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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.
161

Estudo da participação de 2-integrina nas atividades fagocítica e microbicida de macrófagos alveolares e peritoneais na histoplasmose / Study of Participation of 2-integrin in the Phagocytic and Microbicidal Activities of Alveolar and Peritoneal Macrophages in the Histoplasmosis

Soares, Elyara Maria 10 August 2009 (has links)
O Histoplasma capsulatum (H.capsulatum) é um fungo dimórfico patogênico e responsável por graves lesões pulmonares, as quais se caracterizam pelo acúmulo de leucócitos ao redor do fungo, resultando na formação de granulomas. A infecção ocorre principalmente pela inalação de conídios ou pequenos fragmentos de micélio que alcançam os alvéolos, onde se transformam em leveduras, que é a forma patogênica do fungo. Na resposta imune do hospedeiro, as integrinas participam nos mecanismos fagocíticos, essenciais na resposta à histoplasmose. As 2integrinas contêm uma cadeia 2, também conhecida como CD18, comum a várias moléculas de adesão, e uma cadeia variável. Até o momento foram identificadas quatro cadeias distintas: L, a qual forma o dímero L2, também conhecido como LFA-1 (do inglês leukocyte function antigen-1) ou CD11aCD18; m, formando m2, chamado Mac-1 (do inglês macrophage differentiation antigen 1) ou CR3 (do inglês complement receptor 3) ou CD11bCD18; x, formando x2, CD11cCD18, gp150, 95 ou CR4 (do inglês complement receptor 4) e a cadeia d, formando d2, CD11dCD18. Neste trabalho, investigamos o papel da molécula CD18 em macrófagos alveolares (MAs) e macrófagos peritoneais (MPs) nas funções efetoras contra H. capsulatum e a relação do leucotrieno B4 (LTB4) nestas respostas. Inicialmente confirmamos que MAs e MPs provenientes dos animais CD18low, expressam baixa porcentagem de CD11bCD18 (CR3). Demonstramos que, como esperado, MAs e MPs de ambos os grupos fagocitam mais leveduras opsonizadas com complemento do que não opsonizadas. Surpreendentemente, MAs de animais CD18low fagocitam 136% mais leveduras opsonizadas do que MAs de C57BL/6. Também, MPs destes animais fagocitam aproximadamente 240% mais leveduras quando infectados com H. capsulatum e opsonizados, quando comparados aos MPs de C57BL/6. A adição de LTB4 aumenta a atividade fagocítica em 520% por MAs de animais C57BL/6 e 200% por MAs de CD18low, enquanto que a adição de LTB4 aumentou a fagocitose dos MPs de animais C57BL/6 em 600% vezes quando comparado aos MPs de CD18low. Este fenômeno foi inibido pela pré-incubação destas células com antagonista específico do receptor BLT1 apenas em animais C57BL/6. A adição de LTB4 na cultura de MPs reduziu a porcentagem de morte das leveduras apenas nos animais C57BL/6. Os animais CD18low produzem espontaneamente mais LTB4 e apresentaram um grande aumento na produção de óxido nítrico quando comparados aos animais C57BL/6. Pacientes acometidos pela Doença Granulomatosa Crônica (DGC) possuem deficiência congênita da molécula CD18. Células fagocíticas isoladas do sangue periférico de pacientes com DGC foram incubadas com leveduras opsonizadas e assim como macrófagos de animais deficientes de CD18, fagocitam mais leveduras opsonizadas (900%) ou não (300%), quando comparado com células de indivíduos sadios. Sugerimos que a molécula CD18 tem importante participação nos mecanismos efetores da imunidade inata, por mecanismo dependente de mediadores lipídicos, como o LTB4, no controle dos mecanismos de defesa contra H. capsulatum. / Histoplasma capsulatum (H. capsulatum) is a pathogenic dimorphic fungus and its infection is characterized by accumulation of leukocytes and granuloma formation. Infection occurs mainly by fungal inhalation that reaches the alveoli, which became yeast (the pathogenic form). in the immune response of host, integrins participate in phagocytic mechanisms, fundamental in the response against histoplasmosis.,8^2-integrin has a 02 chain known as CD18, usual to many adhesion molecules, and a variable a chain. Until the moment, it was identified four variable a chains: aL, that constitutes the dimer aL,82, also known as LFA-1 (leukocyte function antigen) or CD11aCD18; am forming the a^m,B^2 or Mac-1 (macrophage differentiation antigen 1) and CR3 (complement receptor 3) and CD11bCD18; ax, constituting the dimer Able CD11cCD18, gp150, 95 or CR4 (complement receptor 4) and ad chain, that constitutes a^d,8^2, CD11dCD18. In the present study, we sought to investigate the effect of CD18 in alveolar (AMs) and peritoneal macrophages (PMs) effecter functions against H. capsulatum and the relation of LTB^4 in those responses. We confirm that AMs and PMs of CD18\'°^W mice have low expression of ,32-integrin compared to wild type mice (WT). We demonstrate that, as expected, AMs and PMs from WT and CD18\'°^W, phagocytosed more complement (C)-opsonized yeasts than the unopsonized yeasts. Surprisingly, AMs from CD18\'°^Wmice phagocytosed 136% more (C)-opsonized yeasts than AMs obtained from WT. Also, PMs of CD18^b°^W mice phagocytosed 240% more (C)-opsonized yeasts than PMs of WT. The addition of LTB^4, increases the phagocytic activity by AMs of WT mice in 520% and by AMs from CD18\'°^W mice in 200%, while the addition of LTB^4 only increased the phagocytosis of C-opsonized H. capsulatum by PMs of C57BL/6 mice in 600%, when compaired with PMs from CD18\'°^W mice. This phenomenon was inhibited by pretreatment of these cells with an especific BLT1 receptor antagonist only in PMs from C57BU6 mice. The addition of LTB^4 in the culture of MPs reduced the percentage of death of yeasts in animals C57BL/6. CD18\'°^W mice, spontaneously produce more LTB^4 and showed a large increase in the production of nitric oxide when compared to C57BU6. Patients affected by Chronic Granulomatous Disease (DGC) have congenital deficiency of the CD18 molecule. Phagocytic cells isolated from peripheral blood of patients with DGC were incubated with C-opsonized yeasts and as well as macrophages from CD18\'°^W, phagocytosed more C-opsonized yeasts (900%) or not (300%) when compared with cells from healthy individuals.Therefore, we suggest that the CD18 molecule has important participation in the effector mechanisms of innate immunity, a mechanism dependent on lipid mediators such as LTB^4, to control these mechanisms in defense against H. capsulatum.
162

