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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.
411

Polysaccharide Materials and Sorption Studies of Chloroform and Total Trihalomethanes (TTHMs) in Aqueous Solution

2013 March 1900 (has links)
In this research, a series of synthetically engineered copolymers were synthesized containing polysaccharides (e.g., β-cyclodextrin and chitosan) to address the removal of trihalomethanes (THMs) from water environments. There are two main parts in this research thesis: i) the preparation and characterization of polysaccharide-based copolymers; ii) sorption studies of the copolymers with chloroform and total THMs (TTHMs) in aqueous solution. In the first part of this thesis, grafted polyester, polyester and grafted polyamide copolymers were prepared by cross-linking β-cyclodextrin (β-CD) and chitosan (CS) with various cross-linkers, including poly (acrylic acid) (PAA), terephthaloyl (TCl), and sebacoyl chloride (SCl), respectively. The synthesized copolymer materials were characterized by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), elemental (C and H) analyses, and NMR spectroscopy. Nitrogen porosimetry was used to analyze the surface area and pore structure characteristics of the copolymers and starting materials in solid state. The sorption properties of the copolymers in aqueous solution were studied using different dye probes (e.g., p-nitrophenol and methylene blue) by UV–Vis spectrophotometry. The copolymers showed markedly varied interactions with dye probes in accordance with their composition, surface area, and pore structure characteristics. Diverse materials were afforded by variation of the synthetic conditions. The sorption isotherms were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area and the sorption capacity for various copolymers in aqueous solution. The copolymer sorbents display tunable physicochemical properties according to the synthetic conditions. In the second part of this thesis, the direct aqueous injection (DAI) method with gas chromatography (GC) with electron capture or electrolytic conductivity detectors (ECD) enabled quantitative detection of chloroform and TTHMs in water. A preliminary adsorption study and kinetic study of chloroform provided the information to establish the experimental protocol for the sorption study. The sorption parameters were evaluated using the Sips model. The sorption capacity (Qm) values of chloroform for these synthetically engineered copolymers at similar conditions ranged from 0.00335-1.70 mmol/g. The relative ordering of the Qm values was observed: β-CD/PAA 1:5 > SCl-5 > SCl-10 ~ CP-1 > β-CD/PAA 1:10 > CP-5 > AC > β-CD/PAA 1:5 at high mixing speed. An extension of the sorption study for copolymers toward the multi-component THMs in water was carried out. The copolymers showed distinct adsorption capacities to THMs: chloroform (0.0485-0.287 mmol/g); DBCM (0.0712-0.277 mmol/g); BDCM (0.0684-0.387mmol/g); and bromoform (0.0522-1.07 mmol/g). The copolymers exhibited relatively high selectivity toward individual components of THMs due to their variable molecular size and polarizability. The copolymers showed favorable adsorption (e.g., β-CD/PAA 1:5, CP-1) and each type of polysaccharide (e.g., β-CD and CS) copolymers displays great potential for the removal of halomethane-based contaminants.
412

Function of M4 protein in vitro and in vivo

Wang, Xuan January 2013 (has links)
Herpesviruses are ubiquitous in both humans and animals and can cause life-threatening disease. The discovery of murine gammaherpesvirus 68 (MHV-68), which has many similarities in genome and pathogenesis as the human pathogens Epstein-Barr virus and Kaposi’s sarcoma-associated herpesvirus, provides a model for further investigation of the pathogenesis of gammaherpesviruses. The M4 gene was found to be at the left end region of MHV-68 genome. The presence of the M4 protein is required during the early establishment of MHV-68 latency. However, the function of M4 protein remains unclear. The aim of this project was to investigate the function of the M4 protein in vitro and during infection. By using an ELISA, the recombinant M4 protein was shown to bind several Cxc-chemokines and stop the interaction between Cxcl4 and GAGs. The role of M4 protein during MHV-68 lytic infection and in the early establishment of latency was studied by comparing the pathogenesis of virus which does not express M4 (M4stop) and wild type virus (WT). Compared to WT infection, this study found that M4stop was decreased in the lungs at day 8 post infection (p.i.). At the same time point, the viral loads were higher in M4stop infected spleens, which was accompanied by increased expression of the CD4+ T cell activation marker PD-1 and the macrophage activation marker CD69. However, at day 14 p.i., the M4stop infected spleens had lower viral loads, and the expression of CD69 was decreased on CD4+, CD8+ T cells, B cells and macrophages. Furthermore, gene expression PCR arrays were used to investigate how cellular activation and inflammation were transcriptionally regulated. It has been found that the transcription of several genes, which are involved in germinal centre development, was lower in the spleens of WT infected mice at day 12 and 14 p.i. compared to day 10 p.i. of WT infection, as well as day 12 and 14 p.i. of M4stop infection. In addition, the percentage of germinal centre B cells was found to be higher in spleens infected with M4stop at day 10 p.i.. However, there was no difference in percentages of TFH and plasma cells in the spleens. Finally, in order to understand the role of IFN-γ in control of infection in M4stop infected mice, IFN-γR-/- mice were infected with M4stop and WT. Although there were differences in pathogenesis between WT and M4Stop virus infected IFN-γR-/- mice, there was no clear evidence that M4 function is involved in inhibiting IFN-γ pathways. In this study, we found M4 can disturb the interaction of chemokine and GAGs and might delay virus trafficking to the spleen, which could lead to a reduction of cellular activation. M4 may also impair the development of germinal centres at the beginning of latent infection in the spleens.
413

