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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

Equilibration of D-Glucaric Acid in Aqueous Solution

Brown, Jolene Mary January 2007 (has links)
Abstract The equilibrium of aqueous D-glucaric acid was investigated via Nuclear Magnetic Resonance (NMR) spectroscopy. The NMR spectra of all four species (D-glucaric acid, D-glucaro-1,4-lactone, D-glucaro-6,3- lactone and D-glucaro-1,4;6,3-lactone) were assigned. A 1H NMR spectroscopy method was developed to investigate the kinetics of equilibration of the starting species (D-glucaro-1,4-lactone and D-glucaro-1,4;6,3-dilactone). The equilibration was investigated under neutral conditions as well as conditions with increasing acidity. Each experiment set contained 50-100 1HNMR spectroscopy experiments that were run on the same sample using a program that built in delays. Dimethyl sulfoxide was used as an internal standard, and its signal size was used as a scale to report the changes in relative concentration of the four species throughout the experiment sets. Under neutral conditions D-glucaro-1,4-lactone is relatively stable against equilibration, while D-glucaro-1,4;6,3-dilactone is not. Under acidic conditions both compounds equilibrate within approximately 30,000 seconds. After equilibration under acidic conditions D-glucaric acid is the dominant species, while the relative concentration of D-glucaro-1,4-lactone is slightly higher than that of D-glucaro-6,3-lactone. The relative equilibrium concentration of D-glucaro-1,4;6,3-dilactone is low. A mechanism for the equilibration of aqueous D-glucaric acid was proposed and equilibrium constants and estimates of rate constants were derived from the experimental data. These rate constants were used in MATLAB simulations that were compared to the experimental data. MATLAB simulations were used to alter the rate constants to improve the fits between experimental data and simulated data.
2

Development of an Ion Chromatography Method for the Analysis of Nitric Acid Oxidation Reactions of Common Sugars

Davey, Cara-Lee January 2008 (has links)
The large scale nitric acid oxidation of common sugars into their corresponding aldaric acids is being investigated as an important source of potentially useful components for industrial applications such as polymers. This thesis details the development of an Ion Chromatography (IC) method for the analysis of these oxidation mixtures and related samples from the work-up and purification processes. The method was developed for use with a Dionex ICS2000 IC system equipped with an AS11-HC column and utilising suppressed conductivity detection. IC proved to be a useful, versatile and straightforward method of studying the reactions and their products. The detected ions include but are not restricted to the anionic salt forms of: D-Glucaric acid, Xylaric acid, Mannaric acid, D-gluconic acid and both keto forms of the same, D-xylonic acid, D-mannonic acid, glycolic acid, oxalic acid, tartaric acid and tartronic acid. Nitrate from the nitric acid used in the oxidation is often observed. The results compare favorably to GC-MS and HPLC analysis of similar samples. An overview of the theory and operation of the instrument along with the method development and results from application to the oxidation mixtures and related samples are presented. As part of the investigation into the range of utility of IC for studying these reactions, a study was made of the retention behaviour of a large number of simple and low molecular weight (LMW) carboxylic acids eluted by the ion chromatography system in use. The results of this study are included with an explanation of the major factors affecting anion retention on the column
3

Citrus bioactive compounds influencing phase II detoxifying enzymes: potential for cancer chemoprevention

Perez, Jose Luis 15 May 2009 (has links)
Several cell culture and animal studies demonstrated that citrus limonoids have protective effects against certain types of cancer. These chemopreventive properties of citrus limonoids are attributed to the induction of phase II enzyme, glutathione Stransferase (GST). In the current study, six citrus limonoids and two modified limonoids were utilized for the evaluation of NAD(P)H: quinone reductase (QR) activity and glutathione S-tranferase (GST) activity against 1-chloro-2,4-dinitrobenzene (CDNB) and 4-nitroquinoline 1-oxide (4NQO) in A/J female mice. In liver, limonoids that induced phase II enzyme activity were limonin-7- methoxime (32% CBNB), (270% 4NQO), (65% QR); and deacetylnomilin (180% QR). In stomach, limonin-7-methoxime (51% 4NQO); deacetyl nomilinic acid glucoside (55% 4NQO), nomilin (58% CDNB), (75% 4NQO); isoobacunoic acid (25% CDNB); deacetylnomilin (19% CDNB); limonoid mixture (45% 4NQO), (200% QR). Furthermore, in intestine, nomilin (280% 4NQO); deacetylnomilin (73% 4NQO), (22% QR); and the limonoid mixture (93% 4NQO) increase enzymatic activity. Finally in lung, deacetyl nomilinic acid glucoside (67% CDNB); limonin-7-methoxime (32% QR); and defuran limonin (45% QR) diplayed induction properties. Furthermore, D-glucaric acid (GA), a chemoprotective compound found in fruits and vegetables, was quantified using High Performance Liquid Chromatography (HPLC) grapefruit. Nine widely used grapefruit varieties were analyzed for the levels of D-glucaric acid. Seasonal levels of GA in each of the grapefruit varieties tested were found to be Thompson (58.36-126.8 mg/100ml), Henderson (29.6-49.7 mg/100ml), Rio Red (40.0-58.8mg/100ml), Star Ruby (25.5-46.7 mg/100ml), I-48 (26.6-58.3 mg/100ml), Ruby Red (49.3-63.0 mg/100ml), Ray’s Ruby (58.2-72.1 mg/100ml), Marsh (53.7-65.8 mg/100ml) and Duncan (50.17 mg/100ml). The HPLC method developed for the quantification of D-glucaric acid was found to be simple, fast, and reproducible. Additionally, the labor intensity and cost of sample preparation were greatly reduced.
4