Molecular investigation of type 2 diabetes. / CUHK electronic theses & dissertations collection

January 2000 (has links)
Yang Tao. / "November 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 136-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
163

Time resolved crystallographic studies

Schiffers, Stefanie January 2010 (has links)
X-ray crystallography is an important analytical method for the characterisation of materials in the solid state. During the last decade, it has become important as a tool in the new field of photocrystallography. This combines both crystallography and photochemistry and is used to monitor the formation of light-induced metastable and transient species, so that structural information can be obtained during the change of a material. This is an important area of research as solid state chemistry can display new phenomena and reveal properties that are not possible in solution. Chapter 1 of this thesis commences with a brief introduction to the different methods used to achieve and measure the excitation within crystalline compounds, while Chapter 2 contains an introduction into diffraction methods. In Chapters 3-5 new photocrystallographic studies were performed on two series of compounds. The first one consists of a systematic study on metal complexes with different pyridylethylene ligands. The focus was to align complexes in the solid state so that they can undergo photo induced cycloaddition reactions. These solid state reactions are important as they present “green synthetic chemistry”. The second study involves the photoinduced linkage isomerisation of [Ni(L)2(NO2)2] complexes. Structural characterisation shows that the NO2 ligands change their coordination mode when irradiated with light of different wavelengths. Conditions for the metastable isomerisation were optimised by altering temperature and wavelengths. In Chapters 6 and 7 a systematic study of structural changes in a series of lanthanide complexes and their use as triboluminescence materials, is described. The proposed mechanism of triboluminescence for these complexes is discussed. To summarise, in this thesis, systematic investigations have been carried out in different aspects of crystallography using appropriate series of compounds. The nature of and the conditions required for the change to occur within the solid state have been established.
164

Identification and characterisation of the role of cyclooxygenase-2 (COX-2) in cancer stem cell biology : a comparative study