Novel Solid-Phase Extraction Techniques for Biological and Environmental Analysis Using Isotope Dilution Mass Spectrometry

Boggess, Andrew 18 May 2016 (has links)
Awareness and study of the ways in which the environment can interact with the personal genetics and epigenetics of an individual has grown substantially in recent years, resulting in the field of Exposomics. In an era of increasingly personalized medicine, novel techniques are necessary to ensure the accurate and sensitivity measurement of clinically and environmentally relevant molecules in biological and environmental samples. Addressing existing shortcomings cited in literature, methods were developed and optimized for the extraction, separation, mass analysis, and quantification of a suite of environmental organic pollutants in both biological and environmental samples, with the primary objective of improving accuracy, increasing sensitivity, and reducing sample and reagent consumption. The secondary objective of this research was the production of validated methods capable of inter-laboratory method transfer with minimal training required in the receiving laboratory. Two novel methods have been developed, optimized, validated, and applied to collaborative environmental research. These novel methods represented a demonstrative improvement upon existing methods in both analytical quality and capability for inter-laboratory method transfer. Both developed methods were utilized in two collaborative clinical research studies investigating the impact of environmentally-sources agents on children diagnosed with autism spectrum disorders (ASD). The high-quality data obtained in these studies yielded results that may have provided valuable insight into the development and maintenance of autism spectrum disorders. These novel methods allowed for the discovery of a first-of-its-kind variable in the children with ASD, compared with controls. This variable was statistically predictive for the probability of an individual being diagnosed with the most behaviorally severe autism disorder, with a statistically significant overall model fit. This novel analytical method was then expanded in breadth through application to industrial and municipal wastewater to aid in updating EPA Method 625 for wastewater analysis. Applying this novel method to wastewater produced data of higher analytical quality, in both accuracy and precision, compared with all other collaborative laboratories. The methods developed in this work for the quantification of organic molecules implicated in environmental human health in biological and environmental samples have significantly improved analytically upon existing methods and have yielded clinically relevant findings in collaborative clinical research studies. / Bayer School of Natural and Environmental Sciences; / Chemistry and Biochemistry / PhD; / Dissertation;
414

Application of Solid Phase Micro-Extraction (SPME) - GC-MS for Identifying Pyrolysis Compounds in Textiles

Bradford, Brock 20 September 2016 (has links)
This thesis project describes research using headspace solid phase micro-extraction with gas chromatography (HS-SPME GC-MS) as an analytical tool for assessing textile fibres. It was found that this method required a temperature of >500oC to pyrolize the textile sample. A total of 5 minutes was determined to be the optimal time for collecting the volatile analytes. Numerous analytes were found to be chemical markers for each of the individual textile fibres. The chemical markers are qualitatively used to describe each textile uniquely, and it was found that by using the chromatographic patterns, the textiles could be identified individually and in mixtures containing two textiles. Lastly, by accelerating the age of the textile fibres by means of heat, ultra-violet light, and humidity, a comparison was made between the un-aged and aged fibres. It was found that each of the techniques arose different results and in some cases new compounds. / October 2016
415

