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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.
61

Određivanje trans masnih kiselina u prehrambenim proizvodima gasnom hromatografijom-masenom spektrometrijom / Determination of trans fatty acids in foodstuffs by gaschromatography-mass spectrometry

Kravić Snežana 04 October 2010 (has links)
<p>U okviru doktorske disertacije optimizovani su uslovi određivanja<br />metilestara masnih kiselina, uključujući i trans izomere, primenom<br />kapilarne gasne hromatografije&ndash;masene spektrometrije, na<br />kapilarnoj koloni SP-2560 (dužina x unutra&scaron;nji prečnik: 100 m x<br />0,25 mm, debljina sloja stacionarne likvidne faze 0,20 &mu;m,<br />biscijanopropil polisiloksan). Kori&scaron;ćenjem standarnih rastvora<br />metilestara masnih kiselina optimizovani su temperaturni program,<br />odnos razdeljivanja i uslovi akvizicije podataka SCAN tehnikom.<br />Razvijena je metoda za pripremu uzoraka u cilju određivanja sastava<br />masnih kiselina u prehrambenim proizvodima gasnom<br />hromatografijom&ndash;masenom spektrometrijom zasnovana na<br />istovremenoj mikrotalasnoj ekstrakciji i esterifikaciji (SMEE).<br />Validacija metode je izvedena poređenjem sa rezultatima dobijenim<br />gasnom hromatografijom&ndash;masenom spektrometrijom nakon<br />ekstracije po Soxhlet-u i derivatizacije masnih kiselina u metilestre<br />masnih kiselina. Rezultati dobijeni primenom razvijene i referentne<br />metode bili su statistički isti, kako u pogledu sastava masnih<br />kiselina, tako i efikasnosti ekstrakcije. Rezultati su pokazali da su<br />prednosti SMEE u odnosu na konvencionalnu metodu: kratko vreme<br />pripreme uzoraka i samim tim manja potro&scaron;nja energije, kao i<br />upotreba malih količina skupih organskih rastvarača. Dobro slaganje<br />rezultata dobijenih primenom referentne i metode zasnovane na<br />istovremenoj mikrotalasnoj ekstrakciji i esterifikaciji pokazuje da bi<br />se SMEE mogla primeniti kao rutinska metoda za pripremu uzoraka<br />prehrambenih proizvoda u cilju određivanja trans masnih kiselina<br />(TFA). Određen je sastav masnih kiselina, sa posebnim akcentom na<br />trans masne kiseline, u 273 uzoraka prikupljenih sa na&scaron;eg trži&scaron;ta u<br />periodu od juna 2006. do juna 2009. godine. Sadržaj trans masnih<br />kiselina u analiziranim uzorcima prehrambenih proizvoda, sirovina i<br />međuproizvoda koji se koriste u pekarskoj i konditorskoj industriji,<br />kretao se u veoma &scaron;irokom intervalu, od 0,0% do čak 48,7%.<br />Prosečan sadržaj trans masnih kiselina iznosio je 0,2% u uljima,<br />6,5% u jestivim margarinima, 19,9% u margarinima za domaćinstvo,<br />9,8% u industrijskim margarinima, 24,3% u namenskim mastima,<br />10,8% u masnim punjenjima, 1,6% u mlečnim proizvodima, 10,9%<br />u slanom trajnom pecivu, 10,2% u čajnom pecivu, 6,3% u tvrdom<br />keksu, 11,0% u vafel proizvodima, 10,6% u čokoladnim<br />proizvodima i 9,2% u karamelama. Od ukupno 124 analizirana<br />uzorka, koja se ne koriste za direktnu upotrebu u ishrani (namenske<br />masti, masna punjenja, industrijski i margarini za domaćinstvo) 86<br />uzoraka (69,3%) sadrži vi&scaron;e od 5% trans masnih kiselina, 25<br />(20,2%) sadrži manje od 5% TFA, dok u 13 uzoraka (10,5%) nije<br />detektovano prisustvo trans izomera. Od ukupno 140 analiziranih<br />uzoraka, koji se koriste za direktnu upotrebu u ishrani 74 uzoraka<br />(52,8%) sadrži vi&scaron;e od 2% trans masnih kiselina, 20 (14,3%) sadrži<br />manje od 2% TFA, dok u 46 uzoraka (32,9%) nije detektovano<br />prisustvo trans izomera.