Hurst, Emma Allan January 2017 (has links)
Cancer is a stem cell disease and populations of cancer stem cells (CSCs) are evident in many cancer types. CSCs exhibit similarities to normal embryonic and adult stem cells: they are able to self-renew and have the potential to give rise to a diverse array of differentiated progeny. CSCs are responsible for driving tumourigenesis and metastasis, and are inherently resistant to chemotherapy and radiotherapy. This cell population is enriched after treatment and, as a result of their tumourigenic capability, can re-populate tumour growth resulting in patient relapse, often with increased chemotherapeutic resistance. Increasing evidence supports that only by targeting this population of cells will a cure for cancer be possible. Hence, it is essential to identify pathways within CSC populations that can be targeted therapeutically. Cyclooxygenase-2 (COX-2) is an enzyme associated with inflammation and disease, and is upregulated in many cancers types. The COX-2 / prostaglandin E2 (PGE2) signalling pathway is associated with increased tumour growth, metastasis, immune evasion and overall worse patient prognosis. Recent evidence has identified that COX-2 is further upregulated in CSC populations isolated from cancer cell lines. Previously, we have shown that inhibition of COX-2 reduces CSC sphere-forming ability, a characteristic of stem cell self-renewal, suggesting a role for COX-2 in maintaining CSC populations. This work was carried out in both human and canine osteosarcoma cell lines with similar results. Cancer in dogs is a major health concern among an aging pet population. Many cancer types exhibit similarities between these species, suggesting that naturally occurring canine cancer may be a potential model for the human disease. The aim of this PhD project was to investigate the role of COX-2 in CSCs in a comparative cancer study. CSCs that express stem cell markers have been isolated from a panel of canine and human cancer cell lines including, mammary carcinoma and transitional cell carcinoma of the urinary bladder. CSCs over-express COX-2 compared to non-CSCs, therefore to determine the role of COX-2 in CSC biology the selective COX-2 inhibitor mavacoxib, a non-steroidal anti-inflammatory drug currently licenced for treating osteoarthritis in dogs, was utilised. Our results demonstrate that inhibiting COX-2 has a multifaceted impact on CSC biology, including reducing self-renewal capacity, clonogenicity, proliferation, migration, invasion and in vivo tumourigenicity. To confirm that mavacoxib is mediating these CSC-specific effects via inhibition of COX-2 rather than through unknown off-target effects, we generated canine specific-small interfering RNA to specifically reduce gene expression of COX-2. Our results confirm that mavacoxib exerts its anti-tumour effects via inhibition of COX-2. This project has highlighted a plethora of CSC-specific COX-2 effects, and to gain further insight we compared the global gene expression profiles of CSCs compared to non- CSCs isolated from a canine bladder carcinoma cell line. This data revealed that both mavacoxib and COX-2 specific siRNA target similar pathways within the two cell populations, confirming that mavacoxib exerts its effects in a COX-2 dependent manner. Interestingly, mavacoxib reduced the expression of a number of stemness related genes in the CSC population, including NOTCH and Wnt, suggesting that mavacoxib can inhibit CSC related pathways. Our overall results are comparable between canine and human cancer cell lines supporting the concept of naturally occurring tumours in dogs as models for the human disease. In conclusion, COX-2 plays an important role not only in maintaining CSC populations but also in their function, and targeting COX-2 in CSCs may provide therapeutic benefit.
165

Stress corrosion cracking of Zircaloy in the prescence of iodine

Knorr, David Bruce January 1981 (has links)
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by David Bruce Knorr. / Sc.D.
166

Investigations into Group J herbicide resistance in Nasella trichotoma and Sporobolus fertilis and biological control of S.fertilis using the pathogen Nigrospora oryzae