Speciation analysis of trace metals in natural waters using vibrating electrodes

Bi, Zhaoshun January 2012 (has links)
The speciation of trace metals plays a very important role in conditioning their biogeochemical cycles in the marine system. Their species are found to be strongly related to organic matters such as humic acids (HA) and fulvic acids (FA). This thesis aims to develop appropriate techniques to improve our understanding of the speciation of some trace metals, mainly in marine waters. Lead (Pb), cadmium (Cd) and chromium (Cr) which are widely used in industry were analytzed. The concentration of lead in uncontaminated seawater is between 10 and 100 pM, whilst in coastal waters it is higher at up to low nanomolar levels. Little is known about the chemical speciation of lead since it is difficult to be determined at picomolar levels. The work in this dissertation was to develop a suitable electrode and procedure to determine lead in seawater, with the objective that the electrode could be applied for in-situ measurement (without reagents) and for speciation. Several electrodes and materials were tested, including a solid bismuth rod and different microwire materials. Vibration was used to enhance mass transport, instead of solution stirring, to decrease detection limits and facilitate in-situ monitoring. The bismuth electrode was found to be suitable for monitoring lead in coastal waters: it is mercury-free and therefore environmentally friendly, but insufficiently sensitive for oceanic lead concentrations. Comparison of microwires of carbon, gold and silver showed that all of these bare electrodes give a signal for lead, but they suffer variable interference from cadmium, although this is minor if the cadmium concentration is lower than lead. A large improvement was obtained by coating the electrodes with mercury, which gave good peak resolution between cadmium and lead, and good sensitivity. The carbon and gold electrodes had good reproducibility and sensitivity when the mercury was renewed for each measurement. Once coated with mercury, the silver electrode formed amalgam with the silver which could not be completely removed. This electrode was thus not suitable to be used as a renewable mercury film electrode. However, as a permanently amalgamated silver electrode, it was found to have good sensitivity for lead, good separation from cadmium, and was stable for long time usage. This electrode, the silver amalgam microwire (SAM) electrode, was selected for further speciation study of Pb in oceanic waters. Optimum conditions for using the SAM electrode for trace lead detection in seawater involve the use of conditioning potentials. The limit of detection for lead was 4 pM lead in acidified seawater and 12 pM lead in seawater of pH 8. The higher limit of detection at pH 8 is due to the inorganic speciation at that pH. The SAM electrode was successfully used for pseudopolarography of lead to determine its organic complexation. This method was calibrated using model compounds and applied for the first time to estuarine, coastal and oceanic samples at natural concentrations of Pb. It was found that lead occurs mostly as a labile (reactive, organic) species, with a smaller fraction as a strongly organically bound species. The SAM electrode was also tested for chromium analysis using cathodic stripping voltammetry (CSV) in natural waters. Its detection limit is as good as the mercury drop electrode but reduces consumption of mercury.
416

Entwicklung und Anwendung von Methoden zur Erfassung von Pyrrolizidinalkaloiden in Honig und Pollen / Development and application of methods for the analytical determination of pyrrolizidine alkaloids in honey and pollen