</p> / <p>In this thesis, operating conditions for fatty acids determination,<br />including trans isomers, by capillary gas chromatography&ndash;mass<br />spectrometry, on capillary column SP-2560 (100 m x 0.25 mm, with<br />a 0.20 &mu;m film thickness of biscyanopropyl polysiloxane liquid<br />phase) were optimized. Temperature program, split ratio and<br />condition of data acquisition by SCAN technique were optimized<br />using standard solutions of fatty acid methyl esters. A sample<br />preparation method based on simultaneous microwave assisted<br />extraction&ndash;esterification (SMEE) was developed for the<br />determination of the fatty acid composition of foodstuffs by gas<br />chromatography&ndash;mass spectrometry. The proposed sample<br />preparation method was validated by comparison with the reference<br />Soxhlet extraction method followed by derivatisation by methyl<br />ester formation and the same determination step. The fatty acid<br />compositions, as well as extraction efficiencies obtained by the use<br />of the proposed SMEE method and reference method were<br />statistically similar. The results showed that compared to the<br />conventional method, SMEE method offer the advantages of short<br />sample preparation time, low consumption of expensive organic<br />solvents and less energy consumption. This good agreement between<br />results provided, both by the SMEE and reference method,<br />demonstrates the usefulness of the former as the routine method for<br />the treatment of food samples prior to trans fatty acid analysis. The<br />fatty acid composition, and trans fatty acid content of 273 samples<br />collected from June 2006 to June 2009 year were determined. Trans<br />fatty acid content in the analysed samples of food products, raw<br />materials and intermediate products used in bakery and<br />confectionery industry was ranged in a very wide interval, from<br />0.0% to 48.7%. The average contents of trans fatty acids were 0.2%<br />in oils, 6.5% in the edible margarines, 19.9% in cooking margarines,<br />9.8% in industrial margarines, 24.3% in shortenings, 10.8 % in fat<br />fillings, 1.6% in dairy products, 10.9% in crackers, 10.2% in tea<br />cookies, 6.3% in biscuits, 11.0% in wafer products, 10.6% in<br />chocolate products and 9.2% in the caramels. From the total of 124<br />analysed samples, which are not used for direct human consumption<br />(shortenings, fat fillings, industrial and cooking margarines) 86<br />samples (69.3%) contained more than 5% trans fatty acids, 25 (20.2<br />%) contained less than 5% TFA, while 13 samples (10.5%) had an<br />undetectable levels of trans isomers. From a total of 140 analysed<br />samples, which are used for direct human consumption 74 food<br />samples (52.8%) contained more than 2% trans fatty acids, 20<br />(14.3%) contained less than 2% TFA, while 46 samples (32.9%) had<br />an undetectable levels of trans isomers.</p>
62

