• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 202
  • 136
  • 44
  • 24
  • 16
  • 16
  • 13
  • 11
  • 9
  • 7
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 563
  • 563
  • 90
  • 79
  • 71
  • 66
  • 49
  • 46
  • 44
  • 41
  • 41
  • 41
  • 37
  • 36
  • 36
  • 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.
121

Development of ESI-LC-MS Method for Drug Analysis

Yacoub, Kimberly 20 April 2018 (has links)
No description available.
122

Development and Validation of UPLC/MS/MS Methods for Quantification of Gangliosides in the Clinical Study of Ganglioside GM3 Synthase Deficiency

Huang, Qianyang 26 August 2016 (has links)
No description available.
123

Structural Studies of Oligosaccharides Attached to Proteins Expressed in Different Organisms and PEGylation of a non-Glycosylated Protein

Motari, Edwin Mwamba 26 August 2010 (has links)
No description available.
124

Development of saponin-rich baked goods

Serventi, Luca 21 March 2011 (has links)
No description available.
125

Molecular target identification of antimalarial drugs using proteomic and metabolomic approaches

Laourdakis, Christian Daniel 15 May 2014 (has links)
Malaria is a parasitic infectious disease that results in millions of clinical cases per year and accounts for approximately 1 million deaths annually. Because the parasite has developed resistance to all current antimalarials, new therapies are urgently needed. Purine and pyrimidine biosynthesis for DNA and RNA synthesis has been recognized as a source of therapeutic targets. Targeted metabolite profiling has aided in the understanding of several biological processes in the parasite besides drug discovery. Therefore, having a robust analytical platform to quantify the purines and pyrimidines is of a great value. For this purpose an ion pair reversed phase ultra-performance liquid chromatography in tandem with mass spectrometry method was developed and validated. In addition, the apicoplast is an organelle present in the malaria parasite and other apicomplexan parasites. It was demonstrated that the apicoplast is essential for parasite's survival. The supply of isopentenyl diphosphate and dimethylallyl diphosphate for isoprenoid biosynthesis is the sole function of this organelle in the asexual intraerythrocytic stages. Isoprenoid precursors are synthesized through the methylerythritol phosphate (MEP) pathway in the malaria parasite while humans utilize the mevalonate pathway. Therefore, the MEP pathway is a source of drug targets for drug development. Our group has identified MMV008138 as anti-apicoplast inhibitor through phenotypic screening. Preliminary data suggest that the molecular target of MMV008138 may be within the MEP pathway. We used proteomic and metabolomic approaches to identify the molecular target of MMV008138 to aid future medicinal chemistry to improve the efficacy of this inhibitor. / Master of Science
126

Validering av PFAS-mätning i jord, slam och sediment / Validation of PFAS measurement in soil, sludge, andsediment

Daher, Ghfran January 2024 (has links)
Syftet med detta examensarbete var att validera en metod som kvantitativt bestämmer PFAS ijord, slam och sediment. Valideringen omfattade en del olika tester för att utvärdera metodensrapporteringsgräns, precision, riktighet, mätosäkerhet och specificitet. Excel har använts för attberäkna och sammanställa resultaten från de olika testerna. Blankprover och spikade prover haranalyserats för att undersöka rapporteringsgräns. Kontrollprover har analyserats för attundersöka precision samt specificitet. För att undersöka riktighet har en rad olika tester utförts;ISTD-matchning för några av PFAS-analyter som saknade en direkt ISTD-match, jämförelsermot certifierat referensmaterial, analys av tidigare utförda tester som redan hade analyserats iALS Prag och spikade provmatriser. Mätosäkerheten uppskattade och utvärderades i samrådmed kvalitetsansvarig. Resultatet från metodvalideringen bekräftar att metoden har visat sig vara väl validerad.Samtliga tester som utfördes under valideringsprocessen har konsekvent uppfyllt och överträffatde ställda acceptanskriterium för valideringen. Kriterierna inkluderade bland annat relativstandardavvikelse (RSD), utbyte, bias och halt för olika testparametrar. Den omfattandemetodvalideringen gav starka bevis att metoden är tillförlitlig och kan användas för att genererapålitliga resultat inom PFAS-analys. / The purpose of this thesis was to validate a method for quantitatively determining PFAS in soil,sludge, and sediment. The validation involved a number of different tests to evaluate themethod's reporting limit, precision, accuracy, measurement uncertainty, and specificity. Excelwas used to calculate and summarize the results from the different tests. Blank and spikedsamples were analyzed to investigate the reporting limit. Control samples were analyzed toinvestigate precision and specificity. A variety of tests were performed to investigate accuracy;ISTD matching for some PFAS analytes that lacked a direct ISTD match, comparisons againstcertified reference material, analysis of previously performed tests that had already beenanalyzed at ALS Prague, and spiked sample matrices. The measurement uncertainty wasestimated and evaluated in consultation with the quality manager. The results of the method validation confirm that the method has been shown to be wellvalidated. All tests performed during the validation process have consistently met and exceededthe established acceptance criteria for the validation. Criteria included, among others, relativestandard deviation (RSD), recovery, bias, and concentration for various test parameters. Thecomprehensive method validation provided strong evidence that the method is reliable and canbe used to generate reliable results in PFAS analysis.
127