Kempf, Michael January 2009 (has links) (PDF)
In jüngster Vergangenheit hat die potentielle Belastung von Lebens- und Futtermitteln mit PA wiederholt Aufmerksamkeit erregt. Eine Exposition des Menschen mit PA kann über den Genuss von Tees, Phytopharmaka, pflanzlichen Lebensmitteln (z.B. Salatmischungen) oder, im Fall einer Verfütterung von PA-Pflanzen an Tiere, als sekundäre Kontamination über tierische Lebensmittel erfolgen. Im ‚International Programme on Chemical Safety (IPCS)’ der WHO ist die grundsätzliche Gefährdung der menschlichen Gesundheit durch PA dokumentiert. Aus Gründen des vorbeugenden Verbraucherschutzes gibt es demzufolge Rechtsvorschriften zur Regulierung PA-haltiger Phytopharmaka. Für diese gilt in Deutschland seit 1992 ein Grenzwert von 1 µg PA/Tag für 1,2-ungesättigte PA und deren N-Oxide bei oraler Aufnahme und einer Anwendungsdauer von max. 6 Wochen. Geht die Anwendung darüber hinaus, beträgt der Grenzwert 0,1 µg PA/Tag. Im ersten Teil der Arbeit wurde eine robuste, reproduzierbare und selektive analytische Methode basierend auf Zink-Staub-Reduktion, Festphasenextraktion (SCX-SPE), LiAlH4 Reduktion mit anschließender Silylierung sowie Kapillargaschromatographie-Massenspektrometrie (HRGC-MS)-Analytik erarbeitet. Durch ein solches Vorgehen werden die PA-N-Oxide in tertiäre PA überführt, so dass alle PA in ihrer tertiären Form vorliegen. Durch die anschließende chemische Reduktion werden alle Mono- und Diester-PA in die jeweiligen Necinbasen überführt. Durch die anschließende Derivatisierung zum di-TMS-Derivat, konnten über den Summenparameter Retronecin PA-Kontaminationen mit 1,2-ungesättigten PA-Strukturen verlässlich detektiert und hochselektiv mittels HRGC-MS im SIM-Modus angezeigt werden. Die Validierung der Methode erfolgte durch die Verwendung von Senecio vernalis-Extrakt sowie authentischen PA-Standards und deren N-Oxiden. Unter Modifikationen der Probenaufarbeitung war diese Methode sowohl für Honig und Pollen, als auch für honighaltige Lebensmittel einsetzbar. Im weiteren Verlauf der Arbeit wurde die Methode durch die Synthese des deuterierten Standards di-Butyroyl-[9,9-2H2]-Retronecin zur Stabilisotopen-Verdünnungsanalyse (SIVA) erweitert und optimiert. Die entwickelte Methode erlaubt erstmals, anders als bei bereits vorliegenden Arbeiten zur Bestimmung von PA in Pflanzenteilen, eine exakte und selektive Bestimmung von PA im Spurenbereich, unabhängig von deren botanischem Ursprung oder chemischer Struktur (tertiäres PA, N-Oxide). In einem breit aufgestellten Screening von 216 Honighandelsproben und 35 Forschungshonigen – letztere umfassten 27 Senecio- und 8 Echium-Honige - konnten zum Teil erhebliche Mengen an PA nachgewiesen werden. Die Belastungsrate der einzelnen Probensets reichte von 9 bis zu 100%. Die hierbei ermittelten Gehalte lagen, berechnet als Retronecin-Äquivalente, zwischen 0,019 µg/g und 4,66 µg/g. Ergänzt wurden die analytischen Daten durch die Erhebung von mellisopalynologischen Daten. Hierbei zeigte sich, dass eine Bestimmung von PA-Pflanzenpollen über die relative Pollenhäufigkeit nach DIN 10760 nur eine geringe Aussagekraft bei der Riskioabschätzung besitzt. Zwar war die Anwesenheit von PA-Pflanzenpollen immer ein Indikator für das Vorkommen von PA, jedoch konnten über den relativen Pollengehalt keine Aussagen über die Höhe der PA-Belastung getroffen werden. In einer weiteren Studie zu PA-Gehalten in Pollen und Pollenerzeugnissen sind in den nativen Pollen die erwartet hohen PA-Gehalte bestätigt worden. Aber auch die in Vollsortimentsupermärkten und Reformhäusern häufig vertretenen Pollenprodukte wiesen PA-Gehalte auf, die im Mittel weit über den bei Honig festgestellten Werten lagen. So ergaben sich für die nativen Pollen aller bedeutenden, PA-produzierenden Pflanzenfamilien PA-Gehalte von 0,57-4,07 mg/g, während sich für die Pollenprodukte Gehalte von 1,08-16,35 µg/g feststellen ließen. Eine zusätzliche Erhebung von mellisopalynologischen Daten bestätigte deren bereits bei den Honigproben festgestellte, eingeschränkte Aussagekraft hinsichtlich des PA-Gehaltes. Durch ein Screening von 60 honighaltigen Lebensmitteln mit unterschiedlichen Honiganteilen konnte eine potentielle Downstream-Kontamination durch den Einsatz von hoch PA-belasteten Honigen im Herstellungsprozess nachgewiesen werden. Bei einer Belastungshäufigkeit von 13% lagen die hierbei ermittelten PA-Gehalte, berechnet als Retronecin-Äquivalente, bei 0,010-0,484 µg/g. Abschließend ist in modellhaft durchgeführten Filtrationsversuchen gezeigt worden, dass PA-Pflanzenpollen erheblichen Einfluss auf den PA-Gehalt des Honigs ausüben. Dennoch stellt eine Honigfiltration, wie sie in Anlage 1 der Honigverordnung zulässig ist, keine Möglichkeit dar, hoch mit PA belasteten Honig im PA-Gehalt zu senken. Vielmehr ließ sich mit den durchgeführten Versuchen eine Diffusion der PA aus Pollen in den