Mathisa Thevar Ramasamy Thevar, Sethu Raja Durai, s3085094@student.rmit.edu.au January 2008 (has links)
Serrated tussock (Nassella trichotoma) and Giant Parramatta Grass (Sporobolus fertilis) are among the most noxious weeds in Australia. Both cause problems in pasture and there are limited control measures relying heavily on the herbicide flupropanate. With the recent confirmation of flupropanate resistance in serrated tussock and the report of suspected flupropanate resistance in Giant Parramatta Grass (GPG), this option appeared to be under threat.The aims of this thesis were to determine the extent of flupropanate resistance in serrated tussock and GPG in Australia and to understand the genetics of flupropanate resistance in serrated tussock. This thesis also documents the GPG resistance to 2,2-DPA and investigates a fungal pathogen, Nigrospora oryzae, as a potential biocontrol agent for GPG. A local paddock survey determined the spread and extent of flupropanate resistance in serrated tussock within 5 km of the original resistant site. The pot-dose method of assessing resistance identified plants resistant to flupropanate up to 3.5 km from the original site found in Victoria. Seeds from these plants showed 0-100% resistance, with sensitive plants often having a low („T5%) level of resistant seed. These results indicate the movement of flupropanate resistance through seeds or pollen and shows that its spread occurred within one year of detection. A national mail survey confirmed the massive impacts of serrated tussock across Australia, with annual serrated tussock costs ranging from $15,000 to $16,000 per year per respondent. This survey also identified the widespread infestation of this weed in a variety of land use patterns, from pasture to native grasslands, and the decrease in the value of farmland as a result. Heritability studies using controlled breeding experiments indicated a strong involvement of a maternal component in the inheritance of flupropanate resistance in serrated tussock, with a minor proportion of resistance heritable through pollen. GPG plants and seedlings were tested for flupropanate and 2,2-DPA resistance.Seedlings tested for flupropanate resistance were highly resistant (tolerating 33-39 times more than sensitive biotypes). With 2,2-DPA, resistant GPG plants did not die even at 14 times the field rate and resistant seedlings also showed 5-6 times more resistance than the sensitive biotype. The study has confirmed that flupropanate and 2,2-DPA resistance now exists in GPG.The potential of Nigrospora oryzae, a pathogenic fungus, as a biocontrol agent for GPG was determined. Mature plants and seedlings of GPG were inoculated with conidia of N. oryzae using three treatments (run-off, crown, and spray). Inoculated plants were smaller, with greater proportions of dead leaves (70% with the run-off a nd crown treatments and 53% with the spray treatment) than the control plants. GPG seedlings inoculated with N. oryzae were stunted and showed greater proportions of necrotic leaves in all the treatments than the control. There is potential to develop N. oryzae as a mycoherbicide to control GPG and further testing is warranted.
167

Läromedel + Nationella prov = Sant...Eller? : en studie av ett läromedels anpassning till nationella provet i svenska för årskurs tre

Zetterström, Anneli January 2009 (has links)
<p>Vilka läromedel är bra och vilka är mindre bra? Som lärare, och kanske speciellt som nyutexaminerad lärare är det inte det lättaste att skilja agnarna från vetet. I denna uppsats har jag valt att kritiskt granska läromedlet <em>Språkdax 2 </em>och närmare bestämt beståndsdelarna <em>Läsdax 2, Skrivdax 2 </em>och dess lärarhandledning, <em>Lärardax 2</em>. Jag har tagit reda på om detta läromedel i svenska förbereder eleverna för att de ska klara nationella provet i årskurs tre.</p><p> </p><p>Eftersom nationella prov i årskurs tre ännu bara genomförts som testomgång och därmed är väldigt nytt, tar även detta en stor del i uppsatsen. Jag har jämfört bland annat likheter och skillnader mellan läromedlet och provet, avvägningen mellan text och bild etcetera. För att ta reda på detta har jag intervjuat provkonstruktören för nationella provet i årskurs tre i grundskolan som också försett mig med provmaterialet som jag sedan satt mig in i.</p><p> </p><p>Lärarhandledningen utlovar att läromedlet arbetar mot kursplanernas mål i svenska för årskurs tre, som också är de mål som prövas i nationella provet. Resultatet visar att eleverna får öva på och arbeta med alla mål som prövas i det nationella provet för årskurs tre i grundskolan. Men eleverna kan gå miste om kunskap som prövas i det nationella provet om exempelvis läraren inte följer läromedlets handledning eller väljer bort vissa delar i den. Samtidigt kanske läraren tillgodoser eleverna med denna kunskap på annat sätt.</p>
168

Dihydropyridinones et Pyrrolones : précurseurs potentiels de gamma aminoacides cyclobutaniques