An exploratory LC-MS/MS method for quantitative analysis of acylcarnitines in whole blood originating from forensic autopsy cases / En explorativ LC-MS/MS metod för att kvantitativt analysera acylkarnitiner i helblod taget från forensiska obduktionsärenden

Peterson, Jenny January 2024 (has links)
Forensics face a complicated problem when evaluating intoxications induced by opioids and non – intoxications of opioid abusers since the in vitro concentrations of the said opioid overlap. Researchers found that acylcarnitines role as biomarkers for a diversity of diseases may also be used as biomarkers postmortem, easing the complications that occurs of evaluating the cause of death.  A reversed phase ultra high performance liquid chromatography (UHPLC) method in combination with mass spectrometer detection was developed for a quantitative analysis of different acylcarnitines in authentic blood samples. The hypothesis investigated was the altercation of acylcarnitine concentration depending on the cause of death, specifically when induced by opioids. Separation was achieved using ACQUITY UPLC HSS T3 1.8 µm (2.1 x 100 mm) Waters column along with a gradient elution consisting of Mobile phase A: 0.05% HFo in 10 mM Ammoniumformate and Mobile phase B: 0.05% HFo in Methanol. Flowrate was 0.4 mL/min. The method was validated in respect to linearity and range, accuracy, precision, LOD and LOQ as well as stability and degradation of acylcarnitines. Linearity was acceptable with R2 – values   for all the substances. Results from the authentic sample analysis showed no statistically significant difference between the investigated groups based on Kruskal – Wallis non-parametric tests and median comparison, however a trend in the data was found correlating to the investigated hypothesis suggesting it may be true.
128

Méthode d'analyse dans le miel de trois familles d'insecticides (nicotinoïdes, pyréthrinoïdes et pyrazoles) par chromatographies en phase gazeuse et en phase liquide couplées à la spectrométrie de masse en tandem. : application à l' étude de contamination de ruches. / Analytical method in honey for three insecticide families (nicotinoids, pyrethroids and pyrazoles) by gas and liquid chromatographies couplet tandem mass spectrometry. : application to study hives contamination.