D-Glucaric Acid Based Polymers and Crosslinker:Polyesters Bearing Pendent Hydroxyl Groups andDissolvable Chemically Crosslinked Gels

Seo, Junyoung 29 August 2019 (has links)
No description available.
5

D-glucaric acid excretion: its positive association with gender, tobacco, caffeine, marijuana, and vegetarianism in humans

Kyle, Elizabeth Ellen January 1982 (has links)
The urinary excretion of D-glucaric acid (DGA) has been used as a nonspecific measure of the induction of hepatic enzymes associated with drug metabolism in man. A survey of 124 nonmedicated men (18-56 years of age), who kept a 5-day food and beverage intake record and collected their total urinary output for the last three days of the five, was conducted to assess the relationship between DGA excretion and various dietary factors. Eighteen nonmedicated, healthy women collected the same data, but started recording on the eighth day from the commencement of menstruation. DGA was determined by an enzymatic assay and recorded as micromoles D-glucaro-1,4-lactone/gm creatinine. There was a positive association between total DGA excreted and the use of marijuana, caffeine, and tobacco products, the heaviest users excreting significantly higher levels of urinary DGA than the moderate or low users of the same substance. Analysis of variance of mean DGA excretion also revealed significant differences between females (17.0±3.7) and males (14.3±5.2): male vegetarians (17.4±5.5) and nonvegetarians ( 13.9±5.1) ; and female vegetarians (19.8±4.6) and nonvegetarians (16.2±3.1). Alcohol consumption and family history of cancer incidences were not significantly related to DGA excretion in either sex. Multiple regression analyses revealed that consumption were the two vegetarianism and caffeine strongest predictors of DGA excretion, while alcohol and marijuana consumption affected DGA the least. These results indicate that dietary and environmental factors can exert a significant effect on DGA excretion, and these associations may identify dietary inducers of hepatic enzymes associated with xenobiotic biotransformations in humans. / Master of Science
6

Valorisation des sucres dérivés des hémicelluloses / Upgrading sugars issued from hemicelluloses

Derrien, Elie 28 October 2015 (has links)
Résumé confidentiel / Résumé confidentiel
7

Avaliação de radiofármacos com [[99mTc]glucarato] e (18F)FAZA na determinação de hipóxia em células e tumores de melanoma murino B16F10 / Evaluation of radiopharmaceuticals with [[99mTc]glucarate] and (18F)FAZA on determination of hypoxia in B16F10 murine melanoma cells and tumors