Honig nachweisen. / Recently, the potentially PA contamination of food and feeding stuff attracted high attention. Humans are exposed to these toxins by comsumption of herbal medicine, herbal teas, dietary supplements or food containing PA plant material. In the ´International Programme on Chemical Safety (IPCS) the WHO states the potential threath to human health by PA. In pharmaceuticals, the use of these plants is regulated by the German Federal Health Bureau to a total PA intake of 1 µg per day for 1,2-unsaturated PA and their N-oxides within a six-week period per year, or, if six weeks are surpassed, the level is reduced to 0.1 µg total PA content per day. With regard to food the DFG-Senate Commission on Food Safety (SKLM) passed an opinion that […] The existing data base dealing with the content of PAs in honey collected from PA-containing plants […] as well as the data base dealing with the exposure of consumers to PAs are judged to be inadequate […]. Furthermore, they reminded that […] The main goal of future research should be the careful analytical determination of the PA content of honey and pollen […]. Initiated by this, the essential intention of this work was to develop a reliable tool for selective and quantitative determination of PA in the relevant range of concentration at ≤ 0,1 ppm in this food. Furthermore, the generation of a broad dataset should be the basis for the estimation of the potential risk of PA. First of all, a robust, reproducable and selective method consisting of Zn-dust reduction, strong cation exchance solidphase extraction (SCX-SPE), chemical reduction with LiAlH4, subsequent silylation and capillary gas chromatography-mass spectrometry (HRGC-MS) using SIM mode was established. This procedure converted PA-N-oxides into their basic tertiary form and, due to the subsequent chemical reduction, all mono- and diester PA resulted in their particular necine backbones. The newly developed method represented a reliable tool to detect potential PA contamination with toxic 1,2-unsaturated PA structures using retronecine as sum parameter by capillary gas chromatography-mass spectrometry (HRGC-MS) in SIM mode. This procedure was validated using extracts of Senecio vernalis as well as authentic standards of PA and their N-oxides. This method was applicable to honey and, after some modifications, to pollen and honey-containing foods, respectively. Furthermore, the analytical method was optimised by synthesis of a deuterium labelled standard, di-Butyroyl-[9,9-2H2]-retronecine, used for stable isotope dilution assays. For the first time, the present method allows the exact and selective determination of toxic PA by simply detecting a sum parameter which contains the toxic principle of the PA (1,2-double bond), independently from botanical origin or the oxidation state of the PA (tertiary PA, N-oxides). The method was applied to 216 commercially available flower honey samples and 35 exploratory harvested honeys, comprising 27 Senecio- and 8 Echium-honeys. Among these honeys the contamination degree was between 9 and 100% and the measured PA content was in a range from 0.019 to 4.66 µg g-1, calculated as retronecine equivalents. These results were completed by mellisopalynological data, performed according to DIN 10760. In this context, only a marginal significance between identification and relative frequency of PA plant pollen and the amount of PA contamination could be proven. The presence of PA plant pollen can rather be a precursor for a presence of PA. In a further study, the expected high amounts of PA in pure, floral pollen were verified. Furthermore, pollen products, available as food supplements in various supermarkets and health food shops, showed a much higher PA contamination compared to honey. Within the pure, floral pollen of the major PA producing plant families showed a PA contamination of 0.57 to 4.07 mg g-1. The analysed pollen products revealed PA contaminations in a range of 1.08 to 16.35 µg g-1. An additional data acquisition of mellisopalynological data showed similar results referring the PA levels as it did within the honey samples. Additionally, the modificated method was applied to 60 honey-containing foods with various contents of honey. Thereby a downstream contamination caused by the usage of honey highly contaminated with PA could be proven. Among these foods the degree of contamination was about 13% and the products revealed PA contents in a range of 0.010 to 0.484 µg g-1. Finally, it could be proven by filtration experiments in a bench-scale model, that pollen of PA producing plants have a direct effect on the PA content in honey. Nevertheless, it is not possible to reduce the PA contamination in honey by filtration of the contaminated honey as it is allowed by the German honey-concerning legislation. In fact, PA diffuse from pollen to honey.
417