Paradis, Delphine 19 October 2012 (has links)
Les différentes techniques d'extraction et d'analyse existant pour étudier les insecticides contenus dans le miel ne permettent pas toujours d'atteindre de faibles limites de détection. Or, pour évaluer la toxicité des pesticides, des valeurs de limites de détection de l'ordre du ng/g doivent être obtenues. L'objectif de ce travail a été de développer des méthodes d'extraction et d'analyse compatibles avec différents types de miels (miels de nectars et de miellats, monofloraux et multifloraux) et permettant de rechercher 25 insecticides d'intérêt appartenant à 3 familles (nicotinoïdes, pyréthrinoïdes et pyrazoles,), avec des limites de détection les plus faibles possibles et en éliminant au maximum les interférences liées à la matrice. Après comparaison de différentes méthodes d'extraction, la technique retenue est basée sur la méthode QuEChERS EN 15662, qui consiste en une extraction et une purification à l'aide de sels adaptés à la matrice et aux composés à extraire. Les analyses ont ensuite été effectuées en chromatographie en phase gazeuse couplée à la spectrométrie de masse en tandem (GC-MS²), pour les pyrazoles et les pyréthrinoïdes, et en chromatographie liquide haute performance couplée à la spectrométrie de masse en tandem (LC-MS²) pour les nicotinoïdes et un pyrazole, les réglages des appareils devant être optimisés pour permettre d'obtenir une limite de détection très basse. Les rendements d'extraction obtenus sont majoritairement compris entre 60 et 140%. Les méthodes développées sont spécifiques pour les miels testés. / Several extraction and analytical techniques existing to study insecticides in honey do not always allow reaching low limits of detection. However, to evaluate the toxicity of pesticides, values of limits of detection have to be close to 1 ng/g. The aim of this work was to develop extraction and analytical methods compatible with various types of honey (nectars and honeydews, monofloral and multifloral) and allowing to look for 25 insecticides belonging to 3 families (nicotinoids, pyrethroids and pyrazoles), with the lowest possible limits of detection and eliminating the maximum interference due to the matrix. After comparison of different extraction methods, the reserved technique is based on the QuEChERS EN 15662 method, which consists of an extraction and a purification with mixtures of salts adapted to the matrix and to the compounds to be extracted. Analysis were then performed using gas chromatography coupled with tandem mass spectrometry (GC-MS²) for the pyrazoles and the pyrethroids, and using high performance liquid chromatography coupled with tandem mass spectrometry (LC-MS²) for the nicotinoids and one pyrazole. Device settings have to be optimized to obtain a very low limit of detection. The mean extraction yields were typically between 60 and 140%. The methods are specific for tested honeys. These methods are applicable to analyze commercial honeys and allow reaching limits of detection between 0.2 and 0.7 ng/g. In practice, the dosage of these 3 families in different types of honeys, at low concentrations can be made in routine in an analysis laboratory.
129

Análise metabolômica aplicada à quimiotaxonomia de espécies do gênero Vernonia sensu lato (Vernonieae) / Metabolomics analysis applied to chemotaxonomic study of species from Vernonia sensu lato (Vernonieae)