Evangelista, Monick Junho do Amaral 04 October 2013 (has links)
A baixa oxigenação (hipóxia) altera drasticamente o metabolismo celular e a forma de produção de ATP, que em tumores pode estimular e permitir que as células desenvolvam mecanismos de escape, adaptação e resistência, contribuindo não só para um comportamento maligno e agressivo, mas também lhes conferindo resistência a tratamentos quimioterapêuticos e radioterapêuticos. A detecção de regiões de hipóxia em tumores pode ser realizada com diferentes radiofármacos. Neste trabalho preparamos e avaliamos o comportamento dos radiofármacos (18F)FAZA e [[99mTc]glucarato]- em células de melanoma murino B16F10, correlacionando dados bioquímicos e histopatológicos com a captação celular dos radiofármacos in vitro e com imagens em equipamento PET/SPECT/CT obtidas de camundongos C57Bl6 implantados com tumores. O (18F)FAZA foi obtido em rendimento de 17,9 % e pureza radioquímica de 86,72 %, enquanto que o rendimento e pureza radioquímica do [[99mTc]glucarato]- foi superior a 95 %, sendo que este complexo se liga à proteínas plasmáticas com taxa de aproximadamente 40 % e o complexo é desestabilizados pela mesmas, após 4 horas de incubação a 37 oC. O complexo também não é estável na presença de cisteína e histidina. A captação in vitro do [[99mTc]glucarato]- nas células foi da ordem de 0,1 % independente da condição e do tempo, enquanto que a captação de (18F)FAZA atingiu 0,9 % sob hipóxia e 0,2 % sob normóxia, nos primeiros 15 minutos de estudo. A biodistribuição ex vivo em camundongos apresentou taxa de captação por grama de tumor e razão tumor/sangue da ordem de 0,04 % e 1,49 para o [[99mTc]glucarato]- e de 0,34 % e 1,39 para o (18F)FAZA, em tempo de 1 hora. Imagem obtidas de camundongos, mostraram intensa captação da (18F)FDG no tumor, e tanto (18F)FAZA quanto [[99mTc]glucarato]- foram capazes de evidenciar regiões de hipóxia ou necrose, respectivamente, nos tumores, ainda que com baixa taxa de captação. Imagens autorradiográficas do [[99mTc]glucarato]- nos tumores excisados dos animais apresentaram distribuição homogênea no tumor, com algumas áreas de captação sugeridas como necróticas; tomando a autorradiografia como referência, o [[99mTc]glucarato]- não se concentrou na córtex renal, região reconhecidamente hipóxica. Assim, (18F)FAZA e [[99mTc]glucarato]- puderam ser preparados em nosso laboratório com qualidade suficiente para uso em pesquisa e demonstram potencial para utilização em novos estudos visando a detecção de regiões de hipóxia ou necrose, respectivamente / The low oxygen concentration, also named hypoxia, drastically alters cellular metabolism and the production form of ATP which, in tumors, can stimulate and allow cells to develop mechanisms for escape, adaptation and resistance, contributing not only to malignant and aggressive behavior, but also their conferring resistance to chemotherapeutic and radiotherapeutic treatments. The detection of regions of hypoxia in tumors can be performed using different radiopharmaceuticals. In this work we prepared and evaluated the behavior of radiopharmaceuticals (18F)FAZA and [[99mTc]glucarate]- in B16F10 murine melanoma cells, biochemical and histopathological data correlating it with the radiopharmaceutical cellular uptake, both in vitro or by PET/SPECT/CT imaging obtained from C57Bl6 mice implanted with tumors. The (18F)FAZA was obtained in radiochemical yield of 17.8 % and radiochemical purity of 86.72 %, while the radiochemical yield and purity for [[99mTc]glucarate] - was higher to 95 %, and this complex binds to the plasma proteins at concentration of 40 %, however a the complex is unstable in presence of albumine after 4 hours, at 37 oC. The complex is unstable in the presence of cysteine and histidine, at 37 oC. The in vitro uptake of [[99mTc]glucarate]- in B16F10 cells was approximately 0.1% independently of experimental conditions, while (18F)FAZA reached 0.9%, under hypoxia, and 0.2%, under normoxia, the first 15 minutes of the study. The ex vivo biodistribution in mice showed uptake in tumor and tumor/blood ratio of the 0.04 % and 1.49 for [[99mTc]glucarate]- and 0.34 % and 1.39 for (18F)FAZA. Imaging obtained from mice showed intense uptake of (18F)FDG in the tumor, and both (18F)FAZA and [[99mTc]glucarate]- were able to show hypoxia or necrotic regions in the tumor. Autoradiographic imaging showed homogeneous distribution of [[99mTc]glucarate]- in the slices of tumor excised from animals; taking kidney autoradiography as a reference, the [[99mTc]glucarate]- was not concentrated in renal cortex, a region admittedly hypoxic. In conclusion (18F)FAZA and [[99mTc]glucarate]- could be prepared in our laboratory with sufficient quality for use in research and demonstrate potential for use in future studies aiming to detect regions of hypoxia and necrosis, respectively
8

Avaliação de radiofármacos com [[99mTc]glucarato] e (18F)FAZA na determinação de hipóxia em células e tumores de melanoma murino B16F10 / Evaluation of radiopharmaceuticals with [[99mTc]glucarate] and (18F)FAZA on determination of hypoxia in B16F10 murine melanoma cells and tumors

