk was inoculated to 107 cfu/ml with Listeria monocytogenes (L-2289) and exposed to UV light using the CiderSure 3500 apparatus. Inoculated milk was exposed to an ultraviolet dose range between 0 and 20 mJ/cm2 to determine the optimal UV dose. A greater than 5-log reduction was achieved (p < 0.0001) when the milk was processed 12 times for a cumulative exposure time of roughly 18 sec and a cumulative UV dose of 15.8 +/- 1.6 mJ/cm2. The results of this study indicate that UV irradiation could be used for the reduction of L. monocytogenes in goat's milk. Organoleptic consequences of goat's milk treated with UV technology were assessed. Olfactory studies were conducted and a highly significant difference was determined between the odor of fresh goat's milk and UV processed milk (p < 0.05). The extent of lipid oxidation and hydrolytic rancidity was measured by thiobarbituric acid reactive substances (TBARS) and acid degree values (ADVs). Results indicated that as the UV dose increased, there was a significant increase in TBARS values and ADVs of the milk samples (p < 0.05). Milk samples were processed using the UV processor under the same conditions as previously described without exposure to the UV source to determine if the agitation from pumping was causing off-flavors by way of hydrolytic rancidity. The ADVs from these samples increased at the same rate as the UV irradiated samples; however, sensory studies indicated that the increase of free fatty acids (FFA) was not enough to cause detectable off-odors in the milk. Solid phase microextraction and gas chromatography (SPME-GC) was utilized to quantify the production of volatile compounds that were formed due to UV processing. The formation of pentanal, hexanal and heptanal was identified after as little as 1.3 mJ/cm2 UV dose. Peak areas were measured and analyzed after 7.8 mJ/cm2 and 15.6 mJ/cm2 and were determined to increase significantly as UV dose increased (p < 0.05). The chemical analyses supported the findings from the olfactory studies. The outcome of this research showed that UV irradiation at the wavelength 254 nm, was detrimental to certain chemical properties of fluid milk. The properties that were perceived as negative in fluid milk may be considered an attribute in certain types of cheese and future studies in the cheese production sector should be considered. Other applications for this technology could be for use in developing countries where milk is not typically processed because of the high costs of thermal pasteurization. On-farm applications for the treatment of replacement milk should also be considered. / Ph. D.

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