Gallon, Marília Elias 31 May 2017 (has links)
Vernonia sensu lato é um dos maiores e mais complexos gêneros da tribo Vernonineae. A tribo pertence a família Asteraceae, a qual representa cerca de 10% da flora mundial e é considerada uma das maiores famílias dentre as plantas superiores. As espécies da tribo Vernonineae apresentam distribuição pantropical e são caracterizadas pela presença de lactonas sesquiterpênicas e flavonoides (principalmente flavonas e flavonóis). Ao longo dos anos, diversas classificações têm sido propostas para o gênero Vernonia s.l., porém ainda não há um consenso entre os pesquisadores. Nas classificações mais antigas, o gênero Vernonia s.l. inclui cerca de 1000 espécies (sensu Baker), distribuídas em seções e subseções; em uma divisão mais atual, essas espécies foram segregadas em vários novos gêneros e o gênero Vernonia, nas Américas, foi consideravelmente reduzido (sensu Robinson), ficando restrito a espécies distribuídas principalmente na América do Norte. Neste estudo, foram realizadas análises metabolômicas e estatísticas de espécies do gênero Vernonia s.l., pertencentes às subtribos Vernoniinae, Lepidaploinae e Rolandrinae, com o intuito de verificar se a abordagem metabolômica pode ser utilizada como uma ferramenta quimiotaxonômica e auxiliar nas classificações taxonômicas do gênero. A partir das impressões digitais metabólicas obtidas por UHPLC-UV-MS, foram realizadas análises estatísticas não-supervisionadas (HCA e PCA) e supervisionadas (OPLS-DA). A análise por HCA permitiu a identificação de quatro grupos principais, os quais sugerem que as espécies apresentaram tendência em se agruparem de acordo com os gêneros criados por Robinson. Além disso, observou-se que as espécies dos gêneros Stenocephalum, Stilpnopappus e Rolandra (Grupo 1) estão relacionadas às espécies do gênero Vernonanthura (Grupo 2), enquanto que as espécies dos gêneros Chrysolaena, Cyrtocymura e Echinocoryne (Grupo 3) estão relacionadas às espécies dos gêneros Lessingianthus e Lepidaploa (Grupo 4), indicando que as subtribos Vernoniinae e Lepidaploinae são parafiléticas. Diversos metabólitos foram identificados nas espécies analisadas, destacando-se os ácidos clorogênicos, os flavonoides e as lactonas sesquiterpênicas. Através da análise por OPLS-DA foi possível determinar os metabólitos responsáveis pela separação entre os grupos obtidos na análise por HCA. As espécies do Grupo 1 foram caracterizadas pela ausência de ácido 3-O-cafeoilquínico e 3,5-di-O-cafeoilquínico; o Grupo 2 foi caracterizado pela ausência de quercetina e presença de kaempherol 3-O-rutinosídeo; o Grupo 3 foi o único grupo no qual não foi identificado o flavonoide 7,3?,5?-trihidroxi- 4?-metoxi-3-O-glicosilflavona e as espécies do Grupo 4 caracterizaram-se por apresentarem baixa prevalência de flavonas. Dessa maneira, as análises metabolômicas em conjunto com análises estatísticas multivariadas auxiliaram no esclarecimento da classificação taxonômica das espécies do gênero Vernonia s.l. e permitiram a identificação de potenciais marcadores quimiotaxonômicos / Vernonia sensu lato is one of the largest and more complex genus of the tribe Vernonineae. The tribe belongs to Asteraceae, one of the largest families of flowering plants. Vernonineae is distributed widely in tropical and subtropical regions of America, Africa and Asia and it is chemically characterized by the presence of sesquiterpene lactones and flavonoids (flavones and flavonols). Over the years, several taxonomic classifications have been proposed for the genus Vernonia s.l., however there has been no consensus among the researches. According to the traditional classification, the genus Vernonia s.l. comprises more than 1000 species and it is divided into sections and subsections (sensu Baker). In a recent classification, these species have been segregated into new genera, while the genus Vernonia sensu stricto was restricted to 22 species distributed mainly in North America (sensu Robinson). In this study, species belonging to the subtribes Vernoniinea, Lepidaploinae and Rolandrinae were analysed, employing UHPLC-UV(DAD)-MS(Orbitrap), followed by multivariate analyses. Data mining was performed using unsupervised (HCA and PCA) and supervised statistical analysis (OPLS-DA). The HCA showed segregation into four main groups. Comparing the HCA with the taxonomical classifications, we observed that the groups of the dendogram were in accordance with the genera created by Robinson. The species of the genera Stenocephalum, Stilpnopappus and Rolandra (Group 1) are more related with the species of the genus Vernonanthura (Group 2), while the genera Cyrtocymura, Chrysolaena and Echinocoryne (Group 3) are chemically more similar to the genera Lessingianthus and Lepidaploa (Group 4). These findings indicate that the subtribes Vernoniinae and Lepidaploinae are paraphyletic groups. Several metabolites were identified, highlighting chlorogenic acids, flavonoids and sesquiterpene lactones. ). According to OPLS-DA loading plot, it was possible to determine which variables are important for the discrimination among the groups. The species of the Group 1 were characterized by the absence of 3-O-caffeoylquinic acid and 3,5-di-O-caffeoylquinic acid. Group 2 was characterized by the absence of quercetin (flavonol with free OH) and by the presence of kaempherol 3-O-rutinoside. Group 3 was the only group that do not show the flavonoid 7,3?,5?-trihydroxy-4?- methoxy-3-O-glycosylflavone. The species of the Group 4, especially the species of the genus Lessingianthus, were characterized by the low prevalence of flavones. Therefore, untarget metabolomic approach associated with mutivariate analysis allowed the identification of potential chemotaxonomic markers, helping in the taxonomical classifications
130

Determinação de fármacos em mananciais do estado de São Paulo e estudo da sua ecotoxicidade sobre a cianobactéria Microcystis aeruginosa / Pharmaceuticals determination in São Paulo stare springs and evaluation of their toxicity in cyanobacterium Microcystis aeruginosa