Metabolomanalytik antiinfektiv wirkender Isochinolinalkaloide / Metabolome analysis of antiinfectiv isoquinoline alkaloids

Rikanovic, Carina January 2011 (has links) (PDF)
Die zunehmende Entstehung von Resistenzen macht die Entwicklung neuer potenter Wirkstoffe zur Therapie von Infektionskrankheiten immer wichtiger. Dieser Aufgabe stellt sich auch der interdisziplinär aufgebaute SFB 630, in den sich die vorliegende Arbeit eingliedert. Innerhalb des SFBs wurden Isochinolinalkaloid-Derivate (IQs) synthetisiert, die aktiv gegen verschiedene Mikroorganismen sind. Bioinformatische Modellierungen bilden die für den jeweiligen Mikroorganismus spezifischen Stoffwechselwege ab. In Netzwerkanalysen können Änderungen metabolischer Flüsse durch pharmakologisch aktive Substanzen vorhergesagt werden. Gemeinsam mit bioinformatischen Modellen liefern die Metabolommessungen Hinweise auf mögliche Wirkmechanismen. Im Rahmen der vorliegenden Arbeit wurden verschiedene analytische Methoden etabliert, um antiinfektive Wirkungen dieser verheißungsvollen Leitstrukturen auf das Metabolom verschiedener Mikroorganismen zu untersuchen. Die aus den Metabolommessungen erhaltenen Daten fließen in diese Modelle ein und tragen zu deren Optimierung bei. Die Mikroorganismen wurden für die Metabolomanalysen mit aktiven IQs (für S. aureus und C. albicans GB-AP-143, für L. major GB-AP-304) inkubiert. Bei C. albicans erfolgte die Probennahme zu unterschiedlichen Zeitpunkten (lag-, log-, stationäre Phase), um auch die Zeitabhängigkeit der Effekte zu untersuchen. Zusätzlich dienten bei C. albicans als Kontrollen neben parallel angesetzten Zellkulturen ohne Inhibitor, auch Zellkulturen, denen das Lösungsmittel DMSO zugegeben wurde. Es wurden Extraktionsmethoden für die betreffenden Metabolite der hier untersuchten Mikroorganismen (S. aureus, C. albicans, L. major) etabliert. Dabei lag der Fokus auf polaren Metaboliten, da bioinformatische Modellierungen für die Effekte der IQs Änderungen vor allem im Purin- und Pyrimidinstoffwechsel der Mikroorganismen vorhersagten. Zur Analyse des Nukleotidstoffwechsels wurde eine ionenpaarchromatographische HPLC-Methode entwickelt und optimiert. Mit dieser Methode konnten Nicotinamidderivate und Nukleotide des Purin- und Pyrimidinstoffwechsels in Zellextrakten von S. aureus, C. albicans und L. major quantifiziert werden. Für eine Analyse des Wirkmechanismus von GB-AP-143 wurde die Zusammensetzung des Metaboloms von C. albicans mittels einer GC/MS-Methode bestimmt. Nach einer Derivatisierung des Extrakts mit Methoxyamin-HCl und MSTFA konnten in einem Lauf zugleich Target- und Fingerprintanalytik durchgeführt werden. Die Auswertung der Targetanalytik fand unter Anwendung der NIST-Datenbank und Vermessung von Standards statt. Hierbei konnten vor allem Aminosäuren quantitativ erfasst werden. Der Fingerprint wurde durch Einsatz multivariater statistischer Verfahren ausgewertet. Die Daten für die mit GB AP 143 behandelten S. aureus und die mit GB AP 304 behandelten L. major-Promastigoten liefern Hinweise auf eine Wirkung der IQs auf den Komplex-I der mitochondrialen Atmungskette. Für die Behandlung der C. albicans-Kulturen mit GB-AP-143 konnten komplexe Änderungen im Nukleotid- und Aminosäurestoffwechsel gemessen werden. So beeinflusste bereits der Zeitpunkt der Probennahme (lag-, log- oder stationäre Wachstumsphase) die Zusammensetzung des Metaboloms und auch das Lösungsmittel, das für die IQs verwendet wurde, verursachte komplexe Änderungen im Metabolom von C. albicans. Zusätzlich wurden Nukleotid- und Aminosäurekonzentrationen Fluconazol-resistenter C. albicans-Mutanten (TAC, UPC und MRR) untersucht. Im Nukleotidstoffwechsel waren sowohl Konzentrationssteigerungen als auch ein Absinken der Konzentrationen im Vergleich zum Wildtyp zu verzeichnen. Der Aminosäurestoffwechsel zeigte insgesamt einen verminderten Gehalt an Aminosäuren der Mutanten gegenüber dem Wildtyp. Da GB-AP-143 auch Aktivität gegen diese Mutanten zeigte, wurde exemplarisch die MRR-Mutante mit GB-AP-143 inkubiert, um zu untersuchen, ob die durch GB-AP-143 hervorgerufenen Änderungen im Nukleotid- und Aminosäurestoffwechsel ähnlich zu denen des Wildtyps sind. Es konnten im Nukleotidstoffwechsel gegenläufige Effekte für die Inkubation von GB-AP-143 des Wildtyps und der Mutante verzeichnet werden. Die Daten aus den HPLC/UV- und GC/MS-Messungen werden von der Bioinformatik zur Optimierung der verwendeten Modelle genutzt, um auf diese Weise die Wirkmechanismen der IQs besser modellieren zu können. Da das Cytochrom-P-450-Enzymsystem am Metabolismus von etwa 95 % aller Arzneistoffe beteiligt ist, wurden die Effekte ausgewählter IQs auf die sechs wichtigsten arzneistoffmetabolisierenden Enzyme (CYP1A2, 2C8, 2C9, 2C19, 2D6 und 3A4) mit Hilfe eines bereits etablierten CYP-Assays analysiert und näher charakterisiert. Im CYP-Assay zeigte sich für drei IQs eine CYP2D6-Hemmung. Die ausgeprägte CYP2D6-selektive Hemmung von GB-AP-110 ergab einen IC50-Wert von nur 109 nM. Die Charakterisierung der Hemmung ergab einen