Climate Change Impacts on the Molecular-level Carbon Biogeochemistry in Arctic Ecosystems

Pautler, Brent Gregory 27 July 2010 (has links)
The goal of this thesis was to characterize and quantify changes to Canadian Arctic organic matter (OM) induced by a physical disruption to the permafrost active layer by employing molecular-level techniques such as biomarker extraction and NMR to help elucidate its contribution to carbon turnover and global climate change. The initial biomarker characterization study determined that the extractable plant lipids were unaltered originating from the deposition of new vascular material or permafrost melt where a high alteration of lignin-derived OM was observed suggesting a long residence time in the ecosystem. Analysis of samples where there was a new and historical physical disruption to the permafrost landscape showed an initial increase in bacterial biomass biomarkers, and was corroborated with increased bacterial protein contributions and peptidoglycan signals in the NMR spectra. It is hypothesized that this increase in bacterial biomass resulted in a faster rate of degradation, possibly leading to OM priming.
63

Climate Change Impacts on the Molecular-level Carbon Biogeochemistry in Arctic Ecosystems

Pautler, Brent Gregory 27 July 2010 (has links)
The goal of this thesis was to characterize and quantify changes to Canadian Arctic organic matter (OM) induced by a physical disruption to the permafrost active layer by employing molecular-level techniques such as biomarker extraction and NMR to help elucidate its contribution to carbon turnover and global climate change. The initial biomarker characterization study determined that the extractable plant lipids were unaltered originating from the deposition of new vascular material or permafrost melt where a high alteration of lignin-derived OM was observed suggesting a long residence time in the ecosystem. Analysis of samples where there was a new and historical physical disruption to the permafrost landscape showed an initial increase in bacterial biomass biomarkers, and was corroborated with increased bacterial protein contributions and peptidoglycan signals in the NMR spectra. It is hypothesized that this increase in bacterial biomass resulted in a faster rate of degradation, possibly leading to OM priming.
64

Application of hydrogen bond acidic polycarbosilane polymers and solid phase microextraction for the collection of nerve agent simulant /

Boglarski, Stephen L January 2006 (has links) (PDF)
Thesis (M.S.P.H.)--Uniformed Services University of the Health Sciences, 2006 / Typescript (photocopy)
65

Evaluation of the volatile organic profile profile generated from thermally degraded tissue: analysis by solid phase microextraction and gas chromatography/mass spectrometry

Tincher, Heidi 12 March 2016 (has links)
Ample research has been published regarding the effects of environmental decomposition on volatile organic profiles of tissue, however literature concerning the volatile organic profiles of thermally degraded tissue is limited in quantity and scope. The purpose of this study was to investigate the effects of temperature on the headspace volatile organic compounds produced by muscle, subcutaneous fat, skin, and punch biopsy samples. The majority of the compounds for each tissue type were alcohols and aldehydes. Compounds were extracted using solid phase microextraction and identified using gas chromatography/mass spectrometry. Compounds such as nonanal, 1-octen-3-ol, octanal, and hexanal were present in the volatile organic compound profile for many tissue types at a majority of the temperatures, particularly from 150°C to 300°C. 2-pentylfuran was the most abundant component in the profile of skin samples from 150°C to 300°C. The profile of fresh subcutaneous fat had numerous branched alkanes, while thermally degraded subcutaneous fat profiles were comprised mostly of aldehydes and alcohols. The profile of muscle was primarily composed of alcohols and aldehydes up to 300°C, whereas the most abundant compound at 350°C was trimethylpyrazine. There were consistent compounds identified among each tissue group. The abundance patterns of alcohols and aldehydes over increasing temperatures differed for each tissue type. Analysis of the data gathered in this study indicates that muscle, subcutaneous fat, and skin contribute characteristic compounds, such as alcohols and aldehydes, to the profile of the punch biopsy samples. The findings further suggest that temperature affects the volatile organic profile of tissue in terms of the compounds identified and the abundance trends of certain compounds.
66

The final masquerade : a molecular-based approach to the identification of resinous plant exudates in Roman mortuary contexts in Britain and evaluation of their significance

Brettell, Rhea C. January 2016 (has links)
This study provides chemical confirmation for the use of resinous plant exudates in mortuary contexts in Roman Britain. Analysis of amorphous masses, adhering residues and grave deposits using gas chromatography-mass spectrometry has revealed terpenoid biomarkers in sixteen inhumation and two cremation burials. The natural products characterized include European Pinaceae (conifer) resins, Pistacia spp. (mastic/terebinth) resins from the Mediterranean or the Levant and Boswellia spp. (frankincense) gum-resins from southern Arabia or eastern Africa. In addition, traces of a balsamic resin, probably Liquidambar orientalis, have been identified. A correlation between the use of these exotic exudates and interment in substantial, often multiple, containers with high-quality textiles and grave goods was observed. Theoretical consideration of this imported rite illuminates the multiplicity of roles played by resins/gum-resins in the mortuary sphere. The material properties of these highly scented substances speak to the biological reality of the decomposing body and to the socially constructed identity of the individual. On a practical level, they acted as temporary preservatives and masked the odour of decay. As social signifiers, they denoted the status of the deceased and promoted remembrance through conspicuous consumption and sensory impact. Encoded with ritual meaning, they purified the body and facilitated the final rite of passage to the afterlife. The recovery of these resinous traces provides us with new insights into the treatment of the body in the Roman period and establishes fresh links between the remote province of Britannia and the remainder of the Empire.
67