Monick Junho do Amaral Evangelista 04 October 2013 (has links)
A baixa oxigenação (hipóxia) altera drasticamente o metabolismo celular e a forma de produção de ATP, que em tumores pode estimular e permitir que as células desenvolvam mecanismos de escape, adaptação e resistência, contribuindo não só para um comportamento maligno e agressivo, mas também lhes conferindo resistência a tratamentos quimioterapêuticos e radioterapêuticos. A detecção de regiões de hipóxia em tumores pode ser realizada com diferentes radiofármacos. Neste trabalho preparamos e avaliamos o comportamento dos radiofármacos (18F)FAZA e [[99mTc]glucarato]- em células de melanoma murino B16F10, correlacionando dados bioquímicos e histopatológicos com a captação celular dos radiofármacos in vitro e com imagens em equipamento PET/SPECT/CT obtidas de camundongos C57Bl6 implantados com tumores. O (18F)FAZA foi obtido em rendimento de 17,9 % e pureza radioquímica de 86,72 %, enquanto que o rendimento e pureza radioquímica do [[99mTc]glucarato]- foi superior a 95 %, sendo que este complexo se liga à proteínas plasmáticas com taxa de aproximadamente 40 % e o complexo é desestabilizados pela mesmas, após 4 horas de incubação a 37 oC. O complexo também não é estável na presença de cisteína e histidina. A captação in vitro do [[99mTc]glucarato]- nas células foi da ordem de 0,1 % independente da condição e do tempo, enquanto que a captação de (18F)FAZA atingiu 0,9 % sob hipóxia e 0,2 % sob normóxia, nos primeiros 15 minutos de estudo. A biodistribuição ex vivo em camundongos apresentou taxa de captação por grama de tumor e razão tumor/sangue da ordem de 0,04 % e 1,49 para o [[99mTc]glucarato]- e de 0,34 % e 1,39 para o (18F)FAZA, em tempo de 1 hora. Imagem obtidas de camundongos, mostraram intensa captação da (18F)FDG no tumor, e tanto (18F)FAZA quanto [[99mTc]glucarato]- foram capazes de evidenciar regiões de hipóxia ou necrose, respectivamente, nos tumores, ainda que com baixa taxa de captação. Imagens autorradiográficas do [[99mTc]glucarato]- nos tumores excisados dos animais apresentaram distribuição homogênea no tumor, com algumas áreas de captação sugeridas como necróticas; tomando a autorradiografia como referência, o [[99mTc]glucarato]- não se concentrou na córtex renal, região reconhecidamente hipóxica. Assim, (18F)FAZA e [[99mTc]glucarato]- puderam ser preparados em nosso laboratório com qualidade suficiente para uso em pesquisa e demonstram potencial para utilização em novos estudos visando a detecção de regiões de hipóxia ou necrose, respectivamente / The low oxygen concentration, also named hypoxia, drastically alters cellular metabolism and the production form of ATP which, in tumors, can stimulate and allow cells to develop mechanisms for escape, adaptation and resistance, contributing not only to malignant and aggressive behavior, but also their conferring resistance to chemotherapeutic and radiotherapeutic treatments. The detection of regions of hypoxia in tumors can be performed using different radiopharmaceuticals. In this work we prepared and evaluated the behavior of radiopharmaceuticals (18F)FAZA and [[99mTc]glucarate]- in B16F10 murine melanoma cells, biochemical and histopathological data correlating it with the radiopharmaceutical cellular uptake, both in vitro or by PET/SPECT/CT imaging obtained from C57Bl6 mice implanted with tumors. The (18F)FAZA was obtained in radiochemical yield of 17.8 % and radiochemical purity of 86.72 %, while the radiochemical yield and purity for [[99mTc]glucarate] - was higher to 95 %, and this complex binds to the plasma proteins at concentration of 40 %, however a the complex is unstable in presence of albumine after 4 hours, at 37 oC. The complex is unstable in the presence of cysteine and histidine, at 37 oC. The in vitro uptake of [[99mTc]glucarate]- in B16F10 cells was approximately 0.1% independently of experimental conditions, while (18F)FAZA reached 0.9%, under hypoxia, and 0.2%, under normoxia, the first 15 minutes of the study. The ex vivo biodistribution in mice showed uptake in tumor and tumor/blood ratio of the 0.04 % and 1.49 for [[99mTc]glucarate]- and 0.34 % and 1.39 for (18F)FAZA. Imaging obtained from mice showed intense uptake of (18F)FDG in the tumor, and both (18F)FAZA and [[99mTc]glucarate]- were able to show hypoxia or necrotic regions in the tumor. Autoradiographic imaging showed homogeneous distribution of [[99mTc]glucarate]- in the slices of tumor excised from animals; taking kidney autoradiography as a reference, the [[99mTc]glucarate]- was not concentrated in renal cortex, a region admittedly hypoxic. In conclusion (18F)FAZA and [[99mTc]glucarate]- could be prepared in our laboratory with sufficient quality for use in research and demonstrate potential for use in future studies aiming to detect regions of hypoxia and necrosis, respectively

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