reversiblen, kompetitiven Inhibitionsmechanismus. / The increasing frequency of resistance towards antibiotics in the therapy of infectious diseases highlights the importance of the development of novel drugs against infectious diseases. This work is integrated in the Collaboration Research Center 630 (SFB 630), which has been formed to search for innovative solutions by joint interdisciplinary approaches. In the framework of this SFB, some new isoquinoline alkaloid derivatives (IQs) could be synthesized, which show distinct activities against various microorganisms. The present work focussed on the development of different analytical methods in order to determine the antiinfective properties of these promising lead structures on the level of the metabolome of different microorganisms. Metabolome measurements together with bioinformatic models provide information about the possible mode of action. By using bioinformatic models one can predict changes in metabolic fluxes caused by pharmacologically active substances. The integration of data from metabolic measurements can optimize the predictive power of these models. For these measurements the microorganisms were incubated with the active IQs (GB-AP-143 for S. aureus and C. albicans, GB-AP-304 for L. major). In the case of C. albicans sampling was carried out at different time points (lag-, log and stationary growth stage) in order to examine the time dependence. In addition cell cultures without inhibitor and with the addition of the solvent DMSO were used as controls for C. albicans. Initially, extraction methods for the respective metabolites of the microorganisms S. aureus, C. albicans and L. major were established. Since bioinformatic models predicted alterations especially in the purine and pyrimidine metabolism of these microorganisms as a consequence of treatment with IQs, priority was put on the extraction of polar compounds. To analyze the nucleotide metabolism an ion pair chromatography method was developed and optimized. By means of this method nicotinamide derivatives and nucleotides of the purine and pyrimidine metabolisms could be quantified in cell extracts of S. aureus, C. albicans and L. major. For a more holistic analysis of GB-AP-143´s effect on the composition of the C. albicans metabolome a GC/MS-method was developed. After a derivatisation step of the cell extract by using methoxyamine hydrochloride and MSTFA target and fingerprint analysis were conducted simultaneously. Target analysis was conducted by means of the NIST database and measuring reference standards. Particularly, amino acids could be quantified. Fingerprint analysis was interpreted using multivariate statistics. A detailed biological interpretation of metabolome data was not the focus of this study, because the main goal was the method development. However, data of S. aureus and L. major treated with the IQs gave hints towards an effect of the IQs on complex I of mitochondrial respiration. For the treatment of C. albicans with GB-AP-143 a complex alteration of the metabolites has been detected: already the time of sampling and the solvent, which was applied for GB-AP-143, have an impact on metabolome pattern of C. albicans. Additionally, the nucleotide and amino acid concentrations of fluconazol-resistant C. albicans mutants (TAC; UPC and MRR) have been investigated. Nucleotides showed increased as well as decreased concentrations compared to the C. albicans wild type. The overall concentration of amino acids was decreased in the mutants. Since GB-AP-143 also showed activity against these resistant mutants, exemplarily the MRR-mutant was incubated with this compound in order to determine, whether the effect of GB-AP-143 on the nucleotide and amino acid metabolism in the wild type also occurs in the mutant. Nucleotide metabolism showed antidromic effects for the incubation of wild type and mutant for GB-AP-143. This indicates that the metabolism of the mutant, which differs from the wild type already without treatment, also reacts differently on GB-AP-143-incubation. Data from HPLC/UV- and GC/MS-analysis are used by the bioinformatics to optimize the developed models in order to develop improved models for the mode of action of IQs. Since cytochrome-P-450-enzymes are involved in the metabolism of about 95 % of all drugs, the effects of selected IQs on the six main drug processing enzymes (CYP1A2, 2C8, 2C9, 2C19, 2D6 and 3A4) were investigated. Therefore, a previously developed and well-established in vitro test system was used. Three of the tested IQs showed an inhibition of CYP2D6. The distinct CYP2D6-selective inhibition of GB-AP-110 showed an IC50 value as low as 109 nM. The accurate characterization revealed a reversible and competitive mode of inhibition.
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Vývoj separačních metod pro stanovení perfluoralkylových karboxylových kyselin ve vzorcích životního prostředí / Development of separation methods for determination of perfluoroalkyl carboxylic acids in envirnonmental samples