Bioprospecção de fotossensiblizadores naturais e substâncias bioativas em Eugenia chlorophylla e desenvolvimento de procedimentos analíticos / Bioprospecting of photosensitizers and natural bioactive substances in Eugenia chlorophylla and development of analytical procedures

Lourenço, Caroline Caramano de, 1988- 20 August 2018 (has links)
Orientador: Marcos José Salvador / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T10:46:35Z (GMT). No. of bitstreams: 1 Lourenco_CarolineCaramanode_M.pdf: 7003473 bytes, checksum: 01a19e43e829c4233180019cb1a470d8 (MD5) Previous issue date: 2012 / Resumo: Este estudo teve por objetivo a prospecção químico-farmacológica de fotossensibilizadores naturais para aplicação em terapia fotodinâmica (PDT) antimicrobiana e de substâncias bioativas acumuladas no extrato etanólico das folhas de Eugenia chlorophylla (Myrtaceae), bem como a caracterização química e da atividade antimicrobiana dos óleos essenciais das folhas, caule e flores desta espécie vegetal. Para tanto, procedeu-se o preparo do extrato vegetal bruto (hexânico e etanólico) a partir das folhas de E. chlorophylla e a avaliação da absorção de luz na região espectral do visível de interesse e útil para aplicação em PDT. O extrato bruto etanólico foi submetido a uma extração líquido-líquido com hexano, diclorometano e butanol. Os melhores resultados na avaliação da absorção de luz na região espectral do visível de interesse e útil para aplicação em PDT foram obtidos com o extrato bruto e com a fração diclorometânica da partição, para os quais foram avaliadas suas características fluorescentes em estado estacionário no modo de emissão e excitação (caracterização preliminar de suas propriedades fotoquímicas e fotofísicas). Desenvolveuse a adequação de metodologia para uma avaliação inicial da eficiência fotoquímica dos extratos e frações obtidos (produção de oxigênio singlete, ensaio, 1,3 - diphenylisobenzofuran (DPBF), bem como adequou-se os procedimentos para a realização dos bioensaios na presença e ausência de luz. Procedeu-se a avaliação da atividade antimicrobiana in vitro com o extrato bruto etanólico e suas frações da partição líquidolíquido, na ausência de irradiação laser, determinando-se os valores de Concentração Inibitória Mínima (CIM) para as amostras bioativas e estimando-se os valores de concentração subinibitória que seriam usados na PDT atimicrobiana. Ainda, foram estabelecidos os procedimentos para a padronização do protocolo experimental de PDT antimicrobiana frente a bactérias (Gram positivas e Gram negativas) e leveduras in vitro e avaliou-se o efeito do extrato bruto etanólico e da fração diclorometânica como fotossensibilizadores naturais em PDT antimicrobiana, utilizando-se 11 cepas indicadoras. De acordo com os resultados obtidos o extrato bruto etanólico (ECB) e sua fração diclorometânica (ECD) apresentaram absorção de luz na região de 600 a 800 nm, demonstrou a capacidade de formar oxigênio singlete no ensaio com DPBF quando irradiados pelo laser e apresentou resultado efetivo na inativação de algumas das cepas indicadoras (bactérias e leveduras) em PDT antimicrobiana quando irradiados em sessão única por 5 min com laser diodo InGaAlP, ?=660nm. A partir dos resultados dos ensaios com DPBF e com a utilização de inibidores específicos do mecanismo fotoquímico em modelo biológico sugeriu-se que o mecanismo fotoquímico predominante para ECD é o do tipo II (mediado pela formação de oxigênio singlete). Deu-se inicio ao estudo fitoquímico monitorado pela absorção de luz na região do visível (400 a 830 nm), pela avaliação da eficiência fotoquímica e pelas atividades biológicas. Pelo resultado do estudo de desreplicação por ESI-MS/MS do extrato etanólico bruto e da fração ECD sugeriu-se a presença do ácido quínico nestas amostras. Como as folhas frescas de E. chlorophylla apresentavam odor intenso e neste projeto foi proposto também estudo para a prospecção de substâncias bioativas, realizou-se um estudo para a caracterização química e avaliação da atividade antimicrobiana dos óleos essenciais das folhas, caule e flores desta espécie vegetal. A caracterização química dos constituintes majoritários do óleo essencial foi realizada por cromatografia gasosa (CG-EM). Os óleos essenciais das folhas, caule e flores de E. chlorophylla foram obtidos por hidrodestilação e apresentaram rendimento de 0,01 a 0,1%. Setenta e cinco componentes foram identificados, representando mais de 85% do total do óleo. Os principais componentes detectados nos óleos essenciais foram Ecariofileno (flores), óxido de cariofileno (caule, flores e folhas), globulol (caules e folhas) e T-muurolol, 1-epi-cubenol e ?