Souza, Raquel Cardoso de 12 December 2017 (has links)
A contaminação de corpos d\'água por fármacos é um tema de extrema relevância, tendo em vista problemas como a escassez de água, florações de cianobactérias tóxicas e lançamentos clandestinos de efluentes domésticos. Sendo assim, este trabalho teve como objetivo determinar a presença de cafeína (CAF), fluoxetina (FLX), levotiroxina (LVX) e bezafibrato (BZF) em mananciais do estado de São Paulo, bem como avaliar a toxicidade desses compostos à cianobactéria Microcystis aeruginosa LTPNA 08. Um método por LC-MS/MS foi desenvolvido e validado, de acordo com a RDC nº 166 da ANVISA, para a detecção de CAF, FLX, LVX e BZF em amostras ambientais. As represas Guarapiranga e Billings, bem como os rios Taiçupeba, Sorocaba, Baixo Cotia, Grande e Paraíba foram monitorados de abril a setembro de 2017. A toxicidade dos fármacos foi avaliada por meio do monitoramento do crescimento, produção de microcistinas e viabilidade celular da cianobactéria M. aeruginosa LTPNA 08. CAF foi detectada em todas as amostras analisadas, com concentrações que variaram de 6,6 ng.L-1 a 16,47 µg.L-1. No Rio Cotia foram verificadas as maiores concentrações de CAF, FLX e BZF (16,47 µg.L-1; 3,5 ng.L-1 e 322 ng.L-1, respectivamente). A LVX, cujos produtos de biotransformação não foram monitorados, não foi detectada em nenhuma amostra analisada. A concentração de 50 µg.L-1 de FLX inibiu o crescimento da cianobactéria em 82,3% (CE50: 31,4 µg.L-1). Em relação à produção de microcistinas totais, os fármacos inibiram a liberação da fração extracelular para a maior concentração testada ao longo do tempo de monitoramento, embora não tenham demonstrado efeito sobre a viabilidade celular. Sendo assim, considerando-se que fármacos estão presentes nos mananciais monitorados no estado de São Paulo e que a FLX pode causar efeito sobre a M. aeruginosa, os efeitos decorrentes da exposição a concentrações ambientais contínuas e cumulativas de fármacos em corpos d\'água devem ser estudados. Além disso, uma vez que a ocorrência destas substâncias e outros contaminantes antropogênicos no ambiente aquático natural é uma questão emergente devido aos efeitos adversos potenciais que estes compostos representam para a vida aquática e os seres humanos, os tipos e níveis destes compostos, que têm um impacto maior na qualidade da água, deve ser constantemente monitorada. Práticas de gestão que investem em saneamento e na redução da descarga de efluentes não tratados, e um plano de proteção de recursos hídricos com o objetivo de garantir a segurança da água seriam medidas essenciais para reduzir o aporte de contaminantes nos corpos d\'água do estado de São Paulo. / Contamination of water bodies by drugs is a subject of extreme relevance considering related problems such as water scarcity, harmful cyanobacterial blooms and discharge of untreated domestic effluents. Therefore, the aim of this work was to determine the presence of caffeine (CAF), fluoxetine (FLX), levothyroxine (LVX) and bezafibrate (BZF) in springs in the State of São Paulo, and to evaluate the toxicity of these compounds in cyanobacteria Microcystis aeruginosa LTPNA 08. A LC-MS/MS method was developed and validated according to RDC nº 166 of ANVISA to assess the concentration of CAF, FLX, LVX and BZF in environmental samples. Guarapiranga and Billings reservoirs, as well as the Taiçupeba, Sorocaba, Baixo Cotia, Grande and Paraíba rivers were monitored from April to September 2017.The drugs toxicity in M. aeruginosa LTPNA 08 was assessed by monitoring their effects on cyanobacterial growth, microcystins production and cell viabilityby flow cytometry. CAF was detected in all analyzed samples at concentrations ranging from 6.6 ng to 16.47 µg.L-1.Among studied sites, Cotia river showed the highest concentrations of CAF, FLX and BZF (16.47 µg.L-1, 3.5 ng.L-1 and 322 ng.L-1, respectively). LVX, which biotransformation products were not monitored, was not detected in any of the analyzed samples. Regarding the drugs toxicity, 50 µg.L-1 of FLX inhibited the cyanobacterial grow thin 82.3% (EC50 of 31.4 µg.L-1). Although no effect on cell viability was seen by flow cytometry, the highest concentrations of all compounds tested were able to inhibit the release of microcystins. Therefore, considering that some of the drugs monitored showed to be present in water sources in São Paulo State and that FLX affects cyanobacteria M. aeruginosa growth, the effects of continuous and cumulative exposure at environmental drug concentrations of in water bodies should be evaluated. Also, since the occurrence of these substances and other anthropogenic contaminants in the natural aquatic environment is an emerging issue due to the potential adverse effects these compounds pose to aquatic life and humans, thet ypes and levels of these compounds, which have a greater impact on water quality, should be constantly monitored. Management practices investing in sanitation and in reducing discharge of untreated effluents, as well as a plan for water resources protection with the goal of ensuring water security would be essential measures in reducing drugs loading into water bodies situated in São Paulo State.

Page generated in 0.0304 seconds