Dufková, Veronika January 2012 (has links)
A complete, sensitive and selective procedure was developed for gas chromatographic determination of perfluoroalkyl carboxylic acids (PFCAs, C5 - C12) in river water samples. A rapid and simple derivatization procedure was developed and optimized at first, using isobutyl chloroformate (IBCF) to convert the acids into the more volatile isobutyl esters. The second task was to find the most suitable stationary phase for separation of perfluoroalkyl carboxylic acids by GC. The retention characteristics of PFCA isobutyl esters were measured and compared on 9 different stationary phases. The physical-chemical parameters of analyte interactions with stationary phase were monitored on selected column Rtx-200MS, and these parameters were compared with a non-fluorinated homologue - octanoic acid. A sensitive GC-MS system was used with negative chemical ionization, which is suitable for the selected type of fluorinated analytes. The developed method exhibits very low limits of detection and determination of PFCA isobutyl esters: 0.05 - 9.7 ng mL-1 (LOD) and 0.16 - 32.2 ng mL-1 (LOQ). An optimum pre-concentration technique was found for real water samples, where SPE SupelTM-Select HLB cartridges were used. In these cartridges, PFCAs were captured as ion- pairs with enrichment factor of 400. The recoveries of...
419

Desenvolvimento e validação de metodologia para determinação multirresíduo de glifosato e AMPA via CG-EM em amostras ambientais / Development and validation of methodology for multiresidue determination of glyphosate and AMPA via GC-MS in environmental samples

Benetti, Fernanda 13 April 2011 (has links)
O glifosato é o herbicida mais usado em todo o mundo. Sendo assim, é necessário que se tenham programas de monitoramento do seu uso, para garantir o bem estar da lavoura e da população. O seu metabólito principal é o ácido aminometilfosfônico (AMPA) que apesar de possuir baixa toxicidade, é mais persistente que o glifosato. O presente trabalho teve como objetivo desenvolver uma metodologia de análise para o glifosato e o AMPA por cromatografia gasosa acoplada à espectrometria de massas (CG/EM), a fim de avaliar possíveis contaminações em amostras ambientais nas imediações do Rio Monjolinho, em São Carlos. Para a faixa estudada (1,0 ug L-1 a 500 ug L-1, os limites de detecção e quantificação para o AMPA foram de 0,15 e 0,45 ug L-1 e para o glifosato, 0,67 e 2,02 ug L-1. As recuperações em água variaram entre 96,2 e 121% e para solo 70,1 a 119%. O método proposto apresentou boa linearidade, exatidão, seletividade e sensibilidade. A robustez foi avaliada de acordo com o teste de Youden. O procedimento de extração foi baseado em reações ácido-base e realizou-se etapa de clean-up para água e sedimento. Para os pontos amostrados, houve resíduo de AMPA em dois pontos (4,19 e 6,22 ug L-1). Os resultados encontrados para DBO foram altos, estando acima do limite estabelecido para um corpo d\'água Classe 3, de acordo com a CONAMA 357. Isso pode ter ocorrido devido à grande quantidade de esgoto despejado no leito do rio. Os valores de nitrogênio e fósforo também estão elevados, o que indica uma alta eutrofização do leito do rio. Vale ressaltar a necessidade de se ter uma legislação que estabeleça um limite máximo permitido para o AMPA, visto que ele é mais persistente no ambiente do que o glifosato. / The glyphosate is the most widely used herbicide worldwide. Therefore, it is necessary to have programs for monitoring their use to ensure the welfare of the farming and population. Its main metabolite is the acid aminomethylphosphonic (AMPA) that despite having low toxicity, is more persistent than glyphosate. This study aimed to develop a methodology for analyzing glyphosate and AMPA by gas chromatography coupled to mass spectrometry (GC/MS) in order to assess possible contamination of samples environment in the vicinity of Monjolinho River in São Carlos. In the range studied (1.0 ug L-1 to 500 ug L-1, limits of detection and quantification were 0.15 and 0.45 ug L-1 for AMPA and 0.67 and 2.02 ug L-1 for glyphosate. The recoveries in water varied between 96.2 and 121% and for soil from 70.1 to 119%. The proposed method showed good linearity, accuracy, selectivity and sensitivity. The robustness was evaluated according to the Youden test. The extraction procedure was based on acid-base reactions and included a clean-up step for water and sediment. For the sampling sites, it was determined residual AMPA at two points (4.19 and 6.22 ug L-1). The results for BOD were high, being above the limit set for a waterbody Class 3, according to CONAMA 357. This may be due to large amount of sewage dumped into the river bed. The values of nitrogen and phosphorus are also high, which indicates a high eutrophication of the bed river. It is worth emphasizing the need of having a legislation that establishes a maximum allowed value for AMPA, whereas it is more persistent in environment than glyphosate.
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Kärlanvändning i urban miljö under vikingatid : Lipidanalys av keramik från Birka med GC-MS

Werner, Sara January 2018 (has links)
An analysis of 6 ceramic shards from the Viking Age town Birka was performed by use of Gas Chromatography-Mass Spectrometry. A new interpretation of a previously analyzed material, was performed by analyzing the raw data from 18 ceramic shards. The total of 26 ceramic shards will together form a material base that is used to study the vascular use in an urban environment from the Viking Age. The result of the analysis is used to compare five different parts of Birka with each other, in order to investigate whether there are differences or similarities in pottery use. The results show that residues of animals are most common in all premises. It is also possible to note that fish have been cooked both in the Garnison area and at Stadsvallen.

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