-cadinol (caule, flores e folhas). Todos os óleos mostraram leve a moderada atividade antimicrobiana (na ausência de radiação laser), sobre principalmente as bactérias Gram positivas e Candida albicans, sendo estes resultados similares ao observado na literatura para esta espécie vegetal, com exceção do óleo do caule, coletado em 2011, que não se mostrou ativo nas condições experimentais utilizadas e é composto, predominantemente (85,4%) por um constituinte alifático para o qual não foi possível identificar a estrutura química por CG-EM. Ainda, observou-se variação nos valores de concentração inibitória mínima frente às cepas bioativas dependendo do ano de coleta e armazenagem dos óleos essenciais obtidos / Abstract: This study aimed at making a chemical-pharmacological search for prospection of natural photosensitizers in photodynamic therapy (PDT) and of bioactive compounds accumulated in the ethanolic extract of leaves from Eugenia chlorophylla (Myrtaceae) and to study the chemical characterization and antimicrobial activity of essential oils from leaves, stems and flowers of this plant species. For this purpose, we carried out the preparation of the crude plant extract (hexane and ethanol) from the leaves of E.chlorophylla followed by the assessment of light absorption in the visible spectral region of interest could be useful for application in PDT. The crude ethanol extract was subjected to a liquid-liquid extraction with hexane, dichloromethane and butanol. The best results for the absorption of light in the visible spectral region of interest to gets with usefulness for application in PDT were obtained for the crude extract and dichloromethane fraction, which were evaluated for their characteristics in steady-state fluorescent emission mode and excitement (preliminary characterization of photochemical properties). Still, it has adequate methodology was developed for an initial assessment of the photochemical efficiency of extracts (production of singlet oxygen, DPBF test 1.3-diphenylisobenzofuran) as well as the adequate conformed for the achievement of bioassays in the presence and absence of light. Evaluation of antimicrobial activity was carried out in vitro with a crude ethanol extract and their fractions from liquid-liquid partition, in the absence of laser irradiation, determining the values of minimum inhibitory concentration (MIC) in antimicrobial testes for bioactive samples and estimating the sub-inhibitory concentration values which would be used in antimicrobial PDT. Standardization of the experimental protocol of in vitro antimicrobial PDT was carried out against Gram positive and Gram-negative bacteria and yeast the effect of the crude ethanol extract and the dichloromethane fraction evaluated as natural photosensitizes in antimicrobial PDT using 11indicator strains. According to results obtained from the crude ethanol extract (ECB) and its dichloromethane fraction (ECD) showed light absorption in the region from 600 to 800 nm, it was demonstrated that singlet oxygen was formed in the assay with DPBF when irradiated by laser ( ?=660nm) showed effective results in the inactivation of antimicrobial PDT in some of the indicator strains (bacteria and yeasts) when irradiated in a single session for 5 min with InGaA1P laser diode. Along with the test result with DPBF, research using specific inhibitors of the photochemical mechanism in a biological model suggests that the dominant photochemical mechanism for ECD is the type II (mediated by the formation of singlet oxygen). We carried out the phytochemical study monitored by light absorption in the visible region (400 to 830nm), in which the evaluation of photochemical efficiency and biological activities and the results of the study of dereplication of the crude ethanolic extract and the ECD fraction by ESI-MS/MS suggest the presence of quinic acid in these samples. Since the fresh leaves of E. chlorophylla have an intense smell and this project also contemplated a search for bioactive substances a study was carried out for the chemical characterization and antimicrobial activity of essential oils from leaves, stems and flowers of the plant species. The chemical characterization of the major constituents of the essential oil was performed by gas chromatography (GC-MS). Essential oils from leaves, stems and flowers of E. chlorophylla were obtained by hydrodistillation and presented a yield of 0.01 to 0.1%. Seventy-five compounds were identified, representing over 85% of the total oil. The main components were E-caryophyllene (flowers), caryophyllene oxide (stem, leaves and flowers), globulol (stems and laves) and T-muurolol, 1-epi-? cubenol, and ?-cadinol (stem, leaves and flowers). All essential oils studied showed mild to moderate antimicrobial activity mainly associated with Gram positive bacteria and Candida albicans with results similar to those observed in the literature for this plant species. An exception was the stem oil collected in 2011 that was not active in the experimental conditions used and is constituted predominantly (85.4%) for an aliphatic constituent not identified by GC-MS. Was verified variation in the minimum inhibitory concentration values of essential oils of E. chlorophylla with the year of collect and with storage time / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal
68