Gaucher, Xavier 17 June 2011 (has links) (PDF)
Dans ce mémoire, nous étudions deux voies d'accès possibles à des analogues cyclobutaniques du GABA. Les deux voies que nous explorons font appel à des photocycloadditions de l'éthylène sur des dihydropyridinones ou bien sur des pyrrolones. Dans le premier chapitre constituant l'introduction, nous évoquerons la place des aminoacides dans la chimie peptidomimétique. Après une brève description des structures primaire, secondaire et tertiaire des enchaînements d'aminoacides, nous étudierons plus particulièrement les oligomères dans lesquels la structure primaire comporte une contrainte apportée par un cycle dans la chaîne principale. Dans le deuxième chapitre, nous présenterons notre stratégie de synthèse des dihydropyridinones à partir des azabicyclo[3.1.0]hexanols. Puis, pour obtenir un plus large éventail de dihydropyridinones, nous étudierons la faisabilité de notre méthode pour la synthèse de dihydropyridinones N-α'-substituées. Dans le troisième chapitre, nous développerons les réactivités particulières des dihydropyridinones d'une part, en milieu oxydant et d'autre part en photochimie et nous en conclurons que la dihydropyridinone issue de la phénylglycine ne constitue par un bon précurseur pour les réactions de photocycoloadditions [2+2]. Dans le quatrième chapitre, nous avons synthétisé des pyrrolones γ-substituées comme substrats alternatifs dans les réactions de photocycloaddition [2+2] avec l'éthylène. Les acides aminés naturels (L-Alanine, L-Valine, L-Leucine, L-Sérine, L-Phénylglycine, L-Phénylalanine) ont été utilisés pour préparer ces différentes pyrrolones. Dans le cinquième chapitre, nous avons donc effectué les photocycloadditions [2+2] de l'éthylène sur ces pyrrolones. Nous avons obtenu les bicyclo[4.2.0]heptanes correspondant dans la plupart des cas. Ces composés pourraient constituer des précurseurs de dérivés cyclobutaniques du GABA.
169

Läromedel + Nationella prov = Sant...Eller? : en studie av ett läromedels anpassning till nationella provet i svenska för årskurs tre

Zetterström, Anneli January 2009 (has links)
Vilka läromedel är bra och vilka är mindre bra? Som lärare, och kanske speciellt som nyutexaminerad lärare är det inte det lättaste att skilja agnarna från vetet. I denna uppsats har jag valt att kritiskt granska läromedlet Språkdax 2 och närmare bestämt beståndsdelarna Läsdax 2, Skrivdax 2 och dess lärarhandledning, Lärardax 2. Jag har tagit reda på om detta läromedel i svenska förbereder eleverna för att de ska klara nationella provet i årskurs tre.   Eftersom nationella prov i årskurs tre ännu bara genomförts som testomgång och därmed är väldigt nytt, tar även detta en stor del i uppsatsen. Jag har jämfört bland annat likheter och skillnader mellan läromedlet och provet, avvägningen mellan text och bild etcetera. För att ta reda på detta har jag intervjuat provkonstruktören för nationella provet i årskurs tre i grundskolan som också försett mig med provmaterialet som jag sedan satt mig in i.   Lärarhandledningen utlovar att läromedlet arbetar mot kursplanernas mål i svenska för årskurs tre, som också är de mål som prövas i nationella provet. Resultatet visar att eleverna får öva på och arbeta med alla mål som prövas i det nationella provet för årskurs tre i grundskolan. Men eleverna kan gå miste om kunskap som prövas i det nationella provet om exempelvis läraren inte följer läromedlets handledning eller väljer bort vissa delar i den. Samtidigt kanske läraren tillgodoser eleverna med denna kunskap på annat sätt.
170

Synthesis of substituted Ring-Fused 2-Pyridones and applications in chemical biology

Bengtsson, Christoffer January 2013 (has links)
Antibiotics have been extensively used to treat bacterial infections since Alexander Fleming’s discovery of penicillin 1928. Disease causing microbes that have become resistant to antibiotic drug therapy are an increasing public health problem. According to the world health organization (WHO) there are about 440 000 new cases of multidrug-resistant tuberculosis emerging annually, causing at least 150 000 deaths. Consequently there is an immense need to develop new types of compounds with new modes of action for the treatment of bacterial infections. Presented herein is a class of antibacterial ring-fused 2-pyridones, which exhibit inhibitory effects against both the pili assembly system in uropathogenic Escherichia coli (UPEC), named the chaperone usher pathway, as well as polymerization of the major curli subunit protein CsgA, into a functional amyloid fibre. A pilus is an organelle that is vital for the bacteria to adhere to and infect host cells, as well as establish biofilms. Inhibition of the chaperone usher pathway disables the pili assembly machinery, and consequently renders the bacteria avirulent. The focus of this work has been to develop synthetic strategies to more efficiently alter the substitution pattern of the aforementioned ring-fused 2-pyridones. In addition, asymmetric routes to enantiomerically enriched key compounds and routes to compounds containing BODIPY and coumarin fluorophores as tools to study bacterial virulence mechanisms have been developed. Several of the new compounds have successfully been evaluated as antibacterial agents. In parallel with this research, manipulations of the core structure to create new heterocycle based central fragments for applications in medicinal chemistry have also been performed.

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