Keramikk - fortidens stemme : Lipidanalyse på keramikk fra Påtåker, Sollentuna, Uppland, Sverige.

Wehmer, Kathrine January 2016 (has links)
This paper is about food culture in Uppland under early iron age in Upplans, Sverige. Gas chromatography–mass spectrometry (GC-MS) was used to analysis the lipids that were extracted from archaeological potsherds from Påtåker Raä 62, Sollentuna, Uppland. The result of the lipid analysis shows content of aquatic animal products, terrestrial animal products, vegetables and indication of being heated. Based on these results and what is considered to be a normal diet during the Iron Age, it is possible to say that there are similarities. These results are also compared with three sites from Late Iron Age – Vendel 1:1, Vendel 28 and Tuna, to see if there are any similarities. The reason to choose three sites from Late Iron Age, and not Early Iron Age, is because there haven’t been done studies like this on material from the early Iron Age. Vendel 28 was the site that was most similar to Påtåker, when it comes to its enviorment with meadows and woods, and the ceramics application areas. / This study is part of the on going research of Påtåker Raä 62, Sollentuna, Oppland.
69

Tryptophan and the kynurenine pathway in chronic renal failure patients on dialysis

Bipath, Priyesh 21 October 2008 (has links)
Tryptophan is metabolised along the kynurenine pathway under the influence of tryptophan 2,3 dioxygenase and indoleamine 2,3 dioxygenase. Quinolinic acid and kynurenine, two neuroactive metabolites of the kynurenine pathway are, in chronic renal failure patients, considered as uraemic toxins. Related research is generally hampered by the non-availability of relevant analytical techniques. The primary aim of this study was, therefore, to develop and validate suitable methods for the determination of tryptophan, kynurenine and quinolinic acid. The second aim was to quantify the levels of these substances in the blood of chronic renal failure patients on renal replacement therapies and to compare the levels of haemodialysis patients to those on peritoneal dialysis. Patients’ quality of life was investigated relative to disturbances in tryptophan metabolism. Gas chromatography coupled to mass spectrometry (GC-MS) gave the best results for the analysis of tryptophan, kynurenine and quinolinic acid. A Hewlett Packard HP GC 6890 series gas chromatographer was coupled to a MS 5973 series mass spectrometer. Analytes were separated on a DB-5MS column with a nominal length of 30 metres, a diameter of 250.0 µm and film thickness of 0.10 µm. Helium was used as carrier gas, and the chromatographic analysis run time 12.5 minutes. The validation results were within the acceptance criteria for newly developed methods. The linear calibration curves constructed for all of the analytes gave r2 correlation coefficients >0.99. Other validation data such as precision, bias, accuracy and stability all fell within acceptable validation limits. In the study on chronic renal failure patients significant differences were seen between patients and controls. Tryptophan levels were 5.34 SD 5.04 µM for the haemodialysis group, 6.73 SD 3.18 µM for the peritoneal dialysis group and 28.4 SD 4.31 µM for the control group. Kynurenine levels were 4.7 SD 1.9 µM for the haemodialysis group, 2.9 SD 2.0 µM for the peritoneal dialysis group and 2.1 SD 0.6 µM for the control group. Quinolinic acid levels were 4.9 SD 2.0 µM for the haemodialysis group, 2.8 SD 2.0 µM for the peritoneal dialysis group and 0.3 SD 0.1 µM for the control group. Tryptophan was lower for the total patient group than for controls with significantly lower levels for haemodialysis versus control (p<0.05) and peritoneal dialysis versus control (p<0.05). Kynurenine levels were higher in the total patient group with significantly higher levels for the haemodialysis versus control group (p=0.0001). The patient groups had higher quinolinic acid levels with significantly higher levels for the haemodialysis versus control (p<0.05) and peritoneal dialysis versus control (p<0.05) groups. This study was the first to determine the three substances simultaneously in both haemodialysis and peritoneal dialysis patients. The study showed significant tryptophan depletion, as well as kynurenine and quinolinic acid accumulation for both groups. No significant differences were found between the patient groups other than higher kynurenine levels in the haemodialysis group. The quality of life (SF-36) was largely similar in the two patient groups. This decrease in the quality of life strongly correlated with the degree of tryptophan depletion. / Dissertation (MSc)--University of Pretoria, 2008. / Chemical Pathology / unrestricted
70

A systems approach to understanding Dupuytren's disease

Rehman, Samrina January 2011 (has links)
Introduction: Dupuytren's disease (DD) is an ill-defined fibroproliferative disorder affecting the palms of the hands of certain patient groups. Whether changes in DD fibroblasts are due to genetic alterations alone or related to metabolic dysregulation has not yet been investigated. Hypotheses: 1. DD is a disease of several networks rather than of a single gene. 2. DD may be investigated more effectively by employing systems biology. 3. Strict definition of cell passage number is important for the revelation of any DD phenotype. 4. Some of the differences between DD and healthy tissues reside in a difference in their respiratory metabolism. 5. Any such differences are akin the Warburg effect noted for tumour cells in the literature. Methods: We induced hypoxia in healthy and disease cells to test whether the difference in disease cell types and healthy is the same as the difference in control fibroblasts cultured in normoxia and hypoxia. We investigated both at the metabolic level (intracellular and extracellular) and at the transcript level. This study also employed Fourier transform infrared spectroscopy to permit profiling of cells: (1) DD cords and nodules against the unaffected transverse palmar fascia (internal control), (2) those (1) with carpal ligamentous fascia (external controls) (3) those in (1) against DD fat surrounding the nodule, and skin overlying the nodule. We then compared metabolic profiles of the above to determine the effect of serial passaging by assessment of reproducibility. Subsequently, a novel protocol was employed in carefully controlled culture conditions for the parallel extraction of the metabolome and transcriptome of DD-derived fibroblasts and control at normoxic and hypoxic conditions to investigate this hypothesis. Gas chromatography-mass spectrometry combined with microarrays was employed to identify metabolites and transcript characteristic for DD tissue phenotypes. The extracellular metabolome was also studied for a selected subset. The metabolic and transcriptional changes were then integrated employing a network approach. Results: Carefully controlled culture conditions combined with multivariate statistical analyses demonstrated metabolic differences in DD and unaffected transverse palmar fascia, in addition to the external control. Differences between profiles of the four DD tissue phenotypes were also demonstrated. In addition early passage (0-3) metabolic differences were observed where a clear separation pattern in clusters was observed. Subsequent passages (4-6) displayed asynchrony, losing distinction between diseased and non-diseased sample phenotypes. A substantial number of dysregulated metabolites involved in amino acid metabolism, carbohydrate metabolism and also metabolism of cofactors and vitamins including downregulated cysteine and aspartic acid have been identified from the integrative analyses. Metabolic and transcriptional differences were revealed between fibroblast cell samples (passage number 3) cultured in 1% and 21% oxygen. The hypothesis that the difference in disease and healthy cells maybe akin to the differences in healthy cells in normoxia and hypoxia was rejected as only a very small number of significant molecules from these studies coincided in perturbed fascia and disease samples. No lactic acid was observed and little difference in the pyruvate concentrations. Yet, upon perturbation several of these transcripts and metabolites involved in the afore-mentioned pathways were significantly dysregulated. Conclusion: Early, but not late, passage numbers of primary cells provide representative metabolic and transcript fingerprinting for investigating DD. A unique parallel analysis of transcript and metabolic profiles of DD fibroblasts and control, enabled a robust characterization of DD and correlation of parameters across the various levels of systemic description. The tools that should facilitate our understanding of these complex systems are immature, but the pleiotropy of the difference between healthy and DD tissue suggest the aetiology of a network-based disease.

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